Is action at a distance possible as envisaged by the EPR Paradox. [Archive]

DevilsAvocado

Apr19-10, 07:07 PM

... Anyways if we allow the possibility that unfair sampling is justified assumption then Aspect experiment demonstrates that photon ensembles can have QM type properties that individual photons can't have. And finding that out wouldn't seem like waste of time and money.

With all due respect, this is almost an even worse insult to Alain Aspect...

Would a member of the French Academy of Sciences and French Academy of Technologies, and professor at the Ecole Polytechnique, awarded with 2010 Wolf Prize in physics, spend all this time & money to find out that the detection efficiency is always less than 100% in optical experiments...!?

A high school student can figure this out by asking his teacher... :bugeye:

This is not a sound debate. To me, it seems like a classical example of "not seeing the forest for the trees"... among some.
This is not a question whether we can trust physical experiments involving photons; it’s a much bigger question.

Let’s take a step back - To clarify the background
(for pallidin et al.)
Albert Einstein was not perfectly happy with the non-causal nature of the new quantum physics, and he had an ongoing debate with Niels Bohr about this matter. Both were Nobel Laureates in Physics, and considered the brightest minds of their time (and history!).

To keep it short: Einstein favored 'real' particles like photons – Bohr was only interested in the wave function, or to be precise, the equations describing wave function.

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Niels_Bohr_Albert_Einstein_by_Ehrenfest.jpg/300px-Niels_Bohr_Albert_Einstein_by_Ehrenfest.jpg

In 1935, Albert Einstein published a paper, known as the EPR paradox, with the title; "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". So far Niels Bohr, almost in triumph, had dismantled every argument from Einstein swift and easy. But this time it was different, Bohr’s reply was published five months later (with the exact same title as the original), and the paper implied he had misinterpreted the profound analysis of Einstein.

http://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Eprheaders.gif/700px-Eprheaders.gif

According to Einstein the EPR experiment yields a dichotomy, either:
1) A quantum system has a non-local effect on the physical reality.
2) Quantum mechanics is incomplete in the sense that some extra variable is needed to account for it.

In 1964, John Bell showed (theoretically) that quantum mechanics predicts much stronger statistical correlations between the measurement results, than the theory of hidden variable is ever capable of.

Bell's theorem proves that every quantum theory must violate either locality or counterfactual definiteness (i.e. Heisenberg uncertainty principle; one cannot simultaneously know the position and momentum of a particle).

To make things even more 'contradictory' – we know that quantum mechanics and the predictions of quantum field theory (QFT) are the most precise in all of physics!

John Bell knew that there where theoretical escape routes from his theorem, e.g. Superdeterminism in which we (and the particles) lose our free will by the predetermined laws of physics, and become 18th century Laplace's demons.

And as discussed here, there are other interpretations of QM, like Many-worlds (MWI) where we split the whole universe for every particle in EPR, etc.

Now, with this in mind, it seems almost silly with all this focus on photons!? The brightest minds in history knew that EPR was an important and profound aspect of quantum mechanics.

And we are discussing unfair or fair sampling assumption of photons!?!?

Well, that approach to EPR is certainly unfair to all the effort that has been made by a lot of very intelligent people, in nearly a century.

But, as I mentioned earlier, there are different kind of Bell test experiments performed – and to quit the discussion about 'unfair sampling', once and for all, we can point out the fact that in 2001 M. Rowe et al. conducted an experiment that used detection methods that were almost 100% efficient, thus avoiding the 'unfair sampling loophole', using two trapped ions:

Nature – Experimental violation of a Bell's inequality with efficient detection (http://www.nature.com/nature/journal/v409/n6822/abs/409791a0.html)

Fair sampling is a reasonable assumption and is therefore not a loophole.

Time to rethink.

"It is difficult for me to believe that quantum mechanics, working very well for currently practical set-ups, will nevertheless fail badly with improvements in counter efficiency ..." -- J.S. Bell

Frame Dragger

Apr19-10, 07:23 PM

Many in the foundations community believe attempts to interpret quantum physics are a good way to look for a theory to complete quantum physics. For example, what makes you believe there's something relevant to completing quantum physics "at and below the Planck Scale?" You must have some implicit metaphysical "interpretation" of quantum physics that suggests the importance of this scale.

You are diverting my point, by raising another. Tit for Tat RUTA... "A cat for a hat, or a hat for a cat, but nothing for nothing."

As for the rest, why do you feel I have a metaphysical interpretation? I don't see that as a logical conclusion from the standpoint of wanting to see the two major theories of physics AGREE (i.e. GR/QM). As for believing that interpeting QM will lead to breakthroughs... I'm yet to see that. It DOES provide people with something to say other than, "we don't know"... a notoriously bad phrase to place in a grant request. Please don't assume what I "must" or must not believe.

DevilsAvocado

Apr19-10, 07:45 PM

the standpoint of wanting to see the two major theories of physics AGREE (i.e. GR/QM)
YES! That 'gang' is definitely on my supporter-list! :biggrin:

Frame Dragger

Apr19-10, 07:49 PM

YES! That 'gang' is definitely on my supporter-list! :biggrin:

Heh, thanks DA. :smile: I always was under the impression that, while it seems to always be an elusive goal, that having these two amazingly useful and predictive theories NOT dovetailing is... unacceptable. Perhaps that would be my "metaphysical" reason for wanting to understand the Planck scale...

Btw, great last post!

DevilsAvocado

Apr19-10, 08:01 PM

Heh, thanks DA. :smile: I always was under the impression that, while it seems to always be an elusive goal, that having these two amazingly useful and predictive theories NOT dovetailing is... unacceptable. Perhaps that would be my "metaphysical" reason for wanting to understand the Planck scale...
Well, as we all know – It takes two to tango!
And it’s not always that bad move your a*s around in space-time to see what we’ll find! :biggrin:
Btw, great last post!
Thanks!

hmm.max

Apr19-10, 09:04 PM

I would add, Thomas, that a thread such as you describe exists... you were in it, and I believe you and DrChinese et al couldn't come to an agreement. If we're going to continue that discussion, lets, but starting from square one seems silly.

As a reader of this thread, I would personally rather that ThomasT wasn't discouraged from participating in the conversation. As someone trying to understand the current state of affairs with "hidden variable theories", his comments were the only part of this thread that peaked my interest, i.e. the only statements that I had not already come across numerous times on this forum already.

Obviously, everything in this thread has already been discussed elsewhere. It seems very strange to me to suddenly single out someone who is drawing a very subtle distinction, and tell them to stop, in the midst of advanced discourse such as

"Are you saying that John Bell was totally wrong, and Alain Aspect was totally stupid.."

Not trying to be inflammatory, I just mean that this thread doesn't seem so sacred that shutting someone up is warranted.

zonde

Apr20-10, 06:13 AM

Now, with this in mind, it seems almost silly with all this focus on photons!? The brightest minds in history knew that EPR was an important and profound aspect of quantum mechanics.

And we are discussing unfair or fair sampling assumption of photons!?!?

Well, that approach to EPR is certainly unfair to all the effort that has been made by a lot of very intelligent people, in nearly a century.
This is unfair in respect to Many-worlds interpretation, right?
MWI is so exciting and how can it be compared with something as dull as unfair sampling.
But bear in mind that success of QM is actually success of "shut up and calculate" interpretation and the closest interpretation to this approach is Ensemble interpretation.

But, as I mentioned earlier, there are different kind of Bell test experiments performed – and to quit the discussion about 'unfair sampling', once and for all, we can point out the fact that in 2001 M. Rowe et al. conducted an experiment that used detection methods that were almost 100% efficient, thus avoiding the 'unfair sampling loophole', using two trapped ions:

Nature – Experimental violation of a Bell's inequality with efficient detection (http://www.nature.com/nature/journal/v409/n6822/abs/409791a0.html)
To consider this experiment as an EPR paradox test is a bit of stretch. EPR paradox considers separate measurements of two systems that are not interacting at the moment of measurement. But in this experiment there is only one joined measurement of both systems.

Fair sampling is a reasonable assumption and is therefore not a loophole.
Yes, in most cases fair sampling assumption is considered reasonable. But in this case fair sampling assumption necessarily comes packaged with one of the not-so-reasonable speculations like MWI, superdeterminism or nonlocality of Pilot-wave.
And in that light fair sampling is as reasonable as most reasonable one of those alternatives.

Time to rethink.
As you say

"It is difficult for me to believe that quantum mechanics, working very well for currently practical set-ups, will nevertheless fail badly with improvements in counter efficiency ..." -- J.S. Bell
When Bell said that? Definitely it was quite some time ago. And still there is uncomfortable lack of experiments that explicitly test what happens when counter efficiency is changed above usual ~10% level even when there is constant improvement in photon detection technologies.

DevilsAvocado

Apr20-10, 07:04 AM

Please hmm.max, you are commenting Frame Dragger, but quoting me...
I would personally rather that ThomasT wasn't discouraged from participating in the conversation.
I have never discouraged ThomasT from participating in the conversation, in fact the contrary:
Time will definitely tell – and I hope I’m free to have my own view in the meantime.
You are free to have yours.

As someone trying to understand the current state of affairs with "hidden variable theories", his comments were the only part of this thread that peaked my interest, i.e. the only statements that I had not already come across numerous times on this forum already.

I do think you have misinterpreted ThomasT, he does not support "hidden variable theories", but he replaces it with his own version of "entanglement" (as far as I understand):

It's important to keep in mind that the entanglement correlations in Bell tests have to do with the relationship between the entangled entities. This relationship isn't the same as the hidden variable. It's a hidden, constant parameter that's assumed (in the QM treatment as well) to have a local cause.

It seems very strange to me to suddenly single out someone who is drawing a very subtle distinction, and tell them to stop, in the midst of advanced discourse such as

"Are you saying that John Bell was totally wrong, and Alain Aspect was totally stupid.."
I’m afraid you’re mixing persons, quotes and arguments into an unrecognizable clutter. The quote above was from me addressed to zoned, and not to the very subtle drawings of ThomasT.

that shutting someone up is warranted.
Wrong, but I think Frame Dragger can speak for himself.

DrChinese

Apr20-10, 08:56 AM

As a reader of this thread, I would personally rather that ThomasT wasn't discouraged from participating in the conversation. As someone trying to understand the current state of affairs with "hidden variable theories", his comments were the only part of this thread that peaked my interest, i.e. the only statements that I had not already come across numerous times on this forum already.

I don't think anyone is trying to shut anyone up, but to be fair some of the discussion with ThomasT has been had multiple times previously. I for one don't want to repeat the exact same debate with the same person.

On the other hand: if you are interested in discussing any element of EPR/Bell, I am sure we would all be interested.

DrChinese

Apr20-10, 08:57 AM

Well, as we all know – It takes two to tango!
And it’s not always that bad move your a*s around in space-time to see what we’ll find! :biggrin:

Thanks!

Just adding to what was said already: you had some great posts above... good stuff. :smile:

DrChinese

Apr20-10, 09:02 AM

I do think you have misinterpreted ThomasT, he does not support "hidden variable theories", but he replaces it with his own version of "entanglement" (as far as I understand):

ThomasT has indicated previously that there are definitional issues with entanglement. I don't see those particular ones and neither do most folks. So it gets hard to have a discussion because his vewpoint hinders that. There is a generally accepted common ground to discuss these issues, and that usually goes all the way back to EPR.

Deepak Kapur

Apr20-10, 09:59 AM

ThomasT has indicated previously that there are definitional issues with entanglement. I don't see those particular ones and neither do most folks. So it gets hard to have a discussion because his vewpoint hinders that. There is a generally accepted common ground to discuss these issues, and that usually goes all the way back to EPR.

I think that the real issue is with the definition of 'Local Realism'.

'Local Realism' assumes (as I feel about it):

1. Certainity is inherent in all the objects of nature (big or small). They always tend to 'possess' properties if someone tries/does not try to measure them.

2. Things/objects that are great distances apart (say light years apart in case of our Earth or say 100 feet apart in case of sub atomic particles, no proportion intended) don't get affected by other entities (especially when it come to the measurement of their properties).

In other words if we conduct any kind of measurement related to Earth, the effect of a star (say that is in the farthest corner of Andromeda galaxy) will not have any effect on this measurement.

I have a faint inclination that 'this star' will certainly have an influence on our measurement related to Earth (however small this effect may be). If an instrument could be formed that is (hyper)n sensitive, we may be able to gauge the effect. And it would depend on the (refinement)n/nature of our measurement wheter we take this effect to be of any consequence or not.

Frame Dragger

Apr20-10, 10:55 AM

I think that the real issue is with the definition of 'Local Realism'.

'Local Realism' assumes (as I feel about it):

1. Certainity is inherent in all the objects of nature (big or small). They always tend to 'possess' properties if someone tries/does not try to measure them.

2. Things/objects that are great distances apart (say light years apart in case of our Earth or say 100 feet apart in case of sub atomic particles, no proportion intended) don't get affected by other entities (especially when it come to the measurement of their properties).

In other words if we conduct any kind of measurement related to Earth, the effect of a star (say that is in the farthest corner of Andromeda galaxy) will not have any effect on this measurement.

I have a faint inclination that 'this star' will certainly have an influence on our measurement related to Earth (however small this effect may be). If an instrument could be formed that is (hyper)n sensitive, we may be able to gauge the effect. And it would depend on the (refinement)n/nature of our measurement wheter we take this effect to be of any consequence or not.

That is a very long way of saying that you believe in Hidden Variables, but with the addition that you're speculating in a manner that has nothing to do with physics.

@hmm.max: I would respond, but DrChinese has done so quite nicely, as has DevilsAvocado.

DevilsAvocado

Apr20-10, 11:03 AM

Just adding to what was said already: you had some great posts above... good stuff. :smile:
Thanks a lot DrChinese! I’m fairly new here, but I do understand you are the 'grandmaster' of EPR here on PF; therefore I’m now feeling something like this... :cool: + :smile: + o:) + :blushing: + :approve:

Thanks! ;)

DevilsAvocado

Apr20-10, 11:05 AM

DrChinese

Apr20-10, 11:10 AM

'Local Realism' assumes (as I feel about it):

1. Certainity is inherent in all the objects of nature (big or small). They always tend to 'possess' properties if someone tries/does not try to measure them.
...

There are 4 closely related terms, sometimes used interchangeably, sometimes used in the specific:

a. Realism - a la EPR's "elements of reality".
b. Hidden Variables - Essentially a deduction from realism.
c. Non-contextuality - the context of an experiment does not matter to the realism of an observable.
d. Counterfactual Definiteness - you can speak meaningfully about unmeasured observables.

I don't like to discuss the implications of the differences in these terms when discussing Bell or Aspect, because I think it leads to semantic arguments. For MOST purposes, I consider these terms interchangeable. So do most writers based on my readings, although there are a few who attempt to distinguish among them. Funny thing, the math is pretty much the same regardless. So too the predictions of QM.

DrChinese

Apr20-10, 11:19 AM

Thanks a lot DrChinese! I’m fairly new here, but I do understand you are the 'grandmaster' of EPR here on PF; therefore I’m now feeling something like this... :cool: + :smile: + o:) + :blushing: + :approve:

Thanks! ;)

Between you, RUTA, FrameDragger, SpectraCat and a number of others (sorry if I left out your name too), I think we have seen some great additions around here. I consider the quality of the discussions to be inversely proportional to the number of ZapperZ posts! That meaning, in my book, that he does not need to pop in as much with his wise and informed comments.

:biggrin:

DevilsAvocado

Apr20-10, 12:50 PM

This is unfair in respect to Many-worlds interpretation, right?
Well... no, that’s actually not my point. To me it’s almost clear that EPR must be some kind of "gun smoke" of the next 'paradigm' in physics ('smoke' without 'fire'!? :uhh:). It’s a clear sign that we do not know everything there is to know, yet.

And I’m almost stunned by the numerous attempts to run "business as usual" – stating "well, this doesn’t mean anything... it’s a matter of QM interpretation", or "it’s hard to measure photons, therefore EPR is most probably misleading".

I don’t think that’s fair to all the intelligent persons that spent a lot of time working on this problem.

And if we look with some 'perspective' on the criticism of Bell test experiments – What are they saying? Well, most agree that Bell's theorem is correct and sound, but there is some "magical entangled loophole" that exposes itself in different ways, in different experiments!?

Yet we know that the 'overlapping effect' of all performed Bell test experiments, together with Bell's theorem is very convincing. And over time it will be definite.

I’m not an explicit supporter of MWI, it could be the correct solution, but I can’t get the 'pragmatic workings' of MWI into my head. Therefore I’m (for now) anticipating some hardnosed evidence from another 'branch'... :wink:

To consider this experiment as an EPR paradox test is a bit of stretch. EPR paradox considers separate measurements of two systems that are not interacting at the moment of measurement. But in this experiment there is only one joined measurement of both systems.
This is exactly what I’m talking about – the "magical entangled loophole"!

Yes, in most cases fair sampling assumption is considered reasonable. But in this case fair sampling assumption necessarily comes packaged with one of the not-so-reasonable speculations like MWI, superdeterminism or nonlocality of Pilot-wave.
And in that light fair sampling is as reasonable as most reasonable one of those alternatives.
Agree. It’s maybe not wise to deduce the problem of explaining EPR as an immediate proof of even weirder 'things'...

As you say
Welcome to the club! :smile:

When Bell said that? Definitely it was quite some time ago. And still there is uncomfortable lack of experiments that explicitly test what happens when counter efficiency is changed above usual ~10% level even when there is constant improvement in photon detection technologies.
Again, we have a very solid theory in Bell's theorem, and the experiments are improved day by day.
Where are the theories proving that it’s impossible to ever prove Bell's theorem? Any equations? Anything? Except opposition, and the "magical entangled loophole"...??

How would science look if we apply this 'approach' to everything else? Did the Big Bang really happen? Well, apparently not! No one was there to make the 'proper experiments', and the CMB is just a bunch of photons that we don’t know how to measure with 100% efficiency! Conclusion: Big Bang is not true, and we can explain everything we see with the "Turtle Interpretation"!! :biggrin:

(to be drastic :wink:)

DevilsAvocado

Apr20-10, 12:52 PM

... I consider the quality of the discussions to be inversely proportional to the number of ZapperZ posts!
:rofl:

DevilsAvocado

Apr20-10, 05:51 PM

I think that the real issue is with the definition of 'Local Realism'.
...
I have a faint inclination that 'this star' will certainly have an influence on our measurement related to Earth (however small this effect may be). If an instrument could be formed that is (hyper)n sensitive, we may be able to gauge the effect. And it would depend on the (refinement)n/nature of our measurement wheter we take this effect to be of any consequence or not.
Deepak Kapur, I think the possibility for EPR to ever prove Local realism is almost zero, since it requires local hidden variables (as Frame Dragger & DrChinese already pointed out), and Bell has shown that quantum mechanics is not 'compatible' with LHV, and QM predictions are the most precise in all of physics.

Still, we can be pretty sure that the Moon is "out there" even when no one is observing it... :wink:

Or put it this way – if observations are required for distant stars and galaxies to be 'real' objects – we could today only observe galaxies as they appeared < 4.5 billion years ago, which of course is not true.

The farthest galaxies in this picture (the very faint red specks) are seen as they appeared more than 13 billion years ago.

http://imgsrc.hubblesite.org/hu/db/images/hs-2010-01-a-large_web.jpg

It’s more than 'tough' to put macroscopic objects in superposition or entanglement, and this probably has something to do with the observed facts above... (= my speculation)

zonde

Apr21-10, 08:44 AM

Well... no, that’s actually not my point. To me it’s almost clear that EPR must be some kind of "gun smoke" of the next 'paradigm' in physics ('smoke' without 'fire'!? :uhh:). It’s a clear sign that we do not know everything there is to know, yet.

And I’m almost stunned by the numerous attempts to run "business as usual" – stating "well, this doesn’t mean anything... it’s a matter of QM interpretation", or "it’s hard to measure photons, therefore EPR is most probably misleading".
To me it seems like you are contradicting yourself.
From one side you say that we do not know everything there is to know, yet.
From the other side you do not accept neither indirect modifications of QM - interpretations nor direct modifications of QM - position that QM is incomplete.

Or do you imply that we should modify anything but QM?

I don’t think that’s fair to all the intelligent persons that spent a lot of time working on this problem.
And I do not understand this completely.
Are you saying that if all those intelligent persons spent a lot of time working on this problem we shouldn't work on this problem any more and abandon it?

And if we look with some 'perspective' on the criticism of Bell test experiments – What are they saying? Well, most agree that Bell's theorem is correct and sound, but there is some "magical entangled loophole" that exposes itself in different ways, in different experiments!?

Yet we know that the 'overlapping effect' of all performed Bell test experiments, together with Bell's theorem is very convincing. And over time it will be definite.

I’m not an explicit supporter of MWI, it could be the correct solution, but I can’t get the 'pragmatic workings' of MWI into my head. Therefore I’m (for now) anticipating some hardnosed evidence from another 'branch'... :wink:

This is exactly what I’m talking about – the "magical entangled loophole"!
Interpretation of Rowe's experiment rests on assumption that photons scattered from two ions can not possibly interact (locally) as to change the count of photons that ends in detector. This assumption contradicts with results of double slit experiment not speaking about anything else.
There is no "magical entangled loophole" in Rowe's experiment just plain wrong assumption (even from perspective of QM).

Again, we have a very solid theory in Bell's theorem, and the experiments are improved day by day.
Where are the theories proving that it’s impossible to ever prove Bell's theorem? Any equations? Anything? Except opposition, and the "magical entangled loophole"...??

How would science look if we apply this 'approach' to everything else? Did the Big Bang really happen? Well, apparently not! No one was there to make the 'proper experiments', and the CMB is just a bunch of photons that we don’t know how to measure with 100% efficiency! Conclusion: Big Bang is not true, and we can explain everything we see with the "Turtle Interpretation"!! :biggrin:
Science in general does not depend so much from "no go theorems" as Bell's theorem. There are quite different rules for theories that state "what can be" contrary to "what can't be".
If a theory states "what can be" given this and that it can be quite usable. And actually every theory has limited domain of applicability and still the science provides usable results.

DrChinese

Apr21-10, 10:24 AM

Interpretation of Rowe's experiment rests on assumption that photons scattered from two ions can not possibly interact (locally) as to change the count of photons that ends in detector. This assumption contradicts with results of double slit experiment not speaking about anything else.
There is no "magical entangled loophole" in Rowe's experiment just plain wrong assumption (even from perspective of QM).

I just don't get this at all. You speak as if Rowe is the ONLY Bell test. We already knew that spacelike separation - what you are complaining about - makes no difference from Weihs et al (as well as Aspect). What Rowe shows is that the fair sampling assumption does not make any difference either.

As it stands, we have the following:

a) No individual Bell test "loopholes" exist.
b) No existing/remaining local realistic theory purports to replicate the predictions of QM and explain entanglement test results.

Some scientists hope to eventually close all loopholes simultaneously, although there are others who do not see this as anything other than desirable - so as to end further discussion of the matter by the few remaining local realists. (Like that would make any difference!)

RUTA

Apr21-10, 11:32 AM

You are diverting my point, by raising another. Tit for Tat RUTA... "A cat for a hat, or a hat for a cat, but nothing for nothing."

Sorry, I was distracted and my latest post, plus some other quotes, were actually supposed to be in the first post. That's why the first post doesn't look like we had a disagreement. We do disagree on the value of time spent on interpretations. I believe it's valuable, while you don't find it particularly so. That's my understanding.

As for the rest, why do you feel I have a metaphysical interpretation?

You need to make ontological assumptions in order to map theory to experiment/experience, otherwise you're doing math, not physics. You can explore the mathematical consequences of equation X of theory Y, but to do physics, you would have to map those consequences to experiment/experience, which tacitly, if not explicitly, entails ontology (metaphysics). So, when you use the term "Planck scale" you've some ontological baggage if you're talking physics, not math.

I don't see that as a logical conclusion from the standpoint of wanting to see the two major theories of physics AGREE (i.e. GR/QM). As for believing that interpeting QM will lead to breakthroughs... I'm yet to see that. It DOES provide people with something to say other than, "we don't know"... a notoriously bad phrase to place in a grant request. Please don't assume what I "must" or must not believe.

You might read Gilder's "The Age of Entanglement" or Beller's "Quantum Dialogue" in order to appreciate the extent to which the development of quantum physics was tied to its interpretation. In reference to Beller's work, Smolin notes "there was not a single calculation in [Bohr's] notebooks, which were all verbal argument and pictures." [p 309 of Smolin's "The Trouble with Physics"]. Here is a quote fm Einstein writing to a young physics student (p. 310-11 in Smolin):

"I fully agree with you about the significance and educational value of methodology as well as history and philosophy of science, So many people today -- and even professional scientists -- seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historical and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is -- in my opinion -- the mark of distinction between a mere artisan or specialist and a real seeker after truth."

Smolin goes on to argue for the importance of relating our formal approaches "to the older writings by physicists and philosophers on the big issues in the foundations of space, time, or quantum theory."

No one knows why QM and GR don't marry up. Those of us in foundations are compelled to search for the key to unification in, among other places, our ontological biases. Those who search in this area are of course very interested in "interpretations."

ThomasT

Apr21-10, 11:49 AM

As a reader of this thread, I would personally rather that ThomasT wasn't discouraged from participating in the conversation.Thanks, but I'm not discouraged. :smile:

As you've read, there's some disagreement regarding the title question of this thread. The fact of the matter is that what's called nonlocality or action at a distance (wrt EPR or Bell tests) comes from:

(1) deductions based on the data and associated instrument settings and/or,

(2) interpretations (the semantics) of the associated QM and/or Bell's theorem formalisms (Bell inequalities, GHZ, etc).

But none of it contradicts locality. Bell's theorem (via Bell inequalities, GHZ, etc.) is about formal constraints, not what does or doesn't exist in Nature.

Frame Dragger

Apr21-10, 01:48 PM

Sorry, I was distracted and my latest post, plus some other quotes, were actually supposed to be in the first post. That's why the first post doesn't look like we had a disagreement. We do disagree on the value of time spent on interpretations. I believe it's valuable, while you don't find it particularly so. That's my understanding.

You need to make ontological assumptions in order to map theory to experiment/experience, otherwise you're doing math, not physics. You can explore the mathematical consequences of equation X of theory Y, but to do physics, you would have to map those consequences to experiment/experience, which tacitly, if not explicitly, entails ontology (metaphysics). So, when you use the term "Planck scale" you've some ontological baggage if you're talking physics, not math.

You might read Gilder's "The Age of Entanglement" or Beller's "Quantum Dialogue" in order to appreciate the extent to which the development of quantum physics was tied to its interpretation. In reference to Beller's work, Smolin notes "there was not a single calculation in [Bohr's] notebooks, which were all verbal argument and pictures." [p 309 of Smolin's "The Trouble with Physics"]. Here is a quote fm Einstein writing to a young physics student (p. 310-11 in Smolin):

"I fully agree with you about the significance and educational value of methodology as well as history and philosophy of science, So many people today -- and even professional scientists -- seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historical and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is -- in my opinion -- the mark of distinction between a mere artisan or specialist and a real seeker after truth."

Smolin goes on to argue for the importance of relating our formal approaches "to the older writings by physicists and philosophers on the big issues in the foundations of space, time, or quantum theory."

No one knows why QM and GR don't marry up. Those of us in foundations are compelled to search for the key to unification in, among other places, our ontological biases. Those who search in this area are of course very interested in "interpretations."

Well, it seems we come from deeply different views on the matter, but then, I have the benefit of not being a physicist... a luxury really. I'm just trying to learn for the sake of learning, and I don't need to produce new theories. If I did, I WOULD probably stick to the math, but I wouldn't conclude that because X maps to y that it really has a physical reality.

I respect your approach, but I don't share it. I do see what you mean by bias however, so I think mine is: GR is wonderfully predictive, as in QM. I believe that modificationa and unification of both will reveal new physics. I have no CLUE as to what, except a hope that it explains a bit more.

@ThomasT: None of it contradicts Locality, but then you need a theory to compete with QM's predictions. So far, QM leads, with dBB being able to match the predictions. It's not enough to simply say that Bell doesn't rule out Locality, becuase it DOES if you accept the predictions of QM.

So, yes, bell is about constraints, but it is an EFFECTIVE constraint which has strangled all LHV theories that have been put forward.

RUTA

Apr21-10, 03:38 PM

Well, it seems we come from deeply different views on the matter, but then, I have the benefit of not being a physicist... a luxury really. I'm just trying to learn for the sake of learning, and I don't need to produce new theories. If I did, I WOULD probably stick to the math, but I wouldn't conclude that because X maps to y that it really has a physical reality.

You hold the mainstream view. If you're interested in why that came to be the mainstream view, you can read either Gilder or Beller. But, rest assured, I'm the "quack" in this conversation, not you :-)

I respect your approach, but I don't share it. I do see what you mean by bias however, so I think mine is: GR is wonderfully predictive, as in QM. I believe that modificationa and unification of both will reveal new physics. I have no CLUE as to what, except a hope that it explains a bit more.

As an example of how one might use a QM interpretation to inspire an approach to unification, look up Hiley's recent work. In a summer 2009 preprint he writes,

"Since the advent of general relativity in which matter and geometry codetermine each other, there is a growing realisation that starting from an a priori given manifold in which we allow material processes to unfold is, at best, limited. Can we start from something more primitive from which both geometry and material process unfold together? The challenge is to find a formalism that would allow this to happen. In the early sixties David Bohm introduced the notion of a discrete structural process, [1], [2], in which he takes as basic, not matter or fields in space-time, but a notion of `structure process' from which the geometry of space-time and its relationship to matter emerge together providing a way that could underpin general relativity and quantum theory. Bohm provides a detailed discussion of the general notions implicit in this approach, but the problem of how to develop these ideas into a well defined mathematical structure remained unanswered."

In this paper he introduces what he hopes will serve as Bohm's missing mathematical structure. Just an example.

DevilsAvocado

Apr21-10, 09:27 PM

To me it seems like you are contradicting yourself.
From one side you say that we do not know everything there is to know, yet.
From the other side you do not accept neither indirect modifications of QM - interpretations nor direct modifications of QM - position that QM is incomplete.

Or do you imply that we should modify anything but QM?
And the short answer is – I have absolutely no idea!

Seriously, let’s be honest, I’m only a layman with this as a hobby, and if I’d proclaim – "Hey guys! This is the way to do it! I got the final solution!!" Then my claim in post #18 (http://www.physicsforums.com/showpost.php?p=2675332&postcount=18) that "I’m not stupid", would most certainly be 'somewhat' questioned. :biggrin:

I do understand why you think I’m contradicting myself. My last post will not gain a 'rhetorical medal'... (under stress by 'reality', sorry)

Let’s do it right, let’s take one step back. In post #40 (http://www.physicsforums.com/showpost.php?p=2679632&postcount=40) I pointed out Rowe as an example where the detection methods were almost 100% efficient, as a way of ending the discussion around the "Detection efficiency loophole" and "The fair sampling assumption". Your reaction was:
To consider this experiment as an EPR paradox test is a bit of stretch. EPR paradox considers separate measurements of two systems that are not interacting at the moment of measurement. But in this experiment there is only one joined measurement of both systems.

Then DrChinese hits the nail on the head (thanks DC!):
You speak as if Rowe is the ONLY Bell test.

If we also add this statement of yours:
Yes, in most cases fair sampling assumption is considered reasonable. But in this case fair sampling assumption necessarily comes packaged with one of the not-so-reasonable speculations like MWI, superdeterminism or nonlocality of Pilot-wave.
(emphasis by me)

Now, I hope I can explain, by the means of above, clearly what I’m arguing about:

To me, it seems as if there are two 'camps', struggling to 'get rid of' the EPR paradox (no offense!). One is the "Denial Camp" who tries with all means available to 'diminish' Bell's theorem and Bell test experiments, not to have to face the facts of even 'uglier beasts' like the MWI.

And the other is the "Interpretation Camp" who just loves freaky things – Is there a problem!? What problem?? We just sent it to a parallel universe!! Let’s have dinner now... yawn.

(And then the public, who likes some 'excitement', but in the end always prefers to live in a 'logical world'.)

Get it?

Now back to DrChinese and Rowe. Do you really think it’s fair to avoid 'the sum' of all performed Bell test experiments? If we can rule out one loophole in one experiment, why do you insist on bringing it back in another? Is that really what 'the rules of science' tells you??

Is it healthy science to deny, in absurdity, the facts DrChinese points out??
As it stands, we have the following:

a) No individual Bell test "loopholes" exist.
b) No existing/remaining local realistic theory purports to replicate the predictions of QM and explain entanglement test results.

So what do I want!?

Well, to start with: Let’s throw the 'blinders' away. Let’s not have preconceptions. Let’s not explain 'weird things' with even 'weirder things', that can’t be physically proved in less than +1000 years. Let’s accept what nature shows us, even if it turns out 'crazy'. Let’s accept that the science of nature is not going to be completed in 2010. Let’s find the truth, if there is one.

We know that both QM & GR are very effective in respective domain, thus completely throw one or both out seems farfetched... even if String theory turns out to play the most beautiful music ever heard...

Footnote:
Doesn’t the Double-slit experiment 'crushes' the Ensemble Interpretation, by the footprint of the wave function in the interference pattern??

DevilsAvocado

Apr21-10, 10:05 PM

We talk about moon becuase we see it the way our eyes/brains have been tuned to do so. Our instruments are also made/operated/analysed by our brains/eyes (that are tuned in a particular way).

It may be possible that moon/matter is not at all visible/detectable to someone from other stranger universe. (just foolish speculation with a small tinge of logic).

What would then become of our 'surity' about things.
Well, all this about 'personal interpretation' of the world is very true. Colors e.g. are only in our heads. In nature, there are only electromagnetic waves of different lengths.

But, you cannot avoid the fact that stars and galaxies evolves under a very long time, under gravity. And to make this argument even stronger: When the very first stars formed there where absolutely no life in the universe (to perform any observations)!!

How do you explain that?

Frame Dragger

Apr21-10, 10:46 PM

You hold the mainstream view. If you're interested in why that came to be the mainstream view, you can read either Gilder or Beller. But, rest assured, I'm the "quack" in this conversation, not you :-)

We don't agree, but if you're a quack then I'm the pope. As I'm not an old german man coming to grips with scandal, I suspect you're not a quack. I've read Gilder, not Beller (but I will now!), and I don't see how curiosity = quackery. You're not pushing a view, you're discussing it. I respect that.

As an example of how one might use a QM interpretation to inspire an approach to unification, look up Hiley's recent work. In a summer 2009 preprint he writes,

"Since the advent of general relativity in which matter and geometry codetermine each other, there is a growing realisation that starting from an a priori given manifold in which we allow material processes to unfold is, at best, limited. Can we start from something more primitive from which both geometry and material process unfold together? The challenge is to find a formalism that would allow this to happen. In the early sixties David Bohm introduced the notion of a discrete structural process, [1], [2], in which he takes as basic, not matter or fields in space-time, but a notion of `structure process' from which the geometry of space-time and its relationship to matter emerge together providing a way that could underpin general relativity and quantum theory. Bohm provides a detailed discussion of the general notions implicit in this approach, but the problem of how to develop these ideas into a well defined mathematical structure remained unanswered."

In this paper he introduces what he hopes will serve as Bohm's missing mathematical structure. Just an example.

I've read that (thanks to Demystifier and Zenith8, two very bright and interesting Bohmians here on PF), and I respect the goal. I think that a field with people taking different, but complementary approaches is a PLUS. This isn't fringe, anymore than EPR itself is "fringe". It's a well formulated objection to a formalism that is EFFECTIVE (mostly), but not satisfying or fully explanatory.

What can I say RUTA, you make a good case for your view, and I will continue to explore it. That said, I still maintain my formalism. :wink: I look forward to more of your posts.

Frame Dragger

Apr21-10, 10:52 PM

And the short answer is – I have absolutely no idea!

Seriously, let’s be honest, I’m only a layman with this as a hobby, and if I’d proclaim – "Hey guys! This is the way to do it! I got the final solution!!" Then my claim in post #18 (http://www.physicsforums.com/showpost.php?p=2675332&postcount=18) that "I’m not stupid", would most certainly be 'somewhat' questioned. :biggrin:

I do understand why you think I’m contradicting myself. My last post will not gain a 'rhetorical medal'... (under stress by 'reality', sorry)

Let’s do it right, let’s take one step back. In post #40 (http://www.physicsforums.com/showpost.php?p=2679632&postcount=40) I pointed out Rowe as an example where the detection methods were almost 100% efficient, as a way of ending the discussion around the "Detection efficiency loophole" and "The fair sampling assumption". Your reaction was:

Then DrChinese hits the nail on the head (thanks DC!):

If we also add this statement of yours:

(emphasis by me)

Now, I hope I can explain, by the means of above, clearly what I’m arguing about:

To me, it seems as if there are two 'camps', struggling to 'get rid of' the EPR paradox (no offense!). One is the "Denial Camp" who tries with all means available to 'diminish' Bell's theorem and Bell test experiments, not to have to face the facts of even 'uglier beasts' like the MWI.

And the other is the "Interpretation Camp" who just loves freaky things – Is there a problem!? What problem?? We just sent it to a parallel universe!! Let’s have dinner now... yawn.

(And then the public, who likes some 'excitement', but in the end always prefers to live in a 'logical world'.)

Get it?

Now back to DrChinese and Rowe. Do you really think it’s fair to avoid 'the sum' of all performed Bell test experiments? If we can rule out one loophole in one experiment, why do you insist on bringing it back in another? Is that really what 'the rules of science' tells you??

Is it healthy science to deny, in absurdity, the facts DrChinese points out??

So what do I want!?

Well, to start with: Let’s throw the 'blinders' away. Let’s not have preconceptions. Let’s not explain 'weird things' with even 'weirder things', that can’t be physically proved in less than +1000 years. Let’s accept what nature shows us, even if it turns out 'crazy'. Let’s accept that the science of nature is not going to be completed in 2010. Let’s find the truth, if there is one.

We know that both QM & GR are very effective in respective domain, thus completely throw one or both out seems farfetched... even if String theory turns out to play the most beautiful music ever heard...

Footnote:
Doesn’t the Double-slit experiment 'crushes' the Ensemble Interpretation, by the footprint of the wave function in the interference pattern??

Awesome post, and very clear. As to the footnote, I had this very argument (and "lost) with Zenith and Demystifier. The claim of dBB is that the interference is a function of the PILOT wave, which "guides" the particles. The particles themselves follow Classic Schrodinger trajectories. I don't believe this, but it matches the predictions of QM, so my belief is pretty irrelevant.

When it comes to dBB, you can't go wrong chatting with Zenith and/or Demystifier. :smile:

Deepak Kapur

Apr21-10, 11:48 PM

Well, all this about 'personal interpretation' of the world is very true. Colors e.g. are only in our heads. In nature, there are only electromagnetic waves of different lengths.

But, you cannot avoid the fact that stars and galaxies evolves under a very long time, under gravity. And to make this argument even stronger: When the very first stars formed there where absolutely no life in the universe (to perform any observations)!!

How do you explain that?

Actually, I was talking of a universe that is older/different/stranger than our own (I think this thing is not supported by the present super-structure of science).

Frame Dragger

Apr22-10, 12:16 AM

Actually, I was talking of a universe that is older/different/stranger than our own (I think this thing is not supported by the present super-structure of science).

Ok, I'm genuinely confused... If there are other universes, we'd be completely cut-off from them. Another universe would also lack (us as) observers, so... I'm not sure what you're getting at, supported or not. I get the sense that in many of your posts you're expressing a similar idea about cosmology, but I'm never quite sure what it is. Sometimes you make VERY odd statements (from my perspective), and the other times you ask perfectly reasonable questions.

If you present your beliefs for critique, it may be that you can really learn quite a bit here. Remember, learning about a view that differs from your own doesn't preclude holding personal beliefs. That said, it's difficult to know if you're trying to offer a personal theory, or if you're truly confused... or both! Hell, I'm not sure from one post to the next which it might be. This isn't the thread for it, but maybe you could post your full view in the lounge (which is much more liberal), and start from there. If you present it as your current understanding, and not an attempt to "convert" so to speak, and are open to discussion... well... you might find the rest of the site more useful.

For example... an "older/different/stranger universe"... Different in what ways? Strange how? Our universe seems pretty weird as it is to be fair. Do you mean a previous "incarnation" of this universe is a cyclical model, or something out of Brane Cosmology? I'm just not sure if you're swinging for the fences, are deeply misinformed (not uncommon), or if this is an attempt to reconcile spiritual/religious beliefs with science?

inflector

Apr22-10, 03:47 AM

No one knows why QM and GR don't marry up. Those of us in foundations are compelled to search for the key to unification in, among other places, our ontological biases. Those who search in this area are of course very interested in "interpretations."

To me, this is a key observation. Something about science's collective understanding is incomplete or incorrect, something very significant.

The biases of scientists over the last century have cut off certain paths of inquiry as "unfruitful," "impossible," "foolish," etc. It may be that the key to progress lies at least partway down one of these discarded paths.

Nowhere do these ontological biases show up more strongly than in the interpretations of QM itself. This is one of the reasons that I find dBB to be so interesting. Here we have a perfectly valid way of looking at QM that allows for a broad range of new possibilities. It represents largely unmapped territory. It may be that thinking about QM from a different perspective, would provide fertile soil for the germ of an idea that develops into a unification of QM and GR.

Besides, there has been 70 years or more when physics has been dominated by other interpretations, perhaps these other interpretations have been limiting our capacity to imagine the truth in some way. Perhaps the ontological biases implicit with these interpretations are the blocks that have been keeping us from seeing the obvious.

As an example of how one might use a QM interpretation to inspire an approach to unification, look up Hiley's recent work. In a summer 2009 preprint he writes,

"[snip]...Can we start from something more primitive from which both geometry and material process unfold together? The challenge is to find a formalism that would allow this to happen. In the early sixties David Bohm introduced the notion of a discrete structural process, [1], [2], in which he takes as basic, not matter or fields in space-time, but a notion of `structure process' from which the geometry of space-time and its relationship to matter emerge together providing a way that could underpin general relativity and quantum theory. ...[snip]"

In this paper he introduces what he hopes will serve as Bohm's missing mathematical structure. Just an example.

This is a great example of a different way of looking at things. This idea may or may not bear fruit but at least it is new ground, interesting, and offers some potential for advancement.

Do you have a link to this Hiley paper? I'd love to read it. I couldn't find it using google. Is it on arXiv?

zonde

Apr22-10, 09:37 AM

I just don't get this at all. You speak as if Rowe is the ONLY Bell test. We already knew that spacelike separation - what you are complaining about - makes no difference from Weihs et al (as well as Aspect). What Rowe shows is that the fair sampling assumption does not make any difference either.
I am not complaining about spacelike separation of ions. The problem is that this experiment fails to demonstrate entanglement between two ions.

Non-local correlation does not have to appear at the moment when ions scatter light.
This correlation can appear later quite locally when light from two ions overlap. And then there is no spooky action at a distance but quite local interference of light.

You can try to extend result of Weihs et al experiment to two ions in a way that if they are entangled it can not be explained by some mysterious communication at light or sub-light speed. The problem is that they don't have to be entangled at all to explain results of this experiment.

Frame Dragger

Apr22-10, 10:27 AM

I am not complaining about spacelike separation of ions. The problem is that this experiment fails to demonstrate entanglement between two ions.
How so?! This seems like it would require some serious citation.

Non-local correlation does not have to appear at the moment when ions scatter light. This correlation can appear later quite locally when light from two ions overlap. And then there is no spooky action at a distance but quite local interference of light.

Again, this is a spectacular claim which requires commensurate support.

You can try to extend result of Weihs et al experiment to two ions in a way that if they are entangled it can not be explained by some mysterious communication at light or sub-light speed. The problem is that they don't have to be entangled at all to explain results of this experiment.

See previous objections. This seems like an opinion which is largely discarded. I'll ask again, as has Dr.C: What LHV theory survived Bell? It's not enough to object, you need to provide an alternative to QM which is at least as predictive. Otherwise, you're just explaining a personal bias.

DrChinese

Apr22-10, 10:30 AM

I am not complaining about spacelike separation of ions. The problem is that this experiment fails to demonstrate entanglement between two ions.

Non-local correlation does not have to appear at the moment when ions scatter light.
This correlation can appear later quite locally when light from two ions overlap. And then there is no spooky action at a distance but quite local interference of light.

You can try to extend result of Weihs et al experiment to two ions in a way that if they are entangled it can not be explained by some mysterious communication at light or sub-light speed. The problem is that they don't have to be entangled at all to explain results of this experiment.

Huh? You ARE complaining that they are not spacelike separated! You say that a sub-c effect could account for that. Of course, it would be new and previously undiscovered - probably worth a Nobel. Oh, and it would not account for the results of Weihs et al.

So as I say, don't treat Rowe as if it is a lone experiment. It isn't.

RUTA

Apr22-10, 11:11 AM

To me, this is a key observation. Something about science's collective understanding is incomplete or incorrect, something very significant.

When I first entered the foundations community (1994), there were still a few conference presentations arguing that the statistical and/or experimental analyses of EPR-Bell experiments were flawed. Such talks have gone the way of the dinosaurs. Virtually everyone agrees that the EPR-Bell experiments and QM are legit, so we need a significant change in our worldview. There is a proper subset who believe this change will be related to the unification of QM and GR :-)

Do you have a link to this Hiley paper? I'd love to read it. I couldn't find it using google. Is it on arXiv?

He only wrote it last summer (2009) and sent it to us last fall (2009) in preparation for an upcoming conference. At that time it was still a work in progress and he asked that we not disseminate it. I was hoping he had it posted on the arXiv by now (there are actually two of them -- one for the Dirac equation and one for the Schrodinger equation). If that's not the case, there should be something out there because I remember seeing mention on PF of Lorentz invariant Bohmian mechanics and that's what his Dirac version shows. I'm sorry I don't have more info for you, I'm not a dBB guy :-)

ThomasT

Apr22-10, 01:23 PM

None of it contradicts Locality, but then you need a theory to compete with QM's predictions.Any representation of entanglement conforming to Bell's ansatz will satisfy a Bell inequality and be incompatible with QM. There's no disagreement about this, and it has nothing to do with nonlocality in Nature.

The salient features of Bell's general lhv formulation (ie., that the joint probability be expressed as a product of the individual probabilities involving the hidden variable) place certain limits on the range of the predictions that are possible using that form.

These limits are embodied in the various Bell inequalities. Experimental violation of the Bell inequalities tells us that a viable lhv theory can't have the form specified by Bell. It doesn't imply that nonlocality or ftl propagations exist.

It's not enough to simply say that Bell doesn't rule out Locality, becuase it DOES if you accept the predictions of QM.??? See above.

So, yes, bell is about constraints, but it is an EFFECTIVE constraint which has strangled all LHV theories that have been put forward.If it wasn't effective then it wouldn't be a constraint.

Anyway, regarding the topic, we can't infer the existence of actions at a distance or ftl propagations from this.

RUTA

Apr22-10, 01:50 PM

Experimental violation of the Bell inequalities tells us that a viable lhv theory can't have the form specified by Bell. It doesn't imply that nonlocality or ftl propagations exist. ... Anyway, regarding the topic, we can't infer the existence of actions at a distance or ftl propagations from this.

Correct. There are different ways to parse it, but the way I prefer is this:

Violations of Bell inequalities imply nonlocality and/or nonseparability.

So, nonseparability alone would do the trick, thereby saving locality (no FTL causal connections).

It's rare to hear anyone considering a nonseparable ontology, though. We presented a nonseparable interpretation of QM at New Directions in the Foundations of Physics (2005). We had a full 2 hours of discussion after which Jeff Bub told us, "Congratulations on your new interpretation. Don't be discouraged that they didn't seem to understand it. It took me 3 epiphanies to understand your nonseparable ontology and each epiphany would require a week of lectures in a graduate-level course." Nonseparability violates our dynamical bias at a fundamental level. That's probably why you rarely hear it mentioned as an explanation for violations of Bell inequalities.

DrChinese

Apr22-10, 02:02 PM

RUTA

Apr22-10, 02:07 PM

I liked it after 1 epiphany (I haven't had the other 2 yet). :smile:

Didn't you also admit that you're committed to, or rather live on, Shutter Island? :tongue2:

DrChinese

Apr22-10, 03:08 PM

Didn't you also admit that you're committed to, or rather live on, Shutter Island? :tongue2:

Yes, I live there... in fact I am the detective in charge. Just ask the warden.

Frame Dragger

Apr22-10, 04:10 PM

Any representation of entanglement conforming to Bell's ansatz will satisfy a Bell inequality and be incompatible with QM. There's no disagreement about this, and it has nothing to do with nonlocality in Nature.

Riiight.. which is why I specified that there ARE no theories describing the kind of Locality that you seem to favour. That is why I said, None of it contradicts Locality, but then you need a theory to compete with QM's predictions.

Which you have NOT responded to. Responding to part of a single sentence, is another form of the good old fashioned Straw Man. You're making a case for something... what is it?

DevilsAvocado

Apr22-10, 06:55 PM

So, nonseparability alone would do the trick, thereby saving locality (no FTL causal connections).

It's rare to hear anyone considering a nonseparable ontology, though. We presented a nonseparable interpretation of QM at New Directions in the Foundations of Physics (2005).
...Houston, we've had a problem...

English is not my mother tongue; my mother’s tongue is somewhere else... don’t ask...

So, I got very interested and googled in a hurry nonsenseparability. Even misspelled (:grumpy:) I got two (2!) hits (1 epiphany), and the first was clearly accurate:
Holism and Nonseparability in Physics (Stanford Encyclopedia of Philosophy) (http://plato.stanford.edu/entries/physics-holism/#Spatial)

Nonseparability: Some physical process occupying a region R of spacetime is not supervenient upon an assignment of qualitative intrinsic physical properties at spacetime points in R.

It is important to note that nonseparability entails neither physical property holism nor spatial nonseparability: a process may be nonseparable even though it involves objects without proper parts. But this section has explained that either of the latter principles entails nonseparability under quite weak assumptions.

My very first impression was that this phraseology penetrated alco-holism, but that turned out to some extent off beam... (2 epiphany)

Now I knew I was close, and asked my dear grandfather if he could do the interpretation... but his tongue was occupied explaining the nature of the "Hole-o-graphic Torus Topology of the Universe":

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

Please, maybe some of the more 'subtitle contributors' in this thread could elaborate on this matter. I know I can get there... 3 epiphany is around the corner... I’ve seen the light from the lighthouse... :bugeye:

Footnote:
Do they serve a fruitcake on Shutter Island?? :confused:

DevilsAvocado

Apr22-10, 07:10 PM

Awesome post, and very clear. As to the footnote, I had this very argument (and "lost) with Zenith and Demystifier. The claim of dBB is that the interference is a function of the PILOT wave, which "guides" the particles. The particles themselves follow Classic Schrodinger trajectories. I don't believe this, but it matches the predictions of QM, so my belief is pretty irrelevant.
Thanks a lot FD! Ahhhouch you’ve lost! Did you 'torture' them with the Quantum eraser experiment? Or the Delayed choice quantum eraser?? What kind of PILOT could handle that...!? :grumpy:
(:biggrin:)

DevilsAvocado

Apr22-10, 07:37 PM

Actually, I was talking of a universe that is older/different/stranger than our own (I think this thing is not supported by the present super-structure of science).
Err... have you ever heard the 'turtle story'...?
Turtles all the way down

A well-known scientist once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said:

"What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise."

The scientist gave a superior smile before replying, "What is the tortoise standing on?"

"You're very clever, young man, very clever", said the old lady. "But it's turtles all the way down!"

http://i47.tinypic.com/1621vut.jpg

We can run this 'quarrelling' on every 'turtle', and still the outcome will be the same...

DevilsAvocado

Apr22-10, 07:43 PM

Responding to part of a single sentence, is another form of the good old fashioned Straw Man.
This is somewhat familiar... but in my case... they just dump the whole post! :rofl:

Frame Dragger

Apr22-10, 07:54 PM

This is somewhat familiar... by in my case... they just dump the whole post! :rofl:

Yeah, I hear you. :biggrin:

inflector

Apr22-10, 10:14 PM

Err... have you ever heard the 'turtle story'...?

Of course, I'm very familiar with the story of the turtles (http://www.amazon.com/gp/product/007148664X?ie=UTF8&tag=curtisfaith-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=007148664X) (since I wrote that book). Oh, but I suppose you mean another sort of turtle.

This is one of the philosophical problems that trips up both creationists and atheists alike. What came first? An all-powerful deity? Or perhaps a universe spontaneously erupting from nothingness?

RUTA

Apr22-10, 10:15 PM

Please, maybe some of the more 'subtitle contributors' in this thread could elaborate on this matter.

That was a great post! I'm stealing your "nonsenseparability" and "alco-holism" for use in my QM PowerPoint lecture. I'll cite you, but most people will assume "DevilsAvocado" is just part of the joke :-)

As I warned, nonseparability is much more difficult to understand than nonlocality. I suspect this is because what (most) people need to "understand" nonseparability is a nonseparable ontology. The definition you provided from SEP doesn't give an ontology, it pretty much just says, "The reason for entangled outcomes in QM is not causal nonlocality." This is a gross oversimplification, but let me continue along these lines in an effort to give you SOMETHING you can wrap your head around.

Suppose you have two, entangled, space-like related measurements, A and B. That A and B are "space-like related" means that, per special relativity, in some frames of reference A occurs before B, in some frame of ref A and B are simultaneous, and in other frames of ref B occurs before A. Another way of saying this is a line between A and B would represent a FTL connection. [The combination of these two facts about space-like related events entails, for example, that A cannot be the cause of B unless you believe a cause need not precede its effect or you believe there is a "preferred frame," i.e., one in which A occurs before B.] That A and B are "entangled" means, given repeated trials, correlations in the outcomes of A and B violate a Bell inequality. We have conducted experiments which satisfy this situation and QM accurately predicts the observed correlations, so what's the "problem?"

Quantum physics as a whole has many technical issues (see the SEP entry on QFT, for example), and of course there is the problem of reconciling formally QM and GR, but the "problem" I want to focus on here is simply that of ontology. What is the nature of reality such that we find space-like separated experimental results that violate Bell's inequality?

The SEP entry on nonseparability is (overly) simplistically put just saying no "spooky action at a distance," i.e., no FTL causal connection between A and B. So, here's what you have: You're the guy doing measurement A. You get a result at A, call it "red." If there is no FTL causal connection between A and B, then the reason you got red as a result of your measurement A is not attributable to you, your device, the quantum entity (whatever it is or isn't), or anything else in the immediate vicinity of that measurement. EPR argued that it was possible to know (probability 1) something about the outcome at A due to a measurement at B (the entangled property). So, if you don't have "spooky action at a distance" between A and B, there must be a fact of the matter at A, due entirely to the situation in the immediate spacetime vicinity of A to account for your red outcome. QM doesn't give us any way to obtain those "hidden" facts, so it's clearly incomplete. But, violation of the Bell inequality means EPR are wrong, QM is right, so without "spooky action at a distance" the red outcome at A cannot be due to the situation in the immediate spacetime vicinity of A. That's all SEP tells you, really.

Since the SEP characterization of nonseparability isn't giving you an ontology to "explain" the red outcome, you're probably saying "WTF?" SEP distilled the mystery of nonseparability from the violations of Bell inequalities by telling us what ISN'T true ontologically, but didn't RESOLVE anything mysterious USING nonseparability! To do that they need to tell us what IS true ontologically! Of course, the good philosophers at SEP will simply reply, "We did tell you what IS the case per the second principle of logic, i.e., excluded middle. Your desired ontology is that which we did not exclude in our statement." But, our brains work according to what they say is NOT true, so we just don't have anything left to "see."

At least that's my theory as to why you're confused by what you found on nonseparability :-) If not, well you have my best Roseann Rosanadana, "Nevermind."

zonde

Apr23-10, 03:36 AM

How so?! This seems like it would require some serious citation.

Again, this is a spectacular claim which requires commensurate support.
I am afraid I can not give you citations but let's look at this experiment from QM perspective (no LHV or anything).
We can compare it with double slit experiment:
http://www.physicsforums.com/attachment.php?attachmentid=25325&stc=1&d=1272011112

In interpretation of experiment wave nature of light is completly ignored, insted photons are treated as particles. But if there are two indistinguishable paths for photons treating photons like particles gives wrong result.

Of course it would be nicer if I could give calculations proving that photon interference alone can account for observed result but even without them it's clear that interpretation of experiment is incomplete and can not be considered conclusive.

zonde

Apr23-10, 03:53 AM

I am not complaining about spacelike separation of ions.

Huh? You ARE complaining that they are not spacelike separated!
It seems we have communication problem.

You say that a sub-c effect could account for that. Of course, it would be new and previously undiscovered - probably worth a Nobel. Oh, and it would not account for the results of Weihs et al.
Again you are seeing in my post something I do not see.

zonde

Apr23-10, 04:37 AM

To me, it seems as if there are two 'camps', struggling to 'get rid of' the EPR paradox (no offense!). One is the "Denial Camp" who tries with all means available to 'diminish' Bell's theorem and Bell test experiments, not to have to face the facts of even 'uglier beasts' like the MWI.

And the other is the "Interpretation Camp" who just loves freaky things – Is there a problem!? What problem?? We just sent it to a parallel universe!! Let’s have dinner now... yawn.

(And then the public, who likes some 'excitement', but in the end always prefers to live in a 'logical world'.)

Get it?
Got it.
I am in "Denial Camp" definitely. :devil:

Now back to DrChinese and Rowe. Do you really think it’s fair to avoid 'the sum' of all performed Bell test experiments? If we can rule out one loophole in one experiment, why do you insist on bringing it back in another? Is that really what 'the rules of science' tells you??
Yes, I really think it’s fair to avoid 'the sum' of all performed Bell test experiments.
Let me give you an example.
Lets say we set out to find what influence two polarizers have on each other and measurements of polarization by them if they are put side by side. Suppose (naturally) we find out that they do not have any detectable effect.
Now encouraged by our result we make another setup where we put two Stern-Gerlach apparatuses side by side and claim that they will not influence each other and respective spin measurements.
Now do I have to explain why this claim will be invalid? I hope not.

So what do I want!?

Well, to start with: Let’s throw the 'blinders' away. Let’s not have preconceptions. Let’s not explain 'weird things' with even 'weirder things', that can’t be physically proved in less than +1000 years. Let’s accept what nature shows us, even if it turns out 'crazy'. Let’s accept that the science of nature is not going to be completed in 2010. Let’s find the truth, if there is one.

We know that both QM & GR are very effective in respective domain, thus completely throw one or both out seems farfetched... even if String theory turns out to play the most beautiful music ever heard...
Who talks about throwing away something really useful? Not me.
Well ok as far as it concerns me you can replace GR with something else because it's so complex and it seems that it is not used so much as it could be if it would be more simple. But definitely not SR, no way.
And of course not QM. Well, less no-go theorems would be preferable and of course with entanglement replaced by something else. :rolleyes:

SpectraCat

Apr23-10, 06:48 AM

I am afraid I can not give you citations but let's look at this experiment from QM perspective (no LHV or anything).
We can compare it with double slit experiment:
http://www.physicsforums.com/attachment.php?attachmentid=25325&stc=1&d=1272011112

In interpretation of experiment wave nature of light is completly ignored, insted photons are treated as particles. But if there are two indistinguishable paths for photons treating photons like particles gives wrong result.

Of course it would be nicer if I could give calculations proving that photon interference alone can account for observed result but even without them it's clear that interpretation of experiment is incomplete and can not be considered conclusive.

Well, I don't think this is much of a problem for the Rowe experiment, because the ions were well-separated in two distinct traps more than 1 mm apart. That is more than 1000 times the wavelength of light used, and thus rather far for any of the double-slit effects you are talking about to play a significant role. So, I don't think your objection holds any water in this case.

I am pretty sure that Rowe et al. anticipated just this sort of criticism when designing their trap ... here is an earlier paper detailing the painstaking testing that they did to ensure their design was suitable for this sort of experiment: http://arxiv.org/abs/quant-ph/0205094.

DrChinese

Apr23-10, 08:49 AM

Yes, I really think it’s fair to avoid 'the sum' of all performed Bell test experiments.
Let me give you an example.
Lets say we set out to find what influence two polarizers have on each other and measurements of polarization by them if they are put side by side. Suppose (naturally) we find out that they do not have any detectable effect.
Now encouraged by our result we make another setup where we put two Stern-Gerlach apparatuses side by side and claim that they will not influence each other and respective spin measurements.
Now do I have to explain why this claim will be invalid? I hope not.

Yes, I really have no idea what you are talking about. This makes no sense at all relative to our discussion.

ThomasT

Apr23-10, 08:57 AM

You're making a case for something... what is it?That there's a simpler explanation for why BIs are violated than positing the existence of nonlocality or ftl causality.

It has to do with the constraints on lhv formulatio0ns imposed by Bell (which are the basis for BIs) and the relevance of these constraints to the experimental situations to which they're applied.

Consider, for example, that Bell's locality condition reduces to the definition of statistical independence. But we know that the statistical dependence observed in Bell tests can be produced via local interactions/transmissions.

Do you see the problem? If BIs are derived from the predictive limits of an lhv formulation that doesn't discern nonlocality, then how can we infer the presence of nonlocality due to the violation of those BIs.

The answer is that we can't.

Wrt the topic of this thread, note also that nonlocality (spooky action at a distance) isn't a physical explanation anyway, as it refers to the absence of any intervening physical mechanism between two (apparently invariantly) related events, A and B.

That is, nonlocality is ultimately a word that refers to our ignorance -- or else there isn't any physics underlying the relationship between A and B to be discovered.

zonde

Apr23-10, 09:00 AM

Well, I don't think this is much of a problem for the Rowe experiment, because the ions were well-separated in two distinct traps more than 1 mm apart. That is more than 1000 times the wavelength of light used, and thus rather far for any of the double-slit effects you are talking about to play a significant role. So, I don't think your objection holds any water in this case.
Thanks for constructive comment.

But I think spatial distance doesn't really matter. What matters is if two optical paths are distinguishable, isn't it so? For example if optical path length difference is around 1000 wavelength then my argument is quite questionable because then we can not speak about interference of the "same" photon any more.

DrChinese

Apr23-10, 09:01 AM

Consider, for example, that Bell's locality condition reduces to the definition of statistical independence. But we know that the statistical dependence observed in Bell tests can be produced via local interactions/transmissions.

No, they can't. You know that because of experiments like Weihs et al.

ThomasT

Apr23-10, 09:40 AM

No, they can't. You know that because of experiments like Weihs et al.Which experiment -- is the link on your website, or can you provide one here? Thanks.

ThomasT

Apr23-10, 09:49 AM

Violations of Bell inequalities imply nonlocality and/or nonseparability.

So, nonseparability alone would do the trick, thereby saving locality (no FTL causal connections).I don't think that that's needed. At least I hope not because I'm pretty sure I don't understand what you mean by nonseparability. :smile:

Anyway, regarding BI violations, my (current) understanding is that they're sufficiently explained by the disparity between (1) the limitations imposed (and expressed in BIs) by Bell's formal constraints on lhv representations of entanglement, and (2) Bell test preparations -- independent of considerations of nonlocality or ftl causality.

That is, the incompatibility between (1) and (2) is evident enough that appealing to nonlocality and or nonseparability isn't required.

DrChinese

Apr23-10, 09:56 AM

Which experiment -- is the link on your website, or can you provide one here? Thanks.

It is on my website, and here as well:

http://arxiv.org/abs/quant-ph/9810080

Violation of Bell's inequality under strict Einstein locality conditions

Authors: Gregor Weihs, Thomas Jennewein, Christoph Simon, Harald Weinfurter, Anton Zeilinger

Abstract: We observe strong violation of Bell's inequality in an Einstein, Podolsky and Rosen type experiment with independent observers. Our experiment definitely implements the ideas behind the well known work by Aspect et al. We for the first time fully enforce the condition of locality, a central assumption in the derivation of Bell's theorem. The necessary space-like separation of the observations is achieved by sufficient physical distance between the measurement stations, by ultra-fast and random setting of the analyzers, and by completely independent data registration.

----------------------------------

Let's review what this is saying. Suppose there were a LHV that you proposed. According to Bell, it would need to meet these requirements: a) It makes predictions consistent with experiment; b) It does not violate a Bell Inequality. Clearly,per experiments such as Aspect and many others, a BI is violated. So a) is not possible. Unless...

Now, there is still a possibility that sub-c signalling of detector settings are being communicated between Alice and Bob - which would allow an alternative explanation for the BI violation? With this experiment, however, you can rule that alternative explanation out. They strictly control this so that such signalling is not viable. The essential result was already in the literature, but with this version it rules out any reasonable possibility of another avenue.

Frame Dragger

Apr23-10, 10:56 AM

I think we've isolated two long-standing issues:

1.) Zonde: Your objections make no sense, which is why they are not raised anymore, and why LHV theories don't survive infancy.

2.) ThomasT: You have a fundamental PHILOSPHICAL issue with non-locality, in the same vein as EPR did.

Neither are really open to much in the way of discussion. Not liking something doesn't make it any less true, and QM is marvelously predictive. We're IN this situation precisely because every time someone has tried to burst that bubble, it remains. Non-Locality may represent a fundamental ignorance, but in the context of larger QFTs, it makes a great deal of sense. Weird, and counter-intuitive, but sense nonetheless.

Given that... Maybe we can seperate this into:

1.) Technical objections which can be met, and discussed.
2.) Philosophical objection which can be discussed, but with the understanding that this is not a matter of loopholes or bias, but a "beyond the standard model" theme.

DevilsAvocado

Apr23-10, 11:15 AM

Excellent analysis Frame Dragger! +10 points on my scale!!

DrChinese

Apr23-10, 11:45 AM

Excellent analysis Frame Dragger! +10 points on my scale!!

"When we're reeeeeeeeeeeally rocking, we turn it up to 11." (Spinal Tap)

Anyway, I agree. :smile:

Frame Dragger

Apr23-10, 01:44 PM

@DevilsAvocado & @DrChinese: Thanks very much. :smile:

DevilsAvocado

Apr23-10, 03:36 PM

"When we're reeeeeeeeeeeally rocking, we turn it up to 11." (Spinal Tap)
Marshall "Over the Cliff" 1959SLPX
http://mentalfloss.cachefly.net/wp-content/uploads/2006/10/SpinalTap_Edith_503.jpg

:rofl:

DevilsAvocado

Apr23-10, 03:47 PM

... What came first?
Nothing?

inflector

Apr23-10, 04:39 PM

Nothing?

I think this is just one of those questions we'll never answer. :-) I don't see how we'll ever run the experiment. Something came out of nothing to start it all, or something always existed. One more turtle doesn't help us with answers.

Unless God decides to come out of his slumber and start performing miracles IN FRONT OF science, we'll have to do what we're doing and extrapolate as best we can from the now back as far as we can and see where that takes us.

As far as nonlocality goes. It sure seems to me that science has proven that, as far as one could at this point. Not that we shouldn't be looking for answers to the crazy questions that arise from this knowledge. But it seems we should accept that as the current understanding absent some new data.

DevilsAvocado

Apr23-10, 04:41 PM

We can compare it with double slit experiment:
http://www.physicsforums.com/attachment.php?attachmentid=25325&stc=1&d=1272011112

In interpretation of experiment wave nature of light is completly ignored, insted photons are treated as particles. But if there are two indistinguishable paths for photons treating photons like particles gives wrong result.

It probably don’t mean anything (to the discussion), but let’s be finicky, not to create more confusion. In your picture of Double-slit & EPR you state that the superposition is occurring at the screen?? But that’s where the wavefunction collapses (depending on interpretation) = measurement. The superposition of the particle (photon) is when it passes both slits simultaneously.

Particle = superposition
Wavefunction <> superposition

Right??

Edit: And even I understand that’s it fairly easy to 'get rid' of the wavefunction/interference by making the smallest detection 'on the way'. Those guys making the experiment are most probably smarter than both me & you...

Maybe some of the pros could clarify if it’s possible to get "position" without destroying "spin-entanglement"? It’s maybe impossible after all...??

DevilsAvocado

Apr23-10, 04:58 PM

I think this is just one of those questions we'll never answer. :-)
Right, this is a BIG question, but no logical laws of physics can demand living observers to start the process of 'reality', because living observers first needs 'reality', to be born!

= The Big Bang happened without observers. EOD

ThomasT

Apr23-10, 05:53 PM

It is on my website, and here as well:

http://arxiv.org/abs/quant-ph/9810080

Violation of Bell's inequality under strict Einstein locality conditions

Authors: Gregor Weihs, Thomas Jennewein, Christoph Simon, Harald Weinfurter, Anton Zeilinger

Abstract: We observe strong violation of Bell's inequality in an Einstein, Podolsky and Rosen type experiment with independent observers. Our experiment definitely implements the ideas behind the well known work by Aspect et al. We for the first time fully enforce the condition of locality, a central assumption in the derivation of Bell's theorem. The necessary space-like separation of the observations is achieved by sufficient physical distance between the measurement stations, by ultra-fast and random setting of the analyzers, and by completely independent data registration.

----------------------------------

Let's review what this is saying. Suppose there were a LHV that you proposed. According to Bell, it would need to meet these requirements: a) It makes predictions consistent with experiment; b) It does not violate a Bell Inequality. Clearly,per experiments such as Aspect and many others, a BI is violated. So a) is not possible. Unless...

Now, there is still a possibility that sub-c signalling of detector settings are being communicated between Alice and Bob - which would allow an alternative explanation for the BI violation? With this experiment, however, you can rule that alternative explanation out. They strictly control this so that such signalling is not viable. The essential result was already in the literature, but with this version it rules out any reasonable possibility of another avenue.Ok, I read the paper. Weihs doesn't contradict what I said any more than Aspect does. Weihs improves on Aspect, but the fact is that the statistical dependencies wrt both are produced via local channels.

Weihs moves the observers farther apart, varies the polarizer settings via physical random number generator, and does the data matching after all the data is collected rather than on the fly as Aspect does. None of this impacts what I said.

I'm not sure what you're saying in your review. Bell's requirement for an lhv formulation is that the joint probability be expressed as a product of the individual probabilities, which are expressed in terms of the hidden variable. This requirement limits the range of the predictions of any lhv formulation conforming to it. These limits on the range of predictions are the basis for deriving an associated Bell inequality. However, if Bell's constraints don't distinguish locality from statistical independence, then what can we infer from the violation of inequalities based on these constraints.

We can infer that the class of lhv formulations conforming to Bell's requirements are incompatible with the QM representation of entanglement, and also, via Bell tests, with experimental results. So this class of lhv theories is refuted. But the reasons for this are, as I've been trying to demonstrate, rather trivial and don't require nonlocality, or ftl causation, or anything more exotic than simply recognizing exactly what the disparity between Bell's ansatz and Bell test setups is.

RUTA

Apr23-10, 06:33 PM

I think this is just one of those questions we'll never answer. :-) I don't see how we'll ever run the experiment. Something came out of nothing to start it all, or something always existed. One more turtle doesn't help us with answers.

Unless God decides to come out of his slumber and start performing miracles IN FRONT OF science, we'll have to do what we're doing and extrapolate as best we can from the now back as far as we can and see where that takes us.

If you consider the GR solution (whatever it is) for cosmology, you have a SPACETIME structure (think of a globe as a 2D analogy). Now you can choose a spatial foliation in that spacetime and tell a dynamical story, but the spacetime structure stands alone without any particular foliation and story (let the lines of latitude be your 1D spatial surfaces so the "big bang" is the north pole). Once you appreciate the spacetime view (the globe as a whole), you realize that the existence of ANY point of the spacetime manifold is as mysterious as any other -- the existence of an "initial point" per some particular foliation is as mysterious as the point on the tip of my nose right ... now. It's the otherwise meaningless "story" that YOU created from the spacetime structure that makes you believe the existence of your "initial point" is somehow more "mysterious." Your desire to put a grid on the globe and tell a dynamical story about the creation of a 1D universe that expands to max size (at equator) then shrinks to a "big crunch" (south pole), leads you to ask, "What caused the big bang (north pole)?" You're asking a meaningless question, e.g., "What lies one mile north of the north pole?" You already have the globe (the entirety of spacetime), why bother creating such unnecessary confusion?

As far as nonlocality goes. It sure seems to me that science has proven that, as far as one could at this point. Not that we shouldn't be looking for answers to the crazy questions that arise from this knowledge. But it seems we should accept that as the current understanding absent some new data.
Science has not proven nonlocality. I'm a physicist who believes the Bell experiments are legit, but these experiments don't prove nonlocality; they prove nonlocality and/or nonseparability. So, it's possible that we have nonseparability and locality.

DevilsAvocado

Apr23-10, 08:45 PM

That was a great post! I'm stealing your "nonsenseparability" and "alco-holism" for use in my QM PowerPoint lecture.
Thanks! That’s okay, I have a donations account at PayPal for stolen quotes. :biggrin:

I'll cite you, but most people will assume "DevilsAvocado" is just part of the joke :-)
It is! :tongue:

but let me continue along these lines in an effort to give you SOMETHING you can wrap your head around.
Great, I need some remedy... After your last post, I suffer from posttraumatic brain-expansion... :eek:

Suppose you have two, entangled, space-like related measurements, A and B. That A and B are "space-like related" means that, per special relativity, in some frames of reference A occurs before B, in some frame of ref A and B are simultaneous, and in other frames of ref B occurs before A. Another way of saying this is a line between A and B would represent a FTL connection. [The combination of these two facts about space-like related events entails, for example, that A cannot be the cause of B unless you believe a cause need not precede its effect or you believe there is a "preferred frame," i.e., one in which A occurs before B.]
Yes! Now we’re getting to "des Pudels Kern"! Let’s take the classical example of a speeding train car. A is onboard and B is standing on the platform:
http://upload.wikimedia.org/wikipedia/commons/thumb/c/ce/Traincar_Relativity1.svg/250px-Traincar_Relativity1.svg.png
From the frame of reference of A, the light will reach the front and back of the train car at the same time.

http://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Traincar_Relativity2.svg/294px-Traincar_Relativity2.svg.png
From the frame of reference of B, the light will strike the back of the train car before it reaches the front.

The above is clear to me. But what I don’t get is how the synchronization of events can 'save' EPR? The "problem" is not whether A performs the measurement before B, or vice versa. The "problem" is that if you have one light-year between A & B – entanglement is still there – and can later be verified if B travels back to A!?

I don’t get this at all...

So, if you don't have "spooky action at a distance" between A and B, there must be a fact of the matter at A, due entirely to the situation in the immediate spacetime vicinity of A to account for your red outcome. QM doesn't give us any way to obtain those "hidden" facts, so it's clearly incomplete. But, violation of the Bell inequality means EPR are wrong, QM is right, so without "spooky action at a distance" the red outcome at A cannot be due to the situation in the immediate spacetime vicinity of A. That's all SEP tells you, really.
Okay! I’m gonna be a Philosopher when I grow up, it seem like an easy piece of cake! :smile:

"So, if you don't have "spooky action at a distance" between A and B, there must be a fact of the matter at A, due entirely to the situation in the immediate spacetime vicinity of A to account for your red outcome."

EDIT!: I missed this and it makes things even more contradictory...???
"so without "spooky action at a distance" the red outcome at A cannot be due to the situation in the immediate spacetime vicinity of A. That's all SEP tells you, really."
And the rest from here... well, doesn’t make any sense... as all the rest... :uhh:

Seriously, isn’t this what’s it all about!? And didn’t you get it wrong?? All performed Bell test experiments clearly show that it’s impossible to use local 'entities', whether it’s variable or constant – it just doesn’t work, due to the fact that the receiving polarizer’s are randomly rotated *AFTER* the photons left the source...

And mathematically we can make it quite simple by saying:
If there where local 'entities' to account for the outcome – we would get 50% hits.
If there where 'spukhafte' to account for the outcome – we would get 80% hits.

(I’m not perfectly sure about the numbers, but that doesn’t matter. You get more hits with 'spukhafte', and that’s all that’s matter.)

Now, QM has no 'spukhafte-equations' (yet), so this must be some 'Apples and Oranges' logic:
"QM doesn't give us any way to obtain those "hidden" facts, so it's clearly incomplete"
"EPR are wrong, QM is right"

Since the SEP characterization of nonseparability isn't giving you an ontology to "explain" the red outcome, you're probably saying "WTF?"
You betcha! :grumpy:

SEP distilled the mystery of nonseparability from the violations of Bell inequalities by telling us what ISN'T true ontologically, but didn't RESOLVE anything mysterious USING nonseparability!
Make no mistake about it! I didn’t RESOLVE anything!

To do that they need to tell us what IS true ontologically!
Please!

Of course, the good philosophers at SEP will simply reply, "We did tell you what IS the case per the second principle of logic, i.e., excluded middle. Your desired ontology is that which we did not exclude in our statement." But, our brains work according to what they say is NOT true, so we just don't have anything left to "see."
Words words words and even more words... "second principle of logic" when & where was this introduce, and what does it mean!? "Your desired ontology" ...is what?

"But, our brains work according to what they say is NOT true" Really?? At least some news...

I’m honestly thankful that you gave it a try, but seriously RUTA this is not physics – it’s a game of words – to hide all usable facts. And for God’s sake! How do you get this 'fuzzy-logic' into a mathematical formula (so we can start build "nonseparable DVD-players" etc)!?!?

I think that the problem is that you build all this reasoning on this simple assumption:
The SEP entry on nonseparability is (overly) simplistically put just saying no "spooky action at a distance,"
This is nothing more than a personal preference, no more, no less.

But THANKS for taking the time! The remedy didn’t work, and now you have put me in a state where my posttraumatic brain-expansion has amplified remarkably:

http://i43.tinypic.com/ruqhjr.jpg

DevilsAvocado

Apr24-10, 10:05 AM

Got it.
I am in "Denial Camp" definitely. :devil:
Great! One step forward! :smile:
I do have to warn you that 'backstage' we have formed a :devil: Denial of Denial Camps :devil: !! (:biggrin:)
Lets say we set out to find what influence two polarizers have on each other and measurements of polarization by them if they are put side by side. Suppose (naturally) we find out that they do not have any detectable effect.
Now encouraged by our result we make another setup where we put two Stern-Gerlach apparatuses side by side and claim that they will not influence each other and respective spin measurements.
Now do I have to explain why this claim will be invalid? I hope not.

Well yes, but this is only your personal 'speculations', right? And I do think you got it somewhat wrong... check my post #108 (http://www.physicsforums.com/showpost.php?p=2685669&postcount=108).

You make the assumption that the pros making the experiments are 'fighting in the dark', to get some 'exiting results' to flash to the world... anything...

I’m not in the 'business', but I do know that if a scientist says "Hey! I can prove some weird stuff!", he or she is going to be scrutinized by a lot of very smart people, trying to find any weakness in the claim.

Of course there are swindlers, who make every effort to fool the whole world, but they are rare, and they do not survive the fight against reality, in the long run.

So, what have we got? Well, we have a theory that all agrees is mathematical correct and reliable. This theory makes a prediction:

Either X is true or, Y or Z must be violated.

X = Local Hidden Variables
Y = Counterfactual Definiteness (Heisenberg Uncertainty Principle)
Z = Locality

Now, we know from the theory that X is not true if we accept that QM is a correct theory (and we all agree that QM is the most precise theory we have). To reverse X to true, we have to abandon QM, and start from scratch.

Therefore, the most healthy choice between QM=true/X=false or QM=false/X=true, must naturally be QM=true/X=false.

Y (Heisenberg Uncertainty Principle) is a fundamental part of QM, which we have conclude true, then naturally Y must also be true!

All this is achieved by natural reasoning, common sense, and a very solid theory.

Now, when we start to perform Bell test experiments, every experiment indicates that Y or Z is violated!

What’s the most logical to do in this situation?? Well, it’s not start a "Denial Camp" to reintroduce X as true – it’s way too late for that!!

We are getting the 'expected' results from the experimentalists, and it’s not sound to start questioning if the scientists making the experiments are 'retards' or 'swindlers'...

Come on!
Who talks about throwing away something really useful? Not me.
Okay! Let’s start with not throwing the logic away in the evaluation of Bell test experiments! :wink:

DrChinese

Apr24-10, 11:25 AM

Ok, I read the paper. Weihs doesn't contradict what I said any more than Aspect does. Weihs improves on Aspect, but the fact is that the statistical dependencies wrt both are produced via local channels.

Weihs moves the observers farther apart, varies the polarizer settings via physical random number generator, and does the data matching after all the data is collected rather than on the fly as Aspect does. None of this impacts what I said...

OK, I will try again so you will see.

a. Try to come up with a set of data points for a Bell test in the Mermin format (I have that on one of my pages). So that is at 0, 120, 240 degrees. You will see that NO realistic theory - local or otherwise - can account for this. Just try to put together the dataset and you will quickly see none is possible. So that seems to rule out all hidden variable theories right there. Let's call this the MAIN RESULT: no hidden variable formulations are possible without outside help.

b. BUT... there is an escape from that conclusion. That is because the observers, Alice and Bob, could work together so that their results are "somehow" modified so that the predicted results are witnessed. We don't know what that mechanism is. But IF there were one, THEN it would explain how the otherwise non-realistic results were obtained. So we are stretching here, but it APPEARS within the realm of possibility. Let's call this the MAIN ESCAPE: There is a change to Bob based on the result at Alice (or vice versa).

(I use the word "escape" because it reminds me of a magician escaping from inside of a locked box.)

c. Bell noted explicitly that there was on the table, at that time, a theory compatible with both the Main Result and the Main Escape... and it is non-local. Of course that is Bohmian Mechanics. But note that this does NOT change the Main Result at all. There is simply an escape.

d. Subsequent Bell tests, by Aspect and later Weihs, shows that the Main Escape is NOT open to local candidate theories. That is simply because they insure that escape route is cut off.

Because of the way the Bell debate came down, it is sometimes hard to follow the true logic and meaning of the entire argument. Let me repeat: there are NO theories possible - local or non-local - in which there are real definite hidden variables independent of observation. That is the Main Result.

There are, however, a number of escapes from this: non-locality (BM as already identified), backwards causation (RBW being one) and multiple histories/worlds (MWI) - all of which respect the Main Result by the addition of some wild Escape by our magician, the Amazing Ms. Nature. And note that the Main Result stands, even with the various Escapes! The only remaining question is: by what method did the magician escape? Can you see how the trick is performed?

DevilsAvocado

Apr24-10, 04:26 PM

For those stuck in the "envelope", this maybe will work:

David Mermin's EPR gedanken experiment animated
http://i40.tinypic.com/eal62q.png (http://public.fh-wolfenbuettel.de/~ruediger/lehre/EPRapplet/EPRapplet.html)

Description of Java applet (http://public.fh-wolfenbuettel.de/~ruediger/lehre/EPRapplet/EPRappletDescription.pdf)

Edit: I forgot to say it’s "Value of Alpha" who does the magic, and don’t forget to push "RESET" before setting new Alpha, to get the right percentage.

RUTA

Apr24-10, 08:29 PM

The above is clear to me. But what I don’t get is how the synchronization of events can 'save' EPR? The "problem" is not whether A performs the measurement before B, or vice versa. The "problem" is that if you have one light-year between A & B – entanglement is still there – and can later be verified if B travels back to A!?

I don’t get this at all...

FTL communication (nonlocality) is one way out of the EPR-Bell paradox. I was simply pointing out that should you opt for that solution, you have a problem with the relativity of simultaneity (RoS). That is, you need A to tell B what happened at A so B can adjust accordingly to make the correlations violate the Bell inequality. But, if that msg from A to B is FTL (A and B are spacelike related), then in some frames B occurs before A (RoS), so you then have to resort to a preferred frame (or allow for effects (B outcome) to proceed their causes (A outcome)). There are advocates for a preferred frame based on violations of the Bell inequality.

Okay! I’m gonna be a Philosopher when I grow up, it seem like an easy piece of cake! :smile:

"So, if you don't have "spooky action at a distance" between A and B, there must be a fact of the matter at A, due entirely to the situation in the immediate spacetime vicinity of A to account for your red outcome."

EDIT!: I missed this and it makes things even more contradictory...???
"so without "spooky action at a distance" the red outcome at A cannot be due to the situation in the immediate spacetime vicinity of A. That's all SEP tells you, really."
And the rest from here... well, doesn’t make any sense... as all the rest... :uhh:

Seriously, isn’t this what’s it all about!? And didn’t you get it wrong?? All performed Bell test experiments clearly show that it’s impossible to use local 'entities', whether it’s variable or constant – it just doesn’t work, due to the fact that the receiving polarizer’s are randomly rotated *AFTER* the photons left the source...

Don't confuse locality in the sense of differentiable manifolds (constitutive locality) with the locality of "local hidden variables" in Bell's proof (causal locality). Constitutive locality is associated with separability. Causal locality is "no spooky action at a distance."

Words words words and even more words... "second principle of logic" when & where was this introduce, and what does it mean!?
"Your desired ontology" ...is what?

There are three principles of logic: 1) Principle of Identity (A = A), 2) Principle of Excluded Middle (A or not A), and 3) Principle of Non-Contradiction (not (A and not A)). The SEP entry on nonseparability struck me as only providing a nonseparable ontology in the sense of excluded middle, i.e., the ontology you seek is anything that is not X. Now we know what X is, so techically their definition is valid. Unfortunately, that type of definition is only valuable if you have at least ONE example of not X, but most people don't have any examples of not X. For example, if I tell you the color of my chair is not pink, you have lots of possible colors that my chair could be. But, the SEP definition of nonseparability probably doesn't lead you to visualize even one possible nonseparable ontology.

I’m honestly thankful that you gave it a try, but seriously RUTA this is not physics – it’s a game of words – to hide all usable facts. And for God’s sake! How do you get this 'fuzzy-logic' into a mathematical formula (so we can start build "nonseparable DVD-players" etc)!?!?

I think that the problem is that you build all this reasoning on this simple assumption:

This is nothing more than a personal preference, no more, no less.

I inferred from your post with the SEP definition of nonseparability that you were trying to understand the nonseparability option for avoiding the Bell inequality violations, so I was responding.

QM interpretations can inspire new approaches to physics, e.g., Hiley's new approach to quantum gravity was generated by the dBB interpretation. So, if you understand the nonseparability option for accounting for Bell inequality violations and use it to generate a new interpretation of QM, e.g., “Reconciling Spacetime and the Quantum: Relational Blockworld and the Quantum Liar Paradox,” W.M. Stuckey, Michael Silberstein & Michael Cifone, Foundations of Physics 38, No. 4, 348 – 383 (2008), quant-ph/0510090, you can use this to generate a new approach to unification (“Relational Blockworld: A Path Integral Based Interpretation of Quantum Field Theory,” W.M. Stuckey, Timothy McDevitt & Michael Silberstein, quant-ph/0908.4348, under review at FoP). I'll be glad to continue trying to explain this option to you, but I don't want to cause you physical harm trying to do physics :-)

RUTA

Apr24-10, 08:39 PM

There are, however, a number of escapes from this: non-locality (BM as already identified), backwards causation (RBW being one) and multiple histories/worlds (MWI) - all of which respect the Main Result by the addition of some wild Escape by our magician, the Amazing Ms. Nature. And note that the Main Result stands, even with the various Escapes! The only remaining question is: by what method did the magician escape? Can you see how the trick is performed?

Thanks for the reference, DrC. I should point out that we don't consider Relational Blockworld (RBW) a backwards causation interpretation. We rather consider it an "acausal" account, meaning the notion of causality is not even valid at the level of QM. We wrote a paper arguing that our acausal account is better than backwards causation accounts: “Why Quantum Mechanics Favors Adynamical and Acausal Interpretations such as Relational Blockworld over Backwardly Causal and Time-Symmetric Rivals,” Michael Silberstein, Michael Cifone & W.M. Stuckey, Studies in History & Philosophy of Modern Physics 39, No. 4, 736 – 751 (2008). http://dx.doi.org/10.1016/j.shpsb.2008.07.005. If you want to see how this view generates a nonseparable ontology, see “Relational Blockworld: A Path Integral Based Interpretation of Quantum Field Theory,” W.M. Stuckey, Timothy McDevitt & Michael Silberstein, quant-ph/0908.4348 (under review at FoP).

DrChinese

Apr24-10, 09:04 PM

Thanks for the reference, DrC. I should point out that we don't consider Relational Blockworld (RBW) a backwards causation interpretation. We rather consider it an "acausal" account, meaning the notion of causality is not even valid at the level of QM. We wrote a paper arguing that our acausal account is better than backwards causation accounts: “Why Quantum Mechanics Favors Adynamical and Acausal Interpretations such as Relational Blockworld over Backwardly Causal and Time-Symmetric Rivals,” Michael Silberstein, Michael Cifone & W.M. Stuckey, Studies in History & Philosophy of Modern Physics 39, No. 4, 736 – 751 (2008). http://dx.doi.org/10.1016/j.shpsb.2008.07.005. If you want to see how this view generates a nonseparable ontology, see “Relational Blockworld: A Path Integral Based Interpretation of Quantum Field Theory,” W.M. Stuckey, Timothy McDevitt & Michael Silberstein, quant-ph/0908.4348 (under review at FoP).

Thanks for clarifying this. I often use the dreaded "retro-causal" or "backwards causation" tag to allow these to be distinguished from the Bohmian and MWI types. I know all versions are not identical. Yet at some level, the idea is that the future is a component of things that occur at a point in spacetime we refer to as "here" and "now". I realize these are hazy terms that cease to have the usual meaning when we get down to the specifics. Acausal is probably more accurate but I honestly don't think it conveys much. I do like Relational Blockworld (RBW) though, for what its worth. No term is ever going to do much more than serve as a code for folks so we can have a shortcut in discussions. Obviously the theory is much deeper.

DevilsAvocado

Apr25-10, 09:19 AM

Don't confuse locality in the sense of differentiable manifolds (constitutive locality) with the locality of "local hidden variables" in Bell's proof (causal locality). Constitutive locality is associated with separability. Causal locality is "no spooky action at a distance."
This is important and I have to be sure.

Causal locality
If we set LHV to be +1 & -1 before sending the photons, we are not violating any locality. It’s just a matter of sending away 'predefined letter' in an 'envelope', and we know the outcome in advance, right...?

Constitutive locality
The receivers of the 'envelope' are physically separated in space-time, i.e. they have no connection FTL, right...?
There are three principles of logic: 1) Principle of Identity (A = A), 2) Principle of Excluded Middle (A or not A), and 3) Principle of Non-Contradiction (not (A and not A)). The SEP entry on nonseparability struck me as only providing a nonseparable ontology in the sense of excluded middle, i.e., the ontology you seek is anything that is not X. Now we know what X is, so techically their definition is valid. Unfortunately, that type of definition is only valuable if you have at least ONE example of not X, but most people don't have any examples of not X. For example, if I tell you the color of my chair is not pink, you have lots of possible colors that my chair could be. But, the SEP definition of nonseparability probably doesn't lead you to visualize even one possible nonseparable ontology.
Okay, can we 'refine' this and say – According to SEP the 'cause' of EPR is not "spooky action at a distance", it’s 'something else', but SEP can’t say anything about that. (right?)
I inferred from your post with the SEP definition of nonseparability that you were trying to understand the nonseparability option for avoiding the Bell inequality violations, so I was responding.
Okay, thanks.
I'll be glad to continue trying to explain this option to you, but I don't want to cause you physical harm trying to do physics :-)
No worries mate! It was just a (terribly silly) joke! :wink:
FTL communication (nonlocality) is one way out of the EPR-Bell paradox. I was simply pointing out that should you opt for that solution, you have a problem with the relativity of simultaneity (RoS). That is, you need A to tell B what happened at A so B can adjust accordingly to make the correlations violate the Bell inequality. But, if that msg from A to B is FTL (A and B are spacelike related), then in some frames B occurs before A (RoS), so you then have to resort to a preferred frame (or allow for effects (B outcome) to proceed their causes (A outcome)). There are advocates for a preferred frame based on violations of the Bell inequality.

>> This is extremely interesting! <<
Wow! I thought we only had one "problem" with the "spooky action at a distance", but this proves it’s much worse2!!

Let’s see now... IF we assume there ARE "spooky action at a distance" AND the values of the Particles are 100% RANDOM, and the OTHER Particle must obtain the OPPOSITE value instantly. THIS CAN’T BE DONE DUE TO RoS!?!? :surprised

Sweet jeees... I’m feeling dizzy... :uhh:

Does DrChinese or Frame Dragger or anyone else have a solution to this...?????

Frame Dragger

Apr25-10, 09:25 AM

This is important and I have to be sure.

Causal locality
If we set LHV to be +1 & -1 before sending the photons, we are not violating any locality. It’s just a matter of sending away 'predefined letter' in an 'envelope', and we know the outcome in advance, right...?

Constitutive locality
The receivers of the 'envelope' are physically separated in space-time, i.e. they have no connection FTL, right...?

Okay, can we 'refine' this and say – According to SEP the 'cause' of EPR is not "spooky action at a distance", it’s 'something else', but SEP can’t say anything about that. (right?)

Okay, thanks.

No worries mate! It was just a (terribly silly) joke! :wink:

>> This is extremely interesting! <<
Wow! I thought we only had one "problem" with the "spooky action at a distance", but this proves it’s much worse2!!

Let’s see now... IF we assume there ARE "spooky action at a distance" AND the values of the Particles are 100% RANDOM, and the OTHER Particle must obtain the OPPOSITE value instantly. THIS CAN’T BE DONE DUE TO RoS!?!? :surprised

Sweet jeees... I’m feeling dizzy... :uhh:

Does DrChinese or Frame Dragger or anyone else have a solution to this...?????

If we did... we'd be VERY VERY famous already. Welcome to the counterintuive nature of QM! :biggrin:

SpectraCat

Apr25-10, 09:30 AM

This is important and I have to be sure.

Causal locality
If we set LHV to be +1 & -1 before sending the photons, we are not violating any locality. It’s just a matter of sending away 'predefined letter' in an 'envelope', and we know the outcome in advance, right...?

Constitutive locality
The receivers of the 'envelope' are physically separated in space-time, i.e. they have no connection FTL, right...?

Okay, can we 'refine' this and say – According to SEP the 'cause' of EPR is not "spooky action at a distance", it’s 'something else', but SEP can’t say anything about that. (right?)

Okay, thanks.

No worries mate! It was just a (terribly silly) joke! :wink:

>> This is extremely interesting! <<
Wow! I thought we only had one "problem" with the "spooky action at a distance", but this proves it’s much worse2!!

Let’s see now... IF we assume there ARE "spooky action at a distance" AND the values of the Particles are 100% RANDOM, and the OTHER Particle must obtain the OPPOSITE value instantly. THIS CAN’T BE DONE DUE TO RoS!?!? :surprised

Sweet jeees... I’m feeling dizzy... :uhh:

Does DrChinese or Frame Dragger or anyone else have a solution to this...?????

AFAICS, RoS is a non-issue for this case. There is no question of causality here, only comparison of measurement. There is no logical inconsistency in a frame where B was measured before A or vice-versa, because the results are perfectly correlated. IOW, if you measure B first, you determine the value of A, if you measure A first, you determine the value of B. This holds in all frames, for all observers, so IMO there is no problem. Furthermore, when observers in different frames compare answers (as is required for a Bell test), they may disagree on the ordering of events, but they will always agree that there is a Bell violation for the results.

DevilsAvocado

Apr25-10, 09:39 AM

Welcome to the counterintuive nature of QM! :biggrin:
... I need coffee ... or maybe ... a vacation ... in the sun ... something real ... anything ... booze ... girls ... :uhh:

(:biggrin:)

DevilsAvocado

Apr25-10, 10:03 AM

... IOW, if you measure B first, you determine the value of A, if you measure A first, you determine the value of B.
IMO I see a weakness here, "spooky action at a distance" introduces another 'spooky thing' – An instant and universal NOW (that’s probably what made AE wanna 'throw up').

... but that’s maybe the whole solution!?!? Einstein WAS wrong, there is a universal NOW!?

I dunno... :uhh:

SpectraCat

Apr25-10, 10:15 AM

IMO I see a weakness here, "spooky action at a distance" introduces another 'spooky thing' – An instant and universal NOW (that’s probably what made AE wanna 'throw up').

... but that’s maybe the whole solution!?!? Einstein WAS wrong, there is a universal NOW!?

I dunno... :uhh:

No, that is just the same as saying that there is a "preferred reference frame". As RUTA said, there are people exploring that possibility, but I don't think it is necessary to resolve this issue.

It is important to realize that this is strictly an interpretational "what is going on behind the scenes" question at this point. AFAIK, there is no way to make any testable predictions based on different theories of *how* the Bell inequality occurs (i.e. how particle A "knows" that a measurement was performed on particle "B").

Most of the problems that are raised in this vein would only be real issues if FTL communication was possible using entangled pairs, but it's not, so we are ok. The causality relationship between the measurements at A and B is one example of this ... if it were somehow possible for Alice to know what Bob was doing at the time she made her measurement (assuming a space-like separation between them), then causality would be a problem, and you could potentially have a logical contradiction, because Alice would have access to information that was not available to all observers, i.e. she would be in a preferred reference frame. But that is equivalent to speculating about how things might change if SR is wrong ... as far as we know it isn't, so let's not worry about all of that .. physics is hard enough to understand as it is :wink:.

To reiterate, from a QM point of view, there are two measurements performed on the members of an entangled pair. Since the results are always perfectly correlated, it fundamentally does not matter which measurement comes first, at least for the purposes of Bell tests. All observers in all frames agree on the results of the measurements, once they have communicated them by normal sub-lightspeed channels for comparison.

DevilsAvocado

Apr25-10, 10:24 AM

Okay SpectraCat, I get back to you on that ASAP. NOW one part of my nonseparable body tells me it’s time for food... :wink:

DrChinese

Apr25-10, 10:53 AM

DevilsAvocado

Apr25-10, 06:29 PM

A lot of the Bohmians believe there is such, a preferred frame. ...
Thanks for the info DrC. I continue my reasoning, and relate to some of the 'interpretation issues', in next post.

DevilsAvocado

Apr25-10, 07:02 PM

No, that is just the same as saying that there is a "preferred reference frame". As RUTA said, there are people exploring that possibility, but I don't think it is necessary to resolve this issue.
Okay, I think DrC covers the 'basic'.

It is important to realize that this is strictly an interpretational "what is going on behind the scenes" question at this point. AFAIK, there is no way to make any testable predictions based on different theories of *how* the Bell inequality occurs (i.e. how particle A "knows" that a measurement was performed on particle "B").
Very true! I agree! (with 'some' objections below :wink:)

Most of the problems that are raised in this vein would only be real issues if FTL communication was possible using entangled pairs, but it's not, so we are ok. The causality relationship between the measurements at A and B is one example of this ... if it were somehow possible for Alice to know what Bob was doing at the time she made her measurement (assuming a space-like separation between them), then causality would be a problem, and you could potentially have a logical contradiction, because Alice would have access to information that was not available to all observers, i.e. she would be in a preferred reference frame. But that is equivalent to speculating about how things might change if SR is wrong ... as far as we know it isn't, so let's not worry about all of that .. physics is hard enough to understand as it is :wink:.
Okay, I know this is true, but I’m going to 'challenge' you a little (so you can show where I go wrong):

Let’s say Bob is a cruel bastard, and Alice is a cat. Bob have arranged a "Schrödinger Box" for Alice so that if the spin is up at Bob, and down at Alice, the "Box" will kill Alice!

Now, it’s hard to argue that Bob don’t know what Alice 'is doing'. He knows if she’s dead or alive...
(of course, Bob cannot control the outcome...)

To reiterate, from a QM point of view, there are two measurements performed on the members of an entangled pair. Since the results are always perfectly correlated, it fundamentally does not matter which measurement comes first, at least for the purposes of Bell tests.
I agree on the 'interpretation issues', but at the same time – if we cannot describe in fairly simple and understandable words what’s 'going on', and make logical attachments to current understandings – we’re in deep sh*t, IMO.

That would most probably mean that the true nature of the world is illogical, and that would be the worst outcome of all...

All observers in all frames agree on the results of the measurements, once they have communicated them by normal sub-lightspeed channels for comparison.
Well yes, but let’s have a look at the flip side of the coin... Let’s suppose we have arranged a Bell test where the photons run parallel, with a 'photon barrier' between them. Now, after x amount of time the photons hits the polarizer’s. Who is going to decide which one arrives first? The photons!? And if they arrives at exactly the same time (which they should do according to current understanding of physics)? Who is going to do the 'negotiation'?? "The United Council of Photons"??? :wink:

This is a fairly simple logical problem. Two physically separated entities are going to obtain the opposite outcome 100% random, and ONLY ONE can decide. Who decides? And how is this accomplished on distances FTL?

It does not help if the observers agree. The photons must 'agree' first!!

I don’t think this is an 'interpretation issues'. This must be at the 'core' of nature. And I don’t think mixing past, present & future, is going to help us much either.

The answer is most definitely not easy. Just let’s hope it’s logical...

Talking about interpretations, I found this IMO interesting video where Alain Aspect talks about EPR, Albert Einstein & Niels Bohr. Aspect concludes that Einstein & Bohr trusted their interpretations completely, but in the end John Bell showed that they were both wrong!

In the end of the video Anton Zeilinger talks about Quantum Teleportation (entanglement-assisted). Would you enter such a 'machine' without a fundamental understanding of the process?? Talk about FTL transfer/communication!? :smile:

http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Anton-zeilinger-godany-portr%C3%A4t.jpg/400px-Anton-zeilinger-godany-portr%C3%A4t.jpg

Conference Clips With Scientists in Quantum Tamers (2)
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DevilsAvocado

Apr25-10, 07:08 PM

Here are the other 2 clips with Alain Aspect, Anton Zeilinger, Ray Laflame and Joseph Emerson at WCSJ 2009 London, providing more interesting 'aspects' on EPR, measurement and entanglement.

Conference Clips With Scientists in Quantum Tamers (1)
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Conference Clips With Scientists in Quantum Tamers (3)
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Frame Dragger

Apr25-10, 07:13 PM

Interesting stuff, I've got to look over this later when I get the chance. Thanks DA, you know how to keep a fun discussion going. :smile:

DevilsAvocado

Apr25-10, 07:37 PM

Thanks FD! Do check out the videos, interesting stuff!

(And I just love when Aspect, with French 'intensity', shouts – The wool! :smile:)

eveo

Apr25-10, 08:07 PM

University of Waterloo! That's where I'm off to next year for nanotech engineering :D

Frame Dragger

Apr25-10, 08:07 PM

University of Waterloo! That's where I'm off to next year for nanotech engineering :D

Hey, congrats on that!

DevilsAvocado

Apr25-10, 08:19 PM

University of Waterloo! That's where I'm off to next year for nanotech engineering :D
Lucky you!

eveo

Apr25-10, 08:29 PM

Thank you :D
Well, I'm still staying back a year to get higher marks and take a few extra courses to get an increase in scholarship funds :P

SpectraCat

Apr25-10, 08:45 PM

Okay, I think DrC covers the 'basic'.

Very true! I agree! (with 'some' objections below :wink:)

Okay, I know this is true, but I’m going to 'challenge' you a little (so you can show where I go wrong):

Let’s say Bob is a cruel bastard, and Alice is a cat. Bob have arranged a "Schrödinger Box" for Alice so that if the spin is up at Bob, and down at Alice, the "Box" will kill Alice!

Now, it’s hard to argue that Bob don’t know what Alice 'is doing'. He knows if she’s dead or alive...

This "knowledge" is illusory ... if there is a space-like separation between Alice and Bob, then after he has made his measurement in his frame, he cannot know with certainty anything beyond the value of the measurement at Alice, and (this is crucial) he cannot know that Alice's measurement has even taken place until it has been confirmed on a "normal" communication band. The state of Alice's particle is not determined until it is measured, and he cannot be sure that Alice's measurement was not performed first, and that the value he measured was pre-determined because her measurement had already happened. This last point is what we really mean when we say that entangled pairs cannot be used for FTL communication.

Now, Bob may have tried to place external controls on Alice's environment by trapping her in a box with a death-device, but how did he set up the measurement that was to take place. Whatever arrangements he made, once he goes away to make his measurement (at a suitably large distance to make this test case meaningful and interesting), he can only assume without knowing that his arrangements went off without a hitch. Confirmation must wait for the information to arrive by normal light-speed comms.

(of course, Bob cannot control the outcome...)

Yep, and that's the point, as I mentioned above.

I agree on the 'interpretation issues', but at the same time – if we cannot describe in fairly simple and understandable words what’s 'going on', and make logical attachments to current understandings – we’re in deep sh*t, IMO.

Hmmm .. not sure why it should be 'simple and understandable' .. and to whom should it be so? What level of education and familiarity with physics should they have? How many years of schooling?

Well yes, but let’s have a look at the flip side of the coin... Let’s suppose we have arranged a Bell test where the photons run parallel, with a 'photon barrier' between them. Now, after x amount of time the photons hits the polarizer’s. Who is going to decide which one arrives first? The photons!? And if they arrives at exactly the same time (which they should do according to current understanding of physics)? Who is going to do the 'negotiation'?? "The United Council of Photons"??? :wink:

This is a fairly simple logical problem. Two physically separated entities are going to obtain the opposite outcome 100% random, and ONLY ONE can decide. Who decides? And how is this accomplished on distances FTL?

See .. this is why you should have listened to your mother and not gotten involved with those seedy looking QM interpretations!

It does not help if the observers agree. The photons must 'agree' first!!

I don’t think this is an 'interpretation issues'. This must be at the 'core' of nature. And I don’t think mixing past, present & future, is going to help us much either.

The answer is most definitely not easy. Just let’s hope it’s logical...

All joking aside, I guess I see what you are saying here, and suppose it might be a real issue. I am not sure, because I am not sure what "arriving at the same time" means in this context. I'll think about it some more, but it seems like the only way you might be able to define it absolutely is when both photons were impingent on the same detector. Even in that case I think you get into trouble with the HUP when you try to nail things down precisely for the two measurement events. Like I said .. I need to think about it more ...

On final point is that it seems to me that all of your objections are inherently local in character ... don't they all just go away if you accept that the wavefunction of the entangled pair is inherently non-local?

P.S. the vids look cool .. I will check them out when I have time

Phrak

Apr25-10, 09:13 PM

I'm going to ressurect the opening question, hoping for insight:
Is action at a distance possible as envisaged by the EPR Paradox?

Is it action at a distance, or local action based on concepts of locality had by habitual and provably useful methods of mapping spacetime to a coordinate system with expectations extrapolated from Euclidean geometry?

ThomasT

Apr26-10, 08:01 AM

All performed Bell test experiments clearly show that it’s impossible to use local 'entities', whether it’s variable or constant – it just doesn’t work, due to the fact that the receiving polarizer’s are randomly rotated *AFTER* the photons left the source...Whether the polarizer settings are not varied during a run, or varied nonrandomly, or varied randomly, or varied randomly after emission, the result (the correlation between the angular difference of the polarizers and rate of coincidental detection) doesn't vary.

So, the fact that Bell's lhv ansatz "just doesn't work" is NOT "due to the fact that the receiving polarizers are randomly rotated 'AFTER' the photons left the source".

The problem with getting an lhv formulation that fits the experimental results has nothing to do with loopholes.

-------------------------

Try to come up with a set of data points for a Bell test in the Mermin format (I have that on one of my pages). So that is at 0, 120, 240 degrees. You will see that NO realistic theory - local or otherwise - can account for this. Just try to put together the dataset and you will quickly see none is possible. So that seems to rule out all hidden variable theories right there. Let's call this the MAIN RESULT: no hidden variable formulations are possible without outside help.

Ok, lets use a two photon setup where polarization entanglement is produced when two photons are emitted in opposite directions by the same atom. Due to conservation of angular momentum, they're polarized identically.

For the purpose of discussion we can assume an ideal setup (perfect efficiency, all loopholes closed).

The hidden variable is the polarization angle, and it's the same for each member of any pair of entangled photons (though it varies randomly from pair to pair).

Malus Law applies in this situation. We can denote the individual detection rates as,

P(A) = cos2(|a - L|) and
P(B) = cos2(|b - Ll|)

where a and b are polarizer settings and L is the polarization angle of the optical disturbances incident on a and b.

Since the average angular difference between the polarizer setting and L is 45o, then the expected normalized individual detection rates are,

P(A) = .5 and
P(B) = .5

which agrees with QM prediction and experiment.

For the joint detection situation Malus Law also applies since we have crossed polarizers analyzing identically polarized optical emissions.

The relevant independent variable is the angular difference of the polarizer settings, |a-b|, which can be expressed as (||a-L| - |b-L||).

So, we can denoted the joint detection rate as

P(A,B) = cos2(||a-L| - |b-L||)

which agrees with QM prediction and experiment.

Even though this expression for the joint expectation, per se, doesn't explicate locality (as, say, Bell's ansatz purports to but actually doesn't), it is nonetheless a local hidden variable account of entanglement insofar as it (1) incorporates the hidden variable, and (2) the assumptions underlying it are in accord with the principle of local causality.

zonde

Apr26-10, 08:21 AM

Well yes, but this is only your personal 'speculations', right? And I do think you got it somewhat wrong... check my post #108 (http://www.physicsforums.com/showpost.php?p=2685669&postcount=108).
I do not see connection with your post #108 but yes this is my personal speculation that illustrates problems with your personal speculation about this overlapping effect.

About your statement in post #108
The superposition of the particle (photon) is when it passes both slits simultaneously.

Particle = superposition
Wavefunction <> superposition
From wikipedia - superposition principle (http://en.wikipedia.org/wiki/Superposition_principle) states that, for all linear systems,
The net response at a given place and time caused by two or more stimuli is the sum of the responses which would have been caused by each stimulus individually.

So I would restate what you said this way: The condition for superposition of the particle (photon) is that it should pass both slits concurrently.

You make the assumption that the pros making the experiments are 'fighting in the dark', to get some 'exiting results' to flash to the world... anything...
I do not make such assumption.

I’m not in the 'business', but I do know that if a scientist says "Hey! I can prove some weird stuff!", he or she is going to be scrutinized by a lot of very smart people, trying to find any weakness in the claim.

Of course there are swindlers, who make every effort to fool the whole world, but they are rare, and they do not survive the fight against reality, in the long run.
First, scientist do not to say things like "Hey! I can prove some weird stuff!" because they relay on scientific method (http://en.wikipedia.org/wiki/Scientific_method). They say things like "Results of experiment is in agreement with some weird hypothesis." This is because you can not prove theory with experiment but only disprove competing theories.

Second, you don't have to be considered swindler if you make some error. Everybody makes errors but not everybody is swindler.

There is nice picture that I spied in another thread:
http://www.phdcomics.com/comics/archive/phd051809s.gif

So, what have we got? Well, we have a theory that all agrees is mathematical correct and reliable. This theory makes a prediction:

Either X is true or, Y or Z must be violated.

X = Local Hidden Variables
Y = Counterfactual Definiteness (Heisenberg Uncertainty Principle)
Z = Locality
You are not very careful with your statement.
The theory states that if X, Y, Z and determinism then certain inequalities hold.
Besides Counterfactual Definiteness is in conflict with Heisenberg Uncertainty Principle contrary to what you are implying.

Now, we know from the theory that X is not true if we accept that QM is a correct theory (and we all agree that QM is the most precise theory we have). To reverse X to true, we have to abandon QM, and start from scratch.
This is quite loose statement. There are things in QM that are not very strictly established like correspondence between certain things in mathematical formalism and physical reality. Because of that QM still can accommodate quite different interpretations.
So I would say that with some minor changes in interpretation it can still be compatible with (contextual) LHV.

Therefore, the most healthy choice between QM=true/X=false or QM=false/X=true, must naturally be QM=true/X=false.

Y (Heisenberg Uncertainty Principle) is a fundamental part of QM, which we have conclude true, then naturally Y must also be true!

All this is achieved by natural reasoning, common sense, and a very solid theory.

Now, when we start to perform Bell test experiments, every experiment indicates that Y or Z is violated!

What’s the most logical to do in this situation?? Well, it’s not start a "Denial Camp" to reintroduce X as true – it’s way too late for that!!

We are getting the 'expected' results from the experimentalists, and it’s not sound to start questioning if the scientists making the experiments are 'retards' or 'swindlers'...

Come on!

Okay! Let’s start with not throwing the logic away in the evaluation of Bell test experiments! :wink:

RUTA

Apr26-10, 08:31 AM

This is important and I have to be sure.

Causal locality
If we set LHV to be +1 & -1 before sending the photons, we are not violating any locality. It’s just a matter of sending away 'predefined letter' in an 'envelope', and we know the outcome in advance, right...?

Constitutive locality
The receivers of the 'envelope' are physically separated in space-time, i.e. they have no connection FTL, right...?

Causal locality is the "no FTL communication." Constitutive locality is that spacetime events are separable.

Okay, can we 'refine' this and say – According to SEP the 'cause' of EPR is not "spooky action at a distance", it’s 'something else', but SEP can’t say anything about that. (right?)

SEP "doesn't" say anything about what that "something else" is. I don't know that they "can't" say; the author of that definition of nonseparability might have some examples, but they didn't share them :-)

>> This is extremely interesting! <<
Wow! I thought we only had one "problem" with the "spooky action at a distance", but this proves it’s much worse2!!

Let’s see now... IF we assume there ARE "spooky action at a distance" AND the values of the Particles are 100% RANDOM, and the OTHER Particle must obtain the OPPOSITE value instantly. THIS CAN’T BE DONE DUE TO RoS!?!? :surprised

RoS doesn't bear on the nonseparability option. I was pointing out: FTL causes + RoS = a problem, because then you can have event A causing event B even though A occurs after B.

DrChinese

Apr26-10, 09:09 AM

...
Malus Law applies in this situation. We can denote the individual detection rates as,

P(A) = cos2(|a - L|) and
P(B) = cos2(|b - Ll|)

where a and b are polarizer settings and L is the polarization angle of the optical disturbances incident on a and b.

Since the average angular difference between the polarizer setting and L is 45o, then the expected normalized individual detection rates are,

P(A) = .5 and
P(B) = .5

which agrees with QM prediction and experiment.

For the joint detection situation Malus Law also applies since we have crossed polarizers analyzing identically polarized optical emissions.

The relevant independent variable is the angular difference of the polarizer settings, |a-b|, which can be expressed as (||a-L| - |b-L||).

So, we can denoted the joint detection rate as

P(A,B) = cos2(||a-L| - |b-L||)

which agrees with QM prediction and experiment.

Sorry, this most definitely does NOT agree with experiment and the math is wrong. In fact the coincidence rate varies between .25 and .75 per your example. Experiment has it varying between 0 and 1.

See where your P(A)=.5 and p(B)=.5? That is correct. But it does not lead to your result. For example, where A=0 and B=0, you will NOT get correlation of 100% UNLESS you have entangled photons. Unentangled photons would have the same math as you describe but yield Product statistics. They are NOT the same. Yet they should be, according to you.

This is a frequent mistake that folks make in attempting to come up with local hidden variable models. You must model BOTH of these following cases successfully:

a) Polarization entangled photon pairs yield perfect correlations and entangled state statistics (the cos^2(theta) rule);

b) Polarization UNentangled photon pairs - coming from the same PDC crystal as in a) - yield Product State statistics (.25 + .5(cos^2(theta)). With these, the polarization is known, which is why they are not entangled.

Your example models b) and not a). If I need to, I will be glad to derive this for you in a later post. Or you can do it, but you must put in the correct values for the expansion.

ThomasT

Apr26-10, 11:09 AM

Sorry, this most definitely does NOT agree with experiment and the math is wrong. In fact the coincidence rate varies between .25 and .75 per your example.I think you've got it backwards.

As the angular difference, |a - b| = ||a - L| - |b - L||, goes from 0o to 90o, the cos2 of that angular difference goes from 1 to 0.

Experiment has it varying between 0 and 1.The experiments I've seen have it varying between 0 and .5, and it never quite reaches those limits. It can't go to 1 if the individual detection rates never exceed .5 .

The correct expression for an idealized setup, normalized joint detection rate is, then,

.5 (cos2(|a-b|) ,

which would be modified depending on whatever inefficiencies are involved in the actual production of the data.

By the way, the normalization is wrt the detection rate with no polarizers present.

See where your P(A)=.5 and p(B)=.5? That is correct. But it does not lead to your result.It can't. Isn't that what we've been discussing?

For example, where A=0 and B=0, you will NOT get correlation of 100% UNLESS you have entangled photons. Unentangled photons would have the same math as you describe but yield Product statistics. They are NOT the same. Yet they should be, according to you.If you mean A and B to refer to detection rates, then the normalized individual rates with polarizers in place at both ends is always, in the ideal, A = .5 and B = .5 . If not, then I don't know what you're saying.

a) Polarization entangled photon pairs yield perfect correlations and entangled state statistics (the cos^2(theta) rule);

b) Polarization UNentangled photon pairs - coming from the same PDC crystal as in a) - yield Product State statistics (.25 + .5(cos^2(theta)). With these, the polarization is known, which is why they are not entangled.

Your example models b) and not a).It accounts for a) in the assumptions underlying the application of Malus Law and the model(s) of the production of the entanglement via the emission process. Keep in mind that the perfect correlation/anticorrelation corresponding to angular differences of 0o and 90o have always been explainable assuming a local common cause for the entanglement.

RUTA

Apr26-10, 11:16 AM

AFAICS, RoS is a non-issue for this case.

Correct, RoS doesn't bear on nonseparability. It does, of course, bear on the nonlocality issue, as I pointed out in post #140.

There is no question of causality here, only comparison of measurement. There is no logical inconsistency in a frame where B was measured before A or vice-versa, because the results are perfectly correlated.

QM predicts the correlations between space-like separated experimental outcomes that violate Bell inequalities, that's not the issue. The question QM doesn't answer is, "What is the nature of reality such that correlations between space-like separated experimental outcomes violate Bell inequalities?" For some people, the answer is FTL communication between the measurement events. For those people, RoS becomes an issue.

IOW, if you measure B first, you determine the value of A, if you measure A first, you determine the value of B. This holds in all frames, for all observers, so IMO there is no problem.

The problem with "if you measure B first, you determine the value of A" when A and B are space-like separated is that, per RoS, there is no absolute temporal ordering of A and B. So, what does "if you measure B first" really mean?

Furthermore, when observers in different frames compare answers (as is required for a Bell test), they may disagree on the ordering of events, but they will always agree that there is a Bell violation for the results.

Correct.

RUTA

Apr26-10, 11:35 AM

To reiterate, from a QM point of view, there are two measurements performed on the members of an entangled pair. Since the results are always perfectly correlated, it fundamentally does not matter which measurement comes first, at least for the purposes of Bell tests. All observers in all frames agree on the results of the measurements, once they have communicated them by normal sub-lightspeed channels for comparison.

The strange nature of the correlated outcomes is not illucidated by the measurements for which there is 100% correlation alone. One can imagine there is a "fact of the matter" for the outcomes corresponding to those measurement settings (like settings). But, if you assume there is a "fact of the matter" for the outcomes corresponding to like settings (in order to account for the 100% correlation), then you don't obtain the correct (QM predicted) correlation rate for outcomes in unlike settings. Thus, some people invoke FTL communication of settings between measurements so the particles can "give the right outcomes" no matter how they're measured.

DrChinese

Apr26-10, 11:45 AM

I think you've got it backwards.

As the angular difference, |a - b| = ||a - L| - |b - L||, goes from 0o to 90o, the cos2 of that angular difference goes from 1 to 0.

The experiments I've seen have it varying between 0 and .5, and it never quite reaches those limits. It can't go to 1 if the individual detection rates never exceed .5 .

The correct expression for an idealized setup, normalized joint detection rate is, then,

.5 (cos2(|a-b|) ,

which would be modified depending on whatever inefficiencies are involved in the actual production of the data.

By the way, the normalization is wrt the detection rate with no polarizers present.

It can't. Isn't that what we've been discussing?

If you mean A and B to refer to detection rates, then the normalized individual rates with polarizers in place at both ends is always, in the ideal, A = .5 and B = .5 . If not, then I don't know what you're saying.

No. It models a). Keep in mind that the perfect correlation/anticorrelation corresponding to angular differences of 0o and 90o have always been explainable assuming a local common cause for the entanglement.

OK, first let's agree that there are 2 types of PDC. We can discuss either one, but I personally think it is easier to discuss Type I. With Type I, both photons have identical polarization. With Type II, the photons have anti-symmetric/orthogonal/crossed/opposite polarization.

It makes no difference to the result whether we are going from 0 to 1 or 1 to 0, when moving from 0 to 90 degrees apart. So I will use the Type I example.

Second: the joint detection rate is NOT cos^2(theta) in your example. It is actually .25+.5(cos^2(theta)) which is obviously different. This is the Product State statistics.

Remember: we are talking about your example. IF you take a pair of PDC photons at any KNOWN angle (the hypothesized L in your example) and actually check their polarizations at any angle settings A and B, THEN you will get .25+.5(cos^2(A-B)). That is an experimental fact.

What may be confusing is that PDC photon pairs can come out either polarization entangled or not. Either way, they have identical polarization! If the polarization is known, it is not entangled. You hypothesize that there is a definite polarization L associated with the photons. If there were such, then the expected statistics are PRODUCT state.

If, on the other hand, you specify that there is no definite polarization L, then you would have entanglement. But of course, then you would be accepting that no LHV can reproduce the predictions of QM - exactly what you wish to avoid. Of course, everyone else (save a diehard few) already accepts this.

DrChinese

Apr26-10, 11:52 AM

Keep in mind that the perfect correlation/anticorrelation corresponding to angular differences of 0o and 90o have always been explainable assuming a local common cause for the entanglement.

Yes and No. YES: there have been models that could explain some situations such as these special cases. But NO: your model is NOT one of those. Those models are different. In effect, they postulate that there are a large (and perhaps infinite) number of hidden variables associated with the range of polarization settings. For simplicity, imagine that there is: HV(1), HV(2),... HV(359, HV(360).

Of course, this model "fixes" the problem with your model. But at a cost. Because now you just fell prey to Bell :biggrin: and the problem of being able to provide a realistic resultset for the 3 angles I specified (0/120/240 a la Mermin). You cannot do it - but please feel free to try!!

RUTA

Apr26-10, 12:04 PM

Ok, lets use a two photon setup where polarization entanglement is produced when two photons are emitted in opposite directions by the same atom. Due to conservation of angular momentum, they're polarized identically.

For the purpose of discussion we can assume an ideal setup (perfect efficiency, all loopholes closed).

The hidden variable is the polarization angle, and it's the same for each member of any pair of entangled photons (though it varies randomly from pair to pair).

Malus Law applies in this situation. We can denote the individual detection rates as,

P(A) = cos2(|a - L|) and
P(B) = cos2(|b - Ll|)

where a and b are polarizer settings and L is the polarization angle of the optical disturbances incident on a and b.

Since the average angular difference between the polarizer setting and L is 45o, then the expected normalized individual detection rates are,

P(A) = .5 and
P(B) = .5

which agrees with QM prediction and experiment.

For the joint detection situation Malus Law also applies since we have crossed polarizers analyzing identically polarized optical emissions.

The relevant independent variable is the angular difference of the polarizer settings, |a-b|, which can be expressed as (||a-L| - |b-L||).

So, we can denoted the joint detection rate as

P(A,B) = cos2(||a-L| - |b-L||)

which agrees with QM prediction and experiment.

Even though this expression for the joint expectation, per se, doesn't explicate locality (as, say, Bell's ansatz purports to but actually doesn't), it is nonetheless a local hidden variable account of entanglement insofar as it (1) incorporates the hidden variable, and (2) the assumptions underlying it are in accord with the principle of local causality.

I don't see how you obtained your P(A,B) other than by fiat.

Suppose you say the photons pass a polarizer (vertically polarized wrt the setting, typically denoted V) if their polarization L is within 45 deg of the setting. Between 45 deg and 90 deg the photons are blocked (horizontally polarized wrt the setting, typically denoted H). This is a reasonable assumption and leads to an overall 50% rate for V at each detector. Now, what is the probability of a VV outcome for settings A and B? The answer is 0.5 - |A - B|/pi, which you can obtain by simply drawing the 45-deg cones about settings A and B and looking at their overlap. For a detailed explanation, see equation 19, p 907, of section VIII. Local Realistic Hidden Variable Theory, in "Entangled photons, nonlocality, and Bell inequalities in the undergraduate laboratory," Dietrich Dehlinger and M.W. Mitchell, Am. J. Phys. 70 (9), Sep 2002.

ThomasT

Apr26-10, 12:10 PM

OK, first let's agree that there are 2 types of PDC. We can discuss either one, but I personally think it is easier to discuss Type I. With Type I, both photons have identical polarization. With Type II, the photons have anti-symmetric/orthogonal/crossed/opposite polarization.

It makes no difference to the result whether we are going from 0 to 1 or 1 to 0, when moving from 0 to 90 degrees apart. So I will use the Type I example.

Second: the joint detection rate is NOT cos^2(theta) in your example. It is actually .25+.5(cos^2(theta)) which is obviously different. This is the Product State statistics.

Remember: we are talking about your example. IF you take a pair of PDC photons at any KNOWN angle (the hypothesized L in your example) and actually check their polarizations at any angle settings A and B, THEN you will get .25+.5(cos^2(A-B)). That is an experimental fact.

What may be confusing is that PDC photon pairs can come out either polarization entangled or not. Either way, they have identical polarization! If the polarization is known, it is not entangled. You hypothesize that there is a definite polarization L associated with the photons. If there were such, then the expected statistics are PRODUCT state.

If, on the other hand, you specify that there is no definite polarization L, then you would have entanglement. But of course, then you would be accepting that no LHV can reproduce the predictions of QM - exactly what you wish to avoid. Of course, everyone else (save a diehard few) already accepts this.If you reread the post where I introduced this you'll see that I wasn't talking about SPDC photons.

The counter-propagating photons emitted by the same atom in my example are always entangled in polarization due to conservation of angular momentum. This entanglement means that members of an entangled pair are polarized identically. However, the value of L, the polarization angle of any given pair, is varying randomly.

ThomasT

Apr26-10, 12:23 PM

I don't see how you obtained your P(A,B) other than by fiat. Not by fiat. Malus Law is applied and the angular difference is simply rendered in terms of the hidden variable.

RUTA

Apr26-10, 12:26 PM

Not by fiat. Malus Law is applied and the angular difference is simply rendered in terms of the hidden variable.

Why did you apply Malus Law?

DrChinese

Apr26-10, 12:34 PM

If you reread the post where I introduced this you'll see that I wasn't talking about SPDC photons.

The counter-propagating photons emitted by the same atom in my example are always entangled in polarization due to conservation of angular momentum. This entanglement means that members of an entangled pair are polarized identically. However, the value of L, the polarization angle of any given pair, is varying randomly.

Sorry, you are making an important mistake here. Yes, it is true that the photons you describe from the atom are entangled. However, the model you describe is NOT the same. Instead, it matches the PDC polarization unentangled situation I described above. You cannot say your model works if you apply it to the wrong situation. There is a GIANT different in Entangled State stats and Product State stats. Your example - where there is a definite polarization L - only matches the Product State situation. This is a very important distinction and you need to understand this. It is probably the reason you have had trouble seeing some of the arguments we have provided in the past.

ThomasT

Apr26-10, 12:39 PM

Why did you apply Malus Law?Wrt each trial, two identically polarized optical disturbances are being analyzed by crossed linear polarizers.

Why is Malus Law applied in the QM treatment?

DrChinese

Apr26-10, 12:43 PM

Not by fiat. Malus Law is applied and the angular difference is simply rendered in terms of the hidden variable.

As RUTA is also trying to tell you: Application of Malus as you are trying will NOT yield Entangled State stats. Please note that it is true that Malus is a cos^2 function, and so are the Entangled State statistics. But how you apply these are different for different experimental situations.

a) Application of Malus to (A-L) and (B-L) does NOT lead to Malus for (A-B) as you imagine. It leads to different stats, as I have already told you.

b) The reason you apply Malus to entangled pairs is because of the superposition of states: HH> + VV>. When you then apply rotation to the superposition, rotating by some A or B, you end up with an expression that simplifies to cos^2(A-B).

The Dehlinger reference derives this.

ThomasT

Apr26-10, 12:44 PM

Suppose you say the photons pass a polarizer (vertically polarized wrt the setting, typically denoted V) if their polarization L is within 45 deg of the setting. Between 45 deg and 90 deg the photons are blocked (horizontally polarized wrt the setting, typically denoted H). This is a reasonable assumption and leads to an overall 50% rate for V at each detector. Now, what is the probability of a VV outcome for settings A and B? The answer is 0.5 - |A - B|/pi, which you can obtain by simply drawing the 45-deg cones about settings A and B and looking at their overlap. For a detailed explanation, see equation 19, p 907, of section VIII. Local Realistic Hidden Variable Theory, in "Entangled photons, nonlocality, and Bell inequalities in the undergraduate laboratory," Dietrich Dehlinger and M.W. Mitchell, Am. J. Phys. 70 (9), Sep 2002.All we have are averages. Photon counts per run are accounted for. There are no probabilities for the results of individual trials.

ThomasT

Apr26-10, 12:50 PM

Yes and No. YES: there have been models that could explain some situations such as these special cases. But NO: your model is NOT one of those. Those models are different. In effect, they postulate that there are a large (and perhaps infinite) number of hidden variables associated with the range of polarization settings. For simplicity, imagine that there is: HV(1), HV(2),... HV(359, HV(360).

Of course, this model "fixes" the problem with your model. But at a cost. Because now you just fell prey to Bell :biggrin: and the problem of being able to provide a realistic resultset for the 3 angles I specified (0/120/240 a la Mermin). You cannot do it - but please feel free to try!!The perfect correlation/anticorrelation corresponding to angular differences of 0o and 90o are accounted for by the identical polarizations of the members of each entangled pair.

DrChinese

Apr26-10, 12:53 PM

Wrt each trial, two identically polarized optical disturbances are being analyzed by crossed linear polarizers.

Why is Malus Law applied in the QM treatment?

See the Dehlinger paper. Although it really doesn't matter for your particular model, because yours gives completely different results than experiment even for the perfect correlations cases.

On the other hand, Dehlinger describes a DIFFERENT LHV than yours - as an example - and shows how it falls apart. But his works for the perfect correlation cases, which is more or less what EPR envisioned.

DrChinese

Apr26-10, 12:56 PM

The perfect correlation/anticorrelation corresponding to angular differences of 0o and 90o are accounted for by the identical polarizations of the members of each entangled pair.

No, they are not. Try it and you will see.

L=30 degrees
A=0 degrees
B=90 degrees

cos^2(A-L) * cos^2(B-L) = [Not 0 or 1 as QM predicts]

ThomasT

Apr26-10, 01:08 PM

As RUTA is also trying to tell you: Application of Malus as you are trying will NOT yield Entangled State stats. Please note that it is true that Malus is a cos^2 function, and so are the Entangled State statistics. But how you apply these are different for different experimental situations.Malus Law applies because of the physical setup.

Application of Malus to (A-L) and (B-L) does NOT lead to Malus for (A-B) as you imagine.Malus Law applies in the individual trials because we have an optical disturbance with an unknown polarization L being analyzed by a linear polarizer with a certain setting. The interaction of the incident disturbance with the polarizer yields a resultant disturbance with intensity proportional to cos2|a - L|.

I've already explained the physical reasoning behind the application of Malus Law applies in the joint context.

DrChinese

Apr26-10, 01:18 PM

Malus Law applies because of the physical setup.

Malus Law applies in the individual trials because we have an optical disturbance with an unknown polarization L being analyzed by a linear polarizer with a certain setting. The interaction of the incident disturbance with the polarizer yields a resultant disturbance with intensity proportional to cos2|a - L|.

I've already explained the physical reasoning behind the application of Malus Law applies in the joint context.

You may as well say dogs quack*. Malus does not apply to your setup. Please work through the example I gave above and you will immediately see that the math fails. Sorry, there is nothing gray about your example. If you apply Malus to A-L and to B-L, you don't also get Malus for A-B.

*Although I should add that my dog is so weird, she may as well quack.

RUTA

Apr26-10, 01:30 PM

All we have are averages. Photon counts per run are accounted for. There are no probabilities for the results of individual trials.

I derived the probability per trial using a particular lhv model. The assumption that such a probability will correspond to the frequencies of outcomes in actual experiments is a particular (and still debated in philosophical circles) interpretation of the meaning of "probability." In physics, we take this for granted and it works, so ... .

DrC has answered your other questions. I suggest you read the AJP paper I referenced. Work through all the calculations to make sure you understand them. If you need help, send me your questions. I have my intro QM students supply all the missing calcs in that paper as an exercise. Caveat: There are some typos in his equations but if you understand what he's doing, you'll catch those easy enough.

Frame Dragger

Apr26-10, 01:42 PM

ThomasT, what is your fascination with Malus' Law? This is sounding more and more like a pet theory or an article of faith.

DrChinese

Apr26-10, 01:43 PM

If you need help, send me your questions. I have my intro QM students supply all the missing calcs in that paper as an exercise. Caveat: There are some typos in his equations but if you understand what he's doing, you'll catch those easy enough.

A very kind offer. :smile:

I hope I remember this thread the next time ThomasT brings this subject up. Now I understand better where he is coming from.

ThomasT

Apr26-10, 02:20 PM

No, they are not. Try it and you will see.

L=30 degrees
A=0 degrees
B=90 degrees

cos^2(A-L) * cos^2(B-L) = [Not 0 or 1 as QM predicts]You're evaluating the expression incorrectly. But, yes, there's still a problem. Maybe |a - b| can't be expressed in terms of the hidden variable or maybe there's some simple fix. In either case, cos2|a - b| does give the correct result for all values of a, b and L.

Since this is an expression of Malus Law, then the question is: does Malus Law actually apply simply because we're analyzing identically polarized optical disturbances with crossed linear polarizers?

DrChinese

Apr26-10, 02:28 PM

You're evaluating the expression incorrectly.

Ok, say we have:

A=0
B=0
L=45 degrees

p(A, heads) = cos^2(A-L) = .5
p(B, heads) = cos^2(A-L) = .5
p(A and B, heads) = .25

p(A, tails) = cos^2(A-L) = .5
p(B, tails) = cos^2(A-L) = .5
p(A and B, tails) = .25

Per your model, the matches will be .25 + .25 or 50% of the time.

But entangled A and B give both as matches 100% of the time.

ThomasT

Apr26-10, 02:30 PM

You may as well say dogs quack*. Malus does not apply to your setup.Actually, it applies whenever you're analyzing polarization.

If you apply Malus to A-L and to B-L, you don't also get Malus for A-B.The application of Malus Law gives the correct results in the individual as well as joint contexts. Now, can we express the angular difference in terms of the hidden variable? If we can then we have a local hidden variable account. If not then we just have a local account.

DrChinese

Apr26-10, 02:33 PM

Actually, it applies whenever you're analyzing polarization.

The application of Malus Law gives the correct results in the individual as well as joint contexts. Now, can we express the angular difference in terms of the hidden variable? If we can then we have a local hidden variable account. If not then we just have a local account.

If you are not going to do any work on this issue yourself, you won't see me continuing to try to assist you. Work the math yourself following my example and read the Dehlinger paper too.

RUTA

Apr26-10, 03:02 PM

Actually, it applies whenever you're analyzing polarization.
The application of Malus Law gives the correct results in the individual as well as joint contexts.

I still don't understand where you're getting this result because you're not providing a state or a physical mechanism. You're simply claiming that Malus Law applies to the analysis of polarization experiments, but that's not true in general. The correlation outcome is state dependent, so the result you're calling Malus Law (.5cos^2(A - B)) is only true for a specific QM situation. You're claiming to obtain this formula without specifying the context, so there are certainly many experiments that would not agree with your prediction. For example, in Dehlinger and Mitchell's experimental set up they find the probability of a VV outcome for settings A and B is:

sin^2(A)*sin^2(B)*cos^2(theta) + cos^2(A)*cos^2(B)*sin^2(theta) + .25*sin(2A)*sin(2B)*sin(2theta)*cos(phi).

They don't get the simple .5cos^2(A - B) because their equipment doesn't produce the state (|HH> + |VV>)/sqrt(2). Instead, their equipment produces the state

cos(theta)*|HH> + exp[i*phi]*sin(theta)*|VV>.

That's why I explained the lhv equation (section VIII of their paper) in such detail. It's not true that Malus Law applies to all polarization experiments. You have to derive what is true and sometimes it is Malus Law, but you can't simply posit Malus Law as providing the correlation rate in all polarization experiments, b/c it's not true in general.

DrChinese

Apr26-10, 03:20 PM

That's why I explained the lhv equation (section VIII of their paper) in such detail. It's not true that Malus Law applies to all polarization experiments. You have to derive what is true and sometimes it is Malus Law, but you can't simply posit Malus Law as providing the correlation rate in all polarization experiments, b/c it's not true in general.

Yes, in fact I was tripped up sadly on that once. For example, suppose you have 3 polarization entangled photons. They do not follow the cos^2(theta) rule. Tez had to correct me on that one.

ThomasT

Apr26-10, 03:37 PM

Ok, say we have:

A=0
B=0
L=45 degrees

p(A, heads) = cos^2(A-L) = .5
p(B, heads) = cos^2(A-L) = .5
p(A and B, heads) = .25

p(A, tails) = cos^2(A-L) = .5
p(B, tails) = cos^2(A-L) = .5
p(A and B, tails) = .25

Per your model, the matches will be .25 + .25 or 50% of the time.No. Wrt the setup I described there are no tails. Wrt my account (I wouldn't call it a model, per se) P(A,B) = cos2(|a - b|).

The problem is in expressing |a - b| in terms of the hidden variable. It might not be possible. But even if not, it's still a local account due to my Malus Law rationalization. :smile:

DrChinese

Apr26-10, 03:46 PM

No. Wrt the setup I described there are no tails. Wrt my account (I wouldn't call it a model, per se) P(A,B) = cos2(|a - b|).

What do you mean there are no tails? All actual experiments give you a 1/0, Y/N, Heads/tails boolean result.

And if you are not putting forth a model, then what are you arguing? The whole point of this discussion is to convince you that you CANNOT construct such a model.

ThomasT

Apr26-10, 04:19 PM

What do you mean there are no tails? All actual experiments give you a 1/0, Y/N, Heads/tails boolean result.We're counting photons, detections. Not nondetections.

And if you are not putting forth a model, then what are you arguing? The whole point of this discussion is to convince you that you CANNOT construct such a model.It's only a model if |a - b| can be expressed in a way that includes L without contradiction. :smile: I think there might be a way to do it.

DrChinese

Apr26-10, 04:31 PM

We're counting photons, detections. Not nondetections.

Most Bell tests no longer use that technique because it is inferior. By using a polarizing beamsplitter (PBS) with separate detectors for both outputs, you get a more definite statement.

Obviously, there is a way to adjust the counts to match your setup. And you still get the wrong answer.

ThomasT

Apr26-10, 04:41 PM

I still don't understand where you're getting this result because you're not providing a state or a physical mechanism. You're simply claiming that Malus Law applies to the analysis of polarization experiments, but that's not true in general. The correlation outcome is state dependent, so the result you're calling Malus Law (.5cos^2(A - B)) is only true for a specific QM situation. You're claiming to obtain this formula without specifying the context, so there are certainly many experiments that would not agree with your prediction. For example, in Dehlinger and Mitchell's experimental set up they find the probability of a VV outcome for settings A and B is:

sin^2(A)*sin^2(B)*cos^2(theta) + cos^2(A)*cos^2(B)*sin^2(theta) + .25*sin(2A)*sin(2B)*sin(2theta)*cos(phi).

They don't get the simple .5cos^2(A - B) because their equipment doesn't produce the state (|HH> + |VV>)/sqrt(2). Instead, their equipment produces the state

cos(theta)*|HH> + exp[i*phi]*sin(theta)*|VV>.

That's why I explained the lhv equation (section VIII of their paper) in such detail. It's not true that Malus Law applies to all polarization experiments. You have to derive what is true and sometimes it is Malus Law, but you can't simply posit Malus Law as providing the correlation rate in all polarization experiments, b/c it's not true in general.That's why I used an experimental setup where Malus Law does clearly apply.

RUTA

Apr26-10, 04:45 PM

That's why I used an experimental setup where Malus Law does clearly apply.

I haven't seen you derive your coincidence rate. If you've done that, please tell me the post number. If not, please derive it now.

Frame Dragger

Apr26-10, 05:15 PM

Most Bell tests no longer use that technique because it is inferior. By using a polarizing beamsplitter (PBS) with separate detectors for both outputs, you get a more definite statement.

Obviously, there is a way to adjust the counts to match your setup. And you still get the wrong answer.

When is it alright to accuse someone of not knowing what the hell they're talking about?! I know that this is a civilized forum, but come on...

@ThomasT: Show some work, that WORKS, and until then stop taking the painfully long way around to finding that your assumptions are baseless. PLEASE.

DevilsAvocado

Apr26-10, 07:24 PM

...didn’t we run this debate previously – about the 'detection' loophole...??

Anyhow for myself and any other layman out there, let’s reconcile:
Wikipedia - Malus Law (http://en.wikipedia.org/wiki/Malus%27_law#Malus.27_law_and_other_properties)
Malus' law, which is named after Etienne-Louis Malus, says that when a perfect polarizer is placed in a polarized beam of light, the intensity, I, of the light that passes through is given by ... (yada, yada, yada) ... In practice, some light is lost in the polarizer and the actual transmission of unpolarized light will be somewhat lower than this, around 38% for Polaroid-type polarizers but considerably higher (>49.9%) for some birefringent prism types.

Who is Etienne-Louis Malus? Well, he’s this guy:
http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Etienne-Louis_Malus.jpg/320px-Etienne-Louis_Malus.jpg
A participant in Napoleon's expedition into Egypt (1798 to 1801)

Can we start a poll... if this Napoleon-guy is going to win the battle between QM and ... and ... the Waterloophole Theory Fernwirkung (!?WTF!?) ...

:biggrin:

Frame Dragger

Apr26-10, 08:24 PM

...didn’t we run this debate previously – about the 'detection' loophole...??

Anyhow for myself and any other layman out there, let’s reconcile:

Who is Etienne-Louis Malus? Well, he’s this guy:
http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Etienne-Louis_Malus.jpg/320px-Etienne-Louis_Malus.jpg
A participant in Napoleon's expedition into Egypt (1798 to 1801)

Can we start a poll... if this Napoleon-guy is going to win the battle between QM and ... and ... the Waterloophole Theory Fernwirkung (!?WTF!?) ...

:biggrin:

:rofl: Oooh... for a guy who's said that English is not your first language, you have a keen sense of wielding it for the sake of humour and making a point. I think yours was a fairly... direct way of explaining the "apples and oranges" concept to ThomasT. Malus' Law is certainly useful (sort of)... it just has nothing at all to do with the issue at hand! :grumpy:

DevilsAvocado

Apr27-10, 06:47 AM

Hehe, of course Etienne-Louis Malus is completely innocent – he’s just a victim to his "apples" being used to prove that "oranges" do not exist, by "someone"...
English is not your first language
Correct, but the "Swedish Chef" has taught me almost everything there is to know! :biggrin:

Thanks!

SpectraCat

Apr27-10, 07:29 AM

..

Correct, but the "Swedish Chef" has taught me almost everything there is to know! :biggrin:

Bork Bork Bork!

At his finest: http://www.youtube.com/watch?v=EDFgtFXfnv0

DevilsAvocado

Apr27-10, 08:38 AM

Bork Bork Bork!

Hahaha!! :rofl: "After that – I’m running away!!!"

(but I’ll be back to reply the rest ASAP)

yoda jedi

Apr27-10, 12:30 PM

No. The properties, motion(s) of the entangled particles that are being jointly analyzed are either identical or closely related in some way due to past interaction(s), a common source, or they're parts of an encompassing system.

So there really doesn't need to be any communication or causal link of any sort between the separated particles in order to understand why joint detections of them are correlated wrt some global measurement parameter(s).

That's right, but that statement needs some qualification. In the contexts where joint detection attributes are correlated to global measurement parameters the hidden variable that would, if it were known, allow more precise prediction of individual results is simply not relevant.

What's relevant in the joint context is the relationship between the two separated particles.

The oft repeated statement that QM is incompatible with local hidden variables isn't quite true. QM is compatible with lhv formulations of certain setups, such as wrt the individual arms of optical Bell tests. QM is incompatible with lhv formulations of setups where the lhv is irrelevant wrt determining the results, such as wrt the correlations of joint results with some global measurement parameter.

'Way out' of what -- nonlocality? What nonlocality? If you think that it can be inferred via experimental violations of Bell inequalities or via GHZ inconsistencies, then consider that the physical meaning attributed to BIs and GHZ manipulations associated with Bell tests is rather questionable.

You might start a separate thread exploring exactly how BIs are derived and exactly how the limits imposed by them are connected with the reality of the experimental setups -- and also exactly how the detection attributes (+1s and -1s) involved in GHZ manipulations are connected to EPR elements of reality.

It isn't at all a foregone conclusion, nor has it been definitively demonstrated, that experimental violations of BIs or GHZ inconsistencies have the physical meaning that's been attributed to them by some -- that is, quantum entanglement should not be taken as being synonymous with nonlocality or ftl propagations.

and not the only, to rule out locality.

DevilsAvocado

Apr27-10, 07:51 PM

Now, Bob may have tried to place external controls on Alice's environment by trapping her in a box with a death-device, but how did he set up the measurement that was to take place. Whatever arrangements he made, once he goes away to make his measurement (at a suitably large distance to make this test case meaningful and interesting), he can only assume without knowing that his arrangements went off without a hitch. Confirmation must wait for the information to arrive by normal light-speed comms.

Of course you’re right – the "hitch-factor" can never be ruled out.

Doesn’t this also have influence on Schrödinger's cat? Copenhagen interpretation implies that the cat remains both alive and dead until the box is opened (= 50/50), but if we apply the "hitch-factor", we get Alive 33% / Dead 33% / Hitch 33% = Dead 33% and Alive 66% ...?

And the ('new') Copenhagen interpretation would then be – the cat is more alive than dead until the box is opened!

http://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Schrodingers_cat.svg/400px-Schrodingers_cat.svg.png

(dead serious discovery! :smile:)

Hmmm .. not sure why it should be 'simple and understandable' .. and to whom should it be so? What level of education and familiarity with physics should they have? How many years of schooling?

To everyone! :wink: To make a 'slightly' sensational allegory (FTL=false):

A father is standing with his son on the lawn, and the son suddenly squeals. Then father & son observe a wasp flying towards them, landing on the arm of the son and sting him. After the traumatic event, son is asking – What happened!?

In a logical world, the father says – Well son, this is absolutely nothing to worry about. Science can explain these things, and if you do what I tell you and become a physicist, you will understand this 100%.

In an illogical world, the father says – Well son, sh*t happens all the time before you know it! And if I can live with this, so can you!! Be quiet and GO TO BED!!!!

Get it? :smile:

See .. this is why you should have listened to your mother and not gotten involved with those seedy looking QM interpretations!
:biggrin:

All joking aside, I guess I see what you are saying here, and suppose it might be a real issue. I am not sure, because I am not sure what "arriving at the same time" means in this context. I'll think about it some more, but it seems like the only way you might be able to define it absolutely is when both photons were impingent on the same detector. Even in that case I think you get into trouble with the HUP when you try to nail things down precisely for the two measurement events. Like I said .. I need to think about it more ...

On final point is that it seems to me that all of your objections are inherently local in character ... don't they all just go away if you accept that the wavefunction of the entangled pair is inherently non-local?

Well yes, sort of... but it does seem to me we a slight 'problem' on our hands... When A & B are far away from each other, we refer to SR and RoS. When A & B are at the 'same parallel place', separated by an 'insulator', we refer to QM and HUP...? Hmmm...

Anyhow, since the last post I have had some kind of 'revelation'. Last night I watched public television, to get my mind of the EPR stuff, and what do they show?? The Perimeter Institute for Theoretical Physics - The Quantum Tamers, with Stephen Hawking, Alain Aspect, Anton Zeilinger, Gerard Milburn, Wojciech Zurek, Raymond Laflamme, Peter Shor, Seth Lloyd, Lucien Hardy, Daniel Gottesman, et al!! Is this just a COINCIDENCE!? :biggrin:

In the program Anton Zeilinger talks about entanglement, and that Erwin Schrödinger in 1935 (in the course of developing "Schrödinger's cat") coined the term Verschränkung.

Entanglement in English means something like 'spaghetti', but Verschränkung in German means "very strong, very well defined connection", according to Zeilinger.

I looked up Verschränkung (http://www.dict.cc/german-english/Verschr%C3%A4nkung.html) in a German-English dictionary and got:

interleave
interconnection
folding
crossing
clasping

This is obviously something completely different than 'spaghetti', which is not that well-defined!! Zeilinger visualize Verschränkung like this:

http://i44.tinypic.com/2cpb4ia.png

In this new light, there is no doubt that the entangled pair is a (combined?) wavefunction, not two separate particles!!

Now I have a question: How can we know that the wavefunction has this property of opposite spin? According to QM we can’t apply any property to a wavefunction before measurement?? And some say – the wavefunction doesn’t even 'exist'!?

For those curios about "The Perimeter Institute for Theoretical Physics - The Quantum Tamers", here is a link to the first episode. The part about entanglement and EPR starts at 15:50 and ends at 25:40. Don’t worry about the Swedish speaker, it’s just a few sec, and the important stuff comes from the scientist in English:

http://i42.tinypic.com/do2smv.png (http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.ur.se%2Fplay%2F156548&sl=sv&tl=en)

Website translated to English (http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.ur.se%2Fplay%2F156548&sl=sv&tl=en)
Original Swedish (http://www.ur.se/play/156548)

Enjoy! It’s available until 25-oct-2010.

P.S. Check out The Perimeter Institute for Theoretical Physics - The Quantum Tamers (http://www.perimeterinstitute.ca/Outreach/Quantum_Tamers/The_Quantum_Tamers/) there are more interesting videos, as this one Alain Aspect – From Einstein's Intuition to Quantum Bits (https://www.perimeterinstitute.ca/index.php?option=com_content&task=view&id=551&Itemid=568&lecture_id=6433).

SpectraCat

Apr28-10, 05:58 PM

Wait ... what happened to Frame Dragger? Did he get banned?

DevilsAvocado

Apr28-10, 06:04 PM

I dunno... :uhh: ...really hope not... :cry:

DevilsAvocado

Apr28-10, 06:30 PM

Whether the polarizer settings are not varied during a run, or varied nonrandomly, or varied randomly, or varied randomly after emission, the result (the correlation between the angular difference of the polarizers and rate of coincidental detection) doesn't vary.

So, the fact that Bell's lhv ansatz "just doesn't work" is NOT "due to the fact that the receiving polarizers are randomly rotated 'AFTER' the photons left the source".
'AFTER' was the last nail in the coffin for LHV. There was a theoretical possibility that the entangled photons had 'spooky tentacles' that could 'sense' the settings of the polarizer, to pre-agree on LHV, and then run to 'mimic' the QM predictions. Why else all this work on randomizing the polarizers??

(I googled "Bell's lhv ansatz" and got 2 hits, both pointing at you at PF... is this your own 'invention'?)

The problem with getting an lhv formulation that fits the experimental results has nothing to do with loopholes.

Correct, it has to do with Bell's theorem – "No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics". Here’s one of Alain Aspect’s own slides:

http://i39.tinypic.com/2wr1cgm.jpg

It’s hard to understand what your 'solution' actually is. As I understand you dismiss LHV and "spooky action at a distance" and loopholes. What’s left? Etienne-Louis Malus Law from the 18th century? You mentioned Local Hidden Constants in an earlier post, but that doesn’t work either...

It’s quite strange to see the strong argumentation against Alain Aspect et al. We all seem to agree on the theory. When Alain Aspect performed his very first experiment with 2-channel polarizers, the result matched exactly the QM predictions, as Alain Aspect’s own slide shows:

http://i42.tinypic.com/r6xwxz.jpg

Don’t you think it’s quite farfetched to dismiss the official conclusion, and replace it with your 'personal speculations', based on an optical law from 18th century – basically saying "some light is lost in the polarizer"...?

I can’t do the calculations, but I suspect that the probabilities for the 18th century Malus Law too by chance reproduce exactly the expected results predicted by QM, is even more 'miraculous' than "Spukhafte Fernwirkung"...

DevilsAvocado

Apr28-10, 07:51 PM

I do not see connection with your post #108 but yes this is my personal speculation that illustrates problems with your personal speculation about this overlapping effect.

:smile: Hehe, we’re all a bunch of 'grumpy laymen' here, aren’t we? :grumpy:

About your statement in post #108

From wikipedia - superposition principle (http://en.wikipedia.org/wiki/Superposition_principle) states that, for all linear systems,
The net response at a given place and time caused by two or more stimuli is the sum of the responses which would have been caused by each stimulus individually.

So I would restate what you said this way: The condition for superposition of the particle (photon) is that it should pass both slits concurrently.

Okay, but to be fair we should maybe refer to Wikipedia – Quantum superposition (http://en.wikipedia.org/wiki/Quantum_superposition): "Quantum superposition is a fundamental property of quantum mechanics. It defines the collection of all possible states that an object can have."

Niels Bohr would turn in his grave if someone tried to stipulate a wavefunction as an object... :wink:

But as I said, this is maybe not important. What is important is if the wavefunction of the entangled pair is considered one wavefunction, or two. I don’t think two wavefunctions creates one interference pattern... maybe some of the pros can inform us? :uhh:

First, scientist do not to say things like "Hey! I can prove some weird stuff!" because they relay on scientific method (http://en.wikipedia.org/wiki/Scientific_method). They say things like "Results of experiment is in agreement with some weird hypothesis."

Okay, I will put smileys after all 'bad jokes' from now on... :biggrin:

This is because you can not prove theory with experiment but only disprove competing theories.

Okay, so Eddington's 1919 solar eclipse experiment were actually disproving Newton, not confirming Einstein??

Second, you don't have to be considered swindler if you make some error. Everybody makes errors but not everybody is swindler.

Sounds logical. What don’t sound logical is that every scientist in the 'EPR business' is making the same 'correlated' mistake...??

There is nice picture that I spied in another thread:

Yeah, that is funny! The question is – Is it Einstein, Aspect & Bell wearing the tin foil hat, or is it "someone" else?? :wink:

http://upload.wikimedia.org/wikipedia/commons/8/85/ManWearingTinFoilHat.jpg

You are not very careful with your statement.
The theory states that if X, Y, Z and determinism then certain inequalities hold.
Besides Counterfactual Definiteness is in conflict with Heisenberg Uncertainty Principle contrary to what you are implying.

You’re right. Sorry, layman error... :redface:

This is quite loose statement. There are things in QM that are not very strictly established like correspondence between certain things in mathematical formalism and physical reality. Because of that QM still can accommodate quite different interpretations.
So I would say that with some minor changes in interpretation it can still be compatible with (contextual) LHV.

Humm... "things" ... "certain things" ... "physical reality" ... "quite" ... "minor changes" ... "contextual" ...

To me, 'tin foil warning' is now flashing all red. http://i40.tinypic.com/5nlo9w.gif

Could you please explain how you fit in contextual LHV with this slide from Alain Aspect:

http://i39.tinypic.com/2wr1cgm.jpg

inflector

Apr28-10, 10:46 PM

Wait ... what happened to Frame Dragger? Did he get banned?

I sure hope not. I think I may have jinxed him accidentally:

http://www.physicsforums.com/showthread.php?t=397935

Fortunately, there is hope for Frame Dragger. It seems there is some sort of temporary banning and demerit system whereby you can be warned or penalized for infractions against the rules.

My guess is that Frame Dragger is under a temporary ban. Perhaps not though, he may have reached the 10 point automatic permanent ban threshold.

DevilsAvocado

Apr29-10, 05:37 AM

... Perhaps not though, he may have reached the 10 point automatic permanent ban threshold.
??? :confused: ???

I’m totally confused... is it the "h-word" in post #175 (http://www.physicsforums.com/showpost.php?p=2690682&postcount=175) ??????!?!?!?!?!?!?

... a sad :cry: mad :mad: bad :yuck: day ...

DrChinese

Apr29-10, 09:43 AM

Wait ... what happened to Frame Dragger? Did he get banned?

I hope not as well! I didn't see anything that was weird posted, maybe it's the post Devil indicated. But that would surprise me.

DevilsAvocado

Apr29-10, 10:53 AM

maybe it's the post Devil indicated
DrC, if that’s the case – it must be a complete misunderstanding! You and FD are friends, right? And this was kind of an "insider joke", right? Then it must be corrected.

DrChinese

Apr29-10, 10:57 AM

DrC, if that’s the case – it must be a complete misunderstanding! You and FD are friends, right? And this was kind of an "insider joke", right? Then it must be corrected.

Hey, I would never take that as anything other than light-hearted. I hope FD returns asap. I miss him already [sniff].

Besides, I am friends with everyone. o:)

I will say this: as far as I know, the moderators never comment on suspensions. I actually think that is the best policy all the way around. The intent is to keep the focus on the subject matter.

So with that in mind, I say that EPR-like spooky action at a distance is possible. Did I mention that yet?

DevilsAvocado

Apr29-10, 11:05 AM

Right on DrC! We, all friends on PF, want him back NOW!

Okay, got ya! Let’s hope for the best!

EPR = spooky action = TRUE ;)

glengarry

Apr29-10, 02:36 PM

I think FD got pretty fed up with me to the point of following me to an old topic on the Number Theory forum and saying that my ideas should be taken as "Independent Research." I take it that "Independent Research" is a euphemism for "Not now relevant and never will be relevant"

http://physicsforums.com/showthread.php?t=393577

... I want to be sure here... are you saying that you think the code you've written is novel, and somehow more elucidating and efficient than existing methods? You mention "1mil"... so I assume you are referring to a Nobel? Other than appreciating patterns which have been studied for a VERY long time, and taking a (new to you) approach, why do you think this is in any way... new to anyone else? This also seems like something for "Indipendant Research", not Number Theory.

But anyways... EPR, spookiness, good stuff...

jtbell

Apr29-10, 02:58 PM

I take it that "Independent Research" is a euphemism for "Not now relevant and never will be relevant"

No, he's referring to our Independent Research forum:

http://www.physicsforums.com/forumdisplay.php?f=146

which is the only forum where we permit discussion of "new theories" that have not already been published in one of the professional physics venues. See the PF Guidelines (click on the "Rules" link at the top of any page) and note the section Overly Speculative Posts.

DevilsAvocado

Apr29-10, 03:01 PM

... I take it that "Independent Research" is a euphemism for "Not now relevant and never will be relevant"
Thanks for sharing glengarry, but if the phrase "Indipendant Research" is enough to be banned, my confusion is now googolplex1000 ...

? ? ?

Edit: Okay, jtbell explains it, still a mystery...

glengarry

Apr29-10, 04:07 PM

No, he's referring to our Independent Research forum:

http://www.physicsforums.com/forumdisplay.php?f=146

which is the only forum where we permit discussion of "new theories" that have not already been published in one of the professional physics venues. See the PF Guidelines (click on the "Rules" link at the top of any page) and note the section Overly Speculative Posts.

Yes, I understand that "Independent Research" is a subforum here at PF, and I understand that "speculation" is generally not tolerated here at PF, for very obvious reasons. However, I tried to state an "interesting" proposition (http://www.physicsforums.com/showpost.php?p=2691133&postcount=36) in another thread so that people would ask me to show them, by way of mathematics, to prove to them what I was talking about. And I complied with the request immediately. If you are now saying that mathematical proof is itself "speculative," then I would be very much inclined to disagree. I would simply consider myself to be a thoroughly mathematically minded person who is also interested in questions of how constructive mathematical systems can, qua themselves, provide a believable account for the way that a universe such as ours is indeed possible.

My only "agenda" around here is to try to talk all of the "empiricists" out there into becoming more "idealistic" like us mathematicians. I truly mean no harm, and I just hope that we can all get along :)

DrChinese

Apr29-10, 04:32 PM

Yes, I understand that "Independent Research" is a subforum here at PF, and I understand that "speculation" is generally not tolerated here at PF, for very obvious reasons. However, I tried to state an "interesting" proposition (http://www.physicsforums.com/showpost.php?p=2691133&postcount=36) in another thread so that people would ask me to show them, by way of mathematics, to prove to them what I was talking about. And I complied with the request immediately...

I never saw any math at all. Nor anything more than a sly reference implying you know something worthwhile but are witholding it. I invited you to share. Of course, it should follow guidelines if you decide to post it.

And just because you think your math seems good to you, if it leads to a speculative conclusion, it still belongs in IR.

IR can be junk, or it can be good. Depends I would say.

DevilsAvocado

Apr29-10, 05:50 PM

... My only "agenda" around here is to try to talk all of the "empiricists" out there into becoming more "idealistic" like us mathematicians. I truly mean no harm, and I just hope that we can all get along :)

Well, now we are in the QM forum and as far as I know the mathematics works perfectly fine. The only 'trouble' is that it doesn’t make any 'empirical' sense; (to many of us) it’s completely nuts! One particle here and there, and at two places simultaneously, and it knows if we are looking at it, and if not, it interfere with itself = pure schizo! As if this isn’t enough, the latest discoveries by Bell & Aspect prove that if we look at one particle here – it immediately settles the properties of a twin particle, on the other side of the universe!

IMO, now it’s time to: "Shut up and talk!" :wink:

... about this strange world ...

DevilsAvocado

Apr29-10, 07:36 PM

... As to the Relativity of Simultaneity: If you accept an acausal interpretation such as RBW, that goes away as an issue.
I read the paper The Relational Blockworld Interpretation of Non-relativistic Quantum Mechanics (http://philsci-archive.pitt.edu/archive/00003247/), and I got the creepy 'MWI feeling'. (Is RUTA the author? If that’s the case – no offence.)

Feels like we get rid of one strange phenomenon, by the cost of an almost stranger 'beast':
The ontology of this interpretation is one in which constructive objects (entities such as particles or waves with worldlines in spacetime) are not fundamental constituents of reality.

Not only reality gets a blow, the arrow of time is a non-question.
Keep in mind that in our blockworld setting, talk of “actions performed” gets only a purely logicalcounterfactual meaning—the entire experimental EPR set-up, its past, present and future, and the spacetime symmetries of that set-up are all just ‘there’—no one could really perform some alternative measurement on the other wing of the experiment without changing the entire spatiotemporal description of the experiment.

(RUTA, are you there?) What happens if want to set up my personal "Omelet Experiment"?
The Omelet Experiment
Four eggs are place in a pipeline that is 1 ly long. When the eggs have traveled to 'detector', they are crushed, whipped and fried in a pan.

Are the past, present and future just 'there' in the "Omelet Experiment"? How do we turn the omelet into eggs?

yoda jedi

Apr29-10, 09:31 PM

RUTA

Apr29-10, 09:55 PM

I read the paper The Relational Blockworld Interpretation of Non-relativistic Quantum Mechanics (http://philsci-archive.pitt.edu/archive/00003247/), and I got the creepy 'MWI feeling'. (Is RUTA the author? If that’s the case – no offence.)

Yes, I'm one of the authors (the physicist, Stuckey). I've never tried to hide my identity, you can easily figure out who I am from the personal info on my profile and I've posted my name in other threads. I don't like to make comments in any context that I won't stand behind, I even demand my name accompany all my referee reports.

I hope you don't think RBW is a version of MWI. If so, we failed miserably :-)
Feels like we get rid of one strange phenomenon, by the cost of an almost stranger 'beast':
Not only reality gets a blow, the arrow of time is a non-question.

I admit, you're right, the RBW ontology is a "strange beast." It's contrary to everything people want in an "explanation," i.e., entities moving in space as a function of time. It may be Hilbert space or Fock space, etc, but people want a story about some'thing' moving in some space. RBW is a rule for co-constructing space, time and matter, and this rule is not a story about matter in spacetime.
(RUTA, are you there?) What happens if want to set up my personal "Omelet Experiment"? Are the past, present and future just 'there' in the "Omelet Experiment"? How do we turn the omelet into eggs?

Certainly, any story about eggs is best told using classical mechanics. However, at the most fundamental level, RBW says the eggs are not subatomic particles or quantum waves interacting via forces, i.e., matter in spacetime. At the fundamental level, one must follow the RBW rule for co-constructing space, time and matter to obtain a spacetimematter view of the phenomenon in question. This is done with a distribution of relations over the appropriate graph. If one wants to study the distribution of individual relations, one is doing quantum physics. If one wants to study the behavior of trans-temporal objects in spacetime, one uses the average values of the relations and is doing classical physics.

DrChinese

Apr30-10, 07:55 AM

Are the past, present and future just 'there' in the "Omelet Experiment"? How do we turn the omelet into eggs?

Which came first, the chicken or the egg? The problem is that our way of seeing things creates problems where there may be none. Remember Zeno's paradox? Same kind of issue, where we "prove" something is impossible.

In RBW, time is essentially treated as symmetric and c is respected. Events have no cause. So pick your poison.

zonde

Apr30-10, 08:03 AM

Okay, so Eddington's 1919 solar eclipse experiment were actually disproving Newton, not confirming Einstein??
Confirming GR - yes. Proving GR - no.
About Newton it is not quite disproving as well. Thats because it's still usable and GR is no a match in usability for simple cases. So it's rather establishing domain of applicability for Newton theory.

Sounds logical. What don’t sound logical is that every scientist in the 'EPR business' is making the same 'correlated' mistake...??
Yes that seems strange. So for me it's part of the puzle.
My version is that approaching LHV limit has similar manifestation as presence of experimental imperfections so that without explicit quantitative analysis you can't separate two effects.
Or more detailed version is that sucessful violation of Bell inequalities requires as low as possible coincidence rate for equal settings but any experimenter assumes (quite naturally) that any increase in coincidence rate for equal settings is result of imperfections (decoherence) and does not bother to do quantitative analysis.
And that way it does not seem so strange anymore.

Yeah, that is funny! The question is – Is it Einstein, Aspect & Bell wearing the tin foil hat, or is it "someone" else?? :wink:
No, it's the one who talks about non-locality as proven thing. :wink:

Could you please explain how you fit in contextual LHV with this slide from Alain Aspect:
My explanation is that QM works for ensembles in deterministic way and for idividual particles in probabilistic way.
So when we use detector at say 10% efficiency we acctualy are detecting small ensembles of 10 photons on average. After each "click" detector state is washed away and detection process starts anew from base state.
If you increase detector efficiency you decrease ensemble size of individual detection and approach probabilistic limit.
That way QM prediction with interference term present is for the limit of infinite ensemble size for each detection but classical product state (like QM prediction but without interference term) is for the limit of ensemble size of 1 (100% efficiency limit).
In other words it depends from the influence of ensemble on measurement context versus influence of local randomness.

Two probabilities I am talking about:
P_{QM}(\alpha,\beta) = \frac{1}{2}sin^{2}\alpha\, sin^{2}\beta + \frac{1}{2}cos^{2}\alpha\, cos^{2}\beta + \frac{1}{4}sin 2\alpha\, sin 2\beta = \frac{1}{2}cos^{2}(\alpha-\beta)
P_{C}(\alpha,\beta) = \frac{1}{2}sin^{2}\alpha\, sin^{2}\beta + \frac{1}{2}cos^{2}\alpha\, cos^{2}\beta
Second equation is classical product of probabilities and does not produce 0 coincidence rate for all matching angles.

DrChinese

Apr30-10, 08:33 AM

My explanation is that QM works for ensembles in deterministic way and for idividual particles in probabilistic way.
So when we use detector at say 10% efficiency we acctualy are detecting small ensembles of 10 photons on average. After each "click" detector state is washed away and detection process starts anew from base state.
If you increase detector efficiency you decrease ensemble size of individual detection and approach probabilistic limit.
That way QM prediction with interference term present is for the limit of infinite ensemble size for each detection but classical product state (like QM prediction but without interference term) is for the limit of ensemble size of 1 (100% efficiency limit).
In other words it depends from the influence of ensemble on measurement context versus influence of local randomness.

Two probabilities I am talking about:
P_{QM}(\alpha,\beta) = \frac{1}{2}sin^{2}\alpha\, sin^{2}\beta + \frac{1}{2}cos^{2}\alpha\, cos^{2}\beta + \frac{1}{4}sin 2\alpha\, sin 2\beta = \frac{1}{2}cos^{2}(\alpha-\beta)
P_{C}(\alpha,\beta) = \frac{1}{2}sin^{2}\alpha\, sin^{2}\beta + \frac{1}{2}cos^{2}\alpha\, cos^{2}\beta
Second equation is classical product of probabilities and does not produce 0 coincidence rate for all matching angles.

That isn't so. There is absolutely no evidence (cite it if you think I am wrong) whatsoever that the classical Product state is the limit as efficiency approaches 100%.

yoda jedi

Apr30-10, 12:00 PM

Are the past, present and future just 'there' in the "Omelet Experiment"? How do we turn the omelet into eggs?

the REALITY is poly-ordered or omni-ordered, can coexist (in principle or possibily) the past, present and the future.

establishes order without time (no determinism or a convoluted determinism, non chronological determinism).
(nonlocal determinism requires nonlocal influences in time ordered manner).

.................

DevilsAvocado

Apr30-10, 06:06 PM

Yes, I'm one of the authors (the physicist, Stuckey).

That is cool! :cool: Physics Forums is a fantastic place (except when they ban friends :grumpy:), where people "like me" get a chance to talk with the "source" of what may be the next 'paradigm' in science. PF = :cool: + :!!)

I hope you don't think RBW is a version of MWI. If so, we failed miserably :-)

Nonono! I am a layman, but I FGS hope that a least three neurons, or so, are properly wired... :wink:

When I say "creepy MWI feeling" I mean the feeling you get when smart people have build a model of the world that seems to work just fine – and could be the real solution – it still feels like you landed a bit 'uncomfortably' in a weird mix of; One Flew Over the Cuckoo's Nest + The Exorcist + The Matrix + Alice in Wonderland... :bugeye: (:biggrin:)

I admit, you're right, the RBW ontology is a "strange beast." It's contrary to everything people want in an "explanation," i.e., entities moving in space as a function of time. It may be Hilbert space or Fock space, etc, but people want a story about some'thing' moving in some space. RBW is a rule for co-constructing space, time and matter, and this rule is not a story about matter in spacetime.

Think I got it... When you move from A to B, you’re not moving a distance in space – you’re moving in spacetimematter, right? Still it’s weird... do you mean there is no way to 'filter out' just space (to 'move around' in)... we always carry the 'whole package'...?

Certainly, any story about eggs is best told using classical mechanics. However, at the most fundamental level, RBW says the eggs are not subatomic particles or quantum waves interacting via forces, i.e., matter in spacetime.
...
If one wants to study the distribution of individual relations, one is doing quantum physics. If one wants to study the behavior of trans-temporal objects in spacetime, one uses the average values of the relations and is doing classical physics.

And this is exactly what’s so weird, if we imagine subatomic particles in the 'QM world' as Lego bricks:

http://upload.wikimedia.org/wikipedia/commons/thumb/3/32/Lego_Color_Bricks.jpg/500px-Lego_Color_Bricks.jpg

And the macroscopic 'Classical world' as the 'stuff' built by Lego bricks:

http://upload.wikimedia.org/wikipedia/commons/b/b9/Trafalgar_legoland_Copyright2003KTai.jpg

And realize that a single Lego brick obey Law of Nature I, and a complete Lego building obey Law of Nature II, then IMO we do have some sort of 'problem'... especially if I & II is somewhat a contradiction...

Personally, I can only see two ways out of this:

1) Law of Nature I (QM) is incomplete.

2) Our brains are 'incomplete' and are fooling us all the time and every day – the world doesn’t work the way we perceive it (="creepy MWI feeling").

PS: What’s your opinion on various attempts to scale up superposition to macroscopic scale (cooling of billions of atoms), will it ever work...? And if it works, could we thereby learn anything more about "Law of Nature I"...?

DevilsAvocado

Apr30-10, 06:50 PM

Which came first, the chicken or the egg?
I dunno? I just want an omelet! :biggrin:

Seriously, the "Arrow of Time" is a macro/micro 'problem', as RUTA points out, but it’s nevertheless very strange...

Remember Zeno's paradox? Same kind of issue, where we "prove" something is impossible.

You mean "Achilles and the tortoise"? But, if I'm not mistaken, Richard Feynman in "The Feynman Lectures on Physics" solves this paradox in a couple of sec using infinitesimals... I could be wrong though... :uhh:

Events have no cause.

We do know "one guy" who absolutely suffers bad right now from this very fact... :bugeye:

DevilsAvocado

Apr30-10, 08:09 PM

does not bother to do quantitative analysis.

I’m sorry zonde, but this doesn’t make any sense. I watched a lecture by Alain Aspect, where the audience could ask questions afterwards, and Aspect gets the question:

"You said that when you got the result from your first experiment in 1982, you wished that you would not get the result, that perfectly matched the predicted (QM) curve – What had you wished you would get??"

Aspect explains that, in today’s perspective, he wished that the result had not matched the predictions of QM, because that would mean that he had found the limit of QM – which would be fantastic! And Aspect is convinced that this will happen one day.

Therefore, your "not bother" assumption is quite farfetched. The man or woman, who does find this limit of QM will get a Nobel, lots of fame, and money – besides the scientific thrill and satisfaction.

To "not bother" in this case, is to not be a real scientist. I’m sorry.

No, it's the one who talks about non-locality as proven thing. :wink:
That must be Alain Aspect! :wink:

My explanation is that QM works for ensembles in deterministic way and for idividual particles in probabilistic way.

This sounds like the "Ensemble Interpretation". IMO you have trouble explaining the double slit experiment, that interference fringes seen require repeated trials to be observed. We all know it’s going to be there, and the first and last electron can have no knowledge of any "Ensemble", unless you want to introduce "spooky action in time"...!? :bugeye:

I think DrC can handle this better than me.

Edit: I think it’s a mistake to do a parable to macroscopic objects like an "ensemble of billiard balls", that acts in a deterministic way – photons are not "billiard balls" whether it’s one or googolplex photons – HUP run the business in both cases.

DevilsAvocado

Apr30-10, 08:28 PM

the REALITY is poly-ordered or omni-ordered, can coexist (in principle or possibily) the past, present and the future.

Okay yoda jedi, can you help me reconvert my omelet into 4 eggs, I want to return to the past future? :biggrin:

RUTA

May1-10, 10:26 AM

When I say "creepy MWI feeling" I mean the feeling you get when smart people have build a model of the world that seems to work just fine – and could be the real solution – it still feels like you landed a bit 'uncomfortably' in a weird mix of; One Flew Over the Cuckoo's Nest + The Exorcist + The Matrix + Alice in Wonderland... :bugeye: (:biggrin:)

Unfortunately for us, your reaction is typical :-)
Think I got it... When you move from A to B, you’re not moving a distance in space – you’re moving in spacetimematter, right? Still it’s weird... do you mean there is no way to 'filter out' just space (to 'move around' in)... we always carry the 'whole package'...?

I'm afraid it's worse -- there is no "movement," of any 'thing' any 'where'. When you want to describe an experiment, you have to do so as an entire block of spacetime (when dealing with past, present and future "at once" you've what is called "blockworld"). And, instead of placing material objects (beam splitters, mirrors, source, detectors, etc) into the otherwise empty spacetime block, you have to explicitly build those objects "concurrently" with their spacetime. This means there is no empty spacetime -- there are no material objects without space and time, and there are no space and time without material objects. This is just a relational view of spacetime.

And this is exactly what’s so weird, if we imagine subatomic particles in the 'QM world' as Lego bricks

There are no "quantum objects" (sometimes referred to as "screened off" objects) in our interpretation -- all material objects have trajectories and are therefore "classical." However, you don't model objects via ever smaller objects, you build them with their commensurate spacetime using graphical relations in an "all at once" (blockworld) fashion. Just look at the first four figures of our QFT paper in the arXiv.

And realize that a single Lego brick obey Law of Nature I, and a complete Lego building obey Law of Nature II, then IMO we do have some sort of 'problem'... especially if I & II is somewhat a contradiction...

When you want to explore the distribution of relations comprising some objects (typically, beam splitters, sources, detectors, etc), then you're doing quantum physics. If you want to discuss large-scale average behavior, then you're doing classical physics. Again, look at those first four figures and their captions. The two formalisms are distinct, but there is no "Schnitt" or quantum "cut" between two ontologically distinct realms. The classical (average) description gets better with larger collections of relations, just as the accuracy of thermodynamics as an average from statistical mechanics gets better with more particles, even though you can talk about pressure and temperature when dealing with a single particle.

Personally, I can only see two ways out of this:

1) Law of Nature I (QM) is incomplete.

2) Our brains are 'incomplete' and are fooling us all the time and every day – the world doesn’t work the way we perceive it (="creepy MWI feeling").

I don't know what the "right" answer is. All I can say is that our interpretation solves all the quantum mysteries and is now being used to solve those of QFT as well. If it's successful (ultimately accounts for all quantum and all classical phenomena), then we're stuck with an adynamical picture. I don't care what the picture is as long as it accounts for all our experiments in a coherent fashion. We don't have such a picture now, so we must switch between incongruous pictures when working in formally incongruous theories (quantum and GR).
PS: What’s your opinion on various attempts to scale up superposition to macroscopic scale (cooling of billions of atoms), will it ever work...? And if it works, could we thereby learn anything more about "Law of Nature I"...?

Zeilinger has created interference patterns with buckyballs (buckminsterfullerene C60, a molecule with 60 carbon atoms). I don't think there is a Schnitt, you can create interference patterns with elephants if you can "screen them off."

DevilsAvocado

May1-10, 04:52 PM

Unfortunately for us, your reaction is typical :-)
:smile:

I'm afraid it's worse -- there is no "movement," of any 'thing' any 'where'.
...
This means there is no empty spacetime -- there are no material objects without space and time, and there are no space and time without material objects.

Amazing, just amazing. Hollywood cannot keep up with SFX to beat this one...

I realize you and your partners didn’t come up with this idea just from the "pop-up top hat" :smile:, you’ve spent a lot of time and effort, and in this process you must have tested a lot of 'scenarios'. Still, I have to ask – How do RBW handle CMB, if there is no "movement," of any 'thing' any 'where'?

Photons are subatomic particles or quantum waves interacting via forces, and the only explanation for the measured redshift, are that the waves gets stretched during the long travel in the expanding space... and we can measure photon by photon when they arrive from their long journey that started ~370 000 years after BB. How do RBW explain this?

There are no "quantum objects" (sometimes referred to as "screened off" objects) in our interpretation -- all material objects have trajectories and are therefore "classical." However, you don't model objects via ever smaller objects, you build them with their commensurate spacetime using graphical relations in an "all at once" (blockworld) fashion. Just look at the first four figures of our QFT paper in the arXiv.

http://i43.tinypic.com/24b0ohy.png

Okay, I understand this, sort of, the QM wavefunction do not exist. But... when we perform a measurement on e.g. an electron, hitting a detector screen – doesn’t the electron 'exist' then?

When you want to explore the distribution of relations comprising some objects (typically, beam splitters, sources, detectors, etc), then you're doing quantum physics. If you want to discuss large-scale average behavior, then you're doing classical physics.

I think I have to stop 'yearning', and just accept the fact... maybe a sledgehammer will do the work... :biggrin:

I don't know what the "right" answer is. All I can say is that our interpretation solves all the quantum mysteries and is now being used to solve those of QFT as well. If it's successful (ultimately accounts for all quantum and all classical phenomena), then we're stuck with an adynamical picture. I don't care what the picture is as long as it accounts for all our experiments in a coherent fashion. We don't have such a picture now, so we must switch between incongruous pictures when working in formally incongruous theories (quantum and GR).

Time for the "sledgehammer" again... seriously, do you think that the fact that QM <> GR (at extreme levels), is an indication for, or better, a reason for what we perceive as "quantum mysteries"? I.e. do you think that we (even a layman) someday will say – Ohhh sh*t, is it all that simple!? Now it makes sense all the way!!

(...or is it just a layman’s "wet dream"... :rolleyes:)

Zeilinger has created interference patterns with buckyballs (buckminsterfullerene C60, a molecule with 60 carbon atoms).

WOW! Some time ago I was asking about "macroscopic EPR" in this forum, and was almost banned as the biggest crank in history... :grumpy: (:rofl:) Thanks for the info!! Very interesting!! Would it be possible to perform EPR with buckyballs...??

http://upload.wikimedia.org/wikipedia/en/2/22/CntHAADF.jpg
Electron micrograph showing a single-walled nanotube (buckytube)

I don't think there is a Schnitt, you can create interference patterns with elephants if you can "screen them off."

Okay, no Schnitt on interfering elephants is maybe bad news for me... or maybe not... :rolleyes: (:biggrin:)

PS: Just a coincidence? RUTA in Swedish = SQUARE ≈ BLOCK... :wink:

DevilsAvocado

May1-10, 07:32 PM

About Frame Dragger: Events do have a cause

I finally found the "last" FD post, and it looks like a temporary ban. Maybe someone with more "banning experience" can provide the "final prediction".

Anyway, it happened in the thread Overpopulation (http://www.physicsforums.com/showthread.php?t=391197) where PF ADMIN GB (http://www.physicsforums.com/showpost.php?p=2678978&postcount=61) had an interest in the subject. In second post after GB, FD delivers one off his famous "sarcastic-as-h*ll" (http://www.physicsforums.com/showpost.php?p=2679105&postcount=63) (without direct address). Now, brainstorm & Frame Dragger starts a loooooong discussion (http://www.physicsforums.com/showthread.php?t=391197&page=5) that drifts off-topic into education, religion, politics, racism, migration, culture, etc.

No attention about the post from PF ADMIN GB, whatsoever.

The discussion is now entering "US Domestic policy & language"... quite a bit from "Overpopulation"...

PF ADMIN GB has now had enough, and tell the guys to – "Please keep this thread in a productive state, thank you."

FD misjudges the situation and makes a joke of it all (http://www.physicsforums.com/showpost.php?p=2692904&postcount=80) ...

The rest we know.

RUTA

May2-10, 08:28 AM

I realize you and your partners didn’t come up with this idea just from the "pop-up top hat" :smile:, you’ve spent a lot of time and effort, and in this process you must have tested a lot of 'scenarios'. Still, I have to ask – How do RBW handle CMB, if there is no "movement," of any 'thing' any 'where'?

Photons are subatomic particles or quantum waves interacting via forces, and the only explanation for the measured redshift, are that the waves gets stretched during the long travel in the expanding space... and we can measure photon by photon when they arrive from their long journey that started ~370 000 years after BB. How do RBW explain this?

Actually, we're hoping to account for redshift this summer and reevaluate the galactic rotational velocity profiles. But, it's true that as permanently "screened off entities" photons are never "there." Lucky for us, famous physicists, including a couple Nobel Laureates (A. Bohr and B. Mottelson) and Zeilinger, have already proposed this one :-)
Okay, I understand this, sort of, the QM wavefunction do not exist. But... when we perform a measurement on e.g. an electron, hitting a detector screen – doesn’t the electron 'exist' then?

Yes and no. There is something different about the detector upon a detection event, but what's different about a CCD when it clicks due to an "electron" isn't the same as what's different about a cloud chamber when a track appears due to an "electron." People want to picture one and the same (screened off) 'thing' responsible for what they observe in both cases, but the situations are discernible so their descriptions differ and the descriptions are all we have (not to sound like an instrumentalist).
Time for the "sledgehammer" again... seriously, do you think that the fact that QM <> GR (at extreme levels), is an indication for, or better, a reason for what we perceive as "quantum mysteries"? I.e. do you think that we (even a layman) someday will say – Ohhh sh*t, is it all that simple!? Now it makes sense all the way!!
(...or is it just a layman’s "wet dream"... :rolleyes:)

Absolutely, once you "get it" you realize it's not at all difficult.

Would it be possible to perform EPR with buckyballs...??
Okay, no Schnitt on interfering elephants is maybe bad news for me... or maybe not... :rolleyes: (:biggrin:)

Assuming there is no quantum cut (not everyone agrees), you can entangle anything you want as long as they're "screened off." Just replace the interferometer atoms in an interaction-free measurement device with elephants and you can entangle them like Elitzur's quantum liar experiment.

Elitzur, A.C. and Dolev, S. (2005). Quantum phenomena within a new theory of time. In A. Elitzur, S. Dolev and N. Kolenda (eds.), Quo vadis quantum mechanics? Berlin: Springer Verlag, 325 – 349.

Elitzur, A.C. and Vaidman, L. (1993). “Quantum mechanical interaction-free measurements.”
Foundations of Physics, 23, 987 – 997.

PS: Just a coincidence? RUTA in Swedish = SQUARE ≈ BLOCK... :wink:

A student in my boundary value problems class took to calling me Captain RUTA in reference to the fact that the problems we solved were "nasty." Rather than his (crude) acronym, I'll claim the Swedish origin to keep myself out of trouble :-)

yoda jedi

May2-10, 11:26 AM

Events have no cause.

We do know "one guy" who absolutely suffers bad right now from this very fact... :bugeye:

good joke !!!
...laughs.......

Okay yoda jedi, can you help me reconvert my omelet into 4 eggs, I want to return to the past future? :biggrin:

if i have to go to some city, say...... the netx month, that "fact" can change the order of things to do, today....
and change the order of things today can change things in the future and so on..... of course we see more "natural" the last possibility.....

DevilsAvocado

May3-10, 07:14 PM

Actually, we're hoping to account for redshift this summer and reevaluate the galactic rotational velocity profiles. But, it's true that as permanently "screened off entities" photons are never "there." Lucky for us, famous physicists, including a couple Nobel Laureates (A. Bohr and B. Mottelson) and Zeilinger, have already proposed this one :-)

Cool! :cool:

... an "electron" isn't the same as what's different about a cloud chamber when a track appears due to an "electron." People want to picture one and the same (screened off) 'thing' responsible for what they observe in both cases, but the situations are discernible so their descriptions differ and the descriptions are all we have ...

Aha! The "cloud chamber" is good one, I do understand that! (and I remember it well, when as a freshman I saw it for the first time, wonderful...)

Absolutely, once you "get it" you realize it's not at all difficult.

Okay... but still QM <> GR... so maybe we (I) have to wait a 'while'...

Assuming there is no quantum cut (not everyone agrees), you can entangle anything you want as long as they're "screened off." Just replace the interferometer atoms in an interaction-free measurement device with elephants and you can entangle them like Elitzur's quantum liar experiment.

I think I just have had a 'revelation'! It’s not about SIZE, it’s about "screen off"!!You can’t disturb the system/'object', because then all the 'magic' goes away!

My business idea, to fill Wembley Stadium, presenting – The Two Outrageous Entangled Elephants! – will of course not work. No one is allowed to see... is has to be all black on Wembley for TOEE to work... :rofl:

Thanks for making me understand that!!

(This maybe belongs to the "Philosophical forum"?) Isn’t it strange... weird... kinda... I definitely don’t believe in any "higher being", but still it looks like 'someone' is laughing big time at humans "trying to understand"... at the 'smallest level' – we are forbidden to watch... and at the 'biggest level' – we can’t see beyond the surface of last scattering... someone must be laughing? Agent Smith?? :biggrin:

I'll claim the Swedish origin to keep myself out of trouble :-)

Yeah, absolutely, right! It’s always safest with some "Nobel-compatibility"... you never know... :wink:

DevilsAvocado

May3-10, 07:26 PM

good joke !!!
...laughs.......

Well, huum, not a 'joke'... more like paradox/irony... but if "one guy" leaves permanent... it’s just sad...
if i have to go to some city, say...... the netx month, that "fact" can change the order of things to do, today....
and change the order of things today can change things in the future and so on..... of course we see more "natural" the last possibility.....

Okay, but I was not thinking about the ordering of events. I was thinking about the macroscopic irreversibility of time:
egg -> omelet = TRUE | omelet -> egg = FALSE

ThomasT

May4-10, 10:33 AM

I haven't seen you derive your coincidence rate. If you've done that, please tell me the post number. If not, please derive it now.You can disregard my little exercise in translating |a - b| into ||a - L| - |b - L||. It only works for certain values of a, b, and L. For other values it's ||a - L| + |b - L||.
Of course it must be possible to express |a - b| in terms of the individual angular differences. Anyway, it doesn't matter. We still haven't accounted for the cos^2 term.

Afaik, it's empirical in origin and empirically applied -- based on, as you've mentioned, the equipment that's used, and the experimental setting.

The photon coincidence rate is the intensity of the light transmitted jointly by the polarizers. Do you agree that the cos^2 Theta rule regarding resultant intensity applies in certain optical Bell tests where, in each trial (ie., wrt each pair of entangled photons), identically polarized optical disturbances are jointly analyzed by crossed linear polarizers? (For the purpose of this discussion, we're considering an ideal setup.)

If so, then do you think that the application of this rule is in accord with the principle of local causality and c as a propagational speed limit?

If so, then there's a problem with the interpretation of Bell's theorem which says in effect that the observed cos^2 dependency between the angular difference of the polarizer settings and photon coincidence rate can't be due to a c-limited local common cause, ie., an emission produced entanglement.

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

So, lets try a different interpretation of Bell's theorem:

Bell's theorem says that lhv accounts which meet certain formal requirements can't possibly reproduce the QM predictions and the observed cos^2 dependency between the angular difference of the polarizer settings and the photon coincidence rate.

This seems ok. So, which formal requirements are, effectively, at fault?

c-limited locality can't be explicitly formalized without having some variable (hidden or not) to express it in terms of. But it seems rather illogical to require an account of joint detection rate in terms of a variable, L, which doesn't determine it. The variability of P(A, B) is solely a function of variations in a global measurement parameter, the angular difference of the polarizer settings. To say that an explicitly local hidden variable account is impossible misses this point. Of course a viable lhv account is impossible, but the reason for this precludes inferring or positing from it that >c propagations exist in Nature.

Since NONlocality isn't a physical mechanism, and since positing ftl propagation speeds (to allow the entangled entities to 'communicate ' with each other) based on Bell, GHZ, etc. theorems is unwarranted, then we're left with the assumption (of mainstream physics) that we live in a c-limited, locally causal universe.

Hence my attempt at a local explanation or understanding (of sorts), but not an explicitly local formalization, for at least a certain class of entanglement experiments -- and a rather more physical understanding of quantum entanglement than can be gotten via the formalism(s) of it.

Quantum nonlocality and quantum superposition refer to formal terms and transformations. EPR, Schrodinger, and many others have pointed out the problematic and sometimes even absurd entailments of taking this as a literal description of the states, configurations, and behaviors of physical objects.

The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

So, considering the above, I still think that the correct answer to the title question of this thread is no, spooky action at a distance (or nonlocality) as envisaged by EPR (or anybody else), isn't a physical possibility.

Are ftl propagations a possibility? Yes, wrt certain worldviews. But they're not necessary to understand the correlations associated with quantum entanglement.

RUTA

May4-10, 11:59 AM

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

Not quite, entanglement is a property of the entire experimental arrangement to include outcomes and a particular type of source.

So, lets try a different interpretation of Bell's theorem:

Bell's theorem says that lhv accounts which meet certain formal requirements can't possibly reproduce the QM predictions and the observed cos^2 dependency between the angular difference of the polarizer settings and the photon coincidence rate.

This seems ok. So, which formal requirements are, effectively, at fault?

c-limited locality can't be explicitly formalized without having some variable (hidden or not) to express it in terms of. But it seems rather illogical to require an account of joint detection rate in terms of a variable, L, which doesn't determine it. The variability of P(A, B) is solely a function of variations in a global measurement parameter, the angular difference of the polarizer settings. To say that an explicitly local hidden variable account is impossible misses this point. Of course a viable lhv account is impossible, but the reason for this precludes inferring or positing from it that >c propagations exist in Nature.

Since NONlocality isn't a physical mechanism, and since positing ftl propagation speeds (to allow the entangled entities to 'communicate ' with each other) based on Bell, GHZ, etc. theorems is unwarranted, then we're left with the assumption (of mainstream physics) that we live in a c-limited, locally causal universe.

Hence my attempt at a local explanation or understanding (of sorts), but not an explicitly local formalization, for at least a certain class of entanglement experiments -- and a rather more physical understanding of quantum entanglement than can be gotten via the formalism(s) of it.

Quantum nonlocality and quantum superposition refer to formal terms and transformations. EPR, Schrodinger, and many others have pointed out the problematic and sometimes even absurd entailments of taking this as a literal description of the states, configurations, and behaviors of physical objects.

The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

So, considering the above, I still think that the correct answer to the title question of this thread is no, spooky action at a distance (or nonlocality) as envisaged by EPR (or anybody else), isn't a physical possibility.

Are ftl propagations a possibility? Yes, wrt certain worldviews. But they're not necessary to understand the correlations associated with quantum entanglement.

What you're discovering for yourself is that there are two independent ways to account for QM's violation of Bell inequalities -- causal non-locality and/or non-separability. You're correct in saying "the entangled entities don't have to be communicating with each other," because, for example, you could view the entangled quantum system as "one entity" rather than "entangled entities." Another way to instantiate non-separability is get rid of the quantum entities altogether and simply understand the wave function as a description of the the locations, types and orientations of all the experimental equipment from the initiation to the termination of the experiment.

Anyway, the bottom line is that you don't HAVE to invoke FTL communication to account for QM's violation of Bell inequalities. You can rather invoke non-separability.

DrChinese

May4-10, 12:54 PM

If so, then there's a problem with the interpretation of Bell's theorem which says in effect that the observed cos^2 dependency between the angular difference of the polarizer settings and photon coincidence rate can't be due to a c-limited local common cause, ie., an emission produced entanglement.

And yet the emission model(s) accompanying the QM account say that the entanglement is produced via the emission process.

...The physical essence of quantum entanglement is better understood than some commentators on the subject would lead one to believe. It has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These relationships, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism. The entangled entities don't have to be 'communicating' with each other.

The common cause you push is not generally accepted as occurring at the time of emission. As RUTA says, it is the context of the entire setup that is relevant. What QM says is that spin is conserved. It does not say there is a cause, or that it is definite independent of observation.

Not sure what you mean when you say entanglement is "...better understood...", as I don't think it is all that well understood. However, there is in fact a lot of theory around entanglement precisely because a lot can be directly derived from QM. Experiments can be performed using the tools of the trade. If that is what you mean, then I would agree with you.

As to global parameters, you won't find much agreement with your position on that. At least, not in the sense you intend.

ThomasT

May5-10, 03:37 PM

DrChinese and RUTA, thanks for your replies. I might have some questions or comments regarding them, but for now I'm curious about DrC's comment:
As to global parameters, you won't find much agreement with your position on that. At least, not in the sense you intend.
I was just referring to the crossed polarizers. The global measurement parameter is their angular difference. What sense of global parameter did you think I intended?

DrChinese

May5-10, 03:40 PM

DrChinese and RUTA, thanks for your replies. I might have some questions or comments regarding them, but for now I'm curious about DrC's comment:

I was just referring to the crossed polarizers. The global measurement parameter is their angular difference. What sense of global parameter did you think I intended?

The crossed polarizers are not considered global. On the other hand, c is global.

ThomasT

May5-10, 03:42 PM

'AFTER' was the last nail in the coffin for LHV. There was a theoretical possibility that the entangled photons had 'spooky tentacles' that could 'sense' the settings of the polarizer, to pre-agree on LHV, and then run to 'mimic' the QM predictions.Why would they need to 'pre-agree on LHV'? The value (the polarization angle) of the LHV can be anything. It doesn't matter. The correlations are solely a function of the angular difference of the polarizers.

Why else all this work on randomizing the polarizers??In order to close the 'communication loophole'.

It was necessary to do the experiments. And by doing them it was learned that closing this loophole would have no effect on the results.

As we seem to agree, closing all of the loopholes will have no effect on the results -- except to bring the QM predictions closer to the raw data.

(I googled "Bell's lhv ansatz" and got 2 hits, both point at you at PF ... is this your own 'invention'?)The word ansatz just means formulation. There's at least one other active thread in this forum discussing Bell's lhv ansatz.

As I understand you dismiss LHV and "spooky action at a distance" and loopholes. What's left?ftl locality ? -- but then, I 'dismiss' that too. :smile: That leaves c-limited locality -- which seems to work for pretty much everything.

Nothing is just being dismissed out of hand. If you disagree with the reasons, then we can discuss that.

You mentioned Local Hidden Constants in an earlier, but that doesn't work either ...That just refers to the relationship between the entangled optical disturbances. It does 'work' in that it's part of the QM treatment. And, given that the application of the cos^2 Theta rule doesn't contradict locality, then we have a simpler and more physical understanding of entanglement than saying that "nonlocality (or ftl) did it".

It's quite strange to see the strong argumentation against Alain Aspect et al.Who's arguing against Aspect? I like to use his Bell test(s), considered in the ideal, because the setups are easier to understand than most of the more recent one's using SPDC photons.

Don't you think it's quite farfetched to dismiss the official conclusion, and replace it with your 'personal speculations', based on an optical law from 18th century - basically saying "some light is lost in the polarizer"...?Yes that would be farfetched. :smile:

I can't do the calculations, but I suspect that the probabilities for the 18th century Malus Law too by chance reproduce exactly the expected results predicted by QM, is even more 'miraculous' than "Spukhafte Fernwirkung"...Consider an Aspect-like setup where polarization-entangled counter-propagating photons are analyzed by crossed polarizers. Now visualize both polarizers on the same side. The results are the same as with one polarizer on each side. The side with the two polarizers is called a polariscopic setup and it's the sort of setup where Malus discovered the optical law that bears his name. Now visualize the original setup again. Do you see why this optical law applies? If so, then I would agree that that would be a miracle. :smile:

the latest discoveries by Bell & Aspect prove that if we look at one particle here - it immediately settles the properties of a twin particle, on the other side of the universe?It depends on what you mean by "settles". It really is important how these things are phrased. Somebody might get the wrong idea. :smile:

Wrt the Bell test, if it's known that the polarizer settings are aligned or perpendicular (if the angular difference is 0 or 90 degrees), then if the detection attribute at one end is known, then the detection attribute at the other end can be deduced. These are the only two settings where such deductions are possible. Do the photons really need to be communicating with each other?

Wrt EPR, if one particle of an entangled pair is detected at a certain distance from the emitter at time, t, then the position of the other particle at t can be deduced from this information.

I assume you've read the EPR paper. Where does the spooky nonlocality that you seem so enamored with come from?

ThomasT

May5-10, 03:50 PM

The crossed polarizers are not considered global. On the other hand, c is global.How about their angular difference? If you change the setting at one end or the other, then |a-b| is instantaneously altered.

DrChinese

May5-10, 03:59 PM

How about their angular difference? If you change the setting at one end or the other, then |a-b| is instantaneously altered.

That is a fact. But no one would know that for a while. a and b are local parameters, and their difference does not constitute a global parameter. Neither is the difference between my bank account and my desired spending...

ThomasT

May5-10, 04:13 PM

That is a fact. But no one would know that for a while.It's a fact of the experimental setup. We know it independent of whether it's actually done or not.

a and b are local parameters, and their difference does not constitute a global parameter.What would you call |a-b| then?

ThomasT

May6-10, 12:34 PM

The common cause you push is not generally accepted as occurring at the time of emission.I didn't know that. Anyway, the emission model(s) can be interpreted that way. What do you think? Do the emission preparations enable the photons to 'communicate' sometime after emission via some ftl means, or are their motions related during the emission process.

As RUTA says, it is the context of the entire setup that is relevant.Of course it's relevant. But the deep cause of the correlations is that the motions of the particles are related -- and the best assumption as to when this relationship is created is that it's created during the emission process.

What QM says is that spin is conserved. It does not say there is a cause, or that it is definite independent of observation.The way QM is formulated, the experimental setups, and the observations allow certain rational assumptions regarding the deep reality of things. If we assume that there are no deep causes, that there is no underlying reality, then what are we doing?

Not sure what you mean when you say entanglement is "...better understood...", as I don't think it is all that well understood.I think it's well enough understood to say what I've said about it, which I think is a better understanding of it than attributing it to nonlocal or ftl communication between entangled entities or simply saying that it's due to the experimental setups that produce it.

ThomasT

May6-10, 12:37 PM

Not quite, entanglement is a property of the entire experimental arrangement to include outcomes and a particular type of source.Recall my statement that entanglement has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system?

The relationship between, say, counter-propagating optical disturbances in the Aspect experiments is the deep cause of the entanglement that is a property of the entire experimental arrangement, and the way I read the emission model is that this relationship is produced via the emission process and therefor exists prior to filtration of the optical disturbances.

What you're discovering for yourself is that there are two independent ways to account for QM's violation of Bell inequalities -- causal non-locality and/or non-separability.I don't think so. I think that 'causal non-locality' is a contradiction in terms. It's not a physical account of anything.

My physical interpretation of quantum nonseparability is that the emission-produced motional relationship between the optical disturbances makes them 'nonseparable' wrt the analysis of this relationship via a common or global measurement parameter (the angular difference of the polarizer settings).

The fact that it's this relationship that's being analyzed in the joint context, and not the polarization angle (which is what's being analyzed in individual measurements), is what renders Bell's lhv formulation an inadequate (read: incorrect) representation of the experimental situation, and is therefore what causes Bell inequalities based on the predictive limits of that formulation to be violated by QM predictions and experimental results.

This nonseparability is adequately represented in QM in the nonfactorability of the joint, entangled state.

You're correct in saying "the entangled entities don't have to be communicating with each other," because, for example, you could view the entangled quantum system as "one entity" rather than "entangled entities."
The entangled quantum system can be viewed (physically interpreted) in terms of physically separate entangled entities that don't have to be communicating with each other if their motions are related via the emission process.

The usual response to this is something like: "But Bell proved that there can't be a local common cause for the entanglement." However, as has been shown, Bell didn't prove this. What he did prove was that no lhv theory meeting his formal requirements for an lhv theory can reproduce the full range of QM predictions.

Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

IcedEcliptic

May6-10, 01:45 PM

Recall my statement that entanglement has to do with relationships between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system?

The relationship between, say, counter-propagating optical disturbances in the Aspect experiments is the deep cause of the entanglement that is a property of the entire experimental arrangement, and the way I read the emission model is that this relationship is produced via the emission process and therefor exists prior to filtration of the optical disturbances.

I don't think so. I think that 'causal non-locality' is a contradiction in terms. It's not a physical account of anything.

My physical interpretation of quantum nonseparability is that the emission-produced motional relationship between the optical disturbances makes them 'nonseparable' wrt the analysis of this relationship via a common or global measurement parameter (the angular difference of the polarizer settings).

The fact that it's this relationship that's being analyzed in the joint context, and not the polarization angle (which is what's being analyzed in individual measurements), is what renders Bell's lhv formulation an inadequate (read: incorrect) representation of the experimental situation, and is therefore what causes Bell inequalities based on the predictive limits of that formulation to be violated by QM predictions and experimental results.

This nonseparability is adequately represented in QM in the nonfactorability of the joint, entangled state.

The entangled quantum system can be viewed (physically interpreted) in terms of physically separate entangled entities that don't have to be communicating with each other if their motions are related via the emission process.

The usual response to this is something like: "But Bell proved that there can't be a local common cause for the entanglement." However, as has been shown, Bell didn't prove this. What he did prove was that no lhv theory meeting his formal requirements for an lhv theory can reproduce the full range of QM predictions.

Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

I believed that Bell Inequality had ruled out all of the Local Hidden Variable theories that existed. What theories are left, that have what QM offers of predictions?

DrChinese

May6-10, 02:21 PM

...Unfortunately, and to reiterate, Bell's formal requirements for an lhv theory simply misrepresent the experimental situation. Since the determining hidden parameter in the joint context (the photons' motional relationship) is different from the determining hidden parameter in the individual contexts (the photons' polarization angle), then the joint context can't possibly be viably represented in terms of the individual contexts.

That sounds all well and good, but:

0, 120, 240: give me the dataset. The rest is just words, like "pigs fly". Easy to say, give me an example that addresses these. I learned this from Bell, so if it doesn't apply, it should be easy to come up with.

DevilsAvocado

May6-10, 05:27 PM

Why would they need to 'pre-agree on LHV'? The value (the polarization angle) of the LHV can be anything. It doesn't matter. The correlations are solely a function of the angular difference of the polarizers.

ThomasT, I must say that it’s not only "Spukhafte Fernwirkung" that’s a mystery to me – your 'interpretation' of EPR & Bell test experiments is a 'mystery' as well (no offence).

First: When talking about angle (and settings), I think that most interested folks here understand that it’s the angles of the analyzers we are talking about, and not LHV. When talking about 'pre-agreement' and LHV, it’s the 'presetting' of the particle spin (of the pair) that’s addressed, which can be spin up(+) or spin down(-).

Second: The bright geniuses Albert Einstein & Niels Bohr had a discussion for decades about EPR. There was no way (or at least extremely difficult) to tell the difference between QM predictions and LHV in a 'static' EPR setup, and that’s why Einstein & Bohr never were able to finally settle the question. They never thought that EPR could be solved by an experiment/test – this was all a matter of interpretation in 1935.

Third: 30 years later John Bell introduces the absolutely brilliant idea to 'enforce' probability into the measurement of EPR, to be able to distinguish LHV from QM predictions, and this is implemented in form of varying angles of the analyzers.

http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Bells-thm.png/600px-Bells-thm.png

The spin of the particle pair could be any combination of spin up(+)/spin down(-), i.e. correlated (+,+) (-,-) or non-correlated (+,-) (-,+).

When Alice and Bob measure the spin of entangled particles along the same axis (180°), they get identical results 100% of the time (= correlation of 1.0).

When Bob measures at orthogonal angles (45°) to Alice’s measurements, his measurement matches hers 50% of the time (= correlation of 0.0).

I think that we all agree that QM and Heisenberg's uncertainty principle is valid, and that we can only relay on probability distributions when predict the behavior of QM particles:

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Standard_deviation_diagram.svg/450px-Standard_deviation_diagram.svg.png

The QM probability distribution makes a 'footprint' in Bell test experiments, in the form of a cosine curve from correlated at 0° and anti-correlated at 90°. In contrast, Bell’s theorem places a straight-line limit on the curve that any LHV model can follow from 0° to 90°:

http://i39.tinypic.com/2wr1cgm.jpg

The most obvious difference between any LHV theory and QM predictions is when the analyzer alignment is 22.5°; QM gives a 0.71 correlation, whereas the LHVT "straight-line-limit" is 0.5.

(I know, it’s the second time I show this picture, but it really says it all...)

Now back to 'pre-agree on LHV': I do hope that you now clearly see the logic in a 'pre-agreement' to make the LHV theory work?? The ONLY way to 'compete' with QM, when the analyzer alignment e.g. is 22.5°, is for the 'magic LHV' to make 'pre-agreement' on a 0.71 correlation – before leaving the source!!

I.e. for the LHVT to work at 22.5°, sending 100 pairs of photons, 71 pairs must pre-agree on a correlated result (+,+) and 29 pairs must pre-agree on a non-correlated result (+,-) (-,+).

(AFAICT this must also lead to some "LHV Global Counter", which makes the LHVT even more troublesome...!?!? :bugeye:)

IF the analyzer alignments are settled AFTER the LHVT photons LEFT the source – they can pre-agree on anything (from building a house on Mars to making gold) but they CANNOT be saved – the LHV correlation can NEVER compete with QM predictions in this kind of Bell test!!

If the LHVT make a decision later, after they left the source, we’re back to "Spukhafte Fernwirkung" again, and the L in LHV must be replaced by NL (nonlocal).

That’s why 'AFTER' and angle is "des Pudels Kern" in Bell test experiments. Get it?

In order to close the 'communication loophole'.

Meaning exactly what I just explained + 400 meter, right? :wink:

Who's arguing against Aspect?

Is the 'Malus Law Theory' embraced by Aspect as well?? :smile:

Do you see why this optical law applies? If so, then I would agree that that would be a miracle. :smile:

No sorry, I don’t see how the MLT applies to Bell test experiments? And my best argument is that Bell test experiments have been executed using 9Be+ ions (an isotope of Beryllium, steel-gray, strong, lightweight brittle alkaline earth metal, passing the optical MLT to the closet), with the same successful correlation result. Bell’s own idea was not to use photons (I think it was 'atoms'?), so there is no direct connection between Bell test experiments and photons, except for that’s the easiest way to perform the experiment.

It depends on what you mean by "settles". It really is important how these things are phrased. Somebody might get the wrong idea. :smile:

I agree, we really don’t know exactly what’s going on. There are different interpretations, trying to explain, but no 'official explanation'. I do hope that we all agree that 'something happens' that seems to violate locality, and don’t blame all on good old Etienne-Louis Malus! :wink:

I assume you've read the EPR paper.

You mean Dr. Bertlmanns Socks? :approve:

http://homepage.univie.ac.at/reinhold.bertlmann/pics/comic.gif

Serious, I’m only a layman and I have not mathematically penetrated every 'angle' of EPR & Bell's theorem, but I persuade myself I got the "Big Picture" fairly correct. There are scary examples of people who gets stuck with the nose in a "probability paradox" (http://www.physicsforums.com/showthread.php?t=399795), that make them think it’s physical impossible to have one red and one white card in a box, and take them out to inspect the colors, because the probability for one card/color (according to their "homemade probability chains") is not 0.5, but 0.25!?!? :rofl:

But when I get the time, I’ll do all my 'homework', promise... :rolleyes:

Have you read the EPR paper? :smile:

@RUTA – I did answer (http://www.physicsforums.com/showthread.php?p=2701710#post2701710) your reply, though very late (sorry), just wanted you to know...

zonde

May7-10, 03:32 AM

When Alice and Bob measure the spin of entangled particles along the same axis (180°), they get identical results 100% of the time (= correlation of 1.0).
If you mean that QM predicts that then yes that is so.
But if you mean that this prediction is experimentally tested then no this is not tested. There is only experience that you can get close to this prediction under certain conditions and certain assumptions. But common experience is not scientifically verified fact.
To verify this prediction in scientific fashion you have to test what happens when you vary conditions and if variations in results are justified by theoretical model or not and whether results agree with assumptions to testable limits or not.

DevilsAvocado

May7-10, 07:36 AM

If you mean that QM predicts that then yes that is so.

Correct, and to be fair – LHV can also produce this correlation, but then it all goes 'bananas'... :wink:

But if you mean that this prediction is experimentally tested then no this is not tested.

Okay...?? If you are correct, then this must mean Alain Aspect is an imposter?? Presenting false data on public lectures!? :confused:

Here’s one of Alain Aspect’s own slide:
http://i42.tinypic.com/r6xwxz.jpg

Alternatively: Alain Aspect is one of your "who-cares-it-doesn’t-bother" scientists... ?:bugeye:?

By the way, I did answer your "not bother"-assumption in post #208 (http://www.physicsforums.com/showpost.php?p=2697161&postcount=208).

zonde

May7-10, 09:13 AM

Therefore, your "not bother" assumption is quite farfetched. The man or woman, who does find this limit of QM will get a Nobel, lots of fame, and money – besides the scientific thrill and satisfaction.

To "not bother" in this case, is to not be a real scientist. I’m sorry.
From this paper:
Bell's Theorem : The Naive View of an Experimentalist (http://arxiv.org/abs/quant-ph/0402001)
"On the other hand, the fair sampling assumption is very reasonable, and easy to express."
I call this "not bother".

That must be Alain Aspect! :wink:
From the same paper:
"Clear violations of Bell’s inequalities have been found, under the assumption that the « fair sampling hypothesis » holds."
Seems that it's not Alain Aspect who is wearing the tin foil hat but someone else. :wink:

IcedEcliptic

May7-10, 12:58 PM

From this paper:
Bell's Theorem : The Naive View of an Experimentalist (http://arxiv.org/abs/quant-ph/0402001)
"On the other hand, the fair sampling assumption is very reasonable, and easy to express."
I call this "not bother".

From the same paper:
"Clear violations of Bell’s inequalities have been found, under the assumption that the « fair sampling hypothesis » holds."
Seems that it's not Alain Aspect who is wearing the tin foil hat but someone else. :wink:

Are you seriously making the fair sampling loophole argument?! Really, I was not aware this was still even marginally accepted anymore.

RUTA

May7-10, 01:10 PM

Are you seriously making the fair sampling loophole argument?! Really, I was not aware this was still even marginally accepted anymore.

It's been at least 10 years since I saw someone present this argument at a foundations conference. The community has moved on.

IcedEcliptic

May7-10, 01:14 PM

It's been at least 10 years since I saw someone present this argument at a foundations conference. The community has moved on.

Thank you RUTA, reading your discussion with Dr. Chinese has been very elucidating. I feel I have a deeper understanding of of non-locality as a result. Not a decision on my part, but so much to ponder.

ThomasT

May7-10, 04:32 PM

I believed that Bell Inequality had ruled out all of the Local Hidden Variable theories that existed. What theories are left, that have what QM offers of predictions?There's good reason to believe that, not just due to Bell inequalities, lhv representation of entanglement is impossible.

What I'm trying to explore is why, and I think that the correct answer to that will have nothing whatsoever to do with nonlocality or ftl locality or any of the rather exotic explanations that have been offered over the years.

Of course, we're not all on the same page here. :smile:

And, sorting things out can be a bit tedious.

IcedEcliptic

May7-10, 08:14 PM

There's good reason to believe that, not just due to Bell inequalities, lhv representation of entanglement is impossible.

What I'm trying to explore is why, and I think that the correct answer to that will have nothing whatsoever to do with nonlocality or ftl locality or any of the rather exotic explanations that have been offered over the years.
<snip>

Why do you believe that?

DevilsAvocado

May8-10, 06:58 AM

Why do you believe that?

Because ThomasT has his own version of the 'scientific model': First you decide how the world should work according to your personal taste, and nothing else – then you make up pseudo-mathematical theories that seems to fit your personal view.

That’s why we have seen a long discussion on how the 18th century optical Malus Law can reproduce QM predictions, which has no connection to reality. For Malus Law to work at 22.5°, sending 100 pairs of photons, 71 pairs must agree on a correlated result (+,+) and 29 pairs must agree on a non-correlated result (+,-) (-,+).

And not only that - the 18th century optical Malus Law must keep a Global Counter on the correlated/non-correlated result for 100 pairs of photons! Amazing, isn’t it!?

And when ThomasT is proven wrong – he just refuse to reply – blaming on things being a bit tedious.

And I agree – this is getting tedious – in the manner this debate is performed.

Finally: I must point out that I from the beginning had the same view as ThomasT – this "spooky action at a distance" can’t be true! This is just mathematical mumbo-jumbo from physicist trying to raise more funding by presenting spectacular theories!

But I changed my mind. And I can assure ThomasT – it didn’t hurt at all...

my_wan

May8-10, 11:18 PM

To the OP question: In practice no. In principle we can't be sure. Reading the debate here should make that clear, but I'd like to add something to the debate that appears to have poor representation thus far.

I have a predisposition toward looking for so called loopholes to avoid 'spooky action at a distance', but when I see the case for these classes of models overstated and pinned on distinct ontologies within a class it gets painful. I'm going to attempt a description of the general features of this class of model, but it must be understood that the only justification is that Bell's Theorem fails to rule them out. It's not even a claim that any model in this class exist that's capable of superseding the Standard Model. This thread is the wrong place for anybody that possessed that. RUTA's Blockworld interpretation appears to fit within this class, in an ontologically inverted sort of way. The fact that it run counter to my predispositions in no way limits my fascination with it.

First let's look at the assumptions of Bell's Theorem. Using a list provided by DrC:a. Realism - a la EPR's "elements of reality".
b. Hidden Variables - Essentially a deduction from realism.
c. Non-contextuality - the context of an experiment does not matter to the realism of an observable.
d. Counterfactual Definiteness - you can speak meaningfully about unmeasured observables.

DrC expressed a distaste in discussing the implications of these terms due to semantic arguments. I wish to describe only the class as clearly as possible, the semantic choices are not a legitimate issue in this context. RUTA's Blockworld is a massive distortion of my prejudices, but apparently remains within this class.

The notion behind a 'hidden variable' is that a variable exist that is 'hidden', obeys Einstein realism, and local. EPR experiments obviously can't perform experiments directly on these variables that are presumed 'hidden', else the argument moots itself. Instead we take a measurable variable, such as spin, make some assumptions about the relationship between the hidden element and the measurable variable, and use the measurable variable as a proxy for probing the hidden variable. Thus we are basing our results on this presumed relationship between these hidden and measured variables. This is in general what's referred to when it's said that counterfactual definiteness is a basic assumption of Bell's Theorem. Essentially it presumes that the measured variable is an observer independent absolute property defined by the hidden variables. Thus non-contextuality is related to counterfactual definiteness by the property of observer independent absolutes. What Bell's Theorem proves, from my perspective, is that, if such hidden variables exist, all known measurable variables must be emergent properties of these hidden variables, not inate properties of them.

This in no way proves it is possible to contextualize 'hidden' variables in such a way to recover QM, and people can argue forever on the semantics of how to do that. It merely identifies a class of 'hidden' variables which Bell's Theorem fails to rule out. There are a great many unrelated variables which are obviously contextual. One of the simplest being velocity. Temperature also qualifies, as any given molecule in a gas may be considered at rest between collisions. There's nothing strange about contextual variables in general, except in classical cases we can define definite symmetries relative to known parameters. In the QM case we have only correlations in randomness that interferes with itself. This is further complicated by the nature of quantization itself and the inability to directly observe the processes. Instead we are stuck with inferences from point observations in which our experiments to observe them play a role in the outcomes, for reasons that can also be debated.

I like to think that sub-Planck physics is involved, which not only contains QM/GR but allows QM/GR to be derived. Yet what I like is of no consequence to physics. Ontological claims of what will work, as well as claims of the impossibility of avoiding non-locality, etc., is mooted by the facts as we know them at this time, in spite of the excellent work of Bell and many many others.

DevilsAvocado

May9-10, 07:54 AM

... or we could just make it simple and say:

Local Hidden Variable Theory = Norwegian Blue Parrot

<object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/npjOSLCR2hE&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/npjOSLCR2hE&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>

DevilsAvocado

May9-10, 08:15 AM

Frame Dragger is BACK! :cool:

Frame Dragger

May9-10, 08:50 AM

Frame Dragger is BACK! :cool:

Heyo DevilsAvocado! Love the Montey Python reference, "...it's gone and joined the choir invisible, this, is a DEAD PARROT!." :rofl:

DevilsAvocado

May9-10, 09:00 AM

...it's gone and joined the choir invisible
Yeah! You got it! Choir Invisible = Hidden Variable !!! :biggrin:

Great to have you back FD! I was real worried there for awhile... Now let’s get real ironic AGAIN!!! :rofl:

(got to go now, see you later terminator)

DrChinese

May9-10, 12:15 PM

DrC expressed a distaste in discussing the implications of these terms due to semantic arguments...

The notion behind a 'hidden variable' is that a variable exist that is 'hidden', obeys Einstein realism, and local. EPR experiments obviously can't perform experiments directly on these variables that are presumed 'hidden', else the argument moots itself. Instead we take a measurable variable, such as spin, make some assumptions about the relationship between the hidden element and the measurable variable, and use the measurable variable as a proxy for probing the hidden variable. Thus we are basing our results on this presumed relationship between these hidden and measured variables. This is in general what's referred to when it's said that counterfactual definiteness is a basic assumption of Bell's Theorem. Essentially it presumes that the measured variable is an observer independent absolute property defined by the hidden variables. Thus non-contextuality is related to counterfactual definiteness by the property of observer independent absolutes. What Bell's Theorem proves, from my perspective, is that, if such hidden variables exist, all known measurable variables must be emergent properties of these hidden variables, not inate properties of them.

This in no way proves it is possible to contextualize 'hidden' variables in such a way to recover QM, and people can argue forever on the semantics of how to do that. It merely identifies a class of 'hidden' variables which Bell's Theorem fails to rule out. ...
I like to think that sub-Planck physics is involved, which not only contains QM/GR but allows QM/GR to be derived. Yet what I like is of no consequence to physics. Ontological claims of what will work, as well as claims of the impossibility of avoiding non-locality, etc., is mooted by the facts as we know them at this time, in spite of the excellent work of Bell and many many others.

I realize there may be some differences in what kind of hidden variables might exist. My thing is to avoid getting into a semantic argument (I would rather focus on the physics). The key to that is to FIRST accept that there cannot be local hidden variables of the type identified by EPR (i.e. no objective elements of reality). I think you can then move on to extend the scope further, to include hypothetical classical components of elements of reality (i.e. where the element of reality is an observable, but the component may not be).

In Relational BlockWorld, I like to say the the hidden variables lay in the future. RUTA will probably choke on that description. :smile: If you accept that, then you would probably end up concluding that the future influences the past and causality is lost. RUTA would probably be OK with that, because he considers RBW to be acausal. :smile:

There also could be all kinds of weird rules at the subatomic level that are hidden from us. But the problem with that "escape" is that where else do they manifest themselves? Were there other evidence, it would make more sense.

RUTA

May9-10, 12:26 PM

In Relational BlockWorld, I like to say the the hidden variables lay in the future. RUTA will probably choke on that description. :smile: If you accept that, then you would probably end up concluding that the future influences the past and causality is lost. RUTA would probably be OK with that, because he considers RBW to be acausal. :smile:

If you want to characterize future experimental outcomes as the "hidden variables" needed to understand EPR-Bell phenomena per RBW, then what you said is absolutely true.

DrChinese

May9-10, 01:03 PM

If you want to characterize future experimental outcomes as the "hidden variables" needed to understand EPR-Bell phenomena per RBW, then what you said is absolutely true.

That is what I meant, but you said it better. It is almost as if there are many little hands reaching out from the past, waiting for a handshake before their impact is finalized. Gee, now I am starting to sound like Yoda Jedi.

IcedEcliptic

May9-10, 01:30 PM

RUTA

May9-10, 01:49 PM

That is what I meant, but you said it better. It is almost as if there are many little hands reaching out from the past, waiting for a handshake before their impact is finalized. Gee, now I am starting to sound like Yoda Jedi.

That's Cramer's Transactional Interpretation. In TI, there is literally a wave "coming from" the future experimental outcomes to interact with the wave leaving the source at the beginning of the experiment. That's how they get the Born rule. Of course, if there are waves coming from the future to influence the present, then the future is already "there." And, since the present is the future of the past, the past must also be "there." That's the blockworld wherein "nothing happens." Here's a nice quote from Geroch (General Relativity from A to B, University of Chicago Press, Chicago, 1978, pp. 20-21):

There is no dynamics within space-time itself: nothing ever moves therein; nothing happens; nothing changes. In particular, one does not think of particles as moving through space-time, or as following along their world-lines. Rather, particles are just in space-time, once and for all, and the world-line represents, all at once, the complete life history of the particle.

So, why bother trying to tell "stories" about "the future influencing the past?"

ThomasT

May9-10, 02:01 PM

Why do you believe that?I, and others, think the non-viability of lhv representations is due to a problem with the formal requirements not fitting the experimental situations, and, if that's so, then ftl 'explanations' for BI violations (and the correlations) are obviated.

ThomasT

May9-10, 02:05 PM

ThomasT, I must say that it’s not only "Spukhafte Fernwirkung" that’s a mystery to me – your 'interpretation' of EPR & Bell test experiments is a 'mystery' as well (no offence).None taken. :smile: Spooky action at a distance is just a collection of terms that has no physical meaning. I'm pretty sure that EPR meant it facetiously. If what I'm saying about EPR and Bell is a mystery to you, then all I can tell you is to keep studying and thinking about this stuff and what I'm saying about it will eventually make sense to you -- even though you might still disagree with what I'm saying about it. In any case, I think we're both fascinated by the mysteries of the quantum realm, and that's a key ingredient in motivating one to learn more about this stuff.

First: When talking about angle (and settings), I think that most interested folks here understand that it’s the angles of the analyzers we are talking about, and not LHV. When talking about 'pre-agreement' and LHV, it’s the 'presetting' of the particle spin (of the pair) that’s addressed, which can be spin up(+) or spin down(-).Where do you think it's most logical to assume that the relationship between the counter-propagating photons is created -- (1) during the emission processes which are so carefully and subtley prepared by the experimenters with the intention of doing just that, or (2) sometime after emission due to ftl communication between the photons?

Part of what I'm saying is that choosing (1) is ok because neither Bell nor GHZ rule it out. And if (1) is ok, then (2) isn't warranted.

I agree, we really don’t know exactly what’s going on. There are different interpretations, trying to explain, but no 'official explanation'.Agreed.

I do hope that we all agree that 'something happens' that seems to violate locality ... ...The discussion in this thread is centered on the fact that we don't all agree that something happens (wrt quantum entanglement) to violate c-limited locality.

ThomasT

May9-10, 02:09 PM

That sounds all well and good, but:

0, 120, 240: give me the dataset. The rest is just words, like "pigs fly". Easy to say, give me an example that addresses these. I learned this from Bell, so if it doesn't apply, it should be easy to come up with.I think we agree that viable lhv accounts of entanglement are impossible. The question is why. This is what we're trying to sort out.

You're saying that it might be due to nonlocal effects of one side of the experimental setup on the other. I'm saying that not only is that not a physical explanation (equivalent to "pigs fly"), but also that there is a simpler, physical/formal, explanation for why Bell inequalities are violated experimentally and for the lhv inconsistencies via the GHZ theorem -- and that it might have to do with requiring the joint context to be represented by a hidden variable which is irrelevant wrt determining the results of the joint context.

The "give me the dataset" question you're asking has to do with the simplest version of Bell's theorem, the simplest Bell's inequality (which I referred to in the recent, really long, thread ostensibly dealing with the fair sampling loophole -- which loophole we also agree doesn't matter wrt determining the meaning of BI violations and GHZ inconsistencies). This is why I bring up the cos^2 Theta rule wrt optical Bell tests where it clearly does apply. There's simply no reason to assume that the application of this optical law isn't in accord with c-limited local causality. And yet, the interpretation of Bell's theorem which has Bell's theorem pertaining to what does or doesn't exist in reality, wrt this situation, says, in effect, that "the correlation between the angular difference of the polarizers and the joint detection rate, formally expressed in terms of the local hidden variable, can't possibly duplicate the full range of qm results -- ie., the full cos^2 Theta angular dependency -- IF THE ENTANGLEMENT OF THE OPTICAL DISTURBANCES HAS A LOCAL COMMON CAUSE.

Now, if you delete the part in caps, then I agree. The joint detection rate can't possibly be viably expressed in terms of the LOCAL hidden variable (which entails that it can't possibly be viably expressed in a separable form, a form that is factorable into an expression of the individual detection rates). This is because the determining factors in the joint context are common, or (despite your objection to this terminology) global, variables: 1) the angular difference between the polarizers, and 2) the angular difference between the optical disturbance incident on the polarizer setting at one end and the optical disturbance incident on the polarizer setting at the other end.

This is, I think, the correct physical interpretation of the formal expression of 'quantum nonseparability' for the experimental situation under consideration. And, as you can see, it has nothing to do with nonlocal or ftl 'influences' between entangled photons.

ThomasT

May9-10, 03:06 PM

... ThomasT has his own version of the 'scientific model': First you decide how the world should work according to your personal taste, and nothing else – then you make up pseudo-mathematical theories that seems to fit your personal view.

And when ThomasT is proven wrong – he just refuse to reply – blaming on things being a bit tedious.

And I agree – this is getting tedious – in the manner this debate is performed.

Finally: I must point out that I from the beginning had the same view as ThomasT – this "spooky action at a distance" can’t be true! This is just mathematical mumbo-jumbo from physicist trying to raise more funding by presenting spectacular theories!If you're interested in learning, as I am, then a little silliness is ok, and even somewhat refreshing when one get's saturated with the stuff that's being considered. However, stuff like the above is not ok. Not only is it a false personal attack, but, more importantly, it doesn't further the discussion.

Clearly, we're all operating from some degree of ignorance. A primary function of this forum (and science in general) is to help us learn about the world.

Learning sometimes requires actually thinking.

If you spend all your time dealing with youtube videos, cheerleading, criticizing, fashioning tin foil regalia for you and your pets, snipping quotes here and there, etc., etc. -- basically anything but actually thinking about and researching the stuff you're commenting on -- then ... well, your (mostly off-topic) posts speak for themselves.

Now, there's a legitimate consideration to explore, a question about the applicability of Bell's (and GHZ's) formal requirements/constraints that might obviate ftl 'influences' between entangled particles, that hasn't been definitively resolved.

my_wan

May9-10, 05:53 PM

DrC,
There's nothing in your response that I factually disagree with, but I'm going to make some points wrt semantics and the importance of dealing with them. Your certainly not the primary audience I have in mind, but hopefully it'll provide food for thought.

I realize there may be some differences in what kind of hidden variables might exist. My thing is to avoid getting into a semantic argument (I would rather focus on the physics).
Yes I generally support this sentiment. It's more difficult in the context of EPR because the physics we have merely defines constraints of a presumably unknown model, which is dependent on ontological features which are semantically defined. What I find most distasteful in this context is singling out an ontology, and making ad hoc demands and rejections of the physics we do have on those grounds. People lose winnable debates doing this all the time by overstating both their positive and negative claims.

The key to that is to FIRST accept that there cannot be local hidden variables of the type identified by EPR (i.e. no objective elements of reality).
Again I absolutely agree, the constraints imposed by BI are absolutely real, and constitute some real physical constraints we have to work with in this area. Denial should be and is costly for those who do so. However, many people are predisposed to ontologically invert the words used here, as I'll articulate next. Debates that fail to recognize this do get painful.

I think you can then move on to extend the scope further, to include hypothetical classical components of elements of reality (i.e. where the element of reality is an observable, but the component may not be).
This is the type of model I like playing with. The semantics issues arise when you ask: Is it the elements postulated to be ontically real and remain unobservable that are the "elements of reality", or is it the measurable variables for which their existence is dependent on the relative configuration space of the ontic elements? Einstein realism is best served by the first, empiricism by the second. In fact there is no physical significants to these ontological distinctions whatsoever, and those seeking Einstein realism would be well served to recognize the empirical perspective. Pure empiricism may have limits, but it forever remains the sole source of cogency, legitimacy, for any theoretical model. Arguing the absolute legitimacy of one ontology over the other in itself is a no-go. If we accepted raw claims like this we'd still be stuck on Aristotle. Hence your focus on the physics is far more than justified, just not entirely feasible in the face of unknowns or what specific constraints on such unknowns actually entails.

In Relational BlockWorld, I like to say the the hidden variables lay in the future. RUTA will probably choke on that description. :smile: If you accept that, then you would probably end up concluding that the future influences the past and causality is lost. RUTA would probably be OK with that, because he considers RBW to be acausal. :smile:
http://www.physicsforums.com/images/smilies/laughing.gif
I do find it an ugly distortion of my ontological predispositions, but for the reasons I provided above I'm still undecided how it'll fair under various ontological transforms. RUTA's response was a bit predictable, RUTA appears quiet adept at navigating these ontological mine fields. Makes it all the more fascinating.

There also could be all kinds of weird rules at the subatomic level that are hidden from us. But the problem with that "escape" is that where else do they manifest themselves? Were there other evidence, it would make more sense.
Yep, the unknown is a beast. I can't rightly or legitimately get into much detail of my own perspective in this thread, but I generally tend to think complex rule sets indicate the need to look deeper for simpler ones. The range of empirical data involved is extensive, for which EPR is just a small piece. I'm not really happy with any mere interpretation, or anything short of unification. I also tend to find ad hoc rules crafted solely to sweep under the rug, make unobservable, problem issues highly distasteful. Unfortunately I can't honestly yell BS either without something better on empirical, not ontological, grounds.

IcedEcliptic

May9-10, 06:35 PM

I, and others, think the non-viability of lhv representations is due to a problem with the formal requirements not fitting the experimental situations, and, if that's so, then ftl 'explanations' for BI violations (and the correlations) are obviated.

What others? What separation of the source would satisfy?

DevilsAvocado

May9-10, 07:03 PM

ThomasT please explain – In what way is this ok, and furthering the discussion:
... If you spend all your time dealing with youtube videos, cheerleading, criticizing, fashioning tin foil regalia for you and your pets, snipping quotes here and there, etc., etc. -- basically anything but actually thinking about and researching the stuff you're commenting on -- then ... well, your (mostly off-topic) posts speak for themselves. ...

Criticizing? You’re talking about this?
Nice rant, but (1) I didn't say anything about Bell test loopholes, ...

Tin foil regalia? Do you mean this initial occasion of derogatory insinuation?
... There is nice picture that I spied in another thread: ...

YouTube videos? Well, I have to pass that complaint to PF ADMIN, since there is clearly a function for embedded YouTube videos in the editor, which most probably is meant to be used.

... basically anything but actually thinking about and researching the stuff you're commenting on ...
I haven’t fully understood your implementation of the 18th century optical law yet, but you must clearly be exaggerating – in claiming that it can be used for mind reading as well??

I think that those who followed this thread from start clearly can see what’s true or false in everything that ThomasT is claiming.

Finally I must inform any other reader that dear old ThomasT deliberately has distorted the quoting. If ThomasT does this again, I will report him, since this is clearly a violation of Physics Forums Global Guidelines:

"When you quote from a post, please delete large sections that are not directly relevant to your response, to make reading easier, but do not distort the original poster's meaning in the process."

Here is the correct quote:
... Finally: I must point out that I from the beginning had the same view as ThomasT – this "spooky action at a distance" can’t be true! This is just mathematical mumbo-jumbo from physicist trying to raise more funding by presenting spectacular theories!

But I changed my mind. And I can assure ThomasT – it didn’t hurt at all...

Frame Dragger

May9-10, 08:18 PM

I wouldn't want to be without DA's contributions to this thread; he brings an element of levity and concise thought that can be lost sometimes. RUTA, you and Dr C really make this thread perfect for me, but I must be honest and say ThomasT, you seem to be picking a fight here. I know that, because I've picked a few in my time as well (as indicated by the line through my name for 10 days). I don't believe DA is being mean, he's just expressing what RUTA did very simply: your point is not scientific, not in the spirit of inquiry into this matter, and you refuse or are unable to share a theory of your own to counter the matters at hand.

The issue here is not: "ftl" anything when considered within the QM framework. Is there a better theory yet to come? Sure! Is it here yet? No, and until it is this kind of random challenge to otherwise reasonable and well accepted points is fruitless. Can there be a fair sampling that would satisfy you? Why don't you share your view, with the math, rather than simply verbally dissecting those of others?

DevilsAvocado

May9-10, 08:26 PM

Thank you so very much Frame Dragger. You are much too kind.

zonde

May10-10, 03:49 AM

That isn't so. There is absolutely no evidence (cite it if you think I am wrong) whatsoever that the classical Product state is the limit as efficiency approaches 100%.
Interference of overlap-free entangled photons with a Mach-Zehnder-like interferometer (http://arxiv.org/abs/1005.0802)
From this paper:
"The count rate is about 80k/s in each arm, and the coincidence is about 20k pairs per second. As a result, we prepare the polarization entanglement as

|\Phi^{+}\rangle_{s}=1/\sqrt{2}\;(|H\rangle_{1}|H\rangle_{2}+|V\rangle_{1 }|V\rangle_{2}), (1)

where where |H\rangle(|V\rangle) denotes horizontal (vertical) polarization, the subscripts 1 and 2 specify spatial modes, and subscript s means state of source. The visibilities for the polarization correlations are about 98.1% for |H\rangle/|V\rangle basis and 92.6% for |+45^{\circ}\rangle/|-45^{\circ}\rangle basis, without the help of narrow bandwidth interference filters."

From first sentence we can calculate that detection efficiency is about 25% (20k / 80k per second).
Quasi-decoherence (deviation from perfect 100% case) is 1.9% for |H\rangle/|V\rangle measurement but 7.4% for |+45^{\circ}\rangle/|-45^{\circ}\rangle measurement.

Of course it is hard to tell what is the reason for that difference without explicitly testing what affects this quasi-decoherence. But let me say this that way "this observation is in agreement with hypothesis that classical product state is the limit as efficiency approaches 100%".
Where usual QM interpretation does not predict any difference between decoherence for those two measurements in ideal case. You can however hypothesize that there where imperfections in this setup like angle of incident beam with PDC crystal was not ideal and things like that.

DrChinese

May10-10, 08:55 AM

Interference of overlap-free entangled photons with a Mach-Zehnder-like interferometer (http://arxiv.org/abs/1005.0802)
From this paper:
"The count rate is about 80k/s in each arm, and the coincidence is about 20k pairs per second. As a result, we prepare the polarization entanglement as

|\Phi^{+}\rangle_{s}=1/\sqrt{2}\;(|H\rangle_{1}|H\rangle_{2}+|V\rangle_{1 }|V\rangle_{2}), (1)

where where |H\rangle(|V\rangle) denotes horizontal (vertical) polarization, the subscripts 1 and 2 specify spatial modes, and subscript s means state of source. The visibilities for the polarization correlations are about 98.1% for |H\rangle/|V\rangle basis and 92.6% for |+45^{\circ}\rangle/|-45^{\circ}\rangle basis, without the help of narrow bandwidth interference filters."

From first sentence we can calculate that detection efficiency is about 25% (20k / 80k per second).
Quasi-decoherence (deviation from perfect 100% case) is 1.9% for |H\rangle/|V\rangle measurement but 7.4% for |+45^{\circ}\rangle/|-45^{\circ}\rangle measurement.

Of course it is hard to tell what is the reason for that difference without explicitly testing what affects this quasi-decoherence. But let me say this that way "this observation is in agreement with hypothesis that classical product state is the limit as efficiency approaches 100%".
Where usual QM interpretation does not predict any difference between decoherence for those two measurements in ideal case. You can however hypothesize that there where imperfections in this setup like angle of incident beam with PDC crystal was not ideal and things like that.

Where in the paper does it say ANYTHING remotely similar to the idea that the Product State statistics are approached?

By way of example: at 0 degrees, the Product State is 25.0% and the stated observation was apparently 1.9%. Does not seem too close. At 45 degrees, the Product State value should be 50.0% and the actual was apparently 42.6%.

Don't you think the authors would be raising flags if the stats deviated from QM predictions by a significant amount?

By the way, the 25% detection stat is a bit deceiving. That is because the value is net. Net meaning for both detectors jointly. Obvioulsy, there are a lot of unmatched hits too. I would estimate the gross efficiency at close to 50% (since 50%^2 = 25%).

yoda jedi

May10-10, 12:11 PM

dependent on ontological features which are semantically defined. singling out an ontology, and making ad hoc demands.

assigning properties to ontology that is independent of us.

unusualname

May10-10, 02:55 PM

Interesting and entertaining (at times) discussion. :)

It's clear that Bell Test (violation) experiments are correct (to anyone sensible), and it's also clear that Special Relativity is correct, so to account for entanglement we need either "magic" or a FTL causal mechanism that doesn't contradict SR.

A causal mechanism that doesn't contradict SR would mean it couldn't interact with any classical matter in any classically known way, but that's not such a big deal or even unusual, since (for example) Evolution created our consciousness and that seems be non-classical (and the Blind Watchmaker is skillful but She's not a magician ;) )

It seems to me that this (controversial) piece of the puzzle could be eliminated or confirmed by devising tests to demonstrate a (hypothesised) finite limit on the speed of the entanglement correlations

(I'm hypothesising that entanglement is due to FTL signalling and is not an instantaneous event)

There are two obvious ways I can see how this might be observed.

1. Adapt/Refine the tests which close the communication loophole so that they report an upper bound on the possible speed that ftl "signalling" occurs

2. Increase the number of bits in experimental quantum computers until the finite bound becomes noticeable due to delays in calculations

1 may be practical if the upper bound on the "signalling" speed is reasonable (please god ;) ) , say c^k for some lowish value of k, 2 is probably impractical but each bit requires an exponential increase in the signalling path, so might become noticeable earlier than you might think.

Once confirmed, we could then work much more confidently on constructing a model of how such a signal might travel, and how it does not violate SR (it may be restricted to another dimension, where ftl isn't forbidden)

I really can't believe entanglement enables instantaneous correlations across unlimited space.

DrChinese

May10-10, 03:42 PM

It seems to me that this (controversial) piece of the puzzle could be eliminated or confirmed by devising tests to demonstrate a (hypothesised) finite limit on the speed of the entanglement correlations

(I'm hypothesising that entanglement is due to FTL signalling and is not an instantaneous event)

Believe it or not, there have been such tests. They show that if there is an FTL influence, it must be at least 10,000 times the speed of light.

Source: http://arxiv.org/abs/0808.3316

DevilsAvocado

May10-10, 04:24 PM

... It seems to me that this (controversial) piece of the puzzle could be eliminated or confirmed by devising tests to demonstrate a (hypothesised) finite limit on the speed of the entanglement correlations ...

Welcome to PF unusualname! (that is an unusual name!? :bugeye:) :smile:

Very interesting, sound and constructive thoughts, which at least I welcome to this thread, for a change!

I do think that some of this has already been tested in setting a minimum lower bound of 10,000 times the speed of light (for those hypersensitive of quotes, I temporary recommend closed eyes or a different activity, because now I’m about to do one of those very troublesome Wikipedia quotes):
Wikipedia – Experiment measures "speed" of the quantum non-local connection (http://en.wikipedia.org/wiki/Quantum_entanglement#Experiment_measures_.22speed. 22_of_the_quantum_non-local_connection)
A 2008 quantum physics experiment performed in Geneva, Switzerland has determined that the "speed" of the quantum non-local connection (what Einstein called spooky action at a distance) has a minimum lower bound of 10,000 times the speed of light.[13] However, modern quantum physics cannot expect to determine the maximum given that we do not know the sufficient causal condition of the system we are proposing.

And here’s a link to the arXiv paper Testing spooky action at a distance (http://arxiv.org/abs/0808.3316).

You were asking about the finite limit, and that seems yet to be a problem.

But, please elaborate your thoughts; it’s real refreshing with open-minded poster’s who like a fair and interesting discussion!

Edit: Ahhh! DrC beat me... sorry. (I’ll go and check your new FS gadget now)

DrChinese

May10-10, 04:46 PM

Edit: Ahhh! DrC beat me... sorry. (I’ll go and check your new FS gadget now)

I cheated, edited it... :smile:

DevilsAvocado

May10-10, 04:52 PM

I cheated, edited it... :smile:
Hehe! Is that "RBW posting"!? :smile:

DrChinese

May10-10, 05:07 PM

Hehe! Is that "RBW posting"!? :smile:

Definitely. :biggrin:

DevilsAvocado

May10-10, 05:26 PM

Definitely. :biggrin:
Haha!! We should revive "The Monty... Posting"...!? :uhh: (:biggrin:)

unusualname

May10-10, 06:00 PM

10,000c? That's nothing, if god's being reasonable we might be lucky to get c^2 :)

Thanks for the link, I hadn't been aware of any specific results (although any of the experiments post-Aspect would have a roughly calculable lower bound, I assume)

I initially had the idea that the signal would travel between the particles along some kind of higher dimensional space closely tied to the classical 3d space traced out by each particle, but that doesn't tie in well with single particle interference effects which you would hope would be due to a similar mechanism.

But I don't think it's a highly subtle sub-planckian mechanism or anything else so devious, mainly because evolution is pretty straightforward and works with the simple tools and materials provided by the environment at granularity no worse than atomic level, and I am pretty convinced consciousness is related to entanglement.

RUTA

May10-10, 07:00 PM

It seems to me that this (controversial) piece of the puzzle could be eliminated or confirmed by devising tests to demonstrate a (hypothesised) finite limit on the speed of the entanglement correlations

(I'm hypothesising that entanglement is due to FTL signalling and is not an instantaneous event)

I really can't believe entanglement enables instantaneous correlations across unlimited space.

If the events are space-like related, even 1 m/s faster than c, there is a frame in which those events are simultaneous.

unusualname

May10-10, 07:44 PM

If the events are space-like related, even 1 m/s faster than c, there is a frame in which those events are simultaneous.

If you assume that the signal doesn't travel in classical space then its journey is not related to a SR reference frame, but you're right that there is a privileged frame in which it would appear (to the observer) that the (entangled) events had zero time between them (but the observer wouldn't be able to observe the "signal" travelling between the particles in any classical manner)

For 3 or more particle entanglements (eg quantum computer) you wouldn't have such a privileged reference frame such that all entanglement events were simultaneous.

I need to read that preprint linked to above carefully to understand the importance of the privileged reference frame they mention (apparently it's crucial to bohm-hiley's pilot wave constructions)

I don't think it's a big "cheat" to suggest that the signal travels in non-classical space, not with the ridiculous plethora of calabi-yau manifolds and the like thrown up by string theory

unusualname

May11-10, 06:18 AM

The test of entanglement speed (they call it "speed of quantum information") from the preprint Testing spooky action at a distance (http://arxiv.org/abs/0808.3316) assumes a causal mechanism with a signal travelling in classical space, so I'm not sure if their measurement in the conclusion of a lower bound is even correct if we instead assume the signal travels in non-classical space (either other dimensions or something even weirder) (although there obviously is a lower bound, however it's the upper bound I'm interested in)

A simplistic model might be like this:

## ## ## ## ##
# # # # # # # # # #
# # # # # # # # # #
# ## ## ## ##

------> particle travelling at speed <= c in classical spacetime

#
# # signal travels around extra dimensional
# # ("kaluza-klein") coils at speed c^k

For "circular" coils we'd require the signal to travel at ~c^2 to keep up with the particle, but we can expect even faster speeds for efficient "communication" between the particles.

Now, it may be that these "spooky" signals can only travel "near" a path traced out by particles in classical space-time, and they should influence events restricted to those observed in entanglement (so the signals are responsible for the "magic" entanglement correlations we see, which can happen faster than the speed of light would allow with a classical signal)

In particular, there is no mechanism for transmitting FTL information through classical space (the entangled particles communicate with each other FTL but this only achieves entanglement correlations of their quantum properties, which we can't deterministically influence)

I can see how this may be difficult to check for in current Bell Test experiments since you need to fine-tune an experiment to measure what may be a very tiny delay between the entangled particles switching quantum states.

So perhaps the better way forward would be to detect delays in multi-particle entanglements such as sufficiently complex quantum computers (what are we up to so far ~100 bits yet?)

On a side note, I wonder why Bohm, Hiley et al didn't consider a signal travelling in non-classical space, perhaps physics models based on exotic topology weren't the vogue and they were scared of additional ridicule?

And on the speculative subject of entanglement & consciousness I might also note that our brains don't seem to allow us to think at infinite speed, there seems a (fairly cumbersome) delay involved, but of course that may be due to the requirement for complex chemical and biological mechanisms relating to memory and the like (In fact there is a well known 40hz effect observed in human brains, eg see this paper (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC45309/pdf/pnas01146-0475.pdf)). It's interesting that autistic savants and very young children seem able to process certain information quicker than normal adults, that may be due to their brains lacking certain biological mechanisms and hence they are not slowed down so much.

I would think the determination of an upper bound on entanglement speed would be at least as important as finding the Higgs Boson, so it's surprising that there doesn't seem much experimental effort in this direction.

zonde

May11-10, 07:07 AM

Where in the paper does it say ANYTHING remotely similar to the idea that the Product State statistics are approached?
You where talking about evidence not reference. You said: "That isn't so. There is absolutely no evidence (cite it if you think I am wrong) ..."
Besides this experiment wasn't about violation of BI so the calibration of entangled state was only part of preparations for main experiment.

By way of example: at 0 degrees, the Product State is 25.0% and the stated observation was apparently 1.9%. Does not seem too close. At 45 degrees, the Product State value should be 50.0% and the actual was apparently 42.6%.
visibility is defined as follows:
V=(max-min)/(max+min)
In case of visibility for minimum we can use this formula (but it's the same as above):
V=100%-2*min/(max+min)

Taking into account these formulas visibility for product state at +45deg/-45deg (minimum) would be 0 for 100% efficiency. Maximum in this case is coincidence rate at +45deg/+45deg.
Visibility for product state at H/V (minimum) would be 1 (maximum is coincidence rate at H/H).
So for product state with diminishing interference term as efficiency approaches 100% H/V visibility should stay the same but visibility for +45deg/-45deg should tend to 0 with increasing efficiency.

QM prediction used by Bell was that theoretical visibility for 100% efficiency is 1 for any angle α and β=α+Pi/2.

So according to QM visibility should be the same for +45deg/-45deg and H/V (of course not exactly 1 when considering effect of noise).
This is not so in this experiment by quite significant amount.

Don't you think the authors would be raising flags if the stats deviated from QM predictions by a significant amount?
No, I don't think so. Because QM says that "decoherence happens". Another thing is that it might be assumed that interference term can be diminished due to some imperfections of setup that you somehow can't track down. And you generally do not rise flags because of some unknown imperfection or noise or whatever (that as you would think you are too lame to track down). You try to eliminate it and if you can't you just ignore it (maximum include it in some statistical error estimates) hoping that it will not affect your experiment too much.

By the way, the 25% detection stat is a bit deceiving. That is because the value is net. Net meaning for both detectors jointly. Obviously, there are a lot of unmatched hits too. I would estimate the gross efficiency at close to 50% (since 50%^2 = 25%).
No, it is not. There is no reason to square efficiency if you have identical rate in both arms.
Let's say we have 25% efficiency in first arm - 80k/s rate, but 100% efficiency in second arm - 320k/s rate that we divide into two parts 80k/s and 240k/s.
Now we have probability that 1 of each 4 clicks from first arm will make coincidence with that 80k/s part from second arm and 3 of each 4 clicks will make coincidence with that 240k/s part. Together of course every click from first arm makes coincidence with click at second arm (as it has 100% efficiency).

RUTA

May11-10, 08:16 AM

For 3 or more particle entanglements (eg quantum computer) you wouldn't have such a privileged reference frame such that all entanglement events were simultaneous.

But, any two are simultaneous in SOME frame and their temporal order switches in other frames, so how do you argue for an unambiguous causal ordering without resorting to a preferred frame?
I need to read that preprint linked to above carefully to understand the importance of the privileged reference frame they mention (apparently it's crucial to bohm-hiley's pilot wave constructions)

I don't think it's a big "cheat" to suggest that the signal travels in non-classical space, not with the ridiculous plethora of calabi-yau manifolds and the like thrown up by string theory

My understanding of BM is the wave function is updated in configuration space, so configuration space is "real" for them. But, I don't see how the precise mechanism avoids FTL comm or a preferred frame for an unambiguous causal ordering. The events (measurement outcomes) occur in spacetime and their temporal order is relative if they're space-like related, regardless of what is going on "behind the scenes." Therefore, if you want to explain them via "causal relations" you either need a preferred frame or FTL comm. [There is another way out -- you can say the future has causal influence on the past, but that's another discussion.]

unusualname

May11-10, 08:57 AM

But, any two are simultaneous in SOME frame and their temporal order switches in other frames, so how do you argue for an unambiguous causal ordering without resorting to a preferred frame?

You argue that a classical observer can't observe the sequence of causal events being caused (by the non-classical FTL signal), they only observe the final states.

The fact that an observer might see simultaneous and backward events isn't really a problem, except that it might confuse the observer :) (and remember I'm arguing that the entanglement events can't transmit classical information FTL)

Incidentally, I stated above that we couldn't deterministically influence the quantum state, I think that's true unless, er, you actually are the particle! ie consciousness allows us to choose certain quantum states, which then propagate to macroscopic events.

So in my (very speculative) theory, if we had a brain the size of a galaxy we probably could communicate FTL information within it provided the "information" was restricted to thoughts.

Ignoring the wild speculations, for a significant breakthrough in quantum theory a reasonably simple result is required on an upper bound for "the speed of quantum information"

That would be paradigm changing :)

unusualname

May11-10, 10:22 AM

ah, hold your horses, this has been theoretically postulated:

fundamental quantum limit on the rate of operation of any information-processing system (http://nextbigfuture.com/2009/10/fundamental-quantum-limit-on-computing.html)

In a paper published in the journal Physical Review Letters, Levitin and Toffoli present an equation for the minimum sliver of time it takes for an elementary quantum operation to occur. This establishes the speed limit for all possible computers. Using their equation, Levitin and Toffoli calculated that, for every unit of energy, a perfect quantum computer spits out ten quadrillion more operations each second than today's fastest processors.

http://arxiv.org/abs/0905.3417

unusualname

May11-10, 11:04 AM

so given the above result (which is basically derived from the energy-time uncertainty relationship, there are other papers which discuss this, eg see Ultimate physical limits to computation (http://arxiv.org/abs/quant-ph/9908043)) we already have an upper bound for the speed of quantum computers, hence it would be difficult to distinguish the time taken for the entanglement effects to propagate as opposed to this limit on qubit switching time.

So we'd need to devise our experiment more carefully to distinguish the time taken for propagation of entanglement events.

If we can assume that a classical space distance is quantitatively related to the length of the non-classical path followed by FTL entanglement signals (so if we increase the usual classical space between our entangled pairs we can assume the non-classical path I'm hypothesising also increases) then we could demonstrate that the "speed of entanglement" is finite by carrying out identical experiments at different distances and recording an increase in the time for the entangled pairs to correlate.

Admittedly, this is looking trickier and trickier...

RUTA

May11-10, 11:26 AM

You argue that a classical observer can't observe the sequence of causal events being caused (by the non-classical FTL signal), they only observe the final states.

They can observe the sequence. The problem is other people will observe different sequences.

The fact that an observer might see simultaneous and backward events isn't really a problem, except that it might confuse the observer :) (and remember I'm arguing that the entanglement events can't transmit classical information FTL)

They will be confused if (1) the events are space-like separated, (2) they believe there is a causal connection b/w the events, (3) there is no preferrred frame, (4) the future doesn't causally influence the past. They will be confused b/c this a self-inconsistent set of assumptions.

unusualname

May11-10, 11:50 AM

They can observe the sequence. The problem is other people will observe different sequences.

No they can't, they can only observe the final quantum states, which had a causal sequence determined by the journey taken by the FTL non-classical signal that's responsible for the entanglement correlations. The observer will just see the final (classically observable) quantum states pop up in some arbitrary order determined by their classical reference frame.

It doesn't matter that other observers might claim the states appeared in a different order, no rule of Special Relativity is broken if no classical information was transmitted.

They will be confused if (1) the events are space-like separated, (2) they believe there is a causal connection b/w the events, (3) there is no preferrred frame, (4) the future doesn't causally influence the past. They will be confused b/c this a self-inconsistent set of assumptions.

Well QM is confusing :) They might believe all they like there is a causal connection between the events, but there's no classical causal connection between them, that's for sure.

I don't believe in fuzzy (or philosophically devious) interpretations of entanglement which assumes some magic instantaneous effect, I'd rather be more scientific and accept that our reality has some additional (but mathematically constructible) components which when taken into consideration give us a way to construct new physics models which append to the old and don't contradict long proven observations of theories like SR

DevilsAvocado

May11-10, 11:52 AM

... For 3 or more particle entanglements (eg quantum computer) you wouldn't have such a privileged reference frame such that all entanglement events were simultaneous.

Found one multiqubit (four-qubit) entangled experiment by Zeilinger et al. that cannot be described by local realism:
Experimental Violation of a Cluster State Bell Inequality (<--link) (http://homepage.univie.ac.at/philip.walther/paper/ClusterBelll_PRL05_95_020403.pdf)
Cluster states are a new type of multiqubit entangled states with entanglement properties exceptionally well suited for quantum computation. In the present work, we experimentally demonstrate that correlations in a four-qubit linear cluster state cannot be described by local realism. This exploration is based on a recently derived Bell-type inequality [V. Scarani et al., Phys. Rev. A 71, 042325 (2005)] which is tailored, by using a combination of three- and four-particle correlations, to be maximally violated by cluster states but not violated at all by GHZ states. We observe a cluster-state Bell parameter of 2.59 ± 0.08, which is more than 7 σ larger than the threshold of 2 imposed by local realism.

http://i39.tinypic.com/mljgnd.png

unusualname

May11-10, 05:28 PM

Found one multiqubit (four-qubit) entangled experiment by Zeilinger et al. that cannot be described by local realism:

Over the last few decades I think local realism has clearly been shown to be untenable, and not even desirable ( what an uninteresting world it would be : ) )

I'm puzzled why there has been resistance, since we all possess one thing that can't be modelled by local realist physics, our consciousness

I don't think my suggestions are even that adventurous, I mean, just asking for an extra dimension or two to bypass SR restrictions on FTL signalling is hardly less bizarre than the Copenhagen Interpretation, many-worlds or assuming instantaneous multiple correlations by magic.

You can ignore my speculations about consciousness and entanglement, but I think it's a good bet that the two are related, and I must again emphasise that a really simple process (evolution) created conscious beings.

DrChinese

May11-10, 05:44 PM

Over the last few decades I think local realism has clearly been shown to be untenable, and not even desirable ( what an uninteresting world it would be : ) )

I'm puzzled why there has been resistance, since we all possess one thing that can't be modelled by local realist physics, our consciousness.

So true! While some would like to return to local realism, it seems to me that the exciting things to ponder are in the other direction entirely. There could be some weird dimensions which exist in supersets of existing theory. Perhaps quantum non-locality is local in those dimensions. Or maybe there are strange beings there. (I mean: stranger than the strange beings here.)

:smile:

DevilsAvocado

May11-10, 05:54 PM

... (I mean: stranger than the strange beings here.)
:smile:

Please forgive me! But I can’t help it!! Moooooaaahhhhaaaa LOL!! :rofl:

DevilsAvocado

May11-10, 06:12 PM

... or assuming instantaneous multiple correlations by magic.

I guess this will qualify me for the "severe strangeness classification" :smile:, but I can’t get this out of my head. I assume you are proposing a finite limited upper "speed" of the quantum non-local connection, right?

What 'mechanism' would handle the 'negotiation' between entangled particles, since there is only one particle (or 'end' of the entangled WF) who can 'settle/decide' the correlated outcome?

I know there are interpretations like RBW or MWI that makes this an non-issue, but these interpretations brings other 'stuff' that are more complex than this 'entangled negotiation' – and I always been a big fan of Occam's razor.

Any thoughts?

DevilsAvocado

May11-10, 06:21 PM

my_wan

May11-10, 06:50 PM

So true! While some would like to return to local realism, it seems to me that the exciting things to ponder are in the other direction entirely. There could be some weird dimensions which exist in supersets of existing theory. Perhaps quantum non-locality is local in those dimensions. Or maybe there are strange beings there. (I mean: stranger than the strange beings here.)

:smile:

Here is a paper that shows a violation of Bell's inequalities in classical statistics, among other things.

Abstract: Quantum mechanics from classical statistics (http://arxiv.org/abs/0906.4919)
Quantum mechanics can emerge from classical statistics. A typical quantum system describes an isolated subsystem of a classical statistical ensemble with infinitely many classical states. The state of this subsystem can be characterized by only a few probabilistic observables. Their expectation values define a density matrix if they obey a "purity constraint". Then all the usual laws of quantum mechanics follow, including Heisenberg's uncertainty relation, entanglement and a violation of Bell's inequalities. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. Born's rule for quantum mechanical probabilities follows from the probability concept for a classical statistical ensemble. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem. As an illustration, we discuss a classical statistical implementation of a quantum computer.

Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

DevilsAvocado

May11-10, 07:29 PM

... local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

I agree, and to be real honest we must also consider that fact that local realism may be a stone dead parrot... with the Norwegian Blue plumage... :rolleyes:

Sorry, just a really bad joke. :smile: I agree in what you are saying – "It ain't over 'til the fat lady sings."

my_wan

May11-10, 09:08 PM

I agree, and to be real honest we must also consider that fact that local realism may be a stone dead parrot... with the Norwegian Blue plumage... :rolleyes:

Sorry, just a really bad joke. :smile: I agree in what you are saying – "It ain't over 'til the fat lady sings."

Actually I thought it was a pretty good Monty joke. http://www.physicsforums.com/images/smilies/smile.gif

Given the weakness of the opposing arguments here, it appeared to me that many would get a false impression of excessive certainty of a particular view. I felt that needed corrected, as the actual physics involved don't presently allow a significant degree of certainty. Ironic http://www.physicsforums.com/images/smilies/laughing.gif

Galap

May11-10, 09:38 PM

But... even if we cannot use entanglement to send usable information FTL, the particles must clearly be 'communicating' in some way to present the opposite random property, right? And Bell showed there are no local hidden variables involved... or did I miss something?

MWI is the only 'way out' of this is, as I understand...?

The particles do not need to communicate. One explanation is that they are two aspects of the same thing that aren't in the same place. We have pretty much determined that space and time aren't fundamentals. They are more emergent properties of the universe. Why is it so surprising then that not all phenomena work that way. Something can be in two places at once. In this case, it's the wavefunction. No communication, just evidence that GR isn't a complete theory.

unusualname

May12-10, 05:01 AM

The particles do not need to communicate. One explanation is that they are two aspects of the same thing that aren't in the same place. We have pretty much determined that space and time aren't fundamentals. They are more emergent properties of the universe. Why is it so surprising then that not all phenomena work that way. Something can be in two places at once. In this case, it's the wavefunction. No communication, just evidence that GR isn't a complete theory.

The problem with that argument is that it's a struggle to explain multiparticle entanglement in quantum computers (and perhaps the conscious brain), since all the particles would have to occupy the same "thing" (or have some component of their positions in multidimensional space fixed) undisturbed for long periods of time.

I think it's easier to imagine that signalling between the particles occurs in some non-classical space.

DrChinese posted a link to a recent experiment which established entanglement in photons from different sources ( http://arxiv.org/abs/1005.1426 ) , and several similar results have been published. These type of results make it difficult for me to see how entanglement can be due to particles being aspects of the same "thing" (or having the same component in multidimensional space)

But it's true that we can't rule it out, so we need to make some progress on this impasse in quantum understanding, and I suggest that testing for signalling is not beyond the bounds of current experiments.

It will be difficult if the signalling speed (the "speed of entanglement") is so fast as to be comparable with the minimum qubit switching time predicted by the energy-time uncertainty relation (see links above to limits on computing), since any experiment will have to distinguish the entanglement propagation speed from the quibit switching time.

In fact, if god's being a devil she might have made the signalling time smaller than we can measure classically, then we won't be able to distinguish the effect from an instantaneous one.

But for historical record, in case these forums are archived for future generations, I want to state I believe that signalling occurs in some not overly exotic non-classical space (so not some freaky fractal dimension topology or weird discrete construct).

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness. That's essentially why most paranormal stuff doesn't work, if it did it would have emerged in an obvious way from evolution, and we would have telepathic cats and levitating birds ;)

DevilsAvocado

May12-10, 05:19 AM

Actually I thought it was a pretty good Monty joke. http://www.physicsforums.com/images/smilies/smile.gif

(Thanks! but) "Look, matey," I do know there are 'customers' who "wish to register a complaint (http://www.physicsforums.com/showpost.php?p=2709968&postcount=253)" about this very silly joke! :biggrin:

Given the weakness of the opposing arguments here, it appeared to me that many would get a false impression of excessive certainty of a particular view.

If you suggest: Running down the whole 18th century for an "optical solution", or disqualifying Einstein, Bohr, Bell & Aspect as bummers "who doesn’t care" – I’m with you all the way bro! (severe irony) :rofl:

DevilsAvocado

May12-10, 05:38 AM

The problem with that argument is that it's a struggle to explain multiparticle entanglement in quantum computers (and perhaps the conscious brain), since all the particles would have to occupy the same "thing" (or have some component of their positions in multidimensional space fixed) undisturbed for long periods of time.

I think it's easier to imagine that signalling between the particles occurs in some non-classical space.

...

But for historical record, in case these forums are archived for future generations, I want to state I believe that signalling occurs in some not overly exotic non-classical space (so not some freaky fractal dimension topology or weird discrete construct).

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness. That's essentially why most paranormal stuff doesn't work, if it did it would have emerged in an obvious way from evolution, and we would have telepathic cats and levitating birds ;)

Many BIG THANKS for that!! It's one of the best post I’ve seen so far! Awesome!!

But you still have to explain to me – if only one of these entangled photons can decide spin up/down – WHO decides!?

DevilsAvocado

May12-10, 05:48 AM

I'm sure reality can't be completely bizarre, because if it was, evolution would have created beings to take advantage of the bizarreness.

Or put it this way:

Either our brains are incomplete and the reality of QM is fooling us all the time and every day, or QM (and/or GR) is incomplete?

But would incomplete brains discover a complete theory!?!? :wink:

DevilsAvocado

May12-10, 06:39 AM

... One explanation is that they are two aspects of the same thing that aren't in the same place.

As UN mentioned, you run into trouble with the complete madness that DrChinese has enforced into our heads – Photons from separated sources can be entangled - after they were detected! (http://www.physicsforums.com/showthread.php?t=376225) ?:bugeye:?

And in this case; there has to be four "aspects of the same thing", and this of course is going to get 'worse' in the future:
http://i39.tinypic.com/mljgnd.png (http://homepage.univie.ac.at/philip.walther/paper/ClusterBelll_PRL05_95_020403.pdf)

DrChinese

May12-10, 09:03 AM

...Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

Not sure I would agree with that assessment. Granted, that may not have been true in 1965, but we have had time to consider Bell since. I am somewhat familiar with this paper (I keep links on a lot of local realists for easy reference, and this was one). Not the first time violation of Bell-like inequalities have been alleged in classical situations. If you are interested in discussing this specific paper, I would be happy to. However, I don't sense that is the point you are making.

I think you are saying that the matter is not decided. And I think it quite is. Bell Inequalities are violated experimentally in agreement with the predictions of QM. EPR local realism is untenable. Now, keep in mind that in the intervening years since Bell, all kinds of entanglement phenomena has been discovered. With a green light from Bell, QM has made prediction after prediction which can be verified - none of which remotely smack of local realism and in fact get farther and farther away.

For example: in another thread, I presented evidence that particles outside each others' light cones can be entangled. It's gonna be a cold day before that one can be explained classically.

DevilsAvocado

May12-10, 09:27 AM

... I think you are saying that the matter is not decided. And I think it quite is.

DrC, would you say that "the fat lady has sung", even though we haven’t yet fully understood the complete 'mechanism' behind entanglement?

DevilsAvocado

May12-10, 09:32 AM

What the he*k!? Frame Dragger is permanently banned!?!?!?!?!?!? :confused: :confused: :confused:

IcedEcliptic

May12-10, 09:45 AM

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know. It seems to me, that there is no classical means for this to occur, that separate sources entangle, game over, yes?

I am left with: Reality is not what I think it is from my daily life, and action in time and space is not ordered the way I expect it to be. Spatial separation may be meaningless when it does not change causality?

DrChinese

May12-10, 10:21 AM

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know. It seems to me, that there is no classical means for this to occur, that separate sources entangle, game over, yes?

It is settled to the mainstream community. There are a few doubters. Of course, there are also doubters of a spherical Earth, General Relativity, the Big Bang, etc. If we found out everything we know is wrong, then this could be too.

my_wan

May12-10, 04:34 PM

Not sure I would agree with that assessment. Granted, that may not have been true in 1965, but we have had time to consider Bell since. I am somewhat familiar with this paper (I keep links on a lot of local realists for easy reference, and this was one). Not the first time violation of Bell-like inequalities have been alleged in classical situations. If you are interested in discussing this specific paper, I would be happy to. However, I don't sense that is the point you are making.
I appreciate the offer, but your right, that's wasn't my intention. I tend to lean on the realist side, as a personal preference, and I'd do well just to hear out the objections. I have a lot of issues with the classical models suggested so far, but for reasons unrelated to EPR. Of the attempts at these models 't Hooft seem to be the most torturous. They're generally like trying to force fit a car motor on a moped, and explaining away the extra parts. Yet I still haven't found a fundamental reason why EPR must be defined in terms of a physical switch activated by a FTL mechanism. In fact it seems that not only does this FTL interpretation require assuming a realistic mechanism, contrary to the standard interpretation, but also assumes a particular type of physical character of this mechanism. Vector spaces and statistical ensembles both by their very nature allows an arbitrary number of parameters to be summed up in just a few variables. Ensembles only provide correlation, not causation, classical or otherwise.

I think you are saying that the matter is not decided. And I think it quite is. Bell Inequalities are violated experimentally in agreement with the predictions of QM. EPR local realism is untenable. Now, keep in mind that in the intervening years since Bell, all kinds of entanglement phenomena has been discovered. With a green light from Bell, QM has made prediction after prediction which can be verified - none of which remotely smack of local realism and in fact get farther and farther away.
Nobody can seriously question QM or the limits provided under Bell's Theorem. I'm aware of all sorts experiments from EPR where both detectors did the measurement first in their own frame, delayed choice, frame dependent correlations, Afshar, single photon pictures, pictures taken using photons that never seen the object being photographed, metamaterials, etc. I might have missed something, but I hope not. I'm presently considering a sort of delayed choice/Afshar hybrid. Still I have yet to see an empirically backed argument to rule out all class of models as generally defined by Relational QM.

For example: in another thread, I presented evidence that particles outside each others' light cones can be entangled. It's gonna be a cold day before that one can be explained classically.
Yet therein lies the weakness of your case. Essentially 'entangled' means correlated. Thus your case holds under the assumption that correlation equals causation. Even wise tales warn of that one. The assumption that these properties are absolute real properties may turn out to be akin to assuming velocity is an absolute. Nobody is surprised that the relative velocity of distant objects instantly change with a local boost. The fact that entanglement can be manipulated, is frame dependent, actually lends some support to a purely relational interpretation.
Entangled Light in Moving Frames (http://arxiv.org/abs/quant-ph/0302095)
Quantum Entanglement of Moving Bodies (http://arxiv.org/abs/quant-ph/0205179)

So the objections I would like to hear is how to empirically rule out such models. I'm not asking any given interpretation to be proved one way or the other, merely that EPR correlations rule out this relational model class the same way it rules out a local real signal switching actual mechanisms. This would be trivial if an actual FTL message could be sent, otherwise it hinges on a correlation equals causation claim.

IcedEcliptic

May12-10, 05:04 PM

It is settled to the mainstream community. There are a few doubters. Of course, there are also doubters of a spherical Earth, General Relativity, the Big Bang, etc. If we found out everything we know is wrong, then this could be too.

Are you telling me that the earth is not flat? Hogwash sir! ;)

jtbell

May12-10, 05:11 PM

Are you telling me that the earth is not flat?

And it's not supported by turtles all the way down? :bugeye:

DevilsAvocado

May12-10, 05:32 PM

And it's not supported by turtles all the way down? :bugeye:

No worries mate! I’ve got it all covered! :approve:

http://i47.tinypic.com/1621vut.jpg

DevilsAvocado

May12-10, 05:42 PM

... Essentially 'entangled' means correlated.

This is an interesting point (that can be repeated). Erwin Schrödinger’s term Verschränkung is translated to entanglement, and this is (according to Anton Zeilinger) not as describing as the German term.
Verschränkung translated to English:
interleave
interconnection
folding
crossing
clasping
Anton Zeilinger visualizes verschränkung like this:

http://i44.tinypic.com/2cpb4ia.png

(Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... :smile:)

IcedEcliptic

May12-10, 07:32 PM

And it's not supported by turtles all the way down? :bugeye:

I believe in the great turtle pile as the only sane anchor in a mad universe. ;) heh

jtbell

May13-10, 01:05 AM

(Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... :smile:)

I wonder what it is in Finnish. :uhh: (Being of Finnish-American background, I have a more than passing interest in the language, but I haven't tried to study physics in it.)

zonde

May13-10, 06:02 AM

Opinions put aside, do the Bell Tests and ones that Dr. Chinese is speaking of mean that this is a settled issue? I am not in this community, so I do not know.
What do you mean by "settled issue"? Settled using scientific method or settled by general consensus?
Anyways there is quite a big hole in reasoning about discarding local realism. Bell theorem rests on QM prediction that prefect correlations for any same (or orthogonal too in case of photons) angles do not depend form detection efficiency.
This is testable prediction however it has never been tested.

You can read what is in wikipedia about scientific method (http://en.wikipedia.org/wiki/Scientific_method):
"1. Use your experience: Consider the problem and try to make sense of it. Look for previous explanations. If this is a new problem to you, then move to step 2.
2. Form a conjecture: When nothing else is yet known, try to state an explanation, to someone else, or to your notebook.
3. Deduce a prediction from that explanation: If you assume 2 is true, what consequences follow?
4. Test: Look for the opposite of each consequence in order to disprove 2. It is a logical error to seek 3 directly as proof of 2. This error is called affirming the consequent."

DevilsAvocado

May13-10, 06:37 AM

I wonder what it is in Finnish. :uhh:

...I’m not sure, but could it be Nokia...?? :rolleyes:

Noo sorry, entanglement = Lomittuminen, and the word for QM is really cool Kvanttimekaniikka. Just taste that word (imagine sitting in a real hot sauna), it’s definitely hotter than QM!

(P.S. There’s a "friendly war" between Finnish Nokia and Japanese/Swedish Sony Ericsson, but in the end we are all brothers and sisters, even in ice hockey! :wink:)

my_wan

May13-10, 06:43 AM

[...](Entanglement in Swedish is something like 'spaghetti'... maybe that’s why I sometimes have a hard time digest... :smile:)

Reasonable synonyms in English, but I believe that's what Francis Bacon would refer to as an "idola fori" (idol of the marketplace). To say that a variable is entangled does not endow that variable with the realism of spaghetti. Now if these variables unambiguously possessed these presumed ontic qualities, then where's the FTL communicator? Without that your still stuck with interpretive ambiguity, though something clever in the vein of Bell's Theorem might pull it off.

The Monty Python humor is cool, but until EPR can directly address this relational class, rather than violating the relational objections to formulate arguments against it, it remains just humor. The only honest answer to the OP then remains: It's potentially possible, simply because nobody has any hard answers. I'm still waiting on a cleaner empirical rebuttal to the relational model class.

zonde

May13-10, 07:05 AM

Thought that I might add something to my last post.
In wikipidedia "affirming the consequent" is described as negative thing without looking at positive sides of this approach. Really there are other occupations of people that take advantage of that approach - it's engineering.

So if we do not call modern QM a science but engineering then everything falls in places and all things are fine the way they are. :approve:

DevilsAvocado

May13-10, 07:28 AM

... do not call modern QM a science but engineering ...
Healthy reflection zonde. This approach has the big advantage of eliminating any 'religious elements'. If you put your head in the sand at a construction site, then you risk being buried in cement. (o:))

I’ agree 99.9%, with reservation for the fact the whole universe is inside this "construction site", and this must have some influence on the matter... :uhh:

DevilsAvocado

May13-10, 08:35 AM

... Now if these variables unambiguously possessed these presumed ontic qualities, then where's the FTL communicator? Without that your still stuck with interpretive ambiguity, though something clever in the vein of Bell's Theorem might pull it off.
I agree.

I have tried many times, and this is last try (before maybe starting a new thread). I see two paradoxes in EPR/Bell test experiments:
1) The official "Spukhafte Fernwirkung".

2) The 'madness' of SYNCHRONIZED ENTANGLED OUTCOMES.

If we compare with the double-slit experiment, we don’t have this problem. The wavefunction (of the wave–particle duality) is propagating perpendicular towards the double-slit and passes simultaneously. No problem, no paradox.

Whereas in Bell test experiments we have a wavefunction of two particles (or more!), that are separated outside each other’s light-cones, and have this far been tested at 18 km separation.

Now, to have one influence the other we need "Spukhafte Fernwirkung". But this is not enough, some function/property/mechanism must also resolve which one of the particles is going to DECIDE the correlated outcome.

It won’t work if they are exactly synchronized, because this will create a conflict with QM, HUP and probability.

It will only work if they are unsynchronized, but then we run into problem with GR who says that in some frame of reference they will be exactly synchronized, and in another frame of reference Alice will set the outcome, and in another frame of reference Bob will set the outcome!?

>> This doesn’t work with current understandings of QM and GR!? <<
(... as far as I can tell ...)

IcedEcliptic

May13-10, 08:57 AM

Scandinavian languages make my brain hurt. Lovely to hear, but painful to read and pronounce.

DevilsAvocado

May13-10, 09:08 AM

Scandinavian languages make my brain hurt.

Yeah, I hear you.

This guy has completely destroyed our reputation! :grumpy:

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/mbs64GvGgPU&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

:rofl:

unusualname

May13-10, 09:22 AM

Here is a paper that shows a violation of Bell's inequalities in classical statistics, among other things.

Abstract: Quantum mechanics from classical statistics (http://arxiv.org/abs/0906.4919)

Section VIII covers Bell's inequalities. I can't honestly disparage considerations that local realism may in fact be a dead horse. What I can disparage is the claim that it is certainly so. It's not entirely honest on either side of the fence.

But he doesn't claim this supports local (deterministic) realism, instead he proposes that reality is based on "probabilistic realism":

“Probabilistic realism” starts from the premise that the most general fundamental description of reality is of statistical nature [13]. “Elements of reality”, which allow for deﬁnite predictions, correspond then to values of observables as well as to correlations. Let us consider the EPR case of two entangled spins, carried by spatially separated particles which originate from the decay of a spinless particle and therefore have total spin zero. In this case the element of reality is the maximal anticorrelation for all spin directions, rather than values of individual spins. This element of reality is revealed by measurements of both spins and has existed already before the ﬁrst measurement. In contrast, the value of one of the spins is maximally undetermined before the ﬁrst measurement and not an element of reality.
Due to the correlation, the two spins have to be considered as one system. Even for an arbitrarily large separation, such that signals cannot be exchanged any longer, we cannot divide the system into two independent subsystems, consisting of one of the spins each. The correlation between the two spins is then nonlocal.

which is hardly what most of you local realists mean by local realism :)

I think I prefer nonlocal deterministic realism to this suggestion anyway, and I'm sure the most profitable way forward is to determine possible non-local models of reality, in that regard papers like this one An experimental test of non-local realism (http://arxiv.org/pdf/0704.2529) are interesting (rules out a class of non-local models)

ThomasT

May13-10, 02:09 PM

It's clear that Bell Test (violation) experiments are correct (to anyone sensible), and it's also clear that Special Relativity is correct, so to account for entanglement we need either "magic" or a FTL causal mechanism that doesn't contradict SR.There's almost universal agreement that the tests are correct. But neither magic nor ftl transmissions (nor aliens, etc.) are necessary to understand why the correlations exceed the limits on explicit lhv accounts of them.

To understand why BIs are violated it's necessary to compare the formal requirements, as set forth by Bell, with the experimental setups to which they're being applied (formal requirements that any explicit local hidden variable model of the joint, entangled, situation must meet). It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation. Rather it's relationships between these variables that's being measured in the joint context. These relationships are joint hidden parameters that are being measured by a joint instrumental variable. This is what the 'quantum nonseparability' of the situation physically refers to. QM gives a correct account of the joint, entanglement, situation by not separating its components.

The above point is the key to understanding what Bell's theorem means and why it's impossible to have a local hidden variable model of entanglement. It's not that Bell was wrong or that he unwittingly made a faulty lhv model. Making a lhv model of entanglement is kind of a catch-22. The only way to represent the joint situation with local hidden variables happens to be incompatible with the demands of the situation that it's trying to model. An lhv account of the joint, entangled, situation must necessarily be an incorrect account of that situation. This has been proven by Bell and others (see David Mermin's, "Hidden variables and the two theorems of John Bell", Rev. Mod. Phys., Vol. 65, No. 3, July 1993). So, BIs (and other 'no lhv' theorems) based on the requirements necessary to construct any explicit lhv model of the joint, entangled state, experimental situation must, necessarily, be violated -- and this has nothing to do with nonlocal or ftl communication between the separated entangled quanta or the separated filtering and detection devices. The joint experimental situation is just, in Bell's words, "incompatible with separable predetermination". This doesn't mean that there aren't separate particles that have predetermined unknown individual properties. It just means that the joint experimental situation can't be modelled in those terms. (What sometimes sets people on the wrong path is Bell's statement in the conclusion of his 1964 paper, "On the Einstein Podolsky Rosen Paradox": "In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements, without changing the statistical predictions, there must be a mechanism whereby the settings of one measuring device can influence the reading of another instrument, however remote." Which is correct of course. However, since there's no particular reason to believe that our universe might work that way independent of 'no lhv' theorems, and since BI violations can be explained without such a mechanism, then there's no particular reason to invent such a mechanism.)

Once that's understood, then it remains to understand how the correlations can be produced in a universe in which the principles of SR and local action hold. It should be clear enough that if there's some predetermined underlying relationship between, say, the spins of two photons, and that if these photons are jointly analyzed by crossed polarizers, then the correlations which result are pretty much what would be expected in a locally causal c-limited universe. Local predetermination of individual properties is incompatible with qm, because, for the reasons mentioned above, accounts of joint, entangled state, experimental situations in those terms are, necessarily, incompatible with those experimental situations.

This is not to say that the underlying mechanisms which result in entanglement correlations are completely, or even well, understood. They aren't by any means. And understanding that a local common cause for the underlying entanglement isn't ruled out by 'no lhv' theorems is just a beginning to any approach that's in line with relativistic restrictions. So, it's suggested that, before wierd and absurdly strange scenarios are offered to account for the BI violations and entanglement stats, maybe the focus should stay on the subtleties of the still fascinating, even without any artificially added wierdness, facts of the science and analysis and interpretation that promise to facilitate a better understanding.

So, for the record, I agree with those (eg., David Mermin, see his "What Do These Correlations Know about Reality? Nonlocality and the Absurd) who think that positing the existence of, eg., nonlocality is not in keeping with the best practice of scientific inquiry.

my_wan

May13-10, 03:31 PM

Now, to have one influence the other we need "Spukhafte Fernwirkung". But this is not enough, some function/property/mechanism must also resolve which one of the particles is going to DECIDE the correlated outcome.
This is at the core of the problem. Yet the justification that one must have actually influenced the other, at the time of measurement, is predicated on the unreality during transit and reality at the time of measurement. If these correlations were actually present during transit, then no such 'communication' is needed. The only way to deny this possibility is to deny the reality posited by such models during transit, then requiring what has been denied at the time the measurement takes place. No mechanism is required to "DECIDE" the correlation if it already exist.

You then made a more specific claim, that without a valid response moots my argument above.

It won’t work if they are exactly synchronized, because this will create a conflict with QM, HUP and probability.
Here you specified "exactly synchronized". But "exactly" has implications that may not be valid. I'll use a well known paper by Hall and Reginatto to illustrate.
Schrodinger equation from an exact uncertainty principle (http://arxiv.org/abs/quant-ph/0102069)
An exact uncertainty principle, formulated as the assumption that a classical ensemble is subject to random momentum fluctuations of a strength which is determined by and scales inversely with uncertainty in position, leads from the classical equations of motion to the Schrodinger equation. Thus there is an exact formulation of the uncertainty principle which precisely captures the essence of what is "quantum" about quantum mechanics.
Thus, by analyzing HUP as something somewhat analogous to Brownian motion, a version of HUP was derived from which the Schrodinger equation could then be directly derived. You should also note that this assumed a "classical ensemble", not an absolute valued variable in and of itself. Thus the implication by "exactly synchronized" does not entail that the measured variable is itself an absolute valued variable. Yet we all know that a large ensemble of random variables can be characterized by non-random values, and non-local effects are not needed to arrive at this value. Nor are we required to assume these variables don't exist without measurement, even though they lack real meaning wrt individual elements of a defining ensemble, classical or otherwise. "Exactly", "HUP", "QM", and "probability" has not only been maintained, but defined by and extended to include the Schrodinger equation in exact uncertainty case.

This addresses the "exactly synchronized" issue, but a more general issue implied in your rebuttal needs mentioned. Though I doubt you intended to imply this. In general when speaking of what is in "conflict" with a theory we are limited to empirical "conflict", irrespective of how incongruent the principles used to arrive at the empirical content appears to be. It's my opinion that ontologies have a symmetry similar to coordinate dependence, which we know is untenable in the general case. There can also be a form of covariance between incongruent but empirically equivalent ontologies. Many debates result from these sometimes equivalent but incongruent ontologies, and we call it arguing semantics.

DrChinese

May13-10, 04:48 PM

...It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation. Rather it's relationships between these variables that's being measured in the joint context. These relationships are joint hidden parameters that are being measured by a joint instrumental variable...

Again, no. In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context). This is by definition, but also comes from the EPR definition of an element of reality: if the outcome can be predicted with certainty, then there is an element of reality. And in a local world, what happens here does not affect what happens there.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.

my_wan

May13-10, 05:03 PM

But he doesn't claim this supports local (deterministic) realism, instead he proposes that reality is based on "probabilistic realism":
“Probabilistic realism” starts from the premise that the most general fundamental description of reality is of statistical nature [13]. “Elements of reality”, which allow for deﬁnite predictions, correspond then to values of observables as well as to correlations. Let us consider the EPR case of two entangled spins, carried by spatially separated particles which originate from the decay of a spinless particle and therefore have total spin zero. In this case the element of reality is the maximal anticorrelation for all spin directions, rather than values of individual spins. This element of reality is revealed by measurements of both spins and has existed already before the ﬁrst measurement. In contrast, the value of one of the spins is maximally undetermined before the ﬁrst measurement and not an element of reality.
Due to the correlation, the two spins have to be considered as one system. Even for an arbitrarily large separation, such that signals cannot be exchanged any longer, we cannot divide the system into two independent subsystems, consisting of one of the spins each. The correlation between the two spins is then nonlocal.(Bolding and underlining added to make my point.)

Here it says: "This element of reality is revealed by measurements of both spins and has existed already before the ﬁrst measurement." Thus no signaling mechanism is required to establish a correlation when the measurement takes place. It goes on to say: "In contrast, the value of one of the spins is maximally undetermined before the ﬁrst measurement and not an element of reality." But what does "maximally undetermined" mean here wrt one spin, that doesn't exist with both spins? It is our knowledge that is "maximally undetermined", not the spin state itself. Consider the following analogy.

You have a red and a blue marble. You have a machine package them in separate boxes without any knowledge of what color is in each box, and ship one around the world. Now, in the case of both marbles, like both spins, the color of both marbles is fully determined before the ﬁrst measurement, as specified in the quote. Also, the color of the marble in any one box is "maximally undetermined", because you don't know which marble is in which box, as specified in the quote. Yet the colors are correlated, because knowledge of one provides full knowledge of the other. You can only assume a FTL mechanism if you deny that the marbles had a color before opening one of the boxes.

Now we also know that these QM correlations cannot correspond to singular properties of a singular object, like in the marble sense. Bell's ingenuity made that crystal clear. If the logic holds in the QM sense, then the properties must be defined by ensembles, group behavior/relations which defines the properties. We know, classical or not, that a large number of random variables can be summed as a single well defined variable. Only when we put these variable into two groups, we can't define what each group separately will sum to, without first measuring at least one group. We also know that disparate emergent properties of ensembles can be formalized as if a single entity, if we drop (or don't know) the identifiers which define them.

which is hardly what most of you local realists mean by local realism :)I run into realists 'priest' all the time, and these are a bigger pain than they are worth. However, given the misrepresentation apparently provided in your rebuttal, I think it would be a bit difficult to define what one particular realist means. I'm not even sure "most" is definable.

I think I prefer nonlocal deterministic realism to this suggestion anyway, and I'm sure the most profitable way forward is to determine possible non-local models of reality, in that regard papers like this one An experimental test of non-local realism (http://arxiv.org/pdf/0704.2529) are interesting (rules out a class of non-local models)
I take the opposite tack, but given what we know at this point it would be unreasonable for me to insist my approach will be the most profitable. I'm not so certain as you have stated yourself to be here. I am a bit more certain that certainty in your own view can be a liability to a fruitful search, even if your lucky enough to be essentially right. My own modeling efforts actually include FTL variables of sorts, they just happen to be unusable for EPR and similar effects.

my_wan

May13-10, 05:31 PM

Again, no. In a local hidden variable model, each observer is measuring a separate reality.Funny, I've never seen it that way. There's MWI which is a class of its own, but certainly not universal to lhv models. There's another way I could interpret this, but it would be essentially equivalent to stating that two observers that measure the velocity of the same object differently must be measuring a "separate reality". Of course general covariance is a difficult issue in QM.

So there is no JOINT observable (or context). This is by definition, but also comes from the EPR definition of an element of reality: if the outcome can be predicted with certainty, then there is an element of reality. And in a local world, what happens here does not affect what happens there.Yet I still haven't even seen an acknowledgment of definitions not contained in the EPR definition, nor what those definitions entail. If you restrict the discussion solely to realism as defined by EPR, then logical validity goes without saying. Yet there are entire well defined classes of models which EPR definitions don't apply. You can legitimately ignore them as a personal preference, but stating what certainly is or isn't so, on the basis of a priori rejections of logical classes, doesn't follow.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.I give a marble analogy of a joint detection parameter to unusualname. Then pointed out how EPR puts constraints on this logic through ensembles rather than singular objects with singular properties. I'd still like to hear a rebuttal that does a prior reject the reasoning in order to reject the reasoning.

unusualname

May13-10, 05:44 PM

So, for the record, I agree with those (eg., David Mermin, see his "What Do These Correlations Know about Reality? Nonlocality and the Absurd) who think that positing the existence of, eg., nonlocality is not in keeping with the best practice of scientific inquiry.

yes, but it's much more fun to speculate on non-locality :)

When De Broglie suggested wave-particle duality in 1923, it was a pretty crazy looking suggestion at the time which bypassed a lot of tortuous alternative philosophical and analytical proposals, but turned out to be a spectacularly successful scientific model.

It's quite possible that Entanglement "paradoxes" will turn out to be due to us being restricted to observing a projection of reality, so we don't really see the real picture, like in the holographic principle (http://en.wikipedia.org/wiki/Holographic_principle) which, amongst other things, proposes that all information in a volume is obtainable from the surface area surrounding it.

So the non-locality may be illusory due to us being restricted to observing a subset of reality (although it appears to be non-local behaviour in that subset)

IcedEcliptic

May13-10, 07:04 PM

Ah yes, the science of personal preference. :rolleyes:

my_wan

May13-10, 08:06 PM

Ah yes, the science of personal preference. :rolleyes:
It plays a legitimate role in science when dealing with open questions, unless you think a psychic would do better directing research. It makes no sense for everybody to explore exactly the same set of assumptions, and such preferences distribute these searches more realistically. The danger is when we wrongly insist opposing assumptions are invalid, and artificially restrict research to our personal preferences. Certainly there are closed questions, but we must be careful not to over generalize and close questions that the physics involved didn't specifically close.

DevilsAvocado

May13-10, 08:24 PM

This is at the core of the problem.

I’m sincerely thankful for this comment. I was about to give up, convincing myself I was "lost in translation". Thank you so very much for this.

No mechanism is required to "DECIDE" the correlation if it already exist.

This makes me a little 'nervous' again... do you mean that LHV is still a reasonable possibility??

Here you specified "exactly synchronized". But "exactly" has implications that may not be valid.

Bad formulation of me, I’m sorry. What I wanted to pin down is the problem of Relativity of Simultaneity (RoS), and the fact that entanglement seems to be in need of a global NOW, to work properly.

One weird way to get rid of this problem is to accept Relational Blockworld (RBW) – No movement of particles in spacetime whatsoever.

Another is Many Worlds Interpretation (MWI) – EPR is no paradox and works just fine, in branched and separated universes.

And we can rule out a universal global NOW – since, for example, the GPS satellites needs adjustments for relativistic time dilation effects, essential for the functioning of the system.

So if we skip "interpretations under development" and look at what we 'have today', I say we have some 'trouble' in getting entanglement working.

My hope is that the QM world isn’t that 'crazy' that it’s impossible to 'talk about', and make some sense, in plain language. I could of course be totally wrong; QM world is 'crazy' and/or impossible to talk about. But I sure hope not. (Note: I’m not talking about superposition etc, simultaneously spin up/down – that’s not crazy, just weird.)

In an attempt to get over 'ontology & semantics', I’ll take a real dramatic example:
1) Alice & Bob are going to play "Russian Entangled Roulette".

2) Two revolvers with all rounds are connected to the measuring apparatus, and adapted to Alice & Bob’s heads.

3) If spin up (+) is measured, the revolver will not fire. If spin down (-) is measured, the revolver will fire.

4) Alice & Bob are separate by 1 ly, with the source halfway.

PROBLEM:
In one observer's reference frame we could see Alice’s photon hitting the polarizer first, and measure (+), thus killing Bob by deciding he is going to measure (-).

In another observer's reference frame we could see Bob’s photon hitting the polarizer first, and measure (-), thus saving Alice by deciding she is going to measure (+).

Would you be Alice lawyer in court?

Or what I’m really getting at – how do Alice & Bob’s photons know which reference frame they are in? Either the wavefunction/entanglement is broken/measured – or it is not. You can’t be in a state 'in-between' or 'both', can you? The wavefunction can’t collapse 'twice', can it?

IcedEcliptic

May13-10, 09:19 PM

It plays a legitimate role in science when dealing with open questions, unless you think a psychic would do better directing research. It makes no sense for everybody to explore exactly the same set of assumptions, and such preferences distribute these searches more realistically. The danger is when we wrongly insist opposing assumptions are invalid, and artificially restrict research to our personal preferences. Certainly there are closed questions, but we must be careful not to over generalize and close questions that the physics involved didn't specifically close.

Pretty way of saying that what you and zonde and thomast are on about is not really physics.

my_wan

May14-10, 01:35 AM

This makes me a little 'nervous' again... do you mean that LHV is still a reasonable possibility??In principle yes, but EPR correlations do place very definite restrictions on any such models. I thought I covered those conditions in my responses and papers I referenced for details. I give a marble analogy but Bell's theorem does in fact rule out such singular objects with singular properties. EPR requires some further constraints as follows:
1) The LHV's can't be singular objects, but rather local ensembles, roughly analogous to what any classical waveform is.
2) The properties, presumed non-local, can't be an absolute observer independent character of the ensemble. Rather a property relative to an observer, the experimental apparatus in this case. This is why I said the fact that EPR correlations are frame dependent lends support to this view, and linked papers to demonstrate.
With these two conditions, Bell's theorem is silent. It neither proves it right or wrong, unlike the marbles.

Bad formulation of me, I’m sorry. What I wanted to pin down is the problem of Relativity of Simultaneity (RoS), and the fact that entanglement seems to be in need of a global NOW, to work properly.Yes indeed, IIF a signaling mechanism is required. However, if you accelerate, there's no reason to be surprised that all distant objects change apparent velocity instantly, exactly according to your definition of simultaneity. Yet no signaling is involved. If 1) and 2) above apply, then this is all that's involved with EPR correlations. In fact, the difficulties RoS imposes seems to lend more support to this view.

One weird way to get rid of this problem is to accept Relational Blockworld (RBW) – No movement of particles in spacetime whatsoever.Yes, I've only been aware of RBW a few days, and it's very interesting. However, fundamentally RBW appears to take advantage of the relational view I've been discussing, in an upside down sort of way. The Blockworld does require the entire context to be accounted for.

Another is Many Worlds Interpretation (MWI) – EPR is no paradox and works just fine, in branched and separated universes.Yes, except it lacks empirical justification, beyond the need for sweeping a range of issues under the rug. Maybe that can change, but so far all I see is a lot of stacking of dependent variables.

And we can rule out a universal global NOW – since, for example, the GPS satellites needs adjustments for relativistic time dilation effects, essential for the functioning of the system.

So if we skip "interpretations under development" and look at what we 'have today', I say we have some 'trouble' in getting entanglement working.Yes, very endemic trouble. This is why I look at the issues from a class level, rather than specific models. Hopefully this will be useful in providing some viable clues where to go from here.

My hope is that the QM world isn’t that 'crazy' that it’s impossible to 'talk about', and make some sense, in plain language. I could of course be totally wrong; QM world is 'crazy' and/or impossible to talk about. But I sure hope not. (Note: I’m not talking about superposition etc, simultaneously spin up/down – that’s not crazy, just weird.) Yep, I'm in this boat, but realistically we can't demand it a priori. So I begin with the strongest causality, and give up what the physics says I must, like the marble analogy under EPR is fully untenable. The there are a whole range of notions, common here, which give up even more but are quiet reasonable assumptions, with a fair likelihood of paying off.

In an attempt to get over 'ontology & semantics', I’ll take a real dramatic example:
1) Alice & Bob are going to play "Russian Entangled Roulette".

2) Two revolvers with all rounds are connected to the measuring apparatus, and adapted to Alice & Bob’s heads.

3) If spin up (+) is measured, the revolver will not fire. If spin down (-) is measured, the revolver will fire.

4) Alice & Bob are separate by 1 ly, with the source halfway.

PROBLEM:
In one observer's reference frame we could see Alice’s photon hitting the polarizer first, and measure (+), thus killing Bob by deciding he is going to measure (-).

In another observer's reference frame we could see Bob’s photon hitting the polarizer first, and measure (-), thus saving Alice by deciding she is going to measure (+).

Would you be Alice lawyer in court?

Or what I’m really getting at – how do Alice & Bob’s photons know which reference frame they are in? Either the wavefunction/entanglement is broken/measured – or it is not. You can’t be in a state 'in-between' or 'both', can you? The wavefunction can’t collapse 'twice', can it?
If the relational interpretation holds, then it makes no difference what reference frame they are in. The measurements don't make the choice, they merely finalize them. Fundamentally, in this case, it would be no different from all bullets in one gun without knowing which, and both triggers are pulled. The superposition of both guns tells us exactly how many bullets there is. Without looking we could know nothing about the bullets in any one gun. This is untenable given Bell's theorem, unless the guns are ensembles that can overlap, and you positioned properly relative to the gun. Only the formalism does not make a distinction between an actual overlap of ensembles and an apparent overlap due to our lack of location knowledge. We merely superimpose all possible locations as if all possibilities was the reality, justified on the fact that the waveforms can and do overlap, and required for valid statistical answers.

Years ago, in Jr High, I read "In Search of Schrodinger's Cat". By the time it finally got around to saying what was supposed to be so weird, I thought I had guessed the answer. I figured it was a cross frame effect in relativity. Several years later, when I finally learned how untenable this was, it unambiguously brought home the meaning of general covariance. I even embarrassed myself on this forum once, falsely thinking somebody else made this mistake. You can reverse the apparent order of events visually, but once you account for the intervals involved no change in event ordering occurs. You can compress and stretch them, or even time for an individual, but event ordering remains the same. If this was possible you could use a pair of moving known frames to measure the distance to various stars, but it's not. Yet if a faster than light mechanism actually existed you could. EPR doesn't 'effectively' work to allow changing real event ordering either, which lends to the relational interpretation. Yes, I would be the lawyer.

my_wan

May14-10, 01:39 AM

Pretty way of saying that what you and zonde and thomast are on about is not really physics.
Haven't payed much attention to what zonde and ThomasT have said, though I believe it was ThomasT that was backed into an untenable corner iirc. I'm more interested in views that can potentially demonstrate that I'm wrong. Pretending that a class of models that are ruled out by physics (EPR) when they are not is 'effectively' a pretense about being physics. Thus the debate belongs on the issue of how I'm wrong, and how the relational interpretation is ruled out by EPR correlations. Not on labels you can impose on me to impune.

In particular what can be addressed in the general sense is this paper:
Relational EPR (http://arxiv.org/abs/quant-ph/0604064)

This paper actually weakens the notion of realism, at least as it relates to the variables under question, yet contains the points I have been making. It's not me making demands on how things are, only pointing out that a certain class being rejected is not ruled out by EPR correlations.

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

DrChinese

May14-10, 07:40 AM

unusualname

May14-10, 08:36 AM

Haven't payed much attention to what zonde and ThomasT have said, though I believe it was ThomasT that was backed into an untenable corner iirc. I'm more interested in views that can potentially demonstrate that I'm wrong. Pretending that a class of models that are ruled out by physics (EPR) when they are not is 'effectively' a pretense about being physics. Thus the debate belongs on the issue of how I'm wrong, and how the relational interpretation is ruled out by EPR correlations. Not on labels you can impose on me to impune.

In particular what can be addressed in the general sense is this paper:
Relational EPR (http://arxiv.org/abs/quant-ph/0604064)

This paper actually weakens the notion of realism, at least as it relates to the variables under question, yet contains the points I have been making. It's not me making demands on how things are, only pointing out that a certain class being rejected is not ruled out by EPR correlations.

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.

Well speaking for myself, and continuing the "bull in the china-shop" method of scientific argument (although crude, it does create a clear path), I simply don't see why anyone would prefer pleading to alternative wholesale interpretations of reality rather than accepting some rather straightforward adjuncts to the classical reality we already know and love so well.

EPR fails and shows we need an additional (or alternative) model to explain the observations of quantum theory. Well, since what fails is local classical causality, why not just accept that there's a mechanism that allows non-local causality? As long as the mechanism is consistent with other classical observations everything's sweet, n'est-ce pas?

To be consistent with classical physics, the non-local causal mechanism can't be observable classically (obviously), so lets just chuck in a non-classical space using your favourite topological construct and propose that communication occurs in that space.

That also conveniently allows us to have a real wave-function, consisting of the non-classical signal's effects on classical space at the instersection points of the topology with classical space.

That also allows us to suggest this is the space in which our consciousness exists, and clears up the mind-body duality to boot! (Evolution sussed out how to sustain consciousness in material bodys without much trouble, so it must be constructed from something that pervades the environment)

Then all we need, is some quantitative predictions from the model, such as delayed entanglement propagation, which we then observe.

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)

RUTA

May14-10, 09:22 AM

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)

I can't speak for the (few) others who prefer violations of realism to locality, but I don't want to give up relativity of simultaneity (no preferred frame) and I don't want to talk about the "future causing the past" (if the future is already "there," then you've a blockworld and nothing "happens" in a blockworld anyway) -- either or both of these obtain with causal non-locality. No matter the mechanism, if you have A causing B when A and B are space-like related, you have causal non-locality, so I opted for nonseparability. I think it's healthy for the overall effort at unification to have advocates for all the possible interpretations of QM.

DevilsAvocado

May14-10, 12:14 PM

EPR requires some further constraints as follows:
1) The LHV's can't be singular objects, but rather local ensembles, roughly analogous to what any classical waveform is.
2) The properties, presumed non-local, can't be an absolute observer independent character of the ensemble. Rather a property relative to an observer, the experimental apparatus in this case. This is why I said the fact that EPR correlations are frame dependent lends support to this view, and linked papers to demonstrate.
With these two conditions, Bell's theorem is silent. It neither proves it right or wrong, unlike the marbles.

I’m going to give you my layman assumption why I believe LHV is a dead parrot.

Please feel free to correct me (if and when I’m wrong):

YES, it’s impossible to make any distinction whatsoever between LHV and QM predictions on a singular object/particle/photon, and that’s why Einstein & Bohr had the long and unresolved EPR-debate.

In 1964 John Bell introduces the brilliant idea to enforce probability into the measurement of EPR, to be able to distinguish LHV from QM predictions. John Bell implements this in the form of varying the angles of the analyzers.

There is still no way to calculate QM probability on a single entangled pair of photons.

Today’s technique allows us to "pumping a nonlinear crystal (NL) with a strong pump field, photon pairs are created via SPDC and their polarization is detected with single-photon counters (PC) (http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2529v2.pdf)". Meaning – we can send one pair of entangled photons at a time and measure the outcome.

There is no need to 'speed up' the excitation of entangled photon pairs to get an analogy to a "classical waveform". There could be one year between every pair – and the QM predictions are still there (in the same way as Double-slit electron diffraction*).

Some argue that the entangled pair is disturbed by environment and is impossible to measure with any accuracy. This is somewhat true; there is noise which disturbs the system. However the use of Coincidence Counting (http://en.wikipedia.org/wiki/Coincidence_counting_(physics)) is "improving the signal to noise ratio to the extent that the quantum behavior can be studied, without removing the noise completely".

With the described conditions above, we can send 100 pairs of entangled photons towards the polarizer’s which are RANDOMLY ALIGNED AFTER THE ENTANGLED PAIR LEFT THE SOURCE, where the polarizer’s are separated by 18 km (http://arxiv.org/abs/0803.2425). Meaning – there is absolutely NO WAY for the entangled pair to AGREE on the outcome since they are outside each other’s light cone when the parameters for the experiment are finally settled.

QM predictions stipulate that if we send 100 entangled pairs of photons and the angle of the polarizer is 22.5°, we should get a correlation of 0.71, meaning 71 pairs are correlated (+,+) and 29 pairs are non-correlated (+,-) (-,+). And this is exactly what happens – EVERY TIME in thousands of performed experiments. And there is NO WAY for LHV to even get close to the QM 0.71 correlation, LHV always gives a 0.5 correlation.

To argue that noise is by chance creating this seemingly correlation – is not healthy science.

To argue that defective optics in crystals is by chance creating this seemingly correlation – is not healthy science.

To argue that there is an interpretation (which has not yet been confirmed) who makes everything a non-issue – is (maybe) not healthy science.

This is why I believe: Local Hidden Variable Theory = Norwegian Blue Parrot

Double-slit electron diffraction*
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If the relational interpretation holds, then it makes no difference what reference frame they are in. The measurements don't make the choice, they merely finalize them.

AFAICT this makes the "Norwegian Blue Parrot" moving a little again... :wink:

You can compress and stretch them, or even time for an individual, but event ordering remains the same. If this was possible you could use a pair of moving known frames to measure the distance to various stars, but it's not. Yet if a faster than light mechanism actually existed you could. EPR doesn't 'effectively' work to allow changing real event ordering either, which lends to the relational interpretation. Yes, I would be the lawyer.

It’s possible I have misunderstood the 'problem' of RoS & EPR, but if we for awhile pretend that LHV is a working solution, then it would all be a question of 'good old relativity'. Your example with "all bullets in one gun without knowing which" is as good as any EPR setup – it’s a question of a random value that we yet don’t know.

BUT according to all I have said so far – the outcome is settled at the measurement and are instantaneously effecting to outcome of the entangled partner.

Thus in one observer's reference frame Alice would physically causing Bob’s death, and in the other observer's reference frame Alice would be completely innocent.

I do think that would cause some trouble for you as 'the lawyer'. :rolleyes:

ThomasT

May14-10, 04:47 PM

Again, no. In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context).Right. But the joint, entangled situation requires a joint observable and a joint measurement parameter. So, do you see why lhv theories must be ruled out and why that doesn't tell us anything about Nature?

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either. So you may be correct, but you are not describing a local realistic model.I'm not trying to describe a local realist model. I'm trying to explain why a viable local realist model of entanglement can't be done.

my_wan

May14-10, 11:43 PM

Ok, the reason I got rather insistent was due to the unqualified claim that Bell's theorem proves that local realism is untenable. I take this kind of statement in the general sense, irrespective of semantics. The following quote calls this into question. I'll outline my reading of Rovelli, so perhaps we can clear the undefined issues.

Rovelli's interpretation is generally considered to be acceptable, i.e. it is not local realistic. Therefore it follows Bell.Pedantically :redface:, "not local realistic" does not in itself entail consistency with Bell. Only consistency with empirical detection statistics does that. But more importantly, Relational EPR is local and the realism has been weakened in the interpretation, not removed. Does this justify the position that Relational EPR is not locally realistic? This is strongly dependent on how the realism has been weakened, so we'll look at that a bit closer.

Relational Quantum Mechanics (http://arxiv.org/abs/quant-ph/9609002)
It should be noted the RQM is formulated as an "information theory", rather than a physical theory. This is justified by the fact that what we measure are events rather than things. These events must also involve the observer, measuring device, which is itself an ensemble of events, to have any empirical meaning. The classical notion of observation, without non-trivially interacting with the system being measured, is untenable. The notion of an object in front of you that doesn't interact with the Universe in general is empirically moot. Thus reality in the empirical regime is a verb, rather than a noun. An ensemble of verbs at that. RQM does not speak of unmeasured variables, because that includes information not available in an information theory. Neither does it claim this unavailable information is not fully contained in the local ensemble being measured. That requires the assumption that what is unknown is non-existent, which exceeds the scope of the information available.

Weakening Realism
Also very important is the notion of "observer-independent values of physical quantities". By describing reality solely in terms of verbs, Bell's theorem is sidestepped, because Bell's theorem presumes spin state is a noun, or at least has a one to one ontological correspondence with a noun (lhv). If it is a 'relative' value of an ensemble (system verbs) wrt another ensemble (observer verbs) then an absolute spin state, assumed by Bell, is untenable, at least wrt the empirical information. As a theory of information, counterfactual reasoning is not strictly valid, and obtaining information via an interaction does not entail obtaining information not already present in the local ensemble. In the words of Rovelli:http://arxiv.org/abs/quant-ph/0604064)]From[/url] the relational perspective the Heisenberg picture appears far more natural: \psi codes the information that can be extracted from past interactions and has no explicit dependence on time; it is adjusted only as a result of an interaction, namely as a result of a new quantum event relative to the observer. If physical reality is the set of these bipartite interactions, and nothing else, our description of dynamics by means of relative states should better mirror this fact: discrete changes of the relative state, when information is updated, and nothing else. What evolves with time are the operators, whose expectation values code the time-dependent probabilities that can be computer on the basis of past quantum events.Thus, realism is in fact fully maintained in Relational EPR, in the form of verbs rather than nouns, and no mechanism is required to transfer information, at the time of the measurement, from space like separated regions. The information is fully contained in local events (verbs). The distance between such ensembles, and RoS, is then a moot issue.

Strengthening Realism
What is not provided by RQM are noun predicates that define the events (verbs). This is justifiable, even if they exist, given that any ontic entity, which does not interact with the Universe, lacks any empirical relevance whatsoever. Our experience of the world is fully and exhaustively defined by these verbs (events). Yet if Einstein realism holds, at least in principle, it must be in terms of nouns on which the verbs are relativistically predicated. Such attempts are often constructed as generalized thermodynamic models. The one I referenced previously in this thread actually constructed such EPR correlations from thermodynamic ensembles, among other things. The only response I got from that was that the reference was already known.

Summation
Although Relational EPR weakens Einstein realism in an empirical sense, it does not remove it in principle. Nor is the events themselves, void of any noun predicates, anything other than empirically real events, which requires no space like separated detection of events. It is only by assuming that a lack of information entails the lack of a relativistic properties that evidence of FTL can be constructed. I'm therefore inclined to say:
1) Relational EPR is a local realistic interpretation, with the caveat that the relative 'events' are real irrespective of lacking noun predicates or observer independent variables.
2) Local realistic models can, at least in principle, be formulated consonant with Bell and Relational EPR, with the caveat being that the empirical content is contained in the form of relativistic (observer characterized) verbs.
3) Bell's theorem fails to rule out lhv models in which observables are relativistic observer dependent characterizations of an ensemble of verbs.

DevilsAvocado

May15-10, 03:38 AM

In particular what can be addressed in the general sense is this paper:
Relational EPR (http://arxiv.org/abs/quant-ph/0604064)

Eureka! I think I got it (somewhat)!
Since we know there can’t be a global universal NOW (RoS), there can’t be a global universal REALITY (for all observers), right!?

Relational EPR (http://arxiv.org/PS_cache/quant-ph/pdf/0604/0604064v3.pdf) is a cool paper! :cool:

And I must read it many times more to digest all. Rather 'shockingly' there seems to be parallels to what I was asking about in post #324 (http://www.physicsforums.com/showpost.php?p=2716407&postcount=324), and the question of a wavefunction that collapses 'twice'.
An indication of this fact is in the well-known difficulty of describing and interpreting the relativistic transformation law of the wave function, when measurements involve observers in relative motion.

Relational EPR is very cool in the sense that it tries to 'merge' GR & QM by a 'slight' modification of both interpretations of Einstein & Bohr, smart and very 'diplomatic'.

I guess my 'rant' in post #331 (http://www.physicsforums.com/showpost.php?p=2717199&postcount=331) is completely obsolete in the view of Relational EPR... sorry. :redface:

It looks like even DrChinese is out on thin ice...?
We call locality the principle demanding that two spatially separated events cannot have instantaneous mutual influence. We will argue that this is not contradicted by EPR type correlations, if we take the relational perspective on quantum mechanics.

Locality is at the very roots of RQM, in the observation that different observers (in general distant from one another) can have different descriptions of the same system.

I must digest and read again, but I shall return. Thanks for the link.

http://upload.wikimedia.org/wikipedia/en/thumb/b/b0/Observer-observed.gif/350px-Observer-observed.gif
Observer O measures the state of the quantum system S

my_wan

May15-10, 05:00 AM

Well speaking for myself, and continuing the "bull in the china-shop" method of scientific argument (although crude, it does create a clear path), I simply don't see why anyone would prefer pleading to alternative wholesale interpretations of reality rather than accepting some rather straightforward adjuncts to the classical reality we already know and love so well.Yes, I seek as few adjuncts to classical physics as possible. What I hope to have made clear, unless someone can provide a good counterargument, is that, at least in principle, it's possible to maintain both locality and realism. If someone can posit a rational FTL mechanism, that's empirically useful, I'll accept that as a local mechanism. The speed C is the limit of locality as we know because that's what it defines given our present understanding, not because it is, if faster effects exist. However, simply as a method of sweeping EPR under a rug is not a valid justification in my view.

EPR fails and shows we need an additional (or alternative) model to explain the observations of quantum theory. Well, since what fails is local classical causality, why not just accept that there's a mechanism that allows non-local causality? As long as the mechanism is consistent with other classical observations everything's sweet, n'est-ce pas?Ok, perhaps so, but before that can be stated without equivocation, the objections I have articulated must be addressed. Merely stating it is so does not make it so. As for my reasons for avoiding non-local effects: Because the conceptual and mathematical nightmare it creates in trying to get it to coexist with what we know is beyond belief. Even QM presently is a tame beast in comparison. If it remains "consistent with other classical observations" then it must lack empirical meaning, outside of sweeping conceptual issues under the rug. The constraints of RoS are quiet severe.

To be consistent with classical physics, the non-local causal mechanism can't be observable classically (obviously), so lets just chuck in a non-classical space using your favourite topological construct and propose that communication occurs in that space.Some of my own modeling attempts explicitly allow certain variables of sorts to randomly exceed C. Yet it's unworkable as an EPR mechanism, or any FTL summation. So I'm not adverse to FTL mechanisms as such, but merely to poke it in like some surgical instrument accidentally sewed into your body by a surgical doctor doesn't cut the mustard for me.

That also conveniently allows us to have a real wave-function, consisting of the non-classical signal's effects on classical space at the instersection points of the topology with classical space.FTL is not a requirement for real wavefunctions. It does seem require a separation, at least in principle, between the waveform (itself an ensemble), and the ensemble imposed by on it solely by limitations of specific knowledge of that ensemble.

That also allows us to suggest this is the space in which our consciousness exists, and clears up the mind-body duality to boot! (Evolution sussed out how to sustain consciousness in material bodys without much trouble, so it must be constructed from something that pervades the environment)
Ouch, I don't have a problem with the mind/body connection. I can even provide an empirically realistic self organizing 'toy' mind model, including memory, qualia, and evolutionary stages, with nothing more than metronomes and springs. Mathematically it's not really fundamentally new, but makes it easy to visualize how it leads to the empirical data. I generally find this kind of question involves the composition fallacy, and a failure to appreciate the nature and ubiquity of emergent properties. For this reason I find it interesting, but outside the scope here.

Then all we need, is some quantitative predictions from the model, such as delayed entanglement propagation, which we then observe.Perhaps even something that''ll fill the holes left by Bell's theorem.

There, that's much more reasonable than relational interpretrations of reality and other such malarky. :)I suspect that in labeling it "malarky" it's being interpreted within a singular myopic ontology. It was intentionally restricted in terms of an "information theory" for empirical and model independent consistency. Read my last response to DrC and I included at least one ontological model extension. If I took it as a final answer to the issues posed by QM, which I don't accept without GR, it would in fact be at the very least pointless. Understand what actually makes it work, and it gives you tools to think about real models, rather than just boring interpretations.

The most fundamental point I'm trying to make here is that, contrary to common opinion, EPR correlations don't entirely rules out all locally realistic theories. I've also provide the caveats that such models would require. I still have some interesting points to articulate for DevilsAvocado's last post. I look forward to defeat, if that is the truth, but the points actually need addressed for that to happen.

RUTA

May15-10, 09:01 AM

Summation
Although Relational EPR weakens Einstein realism in an empirical sense, it does not remove it in principle. Nor is the events themselves, void of any noun predicates, anything other than empirically real events, which requires no space like separated detection of events. It is only by assuming that a lack of information entails the lack of a relativistic properties that evidence of FTL can be constructed. I'm therefore inclined to say:
1) Relational EPR is a local realistic interpretation, with the caveat that the relative 'events' are real irrespective of lacking noun predicates or observer independent variables.
2) Local realistic models can, at least in principle, be formulated consonant with Bell and Relational EPR, with the caveat being that the empirical content is contained in the form of relativistic (observer characterized) verbs.
3) Bell's theorem fails to rule out lhv models in which observables are relativistic observer dependent characterizations of an ensemble of verbs.

I spent hours yesterday with my philosopher of science colleague reading van Fraassen and Rovelli on RQM. We think we have it figured out (it's a challenge, thus the van Fraassen's paper). Crudely, it's information theory plus the light cone structure. Overall, physics is about information and special relativity and QM are rules for the exchange of information. RQM says information exchange is local per SR with correlations per QM. RQM does not provide an underlying mechanism for those QM correlations, so we were frustrated until we figured that out and quit looking for his ontology.

Given what I (mis?)understand about RQM, I would say it does not accomplish local realism, weakly or otherwise. He's in the nonseparable (not realism) class, clearly, but exactly how he doesn't say. I'm inclined to think he's saying QM is fundamental, so there is no "why" for its correlations. This is like SR postulating the constancy of c. It's a postulate, so there is no explanation for "why" everyone measures the same speed for light. It's just a brute fact about information and its exchange.

BTW, we think RBW can be used to provide a "why" for information theory and RQM, but that's another story.

my_wan

May15-10, 09:05 AM

Eureka! I think I got it (somewhat)!
Since we know there can’t be a global universal NOW (RoS), there can’t be a global universal REALITY (for all observers), right!?
Yes, but there can be a form of general covariance. So in a relativistic sense it still describes the same thing, with different correlation statistics, measurements, etc. Not a separate reality as opined earlier in this thread. We already empirically know that EPR correlations are frame dependent.

Relational EPR (http://arxiv.org/PS_cache/quant-ph/pdf/0604/0604064v3.pdf) is a cool paper! :cool: Yes, you also need to go over Relational Quantum Mechanics (http://arxiv.org/abs/quant-ph/9609002) for more detail on the interpretation as it relates to QM. Be aware that, as an interpretation, it remains model neutral. That doesn't preclude ontological extensions that go beyond purely the measured information without violating the legitimacy of RQM, as I pointed out in my last post to DrC. The sum total of all measurements is after all a complete specification of what we know or can empirically know, with or without theories that synthesis it in workable models.

And I must read it many times more to digest all. Rather 'shockingly' there seems to be parallels to what I was asking about in post #324 (http://www.physicsforums.com/showpost.php?p=2716407&postcount=324), and the question of a wavefunction that collapses 'twice'.Yes, I only mentioned the "twice collapsing wavefunction" once in passing. Actually my version was a collapsed wavefunction that wasn't collapsed for another observer. This can easily lead outside the EPR question of this thread, but I tend to think the formalized wavefunction consist of real quasi-localized fields we call particles, smeared (superimposed) over all possibilities not entirely relevant to a single self interacting particle (ensemble). This would indicate a the collapse didn't localize the particle, it merely reduced all possibles, from lack of a priori knowledge, to just the information relevant to that one particle. A large number of individual detections of self interacting particles must still be representative of all possibilities, as the formalized wavefunction requires.

Relational EPR is very cool in the sense that it tries to 'merge' GR & QM by a 'slight' modification of both interpretations of Einstein & Bohr, smart and very 'diplomatic'.This "diplomacy" has strengths and weaknesses, and was predicated more on the notion of an "information theory" consonant with QM than diplomacy. It allows the interpretation to be model independent, and still allow logical cogency to be analyzed. Its weakness is that it doesn't by itself provide pointers to how to construct a model, consonant with RQM and/or GR, that could potentially lead us to new empirical content or unification. It's not that hard to access a models cogency with RQM after the fact though. Does P=NP?

I guess my 'rant' in post #331 (http://www.physicsforums.com/showpost.php?p=2717199&postcount=331) is completely obsolete in the view of Relational EPR... sorry. :redface:
Yes, the single particle verses statistical ensembles of possibilities which may only be relevant in part to that single particle verses statistics of a large number of detections where all possibilities becomes relevant makes it somewhat difficult to think about. We know that particles are self interacting, so the wavefunction is relevant, at least in part, to single particles. Though I think it most likely that all possibilities is a useful fiction in the single particle case, while the particle is still a quasi-localized ensemble (field). You also seem to have gotten the issues that a Universal now would impose on present physics if it defines something that can't exist via RoS. If it's found to exist then it can't exist at any given time relative to a particular observer. It only goes stark raving mad from there, however easy it is to say now is now for me. I'll bow to anybody that can pull it off.

It looks like even DrChinese is out on thin ice...?
So am I. I've included a lot of opinion about what is possible here. However, I'm fairly confident in the main points of my claim as they relate to the EPR subject of this thread. Not as a fact of how nature is, but in the claim that EPR correlations fail to rule out the class of LHV theories specified.

I must digest and read again, but I shall return. Thanks for the link.

http://upload.wikimedia.org/wikipedia/en/thumb/b/b0/Observer-observed.gif/350px-Observer-observed.gif
Observer O measures the state of the quantum system S
:rofl:
If you could, continue to try and poke holes in the possibility of LHV models of the class I've specified. It's difficult to learn from merely chasing support for a preexisting viewpoint. I'd like to hear your perspective of what you get from it anyway, and any questions or problems that I failed to address.

unusualname

May15-10, 09:27 AM

Yes, I seek as few adjuncts to classical physics as possible. What I hope to have made clear, unless someone can provide a good counterargument, is that, at least in principle, it's possible to maintain both locality and realism. If someone can posit a rational FTL mechanism, that's empirically useful, I'll accept that as a local mechanism. The speed C is the limit of locality as we know because that's what it defines given our present understanding, not because it is, if faster effects exist. However, simply as a method of sweeping EPR under a rug is not a valid justification in my view.

Ok, perhaps so, but before that can be stated without equivocation, the objections I have articulated must be addressed. Merely stating it is so does not make it so. As for my reasons for avoiding non-local effects: Because the conceptual and mathematical nightmare it creates in trying to get it to coexist with what we know is beyond belief. Even QM presently is a tame beast in comparison. If it remains "consistent with other classical observations" then it must lack empirical meaning, outside of sweeping conceptual issues under the rug. The constraints of RoS are quiet severe.

Some of my own modeling attempts explicitly allow certain variables of sorts to randomly exceed C. Yet it's unworkable as an EPR mechanism, or any FTL summation. So I'm not adverse to FTL mechanisms as such, but merely to poke it in like some surgical instrument accidentally sewed into your body by a surgical doctor doesn't cut the mustard for me.

FTL is not a requirement for real wavefunctions. It does seem require a separation, at least in principle, between the waveform (itself an ensemble), and the ensemble imposed by on it solely by limitations of specific knowledge of that ensemble.

Ouch, I don't have a problem with the mind/body connection. I can even provide an empirically realistic self organizing 'toy' mind model, including memory, qualia, and evolutionary stages, with nothing more than metronomes and springs. Mathematically it's not really fundamentally new, but makes it easy to visualize how it leads to the empirical data. I generally find this kind of question involves the composition fallacy, and a failure to appreciate the nature and ubiquity of emergent properties. For this reason I find it interesting, but outside the scope here.

Perhaps even something that''ll fill the holes left by Bell's theorem.

I suspect that in labeling it "malarky" it's being interpreted within a singular myopic ontology. It was intentionally restricted in terms of an "information theory" for empirical and model independent consistency. Read my last response to DrC and I included at least one ontological model extension. If I took it as a final answer to the issues posed by QM, which I don't accept without GR, it would in fact be at the very least pointless. Understand what actually makes it work, and it gives you tools to think about real models, rather than just boring interpretations.

The most fundamental point I'm trying to make here is that, contrary to common opinion, EPR correlations don't entirely rules out all locally realistic theories. I've also provide the caveats that such models would require. I still have some interesting points to articulate for DevilsAvocado's last post. I look forward to defeat, if that is the truth, but the points actually need addressed for that to happen.

The problem you have is that not many people working in modern physics really care that EPR violations can be explained away by philosophical arguments about the nature of reality. You've mentioned the relational interpretation and an interpretation based on "probabilistic realism" (which I did reply to btw, I think you missed that since you claim your post was ignored) which are fun for those of a philosophical bent to ponder but for pragmatic scientists they are not very useful.

The relational interpretation is particularly unappealing, it just comes across as a clumsy way of extending einstein's spacetime relativity.

You (too) easily claim that consciousness may be explained by emergent properties in complex systems, as if that was a simple issue in comparison to explaining nonlocality!

The physical world is stuff A, consciousness is stuff B. Science will have to accept sooner or later that we haven't included stuff B in our models of reality.

Once we accept that stuff B has to be included we begin the next stage of our scientific development.

I don't think we need to throw deep philosophical arguments in just yet, science is about making theoretical models of how things work so as to make predictions or explain "why" something happens or is the way it is. Science starts with observations, and what I observe is that there is a physical world and there is my conscious awareness of this physical world. My conscious awareness is clearly not part of the physical world, so to model it scientifically I suggest it exists in is own separate "space", which mathematically we can model with extra dimensions appended to physical space or other topological constructs.

Our conscious thoughts seem to be able to have effects in the physical world and the physical world certainly affects our consciousness so we assume the two spaces are joined and can influence each other.

We can also assume consciousness is mundane and not something mystical, since it emerged from a mundane process, evolution.

Given that the only phenomena in science we know to be in conflict with classical local realism are quantum effects, it seems natural to assume consciousness and quantum effects are related, in particular it seems that entanglement and quantum computation gives a natural setting for our consciousness.

It also allows a natural solution to the problem of free-will: without conscious beings the universe is essentially the result of statistical physics. However, if we actually "are" a quantum system it seems reasonable to assume we can influence or "choose" quantum states in our own quantum system, so free-will is a conscious being selecting quantum states in his consciousness (which propagate to effects in the physical world). We do have to allow that an individual particle also has free-will, but if it's not related to any "desires" in a complex consciousness the "choices" made by individual particles are indistinguishable from random.

(Why we have desires to influence quantum states one way or another is complex, and the problem of the human condition)

Rather than argue subtle and complex philosophical issues this raises I like to imagine a simple "thought experiment":

Imagine a sophisticated computer based on Mars, which knows all current physics, observing the Earth's exterior for the last few billion years. The computer would record all physical events, eruptions, meteor impacts, climate change etc and fit them to its physics model without much trouble. But then in 1957 it sees a metal object shoot up from the surface and deliberately orbit the earth, in the years following it sees another metal object travel to the moon. How does it explain that with physics? Have conservation laws been broken? How can those events fit a physical model of the earth which started as a relatively simple physical object, a big ball of molten rock.

Heck, we could even blow the earth to pieces, maybe even the universe.

Without including consciousness (stuff B) as an additional component to reality in your scientific models you get nonsense.

So putting it all together, and returning to the OP's question, I suggest entanglement is due to signalling in the space of stuff B. It doesn't conflict with classical causality because the entire causal chain is restricted to the space of stuff B, although it may give rise to curious observations of backward events in the space of stuff A (classical space), it doesn't allow FTL signalling in the space of stuff A.

I don't even think this is a controversial model, it's bleedin' obvious.

DevilsAvocado

May15-10, 10:36 AM

My conscious awareness is clearly not part of the physical world

Huh? Can that really be proven?

without conscious beings the universe is essentially the result of statistical physics.

Huh?? So the first 400 millions yrs after BB, before the first star was formed – and consciousness was impossible – the universe was a deterministic machine without HUP...?:bugeye:?

But then in 1957 it sees a metal object shoot up from the surface and deliberately orbit the earth, in the years following it sees another metal object travel to the moon. How does it explain that with physics?

If the sophisticated Mars computer had a really good telescope, it could see the first tree deliberately rise from the mud. We don’t apply consciousness to a tree, do we...?? :wink:

DevilsAvocado

May15-10, 10:50 AM

If you could, continue to try and poke holes in the possibility of LHV models of the class I've specified.

You bet! :grumpy:
(:biggrin:)

I think it’s time for some reconciliation... my brain is smeared out (superimposed) over all possibilities in trying to understand EPR – from DrC’s experimental-down-to-earth, to RUTA’s 'strange' RBW, and your 'special' RQM, and now comes an unusualname and propose that consciousness is the key...?:bugeye:?

I got to think... (for a change ;)

ThomasT

May15-10, 03:25 PM

In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context).That's right. (You're almost there.) But entanglement IS a JOINT observational context. (Let that sink in for a moment.)

Now, is what's being measured in the separate measurements at A and B the same as what's being measured jointly?
The answer is no. That's why I said:

It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation.

... in a local world, what happens here does not affect what happens there.That's right. But there are only two values for |a - b| where A and B are perfectly correlated (anticorrelated), and these perfect correlations are compatible with the assumption that the relationship between the entangled photons has a local common cause.

But, you might counter, the full range of entanglement stats can't be reproduced by a lhv description of the joint context. And that's correct, but it's because what's being measured in the separate measurements at A and B is not the same as what's being measured jointly.

A local hidden variable account of the joint context requires the parameter determining joint detection RATE (this parameter is the relationship BETWEEN the relevant individual property or properties of the disturbances incident on a and b) to be described in terms of the parameter determining individual detection SEQUENCE (this parameter is the relevant individual property or properties).

Hence our catch-22 situation: there's no way to model the joint situation using individual properties and get the full range of entanglement stats -- yet an lhv model requires the joint state to be described in terms of the individual properties, properties which, it's quite easy to see, can't possibly be put into a form which would account for the full range of entanglement stats. It's like requiring a peg to fit into a hole that, if you just look at the situation, it can't possibly fit into, and then making all sorts of wild speculations and new realities to account for why it doesn't fit into the hole.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either.(1) The joint measurement parameter is |a - b|. (2) What |a - b| is measuring is the relationship between the counter-propagating disturbances. Both (1) and (2) are compatible with the assumption of c-limited locality.

So you may be correct ...It is correct. But the presentation needs some refining.

... but you are not describing a local realistic model.Hopefully it will become clear that I'm not trying to do that, but rather explain why such a model is impossible, and why the impossibility of constructing such a model doesn't imply nonlocality (or ftl info transfer) in Nature.

ThomasT

May15-10, 03:28 PM

EPR fails and shows we need an additional (or
alternative) model to explain the observations of quantum
theory.There is a local causal explanation for EPR. Just as
there is a local causal explanation for any entanglement stats. It's
just that these stats can't be predicted by an explicit lhv model. And
the reason for that has to do with a disparity between the requirements
of an explicit lhv model and the experimental situation that is being
modelled, independent of the consideration of locality, which is what
I've been talking about in my many posts in this thread.
Well, since what fails is local classical causality
...No, that's not what fails. What fails is the requirement
that an experimental situation be modelled in terms of variables which
are irrelevant wrt the experimental situation.
... why not just accept that there's a mechanism
that allows non-local causality?Because there's a simpler
explanation for why BIs are violated that doesn't require nonlocality
or any interpretation of qm other than the standard one.

-----------snip malarky -----------

There, that's much more reasonable than relational
interpretrations of reality and other such malarky. :)No, it's malarky.

ThomasT

May15-10, 03:45 PM

Since I haven't really received a proper rebuttal, perhaps some questions to clear up the distinctions I'm making between what is and isn't ruled out by EPR experiments, or attempts to paraphrase what I've said so I can see what the issue is.The challenge is to explain why lhv descriptions of entanglement are impossible without resorting to artificial constructions of 'reality', or positing nonlocality or ftl transmissions, etc. I think that's possible.

Read what I've posted. Because if it's correct, then all of the speculative interpretations of qm which purport to account for violations of BIs are simply not necessary to account for violations of BIs -- and a rather well established interpretation of qm, namely dBB theory, might then need to be viewed as quite probably just wrong wrt its explicit nonlocality.

As long as we continue thinking that we don't or can't know exactly why BIs are violated, then the door is open to lots of stuff that would otherwise just be dismissed as being obviously silly.

But, what I'm saying is that we can know why BIs are violated and that it's right in front of us, and all we have to do is compare the requirements of an lhv theory with the reality (ie., the preparations) of entanglement experiments and it's immediately apparent why lhv descriptions of these experimental situations are impossible -- without resorting to nonlocality, or ftl, or dBB, or MWI, or RQM, or RBW, etc.

If one of your electrical appliances doesn't turn on, what's the FIRST thing you do? Check to see that it's plugged in, right? Unfortunately the equivalent isn't happening wrt speculations surrounding the incompatibility between lhv models and entanglement.

unusualname

May15-10, 04:04 PM

Huh? Can that really be proven?

No, it's just an observation (that consciousness is not part of the physical world)

Huh?? So the first 400 millions yrs after BB, before the first star was formed – and consciousness was imp ossible – the universe was a deterministic machine without HUP...?:bugeye:?

Well the uncertainty principle still applied, but (assuming no other conscious lifeforms had formed) the universe was deterministic in the sense of statistical physics, but remember that classical determinism doesn't imply perfect predictability due to the limitations imposed by chaos theory, even in a simple 3-body planetary system.

If the sophisticated Mars computer had a really good telescope, it could see the first tree deliberately rise from the mud. We don’t apply consciousness to a tree, do we...?? :wink:

Ok a joke, but a tree doesn't do anything beyond what we can explain by simple physics, it doesn't have sophisticated inputs from the physical world (no non-trivial sense organs) either. Simple physics can't explain the journey taken by the Apollo rocket to the moon, since it was guided by conscious choices.

I noticed some links were posted above to preprints discussing the behaviour of entangled systems in moving classical frames http://arxiv.org/abs/quant-ph/0302095 and http://arxiv.org/abs/quant-ph/0205179 , these results show that the classical observables in entangled systems vary according to the reference frame, but that's not unexpected since I would expect a form of special relativity to apply to any additional spaces appended to classical reality, just that we don't need to assume c is the limiting speed in that space. :)

unusualname

May15-10, 04:40 PM

There is a local causal explanation for EPR. Just as
there is a local causal explanation for any entanglement stats. It's
just that these stats can't be predicted by an explicit lhv model. And
the reason for that has to do with a disparity between the requirements
of an explicit lhv model and the experimental situation that is being
modelled, independent of the consideration of locality, which is what
I've been talking about in my many posts in this thread.

By "explanation" I mean one that makes sense scientifically.

Because there's a simpler
explanation for why BIs are violated that doesn't require nonlocality
or any interpretation of qm other than the standard one.

-----------snip malarky -----------

Your "simple explanation" is the most convoluted one in the whole thread, at least mine is "simple" ;)

IcedEcliptic

May15-10, 07:33 PM

By "explanation" I mean one that makes sense scientifically.

Your "simple explanation" is the most convoluted one in the whole thread, at least mine is "simple" ;)

I have been quietly reading this for some time, and I agree. I don't ascribe to the RUTA or unusualname view, but I recognize them as scientific and plausible.

Zonde, ThomasT, you are selling your own crazed theories.

my_wan

May15-10, 08:40 PM

You bet! :grumpy:
(:biggrin:)

I think it’s time for some reconciliation... my brain is smeared out (superimposed) over all possibilities in trying to understand EPR – from DrC’s experimental-down-to-earth, to RUTA’s 'strange' RBW, and your 'special' RQM, and now comes an unusualname and propose that consciousness is the key...?:bugeye:?

I got to think... (for a change ;)
:rofl: :rofl:
I've provided no better reason to presume my approach is any better than anybody elses. I would encourage not attaching to a particular view for purely anesthetic reasons. The point I hope to make clear is that EPR correlations, in spite of the very real constraints it imposes, does not support nor rule out local causality in general. That is the point relevant to the OP.

Personally, interpretations for their own sake is of very little interest to me. As a group they provide a space of possibilities, much like EPR correlations provides limits. I also consider observationally equivalent ontologies to the ontological interpretations provided. If an ontologically pleasing interpretation is all that is at stake, QM is just fine as is. But we still have the issue how to get QM and GR to play well together, with a formalism that provides empirical data, more than mere interpretations. The notion that interpretation alone is a useful construct is a stretch for me, especially with bigger game potentially available. Also, the notion that some things simply are because they are (fundamental) may in fact be so, but I think that presuming a priori that they are can be a self defeating self imposed limitation. The history of science supports the notion that fundamental principles can often be derived from more fundamental constructs.

So all the various interpretations have value, in their own way, but attempting to convince me that a given interpretation is the one true interpretation, like a one true absolute frame of reference, is a lost cause in my view. This multiplicity of views and approaches has value, often not as incongruent as supposed if you don't take ontologies as absolutes, and is an important part of the search.

DevilsAvocado

May15-10, 08:57 PM

So all the various interpretations have value, in their own way ...

Okay, I hear you... so how do we proceed to find the TRUTH!? :surprised

(:rofl:)

DevilsAvocado

May15-10, 09:03 PM

No, it's just an observation (that consciousness is not part of the physical world)

I’m curious about this. It’s our brains that have 'trouble' with EPR – not EPR itself (meaning the experiment ;).

I agree, it’s very "natural to assume consciousness and quantum effects are related", even though I personally don’t think it has anything to do with 'binary computing' – with the main objection that the brain is a living biological tissue with a electrochemical network, connected to a living body, which in turn are (must be) connected to other living bodies/brains in a social and cultural network, where the human language is the most important factor (put a newborn in an isolated box, and you will have a creature that has more common with a crazy chimpanzee than a human), whereas the quantum computer is stone dead, and completely alone, even if it has a NIC.

Could you imagine two quantum computers in love, 'connected' by a Cat5!? :biggrin:
Edit: And now I just realized netdating! :biggrin:

(My personal wild guess is that the brain is instead of binary 1/0, is utilizing 'analog chemistry' to build up 'thresholds' to trigger 'events', like falling in love, etc...)

Well the uncertainty principle still applied, but (assuming no other conscious lifeforms had formed) the universe was deterministic in the sense of statistical physics, but remember that classical determinism doesn't imply perfect predictability due to the limitations imposed by chaos theory, even in a simple 3-body planetary system.

Agree, and we can probably be 100% sure that no other conscious was available < 400 myrs, except if life could emerge from free-streaming radiation or cold dark matter...? This would be a miracle that would put EPR in 'kindergarten'! :smile:

... a tree doesn't do anything beyond what we can explain by simple physics ...

Huuum, can we really describe DNA and the "life of a tree" by "simple physics"...? Where is that formula??

I noticed some links were posted above to preprints discussing the behaviour of entangled systems in moving classical frames ...

The paper Quantum Entanglement of Moving Bodies (http://arxiv.org/abs/quant-ph/0205179) is very interesting (why did I miss that?). This seems to prove that the wavefunction is Lorentz invariant (covariant?), and my 'speculation' about RoS wavefunction contradictions is in-valid... still it’s hard to accept that the joint entanglement of the wavefunction can 'survive' this 'environment':

http://upload.wikimedia.org/wikipedia/commons/e/e4/Lorentz_transform_of_world_line.gif
Views of spacetime along the world line
of a rapidly accelerating observer moving
in a 1-dimensional "universe"

zonde

May16-10, 12:38 AM

I have been quietly reading this for some time, and I agree. I don't ascribe to the RUTA or unusualname view, but I recognize them as scientific and plausible.

Zonde, ThomasT, you are selling your own crazed theories.
Scientific means that there is something testable about idea apart from hand waving.
Where is that part in RUTA or unusualname views that you call them scientific?

My idea however can be tested easily any time (assuming of course you have equipment for basic Bell inequality test).
Another thing is that my idea is based on things that you observe in experiments and not on whats in other people heads. So you can call my idea crazy but it's much tighter bound with what you can observe out there compared to those plausible other ideas.

my_wan

May16-10, 03:25 AM

I spent hours yesterday with my philosopher of science colleague reading van Fraassen and Rovelli on RQM. We think we have it figured out (it's a challenge, thus the van Fraassen's paper). Crudely, it's information theory plus the light cone structure. Overall, physics is about information and special relativity and QM are rules for the exchange of information. RQM says information exchange is local per SR with correlations per QM. RQM does not provide an underlying mechanism for those QM correlations, so we were frustrated until we figured that out and quit looking for his ontology.

The last sentence contains what it appears I need to respond to. No, it doesn't specify a mechanism any more than you specify a mechanism by which you know a heads up coin has tails down. Now your obviously not going to get 1 to 1 like a coin with ensembles and relational variables. Recall, as you noted, this cast not just RQM but QM itself as an "information theory". Thus the content of the wavefunction is a specification of what is known from prior measurements, not the actual physical content of it. Read the quote from the paper I provided DrC again:From the relational perspective the Heisenberg picture appears far more natural: \psi codes the information that can be extracted from past interactions and has no explicit dependence on time; it is adjusted only as a result of an interaction, namely as a result of a new quantum event relative to the observer. If physical reality is the set of these bipartite interactions, and nothing else, our description of dynamics by means of relative states should better mirror this fact: discrete changes of the relative state, when information is updated, and nothing else. What evolves with time are the operators, whose expectation values code the time-dependent probabilities that can be computed on the basis of past quantum events.The lack of time dependence mentioned is because the information defined is only that information available from past interactions. The only thing that evolves with time is the empirical time-dependent probabilities computed from past quantum events. If this was a physical theory, rather than an information theory, then you could properly talk about the evolution of relative variables. This is important to realize, that the claim is that both RQM and QM are information theories. Talking about how two particles correlate spins in this situation is pointless, because all it really did was fill in information we couldn't obtain from past measurements. It's like wondering how the other side of the heads up coin knew to be tails, only we are dealing with ensembles of relational variables here (quantum events).

Given what I (mis?)understand about RQM, I would say it does not accomplish local realism, weakly or otherwise. He's in the nonseparable (not realism) class, clearly, but exactly how he doesn't say. I'm inclined to think he's saying QM is fundamental, so there is no "why" for its correlations. This is like SR postulating the constancy of c. It's a postulate, so there is no explanation for "why" everyone measures the same speed for light. It's just a brute fact about information and its exchange.Nonseparable, in the sense used in RQM and claimed for QM, is the same sense in which 10 red and 10 blue marbles are randomly mixed and placed equally in each of 2 boxes. Now, without looking in those boxes, the "information" you have about the number of red and blue marbles in each box is nonseparable. Yet opening one box instantly provides information about what's in the other box, and requires no FTL mechanism regardless of separation.

Now RQM also justifies this "information theory" (RQM and QM) as a complete description of what can be known, and they're absolutely right in a 'purely' empirical sense. I still prefer a wider range of empirically equivalent model constructs.

BTW, we think RBW can be used to provide a "why" for information theory and RQM, but that's another story.RBW is an impressive construct. How difficult would it be to recognize if its ontology was remodeled into an exactly equivalent logical construct that reversed the concept of motion again? The issues raised wrt RQM makes me question this. Ontologies are mostly more akin to coordinate systems that truth statements in my view, with some caveats.

IcedEcliptic

May16-10, 08:17 AM

Scientific means that there is something testable about idea apart from hand waving.
Where is that part in RUTA or unusualname views that you call them scientific?

My idea however can be tested easily any time (assuming of course you have equipment for basic Bell inequality test).
Another thing is that my idea is based on things that you observe in experiments and not on whats in other people heads. So you can call my idea crazy but it's much tighter bound with what you can observe out there compared to those plausible other ideas.

OK, your idea is crazy.

DevilsAvocado

May16-10, 11:07 AM

Nonseparable, in the sense used in RQM and claimed for QM, is the same sense in which 10 red and 10 blue marbles are randomly mixed and placed equally in each of 2 boxes. Now, without looking in those boxes, the "information" you have about the number of red and blue marbles in each box is nonseparable. Yet opening one box instantly provides information about what's in the other box, and requires no FTL mechanism regardless of separation.

Thanks my_wan for the marble analogy, it’s simple and beautiful.

I want to add a 'function' to this story, to make it 'compatible' with my understanding of what happen at Bell test experiments:

10 white and 10 white marbles are randomly mixed and placed equally in each of 2 boxes (i.e. entangled photons are spinless before measurement).

Now, without looking in those boxes, the "information" you have about the number of marbles is that there are 10 white marbles in every box.

We separate the boxes by 18 km, so they cannot influence each other.

For the 'measurement' we have arranged a sloping bridge that randomly will make the marble roll of to the right, or to the left. If the marble goes left, it will land in red dyeing bath, and come out as a red marble for inspection. If the marble goes right, it will land in blue dyeing bath, and come out as a blue marble for inspection.

When we run this experiment thousands of times, with different angles on the sloping bridge (thus changing the probability for red vs. blue) it turns out that the marbles in the two boxes are perfectly correlated with each other. And not only that, the actual correlation is corresponding exactly to the predictions of QM probabilities for marbles on a sloping bridge!

Now, did I poke a hole in the 'RQM Box', or not...!? :grumpy:

(:wink:)

my_wan

May16-10, 05:41 PM

Thanks my_wan for the marble analogy, it’s simple and beautiful.

I want to add a 'function' to this story, to make it 'compatible' with my understanding of what happen at Bell test experiments:

10 white and 10 white marbles are randomly mixed and placed equally in each of 2 boxes (i.e. entangled photons are spinless before measurement).

Now, without looking in those boxes, the "information" you have about the number of marbles is that there are 10 white marbles in every box.

We separate the boxes by 18 km, so they cannot influence each other.

For the 'measurement' we have arranged a sloping bridge that randomly will make the marble roll of to the right, or to the left. If the marble goes left, it will land in red dyeing bath, and come out as a red marble for inspection. If the marble goes right, it will land in blue dyeing bath, and come out as a blue marble for inspection.

When we run this experiment thousands of times, with different angles on the sloping bridge (thus changing the probability for red vs. blue) it turns out that the marbles in the two boxes are perfectly correlated with each other. And not only that, the actual correlation is corresponding exactly to the predictions of QM probabilities for marbles on a sloping bridge!

Now, did I poke a hole in the 'RQM Box', or not...!? :grumpy:

(:wink:)
Cool, but I don't see this working, because as an information theory it is our information that lacks spin, not necessarily the photon. But, let's assume they are all white, and design out thought experiment (detectors) to better represent the conservation laws we do have information about. The same conservation law that require EPR correlations to begin with.

We have 20 white marbles. We collide (interact) pairs of marbles such that they leave this collision/interaction in opposite directions on the X axis. 18 km away, in each direction, we have a pair of side by side paint buckets such that one is on each side of the X axis in each direction. I'll also show this is still valid even if the marbles are never painted (relational interpretation).

Now, when one marbles lands in the (-X,Y) quadrant bucket, conservation laws demand that it is more probable that the other marble will land in the (X,-Y) bucket. Furthermore, we don't even have to paint the marbles when they land in our buckets, they remain white. We merely define marbles that land in the (-X,Y) and (X,Y) buckets as red, and (-X,-Y) and (X,-Y) as blue (opposite properties per correlation). Now red and blue becomes a purely relational concept, relative to the configuration of the bucket detectors and their overall geometry. In that case red and blue are no more real after the measurement than before, except relative to the measuring device.

Note: If QM is an information theory, as RQM posits, it can't be a priori claimed this is reasonable analogy of how it works, as it provides 'information' that's by definition not available. RQM does explicitly posit the relational properties analogous the the relational red and blue properties above. So, like Bell's theorem, even if we assume RQM is perfectly valid in principle, it does not prove no FTL mechanism exists or isn't involved, only that they aren't required.

DrChinese

May16-10, 07:14 PM

If one of your electrical appliances doesn't turn on, what's the FIRST thing you do? Check to see that it's plugged in, right? Unfortunately the equivalent isn't happening wrt speculations surrounding the incompatibility between lhv models and entanglement.

You got the analogy backwards. This is exactly what happened in the 30 years from 1935 to 1965. A common view was that local realism was compatible with the predictions of QM. Bell put that to an end. At least mostly. :smile:

Anyway, I have personally spent plenty of time looking for cracks in Bell. Thousands of others have too. So you are really selling the physics community short, as well as repeating the same unsubstantiated claims.

my_wan

May17-10, 12:13 AM

You got the analogy backwards. This is exactly what happened in the 30 years from 1935 to 1965. A common view was that local realism was compatible with the predictions of QM. Bell put that to an end. At least mostly. :smile:

Anyway, I have personally spent plenty of time looking for cracks in Bell. Thousands of others have too. So you are really selling the physics community short, as well as repeating the same unsubstantiated claims.
Here I agree with you, though I'm not so sure about "mostly". :smile:

EPR correlations do in fact rule out Einstein realism in the sense of absolute observables that can be completely passively observed empirically. Foundationally I don't see this as a problem, because something that exist but doesn't interact with anything isn't observable. Thus what we observe empirically are interactions, not things. However, with Bell's theorem we are provided with two choices: 1) Take the evidence EPR correlations provide as evidence to look beyond the standard local effects, which it is evidence though not proof. 2) Use the constraints imposed by EPR correlations to abandon that set of locally realistic models in contradiction, and try to ferret out the subset capable of maintaining consistency. Which to date hasn't provided any new physics, only interpretations with varying levels of cogency.

Both these possibilities needs investigated, and the first one to succeed, if either can, wins. Debate points notwithstanding, only physics. Thus there are no winners as of today. I therefore object to overstating claims on both ends. :tongue:

ThomasT,
Yes, DrC is correct that your analogy unduly short changes a lot of awe inspiring work by many many brilliant people. Many things I once assumed were extremely unlikely in fact now has come to pass.

DevilsAvocado

May17-10, 08:06 AM

Cool, but I don't see this working, because as an information theory it is our information that lacks spin, not necessarily the photon. But, let's assume they are all white, and design out thought experiment (detectors) to better represent the conservation laws we do have information about. The same conservation law that require EPR correlations to begin with.

Okay, you know these things better than me, and I’m 'digesting' RQM. But, still it seems to me that there is one thing missing in the story about the marbles, and I’ll highlight the 'weak' part in the red:
Nonseparable, in the sense used in RQM and claimed for QM, is the same sense in which 10 red and 10 blue marbles are randomly mixed and placed equally in each of 2 boxes.

To my understanding, the elegance of Bell in investigating "spooky action at a distance", was to implement "randomness at a distance", and setting the final parameters for the experiment in separate light-cones, thus prohibiting any local influence.

To me it looks like you implement the randomness at the "local source", and then put the objects in the in "closed information box". Is this really consistent with Bell test experiments (BTE)...?

Note: If QM is an information theory, as RQM posits, it can't be a priori claimed this is reasonable analogy of how it works, as it provides 'information' that's by definition not available. RQM does explicitly posit the relational properties analogous the the relational red and blue properties above. So, like Bell's theorem, even if we assume RQM is perfectly valid in principle, it does not prove no FTL mechanism exists or isn't involved, only that they aren't required.
I’m clearly missing something in RQM. I agree that QM is an information theory, and we really can’t know what’s in the "box". BUT, we can measure differences in different BTE setups. If we use not entangled photons in BTE, we get a result that don’t correspond to the predictions of QM, and if we use entangle photons – we get correspondence with QM predictions. This must mean that something happens that cannot be explained with 'every-day-local-reality', even if we all agree that there’s no 'usable information' sent FTL.

ThomasT

May17-10, 12:38 PM

I have been quietly reading this for some time, and I agree. I don't ascribe to the RUTA or unusualname view, but I recognize them as scientific and plausible.You have a strange interpretation of scientific and plausible.

Zonde, ThomasT, you are selling your own crazed theories.Which indicates that you don't understand what either of us is saying. We're advocating certain approaches to different aspects of the EPR-Bell stuff.

Here's a link that explains what I'm saying better that I could:

http://arxiv.org/PS_cache/quant-ph/pdf/0001/0001112v3.pdf

my_wan

May17-10, 12:44 PM

To my understanding, the elegance of Bell in investigating "spooky action at a distance", was to implement "randomness at a distance", and setting the final parameters for the experiment in separate light-cones, thus prohibiting any local influence.
You have to consider it in historical context (short version). This is a very very important historical piece to understand. If you get this everything should conceptually click into place.

When the mechanics was introduced by Born in 1926, the probabilities were to be understood as fundamental, without cause. A year later at the Solvay Conference, Heisenberg and Born declared the quantum revolution was over, that the physics was essentially complete and final. This stoked the famous Bohr–Einstein debates in earnest. Einstein used the conservation of energy to obtain information about the interference process, now called the EPR paradox, which he said contradicted the principle of indeterminacy. Einstein never suggested that the EPR correlations didn't exist. Ironically people now often think EPR correlations proves Einstein wrong, when in fact his argument depended on the correlations being real. If EPR correlations weren't real then his argument that they violate indeterminacy is invalid, i.e., ridiculous.

It became the accepted wisdom that indeterminacy was real, and the randomness was fundamental, without cause. Jump ahead 40 odd years, and we get Bell, Aspect, etc., with unambiguous experimental confirmation of EPR. Now, since indeterminacy is by definition true and fundamental, it means Einstein was wrong, even though he correctly predicted EPR correlations to argue against indeterminacy. Thus there must be some kind of new effect (FTL) to keep both indeterminacy and EPR correlations, and maintain that Einstein was wrong with his correct prediction. It is a paradox only because we still maintain that indeterminacy is true at the most fundamental level of nature.

Meanwhile, the search for a local EPR mechanism became the standard by which a search for hvt's was conducted, only with indeterminacy as a fundamental property in spite of EPR being correctly predicted by Einstein to undermine indeterminacy as a "fundamental" property.

Now here's the caveat: If their exist a causal mechanism for indeterminacy, such that it is real, but not fundamental, then EPR correlations prove exactly what Einstein said they prove. It is only through the acceptance of indeterminacy as a "fundamental" property that extra FTL mechanisms are needed to save the fundamental character of indeterminacy.

To me it looks like you implement the randomness at the "local source", and then put the objects in the in "closed information box". Is this really consistent with Bell test experiments (BTE)...?
Yes I did implement randomness at the "local source", and you rightly want to know if this really is consistent with EPR correlations. Well that depends. I'll lay out exactly what that depends on in the most general case.

1) If indeterminacy is a truly fundamental property of 'actual reality': then "local source" is not consistent.
2) If indeterminacy has a causal mechanism in 'actual reality': then "local source" is consistent.
(And we don't know what 'actual reality' is at this time, or even if it's a meaningful claim.)

Ironically (again to make this very important point clear), people often think that for Einstein to be right the correlation experiments must fail, when in fact Einstein correctly predicted them with the expectation that they were real, not to prove EPR correlations didn't exist, but to prove that because they did exist indeterminacy had a more fundamental cause.

Your next paragraph is perfect to finish this argument with.

I’m clearly missing something in RQM. I agree that QM is an information theory, and we really can’t know what’s in the "box". BUT, we can measure differences in different BTE setups. If we use not entangled photons in BTE, we get a result that don’t correspond to the predictions of QM, and if we use entangle photons – we get correspondence with QM predictions. This must mean that something happens that cannot be explained with 'every-day-local-reality', even if we all agree that there’s no 'usable information' sent FTL.
Note the "local source" legitimacy requirements above call for "actual reality". Note that RQM turns QM into an "information theory". If it's a theory about the information we have about the reality, rather than a theory about the reality of nature it claims to be, then by definition we can't claim any part of it as a fundamental property of "actual reality", including indeterminacy.

There are further constraints EPR correlations place on such hvt's. That is that indeterminacy is very real, just not a fundamental causeless property of nature. The only realistic way I know to pull that off is with ensembles of many properties, like the thermodynamic model I referenced. Ironically this means that constraints on the causal mechanism required to explain indeterminacy must itself be indeterminate, at least on empirical, not fundamental, grounds. More or less analogous to classical thermodynamic properties.

What I find strange here is people searching realistic causal mechanisms (FTL or not) when the very notion of a causal mechanism subverts the justification for needing a causal mechanism to explain EPR. Of course for FTL I guess it could be assumed EPR needs a causal mechanism, but indeterminacy doesn't. But what about the question of whether the wavefunction itself is real. That would directly imply a causal mechanism for indeterminacy, unambiguously subverting the need for a FTL causal mechanism for EPR correlations.

ThomasT

May17-10, 12:45 PM

You got the analogy backwards. This is exactly what happened in the 30 years from 1935 to 1965. A common view was that local realism was compatible with the predictions of QM. Bell put that to an end. At least mostly. :smile:My understanding was that qm and hidden variables were assumed to be incompatible due to von Neumann's influence. Bell pointed out the flaw in von Neumann's proof 30 years after Greta Hermann did (but noboday paid any attention to her). This is in one of the Mermin papers I referenced.

Anyway, I have personally spent plenty of time looking for cracks in Bell. Thousands of others have too. So you are really selling the physics community short, as well as repeating the same unsubstantiated claims.What I'm talking about isn't a 'crack in Bell'. In my opinion, he really has ruled out lhv theories. You just don't get yet how that can be and still not need nonlocality or ftl propagations. The paper I linked to by Unnikrishnan in an earlier post should help clarify where I'm coming from.

DrChinese

May17-10, 12:56 PM

My understanding was that qm and hidden variables were assumed to be incompatible due to von Neumann's influence.

That was not completely accepted, although it was certainly influential. Einstein would - in my opinion - have accepted the Bell proof as conclusive had he lived to see it. But he did not accept von Neumann's.

IcedEcliptic

May17-10, 12:57 PM

You have a strange interpretation of scientific and plausible.

Which indicates that you don't understand what either of us is saying. We're advocating certain approaches to different aspects of the EPR-Bell stuff.

Here's a link that explains what I'm saying better that I could:

http://arxiv.org/PS_cache/quant-ph/pdf/0001/0001112v3.pdf

I understand, that you are both borderline crackpots.

DrChinese

May17-10, 01:11 PM

Here's a link that explains what I'm saying better that I could:

http://arxiv.org/PS_cache/quant-ph/pdf/0001/0001112v3.pdf

And this is almost like referencing yourself. Basically, the article says: Entanglement is local realistic, proving that entanglement is local realistic.

It isn't that simple. At least De Raedt offered up a formula that leads to a local realistic dataset. Where is the same for this? As I keep pointing out, there is a simple test for any candidate LHV and this one FAILS miserably. Again.

IcedEcliptic

May17-10, 01:18 PM

I thought crackpots were dealt with on this site, I am satisfied that Zonde and ThomasT are that, and offering personal theories.

DevilsAvocado

May17-10, 06:24 PM

If you get this everything should conceptually click into place.

WOW+WOW+WOW+WOW+WOW!!!

This is the most intelligent and interesting post I’ve ever read on PF!! ABSOLUTELY MIND-BLOWING!!

Not only a "click", I almost broke my neck, jumping up & down in my chair!!! :biggrin:

...I feel dizzy, exhausted...

Now here's the caveat: If their exist a causal mechanism for indeterminacy, such that it is real, but not fundamental, then EPR correlations prove exactly what Einstein said they prove. It is only through the acceptance of indeterminacy as a "fundamental" property that extra FTL mechanisms are needed to save the fundamental character of indeterminacy.

I get this, and it’s absolutely fantastic and beautiful!!! There might be a causal mechanism to create the non-causal mechanism we (so far) believe is "ground zero" in QM. And that causal mechanism must look like it’s indeterminate, even if it’s not on fundamental grounds. WOW!!

I always loved Einstein, but at the same time I always liked the randomness of the universe – and my free will. It looks like you given me a wonderful solution to this dilemma. Thanks!

(I guess all this is strongly related to "you-know-what"...? :wink:)

What I find strange here is people searching realistic causal mechanisms (FTL or not) when the very notion of a causal mechanism subverts the justification for needing a causal mechanism to explain EPR. Of course for FTL I guess it could be assumed EPR needs a causal mechanism, but indeterminacy doesn't. But what about the question of whether the wavefunction itself is real. That would directly imply a causal mechanism for indeterminacy, unambiguously subverting the need for a FTL causal mechanism for EPR correlations.

This is very good: We are looking for causal "FTL" mechanism to explain the non-causal mechanism (QM probabilities) in EPR/BTE – where probabilities are the actual proof for EPR/BTE being a true paradox!? That’s a REAL paradox!!

To sum up: If "FTL" is not true, then there must be local casual explanation for EPR/BTE, and QM is incomplete (anyway).

(But... wait a minute... if QM and HUP are incomplete? Wouldn’t that mean we could send FTL messages with Quantum teleportation!? Thus meaning FTL is true!?!? :uhh:)

I have shown this video before, but it’s very nice wind up for this wonderful news, where Alain Aspect talks about EPR, Albert Einstein & Niels Bohr and the incompleteness of QM. And when Alain Aspect, in the end of the movie (7:50), says – "You cannot get the wool information of system!" – I suspect that one word could be slightly 'wrong'... :biggrin:

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/m8P--jFe3vM&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/m8P--jFe3vM&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

THANKS!

ThomasT

May17-10, 06:41 PM

I understand, that you are both borderline crackpots.

I thought crackpots were dealt with on this site, I am satisfied that Zonde and ThomasT are that, and offering personal theories.Zonde is arguing that the fair sampling loophole has not been sufficiently closed, which has been an accepted argument, based on accepted scientific methodology, for years. So, he's certainly not being a crackpot. Even though I think that what I'm focusing on sort of moots any loophole argument.

If you don't understand what Zonde's saying, then I wouldn't expect that you would understand what I'm saying either. Read Unnikrishnan's paper that I linked to. Pay attention to the part about an internal nondynamical phase variable imparted at emission.

If you think it's crackpotty to think that correlations between counter-propagating photons emitted during the same atomic transition could possibly be due to their being emitted during the same atomic transition, then, as I mentioned in a previous post, you have a strange interpretation of scientific and plausible.

ThomasT

May17-10, 06:45 PM

And this is almost like referencing yourself. Basically, the article says: Entanglement is local realistic, proving that entanglement is local realistic.

It isn't that simple. At least De Raedt offered up a formula that leads to a local realistic dataset. Where is the same for this? As I keep pointing out, there is a simple test for any candidate LHV and this one FAILS miserably. Again.I think you might have missed the point. Unnikrishnan reproduces the qm predictions with an explicitly local model. Afaik, his result hasn't been refuted.

DrChinese

May17-10, 06:59 PM

I think you might have missed the point. Unnikrishnan reproduces the qm predictions with an explicitly local model. Afaik, his result hasn't been refuted.

I just did. You cannot simply SAY it is local realistic. You must demonstrate such. Obviously, this one fails. Otherwise, we would be treated to the solution. You MUST be able to generate a dataset which is realistic.

I am not going to waste my time trying to figure out this gibberish. If you want to use his formula to present a valid set of data, I will look at it. BUT QUIT SAYING IT WITHOUT SHOWING IT!!!!!!!!!!!!

The entire point of Bell is that he cannot follow through on his claims. I can claim 1=2 too. So what? I can even "prove" it! So please take a minute to understand, we don't want an absurd claim when a dataset can do the trick. Remember: it must have answers for 0/120/240!

DevilsAvocado

May17-10, 07:04 PM

DrC, I would love to hear your view on my_wan's "news" in post #359 (http://www.physicsforums.com/showpost.php?p=2721095&postcount=359).

my_wan

May17-10, 08:35 PM

(But... wait a minute... if QM and HUP are incomplete? Wouldn’t that mean we could send FTL messages with Quantum teleportation!? Thus meaning FTL is true!?!? :uhh:)

No, because if indeterminacy is not fundamental, then the information producing the correlation can simply be carried by the particles from the original interaction, like the marble analogy. Only the mechanism that carries it must be indeterminate, but not fundamentally so, i.e., a relational ensemble of real (though observer characterized) states. A rabbit is defined by an ensemble of states, such that no two rabbits are precisely the same, or even precisely the same moment to moment, yet they all carry the property "rabbit" wherever they go. Unless they interact with an ensemble with the property called "wolf".

The issue of completeness also has some caveats. If you have a basic computer, and a theory that provides you with the output of every possible input, would that be a complete theory of that computer? In fact it would, even if you had no idea what or how that computer did what it did, or even if there was a computer there. Your "complete" I/O theory would then be an "information theory", not a physical theory. Like RQM defines QM to be, and justifiably labels it complete in that context. The term "complete" carries an entirely different status in that situation, than what is assumed by Einstein realism, which needs to know every part and operation of the physical computer to be labeled complete. The search for hvt's entails finding and dissecting that computer, whether FTL mechanisms are involved or not.

IcedEcliptic

May17-10, 08:41 PM

Zonde is arguing that the fair sampling loophole has not been sufficiently closed, which has been an accepted argument, based on accepted scientific methodology, for years. So, he's certainly not being a crackpot. Even though I think that what I'm focusing on sort of moots any loophole argument.

If you don't understand what Zonde's saying, then I wouldn't expect that you would understand what I'm saying either. Read Unnikrishnan's paper that I linked to. Pay attention to the part about an internal nondynamical phase variable imparted at emission.

If you think it's crackpotty to think that correlations between counter-propagating photons emitted during the same atomic transition could possibly be due to their being emitted during the same atomic transition, then, as I mentioned in a previous post, you have a strange interpretation of scientific and plausible.

I've read that paper, and I believe that Dr. Chinese summed up that tidibt quite well. The issue is not that the formalism if QM is not untenable in some ways, but rather that you are arguing for a loophole that I, along with many others believe has been utterly disprove as a factor. You both argue against something, and grasp at straws to do so, but really your pages of arguments boil down to not liking SQM, and not having a superior theory in its place.

The paper is like your arguments which Dr. Chinese continues to rip to confetti; it is scattered, distracting, and fundamentally lacking in substance. Its only strength is that you have yet to state enough of your position to refute it on purely scientific grounds, but that is yet another weakness. You go on and on about a non-existent loophole, and Zonde has ideas about Malus' Law that are between laughable and upsetting.

Your papers are crocks, you have pages of nonsense and rhetoric, but you continue your circular retreat, and in theory you will keep this up until a mentor finally accepts that you are a genuine crackpot and not just misguided.

my_wan

May18-10, 02:11 AM

That was not completely accepted, although it was certainly influential. Einstein would - in my opinion - have accepted the Bell proof as conclusive had he lived to see it. But he did not accept von Neumann's.Not sure how you can support that when in fact Einstein's argument required EPR correlations to be real (Bell's inequalities to be violated) as his justification (now empirical) to claim indeterminacy wasn't "fundamental". If indeterminacy has a cause, not fundamental, then that causal mechanism can in principle carry the relevant correlation information with the particle from the time the correlation was created. If indeterminacy is fundamental, without cause, then this is not possible and a FTL mechanism is required for EPR correlations. But if indeterminacy is acausal, why can't correlations be acausal?

Once you allow quantum randomness to have a causal mechanism of any sort, then this same mechanism, in principle, allows correlation information to be carried by the particle from the initial interaction. It's ONLY the lack of a causal mechanism of indeterminacy that makes EPR weird. I don't get why that's so difficult.

No, Einstein most certainly would not have accepted Bell proof as a FTL mechanism, he would have considered it proof of his original claim that indeterminacy has a "causal" mechanism, which carries the correlation information from the initial interaction.

my_wan

May18-10, 05:09 AM

Here is a link to the original EPR paper:
http://www.phys.uu.nl/~stiefelh/epr_latex.pdf

Take special note of the definition of reality. It specifically stated that a comprehensive definition was unnecessary, and what is provided is merely sufficient for the needed purposes, repeatedly. Sounds like my writing, :grumpy: and notes that many other ways exist to recognize reality. The point here is that narrowing in on the one definition provided isn't a valid rebuttal (hence the Neumann rejection), because it was merely chosen as "sufficient" as one way of recognizing reality relevant to the EPR paper argument.

Now the key sentence:[...] we arrive at the conclusion that two physical quantities, with non-commuting operators, can have simultaneous reality.Why did they come to this conclusion?
Because EPR correlations are REAL.
Because Bell's inequalities are VIOLATED.
I don't think, in their wildest imagination, they considered that future generations would actually call an empirically verified prediction a failure.

Now look at the definition given for a complete theory:Every element of physical reality must have a counterpart of physical theory.
Thus the very act of postulating a FTL "mechanism" justifies the conclusion of the original EPR paper , due to the above correct prediction:
We are thus forced to conclude that the quantum-mechanical description of physical reality given by the wavefunction is not complete.
Thus either FTL mechanisms or local hidden variables fully justifies the claims of the paper, only a rejection of the paper itself is required to justify FTL mechanisms.

Now to reiterate "completeness". RQM defines QM as an "information theory". For an information theory to be "complete" does not require that every physical element that defines that information be defined. The definition provided by the EPR paper specifically extended "completeness" to not only include complete information, but also a physical specification of what defines that information. Thus both sides are arguing "completeness" while rejecting that their are two sets of definitions in use.

In no way, shape, or form did Einstein ever reject the validity of any prediction of QM whatsoever. He was an integral part of its development till it was declared complete.

DrChinese

May18-10, 08:50 AM

Not sure how you can support that when in fact Einstein's argument required EPR correlations to be real (Bell's inequalities to be violated) as his justification (now empirical) to claim indeterminacy wasn't "fundamental". If indeterminacy has a cause, not fundamental, then that causal mechanism can in principle carry the relevant correlation information with the particle from the time the correlation was created. If indeterminacy is fundamental, without cause, then this is not possible and a FTL mechanism is required for EPR correlations. But if indeterminacy is acausal, why can't correlations be acausal?

Once you allow quantum randomness to have a causal mechanism of any sort, then this same mechanism, in principle, allows correlation information to be carried by the particle from the initial interaction. It's ONLY the lack of a causal mechanism of indeterminacy that makes EPR weird. I don't get why that's so difficult.

No, Einstein most certainly would not have accepted Bell proof as a FTL mechanism, he would have considered it proof of his original claim that indeterminacy has a "causal" mechanism, which carries the correlation information from the initial interaction.

Well, there are some differences in our views of the historical record. But that is really not surprising, it sorta depends on how you read them and in which order.

When you say "EPR correlations", I assume you mean the so called perfect correlations. Yes, EPR assumes those. There is an element of reality for all angle settings where Alice and Bob pick the same settings. So we agree about that. Einstein accepted this and assumed - reasonably for the time - that a locally causal theory could eventually replace/augment QM at some point in the future.

But Einstein obviously could never have known about Bell inequalities... they weren't discovered until almost 10 years after his death. That changed things dramatically, as Einstein's hopes were no longer feasible. I easily believe that Einstein would have accepted the Bell result as irrefutable. But would he have abandoned locality over realism (or vice versa)? I can't say.

DevilsAvocado

May18-10, 11:30 AM

... No, Einstein most certainly would not have accepted Bell proof as a FTL mechanism, he would have considered it proof of his original claim that indeterminacy has a "causal" mechanism, which carries the correlation information from the initial interaction.

I agree. The whole EPR question was if QM could be considered incomplete, in need of LHV or FTL. And if we today have proven that Einstein was right (QM needs LHV or FTL), then Einstein would of course be an advocate of finding a local mechanism to explain the paradox. I don’t think he would have started the research claiming – Well, I was right about EPR and the incompleteness of QM, and that also sadly proved GR/SR being totally wrong, in the proved FTL mechanism... Let’s start from scratch!! :biggrin:

DevilsAvocado

May18-10, 12:11 PM

No, because if indeterminacy is not fundamental, then the information producing the correlation can simply be carried by the particles from the original interaction, like the marble analogy. Only the mechanism that carries it must be indeterminate, but not fundamentally so, i.e., a relational ensemble of real (though observer characterized) states. ...

I understand this, almost... the 'thing' that looks to us as a FTL mechanism, cannot be 'exposed' in its underlying determinism...?

Why I asked was because in the video in post #365 (http://www.physicsforums.com/showpost.php?p=2721494&postcount=365) Anton Zeilinger talks about Quantum teleportation, and the reason why we can’t "beam" Alice over to Bob, is because HUP makes it impossible to measure Alice exactly, without destroying her (and then the joke about the "Heisenberg compensator" that "works very well, thank you").

But I have another (hopefully) tricky question for you:

Suppose we send 100 entangled photons towards the polarizer’s, and there is no FTL mechanism, all is handled by an 'underlying relational local ensemble' at the source.

What happen and how is this handled if we for example have one year between every entangled pair? Is there a "Global RAM" that 'memorizes' the statistics to be consistent with predictions of QM??

DrChinese

May18-10, 01:56 PM

1. Here is a link to the original EPR paper:
http://www.phys.uu.nl/~stiefelh/epr_latex.pdf

2. ... I don't think, in their wildest imagination, they considered that future generations would actually call an empirically verified prediction a failure.

3. In no way, shape, or form did Einstein ever reject the validity of any prediction of QM whatsoever. He was an integral part of its development till it was declared complete.

1. Waa, my own site is still down, which also contains this paper. SO thanks for posting a link.

2. Oh, but they were quite wrong on this key point. Per their conclusion:

"One could object to this conclusion on the
grounds that our criterion of reality is not suf-
ficiently restrictive. Indeed, one would not ar-
rive at our conclusion if one insisted that two
or more physical quantities can be regarded
as simultaneous elements of reality only when
they can be simultaneously measured or pre-
dicted. On this point of view, since either one
or the other, but not both simultaneously, of
the quantities P and Q can be predicted, they
are not simultaneously real. This makes the
reality of P and Q depend upon the process
of measurement carried out on the first system
in any way. No reasonable definition of reality
could be expected to permit this.

While we have thus shown that the wave
function does not provide a complete descrip-
tion of the physical reality, we left open the
question of whether or not such a description
exists. We believe, however, that such a theory
is possible."

Note how they say: no reasonable definition of reality will allow this! They absolutely did not see that P & Q are NOT simultaneously real (unless of course, there are FTL effects). Further, they believed that a more complete description of the system is possible! We now know that is not true. At least, not as EPR envisioned.

3. I would agree that Einstein did not reject the predictions of QM.

DevilsAvocado

May18-10, 05:10 PM

?:bugeye:? This is confusing... even if it never is mentioned in words in the paper, when EPR talks about "P and Q" they are talking about Spin(p,q), right?? Or to be precise, simultaneously Vertical + Horizontal Spin in the same particle, right??

If this is correct, then what they are saying is:

1) The quantum-mechanical description of reality given by the wave function is not complete *OR*

2) When the operators corresponding to two physical quantities do not commute the two quantities cannot have simultaneous reality. Starting then with the assumption that the wave function does give a complete description of the physical reality, we arrived at the conclusion that two physical quantities, with non-cummuting operators, can have simultaneous reality.

Meaning: If we measure V spin at Alice we also make V spin at Bob real (entanglement). But then we can also measure H spin at Bob, but quantities that do not commute cannot be simultaneous real according to QM = QM description of reality given by the wave function is not complete!

Or did I miss something (again)??

Anyone interested in commuting, sorry communicating, are welcome.

DrChinese

May18-10, 06:02 PM

[QUOTE=DevilsAvocado;2722903]?:bugeye:? This is confusing... even if it never is mentioned in words in the paper, when EPR talks about "P and Q" they are talking about Spin(p,q), right?? Or to be precise, simultaneously Vertical + Horizontal Spin in the same particle, right??

If this is correct, then what they are saying is:

1) The quantum-mechanical description of reality given by the wave function is not complete *OR*

2) When the operators corresponding to two physical quantities do not commute the two quantities cannot have simultaneous reality. Starting then with the assumption that the wave function does give a complete description of the physical reality, we arrived at the conclusion that two physical quantities, with non-cummuting operators, can have simultaneous reality.
QUOTE]

Could be P and Q (momentum and position), or could be non-commuting spins. I think it is a lot easier to talk about spin because then there is no confusion of the purity of their states (i.e. they are on a completely equal basis with each other, and each can take on a random value of either + or -).

An electron has 3 spins: x, y and z.

Now, keep in mind that they acknowledged that if QM is complete, there cannot be simultaneous independent reality of P & Q. On that I agree with EPR. The part I disagree with (as do most) is that it is an unreasonable to deny the simultaneous reality of P & Q. It is that last leap which led to their error.

my_wan

May19-10, 02:29 AM

Nice, you called me out on the right issues, but made bad assumptions about my position.

Well, there are some differences in our views of the historical record. But that is really not surprising, it sorta depends on how you read them and in which order.
Yes, it was a nutshell history, and I did short change the significant contributions Bell's inequalities made with respect to realism. In my latest post I made it sound 'as if' the EPR correlations of the original paper are equivalent to Bell's inequalities, and this is very far from true. The fact is Bell's inequalities make fine distinctions in the character of some classes of causal mechanisms undreamed of in the original EPR paper, which merely chose a simple definition as "sufficient" for the simple case of existential correlations. The case for Einstein being wrong is actually predicated on a stronger argument made by Bell's theorem, which in fact rules out the simple operational definition of of reality used in the paper. The EPR did repeatedly note this, and referred to this definition this way: "Regarded not as necessary, but merely as sufficient, condition of reality, this criterion is in agreement with classical as well as quantum-mechanical ideas of reality." The underlined left a door open here that Bell's theorem has yet to close. The door that I started this debate with.

When you say "EPR correlations", I assume you mean the so called perfect correlations. Yes, EPR assumes those. There is an element of reality for all angle settings where Alice and Bob pick the same settings. So we agree about that. Einstein accepted this and assumed - reasonably for the time - that a locally causal theory could eventually replace/augment QM at some point in the future.

Yes, I spoke in terms of perfect correlations only in the last few posts. I can't specifically object on the term "element of reality", as it doesn't define itself. So up next I'll reiterate exactly what Bell's theorem assumes and the issue with that.

But Einstein obviously could never have known about Bell inequalities... they weren't discovered until almost 10 years after his death. That changed things dramatically, as Einstein's hopes were no longer feasible. I easily believe that Einstein would have accepted the Bell result as irrefutable. But would he have abandoned locality over realism (or vice versa)? I can't say.
True, Einstein couldn't know, but clearly the equivocation on the definition of reality in EPR, and later the rejection of Neumann's proof, showed an understanding of the issues in drawing a linear relation between ontic (perhaps unobservable) elements of nature and the variables they define. Neumann considered an ensemble K such that the subsets ki, kj, ..., should hold the properties of K, which they clearly don't. This is essentially the "preexisting property assumption" required by Bell's notion of reality. The same simplistic notion used in EPR, with equivocation. Bell was quiet clear that the inequality derivation itself didn't require any notion of realism at all. Question is, is this a "sufficient" case for realism in the general case, as it was in the more restricted argument in EPR? The answer is absolutely no. Bell merely ruled this simplistic class of intrinsic properties. Emergence is an ubiquitous phenomena in nature, making such linear assumptions unreasonable.

This paper goes over in some detail the limits of what Bell's theorem can say wrt realism.
Non-local Realistic Theories and the Scope of the Bell Theorem (http://arxiv.org/abs/0811.2862)
There simply is no a priori reason to assume ontic entities have preexisting properties independent of measurement in the classical or empirical sense. The fact is that models that take advantage of contextual/relational variables can successfully models correlation statistics. Within thermodynamics variances between intrinsic and extrinsic variables is a normal feature, which means non-commuting variables are to be expected. Conjugate variables have a very tight analog to these QM properties, which are only untenable when you assume measurables are preexisting properties. Preexisting properties also lead to the so called vacuum catastrophic, deepens the mystery of why the total energy of the Universe is apparently zero, virtual particles, etc.

None of this proves a realistic model is valid, local or otherwise. But to say the Bell's inequalities rules out locally realistic theories is simply not tenable. Yes Bell's results are irrefutable, it simply overreaching to say that ruling out naive linear relations between properties and things says much about realism at all. I see no reason to give up either locality or realism without a much better reason than an grossly overstated interpretation of Bell's theorem.

my_wan

May19-10, 03:43 AM

1. Waa, my own site is still down, which also contains this paper. SO thanks for posting a link.

2. Oh, but they were quite wrong on this key point. Per their conclusion:

"One could object to this conclusion on the
grounds that our criterion of reality is not suf-
ficiently restrictive. Indeed, one would not ar-
rive at our conclusion if one insisted that two
or more physical quantities can be regarded
as simultaneous elements of reality only when
they can be simultaneously measured or pre-
dicted. On this point of view, since either one
or the other, but not both simultaneously, of
the quantities P and Q can be predicted, they
are not simultaneously real. This makes the
reality of P and Q depend upon the process
of measurement carried out on the first system
in any way. No reasonable definition of reality
could be expected to permit this.

While we have thus shown that the wave
function does not provide a complete descrip-
tion of the physical reality, we left open the
question of whether or not such a description
exists. We believe, however, that such a theory
is possible."

Note how they say: no reasonable definition of reality will allow this! They absolutely did not see that P & Q are NOT simultaneously real (unless of course, there are FTL effects). Further, they believed that a more complete description of the system is possible! We now know that is not true. At least, not as EPR envisioned.

3. I would agree that Einstein did not reject the predictions of QM.
Yes, but this analysis is predicated on the 'not real' as defined by indeterminacy. What the paper was out to reject. Thus, to demonstrate what was defined there as "no reasonable definition of reality" requires the variables, I suppose are relational, to not be contained in a local ensemble, such that communication between the correlated pair is required for nonlocal realism. Yet to demonstrate that is the case via Bell's theorem requires the assumption that the measured properties of a single ensemble (particle) are innate properties of the subsets of that ensemble. It is the rejection of this assumption that allows local realistic models in accordance with Bell's inequalities.

Bell was genius is providing us with these constraints, and I prefer to use them as a map, rather than overgeneralize the impossibilities they provide. Thus we are at the same impasse, with properties of ensembles not innate to the subsets of that ensemble verses properties of particle pairs not innate to either particle alone, regardless of separation, as the defining difference of perspective.

So we have choice A and B:
A: Entangled particle pairs with individual properties not innate to either particle alone.
B: Particles are ensembles with properties not innate to the subsets of that ensemble.
Personally I think B is the most reasonable choice.

zonde

May19-10, 07:54 AM

True, Einstein couldn't know, but clearly the equivocation on the definition of reality in EPR, and later the rejection of Neumann's proof, showed an understanding of the issues in drawing a linear relation between ontic (perhaps unobservable) elements of nature and the variables they define. Neumann considered an ensemble K such that the subsets ki, kj, ..., should hold the properties of K, which they clearly don't. This is essentially the "preexisting property assumption" required by Bell's notion of reality. The same simplistic notion used in EPR, with equivocation. Bell was quiet clear that the inequality derivation itself didn't require any notion of realism at all. Question is, is this a "sufficient" case for realism in the general case, as it was in the more restricted argument in EPR? The answer is absolutely no. Bell merely ruled this simplistic class of intrinsic properties. Emergence is an ubiquitous phenomena in nature, making such linear assumptions unreasonable.
I would like to agree with this point and provide something along the line from more practical side.
There is so called "entanglement distillation" and it's description in wikipedia says:
"Entanglement distillation can in this way overcome the degenerative influence of noisy quantum channels by transforming previously shared less entangled pairs into a smaller number of maximally entangled pairs (Bell states)."
To me this seems very much like emergence.

IcedEcliptic

May19-10, 09:02 AM

I would like to agree with this point and provide something along the line from more practical side.
There is so called "entanglement distillation" and it's description in wikipedia says:
"Entanglement distillation can in this way overcome the degenerative influence of noisy quantum channels by transforming previously shared less entangled pairs into a smaller number of maximally entangled pairs (Bell states)."
To me this seems very much like emergence.

Only in the sense that the word used is the same.

DrChinese

May19-10, 09:21 AM

This paper goes over in some detail the limits of what Bell's theorem can say wrt realism.
Non-local Realistic Theories and the Scope of the Bell Theorem (http://arxiv.org/abs/0811.2862)
There simply is no a priori reason to assume ontic entities have preexisting properties independent of measurement in the classical or empirical sense. The fact is that models that take advantage of contextual/relational variables can successfully models correlation statistics. Within thermodynamics variances between intrinsic and extrinsic variables is a normal feature, which means non-commuting variables are to be expected. Conjugate variables have a very tight analog to these QM properties, which are only untenable when you assume measurables are preexisting properties. Preexisting properties also lead to the so called vacuum catastrophic, deepens the mystery of why the total energy of the Universe is apparently zero, virtual particles, etc.

None of this proves a realistic model is valid, local or otherwise. But to say the Bell's inequalities rules out locally realistic theories is simply not tenable. Yes Bell's results are irrefutable, it simply overreaching to say that ruling out naive linear relations between properties and things says much about realism at all. I see no reason to give up either locality or realism without a much better reason than an grossly overstated interpretation of Bell's theorem.

I am not impressed by Laudisa, I am loosely familiar with his work as I scan almost every local realistic paper going into the arxiv. And I must say I am rather surprised by your position, it does not seem to follow from your prior statements. But I admit I still may not follow your position as there are some apparent contradictions (which I am sure are not actual contradictions). :smile:

1. Using Bell as a map (which I think is proper): do you think local realistic theories can yield predicitions consistent with QM?

2. How is the Bell generally acceptede conclusion "grossly overstated"? I mean, after decades of effort there is not ONE single local realistic candidate theory to consider. Every one can, thanks to Bell, be batted out of consideration. You must have seen how the work of Hess, Santos, and numerous others has been systematically dismantled. Not bad for being overstated: QM, 100; LR,0.

3. You say "contextual/relational variables can successfully models correlation statistics". To me, a contextual/relational model is not observer independent. Therefore, it is not realistic. So these sound like the words of someone who in fact denies realism. So are you in that camp or not?

my_wan

May19-10, 03:01 PM

I am not impressed by Laudisa, I am loosely familiar with his work as I scan almost every local realistic paper going into the arxiv. And I must say I am rather surprised by your position, it does not seem to follow from your prior statements. But I admit I still may not follow your position as there are some apparent contradictions (which I am sure are not actual contradictions). :smile: Laudisa does ramble a lot. :rofl:
I also think he overstates the certainty of validity of local models, which object to on the same grounds I object to certainty in ruling local models in general out. It seems your question #3 below contains the issue creating the apparent contradiction. I'll go though the questions.

1. Using Bell as a map (which I think is proper): do you think local realistic theories can yield predicitions consistent with QM?In principle yes, whether cogency can actually pan out for the standard model I can't say. I was recently challenged by one of my favorite skeptics to write a computer program that mimicked EPR correlation statistics. I found this that claims to have done it (haven't looked that close yet):
http://msc.phys.rug.nl/pdf/athens06-deraedt1.pdf
I was considering a variation of an encryption scheme I once wrote, based on some (now defunct) notions of cross frame information embedding. Actually with FTL models I might reconsider a limited version of that. It embedded an encrypted message in a fake encrypted message. Anyway I'm considering these quasirandom sequences and what rules might be needed to mimic detector setting choices. Interesting problem anyway.

2. How is the Bell generally acceptede conclusion "grossly overstated"? I mean, after decades of effort there is not ONE single local realistic candidate theory to consider. Every one can, thanks to Bell, be batted out of consideration. You must have seen how the work of Hess, Santos, and numerous others has been systematically dismantled. Not bad for being overstated: QM, 100; LR,0.I would refer to anything that is stated as 'proof' when it fails to rule out an entire class of possible exceptions grossly overstated. I'll get to that class in your next question. Making a 'proof' claim requires more than just invalidating the special cases on the table. Admittedly it also rules out entire classes of lhv's. It also lend cogency to FTL considerations, but local toy models can and do mimic EPR statistics, including stochastic hidden variables. I can't object to the claim of relatively unlikely, but almost certainly is an overstatement of what has been demonstrated by Bell's Theorem.

3. You say "contextual/relational variables can successfully models correlation statistics". To me, a contextual/relational model is not observer independent. Therefore, it is not realistic. So these sound like the words of someone who in fact denies realism. So are you in that camp or not?I have a bit of confusion how you are defining contextual variables myself. Earlier I seen it referred to as measuring separate realities in this thread. That was a bit ambiguous considering MWI. Here you say the relational model is not observer independent, but fail to specify what it's independent of. There is a difference between a configuration space, and a variable which is dependent on the perspective in which that configuration space is measured. Thus the whole point of contextual variables is that they are not observer independent, but the reality of the configuration space is. Analogs to these types of variables everywhere, the most relevant of which are in GR. What follows is not a claim, but a demonstration of the issues involve in complaining that contextual variables are not observer independent.

Consider what a water wave means to a single water molecule. It's nothing more than a small momentary deflection, not even significant relative to the general random motion. Same thing for air molecules when I say "boo". What part of "boo" is contained in each air molecule? Is the sound "boo" a preexisting property of air molecules? Conjugate variables are common enough in classical physics. What properties are preexisting in this world is a good question, perhaps even the constants?

In GR we make a well justified operational distinction between mass and rest mass. In the general case mass is a contextual variable, but the mass is real. So how relevant is that distinction? Consider a particle in QFT: A particular excitation of a field. Ask what happens if the entire field was uniformly excited by this magnitude. We could assume the total vacuum energy density increases accordingly, but this reasoning lead us to the vacuum catastrophe, and I'd say a prediction 107 orders of magnitude off is trouble for that assumption. Then we have a zero total energy of the universe, GM_t^2/R = M_tc^2. This is pretty strong indication to me that the the entire universe, and everything we empirically measure about it, are purely contextual variables. Could it be that local field variances fully defines all empirical properties contextually, such that uniform absolute magnitudes of anything is meaningless, like gauge fields? This does not mean the configuration space that defined the variables isn't real, and almost certainly covariant. But trying to define reality solely in terms of the variables we measure wouldn't make much sense, in spite of the reality of covariant field variances.

As noted, I'm not trying to convince you that this is the way it is. Significant theoretical issues make this outline problematic. I'm merely trying to point out the issues in assuming that because contextual variables are not observer independent realism is out. Here I described a scenario where *all* variables are contextual, and still maintained realism. Everything you measure gets its metric from you, or some instrument, self referencing. You are a product of the very thing you are measuring, and not even space and time itself, the metric on which measurements are predicated, is non-contextual.

DrChinese

May19-10, 03:33 PM

In principle yes, whether cogency can actually pan out for the standard model I can't say. I was recently challenged by one of my favorite skeptics to write a computer program that mimicked EPR correlation statistics. I found this that claims to have done it (haven't looked that close yet):
http://msc.phys.rug.nl/pdf/athens06-deraedt1.pdf
I was considering a variation of an encryption scheme I once wrote, based on some (now defunct) notions of cross frame information embedding. Actually with FTL models I might reconsider a limited version of that. It embedded an encrypted message in a fake encrypted message. Anyway I'm considering these quasirandom sequences and what rules might be needed to mimic detector setting choices. Interesting problem anyway.

Not meaning to ignore the rest of your post, which I want to review in more detail.

However, I am a computer programmer by profession. I have performed extensive analysis of the De Raedt computer simulation you referenced. I obtained the line by line source code for their model, and have created a series of models that accurately mimic their code using Excel (since their stuff requires a lot of add-on software to run). Using Visual Basic, I create trial runs for a large number of iterations at various angles and graph them. This spreadsheet is available from my website and I will post the link (it was previously posted on another thread).

This shows that it is in fact possible to construct a "local realistic" algorithm that does not violate a Bell Inequality, but yields a subsample which does. Thus it does not reproduce the QM predictions for the full universe, but does for a so-call "unfair sample". It is a very interesting piece of work.

However, my spreadsheet goes on to show why the same model is fatally flawed. In fact, it shows why pretty much ANY similar model is also fatally flawed. As far as I know, this analysis is original although I am sure there are others who have figured this out as well. I don't think anyone else has actually programmed the problem area so as to demonstrate it using the same technique as the De Raedt model itself.

My point being that it is far easier to claim success for a model than to actually produce that success. I will gladly take on any local realistic model which, like the De Raedt model, offers a specific algorithm which is actually "local" and "realistic" (since we are talking computer simulation). I can assure you, there isn't likely to be a model which can withstand attack. All this because Bell is in fact a map.

And keep in mind that the De Raedt model does not purport to mimic the results of all QM in the first place - so technically it is not a local realistic candidate theory. It is really an attempt to demonstrate that Bell can be beat, but it does not actually accomplish that in the end.

ThomasT

May19-10, 03:43 PM

I am not going to waste my time trying to figure out this gibberish. If you want to use his formula to present a valid set of data, I will look at it. BUT QUIT SAYING IT WITHOUT SHOWING IT!!!!!!!!!!!!So, what are you saying? That Unnikrishnan's formulation doesn't reproduce the qm predictions. That's just silly. Read the paper.

If you're saying that his formulation shouldn't be interpreted as local realistic in the sense of EPR-Bell, then I agree with you.

But it is an explicitly local model which expresses the conceptual points I've been making.

The entire point of Bell is that he cannot follow through on his claims.His claim is that we don't need nonlocality to understand the correlations in terms of a local common cause. He's made an explicitly local model using a relational variable produced via emission process. And he correctly reproduces the qm predictions.

I agree with you that Bell put a stopper on explicitly local realistic models which, in effect, require the joint results to be caused by the variables which cause individual results. It's impossible to do that because the joint results are determined by a RELATIONSHIP between the counter-propagating disturbances which is NOT the same thing as the variables which determine the individual results.

ThomasT

May19-10, 03:43 PM

I've read that paper, and I believe that Dr. Chinese summed up that tidibt quite well.Unnikrishnan made an explicitly local model of entanglement that reproduces the qm results. I think that if you had read and understood the paper, then you would see how it relates to the conceptual points I've been trying to get across.

The issue is not that the formalism if QM is not untenable in some ways, but rather that you are arguing for a loophole that I, along with many others believe has been utterly disprove as a factor.I'm not arguing loophole(s). That's Zonde.

You both argue against something, and grasp at straws to do so, but really your pages of arguments boil down to not liking SQM, and not having a superior theory in its place.I'm not arguing for LHV models or against Bell. I'm arguing that we can understand entanglement correlations without resorting to nonlocality, or wierd alternate realities. I don't think you've been paying close enough attention to what's been said to label anyone in this discussion a crackpot.

The paper is like your arguments which Dr. Chinese continues to rip to confetti; it is scattered, distracting, and fundamentally lacking in substance. Its only strength is that you have yet to state enough of your position to refute it on purely scientific grounds, but that is yet another weakness. You go on and on about a non-existent loophole, and Zonde has ideas about Malus' Law that are between laughable and upsetting.Zonde is the loophole person. I'm the one who brought up the applicability of Malus Law to certain situations.

Your papers are crocks, you have pages of nonsense and rhetoric, but you continue your circular retreat, and in theory you will keep this up until a mentor finally accepts that you are a genuine crackpot and not just misguided.Are you calling Unnikrishnan a crackpot now?

DrChinese

May19-10, 03:51 PM

IcedEcliptic

May19-10, 03:52 PM

Here are the links to the Excel spreadsheet models I created around the De Raedt simulations:

DeRaedtComputerSimulation.EPRBwithPhotons.B.xls (http://www.drchinese.com/David/DeRaedtComputerSimulation.EPRBwithPhotons.B.xls)

To see the code I wrote, go into the Visual Basic editor.

You are very devout in your hobby, I respect this! Thanks for showing us the fruits of your labour.

DrChinese

May19-10, 03:59 PM

Unnikrishnan made an explicitly local model of entanglement that reproduces the qm results.

No he didn't. He simply claimed he did.

And I will call any local realist a "crackpot" who can't be bothered to generate a dataset which demonstrates the local realistic nature of their purported model. And I mean that in the nicest way. Why wouldn't someone generate the dataset? I mean, that would convince anyone that they have a solid model. So you have to wonder. So while I am not being literal about the crackpot designation, I am trying to say that an explanation should be forthcoming from the author if he wants to be taken seriously as to WHY there is no dataset.

De Raedt et al at least met this criteria. So my hat is off to them. Of course, I don't wear a hat in the first place, but I think you know what I mean.

DrChinese

May19-10, 04:00 PM

I will be glad to discuss their model and mine either in this thread or even better, in:

http://www.physicsforums.com/showthread.php?t=369286

IcedEcliptic

May19-10, 04:01 PM

Unnikrishnan made an explicitly local model of entanglement that reproduces the qm results. I think that if you had read and understood the paper, then you would see how it relates to the conceptual points I've been trying to get across.

I'm not arguing loophole(s). That's Zonde.

I'm not arguing for LHV models or against Bell. I'm arguing that we can understand entanglement correlations without resorting to nonlocality, or wierd alternate realities. I don't think you've been paying close enough attention to what's been said to label anyone in this discussion a crackpot.

Zonde is the loophole person. I'm the one who brought up the applicability of Malus Law to certain situations.

Are you calling Unnikrishnan a crackpot now?

Show me your data or go away. Dr. Chinese has already addressed the rest.

DrChinese

May19-10, 04:12 PM

I have a bit of confusion how you are defining contextual variables myself. Earlier I seen it referred to as measuring separate realities in this thread. That was a bit ambiguous considering MWI. Here you say the relational model is not observer independent, but fail to specify what it's independent of. There is a difference between a configuration space, and a variable which is dependent on the perspective in which that configuration space is measured. Thus the whole point of contextual variables is that they are not observer independent, but the reality of the configuration space is. Analogs to these types of variables everywhere, the most relevant of which are in GR. What follows is not a claim, but a demonstration of the issues involve in complaining that contextual variables are not observer independent.

Consider what a water wave means to a single water molecule. It's nothing more than a small momentary deflection, not even significant relative to the general random motion. Same thing for air molecules when I say "boo". What part of "boo" is contained in each air molecule? Is the sound "boo" a preexisting property of air molecules? Conjugate variables are common enough in classical physics. What properties are preexisting in this world is a good question, perhaps even the constants?

In GR we make a well justified operational distinction between mass and rest mass. In the general case mass is a contextual variable, but the mass is real. So how relevant is that distinction? Consider a particle in QFT: A particular excitation of a field. Ask what happens if the entire field was uniformly excited by this magnitude. We could assume the total vacuum energy density increases accordingly, but this reasoning lead us to the vacuum catastrophe, and I'd say a prediction 107 orders of magnitude off is trouble for that assumption. Then we have a zero total energy of the universe, GM_t^2/R = M_tc^2. This is pretty strong indication to me that the the entire universe, and everything we empirically measure about it, are purely contextual variables. Could it be that local field variances fully defines all empirical properties contextually, such that uniform absolute magnitudes of anything is meaningless, like gauge fields? This does not mean the configuration space that defined the variables isn't real, and almost certainly covariant. But trying to define reality solely in terms of the variables we measure wouldn't make much sense, in spite of the reality of covariant field variances.

As noted, I'm not trying to convince you that this is the way it is. Significant theoretical issues make this outline problematic. I'm merely trying to point out the issues in assuming that because contextual variables are not observer independent realism is out. Here I described a scenario where *all* variables are contextual, and still maintained realism. Everything you measure gets its metric from you, or some instrument, self referencing. You are a product of the very thing you are measuring, and not even space and time itself, the metric on which measurements are predicated, is non-contextual.

EPR denied we live in a world in which Alice changes spacelike separated Bob's reality. So if your theory allows Alice's reality to change Bob's (or vice versa), I consider it to be context dependent. And that would be fully consistent with the Bell result.

Now, a serious problem exists in any NON-contextual candidate theory because you must explain correlations for entangled particles at the same angles, while also explaining why unentangled particles are NOT correlated. You also have the Bell inequalities to contend with. So these are severe constraints which are not present in either contextual or nonlocal theories.

ThomasT

May19-10, 04:36 PM

No he didn't. He simply claimed he did.

And I will call any local realist a "crackpot" who can't be bothered to generate a dataset which demonstrates the local realistic nature of their purported model. And I mean that in the nicest way. Why wouldn't someone generate the dataset? I mean, that would convince anyone that they have a solid model. So you have to wonder. So while I am not being literal about the crackpot designation, I am trying to say that an explanation should be forthcoming from the author if he wants to be taken seriously as to WHY there is no dataset.

De Raedt et al at least met this criteria. So my hat is off to them. Of course, I don't wear a hat in the first place, but I think you know what I mean.Are you saying that Unnikrishnan's model isn't local (not local realist -- just local -- that's all I've been saying -- remember, I agree with you that local realistic models of entanglement are ruled out by Bell)? Are you saying that his model doesn't reproduce the qm expectation value and correlation function (from which you can calculate datasets for any angles)?

ThomasT

May19-10, 04:47 PM

Show me your data or go away. Dr. Chinese has already addressed the rest.What is a 'dataset' going to tell you that the expectation value and correlation function doesn't already??

DrChinese

May19-10, 04:49 PM

What is a 'dataset' going to tell you that the expectation value and correlation function doesn't already??

A lot! If there is a model, let's see it model!! Otherwise you are saying 1=2 and I can't be bothered showing my work. People can claim they have a secret formula, but that doesn't fly here.

DrChinese

May19-10, 04:51 PM

Are you saying that Unnikrishnan's model isn't local (not local realist -- just local -- that's all I've been saying -- remember, I agree with you that local realistic models of entanglement are ruled out by Bell)? Are you saying that his model doesn't reproduce the qm expectation value and correlation function (from which you can calculate datasets for any angles)?

You cannot create a dataset from the expectation values, no. Let's see it working. I don't know if it is local or realistic or both, all I know is the claims.

ThomasT

May19-10, 05:00 PM

A lot! If there is a model, let's see it model!! Otherwise you are saying 1=2 and I can't be bothered showing my work. People can claim they have a secret formula, but that doesn't fly here.I honestly don't understand what you're saying.

Are you saying that the qm expectation value and correlation function are wrong?

What is it that you want? For Unnikrishnan, or me, or somebody, to plug in some angular values to make a 'dataset'? Is that really necessary?

DrChinese

May19-10, 05:45 PM

I honestly don't understand what you're saying.

Are you saying that the qm expectation value and correlation function are wrong?

What is it that you want? For Unnikrishnan, or me, or somebody, to plug in some angular values to make a 'dataset'? Is that really necessary?

It is simple. If you have a model, you can general a dataset. Give me the values for 0/120/240 degrees for Alice and Bob, using the formula from the paper. If you think it is the same as QM, then fine, show me. P.S. QM does NOT NOT NOT say there is a realistic dataset.

I will then tear your dataset to shreds. Now, quit saying it is unnecessary when it is. I can say that I witnessed my son walking on water, but you would want to see it yourself. Well, here am I, saying I want to see it. Bell would too. :biggrin:

Just like 1 is not 2, a claim of equivalence is NOT equivalence.

DevilsAvocado

May19-10, 06:14 PM

Here is the link to the Excel spreadsheet models I created around the De Raedt simulations:

DeRaedtComputerSimulation.EPRBwithPhotons.B.xls (http://www.drchinese.com/David/DeRaedtComputerSimulation.EPRBwithPhotons.B.xls)

To see the code I wrote, go into the Visual Basic editor. Sheet A shows their model working correctly. Sheet B shows their model working incorrectly for a setup which matches their base assumptions.

DrC, I agree with IcedEcliptic, this is very impressive work for a "hobbyist"! Kudos and +11 on "my scale"!! :smile:

There’s a lot I want to comment in the last posts, but time is running out for today, but your code is so interesting I can’t wait:

I checked the VB code and saw that you are using VB’s pseudorandom number generator Rnd() (http://msdn.microsoft.com/en-us/library/f7s023d2.aspx), without running Randomize() (http://msdn.microsoft.com/en-us/library/8zedbtdt.aspx) (to get new a new seed value). Could this be an "issue" (since QM is true random)?

If you consider this an issue, there could be a solution in the RandomNumberGenerator Class (http://msdn.microsoft.com/en-us/library/system.security.cryptography.randomnumbergenerator .aspx) or the best solution online RANDOM.ORG (http://www.random.org/clients/) for automated clients (HTTP Interface).

Tomorrow I’ll be back to 'tackle' the rest, cheers!

IcedEcliptic

May19-10, 07:30 PM

What is a 'dataset' going to tell you that the expectation value and correlation function doesn't already??

I give up.

DevilsAvocado

May19-10, 08:21 PM

Time for cake! +10,000 views!! :biggrin:

http://upload.wikimedia.org/wikipedia/commons/thumb/4/4f/Birthday_cake.jpg/400px-Birthday_cake.jpg

DrChinese

May19-10, 10:37 PM

time for cake! +10,000 views!! :biggrin:

http://upload.wikimedia.org/wikipedia/commons/thumb/4/4f/birthday_cake.jpg/400px-birthday_cake.jpg

love it!

lisab

May19-10, 10:48 PM

Good to know there are so many folks following this great thread! I'm enjoying it very much.

IcedEcliptic

May20-10, 12:54 AM

Tasty looking cake! I assume the two pictures of it are entangled? If Dr. Chinese had photoshopped the candles to be out, in contrast to the "on" above, I would have died laughing.

DevilsAvocado

May20-10, 06:48 AM

Whoooooossssh
http://i47.tinypic.com/s6lsig.jpg

Glad you all liked it!

@IcedEcliptic, of course they are entangled! :grumpy: Now I will call 9-1-1! :rofl:

IcedEcliptic

May20-10, 07:09 AM

Whoooooossssh
http://i47.tinypic.com/s6lsig.jpg

Glad you all liked it!

@IcedEcliptic, of course they are entangled! :grumpy: Now I will call 9-1-1! :rofl:

Wigner's Cake. :biggrin:

DevilsAvocado

May20-10, 07:23 AM

Yup :biggrin:

DrChinese

May20-10, 07:47 AM

DrC, I agree with IcedEcliptic, this is very impressive work for a "hobbyist"! Kudos and +11 on "my scale"!! :smile:

There’s a lot I want to comment in the last posts, but time is running out for today, but your code is so interesting I can’t wait:

I checked the VB code and saw that you are using VB’s pseudorandom number generator Rnd() (http://msdn.microsoft.com/en-us/library/f7s023d2.aspx), without running Randomize() (http://msdn.microsoft.com/en-us/library/8zedbtdt.aspx) (to get new a new seed value). Could this be an "issue" (since QM is true random)?

If you consider this an issue, there could be a solution in the RandomNumberGenerator Class (http://msdn.microsoft.com/en-us/library/system.security.cryptography.randomnumbergenerator .aspx) or the best solution online RANDOM.ORG (http://www.random.org/clients/) for automated clients (HTTP Interface).

Tomorrow I’ll be back to 'tackle' the rest, cheers!

Yes, I know it is pseudo-random. After a while you will realize that it does not need to be "truly" random. It is just a simulation to get things moving on how everything *should* work in this area. However, it might be worth you adding that element to see how it changes things. Thanks for the reference by the way, I will check it out.

my_wan

May20-10, 08:11 AM

EPR denied we live in a world in which Alice changes spacelike separated Bob's reality. So if your theory allows Alice's reality to change Bob's (or vice versa), I consider it to be context dependent. And that would be fully consistent with the Bell result.
I'm still not sure how you can represent "context dependent" that way from what I described. It would be somewhat analogous to saying Alice changed the reality of spacelike separated Bob by accelerating, thus changing Bob's velocity non-locally.

Now, a serious problem exists in any NON-contextual candidate theory because you must explain correlations for entangled particles at the same angles, while also explaining why unentangled particles are NOT correlated. You also have the Bell inequalities to contend with. So these are severe constraints which are not present in either contextual or nonlocal theories.
If it's modeled contextually in the relativistic sense above, then "now" is simply "now" as defined the detector, with nothing else involved. Same way Alice changed Bob's velocity, by accelerating herself "now" as defined by Alice.

I understand the ease with modeling EPR correlation when the setting for one end always stays the same, and how that breaks to varying degrees under arbitrary detector settings. We operate on a reasonable assumption, with a random spin sequence of particles, single detector settings can't make a statistical difference. I'm going to call this assumption into question wrt detection sequence, not detection rates, even though the sequence appears random to us at any single detector.

Assumptions (I'll use spin only here):
1) Spin is a distinct "real" property, regardless of time dependence, relational character, etc.
2) By 1) spin has a distinctly "real" anti-correlation with its correlated pair.

Now, given the above assumptions, when a particle enters a detectors polarizer, the particle polarization relative to the detectors polarizer has a distinctly "real" physical meaning. Thus the empirical (apparently) random detection sequence is determined by this relative particle/polarizer angle. By 1), through nothing more than simple geometry, this provides information about the "real" polarization of its pair by 2). Likewise for the other particle. Thus, through simple geometry and the realness of spin defined by 1) and 2), a zero setting for the detectors is uniquely defined by the polarizer/spin angle, regardless of the experimenters knowledge or choice in how the detectors zero setting is chosen.

If the particle spin/polarizer angle has "real" physical meaning, arbitrary choices become moot, as that provides an reference to a unique angle inversely common to both particles. Thus a relation that provides for Bell's inequalities, where any one detector is predefined, is valid under arbitrary choices.

So now we can add 3) to our assumptions:
3) By 2) the relative spin to polarizer angle of a single detector uniquely identifies the polarization angle of both particles.

Now we obviously can't detect the relative angle between 'individual' particle spin and polarizer setting, but if spin is real it is there, and apparently affects detection sequence, though not overall detection rate. I can't say this is how it is but the information is there, without FTL. In fact, if this is true, it requires perfect determinacy to perfectly violate Bell's inequalities.

DevilsAvocado

May20-10, 08:50 AM

Yes, I know it is pseudo-random. After a while you will realize that it does not need to be "truly" random. It is just a simulation to get things moving on how everything *should* work in this area. However, it might be worth you adding that element to see how it changes things. Thanks for the reference by the way, I will check it out.

You are welcome.

I think simulation of EPR is very interesting. It would be great to have an open "EPR framework" with real-time simulations + graphs + automatic validation of BI, which would allow for input of 'new ideas' for immediate testing, with minimal coding. Maybe a project for the future... if possible...

my_wan

May20-10, 08:54 AM

DrChinese

May20-10, 09:03 AM

I need to polish up my last argument and better outline its consequences. Until that post I only viewed it in the context of more complex physical constructs, but distilled down it's easier to see the bare consequences.

In essence, when we say we have a choice of detector setting we are overgeneralizing. In fact, if the realism assumptions are valid, the particle entering the detector itself defines a unique zero setting via the particles "real" polarization. The experimenter can only choose an offset from that polarization, and not specifically the offset relative to the distant detector. A violation of Bell's inequalities, in this view, entails a unique and separate perfectly determined detection sequence for each detector offset relative the particle polarization. Likely quantized offsets to get such perfect experimental results. The inverse of this perfectly determined sequence can be repeated IIF the distant detector chooses the same offset relative to a distant, but perfectly anticorrelated particle. Not having prior knowledge of determinates, polarization, etc., we can only see it in the coincidences of a pair of otherwise random sequences.

OK, you are really going off the deep end now. :smile: (And I mean that in a nice way.)

Everything you are saying has been refuted a zillion times already. I can demonstrate it either by theory or by experiment, pick your poison. But first, like ThomasT, you will need to show me something! I can't refute NOTHING!!

Walk me through some examples. Provide me a dataset. If you want, I will make it easy and you can talk through the perfect (EPR) correlation cases first before moving on to the Bell cases (like 0/120/240 I always mention).

And by the way, I will make a little prediction: when we are done, I will have proven your example wrong. But you won't change your opinion because you will say that there is an example that proves you right, you just haven't found it yet.

So if you are going to follow this line, you can just say so now and save us both time. The question comes down to: are you asking or are you telling? Because I'm *telling* you that your thinking does NOT follow from the facts. I mean you might want to consider this little tidbit before you go much further: photons can be entangled that have NEVER existed within the same light cone. How do you propose to explain that? That certainly would have turned Einstein's head.

ajw1

May20-10, 11:14 AM

You are welcome.

I think simulation of EPR is very interesting. It would be great to have an open "EPR framework" with real-time simulations + graphs + automatic validation of BI, which would allow for input of 'new ideas' for immediate testing, with minimal coding. Maybe a project for the future... if possible...

For those acquainted with c-sharp, I have the same de Raedt simulation, but converted in an object oriented way (this allows a clear separation between the objects(particles and filters) used in the simulation).
But an open framework should probably be started in something like Maxima (http://maxima.sourceforge.net/).

DrChinese

May20-10, 01:12 PM

For those acquainted with c-sharp, I have the same de Raedt simulation, but converted in an object oriented way (this allows a clear separation between the objects(particles and filters) used in the simulation).

Yes, it still takes a little thought for the coder. I wanted to have something that clearly related to the original De Raedt model, so that there would be little question that my program did the job.

The issue is to make sure that there is nothing happening in the code that: a) has the detectors considered when the particles are prepared initially; or b) has particle 1/detector 1 mixed with particle 2/detector 2 in any way.

I know you are aware of this, I am saying this for the benefit of others who may be reading.

my_wan

May20-10, 02:11 PM

I see your site is back up DrC. :smile: I'll go over it soon.

OK, you are really going off the deep end now. (And I mean that in a nice way.)

Everything you are saying has been refuted a zillion times already. I can demonstrate it either by theory or by experiment, pick your poison. But first, like ThomasT, you will need to show me something! I can't refute NOTHING!!

Walk me through some examples. Provide me a dataset. If you want, I will make it easy and you can talk through the perfect (EPR) correlation cases first before moving on to the Bell cases (like 0/120/240 I always mention).

And by the way, I will make a little prediction: when we are done, I will have proven your example wrong. But you won't change your opinion because you will say that there is an example that proves you right, you just haven't found it yet.

So if you are going to follow this line, you can just say so now and save us both time. The question comes down to: are you asking or are you telling? Because I'm *telling* you that your thinking does NOT follow from the facts. I mean you might want to consider this little tidbit before you go much further: photons can be entangled that have NEVER existed within the same light cone. How do you propose to explain that? That certainly would have turned Einstein's head.
Ok, you may have a point, but I'd like to see it. I hope you deliver, I'm arguing in the hopes of learning something new. I have a preference for experiment in empirical matters but without ignoring theory, as theory is what is at issue here. As for whether I'm asking or telling: Neither. I'm taking a position to be debated to sharpen the articulation of the controversial points. The example I'll go through is from 0 to 45, and explain how counterfactual reasoning can be interpreted in those discrepancies. In particular, when you say on your website:
Yet according to EPR, an element of reality exists independent of the act of observation. I.E. all elements of reality have definite values at all times, EVEN IF WE DON'T KNOW THEIR VALUES.
When you say, A i.e. B, I agree with A but will argue B implies properties that don't necessarily follow from A. I think it was the above interpretation you placed on the "realism" I used in my prior post.

Consider the following detection rates:
00 = 1
50 = 0.985
100 = 0.940
150 = 0.867
200 = 0.767
250 = 0.643
300 = 0.5
350 = 0.342
400 = 0.174
450 = 0
This pattern inversely after every 45 degrees.

To show the discrepancy with realism as defined, let's consider a set of string detections where any common setting of detector pairs matches this (rounded). [0] is a 'coincidence' non-detection and [1] is a 'coincidence' detection.
00 = [1111111111] (100% coincidences)
50 = [1111111111]
100 = [1111111110]
150 = [1111111110]
200 = [1111111100]
250 = [1111111000]
300 = [1111100000]
350 = [1111000000]
400 = [1100000000]
450 = [0000000000]

Now if we pick a pair of arbitrary angles 100 and 400 we get:
100 = [1111111110]
Diff 300 = 0.5 (empirical) :: 0.766 if reality match (falsified) -> [1111100000] verses [1111111100]:200 = 0.767
400 = [1100000000]

Now what went wrong with realism here? Note that the strings represent coincidences, not detections. Furthermore, for any given detection potentially an arbitrarily large, perhaps infinite, number individual states, vectors, etc., went into defining that detection. Thus when looking at "coincidences", not detections, we can't automatically presume that the detections that define the coincidences between 100 and 400 are the same coincidences in detections between 00 and 300. Yet the 'reality' condition being imposed presumes only a single coincidence pattern can be involved in a given coincidences rate. Thus each coincidence profile would have a distinct detection and coincidence profile for each particle and relative angle of detector, which can only be repeated on a twin to the degree that the relative detector angle matches the original relative detector angle, as define relative to the polarization of that particle.

In principle, you can take each coincidence term in [1111111111...], [], ...., at each angle, expand each term [1] to contain its own coincidence profile with the other coincidence elements for each variation of angle. Then repeat for those coincidence elements. This would diverge rather quickly, but presumably converge quickly with a measurement for the same reason. I can't prove this, but in some sense if you want to take Hilbert space and wavefunctions seriously as real requires taking infinities pretty seriously. as in actual infinities.

Am I convinced by this? Perhaps on Mondays, Wednesdays, and Fridays, but it is as reasonable as anything else proposed, and I've seen no argument to escape it. Even if it flies in the face of indeterminism in principle, it doesn't even in principle allow an escape in practice, EPR notwithstanding. This mutual dependence on individual 'real' particle properties verses detector settings, and the resulting variation in specific detections verses coincidences is how relational interpretations escape EPR while maintaining realism in the event sets that define them.

The key point here is that the specific detection pattern of a series of particles at one angle can't be the same detection pattern at another angle, cross setting counterfactual assumptions are presumptuous with or without realism. Thus the coincidences between two pair of detector patterns and settings is even further removed from counterfactual claims from alternative settings. Yet the "realism" as defined by impossibility claims requires coincidences from random sequence pairs to counterfactually match entirely different coincidences in entirely different random sequences as a proxy for "realness" in values. The summation of events that define the outcome can nonetheless be real, so long as you don't require a summation of them in one physical configuration, defined my the detector settings, to match the summation of the same events with another set of detector settings. It would be analogous to saying mass, space, time, etc., can't be real because observer measure it differently in different circumstances.

About your "prediction" (I hope so):
Hopefully my point is fairly clear now, I hope you can offer more, because this is where I'm stuck atm. To tell me I have to explain it isn't realistic as the alternative hasn't explained anything either. To say I will not change my mind presumes I have made up my mind, but so long as a fundamental weakness exist in FTL claims through counterfactual reasoning, and reasonable arguments exist that justify invalidating counterfactual reasoning even if in realism based toy models, I'll be stuck with uncertainty. Yes, counterfactual reasoning is a 'fundamental' weakness of Bell's theorem et al. Not to mention the trouble it creates for realism based FTL theories. My position will remain a mere choice, which I can only hope helps lead me forward in some way, unless you can deliver.

DrChinese

May20-10, 02:27 PM

1. I see your site is back up DrC. :smile: I'll go over it soon...

2. When you say, A i.e. B, I agree with A but will argue B implies properties that don't necessarily follow from A. I think it was the above interpretation you placed on the "realism" I used in my prior post.

Consider the following detection rates:
00 = 1
50 = 0.985
100 = 0.940
150 = 0.867
200 = 0.767
250 = 0.643
300 = 0.5
350 = 0.342
400 = 0.174
450 = 0
This pattern inversely after every 45 degrees.

To show the discrepancy with realism as defined, let's consider a set of string detections where any common setting of detector pairs matches this (rounded). [0] is a 'coincidence' non-detection and [1] is a 'coincidence' detection.
00 = [1111111111] (100% coincidences)
50 = [1111111111]
100 = [1111111110]
150 = [1111111110]
200 = [1111111100]
250 = [1111111000]
300 = [1111100000]
350 = [1111000000]
400 = [1100000000]
450 = [0000000000]

Now if we pick a pair of arbitrary angles 100 and 400 we get:
100 = [1111111110]
Diff 300 = 0.5 (empirical) :: 0.766 if reality match (falsified) -> [1111100000] verses [1111111100]:200 = 0.767
400 = [1100000000]

Now what went wrong with realism here? Note that the strings represent coincidences, not detections. Furthermore, for any given detection potentially an arbitrarily large, perhaps infinite, number individual states, vectors, etc., went into defining that detection. Thus when looking at "coincidences", not detections, we can't automatically presume that the detections that define the coincidences between 100 and 400 are the same coincidences in detections between 00 and 300. Yet the 'reality' condition being imposed presumes only a single coincidence pattern can be involved in a given coincidences rate. Thus each coincidence profile would have a distinct detection and coincidence profile for each particle and relative angle of detector, which can only be repeated on a twin to the degree that the relative detector angle matches the original relative detector angle, as define relative to the polarization of that particle.

1. Yes....!!!

2. OK, now we are getting somewhere. But you have already jumped a few places too far here, and so we need to go back a step or two.

a. EPR defines realism as being the ability to predict the outcome in advance. That is a separate criteria from the Bell test itself, and something which is assumed to be true. In other words, if we have a Bell state, we have perfect correlations. If we have perfect correlations, then there is an element of reality. If we have elements of reality at all angles, then there must be beginning values which were predetermined IF realism applies. Do you follow this argument? This is straight from EPR. Bell too. So if you agree on this definition of realism, we can apply it in your example.

b. To apply to your example: we cannot simply say: the correlations are [1111100000] or whatever. We need to specify the Alice values and the Bob values, as well as values for Chris. Later, during the test, we will make a separate selection of which pair (2 of the 3) we will actually pick. Then we calc the coincidences. If you agree with this, then we can proceed to the next steps.

And I do agree that the set of coincidences for 0 and 30 degrees is different than for 10 and 40 degrees. They have no causal connection to each other. I am glad you see that point. We will return to it later I suspect. For purposes of our example, don't worry about randomizing the results: just get values that work correctly when we ulitmately do look at coincidences. We will likely need 12 items instead of 10 in order to make the example arithmetic work out. Which is seeing that there is 3/12 coincidences per QM vs. 4/12 for local realistic at my example 0/120/240 example. By the way, that is also the same as 0/30/60 degrees so we only need your 30 degree value to work everything out (since the perfect correlations are always 100%). Simple, eh?

Also we need to agree about what a coincidence is. I call it a coincidence if there is a match. With no deduction for non-matches. Your formula seems to deduct for non-matches, which is confusing to me. Can we use the terms such that Match=Coincidence? That way, the coincidence rate at 45 degree is 50%. Actually, I don't entirely follow your labeling about detections vs. coincidences. There are always detections in our ideal example.

DrChinese

May20-10, 02:38 PM

And just to be clear: We need observer Chris (i.e. 3 sets of values) because the open question is: Does the choice of observation (i.e. which 2 observers are selected out of 3) affect the outcome? You are arguing that it cannot (assuming the observers are spacelike separated). I say it does matter, that you cannot arrive at the QM predictions otherwise.

my_wan

May20-10, 03:52 PM

DrChinese

May20-10, 04:18 PM

Yes in my string notation I ignored random detections not attributable to a causal mechanism per the "reality" postulate, and reordered them in nonrandom sequences. Trivial to simply randomize 00, change the remaining values accordingly. I did this to grab the main content in a nonrandom handwritten way to directly compare what was considered "real" about the coincidences. I'm a little strapped for time atm, but your issue with detections vs. coincidences is something that needs worked out. My string notation can't really have helped considering your version. I need to reformulate something you are more familiar with. You used a third observer, where I simply compared one pair of coincidences at one set of detector settings to different pair rather than a third observer.

I'll be back later, hopefully with a third person version, and also reiterate my earlier issues with realism as defined in paragraph a. Also again why EPR used it knowing its limitations. Your right we should take it piece by piece.

No problem on the time issue.

I use notation similar to yours in my examples when I am working things out. So try this for a dataset for 0/120/240:

Alice = [111111111111]
Bob = [000000001111]
Chris = [001100110000]

Notice that between any pair of observers, there are 4 out of 12 coincidences. That is 33%, the bottom limit for a local realistic theory. QM makes the predictions that there will be a coincidence rate of 25%.

================================================== ==========

See why I ask about datasets? If Bob's reality depends on whether Alice or Chris is the other observer, then you can have the correct relationships. But if Bob is blind to that, the relationships don't hold.

ThomasT

May20-10, 04:21 PM

It is simple. If you have a model, you can general a dataset. Give me the values for 0/120/240 degrees for Alice and Bob, using the formula from the paper. If you think it is the same as QM, then fine, show me. P.S. QM does NOT NOT NOT say there is a realistic dataset.

I will then tear your dataset to shreds. Now, quit saying it is unnecessary when it is. I can say that I witnessed my son walking on water, but you would want to see it yourself. Well, here am I, saying I want to see it. Bell would too. :biggrin:

Just like 1 is not 2, a claim of equivalence is NOT equivalence.This is absurd. You speak in riddles, and it's becoming clear to me that you don't understand the issues or the arguments being presented.

An equation expressing the expectation value of the joint probability isn't enough -- you want a dataset.

I know that you know enough physics to be able to ascertain if the joint probability in the paper matches the qm joint probability for the experimental situation.

So why don't you just do that, and then we can continue the discussion.

ThomasT

May20-10, 04:23 PM

I give up.One can only hope.

DrChinese

May20-10, 04:28 PM

Now, just to drive home the point I am making in my earlier post:

a. If I change the dataset to get the "right" answer between Alice and Bob:

Alice = [111111111111]
Bob = [000000000111]
Chris = [001100110000]

Then AliceBob yields 25% but BobChris is now 42% (5/12). But that doesn't work, because as we mentioned earlier, the ratio must hold between any pair of angles where the theta is the same.

b. If you want to see the QM dataset that most closely represents the "complete" reality of the test:

Alice = [111111111111]
Bob = [000000000111]

There is no Chris. Sorry Chris, you're outta here!!!!!!!!!!!!!

DrChinese

May20-10, 04:32 PM

So why don't you just do that, and then we can continue the discussion.

Forget it. You're the one out on the limb with your non-standard viewpoint. I can't prove the unprovable.

There is a formula, yes, I can read that. But it is not a local realistic candidate and there is no way to generate a dataset. He can't do it, and obviously neither can you. :bugeye:

Folks, we have another local realist claiming victory after demonstrating... ABSOLUTELY NOTHING. AGAIN.

my_wan

May21-10, 03:54 AM

Note: The way I ended this post shocked me, it wasn't planned, but I think I'll leave it as is. I have numbers to run.

I'm going to cover two issues in this post. The second, your 3 party detection system, has a physical equivalence to a QM effect in a rather classic series of three polarizers. This lead me to consider an experiment that would falsify my detection rate verses coincidence objection.

Issue #1
The first is the notion of realism again. If I'm required to maintain a strict adherence to Bell Realism as you have defined it, there simply is no way around it in the Bell's theorem context. Yet I find this restriction unwarranted, even in the context of EPR. The EPR paper stated: "A comprehensive definition of reality is, however, unnecessary for our purpose". What was defined was given on the limited grounds of "sufficiency" as needed for the EPR case provided in the paper. Yet even to this definition is was said: "Regarded not as necessary...". Yet even with these equivocations I think the paper failed to appreciate the richness in the way measured variables can vary in relation to the states that define them. Consider the words of Schneider:
http://www.drchinese.com/David/Hume%27s_Determinism_Refuted.htm
A review of the problem shows that we cannot, in principle, ever observe an independent variable. For it to be identified unambiguously as being independent, such variable can have no causal connection to other observables. (If there is any causal connection to another variable, then the cause cannot be narrowed to the hypothetical independent variable.) If it has no causal connection to other observables, then it cannot be observed! For all intents and purposes, it would not be part of the observable universe.

How would such an independent variable, which only intermittently maintained causal connections to other observables, fare in in this notion of Bell Realism? It would certainly rule out determinism and Bell Realism in the empirical arena, yet still be entirely feasible in principle in the theoretical arena. It wouldn't be any more unwarranted than any mathematical postulate. You've, to my understanding, stated contextual variables are not real, real variables have "simultaneous definite answers", etc., yet I can't even be sure any such measurable variable exist. Planck's constant probably being the most difficult to contextualize, though some have tried.

Let's start with this question to articulate this issue: Is the following 3 variables contextual, real, or both; space, time, and mass?

Issue #2
I'll start with how to falsify my detection rate verse coincidence objection, and perhaps this will provide the meaning. Your 3 party EPR correlation is essentially equivalent to a textbook example of a set of 3 polarizers in series. When 2 of them are put in series, set at 90 degrees from each other, no light will pass through both of them. Yet place a third polarizer placed between them, set at 45 degrees to the other 2, then 12.5% of the randomly polarized light will pass through all 3 of them, even though none could make it through just 2 at the same settings. Now we're going to do a version of your 3 party correlation test with photon polarization, except measure detection rates (intensity variance), rather than coincidences, and in a parallel rather than series. I'm personally not so concerned with absolute intensity or large separations to rule out local mechanisms, prior empirical data well satisfies me in that regard.

Place an emitter at the point of origin which emits polarized photons some distance to a pair of detectors on the + and -x axis. The output of the emitter will be constant over time for reference. The initial orientation of the polarizers at the detectors will match the polarization of the emitted photons, and the detection rate (intensity), not coincidences, are measured. Now this is like photons passing through a series pair of polarizers with a common polarization settings. In the series when you rotate one polarizer the light intensity through the 2 is reduced. Question: When you rotate polarizer A in the parallel setup will it induce a change detection rates (intensity) crossing polarizer B, like in the series arrangement? If so, my detection rate verse coincidence objection is busted. If not, this counterfactually entails that a change in polarization settings involves changing the actual individual particles involved in making correlation comparison. Thus couterfactual assumptions are empirically voided even before coincidence counts takes place.

Counterfactual assumptions have another problem in the properties of polarizers, as the 3 polarizer textbook example illustrates. When we measure the polarization of a photon, any photon that has a polarization near enough to the polarizer setting has some chance of being detected as having a polarization equal to that polarizer setting, which it does thereafter because the polarizer set it. Thus, when we talk about measuring polarization, we are actually, in most cases, resetting the polarization of that subset of particles which have properties close enough to be successful. Yet we call this a detection of a property that we just reset to that value ourselves. The amazing thing is that, when you adjust polarizer A out of alignment with B, you change the properties of the photons passing through it. Yet when you change B, to put it back in line with A, you change the properties of those photons in exactly the same way and sequence that A initially changed the properties of the photons at the other end, recreating the correlations. Does that crack the deterministic interpretation? It even provides the specific macroscopic context, polarizers resetting particle properties, which defines the context of the so called contextual variables. That would mean coincidence statistics are dependent on common spacial polarization, and the polarizers are simply resetting, not strictly measuring, that polarization, preferentially those nearest the polarizer setting. :bugeye:

my_wan

May21-10, 08:08 AM

Funny thing is it doesn't appear to make any difference whether the range at which a the polarizer detects a particle is modeled as indeterminacy or an actual range. The resulting behavior is the same, at least in this case, and appears to provides a local means for the coincidence to exceed classical variance.

DrChinese

May21-10, 08:58 AM

1. The first is the notion of realism again. If I'm required to maintain a strict adherence to Bell Realism as you have defined it, there simply is no way around it in the Bell's theorem context. Yet I find this restriction unwarranted, even in the context of EPR. The EPR paper stated: "A comprehensive definition of reality is, however, unnecessary for our purpose". What was defined was given on the limited grounds of "sufficiency" as needed for the EPR case provided in the paper. Yet even to this definition is was said: "Regarded not as necessary...". Yet even with these equivocations I think the paper failed to appreciate the richness in the way measured variables can vary in relation to the states that define them. Consider the words of Schneider:
http://www.drchinese.com/David/Hume%27s_Determinism_Refuted.htm

2. "Originally Posted by http://www.drchinese.com/David/Hume's_Determinism_Refuted.htm
A review of the problem shows that we cannot, in principle, ever observe an independent variable. For it to be identified unambiguously as being independent, such variable can have no causal connection to other observables. (If there is any causal connection to another variable, then the cause cannot be narrowed to the hypothetical independent variable.) If it has no causal connection to other observables, then it cannot be observed! For all intents and purposes, it would not be part of the observable universe."

How would such an independent variable, which only intermittently maintained causal connections to other observables, fare in in this notion of Bell Realism? It would certainly rule out determinism and Bell Realism in the empirical arena, yet still be entirely feasible in principle in the theoretical arena. It wouldn't be any more unwarranted than any mathematical postulate. You've, to my understanding, stated contextual variables are not real, real variables have "simultaneous definite answers", etc., yet I can't even be sure any such measurable variable exist. Planck's constant probably being the most difficult to contextualize, though some have tried.

1. Thanks for acknowledging my point, makes the discussion a lot easier. Yes, you are required to maintain a strict adherence to Bell Realism. :smile: What other point would there be to any meaningful definition of realism than to have a definition and adhere to it? If Bell shows Local Realism is at odds with QM, then we need to know what Local and Realism mean. EPR lays that out, and your quote misses the mark. They said there are elements of reality, and they ask at the end of their paper if they are simultaneous. Bell takes that to the next step.

So no, you cannot come up with a Bell realistic dataset using a local realistic theory. QED.

2. Nice quote, I don't think I could do better. :wink:

DrChinese

May21-10, 08:59 AM

DevilsAvocado

May21-10, 09:05 AM

... That would mean coincidence statistics are dependent on common spacial polarization, and the polarizers are simply resetting, not strictly measuring, that polarization, preferentially those nearest the polarizer setting. :bugeye:

But is this really strange...?

We have the QM probability distributions (HUP) for particles:
http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Standard_deviation_diagram.svg/450px-Standard_deviation_diagram.svg.png
And at 45° we have probability of 50% for spin up/spin down (top of the sine above), meaning the correlation is 0, or perfectly random, or equal to what LHVT can reproduce.
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c8/Bells-thm.png/600px-Bells-thm.png
At 22.5° we get a QM correlation of 0.71 which LHVT cannot compete with...

(And maybe that’s exactly what you are saying in next post :wink:)

DrChinese

May21-10, 09:15 AM

... That would mean coincidence statistics are dependent on common spacial polarization, and the polarizers are simply resetting, not strictly measuring, that polarization, preferentially those nearest the polarizer setting. :bugeye:

Not so fast! That was the entire point of the "elements of reality"!

We know that the polarizer is measuring and NOT resetting. How? We can perform the test on Alice, and use that result to predict Bob. If we can predict Bob with certainty, without changing Bob in any way prior to Bob's observation, then the Bob result is "real". Bell real.

DevilsAvocado

May21-10, 09:21 AM

... We can perform the test on Alice, and use that result to predict Bob. If we can predict Bob with certainty, without changing Bob in any way prior to Bob's observation, then the Bob result is "real". Bell real.

Not for a single pair of entangled photons, right?

DrChinese

May21-10, 10:16 AM

Not for a single pair of entangled photons, right?

Sure. Just not all angles simultaneously. But I can do for any specified angle. So the conclusion is that there must be an element of reality - per EPR - to that value.

Now keep in mind that within QM, entangled photons are in fact connected in that they are part of a shared wave state. But within local realism, there is no ongoing state called "entangled". In LR, entangled particles are more like a matched pair of socks. So there is the difference.

IcedEcliptic

May21-10, 10:20 AM

Dr. Chinese, I have been thinking of your "Frankenstein" entanglement, and I wonder if you could show the relationship with a data-set such as the one you just provided? I have read the papers you linked to, in this and other threads, and it seems that there is some indirect experimental evidence of this. Does this in any way reinforce some version of Cramer's TCI? Modify collapse from being atemporal, and map to decoherence instead and we no longer require "spooky" means or extra dimensions to explain entangled pairs.

DevilsAvocado

May21-10, 12:41 PM

Sure. Just not all angles simultaneously. But I can do for any specified angle. So the conclusion is that there must be an element of reality - per EPR - to that value.

DrC, if you could explain this to me I would be most thankful. Let’s keep it simple (safest for me :smile:):

We arrange the polarizer’s so that Alice = 0° and Bob = 22.5° (fixed).

We always measure Alice first, and then Bob (by putting them at different distances from S).

We send 100 entangled pairs of photons.

According to QM predictions we will get a correlation of 0.71.

This means we will get 71 correlated pairs (+, +) and 29 non-correlated pairs (+, -).

Alice at 0° will always measure 100 (+), and Bob at 22.5° will measure 71 (+) and 29 (-).

To me this means that we cannot be certain about one single outcome at Bob, only say that the probability for a single correlated pair (+, +) is 71%... what did I miss??

DrChinese

May21-10, 01:15 PM

DrC, if you could explain this to me I would be most thankful. Let’s keep it simple (safest for me :smile:):

We arrange the polarizer’s so that Alice = 0° and Bob = 22.5° (fixed).

We always measure Alice first, and then Bob (by putting them at different distances from S).

We send 100 entangled pairs of photons.

According to QM predictions we will get a correlation of 0.71.

This means we will get 71 correlated pairs (+, +) and 31 non-correlated pairs (+, -).

Alice at 0° will always measure 100 (+), and Bob at 22.5° will measure 71 (+) and 31 (-).

To me this means that we cannot be certain about one single outcome at Bob, only say that the probability for a single correlated pair (+, +) is 71%... what did I miss??

Here is how it works: I measure Alice at 0 degrees. The result is a +. With that information, I can predict the result of a mesaurement of Bob at 0 degrees. I make the prediction without first disturbing Bob. Therefore (according to EPR, Bell and most others) there is an element of reality to Bob's polarization at 0 degrees.

Similarly: I measure Alice at X degrees. The result is a +. With that information, I can predict the result of a mesaurement of Bob at X degrees. I make the prediction without first disturbing Bob. There is an element of reality to Bob's polarization at X degrees.

So there is no question that regardless of what angle I measure Bob, I can predict the result in advance with certainty. The implication, if you are a realist, is that the result of that observation must have been predetermined. How could it not be? At least, that is what a realist would assume. If the outcome was predetermined, then the effect of the measurement apparatus is not really an issue. After all, you get the same answer for Alice and Bob so whatever effect it has is a wash.

Of course, all of this is the EPR line.

Edgardo

May21-10, 02:04 PM

I thought this might be interesting for this thread:

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/yADcuGPphkY&hl=de_DE&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/yADcuGPphkY&hl=de_DE&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

From Bell's Inequalities to Entangled Qubits: A New Quantum Age? (http://www.cleoconference.org/about_cleo/Archives/2009/plenary2009.aspx)
A talk given by Alain Aspect (including youtube video and pdf file of his presentation).

Abstract: Bell’s theorem has drawn physicists’ attention onto the revolutionary character of entanglement. Based on that concept, a new field has emerged, quantum information, where one uses entanglement between qubits to develop conceptually new methods for processing and transmitting information.

DevilsAvocado

May21-10, 03:13 PM

(:redface: OMG I have just proved I can’t count to 100: 71 + 31 = 102!! How can you ever take me serious after this!? :rofl: EDIT!!)
Here is how it works: I measure Alice at 0 degrees. The result is a +. With that information, I can predict the result of a mesaurement of Bob at 0 degrees. I make the prediction without first disturbing Bob. Therefore (according to EPR, Bell and most others) there is an element of reality to Bob's polarization at 0 degrees.

Yes agree, absolutely no problem. (And this also works for LHV...)

Similarly: I measure Alice at X degrees. The result is a +. With that information, I can predict the result of a mesaurement of Bob at X degrees. I make the prediction without first disturbing Bob. There is an element of reality to Bob's polarization at X degrees.

This is where I get problem...

Of course, all of this is the EPR line.

Ahh, this is explains it! This is not according to Bell, right?

If it is Bell, then I get problem with this:

Instead of 100, we send 10 pairs (this makes it a lot easier for me to count! :biggrin:) and round correlation to 0.7 at 22.5°. Then one possible 'sequence' could look like this:
[11111 11111] = Alice
[00011 11111] = Bob

And another possible sequence could look like this:
[11111 11111] = Alice
[11100 01111] = Bob

And this:
[11111 11111] = Alice
[11111 10001] = Bob

And this:
[11111 11111] = Alice
[01010 11111] = Bob

And this:
[11111 11111] = Alice
[11111 01010] = Bob

And so on and so forth.

Now if you went to a bookmaker to make a bet on Bob, you can’t possibly be 100% sure to get your money back, when betting on the correct entangled pair sequence, could you??

---------------------------------------------------------------------------------
Footnote: DrC, your "Frankenstein" particle is cool, but what about Craig Venter?
Who today enounce the world’s first synthetic life form!! AHHHHHH :surprised
Here’s the press conference (http://a.blip.tv/scripts/flash/showplayer.swf?file=http%3A%2F%2Fblip.tv%2Frss%2Ff lash%2F3670782%3Freferrer%3Dhttp%25253A%25252F%252 52Fsvt.se%25252F2.106538%26source%3D3&showplayerpath=http%3A%2F%2Fblip.tv%2Fscripts%2Ffl ash%2Fshowplayer.swf&feedurl=http%3A%2F%2Fjcvi.blip.tv%2Frss%2Fflash&brandname=blip.tv&brandlink=http%3A%2F%2Fblip.tv%2F%3Futm_source%3Db randlink&enablejs=true).

DrChinese

May21-10, 03:28 PM

Ahh, this is explains it! This is not according to Bell, right?

If it is Bell, then I get problem with this:

Instead...

The elements of reality is the part that EPR and Bell agree on. This is the so called perfect correlations. To have a Bell state, in a Bell test, you must have these. The disagreement is whether these represent SIMULTANEOUS elements of reality. EPR thought they must, in fact thought that was the only reasonable view. But Bell realized that this imposed an important restriction on things.

In fact, that is the restriction that my_wan objects to. But that is part and parcel of Bell. In fact, it makes absolutely NO difference to Bell whether you think it is a reasonable requirement or not. The proof and the conclusion remain the same: IF you assume Bell realism (which is simply the simultaneous existence of individual EPR elements of reality), THEN QM will yield incompatible predictions. That is the Bell result.

So I am not sure by now if I have veered off from your question. :smile: So re-ask it if needed. And if I am repeating myself repeating myself repeating myself just say so.

Remember: Bell is holding the perfect correlations in his hand when he starts down the road for the 3 different settings path (a, b, c).

DevilsAvocado

May21-10, 05:42 PM

So I am not sure by now if I have veered off from your question. :smile: So re-ask it if needed.

Well... I think I do... :smile:

There’s a lot to talk about, realism etc, and I’ll dive into that when 'basics' are 'secured and in place'. So, the original question was:
If we can predict Bob with certainty, without changing Bob in any way prior to Bob's observation, then the Bob result is "real". Bell real.

And my 'objection' to that was: "Not for a single pair of entangled photons, right?"

Why I reacted was that my understanding of Bell’s contribution to EPR was to include probability theory into EPR, and probabilities never function well on only one event = "a single pair of entangled photons"...

There are absolutely no questions that in case of Alice 0° & Bob 0° we can, with certainty, predict Bob when only measuring Alice. And this could also Einstein, Podolsky, and Rosen achieve with their "agreement" or hidden variable.

Now, I think we both agree that at Alice 0° & Bob 22.5°, we have a QM prediction of a 0.71 correlation, right?

And I think, most certainly, that we both agree that "a single pair of entangled photons" cannot produce the number 0.71, right? (i.e. spin < ±1)

And here comes the 'tricky question'!

If I’m about to send 10 entangled pairs to Alice 0° & Bob 22.5°, the first photon for Alice would be:
[1] = Alice

Now, what is your prediction for Bob, and how certain can you be on that?? :wink:

(Remember, I’m going follow this up with 9 exactly the same questions! :biggrin:)

my_wan

May22-10, 12:37 AM

The elements of reality is the part that EPR and Bell agree on. This is the so called perfect correlations.
And I have repeatedly pointed out that contextual variables are allowed, and that if I'm required to maintain strict adherence to EPR/Bell definition, used only by EPR for operational sufficiency to that restricted argument, I can't argue realism. Originally I could only argue that these contextual variables, beyond what your allowing with the strict Bell's realism restrictions (measurement=absolute property) , could validly be considered. It's like demanding that because a coin lands tails-up I must talk of 'tails-up' as a counterfactual absolute property.

Yet I still had an empirical problem with how a contextual variable would work locally. We already knew with perfect anti-correlations that the initial state prior to measurement needed no FTL mechanism to explain the correlation. Even the local polarizer setting a particle came in contact with was locally known, but the nature of 'arbitrary' detector settings remained enigmatic. This was even a problem for FTL realistic mechanisms.

Now we have an empirically identifiable effect, with unknown but locally definable mode of operation, to contextualize that variable. All the "information" needed to supply these correlations can strictly defined locally, with or without FTL mechanisms.

Not so fast! That was the entire point of the "elements of reality"!

We know that the polarizer is measuring and NOT resetting. How? We can perform the test on Alice, and use that result to predict Bob. If we can predict Bob with certainty, without changing Bob in any way prior to Bob's observation, then the Bob result is "real". Bell real.
Is 'tails-up' an "element of reality" of a coin? It is IIF tails is up. If we know another coin, by conservation law, is perfectly anti-correlated, we know its "element of reality" is 'heads-up', without FTL mechanisms.

DevilsAvocado called the statistics situation perfectly. So what about this "measuring and NOT resetting"? This directly contradicts what is observed when 2 polarizers set at 90 degrees passes no light, but when a 3rd, set at 45 degrees to those 2, is placed between them light can then pass. Now I'm also well aware of the HUP version of this, but the results are the same, whether the uncertainty is real or a product of our state of knowledge. Like the momentum of an individual air molecule when we know the temperature.

In the HUP version the polarizer grid acts as measurement like squeezing light:
http://www.youtube.com/watch?v=KT7xJ0tjB4A
Except for polarizations rather than positions (conjugates). Which again empirically changes the very properties that Bell's Realism requires us to label innate. We can't predict the angle at which an air molecule escapes a hole in a compressed air tank either. Thus the notion that the properties are unchanged by polarizers is untenable whether were talking classical or QM.

Yet, even if a polarizer doesn't change the polarization of a photon, but merely allows a range of photon polarizations to pass, the 'group' statistics play out consistently. If you demand a singular property to be singularly defined by a polarizer, the notion that half of all randomly polarized light has that one singular property is patently ridiculous. Yet this 50% is precisely what empirically happens when we measure randomly polarized light with a single polarizer. Thus the realism=absolute unique property demands placed on EPR by Bell's Realism is empirically falsified by a single polarizer measuring randomly polarized light, without any correlation effects at any distance whatsoever.

my_wan

May22-10, 01:20 AM

my_wan

May22-10, 02:35 AM

We'll call the above "single question version" Bell's realism paradox (BRP). Once we allow, and we empirically must, this range of values to be included in a polarizer measurement, then it must induce more coincidences than singular values can account for.

This coincidence overcount can be replicated by two polarizers measuring randomly polarized light. Since 50% of all randomly polarized light passes through a polarizer either at 0 or 90 degrees, accounting for 100% of the light, Bell's realism requires us to assume all randomly polarized light must have a polarization of either 0 or 90 degrees. This then results in a paradox (BRP), when we consider arbitrary polarizer setting, other than 0 and 90 degrees.

Thus the empirical stature of Bell's theorem begs the question of how/why individual polarizers overcount the particles at a given polarization, but removes the locality issue from it. Of course HUP works just fine to mathematically describe this single polarizer overcount. But that 'appears' to restore the original objection EPR posed wrt indeterminacy lacking a mechanism, which, except for constraints imposed by conservation law, doesn't allow statistically significant correlations.

my_wan

May22-10, 07:30 AM

DrChinese

May22-10, 08:34 AM

There are absolutely no questions that in case of Alice 0° & Bob 0° we can, with certainty, predict Bob when only measuring Alice. And this could also Einstein, Podolsky, and Rosen achieve with their "agreement" or hidden variable.

Now, I think we both agree that at Alice 0° & Bob 22.5°, we have a QM prediction of a 0.71 correlation, right?

I have cos^2(22.5) as 85.36%, although I don't think the value matters for your example. I think you are calculating cos^2 - sin^2 - matches less non-matches - to get your rate, which yields a range of +1 to -1. I always calc based on matches, yielding a range from 0 to 1. Both are correct.

:biggrin:

DrChinese

May22-10, 08:50 AM

Another perspective:
Empirical proof invalidates the counterfactual assumption on which Bell's Theorem depends:

The polarization of a randomly polarized beam of light is measured at 3 angles: A=0°, B=45°, and C=90°. Since A and C add up to 100%, we cannot counterfactually maintain that none of the 50% detected at B wouldn't also have been detected at A and/or C, had that measurement been performed instead, without more than 100% of the photons involved. The same conservation laws which demand EPR correlations forbids it.

This is a dead solid proof invalidating the counterfactual assumption of Bell's theorem.

Most certainly is not. Has nothing to do with Bell: "The same conservation laws which demand EPR correlations forbids it.". You are arguing against QM. QM does not need to be correct for Bell to be correct.

It would be helpful if you could explain your example using datasets. Then it would be unambiguous. As it is, I am having a bit of difficulty following your point. It sounds as if you are saying that light cannot change its polarization due to conservation issues.

If you have a Local Realistic theory in which this example is correctly modeled, while QM does not, let's see it. It should be obvious that your example either applies - or does not apply - equally to QM and your (still invisible) LR theory. ON THE OTHER HAND: Bell points out an important different between QM and all LR candidate theories. This difference is generally accepted. If you don't want to accept this difference as being a defining point for an LR theory, then fine, you don't accept it. But don't expect others versed in the language of science to accept your definition of day as night, either.

DrChinese

May22-10, 08:55 AM

Single question version:
If polarization is an absolute observer independent state of a particle, which a polarizer (is presumed to) uniquely identifies, why does a polarizer identify 50% of all randomly polarized light as having that one singular polarization?

Who says this?????????????????????????????????????????????? ?

I certainly don't. We live in an observer dependent universe. At least, that's my interpretation.

my_wan

May22-10, 09:04 AM

Most certainly is not. Has nothing to do with Bell: "The same conservation laws which demand EPR correlations forbids it.". You are arguing against QM. QM does not need to be correct for Bell to be correct.

It would be helpful if you could explain your example using datasets. Then it would be unambiguous. As it is, I am having a bit of difficulty following your point. It sounds as if you are saying that light cannot change its polarization due to conservation issues.

If you have a Local Realistic theory in which this example is correctly modeled, while QM does not, let's see it. It should be obvious that your example either applies - or does not apply - equally to QM and your (still invisible) LR theory. ON THE OTHER HAND: Bell points out an important different between QM and all LR candidate theories. This difference is generally accepted. If you don't want to accept this difference as being a defining point for an LR theory, then fine, you don't accept it. But don't expect others versed in the language of science to accept your definition of day as night, either.
I provided the data set:
A randomly polarized beam of light, with 3 measurements.
1) Polarizer measures 50% photons at 0°.
2) Polarizer measures 50% photons at 45°.
3) Polarizer measures 50% photons at 90°.
Therefore any one measurement must include photons from one or more of the other measurements, per conservation law.

This is not a proof for or against any hvt, nor does it disprove Bell's theorem alone. It does, as a matter of fact, invalidate the counterfactual reasoning used to apply Bell's theorem to the locality issue of EPR.

No, I am not making any argument, whatsoever, against the empirical validity of QM. I am depending on that validity, along with conservation, to make the proof claim.

DrChinese

May22-10, 09:11 AM

1. And I have repeatedly pointed out that contextual variables are allowed, and that if I'm required to maintain strict adherence to EPR/Bell definition, used only by EPR for operational sufficiency to that restricted argument, I can't argue realism. Originally I could only argue that these contextual variables, beyond what your allowing with the strict Bell's realism restrictions (measurement=absolute property) , could validly be considered. It's like demanding that because a coin lands tails-up I must talk of 'tails-up' as a counterfactual absolute property.

2. Yet I still had an empirical problem with how a contextual variable would work locally.

1. Yes, if you are a local realist, you must acknowledge that a 100% certain tails up prediction indicates an element of reality. It does NOT say that tails up itself is an element of reality. That is simply a measuring rod. But there must be SOME element of reality somewhere or else you wouldn't get the certain result.

2. This is a good question!

Because I accept Bell, I know the world is either non-local or contextual (or both). If it is non-local, then there can be communication at a distance between Alice and Bob. When Alice is measured, she sends a message to Bob indicating the nature of the measurement, and Bob changes appropriately. Or something like that, the point is if non-local action is possible then we can build a mechanism presumably which explains entanglement results.

But what if the world is contextual instead of non-local? How would I answer your question then?

The answer is: I don't know. It is merely a logical requirement of Bell that contextuality is a possiblity. I don't know the mechanism.

Now, there are a number of interpretations which are non-realistic (i.e. contextual) but are fully local: Many Worlds (MWI) and Relational BlockWorld (RBW) come to mind as being explicitly local. The point is, QM is silent as to mechanisms. There is only the formalism. Yet the fact is: there is nothing specific missing from QM that we can be sure exists at this time.

DrChinese

May22-10, 09:14 AM

I provided the data set:
A randomly polarized beam of light, with 3 measurements.
1) Polarizer measures 50% photons at 0°.
2) Polarizer measures 50% photons at 45°.
3) Polarizer measures 50% photons at 90°.
Therefore any one measurement must include photons from one or more of the other measurements, per conservation law.

This is not a proof for or against any hvt, nor does it disprove Bell's theorem alone. It does, as a matter of fact, invalidate the counterfactual reasoning used to apply Bell's theorem to the locality issue of EPR.

No, I am not making any argument, whatsoever, against the empirical validity of QM. I am depending on that validity, along with conservation, to make the proof claim.

1) 2) 3) are formulas, not datasets. I guess you are saying something like:

1) HHHH
2) HTTH
3) TTTT

But I guess I am missing it because that works fine. You said there is a contradiction. Where is it?

my_wan

May22-10, 09:21 AM

Not data sets? They are exactly the datasets you'd get measuring the photons that a polarizer measure at that polarization at those angles, or any other angles for that matter.

Edit: for randomized polarization anyway.

my_wan

May22-10, 09:23 AM

Do you want a photon count to insure the polarizer is actually passing 50%?

DrChinese

May22-10, 09:44 AM

Not data sets? They are exactly the datasets you'd get measuring the photons that a polarizer measure at that polarization at those angles, or any other angles for that matter.

I cannot for the life of me understand how DATASET is not clear. A formula is a general case. A dataset is the specific. The purpose of the dataset is to demonstrate your point, because saying the formula isn't.

DrChinese

May22-10, 09:46 AM

Do you want a photon count to insure the polarizer is actually passing 50%?

No, experiments use beam splitters with detectors for both the H and V cases (of course the designation H and V is more or less arbitrary).

So if you can label as H/T or +/- or 0/1, that would be great. Show me a dataset and repeat your point.

my_wan

May22-10, 09:47 AM

2. This is a good question!
When I got into this debate I knew I was on thin ice. You had a much more defensible position. The empirical facts about how polarizers measure polarization of randomly polarized light, irrespective of interpretation, is a game changer. Here's what it does:

It provides a mechanism by which the overcount of coincidences, over and above Bell's inequalities, can be fully defined by the local properties of the measuring instrument, so long as conservation laws perfectly specify anti-correlations. Because the same correlations can be counted at different detector settings.

my_wan

May22-10, 09:54 AM

I cannot for the life of me understand how DATASET is not clear. A formula is a general case. A dataset is the specific. The purpose of the dataset is to demonstrate your point, because saying the formula isn't.
Property K is measured at 3 settings: A, B, and C.
Formula: If property K at A+B+C > 100%, then the properties associated with K must be measurable at more than one detector setting.
A=50%, B=50%, C=50% = 150%

my_wan

May22-10, 09:59 AM

Note: The proof does not involve any correlated particles. Merely randomized polarization of a local particle source.

my_wan

May22-10, 10:08 AM

No, experiments use beam splitters with detectors for both the H and V cases (of course the designation H and V is more or less arbitrary).

So if you can label as H/T or +/- or 0/1, that would be great. Show me a dataset and repeat your point.
I am not using any beam splitters, correlations, etc, etc. I specified a randomly polarized light source only, with a single local polarizer/detector at 3 settings.

DrChinese

May22-10, 10:24 AM

I am not using any beam splitters, correlations, etc, etc. I specified a randomly polarized light source only, with a single local polarizer/detector at 3 settings.

Are entangled pairs involved?

EDIT: I see that now that we are not talking about entangled pairs. See my next post.

DrChinese

May22-10, 10:38 AM

The empirical facts about how polarizers measure polarization of randomly polarized light, irrespective of interpretation, is a game changer. Here's what it does:

It provides a mechanism by which the overcount of coincidences, over and above Bell's inequalities, can be fully defined by the local properties of the measuring instrument, so long as conservation laws perfectly specify anti-correlations. Because the same correlations can be counted at different detector settings.

1415926535 is a dataset of digits. What correlations, what is the setup?

I would be glad to discuss polarized beams, unpolarized beams, and a sequence of 2/3 polarizers with their variations. I happen to think it is very interesting, and agree with you that even these examples involved conceptual issues. But keep in mind that the QM formalism handles these situations nicely regardless. A lot of folks also think classical wave theory handles this too (which it does) but of course the same wave theory does not explain the particle nature of light. Which QM does.

There are a lot of experiments out there that can confirm or deny any proposed hypothesis you might put forth. So don't forget my point about light's particle behavior. There is no classical analog. And when we talk about polarizers, all QM states is that the cos^2 rule is in effect for polarized beams. For unpolarized beams, the rule is 50%. I am curious as to what you hope to make with this. Good luck. :smile:

DrChinese

May22-10, 10:53 AM

I thought it might be worthy to post the words of Phillippe Grangier (2007) from his refutation of Christian:

"More generally, Bell’s theorem cannot be 'disproved', in the sense that its conclusions follow from its premices in a mathematically correct way. On the other hand, one may argue that these premices [sic] are unduly restrictive, but this is discussing, not disproving."

I.e. he is saying that you are indeen free to ignore Bell's definition of Realism. Of course, you are stuck with trying to replace it with a definition of Realism that does NOT follow the Bell result. No easy task, because such definition ends up being useless (i.e. has no utility, which is an important measure within scientific theory). Grangier mentions this point too.

my_wan

May22-10, 12:43 PM

Coming in a few moments is an attempt at a more thorough description, including very careful distinction between what I claimed to prove, and more general claims that appear to follow from it. I'm well aware that QM handles this perfectly, without interpretation, and anything that I claim in 'empirical' contradiction to QM is patently false. That does not restrict me to a 'literal' reading of the stated principles as 'the' reality. The QM formalism is as perfect a proxy for the truth of an empirical claim as can be imagined at this time, though in principle empiricism can potentially trump it. Hard to imagine how.

my_wan

May22-10, 01:02 PM

The elements of reality is the part that EPR and Bell agree on. This is the so called perfect correlations. To have a Bell state, in a Bell test, you must have these. The disagreement is whether these represent SIMULTANEOUS elements of reality. EPR thought they must, in fact thought that was the only reasonable view. But Bell realized that this imposed an important restriction on things.One of these important restrictions assumed that a particle, measured with particular detector setting, is unique to that detector setting. Thus counterfactually assumed that another detector setting would not have detected the same correlation with an alternative detector setting, i.e., definite variable value. Yet we can invalidate this without the use of any correlated/entangled particles.

We have a particle source emitting a single beam of particles with randomized polarizations. We use a single polarizer as our detector to measure polarizations, and all we are interested in is the percentage of the particles in the beam that has a polarization property consonant with a particular detector setting.

Question: Does our detector setting uniquely identify a property 'value', or can this property 'value' of a single particle be counterfactually detected with multiple detector settings?

Assertion: We know the polarization is randomized. Thus if we can add the particle detections from two or more detector settings, of the same particle beam, to add up to more than 100% of the detectable particles, then counterfactually we know the same particles can be detected from more than one detector setting.

We have property K, which we measure at unique detector settings [A, B, C, ...]. If A+B+C+... > 100% of the detectable particles, then we are measuring the same property K at multiple detector settings, and can't call a unique detector setting a unique '''value''' of that property of that unique particle.

Now we choose 3 settings: [A, B, C] at setting [0°, 45°, 90°].
Our results, per QM, is:
50% of particles have property K with a 'value' of 0°.
50% of particles have property K with a 'value' of 45°.
50% of particles have property K with a 'value' of 90°.
A+B+C=150%

Conclusion: Detector settings do not uniquely identify the '''value''' of property K, rather unique detector settings can include a range of possible values for the singular property K. K is of course polarization in this case. Per conservation law, we are forbidden to add extra particles to account for this discrepancy, but no such restriction exist for counterfactually measuring the same unique particle/property using multiple detector settings. Thus we cannot assume the value of property K, as provided by our measuring device, uniquely identifies the property K. The same property K can also be detected, counterfactually, with alternative detector settings.

Relevance to the EPR paradox:
This merely proves the counterfactual condition used in conjunction Bell's inequalities to label 'real' values as a proxy for realism is invalid. It does not invalidate the reality (or lack of) property K itself. Nor does it prove the this property of measurement alone is enough to account for the specific empirical statistical profile of QM in violation of Bell's inequality. That requires a little more than the simple proof that the counterfactual assumption used is invalid. If those are the numbers you wanted, those are in the process of being polished.

What I'll say, without proof, atm:
This entails that, under arbitrary detector settings, our detector can include a range of possible values for K, not just those with a particular value of K. In any EPR correlation experiment the polarization, from the perspective of any one detector, is randomized. The detector, at any given setting, empirical has a 50% chance of detecting property K, not necessarily value, from this random sequence of correlated particles. Preferentially those nearest the polarization of the measuring device, as other empirical test demonstrate. Thus, with minor changes in the detector settings, minor changes are made in which individual particles it couterfactually detects. This entails that the relative difference in detector settings on both ends is all that matters in capturing coincidences. The fact that value of K, as provided by the detector setting, is assumed to uniquely define property K leads to an overcount of coincidences when added over all arbitrary detector settings. As noted, small changes in detector settings have similarly small effects on which particular particles are couterfactually detected. This means the arbitrary detector setting choices act exactly as they should, relative settings. And can fully characterize Bell inequality violation solely by the local empirical detection properties of a polarizer, if the anti-correlations, per conservation law, is real.

Want proof of that last paragraph? Sorry, work in progress. But if you'll look at it yourself... :bugeye:

Ask any questions I wasn't clear on.

ajw1

May22-10, 01:52 PM

my_wan

May22-10, 02:32 PM

A lot of folks also think classical wave theory handles this too (which it does) but of course the same wave theory does not explain the particle nature of light. Which QM does.
Actually consider these:
A Soliton Model of the Electron with an internal Nonlinearity cancelling the de Broglie-Bohm Quantum (Potential: http://arxiv.org/abs/0906.0598)
The Photon as a Soliton (http://www.springerlink.com/content/j3m4p4026332r455/)
How to Describe Photons as (3+1)-Solitons? (http://arxiv.org/abs/physics/9812009)

Your still essentially correct. The whole classical wave theory approach is basically a disparate collection of works of wildly varying quality, with lots of toy models. About the only universal thread tying them together is a rough connection to classical thermodynamics. Of course QM already has a strong connection to generalized thermodynamics. Such classical leaning models lack a true foundational groundwork to build from. Then there's the problem of QM+GR, but then there's this:
The Einstein equations for generalized theories of gravity and the thermodynamic relation δQ = T δS are equivalent (http://arxiv.org/abs/0903.0823)

As intriguing as this is as a whole, with a few intriguing individual works, something needs to break to provide a cohesive foundation, so it don't look so much like an ad hoc force fit of disparate elements of the standard model on a classical thermodynamic model, like Christmas tree lights on a barn. The QM modeling has been improving, but even at its best it still looks more interpretive than theoretical.

DrChinese

May22-10, 04:19 PM

One of these important restrictions assumed that a particle, measured with particular detector setting, is unique to that detector setting. ...
Assertion: We know the polarization is randomized. Thus if we can add the particle detections from two or more detector settings, of the same particle beam, to add up to more than 100% of the detectable particles, then counterfactually we know the same particles can be detected from more than one detector setting.

We have property K, which we measure at unique detector settings [A, B, C, ...]. If A+B+C+... > 100% of the detectable particles, then we are measuring the same property K at multiple detector settings, and can't call a unique detector setting a unique '''value''' of that property of that unique particle.

Now we choose 3 settings: [A, B, C] at setting [0°, 45°, 90°].
Our results, per QM, is:
50% of particles have property K with a 'value' of 0°.
50% of particles have property K with a 'value' of 45°.
50% of particles have property K with a 'value' of 90°.
A+B+C=150%

Conclusion: Detector settings do not uniquely identify the '''value''' of property K, rather unique detector settings can include a range of possible values for the singular property K. K is of course polarization in this case. Per conservation law, we are forbidden to add extra particles to account for this discrepancy, but no such restriction exist for counterfactually measuring the same unique particle/property using multiple detector settings. Thus we cannot assume the value of property K, as provided by our measuring device, uniquely identifies the property K. The same property K can also be detected, counterfactually, with alternative detector settings.

Relevance to the EPR paradox:
This merely proves the counterfactual condition used in conjunction Bell's inequalities to label 'real' values as a proxy for realism is invalid. It does not invalidate the reality (or lack of) property K itself. Nor does it prove the this property of measurement alone is enough to account for the specific empirical statistical profile of QM in violation of Bell's inequality. That requires a little more than the simple proof that the counterfactual assumption used is invalid. If those are the numbers you wanted, those are in the process of being polished.

... The fact that value of K, as provided by the detector setting, is assumed to uniquely define property K leads to an overcount of coincidences when added over all arbitrary detector settings. ...

Ok, you have discovered a variation of some old logic examples: All boys are human, but not all humans are boys. And a little thought would indicate that 100% of all particles have either H or V values at ALL angles. By your thinking, A + B + C + D ... infinity means that the sum is actually infinite. Not what I would call a meaningful formula.

But where does Bell say anything remotely like this? Or EPR for that matter? A quote from Bell would be a good response.

In fact: Bell does NOT in any way require the outcomes to be unique to a measurement setting. Nor does Bell require all of the "rules" to relate to the particle itself. Some could relate to the interaction with the polarizer. All Bell requires is that whatever they are, there are 3 of them simultaneously.

I understand you have something in the back of your head, but you aren't making it easy. You obviously don't think the Bell result means that Local Realism is ruled out. Well, I can lead a horse to the bar but I can't make him take a drink. But it is wildly unreasonable for you to say the drinks are no good when everyone in the bar is having a grand time. That would be, for instance, because we are celebrating new and more exotic entanglement experiments daily. There were probably about 10 this week alone. The point being that nothing you are saying is useful. If these experimentalists followed your thinking, none of these experiments would ever be performed. Because every one of them involved finding and breaking Bell Inequalities.

I will leave you with 2 thoughts on the matter:

a) Can you put forth a local realistic model that yields the same predictions as QM? If you did, it would be significant.

The De Raedt team has worked diligently on this matter, and so you would find it difficult to out-gun them. They have yet to succeed, see my model for a proof of that.

b) Can you explain how, in a local realistic world, particles can be perfectly correlated when those particles have never existed within a common area of spacetime? If you could explain that, it would be significant.

You will see soon enough that the combination of a) and b) above will box you in.

ThomasT

May22-10, 04:34 PM

Forget it. You're the one out on the limb with your non-standard viewpoint.On the contrary, it's the advocates of nonlocality that hold the nonstandard viewpoint. One can't get much more unscientific, or nonscientific, than to posit that Nature is fundamentally nonlocal. The problem with it as an explanation for entanglement correlations is that it then remains to explain the explanation -- and I don't think that can be done.

On the other hand, there's a much simpler explanation for the correlations in, say, the Freedman and Clauser experiment, or the Aspect et al. experiments, that fits with the fundamental theories and assumptions on which all of modern science has been based -- and that explanation begins with the notion that the entanglement is due to the photons being emitted during the same atomic transition (ie., that there is a relationship between properties imparted at emission that, wrt analysis by a global measurement parameter, results in correlations that we refer to as entanglement stats).

What's being suggested is that, before we trash relativity or posit the existence of an underlying preferred frame where ftl propagations or instantaneous actions at a distance (whatever that might mean) are happening, perhaps it would be more logical (in light of what's known) to explore the possibility that Bell inequalities are violated for reasons that have nothing to do with ftl propagations or instantaneous actions at a distance. To that end, it's been suggested that Bell's lhv ansatz is incompatible with the experimental situations for which it was formulated for reasons that have nothing to do with whether or not Nature is exclusively local. In another, recent, thread it was demonstrated that there's a contradiction between probability theory, as utilized by Bell to denote locality, and probability theory as it should correctly be applied to the joint experimental situations that Bell's lhv ansatz purports to describe. What this entails is that Bell inequalities are violated because of that contradiction -- and not because the photons (or whatever) are communicating ftl or instantaneously. You responded to that OP's consideration in a decidedly nonsequiter, and yet charming, way, asking for ... a dataset. To which the OP responded, appropriately I think, something to the effect, "What's that got to do with what I was talking about?". The point is that there are considerations pertinent to the issue of evaluating the physical meaning of Bell's theorem that don't mean or require that the presenters of those considerations are advocating that an lhv interpretation of qm is possible. (Maybe the OP in the other thread is advocating the possibiltiy of an lhv interpretation of qm, but that's his problem. Anyway, he wasn't advocating that wrt the consideration he presented in that thread, afaict. )

By the way, DrC, please don't take my sarcasm too seriously (as I don't take yours that way). As I've said before, I admire your abilities, and contributions here, and have learned from you. But sometimes discussing things with you can be, well, a bit ... difficult.

Here's some light reading for those who care to partake:

http://bayes.wustl.edu/etj/articles/cmystery.pdf

Apparently, Jaynes viewed 'nonlocalists' with as much contempt as Mermin. I do hope that no one thinks that these guys (Jaynes and Mermin) are crackpots.

I can't prove the unprovable.And no one is asking anyone to do that. What would be nice is that contributors to these discussions at least try to discuss the issues that have been presented.

Of course, as usual with foundational issues, there are several 'threads' within this thread.

RUTA presents a conceptualization (and,at least symbolically, a realization) of quantum nonseparabiltiy which is both fascinating and, it seems, impossible to reconcile with the way I think it's most logical to presume that Nature is and the way she behaves. (OK, I don't understand it. Look, if it took Bub three, that's THREE, epiphanies to get it, then what hope do us normal people have to understand what RUTA's done . Anyway, I have a simpler conception of the physical meaning of quantum nonseparability which hasn't been refuted.)

DrC's instructive and informative VisualBasic construction I do understand (not that I could replicate it without months of getting back up to speed wrt programming), and it does what it purports to do.

I don't yet understand My_wan's considerations, having not had time to ponder them. But I will.

Zonde's consideration, wrt fair sampling, is certainly relevant wrt the proper application of the scientific method. However, it's preceded by considerations of the applicability of Bell's lhv ansatz to the experimental situation, and to the extent that these prior considerations effectively rule out inferences regarding what's happening in Nature from violations of BI's, then the fair sampling loophole is mooted wrt the OP of this thread. Anyway, I see no reason to assume that if an experiment were to simultaneously close all the technical loopholes, that the qm predictions would then, thereby, be invalidated. I'm not sure if Zonde thinks otherwise, or, if he does, what his reasons are for thinking this.

There is a formula, yes, I can read that.Ok, that's a step in the right direction.

But it is not a local realistic candidate ... I don't think it's meant to be -- at least not in the sense of EPR-Bell. Anyway, it's at least local. Explicitly so. It's just local wrt a different hidden parameter than Bell's lhv ansatz. And the fact that it's explicitly local, and reproduces the qm predictions, is all that matters wrt this thread.

I keep saying this, and you are, apparently, not reading it: An lhv interpretation of qm compatible with Bell's requirements is impossible.

... and there is no way to generate a dataset.If his formula matches the qm formula for the same experimental situation, then they'll predict the same results. Right? So, does it, or doesn't it?

Folks, we have another local realist claiming victory after demonstrating... ABSOLUTELY NOTHING. AGAIN.I don't recall claiming any sort of victory. The goal here is to get at the truth of things, collectively. Then we all win.

Naaaaaaaaah!
----------------------------------------------------

The following are some points to ponder -- more neatly presented than before.

WHY ARE BELL INEQUALITIES VIOLATED?

... USING LOCALITY ...

(1) Bell tests are designed and prepared to produce statistical dependence between separately accumulated data sets via the joint measurement of disturbances which have a local common origin (eg. emission by the same atom during the same transitional process).

(2) A correct model of the joint measurement situation must express the statistical dependence that the experiments are designed and prepared to produce.

(3) The assumption of locality is expressed in terms of the statistical INdependence of the separately accumulated data sets.

Conclusion: (3) contradicts (1) and (2), hence BIs based on limitations imposed by (3) are violated because an experimental situation designed to produce statistical dependence has been modelled as an experimental situation not designed to produce statistical dependence (ie., it's being modelled as a situation designed to produce statistical INdependence).. And since statistical dependencies can be due to local common causes, and since the experiments are jointly measuring disturbances that have a common origin, then no nonlocality is necessary to understand the violation of BIs based on (3).

... USING ELEMENTS OF REALITY ...

(4) Bell tests are designed and prepared to measure a relationship between two or more disturbances.

(5) The relationship between the measured disturbances does not determine individual results.

(6) EPR elements of reality require that a local hidden variable model of the joint measurement situation be expressed in terms of the variable or variables which, if it(they) were known, would allow the prediction of individual results.

Conclusion: (6) contradicts (4) and (5), hence the 'no lhv' theorems (eg., GHZ) based on limitations imposed by (6) are violated because the limitations imposed by (6) contradict an experimental situation designed to produce correlations based on a relationship between disturbances incident on the measuring devices. And since the relationship between the incident disturbances can reasonably be assumed to have been created locally during, say, an emission process, then no nonlocality is necessary to understand contradictions revealed by 'no lhv' theorems.

-------------------------------------

ARE LHV FORMULATIONS OF ENTANGLEMENT POSSIBLE?

No. Unless we want to change the historical meaning of 'local hidden variables', then Bell demonstrated that lhv formulations of entanglement are impossible. To paraphrase Bell, the statistical predictions of qm for the joint entangled state are incompatible with separable predetermination. In other words, a theory in which parameters are added to qm to determine the results of individual measurements cannot use those same parameters to determine the results of joint measurements. The relationship between jointly measured disturbances is nonseparable wrt the joint measurement parameter.

-------------------------------------

IS NONLOCALITY POSSIBLE?

Obviously, nonlocality is impossible if our universe is evolving in accordance with the principle of locality. Since there's presently no reason to suppose that it isn't, then, for now at least, based on what is known, the answer to that question has to be no.

IcedEcliptic

May22-10, 04:37 PM

You may believe that non-locality is incorrect, or even absurd, but it is standard. To say otherwise distorts the meaning of "standard". For the rest, you conclude that non-locality is impossible,"obviously", which makes me wonder why you've bothered to discuss such a "silly" topic with we poor fools who believe mounting evidence contrary to your a priori prejudice.

my_wan

May22-10, 06:14 PM

Ok, you have discovered a variation of some old logic examples: All boys are human, but not all humans are boys. And a little thought would indicate that 100% of all particles have either H or V values at ALL angles. By your thinking, A + B + C + D ... infinity means that the sum is actually infinite. Not what I would call a meaningful formula.
But the point is that A+B+C+.. can't exceed the total number of particles emitted.

But where does Bell say anything remotely like this? Or EPR for that matter? A quote from Bell would be a good response.
Counterfactual definiteness is a fundamental assumption when Bell's theorem is used to elucidate issues of locality. The clearest presentation puts it this way: The theorem indicates the universe must violate either locality or counterfactual definiteness.

What I have pointed out, by the fact that a single polarizer always measures 50% of randomly polarized light as having a single polarization, is that there is a specific empirically consistent way in in which we can talk about counterfactual measurements, at least statistically. Provided we can't measure more particles than was emitted. This not only results in a violation of Bell's inequalities, though by exactly how much I can't say yet, it requires the violations to be dependent only on the relative polarization settings. Thus no incongruencies in arbitrary settings, because many of the coincidences counted at one detector setting would also have counted by most other detector settings also.

Of course you have every right to ask for proof of this stronger claim, where I only proved that counterfactual definiteness as assumed by the use of Bell's inequalities isn't valid. I'll make one more post after this one to point it out again. Then hold off to provide at least a toy model to demonstrate.

In fact: Bell does NOT in any way require the outcomes to be unique to a measurement setting. Nor does Bell require all of the "rules" to relate to the particle itself. Some could relate to the interaction with the polarizer. All Bell requires is that whatever they are, there are 3 of them simultaneously.

Your own words:
"Yes, you are required to maintain a strict adherence to Bell Realism."
"It does NOT say that tails up itself is an element of reality."
Bell Realism is defined as a measurement we can predict, but that in some circumstances "tails-up" is a quiet predictable measurement.

But Bell inequalities goes further, it counts those predictions at a given polarizer setting and says whoa, there's too many coincidences to "realistically" account for at this one polarizer setting. Yet as I pointed out, the particles have a random polarization wrt one detector, and more importantly, one polarizer setting is detecting 50% of ALL the particles that come in contact with it, regardless of actual polarization prior to measurement. The only particles not subject to detection at all at a given polarizer angle are those exactly orthogonal, very few. How else do you account for 50% of all randomly polarized particles getting detected, even without correlations/entanglements. Thus any given photon has a 50% chance of being detected at any random detector setting, and tested for a correlation.

I'll construct a simple model to demonstrate the stronger claims I made.

DrChinese

May22-10, 06:29 PM

1. But sometimes discussing things with you can be, well, a bit ... difficult.

2. Here's some light reading for those who care to partake:

http://bayes.wustl.edu/etj/articles/cmystery.pdf

Apparently, Jaynes viewed 'nonlocalists' with as much contempt as Mermin. I do hope that no one thinks that these guys (Jaynes and Mermin) are crackpots.

1. Pot calling the kettle...

2. You apparently don't follow Mermin closely. He is as far from a local realist as it gets.

Jaynes is a more complicated affair. His Bell conclusions are far off the mark and are not accepted.

--------------------

I am through discussing with you at this time. You haven't done your homework on any of the relevant issues and ignore my suggestions. I will continue to point out your flawed comments whenever I think a reader might actually mistake your commentary for standard physics.

IcedEcliptic

May22-10, 06:36 PM

1. Pot calling the kettle...

2. You apparently don't follow Mermin closely. He is as far from a local realist as it gets.

Jaynes is a more complicated affair. His Bell conclusions are far off the mark and are not accepted.

--------------------

I am through discussing with you at this time. You haven't done your homework on any of the relevant issues and ignore my suggestions. I will continue to point out your flawed comments whenever I think a reader might actually mistake your commentary for standard physics.

I would not worry, no one could mistake personal fanaticism for scientific inquiry here, I hope.

DrChinese

May22-10, 06:38 PM

1. But the point is that A+B+C+.. can't exceed the total number of particles emitted.

2. But Bell inequalities goes further, it counts those predictions at a given polarizer setting and says whoa, there's too many coincidences to "realistically" account for at this one polarizer setting.

3. I'll construct a simple model to demonstrate the stronger claims I made.

1. This is fairly absurd. You might want to re-read what you are saying. Why would A+B+C... have any limit? I asked for a quote from Bell, where is it?

2. It is true that Bell Inequalities are usually expressed in terms of a limit. But that is a direct deduction from the Realism requirement. Which is essentially that counterfactual cases have a likelihood of occurring between 0 and 100%. Most consider this a reasonable requirement. If you use the cos^2 rule for making predictions, then some cases end up with a predicted occurance rate of less than -10% (that's a negative sign). If that is reasonable to you, then Local Realism is a go.

3. I truly look forward to that! :smile: And please, take as much time as you need.

----------------------

Again, a pattern is developing: I am challenging you on specific points. Here are 3 more. I recommend that you stop, read the above, and address them BEFORE going on to other points. I realize you have a lot to say, but we are simply going around in circles as you abandon one line of thinking in favor of another. So please, do us both a favor, let's discuss the 3 above before going elsewhere. I have provided very specific criticisms to what you are saying, and they should be taken seriously. That is, if you want me to take you seriously.

DrChinese

May22-10, 06:43 PM

I would not worry, no one could mistake personal fanaticism for scientific inquiry here, I hope.

I hope not, thanks for your welcome comments and support.

IcedEcliptic

May22-10, 07:06 PM

I hope not, thanks for your welcome comments and support.

Thanks for your tireless efforts to educate and further the discussion of Bell and N-L issues here. I've been reading through your threads, and truly you have the patience of a saint. I don't follow everything, but I really learn when I read these discussions. Some of this is a real challenge to accept and visualize, even when I believe it to be true.

RUTA

May22-10, 07:24 PM

On the other hand, there's a much simpler explanation for the correlations in, say, the Freedman and Clauser experiment, or the Aspect et al. experiments, that fits with the fundamental theories and assumptions on which all of modern science has been based -- and that explanation begins with the notion that the entanglement is due to the photons being emitted during the same atomic transition (ie., that there is a relationship between properties imparted at emission that, wrt analysis by a global measurement parameter, results in correlations that we refer to as entanglement stats).

You can entangle atoms that have not interacted with each other by using interaction-free measurement in an interferometer. Accordingly, these atoms don't interact with the photon in the interferometer either.

my_wan

May22-10, 08:52 PM

Yeah, the limit in the case I described is the total number of particles emitted, 100%. You still talking 'as if' I'm was talking about correlations, when there weren't even any entangled particles involved.

Yeah, the so called negative predicted occurrence rate occurs when detections are more likely in only one of the detectors, rather than neither or both. You almost made it sound like a "probability".
:frown:

billschnieder

May22-10, 10:00 PM

b) Can you explain how, in a local realistic world, particles can be perfectly correlated when those particles have never existed within a common area of spacetime? If you could explain that, it would be significant.

This is trivial. Every clock is correlated with every other clock whether or not they've ever been in a common area of spacetime. Any two harmonic signals are correlated irrespective of differences in amplitude, phase and frequency.

DrChinese

May22-10, 11:35 PM

This is trivial. Every clock is correlated with every other clock whether or not they've ever been in a common area of spacetime.

That's bull. I am shocked you would assert this. Have you not been listening to anything about Bell? You sound like someone from 1935.

DrChinese

May22-10, 11:37 PM

This is trivial. Every clock is correlated with every other clock whether or not they've ever been in a common area of spacetime. Any two harmonic signals are correlated irrespective of differences in amplitude, phase and frequency.

There are no global correlations. And on top of my prior post, I would like to mention that a Nobel likely awaits any iota of proof of your statement. Harmonic signals are correlated in some frames, but not in all.
There can be no entanglement - in a local realistic world - and classical particles will NOT violate Bell Inequalities. All of which leads to experimental disproof of your assertion. That being that perfect correlations are some easy to achieve feat, and do not require shared wave states. They only occur with entangled particles. Look at unentangled particle pairs and this will be clear.

my_wan

May23-10, 03:17 AM

I'm tired and getting sloppier, but I read your negative probabilities page at:
http://www.drchinese.com/David/Bell_Theorem_Negative_Probabilities.htm
I was thinking in terms of the of a given value E(a,b) from possible outcomes P(A,B|a,b) in the general proof of Bell's theorem. You had something else in mind.

What you have, at your link, is 3 measurements at angles A=0, B=67.5, and C=45. A and B are actual measurements where C is a measurement that could have been performed at A or B, let's say B in this case. This does indeed lead to the given negative probabilities, if you presume that what you measured at B cannot interfere with what you could have measured at C, had you done the 3 measurements simultaneously. The counterfactual reasoning is quoted: "When measuring A and B, C existed even if we didn't measure it."

So where do the negative probability come from here? What I claimed, and empirically justified on the grounds that a polarizer always detects 50% of all randomly polarized light (an absurdity if only light at that one polarization is being detected), is that some subset of the same particles detected at B would also have been detected at C, had that measurement been done. Since the same particle, presumed real, cannot be detected by both detectors, detection at one detector precludes a detection at the other detector, because the particles are considered real regardless of the variation of angles capable of detecting it. Therefore measuring the particle at B can negatively interfere with the measurement of that same particle at C.

So the page quote: "When measuring A and B, C existed even if we didn't measure it." Not when some subset of the particles, when measures are performed separately, are measured by both B and C. Thus when you consider simultaneous measures, at these detectors, the same particles must be detected twice by both B and C simultaneously to be counterfactually consistent with the separate measures.

Now I know this mechanism can account for interference in counterfactual detection probabilities, but you can legitimately write it off until the sine wave interference predicted by QM is quantitatively modeled by this interference mechanism. But I still maintain the more limited claim that the counterfactual reasoning contained in the quote: "When measuring A and B, C existed even if we didn't measure it" is falsified by the fact that the same particles cannot simultaneously be involved in detections at B and C. Yet it still existed, at one or the other detector, just not both. Probability interference is a hallmark of QM.

unusualname

May23-10, 08:14 AM

This is a fascinating debate although I must admit it is difficult to follow at times. my_wan's arguments appear very deep and well thought out, but I think I'm missing the requisite philosophical training to appreciate fully his viewpoint. However the exchanges between my_wan and DrChinese are very educational and I thank them for their efforts here in enlightening the subtle issues at the core of the EPR debate. :)

Earlier, I suggested a scientific experiment that would help settle this one way or the other, since as I understand it my_wan's explanation for the non-local correlations in entanglement would require that the correlations are instantaneous.

If we can demonstrate any delay in the entanglement correlations would that not rule out the relational theory of QM or the existence of fundamental probabilistic elements of reality (probabilistic realism)?

In principle it may be possible to construct a quantum computer which could record the time of qubit switching for certain qubits, although we would have to factor out the limit on qubit switching speed imposed by the uncertainty principle (mentioned previously)

Alternatively it may be possible to demonstrate a delay in Aspect type experiments by refining the timing and precision of the switching apparatus until it reaches a switching speed so fast that we can observe a reduction in entanglement effects (as we reached the threshold for the FTL signalling mechanism I proposed earlier we would expect entanglement effects to gradually fail). This would be tricky with the original Aspect setup, since we would have to switch the deflectors very precisely almost as the photons were about to hit them (since remember we are looking for a faster than light signalling mechanism between the entangled photons)

DrChinese

May23-10, 12:15 PM

...I read your negative probabilities page at:
http://www.drchinese.com/David/Bell_Theorem_Negative_Probabilities.htm
I was thinking in terms of the of a given value E(a,b) from possible outcomes P(A,B|a,b) in the general proof of Bell's theorem. You had something else in mind.

What you have, at your link, is 3 measurements at angles A=0, B=67.5, and C=45. A and B are actual measurements where C is a measurement that could have been performed at A or B, let's say B in this case. This does indeed lead to the given negative probabilities, if you presume that what you measured at B cannot interfere with what you could have measured at C, had you done the 3 measurements simultaneously. The counterfactual reasoning is quoted: "When measuring A and B, C existed even if we didn't measure it."

So where do the negative probability come from here?...

So the page quote: "When measuring A and B, C existed even if we didn't measure it." Not when some subset of the particles, when measures are performed separately, are measured by both B and C. Thus when you consider simultaneous measures, at these detectors, the same particles must be detected twice by both B and C simultaneously to be counterfactually consistent with the separate measures.

Now I know this mechanism can account for interference in counterfactual detection probabilities, but you can legitimately write it off until the sine wave interference predicted by QM is quantitatively modeled by this interference mechanism. But I still maintain the more limited claim that the counterfactual reasoning contained in the quote: "When measuring A and B, C existed even if we didn't measure it" is falsified by the fact that the same particles cannot simultaneously be involved in detections at B and C. Yet it still existed, at one or the other detector, just not both. Probability interference is a hallmark of QM.

OK, there are a couple of issues. This is indeed a counterfactual case. There are only 2 readings, not 3, so you have that correct.

As to interference: yes, you must consider the idea that there is a connection between Alice and Bob. But NOT in the case that there is local realism. In that case - which is where the negative probabilities come from - there is no such interaction. QM would allow the interaction, but explicit denies the counterfactual case as existing. Because it is not a Realistic theory.

DrChinese

May23-10, 12:19 PM

Earlier, I suggested a scientific experiment that would help settle this one way or the other, since as I understand it my_wan's explanation for the non-local correlations in entanglement would require that the correlations are instantaneous.

If we can demonstrate any delay in the entanglement correlations would that not rule out the relational theory of QM or the existence of fundamental probabilistic elements of reality (probabilistic realism)?

In principle it may be possible to construct a quantum computer which could record the time of qubit switching for certain qubits, although we would have to factor out the limit on qubit switching speed imposed by the uncertainty principle (mentioned previously)

Alternatively it may be possible to demonstrate a delay in Aspect type experiments by refining the timing and precision of the switching apparatus until it reaches a switching speed so fast that we can observe a reduction in entanglement effects (as we reached the threshold for the FTL signalling mechanism I proposed earlier we would expect entanglement effects to gradually fail). This would be tricky with the original Aspect setup, since we would have to switch the deflectors very precisely almost as the photons were about to hit them (since remember we are looking for a faster than light signalling mechanism between the entangled photons)

Scientists would in fact love to answer this question. Experiments have been done to the edge of current technology, and no limit has been found yet up to 10,000 times c. So I expect additional experiments as time goes on. If I see anything more on this, I will post it.

glengarry

May23-10, 02:28 PM

One can't get much more unscientific, or nonscientific, than to posit that Nature is fundamentally nonlocal.

Not only is it "scientific" to posit that Nature is fundamentally nonlocal, it is also the only "logical" thing to do. That is, we know that the physical space of our universe consists of three dimensions. Through pure force of reasoning, therefore, we should expect that the elements that constitute a physical reality such as ours are fundamentally spatial in nature. It is for this reason that Erwin Schrodinger posited the existence of a mathematically defined, dynamical object that can be understood--for lack of a better phrase--as an "ontological unity".

The main problem here, though, is that physics had never before been in a position to come to terms with the necessarily space-occupying nature of elemental reality. And this is indeed *necessary* because a three-dimensional universe that consists only of purely local (i.e. zero-dimensional) objects is simply a void. That is, all objects that are anything less than three-dimensional will occupy precisely a zeroth of the space of the universe. In other words, it only makes sense to understand that the parts of a three-dimensional universe are themselves three-dimensional.

But the reason why locality is taken so seriously by certain "naive" individuals is because the entire course of physics since the time of Galileo (up to the 20th century) has been simply to chart the trajectories of empirical bodies through "void" space rather than to come to terms with the way in which any such experience of physical seperateness is at all possible.

So, we can now understand Newton's famous hypothesis non fingo as an implicit acknowledgement that the question of the "true nature" of physical reality is indeed an interesting/important question, but that his particular job description at Cambridge University did not give him any reason to depart from the [nascent] tradition of physics as empirical prediction rather than ontological description.

But given the rise of Maxwellian "field type" theories in the 19th century, the question of the space-filling quality of elemental matter could not be ignored for much longer. It is for this reason that ether theories came into prominence. So by the early 1900's, there was an urgent need to find a resolution between the manifestly continuous aspects and granular aspects of physical experience.

This resolution was accomplished by way of the logical "quantization" of the electromagnetic continuum, giving a way for there to be a mathematical description for the way in which atoms are able to interact with one another. That is, photons are taken to be "radiant energy particles" that are able to cross the "void" that seperates massive bodies. So, we must understand that the desire to understand energy in a quantitative way was nothing other than a continuation of the Newtonian project of developing theories of a mathematically analytical nature, rather than a break from classical Newtonian thought. That is, the *real* break from the classical model is Maxwell's notion that there is a continuous "something" that everywhere permeates space. One implication of this way of thinking is that this "something" is the only "ontologically real thing," and that all experiences of particularity are made possible by modulations of continuous fields.

The reason why there is so much difficulty in coming into a physical theory that attains the status of being a compelling, "ontologically complete" model is that there is always a desire on the parts of human beings to be able to predict phenomena--that is, to be "certain" about the future course of events. And our theories reflect this desire by way of being reduced to trivially solvable mathematical formulations (i.e. differential equations of a single independent variable) rather than existing in formulations whose solutions are anything but apparent (i.e. partial differential equations of several independent variables).

So, we can now understand that Schrodinger's idea of reality as consisting of harmonically oscillating, space filling waveforms raised an extremely ominous mathematical spectre--which was summarily overcome by way of the thought of the psi function as a "field of probabilities" that can be satisfactorily "reduced" by way of applying Hermitian operators (i.e. matrices of complex conjugates) to it.

But now, we can see that Schrodinger's conceptually elegant ontological solution has been replaced by a purely logical formalism that is not meant to have any ontological significance. That is, the system of equations that can be categorized under the general heading of "quantum mechanics" is only meant to be a theory of empirical measurement, rather than a theory that offers any guidance as regards "what" it is that is "really" happening when any experimental arrangement registers a result.

So, if there is anyone who is searching for, shall we say, "existential comfort" as regards the nature of the "stuff" of physical reality, you are setting yourself up for major disappointment by looking towards the mainstream academic physics establishment (with physicsforums being its best online representative). Your best bet would probably be to pick up a book by or about Erwin Schrodinger, the man, rather than a book that merely uses his name in its exposition of the pure formalism that is quantum mechanics.

And other than that, I am doing my best to continue the tradition of pushing towards a thoroughly believable ontological theory of physical reality (www.physicsforums.com/showthread.php?t=398634) here at physicsforums.

my_wan

May23-10, 05:57 PM

OK, there are a couple of issues. This is indeed a counterfactual case. There are only 2 readings, not 3, so you have that correct.

As to interference: yes, you must consider the idea that there is a connection between Alice and Bob. But NOT in the case that there is local realism. In that case - which is where the negative probabilities come from - there is no such interaction. QM would allow the interaction, but explicit denies the counterfactual case as existing. Because it is not a Realistic theory.

To the assertion:"NOT in the case that there is local realism":
In the local realism assumption, the connection between Alice and Bob is carried by the particles as inverse local properties, and read via statistical coincidence responses to polarizers with various settings. Since Alice and Bob are the emitted particle pairs, C is not Charlie, but a separate interrogator of Bob asking for Bob's identity papers. In any reasonable experimental construction, B and counterfactual C, either B or C gets to Bob first to interrogate his identity. But whichever interrogates Bob first interferes with the other getting to interrogate Bob also. This is a requirement of local realism.

Thus Alice and Bob are the particles emitted, not A, B, and C interrogators (polarizers) that you choose to interrogate Alice and Bobs identity with, nor the singular arbitrary settings A, B, and C, used to interpret Alice and Bobs reported identity.

If this explanation holds, then your model, used to refute the De Raedt team's modeling attempts, is physically valid in interference effects, but fails to fully refute them.
http://msc.phys.rug.nl/pdf/athens06-deraedt1.pdf
The physical interpretation of the negative probability, defined from the possibly valid explanation given, is actually a positive possibility that the interrogator C will interrogate Bob first, before B gets to him. Thus if you assign this probability to interrogator B instead of C, which actually intercepted Bob, it takes a negative value.

This means my original assumption when you challenged me on negative probabilities, before I read your sites page on negative probabilities, wasn't as far off as I thought. As I stated then, the negative probability results from a case instance E(a,b) of a possibility derived from probability P(A,B|a,b). Thus not technically a probability in the strict sense. As I noted then, this only occurs "when detections are more likely in only one of the detectors, rather than neither or both". Such as when interrogator C gets to Bob before interrogator B does, producing a detection at C and missing at B. Which a full, and possibly valid, explanation was given above.

QM:
Technically QM doesn't confirm nor deny counterfactual reasoning. It merely calcs for whatever situation you 'actually' provide it. The counterfactual conflict only comes in after the fact, when you compare two cases you 'actually' provided. The fact that QM is not explicitly time dependent makes counterfactual reasoning even more difficult to interpret. If any time dependent phenomena are involved, it must be counterfactually interpreted as something that occurred between an event and a measurement, for which we have no measurements to empirically define, except after the fact when the measurement is performed.

DevilsAvocado

May23-10, 06:00 PM

For those acquainted with c-sharp, I have the same de Raedt simulation, but converted in an object oriented way (this allows a clear separation between the objects(particles and filters) used in the simulation).

OOP is cool, my favorite is Delphi/Object Pascal, which is very similar to C# (Anders Hejlsberg was/are chief architect for both).

Maybe I’ll check your version (http://www.physicsforums.com/showpost.php?p=2728427&postcount=464) out, but I have become somewhat 'doubtful' after reading the article (http://rugth30.phys.rug.nl/pdf/COMPHY3339.pdf). They are claiming to prove deterministic EPR–Bohm & NLHVT, stating this:
Thus, these numbers are no “random variables” in the strict mathematical sense. Probability theory has nothing useful to say about the deterministic sequence of these numbers. In fact, it does not even contain, nor provides a procedure to generate random variables.

(!?) Funny approach... when the probabilistic nature of QM is the very foundation of Bell’s work...?? It’s like proving that Schrödinger's cat can’t run, by cutting off the legs?:bugeye:?
(And true random numbers from atmospheric noise is available for free at random.org :wink:)

And what is this "time window"?? The code is executed sequentially, not multithreaded or parallel! And then multiply the "measurement" with a (pseudo-)random number to "check" if the "measurement" is inside this "time window"!? ... jeeess, I wouldn’t call this a "simulation"... more like an "imitation".

And De Raedt has another gigantic problem with his 'proof' of the non-local hidden variable theory:
An experimental test of non-local realism (http://arxiv.org/abs/0704.2529)
(Anton Zeilinger et.al)

Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories.

The best statement in the de Raedt article is this:
In the absence of a theory that describes the individual events, the very successful computational-physics approach “start from the theory and invent/use a simulation algorithm” cannot be applied to this problem.

Which lead to the next...

(I still admire all the work that you and DrC have put into this.)

But an open framework should probably be started in something like Maxima (http://maxima.sourceforge.net/).

The more I think about an "EPR framework" I realize it’s probably not a splendid idea, as De Raedt says – we don’t have a theory that describes the individual events. We don’t know what really happens!

So it’s going to be very hard, if not impossible, to produce an 'all-purpose' framework, that could be used for testing new ideas. All we can do is what De Raedt has done – to mimic already performed experiments.

I think...

If you think I’m wrong, there’s another nice alternative to Maxima in FreeMat (http://en.wikipedia.org/wiki/FreeMat) (with source (http://freemat.sourceforge.net/download.html)) which has an interface to external C, C++, and Fortran code (+ loading dll’s).

Cheers!

DevilsAvocado

May23-10, 06:42 PM

I have cos^2(22.5) as 85.36%, although I don't think the value matters for your example. I think you are calculating cos^2 - sin^2 - matches less non-matches - to get your rate, which yields a range of +1 to -1. I always calc based on matches, yielding a range from 0 to 1. Both are correct.

:biggrin:

You bet! :grumpy: Because I’ve got my value from a public lecture by Alain Aspect at the Perimeter Institute for Theoretical Physics, talking about Bell's theorem! :rofl:

To avoid that this thread soon get’s a subtitle – "The noble art of not answering simple questions" – I’m going to act proactive. :biggrin:

This is wrong:
We can perform the test on Alice, and use that result to predict Bob. If we can predict Bob with certainty, without changing Bob in any way prior to Bob's observation, then the Bob result is "real". Bell real.

Bell's theorem is all about statistical QM probability (except for 0° and 90° which also LHV handles perfect).

ajw1

May24-10, 05:06 AM

(!?) Funny approach... when the probabilistic nature of QM is the very foundation of Bell’s work...?? It’s like proving that Schrödinger's cat can’t run, by cutting off the legs?:bugeye:?
(And true random numbers from atmospheric noise is available for free at random.org :wink:)

It is very common to use pseudo random numbers in these kind of simulations, and often not worth the effort to get real random values. I don't think this is realy an issue, provided that your pseudo random generator is ok for the purpose.

And what is this "time window"?? The code is executed sequentially, not multithreaded or parallel! And then multiply the "measurement" with a (pseudo-)random number to "check" if the "measurement" is inside this "time window"!? ... jeeess, I wouldn’t call this a "simulation"... more like an "imitation".
De Raedt is not proposing a hidden variable theory, he says he can obtain the results of real Bell type experiments in a local realistic way.
So in real experiments one has to use a time frame for determining whether to clicks at two detectors belong to each other or not.
There are indications that particles are delayed by the angle of the filter. This delay time is used by de Raedt, and he obtains the exact QM prediction for this setup (well, similar results as the real experiment, which more or less follows the QM prediction).

The more I think about an "EPR framework" I realize it’s probably not a splendid idea, as De Raedt says – we don’t have a theory that describes the individual events. We don’t know what really happens!

So it’s going to be very hard, if not impossible, to produce an 'all-purpose' framework, that could be used for testing new ideas. All we can do is what De Raedt has done – to mimic already performed experiments.

I think...

If you think I’m wrong, there’s another nice alternative to Maxima in FreeMat (http://en.wikipedia.org/wiki/FreeMat) (with source (http://freemat.sourceforge.net/download.html)) which has an interface to external C, C++, and Fortran code (+ loading dll’s).

Cheers!
I don't know about 'all-purpose'. It seems to me that a De Raedt like simulation structure should be able to obtain the datasets DrChinese often mentions, for all kinds of new LR ideas.

DrChinese

May24-10, 08:41 AM

This is wrong:

[something DrChinese says...]

Bell's theorem is all about statistical QM probability (except for 0° and 90° which also LHV handles perfect).

Ha!

But we are talking about 2 different things. Yes, Bell is about the statistical predictions of QM vs. Local Realism. But both EPR and Bell use the idea of the "elements of reality" (defined as I have) as a basis for their analysis.

Score: Avocado 1, DrC 1.

DrChinese

May24-10, 09:07 AM

1. De Raedt is not proposing a hidden variable theory, he says he can obtain the results of real Bell type experiments in a local realistic way.

So in real experiments one has to use a time frame for determining whether to clicks at two detectors belong to each other or not.

There are indications that particles are delayed by the angle of the filter. This delay time is used by de Raedt, and he obtains the exact QM prediction for this setup (well, similar results as the real experiment, which more or less follows the QM prediction).

2. I don't know about 'all-purpose'. It seems to me that a De Raedt like simulation structure should be able to obtain the datasets DrChinese often mentions, for all kinds of new LR ideas.

1. The delay issue is complicated, but the bottom line is this is a testable hypothesis. I know of several people who are investigating this by looking at the underlying data using a variety of analysis techniques. I too am doing some work in this particular area (my expertise is in the data processing side). At this time, there is no evidence at all for anything which might lead to the bias De Raedt et al propose. But there is some evidence of delay on the order of a few ns. This is far too small to account for pairing problems.

2. Yes, it is true that the De Raedt simulation exploits the so-called "fair sampling assumption" (the time window) to provide a dataset which is realistic. The recap on this is:

a) The full universe obeys the Bell Inequality, and therefore does not follow Malus.
b) The sample violates the Bell Inequality and is close to the QM predictions.
c) The model is falsified for entangled photons which are not polarization entangled.

DevilsAvocado

May24-10, 09:12 AM

Score: Avocado 1, DrC 1.

Okay, I give up, you are right (as always)... :redface:

Score: (Smashed)Avocado ≈1, DrC >1.

:rofl:

ajw1

May24-10, 09:41 AM

But there is some evidence of delay on the order of a few ns. This is far too small to account for pairing problems.

It is not my intention to discuss the De Raedt model here intensively, but the time window used in the simulation and in the real experiment seems to be in the order of a few nano seconds, so in the same range as the evidence you mention (I haven't seen the articles with this evidence yet). Or am I misreading your statement?

But more important to this thread I think is that when his time tag calculation is set off, the event by event simulation can be used to test other LR theories.

DevilsAvocado

May24-10, 10:05 AM

It is very common to use pseudo random numbers in these kind of simulations, and often not worth the effort to get real random values. I don't think this is realy an issue, provided that your pseudo random generator is ok for the purpose.

Okay, you have spent at lot more time on this than me. At the same time this is interesting, as pseudo-random numbers are deterministic in the sense that if we know the seed, we can calculate the 'future' in a deterministic way. To my understanding, this is exactly what LHV does, right?

Conclusion: If we can make a computer version of EPR/BTE to produce the correct statistics with pseudo-random numbers, we have then automatically proved that (N)LHVT is correct!

So in real experiments one has to use a time frame for determining whether to clicks at two detectors belong to each other or not.
There are indications that particles are delayed by the angle of the filter. This delay time is used by de Raedt, and he obtains the exact QM prediction for this setup (well, similar results as the real experiment, which more or less follows the QM prediction).

Yes I know, Coincidence counting (http://en.wikipedia.org/wiki/Coincidence_counting_(physics)) in real experiment, where detections must be sorted into time bins. This is a interesting problem because, as we all know, there are no noise or disturbances in a sequential executed code without bugs, and there is no problem to get a 100% detection (unless we do a BASIC GOTO SpaghettiMessUpRoutine() :smile:):
Start
...
Detection1
...
Detection2
...
EvaluateDetections
...
End
(= almost impossible to fail)

So what does de Raedt do? He implements the 'weakness' of real experiments, and that’s maybe okay. What I find 'peculiar' is how pseudo-random numbers * measurement, has anything to do with real time bins and Coincidence counting... I don’t get it...

I don't know about 'all-purpose'. It seems to me that a De Raedt like simulation structure should be able to obtain the datasets DrChinese often mentions, for all kinds of new LR ideas.

Okay, if you say so.

DevilsAvocado

May24-10, 10:22 AM

1. The delay issue is complicated, but the bottom line is this is a testable hypothesis. I know of several people who are investigating this by looking at the underlying data using a variety of analysis techniques. I too am doing some work in this particular area (my expertise is in the data processing side). At this time, there is no evidence at all for anything which might lead to the bias De Raedt et al propose. But there is some evidence of delay on the order of a few ns. This is far too small to account for pairing problems.

DrC, I haven’t had the time to test/modify your code (need new/bigger HDD to install Visual Studio), but what happens if you completely skip "Coincidence counting" in the code??

(To me it seems very strange to build a whole scientific theory on noise and the 'troubles' of real measurements... :confused:)

EDIT: Ahh! I see ajw1 just answered the question...

DevilsAvocado

May24-10, 10:41 AM

... but the time window used in the simulation and in the real experiment seems to be in the order of a few nano seconds ...

How can you convert "a few nano seconds" to this code?

http://i49.tinypic.com/6oztpt.png

ajw1

May24-10, 10:47 AM

How can you convert "a few nano seconds" to this code?

http://i49.tinypic.com/6oztpt.png

The remark is base on their comparison of the dataset with real data (http://rugth30.phys.rug.nl/pdf/shu5.pdf), see for example page 8.

DevilsAvocado

May24-10, 11:37 AM

The remark is base on their comparison of the dataset with real data (http://rugth30.phys.rug.nl/pdf/shu5.pdf), see for example page 8.

Okay, thanks. It could most certainly be my lack of knowledge in polarizer’s and physics, that makes me see this as "strange", but I can’t help it – how can anyone derive "a few nano seconds" from this? It’s just a mystery to me? There are no clocks or timing in the sequential code, just Pi, Cos and Radians?
5.4 Time Delay

In our model, the time delay tn,i for a particle is assumed to be distributed uniformly over the interval [t0, t0 + T ]. In practice, we use uniform pseudo-random numbers to generate tn,i . As in the case of the angles ξn, the random choice of tn,i is merely convenient, not essential. From (2), it follows that only differences of time delays matter. Hence, we may put t0 = 0. The time-tag for the event n is then tn,i ∈ [0,T ]. There are not many reasonable options to choose the functional dependence of T . Assuming that the particle “knows” its own direction and that of the polarizer only, T should be a function of the relative angle only. Furthermore, consistency with classical electrodynamics requires that functions that depend on the polarization have period π [27]. Thus, we must have T (ξn − θ1) = F((Sn,1 • a)2) and, similarly, T (ξn − θ2) = F((Sn,2 • b)2), where b = (cos β, sin β). We found that T (x) = T0|sin 2x|d yields the desired results [15]. Here, T0 = maxθ T (θ) is the maximum time delay and defines the unit of time, used in the simulation. In our numerical work, we set T0 = 1.

To me, this looks like "trial & error", but I could be catastrophically wrong...

unusualname

May24-10, 11:40 AM

You simulation guys might be interested in this paper Corpuscular model of two-beam interference and double-slit experiments with single photons (http://arxiv.org/abs/1005.0906)

where they demonstrate single particle interference with a computer model which models the particles as "information carriers" exchanging information with the experimental apparatus. No wave function or non-local effects are assumed.

I like the idea that particles might exchange protocols like packets in a wifi network, but it seems a bit unlikely :smile:

DevilsAvocado

May24-10, 11:59 AM

Thanks UN, I have to leave for shorter break, but I’ll check the link later!

DrChinese

May24-10, 12:08 PM

It is not my intention to discuss the De Raedt model here intensively, but the time window used in the simulation and in the real experiment seems to be in the order of a few nano seconds, so in the same range as the evidence you mention (I haven't seen the articles with this evidence yet). Or am I misreading your statement?

As I say, it is a bit complicated. Keep in mind that the relevant issue is whether the delay is MORE for one channel or not. In other words, similar delays on both sides have little effect. I use the setup of Weihs et al as my "golden standard".

Violation of Bell's inequality under strict Einstein locality conditions, Gregor Weihs, Thomas Jennewein, Christoph Simon, Harald Weinfurter, Anton Zeilinger (Submitted on 26 Oct 1998)
http://arxiv.org/abs/quant-ph/9810080

As to the size of the window itself: Weihs uses 6 ns for their experiment. As there are about 10,000 detections per second, the average separation between clicks might be on the order of 25,000 ns. The De Raedt simulation can be modified for the size you like obviously.

It follows that if you altered the window size and got a different result, that would be significant. But with a large time difference between most events, I mean, seriously, what do you expect to see here? ALL THE CLICKS ARE TAGGED! It's not like they were thrown away.

When I finish my analysis of the data (which is a ways off), I will report on anything I think is of interest. In the meantime, I might suggest the following article if you want to learn more from someone who has studied this extensively:

http://arxiv.org/abs/0801.1776

Violation of Bell inequalities through the coincidence-time loophole, Peter Morgan, (11 Jan 2008)

"The coincidence-time loophole was identified by Larsson & Gill (Europhys. Lett. 67, 707 (2004)); a concrete model that exploits this loophole has recently been described by De Raedt et al. (Found. Phys., to appear). It is emphasized here that De Raedt et al.'s model is experimentally testable. De Raedt et al.'s model also introduces contextuality in a novel and classically more natural way than the use of contextual particle properties, by introducing a probabilistic model of a limited set of degrees of freedom of the measurement apparatus, so that it can also be seen as a random field model. Even though De Raedt et al.'s model may well contradict detailed Physics, it nonetheless provides a way to simulate the logical operation of elements of a quantum computer, and may provide a way forward for more detailed random field models."

Peter has been designing theoretical models for a number of years, with an emphasis on those with local random fields. I don't consider him a local realist (although I am not sure how he labels himself) because he respects Bell.

DrChinese

May24-10, 12:22 PM

So what does de Raedt do? He implements the 'weakness' of real experiments, and that’s maybe okay. What I find 'peculiar' is how pseudo-random numbers * measurement, has anything to do with real time bins and Coincidence counting... I don’t get it...

I don't think that would be a fair characterization of the de Raedt model. First, it is really a pure simulation. At least, that is how I classify it. I do not consider it a candidate theory. The "physics" (such as the time window stuff) is simply a very loose justification for the model. I accept it on face as an exercise.

The pseudo-random numbers have no effect at all (at least to my eyes). You could re-seed or not all you want, it should make no difference to the conclusion.

The important thing - to me - is the initial assumptions. If you accept them, you should be able to get the desired results. You do. Unfortunately, you also get undesired results and these are going to be present in ANY simulation model as well. It is as if you say: All men are Texans, and then I show you some men who are not Texans. Clearly, counterexamples invalidate the model.

DrChinese

May24-10, 12:28 PM

To me, this looks like "trial & error", but I could be catastrophically wrong...

I would guess that they did a lot of trial and error to come up with their simulations. It had to be reverse engineered. I have said many times that for these ideas to work, there must be a bias function which is + sometimes and - others. So one would start from that. Once I know the shape of the function (which is cyclic), I would work on the periodicity.

DevilsAvocado

May24-10, 03:26 PM

Thanks for the clarification DrC.

DevilsAvocado

May24-10, 03:46 PM

... No wave function or non-local effects are assumed.

I like the idea that particles might exchange protocols like packets in a wifi network, but it seems a bit unlikely :smile:

Yeah! I also like this approach.
In our simulation approach, we view each photon as a messenger carrying a message. Each messenger has its own internal clock, the hand of which rotates with frequency f. As the messenger travels from one position in space to another, the clock encodes the time-of-flight t modulo the period 1/f. The message, the position of the clock’s hand, is most conveniently represented by a two-dimensional unit vector ...

Thru this I found 3 other small simulations (with minimal code) for Mathematica which relate to EPR:

http://demonstrations.wolfram.com/BellsTheorem/thumbnail.jpg
Bell's Theorem (http://demonstrations.wolfram.com/BellsTheorem/)

http://demonstrations.wolfram.com/GeneratingEntangledQubits/thumbnail.jpg
Generating Entangled Qubits (http://demonstrations.wolfram.com/GeneratingEntangledQubits/)

http://demonstrations.wolfram.com/RetrocausalityAToyModel/thumbnail.jpg
Retrocausality: A Toy Model (http://demonstrations.wolfram.com/RetrocausalityAToyModel/)

(All include a small web preview + code)

DevilsAvocado

May24-10, 03:53 PM

And this:

http://demonstrations.wolfram.com/EventByEventSimulationOfDoubleSlitExperimentsWithS inglePhoto/thumbnail.jpg
Event-by-Event Simulation of Double-Slit Experiments with Single Photons (http://demonstrations.wolfram.com/EventByEventSimulationOfDoubleSlitExperimentsWithS inglePhoto/)

ajw1

May24-10, 05:12 PM

1. As I say, it is a bit complicated. Keep in mind that the relevant issue is whether the delay is MORE for one channel or not. In other words, similar delays on both sides have little effect.

2. I use the setup of Weihs et al as my "golden standard". Violation of Bell's inequality under strict Einstein locality conditions, Gregor Weihs, Thomas Jennewein, Christoph Simon, Harald Weinfurter, Anton Zeilinger (Submitted on 26 Oct 1998)
http://arxiv.org/abs/quant-ph/9810080

3. As to the size of the window itself: Weihs uses 6 ns for their experiment. As there are about 10,000 detections per second, the average separation between clicks might be on the order of 25,000 ns. The De Raedt simulation can be modified for the size you like obviously.

It follows that if you altered the window size and got a different result, that would be significant. But with a large time difference between most events, I mean, seriously, what do you expect to see here? ALL THE CLICKS ARE TAGGED! It's not like they were thrown away.

4. When I finish my analysis of the data (which is a ways off), I will report on anything I think is of interest.

1. I think the delay is only important when it depends on the angle of the filter. This relation can be equal on both sides.

2. De Raedt's work is based on the same article/data

3. All clicks are tagged, but not all clicks are used (that's why one uses a time window). It appears from the analysis of De Raedt of the data from Weihs et al. one needs to use a time window in the order of several ns to obtain QM like results, the optimum being near 4 ns. Either a larger time window or a smaller will yield worse results (and the reason for the latter is not because the dataset is getting too small for correct statistics).

4. You were able to obtain the raw data from Weihs et al.? I tried to find them, but I think they are no longer available on their site.

DrChinese

May24-10, 05:49 PM

1. I think the delay is only important when it depends on the angle of the filter. This relation can be equal on both sides.

2. De Raedt's work is based on the same article/data

3. All clicks are tagged, but not all clicks are used (that's why one uses a time window). It appears from the analysis of De Raedt of the data from Weihs et al. one needs to use a time window in the order of several ns to obtain QM like results, the optimum being near 4 ns. Either a larger time window or a smaller will yield worse results (and the reason for the latter is not because the dataset is getting too small for correct statistics).

4. You were able to obtain the raw data from Weihs et al.? I tried to find them, but I think they are no longer available on their site.

1. Keep in mind, the idea of some delay dependent on angle is purely hypothetical. There is no actual difference in the positions of the polarizers in the Weihs experiment anyway. It is fixed. To change angle settings:

"Each of the observers switched the direction of local
polarization analysis with a transverse electro-optic modulator.
It’s optic axes was set at 45◦ with respect to the
subsequent polarizer. Applying a voltage causes a rotation
of the polarization of light passing through the modulator
by a certain angle proportional to the voltage [13].
For the measurements the modulators were switched fast
between a rotation of 0◦ and 45◦."

2. Yup. Makes it nice when we can all agree upon a standard.

3. I think you missed my point. I believe Weihs would call attention to the fact that it agrees with QM for the 6 ns case but not the 12 ns case (or whatever). It would in fact be shocking if any element of QM was experimentally disproved, don't you think? As with any experiment, the team must make decisions on a variety of parameters. If anyone seriously thinks that there is something going on with the detection window, hey, all they have to do is conduct the experiment.

4. I couldn't find it publicly.

DevilsAvocado

May24-10, 06:24 PM

... the idea of some delay dependent on angle is purely hypothetical ...

That’s a big relief! :approve:

ajw1

May24-10, 06:31 PM

3. I think you missed my point. I believe Weihs would call attention to the fact that it agrees with QM for the 6 ns case but not the 12 ns case (or whatever). It would in fact be shocking if any element of QM was experimentally disproved, don't you think? As with any experiment, the team must make decisions on a variety of parameters. If anyone seriously thinks that there is something going on with the detection window, hey, all they have to do is conduct the experiment.
I was not suggesting any unfair playing by Weihs (re-reading my post I agree it looks a bit that way) :wink:. Furthermore as I said De Raedt has analysed the raw data from Weihs et al. and published the exact relation between the chosen time window and the results here (http://rugth30.phys.rug.nl/pdf/shu5.pdf). But surely you must have read this article.

ThomasT

May24-10, 06:41 PM

1. Pot calling the kettle...

2. You apparently don't follow Mermin closely. He is as far from a local realist as it gets.

Jaynes is a more complicated affair. His Bell conclusions are far off the mark and are not accepted.Again you've missed the point. I'm guessing that you probably didn't bother to read the papers I referenced.

I am through discussing with you at this time. You haven't done your homework on any of the relevant issues and ignore my suggestions. I will continue to point out your flawed comments whenever I think a reader might actually mistake your commentary for standard physics.You haven't been discussing any of the points I've brought up anyway. :smile: You have a mantra that you repeat.

Here's another question for you. Is it possible that maybe the issue is a little more subtle than your current understanding of it?

If you decide you want to answer the simple questions I've asked you or address the salient points that I've presented (rather than repeating your mantra), then maybe we can have an actual discussion. But when you refuse to even look at a paper, or answer a few simple questions about what it contains, then I find that suspicious to say the least.

billschnieder

May24-10, 06:53 PM

That's bull. I am shocked you would assert this. Have you not been listening to anything about Bell? You sound like someone from 1935.
I take it then you do not understand the meaning of "correlation".

EDIT:
There are no global correlations. And on top of my prior post, I would like to mention that a Nobel likely awaits any iota of proof of your statement. Harmonic signals are correlated in some frames, but not in all.
You contradict yourself by finally admitting that in fact all harmonic signals are correlated. The fact that it is possible to screen-off correlations in some frames does not eliminate the fact that there exists a frame in which a correlation exists. In reverse, just because it is possible to find a frame in which a correlation is screened-off does not imply that the correlation does not exist.

In any case, my original point which I believe still stands is the fact that two entities can be correlated even if they have never been in the same space-time area. It is trivial to understand that two systems governed by the same physical laws will be correlated whether or not they have been in the same space-time area or not.

I could go a step further and claim that every photon is correlated with every other photon just due to the fact that they are governed by the same physical laws, but I wouldn't as it is fodder for a different thread. ;-)

DevilsAvocado

May25-10, 07:59 AM

... Houston, we've have a problem with the FTL mechanism ...

The EPR paradox seems to be a bigger problem than one might guess at first sight. Bell's theorem has ruled out local hidden variables (LHV), both theoretically and practically by numerous Bell test experiments, all violating Bell inequalities.

To be more precise: Bell inequalities, LHV and Local realism are more or less the same thing, stating – there is an underlying preexisting reality in the microscopic QM world, and no object can influence another object faster than the speed of light (in vacuum).

There are other theories trying to explain the EPR paradox, like the non-local hidden variables theory (NLHV). But as far as I can tell, this has lately also been ruled out experimentally by Anton Zeilinger et.al.

Then we have other interpretations of QM, like Many Worlds Interpretation (MWI), Relational Blockworld (RBW), etc. Many of these interpretations have the 'disadvantage' of introducing a mechanisms that, too many, are more 'astonishing' than the EPR paradox itself, and thereby a contradiction to Occam's razor – "entities must not be multiplied beyond necessity".

Even if it seems like "Sci Fi", (the last and) the most 'plausible' solution to the EPR paradox seems to be some 'mechanism' operating faster than the speed of light between Alice & Bob. As DrChinese expresses (my emphasis):
... Because I accept Bell, I know the world is either non-local or contextual (or both). If it is non-local, then there can be communication at a distance between Alice and Bob. When Alice is measured, she sends a message to Bob indicating the nature of the measurement, and Bob changes appropriately. Or something like that, the point is if non-local action is possible then we can build a mechanism presumably which explains entanglement results.

If we look closer at this claim, we will see that even the "FTL mechanism" creates another unsolvable paradox.

John Bell used Probability theory to prove that statistical QM probabilities differ from LHV. Bell's theorem thus proves that true randomness is a fundamental part of nature:
"No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."

Now, what happens if we solve the EPR paradox with the "FTL mechanism"? Well, as DrC says, Alice sends a message to Bob to inform him about her angle and result, and what Bob needs to change appropriately.

Does this look like a fundamental and true randomness of the QM nature?

To me it doesn’t. Even if FTL is involved, there is a cause for Alice to send a message to Bob, and Bob will have a cause for his changes!?

This doesn’t make sense. This is a contradiction to the true randomness of QM, which Bell's theorem is proving correct!?

Any thoughts, anyone?

my_wan

May25-10, 08:45 AM

Since my post #485 (http://www.physicsforums.com/showpost.php?p=2729969&postcount=485) got ignored, I'm going to make a purely academic objection to the negative probabilities expressed on DrC's website (http://www.drchinese.com/David/Bell_Theorem_Negative_Probabilities.htm).

As I've previously noted, it's not a "probability" being described as negative, it's possible case instance E(a,b) of a probability P(A,B|a,b). To explain the different between a "possible case instance" and a "probability", consider a coin toss. The "probability" of a heads or tails is 50% each. A "possible case instance" will be either a heads or a tails, but no "probability" is involved after the coin toss and we know which side the coin landed on. What being compared is a large group of deterministically selected case instances.

Thus saying that case instances where the coin did in fact land on tails negatively interferes with heads is true, but makes no sense in terms of "probabilities". It's a case instance, not a probability. By itself this doesn't fully describe the negative probabilities possibilities described on the "negative probabilities" page, because there is still too many negative possibilities to account for in coin tosses.

As is well known, in the derivation of Bell's inequalties, negative possibilities only occur in case 'instances' where detections are more likely in only one of the detectors, rather than neither or both. So far exactly as you would expect in coin tosses. To understand where the extra coin tosses c0me from we need to look at a definition.
1) Bell realism - An element of reality is defined by a predictable value of a measurement.

Have have 2 measuring instruments A and B, which each consist of a polarizer and a photon detector. Each measure is considered an element of reality, per Bell realism, such that a measure by each of our 2 measuring instruments constitutes 2 elements of reality. Now we are going to emit a single photon at our detectors. Only detector A has a particular polarization setting, and detector B is not another detector, but another setting we could have chosen for detector A, i.e., a counterfactual measurement.

Now, by definition we are looking for 2 elements of reality, i.e., predictable measures per Bell realism. Yet if A detects our single photon, we know B can't, and visa versa. But if counterfactually both A and B was in principle capable of separately detecting that one photon, we are allowed to presume that only sometimes did A and B both see the photon (since we can call it both ways counterfactually), and sometimes not. So if that counterfactual measure can sometimes see the same photon we are required to call that a separate element of reality per Bell Realism, even though it's the same photon. Yet that requires us to also call the times A detected the photon but B didn't 2 separate elements of reality also.

If we call it the other way, and call both measurements the same element of reality per photon, it makes sense in those case where one detector detects the photon, but not the other. But violates Bell realism in cases where both detectors were capable of detecting that same photon. The negative possibility page presumes each measurement represents it's own distinct element of reality, which makes sense in those cases where both A and B could have detected the same photon. Thus, in those cases where our single photon can't counterfactually be detected by both detectors, it appears as if reality itself has been negatively interfered with.

Objections:
But we are talking statistics of a large number of photons, not a single photon. The negative probabilities are of a large number of detections.

True, but by academic definition, the large number of cases where derived from the special cases E(a,b) of the general probability P(A,B|a,b). It's tantamount to flipping a coin many times, taking all the cases where E(a,b)=tails, and calling that a probability because we are dealing with many cases of tails, rather than just one.

This argument is contingent upon a single assumption, that a single photon can 'sometimes' be 'counterfactually' detected by the same detector with a different polarization setting. I empirically justify this by the following empirical facts:
1) A polarizer will pass 50% of all 'randomly' polarized light.
2) A polarizer set at a 45 degree angle to a polarized beam of light will pass 50% of the light in that beam.

Now this is perfectly well described in QM and HUP, and this uncertainty is a LOCAL property of the individual photon itself. In QM, polarization is also perfectly well described as a quantum bit, where it can have values between 0 and 1. It is these partial values between 0 and 1 that allows the same photon to 'sometimes' be counterfactually detected with multiple polarizer settings. Yet this bit range is still a LOCAL property of the bit/photon.

We only have to accept the reality of HUP as a real property of the LOCAL photon polarization bit to get violations of Bell realism (a distinct issue from correlations). Yet the fact that correlations exist at all, and anti-twins (anti-correlated particles) can repeat the same response to polarizers deterministically, even with offsets in the 0/1 bits, indicates that as real as HUP is, it doesn't appear to be fundamental. So in this conception we have real LOCAL bit value ranges via HUP, legitimizing the QM coincidence predictions, with correlations that indicate HUP is valid, but not fundamental. The LOCAL validity of HUP is enough to break Bell's inequalities. While the breaking of Bell realism itself, due to LOCAL HUP, breaks the negative "possibility" proof.

The one to one correspondence between an element of reality (photon) and a detection is broken (Bell realism), when counterfactually a different detector setting can sometimes detect the same photon, and sometimes not. It does not explicitly break realism wrt the reality and locality of the photon itself. Detector and counterfactual detector is, after all, effectively in the same place.

DrChinese

May25-10, 08:49 AM

I was not suggesting any unfair playing by Weihs (re-reading my post I agree it looks a bit that way) :wink:. Furthermore as I said De Raedt has analysed the raw data from Weihs et al. and published the exact relation between the chosen time window and the results here (http://rugth30.phys.rug.nl/pdf/shu5.pdf). But surely you must have read this article.

Sure. And I consider it reasonable for them to make the argument that a change in time window causes some degradation of the results, although not enough to bring in to the realistic realm. This is a good justification for their algorithm then, because theirs does not perfectly model the QM cos^2 relationship. But it does come sorta close and it does violate a Bell Inequality (as it should for their purposes) while providing a full universe which does not. Again, as a simulation, I think their ideas are OK to that point. My issue comes at a different step.

DrChinese

May25-10, 08:53 AM

...Now, what happens if we solve the EPR paradox with the "FTL mechanism"? Well, as DrC says, Alice sends a message to Bob to inform him about her angle and result, and what Bob needs to change appropriately.

Does this look like a fundamental and true randomness of the QM nature?

To me it doesn’t. Even if FTL is involved, there is a cause for Alice to send a message to Bob, and Bob will have a cause for his changes!?

This doesn’t make sense. This is a contradiction to the true randomness of QM, which Bell's theorem is proving correct!?

Any thoughts, anyone?

I would tend to agree. FTL seems to fill in the cause. As I understand the Bohmian program, it is ultimately deterministic. Randomness results from stochastic elements.

DrChinese

May25-10, 08:58 AM

1. You contradict yourself by finally admitting that in fact all harmonic signals are correlated.

2. I could go a step further and claim that every photon is correlated with every other photon just due to the fact that they are governed by the same physical laws, but I wouldn't as it is fodder for a different thread. ;-)

1. I never said anything of the kind. Some synchronization is possible in some frames. Entangled particles are entangled in all frames as far as I know.

2. Maybe they are. That would be a global parameter. c certainly qualifies in that respect. Beyond that, exactly what are you proposing?

DrChinese

May25-10, 09:05 AM

As is well known, in the derivation of Bell's inequalties, negative possibilities only occur in case 'instances' where detections are more likely in only one of the detectors, rather than neither or both. ...

Have have 2 measuring instruments A and B, which each consist of a polarizer and a photon detector. Each measure is considered an element of reality, per Bell realism, such that a measure by each of our 2 measuring instruments constitutes 2 elements of reality. Now we are going to emit a single photon at our detectors. Only detector A has a particular polarization setting, and detector B is not another detector, but another setting we could have chosen for detector A, i.e., a counterfactual measurement.

Now, by definition we are looking for 2 elements of reality, i.e., predictable measures per Bell realism. Yet if A detects our single photon, we know B can't, and visa versa.

...

If we call it the other way, and call both measurements the same element of reality per photon, it makes sense in those case where one detector detects the photon, but not the other. But violates Bell realism in cases where both detectors were capable of detecting that same photon. The negative possibility page presumes each measurement represents it's own distinct element of reality, which makes sense in those cases where both A and B could have detected the same photon. Thus, in those cases where our single photon can't counterfactually be detected by both detectors, it appears as if reality itself has been negatively interfered with.

Objections:
But we are talking statistics of a large number of photons, not a single photon. The negative probabilities are of a large number of detections.

True, but by academic definition, the large number of cases where derived from the special cases E(a,b) of the general probability P(A,B|a,b). It's tantamount to flipping a coin many times, taking all the cases where E(a,b)=tails, and calling that a probability because we are dealing with many cases of tails, rather than just one.

This argument is contingent upon a single assumption, that a single photon can 'sometimes' be 'counterfactually' detected by the same detector with a different polarization setting. .

OK, I am still calling you out on your comments about a photon not being able to be detected at more than 1 angle. Show me a single photon - anywhere anytime - that cannot be detected by a polarizing beam splitter. Your assertion is simply incorrect! (Yes, in an ordinary PBS there is some inefficiency so 100% will not get through, but this is not what you are referring to.)

Further, the Bell program is to look for at least 3 elements of reality, not 2. The EPR program was 2.

DrChinese

May25-10, 09:16 AM

In any case, my original point which I believe still stands is the fact that two entities can be correlated even if they have never been in the same space-time area. It is trivial to understand that two systems governed by the same physical laws will be correlated whether or not they have been in the same space-time area or not.

Oh really? Trivial, eh? You really like to box yourself in. Well cowboy, show me something like this that violates Bell inequalities. I mean, other than entangled particles that have never been in each others light cones. LOL.

You see, it is true that you can correlate some things in simple ways. For example, you could create spatially separated Alice and Bob that have H> polarization. OK. What do you have? Not much. But that really isn't what we are discussing is it? Those photons are polarization correlated in a single basis only. Not so entangled photons, which are correlated in ALL bases. So sure, we all know about Bertlmann's socks but this is not what we are discussing in this thread.

my_wan

May25-10, 12:09 PM

OK, I am still calling you out on your comments about a photon not being able to be detected at more than 1 angle. Show me a single photon - anywhere anytime - that cannot be detected by a polarizing beam splitter. Your assertion is simply incorrect! (Yes, in an ordinary PBS there is some inefficiency so 100% will not get through, but this is not what you are referring to.)

Further, the Bell program is to look for at least 3 elements of reality, not 2. The EPR program was 2.
Sentence 1): "OK, I am still calling you out on your comments about a photon not being able to be detected at more than 1 angle."

My argument is contingent upon the assumption that single photons can (counterfactually) be detected at more than 1 angle.

Sentence 2): "Show me a single photon - anywhere anytime - that cannot be detected by a polarizing beam splitter."

Simple enough. I'll do it for a whole beam of photons. Simply polarize the beam to a particular polarization, and turn a polarizer to 90 degrees of that beam. Effective none of the photons will get through the polarizer to a detector. Not sure why you specified a "beam splitter" here, as I'm only talking about how a photon responds to a polarizer at the end of it's trip. When final detection takes place for later coincidence comparisons. But it doesn't make a lot of difference.

Just because a quantum bit has effective values between 0 and 1 doesn't entail an equal likelihood of a measurement producing a 0 or a 1 in all cases.

Sentence 3): "Your assertion is simply incorrect!"
Suspect, given that sentence 1) indicates I claimed against what I claimed on reasonable empirical grounds.

Sentence 3): (Yes, in an ordinary PBS there is some inefficiency so 100% will not get through, but this is not what you are referring to.)
True, not what I was referring to. As a matter of fact I'm quiet happy to assume 100% efficiency for practical purposes, even if not strictly valid. Nor does my argument include the PBS, only the polarizers at the distant detection points, at the time of final detection but before the coincidence counts takes place. The one that's paired with the photon detector.

my_wan

May25-10, 12:47 PM

Oops, I left out sentence 4): "Further, the Bell program is to look for at least 3 elements of reality, not 2. The EPR program was 2."

Yes, and it is this 3rd "elements of reality" that I am saying is sometimes a distinct "elements of reality", when the photons are unique, and sometimes not, when counterfactually the same photon would have been detected by both the 2nd and counterfactual 3rd so called "element of reality" (detector).

What this would mean is that the negative probability you calculated is the percentage of photons that would have been detected by the 2nd and counterfactual 3rd "element of reality" (detectors).

my_wan

May25-10, 01:08 PM

I'm still a bit shocked at sentence 1):
"OK, I am still calling you out on your comments about a photon not being able to be detected at more than 1 angle."

Let's enumerate sentences to the contrary in the specific post you responded to:
(Let's put the granddaddy of them first, even if out of occurrence order)

1) This argument is contingent upon a single assumption, that a single photon can 'sometimes' be 'counterfactually' detected by the same detector with a different polarization setting.

2) But if counterfactually both A and B was in principle capable of separately detecting that one photon, we are allowed to presume that only sometimes did A and B both see the photon (since we can call it both ways counterfactually), and sometimes not.

3) So if that counterfactual measure can sometimes see the same photon we are required to call that a separate element of reality per Bell Realism, even though it's the same photon.

4) It is these partial values between 0 and 1 that allows the same photon to 'sometimes' be counterfactually detected with multiple polarizer settings.

5) The one to one correspondence between an element of reality (photon) and a detection is broken (Bell realism), when counterfactually a different detector setting can sometimes detect the same photon, and sometimes not.

These are the sentences that explicitly require the opposite of what you claimed I said, but many more contingent upon it.

DrChinese

May25-10, 01:34 PM

I'm still a bit shocked at sentence 1):
"

Let's enumerate sentences to the contrary in the specific post you responded to:
(Let's put the granddaddy of them first, even if out of occurrence order)

1) This argument is contingent upon a single assumption, that a single photon can 'sometimes' be 'counterfactually' detected by the same detector with a different polarization setting.

I am so confused at what you are asserting. :bugeye:

My version does not require counterfactuality. I can do the experiment all day long. A photon can be observed at any angle at any time. I can do angle A, then B, then C, then C again, etc. And I still have a photon. So again, I am calling you out: please quote a reference which describes the behavior you mention, and point to a spot in Bell where this is referenced. Or alternately say that it is your personal speculation.

my_wan

May25-10, 03:40 PM

DrC,
This model I am describing is new to me, only occurred to during this debate a few days ago. Before then the contextuality issue was purely theoretical, however reasonable it appeared to me as at least possible. Now I'm trying to express it as it's being investigated. I'm quiet aware that I haven't been completely lucid in my account of it in all cases, but it seemed to me that the underlying idea should be fairly clear. Maybe that's just a perspective though.

Regardless, debating you has been far more fruitful and informative than I could possibly have hoped. It's rare for me to have the pleasure of such a worthy debate. The science certainly will not be decided by this debate, and to declare a winner or loser would not be science by any stretch of the imagination.

Beyond the rebuttals I supplied, which I found to be reasonably, and stick to my limited proof claim, this is quickly turning into independent research for me. Due to my newfound 'definable' contextuality scheme. So I'll answer questions if interested, but this debate does not exist to win, rather for learning, and I have learned more than I could have hoped, thanks to you. If I'm not expressing myself clearly enough to get the quality rebuttals the debate started with, it's time I run with my newfound understanding, and put my money where my mouth is. Thank you for such a worthy debate.

P.S. :tongue:
I understand that your counterfactual C can be run as a separate experiment. But when counterfactually matching it against the previously 'actual' experiment there's a crossover in certain 'instances' where sometimes the photons from B and C should show up as common events (where B and C are calling the same events distinct). Whereas in the individual experiments they were indeed distinct elements of reality. Your calculation, in my interpretation was a statistical count of the percentage of common events to B and C, assuming C is measured on the B side for purposes of definition.

Hopefully that might help, but it's time for me to do something more real than debate it. The computer modeling sounds interesting. :biggrin: If it works the way I hope, I should be able to emulate an expansion series, and express photons as large base 2 quasi-random numbers in a text file. Kind of a finite way to emulate a single quantum bit, with a probability function built into the random variance of a long 0/1 binary sequence. I'll have to limit the angle setting to half angle increments to keep photon number a reasonable size. The code should be simple enough, but why it works, if it does, may still be confusing just from reading the source. But now I'm just running my mouth.

Thanks, it was not only your modeling on your website, but your forcing me to face a perspective other than my own, that give me a new toy that might even pay. At least learn from. I'm off to play.

DevilsAvocado

May25-10, 03:59 PM

I would tend to agree. FTL seems to fill in the cause. As I understand the Bohmian program, it is ultimately deterministic. Randomness results from stochastic elements.

Yes, and if FTL brings cause to Bell test experiments, then either Bell's theorem or FTL goes in the paper bin.

And there seems to be additional dark clouds, gathering up on the "Bell sky"...
(original paper from your site)
III.5 ON THE EINSTEIN PODOLSKY ROSEN PARADOX* (http://www.drchinese.com/David/Bell_Compact.pdf)
John S. Bell
...

VI. Conclusion
In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements, without changing the statistical predictions, there must be a mechanism whereby the setting of one measuring device can influence the reading of another instrument, however remote. Moreover, the signal involved must propagate instantaneously, so that such a theory could not be Lorentz invariant.

Of course, the situation is different if the quantum mechanical predictions are of limited validity. Conceivably they might apply only to experiments in which the settings of the instruments are made sufficiently in advance to allow them to reach some mutual rapport by exchange of signals with velocity less than or equal to that of light. In that connection, experiments of the type proposed by Bohm and Aharonov [6], in which the settings are changed during the flight of the particles, are crucial.

Instantaneously!? Not Lorentz invariant!! ???:confused:???

Not only has QM non-locality 'problems', here goes Einstein, SR and RoS down the drain!?!?

I have absolutely no idea what to think... we must all have missed something very crucial... because all this is too strange to be true... :eek:

DrChinese

May25-10, 04:04 PM

...Regardless, debating you has been far more fruitful and informative than I could possibly have hoped. It's rare for me to have the pleasure of such a worthy debate. ... Thanks, it was not only your modeling on your website, but your forcing me to face a perspective other than my own, that give me a new toy that might even pay. At least learn from. I'm off to play.

I am glad if I was a help in any small way. The point is often to address a different perspective, and in that regard I benefit too. :smile:

DrChinese

May25-10, 04:09 PM

Yes, and if FTL brings cause to Bell test experiments, then either Bell's theorem or FTL goes in the paper bin.

And there seems to be additional dark clouds, gathering up on the "Bell sky"...
(original paper from your site)

Be careful of Bell's comment, which can be EASILY misinterpreted:

"Moreover, the signal involved must propagate instantaneously, so that such a theory could not be Lorentz invariant."

This ONLY applies when coupled with: "In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements..." which is the REALISM requirement.

There is another time in the paper in which a similar dichotomy appears, which also can be read as indicating he is on the non-local side of things. In actuality, he personally went back and forth a bit. But his opinion is not the proper conclusion of the paper, you must stop at the local OR hidden variable point. Does that make sense?

ThomasT

May25-10, 04:16 PM

You can entangle atoms that have not interacted with each other by using interaction-free measurement in an interferometer. Accordingly, these atoms don't interact with the photon in the interferometer either.This is very interesting (reference, link?) and I'd like to learn the setup, but what does this have to do with what I said wrt the FandC and Aspect experiments?

Please recall my statement that entanglement has to do with RELATIONSHIPS between and among the motional properties of entangled entities that result from these entities' interaction with each other or with a common disturbance, or having a common origin, or being part of an encompassing system. These RELATIONSHIPS, when subjected to physical analysis via global measurement parameters, are revealed in the form of correlations predicted by the QM formalism.

My contention is, of course, that any such entanglement RELATIONSHIPS, and observations of them, are compatible with the assumption of locality.

I don't consider it strange or wierd at all that entities that have never interacted with each other can be related in a way or ways such that entanglement stats result when these relationships are observed in certain contexts. The orderliness of our universe suggests that a fundamental wave dynamic(s) underlies all of our universe's emergent complexity, and pervades every epistemic and ontic scale. The essence of entanglement is that everything is related to this fundamental dynamic(s).

I've never considered nonlocality or even ftl locality to be serious contenders in the effort to understand and explain EPR-Bell related conundra. For me it's always been about getting at the physical meaning of 'quantum nonseparability', which has to do with the nonseparability of the relationships between the entangled entities wrt the measurement parameters which reveal those relationships in the form of entanglement stats. So, as long as those relationships can be maintained, or insofar as they can be produced, in entities at great separations, then the revealing of the entanglement correlations via the joint analysis of the relationship(s) between those entities can be understood as evolving via local channels no matter how far apart the joint measurements are done.

ThomasT

May25-10, 04:26 PM

You apparently don't follow Mermin closely. He is as far from a local realist as it gets.

Jaynes is a more complicated affair. His Bell conclusions are far off the mark and are not accepted.I want to say something else about this reply of yours.

It's in response to a rather long post where I laid out what I've been trying to say a bit more clearly, I think. Yet, instead of replying to the substance of the post, to the actual arguments regarding nonviability of lhv theorems per EPR-Bell, you chose this, peripheral, issue to reply to. Very curious.

I'm led to suppose that you're initimidated by the argument that I'm presenting. I'm supposing this because (1) you have yet to directly address it, and (2) in a post of yours you said that I was 'claiming victory' (though I've done no such thing).

So, what is it about the argument that you find so difficult? It can't be that you think that I'm advocating the possibility of lhv theories, because, as I've repeatedly stated, I'm not. In fact, the argument is telling you exactly why lhv theories are impossible. Of course if the argument is correct, then there's no basis for inferring nonlocality.

On the other hand, if the argument isn't difficult or subtle, and if it's obviously incorrect, then why not just refute it outright and maybe I can learn something (you know, point out the error in my thinking). Isn't that what a science advisor is supposed to do?

But instead you said this:

I am through discussing with you at this time. You haven't done your homework on any of the relevant issues and ignore my suggestions. I will continue to point out your flawed comments whenever I think a reader might actually mistake your commentary for standard physics.This isn't about standard physics. I'm pretty sure we agree on the standard physics. We're not arguing about qm or even Bell's theorem, per se. This is an interpretational issue. The interpretation of the physical meaning of violations of BIs that's been presented happens to be based on standard physics. It simply points out a reason for the incompatibility between lhv formulations (as restricted by Bell and EPR elements of reality) that's been noticed by relatively few commentators on the subject. It makes nonlocality unnecessary. Nonlocality is, anyway, neither standard nor nonstandard physics. It isn't physics at all. It's just a word for ignorance of precisely why lhv theories are impossible and why BIs are violated. An interpretation and explanation for this has been presented which doesn't involve invoking nonlocality. So far it's gone unaddressed. Is it possible that what it entails (that the assumption of locality is compatible with the impossibility of lhv theories vis EPR, Bell, GHZ, etc.) isn't nonstandard enough?

Is it possible that Bell is right and nonlocality is wrong? Of course it is, and that's all that I'm saying.

In a local hidden variable model, each observer is measuring a separate reality. So there is no JOINT observable (or context).That's right. (You're almost there.) But entanglement IS a JOINT observational context. (Let that sink in for a moment.)

Now, is what's being measured in the separate measurements at A and B the same as what's being measured jointly?
The answer is no. That's why I said:

.It should become clear that the variables which determine individual detection rates can't be made to (can't be put into a form which would) account for the joint detection rates, because they aren't the determining factors in that situation.

... in a local world, what happens here does not affect what happens there.That's right. But there are only two values for |a - b| where A and B are perfectly correlated (anticorrelated), and these perfect correlations are compatible with the assumption that the relationship between the entangled photons has a local common cause.

But, you might counter, the full range of entanglement stats can't be reproduced by an lhv description of the joint context. And that's correct, but it's because what's being measured in the separate measurements at A and B is not the same as what's being measured jointly.

If there is a "joint detection parameter" observable, it is global. That does not work in a local world either.It works in a local world. It just doesn't work in a local hidden variable theory per EPR-Bell. (1) The joint measurement parameter is |a - b|. (2) What |a - b| is measuring is the relationship between the counter-propagating disturbances. Both (1) and (2) are compatible with the assumption of c-limited locality. However, the relationship between the counter-propagating disturbances doesn't determine individual results.

So you may be correct ...It is correct. But the presentation needs some refining.

... but you are not describing a local realistic model.Hopefully it will become clear that I'm not trying to do that, but rather explain why such a model is impossible, and why the impossibility of constructing such a model doesn't imply nonlocality (or ftl info transfer).

To revisit the Unnikrishnan paper that you didn't want to look at, the purpose of presenting it was to illustrate the point(s) that I've been presenting, not to advocate it as an lhv theory candidate. If you look at it you'll see that it isn't an lhv model in the sense of EPR-Bell. The author even says as much. So it can be taken as further, indirect, evidence that lhv theories per EPR-Bell are impossible. But it is explicitly local. Hence the conclusion: Bell is correct AND nonlocality is obviated.

So, wrt this statement:
There can be no entanglement - in a local realistic world ... I think that a better way to put it is that there can be no local realistic (per EPR-Bell) theories of entanglement in a local realistic world.

ThomasT

May25-10, 04:36 PM

Not only is it "scientific" to posit that Nature is fundamentally nonlocal, it is also the only "logical" thing to do.Regarding your lengthy, interesting, and well written post, I agree that nonlocality is a matter of convenience.

And other than that, I am doing my best to continue the tradition of pushing towards a thoroughly believable ontological theory of physical reality here at physicsforums.And a fine tradition it is. However, my immediate aim, although it might be compatible with this tradition, is simply to understand why lhv theories per Bell-EPR are impossible in a universe which seems to be evolving in accord with the principle of locality. And it turns out, it seems, that this is rather simply explained.

DrChinese

May25-10, 04:45 PM

1. I want to say something else about this reply of yours.

It's in response to a rather long post where I laid out what I've been trying to say a bit more clearly, I think. Yet, instead of replying to the substance of the post, to the actual arguments regarding nonviability of lhv theorems per EPR-Bell, you chose this, peripheral, issue to reply to. Very curious.

I'm led to suppose that you're initimidated by the argument that I'm presenting.

2. To revisit the Unnikrishnan paper that you didn't want to look at, the purpose of presenting it was to illustrate the point(s) that I've been presenting, not to advocate it as an lhv theory candidate. If you look at it you'll see that it isn't an lhv model in the sense of EPR-Bell. The author even says as much. So it can be taken as further, indirect, evidence that lhv theories per EPR-Bell are impossible. But it is explicitly local. Hence the conclusion: Bell is correct AND nonlocality is obviated.

So, wrt this statement:
I think that a better way to put it is that there can be no local realistic (per EPR-Bell) theories of entanglement in a local realistic world.

1. :tongue: :biggrin: You really are making me laff...

2. This paper does not offer a local realistic model. And your thoughts on non-locality are simply an opinion, much like any interpretation would be considered.

DevilsAvocado

May25-10, 04:50 PM

Be careful of Bell's comment, which can be EASILY misinterpreted:

"Moreover, the signal involved must propagate instantaneously, so that such a theory could not be Lorentz invariant."

This ONLY applies when coupled with: "In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements..." which is the REALISM requirement.

There is another time in the paper in which a similar dichotomy appears, which also can be read as indicating he is on the non-local side of things. In actuality, he personally went back and forth a bit. But his opinion is not the proper conclusion of the paper, you must stop at the local OR hidden variable point. Does that make sense?

To be honest – I’m wandering around in a "personal intellectual mud", up to my knees right now.

We’ve eliminated LHV, NLHV, FTL, Loopholes, Malus, etc, and stated that QM is correct.

What’s left!? How does QM solve this unsolvable problem?? I’m going crazy over here... :cry:

I will not believe in MWI before we get a "Hello world!" from a parallel universe (which could take 'awhile')...

What’s your solution??

ThomasT

May25-10, 04:54 PM

1. :tongue: :biggrin: You really are making me laff...You're making my case for me. You still haven't addressed the argument(s).

2. This paper does not offer a local realistic model.No kidding. Maybe you should read the paper, or what I said about it.

To revisit the Unnikrishnan paper that you didn't want to look at, the purpose of presenting it was to illustrate the point(s) that I've been presenting, not to advocate it as an lhv theory candidate. If you look at it you'll see that it isn't an lhv model in the sense of EPR-Bell. The author even says as much. So it can be taken as further, indirect, evidence that lhv theories per EPR-Bell are impossible. But it is explicitly local. Hence the conclusion: Bell is correct AND nonlocality is obviated.

And your thoughts on non-locality are simply an opinion, much like any interpretation would be considered.Again, duh. What do you think your thoughts on nonlocality are?

Of course, if you won't even address the reasons behind the opinion ...

DrChinese

May25-10, 05:00 PM

What’s your solution??

Easy, drink wine and listen to the Beatles.

DevilsAvocado

May25-10, 05:13 PM

Easy, drink wine and listen to the Beatles.

HAHAHA!! :rofl: Non-local wine, right? And the Beatles from the surrealistic period, right? :rofl::rofl:

DrChinese

May25-10, 05:19 PM

HAHAHA!! :rofl: Non-local wine, right? And the Beatles from the surrealistic period, right? :rofl::rofl:

I'm talking sitars!

DevilsAvocado

May25-10, 05:31 PM

I'm talking sitars!

Yeah, I hear you!

http://i43.tinypic.com/ruqhjr.jpg

LMPO :biggrin:

my_wan

May25-10, 06:42 PM

I am glad if I was a help in any small way. The point is often to address a different perspective, and in that regard I benefit too. :smile:
The help wasn't so small, it was instrumental.

zonde

May26-10, 07:17 AM

I would like to pick up this part of discussion as you made similar comment in other thread:
Don't you think the authors would be raising flags if the stats deviated from QM predictions by a significant amount?
I actually wrote Xian-Min Jin asking this question:
"The question is about calibration data of entangled photon source. And exactly this sentence: "The visibilities for the polarization correlations are about 98.1% for |H>/|V> basis and 92.6% for |+45°>/|−45°> basis, without the help of narrow bandwidth interference filters."
Two visibilities seem quite different. So could you please tell me what is the possible reason for this difference in two visibilities?"

And the answer he gave was:
"About the entanglement source, we employ type II SPDC phase match
to generate biphoton. The obtained two photons are either H1V2 or V1H2 with equal probability. So normally we can get very high visibility when we measure H/V basis. If we want make the two photons be entangled, we need to make the two possible events overlap very well at both spatial and temporal modes so that we can not distinguish them any more without measuring their polarization basis. Experimentally, we can not get so ideal condition, that means H1V2 and V1H2 are partially distinguishable. As a result, the entanglement visibility is limitted, this induce that we can not observe perfect correlation at +/- basis. In my experiment, actually, the visibility is considerablely high comparing with previous work, and sufficient for observation of photonics de Broglie wave."

So my answer regarding your comment is that QM prediction on more detailed level includes product state and entangled state as two extremes for the setup of entangled source.
QM prediction a la Bell is just that theoretically you can reach this entangled extreme for the case of efficient detection. And if you do not perform dedicated research you can never find out whether detection efficiency is one of the factors that influences quality of entanglement or not.

DrChinese

May26-10, 08:41 AM

1. I actually wrote Xian-Min Jin asking this question:
"The question is about calibration data of entangled photon source. And exactly this sentence: "The visibilities for the polarization correlations are about 98.1% for |H>/|V> basis and 92.6% for |+45°>/|−45°> basis, without the help of narrow bandwidth interference filters."
Two visibilities seem quite different. So could you please tell me what is the possible reason for this difference in two visibilities?"

And the answer he gave was:
"About the entanglement source, we employ type II SPDC phase match
to generate biphoton. The obtained two photons are either H1V2 or V1H2 with equal probability. So normally we can get very high visibility when we measure H/V basis. If we want make the two photons be entangled, we need to make the two possible events overlap very well at both spatial and temporal modes so that we can not distinguish them any more without measuring their polarization basis. Experimentally, we can not get so ideal condition, that means H1V2 and V1H2 are partially distinguishable. As a result, the entanglement visibility is limitted, this induce that we can not observe perfect correlation at +/- basis. In my experiment, actually, the visibility is considerablely high comparing with previous work, and sufficient for observation of photonics de Broglie wave."

2. So my answer regarding your comment is that QM prediction on more detailed level includes product state and entangled state as two extremes for the setup of entangled source.

QM prediction a la Bell is just that theoretically you can reach this entangled extreme for the case of efficient detection. And if you do not perform dedicated research you can never find out whether detection efficiency is one of the factors that influences quality of entanglement or not.

1. Great stuff, thank you for sharing his comments. I love hearing more details about these experiments.

2. The quality of entanglement can be measured by how close you come to perfect correlations when setting up the experiment. So you might expect that there is always a mix of ES> + PS> statistics (Entangled and Product). Ideally, ES is 100%. But clearly, that ideal is not met in this experiment and the result will be a deviation from the QM predicted rates accordingly. But not enough to cross back into the Local Realistic side of the Bell Inequality.

So are you saying that the detectors somehow influence this? I don't follow that point or what you think the implications would be. It is the setup that determines things, of which the detectors are an element. But their efficiency shouldn't matter to that setup.

my_wan

May26-10, 06:16 PM

After reading about and debating this issue I began to question the difference in perspective that makes some so willing to question the interpretation of Bell's violations, while others see it as unavoidable. I'm not talking about those who simply refuse on the grounds it's too non-physical. It seems to me to involve different ways of thinking about what constitutes an element of reality. I think of emitted photons as conserved numbers of things, independent of what measurements seem to imply. The converse is to think in terms of the measurements as what's physically real, and assume properties back from that. I can think of countless measurable quantities which depend on elements of reality, but do not represent countable elements of reality.

Consider temperature, easily measurable. We know it's the average momentum of molecular collisions, but temperature alone tells us nothing about the number of particles involved. With the Mole unit we know it's mass, but the notion of a single basic unit of existential mass is speculative. Temperature doesn't even tell us the state of matter at that temperature. Some liquid, some solid, some gas, and some plasma. The notion of Bell realism notion seems a stretch, especially once QM is brought in the picture. I also understand it was used in EPR, and why. In some abstract sense we can make Planck's constant, quantum events, the fundamental unit. But as we'll see below this is not allowed under Bell's theorem.

I began reading this and it made some curious points:
Nonlocality, Bell's Ansatz and Probability - http://arxiv.org/abs/quant-ph/0602080

In section III it says this:BELL'S intention when conceiving of his "proof" excluded insinuating, at the meta-level where the inequalities are being derived, any hypothesis not found in classical, local and realistic physics as it was understood before the discovery of QM, where the interpretation issues of QM do not exist. His explicit purpose was to examine the question of the existence of a covering theory that has just the structure exploited by classical, pre-quantum theories.
In fact my argument that EPR could be a local phenomena explicitly depends on the empirical reality of distinctly quantum effects. Albeit quantum effects that occurs distinctly LOCALLY at the particle detection points. Yet, according to this, that doesn't pass the muster for "local realism" for purposes of Bell's inequality. The notion that QM, which no reasonable person could empirically deny, is disallowed from consideration as a LOCAL mechanism for explaining violations of Bell's inequalities is empirically beyond the pale. It's tantamount to requiring a 'complete' classical theory of the entirety of QM to refute the non-local+non-realistic proof by Bell. Irrespective of whether the effects can be fully described by purely local 'quantum' effects. Entirely unreasonable, and empirically unjustifiable.

Here's another point that was fundamental to my argument:Of course, what is not known in this case is the precise polarization of the signal comprising the pair as emitted at the source but before they reach the polarizer-filters. The polarizer settings can be known because they are inputs into measuring devices under the control of the experimenter who selects their orientation before the pair is generated at the source. Seen this way, it is absolutely clear that such detector settings have no effect on the source, and, therefore, have no effect on the pair of signals before they enter the polarizers.
Some may argue the effect issue claimed here, but again, the unknown polarization at the time of emission was a core feature of my argument. Though I did take the consequences much farther.

I do not wish to further defend my poorly explored interpretation at this point. Nor use it as an instrument to portray potentially false impressions of myself or others. But there's a few things to be learned from this debate, you can take to the bank. The mathematical legitimacy of Bell's theorem is irrefutable. The fact of this legitimacy does not translate to any fact of legitimacy about any given interpretation of what it means. The issues involved are open research, and nobody has all the answers, nor fully appreciates all nuances of alternative viewpoints and issues. If it was really that easy it wouldn't be an open area of research, and that's part of what makes it exciting and curious. Strong arguments for what may or may not ultimately be right can be made on both sides of the fence.

Gordon Watson

May26-10, 07:31 PM

... there's a few things to be learned from this debate, you can take to the bank. The mathematical legitimacy of Bell's theorem is irrefutable. The fact of this legitimacy does not translate to any fact of legitimacy about any given interpretation of what it means...

The mathematical legitimacy of Bell's theorem is irrefutable?

Does Bell use P(AB|H) = P(A|H).P(B|H)?

Is P(AB|H) = P(A|H).P(B|H) valid when A and B are correlated?

Are A and B correlated in EPR settings?

my_wan

May26-10, 08:17 PM

The mathematical legitimacy of Bell's theorem is irrefutable?

Does Bell use P(AB|H) = P(A|H).P(B|H)?

Is P(AB|H) = P(A|H).P(B|H) valid when A and B are correlated?

Are A and B correlated in EPR settings?

That depends on how you define H, the nature of the hidden variable that is presumed to be involved in determining the correlation effects between A and B. I would certainly say H is overly restrictive, even in a 'realistic' sense, but others disagree.

The physical validity doesn't have to be legitimate for the mathematical validity to hold, and models which are limited to H, as it is defined here, are indeed invalid. But I was satisfied with that on Neumann's argument alone. That's only the simplest unabashed classical approach anyway. There are plenty of issues with pre-quantum classical physics, from many areas not just restricted to QM, to justify modifications. Even if it still manages to remain essentially classical in character from some perspective. Even Newton had his critiques over the 'magical' elements of classical theory, and background dependence almost certainly has to go.

zonde

May27-10, 05:53 AM

2. The quality of entanglement can be measured by how close you come to perfect correlations when setting up the experiment. So you might expect that there is always a mix of ES> + PS> statistics (Entangled and Product). Ideally, ES is 100%. But clearly, that ideal is not met in this experiment and the result will be a deviation from the QM predicted rates accordingly. But not enough to cross back into the Local Realistic side of the Bell Inequality.
It is not exactly deviation from QM. You see QM covers this PS> state too. So you don't need to resort to some other idea (LHV or anything) in any case.

I have posted this formula couple of times but maybe it will make more sense now in conjunction with real experimental setup.
P_{VV}(\alpha,\beta) = \underset{product\; terms}{\underline{sin^{2}\alpha\, sin^{2}\beta + cos^{2}\alpha\, cos^{2}\beta}} + \underset{interference\; term}{\underline{\frac{1}{4}sin 2\alpha\, sin 2\beta\, \mathbf{cos\phi}}}
This is a bit reduced (without \theta_{l} factor) equation (9) from paper - Entangled photons, nonlocality and Bell inequalities in the undergraduate laboratory (http://arxiv.org/abs/quant-ph/0205171/) that describes type-I PDC source.
The same way can be described type-II PDC. I found this out from Kwiat et al "New High-Intensity Source of Polarization-Entangled Photon Pairs" (I won't post the link to be on the safe side with forum rules about copyrights). There equation (1) is:
|\psi\rangle=(|H_{1},V_{2}\rangle+e^{i\alpha}|V_{1 },H_{2}\rangle)/\sqrt{2}
that is basically the same equation but in more QM format.

As you can see from this first formula cos\phi acts as coefficient in range from -1 to 1 and accordingly this interference term can change it's weight between maximally negative, none at all and maximally positive. QM does not place any restrictions on that.
So if interference term becomes zero and photon state reduces to completely local realistic product state it's still covered by this QM description.
Physical interpretation in QM about this cos\phi coefficient is that it characterizes transverse and longitudinal (temporal) walkoffs.

As experimenter you have a goal to get this cos\phi maximally close to either 1 or -1 and if you do not succeed for some reason then interpretation says you have not compensated those walkoffs to satisfactory level.

So are you saying that the detectors somehow influence this? I don't follow that point or what you think the implications would be. It is the setup that determines things, of which the detectors are an element. But their efficiency shouldn't matter to that setup.
It's hard for me to say something about your comment that efficiency shouldn't be a factor. That's because since some time for me it's not the question of "if" but rather "how". And to be precise it's not only efficiency of detectors but rather coincidence detection efficiency of the setup as whole.

But more to the point, I interpret this interference term as correlation in samples of detected photons meaning that they are uneven. If this unevenness is similar we have positive interference term, if this similarity is inverted we have negative interference term and if we have this unevenness in independent "directions" we don't have interference term. Obviously for efficient detection any "direction" in unevenness of sample is no more detectable.

This loss of information for efficient detection can be illustrated with example like this. Let's say we have a box with different objects in it. We have hole in the box and if we shake the box some objects fall out. Afterward we can look at the objects that are outside the box and objects that are left inside. So we can find out some probabilities whether particular object is more likely to fall out of the box or stay inside. If we always shake the box until all the objects fall out of the box (efficient detection) we loose any information about that falling out probability.

Dmitry67

May27-10, 07:39 AM

What’s left!? How does QM solve this unsolvable problem?? I’m going crazy over here... :cry:

May be I missed something. What is a problem? Nature is not local. I am ok with it.

DrChinese

May27-10, 08:54 AM

The mathematical legitimacy of Bell's theorem is irrefutable?

Does Bell use P(AB|H) = P(A|H).P(B|H)?

Is P(AB|H) = P(A|H).P(B|H) valid when A and B are correlated?

You do NOT need the probability formula to get the Bell result. Despite some of the posts you may have seen, you can get it a variety of ways. For example: if you accept that:

0<=P(A|H)<=1
0<=P(B|H)<=1
0<=P(C|H)<=1

Then you can derive the formula too. A, B and C can be correlated in any way you like. Because then you have:

0<=P(AB|H)<=1
0<=P(AC|H)<=1
0<=P(BC|H)<=1

and then:

0<=P(ABC|H)<=1

But as I have shown previously, this value is less than -.1 (i.e. less than -10%) for some ABC combinations if the QM predictions are substituted. Obviously, a negative value for P(ABC|H) contradicts the above.

DevilsAvocado

May27-10, 12:36 PM

May be I missed something. What is a problem? Nature is not local. I am ok with it.

Hi Dmitry67, the 'problem' is that you believe in MWI, which I don’t, unless you show me a "Hello world!" form one of those >centillion1000 parallel universes! :wink:

ThomasT

May27-10, 12:39 PM

The mathematical legitimacy of Bell's theorem is irrefutable?Wrt the inequalities it is.

Does Bell use P(AB|H) = P(A|H).P(B|H)?Yes.

Is P(AB|H) = P(A|H).P(B|H) valid when A and B are correlated?No.

Are A and B correlated in EPR settings?Yes.

my_wan

May27-10, 12:53 PM

I wonder if this will make the counterfactual assumptions clearer?

You have:
0<=P(A|H)<=1
0<=P(B|H)<=1
0<=P(C|H)<=1

From which this is derived:
0<=P(AB|H)<=1
0<=P(AC|H)<=1
0<=P(BC|H)<=1

But the P(BC|H) case was never performed in tandem, rather constructed from actual measures P(AB|H) and P(AC|H), and even P(BC|H) for good measure, because the correlations come in pairs. Suppose P(AB|H) and P(AC|H) was constructed from a dataset of 1500 correlations pairs each, 3000 photon count "elements of reality" per detector, 6000 total. Now when you combine B and C, you are adding 1500 pairs of "elements of reality" (3000 total) that never actually existed simultaneously but presumably could. By counterfactually assuming they simultaneously occurred in the same dataset, if C can detect the same "elements of reality" (photon) in some, but not all, cases, it becomes impossible to get the "elements of reality", as defined by the measurements, to equal the "elements of reality" as defined by the number of photons.

This is only a valid concern, if and only if, C is sometimes selecting photons that would have also been selected by B, and visa versa, such that if emitted photons AND detections are both to labelled "elements of reality", the count between the two cannot possibly match. In the combined counterfactual case, B and C can effectively be viewed as the exact same detector with 2 different detection settings at once.

If Malus' Law is a valid in defining the odds of a single photon being detectable with two different detector settings, such that a photon with a specific polarization has a 50% chance of passing a polarizer set 45 degrees to its 'actual' polarization, then the derivation of the mismatch in these two ways of counting the "element of reality" almost exactly matched the negative probabilities derivation.

The only difference is that you take the counterfactual "element of reality" set BC, which is 2 settings of the same detector counting the same set of photons, and subtract the total of both the AB and AC set, and you have the percentage of the detector event defined "elements of reality" minus the photon count defined "elements of reality". Z - (X + Y). Divide by 2 to get a per detector percentage, B and C.

I'm not trying to argue this atm, but it would be cool to make the case clear enough to get some effective criticism.

Dmitry67

May27-10, 12:57 PM

Hi Dmitry67, the 'problem' is that you believe in MWI, which I don’t, unless you show me a "Hello world!" form one of those >centillion1000 parallel universes! :wink:

Whats about BM?
Wavefunction is, in any case, non-local.
So MWI or not, nonlocality is inevitable.

I see causality as emergent property of macroscopic world. In that case a-causality is more fundamental, and we are just lucky that our world has causality in IR (macroscopic) limit.

It is curious that the opposite way of thinking is common: "wow, how nature can be non-local! I can't believe!". For me the deeper mystery is why it is causal.

DrChinese

May27-10, 02:47 PM

If Malus' Law is a valid in defining the odds of a single photon being detectable with two different detector settings, such that a photon with a specific polarization has a 50% chance of passing a polarizer set 45 degrees to its 'actual' polarization, then the derivation of the mismatch in these two ways of counting the "element of reality" almost exactly matched the negative probabilities derivation.

The only difference is that you take the counterfactual "element of reality" set BC, which is 2 settings of the same detector counting the same set of photons, and subtract the total of both the AB and AC set, and you have the percentage of the detector event defined "elements of reality" minus the photon count defined "elements of reality". Z - (X + Y). Divide by 2 to get a per detector percentage, B and C.

You cannot get "close" to the negative probability derivation as long as you cling to the idea that:

0<=P(A|H)<=1
0<=P(B|H)<=1
0<=P(C|H)<=1
and Malus.

DevilsAvocado

May27-10, 04:29 PM

Whats about BM?

The future for de Broglie–Bohm theory doesn’t look overwhelmingly bright:
An experimental test of non-local realism (http://arxiv.org/abs/0704.2529)
Anton Zeilinger et.al
...
Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories. Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned.

Add this to Bell’s own conclusion in 1964 (my emphasis):
III.5 ON THE EINSTEIN PODOLSKY ROSEN PARADOX* (http://www.drchinese.com/David/Bell_Compact.pdf)
John S. Bell
...
VI. Conclusion
In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements, without changing the statistical predictions, there must be a mechanism whereby the setting of one measuring device can influence the reading of another instrument, however remote. Moreover, the signal involved must propagate instantaneously, so that such a theory could not be Lorentz invariant.

Then we have to reject Einstein, SR and RoS + the physical experiment by Anton Zeilinger + introducing a global NOW (that we know doesn’t work in e.g. GPS satellites)...

It is curious that the opposite way of thinking is common: "wow, how nature can be non-local! I can't believe!".

It’s not the non-locality in itself that brings 'problem'. It’s the fact that Bell's theorem proves that nature at microscopic QM level must be a-casual/true random/stochastic/non-deterministic, i.e. Local Hidden Variables doesn’t work either in theory or experiment.

Now, if we bring in a "FTL mechanism" as an explanation to what goes on in Bell test experiments – that doesn’t work either! Since a "FTL mechanism" brings cause* to Bell's theorem, where cause is forbidden!!

Get it?

(*Alice sends a FLT-message to Bob to tell him what to do, in respect of what she just did.)

my_wan

May27-10, 04:36 PM

DrChinese

May27-10, 07:54 PM

But the assumption is that P(C|H) is a partial subset of P(B|H) and P(A|H), and partially a set of distinctly unique events. But given that the argument is not being followed, rather that if I cling to what I rejected in the argument, I must be wrong, I have nowhere to go.

If a man is Texan, he can also be a college graduate and a musician. These are not exclusive elements of reality. That is my A, B and C. If I can have these attributes simultaneously, then they are realistic. I would expect that their likelihood would between 0 and 100% inclusively. But if I found out that Texas musicians were less than -10% likely to be college graduates, that would cause me to question things. We like our music here. :biggrin: But we're not so dumb as to appreciate college THAT little.

Gordon Watson

May27-10, 11:49 PM

You do NOT need the probability formula to get the Bell result. Despite some of the posts you may have seen, you can get it a variety of ways. For example: if you accept that:

0<=P(A|H)<=1
0<=P(B|H)<=1
0<=P(C|H)<=1

Then you can derive the formula too. A, B and C can be correlated in any way you like. Because then you have:

0<=P(AB|H)<=1
0<=P(AC|H)<=1
0<=P(BC|H)<=1

and then:

0<=P(ABC|H)<=1

But as I have shown previously, this value is less than -.1 (i.e. less than -10%) for some ABC combinations if the QM predictions are substituted. Obviously, a negative value for P(ABC|H) contradicts the above.

Thank you DrC. I hoped that Bell's mathematics might be clearer to my_wan if we began with fundamental mathematical principles. Is there any good reason why not to begin in that way?

Gordon Watson

May28-10, 12:22 AM

Wrt the inequalities it is.

Yes.

No.

Yes.

Thank you ThomasT, but I am confused. Probably I misunderstand your stand on BT? Are you saying Yes (it is irrefutable, it stands forever), Yes, No, Yes? Is your position logical with your other posts? What about

Q1. Are A and B correlated in EPR settings?

Q2. Does Bell use P(AB|H) = P(A|H).P(B|H)?

Q3. Is P(AB|H) = P(A|H).P(B|H) invalid when A and B are correlated?

Q4. Is the mathematical legitimacy of Bell's theorem debatable?

Dmitry67

May28-10, 12:51 AM

unusualname

May28-10, 08:31 AM

DevilsAvocado,

As I remember Demistifier's arguments, BM is compatible with QM, it is Lorentz-invariant, even in fact there is 'hidden' preferred frame. I don't like it, it is urgly, but it is consistent with all experiments. May be you can ask Demistifier about the interpretation of Bell in BM framework, but I am sure there are no problems.

In any case, SM, BM and MWI is all what is left. SM=giving up updarstanding, BM=ugly, conclusion is...

BM isn't much different to MWI since both are derived from a wavefunction of the universe, which is a bit unappealing, since it seems clear that quantum effects become a statistical non-effect for large particle systems at anything beyond molecular scales. (Although, by intelligent design we will probably improve on nature and build large quantum computers in the near future)

They should have just stuck to de Broglie's original idea of a real guiding wave or even Shrodinger's naive interpretation of a real wave entity, except these days we can validly propose that its existence is generated from signals in other dimensions (or other non-classical space) since all sorts or weird extra dimensions are now being proposed (even if they are compactified, they're extra dimensions, once you propose that I don't see a philosophical reason for not allowing that a noncompactified extra dimension exists which we haven't detected or modelled yet). So we may have a real local theory, except it's not local in einsteinian (classical) space. QED :wink: :smile:

DrChinese

May28-10, 09:04 AM

Thank you DrC. I hoped that Bell's mathematics might be clearer to my_wan if we began with fundamental mathematical principles. Is there any good reason why not to begin in that way?

I agree entirely. I think it is convenient to follow some of the different ways to get to the Bell result, because otherwise the lingo itself can stand in the way. Bell was writing for a very specific audience, whom he knew could follow his wording. He probably assumed they knew EPR as well. So he did not feel the need to spell everything as a non-professional might prefer.

We have a pair of entangled particles, Alice (and her default measurement setting A) and Bob (and his default measurement setting B). We also have a counterfactual setting C (could be associated with either Alice or Bob, doesn't really matter).

Bell says that in a hidden variable theory (and we will use the symmetric case for simplicity):

Alice@A = Bob@A
Alice@B = Bob@C
Alice@C = Bob@C

And further Bell says that these must be simultaneously true if realism applies. Which is just to say that there are hidden variables which exist independently of the act of observation. If the above is true, then there are 8 possible permutations for Alice@A,B or C (using Heads/Tails notation):

HHH, HHT, HTH, HTT, TTT, TTH, THT, THH

There is no particular requirements for their relative frequencies (yet), but we want the sum of these 8 to add to 100% and we want each individual to be within the range 0 to 100%. Again, this is just the realism requirement.

Is the above agreeable?

DevilsAvocado

May28-10, 09:57 AM

... I hoped that Bell's mathematics might be clearer to my_wan if we began with fundamental mathematical principles.

JenniT, I’m sure you mean well, but I can guarantee you that mathematics is not a problem for my_wan. :wink:

DevilsAvocado

May28-10, 10:01 AM

conclusion is...

Ta-da! Aaaaaand the winner is... MWI !! :rofl:

As I said, show me one 'postcard' from any of those +centillion1000 parallel universes, and I’m on the train! :biggrin:

DrChinese

May28-10, 10:28 AM

JenniT, I’m sure you mean well, but I can guarantee you that mathematics is not a problem for my_wan. :wink:

And yet I get confused by the references my_wan makes to ensembles that add to more than 100%. Maybe JenniT's point is worthy, and if not for my_wan, maybe someone else. Because if you start from a local realistic perspective, you must agree to the mathematical ground rules before Bell makes sense. EPR said these ground rules are "reasonable" as an initial hypothesis, and I agree.

So the first point is: Imagine 360 degrees in a circle. For any of the 360: If you ask the same question of Alice and Bob, you get the same answer. Of course, saying there are 360 possible questions is arbitrary, you could just as easily say a billion. The important thing is that these entangled pairs are polarization clones of each other. We don't know the "how", but we can see that they are.

DevilsAvocado

May28-10, 10:54 AM

And yet I get confused by the references my_wan makes to ensembles that add to more than 100%.

That’s a reasonable point. Not to mess things up, I think it’s safest if my_wan answers the question regarding 'confusion' on "more than 100%".

DrChinese

May28-10, 11:14 AM

my_wan

May28-10, 12:03 PM

And yet I get confused by the references my_wan makes to ensembles that add to more than 100%.

It's not just 'an' ensemble. In defining an "element of reality" via realism, the argument involves not only the ensemble, but the the set of individual elements that defines that ensemble, and the differences that occur when you switch from detector event "element" counts and individual photon defined count of elements of reality. If the detector count is double counting certain photons, through couterfactual assumptions, then I am removing "ensembles that add to more than 100%". Only the elements of my ensembles is photons, not detector events. To use detector events the photon double counts must be calced, which your negative probabilities can be interpreted as a count of. I've already pointed out your negative "probabilities" are not "probabilities, but case instances, i.e., elements, derived as individual case instances from a probability function. As well as the fact that the definition of those case instances are: when a detection occurs in one, but not neither or both, detectors.

Thus your proof depends on the existence of negative probabilities possibilities. Whereas the interpretation I suggested removes them when the set of individual elements that defines the ensemble is properly counted.

ThomasT

May28-10, 12:42 PM

Thank you ThomasT, but I am confused. Probably I misunderstand your stand on BT? Are you saying Yes (it is irrefutable, it stands forever), Yes, No, Yes? Is your position logical with your other posts? What about

Q1. Are A and B correlated in EPR settings?

Q2. Does Bell use P(AB|H) = P(A|H).P(B|H)?

Q3. Is P(AB|H) = P(A|H).P(B|H) invalid when A and B are correlated?

Q4. Is the mathematical legitimacy of Bell's theorem debatable?

You asked if the mathematical legitimacy of Bell's theorem is irrefutable. The mathematical form of Bell's theorem is the Bell inequalities, and they are irrefutable. Their physical meaning, however, is debatable.

In order to determine the physical meaning of the inequalities we look at where they come from, Bell's locality condition, P(AB|H) = P(A|H)P(B|H).

Then we can ask what you asked and we see that:
1. A and B are correlated in EPR settings.
2. Bell uses P(AB|H) = P(A|H)P(B|H)
3. P(AB|H) = P(A|H)P(B|H) is invalid when A and B are correlated.

Conclusion: The form, P(AB|H) = P(A|H)P(B|H), cannot possibly model the experimental situation. This is the immediate cause of violation of BIs based on limitations imposed by this form.

What does this mean?

P(AB|H) = P(A|H)P(B|H) is the purported locality condition. Yet it is first the definition of statistical independence. The experiments are prepared to produce statistical dependence via the measurement of a relationship between two disturbances by a joint or global measurement parameter in accordance with local causality.

Bell inequalities are violated because an experiment prepared to produce statistical dependence is being modelled as an experiment prepared to produce statistical independence.

Bell's theorem says that the statistical predictions of qm are incompatible with separable predetermination. Which, according to certain attempts (including mine) at disambiguation, means that joint experimental situations which produce (and for which qm correctly predicts) entanglement stats can't be viably modelled in terms of the variable or variables which determine individual results.

Yet, per EPR elements of reality, the joint, entangled, situation must be modelled using the same variables which determine individual results. So, Bell rendered the lhv ansatz in the only form that it could be rendered in and remain consistent with the EPR meaning of local hidden variable.

Therefore, Bell's theorem, as stated above by Bell, and disambiguated, holds.

Does it imply nonlocality -- no.

DrChinese

May28-10, 12:54 PM

It's not just 'an' ensemble. In defining an "element of reality" via realism, the argument involves not only the ensemble, but the the set of individual elements that defines that ensemble, and the differences that occur when you switch from detector event "element" counts and individual photon defined count of elements of reality. If the detector count is double counting certain photons, through couterfactual assumptions, then I am removing "ensembles that add to more than 100%". Only the elements of my ensembles is photons, not detector events. To use detector events the photon double counts must be calced, which your negative probabilities can be interpreted as a count of. I've already pointed out your negative "probabilities" are not "probabilities, but case instances, i.e., elements, derived as individual case instances from a probability function. As well as the fact that the definition of those case instances are: when a detection occurs in one, but not neither or both, detectors.

Thus your proof depends on the existence of negative probabilities possibilities. Whereas the interpretation I suggested removes them when the set of individual elements that defines the ensemble is properly counted.

I guess I have a different idea of what double counting is. If Alice is counted once and only once, that is good and is not double counting. On the other hand, Alice may be "counterfactually" counted an infinite number of times, and this too is OK as long as the H case and the V case add to 100% for each of the counterfactual cases.

I don't know what you are implying when you say something about "when a detection occurs in one, but not neither or both, detectors". We are discussing the ideal case, so every photon is counted somewhere a single time.

DrChinese

May28-10, 01:15 PM

In order to determine the physical meaning of the inequalities we look at where they come from, Bell's locality condition, P(AB|H) = P(A|H)P(B|H).

Then we can ask what you asked and we see that:
1. A and B are correlated in EPR settings.
2. Bell uses P(AB|H) = P(A|H)P(B|H)
3. P(AB|H) = P(A|H)P(B|H) is invalid when A and B are correlated.

This is not correct because it is not what Bell says. You are mixing up his separability formula (Bell's 2), which has a different meaning. Bell is simply saying that there are 2 separate probability functions which are evaluated independently. They can be correlated, there is no restiction there and in fact Bell states immediately following that "This should equal the Quantum mechanical expectation value..." which is 1 when the a and b settings are the same. (This being the fully correlated case.)

Dmitry67

May28-10, 02:35 PM

Ta-da! Aaaaaand the winner is... MWI !! :rofl:

As I said, show me one 'postcard' from any of those +centillion1000 parallel universes, and I’m on the train! :biggrin:

Show me objects behind the cosmological horizon in the telesope, or I claim that nothing exists behind it :)

Do you believe that Universe ends behind the horizon just because we cant see these obejcts (and will never see in some models)? No, you extrapolate the laws of physics to these areas. Exactly what I do.

RUTA

May28-10, 03:05 PM

Show me objects behind the cosmological horizon in the telesope, or I claim that nothing exists behind it :)

Do you believe that Universe ends behind the horizon just because we cant see these obejcts (and will never see in some models)? No, you extrapolate the laws of physics to these areas. Exactly what I do.

I don't think these are equivalent situations. You don't need anything to exist beyond the particle horizon in cosmology to explain what you see within the particle horizon, GR is a local theory (in the sense of differential geometry). In MWI the existence of the extra universes is germane to the explanation.

The main problem I have with MWI is that pointed out by Adrian Kent, "Theory Confirmation in One World and its Failure in Many" (http://www.perimeterinstitute.ca/Events/The_Clock_and_the_Quantum/Plenary_Talks/). If you really believe MWI, then you have to admit that there's no way you can ever safely infer the "correct" distribution for experimental outcomes because there's no way to know which branch you reside in.

Dmitry67

May28-10, 03:13 PM

I have what to reply, but I dont want to hijack the thread with MWI.
But what is your personal opinion, how do you explain everything?

RUTA

May28-10, 04:22 PM

I have what to reply, but I dont want to hijack the thread with MWI. But what is your personal opinion, how do you explain everything?

This paper (arXiv 0908.4348) explains where I'm at. It's been accepted for presentation at PSA 2010 and was revised and resubmitted to FoP (decision pending). If you don't want to bother with the formalism (it's messy, discrete path integral over graphs), just look at Figures 1-4.

Dmitry67

May29-10, 02:37 PM

RUTA, thank you. THis is interesting, especially:

Probably the most important aspect of the RBW ontology for the
interpretation of quantum physics is that there are no “quantum Clusters,” so there
are no “quantum Objects,” i.e., all Objects are classical and quantum physics is an
exploration of their relational “composition” (Figure 4). This is in stark contrast to
those interpretations of quantum physics which employ dynamical ontological
constituents of the essentially quantum realm (particles, waves, wave-functions,
fields, etc.) with their strange non-commutative properties and struggle to somehow
compose or realize the essentially classical realm of dynamical ontological
constituents with commutative properties. Thus, there simply is no possibility of a
measurement problem(21) on our view (a problem driven by taking quantum
dynamics realistically), and quantum non-separability is ultimately explained
kinematically by the unity of spacetimematter

So it is in the same camp as SM where macroscopic realty is axiomatic.

Could you answer the list of standard questions for any Interpretation for BRW:

http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison

If possible?

DevilsAvocado

May29-10, 07:16 PM

Show me objects behind the cosmological horizon in the telesope, or I claim that nothing exists behind it :)

I think RUTA answers the question neatly (thanks RUTA). Personally I think there’s a huge difference between "much more of the same" and "a magic box where anything is possible, including Boltzmann brains".

And in one of those +centillion1000 parallel universes, I must live forever (escaping every last heart attack into a parallel universe) and have proven MWI wrong, right?? :biggrin:

Dmitry67

May30-10, 01:43 AM

I think RUTA answers the question neatly (thanks RUTA). Personally I think there’s a huge difference between "much more of the same" and "a magic box where anything is possible, including Boltzmann brains".

And in one of those +centillion1000 parallel universes, I must live forever (escaping every last heart attack into a parallel universe) and have proven MWI wrong, right?? :biggrin:

No, there is no difference: in truly infinite universe there are exact copies of you (Max Tegmark had even calculated a distance). In infinite Universe all possibilites are real - you just need to go far enough to find the same earth where you got a Nobel prize or where you spent all your time in prison for armed robbery and murder.

Unifinite Universe with randomness is equivalent in some sense to MWI, because in both cases it forms FULL UNIVERSUM of all options. But for people (beginning from Newton) it was much easier to accept spacial infinity than other types of infinities.

RUTA

May30-10, 11:41 AM

Could you answer the list of standard questions for any Interpretation for RBW:

http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison

If possible?

"Deterministic?" As you can see in Figures 1-4, we assume there may well be a definite collection of relations comprising the experimental equipment, but it's impossible to know exactly what all those relations are in practice. As an analogy, different distributions of velocities for the atoms in a gas can give rise to the same pressure and temperature; it's impossible to know what all the velocities are in any particular distribution in practice. So, in doing QM one is simply asking for the probability of finding a particular relation in a particular trial.

"Wave function real?" No.

"Unique history?" Yes.

"Hidden variables?" Uh, yes and no. There is a fact of the matter concerning the experimental equipment, but there is no "screened-off quantum entity" moving through the device, so the "hidden variables," if you want to use that language, would pertain to the experimental equipment.

"Collapsing wavefunctions?" No.

"Observer role?" Computationally, no. Ontologically, yes, because there is no "God's eye view" of a relational reality -- any observer must be part of that which he observes in a relational reality.

Dmitry67

May30-10, 11:46 AM

In general, the answers are the same (with few minor corrections) as SM?

I would even add:
Macroscopic events are basic irreductable notions - SM-Yes, BRW-Yes.

DevilsAvocado

May30-10, 12:06 PM

... to find the same earth where you got a Nobel prize ...

This sound like a perfect a theory for me!! :rolleyes:

(:wink:)

GeorgCantor

May30-10, 12:40 PM

"Observer role?" Computationally, no. Ontologically, yes, because there is no "God's eye view" of a relational reality -- any observer must be part of that which he observes in a relational reality.

It's as if i heard my full name being called out, when i read this. I think there is only one way to 'interpret' the DCE - it must be about the observer's knowledge of the system being measured. And the fact that the measured 'particles' appear to violate both the concepts of time and space, i think you put it right - 'the observer', there is likely just one. Einstein's relativity favors your position nicely, it's only the common-sense that bent to Hell. Most physicists are very naive; most still believe in real waves or particles. This last statement was made by Zeilinger, though.

RUTA

May30-10, 12:55 PM

In general, the answers are the same (with few minor corrections) as SM?

I would even add:
Macroscopic events are basic irreductable notions - SM-Yes, BRW-Yes.

These are very different interpretations, formally and ontologically. In SM, one uses the free-particle propagator. From section 3.4 of 0908.4348, "We point out again that conventional NRQM uses the free-particle propagator for this case while our two-source amplitude is obtained via the discrete, free (Gaussian) theory fundamental to QFT." And SM is applicable only to non-relativistic QM while our path integral is Poincare invariant (see section 4.3).

RUTA

May30-10, 01:05 PM

It's as if i heard my full name being called out, when i read this. I think there is only one way to 'interpret' the DCE - it must be about the observer's knowledge of the system being measured. And the fact that the measured 'particles' appear to violate both the concepts of time and space, i think you put it right - 'the observer', there is likely just one. Einstein's relativity favors your position nicely, it's only the common-sense that bent to Hell. Most physicists are very naive; most still believe in real waves or particles. This last statement was made by Zeilinger, though.

This illustrates your point nicely. From quant-ph/0505187:

Thomas Jennewein: Quoting A.Z., "Photons are just clicks in photon detectors; nothing real is traveling from the source to the detector." — But what about the energy flowing from the source to the detector?

GeorgCantor

May30-10, 01:42 PM

This illustrates your point nicely. From quant-ph/0505187:

Thomas Jennewein: Quoting A.Z., "Photons are just clicks in photon detectors; nothing real is traveling from the source to the detector." — [b]But what about the energy flowing from the source to the detector[b]?

Whoever asked the question about "energy flowing from the source to the detector" must have meant the relativistic "energy flowing from the source to the detector" that can't be unambiguously quantified in a universal frame of reference. Without a context(observer in a FOR), it seems to make very little sense to talk about particular values of measured entities. But conservation laws still apply, the question is how?

What is your opinion on this question?

RUTA

May30-10, 04:43 PM

Whoever asked the question about "energy flowing from the source to the detector" must have meant the relativistic "energy flowing from the source to the detector" that can't be unambiguously quantified in a universal frame of reference. Without a context(observer in a FOR), it seems to make very little sense to talk about particular values of measured entities. But conservation laws still apply, the question is how?

What is your opinion on this question?

Even if you go to M4, as you say, there is the divergence-free nature of the stress-energy tensor to satisfy (local conservation of energy and momentum). The question Jennewein is raising: How can Zeilinger satisfy local conservation principles with his picture? I don't know whether Zeilinger has answered that question.

RBW is fundamentally nonseparable and the separability of classical physics holds only as a statistical approximation, so you'll only have a divergence-free SET when the classical approximation is valid.

DevilsAvocado

May30-10, 05:21 PM

RUTA

May30-10, 09:44 PM

If the wave function is not real, then how do we explain Afshar experiment (http://en.wikipedia.org/wiki/Afshar_experiment) ?:bugeye:?

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Afshar-experiment-1.png/250px-Afshar-experiment-1.png

As I told DrC in his thread on this subject, in these experiments you construct the wave function for the entire set up -- source, screen, lens, grid, mirrors, detectors. You don't need a story involving any'thing' in addition to the experimental equipment to construct the distribution amplitude of outcomes.

my_wan

May31-10, 01:42 AM

I went through a whole battery of test of LHV. The only one I found to work depended on the polarization of 1 of the detectors to be defined as a 0 angle. Once this condition is imposed, it works without either detector using any information about the other detectors settings. If detector A setting is defined 0 degrees, that could still be 2 different settings as far as the information provided detector B, and B could still be anything from the information provided to A.

It could be argued that this condition implicitly includes the other polarizer setting. But there's a problem with that also. It includes no more information than what can be obtained from a specific photon polarization, knowing that the other is perfectly anti-correlated. Thus not even a FTL mechanism would include more information than can be obtained from a specific correlated/anti-correlated polarization of the photon itself. It seems to be a coordinate property itself.

This could be interpreted as a conflict between coordinate independence and finite non-contextual realism. Any opinions on this issue with LHV's working if we arbitrarily define a 0 setting for 1 detector, or how a FTL mechanism can possibly provide more information than what this does?

zonde

May31-10, 05:57 AM

I went through a whole battery of test of LHV. The only one I found to work depended on the polarization of 1 of the detectors to be defined as a 0 angle.
Why do you think this should work?
To test Bell or let's say rather CHSH inequalities you have to change settings of polarizer. Once you change settings for your reference polarizer then if you change your reference so that new settings remain 0 angle you have to transform whole setup including source (and including photons in transit).
Anyways how does it help with hypothetical additional (counterfactual) measurements that clearly lead to contradictions?

my_wan

May31-10, 08:42 AM

Why do you think this should work?
To test Bell or let's say rather CHSH inequalities you have to change settings of polarizer. Once you change settings for your reference polarizer then if you change your reference so that new settings remain 0 angle you have to transform whole setup including source (and including photons in transit).
Anyways how does it help with hypothetical additional (counterfactual) measurements that clearly lead to contradictions?

Yes, true. It has to do with the way the photon is defined in the model I used. The photon number began with a random polarization and a 180 digit binary number, 1 for each 1/2 degree polarization over 90 degrees. Reversed for some angles over 90 degrees. The photon was assumed to have a particular polarization, defined such that a polarizer at that same angle essentially had a 100% chance of passing that polarizer. If the polarizer detector was offset from that photon polarization, say 22.5 degrees, the binary number at that location had ~85% chance of being a 1 at that binary offset for any given random photon.

The 0 polarization definition condition essentially meant that the side of the formula that was non-zero used the relative offset between the 2 detectors. The 0 setting always returned the first column in the binary number, while the other returned essentially the binary relative offset. Thus any relative settings could be used, as long as 1 of them was defined to be zero.

Any attempt at retrieving the relative offset from settings without a defined 0 polarizer setting required information about the other polarizer setting. Thus this is a situation where, in order for nature to be coordinate independent, only relative settings are meaningful. Yet, for the math to work with finite absolute variables, requires 1 of 2 special coordinate choices. From this perspective, it could be said that coordinate independence requires either a violation of Bell's inequalities, or very different empirical results, from physically identical experiments, simply due to a change in coordinate choices.

I still may be missing something, but I attempted to make only half binary bit in the first column 1's, such that only those with 1's in that location were detected and counted at that detector setting. The detection statistics wouldn't balance out properly to violate Bell's inequalities under arbitrary settings, without or without a 0 degree polarizer setting. These are still absolute finite variables I presupposed, with contextually defined solely in terms of which absolute variables in a set was read. Under relativity this quantization of contextually doesn't follow, but under QM it could in principle.

With these hidden variables it's trivial to define 1 detector or the other as 0 degrees using the photon polarization offset from the first pair of correlated photons at 1 detector, and the perfect anti-correlation defines where that same 0 angle is at the other detector. Thus it's extremely hard to define how a FTL 'real' mechanism would provide more information than already contained here. Which leads me in other directions.

I wonder what classical analogs can be defined, using just coordinate independence and relativity?

DrChinese

May31-10, 09:50 AM

Yes, true. It has to do with the way the photon is defined in the model I used. The photon number began with a random polarization and a 180 digit binary number, 1 for each 1/2 degree polarization over 90 degrees. Reversed for some angles over 90 degrees. The photon was assumed to have a particular polarization, defined such that a polarizer at that same angle essentially had a 100% chance of passing that polarizer. If the polarizer detector was offset from that photon polarization, say 22.5 degrees, the binary number at that location had ~85% chance of being a 1 at that binary offset for any given random photon.

The 0 polarization definition condition essentially meant that the side of the formula that was non-zero used the relative offset between the 2 detectors. The 0 setting always returned the first column in the binary number, while the other returned essentially the binary relative offset. Thus any relative settings could be used, as long as 1 of them was defined to be zero.

Any attempt at retrieving the relative offset from settings without a defined 0 polarizer setting required information about the other polarizer setting. ...

I still may be missing something, but I attempted to make only half binary bit in the first column 1's, such that only those with 1's in that location were detected and counted at that detector setting. The detection statistics wouldn't balance out properly to violate Bell's inequalities under arbitrary settings, without or without a 0 degree polarizer setting. These are still absolute finite variables I presupposed, with contextually defined solely in terms of which absolute variables in a set was read. Under relativity this quantization of contextually doesn't follow, but under QM it could in principle.

With these hidden variables it's trivial to define 1 detector or the other as 0 degrees using the photon polarization offset from the first pair of correlated photons at 1 detector, and the perfect anti-correlation defines where that same 0 angle is at the other detector. Thus it's extremely hard to define how a FTL 'real' mechanism would provide more information than already contained here. Which leads me in other directions.

Good work on creating the simulation. I think these are very helpful in seeing how constraining the Bell work is. That 85% you mention for 22.5 degrees is still 10% too high for local realism (which has a limit of 75%). In other words, your model will show an unusually low correlation between 22.5 degrees and 45 degrees - one which is less than 75% and therefore substantially different than the expected 85% (since 0/22.5 cases should match the 22.5/45 degree cases on average).

You should be able to conclude that your model cannot provide pairs that match the QM rates for arbitrary pairs of angles. Having your model work for 0 degrees is tantamount, of course, to signaling Alice's setting to Bob (which we wish to avoid).

Thanks for taking the time out to run this.

my_wan

May31-10, 12:30 PM

Good work on creating the simulation. I think these are very helpful in seeing how constraining the Bell work is. That 85% you mention for 22.5 degrees is still 10% too high for local realism (which has a limit of 75%). In other words, your model will show an unusually low correlation between 22.5 degrees and 45 degrees - one which is less than 75% and therefore substantially different than the expected 85% (since 0/22.5 cases should match the 22.5/45 degree cases on average).

You should be able to conclude that your model cannot provide pairs that match the QM rates for arbitrary pairs of angles. Having your model work for 0 degrees is tantamount, of course, to signaling Alice's setting to Bob (which we wish to avoid).

Thanks for taking the time out to run this.

This kind of begs the question of what constitutes FTL. I agree that on the surface requiring 0 degrees appears tantamount to signaling Alice's setting to Bob. Yet the information to do that, at least in principle, is contained in the default polarizations of the photon (sort of). Consider 2 factors here, above and this:

When you define 2 arbitrary polarizations, such as 22.5 and 30, this already requires using a common coordinate where both detectors agree on where the settings representing 22.5, 30 and all other settings, including 0 is. So even arbitrary setting requires FTL information of some sort, albeit predefined. We don't consider this FTL because space has covariant symmetries wrt various coordinate systems. Yet, in the EPR case, relative covariance is maintained, i.e., difference in detector settings, but covariance with the numerical labels we put on that coordinate system is broken. It makes our coordinate system look broken in this respect.

I don't care for this, but, extra spacial dimensions can produce this effect. I personally think it's more likely points on our coordinate system are not distinct points, but dynamic vectorial creations (real wavefunction sort of). This, of course, begs the question of why the unit vectors in Hilbert space, in QM, and still allow the limits of calculus.

The way I constructed the HV's in the photons allows any level of violation of Bell's inequalities. I defined photons by a default polarization, followed by a binary digit for each angle available to the detector. So a random number generator, min/max=0/1, that exceeded the Malus' Law for that angle was set to 0. So I did match the QM rates for any arbitrary angle 'difference', but only when the difference was definable. This begs the question, paragraph 2, why the coordinate independent difference requires FTL when 2 coordinate system that must share the same definition of any angle does not. Given the way I defined a default photon polarization, that hits any polarizer at some angle, getting through or not, and the fact that the other photon had exactly the opposite polarization, then a polarization of each detector independently is defined by HV of the photons that hit them. All the information is there, and all that is required to calculate violations of Bell's inequalities is to choose 1 to call 0. It doesn't even matter which 1 is labeled 0, or what actual angle that 0 represents.

This is similar to defining the a relative velocity between 2 inertial observers. You can define the velocity of either inertial observer as 0, but it is senseless to define both as 0 at the same time. If the only way to measure the momentum of an inertial observer was to put something bigger in front of it, then you would have a situation somewhat more like measuring the properties of a photon. In relativity we have Lorentz transformations. In EPR we have QM, or Malus' Law with some added assumptions about properties and interactions like I used.

Given information obtainable from the difference between a presumed default photon polarization and detector setting, plus a partner photon with exactly opposite default polarization, how could a FTL mechanism possibly add more information? In fact the only extra information required is not about polarizations, etc., but which way is "really" up in space, which is nonsensical. Especially given that, even for the LHV, any answer about which way is "really" up is just as good as any other.

DevilsAvocado

May31-10, 02:26 PM

... Given information obtainable from the difference between a presumed default photon polarization and detector setting, plus a partner photon with exactly opposite default polarization, how could a FTL mechanism possibly add more information? In fact the only extra information required is not about polarizations, etc., but which way is "really" up in space, which is nonsensical. Especially given that, even for the LHV, any answer about which way is "really" up is just as good as any other.

Please feel free to laugh (:redface:). This is only a layman’s 'feeling' of how we maybe can find a clue to this problem. There are no real mathematical theories behind this, just a "personal guess".

We know that the two entangled photons share the same wave function (I hope!?). In the double-slit experiment, one wave function of one particle (photon) goes thru two slits to create interference with itself.

In EPR we have one wave function with two photons, in each end, going in opposite direction. What if the wave function is the holder of the "default angle reference", i.e. what’s "up and down"??

If we look at this animation of a sine wave, the rotating circle is moving to create a sine wave, but it’s very easy to imagine the circle standing still and rotating, and the sine wave is moving forward to hit at a specific angle.

http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/ComplexSinInATimeAxe.gif/450px-ComplexSinInATimeAxe.gif

This translated to QM and EPR/BTE would be that the sine wave is the wave function and the probability distribution for a certain outcome.

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Standard_deviation_diagram.svg/500px-Standard_deviation_diagram.svg.png

If this works, there is no need for a FTL mechanism, since the "default angle reference" is in the wave function itself, and travels in both directions simultaneously, and there is no need for LHV, and the outcome is true random.

Pretty nice, huh? :rolleyes:

Now the BIG question is – how many are laughing their pants off right now, respective applauding...?? :biggrin:

my_wan

May31-10, 03:25 PM

Please feel free to laugh (:redface:). This is only a layman’s 'feeling' of how we maybe can find a clue to this problem. There are no real mathematical theories behind this, just a "personal guess".

We know that the two entangled photons share the same wave function (I hope!?). In the double-slit experiment, one wave function of one particle (photon) goes thru two slits to create interference with itself.

In EPR we have one wave function with two photons, in each end, going in opposite direction. What if the wave function is the holder of the "default angle reference", i.e. what’s "up and down"??

If we look at this animation of a sine wave, the rotating circle is moving to create a sine wave, but it’s very easy to imagine the circle standing still and rotating, and the sine wave is moving forward to hit at a specific angle.

http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/ComplexSinInATimeAxe.gif/450px-ComplexSinInATimeAxe.gif

This translated to QM and EPR/BTE would be that the sine wave is the wave function and the probability distribution for a certain outcome.

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Standard_deviation_diagram.svg/500px-Standard_deviation_diagram.svg.png

If this works, there is no need for a FTL mechanism, since the "default angle reference" is in the wave function itself, and travels in both directions simultaneously, and there is no need for LHV, and the outcome is true random.

Pretty nice, huh? :rolleyes:

Now the BIG question is – how many are laughing their pants off right now, respective applauding...?? :biggrin:

Yes this is fairly near the way I was modeling it, with some distinct differences.

The rotation you see didn't have to exactly match the polarizer in my LHV modeling. It had some chance of getting through if it was within + or -90 degrees, with a bit set at creation time to determine if it would at any given angle. It's the only (classical) way for 1 polarizer setting to pass 50% of the randomly polarized photons that hit it. The big picture is quiet similar though. It still only works, at least as far as I was able to model, when one of the polarizers was defined to be set at 0. Though it didn't matter what actual angle 0 represented.

Still trying to think up some weird stuff to make it work more clearly, but I'm suspecting it's a more fundamental issue with coordinate independence. Perhaps even a coordinate transform from an element in Hilbert to classical space |\psi(x)|^2, if we define that as real. It would mean that observables are not direct representations of the 'real' parts of the Universe. I considered defining a bias in the emitter that sets a defined constant angle for all photons somehow. But I'm not really seeing it adding usable information beyond what it already has, because it is a detector angle that must be defined 0. Same reason FTL real mechanisms don't necessarily help.

ThomasT

May31-10, 04:39 PM

Now once you agree that Alice and Bob are ENTANGLED, i.e. they are clones of each other and always yield the same answer to the same question, then you ask: HOW can that happen?

There are 3 basic ways:

a) All measurements give the same answers. We know this isn't true because ONLY entangled pairs have this property, and the answers appear random. So "lucky" guesses are ruled out. If you have collusion between the observers, then this can be gamed. So you have to convince yourself this case is not happening. This is usually handled by a proper experimental setup.

b) Alice and Bob are clones of each other, but otherwise are completely independent. They are local/separate and must therefore have ALL the answers encoded in advance a la EPR. This is the case Bell addresses.

c) Alice and Bob are in communication with each other somehow, and so when Alice answers a question, she shares her answer with Bob. Bell does not address this case. Now, there are other ways to get this result besides instantaneous action-at-a-distance, such as retrocausal and other interpretations. I don't want to discuss any of these in this thread if it can be avoided.

Another alternative is:

Alice and Bob are clones of each other, but otherwise are completely independent. They are local/separate, but the relationship between them is an underlying, or hidden. joint parameter which, when analyzed by a joint measurement parameter (say, the relationship, or angular difference, between crossed polarizers) results in entanglement stats, P(A,B), which are not independent because of what's being measured (the difference between Alice and Bob ... none -- they're clones of each other) and how it's being measured.

Say Alice and Bob are counter-propagating sinusoidal (light) waves that share a cloned property, eg., they're identically polarized. Analyze this cloned property with crossed polarizers and you get entanglement correlation. Cos^2 |a-b| in the ideal. It's just optics. Not that optics isn't somewhat mysterious in it's own right. But we can at least understand that the entanglement stats so produced don't have to be due to Alice and Bob communicating with each other, or that nonseparability means that Alice and Bob are the same thing in the sense that they're actually physically connected when they reach the polarizers..

Bell didn't address this case, because it's precluded by the EPR requirement that lhv models of entanglement be expressed in terms of parameters that determine individual results.

Bell showed that there's an inevitable boundary imposed on formal models that express joint results in terms of individual results. That boundary is expressed in Bell inequalities, and crossed by qm predictions and experimental results.

On the other hand, since a local realistic computer simulation of an entanglement preparation is not the same as a local realistic formal model (in the EPR sense), then it wouldn't be at all surprising if such a simulation could reproduce the observed experimental results, and violate a BI appropriate to the situation being simulated -- and this wouldn't contradict Bell's result, but, rather, affirm it in a way analogous to the way real experiments have affirmed Bell's result.

ThomasT

May31-10, 04:40 PM

This is not correct because it is not what Bell says. You are mixing up his separability formula (Bell's 2), which has a different meaning. Bell is simply saying that there are 2 separate probability functions which are evaluated independently. They can be correlated, there is no restiction there and in fact Bell states immediately following that "This should equal the Quantum mechanical expectation value..." which is 1 when the a and b settings are the same. (This being the fully correlated case.).

Bell illustrated that, for EPR settings, the form (2) can reproduce the qm predictions without assuming nonlocality. For EPR settings, the analogous probability expression doesn't reduce to P(AB|L) = P(A|L)P(B|L).

The form P(AB|L) = P(A|L).P(B|L) is analogous to the form of Bell's (2) wrt at least one salient feature that Bell incorporated in (2). The separability, or independence, of the data sets, A and B. Because it's analogous wrt this feature of (2) it might be used to, say, illustrate the incompatibility of that form wrt the modelling requirements of entanglement experimental situations.

And insofar as the probabilities are conditioned on L, then it seems that it's also analogous to the predetermination feature of Bell's (2).

Bell's (2) isn't just a 'separability formula'. It's the form (which encodes separable predetermination) that any lhv (per EPR elements of reality) model of entanglement has to be rendered in. The main result of his paper involved proving that the form (2) can't possibly reproduce all the qm predictions wrt the experimental (entanglement) situation that he was considering. The EPR requirement that Bell adhered to is that the joint, entangled, experimental situation be modelled in terms of parameters that determine individual results. The proof involved demonstrating that a certain boundary, which he denoted as 'epsilon', can't be made arbitrarily small if you model entanglement situations in terms of parameters that determine individual results.

It was possible for Bell to prove this, formally, precisely because the parameters that determine individual results are different than the parameters that determine joint results.

Here's one way to phrase it. Bell's theorem means that joint experimental situations which are prepared to produce and which do produce (and for which qm correctly predicts) entanglement stats can't be viably modelled in terms of parameters which determine individual results because, simply put, those different experimental situations are measuring different things.

Does Bell's result imply anything about what does or doesn't exist in Nature. No.

What Bell showed is that even if Einstein's ideas about the 'incompleteness' of qm and the contiguity of a fundamental medium (and the principle of local action) are true, it's still also true that lhv theories of entanglement are impossible.

How can both Einstein and Bell be right? The reasons have already been presented. But, we can also look at what Bell did not show.

Bell did not show that local realistic (but not realistic in the sense of the EPR requirement) nonseparable theories of entanglement are impossible. The experimental preparation of entanglement doesn't, per se, require models thereof to be rendered in terms of EPR elements of reality. It isn't constrained by the lhv requirement of modelling the situation in terms of parameters which determine individual results. Entanglement situations can be viably modelled in terms of locally produced underlying relationships between disturbances that are jointly analyzed by global measurement parameters. It's this sort of 'realistic nonseparability' (based on a certain understanding of the actual physics involved, and not some sort of 'nonlocal connection') that is the conceptual foundation on which the qm description of entanglement is based.

DevilsAvocado

May31-10, 05:14 PM

Still trying to think up some weird stuff to make it work more clearly, but I'm suspecting it's a more fundamental issue with coordinate independence.

I always thought of the wave function as 'sine wave' propagating in space, maybe childish and/or wrong. On the other hand, if we look at double-slit experiment, the wave function behaves very much like water wave interference:

http://upload.wikimedia.org/wikipedia/commons/2/2c/Two_sources_interference.gif

Maybe it was misleading with the very strong bound between "the rotating circle and the sine wave", but think of the propagating wave function as 'predefined' probabilities acting in a certain manner, in a certain situation – the wave function 'knows' what it can do, and cannot.

And the entangled partner has the exact, but mirrored, information.

Now, when the wave function reaches Alice polarizer, it doesn’t care one bit about "up & down", it 'knows' the probabilities for any angle Alice polarizer can have – and starts 'executing' that 'probability generator' on Alice’s polarizer.

And the entangled partner executes the exact, but mirrored, 'probability generator' on Bob’s polarizer.

Now how come the entangled photons always and exactly show inverse values when measured along the same axis??

Easy – the entangled photons doesn’t care about Alice or Bob, they only have their probability distribution to care about – and these probability distributions are mirrored!

Meaning, they will always behave in a mirrored way under exactly the same conditions, whatever they may be – i.e. any axis 0º - 360º.

(...I don’t know if this ever going to work in theory and/or practice, but maybe a start for 'something'... :uhh:)

DevilsAvocado

May31-10, 05:39 PM

As I told DrC in his thread on this subject, in these experiments you construct the wave function for the entire set up -- source, screen, lens, grid, mirrors, detectors. You don't need a story involving any'thing' in addition to the experimental equipment to construct the distribution amplitude of outcomes.

The 'trouble' I see with this explanation is that changes in the set up in a real way (wires), creates real changes in the outcome... To me this indicates the wave function must "be there" to produce these changes... (as much as a water wave is real)

Look at this picture, and hopefully you see what I’m aiming at:

zonde

Jun1-10, 03:08 AM

When you define 2 arbitrary polarizations, such as 22.5 and 30, this already requires using a common coordinate where both detectors agree on where the settings representing 22.5, 30 and all other settings, including 0 is. So even arbitrary setting requires FTL information of some sort, albeit predefined. We don't consider this FTL because space has covariant symmetries wrt various coordinate systems. Yet, in the EPR case, relative covariance is maintained, i.e., difference in detector settings, but covariance with the numerical labels we put on that coordinate system is broken. It makes our coordinate system look broken in this respect.
No, common reference does not require FTL. Common reference is established when you set up experiment. You measure birefringence of fiber that is used to transport photons from source to measurement site. And you compensate birefringence of fiber to establish common reference.
For example imagine that fiber is arranged so that at one site of measurement photons are received from up direction and polarizer is rotated in horizontal plane. In that case you simply establish common reference by finding out what is the angle of polarization for photons that come out of the fiber given certain angle of polarization for photons that go into the fiber at the other end.
So common reference is established by setup of experiment. Nothing like FTL.

RUTA

Jun1-10, 07:42 AM

The 'trouble' I see with this explanation is that changes in the set up in a real way (wires), creates real changes in the outcome... To me this indicates the wave function must "be there" to produce these changes... (as much as a water wave is real)

Look at this picture, and hopefully you see what I’m aiming at:

Changes in the set up are all that you need to change the distribution of outcomes -- you don't need any 'thing' other than equipment characteristics, i.e., no reference to quantum entities, waves, etc. For example, see section 4.3 Geometrical Account of QLE starting on p 28 of our FoP paper, http://users.etown.edu/s/stuckeym/FOP%202008.pdf. In particular notice how how Eq. 31 becomes Eq. 32 on p. 29.

DrChinese

Jun1-10, 08:41 AM

The way I constructed the HV's in the photons allows any level of violation of Bell's inequalities. I defined photons by a default polarization, followed by a binary digit for each angle available to the detector. So a random number generator, min/max=0/1, that exceeded the Malus' Law for that angle was set to 0. So I did match the QM rates for any arbitrary angle 'difference', but only when the difference was definable.

Maybe we are not saying the same thing. Of course you DON'T have HV values for arbitrary thetas. I already gave you one set, 0/22.5/45. You got 85% for 0/22.5, so you must have about 65% for 22.5/45.. which is incorrect of course. That's the point, you cannot have the ratios work out in your model unless you use 0 as one of the two points. If those work, others will not.

my_wan

Jun1-10, 01:26 PM

Maybe we are not saying the same thing. Of course you DON'T have HV values for arbitrary thetas. I already gave you one set, 0/22.5/45. You got 85% for 0/22.5, so you must have about 65% for 22.5/45.. which is incorrect of course. That's the point, you cannot have the ratios work out in your model unless you use 0 as one of the two points. If those work, others will not.

Yes, but all the photons default polarization are perfectly randomized, so it makes no difference which polarization you call 0. So by labeling 22.5/45, your assuming 22.5 has absolute meaning to a relative value. Consider this analogy:

You have 3 inertial observers A, B, and C. Relative to A, B and C is going 85 km/hour and 50 km/hour respectively. This doesn't mean relative to B that C is going 15 km/hour or 135 km/hour. So when you say: 22.5/45 is incorrect you are in a sense correct. For the same reason it's incorrect to say relative to B, B and C have velocities of 85 km/hour and 50 km/hour respectively.

Similar to the velocity vectors above, the photon interaction with a polarizer is the product of a vector space, and the 0 condition is not fundamentally different from a 0 self velocity of an inertial observer. So 22.5/45 is 0/22.5. You can't say that means the original 0 angle, in 0/22.5/45, must then match coincidences 100%, any more than you can say 2 inertial observers with 0 self velocity must then have 0 relative velocity wrt each other.

You specifically violated the condition I specified for it to work, to demonstrate it wouldn't work that way. Because this is ostensibly predicated on Bell's realism, i.e., pre-QM classical physics, I justified this required condition with 3 purely classical objects with a measurable property (velocity).

Of course it could be argued a detection either happens or doesn't, unlike velocity. With detector settings 0/90, each is detecting a different 50% of the photons. If you move 0->22.5 and 90->110.5, then the 50% of photons being detected by 22.5 is a different 50% than what was detected at 0. Yet it remains exactly that 50% not being detected at 110.5. Same for any settings, like 0/22.5. Even if you maintain that classical type hidden variables can't mimic this, this is exactly what QM predicts to happen in photon detection statistics with a 'single' polarizer being rotated in single beam of randomly polarized light. That is that a photon that passes a polarizer at 0 has a ~85% chance of passing that same polarizer at 22.5. This is without a correlated pair in existence at all to communicate with FTL. Thus, it's certain that the detection statistics are a local QM phenomena, local to the way a photon interacts with a polarizer. Yet whatever this local phenomena, it's deterministically replicable in a perfectly (anti)correlated particle.

DrChinese

Jun1-10, 01:48 PM

Yes, but all the photons default polarization are perfectly randomized, so it makes no difference which polarization you call 0. So by labeling 22.5/45, your assuming 22.5 has absolute meaning to a relative value..

It does matter IF you won't get the QM predicted values, which you won't.

All I ask is that the percentage of matches between 0/22.5 match the percentage from 22.5/45 and that the 0/45 matches are 50%. Your model does not do this for any dataset with more than about 20 items. You should acknowledge that is so. I assume you now understand why such a dataset is not possible.

DrChinese

Jun1-10, 02:27 PM

my_wan

Jun1-10, 02:57 PM

It does matter IF you won't get the QM predicted values, which you won't.

All I ask is that the percentage of matches between 0/22.5 match the percentage from 22.5/45 and that the 0/45 matches are 50%. Your model does not do this for any dataset with more than about 20 items. You should acknowledge that is so. I assume you now understand why such a dataset is not possible.

And all I ask is that if you and I both have 0 self momentum, we must not have any momentum relative to each other. Even with plain old Galilean Relativity, it's not a very reasonable thing to ask is it?

And all I ask is that if our relative velocity is 30 km/hour, and we both increase our velocity by 30 km/hour, our relative velocity must remain unchanged. Not a very reasonable thing to ask is it.

Yet I do get QM predicted values, if I'm allowed to define ANY angle as 0, just like any inertial observer can describe their velocity as 0. If I change my definition of my velocity by X, it does not mean it changes my measurement of your velocity by X. Same with linear changes in relative polarizer angles.

So why demand even stricter linearity in measureables than what even Galilean Relativity supports? Fundamentally all EPR correlations measure is how many of the 50% of photons a polarizer detects overlaps with different polarizer settings. Yet, counterfactually, it is being presumed that the same subset of photons, with a common detection overlap, are involved with 2 different detector settings.

DrChinese

Jun1-10, 03:02 PM

And all I ask is that if you and I both have 0 self momentum, we must not have any momentum relative to each other. Even with plain old Galilean Relativity, it's not a very reasonable thing to ask is it?

And all I ask is that if our relative velocity is 30 km/hour, and we both increase our velocity by 30 km/hour, our relative velocity must remain unchanged. Not a very reasonable thing to ask is it.

Yet I do get QM predicted values, if I'm allowed to define ANY angle as 0, just like any inertial observer can describe their velocity as 0. If I change my definition of my velocity by X, it does not mean it changes my measurement of your velocity by X. Same with linear changes in relative polarizer angles.

So why demand even stricter linearity in measureables than what even Galilean Relativity supports? Fundamentally all EPR correlations measure is how many of the 50% of photons a polarizer detects overlaps with different polarizer settings. Yet, counterfactually, it is being presumed that the same subset of photons, with a common detection overlap, are involved with 2 different detector settings.

I truly have no idea what you are talking about. I am discussing polarization, not velocity or relativity. If you generated a realistic dataset that works like real QM does, then simply show it. It is easy for me to request this since I KNOW you don't have it.

And why do you talk about the 50% detected? There is no 50%! They are ALL detected!! The relevant issue is subensembles of the entire universe.

my_wan

Jun1-10, 04:45 PM

I truly have no idea what you are talking about. I am discussing polarization, not velocity or relativity. If you generated a realistic dataset that works like real QM does, then simply show it. It is easy for me to request this since I KNOW you don't have it.

And why do you talk about the 50% detected? There is no 50%! They are ALL detected!! The relevant issue is subensembles of the entire universe.

So what you are saying here is that the a giver polarizer setting passes all photons at that polarization? No, a given polarization setting passes 50% of a randomly polarized beam of light. A polarization setting at 90 degrees to that will pass exactly the other 50%. Thus any setting between those 2 must pass some of the photon at the 0 setting, and some from the 90 setting. This is true with or without classical mechanisms. See a visual here:
http://www.lon-capa.org/~mmp/kap24/polarizers/Polarizer.htm

The only thing to explain, per Bell's ansatz, is why the transition between 0 and 90 is not, counterfactually, linear with changes in the angle. The exact same paradox exist, in that polarizer applet above, when you add a second inline polarizer and notice that, with arbitrary offsets from the first polarizer, the percentage of the photons passing both polarizers do NOT fall off linearly between 0 and 90. EXACTLY the same non-linearity seen in EPR correlations, without ANY correlated photons. Yet EPR correlations indicate this is deterministically replicable if the photons are exactly (anti)correlated. But it is a LOCAL non-linearity producing it, exactly as seen in that applet.

Unlike the restrictions of Bell's realism, I include 'LOCAL' QM effects as valid effects to explain this non-linearity with. If nature is defined as a 'real' pure field, how can you expect properties to be linear representations of parts? If the relevant is "subensembles", we are likely not dealing with a finite Universe, even on the microscopic scale. But that is, in itself, not a violation of realism. Einstein did build GR as a causally connected field theory, however problematic that is for quantization.

DrChinese

Jun1-10, 04:56 PM

So what you are saying here is that the a giver polarizer setting passes all photons at that polarization? No, a given polarization setting passes 50% of a randomly polarized beam of light. A polarization setting at 90 degrees to that will pass exactly the other 50%. Thus any setting between those 2 must pass some of the photon at the 0 setting, and some from the 90 setting. This is true with or without classical mechanisms. See a visual here:
http://www.lon-capa.org/~mmp/kap24/polarizers/Polarizer.htm

I keep trying to tell you that this is NOT how most real experiments are performed. Polarizing beam splitters are used. 100% of the light emerges, and it goes one way or another. That way, there is no question that there is a match.

You are creating artificial confusion by talking about the counterfactual "overlapping" or whatever it is. In fact, Alice and Bob are always counted (ideal case of course).

DrChinese

Jun1-10, 05:07 PM

The exact same paradox exist, in that polarizer applet above, when you add a second inline polarizer and notice that, with arbitrary offsets from the first polarizer, the percentage of the photons passing both polarizers do NOT fall off linearly between 0 and 90. EXACTLY the same non-linearity seen in EPR correlations, without ANY correlated photons. Yet EPR correlations indicate this is deterministically replicable if the photons are exactly (anti)correlated. But it is a LOCAL non-linearity producing it, exactly as seen in that applet.

You know, that is an interesting similarity. But it actually has nothing directly to do with Bell test correlations. Those are obtained by a different technique, and yes, there is an underlying mathematical relationship connecting them. But that is where the connection ends.

If you can formulate a non-local connection between 2 polarizers in series, go for it. But that analogy does not apply to Bell tests. In fact, I am sure that there probably IS a connection at some deep level as you suggest. After all, the Heisenberg Uncertainty Principle is at work in both cases so that is to be expected. In my opinion, the same quantum non-locality is at work whenever the HUP is invoked. But everyone may not agree with that opinion.

However, that does not change the fact that it is the ENTANGLED connection which is of interest in Bell tests. It is that paradox which is at hand, and which is the subject of EPR.

my_wan

Jun1-10, 06:44 PM

Note: Experimental constraints are too high for me to worry about anything but the ideal case.
And why do you talk about the 50% detected? There is no 50%! They are ALL detected!! The relevant issue is subensembles of the entire universe.
This is a single polarizer with a photon detector:
http://www.physicsforums.com/attachment.php?attachmentid=26133&stc=1&d=1275435978
Now when we turn a second polarizer to 22.5 degrees, relative to that one, we get:
http://www.physicsforums.com/attachment.php?attachmentid=26134&stc=1&d=1275435978
Given that only 50% of the orginal beam hits the second polarizer, it's passing 85.36% of the polarized light hitting it. This is precisely the percent of EPR correlations at that same angle offset. It also matches at EVERY arbitrary offset. I take this to empirically mean that 2 polarizers, with a 22.5 degree offset, will counterfactually detect 85.36% of the same individual photons.

You know, that is an interesting similarity. But it actually has nothing directly to do with Bell test correlations. Those are obtained by a different technique, and yes, there is an underlying mathematical relationship connecting them. But that is where the connection ends.
So a point for point, angle for angle exact match is no connection? Let's look at what Bell's ansatz operationally assumed: That the correlations of any local realistic EPR mechanism must linearly transition from 50% to 100% max. Hence the 75% Bell limit on correlations at 22.5 degrees. But if a beam of polarized light does NOT linearly transition from 0 to 90 degrees, how can you possibly expect (presummed deterministic) correlations to?

If you can formulate a non-local connection between 2 polarizers in series, go for it. But that analogy does not apply to Bell tests. In fact, I am sure that there probably IS a connection at some deep level as you suggest. After all, the Heisenberg uncertainty principle is at work in both cases so that is to be expected. In my opinion, the same quantum non-locality is at work whenever the HUP is invoked. But everyone may not agree with that opinion.

The first sentence if kind of interesting, but my only point was that if the mechanism that induced the non-linearity exists in uncorrelated photons was a QM property of the way a photon interacts with a polarizer, and this interaction is fundamentally deterministic, it cannot be used as an ansatz to define a non-local mechanism. There is no doubt whatsoever that HUP is empirically valid, but that doesn't rule out a local deterministic underpinning, with or without finite parts (subensembles). Bell's ansatz is contingent upon countable subensembles with 'absolute' (measurable) properties.

However, that does not change the fact that it is the ENTANGLED connection which is of interest in Bell tests. It is that paradox which is at hand, and which is the subject of EPR.
Yes, but the locality claims about the meaning of ENTANGLED connection is predicated on a linearity that are trivially violated generally, in even Newtonian physics, and specifically in polarizer/photon interactions without EPR correlations. Yes the entangles states is interesting, but the non-linearity accross relative detector settings do not represent a test of locality, except in the rawest assumption that all observables have perfectly linear relationships with things.

You keep asking for a dataset, but you'll just hang to the notion that you must be able to plug in 22.5/45, and get the same answer as 0/22.5. To that I have 1 question: If predefining a common coordinate system such that 22.5/45 has a relative difference of 22.5 is not a FTL cheat, why the is predefining ONLY the relative difference a FTL cheat? Coordinate systems are by definition non-physical, only the symmetries on them are.

Gordon Watson

Jun1-10, 08:50 PM

You asked if the mathematical legitimacy of Bell's theorem is irrefutable. The mathematical form of Bell's theorem is the Bell inequalities, and they are irrefutable. Their physical meaning, however, is debatable.

In order to determine the physical meaning of the inequalities we look at where they come from, Bell's locality condition, P(AB|H) = P(A|H)P(B|H).

Then we can ask what you asked and we see that:
1. A and B are correlated in EPR settings.
2. Bell uses P(AB|H) = P(A|H)P(B|H)
3. P(AB|H) = P(A|H)P(B|H) is invalid when A and B are correlated.

Conclusion: The form, P(AB|H) = P(A|H)P(B|H), cannot possibly model the experimental situation. This is the immediate cause of violation of BIs based on limitations imposed by this form.

What does this mean?

P(AB|H) = P(A|H)P(B|H) is the purported locality condition. Yet it is first the definition of statistical independence. The experiments are prepared to produce statistical dependence via the measurement of a relationship between two disturbances by a joint or global measurement parameter in accordance with local causality.

Bell inequalities are violated because an experiment prepared to produce statistical dependence is being modelled as an experiment prepared to produce statistical independence.

Bell's theorem says that the statistical predictions of qm are incompatible with separable predetermination. Which, according to certain attempts (including mine) at disambiguation, means that joint experimental situations which produce (and for which qm correctly predicts) entanglement stats can't be viably modelled in terms of the variable or variables which determine individual results.

Yet, per EPR elements of reality, the joint, entangled, situation must be modelled using the same variables which determine individual results. So, Bell rendered the lhv ansatz in the only form that it could be rendered in and remain consistent with the EPR meaning of local hidden variable.

Therefore, Bell's theorem, as stated above by Bell, and disambiguated, holds.

Does it imply nonlocality -- no.

This is not correct because it is not what Bell says. You are mixing up his separability formula (Bell's 2), which has a different meaning. Bell is simply saying that there are 2 separate probability functions which are evaluated independently. They can be correlated, there is no restiction there and in fact Bell states immediately following that "This should equal the Quantum mechanical expectation value..." which is 1 when the a and b settings are the same. (This being the fully correlated case.)

DrC, ThomasT.

You both appear to agree that Bell uses P(AB|H) = P(A|H).P(B|H) in his work.

I cannot see how EPR studies using that formula could be serious. If H includes a hidden variable for each particle, that formula gives P(AB|H) = P(A|H).P(B|H) = (1/2).(1/2) = 1/4.

Can you direct me to an example where Bell uses P(AB|H) = P(A|H).P(B|H) in his work, please?

[Apologies for possible hi-jack; I will add this under Understanding Bell's mathematics.]

DrChinese

Jun1-10, 10:53 PM

...

You are wandering all over the place. When you want to tackle a point, I will be glad to discuss. I have asked you before to stop your meandering. Listen to what I am saying, and re-read your responses. You are just flailing.

I told you to look at PBSs not polarizers. I know how polarizers work, you don't need to provide a diagram. They have nothing to do with the discussion. We are talking about Bell's theorem and Bell tests.

I know you have a lot of pet ideas. So what? We are NOT here to discuss your pet ideas. The point is to discuss the science of EPR and Bell. I know you are "supremely" confident of your ideas, but you have yet to demonstrate a single cogent idea. I refuse to continue if you won't be a well-behaved participant.

DrChinese

Jun1-10, 10:54 PM

DrC, ThomasT.

You both appear to agree that Bell uses P(AB|H) = P(A|H).P(B|H) in his work.

I cannot see how EPR studies using that formula could be serious. If H includes a hidden variable for each particle, that formula gives P(AB|H) = P(A|H).P(B|H) = (1/2).(1/2) = 1/4.

Can you direct me to an example where Bell uses P(AB|H) = P(A|H).P(B|H) in his work, please?

[Apologies for possible hi-jack; I will add this under Understanding Bell's mathematics.]

Will continue that part of the discussion in that thread...

my_wan

Jun2-10, 01:53 AM

I was reading over the rebuttals, and it seems I often misinterpreted your claim of 100% of photons emerging from a polarizer. I argued the polarizer effect by narrowing attention to a particular subsystem of the experiment. I do need to include polarizing beam splitter if for no other reason than perhaps to avoid some confusion.

Yes it's true that a PBS effectively detects ~100% of the light. Yet this still represents a single detection axis. So let's see what looking at both outputs of a PBS entails in the argument I posed. Consider a PBS in front of a randomly polarized beam of light. ~50% will be diverted to 1 detector, while the other ~50% is diverted to another. By the argument I proposed, if you rotate that PBS 22.5 degrees, ~15% of the light that would have been diverted 1 way is now diverted the other way.

Now consider a pair of PBS/detectors at each end of an EPR experiment. With both PBS's set on the same axis we get ~100% correlations. We offset 1 PBS by 22.5 degrees. Each photon has a certain tolerance for how far off from the PBS axis can be relative to the default photon polarization before it's diverted the other way by the PBS. When you exceed this tolerance, then, in spite of being anticorrelated with it's partner, the tolerance in the difference between the PBS detection axis is exceeded, so it reads as uncorrelated.

Bell's ansatz assumes a locally realistic mechanism must take a form that linearly transitions with the change in angle. What we have is a transition that changes with the square of the angle. Yet this empirical fact is ubiquitous. The same rules apply to polarizers, the efficiency loss in aerial antennas offset from the ideal setting, etc. This empirical fact may or may not have a realistic basis. But the fact that EPR correlations exhibit the same detection profile says nothing about locality when the same effect occurs without any correlations involved. EPR correlations, in this view, would only indicate the mechanism is deterministically replicable.

By the way, if the wavefunction is assumed to be real, with particles being a projection from a Hilbert space construct, it's reasonable that the square of the angle defines the observables. Even if only a subset of the 'possibilities' formally defined in Hilbert space represent an actual state. Self interaction still seems to require an ensemble (possible infinity) of micro-states.

DrChinese

Jun2-10, 10:46 AM

1. I was reading over the rebuttals, and it seems I often misinterpreted your claim of 100% of photons emerging from a polarizer. I argued the polarizer effect by narrowing attention to a particular subsystem of the experiment. I do need to include polarizing beam splitter if for no other reason than perhaps to avoid some confusion.

Yes it's true that a PBS effectively detects ~100% of the light. Yet this still represents a single detection axis. So let's see what looking at both outputs of a PBS entails in the argument I posed. Consider a PBS in front of a randomly polarized beam of light. ~50% will be diverted to 1 detector, while the other ~50% is diverted to another. By the argument I proposed, if you rotate that PBS 22.5 degrees, ~15% of the light that would have been diverted 1 way is now diverted the other way.

Now consider a pair of PBS/detectors at each end of an EPR experiment. With both PBS's set on the same axis we get ~100% correlations. We offset 1 PBS by 22.5 degrees. Each photon has a certain tolerance for how far off from the PBS axis can be relative to the default photon polarization before it's diverted the other way by the PBS. When you exceed this tolerance, then, in spite of being anticorrelated with it's partner, the tolerance in the difference between the PBS detection axis is exceeded, so it reads as uncorrelated.

2. Bell's ansatz assumes a locally realistic mechanism must take a form that linearly transitions with the change in angle...

1. This is correct, you end up with subensembles where you have HH, VV, HV and VH. These are experimentally verifiable. What is counterfactual is the realistic case where there are 3 settings, and you get 8 permutations: HHH, HHV, ... , VVV.

2. Bell does not say this. He says that the local realistic formula ideally should reproduce the quantum expectation value. That is, if there is to be agreement between local realism and QM. So then you notice that it more or less requires the function to have a second derivative of zero (i.e. stationary) so that the realism requirement works. Now, this is not an absolute requirement per se. But you can see that he is setting things up to hint strongly that there will be a contradiction. And he is sharing some of his thoughts about how he arrives at his proof.

my_wan

Jun2-10, 03:55 PM

1. Yes, but hidden variables may themselves be subassemblies of those measurables, which define the measurables, rather than just a hidden appendange to them.

2. Wrt: "Bell does not say this."
So, his ansatz, which assumes a maximum classical correlation 0=100%, 22.5=75%, 45=50%, 67.5=25%, and 90=0%, is not a requirement that max correlation statistics must linearly transition with the angle?

Here is an approach that takes a generally similar tack to my argument, with the a priori known probability distribution, but in the context of classical nonlinear filtering in a stochastic system.
Dynamical state reduction in an EPR experiment (http://arxiv.org/abs/0907.2327)
A model is developed to describe state reduction in an EPR experiment as a continuous, relativistically-invariant, dynamical process. The system under consideration consists of two entangled isospin particles each of which undergo isospin measurements at spacelike separated locations. The equations of motion take the form of stochastic differential equations. These equations are solved explicitly in terms of random variables with a priori known probability distribution in the physical probability measure. In the course of solving these equations a correspondence is made between the state reduction process and the problem of classical nonlinear filtering. It is shown that the solution is covariant, violates Bell inequalities, and does not permit superluminal signaling. It is demonstrated that the model is not governed by the Free Will Theorem and it is argued that the claims of Conway and Kochen, that there can be no relativistic theory providing a mechanism for state reduction, are false.

DrChinese

Jun2-10, 04:37 PM

1. Yes, but hidden variables may themselves be subassemblies of those measurables, which define the measurables, rather than just a hidden appendange to them.

2. Wrt: "Bell does not say this."
So, his ansatz, which assumes a maximum classical correlation 0=100%, 22.5=75%, 45=50%, 67.5=25%, and 90=0%, is not a requirement that max correlation statistics must linearly transition with the angle?

3. Here is an approach that takes a generally similar tack to my argument, with the a priori known probability distribution, but in the context of classical nonlinear filtering in a stochastic system...

1. They can only go as deep as A and B. There is no C, hence no realism.

2. I think you mean the boundary point of a Bell inequality. Bell does not require that boundary to be the actual expectation function. Rather, that QM and LR are on different sides of it.

3. Again, another author who does not feel the need to provide for realism in their "realistic" solution. Hey, Joy Christian just came up with yet another "disproof of Bell" this week! Same thing, proof of hidden variables for A and B but not C. So what is the point of touting realism when no realistic dataset is forthcoming? A single counterexample should do it!

my_wan

Jun2-10, 05:58 PM

1. They can only go as deep as A and B. There is no C, hence no realism.
The 3rd variable is counterfactual in Bell's EPR argument, so the realism is suspect in that case.

2. I think you mean the boundary point of a Bell inequality. Bell does not require that boundary to be the actual expectation function. Rather, that QM and LR are on different sides of it.Well naturally the linear assumption is a boundary rather than a prediction. Yet it remains that Bell's ansatz assumes a classical mechanism can not exceed this linear boundary.

3. Again, another author who does not feel the need to provide for realism in their "realistic" solution. Hey, Joy Christian just came up with yet another "disproof of Bell" this week! Same thing, proof of hidden variables for A and B but not C. So what is the point of touting realism when no realistic dataset is forthcoming? A single counterexample should do it!
Actually, wrt the authors mentioned, I have to agree.. :blushing: They tend to overstate the significance of what they provided. Such attempts do remain important though.

The thing is, the claims of what violations of Bell's inequalities actually mean tends to be overstated on both sides of the fence. We are both arguing on the grounds of what we don't know, the nature of a connection between spacelike separated correlations. The argument from ignorance is inherent in the whole debate. I appreciate you making me think though.

Wrt a dataset, your not going to be happy with the floating 0 angle to maintain relative detector data locally. Neither am I really, but the physical significance of a choice in coordinate labels, distinct from the symmetries, is also dubious. My modeling attempts is to articulate the issues in my mind. They involve generating a list of thousands of random virtual photons and looping through them with a set of virtual detectors. I'm still trying some new, likely dubious, ideas. If we are dealing with transfinite subensembles it may not be possible with or without FTL. But the objective is to learn the issues in as much detail as possible. Adding both sides of the PBS output is actually quiet useful.

DrChinese

Jun3-10, 09:45 AM

The 3rd variable is counterfactual in Bell's EPR argument, so the realism is suspect in that case.

That is the definition of realism. If there is no simultaneous C, there is nothing to discuss in a hidden variable theory. It simply isn't a hidden variable theory.

Because Bell slips this requirement in such a subtle manner, it doesn't jump out to many folks. But there it is, right after his (14), and it is quite evident: a, b and c are all together in one equation.

So it is simple: if you reject this assumption as meaningful, then the Bell result is not meaningful.

But you will be part of a small minority. Hey, some people don't like the Beatles either.

my_wan

Jun3-10, 12:08 PM

If we take fully generalized thermodynamic models and/or Hilbert space seriously, we could also be looking at a version of Hilbert's paradox of the Grand Hotel. Of course that begs the question of why QM is normalizable. Yet thats a bit of a soft spot from a foundational perspective anyway. Yet, again, if a unit vector is a sum over an infinite number of local "hotel rooms", infinitesimals momentarily occupying a finite subset of those rooms, it still doesn't require FTL as a mechanism.

Would you consider 'actual infinities' a violation of realism? Even the linked paper by Bedingham, using a stochastic model, appears to be stuffing an arbitrary number of possible states into a singular ensemble. Same for the thermodynamic model, with statistically complete variables, linked a few pages back. Hilbert space, with it's required metrically complete property, appears to require the same thing, if it's taken to be physically real in some sense.

This also appears to be a required property for Quantum Computers to work as expected. Who was it that offered Quantum Computers as proof of MWI, due to not enough particles in the Universe to mimic them? The Axiom of Choice also appears to be related in some sense.

So what is your view wrt realism if it's defined in terms of 'actual infinities'?

DrChinese

Jun3-10, 03:20 PM

If we take fully generalized thermodynamic models and/or Hilbert space seriously, we could also be looking at a version of Hilbert's paradox of the Grand Hotel. Of course that begs the question of why QM is normalizable. Yet thats a bit of a soft spot from a foundational perspective anyway. Yet, again, if a unit vector is a sum over an infinite number of local "hotel rooms", infinitesimals momentarily occupying a finite subset of those rooms, it still doesn't require FTL as a mechanism.

Would you consider 'actual infinities' a violation of realism?... So what is your view wrt realism if it's defined in terms of 'actual infinities'?

There is no dividing line between QM and realism on this subject. I don't see how the problem of infinities relates to realism. I guess you are saying that infinities cannot exist, and that somehow that means that counterfactuals don't have to exist. But I am not asserting counterfactuals exist, you are. Or at least you are if you are a realist.

my_wan

Jun3-10, 05:54 PM

There is no dividing line between QM and realism on this subject. I don't see how the problem of infinities relates to realism. I guess you are saying that infinities cannot exist, and that somehow that means that counterfactuals don't have to exist. But I am not asserting counterfactuals exist, you are. Or at least you are if you are a realist.
Your reading way too much into my words, apparently based on a 'perception' of my position. In fact I said "actual infinities" may indeed exist. A sentiment that I have stated several ways before. Here I suggested perhaps the incongruence in counterfactual measures might be a real 'physical' result of Hilbert's paradox of the Grand Hotel.

I'm not holding nature to a conception of my choice. I am debating points for which I lack certainty, in the hopes of learning something that increases or decreases that certainty. The highly limited few things I have a fair degree of certainty on, is not even included in my arguments. I've asserted how I think it's possible for counterfactuals to be interpreted within a 'particular' contextual construct, but mostly dropped it for lack of clarity. But I can't a priori reject reasonable arguments, even if they lack the conclusiveness the authors wish it to.

When you objected with: "another author who does not feel the need to provide for realism in their "realistic" solution", I had to agree that, in spite of some reasonable content, your objection was essentially valid. I don't see any solid justification on either side. The non-realist seems to say, we don't see it so it must not exist. The realist seems happy to suggest mechanisms without actually stating what's real. So I began thinking about how Bedingham and others smooth over Bell's violations, where they hide the inequalities, and why it's not sufficient for some to define realism.

I'm not asking you to accept Hilbert's hotel paradox as an actual explanation, only something that it might in principle be so. My question was far more limited, to get a better picture of what you would 'in principle' accept as a realistic model. Because a repeat of Bell's realism really leaves me with a lot of questions about the range of what can and can't qualify as realism in your view. It seems the definitions used by various authors are incongruent, even when based on the same words, like the definition used by Bell.

Note: 'Actual infinities' is distinct concept from infinities in general. 'Actual infinities' are existential, so they by definition relates to realism. And it seemed to me the approach Bedingham et al used implicitly stuffed extra occupants in Hilbert's hotel, and even provided some justification in terms Hilbert space, quantum computers, etc. I remain at a loss for how you define the constraints of what qualifies for realism. You've rejected my characterization as a linear part-->measurable property, and continually quote my text that says one thing and characterize it as saying another. My desire for more concrete definitions is hampered by assumption of my positions, opposite of what I stated, on the very questions I ask to articulate those definitions. So I can only guess what your answer might have been.

ThomasT

Jun5-10, 03:49 PM

1. Say Alice and Bob are counter-propagating sinusoidal (light) waves that share a cloned property, eg., they're identically polarized. Analyze this cloned property with crossed polarizers and you get entanglement correlation. Cos^2 |a-b| in the ideal. It's just optics. Not that optics isn't somewhat mysterious in it's own right. But we can at least understand that the entanglement stats so produced don't have to be due to Alice and Bob communicating with each other, or that nonseparability means that Alice and Bob are the same thing in the sense that they're actually physically connected when they reach the polarizers.

1. I have news for you: this is patently FALSE. If you take 2 identically polarized photons and run them through the polarizers as you describe here, you do NOT get Cos^2 |a-b| or anything close to it.In the cases you're talking about, the explanation is that the photons (while sometimes very closely polarized) aren't identically polarized. They're not 'clones' of each other. How do we know that? Precisely because when you run them through the polarizers you don't get cos^2 |a-b| entanglement stats (but you do get a range of approximations of essentially the same sinusoidal angular dependency -- which suggests to me that 'entanglement' is simply a special case involving the same underlying physical principles, which include, but aren't limited to, (1) the principle of locality and (2) the cos^2 theta rule).

You ONLY get this for ENTANGLED photons.I agree. They (or a common property that's being jointly measured) are clones of each other. Which means that they're, eg., identically polarized. Which is deduced via the production of entanglement stats.

In other words: in the case where your assumption is actually valid - and I do mean identical and identically polarized photons coming out of a PDC crystal - you do NOT get entangled state statistics.Then, as I said above, these photons aren't cloned (ie., entangled) wrt polarization. In this case, we can assume that |L1 - L2| > 0 (ie., we can assume that they weren't identically polarized), where L1 and L2 denote the optical vectors of the photons.

------------------------

2. Bell didn't address this case, because it's precluded by the EPR requirement that lhv models of entanglement be expressed in terms of parameters that determine individual results.
2. Bell quite discussed the case where the correlations are due anti-symmetric considerations.That's not what I'm talking about -- which is that if Bell had modelled the joint situation in the global (ie., nonseparable) terms that it actually required (involving some modification in the representation of the 'beables' involved), then he might have presented a local realistic model which would have reproduced the qm correlation. The point of departure for viable local realistic models is that an experimental situation measuring a joint microphysical parameter vis a joint measurement parameter requires a 'nonseparable' representation. Such models have been produced, they work, and they remain unrefuted.

(Wrt my statement 2. above, I've come to think that EPR's definition of reality doesn't require that LR models of entanglement be expressed in terms of parameters that determine individual results. That is, there can be a common, underlying parameter that determines joint results while not determining individual results, and this, realistic, conception isn't contradicted by the EPR's conception of reality and definition thereof vis elements of reality.)

-----------------------------------------------

3. On the other hand, since a local realistic computer simulation of an entanglement preparation is not the same as a local realistic formal model (in the EPR sense), then it wouldn't be at all surprising if such a simulation could reproduce the observed experimental results, and violate a BI appropriate to the situation being simulated -- and this wouldn't contradict Bell's result, but, rather, affirm it in a way analogous to the way real experiments have affirmed Bell's result.

3. I would like to see one (and yes, it would surprise me). This is a somewhat complex subject and I am currently working with the De Raedt team (and another independent theoretical physicist) regarding some concerns I have expressed about their model. Their model does have some very interesting features. If it were possible to suitably express such a simulation, I think it might require some additional experimental analysis. It would not affect Bell's Theorem.Not the math itself, no, but it would affect the physical interpretation of BI violations wrt locality and determinism -- rendering them irrelevant wrt those considerations.

---------------------------------------------------

From the thread: "Why the De Raedt Local Realistic Computer Simulations are wrong", you stated:

In trying to show that there "could" be an exception to Bell, please consider the following to add to your list of tests for you candidate LHV theory:
... snip ...
b) The formula for the underlying relationship will be different than the QM predictions, and must respect the Bell Inequality curve. I.e. usually that means the boundary condition which is a straight line, although there are solutions which yield more radical results. If you're requiring that an LR model of entanglement not agree with qm predictions or experimental results, then I now see the point of your 'LR dataset' requirement. Well, yes, I certainly agree that one way to rule out qm compatible and viable LR accounts of entanglement is to simply require them to be incompatible with qm and inaccurate. But that would be inane. So I must be misunderstanding what you mean.

DrChinese

Jun5-10, 04:32 PM

1. Then, as I said above, these photons aren't cloned (ie., entangled) wrt polarization. In this case, we can assume that |L1 - L2| > 0 (ie., we can assume that they weren't identically polarized), where L1 and L2 denote the optical vectors of the photons.

2. If you're requiring that an LR model of entanglement not agree with qm predictions or experimental results, then I now see the point of your 'LR dataset' requirement. Well, yes, I certainly agree that one way to rule out qm compatible and viable LR accounts of entanglement is to simply require them to be incompatible with qm and inaccurate. But that would be inane.

1. Again, this is patently false. They most certainly ARE polarization clones of each other. And they are entangled. But they are not polarization entangled, which is quite different. If we accept your physical assumption of "counter-propagating influences", then these should produce the same statistics as entangled particles. But they don't.

Now why are these particles acting different? Because they are NOT in a superposition of polarization states. This is meaningful within QM but has no counterpart in a local realistic theory - in which there is no such thing as a superposition (by definition). Take a look at how these photon pairs are produced and you will see how ridiculous your assertion is. A reference:

Theory of two-photon entanglement in type-II optical parametric down-conversion
M. Rubin, D. Klyshko, Y. Shih, A. Sergienko
Physical Review A, December 1994
http://sws.bu.edu/alexserg/PRA_50_5122.pdf

"Using Eq. (41), it is easy to see that |Phi'> is a product state when Psi=pi/8; otherwise it is in an entangled state. It is an EPR state if Psi=0 or pi/4 and is a linear superposition of two EPR states for all other Psi's..."

What this means is that the only difference in producing the entangled state versus the product state is a small rotation of a wave plate. Perhaps you could explain how that separates these streams using a local realistic viewpoint. (P.S. this is a trick question because any accurate answer would show where to find the physical source of entanglement, and there isn't one.) Similarly there are other ways to break polarization entanglement and all of them rely on gaining knowledge of "which path" and therefore do not produce a superposition.

Again, I keep calling you out on this subject and you are operating in denial. The fact is that entangled particles have attributes that do not follow a local realistic explanation. You are simply trying to claim your ideas are equivalent to QM and they are not. If you are going to make an assumption with physical implications, then you lay yourself open to seeing that disproved. Which it has been, over and over.

2. Talk to Bell about this. Or God. I did not create our universe, so it is not my requirement. Next you will be complaining about the 4 color map theorem as being "inane".

my_wan

Jun5-10, 08:08 PM

Here is an interest paper by Michael Seevinck, which rigorously derives a version of Bell's inequalities for correlations.
The Quantum World is Not Built Up From Correlations (http://philpapers.org/rec/SEETQW).
Found. Phys. 36, 1573-1586 (2006)

He makes a more heuristic case here:
It is possible that one thinks that the requirement of local realism is too strong a requirement for ontological robustness. However, that one cannot think of entanglement as a property which has some ontological robustness can already be seen using the following weaker requirement: anything which is ontologically robust can, without interaction, not be mixed away, nor swapped to another object, nor flowed irretrievably away into some environment. Precisely these features are possible in the case of entanglement and thus even the weaker requirement for ontological robustness does not hold.
This same case against ontological robustness made here naturally also applies to the properties in Bell's inequalities. If ontologically robust variables exist, independent of any observation of it, this tells us it can't innately contain the properties, or observables, that we associate with the realism of classical properties. These properties must be generated dynamically.

At a foundational level, any such ontologically robust variables, independent of the dynamically generated properties, must by definition make them independent variables. As Schneider put so well in Hume’s Determinism Refuted (http://www.drchinese.com/David/Hume's_Determinism_Refuted.htm), an independent variable cannot even in principle be observed. However, if they play a role in dynamically generating observables, they may still have deterministic underpinnings. Thus Schneider has not refuted determinism, nor ontologically robust variables, in principle, but merely described exactly why it can't be directly observed in experiments, whether they exist or not. Schneider's argument only holds if absolutely nothing we can't see exist. The standard QM interpretation is predicated on this notion.

The positivist can yell poppycocks, but existential postulates are fundamentally no different from any mathematical postulate, so long as it's used for more than just to sweep the ontological and/or empirical difficulties of QM under the rug. So long as QM and GR remain disconnected, even failing the above criterion, it remains a legitimate open and worthy question. There is sound reason to consider observables synonymous with what is 'real'. It is the sole source of cogency of any theory. Yet to fail to make a distinction, in principle, between what is observed and what is ontologically real has been referred to as sleepwalking by some authors.

The point here is that ontological realism, ontologically robust variables, does not explicitly depend on any given measurable having any direct relation to those variables. Schneider's argument should make it clear that, even if realism is factual in principle, the notion that these ontologically robust variables are in themselves measurables is untenable. For a realist to assume a thing is observable without interaction amounts to ESP, at which point a self-referential interaction is observed, not the thing. From this perspective, the very notion of classical realism, used by Bell, Einstein, etc., is fatally flawed at the foundational level. Yet the realism may yet persist, or not.

DrChinese

Jun5-10, 08:31 PM

At a foundational level, any such ontologically robust variables, independent of the dynamically generated properties, must by definition make them independent variables. As Schneider put so well in Hume’s Determinism Refuted (http://www.drchinese.com/David/Hume's_Determinism_Refuted.htm), an independent variable cannot even in principle be observed. However, if they play a role in dynamically generating observables, they may still have deterministic underpinnings. Thus Schneider has not refuted determinism, nor ontologically robust variables, in principle, but merely described exactly why it can't be directly observed in experiments, whether they exist or not. Schneider's argument only holds if absolutely nothing we can't see exist. The standard QM interpretation is predicated on this notion.

That Schnieder guy makes some good points, thanks for pointing this out.

:smile:

my_wan

Jun5-10, 09:57 PM

That Schnieder guy makes some good points, thanks for pointing this out.

:smile:

:wink:

my_wan

Jun6-10, 01:17 AM

Here is a more rigorous treatment of the idea that, if QM holds locally, then it indicates a violation of Bell's inequalities with no-signaling:
Local Quantum Measurement and No-Signaling Imply Quantum Correlations (http://arxiv.org/abs/0910.3952)
Phys. Rev. Lett. 104, 140401 (2010)

This paper also uses an argument I previously attempted here wrt classical variables:
Breakdown of Bell's Theorem for incompatible measurements (http://arxiv.org/abs/0804.0884)

It still seems to me, based on my modeling, that in order to define EPR in terms of variables, each offset in detector settings has to be defined by a separate (probably relativistically related) probability space as defined by Hess et al. Unless of course I'm allowed to define 1 of the detector settings as 0, and simply rotate the whole coordinate system to change its settings. Otherwise the number of variables required grows excessively large for arbitrary settings, perhaps even diverges. Quantum computers appears to require an arbitrary number of variables also.

QM, in a sense, consist of discontinuous solutions to differential equations. Along with the Born rule and HUP, it primarily sums up the conceptual difficulties with QM. I suspect Bell violations may be related more to a physical manifestation the Born rule than HUP. As if natures measurables really are a projection from an entirely different coordinate symmetry than we assume.

DrChinese

Jun6-10, 11:14 AM

This paper also uses an argument I previously attempted here wrt classical variables:
Breakdown of Bell's Theorem for incompatible measurements (http://arxiv.org/abs/0804.0884)

That reference deserved to be labeled with the author's name. Hess is a persistent local realist who has attacked Bell and Bell tests from numerous angles. His work is widely rejected.

In this piece, he basically argues for the QM position by asserting that there are no classical probability spaces. He discusses the idea of incompatible measurements (i.e. >2) which is in fact the QM position. I guess if you move the bar far enough, everyone can claim victory.

The question I always ask myself for these arguments is really quite simple: what would history's greatest local realist - Einstein - think of the argument? Of course, we can only speculate but speculate I will. Einstein would have appreciated the Bell argument and would NEVER try to con his way out of it with an argument like Hess has made. Please, feel free to disagree...

my_wan

Jun6-10, 02:55 PM

Ok, so Hess has his critiques, but on what grounds are the counterarguments predicated? In fact this is why I chose this reference, rather than the original version, because it was a response to criticisms, thus contained references to those criticisms.

Criticizing it on the grounds that it fails to explain EPR correlations, or provide a mechanism for doing so, is a non-starter. Consider the following quote from the Hess paper, as a result of implied content of his critiques:

It also should be noted that the author subscribes fully to the teachings of both quantum and Kolmogorov probability (as different and well proven probability frameworks) and to their well known relationship to actual experiments (see e.g. [16]). The author has neither any criticism for these frameworks nor for the definition of the “elements of physical reality” of the EPR paper [17] nor for the EPR-type experiments performed by Aspect [18] and others. The author criticizes exclusively the work of Bell as not being general enough to apply to general physics problems (quantum and/or classical) and the work of Bell’s followers for the same reason and for actual logical and mathematical mistakes.

So when you say widely rejected, precisely what was widely rejected? No specific claim was made that the given mechanism would even provide a realistic explanation of the inequality violations. Only that Bell's argument, as posed, lacked the generality needed for the generality often taken in its interpretation, whether a classical or quantum context. So his critiques proceeded on the grounds that the assumed variables have a presupposed relationship to the measurables, and proceeds to destroy the argument on those grounds. Well duh... So the implied meaning of "His work is widely rejected" is of little import to the questions that remain open and unanswered. Facts are not a democracy, and the claims here presupposes a generality lacking in the argument. Thus no complete proof or disproof exist atm.

I get a queasy feeling anytime I start trying to second guess how someone else would view something. I suspect Einstein had his own perspective, that didn't lack a full appreciation of the empirical validity of QM, nor the loss he was at to explain what quanta was.I consider it quite possible that physics cannot be based on the field concept, i.e., on continuous structures. In that case, nothing remains of my entire castle in the air, gravitation theory included, [and of] the rest of modern physics. (Albert Einstein, 1954)Here he placed the importance of describing what actually is above his own lifes work. So where we might presuppose Einstein would go with any given piece of empirical evidence is more than a little presumptuous.

DrChinese

Jun6-10, 03:30 PM

1. Ok, so Hess has his critiques, but on what grounds are the counterarguments predicated? In fact this is why I chose this reference, rather than the original version, because it was a response to criticisms, thus contained references to those criticisms.

So when you say widely rejected, precisely what was widely rejected? No specific claim was made that the given mechanism would even provide a realistic explanation of the inequality violations. Only that Bell's argument, as posed, lacked the generality needed for the generality often taken in its interpretation, whether a classical or quantum context. So his critiques proceeded on the grounds that the assumed variables have a presupposed relationship to the measurables, and proceeds to destroy the argument on those grounds. Well duh... So the implied meaning of "His work is widely rejected" is of little import to the questions that remain open and unanswered. Facts are not a democracy, and the claims here presupposes a generality lacking in the argument. Thus no complete proof or disproof exist atm.

2. I get a queasy feeling anytime I start trying to second guess how someone else would view something. I suspect Einstein had his own perspective, that didn't lack a full appreciation of the empirical validity of QM, nor the loss he was at to explain what quanta was.Here he placed the importance of describing what actually is above his own lifes work. So where we might presuppose Einstein would go with any given piece of empirical evidence is more than a little presumptuous.

1. It is normal, in this forum, to identify work which is not generally accepted (or worse, is generally rejected). Hess makes note of the fact that his position is rejected by Mermin. As to the substance of his argument: Hess is constantly trying new attacks on Bell. It is hard not to get the feeling that his position is based on emotion rather than science. When he comes up with something worth looking at in more detail, I will. In the meantime, I am waiting for a specific counterexample to discuss. He doesn't offer any.

2. Well, I presume to state that Einstein would have no part of Hess' ideas. He would have understood Bell immediately, and would never have tried to weasel out of it with anything less than something equally substantial. As you mention, Einstein would be willing to give up everything for one good argument. Fortunately, Bell only requires Einstein give up 1 thing.

my_wan

Jun6-10, 10:02 PM

Again, what exactly has been rejected, the claim that the Bell argument contains this class of of variables the Bell argument doesn't address, or the claim that that no such class has been constructed to do so?

I mention this paper only because I did use a similar argument as one possibility among others. I am also dissatisfied with it, as I have noted. The 0 angle definition condition, I was forced into to make it work, is physically quiet similar to what Hess et al proposed in making a new HV set for each possible angle. A new set for each angle gets out of the 0 angle condition I had, but creates a new problem. The variables must still define the offset, and 1 or the other detector, but not both, has to count off from that offset. Thus it introduces the same relative coordinate condition I was forced to impose with an arbitrarily defined 0 setting.

The thing about Mermin's counter is that he presupposes the counterfactual coincidences must have the same coincidence rates relative to a separate run in which they were empirically established. In fact Mermin states he uses his red/green light toy model to articulate issues with.

Let's consider at a pair of unfair coins. These coins are special, and have a micro-dial setting to determine how unfair they are. You set it so they have an 15% chance of landing on the opposite sides. Now you take a 3rd coin, and want to set it so it has a 50% chance of landing on the same side as the 1st coin, and an 85% chance of landing on the opposite side as the second coin. Does the fact that it can't be done invalidate the reality of the coin settings? Yet separately you can do just that.

Are we arbitrarily imposing a similar physical absurdity, and hiding it behind a presupposed 3-way correlation? Does the variables we suppose are carried by the photons physically preclude such 3-way correlations for perfectly valid physical reasons? In fact, in QM, the probabilities must be considered jointly, precluding probabilities greater than 1. It is only through an a priori imposition that such conditions are demanded in QM, which are contrary to the rules of QM. So we are also violating the rules of QM, as well as physical constraints on the coin analogy, with such counterfactual a priori demands.

So if the rules of QM are not being violated, show how QM predicts a probability greater than 1, without presupposing it through counterfactual choices. Otherwise Bell's inequality sneaks a QM rules violation in the back door, via a counterfactual claim. The physical constraint, like the coins, would be in physical creation the 3rd correlated particle (variables) with the specified properties, not in what the detectors read after the fact, nor a constraint on any single pairing of properties and hv's.

That may be the strongest objection yet. Like trying to define 3 coins that can all land on opposite sides, because couterfactually any 2 can.

DrChinese

Jun7-10, 09:06 AM

ThomasT

Jun7-10, 01:42 PM

Bell's ansatz assumes a locally realistic mechanism must take a form that linearly transitions with the change in angle. What we have is a transition that changes with the square of the angle. Yet this empirical fact is ubiquitous. The same rules apply to polarizers, the efficiency loss in aerial antennas offset from the ideal setting, etc.It was from evaluations along these lines that suggested to me that there might be something wrong with Bell's formulation. For example, if EPR elements of reality are too restrictively represented, or if the statistical independence represented by Bell's equation (2) supercedes it's represention of causal independence between A and b (B and a), then Bell's formulation isn't logically rigorous, and violations of BIs aren't physically relevant.

This empirical fact may or may not have a realistic basis.What do you mean by this? That the cos^2 theta rule can't be understood realistically?

But the fact that EPR correlations exhibit the same detection profile says nothing about locality when the same effect occurs without any correlations involved. EPR correlations, in this view, would only indicate the mechanism is deterministically replicable.This is the way everyone would think about it in the absence of interpretations of Bell to the contrary. And, this is why it's so important to continue to examine the assumptions underlying Bell's formulation. A couple of generations of professionals in the field going back and forth on what BI violations mean is reason enough to think that it's just possible that some subtle point which would render Bell's theorem physically irrelevant (except for it's possible application as an indicator of the presence and degree of entanglement) has been glossed over.

Here is an interest paper by Michael Seevinck, which rigorously derives a version of Bell's inequalities for correlations.
The Quantum World is Not Built Up From Correlations.
Found. Phys. 36, 1573-1586 (2006)I just briefly looked at this so far, but it would seem to support the idea that the nature of entanglement is relationships between and among things. Not things in themselves. Whether or not we see entanglement depends on how we look at things. Hence the nonseparability of the relationship between (the relationship between) the things being observed and the observational context. Which Bell doesn't quite capture in his LR ansatz.

DrChinese

Jun7-10, 01:51 PM

It was from evaluations along these lines that suggested to me that there might be something wrong with Bell's formulation. For example, if EPR elements of reality are too restrictively represented, or if the statistical independence represented by Bell's equation (2) supercedes it's represention of causal independence between A and b (B and a), then Bell's formulation isn't logically rigorous, and violations of BIs aren't physically relevant.

If you are going to make statements like this, you had better back it up.

So perhaps you can give me an example if how a) EPR elements of reality are too restrictive; b) a classical case in which Bell's (2) is violated when considering the full universe.

In other words, what is wrong with Bell's definitions (other that you don't like the conclusions they inevitably lead to) ?

ThomasT

Jun7-10, 01:51 PM

They most certainly ARE polarization clones of each other. And they are entangled. But they are not polarization entangled, which is quite different.How do we know that they're polarization clones of each other if they don't produce entanglement stats?

Also, if ...the only difference in producing the entangled state versus the product state is a small rotation of a wave plate.That wouldn't seem to indicate that they're "quite different", unless we are to assume that a "small rotation of a wave plate" somehow switches on some sort of action at a distance or ftl communication between the photons.

If we accept your physical assumption of "counter-propagating influences", then these should produce the same statistics as entangled particles. But they don't.The fact that a wave plate rotation is required to produce polarization entanglement would seem to indicate that they weren't clones of each other to begin with. Or, maybe the wave plate rotation keeps them cloned but adjusts some other parameter which then results in entanglement. Or, maybe the wave plate rotation unclones them, and then, since they're uncloned they have to communicate via action at a distance or ftl to be 'entangled'.

Now why are these particles acting different? Because they are NOT in a superposition of polarization states. This is meaningful within QM but has no counterpart in a local realistic theory - in which there is no such thing as a superposition (by definition).I think we both agree that (1) quantum superposition and quantum entanglement can't be understood in terms of separable (factorable) combinations of the individual systems. However, contrary to (1), (2) Bell (via a certain interpretation of the scope of EPR's definition of reality) has required LR models of entanglement to be represented in a separable form which contradicts the reality of the experimental situations to which that form is being applied. The paper that you referenced agrees with (1). So does every other paper I've read on this. I haven't found anything yet that specifially addresses (2), except for viable LR models that, in agreement with (1), encode the fact that joint detection is determined by different parameters than those which determine individual results -- but, according to you, we can't accept those because their predictions agree with qm and experiments.

By the way, thanks for the reference. My 'assertion' wrt a simplified 'realistic' view of the underlying optical disturbances is probably much too simplistic. It does seem to work for entangled photons produced by atomic cascades though. I'm just beginning a study of OPDC. So, my little simplification might turn out to be ridiculous.

Here's another paper (you've probably read it) that some viewers might be interested in. There's lots of good stuff at Sergienko's group's website.

http://people.bu.edu/alexserg/PRL3893_1993.pdf
Einstein-Podolsky-Rosen-Bohm Experiment Using Pairs of Light Quanta Produced by Type-II Parametric Down-Conversion
Authors:T.E. Kiess, Y.H. Shih, A.V. Sergienko, and C.O. Alley
Phys. Rev. Lett. v.71, pp. 3893-3897 (1993)

So far I don't find anybody saying that the correlations are due to action at a distance or ftl. Eg., in the paper referenced below, they define nonlocality rather innocuously (and in fact state that action at a distance isn't indicated). I think this might be the way that lots (most?) physicists think about it. Quantum nonlocality doesn't mean nonlocality. (The first link might time out, so I included a link to the preprint version.)

http://qopt.postech.ac.kr/publications/PhysRevA-60-p2685.pdf
http://arxiv.org/PS_cache/quant-ph/pdf/9811/9811060v1.pdf
Experimental study of a photon as a subsystem of an entangled two-photon state
Authors: Dmitry V. Strekalov, Yoon-Ho Kim, Yanhua Shih
Phys. Rev. A v.60, pp. 2685-2688 (1999)

The fact is that entangled particles have attributes that do not follow a local realistic explanation.Only wrt Bell's LR model. Which we know doesn't fit the requirements of the experimental situation.

Considering the small experimental differences necessary for entanglement vs nonentanglement stats, and the fact that even LR models conforming to Bell's restrictions aren't that far away from qm predictions, and the fact that there are viable LR models that don't conform to Bell's restrictions, all support the idea that the 'problem of nonlocality' has to do with the way things are being talked about, and not anything to do with the existence of action at a distance or ftl anything.

Talk to Bell about this. Or God. I did not create our universe, so it is not my requirement. Next you will be complaining about the 4 color map theorem as being "inane".The 4 color map theorem is logically rigorous. Bell's assessment of the form that an LR model of entanglement must take isn't.

Anyway, the requirement than any LR model in any form be incorrect is your requirement. You've been shown LR models whose predictions agree with those of qm and experimental results -- and your response is that you want them to produce a dataset that disagrees with qm and experimental results.

I know how you got there (there's only one way -- Bell's way), but wouldn't it make sense to at least look at them and evaluate whether they're realistic and/or local instead of dismissing them because they're quantitatively correct?

I'm going to keep my Bell talk to a minimum for the time being. You've opened up a whole new world for me with the OPDC stuff, and I feel compelled to learn as much about it as I can. (Hmmmm, maybe there is a method to your madness.) Anyway, thanks again.

ThomasT

Jun7-10, 02:00 PM

If you are going to make statements like this, you had better back it up.

So perhaps you can give me an example if how a) EPR elements of reality are too restrictive; b) a classical case in which Bell's (2) is violated when considering the full universe.

In other words, what is wrong with Bell's definitions (other that you don't like the conclusions they inevitably lead to) ?Wrt a), they're in the literature, and they encode the more reasonable interpretation of EPR's conception of reality that would allow joint detection to be represented in a nonseparable form. Wrt b), I don't understand what you're asking.

Bell represented locality via the factorability (separability) of the joint situation which is entailed by the requirement to represent joint detection in terms of individual detections. However, because this isn't the reality of the joint situation, then the locality condition's relevance to locality is screened out or superceded by the fact that the joint situation is being modelled in terms of individual parameters which simply can't be combined in the way that Bell requires them to be combined (and also correctly model the nonseparability of the experimental situation) in his LR model.

my_wan

Jun7-10, 04:50 PM

This empirical fact may or may not have a realistic basis.What do you mean by this? That the cos^2 theta rule can't be understood realistically?No, that's not what I mean. But, at the end of the day, pragmatism trumps preconceptions. The empirical is what you take to the bank. We don't get to decide what nature is and isn't. I have an extensive list of classical analogs of QM, but in the general case it still breaks, and why it always breaks is tied with the issues in BI violations in some ways. So just because I agree with you, in principle, that there may be realistic mechanisms by some definition, I can't claim it must be so just because I can justify it in principle. It's just as unreasonable to marginalize people for trying, as it is unreasonable to claim what is true based solely on what can be heuristically justified.

%%%%%%%%%%
I reject the idea that a realistic theory is possible. It is really that simple. My definition of reality being the same as the EPR definition: if it can be predicted in advance, there must be an element of reality. But there cannot be 3 simultaneously real.Here's a simplistic fundamental issue I have with that: Given an initial condition and momentums of a set of pool balls, I can predict in advance the topology of those balls will form an X. Does that make the X an 'element of reality' of those balls? If a measuring instrument simply selects a range of topologies, consistent with some condition, what does that leave you with wrt realism in EPR. I'll make this even clearer wrt Mermin's work you mention below.

This is not a requirement of QM, and in no way is QM given a preferred status in Bell other than by way of comparison.Which was exactly my point. Bell counterfactually imposed a condition on QM that QM doesn't allow.

You cannot get a realistic theory with ANY function where there is rotational invariance, as Mermin demonstrated. Hess has provided nothing for me to reject other than his conclusion. There is no realistic model. Again.Thanks for reminding me of this! In fact this is a fully general feature of all vectors, including vectorial components of classical objects!

Consider a pair of unit vectors, P and Q. You can even view them as a pair of balls colliding in space.
Rx = PxQx
Ry = PyQy
Rz = PzQz

Now we consider the perpendicular case:
Rx = 0
Ry = 0
Rz = 0

But, if we rotate this coordinate system 45 degrees we get:
Rx = 1/2
Ry = -1/2
Rz = 0

But nature doesn't care how we labeled our coordinate system, or that these labels give us incongruent results wrt values. The fact remains that 'reality' is the same (even the same instance of reality) no matter how we choose our coordinate basis. If we claim unreality on the grounds that 1/2 = -1/2 = 0 is false, that's our problem, not one of reality. The arbitrary angle verses relative offset requirement in BI imposes this absolutely general mathematically incongruent wrt values of ALL vectors, not just polarizer settings in EPR experiments, but ANY classical vector.

Based on this, following the BI version of realism, it's trivially provable that, since vectorial components of pool balls is a measurable property, pool balls are not real.

QM does not ask for counterfactuality, so your argument is backwards. It is realism that requires extra assumptions, not QM.Again :surprised
That was exactly my point. It was imposed on QM, not asked for by QM. In fact I went farther and said it's invalid under QM alone, just as it's invalid as settings for 3 unfair coins. It remains confusing how my point is continually objected to by making my point.

So if you think these requirements are absurd, well, that would simply mean you reject realism. Sorry, but you cannot have your cake and eat it too.So if realism requires this extra assumption, this means that, since the vectorial components of pool ball collisions are measurable, yet incongruent wrt values, pool balls can't be real.

So define realism however you like. Define it like Hess if that makes you happy (or whatever his latest absurd definition of the week happens to be). But I won't agree that day is night, that blue is red, or whatever. I will stick with Einstein's elements of reality.I don't agree that 1/2 = -1/2 = 0 either, but if that means I'm supposed to define the pool balls as not real on these grounds, I'll pass.

billschnieder

Jun7-10, 05:46 PM

That may be the strongest objection yet. Like trying to define 3 coins that can all land on opposite sides, because couterfactually any 2 can.
You may be interested in this post from a previous thread that discusses the issue raised by Hess, clearly showing that correct labelling of variables is paramount to understanding violations of BIs.
Trying to Understand Bell's reasoning, post #69 (http://www.physicsforums.com/showpost.php?p=2707087&postcount=69)

Consider a certain disease that strikes persons in different ways depending on circumstances. Assume that we deal with sets of patients born in Africa, Asia and Europe (denoted a,b,c). Assume further that doctors in three cities Lyon, Paris, and Lille (denoted 1,2,3) are are assembling information about the disease. The doctors perform their investigations on randomly chosen but identical days (n) for all three where n = 1,2,3,...,N for a total of N days. The patients are denoted Alo(n) where l is the city, o is the birthplace and n is the day. Each patient is then given a diagnosis of A = +1/-1 based on presence or absence of the disease. So if a patient from Europe examined in Lille on the 10th day of the study was negative, A3c(10) = -1.

According to the Bell-type Leggett-Garg inequality

Aa(.)Ab(.) + Aa(.)Ac(.) + Ab(.)Ac(.) >= -1

In the case under consideration, our doctors can combine their results as follows

A1a(n)A2b(n) + A1a(n)A3c(n) + A2b(n)A3c(n)

It can easily be verified that by combining any possible diagnosis results, the Legett-Garg inequalitiy will not be violated as the result of the above expression will always be >= -1, so long as the cyclicity (XY+XZ+YZ) is maintained. Therefore the average result will also satisfy that inequality and we can therefore drop the indices and write the inequality only based on place of origin as follows:

<AaAb> + <AaAc> + <AbAc> >= -1

Now consider a variation of the study in which only two doctors perform the investigation. The doctor in Lille examines only patients of type (a) and (b) and the doctor in Lyon examines only patients of type (b) and (c). Note that patients of type (b) are examined twice as much. The doctors not knowing, or having any reason to suspect that the date or location of examinations has any influence decide to designate their patients only based on place of origin.

After numerous examinations they combine their results and find that

<AaAb> + <AaAc> + <AbAc> = -3

They also find that the single outcomes Aa, Ab, Ac, appear randomly distributed around +1/-1 and they are completely baffled. How can single outcomes be completely random while the products are not random. After lengthy discussions they conclude that there must be superluminal influence between the two cities.

But there are other more reasonable reasons. Note that by measuring in only two citites they have removed the cyclicity intended in the original inequality. It can easily be verified that the following scenario will result in what they observed:

- on even dates Aa = +1 and Ac = -1 in both cities while Ab = +1 in Lille and Ab = -1 in Lyon
- on odd days all signs are reversed

In the above case
<A1aA2b> + <A1aA2c> + <A1bA2c> >= -3
which is consistent with what they saw. Note that this equation does NOT maintain the cyclicity (XY+XZ+YZ) of the original inequality for the situation in which only two cities are considered and one group of patients is measured more than once. But by droping the indices for the cities, it gives the false impression that the cyclicity is maintained.

The reason for the discrepancy is that the data is not indexed properly in order to provide a data structure that is consistent with the inequalities as derived.Specifically, the inequalities require cyclicity in the data and since experimenters can not possibly know all the factors in play in order to know how to index the data to preserve the cyclicity, it is unreasonable to expect their data to match the inequalities.

For a fuller treatment of this example, see Hess et al, Possible experience: From Boole to Bell. EPL. 87, No 6, 60007(1-6) (2009)

Note that in deriving Bell's inequalities, Bell used Aa(l), Ab(l) Ac(l), where the hidden variables (l) are the same for all three angles. For this to correspond to the Aspect-type experimental situation, the hidden variables must be exactly the same for all the angles, which is an unreasonable assumption because each particle could have it's own hidden variables with the measurement equipment each having their own hidden variables, and the time of measurement after emission itself a hidden variable. So it is more likely than not that the hidden variables will be different for each measurement. However, in actual experiments the photons are only measured in pairs (a,b), (a,c) and (b,c). The experimenters, not knowing the exact nature of the hidden variables, can not possibly collect the data in a way that ensures the cyclicity is preserved. Therefore, it is not possible to perform an experiment that can be compared with Bell's inequalities.

DrChinese

Jun7-10, 06:41 PM

Wrt a), they're in the literature, and they encode the more reasonable interpretation of EPR's conception of reality that would allow joint detection to be represented in a nonseparable form. Wrt b), I don't understand what you're asking.

I am asking for a reference for these alternative reasonable definitions. I am not familiar with any others generally out there. I have yet to see actual proposed ones.

As to b): if you think there is a classical counterexample, give it! And please, nothing where we have an unfair sample of doctors or similar. A full universe. You won't be able to do it!

DrChinese

Jun7-10, 06:45 PM

Which was exactly my point. Bell counterfactually imposed a condition on QM that QM doesn't allow.

You still have it backwards. QM has nothing to do with it. And I don't follow your pool ball example.

DrChinese

Jun7-10, 06:47 PM

You may be interested in this post from a previous thread that discusses the issue raised by Hess, clearly showing that correct labelling of variables is paramount to understanding violations of BIs.
Trying to Understand Bell's reasoning, post #69 (http://www.physicsforums.com/showpost.php?p=2707087&postcount=69)

Again, this example is an attempt to show that there is an unfair sample of a full universe. This is not Bell at all. For Bell, you use a full universe of trials.

ThomasT

Jun7-10, 07:44 PM

I am asking for a reference for these alternative reasonable definitions. I am not familiar with any others generally out there. I have yet to see actual proposed ones.

As to b): if you think there is a classical counterexample, give it! And please, nothing where we have an unfair sample of doctors or similar. A full universe. You won't be able to do it!The few that I know of aren't published. Just in preprint. You're probably aware of most, if not all, of them. Since it's unlikely that any of it will get published, there's not much to discuss.

By the way, after thinking about it, I think you're right about Bell's (2) wrt EPR settings. There's nothing special about these settings except that a certain LR implementation of Bell's (2) does agree with qm for EPR settings (and |a-b|=45o). But other than that no. And after looking at Bell's paper more closely it does seem that he's showing that an LR implementation of (2) is incompatible with all qm predictions for any settings.

my_wan

Jun7-10, 08:02 PM

You still have it backwards. QM has nothing to do with it. And I don't follow your pool ball example.

But QM does have something to do with it. QM says the counterfactual case is interfered with by some some mechansim, often presumed FTL. Perhaps it's really interefereing with the absurdity the pre-conditions placed on the HV's from the start.

When you say you don't follow my pool ball example, what don't you get? Can you look at any single vectorial outcome of a classical interaction, and ask what that vectorial product looks like under different coordinate rotations? The 'values' of the 'predicted' measurables are incompatible wrt those 'values' obtained under an arbitrary coordinate rotation. Per the realism definition the predictability of those values, given any particular rotation, requires us to defines those vectorial products as 'elements of reality'. But rotate your coordinate system on this same physical event and your value obtained from this 'element of reality' becomes inconsistent with the prior 'value' of the same event.

DevilsAvocado

Jun7-10, 08:35 PM

And please, nothing where we have an unfair sample of doctors or similar.

:rofl: :rofl: :rofl:

ThomasT

Jun7-10, 08:40 PM

No, that's not what I mean. But, at the end of the day, pragmatism trumps preconceptions. The empirical is what you take to the bank. We don't get to decide what nature is and isn't. I have an extensive list of classical analogs of QM, but in the general case it still breaks, and why it always breaks is tied with the issues in BI violations in some ways. So just because I agree with you, in principle, that there may be realistic mechanisms by some definition, I can't claim it must be so just because I can justify it in principle. It's just as unreasonable to marginalize people for trying, as it is unreasonable to claim what is true based solely on what can be heuristically justified.Thanks for the reply. Some interesting considerations for future threads.

my_wan

Jun7-10, 09:26 PM

Again, this example is an attempt to show that there is an unfair sample of a full universe. This is not Bell at all. For Bell, you use a full universe of trials.No, only that's it's, in principle, possible that the sampling used by Bell isn't valid. It has nothing to do with the full universe's sampling, and everything to do with how we choose to define our sampling of it.

Wrt the vector argument, there's a very simple reason vectors are not generally rotation invariant. When looking at the product of a pair of vectors, the defining vectors are indeterminate. That is there is an arbitrarily large possible number of vector pairs that could have created that vector. That 1 vector can even represent the result of an arbitrarily large number of products from actual vectors.

So when Bell's inequalities specifies any arbitrary theta must be modeled to avoid FTL, it could be requiring the particular vectorial instances that defined a vector to be uniquely identified after the fact. This is impossible even for the product of a single pair of vectors, given only a single resulting vector.

---------
I hoped a more reasonable objection would be posed. Like the fact that the pool ball example doesn't define a rotationally invariant function, like Mermin defined. Whereas QM is dependent on the existence rotationally invariant functions. So how can a rotationally invariant functions represent anything real, if the pool ball analogy holds?

Consider a particle with a real default polarization. The default polarization is -only- unique in that a polarizer at that setting has essentially a 100% chance of passing that particle, but offsets can also pass some of the time via cos^2(theta). If the default polarization is completely randomized over a large group of particles, it's physically impossible for any one polarizer setting to uniquely define a statistical function unique to a given polarizer setting. Only the particular sequence of detections can be unique, case instances of a probability which, by definition, are not themselves probabilities, which are later used to define the coincidences. Thus probability functions, not the case instances that result from them, are physically -required- to be rotationally invariant.

This would explain also why I could only model inequality violations, in my computer simulations, if I restricted one or the other setting to be defined at 0 angle. Even though the 0 angle could be arbitrarily chosen, and this didn't uniquely identify the other detector setting in calculating the detection sequence for later comparison to derive coincidences. Perhaps I should attempt to replace my binary bits with some form of predefined sets of vectors.

billschnieder

Jun7-10, 10:58 PM

Again, this example is an attempt to show that there is an unfair sample of a full universe. This is not Bell at all. For Bell, you use a full universe of trials.

I suspect you have ready to produce a citation to a published example of an experiment in which they made absolutely sure that the full universe of all possible values of all hidden variables was realized.

In any case, the point of the example is that by making similar errors in macroscopic situations, you can create FTL paradoxes at the macroscopic level too.

As my_wan already explained, the error is NOT the fact that the data is incomplete or sampled unfairly. The error is the fact that the data is not properly indexed according to the contexts. In other words, multiple contexts are mixed together in a manner not expected by the inequalities, such that the only cases for which the inequalities will be universally valid irrespective of how the data is indexed, are non-contextual variables.

DrChinese

Jun8-10, 08:30 AM

I suspect you have ready to produce a citation to a published example of an experiment in which they made absolutely sure that the full universe of all possible values of all hidden variables was realized...

I think you are admitting that Bell is correct. There is no local realistic universe.

And we have already been through the bit about the fair sampling. There are a number of experiments that do not require the fair sampling assumption that I have already referenced. You reject all counterevidence so it is meaningless to discuss this with you.

I suspect you even like the Monkees more than the Beatles. :biggrin:

DrChinese

Jun8-10, 08:36 AM

So when Bell's inequalities specifies any arbitrary theta must be modeled to avoid FTL, it could be requiring the particular vectorial instances that defined a vector to be uniquely identified after the fact. This is impossible even for the product of a single pair of vectors, given only a single resulting vector.

...

This would explain also why I could only model inequality violations, in my computer simulations, if I restricted one or the other setting to be defined at 0 angle. Even though the 0 angle could be arbitrarily chosen, and this didn't uniquely identify the other detector setting in calculating the detection sequence for later comparison to derive coincidences. Perhaps I should attempt to replace my binary bits with some form of predefined sets of vectors.

All it takes is one.

my_wan

Jun8-10, 10:12 AM

All it takes is one.
What conditions must be met to qualify as this "one"? Does it require an explicit theory that explains exactly the mechanism by which BI violations occur? Does is simply require a toy models which mimics such violations? Are these (toy) models required to be rotational invariant, in spite of the fact that you pointed out Mermin showed rotational invariance entail non-real variables? Are you denying that realistic classical variables exist that lack rotational invariance?

Why do I ask so many questions at once? Because I give detailed explanations and spread dozens of questions and you never answer anyway, so I ask in irony. You responses, or lack of, are tipping my scales.

Look at how you just now responded to the -RAW- sarcasm of billschnieder, by accusing him of an admission of your point of view.

I think you are admitting that Bell is correct. There is no local realistic universe.

And we have already been through the bit about the fair sampling. There are a number of experiments that do not require the fair sampling assumption that I have already referenced. You reject all counter evidence so it is meaningless to discuss this with you.

I suspect you even like the Monkees more than the Beatles. :biggrin:

The "fair sampling" accusation here is facetious as hell., and you know it. You've taken a prior issue, where the sampling accuracy of the experimental data was questioned, and pretending it's the same argument contained in a toy model describing contextually of variables. I think you know good and well that "fair sampling" is a separate issue, and if I'm wrong, why respond to explanations that its not with accusations of your opponents admitting they are wrong in the same post they are explaining this to you?

You've continually mirrored my points, as if they were a denial of my points. You've claimed ignorance repeatedly, even of something so simple as a vectorial product before and after a coordinate rotation. Failed to explain your position when asked. Failed to even explain what you claimed not to understand, even when asked. Continually, and chronically, fail to provide any context, or justification, or explanation, to your rebuttals. You even fail to specify what, in post for which much effort was put in, your rebuttals actually refer to in that post.

What's your point of even debating here? To run authoritative interference of any viewpoints you don't like?

Show me I'm wrong, and answer some questions. Ask some questions if somethings not clear. But to simply keep accusing people of viewpoints they are expending great effort and honest feedback to deny, with no good faith return rebuttals, appears awfully bad to me. My apologies for the aggravation, but it appears well called for when I'm not the only one getting this treatment, and others seem to understand what you deny understanding of. Without even the courtesy of questions indicate where the clarity was lacking, only accusations of admissions to your point of view.

The real shame is that you have a perspective I really really want to understand.

DevilsAvocado

Jun8-10, 10:25 AM

Changes in the set up are all that you need to change the distribution of outcomes -- you don't need any 'thing' other than equipment characteristics, i.e., no reference to quantum entities, waves, etc. For example, see section 4.3 Geometrical Account of QLE starting on p 28 of our FoP paper, http://users.etown.edu/s/stuckeym/FOP%202008.pdf. In particular notice how how Eq. 31 becomes Eq. 32 on p. 29.

Thanks RUTA, for the interesting paper.
Reconciling Spacetime and the Quantum:
Relational Blockworld and the Quantum Liar Paradox (http://users.etown.edu/s/stuckeym/FOP%202008.pdf)

W.M. Stuckey • Michael Silberstein • Michael Cifone

...
It is now generally believed that Einstein-Podolsky-Rosen (EPR) correlations, i.e., correlated space-like separated experimental outcomes which violate Bell’s inequality, force us to abandon either the separability or locality principle.
...
As we will show, the Relational Blockworld [9–11] interpretation of NRQM points to a far more intimate and unifying connection between spacetime and the quantum than most have appreciated.
...
RBW employs the spatiotemporal relations via symmetries of the entire (past, present and future) experimental configuration and is thus fundamentally kinematical. And unlike other BW inspired accounts of quantum mechanics such as BCQM, RBW is truly acausal, adynamical and atemporal.

I guess that in this field of view you are right – there is nothing 'special' about the wires 'interacting' with the wave function in the Afshar experiment – it’s just a different setup that generates a different mathematical (RBW) formula to explain what happens.

For a layman like me it’s quite easy, if one has to make a choice of, what can be consider more real than the other – and I intuitively choose the experiment and the physical wires, not the RBW mathematics, as my reality. Maybe future progress in science can physically prove me wrong – and then I have to change my mind, whether I like it or not.

Another 'objection' I have against RBW is the way you get rid of 'one problem' (separability vs. locality principle) by introducing another (to me stranger) 'phenomena' in; symmetries of the entire past, present and future + truly acausal, adynamical and atemporal...?

It doesn’t give me that 'natural' "WOW-feeling"... but maybe it’s idiocy to look/hope for some "human/natural/logical" explanation to what’s going on in the QM-world... ?:bugeye:?

DrChinese

Jun8-10, 11:56 AM

What conditions must be met to qualify as this "one"? Does it require an explicit theory that explains exactly the mechanism by which BI violations occur? Does is simply require a toy models which mimics such violations? Are these (toy) models required to be rotational invariant, in spite of the fact that you pointed out Mermin showed rotational invariance entail non-real variables? Are you denying that realistic classical variables exist that lack rotational invariance?

Why do I ask so many questions at once? Because I give detailed explanations and spread dozens of questions and you never answer anyway, so I ask in irony. You responses, or lack of, are tipping my scales.

Look at how you just now responded to the -RAW- sarcasm of billschnieder, by accusing him of an admission of your point of view.

The "fair sampling" accusation here is facetious as hell., and you know it. You've taken a prior issue, where the sampling accuracy of the experimental data was questioned, and pretending it's the same argument contained in a toy model describing contextually of variables. I think you know good and well that "fair sampling" is a separate issue, and if I'm wrong, why respond to explanations that its not with accusations of your opponents admitting they are wrong in the same post they are explaining this to you?

You've continually mirrored my points, as if they were a denial of my points. You've claimed ignorance repeatedly, even of something so simple as a vectorial product before and after a coordinate rotation. Failed to explain your position when asked. Failed to even explain what you claimed not to understand, even when asked. Continually, and chronically, fail to provide any context, or justification, or explanation, to your rebuttals. You even fail to specify what, in post for which much effort was put in, your rebuttals actually refer to in that post.

What's your point of even debating here? To run authoritative interference of any viewpoints you don't like?

Show me I'm wrong, and answer some questions. Ask some questions if somethings not clear. But to simply keep accusing people of viewpoints they are expending great effort and honest feedback to deny, with no good faith return rebuttals, appears awfully bad to me. My apologies for the aggravation, but it appears well called for when I'm not the only one getting this treatment, and others seem to understand what you deny understanding of. Without even the courtesy of questions indicate where the clarity was lacking, only accusations of admissions to your point of view.

The real shame is that you have a perspective I really really want to understand.

I have repeated indicated that it is not possible to come up with a local realistic dataset. That is all it takes to refute Bell. You tried and failed, as have others - including myself! Yes, I have tried to break Bell many times and this has taught me where its strengths are.

I am trying to be patient, but what I actually have on my hands is people who deny a standard scientific viewpoint which has been scrutinized by thousands. Which has over a thousand papers published annual with both theoretical and experimental support. And you are treating my position - the standard one - as if it requires non-stop defense. Well, actually the burden is on you.

Yes, I know that science can be wrong but that possibility does not make it wrong and is in NO WAY a help to your position. It should give you pause, however, in your assertions. I know that whenever I find myself speculating against the mainstream, that is usually a sure sign that I need to do some additional research. I do actively disagree with some scientific research - especially in the area of human research studies - but I temper that with the desire to present something USEFUL in its place. I have repeatedly suggested that

It does little good for you to say "I reject standard definitions" and "I need more proof". I can't provide that for you, and in fact no one can. Only you can do that.

-----------------------------

If you think that Bell is wrong, consider one of the following:

a) Come up with a dataset. You should have already learned the difficulty with this after developing your model.
b) Come up with a different and better definition of locality that yields the possibility of a local realistic dataset (under this revised definition). Then present it and see if others accept this as an alternative definition.
c) Come up with a different and better definition of realism that yields the possibility of a local realistic dataset (under this revised definition). Then present it and see if others accept this as an alternative definition.

As to the fair sampling assumption: billschnieder brought it up again, not me. It does not properly belong in discussions of EPR and Bell, instead is more appropriate to the evaluation of Bell tests. I take this area quite seriously and am involved in active research into such models, specifically looking at the De Raedt local realistic models. But please note: they are the ONLY team that has EVER - to my knowledge - provided a local realistic dataset to critique. So you are far off the mark, my friend. Give me something specific that addresses the meat of the subject.

Stuff like your billiard ball example - and billschnieder's African doctors - does not come close. This is the quantum world, and experimentalists are running hundreds of experiments that are flat out in contradiction to the local realistic world.

my_wan

Jun9-10, 12:20 AM

I have repeated indicated that it is not possible to come up with a local realistic dataset. That is all it takes to refute Bell. You tried and failed, as have others - including myself! Yes, I have tried to break Bell many times and this has taught me where its strengths are.
The only failure I had was rotational invariance in the underlying mechanism, which did not destroy rotational invariance in the sense that it made no difference how the coordinate system was rotated. Thus in spite of lacking rotational invariance, like ALL classical mechanisms, it was in fact coordinate independent. This is nothing new in the literature. Consider:
Rotational invariance as an additional constraint on local realism (http://arxiv.org/abs/quant-ph/0407232)
Phys. Rev. Lett. 93, 230403 (2004)

Rotational invariance of physical laws is a generally accepted principle. We show that it leads to an additional external constraint on local realistic models of physical phenomena involving measurements of multiparticle spin 1/2 correlations. This new constraint rules out such models even in some situations in which standard Bell inequalities allow for explicit construction of such models. The whole analysis is performed without any additional assumptions on the form of local realistic models.

Are you denying that such models exist? You have pointed out that Mermin showed rotational invariance cannot be mimicked by any realistic mechanism. I showed why not even the vectorial product of a pool ball collision is rotational invariant, though you deemed it incomprehensible. So any such underlying realistic mechanism can't be rotational invariant.

Yet it's trivial to show that any probability function written for a randomized rotation of a mechanism lacking rotational invariance will itself be rotational invariant. Do you deny this?

If you cannot deny both of the red questions, then the only way to deny the possibility of realistic models is to invoke rotational invariance is to invoke it as -fundamental-, rather than a probabilistic result of a mechanism lacking rotational invariance. But that only invokes the completeness claim of QM that Einstein denied, in order to deny the incompleteness LHV's depend on to attempt such models to begin with! It's having your cake and eating it to.

Yes, I want a very specific answer to BOTH of those questions. What opinion you indicate based on authority means nothing.

Here are the questions again for which even a yes/no answer would be a breakthrough:
1) Do coordinate independent LHV models of BI violations exist that lack rotational invariance?
2) Does a rotational invariant probability function exist for any mechanism with a randomized rotation?

Answers are non-negotiable.

ThomasT

Jun9-10, 12:24 AM

...... snip long tirade re DrC ....

The real shame is that you have a perspective I really really want to understand.

I agree with much of what you said in your tirade re DrC. But since I have learned much from him (as well as you and others) I have wanted to give him the benefit of the doubt and simply assume that he had a deeper understanding of Bell's theorem -- and then proceed to present my current lines of thought via my still developing comprehension of the subject in a sort of authoritative style. Despite the fact that my thinking has been wrong wrt certain details, or maybe because of it, I've learned from these recent Bell threads.

Wrt DrC's perspective on Bell, it seems pretty clear to me that he thinks that Bell's LR construction is unassailable and physically significant -- so that even if Bell locality doesn't represent locality, that, nevertheless, Bell's modelling of the experimental situation does indeed represent the reality of the experimental situation -- and hence nature is either nonlocal or, well, I'm not sure what the alternative (wrt reality) is. The possibility that Bell's ansatz might not actually be representing the reality of the situation, and therefore be physically insignificant, simply isn't considered. *

So, vetting your ideas to someone of that persuasion is something of a nonstarter. Of course, the difficulty of the task for those who think there might be something about Bell's treatment, and certain interpretations thereof, that isn't quite right is compounded by the apparent fact that DrC's view is the mainstream view (at least wrt the set of physicists who have an opinion re Bell). So, there are few published articles (quite a few preprints, but they're off limits for discussion here) and very little discussion by professionals of the approaches they present.

Anyway, I think that I understand, superficially at least, and conceptually to a certain extent, what you're talking about -- and it's interesting.
-------------------------------------------
* (The upside to Bell's theorem, even if it's eventually generally interpreted to be physically insignificant, is that it will remain extremely significant because of what it's generated experimentally, theoretically, and philosophically.)

my_wan

Jun9-10, 12:55 AM

ThomasT,
I to have benefited from DrC. I'm more than happy to have any notions I present here completely destroyed. That's the only reason I take one side of the debate, knowing that it's open to be destroyed.

My tripping point was not his denials, nor his opinions. My tripping point was consistent, chronic, failures to respond to any rebuttals, or even reference what specifically was the issue in his general denials.

DrChinese

Jun9-10, 08:47 AM

The only failure I had was rotational invariance in the underlying mechanism, which did not destroy rotational invariance in the sense that it made no difference how the coordinate system was rotated. Thus in spite of lacking rotational invariance, like ALL classical mechanisms, it was in fact coordinate independent. This is nothing new in the literature. Consider:
Rotational invariance as an additional constraint on local realism (http://arxiv.org/abs/quant-ph/0407232)
Phys. Rev. Lett. 93, 230403 (2004)

Are you denying that such models exist? You have pointed out that Mermin showed rotational invariance cannot be mimicked by any realistic mechanism. I showed why not even the vectorial product of a pool ball collision is rotational invariant, though you deemed it incomprehensible. So any such underlying realistic mechanism can't be rotational invariant.

Yet it's trivial to show that any probability function written for a randomized rotation of a mechanism lacking rotational invariance will itself be rotational invariant. Do you deny this?

If you cannot deny both of the red questions, then the only way to deny the possibility of realistic models is to invoke rotational invariance is to invoke it as -fundamental-, rather than a probabilistic result of a mechanism lacking rotational invariance. But that only invokes the completeness claim of QM that Einstein denied, in order to deny the incompleteness LHV's depend on to attempt such models to begin with! It's having your cake and eating it to.

Yes, I want a very specific answer to BOTH of those questions. What opinion you indicate based on authority means nothing.

Here are the questions again for which even a yes/no answer would be a breakthrough:
1) Do coordinate independent LHV models of BI violations exist that lack rotational invariance?
2) Does a rotational invariant probability function exist for any mechanism with a randomized rotation?

Answers are non-negotiable.

You make me laff. Non-negotiable? :biggrin:

Apparently you are not aware of PhysicsForums policy regarding personal theories. Generally, these are not allowed. That is why I repeatedly mention that what I am saying is standard, accepted physics. Not because it is a resort to authority. Not that authoritative sources are bad, they are the best. But as I said before, it only takes one.

So to answer some of your "questions": Yes, I deny that that rotational invariance cannot be modeled by any local realistic theory. But I do think it is a constraint. In fact, thatnks for the reference, not sure if I had seen that or not. Can such models be constructed or whatever it is you ask? I guess so, haven't thought much about it and don't plan to. The problems of constructing local realistic theories is not one of my priorities as I follow Bell. Apparently you have convinced yourself that local realistic theories cannot be constructed for other reasons. Ergo, you should likewise reject local realism as I do.

I am not otherwise sure why you are focusing on rotational invariance, in fact I am not even sure we are talking about the same thing. In my mind, rotational invariable is getting the same answer in any rotated reference frame. There can be no preferred frame. You model suffered from the problem that it appears to work as long as one of the angles is 0 - but not at other angle settings. Therefore it is not rotationally invariant. Is that a requirement of a model? I guess so, because no one has ever done an experiment demonstrating rotational variance. Therefore I would expect any rotational variant model - such as your simulation - to be falsifiable by experiment. A fair requirement, don't you think, that the model be held up to experimental examination? Or is that too much to ask?

DrChinese

Jun9-10, 08:50 AM

(The upside to Bell's theorem, even if it's eventually generally interpreted to be physically insignificant, is that it will remain extremely significant because of what it's generated experimentally, theoretically, and philosophically.)

I think that is praise for Bell.

And yes, I think Bell's logic is unassailable but that certainly doesn't mean it is off limits.

unusualname

Jun9-10, 10:19 AM

DrChinese

Jun9-10, 10:35 AM

Don't want to appear insensitive, but shouldn't someone point out that arguing about the validity of Bell's Theorem experiments seems pretty redundant now, since multi-particle entanglement experiments have trivially demonstrated that local realism fails (and in particular that the EPR argument for it fails)

eg google Greenberger Horne Zellinger (http://www.google.co.uk/search?q=Greenberger%E2%80%93Horne%E2%80%93Zeiling er+local+realism&ie=utf-8&oe=utf-8&aq=t)

Going Beyond Bell's Theorem (http://arxiv.org/abs/0712.0921)

This is a great point!!

In addition to the amazing GHZ, there are also: Hardy's Paradox, Leggett's Theorem, and works by Cabello including ones following Kocken-Specker. And others as well, generally casting strong doubt on ANY form of realism (although for technical reasons, the Bohmians generally believe that non-local realism is not ruled out by these).

[Bill Murray]I'm really close on this one...[/Bill Murray]

my_wan

Jun9-10, 10:42 AM

You make me laff. Non-negotiable? :biggrin:

Apparently you are not aware of PhysicsForums policy regarding personal theories. Generally, these are not allowed. That is why I repeatedly mention that what I am saying is standard, accepted physics. Not because it is a resort to authority. Not that authoritative sources are bad, they are the best. But as I said before, it only takes one.
I have dropped many lines of reasoning to maintain distance from personal theories, and you know it. Neither can you claim that HV models are lacking in the published literature. So you can only claim what you take to be the predominate view toward what is published. Yet few I have spoken to take as absolute a few as what you have expressed. Of course I haven't hired Gallup to give me any numbers on that.

So to answer some of your "questions": Yes, I deny that that rotational invariance cannot be modeled by any local realistic theory.This was not an answer to any question I asked, in any post. It sounds more like you looked at the consequences of actually answering the questions, and chose a preemptive response to those consequences.

But I do think it is a constraint. In fact, thatnks for the reference, not sure if I had seen that or not. Can such models be constructed or whatever it is you ask? I guess so, haven't thought much about it and don't plan to. The problems of constructing local realistic theories is not one of my priorities as I follow Bell. Hmm, that makes your response here suspect:
You tried and failed, as have others - including myself!
:frown:

Apparently you have convinced yourself that local realistic theories cannot be constructed for other reasons. Ergo, you should likewise reject local realism as I do.There you go again. Avoided the questions, and added woefully ridiculous characterizations of other peoples post to claim consistency with you pov.

I am not otherwise sure why you are focusing on rotational invariance, in fact I am not even sure we are talking about the same thing. In my mind, rotational invariable is getting the same answer in any rotated reference frame. There can be no preferred frame.You brought it up, and I thanked you for reminding me. Yes but frame independence is not the same thing as value independence. If you call the pockets on a pool table detectors, then measured outcomes of the exact same physical set of events on the table will be very dependent on the orientation of the table relative to the events on it. Given the trajectory of a pool ball alone, you can't even determine after the fact what angle the q-ball hit it.

You model suffered from the problem that it appears to work as long as one of the angles is 0 - but not at other angle settings. Therefore it is not rotationally invariant.Woefully misleading mischaracterization. In fact the 0 angle of the detector can be anywhere, and you can change the 0 angle to any other 0 angle you wish, anytime. You can also move it to the other detector instead. Because rotating the coordinate system is not a physical thing, because coordinate systems are not a physical thing.

The photons are written as numbers in a text file. So you can create new randomized photons anytime, or use the exact same ones in the same order with 0 angle defined anywhere entirely differently from the last run of the same set of photon numbers, and still get the same BI violations. You can even account for this rotating coordinate system by making sure the photon definition of default orientation is not rotated when you rotate the coordinate system and still get BI violations.

Your characterization is flat out false. It needs a 0 definition for the same reason the self velocity of an inertial observer either needs a 0 self definition or FTL signal to account for a non-zero self velocity definition. Else no 2 observers could ever agree on what the momentum should be under arbitrarily defined self velocities.

Is that a requirement of a model? I guess so, because no one has ever done an experiment demonstrating rotational variance. Therefore I would expect any rotational variant model - such as your simulation - to be falsifiable by experiment. A fair requirement, don't you think, that the model be held up to experimental examination? Or is that too much to ask?My model didn't rotationally vary even when the rotation was varied, only the definitions of the frame of reference was changed to match the various settings. In other words you could also rotate all the default orientations of the individual photons and still get BI violations also. Rotating a coordinate system is non-physical, and either detector can have any -absolute- orientation variations wrt each other in space you want. Do you get it?

But, you still didn't answer my questions. Why is that? Do you wish another try at answering those questions, or is that too tough? You challenged me on negative probabilities before I even found your page on them. I not only demonstrated, by academic definition, that your negative probabilities were not probabilities but case instances, I also demonstrated and identified exactly which case instances they were. Irrespective of any interpretation. Though I provided a possible interpretation also. I now challenge you to a far more basic request: Answer questions!!!

my_wan

Jun9-10, 10:50 AM

Don't want to appear insensitive, but shouldn't someone point out that arguing about the validity of Bell's Theorem experiments seems pretty redundant now, since multi-particle entanglement experiments have trivially demonstrated that local realism fails (and in particular that the EPR argument for it fails)

eg google Greenberger Horne Zellinger (http://www.google.co.uk/search?q=Greenberger%E2%80%93Horne%E2%80%93Zeiling er+local+realism&ie=utf-8&oe=utf-8&aq=t)

Going Beyond Bell's Theorem (http://arxiv.org/abs/0712.0921)

Nobody is arguing the empirical validity of any experiment, or the reality of BI violations in general. Only what is and isn't physically required to model them.

unusualname

Jun9-10, 10:52 AM

Nobody is arguing the empirical validity of any experiment, or the reality of BI violations in general. Only what is and isn't physically required to model them.

But why?

my_wan

Jun9-10, 11:09 AM

But why?
Certainly not because the inequality is wrong, but because it's physical meaning may be taken with a far higher level of generality than what the empirical fact of it justifies.

unusualname

Jun9-10, 11:26 AM

Certainly not because the inequality is wrong, but because it's physical meaning may be taken with a far higher level of generality than what the empirical fact of it justifies.

Maybe, but don't you agree that the subtlety of the arguments are more in the philosophically delicate vein than scientifically interesting? The resolution to your logical conundrums can't be scientifically useful since as you probably know, EPR type arguments have been refuted now using trivial 100% correlation results (see links above) rather than statistical ones.

If you find some doubt in the reasoning attached to the implications of results of Bell experiments, it's a bit like discovering there are logical issues in Newton's Principia.

Your ideas do seem deeply thought out and might make an interesting paper from a historical/philosopical perspective.

And after all the thread title does ask a specific question :smile:

DrChinese

Jun9-10, 11:28 AM

a. Neither can you claim that HV models are lacking in the published literature.

b. Here are the questions again for which even a yes/no answer would be a breakthrough:
1) Do coordinate independent LHV models of BI violations exist that lack rotational invariance?
2) Does a rotational invariant probability function exist for any mechanism with a randomized rotation?

a. The only suitably realistic one is the De Raedt et al model. And by suitably I mean able to generate simultaneous values for a, b, c. (Keep in mind that it exploits the Fair Sampling assumption, which is generally not used by other groups.) ALL of the others are not realistic, i.e. they cannot generate a local realistic dataset. Examples of published failures would be Hess, Phillipp, Santos, Christian, Laudisa, Broda, Matzkin, Thompson etc. If they could provide a dataset, my assumption is that they would - which makes them failures. Many have also be attacked on other grounds (Santos, Hess, Phillipp possibly gaining some kind of records in that regard). De Raedt's, on the other hand, provides an event by event dataset, which I have personally verified. I would be glad to look at anything any of these other authors presents in the way of a realistic dataset. In fact, you can consider it an open challenge.

So there are none such remaining in the literature as far as I am aware. That is my claim.

b. As to your "questions": Sure, let's see if I can be clearer (although these questions are really weird to me):
1. No, because there are NO LHVs that violate Bell inequalities. See Bell.
2. I believe a linear one might work. But I am not an expert in this.

P.S. Your comment about my having tried to find loopholes in Bell ("suspect") is off the mark. It is no different that ways I may have tried to find loopholes in the HUP. Or in other aspects of QM or GR. Just because I follow them does not mean I don't try to push the envelope. No telling what I might learn from trying.

DrChinese

Jun9-10, 11:37 AM

Certainly not because the inequality is wrong, but because it's physical meaning may be taken with a far higher level of generality than what the empirical fact of it justifies.

"No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics."

You think that is shows a physical meaning which is more general than justified empirically?

I don't see this as something which is empirical. Nor do I see it as more general than warranted. Nor am I aware of any physical theory which threatens this conclusion.

my_wan

Jun9-10, 12:10 PM

"No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics."

You think that is shows a physical meaning which is more general than justified empirically?

I don't see this as something which is empirical. Nor do I see it as more general than warranted. Nor am I aware of any physical theory which threatens this conclusion.

Again you have placed a backward interpretation of my words.
1) Yes. BI violations are an empirical fact. That is ALL that empirical means in this case.
2) No, I didn't imply "empirical" meant physical in any way. It's merely a fact that BI violations are an empirical fact.

I don't see this as something which is empirical.
Do you even know what "empirical" means? It means it is an observable fact, independent of any interpretation placed on it.

Nor do I see it as more general than warranted.
Presumably your associating "more general" with the empirical fact itself. An empirical fact is only a repeatable observation. The generality of it applies only to the interpretation, not the empirical fact.

Nor am I aware of any physical theory which threatens this conclusion.I'm not aware of any physical theory which threatens the color orange either. I didn't know it was possible to butcher a parsing of my sentences so badly. Is my English really that bad?

I give up...

DrChinese

Jun9-10, 01:12 PM

Do you even know what "empirical" means? It means it is an observable fact...

Yes. For example: It is an empirical fact that the Bell proof is considered a theoretical/mathematical one, and is not subject to empirical confirmation as an observable fact. Which is why I used it in my statement the way I did. Which is in direct contradiction to your statement.

Listen, you obviously are going to hold your (non-standard) opinion regardless. So I see no benefit to this conversation to either of us. You are able to find your own references supporting realism and casting dispersion on Bell, so I can't help you there either. You are capable of reading the literature and making your own decisions on what you will accept or reject. Further, my references and reasoning are of limited value at this point. Since you clearly think your words make sense - and I do not - I don't see any point of intersection.

All I ask is that you label your opinions going forward as non-standard wherever they are. Otherwise, you will suffer the same fate as ThomasT: I will pick apart your statements because it is wrong for you to use PhysicsForums as a soapbox for personal pet theories. Please see Forum guidelines if you have any questions.

my_wan

Jun9-10, 01:55 PM

Yes. For example: It is an empirical fact that the Bell proof is considered a theoretical/mathematical one, and is not subject to empirical confirmation as an observable fact. Which is why I used it in my statement the way I did. Which is in direct contradiction to your statement.
So here you claim an empirical fact is not subject to empirical confirmation!!!! Or even an observation. Freaking ridiculous beyond belief!!

1 : originating in or based on observation or experience <empirical data>
2 : relying on experience or observation alone often without due regard for system and theory <an empirical basis for the theory>
3 : capable of being verified or disproved by observation or experiment <empirical laws>

Bell's theorem is built on an an ansatz, and the proof that follows is predicated on that ansatz. There is NOTHING empirical about any logic "considered" true by people, no matter how immaculate the logic. Even a well proved theorem by definition can't be an empirical fact. The empirical is what is observed, irrespective of any disagreements about what that observation actually is, or any axioms used to define it, or how many people agree with it. The empirical fact is X devices counted Y coincidences in excess of inequality Z, period. Your opinion, predudice, etc., no matter how shared with others does not make anything you "consider" an empirical fact!

DrChinese

Jun9-10, 02:37 PM

Even a well proved theorem by definition can't be an empirical fact.

Try reading before writing; that is precisely what I said. After you re-read, I will gladly accept your apology. :smile:

Before you say stuff like "freaking ridiculous beyond belief" you might want to carefully consider whether the context deserves that. I have considerately tried to follow your reasoning for weeks. And believe me, your muddled thinking has not made that easy. (Muddled, by the way, is me being kind.) I realize that in YOUR mind, I have not answered your questions. And the fault lies with me to the extent I have not. Whenever there is a lack of communication, there are at least 2 frustrated people. But you are far off base with your recent comments, including any hint that I would evade an answer. I have been around here for a while, and I doubt there are many who have seen me shy away from anything. Probably quite the opposite, a few who wish I might step back more frequently.

Ah, perhaps we can both enjoy a glass of wine later and toast Bell in some fashion.

DevilsAvocado

Jun9-10, 05:13 PM

DrChinese & my_wan

I’ve been following your last debate, and to me it all seems like a misunderstanding, maybe on both sides.

I think that you both have very interesting points and great knowledge, and you both clearly makes this thread much more interesting. DrC advocates the standard position, and my_wan tries to find new solutions to explain what happens in Bell test experiments.

You are both confirming the mathematical validity of Bell’s theorem.

I don’t see anything wrong in either position, and 'tension' can create good (or bad) things...

In an attempt to hopefully make DrC understand what my_wan mean when talking about "Rotational Invariance in EPR-Bell Experiments", maybe this video could be a clue...?

Adenier - Fair Sampling and Rotational Invariance in EPR-Bell Experiments

http://video.google.com/ThumbnailServer2?app=smh&contentid=595a3795542a4921&offsetms=165000&itag=w160&sigh=CKXHBqOUeTu_m9UhHOYffTpgRCI&h=90&w=120&sigh=__KAuypyL7eh9Iqx33L85yRghKV94= (http://video.google.com/videoplay?docid=-1050719353457515819)

Guillaume Adenier, from Vaxjo University Sweden, also has a paper related to the video: Is the Fair Sampling Assumption supported by EPR Experiments? (http://arxiv.org/abs/quant-ph/0606122)

(Personally I don’t think that "Fair Sampling" is an issue, but that’s another question...)

DevilsAvocado

Jun9-10, 07:22 PM

... In my mind, rotational invariable is getting the same answer in any rotated reference frame. There can be no preferred frame.

DrC, I have some questions and if you have the time to answer, it would be great (as a 'reward' maybe I’ll deliver a BIG surprise in coming days :wink:). Many questions are more of 'verification' yes/no:

http://www.tongue-twister.net/mr/physics/photons.jpg

Q1) The photons coming out of the BBO crystal are entangled + entangled in polarization, so called superposition of (polarization) state (in the intersecting cone), right?

Q2) Does this entangled superposition mean that the two photons are QM coherent (pure state), and described by one single wavefunction?

Q3) Does the wavefunction collapse (or decohere) when the photon is measured in the polarizer?

Q4) When measuring the entangled photons with polarizers aligned, let’s say 0º on both, what coordinate system is used, to get the exact same angle, if the polarizers are separated by 10 km or more?

Q5) Is it practical to talk about exact polarizer angles for incoming photons, in respect of HUP?

Q6) In this thread we usually talk about up/down spin of entangled photons, but the correct term is right-handed and left-handed (clockwise/counter-clockwise), that correspond to the two possible circular polarization states of the photon (along its direction of motion), right?

Q7) The circular polarization in Q6 explains why the two entangled photons can be measured aligned on any angle 0 – 360º, right?

Q8) If the photon polarization is a result of spin, and thus direction of motion, would a change in the direction of motion also result in a change of the polarization?

Thanks in advance!

my_wan

Jun9-10, 08:02 PM

I don't accept the fair sampling argument either, but that doesn't mean an argument here that was characterized as a fair sampling argument here actually was. Some inefficiencies may lead to some slightly distorted data, but experimentally today it's well withing QM constraints. I see no reason to question perfect QM predicted correlations in the ideal case.

I did notice, in my own computer models, that the standard deviations increased greatly at offset maxima. I used a sample group of 10k photons. The standard deviation increase occurred due to low sample size as the expected hits/misses approached 0 or 100%. I was modeling the ideal QM case with exactly known particle numbers and detections, with perfect correlations and ideal detectors. This is likely to vary at least some in less than ideal conditions, but I don't see that refuting, or even seriously questioning, the QM predictions. I'll stick with modeling the ideal QM predictions.

Some interesting points was made in the video wrt rotational invariance (@12:30). I'm not sure how to interpret the anomalies. It looks too consistent in the pdf graph, even across experiments, to simply be variations in standard deviation. Yet the correlation coefficient remain consistent with QM. Weird.

my_wan

Jun9-10, 09:13 PM

DrC,
Perhaps my language was too unforgiving. It wasn't your denials, your opinions, your rejections, etc., that put me over the edge. That I welcomed, and even hoped for. I even hoped I could be backed in a corner with no other escape than a handshake. Regardless of how it might be interpreted, I have not demonstrated the side of the debate I took is factual. But neither does your interpretation come with overwhelming certainty.

The thing that triggered me was a complete lacking of answers to questions. When I expending great effort for an argument, and got a single sentence denial, which didn't even specify what was being denied, it was aggravating. Surely my articulation shared heavy burden in fault, but lacking any clues as to what needed improved, how could I even think of improving it?

I took great care early on, and several times since, to insure not only you but other realist here that I was a thin ice with my position in the debate. yet bias was assumed in every inane statement I made. Naturally, taking a realist position in the debate, I was by definition going to bias toward realism. But only to the degree needed for a proper debate.

So my apologies, for such strong innuendo. Not even the innuendo about what my bias indicated fully justified that. However, at the core, when you look past the emotional implications I imposed, there remains what I feel is a valid issue to express. I was simply at a total loss without being given a clue, even when I asked, how to clean up my articulation of the issues. So I must take at least as much responsibility, for lacking the tact to get the point across any other way.

ThomasT

Jun10-10, 12:25 AM

Don't want to appear insensitive, but shouldn't someone point out that arguing about the validity of Bell's Theorem experiments seems pretty redundant now ... Your comments don't appear to be insensitive. This is an argument based on arguable positions, not a quarrel based on emotion. I've benefited (as I assume others have) from your comments. So please stay tuned in and keep commenting.

... since multi-particle entanglement experiments have trivially demonstrated that local realism fails (and in particular that the EPR argument for it fails).Multi-particle entanglement experiments have demonstrated that Bell inequalities are violated. There's absolutely no dispute regarding that. The discussion here is about what can be inferred from those violations. The contention of some is that Bell's LR ansatz doesn't actually model the experimental situation that it purports to model, so that inferences regarding reality from those violations are obviated. I, and others, think they've got a good argument.

Certainly not because the inequality is wrong, but because it's physical meaning may be taken with a far higher level of generality than what the empirical fact of it justifies.

Maybe, but don't you agree that the subtlety of the arguments are more in the philosophically delicate vein than scientifically interesting?I think what you're saying is true. But the foundations of physical science are philosophical issues, not scientific issues. So, if Bell's argument against LR models of entanglement is logically flawed, then this is important.

unusualname

Jun10-10, 07:19 AM

Y
Multi-particle entanglement experiments have demonstrated that Bell inequalities are violated. There's absolutely no dispute regarding that. The discussion here is about what can be inferred from those violations. The contention of some is that Bell's LR ansatz doesn't actually model the experimental situation that it purports to model, so that inferences regarding reality from those violations are obviated. I, and others, think they've got a good argument.

But multi-particle entanglement experiments rule out local realism without the use of inequalities, which is why I suggested that the debate on Bell experiments is redundant (scientifically speaking)

Multi-Photon Entanglement and Quantum Non-Locality (http://books.google.co.uk/books?id=wiC0SEdQ454C&lpg=PA225&ots=XtQCKzvyi2&dq=Greenberger%E2%80%93Horne%E2%80%93Zeilinger%20n onlocality&pg=PA225#v=onepage&q=Greenberger%E2%80%93Horne%E2%80%93Zeilinger%20no nlocality&f=false)

(direct download link here (http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf))

Not saying it's not a worthwhile debate, but now that there are simpler experimental refutations of local realism than Aspect et al I don't think you can appeal to flaws in Bell to lend any support to counter arguments against this.

(Unless of course we subsequently find logical/philosophical issues with interpreting GHZ relations etc :smile: )

zonde

Jun10-10, 08:50 AM

But multi-particle entanglement experiments rule out local realism without the use of inequalities, which is why I suggested that the debate on Bell experiments is redundant (scientifically speaking)
GHZ inequality experiments rule out only non-contextual local realism just like Bell experiments only more directly.

But GHZ experiments just the same use fair sampling assumption so they can't rule out contextual local realism.

But I would agree that debate about non-contextual local realism is redundant.

my_wan

Jun10-10, 02:34 PM

GHZ inequality experiments rule out only non-contextual local realism just like Bell experiments only more directly.

But GHZ experiments just the same use fair sampling assumption so they can't rule out contextual local realism.

But I would agree that debate about non-contextual local realism is redundant.

I certainly do accept that BI violations experimentally rule out all non-contextual local realistic models. However, perhaps my definition of "fair sampling" is overly restrictive. Perhaps others can judge that. I take "fair sampling" to mean only that a small sampling of detections are representative. Yet many of the EPR mechanisms posited made no claims dependent on sample size and/or efficiency with which detections occurred, yet were labeled a fair sampling argument.

For instance, when a complete sampling is assumed, you can still index the properties to events in physically inappropriate ways, such that physically absurd situations are implied. How, when no problems with the validity of the sampling is assumed, only in the way they are indexed, can it be called a "fair sampling" argument?

Let's get inequality violations without correlation in a single PBS:
Let's assume a perfect detection efficiency in a single channel, 100% of all particles sent in this channel get detected either go left or right using a PBS. Consider a set of detections at this PBS at angle 0. 50% go left and 50% right. Now if you ask which left would have went right, and visa versa, these photons would have went at an angle setting of 22.5, it's reasonable to say ~15% that would have went left go right, and visa versa. Yet this same assumption indicates that at an angle of 45, ~50% that would have gone left go right (relative to the 0 angle), and visa versa. Yet, relative to angle 22.5, the 45 angle can only have switched ~15% of the photon detection rates. 15% + 15% = 30%, not 50%.

If you look at the above situation closely, with a single PBS and channel lacking any correlated pairs, any possible counterfactual assumptions about what the photons would have done if the setting had been different leads to exactly the same inequality violation as Bell posited. Thus the coincidences only show a repeatability of a local correlation free phenomena.

Fair sampling cannot be responsible when the same inequality issues can be reproduced under any possible, empirically realistic, counterfactual assumptions about what photons would have done in a single channel, correlation free, response to a single PBS.

It can be argued that this proves a lack of realism without even referring to EPR correlations, but any role of an FTL mechanism becomes moot, except that it's perfectly repeatable with a perfectly correlated particle. Yet this repeatability apparently indicates there's a deterministic mechanism for the local inequality present in the single uncorrelated particle beam case.

Thus any realistic model must model this local inequality deterministically, but attempts to do so forces you to choose a reference coordinate system, in which you can arbitrarily relabel the coordinate labels such that one or the other detector, when arbitrarily rotated, allows you to relabel that coordinate point as 0, to get the EPR case to work mathematically. Though I don't consider such arbitrary coordinate relabeling as having a real physical significance, since coordinate systems aren't physical constructs, I'm attempting to replace the deterministic 0/1 bits in my model with vectors, in the hopes of fixing the coordinate transform requirement when arbitrary detector settings are chosen.

Here's a simple outline of vector properties under rotation, perfectly matching what I presented, I'm attempting to take advantage of.
http://www.vias.org/physics/bk1_09_05.html

my_wan

Jun10-10, 03:09 PM

A second issue I had involves the meaning of what a contextual variable is. It's been posited that contextual variables entails a lack of realism. I have a hard time seeing how this can be justified. Though attempts at inquiring came to naught. It seems to me to be conflating the notion of a non-contextual variable lacking an existential container with contextual variables. A contextual variable is not simply a variable lacking an existential container, it's a variable that is contingent upon the overall structure of other undefined variables.

A simple example would be the property rabbit, rock, carrot, etc. Our entire physical experience is built on contextual variables defined by the periodic table of elements, plus radiation for our observation of it. If we take a pool ball collision to be a real event, and the pockets on the pool table to be detectors, then the variables our pockets detect is highly dependent on how you rotate the pool table under the pool ball collision. Thus pool table pockets only detect contextual variables. Is the polarization settings of a polarizer/detector like the pool table rotation? Almost certainly, whether the variables are realistic or not.

So I reject the notion that contextual variables entails a lack of realism.

DrChinese

Jun10-10, 03:15 PM

But GHZ experiments just the same use fair sampling assumption so they can't rule out contextual local realism.

But I would agree that debate about non-contextual local realism is redundant.

GHZ tests are not considered to rely on the Fair Sampling assumption. Now there is a kicker on this that may confuse folks. It is true that only a sample is used, so you might think the Fair Sampling issue is present. But it is not. The sample looks like this:

-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1...

Where local realism predicts

1
1
1
1
1
1
1
1
1
1
1...

A little consideration will tell you that local realism is falsified in this case. Every case, individually, is a falsification.

DrChinese

Jun10-10, 03:32 PM

my_wan

Jun10-10, 04:13 PM

I would agree that Fair Sampling is not a factor here. :smile:

And I actually agree that your example can be instructive about counterfactual reasoning. In fact, Eberly performed a neat analysis of this a few years back extending your idea. It did lead to the violation of a Bell type equality precisely because QM does not acknowledge the counterfactual case. But that would not lend support to your basic premise, because QM rules work when classical rules do not.

http://www.optics.rochester.edu/~stroud/cqi/rochester/UR19.pdf

I just recently completed a detail analysis of his derivation for a paper I wrote. I can reproduce this in a shortened manner if it is of interest. He concludes that it is meaningless to contemplate the results of experiments in which "data is not taken" (i.e. it is erased). This includes counterfactual cases.

I agree with you that there is a mystery in the 22.5 + 22.5 degree case you describe above (even though I may have given you a different impression in earlier posts). However, I am not clear how (or if) you can use that to demonstrate that local realism cannot hold.

I'd like to make a distinction here that may be leading to a little confusion, involving the two separate notions in "local realism" What this thought experiment was meant to exclude was not local realism or lack of realism, but the legitimacy of a non-local signaling mechanism to define the inequality violation. To validate the no-signaling assumption. I can't see how such a signaling mechanism is legitimate, when the same inequality violation exist without any reference events in existence to communicate with.

This argument was meant only to remove the non-local issue while leaving the realism issue open. Would any object to this removing the non-local issue, without actually resolving the realism issue? Thus, if acceptable, for any realist to maintain realism, a mechanism needs defined for how HUP pulls off this magic both locally and deterministically. Which requires other arguments this thought experiment doesn't address.

To extend beyond the limited argument above involves rotational invariance, due to the arbitrary detector setting requirement imposed by Bell proponents, this effect must be appreciated if such a mechanism is at all possible:
http://www.vias.org/physics/bk1_09_05.html

my_wan

Jun10-10, 04:26 PM

It should be noted that, in my modeling, I merely presume Malus' Law a priori. How Malus' Law pulls off this magic, even in an uncorrelated beam and single PBS, technically requires it's own explanation to claim anything more than a 'real' variable working toy model. Thus any success still does not say what is 'really' going on in such an experiment, it merely provides a toy model mimic that shows it's possible only in principle.

That's why I started thinking in vectors, because I wanted the toy model to resemble QM as close as possible while still using real variables.

Edit: The Born rule is a beast :redface:

DrChinese

Jun10-10, 04:35 PM

So my apologies, for such strong innuendo. Not even the innuendo about what my bias indicated fully justified that.

Why apology accepted! :smile:

I promise I will do a better job of listening for your questions. I am not trying to avoid anything, and certainly will not shy away because the going gets tough. I may be wrong, and if I am then that is my opportunity to learn something new. Which is why I am here.

DrChinese

Jun10-10, 04:43 PM

DrC, I have some questions and if you have the time to answer, it would be great (as a 'reward' maybe I’ll deliver a BIG surprise in coming days :wink:). Many questions are more of 'verification' yes/no:

http://www.tongue-twister.net/mr/physics/photons.jpg

Q1) The photons coming out of the BBO crystal are entangled + entangled in polarization, so called superposition of (polarization) state (in the intersecting cone), right?

Q2) Does this entangled superposition mean that the two photons are QM coherent (pure state), and described by one single wavefunction?

Q3) Does the wavefunction collapse (or decohere) when the photon is measured in the polarizer?

Q4) When measuring the entangled photons with polarizers aligned, let’s say 0º on both, what coordinate system is used, to get the exact same angle, if the polarizers are separated by 10 km or more?

Q5) Is it practical to talk about exact polarizer angles for incoming photons, in respect of HUP?

Q6) In this thread we usually talk about up/down spin of entangled photons, but the correct term is right-handed and left-handed (clockwise/counter-clockwise), that correspond to the two possible circular polarization states of the photon (along its direction of motion), right?

Q7) The circular polarization in Q6 explains why the two entangled photons can be measured aligned on any angle 0 – 360º, right?

Q8) If the photon polarization is a result of spin, and thus direction of motion, would a change in the direction of motion also result in a change of the polarization?

Thanks in advance!

Don't know if I can answer all of these, but let me take a stab at a few off the top of my pointy head:

1) Yes, the intersection is where you find the entangled ones.

3) This is not clear. You can subsequently "erase" the measurement so I would say no.

4) Actually, I would say that a somewhat relative system is used. Consider that the environment does slightly affect the polarization. To be honest, I don't know all of the adjustments they make in a lab so maybe someone else can add here. The usual texts are not completely clear and leave out a lot of details.

6) There is circular AND linear polarization. One can be changed to the other by use of wave plates.

8) No, you can change directions without changing the polarization. This is frequently done with fiber.

DevilsAvocado

Jun10-10, 06:50 PM

... let me take a stab at a few ...

Thanks for the answers DrC!

I know these questions are kinda weird and not easy to answer. However Q2 + Q3 is maybe the most crucial if I am about to deliver "something interesting"...

If I put it this way: If we compare with the Double-slit experiment and the superposition of one photon (or electron), and that this superposition "is lost" if we try to measure which slit it passes, and thus the Double-slit interference pattern is also lost.

Would you say that the photon superposition of polarization in EPR-Bell "is lost" in the same way, when we measure a 'fixed' photon polarization in the polarizer?

(not counting delayed quantum erasers etc)

EDIT: In Q4, could we assume that the experimentalist does a "later calibration/fine-tune" on angles, and when they have 100% correlation in data, they can be sure that this was a perfect parallel alignment...?

EDIT2: "6) There is circular AND linear polarization" - What is the (normal) case in EPR-Bell entangled photons?

P.S. I have found some real interesting "new" material from John Bell himself. I can’t see it on your site, so it’s probably news even to you. This is going to be a jaw-dropper to many of us in this thread...

DevilsAvocado

Jun10-10, 07:07 PM

... Some interesting points was made in the video wrt rotational invariance (@12:30). I'm not sure how to interpret the anomalies. It looks too consistent in the pdf graph, even across experiments, to simply be variations in standard deviation. Yet the correlation coefficient remain consistent with QM. Weird.

Yes, I don’t know if this is of any value, but would you say that this is somehow 'related' to 'your' rotational invariance?

my_wan

Jun10-10, 07:41 PM

I found this, which I completely overlooked till I seen it, even though it should have been obvious, which provides more experimental justification for assuming light has a distinct polarization even when its particle properties are being measured.
http://farside.ph.utexas.edu/teaching/qm/lectures/node5.htmlIt is known experimentally that when plane polarized light is used to eject photo-electrons there is a preferred direction of emission of the electrons. Clearly, the polarization properties of light, which are more usually associated with its wave-like behaviour, also extend to its particle-like behaviour. In particular, a polarization can be ascribed to each individual photon in a beam of light.

It goes on with a really easy read of some of the arguments I made, but placed within the framework of superposition of states. I was thinking I needed something extra beyond state superpositions to model EPR, but maybe not. Maybe all I need is to define a degree of superposition, defined by a pair of vectors, which transforms with different polarizer settings. Then simply predefine a detection limit defined by the product of those vectors at that detector setting. Perhaps I can even dispense with predefined detection limits and simply let the vector product range from -1 to 1, and select by which side of 0 the vector product produces. As noted, vector products are not rotational invariant for the reason pointed out here:
http://www.vias.org/physics/bk1_09_05.html
Even though the underlying real state is.

This would actually build the Born rule into the model. This requires defining the wavefunction as physically real, while all observables are not themselves representative of a real state, but a product projection of a real state.

Ah, well.. I'm just running my mouth again, going beyond what I can demonstrate atm. The electron ejection data remains interesting and relevant to potential realism models.

my_wan

Jun10-10, 07:54 PM

Yes, I don’t know if this is of any value, but would you say that this is somehow 'related' to 'your' rotational invariance?

It's hard to say. It's not a direct analog, and I'm not sure how to interpret the anomalies. I can't say it's not related either. The most significant effect wrt rotational invariance I can point at the illustrate what I described is here:
http://www.vias.org/physics/bk1_09_05.html
The operation's result depends on what coordinate system we use, and since the two versions of R have different lengths (one being zero and the other nonzero), they don't just represent the same answer expressed in two different coordinate systems. Such an operation will never be useful in physics, because experiments show physics works the same regardless of which way we orient the laboratory building! The useful vector operations, such as addition and scalar multiplication, are rotationally invariant, i.e., come out the same regardless of the orientation of the coordinate system.
And this was done using only two very basic unit vectors. It says it "will never be useful in physics", but the Born rule imposes this very condition to define observables from the QM framework!

DevilsAvocado

Jun10-10, 08:07 PM

It's hard to say. It's not a direct analog, and I'm not sure how to interpret the anomalies. ...

Okay, I think that in the video the focus was on "rotational invariance in the source", and you are focusing on the angles of polarizers, right?

The Born rule (http://en.wikipedia.org/wiki/Born_rule) seems tuff... :wink:
There have been many attempts to derive the Born rule from the other assumptions of quantum mechanics, with inconclusive results.

DevilsAvocado

Jun10-10, 08:19 PM

... This requires defining the wavefunction as physically real ...

Where can I buy a member card?? :approve:

Seriously, what’s your opinion on a possible "wavefunction collapse" when the entangled photon (superposition polarized) is measured by the polarizer?

my_wan

Jun10-10, 08:26 PM

Okay, I think that in the video the focus was on "rotational invariance in the source", and you are focusing on the angles of polarizers, right?More specifically the observable values, but since those would depend on a vector product with its (complex) conjugate, which in turn is dependent of polarizer angles, it does come down to the angles of polarizers.

The Born rule (http://en.wikipedia.org/wiki/Born_rule) seems tuff... :wink:
Yes, more than a little weird from the perspective of classical physics. Yet taking the wavefunction serious as a real physical state provides an EPR mechanism. Unfortunately the published thermodynamics models don't really deal with it explicitly. They tend to simply impose such weirdness on top a priori. So even if we simply assume the wavefunction is real, and claim some modeling success, it still doesn't fully answer the realism question.

Edit: Oops forgot to answer the question. I don't really take wavefunction collapses seriously, for reasons well outside this debate. I think it more likely the apparent collapse is the removal of the possible states evolved from a prior state, to leave on the actual state. It still requires the rules what a wavefunction can really do be analogous to what it could have done, but didn't, in some very fundamental ways.

DevilsAvocado

Jun10-10, 08:38 PM

Yet taking the wavefunction serious as a real physical state provides an EPR mechanism.

But... QM stipulate "no signals"... ?:bugeye:?

my_wan

Jun10-10, 09:03 PM

But... QM stipulate "no signals"... ?:bugeye:?
As am I. The mechanism would still be local phenomena, using the local field interactions, while the other detector reacts the same to its local field the same way. I'm just trying to inject QM effects in that local interaction in as realistic a way possible. But the reality atm is that I'm going beyond what I can demonstrate right now, and should back up to the more limited factual elements of the argument.

ThomasT

Jun11-10, 10:07 AM

DrC, in a recent reply to my-wan you stated:
Otherwise, you will suffer the same fate as ThomasT: I will pick apart your statements because it is wrong for you to use PhysicsForums as a soapbox for personal pet theories.The fate that I've suffered is that my understanding of the issues involved in determining the meaning of Bell's theorem has increased due to these recent discussions. My thanks to all who contributed to these discussions for that.

As for a pet theory, I don't have one. Any particular modelling attempts have been presented simply to clarify what is and isn't possible given certain assumptions. So, it would be misunderstanding, and mischaracterizing, the aim and the content of my participation in these discussions to say that I was using PF as a "soapbox for personal pet theories", or, as I explain below, to say that my approach to understanding Bell's theorem is nonstandard wrt the traditions of modern science.

I presented one preprint of an LR model, which reproduced the qm predictions, for you to look at and comment on. You didn't do that. Instead you asked for the model to produce a "dataset" which doesn't agree with qm predictions. This confusion is addressed in the following paragraph.

What some people in this, and other recent related, threads are discussing, and what I'm interested in exploring, is the possiblity that the restriction that any (and all) LR models of entanglement be constructed in terms of "local hidden variables" (which has certain implications wrt the form that any such model can take) doesn't apply to a rather wide range of local realistic models which aren't, strictly speaking, local hidden variable models, but are, nonetheless, compatible with the notions of c-limited locality and seperable predetermination. This has to do with the consideration that the parameters involved in the joint measurement context are not themselves "elements of reality" but rather relationships between those elements.

So, I can absolutely agree with this expression of Bell's theorem:
"No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics."
And, still entertain the possibility that LR models of entanglement are possible.

So, when I say that Bell's logic was flawed, what I mean is that, if his program was to give a general form for any and all LR models, then, imo, he didn't do that. On the other hand, if his program was to give a general form for any and all LHV models, then, imo, he did that. And since I think his program was the former, and that his analysis didn't take into account the contextual parameters (not LHV's) which determine joint detection (but not individual detection), then the application of his ansatz to entanglement preparations was logically flawed. The same reasoning applies to GHZ, Hardy, and any other theorems which rule out LHV, but not all LR, models of entanglement.

We know for sure that Bell's formulation is incompatible with qm and experimental results. The fact that it's incompatible with experimental results demonstrates that it incorrectly models the experimental situations to which it's being applied. From this, some people (1) choose to trash a pillar (or two?) of modern science, while other's (2) choose to look more closely at Bell's construction to explore the possibility that maybe it has no corollaries pertaining to what does or doesn't exist in nature. I would characterize (1) as somewhat nonstandard wrt accepted methods of scientific inquiry, because (2) is ongoing.

Referring to the preceding quoted expression of Bell's theorem, you ask:
You think that this shows a physical meaning which is more general than justified empirically?No, I agree with you that it doesn't.. And as long as Bell's theorem is expressed that way then it's clear enough that it doesn't imply anything about nature.

And you continue with:
I don't see this as something which is empirical. Nor do I see it as more general than warranted. Nor am I aware of any physical theory which threatens this conclusion.Again, I agree with you on this. We seem to agree that Bell's theorem doesn't provide a basis for assuming nonlocality or ftl. But since you seem to want to hold onto the idea that nonlocality is, in some sense, possible, then I'll grant you that, in the sense that none of us has any unassailable ideas regarding the reality underlying our sensory experience so that pretty much 'anything' is possible wrt deep reality, then, in that sense, nonlocality is possible. Just that, without Bell's theorem as a basis, it isn't a reasonable assumption (ie., it doesn't follow from what's known).

DrChinese

Jun11-10, 11:05 AM

DrC, in a recent reply to my-wan you stated:...

Hey, I hope you know I am glad you are here. I hope nothing I say discourages you in any way. In fact, I encourage you to challenge from every angle. :smile: I enjoy a lot of your ideas and they keep me on my toes.

I think you know that there are a lot of readers who are not active posters in many of our discussions. Just look at the view count on these threads. While I know what is what throughout the thread, these readers may not. That is why I frequently add comments to the effect of "not generally accepted", "show peer reviewed reference" , etc. my_wan and billschnieder get that too. So my objective is to keep casual readers informed so that they can learn both the "standard" (generally accepted) and the "non-standard" (minority) views. I would encourage any reader to listen and learn to a broad spectrum of ideas, but obviously the mainstream should be where we start. And that is what PhysicsForums follows as policy as well.

On the other, when posters suitably label items then that is not an issue and I don't feel compelled to add my (sometimes snippy) comments. Also, many times a personal opinion can be converted to a question so as not to express an opinion that can be mistrued. For example: "Is it possible that Bell might not have considered the possibility of X?". That statement - er question - does not attempt to contradict Bell per se. And then the discussion can continue.

And less feelings get hurt. And people won't think I am resorting to authority as a substitute for a more convincing argument. As I often say, it only takes one. Of course, me being me, that line is stolen (in mangled form) from a man who is quite well known. In fact, maybe it is time to add something new to my tag line...

DevilsAvocado

Jun11-10, 12:35 PM

... As I often say, it only takes one.

Good post DrC, and to the "readers" we maybe should explain the "stolen line", which is both brilliant and humorous.

Leipzig, Germany in early 1931 (propaganda), a booklet that denied the theories of Albert Einstein was titled:
"One Hundred Scientists against Einstein"

Einstein -- "Why 100? If I were wrong, then one would have been enough!"

:biggrin:

DrChinese

Jun11-10, 01:29 PM

Good post DrC, and to the "readers" we maybe should explain the "stolen line", which is both brilliant and humorous.

Leipzig, Germany in early 1931 (propaganda), a booklet that denied the theories of Albert Einstein was titled:
"One Hundred Scientists against Einstein"

Einstein -- "Why 100? If I were wrong, then one would have been enough!"

:biggrin:

Suitably modified. :smile:

Einstein had so many great quotes, in addition to his marvelous contributions to science.

my_wan

Jun11-10, 04:09 PM

As for a pet theory, I don't have one. Any particular modelling attempts have been presented simply to clarify what is and isn't possible given certain assumptions. So, it would be misunderstanding, and mischaracterizing, the aim and the content of my participation in these discussions to say that I was using PF as a "soapbox for personal pet theories", or, as I explain below, to say that my approach to understanding Bell's theorem is nonstandard wrt the traditions of modern science.
My own realist slant is based on the fact that the default and presumably the most defensible position is against it, and I made no bones about the precariousness of my arguments. BI violations are often billed as proof of either non-local or non-realism. To maintain that requires standing up to even "in principle" mechanisms. To that a class of lhv's exist that in principle that does that, but mostly involve contentious issues with fundamental principles and definitions of realism. So I object to an unequivocated proof claim, while I'm perfectly content with the default position being a general acceptance of BI. It is this acceptance on which the search for falsification is predicated, just as it should be.

Yes, outside readers should understand that the default position is and should be an acceptance of BI. Science also gains it's strength through standing up to falsification, so countering the default position is part of the process. Implying that attempts at falsification is not science, but prejudice, doesn't serve science well. So long as those countering are not demanding their position as absolute truth.

DrChinese

Jun11-10, 04:22 PM

Yes, outside readers should understand that the default position is and should be an acceptance of BI. Science also gains it's strength through standing up to falsification, so countering the default position is part of the process.

Thanks for clarifying that. It really helps if you mention that from time to time, so the other readers don't accidentally get the wrong impression. Someone who starts reading in the middle of the thread (which is most) will benefit greatly from knowing the sides as they listen and learn.

Keep in mind that persuading you to change your position is not really my objective. If that happens, fine, but there are lots of people who have the same questions or concerns as you. You deserve the best anyone here can offer. If anything I say helps you to frame your position better, then I am happy.

my_wan

Jun11-10, 06:27 PM

What I want doesn't involve a position to be changed, as I accepted my position for debate purposes was precarious from the beginning. I want a clearer view of how to model the situation with or without realism, and I feel that pitting BI violations against potential realistic models helps, valid or not. As is well known, BI is not directly related to QM but far more general. It seems fairly obvious that any explanation must involve mechanisms consistent with QM, realistic or not. Articulating precisely if and how realistic models fall short leads to clues about precisely what QM principle are involved.

This is why the debate is leading me toward the Born rule, and the general lack of rotational invariance in vectorial products. Vector products of the type the Born rule imposes is generally avoided in physics for this reason. The squaring to get observable magnitudes would also provide for the nonlinearity in the detection counts at various offsets. So a realism argument might ultimately come down to a realistic mechanism for the Born rule. Even lacking this, if it can be demonstrated that the Born rule alone can provide the mechanism, it would be quiet significant.

I will continue to object to BI violations being presented as an overly general "proof", however significant and physically valid experimentally. I object almost as strongly as I would to absolute claims that it must have a realistic explanation.

DevilsAvocado

Jun11-10, 08:27 PM

Suitably modified. :smile:

P l e a s e tell me you changed your signature just now!? :redface: ...or I have to get new glasses... :rofl:

EDIT: Just realized what happened here. I was reading your post without being logged in, and then your signature doesn’t show (why? :grumpy:). For those readers who aren’t registered users, my comment could be 'useful' after all... :rolleyes: (and I can keep my old glasses :blushing:)

DevilsAvocado

Jun11-10, 08:39 PM

DrChinese & my_wan

How about a request to PF Admin for a new option in PF that would allow us to set a "Footer Disclaimer" (maybe thread specific), that is shown whether the "readers" are logged on or not?

This would probably avoid a lot of unnecessary internal "hubbub"... and be a guarantee for the reader not to get the wrong "impression"...

My "Disclaimer" would look something like this:
I’m a 100% curious layman looking for more knowledge. Naturally, I accept all standards in the scientific community, but I think it’s fun to find (what I imagine) new perspectives and questions (that probably already have been answered). Everything I say can be totally wrong (read at own risk), though I regard myself as perfectly sane - but even this fact could be questioned by some. :wink:

(Realize... this would only work as a "popup function"...)

What do you think?

DevilsAvocado

Jun12-10, 09:17 AM

EPR-Bell Experiment for Dummies
A Reference for the Rest of Us

Found a very informative video which explains all parts in a modern EPR-Bell setup.

<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/c8J0SNAOXBg&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/c8J0SNAOXBg&hl=en_US&fs=1&rel=0&color1=0x006699&color2=0x54abd6" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

http://www.youtube.com/watch?v=c8J0SNAOXBg

DrChinese

Jun12-10, 10:49 AM

I will continue to object to BI violations being presented as an overly general "proof", however significant and physically valid experimentally. I object almost as strongly as I would to absolute claims that it must have a realistic explanation.

my_wan, I honestly think you are stretching the meaning of the words a bit (and I am not trying to criticize as I see words to the same effect from others too). Absolute might be a little strong about ANYTHING we think we know. At some point, you have to say: this is proven, this is supported experimentally, or this is a conjecture. Clearly, all sides are NOT equal.

I would say that Bell is proven, local realism is not experimentally supported, and there are conjectures regarding various interpretations. Are any of these absolutes? I think each of us has a slightly different opinion on that and I don't think that is too important. But it would be quite unfair to characterize local realism as being on the same footing as QM in terms of Bell/Bell tests.

my_wan

Jun12-10, 03:09 PM

Absolute may be too strong, but when it's said Bell's theorem proves non-locality or non-realism, it is overstated. What has been proven is that nature violates BI. I even go with the extension that it has been irrevocably proven is that nature does not assign properties to things in a manner consistent with that one definition of realism.

By the time I was 10 years old, based on purely mechanistic reasoning, the notion of "physical property" as used in classical physics wrt -fundamental- parts, sounded like an oxymoron to me. When I apply that same reasoning today wrt BI, BI violations only justify my original, age 10, issues with the notion of fundamental properties. Yet to insist that experimental evidence that "fundamental property" wrt to things is an oxymoron proves the lack of realism in things requires assuming the definition wasn't an oxymoron from the start. Before I ever even started kindergarten, I was sneaking rocks in the car to drop out the window, to compare how the path looked from inside and outside the car. I tried using telephone poles and mail boxes as reference points.

At some point, you have to say: this is proven, this is supported experimentally, or this is a conjecture. Clearly, all sides are NOT equal.
BI violations are proven beyond ANY reasonable doubt. But no, you can't assume that because the fact of BI violations remain factual proves an interpretation of what it means physically.

I would say that Bell is proven, local realism is not experimentally supported, and there are conjectures regarding various interpretations.Yes, BI violations are factual, and will never go away simply as a result of better experiments. As to what it means wrt realism requires the assumptions that the definition of realism used wasn't predicated on an oxymoron from the start.

If you take a rabbit to have the property 'rabbit, which eats clover with the property 'clover', what happened to the 'clover' property when the rabbit eats it? Does that mean the 'rabbit' property is not 'real'? If no, does that mean the 'rabbit' is not real?

So yes you can say with certainty that BI is valid. You cannot make claims of what it means wrt to realism in general, irrespective of chosen definitions which might even be an oxymoron from the perspective of realism itself, and then claim that the fact that it has remained an oxymoron as defined for some time strengthens the claim realism is falsified. I find it ironic that experimental evidence that my perception at 10, predicated on realism, that 'physical properties' as defined was an oxymoron, is now used to claim realism is falsified.

my_wan

Jun12-10, 06:38 PM

How did the original EPR paper actually define realism?
http://www.drchinese.com/David/EPR.pdf

This was the primary completeness condition (unequivocated) which is predicated on realism:Whatever the meaning assigned to the term complete, the following requirement for a complete theory seems to be a necessary one: every element of physical reality must have a counterpart in physical theory. We shall call this the condition of completeness.

Now this is far more general than the definition actually used, where it was stated:A comprehensive definition is, however, unnecessary for our purposes. We shall be satisfied with the following criterion, which we regard as reasonable.

Notice the equivocations? The following definition was even, in the original paper, disavowed as a complete specification of realism. The following definition was purely utilitarian for purposes of the argument:If, without in any way disturbing the system, we can predict with certainty (i.e., with probability equal to one) the value of a physical quantity, then there exist an element of physical reality corresponding to this physical quantity.

Note that "there exist an element of physical reality" is not even a condition that the "physical quantity" associated with it must be singular or innate to singular "elements". This was in a sense the basis on which Einstein rejected Neumann's proof. Deterministic (classical) was taken to mean dispersion free, in which the measurables were taken as distinct preexisting properties of individual "beables". Bell showed that the properties of any such "beables" must also depend on the context of the measurement, much like classical momentum is context dependent. How many different times, not counting the abstract, was this definition equivocated? Let's see:
1) A comprehensive definition is, however, unnecessary for our purposes.
2) It seems to us that this criterion, while far from exhausting all possible ways of recognizing a physical reality, at least provides us with one such way, whenever the conditions set down in it occur.
3) Regarded not as necessary, but merely as sufficient, condition of reality, this criterion is in agreement with classical as well as quantum-mechanical ides of reality.

The point here is that not even the original EPR paper supported the notion that an invalidation of the singular utilitarian definition used was itself an invalidation of reality, or that singular properties represented singular elements. It allowed many more methods and contexts with which to define reality, and merely chose this one to show, given the assumptions, that cases existed where conservation law allowed values lacking a real values in QM could be predicted when QM defined them as fundamentally undefined. To predicate a proof on this singular utilitarian definition as proof that all definitions of objective reality are falsified goes well beyond the claims of the EPR paper. It is also this artificial restriction, to this utilitarian definition provided, that is the weakness in the proof itself.

Look at the rabbit analogy again. Given a rabbit and its diet, the physical quantity of a substance with the property [rabbit poo] is predictable. That by definition, under the utilitarian definition used, defines [rabbit poo] as an element of reality, but does that means the rabbit poo property is also an element of reality. If so, where was the "poo" property before the rabbit eat the clover? If not does mean the "poo" property does not define an element of reality? The only reasonable assumptions are:
1) The [rabbit poo] property in fact represents an element of reality.
2) The [rabbit poo] property is not itself a physical element of reality, but a contextual element of reality representing a real physical state.
3) The rabbit poo itself is a physical element of reality.

Taken this way, BI violations might only indicate that ALL measurable properties have the same contextual dependence as every property we are familiar with in the everyday world. It may only be our notion that fundamental properties of "beables" exist that is at fault. Yet a "beable" lacking measurable properties of its own may still gain properties through persistent, or quasi-persistent, interactions with other beables. A Schneider quote I like a lot from Hume’s Determinism Refuted (http://www.drchinese.com/David/Hume's_Determinism_Refuted.htm), illustrating the unobservability of independent variables is fitting here. This entails that what we perceive as the physical world is built from verbs, rather than nouns, but doesn't prove that nouns don't exist to define the verbs. So the claim of a proof of the nonexistence of beables goes well beyond any reasonable level of generality that can be claimed.

The issue of completeness is twofold. If -every- possible empirical observation and prediction is contained within a mathematical formalism, is it complete? I would say so, even if reality contains physical constructs at some level, not defined in the formalism, that provides for the outcomes predicted by the formalism. Einstein insisted on these physical constructs being specified in order to qualify as complete. Funny he didn't insist on the same with his own theories, presumably on the grounds that they didn't conflict with certain realist notions. Thus I don't consider, as Einstein did, that every element of physical reality must have a counterpart in physical theory to be considered complete. If QM is considered lacking in completeness, gravity is the issue. Yet a model, complete in the Einstein sense, would be a useful construct, and maybe even play a pivotal role in unification.

DevilsAvocado

Jun13-10, 06:24 AM

... but does that means the rabbit poo property is also an element of reality.

If the rabbit poo hits the fan, then I think most would regard 3) as the most plausible alternative. :rofl:

Seriously, I’m not quite following all this talk about what is real or not... is a measured photon more real than an unmeasured photon?? Is the measuring apparatus 100% real??

According to Quantum Chromodynamics (QCD) both rabbit poo and measuring apparatus consist of 90% virtual particles, popping in and out all the time:

http://www.physics.adelaide.edu.au/~dleinweb/VisualQCD/QCDvacuum/su3b600s24t36cool30actionHalf.gif

So, what is really real real or counterfactual real or context real, etc !?:confused:!?

DrChinese

Jun13-10, 01:34 PM

How did the original EPR paper actually define realism?
http://www.drchinese.com/David/EPR.pdf

This was the primary completeness condition (unequivocated) which is predicated on realism:

Now this is far more general than the definition actually used, where it was stated:

Notice the equivocations? The following definition was even, in the original paper, disavowed as a complete specification of realism. The following definition was purely utilitarian for purposes of the argument:

Note that "there exist an element of physical reality" is not even a condition that the "physical quantity" associated with it must be singular or innate to singular "elements". This was in a sense the basis on which Einstein rejected Neumann's proof. Deterministic (classical) was taken to mean dispersion free, in which the measurables were taken as distinct preexisting properties of individual "beables". Bell showed that the properties of any such "beables" must also depend on the context of the measurement, much like classical momentum is context dependent. How many different times, not counting the abstract, was this definition equivocated? Let's see:
1) A comprehensive definition is, however, unnecessary for our purposes.
2) It seems to us that this criterion, while far from exhausting all possible ways of recognizing a physical reality, at least provides us with one such way, whenever the conditions set down in it occur.
3) Regarded not as necessary, but merely as sufficient, condition of reality, this criterion is in agreement with classical as well as quantum-mechanical ides of reality.

The point here is that not even the original EPR paper supported the notion that an invalidation of the singular utilitarian definition used was itself an invalidation of reality, or that singular properties represented singular elements. It allowed many more methods and contexts with which to define reality, and merely chose this one to show, given the assumptions, that cases existed where conservation law allowed values lacking a real values in QM could be predicted when QM defined them as fundamentally undefined. To predicate a proof on this singular utilitarian definition as proof that all definitions of objective reality are falsified goes well beyond the claims of the EPR paper. It is also this artificial restriction, to this utilitarian definition provided, that is the weakness in the proof itself.

I do agree with much of what you are saying here. There are definitely utilitarian elements to Bell's approach. But I may interpret this in a slightly different way than you do. In my mind, Bell says to the effect: "Define realism however you like, and I would still expect you to arrive at the same place." I think he took it for granted that the reader might object to any particular definition as somewhat too lenient or alternately too restrictive. But that one's substitution of a different definition would do little to alter the outcome.

Again, for those following the discussion, I would state as follows: EPR defined elements of reality as being able to predict the result of an experiment without first disturbing the particle. They believed that there were elements of reality for simultaneous measurement settings a and b. Bell hypothesized that there should, by the EPR definition, be also a simultaneous c. This does not exist as part of the QM formalism, and is generally disavowed as part of most treatments. So it is a requirement of the realistic school, i.e. the school of thought that says that hidden variables exist. But not an element of QM.

DrChinese

Jun13-10, 01:39 PM

Look at the rabbit analogy again. Given a rabbit and its diet, the physical quantity of a substance with the property [rabbit poo] is predictable. That by definition, under the utilitarian definition used, defines [rabbit poo] as an element of reality, but does that means the rabbit poo property is also an element of reality. If so, where was the "poo" property before the rabbit eat the clover? If not does mean the "poo" property does not define an element of reality? The only reasonable assumptions are:
1) The [rabbit poo] property in fact represents an element of reality.
2) The [rabbit poo] property is not itself a physical element of reality, but a contextual element of reality representing a real physical state.
3) The rabbit poo itself is a physical element of reality.

The EPR view was that there was an element of reality associated with the ability to predict an outcome with certainty. There was no claim the what was measured was itself "real", as it was understood that it might be a composite or derived quantity. Is temperature real?

But the EPR view was also that the element of reality is non-contextual. They said that any other view was "unreasonable".

DevilsAvocado

Jun13-10, 06:40 PM

(my_wan, sorry for the silly rabbit joke... parrots & rabbits + EPR seems to short circuit my brain...)

I’m going to stick my layman nose out, for any to flatten.

To my understanding, Einstein didn’t like the idea that nature was uncertain according to QM. That was the main problem – not if A & B was "real" or not.

Einstein formulated the EPR paradox to show that there was a possibility to get 'complete' information about a QM particle, like momentum and position, by measuring one of the properties on a twin particle, without disturbing the 'original'.

One cornerstone in QM is the Heisenberg uncertainty principle, which says it’s impossible to get 'complete' information about a QM particle (like momentum and position), not because the lack of proper equipment – but because uncertainty and randomness is a fundamental part of nature.

Einstein raised the bet and placed his own special theory of relativity at stake (probably certain it couldn’t fail) stating – either local hidden variables exist, or spooky action at a distance is a requirement – to explain what happens in the EPR paradox.

Einstein didn’t know that his own argument would boomerang back on him...

And here we are today with a theoretical proven and physical (99,98%) theory stating that the QM world is non-local, in Bell’s theorem.

This means, beyond any doubt, that GR <> QM and to solve this dilemma we need to get GR = QM.

So gentlemen, why all this 'fuss' about reality, counterfactuals, context, C, etc?

my_wan

Jun13-10, 09:27 PM

The EPR view was that there was an element of reality associated with the ability to predict an outcome with certainty. There was no claim the what was measured was itself "real", as it was understood that it might be a composite or derived quantity. Is temperature real? Yes, exactly. But the issue is what BI has to assume about the contextually of the measured values wrt elements of reality. EPR needed only the fact it was predictable, and no other assumption. I have to object to your next claim.

But the EPR view was also that the element of reality is non-contextual. They said that any other view was "unreasonable".
No. EPR did not assume reality is non-contextual. The "unreasonable" quote only denied a singular form of contextuality, i.e., that the reality of measurement P was dependent on measurement Q. That is certainly far from the only form of contextuality that exist, and the interpretation the BI demonstrates this form denies any other form of contextuality, and presumes correlation equals causation. It would certainly be "unreasonable" to conclude that classical physics does not allow correlations without the defining the measurement itself as the causative agent of the correlation.

Consider what it entails if we assume a realist perspective of BI violations.
1) Correlations at common detector settings is a physical certainty.
2) Offsets from a common detector setting introduces noise, completely random from an experimental/empirical perspective.

Now, via BI violations, counterfactually we can show the randomness of the noise in 2) cannot show the same randomness wrt another detector setting. Well big shocker when arbitrary but common detector settings doesn't show any significant randomness. If this noise itself is -fundamentally- deterministic but unpredictable, then you can always choose an after the fact measurement you could have done that would have given a different value than the expectation value of this randomness. The same for any random series of predefined heads/tails can be chosen after the fact to show a non-random correlation with a set of coin tosses.

To illustrate, note how in the negative probability proof the non-correlations, (Y = SIN^2(45 degrees), are given the same ontological certainty status as the correlations at common angles. Certainly, from a purely statistical standpoint, the noise of 2) is a certainty in the limit. Yet if you assume a realist position, you can always choose an after the fact condition in which noise becomes a signal, or visa versa. I can win the lottery every time if I can choose after the fact.

Of course, a good rebuttal is, the problem in BI violations is that BI violations are always inconsistent with what an alternative measurement would have indicated. The problem here is that the randomness of the noise in 2) is given the same ontological status as the certainty of 1). When you define a counterfactual channel, you are by definition imposing a non-random after the fact condition on C. The noise of the counterfactual channel is predefined to be non-random wrt any performable actual experiment, for either leg A or B, since it is after the fact correlated and anti-correlated respectively. This entails that the noise is -predefined- to be inversly related to the randomness of any actual measurement of A and B, thus the randomness of Y = SIN^2(45 degrees) is defined out of it after the fact. Like calling heads after the toss. The stochastic noise can't be considered to have the same ontological certainty status as the certainty of the physical correlation itself, which exist even when the noise introduced by offsets shows noncorrelated measurements.

I still think the Born rule is probably directly involved here, which by itself would give realist a headache. :tongue: I haven't had time to test my rotationally variant vectorial ideas yet either. I'll get to it sooner or later.

my_wan

Jun13-10, 09:44 PM

This means, beyond any doubt, that GR <> QM and to solve this dilemma we need to get GR = QM.

So gentlemen, why all this 'fuss' about reality, counterfactuals, context, C, etc?

Because precisely what we can presume about reality, counterfactuals, context, etc., plays a large role in what we can consider to get GR <> QM to GR = QM. Short of doing that, I don't see the value of purely interpretive models.

And your rabbit poo joke was fine :rofl:

ThomasT

Jun14-10, 02:19 AM

I still think the Born rule is probably directly involved here, which by itself would give realist a headache.Why do you think that? Doesn't the Born rule have an empirical basis?

ThomasT

Jun14-10, 02:46 AM

But the EPR view was also that the element of reality is non-contextual. They said that any other view was "unreasonable".The EPR view was that the element of reality at B determined by a measurement at A wasn't reasonably explained by spooky action at a distance -- but rather that it was reasonably explained by deductive logic, given the applicable conservation laws.

That is, given a situation in which two disturbances are emitted via a common source and subsequently measured, or a situation in which two disturbances interact and are subsequently measured, then the subsequent measurement of one will allow deductions regarding certain motional properties of the other.

Do you doubt that this is the view of virtually all physicists?

Do you see anything wrong with this view?

zonde

Jun14-10, 02:58 AM

zonde

Jun14-10, 03:33 AM

GHZ tests are not considered to rely on the Fair Sampling assumption.
In original GHZ paper "Bell's theorem without inequalities" (it is pay per view unfortunately) it is said:
"The second step is to show the test could be done even with low-efficiency detectors, provided that we make a plausible auxiliary assumption, which we call fair sampling. Finally, we show that the auxiliary assumption is dispensable if detector efficiencies exceed 90.8%."

Now there is a kicker on this that may confuse folks. It is true that only a sample is used, so you might think the Fair Sampling issue is present. But it is not. The sample looks like this:

-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1...

Where local realism predicts

1
1
1
1
1
1
1
1
1
1
1...

A little consideration will tell you that local realism is falsified in this case. Every case, individually, is a falsification.
GHZ experiments use four photons not one photon.
If we talk about three photon GHZ then it's results are acquired using four different modifications of setup. And GHZ inequalities are calculated from all four results together that each consists of three-fold coincidences in four detectors.
Nothing of this indicates that you can simplify experimental outcome the way you did.

my_wan

Jun14-10, 04:47 AM

Let's get inequality violations without correlation in a single PBS:
Let's assume a perfect detection efficiency in a single channel, 100% of all particles sent in this channel get detected either go left or right using a PBS. Consider a set of detections at this PBS at angle 0. 50% go left and 50% right. Now if you ask which left would have went right, and visa versa, these photons would have went at an angle setting of 22.5, it's reasonable to say ~15% that would have went left go right, and visa versa.

This is only true if the source produces only H and V photons.
Absolutely not. The statistics, as stated, are in fact predicated on completely randomized polarizations coming from the source. However, if the photons coming from the source were 50% H and V, strictly at those 2 polizations, it would have the same statistical effect, because the rate photons switch paths from H is the same rate they would switch from V in reverse.

But the fact remains, purely randomed polarization would have the same statistics. I went to great lengths to verify this assumption.

You can easily check it with such setup. Let's say single run of experiment lasts 10 seconds. Our photon source produces H polarized photons for first 5 seconds of experiment and V polarized photons for other 5 seconds.
Say for first 5 seconds all photons appear in PBS channel #1 and for other 5 seconds all photons appear in channel #2. When we rotate PBS by 22.5° we have:
85% photons in channel #1 and 15% photons in #2 for first half and
15% photons in channel #1 and 85% photons in #2 for second half.
So it is indeed reasonable to assume that 15% of photons changed their channel.
Yep, but this is quiet different from random polarizations, where any setting of the PBS sends 50% in each direction, but also incidentally matches, at all PBS settings, the statistics as two pure polarizations at 90 degree offsets.

Consider this: Add the first and second set of 5 second runs together and the 85% and 15% wash out, just like what you initially specified above. Now check and see that the same thing happens at all settings. Thus if it always washed out at all settings in the strict H and V cases, why would a completely randomized source, which only changes those same settings via the photons rather than polarizer settings lead to anything different in the overall statistics?

However if source produces +45° and -45° polarized photons we will have different picture.
For PBS at 0° we have:
50% photons in channel #1 and 50% photons in #2 for first half and
50% photons in channel #1 and 50% photons in #2 for second half.
For PBS at 22.5° we have:
85% photons in channel #1 and 15% photons in #2 for first half and
15% photons in channel #1 and 85% photons in #2 for second half.
So it is reasonable to assume that 35% of photons changed their channel.Yep, but only if the photon from the source are not randomized, which you falsely assumed my description didn't do, simply because the overall statistics happen to match for both pure H and V and randomized photon polarization cases.[/QUOTE]

Yet this same assumption indicates that at an angle of 45, ~50% that would have gone left go right (relative to the 0 angle), and visa versa. Yet, relative to angle 22.5, the 45 angle can only have switched ~15% of the photon detection rates. 15% + 15% = 30%, not 50%.Above explanation indicate that you don't get the problem you are stating here.
The only mistake I see in your reasoning is thinking that because there is a statistical match between the pure H and V case, and the randomized case, I must have only have been referring the pure H and V case. This is wrong. Check the same statistics for the randomized case and you'll see a statistical match for both cases, but the randomized case would invalidate your +45° and -45° case, because I was assuming the randomized case.

ThomasT

Jun14-10, 04:47 AM

Hey, I hope you know I am glad you are here.Was there something in my prior post in this thread that indicated that I think that you're not glad that I'm here? (Please don't misunderstand the 'tone' of any of my posts. A day without you at PF would be like a day without ... sunshine. However, while I do like the fact that the sun is shining, it doesn't contradict the fact of shade. This is just elementary optics which both you and Bell seem to be avoiding in your interpretations of Bell's theorem.)

I quote you from a previous post:
You shouldn't be able to have this level of correlation if locality and realism apply.
This betrays an apparent lack of understanding of elementary optics. Which, by the way, also applies in qm.

I hope nothing I say discourages you in any way. In fact, I encourage you to challenge from every angle. I enjoy a lot of your ideas and they keep me on my toes.Then, when I, or someone else, offers a, purported, LR model of entanglement that reproduces the qm predictions, why not look at it closely and express exactly why you think it is or isn't an LR model of entanglement?

I think you know that there are a lot of readers who are not active posters in many of our discussions. Just look at the view count on these threads. While I know what is what throughout the thread, these readers may not. That is why I frequently add comments to the effect of "not generally accepted", "show peer reviewed reference" , etc. my_wan and billschnieder get that too. So my objective is to keep casual readers informed so that they can learn both the "standard" (generally accepted) and the "non-standard" (minority) views. I would encourage any reader to listen and learn to a broad spectrum of ideas, but obviously the mainstream should be where we start. And that is what PhysicsForums follows as policy as well.My approach to understanding Bell's theorem isn't a 'nonstandard' or 'minority' approach. To characterize it as such does a disservice to me and misinforms less sophisticated posters. What you are stating, sometimes, as the mainstream view is, I think, incorrect, and also not the mainstream view.

There's a very important difference between:
1. No physical theory of local Hidden Variables can ever reproduce all of the predictions of Quantum Mechanics.
and:
2. No Local Realistic physical theory can ever reproduce all of the predictions of Quantum Mechanics.

We KNOW that 2. is incorrect, because viable LR models of entanglement exist, and they remain unrefuted. If you refuse to acknowledge them, then so what. They exist nonetheless.

I want readers of this thread to understand this. There are LR theories of entanglement which reproduce all of the predictions of qm. They're in the preprint archives at arxiv.org, and there are some that have even been published in peer reviewed journals. Period. If you, DrChinese, want to dispute this, then it's incumbent on you, or anyone who disputes these claims, to analyze the theories in question and refute their claims regarding locality or realism or compatibility with qm. If this isn't done, then the claims stand unrefuted. And, since no such refutations exist, then the current status of LR theories which reproduce all qm predictions is that they remain unrefuted.

If you don't want to inform casual readers of this thread of this fact, then fine. I've informed them.

And just so there's no confusion about this, let me say it again. Bell's theorem does not rule out local realistic theories of entanglement. If DrChinese disagrees with this, then I want you, the casual reader of this thread, to demand that DrChinese analyze a purported LR theory and show that it either isn't local or realistic or both or that it doesn't reproduce qm predictions.

On the other, when posters suitably label items then that is not an issue and I don't feel compelled to add my (sometimes snippy) comments. Also, many times a personal opinion can be converted to a question so as not to express an opinion that can be mistrued. For example: "Is it possible that Bell might not have considered the possibility of X?". That statement - er question - does not attempt to contradict Bell per se. And then the discussion can continue.And what you often don't do in many of your statements is to qualify exaclty what you're saying. So, bottom line, your statements often perpetuate the myth that Bell's theorem informs us about facts of nature -- rather than facts of what sorts of theoretical forms are compatible with certain experimental situations.

And less feelings get hurt. And people won't think I am resorting to authority as a substitute for a more convincing argument. As I often say, it only takes one. Of course, me being me, that line is stolen (in mangled form) from a man who is quite well known. In fact, maybe it is time to add something new to my tag line...There are, at least, a dozen different LR models of entanglement in the literature which reproduce the qm predictions. Of course, if you won't look at any of them then 10^1000 wouldn't be enough. Would it?

All you have to do is look at one. If you think it doesn't qualify as a local or a realistic model, then you can point out why (but don't require that it produce incorrect predictions, because that's just silly). If you're unwilling to do that, then your Einstein quote is just fluffy fuzziness wrt your position on LR models of entanglement.

I want you to refute an LR theory of entanglement that I present. You've been called out. Will you accept the challenge?

By the way, I like the Korzybski quote.

www.DrChinese.com "The map is not the territory." - Korzybski.

"Why 100? If I were wrong, one would have been enough." - Albert Einstein, when told of publication of the book One Hundred Authors Against Einstein.

my_wan

Jun14-10, 06:48 AM

ThomasT has a point wrt mainstream view on the realism issue. I know very few that take as hard a view on realism as DrC. Rather an acceptance the uncertainty in any particular interpretation. Of course my personal experience is limited. However, a review of published opinions is not necessarily indicative of the general opinion. Like the myth that violence is increasing, when in fact it's been steadily dropping year to year for many generations. I would be curious what the actual numbers look like.

So even though BI might specify the status quo of the argument, it's likely much more suspect to claim the standard interpretation represents the predominate view.

The sample looks like this:

-1
-1
-1
-1...

Where local realism predicts

1
1
1
1...

A little consideration will tell you that local realism is falsified in this case.
Only with a very restricted notion of realism and what it entails can this be said. I also never got a response to my objection to calling realistic ways a defining contextualization of such variables a Fair Sampling argument.

I would love to hear a definition of contextual variables? Certain statements made it sound like contextual variables, by definition, meant non-realistic. I never got a response to the questions, is velocity a contextual variable?

I also never got an objection when I pointed out that straight forward squaring of any vector leads to values that are unavoidably coordinate dependent, that is it produces different answers and not just the same answer defined by a different coordinate system. Yet the requirement that a realistic model must model arbitrary detector settings, rather than arbitrary offsets, requires a coordinate independent square of a vector.

To say realism is falsified most certainly is an overreach of what can be ascertained from the facts. I don't care who is right, I want a clearer picture of the mechanism, locally realistic or not.

DevilsAvocado

Jun14-10, 07:28 AM

I must inform the casual reader: Don’t believe everything you read at PF, especially if the poster defines you as "less sophisticated".

Everything is very simple: If you have one peer reviewed theory (without references or link) stating that 2 + 2 = 5 and a generally accepted and mathematical proven theorem stating 2 + 2 = 4, then one of them must be false.

And remember: Bell’s theorem has absolutely nothing to do with "elementary optics" or any other "optics", I repeat – absolutely nothing. Period.

zonde

Jun14-10, 08:45 AM

Absolutely not. The statistics, as stated, are in fact predicated on completely randomized polarizations coming from the source. However, if the photons coming from the source were 50% H and V, strictly at those 2 polizations, it would have the same statistical effect, because the rate photons switch paths from H is the same rate they would switch from V in reverse.

But the fact remains, purely randomed polarization would have the same statistics. I went to great lengths to verify this assumption.

Yep, but this is quiet different from random polarizations, where any setting of the PBS sends 50% in each direction, but also incidentally matches, at all PBS settings, the statistics as two pure polarizations at 90 degree offsets.

Consider this: Add the first and second set of 5 second runs together and the 85% and 15% wash out, just like what you initially specified above. Now check and see that the same thing happens at all settings. Thus if it always washed out at all settings in the strict H and V cases, why would a completely randomized source, which only changes those same settings via the photons rather than polarizer settings lead to anything different in the overall statistics?

Yep, but only if the photon from the source are not randomized, which you falsely assumed my description didn't do, simply because the overall statistics happen to match for both pure H and V and randomized photon polarization cases.

The only mistake I see in your reasoning is thinking that because there is a statistical match between the pure H and V case, and the randomized case, I must have only have been referring the pure H and V case. This is wrong. Check the same statistics for the randomized case and you'll see a statistical match for both cases, but the randomized case would invalidate your +45° and -45° case, because I was assuming the randomized case.
Hmm, you think that I am questioning 50%/50% statistics?
I don't do that. I am questioning your statement that "it's reasonable to say ~15% that would have went left go right, and visa versa."
That is not reasonable or alternatively it is reasonable only if you assume that you have source with even mixture of H and V photons.
If you have source that consists of even mixture of photons with any polarization then reasonable assumption is that ~25% changed their channel.

DrChinese

Jun14-10, 09:45 AM

...2. No Local Realistic physical theory can ever reproduce all of the predictions of Quantum Mechanics.

We KNOW that 2. is incorrect, because viable LR models of entanglement exist, and they remain unrefuted. If you refuse to acknowledge them, then so what. They exist nonetheless.

I want readers of this thread to understand this. There are LR theories of entanglement which reproduce all of the predictions of qm. They're in the preprint archives at arxiv.org, and there are some that have even been published in peer reviewed journals. Period. If you, DrChinese, want to dispute this, then it's incumbent on you, or anyone who disputes these claims, to analyze the theories in question and refute their claims regarding locality or realism or compatibility with qm.

If you don't want to inform casual readers of this thread of this fact, then fine. I've informed them.

And just so there's no confusion about this, let me say it again. Bell's theorem does not rule out local realistic theories of entanglement. If DrChinese disagrees with this, then I want you, the casual reader of this thread, to demand that DrChinese analyze a purported LR theory and show that it either isn't local or realistic or both or that it doesn't reproduce qm predictions.
...

There are, at least, a dozen different LR models of entanglement in the literature which reproduce the qm predictions. Of course, if you won't look at any of them then 10^1000 wouldn't be enough. Would it?

All you have to do is look at one. If you think it doesn't qualify as a local or a realistic model, then you can point out why (but don't require that it produce incorrect predictions, because that's just silly). If you're unwilling to do that, then your Einstein quote is just fluffy fuzziness wrt your position on LR models of entanglement.

I want you to refute an LR theory of entanglement that I present. You've been called out. Will you accept the challenge?

I have a requirement that is the same requirement as any other scientist: provide a local realistic theory that can provide data values for 3 simultaneous settings (i.e. fulfilling the realism requirement). The only model that does this that I am aware of is the simulation model of De Raedt et al. There are no others to consider. There are, as you say, a number of other *CLAIMED* models yet none of these fulfill the realism requirement. Therefore, I will not look at them.

Perhaps you will show me where any of the top scientific teams have written something to the effect of "local realism is tenable after Bell". Because all of the teams I know about state the diametric opposite. Here is Zeilinger (1999) in a typical quote of his perspective:

"Second, a most important development was due to John Bell (1964) who continued the EPR line of reasoning and demonstrated that a contradiction arises between the EPR assumptions and quantum physics. The most essential assumptions are realism and locality. This contradiction is called Bell’s theorem."

I would hope you would recognize the above as nearly identical to my line of reasoning. So if you know of any hypothesis that contradicts the above AND yields a local realistic dataset, please give a link and I will give you my thoughts. But I cannot critic that which does not exist. (Again, an exception for the De Raedt model which has a different set of issues entirely.)

DevilsAvocado

Jun14-10, 10:05 AM

Because precisely what we can presume about reality, counterfactuals, context, etc., plays a large role in what we can consider to get GR <> QM to GR = QM.

Maybe you’re right. Personally, I think semantic discussions on "reality" could keep you occupied for a thousand years, without substantial progress. What if Einstein presented something like this:

"The causal reality for the joint probabilities of E having a relation to M, in respect of the ideal context, is strongly correlated to C."

Except for the very fine "sophistication" – could this be of any real use?

Maybe I’m wrong, and Einstein indeed used this very method to get to:

E = mc2

... I don’t know ...

But wrt "reality", I think we have a very real problem, in that the discordance for aligned parallels is 0:

N(0°, 0°) = 0

If we then turn one minus thirty degrees and the other plus thirty degrees, from a classical point of view we should get:

N(+30°, -30°) ≤ N(+30°, 0°) + N(0°, -30°)

Meaning that the discordance when both are turned cannot be greater than the sum of the two turned separately, which is very logical and natural.

But this is NOT true according to quantum mechanical predictions and experiments!!

Even a high school freshman can understand this problem, you don’t have to be "sophisticated" or "intellectual superior", that’s just BS.

Now, to start long die-hard discussions on "elementary optics" to get an illusion of a probable solution is not very bright, not even "sophisticated".

I think most here realize that attacking the mathematics as such cannot be considered "healthy".

To discuss what’s real or not maybe could lead to "something", but it will never change the mathematical reality.

Therefore, the only plausible way 'forward' is to find a 'flaw' in QM, which will be very very hard since QM is the most precise scientific theory we got. That potential 'flaw' in QM has to be mathematical, not semantical – words won’t change anything about the EPR paradox and the mathematical predictions of QM.

I think it’s very interesting with your attempts to get a 'classical' explanation for what happens in EPR-Bell experiments, but how is this ever going to change the real mathematical truth, which we both know is true?

DrChinese

Jun14-10, 10:29 AM

1. ThomasT has a point wrt mainstream view on the realism issue. I know very few that take as hard a view on realism as DrC.

2. Only with a very restricted notion of realism and what it entails can this be said. I also never got a response to my objection to calling realistic ways a defining contextualization of such variables a Fair Sampling argument.

3. I would love to hear a definition of contextual variables? Certain statements made it sound like contextual variables, by definition, meant non-realistic. I never got a response to the questions, is velocity a contextual variable?

4. I also never got an objection when I pointed out that straight forward squaring of any vector leads to values that are unavoidably coordinate dependent, that is it produces different answers and not just the same answer defined by a different coordinate system. Yet the requirement that a realistic model must model arbitrary detector settings, rather than arbitrary offsets, requires a coordinate independent square of a vector.

5. To say realism is falsified most certainly is an overreach of what can be ascertained from the facts. I don't care who is right, I want a clearer picture of the mechanism, locally realistic or not.

In trying to be complete in my response so you won't think I'm avoiding anything:

1. ThomasT is refuted in a separate post in which I provided a quote from Zeilinger. I can provide a similar quote from nearly any major researcher in the field. And all of them use language which is nearly identical to my own (since I closely copy them). So YES, the generally accepted view does use language like I do.

2. GHZ is very specific. It is a complex argument, but uses the very same definition of reality as does Bell. And this yields a DIFFERENT prediction in every case from QM, not just in a statistical ensemble. So NO, your conclusion is incorrect.

3. A contextual variable is one in which the nature of the observation is part of the equation for predicting the results. Thus it does not respect observer independence. You will see that in your single particle polarizer example, observer dependence appears to be a factor in explaining the results. Keep in mind, contextuality is not an assumption of Bell.

4. Your argument here does not follow regarding vectors. So what if it is or is not true? This has nothing to do with a proof of QM over local realism. I think you are trying to say that if vectors don't commute, then by definition local realism is ruled out. OK, then local realism is ruled out which is what I am asserting anyway. But that result is not generally accepted as true and so I just don't follow. How am I supposed to make your argument for you?

5. I know of noone who can provide ANY decent picture, and I certainly can't help. There are multiple interpretations, take your pick.

DevilsAvocado

Jun14-10, 11:28 AM

I don't care who is right, I want a clearer picture of the mechanism, locally realistic or not.
I’m with you on this one 1000%. This is what we should discuss, not "elementary optics".

I think that it’s overlooked in this thread that this was a major problem for John Bell as well (and I’m going to prove this statement in a few days).

Bell knew that his theorem creates a strong contradiction between QM & SR, one or both must be more or less wrong. Then if QM is more or less wrong, it could mean that Bell’s theorem is also more or less wrong, since it builds its argument on QM predictions.

5. I know of noone who can provide ANY decent picture, and I certainly can't help. There are multiple interpretations, take your pick.

Don’t you think that interpretations are a little too easy way out of this?? I don’t think John Bell would have agreed with you here...

DrChinese

Jun14-10, 11:38 AM

Bell knew that his theorem creates a strong contradiction between QM & SR, one or both must be more or less wrong. Then if QM is more or less wrong, it could mean that Bell’s theorem is also more or less wrong, since it builds its argument on QM predictions.

Don’t you think that interpretations are a little too easy way out of this?? I don’t think John Bell would have agreed with you here...

Bell shifted a bit on interpretations. I think the majority view is that he supported a Bohmian perspective, but I am not sure he came down fully in any one interpretation. At any rate, I really don't know what we can say about underlying physical mechanisms. We just don't know how nature manages to implement what we call the formalism.

And don't forget that Bell does not require QM to be correct, just that the QM predictions are incompatible with LR predictions. Of course, Bell tests confirm QM to many SD.

DevilsAvocado

Jun14-10, 11:57 AM

... QM predictions are incompatible with LR predictions.

Yes you are right, and this is what causes the dilemma. The Einsteinian argument fails:

no action on a distance (polarisers parallel) ⇒ determinism

determinism (polarisers nonparallel) ⇒ action on a distance

Meaning QM <> SR.

my_wan

Jun14-10, 01:49 PM

Hmm, you think that I am questioning 50%/50% statistics?
I don't do that.
No. I understood what you asserted.

I am questioning your statement that "it's reasonable to say ~15% that would have went left go right, and visa versa."
Yes, I seen that. The pure case is in fact what I used to empirically verify the assumption.

That is not reasonable or alternatively it is reasonable only if you assume that you have source with even mixture of H and V photons.
And this is where you go wrong again. I stand by my factual statement (not assumption) that randomized photon polarizations will have the same route switching statistics as an even mixture of pure H and V polarizations. I verified it both mathematically and in computer simulations.

Consider, in the pure case where you got it right, where you move a detector setting from 0 to 22.5 degrees. The route switching statistics look like cos^2(22.5) = sin^2(67.5), thus you are correct about the pure polarization pairs at 90 degree offsets. Now notice that cos^2(theta) = sin^2(theta +- 90) for ANY arbitrary theta. Now add a second pair of pure H and V photons polarizations that is offset 45 degrees from the first pair. Now at a 0 angle detector setting you've added 50% more photons to be detected from the new H and 50% from the new V polarization beams. Since cos^2(theta) = sin^2(theta +- 90) in ALL cases the overall statistics have not changed. To add more pure beam pairs without changing overall statistics, you have to add 2 pair of pure H and V beams at both 22.5 and 67.5 degree offsets. To add more pure beam sets, without changing overall statistics, requires 4 more H and V pure beams offset equidistant from those 4. Next step requires 8 to maintain the same statistics, and simply take the limit. You then end up with a completely randomized set of photons polarization that exhibit the exact same path switching statistics as the pure H and V case, because cos^2(theta) = sin^2(theta +- 90) for absolutely ALL values of theta.

So if you still don't believe it, show me. If you want a computer program that uses a random number generator, to generate randomly polarized photons and send them to a virtual detector, ask. I can write the program pretty quick. You'll need AutoIt (freeware, not nagware) if you don't want to be sent an exe. With AutotIt installed, you can run the script directly without compiling it.

If you have source that consists of even mixture of photons with any polarization then reasonable assumption is that ~25% changed their channel.
False, and false is not an assumption, it is a demonstrable fact. So long as the pure randomization case exhibits those statistics, physically so must the completely randomized case. This fact is central to EPR modeling attempts. If you can demonstrate otherwise, I'll add a sig line to my profile stating that and linking to where you made a fool of me.

my_wan

Jun14-10, 02:46 PM

Hmm, you think that I am questioning 50%/50% statistics?
I don't do that. I am questioning your statement that "it's reasonable to say ~15% that would have went left go right, and visa versa."
That is not reasonable or alternatively it is reasonable only if you assume that you have source with even mixture of H and V photons.
If you have source that consists of even mixture of photons with any polarization then reasonable assumption is that ~25% changed their channel.
I also just notice you contradicted yourself. You say:
1) ...it is reasonable only if you assume that you have source with even mixture of H and V photons.
2) If you have source that consists of even mixture of photons with any polarization then reasonable assumption is that ~25% changed their channel.

But a random distribution is an "even mixture of H and V" as defined by 1), just not all on the same 2 axis. For a random distribution, there statistically exist both an opposite and perpendicular case for every possible polarization instance.

my_wan

Jun14-10, 05:25 PM

In trying to be complete in my response so you won't think I'm avoiding anything:

1. ThomasT is refuted in a separate post in which I provided a quote from Zeilinger. I can provide a similar quote from nearly any major researcher in the field. And all of them use language which is nearly identical to my own (since I closely copy them). So YES, the generally accepted view does use language like I do.
Don't have much to refute this with. I've read the arguments and counterarguments, I was more curious about the general opinion among physicist, with published positions on EPR or not.

2. GHZ is very specific. It is a complex argument, but uses the very same definition of reality as does Bell. And this yields a DIFFERENT prediction in every case from QM, not just in a statistical ensemble. So NO, your conclusion is incorrect.
The question was the reasoning behind labeling any specific form of contextualization of contextual variables a Fair Sampling argument. I'm not even sure what this response has to do with the issue as stated. Though I have previously expressed confusion how you defined precisely what did or didn't qualify as realism even with that definition. Merely restating the definition doesn't help much. Nor does it indicate whether realistic models can exist that doesn't respect that definition.

3. A contextual variable is one in which the nature of the observation is part of the equation for predicting the results. Thus it does not respect observer independence. You will see that in your single particle polarizer example, observer dependence appears to be a factor in explaining the results. Keep in mind, contextuality is not an assumption of Bell.
Nice definition, I'll keep that for future reference. I'm well aware that my single polarizer example contains contextual dependencies, yet empirically valid consequences. It was the fact that the contextual values didn't depend on any correlations to anything that was important to the argument. Thus it was limited to refuting a non-local claim, not a realism claim. What it indicates is that a classical mechanism for the nonlinear path switching of uncorrelated photon responses to a single polarizer is required to fully justify a realistic model. I even give the opinion that a mechanistic explanation of the Born rule might be required to pull this off. Some would be happy to just accept the empirical mechanism itself as a local classical optics effect and go from there. I'm not. I'm aware contextuality was not an assumption of Bell. Hence the requirement of some form of classical contextuality to escape the stated consequences of his inequality.

4. Your argument here does not follow regarding vectors. So what if it is or is not true? This has nothing to do with a proof of QM over local realism. I think you are trying to say that if vectors don't commute, then by definition local realism is ruled out. OK, then local realism is ruled out which is what I am asserting anyway. But that result is not generally accepted as true and so I just don't follow. How am I supposed to make your argument for you?
1) You say: "Your argument here does not follow regarding vectors. So what if it is or is not true?", but the claim about this aspect of vectors is factually true. Read this carefully:
http://www.vias.org/physics/bk1_09_05.html
Note: Multiplying vectors from a pool ball collision under 2 different coordinate systems don't just lead to the same answer expressed in a different coordinate system, but an entirely different answer altogether. For this reason such vector operations are generally avoided, using scalar multiplication instead. Yet the Born rule and cos^2(theta) do just that.
2) You say: "I think you are trying to say that if vectors don't commute, then by definition local realism is ruled out.", but they don't commute for pool balls either, when used this way. That doesn't make pool balls not real. Thus the formalism has issues in this respect, not the reality of the pool balls. I even explained why: because given only the product of a vector, there exist no way of -uniquely- defining the particular vectors that went into defining it.

5. I know of noone who can provide ANY decent picture, and I certainly can't help. There are multiple interpretations, take your pick.
That's more than a little difficult when you seem to falsely represent any particular contextualization of variables as a Fair Sampling argument. Refer back to 2. where your response was unrelated to my objection to labeling contextualization arguments as a Fair Sampling argument.

zonde

Jun15-10, 04:43 AM

Consider, in the pure case where you got it right, where you move a detector setting from 0 to 22.5 degrees. The route switching statistics look like cos^2(22.5) = sin^2(67.5), thus you are correct about the pure polarization pairs at 90 degree offsets.
To set it straight it's |cos^2(22.5)-cos^2(0)| and |sin^2(22.5)-sin^2(0)|

Now notice that cos^2(theta) = sin^2(theta +- 90) for ANY arbitrary theta. Now add a second pair of pure H and V photons polarizations that is offset 45 degrees from the first pair. Now at a 0 angle detector setting you've added 50% more photons to be detected from the new H and 50% from the new V polarization beams. Since cos^2(theta) = sin^2(theta +- 90) in ALL cases the overall statistics have not changed.
The same way as above
|cos^2(67.5)-cos^2(45)| and it is not equal to |cos^2(22.5)-cos^2(0)|
and
|sin^2(67.5)-sin^2(45)| and it is not equal to |sin^2(22.5)-sin^2(0)|

so if you add H and V photons that are offset by 45 degrees you change your statistics.

So if you still don't believe it, show me. If you want a computer program that uses a random number generator, to generate randomly polarized photons and send them to a virtual detector, ask. I can write the program pretty quick. You'll need AutoIt (freeware, not nagware) if you don't want to be sent an exe. With AutotIt installed, you can run the script directly without compiling it.
I would stick to simple example:
polarizer at 0 polarizer at 22.5
p=0 cos^2(0-0) =1 cos^2(0-22.5) =0.85 difference=0.15
p=45 cos^2(45-0) =0.5 cos^2(45-22.5) =0.85 difference=0.35
p=90 cos^2(90-0) =0 cos^2(90-22.5) =0.15 difference=0.15
p=135 cos^2(135-0)=0.5 cos^2(135-22.5)=0.15 difference=0.35
average difference=0.25

I also just notice you contradicted yourself. You say:
1) ...it is reasonable only if you assume that you have source with even mixture of H and V photons.
2) If you have source that consists of even mixture of photons with any polarization then reasonable assumption is that ~25% changed their channel.

But a random distribution is an "even mixture of H and V" as defined by 1), just not all on the same 2 axis. For a random distribution, there statistically exist both an opposite and perpendicular case for every possible polarization instance.
The statement in bold makes the difference between 1) and 2).

my_wan

Jun15-10, 06:29 AM

To set it straight it's |cos^2(22.5)-cos^2(0)| and |sin^2(22.5)-sin^2(0)|

This formula breaks at arbitrary settings, because you are comparing a measurement at 22.5 to a different measurement at 0 that you are not even measuring at the that time. You have 2 photon routes in any 1 measurement, not 2 polarizer setting in any 1 measurement. Instead you have one measurement at one location and what you are comparing is the photon statistics that take a particular route through a polarizer at that one setting, not 2 settings.

In your formula you have essentially subtracted V polarizations from V polarizations not being measured at that setting, and visa versa for H polarization. We are NOT talking EPR correlations here, only normal photon route statistics as defined by a single polarizer.

Consider, you have 1 polarizer at 1 setting (0 degrees) with 1 uncorrelated beam pointed at it, such that 50% of the light goes through. You change settings to 22.5 degrees. Now 15% of the V photons switch from going through to not going through the detector, sin^2(22.5). Now at the SAME 22.5 degree setting, you get cos^2(67.5) = 15% more detections from the H photons. 15% lost from V and 15% gained from H. This is even more general in that sin^2(theta) = |cos^2(90-theta)| for all theta. This is NOT a counterfactual measure. This is what you get from the one measure you are getting at the one setting. So you can't use cos from the previous measurement you are not currently measuring. Else it amounts to subtracting cos from a cos that's not even part of the polarizer setting at that time, which breaks it's consistency with BI violations statistics for other possible settings.

ONLY include the statistics of whatever measurement you are performing at THAT time, and you get statistical consistency between BI violations and photon route switching without correlations, with purely randomized photon polarizations. The key is DON'T mix the math for both settings for one measurement. This is key to subverting the couterfactuals in BI and still getting the same statistics. Only count what photons you can empirically expect to switch routes upon switching to that ONE setting by counting H adds and V subtracts at that ONE setting.

Then, by noting it's applicable at all thetas it remains perfectly valid for fully randomized photon polarizations at ANY arbitrary setting, provided you are allowed to arbitrarily relabel the 0 point of the non-physical coordinate labels.

my_wan

Jun15-10, 06:36 AM

Besides, you can't change my formula, then claim my formula doesn't do what I claimed because the formula you swapped in doesn't. :wink:

zonde

Jun15-10, 08:49 AM

This formula breaks at arbitrary settings, because you are comparing a measurement at 22.5 to a different measurement at 0 that you are not even measuring at the that time. You have 2 photon routes in any 1 measurement, not 2 polarizer setting in any 1 measurement. Instead you have one measurement at one location and what you are comparing is the photon statistics that take a particular route through a polarizer at that one setting, not 2 settings.

In your formula you have essentially subtracted V polarizations from V polarizations not being measured at that setting, and visa versa for H polarization. We are NOT talking EPR correlations here, only normal photon route statistics as defined by a single polarizer.
Yes, that is only speculation. Nothing straightforwardly testable.

Consider, you have 1 polarizer at 1 setting (0 degrees) with 1 uncorrelated beam pointed at it, such that 50% of the light goes through. You change settings to 22.5 degrees. Now 15% of the V photons switch from going through to not going through the detector, sin^2(22.5). Now at the SAME 22.5 degree setting, you get cos^2(67.5) = 15% more detections from the H photons. 15% lost from V and 15% gained from H.
Or lost 35% and gained 35%. Or lost x% and gained x%.
The question is not about lost photon count = gained photon count.
Question is about this number - 15%.
You will keep insisting that it's 15% because it's 15% both ways then we can stop our discussion right there.

This is even more general in that sin^2(theta) = |cos^2(90-theta)| for all theta.
sin(theta)=cos(90-theta) is trivial trigonometric identity. What you expect to prove with that?

This is NOT a counterfactual measure. This is what you get from the one measure you are getting at the one setting. So you can't use cos from the previous measurement you are not currently measuring. Else it amounts to subtracting cos from a cos that's not even part of the polarizer setting at that time, which breaks it's consistency with BI violations statistics for other possible settings.

ONLY include the statistics of whatever measurement you are performing at THAT time, and you get statistical consistency between BI violations and photon route switching without correlations, with purely randomized photon polarizations. The key is DON'T mix the math for both settings for one measurement. This is key to subverting the couterfactuals in BI and still getting the same statistics. Only count what photons you can empirically expect to switch routes upon switching to that ONE setting by counting H adds and V subtracts at that ONE setting.
Switch routes to ... FROM what?
You have no switching with ONE setting. You have to have switching FROM ... TO ... otherwise there is no switching.

DrChinese

Jun15-10, 09:10 AM

That's more than a little difficult when you seem to falsely represent any particular contextualization of variables as a Fair Sampling argument. Refer back to 2. where your response was unrelated to my objection to labeling contextualization arguments as a Fair Sampling argument.

To me, the (Un)Fair Sampling argument is as follows: "The full universe does not respect Bell's Inequality (or similar), while a sample does. The reason an attributes of the sample is different than that of the universe is that certain data elements are more likely to be detected than others, causing a skewing of the results."

I reject this argument as untenable; however, I would say my position is not generally accepted. A more generally accepted argument is that the GHZ argument renders the Fair Sampling assumption moot.

Now, I am not sure how this crept into our discussion except that as I recall, you indicated that this had some relevance to Bell. I think it is more relevant to tests of Bell's Inequality, which we aren't really discussing. So if there is nothing further to this line, we can drop it.

DrChinese

Jun15-10, 09:12 AM

zonde

Jun15-10, 09:39 AM

A more generally accepted argument is that the GHZ argument renders the Fair Sampling assumption moot.
Can you produce some reference?

I gave reference for the opposite in my post #715 (http://www.physicsforums.com/showthread.php?p=2760591#post2760591) but this paper is not freely accessible so it's hard to discuss it. But if you will give your reference then maybe we will be able to discuss the point.

JesseM

Jun15-10, 01:40 PM

The EPR view was that the element of reality at B determined by a measurement at A wasn't reasonably explained by spooky action at a distance -- but rather that it was reasonably explained by deductive logic, given the applicable conservation laws.

That is, given a situation in which two disturbances are emitted via a common source and subsequently measured, or a situation in which two disturbances interact and are subsequently measured, then the subsequent measurement of one will allow deductions regarding certain motional properties of the other.
If this is a local theory in which any correlations between the two disturbances are explained by properties given to them by the common source, with the disturbances just carrying the same properties along with them as they travel, then this is exactly the sort of theory that Bell examined, and showed that such theories imply certain conclusions about the statistics we find when we measure the "disturbances", the Bell inequalities. Since these inequalities are violated experimentally, this is taken as a falsification of any such local theory which explains correlations in terms of common properties given to the particles by the source.

Again, you might take a look at the lotto card analogy I offered in post #2 here (http://www.physicsforums.com/showthread.php?t=355538). If Alice and Bob are each sent scratch lotto cards with a choice of one of three boxes to scratch, and we find that on every trial where they choose the same box to scratch they end up seeing the same fruit, a natural theory would be that the source is always creating pairs of cards that have the same set of "hidden fruits" behind each of the three boxes. But this leads to the conclusion that on the trials where they choose different boxes there should be at least a 1/3 probability they'll see the same fruit, so if the actual observed frequency of seeing the same fruit when they scratch different boxes is some smaller number like 1/4, this can be taken as a falsification of the idea that the identical results when identical boxes are chosen can be explained by each card being assigned identical hidden properties by the source.
Do you doubt that this is the view of virtually all physicists?
Virtually all physicists would agree that the violation of Bell inequalities constitutes a falsification of the kind of theory you describe, assuming you're talking about a purely local theory.

DrChinese

Jun15-10, 02:06 PM

Can you produce some reference?

I gave reference for the opposite in my post #715 (http://www.physicsforums.com/showthread.php?p=2760591#post2760591) but this paper is not freely accessible so it's hard to discuss it. But if you will give your reference then maybe we will be able to discuss the point.

Here are a couple that may help us:

Theory:
http://www.cs.rochester.edu/~cding/Teaching/573Spring2005/ur_only/GHZ-AJP90.pdf

Experiment:
http://arxiv.org/abs/quant-ph/9810035

"It is demonstrated that the premisses of the Einstein-Podolsky-Rosen paper are inconsistent when applied to quantum systems consisting of at least three particles. The demonstration reveals that the EPR program contradicts quantum mechanics even for the cases of perfect correlations. By perfect correlations is meant arrangements by which the result of the measurement on one particle can be predicted with certainty given the outcomes of measurements on the other particles of the system. This incompatibility with quantum mechanics is stronger than the one previously revealed for two-particle systems by Bell's inequality, where no contradiction arises at the level of perfect correlations. Both spin-correlation and multiparticle interferometry examples are given of suitable three- and four-particle arrangements, both at the gedanken and at the real experiment level. "

DrChinese

Jun15-10, 02:13 PM

my_wan

Jun16-10, 12:35 AM

Yes, that is only speculation. Nothing straightforwardly testable.
It demonstrably consistent with any test. This consistency is taken from the fact that if you take a polarized beam and offset a polarizer in its path, offset defined by the difference between light polarization and polarizer setting, the statistics of what is passed, defined by the light intensity making it through that polarizer, exactly matches in all cases the assumptions I am making.

To demonstrate you can use this polarizer applet:
http://www.lon-capa.org/~mmp/kap24/polarizers/Polarizer.htm
Just add a second polarizer and consider the light coming through the first polarizer your polarized beam, which means you double whatever percentage is read, because the 50% lost to the first polarizer doesn't count.

Or lost 35% and gained 35%. Or lost x% and gained x%.
The question is not about lost photon count = gained photon count.
Question is about this number - 15%.
You will keep insisting that it's 15% because it's 15% both ways then we can stop our discussion right there.
The number 15% only results from the 22.5 setting. If we use a 45 setting then it's 50% lost and 50% gained. Any setting cos^(theta) defines both lost and gained because sin^2(theta) = |cos^2(90-theta)| in all cases. There is nothing special about 22.5 and 15%.

sin(theta)=cos(90-theta) is trivial trigonometric identity. What you expect to prove with that?
That's why it constitutes a proof at all angle, and not just the 22.5 degree setting that gets 15% lost and gained in the example used.

Switch routes to ... FROM what?
You have no switching with ONE setting. You have to have switching FROM ... TO ... otherwise there is no switching.
Lost is photons that would have passed the polarizer but didn't at that setting. Gained is what wouldn't have passed the polarizer but did at that setting. Let's look at it using a PBS so we can divide things in H, V, and L, R routes through the polarizer.

Consider a PBS rather than a plain polarizer placed in front of a simple polarized beam of light that evenly contains pure H an V polarized photons. We'll label the V polarization as angle 0. So, a PBS set a angle 0 will have 100% of the V photons takes L route, and 100% of the H photons takes R. At 22.5 degrees L is ~85% V photons and ~15% H photons, while R beams now contains ~15% V photons and ~85% H photons. WARNING: You have to consider that by measuring the photons at a new setting, it changes the photons polarization to be consistent with that new setting. At a setting of 45 degree you get 50% H and 50% V going L, and 50% H and 50% V going R. Nothing special about 15% or the 22.5 degree setting.

Now what the sin^2(theta) = cos^2(90-theta) represents here is any one (but only one) polarizer setting, such that theta=theta in both cases, and our sin^2(theta) is V photons that switch to the R route, while cos^2(90-theta) is the H photons that switch to the L route.

Now since this is a trig identity for all cases, it valid for ANY uniform mixture of polarizations, whether 2 pure H and V beams or a random distribution, which by definition is a uniform mixture of polarizations.

It would even be easy to make non-uniform beam mixtures, where certain ranges of polarizations are missing in the beam, such that the sin^2(theta) = cos^2(90-theta) can be used to define the ratios of beam intensities as theta, the polarizer setting, is adjusted. If ANY situation can be defined where sin^2(theta) = cos^2(90-theta) doesn't properly predict beam intensity ratios, from any crafted beam mixture, then I'm wrong.

And here's the kicker: by defining properties in terms of photons properties, rather than properties as defined by the polarizer settings that detect them, and using these polarizer path statistics, BI violations statistics also result as a consequence.

my_wan

Jun16-10, 01:46 AM

Again, I am missing your point. So what? How does this relate to Bell's Theorem or local realism?
It relates to the arbitrary angle condition placed on the modeling of hv models and nothing else.
Consider:
Hidden variable model successfuly Models QM coincidence statistics, but requires coordinate freedom that is objected to. The following properties are noted:
1) One ot the other, but not both detector settings must be defined to have a 0 angle setting. (objection noted)
2) The detector defined as a zero setting has zero information about the other detectors setting.
3) The zero setting can be arbitrarily changed to any absolute setting along with the detector angle changes with or WITHOUT redefining absolute photon polarizations in the process.
4) The default photon polarizations can be rotated with absolute impunity, having no effect whatsoever on coincidence statistic.
5) The only thing considered for detections/non-detections is the photon polarization relative to the setting of the detector it actually hit.

Thus this proves the 0 coordinate requirement in no way hinges upon physical properties unique to the angles chosen. It is a mathematical artifact, related to non-commuting vectors. It's essentially equivalent of giving only the path of a pool ball and demanding that the path of q-ball that hit it must be uniquely calculable in order to prove pool balls are real.

I'll get around to attempting to use predefined non-commutative vectors to get around it soon, but I have grave doubts. Disallowing arbitrary 0 coordinates is tantamount to disallowing an inertial observer from self defining their own velocity as 0, which requires a universal 0 velocity.

At the very least, I would appreciate if you quit misrepresenting the 0 angle condition as a statistically unique physical state at that angle.

my_wan

Jun16-10, 02:41 AM

If this is a local theory in which any correlations between the two disturbances are explained by properties given to them by the common source, with the disturbances just carrying the same properties along with them as they travel, then this is exactly the sort of theory that Bell examined, and showed that such theories imply certain conclusions about the statistics we find when we measure the "disturbances", the Bell inequalities. Since these inequalities are violated experimentally, this is taken as a falsification of any such local theory which explains correlations in terms of common properties given to the particles by the source.

When you say: "this is exactly the sort of theory that Bell examined", it does require some presumptive caveats. That is that the properties that is supposed as carried by the photons are uniquely identified by the route it takes at a detector.

If a particle has a perfectly distinct property, in which a detector setting tuned to a nearby setting has some nonlinear odds of defining the property as equal to that offset setting, then BI violations ensue. The problem for models is that vector product are non-commutative, requiring a 0 angle to be defined for one of the detectors.

Consider a hv model that models BI violations, but has the 0 setting condition. You can assign one coordinate system to the emitter, which the detectors know nothing about. Another coordinate system to the detectors, which the emitter knows nothing about, but rotates in tandem with one or the other detector. Now rotating the emitter has absolutely no effect on the coincidence statistics whatsoever, thus proving that the statistics is not unique to physical states of the particles at a given setting. You can also have any arbitrary offset between the two detectors, and consistency with QM is also maintained. Thus the non-commutativity of vectors is the stumbling block for such models. But the complete insensitivity to arbitrary emitter settings proves it's not a physical stumbling block.

So perhaps you can explain to me the physical significant of requiring a non-physical coordinate choice to give exactly the same answers to vector products, under arbitrary rotations, when you can't even do that on a pool table?

zonde

Jun16-10, 03:43 AM

Lost is photons that would have passed the polarizer but didn't at that setting. Gained is what wouldn't have passed the polarizer but did at that setting. Let's look at it using a PBS so we can divide things in H, V, and L, R routes through the polarizer.

Consider a PBS rather than a plain polarizer placed in front of a simple polarized beam of light that evenly contains pure H an V polarized photons. We'll label the V polarization as angle 0. So, a PBS set a angle 0 will have 100% of the V photons takes L route, and 100% of the H photons takes R. At 22.5 degrees L is ~85% V photons and ~15% H photons, while R beams now contains ~15% V photons and ~85% H photons. WARNING: You have to consider that by measuring the photons at a new setting, it changes the photons polarization to be consistent with that new setting. At a setting of 45 degree you get 50% H and 50% V going L, and 50% H and 50% V going R. Nothing special about 15% or the 22.5 degree setting.
You compare measurement at 22.5 angle with hypothetical measurement at 0 angle. When I used similar reasoning your comment was that:

This formula breaks at arbitrary settings, because you are comparing a measurement at 22.5 to a different measurement at 0 that you are not even measuring at the that time. You have 2 photon routes in any 1 measurement, not 2 polarizer setting in any 1 measurement. Instead you have one measurement at one location and what you are comparing is the photon statistics that take a particular route through a polarizer at that one setting, not 2 settings.

In your formula you have essentially subtracted V polarizations from V polarizations not being measured at that setting, and visa versa for H polarization. We are NOT talking EPR correlations here, only normal photon route statistics as defined by a single polarizer.
So how is your reasoning so radically different than mine that you are allowed to use reasoning like that but I am not allowed?

But let's say it's fine and look at a bit modified case of yours.
Now take beam of light that consists of H, V, +45 and -45 polarized light. What angle should be taken as 0 angle in this case? Let's say it's again V polarization that is 0 angle. Can you work out photon rates in L and R beams for all photons (H,V,+45,-45)?

Now what the sin^2(theta) = cos^2(90-theta) represents here is any one (but only one) polarizer setting, such that theta=theta in both cases, and our sin^2(theta) is V photons that switch to the R route, while cos^2(90-theta) is the H photons that switch to the L route.
How you define theta? Is it angle between polarization axis of polarizer (PBS) and photon so that we have theta1 for H and theta2 for V with condition that theta1=theta2-90?
Otherwise it's quite unclear what you mean with your statement.

my_wan

Jun16-10, 06:30 AM

So how is your reasoning so radically different than mine that you are allowed to use reasoning like that but I am not allowed?

When I give the formula sin^2(theta) = |cos^2(90-theta)| theta and theta are the same number from the same measurement. Hence:
sin^2(0) = |cos^2(90-0)|
sin^2(22.5) = |cos^2(90-22.5)|
sin^2(45) = |cos^2(90-45)|
etc.

You only make presumptions about the path statistics of individual photons, and wait till after the fact to do any comparing to another measurement.

You previously give the formula:
To set it straight it's |cos^2(22.5)-cos^2(0)| and |sin^2(22.5)-sin^2(0)|
Here you put in the 0 from the first measurement as if it's part of what you are now measuring. It's not. The 22.5 is ALL that you are now measuring. The only thing you are comparing after the fact is the resulting path effects. You don't include measurements you are not presently performing to calculate the results of the measurement you are now making. This is to keep the reasoning separate, and avoid the interdependence inherent in the presumed non-local aspect of EPR correlations. It also allows you to compare it to any arbitrary other measurement without redoing the calculation. It's a non-trivial condition of modeling EPR correlations without non-local effects to keep the measurements separate. On these grounds alone mixing settings from other measurements to calculate results of the present measurement must be rejected. Only the after the fact results may be compared, to see if the local path assumptions remain empirically and universally consistent, with and without EPR correlations.

The primary issue remains whether the path statistics are consistent for both the pure H and V case and the randomized polarization case. This is the point on which I will put my pride ALL in by stating this is unequivocally a factual yes. This should also calculate cases in which the intensity of H and V are unequal, giving the variations of intensity at various polarizer settings at different angles. Such non-uniform beam mixtures to test this can quiet easily be experimentally tested. From a QM perspective this would be equivalent to interference in the wavefunction at certain angles.

zonde

Jun16-10, 07:07 AM

Here are a couple that may help us:

Theory:
http://www.cs.rochester.edu/~cding/Teaching/573Spring2005/ur_only/GHZ-AJP90.pdf
Nice, it's exactly the same paper I looked at. I was just unsure if posting that link doesn't violate forum rules.
As the file is not searchable I can point out that the text I quoted can be found on p.1136 in the last full paragraph (end of the page).

Experiment:
http://arxiv.org/abs/quant-ph/9810035

"It is demonstrated that the premisses of the Einstein-Podolsky-Rosen paper are inconsistent when applied to quantum systems consisting of at least three particles. The demonstration reveals that the EPR program contradicts quantum mechanics even for the cases of perfect correlations. By perfect correlations is meant arrangements by which the result of the measurement on one particle can be predicted with certainty given the outcomes of measurements on the other particles of the system. This incompatibility with quantum mechanics is stronger than the one previously revealed for two-particle systems by Bell's inequality, where no contradiction arises at the level of perfect correlations. Both spin-correlation and multiparticle interferometry examples are given of suitable three- and four-particle arrangements, both at the gedanken and at the real experiment level. "
I think I caught the point you are making.

Let's see if I will be able to explain my objections from the viewpoint of contextuality.
First about EPR, Bell and non-contextuality.
If we take photon that has polarization angle 0° and put it through polarizer at angle 0° it goes through with certainty. However if we change polarizer angle to 45° it goes through with 50% chance (that's basically Malus law).
So when we have entangled photons we have a prediction that 50% chance is somehow correlated between two entangle photons.
Bell's solution to this was non-contextuality i.e. photon is predetermined to take his chance one way or the other way. I would argue that EPR does not contain any considerations regarding solution of this particular problem - it was just the statement of general problem.

So what are other options different from Bell's solution. As I see other solution is that photons can be considered as taking this 50% chance (under 45° measurement base) dependent from particular conditions of polarizer (context of measurement). But in that case it is obvious that this correlation between two entangled photons of taking chances the same way should be correlation between measurement conditions of two photons and not only correlation between photons themselves. This of course leaves the question how measurement conditions get "entangled" and here I speculate that some leading photons from ensemble transfer their "entanglement" to equipment at the cost of becoming uncorrelated.
That way we have classical correlation when we measure photons in the same base as they were created (0° and 90° measurement base) and quantum (measurement context) correlation when we measure photons using incompatible base from the one they were created in (+45° and -45° measurement base).

Now if we go back to GHZ. These inequalities where derived using Bell's non-contextual approach. If we look at them from perspective of contextuality then we can see that this measurement context correlation is not strictly tied to photon polarizations but by varying experiment setup it could be possible to get quite different correlations then the ones you would expect from pure classical polarization correlations.
And if we isolate conditions so that we measure mostly measurement context correlations then pure classical polarization correlations will be only indirectly related to observed results.

zonde

Jun16-10, 07:28 AM

When I give the formula sin^2(theta) = |cos^2(90-theta)| theta and theta are the same number from the same measurement.
Please tell me what theta represents physically.

As I asked already:
How you define theta? Is it angle between polarization axis of polarizer (PBS) and photon so that we have theta1 for H and theta2 for V with condition that theta1=theta2-90?
Or it's something else?

DrChinese

Jun16-10, 09:06 AM

Now if we go back to GHZ. ...

Imagine that for a Bell Inequality, you look at some group of observations. The local realistic expectation is different from the QM expectation by a few %. Perhaps 30% versus 25% or something like that.

On the other hand, GHZ essentially makes a prediction of Heads for LR, and Tails for QM every time. You essentially NEVER get a Heads in an actual experiment, every event is Tails. So you don't have to ask whether the sample is fair. There can be no bias - unless Heads events are per se not detectible, but how could that be? There are no Tails events ever predicted according to Realism.

So using a different attack on Local Realism, you get the same results: Local Realism is ruled out. Now again, there is a slight split here are there are scientists who conclude from GHZ that Realism (non-contextuality) is excluded in all forms. And there are others who restrict this conclusion only to Local Realism.

JesseM

Jun16-10, 09:12 AM

When you say: "this is exactly the sort of theory that Bell examined", it does require some presumptive caveats. That is that the properties that is supposed as carried by the photons are uniquely identified by the route it takes at a detector.

If a particle has a perfectly distinct property, in which a detector setting tuned to a nearby setting has some nonlinear odds of defining the property as equal to that offset setting, then BI violations ensue.
Do you just mean that local properties of the particle are affected by local properties of the detector it comes into contact with? If so, no, this cannot lead to any violations of the Bell inequalities. Suppose the experimenters each have a choice of three detector settings, and they find that on any trial where they both chose the same detector setting they always got the same measurement outcome. Then in a local hidden variables model where you have some variables associated with the particle and some with the detector, the only way to explain this is to suppose the variables associated with the two particles predetermined the result they would give for each of the three detector settings; if there was any probabilistic element to how the variables of the particles interacted with the state of the detector to produce a measurement outcome, then there would be a finite probability that the two experimenters could both choose the same detector setting and get different outcomes. Do you disagree?
Consider a hv model that models BI violations, but has the 0 setting condition. You can assign one coordinate system to the emitter, which the detectors know nothing about. Another coordinate system to the detectors, which the emitter knows nothing about, but rotates in tandem with one or the other detector.
What do you mean by "assigning" coordinate systems? Coordinate systems are not associated with physical objects, they are just aspects of how we analyze a physical situation by assigning space and time coordinates to different events. Any physical situation can be analyzed using any coordinate system you like, the choice of coordinate system cannot affect your predictions about coordinate-invariant physical facts.

Anyway, your description isn't at all clear, could you come up with a mathematical description of the type of "hv model" you're imagining, rather than a verbal one?

ThomasT

Jun16-10, 01:10 PM

ThomasT is refuted in a separate post in which I provided a quote from Zeilinger. I can provide a similar quote from nearly any major researcher in the field. And all of them use language which is nearly identical to my own (since I closely copy them). So YES, the generally accepted view does use language like I do.Yes, the generally accepted view does use language like you do. And the generally accepted view for 30 years was that von Neumann's proof disallowed hidden variable theories, even though that proof had been shown to be unacceptable some 30 years before Bell's paper.

Zeilinger's language in the quote you provided, and the general tone of his continuing program, and your language wrt Bell, indicate to me that neither of you understand the subtleties of the arguments being presented here and in certain papers (which are, evidently, not being as clearly presented as necessary) regarding the interpretation of Bell's theorem (ie., the physical basis of Bell inequalities).

You can provide all the quotes you want. Quotes don't refute arguments. You're going to have to refute some purported LR models that reproduce qm predictions but are not rendered in the form of Bell's LHV model.

However, you refuse to look at them because:

I have a requirement that is the same requirement as any other scientist: provide a local realistic theory that can provide data values for 3 simultaneous settings (i.e. fulfilling the realism requirement). The only model that does this that I am aware of is the simulation model of De Raedt et al. There are no others to consider. There are, as you say, a number of other *CLAIMED* models yet none of these fulfill the realism requirement. Therefore, I will not look at them.

Please explain what you mean by "a local realistic model that can provide data values for 3 simultaneous settings". Three simultaneous settings of what? In the archetypal optical Bell test setup there's an emitter, two polarizers, and two detectors. The value of (a-b), the angular difference in the polarizer settings, can't have more than one value associated with any given pair of detection attributes. So, I just don't know what you're talking about wrt your 'requirement'.

My not understanding your 'requirement' might well be just a 'mental block' of some sort on my part. In any case, before we can continue, so that you might actually 'refute' something (which you haven't yet), you're going to have to explain, as clearly as you can, what this "data values for 3 simultaneous settings" means and how it is a 'requirement' that purported LR models of entanglement must conform to.

(Again, an exception for the De Raedt model which has a different set of issues entirely.)My understanding is that a simulation is not, per se, a model. So, a simulation might do what a model can't. If this is incorrect, then please inform me. But if it is incorrect, then what's the point of a simulation -- when a model would suffice?

Here's my thinking about this: suppose we eventually get a simulation of an optical Bell test which reproduces the observed results. And further suppose that this simulation involves only 'locally' produced 'relationships' between counter-propagating optical disturbances. And further suppose that this simulation can only be modelled in a nonseparable (nonfactorizable) way. Then what might that tell us about Bell's ansatz?

ThomasT

Jun16-10, 01:14 PM

I must inform the casual reader: Don’t believe everything you read at PF, especially if the poster defines you as "less sophisticated".No offense DA, but you are 'the casual reader'.

Everything is very simple: If you have one peer reviewed theory (without references or link) stating that 2 + 2 = 5 and a generally accepted and mathematical proven theorem stating 2 + 2 = 4, then one of them must be false.No. Interpreting Bell's theorem (ie., Bell inequalities) is not that simple. If it was then physicists, and logicians, and mathematicians wouldn't still be at odds about the physical meaning of Bell's theorem. But they are, regardless of the fact that those trying to clarify matters are, apparently, a small minority at the present time.

And remember: Bell’s theorem has absolutely nothing to do with "elementary optics" or any other "optics", I repeat – absolutely nothing. Period.Do you think that optical Bell tests (which comprise almost all Bell tests to date) have nothing to do with optics? Even the 'casual reader' will sense that something is wrong with that assessment.

The point is that if optical Bell tests have to do with optics, then any model of those experimental situations must have to do with optics also.

By the way, the fact that I think you're way off in your thinking on this doesn't diminish my admiration for your obvious desire to learn, and your contributions to this thread. Your zealous investigations and often amusing and informative posts are most welcome. And, I still feel like an idiot for overreacting to what I took at the time to be an unnecessarily slanderous post. (Maybe I was just having a bad day. Or, maybe, it isn't within your purview to make statements about other posters' orientations regarding scientific methodology -- unless they've clearly indicated that orientation. The fact is that the correct application of the scientific method sometimes requires deep logical analysis. My view, and the view of many others, is that Bell's 'logical' analysis didn't go deep enough. And, therefore, the common interpretations of Bell's theorem are flawed.)

So, while it's granted that your, and DrC's, and maybe even most physicists, current opinion and expression regarding the physical meaning of violations of BIs is the 'common' view -- consider the possibility that you just might be missing something. You seem to understand that Bell's theorem has nothing to do with optics. I agree. Is that maybe one way of approaching, and understanding, the question of why Bell's ansatz gives incorrect predictions wrt optical Bell tests?

ThomasT

Jun16-10, 01:18 PM

1) You say: "Your argument here does not follow regarding vectors. So what if it is or is not true?", but the claim about this aspect of vectors is factually true. Read this carefully:
http://www.vias.org/physics/bk1_09_05.html
Note: Multiplying vectors from a pool ball collision under 2 different coordinate systems don't just lead to the same answer expressed in a different coordinate system, but an entirely different answer altogether. For this reason such vector operations are generally avoided, using scalar multiplication instead. Yet the Born rule and cos^2(theta) do just that.
2) You say: "I think you are trying to say that if vectors don't commute, then by definition local realism is ruled out.", but they don't commute for pool balls either, when used this way. That doesn't make pool balls not real. Thus the formalism has issues in this respect, not the reality of the pool balls. I even explained why: because given only the product of a vector, there exist no way of -uniquely- defining the particular vectors that went into defining it.

Again, I am missing your point. So what? How does this relate to Bell's Theorem or local realism?
I think that my-wan's point might be related to Christian's formulation of his (Christian's) LR model. Christian's point being that you need an algebra that can suitably represent the rotational invariance of the local beables -- which, in his estimation, Bell didn't represent adequately. According to Christian, Bell's ansatz misrepresents the topology of the experimental situation. Christian has produced 5, or so, papers (for anyone interested, go to arxiv.org and search on Joy Christian) that I know of trying to explain his idea(s). I don't fully understand what he's saying. That is, presently, I'm having difficulty incorporating what Christian is saying into my own 'intuitive' understanding of what I currently regard as the lack of depth in Bell's 'logical' analysis. Although, intuitively, I see a connection. I've read his papers and the discussions on sci.physics.research that Christian participated in a couple of years ago, and the impression I got was that he became frustrated with the lack of knowledge and preparation of those involved. Since then, I've seen nothing about his stuff and don't know if it's still under consideration for publication or not. Maybe he just abandoned it. Maybe someone should send him an email or something to find out what's what. (No, not me!!) After all, the guy is a bona fide mathematical physicist who got his PhD under Shimony -- and he has published some respected peer reviewed stuff. It's very curious to me.) If he came to the conclusion that he was wrong, then wouldn't he be obligated, as a scientist, to say so? I assume that there are physicists and mathematicians here at PF qualified to critique his stuff. So, maybe they will contribute their synopses and critiques.

Anyway, I think my_wan's considerations about vectors are related to this. If I'm wrong, then please let me know why.

ThomasT

Jun16-10, 01:21 PM

If this is a local theory in which any correlations between the two disturbances are explained by properties given to them by the common source, with the disturbances just carrying the same properties along with them as they travel, then this is exactly the sort of theory that Bell examined, and showed that such theories imply certain conclusions about the statistics we find when we measure the "disturbances", the Bell inequalities. Since these inequalities are violated experimentally, this is taken as a falsification of any such local theory which explains correlations in terms of common properties given to the particles by the source. Bell's ansatz depicts the data sets A and B as being statistically independent. And yet we know that separately accumulated data sets produced by a common cause can be statistically dependent -- even when there is no causal dependence between the spacelike separated events that comprise the separate data sets -- precisely because the spacelike separated events have a common cause.

Bell has assumed that statistical dependence implies causal dependence. But we know that it doesn't. So, I ask you, is Bell's purported locality condition, in fact, a locality condition?

Virtually all physicists would agree that the violation of Bell inequalities constitutes a falsification of the kind of theory you describe, assuming you're talking about a purely local theory.
But that isn't what I asked.

What I asked was:

... given a situation in which two disturbances are emitted via a common source and subsequently measured, or a situation in which two disturbances interact and are subsequently measured, then the subsequent measurement of one will allow deductions regarding certain motional properties of the other.Assuming the conservation laws are correct, then are these sorts of deductions allowable?

ThomasT

Jun16-10, 01:30 PM

The EPR conclusion is most certainly not the view which is currently accepted.The EPR conclusion was that qm is not a complete description of the physical reality underlying instrumental phenomena. Are you telling me that this isn't the view of a majority of physicists? If so, how do you know that? Every single physicist that I've talked to personally about this, whether they're familiar with EPR and Bell etc. or not, has said to me that they regard qm, in the sense of a description of the physical reality underlying instrumental phenomena, to be incomplete. This doesn't speak to why it's incomplete, or whether it must be incomplete, but just that it is incomplete. I conjecture that this is the view of a majority of working physicists. Now you can do a representative survey to prove that that conjecture is incorrect. But in the absence of such a survey, then a conjecture to the contrary is also just a conjecture.

That is because the EPR view has been theoretically (Bell) and experimentally (Aspect) rejected. But that was not the case in 1935. At that time, the jury was still out.The EPR view stands as well today as it did in 1935. Either a real physical disturbance with real physical attributes is being emitted by the emitter or it isn't. If it isn't, then, according to a strict, realistic interpretation of the qm formalism, then the reality of B depends on a detection at A, and vice versa. Pretty silly, eh?

What is wrong with this view is that it violates the Heisenberg Uncertainty Principle. Nature does not allow that.There's nothing in the EPR view that violates the uncertainty relations.

EPR says that two particles emitted from a common source are related wrt an applicable conservation law. So that, if the position of particle A is measured, then the position of particle B can be deduced, and if the momentum of particle A is measured, then the momentum of particle B can be deduced.

The uncertainty relations say that for a large number of similar preparations, the deviation from the statistical mean value of the position measurements will be related to the deviation from the statistical mean value of the momentum measurements by the following inequality: (delta q) . (delta p) >= h (where h is Planck's constant, the quantum of action).

As Bohr so eloquently, and yet so, er, cryptically, expressed, the uncertainty relations have no bearing on the relationship between a measurement that WAS made at A and a measurement that WAS NOT made at B.

Bottom line, the EPR argument has nothing to do with the uncertainty relations.

But it has everything to do with the, I conjecture, virtually universal acceptance that qm is an incomplete description of the physical reality underlying instrumental phenomena.

However, just so you don't take what I'm saying the wrong way. I don't see that an unassailably more complete description is possible. Even though there are LR models of entanglement that reproduce the qm predictions, there's absolutely no way to ascertain whether or not they're accurate depictions of an underlying reality. This was Bohr and Heisenberg's, et al., meeting of the minds, so to speak. Qm is, as a probability calculus of instrumental phenomena, as complete as it needs to be, and as complete as it can be without unnecessary and ultimately frustrating speculation regarding what does or doesn't exist or what is or isn't happening in the deep reality underlying instrumental phenomena. The point is that qm, as a mathematical probability calculus, can continue to be progressively developed, and technologically applicable, without any consensus regarding the constituents or behavior of proposed underlying 'elements of reality'.

my_wan

Jun16-10, 01:44 PM

Do you just mean that local properties of the particle are affected by local properties of the detector it comes into contact with? If so, no, this cannot lead to any violations of the Bell inequalities.
I'll go through the computer model (virtual detectors) I used in your question below. I'll also explain the empirical based assumptions used.

Suppose the experimenters each have a choice of three detector settings, and they find that on any trial where they both chose the same detector setting they always got the same measurement outcome.
Naturally you get consistency between experiments, at least statistically. It really would be weird otherwise. But real experiments are limited to 2 setting choices at a time. The 3rd setting is a counterfactual from previous experiments. I doubt you've read the unfair coin example, an unfair coin with a tiny adjuster to set so it match a second 85% of the time, but by defining a 3rd simultaneous setting you are putting very severe non-random constraints on how it relates to 2 other settings. Both completely correlated with 1 and totally uncorrelated with the other, yet expecting this nonrandom choice to match stochastically with both based on statistical profiles pulled from previous experiments without such constraints. Neither classical nor QM mechanism allows this. Only QM is not explicitly time dependent so it's much harder to see the mechanism counterfactually in QM.

Then in a local hidden variables model where you have some variables associated with the particle and some with the detector, the only way to explain this is to suppose the variables associated with the two particles predetermined the result they would give for each of the three detector settings; if there was any probabilistic element to how the variables of the particles interacted with the state of the detector to produce a measurement outcome, then there would be a finite probability that the two experimenters could both choose the same detector setting and get different outcomes. Do you disagree?
Finite, maybe. Though there's at least some reason to believe nature is not finite. But assuming finite, I can also calculate the odds that all the air in the half of the room you are in spontaneously ends up in the other half of the room. The odds of it happening are indeed finite, but I'm not holding my breath just in case.

What do you mean by "assigning" coordinate systems? Coordinate systems are not associated with physical objects, they are just aspects of how we analyze a physical situation by assigning space and time coordinates to different events. Any physical situation can be analyzed using any coordinate system you like, the choice of coordinate system cannot affect your predictions about coordinate-invariant physical facts.
Quiet simple cases exist were quantities are not coordinate-invariant, and a very important one involves basic vector products. Consider:
http://www.vias.org/physics/bk1_09_05.html
The operation's result depends on what coordinate system we use, and since the two versions of R have different lengths (one being zero and the other nonzero), they don't just represent the same answer expressed in two different coordinate systems. Such an operation will never be useful in physics, because experiments show physics works the same regardless of which way we orient the laboratory building! The useful vector operations, such as addition and scalar multiplication, are rotationally invariant, i.e., come out the same regardless of the orientation of the coordinate system.
It states it "will never be useful in physics", yet both the Born rule and Malus Law involve just such a vector product if you presume there is some underlying mechanism. Given just a single vector magnitude it's not even possible to uniquely identify the vectors that it was derived from.

Anyway, your description isn't at all clear, could you come up with a mathematical description of the type of "hv model" you're imagining, rather than a verbal one?
My model is based on a computer model, virtual emitters and detectors.

Assumptions (I'll use photons and polarizations for simplicity):
1) A photon has a single unique default polarization, which is only unique in that upon meeting a polarizer at the same polarization it effectively has a 100% chance of passing that polarizer.
2) The odds that a photon will pass through a polarizer that is offset from that photon default polarization is defined by cos^2(theta), Malus Law.
3) A bit field is set to predefine passage through a polarizer it meats at various settings, with the odds of a bit being predefined as 1 (for passage) determined by a random number generator with a min/max of 0/1 that rolls less than cos^2(theta) when created at the emitter.
4) A random number with a min/max of 0/359.5, rounded to half degree increments, predefines the default polarization at the emitter. These can be rotated with impunity.

For computer modeling a default polarization and a bit field is set. I used 180 bit field, which predefines passage or not for each 1/2 degree over 90 degrees, reversed for every other 90 degrees. The odds that a 10 degree bit, for instance, will be predefined 1 is cos^2(10). Anticorrelated photons are simply flipped 180 degrees, with the same bit field. The photons can be randomly generated and written to a text file. I have lots of improvements to try, but haven't got to it yet.

The formula, when a photon meets a detector is simply (polarizer1 - photon1) and (polarizer2 - photon2) at the other end. Then simply count that many bits into the bit field to see if a detection occurs. No Malus Law used here because it's built into the statistics of the bit field. Detections are returned before comparisons are made between polarizer1 and polarizer2.

This only works to match QM predictions if 1 of the polarizer settings is defined to be 0. Yet you can rotate the photons coming from the emitter with impunity, without effecting the coincidence statistics. So there exist no unique physical state at certain rotations. Neither polarizer directly references the setting of the other polarizer. Only the difference between the photons default polarization and the polarizer setting it actually comes in contact with is used to define detections.

The 0 angle is the biggest issue. You could also add another 719 180 bit fields, for 1/2 degree increments, to undo the 0 degree requirement on one of the detector. This would blow up into a huge, possibly infinite, number of variables in real world conditions, but if quantum computers work as well as expected this shouldn't be an issue.

I'm not happy with this, and have a lot of improvements to try, when I get to it. Including using predefined ranges instead of bit fields, and non-commutative vector rotations in an attempt to remove the coordinate rotations as I change a certain detector setting. I have my doubts about these.

my_wan

Jun16-10, 01:44 PM

Please tell me what theta represents physically.

As I asked already:
How you define theta? Is it angle between polarization axis of polarizer (PBS) and photon so that we have theta1 for H and theta2 for V with condition that theta1=theta2-90?
Or it's something else?

Theta is simply a polarizer setting relative to any arbitrary coordinate system. However, it only leads to valid counterfactual (after the fact) comparisons to route statistics at a 0 setting, but it makes no difference which coordinate choice you use, so long as the photon polarizations are uniformly distributed across the coordinate system.

JesseM

Jun16-10, 01:47 PM

Bell's ansatz depicts the data sets A and B as being statistically independent.
Only when conditioned on the appropriate hidden variables represented by the value of λ. When not conditioned on λ, Bell's argument says there can certainly be a statistical dependence between A and B, i.e. P(A|B) may be different than P(A). Do you disagree?
And yet we know that separately accumulated data sets produced by a common cause can be statistically dependent -- even when there is no causal dependence between the spacelike separated events that comprise the separate data sets -- precisely because the spacelike separated events have a common cause.
Yes, and this was exactly the possibility that Bell was considering! If you don't see this, then you are misunderstanding something very basic about Bell's reasoning. If A and B have a statistical dependence, so P(A|B) is different than P(A), but this dependence is fully explained by a common cause λ, then that implies that P(A|λ) = P(A|λ,B), i.e. there is no statistical dependence when conditioned on λ. That's the very meaning of equation (2) in Bell's original paper, that the statistical dependence which does exist between A and B is completely determined by the state of the hidden variables λ, and so the statistical dependence disappears when conditioned on λ. Again, please tell me if you disagree with this.
Bell has assumed that statistical dependence implies causal dependence.
No, he didn't. He was explicitly considering a case where there is a statistical dependence between A and B but not a causal dependence because the dependence is fully explained by λ. In the simplest type of hidden-variables theory, λ would just represent some set of hidden variables assigned to each particle by the source when the two particles were created, which remained unchanged as they traveled to the detector and which determined their responses to various detector settings.

It would really help if you looked over my lotto card analogy in post #2 here (http://www.physicsforums.com/showthread.php?t=355538)! Your comments suggest you may be confused about the most basic aspects of Bell's proof, so instead of trying to understand the abstract equations in his original paper, I think it would definitely help to look over a concrete model of a situation where we propose a simple hidden-variables theory (involving a common cause, namely the cards being assigned identical 'hidden fruits' by the source) to explain a statistical dependence in observed measurements (the fact that whenever Alice and Bob choose the same box on their respective cards to scratch, they always find the same fruit behind it).
So, I ask you, is Bell's purported locality condition, in fact, a locality condition?
Properly understood, yes it most certainly is.
Virtually all physicists would agree that the violation of Bell inequalities constitutes a falsification of the kind of theory you describe, assuming you're talking about a purely local theory.
But that isn't what I asked.

What I asked was:
given a situation in which two disturbances are emitted via a common source and subsequently measured, or a situation in which two disturbances interact and are subsequently measured, then the subsequent measurement of one will allow deductions regarding certain motional properties of the other.
That paragraph is not even a question, so I would say that's not what you asked. My comment above was in response to your question (which I quoted in my post), "Do you doubt that this is the view of virtually all physicists?" And I understood "this is the view" to refer to your earlier comment "The EPR view was that the element of reality at B determined by a measurement at A wasn't reasonably explained by spooky action at a distance", i.e. specifically the view that correlations in quantum physics could be explained by this sort of common cause, in which case this is not the view of virtually all physicists. On the other hand, if you were just asking whether all physicists would agree there are some situations (outside of QM) where correlations between separated measurements can be explained in terms of common causes, then of course the answer is yes.
Assuming the conservation laws are correct, then are these sorts of deductions allowable?
Here you seem to be asking a new question, and my answer is "yes, in cases where two disturbances are emitted by a common source, observations of one may allow for deductions about the other". And of course, the whole point of Bell's argument was to consider whether or not the observed correlations between measurements on entangled particles could be explained in terms of this sort of "common cause" explanation in a local realist theory. The conclusion he reached was that any such explanation would imply certain Bell inequalities, which are experimentally observed to be violated in quantum experiments.

ThomasT

Jun16-10, 02:12 PM

Only when conditioned on the appropriate hidden variables represented by the value of ?. When not conditioned on λ, Bell's argument says there can certainly be a statistical dependence between A and B, i.e. P(A|B) may be different than P(A). Do you disagree?Does the form, Bell's (2), denote statistical indepencence or doesn't it?

Yes, and this was exactly the possibility that Bell was considering! If you don't see this, then you are misunderstanding something very basic about Bell's reasoning. If A and B have a statistical dependence, so P(A|B) is different than P(A), but this dependence is fully explained by a common cause λ, then that implies that P(A|λ) = P(A|λ,B), i.e. there is no statistical dependence when conditioned on λ. That's the very meaning of equation (2) in Bell's original paper, that the statistical dependence which does exist between A and B is completely determined by the state of the hidden variables λ, and so the statistical dependence disappears when conditioned on λ. Again, please tell me if you disagree with this.It seems that you're saying that if the disturbances incident on a and b have a common cause, then the results, A and B, can't be statistically dependent. Is that what you're saying?

... the whole point of Bell's argument was to consider whether or not the observed correlations between measurements on entangled particles could be explained in terms of this sort of "common cause" explanation in a local realist theory. The conclusion he reached was that any such explanation would imply certain Bell inequalities, which are experimentally observed to be violated in quantum experiments.Yes, well, we disagree then on the depth of Bell's analysis, or simply on the way his analysis and result is communicated. The problem is that viable LR models of entanglement exist. Would you care to look at one and refute it -- either wrt to its purported locality or reality or agreement with qm predictions?

DrChinese

Jun16-10, 02:12 PM

Quiet simple cases exist were quantities are not coordinate-invariant, and a very important one involves basic vector products. Consider:
http://www.vias.org/physics/bk1_09_05.html

We are not discussing whether 2 measurements commute or not. Or two vector operations. We are discussing whether 2 measurements on separated particles have various attributes. So this statement and the related example are completely meaningless in the context of this discussion. I really wish you would stop mentioning it as it leads us nowhere useful.

We understand that your model lacks rotational invariance in that it works with a reference angle of 0 and not at others. And no, it is not OK that you can define any angle as 0 to make it appear to work. Your "trick" works because you are effectively communicating Alice's setting to Bob or vice versa. Whether or not vectors add in all coordinate systems does not change this point in any way.

ThomasT

Jun16-10, 02:20 PM

JesseM, do you think that most physicists equate EPR's spooky action at a distance with quantum correlations?

JesseM

Jun16-10, 02:29 PM

Does the form, Bell's (2), denote statistical indepencence or doesn't it?
You haven't defined what you mean by "statistical independence". I think I made clear already that two variables can be statistically dependent in their marginal probabilities but statistically independent when conditioned on other variables.

Could you please answer the questions I ask you in my posts, like this one?
When not conditioned on λ, Bell's argument says there can certainly be a statistical dependence between A and B, i.e. P(A|B) may be different than P(A). Do you disagree?
It seems that you're saying that if the disturbances incident on a and b have a common cause, then the results, A and B, can't be statistically dependent. Is that what you're saying?
If the common cause is the complete explanation for the statistical dependence in the marginal probabilities, then when conditioned on the common cause they wouldn't be statistically dependent (i.e. if you already know precisely what properties were given to system A by the common cause which also gave some related properties to system B, then learning about a later measurement on system B will tell you nothing new about what you are likely to see when you measure system A). Do you disagree with that? If you do disagree, can you think of any classical examples where we have correlations that are completely explained by a common cause, yet where the above would not be true?

Of course you could have a more complicated situation where there were multiple common causes, and perhaps also some direct causal influences between A and B. But then the given common cause wouldn't be the complete explanation for the correlation observed between measurements on A and B.
Yes, well, we disagree then on the depth of Bell's analysis.
OK, but do you want to engage in an actual substantive discussion about the details of his analysis and whether his assumptions are justified? If so then I would ask that you please answer my direct questions to you, and also address the examples and arguments I present like the lotto card analogy in post #2 here (http://www.physicsforums.com/showthread.php?t=355538) or the argument I made about conditioning on complete past light cones, and what this would imply in both deterministic and probabilistic theories, in this post (http://www.physicsforums.com/showpost.php?p=2753742&postcount=63). Of course there's no need to respond to all of this immediately, but if you are intellectually serious about exploring the truth and not just trying to engage in rhetorical denunciations, then I'd like some assurances that you do plan to address my questions and arguments seriously if we're going to keep discussing this stuff.

DrChinese

Jun16-10, 02:40 PM

Does the form, Bell's (2), denote statistical indepencence or doesn't it?

It seems that you're saying that if the disturbances incident on a and b have a common cause, then the results, A and B, can't be statistically dependent. Is that what you're saying?

A common cause is assumed. Statistical correlation of A and B is assumed as well. Even perfect correlations can be explained, all within Bell (2). There is no problem with any of this. This is simply a restatement of what EPR was trying to say.

The problem is getting this to agree to the QM expectation values. There are a variety of constraints in this as my_wan has discovered. Under scenario a), the Malus relationship does not hold except at privileged angle settings. Under scenario b), an infinite or at least very large amount of data must be encoded. And both of these scenarios are BEFORE we come to terms with a Bell Inequality.

So my point is that for everyone attacking Bell (2), you are coming at it backwards. It is a generic statement, and does not provide any particular insight into the EPR issue at all. Any way you want to express the statement "The result A does not depend on setting b, and vice versa" would work here. Bell calls this requirement essential because it is his version of locality. (Or call it "local causality" if that is a preferable label.) Bell assumed his version would not cause anybody to have a cow, that it would be accepted as a mathematical version of the "...A not dependent on b..." statement. So whether or not there is a statistical connection, that really makes no difference. Since this is assumed by everyone. So Bell (2) is not an expression of the independence of statistical correlations A and B. It has to do with the independence of A and b, and B and a. If your model has A dependent on b, then it fails test #1. Because it is not local.

ThomasT

Jun16-10, 02:41 PM

You haven't defined what you mean by "statistical independence". Factorability of the joint probability. The product of the probabilities of A and B. Isn't that the definition of statistical independence?

DrChinese

Jun16-10, 02:43 PM

Factorability of the joint probability. The product of the probabilities of A and B. Isn't that the definition of statistical independence?

a and b are different than A and B. A and B do not need to be independent.

ThomasT

Jun16-10, 02:51 PM

a and b are different than A and B. A and B do not need to be independent.Exactly. But that's how Bell's model denotes them. In Bell's model, the data sets A and B are independent.

ThomasT

Jun16-10, 02:56 PM

So Bell (2) is not an expression of the independence of statistical correlations A and B.Are you sure about that? I think it's been demonstrated that Bell's ansatz reduces to the probability definition of statistical independence. If you think otherwise then maybe you should revisit the posts in this and other threads dealing with that.

ThomasT

Jun16-10, 02:59 PM

DrChinese

Jun16-10, 03:28 PM

Are you sure about that? I think it's been demonstrated that Bell's ansatz reduces to the probability definition of statistical independence. If you think otherwise then maybe you should revisit the posts in this and other threads dealing with that.

I have stated many times: A and b, not A and B. The result A is definitely correlates with B. The question is: does A change with b? It shouldn't in a local world. In other words: if Alice's result changes when spacelike separated Bob moves his measurement dial, then there is spooky action at a distance. I know you will agree with that statement.

From the EPR conclusion: "This makes the reality of P and Q depend upon the process of measurement carried out on the first system in any way. No reasonable definition of reality could be expected to permit this." They are saying the same thing as Bell (2).

And in Bell's words: "The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b." Which he then presents in his form (2). There is no restriction on the correlation of A and B in this.

So the data points for A with setting a come out the same regardless of the value of b. Of course the correlation of A and B may change with a change in a or b. Bell (2) is not saying anything about that. If you doubt this, just re-read what Bell said above. Or what EPR said.

DrChinese

Jun16-10, 03:37 PM

DrC, the view of many physicists, including past discussions I've had here at PF, indicate that Bell's idea was that if the data sets A and B were statistically dependent, then they must be causally dependent. Of course, we know this is wrong.

There is nothing wrong with causality in this situation. I mean, the entire point is that the pairs are clones (or anti-clones) of each other because they were created at the same time. The question is whether there is observer independence in the outcomes. Whether the reality of P and Q are independent of what goes on elsewhere. Whether the result A is dependent on setting b.

And as far as anyone knows, this is "possible" within constraints when you consider Bell (2) by itself. This has been demonstrated by who knows how many local realistic papers. But of course all this falls apart when you add the realism requirement. EPR said that it was possible to constrain reality to just the number of observables that could be predicted simultaneously (1), but that was too restrictive (in their opinion). So by then applying the less restrictive definition of reality which they claim as reasonable (2 or more), Bell obtains his famous result.

DrChinese

Jun16-10, 03:41 PM

Exactly. But that's how Bell's model denotes them. In Bell's model, the data sets A and B are independent.

No, that is my point. You have misinterpreted Bell (2). How many times must I repeat Bell:

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

Yes, I am pretty good with ^V. And there can be a connection between A and B. In fact, there has to be to have an element of reality according to EPR. It was assumed that A and B would be perfectly correlated when a=b. That is how you predict the outcome of one without first disturbing it.

ThomasT

Jun16-10, 03:54 PM

I have stated many times: A and b, not A and B. The result A is definitely correlates with B. The question is: does A change with b? It shouldn't in a local world. In other words: if Alice's result changes when spacelike separated Bob moves his measurement dial, then there is spooky action at a distance. I know you will agree with that statement.

From the EPR conclusion: "This makes the reality of P and Q depend upon the process of measurement carried out on the first system in any way. No reasonable definition of reality could be expected to permit this." They are saying the same thing as Bell (2).

And in Bell's words: "The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b." Which he then presents in his form (2). There is no restriction on the correlation of A and B in this.

So the data points for A with setting a come out the same regardless of the value of b. Of course the correlation of A and B may change with a change in a or b. Bell (2) is not saying anything about that. If you doubt this, just re-read what Bell said above. Or what EPR said.You miss the point. Bell's ansatz denotes that the data sets A and B are statistically independent.

DrChinese

Jun16-10, 04:05 PM

You miss the point. Bell's ansatz denotes that the data sets A and B are statistically independent.

No. They aren't independent. Bell never mentions that point.

ThomasT

Jun16-10, 04:20 PM

No, that is my point. You have misinterpreted Bell (2). How many times must I repeat Bell:

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

"The vital assumption is that the result B for particle 2 does not depend on the setting a, of the magnet for particle 1, nor A on b."

Yes, I am pretty good with ^V. And there can be a connection between A and B. In fact, there has to be to have an element of reality according to EPR. It was assumed that A and B would be perfectly correlated when a=b. That is how you predict the outcome of one without first disturbing it.You can repeat anything you want as much as you want. The fact is that Bell's model says that the data sets A and B are independent.

This point is important, so if you dispute it, then you'll have to demonstrate why.

And yet we know from the experimental designs that the data sets, A and B, aren't independent. And we also know that this statistical dependence doesn't have to have anything to do with a causal connection between A and B or A and b or B and a or B and A. A local common cause is sufficient to explain the statistical dependencies that are observed. Period. If you think that Bell's theorem proves that there is no local common cause to the correlations, then you're just not thinking about this like a physicist. In fact, I'll submit this: many physicists, maybe even most, having neither the time nor the inclination to delve very deeply into Bell's theorem, have accepted the common view that all local realistic theories of entanglement are impossible. What do they care. It has nothing to do with their research or their experiments or their grants. Period.

Of course, imo, they're wrong. But so what? It doesn't affect their programs one bit. So I reject your appeals to 'a majority of physicists' think this or that. I've issued you a challenge and asked you to clarify what you mean by your 'requirement'. Please address that issue. It's most difficult to learn anything from obfuscations.

ThomasT

Jun16-10, 04:30 PM

No. They aren't independent. Bell never mentions that point.It doesn't matter if he 'mentions' it. It's there, in the model.

On the one hand, in some posts, you say that it doesn't matter if Bell says this or that. And on the other hand, when it suits your purpose, you appeal to what Bell did or didn't say.

Well, I'm telling you now, the arguments that have been presented have nothing to do with what Bell did or didn't say about any of his formal presentations. All we're concerned with are the formalisms. Period.

So, you'd better forget about what 'most' physicists say or believe, and what Bell said or believed, and just look at what he presented as a model of a certain experimental situation. It happens to be wrong. And we're trying to determine exactly what's wrong with it.

DrChinese

Jun16-10, 04:53 PM

It doesn't matter if he 'mentions' it. It's there, in the model.

On the one hand, in some posts, you say that it doesn't matter if Bell says this or that. And on the other hand, when it suits your purpose, you appeal to what Bell did or didn't say.

Well, I'm telling you now, the arguments that have been presented have nothing to do with what Bell did or didn't say about any of his formal presentations. All we're concerned with are the formalisms. Period.

So, you'd better forget about what 'most' physicists say or believe, and what Bell said or believed, and just look at what he presented as a model of a certain experimental situation. It happens to be wrong. And we're trying to determine exactly what's wrong with it.

It would be nice if you would mention that it is the 1965 paper which I quote, not his later writings. And it is that same paper which is usually referenced by authors, not his later writings. There has never been much question about the respect I give that paper.

Now, after saying the words, Bell presents the mathematical form which is the SAME as the words. There is no question about this to most anyone. But I see that for many, this can be a bit confusing. So I will point out EXACTLY what his (2) says:

There is a result function for Alice, A(a, lambda), which has no dependence on b. There is a result function for Bob, B(b, lambda), which has no dependence on a. These share a common dependence on a set of hidden variables or hidden functions. I believe you can see this point for yourself. And there is the correlation function, P(a, b) which we would expect to match the quantum expectation value, which is Bell's (3). For a=b, the result is -1 for the singlet state. I believe you can plainly see this point.

Now, where is the above any different than what I have told you: Bob's result B is independent of Alice's setting a. But there is definitely a correlation between A and B, which is in fact -1 when a=b.

I really don't know how to make it much clearer. Show me any respected author who says that Bell (2) is a requirement that outcomes A and B are statistically unrelated. Or if the author is not respected, at least give me a funny quote.

DrChinese

Jun16-10, 05:04 PM

And yet we know from the experimental designs that the data sets, A and B, aren't independent. And we also know that this statistical dependence doesn't have to have anything to do with a causal connection between A and B or A and b or B and a or B and A. A local common cause is sufficient to explain the statistical dependencies that are observed. Period. If you think that Bell's theorem proves that there is no local common cause to the correlations, then you're just not thinking about this like a physicist. In fact, I'll submit this: many physicists, maybe even most, having neither the time nor the inclination to delve very deeply into Bell's theorem, have accepted the common view that all local realistic theories of entanglement are impossible. What do they care. It has nothing to do with their research or their experiments or their grants. Period.

Of course, imo, they're wrong. But so what? It doesn't affect their programs one bit. So I reject your appeals to 'a majority of physicists' think this or that. I've issued you a challenge and asked you to clarify what you mean by your 'requirement'. Please address that issue. It's most difficult to learn anything from obfuscations.

OK, you are going off the deep end again. There are a lot of physicists out there who DO follow Bell tests very closely, and it is these that I generally quote. Zeilinger and Aspect being just 2, but there are a lot of very well respected scientists out there - Gisin, Weihs, Mermin, Greenberger, many many more. I am not invoking the authority of those who don't know the field. So I would recommend you cease your diatribe, it really reflects poorly. These guys know their stuff, theory and history. And every day they are dreaming up and running experiments that would be impossible in a local realistic world. So please, don't speak like a fool.

Second, as I have repeatedly told you, there IS a statistical relationship between the results of Alice and Bob. And that IS effectively due to a common cause or whatever you want to call it. I call it a conservation law. Also, a local connection MIGHT be able to follow the requirements of Bell (2) and Bell (3) but cannot survive the Bell final result (which rules out all local realistic theories).

And third, it is not my requirements which are in question here. It is the requirement of EPR, as I quoted you earlier, that there be 2 or more simultaneous elements of reality. In Bell's case, there are 3: a, b and c.

ThomasT

Jun16-10, 05:07 PM

It would be nice if you would mention that it is the 1965 paper which I quote, not his later writings. And it is that same paper which is usually referenced by authors, not his later writings. There has never been much question about the respect I give that paper.

Now, after saying the words, Bell presents the mathematical form which is the SAME as the words. There is no question about this to most anyone. But I see that for many, this can be a bit confusing. So I will point out EXACTLY what his (2) says:

There is a result function for Alice, A(a, lambda), which has no dependence on b. There is a result function for Bob, B(b, lambda), which has no dependence on a. These share a common dependence on a set of hidden variables or hidden functions. I believe you can see this point for yourself. And there is the correlation function, P(a, b) which we would expect to match the quantum expectation value, which is Bell's (3). For a=b, the result is -1 for the singlet state. I believe you can plainly see this point.

Now, where is the above any different than what I have told you: Bob's result B is independent of Alice's setting a. But there is definitely a correlation between A and B, which is in fact -1 when a=b.

I really don't know how to make it much clearer. Show me any respected author who says that Bell (2) is a requirement that outcomes A and B are statistically unrelated. Or if the author is not respected, at least give me a funny quote.The 'form' of Bell's (2) says, explicitly, that the data sets A and B are independent.

Look, I don't care about this right now. I already understand it. I want you to tell me what your LR 'requirement" means. Please do that. Thank you.

ThomasT

Jun16-10, 05:15 PM

I'm waiting ...

ThomasT

Jun16-10, 05:18 PM

Look, I have some other stuff to do soon. I want the 'casual reader' to understand that you're unable to refute a simple LR model of entanglement.

There's no need to be alarmed. It will only hurt for a second or two.

DrChinese

Jun16-10, 05:39 PM

I want the 'casual reader' to understand that you're unable to refute a simple LR model of entanglement.

You are proof of the existence of many worlds. :eek:

ThomasT, you are really messing yourself up with this one. I appreciate that you have convinced yourself that you have brilliantly deduced the "flaws" in Bell that no one else has had the keen insight to spot. But I don't need to prove Bell, that has already been done X times over. And you have not put forth ANYTHING, much less a candidate to refute.

Any casual reader who mistakenly takes you as an authority on this subject will end up disappointed in the end. But please, continue your idle boasting if it makes you feel better.

DrChinese

Jun16-10, 05:40 PM

I'm waiting ...

And if you are holding your breath, you will eventually turn blue. I am pretty certain of that.

:bugeye:

JesseM

Jun16-10, 06:54 PM

Factorability of the joint probability. The product of the probabilities of A and B. Isn't that the definition of statistical independence?
Again, you're ignoring the issue of whether the joint probability is conditioned on some other variable λ. Do you agree it's possible to have a situation where P(AB) is not equal to P(A)*P(B), and yet P(AB|λ)=P(A|λ)*P(B|λ)? (and that this situation was exactly the type considered by Bell?) In this situation do you think there is a single correct answer to whether A and B are "statistically independent" or not? If so, what is that answer?

billschnieder

Jun16-10, 11:28 PM

Again, you're ignoring the issue of whether the joint probability is conditioned on some other variable λ. Do you agree it's possible to have a situation where P(AB) is not equal to P(A)*P(B), and yet P(AB|λ)=P(A|λ)*P(B|λ)? (and that this situation was exactly the type considered by Bell?) In this situation do you think there is a single correct answer to whether A and B are "statistically independent" or not? If so, what is that answer?

1) Is Bell's equation (2) specifying a conditional, or a marginal probability?
2) According to Bell's equation (2), is logical dependence between outcomes A and B allowed or not ?

The answers to the above two questions should shatter the smokescreen in the above response.

zonde

Jun17-10, 05:14 AM

Theta is simply a polarizer setting relative to any arbitrary coordinate system. However, it only leads to valid counterfactual (after the fact) comparisons to route statistics at a 0 setting, but it makes no difference which coordinate choice you use, so long as the photon polarizations are uniformly distributed across the coordinate system.
Please do not escape my question.
Question is about the case when we do not have uniform distribution of polarization across the coordinate system but rather when we have only two orthogonal polarizations H and V.
That was the case you were describing with your formulas.

I will repeat my question. What theta represents physically when we talk about orientation of polarizer and photon beam consisting of photons with two orthogonal polarizations (H and V)?

zonde

Jun17-10, 05:56 AM

Imagine that for a Bell Inequality, you look at some group of observations. The local realistic expectation is different from the QM expectation by a few %. Perhaps 30% versus 25% or something like that.

On the other hand, GHZ essentially makes a prediction of Heads for LR, and Tails for QM every time. You essentially NEVER get a Heads in an actual experiment, every event is Tails. So you don't have to ask whether the sample is fair. There can be no bias - unless Heads events are per se not detectible, but how could that be? There are no Tails events ever predicted according to Realism.
This is incorrect interpretations of GHZ theorem.
What Bell basically says is that cos(a-b) is not factorizable for all angles (even if it's factorizable when a-b=0,Pi and some other cases).
What GHZ says is that cos(a+b+c+d) is not factorizable even when a+b+c+d=0,Pi.
So there is no prediction at all in GHZ for (non-contextual) local realism.

So using a different attack on Local Realism, you get the same results: Local Realism is ruled out. Now again, there is a slight split here are there are scientists who conclude from GHZ that Realism (non-contextuality) is excluded in all forms. And there are others who restrict this conclusion only to Local Realism.
No it is not Local Realism that is ruled out but only non-contextual Local Realism that is ruled out.
And there is no need to put non-contextuality in parentheses after Realism because Realism is not restricted to non-contextuality only. Even more Realism is always more or less contextual and non-contextuality is only approximation of reality.

JesseM

Jun17-10, 07:59 AM

1) Is Bell's equation (2) specifying a conditional, or a marginal probability?
Conditional.
2) According to Bell's equation (2), is logical dependence between outcomes A and B allowed or not ?
There can be a logical dependence in their marginal probabilities, but not in conditional probabilities conditioned on λ.
The answers to the above two questions should shatter the smokescreen in the above response.
No smokescreen, distinguishing the two is relevant to my discussion with ThomasT because he seems to be conflating the two, pointing to the example where two variables are correlated in their marginal probabilities due to a common cause in their past, and talking as though Bell's equation (2) was somehow saying this is impossible.

DrChinese

Jun17-10, 09:43 AM

So there is no prediction at all in GHZ for (non-contextual) local realism.

No it is not Local Realism that is ruled out but only non-contextual Local Realism that is ruled out. ... And there is no need to put non-contextuality in parentheses after Realism because Realism is not restricted to non-contextuality only. Even more Realism is always more or less contextual and non-contextuality is only approximation of reality.

Non-contextual = Realistic

Now some folks quibble about the difference, but the difference is mostly a matter of your exact definition - which does vary a bit from author to author. So I acknowledge that. However, I think EPR covers the definition in a manner most accept:

"One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive. Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted.... No reasonable definition of reality could be expected to permit this."

In other words: You do not need to demonstrate that the elements of reality are SIMULTANEOUSLY predictable, in their view of a reasonable definition. Therefore, they only need to be predictable one at a time. All counterfactual observables are in fact elements of reality under THIS definition. That is because they can be individually predicted with certainty. So EPR is asserting the simultaneous realism of counterfactual observables as long as those observables qualify as "elements of reality". That is also the definition Bell used for his a, b and c. These qualify as being "real" by the EPR definition above. Bell introduces the counterfactual c as being on an equal basis with the observable a and b after his (14). See EPR and Bell as references.

As to GHZ:

"Surprisingly, in 1989 it was shown by Greenberger, Horne and Zeilinger
(GHZ) that for certain three- and four-particle states a conflict with
local realism arises even for perfect correlations. That is, even for those cases
where, based on the measurement on N −1 of the particles, the result of the
measurement on particle N can be predicted with certainty. Local realism
and quantum mechanics here both make definite but completely opposite
predictions.

"To show how the quantum predictions of GHZ states are in stronger conflict
with local realism than the conflict for two-particle states as implied by Bell’s
inequalities, let us consider the following three-photon GHZ state:

"We now analyze the implications of these predictions from the point of
view of local realism. First, note that the predictions are independent of the
spatial separation of the photons and independent of the relative time order
of the measurements. Let us thus consider the experiment to be performed
such that the three measurements are performed simultaneously in a given
reference frame, say, for conceptual simplicity, in the reference frame of the
source. Thus we can employ the notion of Einstein locality, which implies
that no information can travel faster than the speed of light. Hence the
specific measurement result obtained for any photon must not depend on
which specific measurement is performed simultaneously on the other two
or on the outcome of these measurements. The only way then to explain
from a local realistic point of view the perfect correlations discussed above
is to assume that each photon carries elements of reality for both x and y
measurements considered and that these elements of reality determine the
specific individual measurement result. Calling these elements of reality...

"In the case of Bell’s inequalities for two photons the conflict between local
realism and quantum physics arises for statistical predictions of the theory;
but for three entangled particles the conflict arises even for the definite predictions."

Zeilinger talking about GHZ in:
http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf

So GHZ does show that Local Realism makes specific predictions which are flat out contradicted by both QM and experiment.

DevilsAvocado

Jun17-10, 09:50 AM

... A local common cause is sufficient to explain the statistical dependencies that are observed. Period. If you think that Bell's theorem proves that there is no local common cause to the correlations, then you're just not thinking about this like a physicist. ...

A friendly advice: Hold on a couple of days with this kind of statements. I can guarantee you that you will regret this, as much as some other posts, and make you feel even worse than in #750 (http://www.physicsforums.com/showpost.php?p=2764087&postcount=750).

I’m currently working on compiling "new" (never discussed on PF) material from John Bell himself. If you should decide to continue along this line, you’re left with a catastrophic choice; John Bell’s own mathematical conclusion on Bell’s theorem is wrong, and ThomasT has on his own obtained the correct mathematical conclusion on Bell’s theorem - or the other way around.

If you make the wrong choice, your "sophisticated status" will be considered as hurt as the "Norwegian Blue Parrot" by all, from the casual reader to a real professor. I’m sorry, but this will be a fact.

After I’ve finished and posted this work, I’ll answer any posts from #727 and forward.

billschnieder

Jun17-10, 10:36 AM

1) Is Bell's equation (2) specifying a conditional, or a marginal probability?
Conditional.

Have you ever heard of marginalization? If you marginalize a probability distribution with respect to λ, the resulting probability is no longer dependent on λ. It is a marginal probability. So Let me ask you the question again, so that you have an opportunity to correct yourself. Maybe you mispoke.

1) Is Bell's equation(2) specifying a conditional or a margnial probability?

If you insist it is conditional, please tell us on what it is conditioned. λ?

2) According to Bell's equation (2), is logical dependence between outcomes A and B allowed or not ?
There can be a logical dependence in their marginal probabilities, but not in conditional probabilities conditioned on λ.
You answered above that Bell's equation (2) specifies a conditional probability. The question is, in that "conditional probability" specified by Bell's equation (2) (according to you), is logical dependence between outcomes A and B allowed or not. From the part of your answer underlined above, I can surmise that you are saying logical dependence is not allowed between outcomes A and B in the probability expressed in Bell's equation (2), since you have already answered above that Bell's equation(2) specifies a conditional probability.

So then as a follow up question.

3) Is logical dependence between outcomes A and B allowed in Bell's inequalities which are derived from equation (2).

Your answers so far:

1: Bell's equation(2) expresses a conditional probability
2: Logical dependence between A and B is not allowed in the probability expressed in Bells equation (2)
3: ???? -- waiting for an answer ---

You are free to go back and revise any of your previous answers. My intention here is not to trap you but to make you understand the issue being discussed here. ThomasT, correct me if I'm misrepresenting your position, but isn't this relevant to the question you asked?

billschnieder

Jun17-10, 10:58 AM

Non-contextual = Realistic
Not according to EPR, it isn't.

All counterfactual observables are in fact elements of reality under THIS definition.
Contextual observables are also elements of reality under THIS definition

Can you see the moon if you are not looking at it? Just because you can not see the moon when you are not looking at it, does not mean the moon does not exist when no one is looking at it.

JesseM

Jun17-10, 12:10 PM

Have you ever heard of marginalization?
Hadn't heard that particular term, no. Wikipedia defines it in the second paragraph here (http://en.wikipedia.org/wiki/Conditional_probability), it's just finding the marginal probability of one variable by summing over the joint probabilities for all possible values of another variable (so if B can take two values B1 and B2, we could find the marginal probability of A by calculating P(A)=P(A, B1) + P(A, B2)).
If you marginalize a probability distribution with respect to λ, the resulting probability is no longer dependent on λ. It is a marginal probability.
Yes, I wasn't familiar with the terminology but I'm familiar with the concept, in fact I referred to the same idea in many previous posts addressed to you, that we could find the marginal probabilities of A and B by summing over all possible values of the hidden variable (the last section of this post (http://www.physicsforums.com/showthread.php?p=2706689), for example).
So Let me ask you the question again, so that you have an opportunity to correct yourself. Maybe you mispoke.

1) Is Bell's equation(2) specifying a conditional or a margnial probability?
Bell's equation (2) involves such a sum, so the summation itself (on the right side of the equation) is a sum over various conditional probabilities, but result of the sum (on the left side of the equation) is a marginal probability. In case you want to quibble with this, I suppose I should point out that strictly speaking, in equation (2) Bell actually assumes the measurement outcomes are determined with probability 1 by the value of λ, so instead of writing P(A|a,λ) he just writes A(a,λ), but this is just a special case of a conditional probability where the probability of any specific outcome for A will always be 0 or 1 (and in later proofs he did write it explicitly as a sum over conditional probabilities, as with equation (13) on p. 244 of Speakable and Unspeakable in Quantum Mechanics (http://books.google.com/books?id=FGnnHxh2YtQC&lpg=PA243&ots=3rRcOQrpT3&dq=%22Invoking%20local%20causality%2C%20and%20the% 20assumed%20completeness%22&pg=PA244#v=onepage&q=%22Invoking%20local%20causality,%20and%20the%20a ssumed%20completeness%22&f=false) which plays the same role as equation (2) in his original paper)
You answered above that Bell's equation (2) specifies a conditional probability. The question is, in that "conditional probability" specified by Bell's equation (2) (according to you), is logical dependence between outcomes A and B allowed or not. From the part of your answer underlined above, I can surmise that you are saying logical dependence is not allowed between outcomes A and B in the probability expressed in Bell's equation (2), since you have already answered above that Bell's equation(2) specifies a conditional probability.
I'll amend that to say that on the right side there can be no logical dependence since this side deals with A and B conditioned on λ, but on the left side there can. Remember, ThomasT's original argument concerned whether or not Bell was justified in treating the joint probability as the product of two individual probabilities, which doesn't even involve marginalization, it just involves the sort of equation that you disputed in your first thread on this subject (http://www.physicsforums.com/showthread.php?t=399795), P(AB|H)=P(A|H)*P(B|H) (or equation (10) on p. 243 of Speakable and Unspeakable (http://books.google.com/books?id=FGnnHxh2YtQC&lpg=PA243&ots=3rRcOQrpT3&dq=%22Invoking%20local%20causality%2C%20and%20the% 20assumed%20completeness%22&pg=PA243#v=onepage&q=%22Invoking%20local%20causality,%20and%20the%20a ssumed%20completeness%22&f=false)).
So then as a follow up question.

3) Is logical dependence between outcomes A and B allowed in Bell's inequalities which are derived from equation (2).
When A and B are not conditioned on λ, as on the left side of (2) or in the Bell inequalities themselves, then yes there can be a logical dependence between them according to Bell's argument. Do you disagree?

GeorgCantor

Jun17-10, 12:15 PM

Can you see the moon if you are not looking at it? Just because you can not see the moon when you are not looking at it, does not mean the moon does not exist when no one is looking at it.

Can you see the fullerene molecule when you are not looking at it? Or if i shoot c60 molecules in a quantum eraser experiment and 'erase' the information about the which-path i have obtained, would the resultant interference pattern mean the complex-structure 60-atom molecule was there?

DevilsAvocado

Jun17-10, 12:18 PM

Sorry for bumping in, I have other "things" to complete, but this is a basic no-brainer, thus to avoid extensive discussions whether the moon is real or not:
So then as a follow up question.

3) Is logical dependence between outcomes A and B allowed in Bell's inequalities which are derived from equation (2).

Yes and No, according to QM predictions and experiments. It depends on the relative angle. If measured parallel or perpendicular, the outcome is strongly logical correlated. In any other case, it’s statistically correlated thru QM predictions cos2(A-B).

Every outcome on every angle is perfectly random, with exception for parallel and perpendicular, where the outcome for A must be perfectly correlated to B.

That’s it. Don’t make things harder than they are by "probability enigmas"...

"Everything should be made as simple as possible, but not simpler" -- Albert Einstein

Edit: Ops, Jesse has already answered...

DrChinese

Jun17-10, 01:07 PM

1. Not according to EPR, it isn't.

2. Contextual observables are also elements of reality under THIS definition

3. Can you see the moon if you are not looking at it? Just because you can not see the moon when you are not looking at it, does not mean the moon does not exist when no one is looking at it.

1. I gave you the quote from EPR. Perhaps you have a quote that says something different that you might post. Oh, I mean from EPR.

2. The definition from EPR is that it can be predicted with certainty. If it is contextual and can be predicted with certainty, that would make it real per EPR.

3. You must be kidding, since that was the title of the Mermin piece. The conclusion is that the moon is most definitely NOT there when you are not looking at it. Of course, the existence of the moon is just an analogy. We are actually discussing elements of reality.

billschnieder

Jun17-10, 05:06 PM

1. I gave you the quote from EPR. Perhaps you have a quote that says something different that you might post. Oh, I mean from EPR.

2. The definition from EPR is that it can be predicted with certainty. If it is contextual and can be predicted with certainty, that would make it real per EPR.

3. You must be kidding, since that was the title of the Mermin piece. The conclusion is that the moon is most definitely NOT there when you are not looking at it. Of course, the existence of the moon is just an analogy. We are actually discussing elements of reality.

1) I don't need any other quote. The quote you presented is consistent with what I said. If you think it is not, explain why it is not.

2) Again if you think a contextual element of reality can not be predicted with certainty, explain why you would believe such a ridiculous thing.

3) So what Mermin if said it? What matters is whether it is true or not. It is impossible to see the moon when you are not looking at it. Seeing the moon is contextual. It involves your eyes and the moon. Are you going to tell me next that "seeing the moon" is not real unless it is independent of any eyes? Are you going to tell me next that because it is impossible to see the moon without looking at it, there are no elements of reality which underlie that observation? Are you going to tell me that given all complete knowledge of all those hidden elements of reality, it will be impossible to predict if a hypothetical person in that same situation will see the moon or not?

Certainly you do not ascribe such a naive definiton of realism to EPR since they meant no such thing.
If without in any way disturbing a system, we can predict with certainty the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity

Please show me where EPR says contextual observables can not be predicted with certainty. In fact they argue aganist this mindset when they say:

One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive. Indeed one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted. On this point of view, since either one or the other, but not both simultaneously, of the quantities P and Q can be predicted, they are not simultaneously real. This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.

DrChinese

Jun17-10, 05:34 PM

1) I don't need any other quote. The quote you presented is consistent with what I said. If you think it is not, explain why it is not.

2) Again if you think a contextual element of reality can not be predicted with certainty, explain why you would believe such a ridiculous thing.

3) So what Mermin if said it? What matters is whether it is true or not. It is impossible to see the moon when you are not looking at it. Seeing the moon is contextual. It involves your eyes and the moon. Are you going to tell me next that "seeing the moon" is not real unless it is independent of any eyes? Are you going to tell me next that because it is impossible to see the moon without looking at it, there are no elements of reality which underlie that observation? Are you going to tell me that given all complete knowledge of all those hidden elements of reality, it will be impossible to predict if a hypothetical person in that same situation will see the moon or not?

Certainly you do not ascribe such a naive definiton of realism to EPR since they meant no such thing.

1) I gave it because it supports my position. Nice that you can turn that around with the wave of a... nothing!

2) Well of course it can be. For example, I measure Alice at 0 degrees. I know Bob's result at 0 degrees with certainty. That is an element of reality, and it is contextual (observer dependent). Duh. Perhaps you might read what I say next time.

3) The moon is NOT there when we are not looking, and of course this is an analogy as I keep saying. How many ways can I say it, and how many famous people need to say it before you accept it as a legitimate position (regardless of whether you agree with it)? There is no hypothetical observer, unless we live in a non-local universe. Which perhaps we do.

As to EPR not meaning it that way: Einstein SPECIFICALLY said he meant it that way. Do I need to produce the quote? That is why Mermin titled his article as he did.

You know, on a side note: It really makes me laff to see folks like you dismiss towering figures of modern science without so much as one iota of support for your position, other than YOU say it. I can't recall a single useful reference or quote from you. :tongue:

ThomasT

Jun17-10, 09:10 PM

In this situation do you think there is a single correct answer to whether A and B are "statistically independent" or not?Ok, here's the way I'm thinking about it today. Wrt the experimental situation, there's a single correct answer, the data sets A and B are not independent. This is because of the data matching via time stamping. Matching the data in this way is based on the assumption of a local common cause. The fact that data matching via time stamping does produce (or reveal) entanglement correlations would, then, seem to support the idea that a locally produced relationship between counter-propagating disturbances is a necessary condition and the root cause of the correlations between joint detection and angular difference of the polarizers.

Wrt the form of Bell's (2), wasn't it demonstrated that it can be reduced to, or is analogous to, a statement of the independence of the two data sets?

ThomasT

Jun17-10, 09:17 PM

Here is the issue: I demand of any realist that a suitable dataset of values at three simultaneous settings (a b c) be presented for examination. That is in fact the realism requirement, and fully follows EPR's definition regarding elements of reality. Failure to do this with a dataset which matches QM expectation values constitutes the Bell program. Clearly, Bell (2) has only a and b, and lacks c. Therefore Bell (2) is insufficient to achieve the Bell result.DrC, if you would clarify this for me it would be most appreciated.

JesseM

Jun17-10, 09:28 PM

Ok, here's the way I'm thinking about it today. Wrt the experimental situation, there's a single correct answer, the data sets A and B are not independent. This is because of the data matching via time stamping. Matching the data in this way is based on the assumption of a local common cause.
It's based on the assumption from quantum mechanics that entangled particles are both created at the same position and time, but that doesn't mean that it's assumed that correlations in measurements of the two particles can be explained by local hidden variables given to them by the source.
The fact that data matching via time stamping does produce (or reveal) entanglement correlations would, then, seem to support the idea that a locally produced relationship between counter-propagating disturbances is a necessary condition and the root cause of the correlations between joint detection and angular difference of the polarizers.
If by "a locally produced relationship" you mean local hidden variables, then no, the fact that the statistics violate Bell's inequalities show that this cannot be the explanation.
Wrt the form of Bell's (2), wasn't it demonstrated that it can be reduced to, or is analogous to, a statement of the independence of the two data sets?
Again, you can't just use words like "independence" without being more specific. The equation (2) was based on the assumption of causal independence between the two particles (i.e measuring one does not affect the other), which was expressed as a condition saying they're statistically independent conditioned on the hidden variables λ, but the equation is consistent with the idea that P(AB) can be different from P(A)*P(B).

billschnieder

Jun17-10, 10:35 PM

2) Well of course it can be. For example, I measure Alice at 0 degrees. I know Bob's result at 0 degrees with certainty. That is an element of reality, and it is contextual (observer dependent). Duh. Perhaps you might read what I say next time.
So you have changed your mind that Realism means non-contextual? You are not making a lot of sense. One minute you are arguing that realism means non-contextual, the next you are arguing that it means contextual also.

3) The moon is NOT there when we are not looking, and of course this is an analogy as I keep saying.
Keep deluding yourself.

How many ways can I say it, and how many famous people need to say it before you accept it as a legitimate position (regardless of whether you agree with it)?
You can not find enough famous people to make me believe a lie.

As to EPR not meaning it that way: Einstein SPECIFICALLY said he meant it that way. Do I need to produce the quote? That is why Mermin titled his article as he did.
I just gave you a quote in which EPR said such a view as unreasonable. What about that quote did you not understand?

You know, on a side note: It really makes me laff to see folks like you dismiss towering figures of modern science without so much as one iota of support for your position, other than YOU say it. I can't recall a single useful reference or quote from you. :tongue:
Appeal to authority is a fallacy of reasoning. I don't think I'm the first one to point it out to you recently. Feel free to make a shrine of these "towering figures" but don't expect us to join you.

billschnieder

Jun17-10, 11:13 PM

I'll amend that to say that on the right side there can be no logical dependence since this side deals with A and B conditioned on λ, but on the left side there can.

Bell's equation (2) is an equation, which means the LHS is equal to the RHS, how can one side of an equation be conditioned on λ when the other is not? Don't you mean the term under the integral sign is conditioned on a specific λ?

When A and B are not conditioned on λ, as on the left side of (2) or in the Bell inequalities themselves, then yes there can be a logical dependence between them according to Bell's argument. Do you disagree?
We have discussed this before and apparently you did not get anything out of it. Each λ on the RHS represents a specific value, so you can not say the LHS is conditioned on λ. Each term under the integral is dependent on a specific value of λ, not the vague concept of λ as we have already discussed at length.

So then since you amended your answers, let me also amend my summary of your responses:

Your responses so far are now:
1: Bell's equation(2) expresses a conditional marginal probability
2: Logical dependence between A and B is not allowed in the probability expressed in Bells equation (2)
2b: Logical dependence between A and B is not allowed for the probability dependent on a specific λ under the integral on the RHS of Bell's equation (2)

Does this reflect your view accurately? Are you sure Bell's equation (2) is not a conditional probability, conditioned on the pair of detector settings a and b? Please look at it again carefully and if you decide to stick to this answer, let me know. I don't want to carry on an argument in which the opposing position is shifting based on argumentation tactics so I want to be sure I have given you enough opportunity to express your position before I proceed.

JesseM

Jun18-10, 07:42 AM

Bell's equation (2) is an equation, which means the LHS is equal to the RHS, how can one side of an equation be conditioned on λ when the other is not?
Because a sum of probabilities conditioned on λ can be equal to a probability that isn't conditioned on λ. That's essentially what's meant by "marginalization" according to wikipedia--you agree that if some variable B can take two values B1 and B2, then marginalization says P(A) = P(A, B1) + P(A, B2) right? Well, by the definition of conditional probability, P(A, B1) = P(A|B1)*P(B1), and likewise for B2, so the marginalization equation reduces to P(A) = P(A|B1)*P(B1) + P(A|B2)*P(B2). Here, the left side is not conditioned on B, while the right side is a sum of terms conditioned on every possible specific value of B.
Don't you mean the term under the integral sign is conditioned on a specific λ?
Sure, and the integral represents the idea that you are summing over every possible specific value of λ, just as in my simpler equation above.
We have discussed this before and apparently you did not get anything out of it. Each λ on the RHS represents a specific value, so you can not say the LHS is conditioned on λ.
I remember our previous discussion, which consisted of you making a big deal out of a mere semantic quibble. I already explained in posts like this one (http://www.physicsforums.com/showpost.php?p=2757474&postcount=18) and this one (http://www.physicsforums.com/showpost.php?p=2757729&postcount=21) (towards the end of each) that what I mean when I say "conditioned on λ" is just "conditioned on each specific value of λ", so construing me as saying anything else would suggest you either forgot the entire previous discussion, or that you are using a semantic quibble as an excuse for a strawman argument about what I actually mean. And as far as semantics go, in those posts I also pointed you to section 13.1 of this book (http://books.google.com/books?id=PYNAgzDffDMC&lpg=PA151&dq=%22conditional%20probability%22%20%22random%20v ariable%22&pg=PA151#v=onepage&q=%22conditional%20probability%22%20%22random%20va riable%22&f=false) which is titled "conditioning on a random variable"--do you think the book is using terminology incorrectly?
Each term under the integral is dependent on a specific value of λ, not the vague concept of λ as we have already discussed at length.
Yes, and when I talk about conditioning on λ I just mean conditioning on each specific value of λ, as you should already know if you'd been paying attention. If you understand what I mean but don't like my terminology, tough, I think it's correct and I've given a reference to support my use of terminology, you'll have to point me to an actual reference rather than just assert your authority if you want to convince me to change it.
Your responses so far are now:
1: Bell's equation(2) expresses a conditional marginal probability
Conditional probabilities in the integral on the right side of the equation, a marginal probability on the left.
2: Logical dependence between A and B is not allowed in the probability expressed in Bells equation (2)
Allowed for the term on the left side of the equation.
2b: Logical dependence between A and B is not allowed for the probability dependent on a specific λ under the integral on the RHS of Bell's equation (2)
Yes.
Does this reflect your view accurately? Are you sure Bell's equation (2) is not a conditional probability, conditioned on the pair of detector settings a and b?
Well, now you're quibbling again, the main idea being discussed with ThomasT was the idea that there could be a dependence between A and B when not conditioned on the hidden variables which disappeared when they were conditioned on the hidden variables. It's true that you can interpret the left side as a conditional probability conditioned on a and b, but the only point relevant to the argument is whether it's conditioned on the hidden variables. And Bell doesn't clearly use the conditional probability notation in (2), so you could think of the a and b that appear in the equation as just denoting the idea that we are considering a sample space which consists only of trials where the detectors were set to a and b, in which case A would be defined as a variable that represents the measurement outcome with detector setting a and B is a variable that represents the measurement outcome with detector setting b. So under this interpretation the left side is really a marginal probability...it just depends how you interpret the equation, and in any case the choice of interpretation is irrelevant to the actual discussion with ThomasT. So, if you try to do a "gotcha" based on the fact that I said the left side was a marginal probability as it's not conditioned on λ, which you say is wrong because it is conditioned on a and b, I'll consider you to be playing pointless one-upmanship games again. It's irrelevant to the actual argument whether or not the left side is conditioned on variables other than λ, the argument is just about how A and B are statistically independent when conditioned on λ but statistically dependent when not. It simplifies the discussion to call the "when not" case the marginal correlation between A and B, and as I said you're free to interpret the left side of the equation so that it is a marginal probability and a and b merely tell us which settings are to be considered in the sample space.

zonde

Jun18-10, 08:49 AM

Non-contextual = Realistic

Now some folks quibble about the difference, but the difference is mostly a matter of your exact definition - which does vary a bit from author to author. So I acknowledge that. However, I think EPR covers the definition in a manner most accept:

"One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive. Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted.... No reasonable definition of reality could be expected to permit this."

Not sure but I think you misquoted EPR.
Full quote goes like that:
"One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive. Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted. On this point of view, since aither one or the other, but not both simultaneously, of the quantities P and Q can be predicted, they are not simulataneously real. This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."
To me it seems that last sentence speaks about previous sentence i.e. EPR says that first measurement can not "create" reality of second measurement.
So it is like even with that definition of reality their argument as it is outlined in their paper still holds.

As to GHZ:

"Surprisingly, in 1989 it was shown by Greenberger, Horne and Zeilinger
(GHZ) that for certain three- and four-particle states a conflict with
local realism arises even for perfect correlations. That is, even for those cases
where, based on the measurement on N −1 of the particles, the result of the
measurement on particle N can be predicted with certainty. Local realism
and quantum mechanics here both make definite but completely opposite
predictions.

"To show how the quantum predictions of GHZ states are in stronger conflict
with local realism than the conflict for two-particle states as implied by Bell’s
inequalities, let us consider the following three-photon GHZ state:

"We now analyze the implications of these predictions from the point of
view of local realism. First, note that the predictions are independent of the
spatial separation of the photons and independent of the relative time order
of the measurements. Let us thus consider the experiment to be performed
such that the three measurements are performed simultaneously in a given
reference frame, say, for conceptual simplicity, in the reference frame of the
source. Thus we can employ the notion of Einstein locality, which implies
that no information can travel faster than the speed of light. Hence the
specific measurement result obtained for any photon must not depend on
which specific measurement is performed simultaneously on the other two
or on the outcome of these measurements. The only way then to explain
from a local realistic point of view the perfect correlations discussed above
is to assume that each photon carries elements of reality for both x and y
measurements considered and that these elements of reality determine the
specific individual measurement result. Calling these elements of reality...

"In the case of Bell’s inequalities for two photons the conflict between local
realism and quantum physics arises for statistical predictions of the theory;
but for three entangled particles the conflict arises even for the definite predictions."

Zeilinger talking about GHZ in:
http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf

So GHZ does show that Local Realism makes specific predictions which are flat out contradicted by both QM and experiment.
Hmm, I will need to investigate a bit more.
I looked at this paper where they speak about 4 particle GHZ and here it is clear that they can not produce prediction for local realism at all.
Going Beyond Bell's Theorem (http://arxiv.org/abs/0712.0921)
On the other hand in the paper from your site they make some prediction for local realism when tree-photon GHZ is considered. I will look at four-photon GHZ experiment from the same paper.

unusualname

Jun18-10, 09:27 AM

4 Particle GHZ violations of local realism were demonstrated back in 2003:

Experimental Violation of Local Realism by Four-Photon
Greenberger-Horne-Zeilinger Entanglement Phys. Rev. Lett. 91, 180401 (2003) [4 pages] (http://www.physics.princeton.edu/~mcdonald/examples/QM/zhao_prl_91_180401_03.pdf)

We report the first experimental violation of local realism by four-photon Greenberger-Horne-Zeilinger (GHZ) entanglement. In the experiment, the nonstatistical GHZ conflicts between quantum mechanics and local realism are confirmed, within the experimental accuracy, by four specific measurements of polarization correlations between four photons. In addition, our experimental results also demonstrate a strong violation of Mermin-Ardehali-Belinskii-Klyshko inequality by 76 standard deviations. Such a violation can only be attributed to genuine four-photon entanglement.

There are several results like this:

Greenberger-Horne-Zeilinger-type violation of local realism by mixed states (2008) (http://arxiv.org/abs/0805.1468)
Bell Theorem without Inequality for Some Generalized GHZ and W States (2007) (http://iopscience.iop.org/0256-307X/24/11/006)

local realism is dead, live with it :)

We're (obviously) just observing a 3-dimensional subset of reality restricted to a 3-brane or similar.

DrChinese

Jun18-10, 10:43 AM

1. So you have changed your mind that Realism means non-contextual? You are not making a lot of sense. One minute you are arguing that realism means non-contextual, the next you are arguing that it means contextual also.

2. Keep deluding yourself... You can not find enough famous people to make me believe a lie.

3. I just gave you a quote in which EPR said such a view as unreasonable. What about that quote did you not understand?

1. The realism requirement is essentially equivalent to non-contextuality, no change in my view on that.

Apparently, you do not understand: accepting that there exists an inidividual "element of reality" per EPR - which can be demonstrated experimentally - is not the same thing as accepting that all "elements of reality" are simultaneously real. The belief that elements of reality simultaneously exist - that the moon is there even when you are not looking - is EPR realism.

2. All I am asking is that you accept a different point of view as legitimate. I have never said I expect you to accept the position of Zeilinger or whoever as your own. I appreciate that you think any opinion different than your own as being a "lie" but that is basically borderline moronic.

3. I wish you would read what you quote. Yes, EPR says that it is unreasonable to assert that the moon is not there when no one is looking. That would mean they believe the moon IS there when no one is looking. And Einstein said precisely that: "...an electron has spin, location and so forth even when it is not being measured. I like to think that the moon is there even if I am not looking at it..."

Come on, Bill, I think you can do better. Don't you have anything USEFUL to add? Other than being a craggly contrarian?

DrChinese

Jun18-10, 10:47 AM

Not sure but I think you misquoted EPR.
Full quote goes like that:
"One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive. Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted. On this point of view, since aither one or the other, but not both simultaneously, of the quantities P and Q can be predicted, they are not simulataneously real. This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."
To me it seems that last sentence speaks about previous sentence i.e. EPR says that first measurement can not "create" reality of second measurement.
So it is like even with that definition of reality their argument as it is outlined in their paper still holds.

Yes, that is the full quote. My point is that EPR sets up a definition of realism which is NOT limited to what can be experimentally demonstrated. That 2 or more elements of reality - a, b and c were used by Bell - should be reasonably expected to exist simultaneously. Bell and Aspect have shown us that this view (EPR realism) is theorically and experimentally invalid.

DevilsAvocado

Jun18-10, 12:07 PM

http://i40.tinypic.com/5nlo9w.gifGeneral Warning - billschniederhttp://i40.tinypic.com/5nlo9w.gif

I’ve found "the source" for billschnieder’s weirdness, and it’s some of the worse crackpots I ever seen. His name is A. F. Kracklauer:

http://i50.tinypic.com/md1hyu.jpg
(Please note! This is NOT a joke: Krack-lauer / Crack-pot :biggrin:)

He’s an "independent researcher" and on his homepage Non-loco Physics (http://www.nonloco-physics.000freehosting.com/) you can see from his personalia (http://www.nonloco-physics.000freehosting.com/#personalia) that he is real "independent"...

billschnieder’s crazy arguments is a raw copy of Crackpot Kracklauer’s NOT peer reviewed paper - Nonlocality, Bell's Ansatz and Probability (http://arxiv.org/abs/quant-ph/0602080). After rambling on for 9 pages of completely meaningless words (familiar!?), Crackpot Kracklauer draws this breathtaking conclusion:
IX. CONCLUSIONS
The points made above offer several explanations for the observation noted in the introduction, that BELL’s Ansatz, Eq. (1), cannot be found in treatises on statistics and probability. To begin, there is misleading notation; BELL used a COMMA to separate the independent arguments, whereas ‘hidden’ variables, by definition would be conditioning parameters, and, as such, in the notation customary in works on probability, are separated from independent variables by a VERTICAL BAR. This malapropos TURN OF THE PEN appears to have been an important facilitating element in the general misconstrual of BELL’s analysis. Once this defect is corrected, it is a short leap to the understanding of the necessity for applying BAYES’ formula; a leap apparently made first by JAYNES.

WOW! Now we know why Bell is wrong! He used a comma instead of vertical bar!! THIS IS GROUNDBREAKING NEWS!! Why hasn’t anyone thought of this BEFORE !?:bugeye:!?:bugeye:!?

Laughing out loud? Wait, next part in this story of Crackpot Kracklauer is a strong competitor to Monty Python's Flying Circus!! :biggrin:

I’ve found this very amusing video (23:46), where Crackpot Kracklauer makes a hilarious "analysis" of Bell inequalities violation, and finally presents his own very functional solution to the problem:

Kracklauer - EPR Experiments: Analysis of Bell Inequalities Violation

http://i45.tinypic.com/k1cal1.jpg (http://video.google.com/videoplay?docid=-1112934842741515675)

I’m pretty impressed by his vocabulary. He frequently uses the scientifically sophisticated term – "Blah Blah Blah" and sometimes even "Ops!".

Crackpot Kracklauer is a brave man, not afraid to challenge the establishment:

"There is NO quantum mechanics in 'Qubit Space'!"

(He also sees a real possibility to run quantum computing on vacuum tubes!:surprised!)

Crackpot Kracklauer therefore rejects that a Qubit (http://en.wikipedia.org/wiki/Qubit) has anything to do with Quantum information (http://en.wikipedia.org/wiki/Quantum_information), which is breaking news and deserves a Nobel!! :biggrin:

Crackpot Kracklauer rambles on and makes scandalous insinuations on John Bell’s death ("knocked over" by his theorem), and gets the year wrong.

Finally, at 16:25 he presents his "solution" and his equations for a few sec, and says:

"Now once again, it takes a little patient and thought to see exactly how these equations work." (you bet! :grumpy:)

But he really scores at 16:30, where he gets to the "punch line". Here he shows real data from his own computer simulation (using his "solution"), and states:

"This simulation exceeds the limit of 2, in fact it’s 2 times the square of 2, what’s exactly what a Bell inequality shows you!"
The only problem with this revolutionary news is that Crackpot Kracklauer apparently has forgotten that he one year earlier "proved" that Bell inequalities are WRONG!! And now he is using Bell inequalities to prove the he is RIGHT!?!?!?!? Pure madness!! :rofl: :rofl:

After this, there’s absolutely NO reason to "Trying to Understand billschnieder’s reasoning". He’s inspired by a complete lunatic, and he’s thereby polluting PF with cranky speculations. Completely meaningless words and argumentation from billschnieder in thread Trying to Understand Bell's reasoning (http://www.physicsforums.com/showthread.php?t=399795) generated 111 posts, to absolutely NO use at all, polluted PF, and has stolen valuable time.

Please, ignore all new post along this line from billschnieder. It will make us all happier!!

DrChinese

Jun18-10, 01:39 PM

I’ve found "the source" for billschnieder’s weirdness, and it’s some of the worse crackpots I ever seen. His name is A. F. Kracklauer:
...

I have this one of his in my list of local realists, a paper from 2009:

http://arxiv.org/abs/0903.0733

Hmmm.

By the way, the sirens are a nice effect. :smile: And you always have the best.

ajw1

Jun18-10, 02:16 PM

The man seems to have quite an impressive list of what I suppose to be peer reviewed articles. So why call him crackpot?

DevilsAvocado

Jun18-10, 03:54 PM

I have this one of his in my list of local realists, a paper from 2009:

http://arxiv.org/abs/0903.0733

Hmmm.

By the way, the sirens are a nice effect. :smile: And you always have the best.

Thanks DrC. Yes, Crackpot Kracklauer is a real heavy borderliner. He’s apparently fairly productive and has skills in mathematics and physics, but the overall picture says only one thing – crackpot.

Here’s the list of all his papers (http://arxiv.org/find/all/1/all:+Kracklauer/0/1/0/all/0/1) on arXiv.org.

DevilsAvocado

Jun18-10, 04:05 PM

The man seems to have quite an impressive list of what I suppose to be peer reviewed articles. So why call him crackpot?

Do you mean his 21 papers on arXiv.org? There is no obligation for peer review on arXiv.org (http://en.wikipedia.org/wiki/ArXiv#Peer_review), and only 2 are peer reviewed, and that was more than 10 years ago, and I can’t tell about the legitimacy of these two:

An Intutive Paragidm for Quantum Mechanics (http://arxiv.org/abs/quant-ph/0008121)
Journal reference: Physics Essays 5(2) 226-234 (1992)

Pilot Wave Steerage: A Mechanism and Test (http://arxiv.org/abs/quant-ph/9711013)
Journal reference: Found. Phys. Lett. 12(5) 441-453 (1999)

But if you watch the whole video, you don’t need to be a professor to draw the conclusion I did, and I’m 100% - he IS a crackpot.

Do you really think a serious scientist would have a homepage named Non-loco Physics (loco means crazy in Spanish) = Non-crazy Physics. This can only be interpreted two ways; either Kracklauer thinks physics in general should be considered "loco" – or he acting preemptive to his own wild ideas. None is appealing...

How big is the chance that a great and healthy scientist has links to papers titled "Complementarity or Schizophrenia: is Probability in Quantum Mechanics Information or Onta?" ... ?:bugeye:?

The man is a BIG joke, watch the video and have fun... :wink:

RUTA

Jun18-10, 05:13 PM

Do you mean his 21 papers on arXiv.org? There is no obligation for peer review on arXiv.org (http://en.wikipedia.org/wiki/ArXiv#Peer_review), and only 2 are peer reviewed, and that was more than 10 years ago, and I can’t tell about the legitimacy of these two:

An Intutive Paragidm for Quantum Mechanics (http://arxiv.org/abs/quant-ph/0008121)
Journal reference: Physics Essays 5(2) 226-234 (1992)

Pilot Wave Steerage: A Mechanism and Test (http://arxiv.org/abs/quant-ph/9711013)
Journal reference: Found. Phys. Lett. 12(5) 441-453 (1999)

But if you watch the whole video, you don’t need to be a professor to draw the conclusion I did, and I’m 100% - he IS a crackpot.

Do you really think a serious scientist would have a homepage named Non-loco Physics (loco means crazy in Spanish) = Non-crazy Physics. This can only be interpreted two ways; either Kracklauer thinks physics in general should be considered "loco" – or he acting preemptive to his own wild ideas. None is appealing...

How big is the chance that a great a healthy scientist has links to papers titled "Complementarity or Schizophrenia: is Probability in Quantum Mechanics Information or Onta?" ... ?:bugeye:?

The man is a BIG joke, watch the video and have fun... :wink:

Are you talking about A.F. Kracklauer, "Is 'entanglement' always entangled?" J. Opt. B: Quantum Semiclass. Opt. 4 (2002), S121-S126? I met him at a conference some years ago and he presented what he claimed was the "proper" statistics for QM. In his approach, there was no need for non-locality or non-separability. After the conference, I found the faulty assumption in his approach -- his statistics assumes that knowledge of detector settings is available at both detection sites. I wrote him a detailed email explaining that experiments change polarization settings at very high frequencies precisely so info about Alice's detector settings is not available to Bob and vice versa. He became very upset and told me I didn't know what I was talking about. I don't know what else to do to help him and we haven't been in contact since.

DevilsAvocado

Jun18-10, 05:38 PM

Are you talking about A.F. Kracklauer, "Is 'entanglement' always entangled?" J. Opt. B: Quantum Semiclass. Opt. 4 (2002), S121-S126? I met him at a conference some years ago and he presented what he claimed was the "proper" statistics for QM. In his approach, there was no need for non-locality or non-separability. After the conference, I found the faulty assumption in his approach -- his statistics assumes that knowledge of detector settings is available at both detection sites. I wrote him a detailed email explaining that experiments change polarization settings at very high frequencies precisely so info about Alice's detector settings is not available to Bob and vice versa. He became very upset and told me I didn't know what I was talking about. I don't know what else to do to help him and we haven't been in contact since.

Hehe! Sounds very much like "my" Crackpot Kracklauer!! :biggrin:

This is getting better and better. The world is full of weird surprises. One thing that’s baffles me – how can a man with this much mathematical skill still draw completely illogical conclusions...? The only reasonable conclusion is that he knows what he’s doing – and he does it on purpose... You can’t be completely mad and solve this kind of equations, can you??

(Did you see post #806 (http://www.physicsforums.com/showthread.php?p=2766674#2766674)?)

P.S. I will be surprised if billschnieder ever shows up in this thread again. :rofl:

RUTA

Jun18-10, 05:46 PM

(Did you see post #806 (http://www.physicsforums.com/showthread.php?p=2766674#2766674)?)

No, that's the first I've seen it. That is the guy I met and tried to educate. I haven't seen any of his recent stuff, but given my past experience with him, it's probably not worth the time.

DevilsAvocado

Jun18-10, 06:09 PM

... it's probably not worth the time.

Okay, I understand you completely.

RUTA, I think it would be of value (for any 'doubtful' reader) if you, as legitimate professor in physics, could confirm my conclusion that; Kracklauer cannot be using Bell inequalities to prove that he has found a working classical local realistic solution to EPR-Bell – and at the same time publish a paper where he claims to have proven that Bell inequalities are wrong from the very first assumption.

I’m only a layman, but even I understand that this is a complete crazy Catch-22, that it cannot be regarded as serious in any way.

billschnieder

Jun18-10, 06:15 PM

Conditional probabilities in the integral on the right side of the equation, a marginal probability on the left.
...
It's true that you can interpret the left side as a conditional probability conditioned on a and b

So then your answer is that the left hand side of Bell's equation (2) is conditional with respect to (a,b) but marginal with respect to λ. And that outcome dependence between A and B exists when conditioned only on (a,b) but does not exist when conditioned on λ.

So then the expression P(AB|a,b) will accurately reflect what the probability Bell is calculating in equation (2) on the LHS? Yes or no.

And according to the chain rule of probability theory, the following expression is also true according to Bell's equation (2).

P(AB|a,b) = P(A|a,b)P(A|a,b,B)

Yes or no.

Please, note I am trying to engage in a precise discussions so don't assume you know where I am going with this and give me a preemptive response. A simple yes or no is sufficient here.

DevilsAvocado

Jun18-10, 06:24 PM

billschnieder, please stop polluting this thread with CRACKPOT THEORIES, read post #806 (http://www.physicsforums.com/showthread.php?p=2766674#post2766674).

ajw1

Jun18-10, 06:43 PM

DevilsAvocado

Jun18-10, 07:16 PM

I see about 25 publications in peer reviewed magazines

Please, show me one paper from Kracklauer published outside Non-loco Physics and peer reviewed in a reputable scientific magazine after 1999?

billschnieder

Jun18-10, 09:40 PM

Please, show me one paper from Kracklauer published outside Non-loco Physics and peer reviewed in a reputable scientific magazine after 1999?
Devil,
I was surprised not so see flashing and blinking animation reminiscent of 1995's internet in the above post of yours, check your calendar, it is 2010 not 1999. It is now possible to just type a name in scholar.google.com and verify what awj1 said above. BTW, you could have simply asked I would have given you the list of people who have influenced my approach to Bell.

Initially I thought I would just ignore you but then again by directly challenging you, you might benefit something from it and grow up from the dated distracting gifs and animations your posts are so infamous for.

Oh by the way, do you esteem yourself more wise and knowledgeable than the folks here, to the extent that you think they are unable to think for themselves, and need your advice on when to pay attention to what I say or not?

ThomasT

Jun18-10, 09:41 PM

One thing that’s baffles me – how can a man with this much mathematical skill still draw completely illogical conclusions...?Maybe they're not illogical. Maybe his premises are wrong. Or maybe some of his conclusions are illogical. Or maybe not. Since I haven't read his papers it's, as they say, too early (for me) to tell.

In any case, thanks for the resource. He has peer reviewed publications in several well respected journals. Even if his approach or conclusions turn out to be wrong, there is the benefit of his, from what I've seen so far, clear writing style. And of course there are his translations of some real classics in the physics literature. Definitely recommended reading.

So far, he doesn't seem like a crackpot. But I'll grant you that in the video he did seem a bit, er, scattered (but considering the obvious time constraint, his behavior didn't seem wierd or anything). Nevertheless, his credentials appear to exceed any of the contributors to this thread.

So, again, thank you DA.

Edit:
Please, show me one paper from Kracklauer published outside Non-loco Physics and peer reviewed in a reputable scientific magazine after 1999?There appear to be several.

ThomasT

Jun18-10, 09:46 PM

ThomasT

Jun18-10, 09:53 PM

It's {the data matching} based on the assumption from quantum mechanics that entangled particles are both created at the same position and time ...Ok.

... but that doesn't mean that it's assumed that correlations in measurements of the two particles can be explained by local hidden variables given to them by the source.I agree. The relationship between the two particles isn't, strictly speaking, a 'local' hidden variable. It's a parameter that emerges, and is only relevant, in the joint context. It doesn't determine individual measurement probabilities. And yet, isn't Bell's (2) requiring that the joint probability be modelled as the product of the two individual probabilities?

If by "a locally produced relationship" you mean local hidden variables, then no, the fact that the statistics violate Bell's inequalities show that this cannot be the explanation.I agree, per above. But the root cause of the relationship can be assumed to be a local common source.

The local hidden variable in any trial is the randomly varying (from trial to trial) polarization angle that, presumably, would, if known, allow precise predictions of individual results. Qm says, in effect, that this local hidden variable is irrelevant wrt determining joint results -- that it is, rather, the unvarying relationship between counter-propagating disturbances emitted during the same atomic transition due to the conservation of angular momentum that determines joint results (re, eg., Clauser-Aspect type setups). This is just an interpretation of course, but it doesn't contradict anything in the qm treatment. And it's suggested that the attribution of, and subsequent projection along, a 'principle' axis given a qualitative result at one end or the other is compatible with the assumptions of locality and predetermination (albeit not separable) regarding the jointly measured underlying parameter. Why does the cos^2 theta rule following the attribution of the principle axis wrt a detection attribute work? Because the local hidden variable (as differentiated from the global parameter) can be any polarization angle. There are three vectors involved, call them, V1, V2, and V3, an optical vector and two unit vectors. They can be ordered in any way. One, the optical vector, is undetermined but assumed to be continuous between the two unit vectors. So, it seems logical to me, and compatible with the idea that everything is evolving according to the principle of locality, that the joint detection rate would be described by the cos^2 of the angular difference between the two unit vectors. As, I've said before, it's just accepted optics. And, because it's accepted optics, this is why the qm treatment for these types of setups is evaluated using Malus Law. I don't think that Bell's analysis rules this out, but rather that it's saying something about how this situation can be modelled. And, wrt that, Bell was correct.

The equation (2) was based on the assumption of causal independence between the two particles (i.e measuring one does not affect the other), which was expressed as a condition saying they're statistically independent conditioned on the hidden variables L ... I agree. The equation says that the two particles (ie., the sets of detection attributes denoted by A and B) are statistically independent. In which case, the locality condition (separability of the joint state) is clearly formulated, but simply doesn't fit the experimental situation which, per se, doesn't require, or indicate in its evolution, the presence of nonlocal or ftl 'communication' between anything. So, we have a situation in which the purported independence between A and B is violated by the experimental design and realization which are entirely compatible with the assumption of locality. In other words, the fact that Bell's lhv form models statistical independence supercedes it's purported modelling of locality.

... but the equation is consistent with the idea that P(AB) can be different from P(A)*P(B).Not sure what you mean.

ThomasT

Jun18-10, 09:55 PM

DrChinese

Jun19-10, 09:56 AM

DrC, you might have missed this. So, I'm posting it again. You've been asked to look at and comment on some LR models, and have refused to do so because they reproduce the qm predictions. This doesn't make sense to me, so if you would clarify the following, then maybe we might proceed. Thanks.

I stated:

i) I demand of any realist that a suitable dataset of values at three simultaneous settings (a b c) be presented for examination. That is in fact the realism requirement, and fully follows EPR's definition regarding elements of reality. Failure to do this with a dataset which matches QM expectation values constitutes the Bell program.

ii) Clearly, Bell (2) has only a and b, and lacks c. Therefore Bell (2) is insufficient to achieve the Bell result.

------------------
So to expand on these:

i) There are a number of papers that "purport" to provide local realistic models. But they do not provide datasets (with 3 angle settings) which match the QM expectation values. That is to be expected, because Bell discovered that there are no such datasets. Why is a dataset important? Because it was known already that datasets with 2 angle settings were possible. In fact, that was more or less one of the EPR conclusions although they did not really specify that single point. What they did specify was that the existing (at that time) QM program could be made "more complete" with additional parameters, yet to be discovered.

So local realistic theories with 2 simultaneous settings are missing the boat, precisely because they describe something which is not prohibited by Bell. And if they did offer the ability to provide a 3 setting dataset, they would simply provide it and Bell would be overturned. So I don't really need to read and de-bunk each purported solution until and unless a dataset can be provided.

In the case of the De Raedt local realistic computer simulation, on the other hand, such a dataset is provided. So naturally I DO take it seriously and am actively involved in working with a respected member of their team to understand their model and its characteristics. Keep in mind that it is a simulation, not a true physical model. However, the success of their model would open the door to a physical model - if it can survive questions that are inevitable.

ii) One of the recent questions on this board concerns whether Bell (2) is a sufficient assumption to achive the main result. You can see for yourself - as can anyone who will simply look - that it does not involve 3 settings, but instead only 2. The Bell program requires the assumption of at least existence of 3 simultaneous "elements of reality". In the EPR program, there was only 1 (let's call it a), because that was all that could be predicted with certainty. But they said in their closing papragraphs that it was reasonable to consider that any element of reality individually should reasonably be considered to exist independent of actual observation. So this is the counterfactual case: b, c... etc. They needed this because it was essential to their claim that QM was incomplete. Bell accepted the "challenge" and considered a, b and c, achieving his now famous result. But you cannot get it - as far as I have seen - with just (2). You need after (14) too.

billschnieder

Jun19-10, 10:06 AM

DrChinese

Jun19-10, 11:22 AM

DrC,
Take a look at my last post in the thread "Understanding Bell's logic (post #113)" in which I presented a simplified version of JesseM's scratch-lotto card example, which is essentially a copy of Mermin's example.

Is it still your believe that an instruction set explanation of it is impossible? Will an instruction-set explanation of that example qualify as a "dataset" that you keep asking for?

Yes, Bill, I think that works for me. I looked over the example and it looks pretty good. That is definitely the kind of example that clarifies so that definitions are not standing in the way of finding a common ground.

DevilsAvocado

Jun19-10, 03:42 PM

He has peer reviewed publications in several well respected journals.

Could you please show me one title, link, or paper-id?

So far, he doesn't seem like a crackpot. But I'll grant you that in the video he did seem a bit, er, scattered (but considering the obvious time constraint, his behavior didn't seem wierd or anything). Nevertheless, his credentials appear to exceed any of the contributors to this thread.

ThomasT, please tell me you are joking, right? A bit "scattered"?? This is some of the worst cranky stuff I have ever seen. The first 4 min of the video Crackpot Kracklauer dismisses QM and states that the Heisenberg uncertainty principle is wrong!! According to Crackpot Kracklauer at 03:20.

"The reason they don’t commute is not because someone has imposed the Heisenberg uncertainty relationship on them. In fact, the reason they don’t commute is purely geometry. The ah eh the the the structure of 'Qubit Space' in terms of polarization was worked out by... by... what’s his name... an Englishman ...in 1856... Stokes's! Fifty years before Pauli was born even!"

Crackpot Kracklauer is now talking about one of the pioneers of quantum physics and a Nobel laureate in Physics Wolfgang Pauli (http://en.wikipedia.org/wiki/Wolfgang_Pauli), and also Werner Heisenberg (http://en.wikipedia.org/wiki/Werner_Heisenberg) was a QM pioneer and a Nobel laureate in Physics.

Don’t you see the pure madness in this!? Crackpot Kracklauer tries to give picture that QM is completely wrong, and the big questions were already solved fifty years before anyone has ever heard the word quantum theory!?!? This is insane. He runs his own private mad war against QM.

And to be perfectly clear to the "casual reader"; IF Crackpot Kracklauer is right and QM is wrong, then right now your hard disk drive in your own computer will have 3 times lesser capacity! Since QM Giant magnetoresistance (GMR) (http://en.wikipedia.org/wiki/Giant_magnetoresistance) is used by ALL manufacturers to increase HDD capacity.

Furthermore, there’s a whole bunch of gadgets you use every day that will stop working if Crackpot Kracklauer is anywhere near right. But don’t worry, Crackpot Kracklauer dead wrong and QM is the most precise theory we got. Period.

So, Crackpot Kracklauer is just too much, and I will never back off from this, never. Supporting Crackpot Kracklauer must be against all and everything in Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=5374) (my emphasis):

Overly Speculative Posts:
One of the main goals of PF is to help students learn the current status of physics as practiced by the scientific community; accordingly, Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. It is against our Posting Guidelines to discuss, in most of the PF forums or in blogs, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion. Personal theories/Independent Research may be submitted to our Independent Research Forum, provided they meet our Independent Research Guidelines; Personal theories posted elsewhere will be deleted. Poorly formulated personal theories, unfounded challenges of mainstream science, and overt crackpottery will not be tolerated anywhere on the site. Linking to obviously "crank" or "crackpot" sites is prohibited.

In any case, thanks for the resource.

You are welcome.

DevilsAvocado

Jun19-10, 03:45 PM

... BTW, you could have simply asked I would have given you the list of people who have influenced my approach to Bell.

So I’m asking you very friendly now: Please show me one reputable scientist who speculates around the possibilities that John Stewart Bell made a terrible mistake when he used a comma instead of vertical bar, in equation (2), and therefore Bell's Theorem is all wrong from start. Please, just one trustworthy scientist.

I will apologize sincerely if you prove me wrong.

billschnieder

Jun19-10, 06:00 PM

So I’m asking you very friendly now: Please show me one reputable scientist who speculates around the possibilities that John Stewart Bell made a terrible mistake when he used a comma instead of vertical bar, in equation (2), and therefore Bell's Theorem is all wrong from start. Please, just one trustworthy scientist.

I will apologize sincerely if you prove me wrong.

Provide a quote from the article where you think Kracklauer made such a statement, and I will use the same quote to prove to the whole world just why it is you who has issues understanding simple English. So the the ball is in your court. I hope you will keep your honor by appologizing sincerely when this is all over.

I'm waiting!

DevilsAvocado

Jun19-10, 07:09 PM

Provide a quote from the article where you think Kracklauer made such a statement

I hope there’s nothing wrong with your glasses? Because it’s right in front of your nose in post #806 (http://www.physicsforums.com/showpost.php?p=2766674&postcount=806):

(I’ll make it a little bigger for you this time)
IX. CONCLUSIONS
The points made above offer several explanations for the observation noted in the introduction, that BELL’s Ansatz, Eq. (1), cannot be found in treatises on statistics and probability. To begin, there is misleading notation; BELL USED A COMMA to separate the independent arguments, whereas ‘hidden’ variables, by definition would be conditioning parameters, and, as such, in the notation customary in works on probability, are separated from independent variables by a VERTICAL BAR. This malapropos TURN OF THE PEN appears to have been an important facilitating element in the general MISCONSTRUAL OF BELL’S ANALYSIS. Once this defect is corrected, it is a short leap to the understanding of the necessity for applying BAYES’ formula; a leap apparently made first by JAYNES.

The pure fact that you are continually supporting Crackpot Kracklauer proves, without any doubt, that I was perfectly correct from the start. I gave you a fair chance to solve this in a civilized manner – you didn’t take it.

If you continue to promote Crackpot Kracklauer’s completely crazy theories, I will report you. I don’t even have to "prove" anything – Crackpot Kracklauer is, by his very own definition, an independent researcher. His crazy "stuff" is only allowed in the Independent Research Forum, provided he meets the Independent Research Guidelines, which he will never do. End of story.

I do hope you are capable of reading and understanding the Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=5374)?

Make your choice.

billschnieder

Jun19-10, 11:30 PM

Remember, the phrases you are trying to prove against Kracklauer are the following, in your own words:

WOW! Now we know why Bell is wrong! He used a comma instead of vertical bar!! THIS IS GROUNDBREAKING NEWS!

John Stewart Bell made a terrible mistake when he used a comma instead of vertical bar, in equation (2), and therefore Bell's Theorem is all wrong from start.

You said twice, that Kracklauer claims Bell's Theorem is all wrong because he used a comma instead of a vertical bar. So let us examine your so-called proof.

IX. CONCLUSIONS
The points made above offer several explanations for the observation noted in the introduction, that Bell’s Ansatz, Eq. (1), cannot be found in treatises on statistics and probability.
To begin, there is misleading notation; Bell used a comma to separate the independent arguments, whereas ‘hidden’ variables, by definition would be conditioning parameters, and, as such, in the notation customary in works on probability, are separated from independent variables by a vertical bar.
This malapropos turn of the pen appears to have been an important facilitating element in the general misconstrual of Bell's analysis. Once this defect is corrected, it is a short leap to the understanding of the necessity for applying bayes’ formula; a leap apparently made first by Jaynes.

Clearly, from the above, any layman capable of understanding English can figure out that according to Kracklauer, the non-standard notation used by Bell, has facilitated a general misunderstanding of Bell's analysis. Was this quote supposed to prove that Kracklauer claims Bell's inequalities are wrong because he used a comma instead of a vertical bar?

1) Did Bell use non-standard notation? Yes
2) Does standard notation use a vertical bar instead of a comma when expressing conditional probability? Yes
3) Is it reasonable to suggest that the use of non-standard notation leads to misunderstanding? Yes.

I do hope you are capable of reading and understanding the Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=5374)?

Let us see what the document you linked to says:

When posting a new topic do not use the CAPS lock (all-CAPS), bold, oversized, or brightly colored fonts, or any combination thereof. They are hard to read and are considered yelling. When replying in an existing topic it is fine to use CAPS or bold to highlight main points.

So keep looking and produce the quote where Kracklauer claims Bell's inequalities are wrong because he used a comma instead of a vertical bar.

DevilsAvocado

Jun20-10, 09:06 AM

Remember, the phrases you are trying to prove against Kracklauer are the following

Hahahah!! I’m laughing my pants off!!!!!! :rofl: (<-- Note: BOLD!!! :surprised)

billschnieder, you must be the most "peculiar" guy I’ve ever seen on PF. Don’t you understand that you are helping me to prove beyond any doubts – that your one and only source for all this extensive cranky-probability-mess, that you have practiced all over the place, is Crackpot Kracklauer!!

Don’t you understand this?? Is this really so hard??

And this strategic blunder is nothing more than laughable (and I do feel sorry for you):

1) Did Bell use non-standard notation? Yes
2) Does standard notation use a vertical bar instead of a comma when expressing conditional probability? Yes
3) Is it reasonable to suggest that the use of non-standard notation leads to misunderstanding? Yes.

Here you are actually verifying that all my claims were correct from the very start.

I don’t care if you spend 1000 "probability-enigma-posts" in threads like "Trying to understand this and that", but if you continue in this thread, I will report you, guaranteed.

By the way: Why don’t you report me for using CAPS lock (all-CAPS) + bold + oversized?? It’ll be fun! Ever heard of the boomerang??

Thanks for the laughs, take care.

billschnieder

Jun20-10, 10:27 AM

DevilsAvocado,
Did you find the quote yet where you say Kracklauer claims Bell's inequalities are wrong because he used a comma instead of a vertical bar? Or was it just as untrue as the claim that Kracklauer has only two peer reviewed articles published before 1999 and none after.

billschnieder

Jun20-10, 11:00 AM

Yes, that is the full quote. My point is that EPR sets up a definition of realism which is NOT limited to what can be experimentally demonstrated. That 2 or more elements of reality - a, b and c were used by Bell - should be reasonably expected to exist simultaneously. Bell and Aspect have shown us that this view (EPR realism) is theorically and experimentally invalid.

DrC,
I disagree with your interpretation of the EPR quote, which I parse below. Not only is theEPR definition not limited to what can be experimentally demonstrated, but it is also not limited to what can be predicted as explained below.

"
1) One could object to this conclusion on the grounds that our criterion of reality is not sufficiently restrictive.
2) Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted.
3) On this point of view, since either one or the other, but not both simultaneously, of the quantities P and Q can be predicted, they are not simulataneously real. This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way.
4) No reasonable definition of reality could be expected to permit this."

1) Here they lay out a possible objection to their criterion for reality, the one that they should have restricted it more as outlined in point (2).
2) EPR argue that, if we insist that "simultaneous elements of reality" is taken to mean elements of reality must be simultaneously measured or predicted, then their conclusion can not be reached. Therefore, according to EPR, their definition of "simultaneous elements of reality" does not mean they must be simultaneously measured or predicted.
3) In support of the above, EPR lay out a situation in which it is not possible to simultaneously measure or predict P and Q, and use it to show that if we insist that "simultaneous elements of reality" means they must simultaneously be measurable or predictable, then under this more restrictive definition (which is not the one they are proposing), the reality of a remote station can be changed by a measurement on a local station.
4) They then conclude that such a more restrictive definition is therefore not reasonable. According to EPR, therefore, any definition of reality which insists that elements of reality are only simultaneously real if they can be simultaneously measured, is a different definition from the EPR definition.

DrChinese

Jun20-10, 11:05 AM

Did you find the quote yet where you say Kracklauer claims Bell's inequalities are wrong because he used a comma instead of a vertical bar?

And I will tell you again, as I have said many times before, that trying to read Bell on a literal or character for character basis is absurd. You don't need Bell (2) to get to his result, there are other ways too. That is simply a single way to express one of the assumptions of local realism. If you substitute your own, you will still arrive at his conclusion. Ergo, attacking the specific form is a waste of time.

The correct way to read Bell is to consider his audience. He knew they would follow his thinking in their own manner. The key was that any reasonable set of local realistic assumptions - again supply your own - leads right back to the Bell conclusion: QM and LR are not compatible.

I have to tell you that Devil's quote about the "misleading" notation is pretty funny. I don't think I have EVER heard an attack like that from a professional about another professional. And as I say, it is ridiculous to boot!

DrChinese

Jun20-10, 11:11 AM

...

1) Here they lay out a possible objection to their criterion for reality, the one that they should have restricted it more as outlined in point (2).
2) EPR argue that, if we insist that "simultaneous elements of reality" is taken to mean elements of reality must be simultaneously measured or predicted, then their conclusion can not be reached. Therefore, according to EPR, their definition of "simultaneous elements of reality" does not mean they must be simultaneously measured or predicted.
3) In support of the above, EPR lay out a situation in which it is not possible to simultaneously measure or predict P and Q, and use it to show that if we insist that "simultaneous elements of reality" means they must simultaneously be measurable or predictable, then under this more restrictive definition (which is not the one they are proposing), the reality of a remote station can be changed by a measurement on a local station.
4) They then conclude that such a more restrictive definition is therefore not reasonable. According to EPR, therefore, any definition of reality which insists that elements of reality are only simultaneously real if they can be simultaneously measured, is a different definition from the EPR definition.

Yes, I quite agree with your parsing of EPR (as I said previously). And as I said, they assert that for their elements of reality to stand - a, b and c for example - they do not need to be simultaneously predictable with certainty. Bell accepted this definition, and I do too.

So then Bell went to work on a, b and c, and discovered that IF they existed simultaneously - as EPR asserts - then they could NOT match the QM expectation values. Ergo, either the EPR assertion is wrong OR there is spooky action at a distance. Take your pick!

billschnieder

Jun20-10, 01:51 PM

So then Bell went to work on a, b and c, and discovered that IF they existed simultaneously - as EPR asserts - then they could NOT match the QM expectation values. Ergo, either the EPR assertion is wrong OR there is spooky action at a distance. Take your pick!

But you are drawing the wrong conclusion. EPR did not say Bell's a, b, c must be simultaneous elements of reality. So I do not see which EPR assertion is claimed to be wrong here?

DevilsAvocado

Jun20-10, 03:13 PM

And I will tell you again, as I have said many times before, that trying to read Bell on a literal or character for character basis is absurd. You don't need Bell (2) to get to his result, there are other ways too. That is simply a single way to express one of the assumptions of local realism. If you substitute your own, you will still arrive at his conclusion. Ergo, attacking the specific form is a waste of time.

Thanks DrC, very well formulated words.

my_wan

Jun20-10, 11:15 PM

Yes, I quite agree with your parsing of EPR (as I said previously). And as I said, they assert that for their elements of reality to stand - a, b and c for example - they do not need to be simultaneously predictable with certainty. Bell accepted this definition, and I do too.

So then Bell went to work on a, b and c, and discovered that IF they existed simultaneously - as EPR asserts - then they could NOT match the QM expectation values. Ergo, either the EPR assertion is wrong OR there is spooky action at a distance. Take your pick!

Put this way I have to agree. The operational definition of realism as provided by EPR is fatally flawed beyond any reasonable doubt. I see this as an indication that observables are not non-degenerate. As such, the observables likely do, in a sense, lack a reality independent of the measurement. I don't see the generalization of this as a refutation of realism in general, nor that determinism is refuted. Though this, and other considerations, indicates that if elements of reality exist they are not directly accessible empirically and also most likely transfinite.

zonde

Jun21-10, 07:50 AM

As to GHZ:

"Surprisingly, in 1989 it was shown by Greenberger, Horne and Zeilinger
(GHZ) that for certain three- and four-particle states a conflict with
local realism arises even for perfect correlations. That is, even for those cases
where, based on the measurement on N −1 of the particles, the result of the
measurement on particle N can be predicted with certainty. Local realism
and quantum mechanics here both make definite but completely opposite
predictions.

"To show how the quantum predictions of GHZ states are in stronger conflict
with local realism than the conflict for two-particle states as implied by Bell’s
inequalities, let us consider the following three-photon GHZ state:

"We now analyze the implications of these predictions from the point of
view of local realism. First, note that the predictions are independent of the
spatial separation of the photons and independent of the relative time order
of the measurements. Let us thus consider the experiment to be performed
such that the three measurements are performed simultaneously in a given
reference frame, say, for conceptual simplicity, in the reference frame of the
source. Thus we can employ the notion of Einstein locality, which implies
that no information can travel faster than the speed of light. Hence the
specific measurement result obtained for any photon must not depend on
which specific measurement is performed simultaneously on the other two
or on the outcome of these measurements. The only way then to explain
from a local realistic point of view the perfect correlations discussed above
is to assume that each photon carries elements of reality for both x and y
measurements considered and that these elements of reality determine the
specific individual measurement result. Calling these elements of reality...

"In the case of Bell’s inequalities for two photons the conflict between local
realism and quantum physics arises for statistical predictions of the theory;
but for three entangled particles the conflict arises even for the definite predictions."

Zeilinger talking about GHZ in:
http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf

So GHZ does show that Local Realism makes specific predictions which are flat out contradicted by both QM and experiment.
I looked into experiments. Have to say that the one provided by unusualname was very helpful:
4 Particle GHZ violations of local realism were demonstrated back in 2003:
Experimental Violation of Local Realism by Four-Photon
Greenberger-Horne-Zeilinger Entanglement Phys. Rev. Lett. 91, 180401 (2003) [4 pages] (http://www.physics.princeton.edu/~mcdonald/examples/QM/zhao_prl_91_180401_03.pdf)
So as to what it demonstrates.
First of all it uses four modifications of experiment to demonstrate the point about LR.
Three experiments are used to make LR prediction for the fourth experiment.
That way you can't say that contradiction is achieved in single run.

Another thing is that as in any real experiment you don't have perfect result. So if you say that every single (4-fold coincidence) detection confirms QM and contradicts LR then in experiment we have situation like that:
"The experimental results in (f) are in agreement with the QM predictions (d) while in conflict with LR (e), with a visibility of 0.789+-0.012."
That means we have 90 detections out of every 100 that without any doubt confirm QM and 10 detections that without any doubt confirm LR.

That of course is not very serious interpretation of experimental results.

Next if we look at this sentence (from the quote you already provided):
"The only way then to explain from a local realistic point of view the perfect correlations discussed above is to assume that each photon carries elements of reality for both x and y measurements considered and that these elements of reality determine the specific individual measurement result."
First of all correlations are not perfect. If we compare visibility of HVVH and VHHV results they had around 0.98 visibility. Switching to L/R and H'/V' (+45°/-45°) base considerably reduced visibility i.e. around 0.80. So measurements in base that is incompatible with the base photons where created in are far from prefect correlations.
Second a local realistic point of view is not restricted to the point that each photon should carry all the relevant information.
For example, two photon combination can carry more information than simple sum of information from two single photons. That's because there is additional information in possible two photon configurations relative to each other.
So the point about "the only way" is not very serious.

JesseM

Jun21-10, 08:29 AM

So then your answer is that the left hand side of Bell's equation (2) is conditional with respect to (a,b) but marginal with respect to λ. And that outcome dependence between A and B exists when conditioned only on (a,b) but does not exist when conditioned on λ.
Yes.
So then the expression P(AB|a,b) will accurately reflect what the probability Bell is calculating in equation (2) on the LHS? Yes or no.
Yes.
And according to the chain rule of probability theory, the following expression is also true according to Bell's equation (2).

P(AB|a,b) = P(A|a,b)P(A|a,b,B)

Yes or no.
No, but if you meant to write P(AB|a,b) = P(B|a,b)P(A|a,b,B) then yes. This would actually be derived from the chain rule plus a few substitutions...the chain rule of probability would tell us this:

P(A,B,a,b)=P(A|B,a,b)P(B|a,b)P(a|b)P(b)

And from the definition of conditional probability we know P(a|b)*P(b)=P(a,b), and P(A,B,a,b)=P(AB|a,b)*P(a,b), so substitute these in the above equation, divide both sides by P(a,b) and we get P(AB|a,b)=P(A|B,a,b)P(B|a,b).

JesseM

Jun21-10, 08:59 AM

but that doesn't mean that it's assumed that correlations in measurements of the two particles can be explained by local hidden variables given to them by the source.
I agree. The relationship between the two particles isn't, strictly speaking, a 'local' hidden variable. It's a parameter that emerges, and is only relevant, in the joint context. It doesn't determine individual measurement probabilities.
But are you saying that this relationship is completely explained by some parameters that each particle got at the moment they were created at a common location by the source (like each starting out with the same 'polarization vector'), and where the parameter for each particle is itself a local variable that's carried around by the particle as it travels, either unchanging (like if each particle's own polarization vector continues to point in the same direction as the particle travels, at least until the particle is measured by a polarizer) or changing in a way that isn't causally affected by anything outside the particle's past light cone? If so this would be a local hidden variables explanation for the relationship between the particles.
And yet, isn't Bell's (2) requiring that the joint probability be modelled as the product of the two individual probabilities?
Only when conditioned on the hidden variables. In other words, P(AB|λ) is equal to the product of the two individual probabilities P(A|λ)*P(B|λ), but P(AB) is not equal to the product of the two individual probabilities P(A)*P(B). Do you understand the distinction?
If by "a locally produced relationship" you mean local hidden variables, then no, the fact that the statistics violate Bell's inequalities show that this cannot be the explanation.
I agree, per above. But the root cause of the relationship can be assumed to be a local common source.
I think you misunderstand, if the "root cause of the relationship" can be explained in terms of correlated local hidden variables assigned to each particle by the source, then is exactly what a "local hidden variables explanation" means, and this sort of explanation is ruled out if the statistics violate Bell's inequality.
The local hidden variable in any trial is the randomly varying (from trial to trial) polarization angle that, presumably, would, if known, allow precise predictions of individual results.
Can you explain how the "polarization angle" would interact with the detector angle to give the results? I've asked you this before and you haven't answered my question. Suppose the particle's polarization angle were 90 degrees while the detector angle was set to 60 degrees...what would this imply about the results? Would it mean the probability the particle passes through the detector is cos2(90-60), for example?
And it's suggested that the attribution of, and subsequent projection along, a 'principle' axis given a qualitative result at one end or the other is compatible with the assumptions of locality and predetermination (albeit not separable) regarding the jointly measured underlying parameter.
"suggested" by who? You? It certainly isn't suggested by orthodox QM or by anyone who agrees with Bell's analysis.
Why does the cos^2 theta rule following the attribution of the principle axis wrt a detection attribute work? Because the local hidden variable (as differentiated from the global parameter) can be any polarization angle. There are three vectors involved, call them, V1, V2, and V3, an optical vector and two unit vectors. They can be ordered in any way. One, the optical vector, is undetermined but assumed to be continuous between the two unit vectors.
I don't understand, what do these vectors represent physically in the problem? Is the optical vector supposed to be the hidden polarization angle, and the unit vectors are the angles of the two detectors? If not, what?
So, it seems logical to me, and compatible with the idea that everything is evolving according to the principle of locality, that the joint detection rate would be described by the cos^2 of the angular difference between the two unit vectors. As, I've said before, it's just accepted optics. And, because it's accepted optics, this is why the qm treatment for these types of setups is evaluated using Malus Law. I don't think that Bell's analysis rules this out, but rather that it's saying something about how this situation can be modelled.
Again, if you're just saying that each particle received the same "polarization vector" when they were created by the source, and that the polarization vectors are local properties of the particles that travel along with them and determine their response to the detectors, then this is definitely ruled out by Bell's analysis.
The equation (2) was based on the assumption of causal independence between the two particles (i.e measuring one does not affect the other), which was expressed as a condition saying they're statistically independent conditioned on the hidden variables L ...
I agree. The equation says that the two particles (ie., the sets of detection attributes denoted by A and B) are statistically independent.
No it doesn't. P(AB) can be different than P(A)P(B), meaning that they are statistically dependent in their probabilities when not conditioned on the hidden variables λ. For example, if A and B represent measurement results when both detectors are set to the same angle (say, 60 degrees), then if we know B, that automatically tells us the value of A with probability 1. Do you disagree?

It would really help if you would answer my question from post 781 (http://www.physicsforums.com/showthread.php?p=2764520#post2764520):
Do you agree it's possible to have a situation where P(AB) is not equal to P(A)*P(B), and yet P(AB|λ)=P(A|λ)*P(B|λ)? (and that this situation was exactly the type considered by Bell?) In this situation do you think there is a single correct answer to whether A and B are "statistically independent" or not? If so, what is that answer?
Can you address this please?
... but the equation is consistent with the idea that P(AB) can be different from P(A)*P(B).
Not sure what you mean.
Do you understand that if P(AB)=P(A)*P(B), that means A and B are statistically independent in their marginal probabilities (i.e. probabilities not conditioned on another variable like λ)? If so, my point is that if P(AB) is different from P(A)*P(B), that models a situation where A and B are statistically dependent in their marginal probabilities, equivalent to saying that P(A|B) is different from P(A) (i.e. learning the outcome B causes you to modify your estimate of the probability of A). Bell's equation certainly allows for this--it had better do so, because he was trying to explain the perfect correlation (the highest degree of statistical dependence possible) between A and B when both detectors were set to the same angle.

DrChinese

Jun21-10, 09:31 AM

But you are drawing the wrong conclusion. EPR did not say Bell's a, b, c must be simultaneous elements of reality. So I do not see which EPR assertion is claimed to be wrong here?

Yes, EPR says this. Of course they do not say a, b and c. Bell said that.

What EPR gives is a definition of an element of reality. By that definition, any angle setting measuring particle spin qualifies as an element of reality because it can be predicted with certainty. They then discuss whether 2 or more such elements of reality stand if they cannot be predicted with certainty simultaneously. They assert that such requirement is unreasonable. You are then left with the EPR definition of realism being that any observable which can be predicted with certainly maps to an element of reality.

That would include Bell's a, b and c, which qualify as elements of reality.

DrChinese

Jun21-10, 09:33 AM

Put this way I have to agree. The operational definition of realism as provided by EPR is fatally flawed beyond any reasonable doubt. I see this as an indication that observables are not non-degenerate. As such, the observables likely do, in a sense, lack a reality independent of the measurement. I don't see the generalization of this as a refutation of realism in general, nor that determinism is refuted. Though this, and other considerations, indicates that if elements of reality exist they are not directly accessible empirically and also most likely transfinite.

You could be correct, to a certain degree it is in fact a function of your definition of reality. I choose to believe that observables of a particle do not have simultaneous reality in the EPR sense of being elements of reality. In other words, I believe their reality is a function of the act of observation.

DrChinese

Jun21-10, 09:43 AM

Another thing is that as in any real experiment you don't have perfect result. So if you say that every single (4-fold coincidence) detection confirms QM and contradicts LR then in experiment we have situation like that:
"The experimental results in (f) are in agreement with the QM predictions (d) while in conflict with LR (e), with a visibility of 0.789+-0.012."
That means we have 90 detections out of every 100 that without any doubt confirm QM and 10 detections that without any doubt confirm LR.

That of course is not very serious interpretation of experimental results.

Hmmm, I am not sure how you get this because that is quite different than the actual conclusion. Visibility means the number that are detected. So that is 78.9% +/-1.2%. The actual result was a value of 4.433+/-0.032. This was greater than the Local Realistic max of 4 by 76 standard deviations.

So, no this was not a contest where 90% of events say one thing, and 10% say the opposite. 76 SD is overwhelming. 5 SD was enough for the 1982 Aspect experiment.

DevilsAvocado

Jun21-10, 09:57 AM

P(A,B,a,b)=P(A|B,a,b)P(B|a,b)P(a|b)P(b)

JesseM, you are PF Science Advisor with +6,000 posts, I beg you to read post #806 (http://www.physicsforums.com/showthread.php?p=2766674#post2766674) to get information about the source for billschnieder’s search for "knowledge and clarity".

Also read the following posts between billschnieder and me, and you will see beyond any doubt that the one and only source for billschnieder’s reasoning is Crackpot Kracklauer.

It may look like billschnieder is here to learn more about professional mainstream science, while billschnieder and Crackpot Kracklauer are in fact trying to dismiss Bell’s Theorem by cranky argumentation around the notation in Bell (2).

This is the cranky "truth", that you are currently engaged in:
Nonlocality, Bell's Ansatz and Probability (http://arxiv.org/abs/quant-ph/0602080)
Authors: A. F. Kracklauer
...
IX. CONCLUSIONS
...
And, once it is clear that Bell Inequalities cannot be derived using BAYES’ formula, the issue of nonlocality is rendered moot. This, in turn, resolves one conflict between two fundamental theories of modern physics—a conflict that on the face of it has the character typical of small, technical misunderstandings. This is only reinforced by the observation that there is no empirical evidence for nonlocality; that which has been taken as such, is in fact just an interpretation imposed indirectly on statistics derived from non kinematic data, but as argued herein, incorrectly.

I sincerely hope you realize the madness in continuing this kind of discussion, spread out all over PF.

my_wan

Jun21-10, 02:27 PM

You could be correct, to a certain degree it is in fact a function of your definition of reality. I choose to believe that observables of a particle do not have simultaneous reality in the EPR sense of being elements of reality. In other words, I believe their reality is a function of the act of observation.
Put this way I can respect such a position. I'm accustomed to thinking of observables as degenerate, since even before my teens or any notion of what QM was. The reasoning very closely followed your argument on the unobservability of independent variables I like to quote. I didn't know about the correspondence between statistical mechanics and classical thermodynamics at the time either, but the same basic reasoning was embedded in my thinking.

I'll give up what notions I must, but my feeling is that, in some sense, defining what ideas must go requires a comparison to various notions of realism, not just the one operationally defined by EPR. Much like what inspired Bell to derive his inequality. However, I must admit science has made astounding progress without it, and the crackpots that want to claim QM is not science are easy to lose patients with. That's enough to prove my feelings about it are not strictly true, but I still think comparing different notions of realism has value, even if only to define exactly where and how they break. I guess you could call it a minimalist approach to weirdness.

DrChinese

Jun22-10, 10:45 AM

I have started a new thread in Independent Research:

http://www.physicsforums.com/showthread.php?t=408231

This is on another subject off-topic to this thread. I wanted to invite my friends here to come over and give me your thoughts on a paper I have written on a proposed experiment. Thanks!

billschnieder

Jun22-10, 10:58 PM

No, but if you meant to write P(AB|a,b) = P(B|a,b)P(A|a,b,B) then yes.

That is what I meant, thanks for spotting the typo.

So then according to Bell, the P on the LHS ie equivalent to P(AB|a,b) in standard notation, where as we have agreed before a and b are place-holders for a specific value of the "random variables" a and b.

Now on age 405 of Bell's paper, just after equation (12) he writes the following:

P in (2) can not be less than -1. It can reach -1 at a = b, only when when
A(a,λ) = -B(b,λ)

How can a probability reach -1? Clearly then, according to Bell, P can not be a probability, since probabilities are only defined from 0 to 1. Do you agree? Yes or no?

JesseM

Jun23-10, 08:03 AM

How can a probability reach -1? Clearly then, according to Bell, P can not be a probability, since probabilities are only defined from 0 to 1. Do you agree? Yes or no?
OK, this is another minor quibble, the left side is actually an expectation value. I noted earlier in post #790 that A and B in (2) were just written as functions rather than probabilities:
I suppose I should point out that strictly speaking, in equation (2) Bell actually assumes the measurement outcomes are determined with probability 1 by the value of λ, so instead of writing P(A|a,λ) he just writes A(a,λ)
I neglected to note there that he allows the function A(a,λ) (and likewise B(b,λ)) to take values +1 or -1 depending on the measurement result (+1 for spin-up when measured with setting a and -1 for spin-down when measured with setting a, for example). So the notation P(a,b) on the left side of the equation is the expectation value for the product of A and B, which would be equivalent to a weighted sum of four different probabilities: P(A=+1, B=+1|ab)*(+1*+1) + P(A=+1, B=-1|ab)*(+1*-1) + P(A=-1, B=+1|ab)*(-1*+1) + P(A=-1, B=-1|ab)*(-1*-1)

This can be simplified to [P(A=+1, B=+1|ab) + P(A=-1, B=-1|ab)] - [P(A=+1, B=-1|ab) + P(A=-1, B=+1|ab)], and if you wish to do the substitution P(AB|a,b) = P(B|a,b)P(A|a,b,B), then it becomes:

[P(B=+1|a,b)P(A=+1|a,b,B=+1) + P(B=-1|a,b)P(A=-1|a,b,B=-1)] -
[(P(B=-1|a,b)P(A=+1|a,b,B=-1) + P(B=+1|a,b)P(A=-1|a,b,B=+1)]

DrChinese

Jun23-10, 09:07 AM

So then according to Bell, the P on the LHS ie equivalent to P(AB|a,b) in standard notation, where as we have agreed before a and b are place-holders for a specific value of the "random variables" a and b.

I thought you guys were using a, b as measurement settings, not hidden variables. Where/when did you switch to this notation? Lambda represents the hidden variables.

JesseM

Jun23-10, 09:42 AM

I thought you guys were using a, b as measurement settings, not hidden variables. Where/when did you switch to this notation? Lambda represents the hidden variables.
I'm still using them to mean measurement settings--perhaps Bill is too, and just called them "random variables" because it's assumed the measurement settings are to be chosen randomly by the two experimenters on each trial.

RUTA

Jun23-10, 03:12 PM

Sorry, I haven't been able to keep up with this thread. I'm out of town this week and without access to his papers, but a couple of people have asked me to explain where Kracklauer is mistaken.

Again, my last exchange with him was some years ago concerning one of his published papers. In that paper I pointed out to him that his statistics assumed information concerning the detector settings at all sites was available at all sites. He confirmed this was correct. I told him that there is no mystery if this is true (and sent him a quote from Mermin to this effect, since I'm not an authority). I told him that experimentalists understand that this would have to be avoided and change polarizer settings at very high frequencies so that information concerning settings at remote sites is not available prior to recording relevant outcomes. He said I didn't know what I was talking about, so I sent him a quote from one of Aspect's papers making this same claim and never heard from him again.

That's all I know about Kracklauer.

I may not be able to tend to PF in the immediate future because I'm teaching, doing research and preparing for a conference in July. I'll get back to you after my summer research students and class are finished :-)

billschnieder

Jun23-10, 05:28 PM

OK, this is another minor quibble, the left side is actually an expectation value. I noted earlier in post #790 that A and B in (2) were just written as functions rather than probabilities

I neglected to note there that he allows the function A(a,λ) (and likewise B(b,λ)) to take values +1 or -1 depending on the measurement result (+1 for spin-up when measured with setting a and -1 for spin-down when measured with setting a, for example). So the notation P(a,b) on the left side of the equation is the expectation value for the product of A and B, which would be equivalent to a weighted sum of four different probabilities: P(A=+1, B=+1|ab)*(+1*+1) + P(A=+1, B=-1|ab)*(+1*-1) + P(A=-1, B=+1|ab)*(-1*+1) + P(A=-1, B=-1|ab)*(-1*-1)

There now appears to be two different meanings ascribed to what Bell is doing in equation (2), which I asked you earlier several times:
1) Bell is marginalizing with respect to λ.
2) Bell is calculating an expectation value for the probability P(AB|ab)
Which one is it? I see only a single integral and no summation, and you need one for each if you are doing both.

JesseM

Jun23-10, 08:54 PM

There now appears to be two different meanings ascribed to what Bell is doing in equation (2), which I asked you earlier several times:
1) Bell is marginalizing with respect to λ.
2) Bell is calculating an expectation value for the probability P(AB|ab)
Which one is it? I see only a single integral and no summation, and you need one for each if you are doing both.
Yes, I didn't notice before that the left side of (2) was an expectation value rather than a straight probability. But it's not quite an expectation value for P(AB|ab) as you suggest, it's actually an expectation value for A*B, which is equivalent to a sum over all possible combinations of values for A and B of the quantity A*B*P(AB|a,b). Remember, though, Bell is assuming that the value of A and B is completely determined by the values of a, b, and λ. So, the integral on the right of (2) is exactly equivalent to the following weighted sum of four integrals:

(+1)*(+1)\int P(A=+1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda +
(+1)*(-1)\int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda +
(-1)*(+1)\int P(A=-1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda +
(-1)*(-1)\int P(A=+1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda

The reason this works is because for any given value of λ, say λ=λi, three of the probabilities in the four integrals above will be equal to zero, while the other probability will be equal to 1. So by splitting up the single integral into the four above, you aren't overcounting or undercounting A*B*P(λ) for any specific value of λ, you're counting it exactly once. This is easier to see if you suppose λ can only take a discrete set of values from 0 to N, so the integral on the right side of (2) can be replaced by the sum \sum_{i=0}^N A(a,\lambda_i)*B(b,\lambda_i)*P(\lambda_i). Then if a,b,λ completely determine the values of A and B (which each take one of two values +1 or -1), that means the four-term sum (+1)*(+1)*P(A=+1,B=+1|a,b,λi) + (+1)*(-1)*P(A=+1,B=-1|a,b,λi) + (-1)*(+1)*P(A=-1,B=+1|a,b,λi) + (-1)*(-1)*P(A=-1,B=-1|a,b,λi) will always be equal to A(a,λi)B(b,λi) for each specific value of λi [for example, if a,b,λi determine that A=+1 and B=-1, then (+1)*(+1)*P(A=+1,B=+1|a,b,λi) + (+1)*(-1)*P(A=+1,B=-1|a,b,λi) + (-1)*(+1)*P(A=-1,B=+1|a,b,λi) + (-1)*(-1)*P(A=-1,B=-1|a,b,λi) = (+1)*(+1)*0 + (+1)*(-1)*1 + (-1)*(+1)*0 + (-1)*(-1)*0 = (+1)*(-1) = A(a,λi)B(b,λi)]. So, if we substitute the four-term sum in for the individual term A(a,λi)B(b,λi) in the sum over all possible values of λ I wrote above, we get:

\sum_{i=0}^N [(+1)*(+1)*P(A=+1,B=+1|a,b,\lambda_i)\,+\,(+1)*(-1)*P(A=+1,B=-1|a,b,\lambda_i)+ \,(-1)*(+1)*P(A=-1,B=+1|a,b,\lambda_i)\,+\,(-1)*(-1)*P(A=-1,B=-1|a,b,\lambda_i)]*P(\lambda_i)

Which can be split up into the following four sums:

\sum_{i=0}^N (+1)*(+1)*P(A=+1,B=+1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (+1)*(-1)*P(A=+1,B=-1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (-1)*(+1)*P(A=-1,B=+1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (-1)*(-1)*P(A=-1,B=-1|a,b,\lambda_i)*P(\lambda_i)

...which is just the discrete version of the four integrals I wrote before.

So, the left side is an expectation value which can be broken up into a weighted sum of four probabilities of the form P(AB|ab), and the right side can be broken up into a weighted sum of four integrals or sums over all possible values of λ of terms of the form P(AB|a,b,λ). For example, on the left side one of the four weighted probabilities is (+1)*(-1)*P(A=+1,B=-1|ab), and on the right side one of the four weighted integrals is (+1)*(-1)\int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda. So if you take the marginalization equation P(A=+1,B=-1|a,b) = \int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda and then multiply both sides by A*B=(+1)*(-1) and add this equation to three other marginalization equations where both sides have been multiplied by the corresponding value of A*B, you get something mathematically equivalent to equation (2) in Bell's proof.

billschnieder

Jun23-10, 10:49 PM

But it's not quite an expectation value for P(AB|ab) as you suggest, it's actually an expectation value for A*B, which is equivalent to a sum over all possible combinations of values for A and B of the quantity A*B*P(AB|a,b)....

One unanswered question and a few comments:
This "thing" which Bell calculates in equation (2), which you now say is an expectation value and from my initial glimpse of your explanation, it appears to be. Is the equation as it stands indicating that the numerical value represents what is obtained by measuring a specific pair of settings (ai, bi) a large number of times, or is it indicating that expectation value is what will be obtained my measuring a large number of different pairs of angles (ai,bi)? Or do you think the two are equivalent.

As a follow up of the above, in order to understand what you understand the expected value to mean: If I perform a survey in which respondents answer either ("yes") or ("no") and I know that both outcomes are equally likely, what would you say the expectation value of the survey result?

JesseM

Jun24-10, 06:30 AM

One unanswered question and a few comments:
This "thing" which Bell calculates in equation (2), which you now say is an expectation value and from my initial glimpse of your explanation, it appears to be. Is the equation as it stands indicating that the numerical value represents what is obtained by measuring a specific pair of settings (ai, bi) a large number of times, or is it indicating that expectation value is what will be obtained my measuring a large number of different pairs of angles (ai,bi)? Or do you think the two are equivalent.
The first, I think he's calculating the expectation value for some specific pair of settings. If he wanted to talk about the expectation value for a variety of different ai's I think he'd need to have a sum over different values of i in there.
As a follow up of the above, in order to understand what you understand the expected value to mean: If I perform a survey in which respondents answer either ("yes") or ("no") and I know that both outcomes are equally likely, what would you say the expectation value of the survey result?
You have to assign a number to each possibility to have an expectation value. For instance, if you let yes=1 and no=2, then if they're equally likely the expectation value is 1.5, but if you let yes=-1 and no=-1, the expectation value is 0. In Bell's case he's doing something like "result of particle's measurement is spin-up"=+1 and "result of particle's measurement is spin-down"=-1.

billschnieder

Jun24-10, 10:19 AM

The first, I think he's calculating the expectation value for some specific pair of settings. If he wanted to talk about the expectation value for a variety of different ai's I think he'd need to have a sum over different values of i in there.
The first, I think he's calculating the expectation value for some specific pair of settings. If he wanted to talk about the expectation value for a variety of different ai's I think he'd need to have a sum over different values of i in there.
So then, let us consider a specific pair of settings (a, b), and presume that we have calculated an expectation value from equation (2) of Bell's paper, say E(a,b). From what you have explained above, there is going to be a specific probability distribution P(λi) over which E(a,b) was obtained, since the corresponding P(AB|ab) which you obtained your E(a,b) from, was obtained by marginalizing over a specific P(λi) . Do you agree?

Fast forward to then to the resulting CHSH inequality
|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

In your opinion then, is the P(λi) the same for each of the above terms, or do you believe it doesn't matter.

JesseM

Jun24-10, 01:32 PM

So then, let us consider a specific pair of settings (a, b), and presume that we have calculated an expectation value from equation (2) of Bell's paper, say E(a,b). From what you have explained above, there is going to be a specific probability distribution P(λi) over which E(a,b) was obtained, since the corresponding P(AB|ab) which you obtained your E(a,b) from, was obtained by marginalizing over a specific P(λi) . Do you agree?
If we wanted to calculate a precise expectation value, yes we'd need a specific probability distribution on the hidden variables, as well as knowledge of what value of A and B went with each possible value of λ. However, the inequalities he derives would apply to any specific choice of probability distribution in a local realist universe.
Fast forward to then to the resulting CHSH inequality
|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

In your opinion then, is the P(λi) the same for each of the above terms, or do you believe it doesn't matter.
The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).

billschnieder

Jun24-10, 11:13 PM

The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).
So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?

Do you believe, P(λi) is always uniform between all the terms in the inequality, when calculating from data acquired in Aspect-type experiments?

JesseM

Jun25-10, 09:45 AM

So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same.
When you suggest the possibility that P(λi) could be "different for at least one of the terms in the inequality", that would imply that P(λi) depends on the choice of detector settings, since each expectation value is defined relative to a particular combination of detector settings. Am I understanding correctly, or are you talking about something else?

If I am understanding you right, note that it's generally accepted that one of the assumptions needed in Bell's theorem is something called the "no-conspiracy assumption", which says the decisions about detector settings should not be correlated with the values of the hidden variables. For example, this page (http://www.iep.utm.edu/epr/#Assumption4) on EPR/Bell says:
Assumption 4. The choices between the measurement setups in the left and right wings are entirely autonomous, that is, they are independent of each other and of the assumed elements of reality that determine the measurement outcomes.

Otherwise the following conspiracy is possible: something in the world pre-determines which measurement will be performed and what will be the outcome. We assume however that there is no such a conspiracy in our world.
And later on the same page (http://www.iep.utm.edu/epr/#SH5a):
a. Conspiracy
There is an easy resolution of the EPR/Bell paradox, if we allow the conspiracy that was prohibited by Assumption 4 (Brans 1988; Szabó 1995). It is hard to believe, however, that the “free” decisions of the laboratory assistants in the left and right wings depend on the value of the hidden variable which also determines the spins of the two particles.
Likewise the fairly rigorous-looking derivation Minimal assumption derivation of a Bell-type inequality (http://arxiv.org/abs/quant-ph/0312176) mentions this assumption on p. 6:
D. No conspiracy

The events of type C^{+-}_{ii} are not supposed to be influenced by the measuring operations Li and Rj . One reason for this assumption is that the measurement operations can be chosen arbitrarily before the particles enter the magnetic field of the Stern-Gerlach magnets and that an event of type C^{+-}_{ii} is assumed to happen before the particles arrive at the magnets. Therefore a causal influence of the measurement operations on events of type C^{+-}_{ii} would be tantamount to backward causation. Also an inverse statement is supposed to hold: The event types C^{+-}_{ii} are assumed not to be causally relevant for the measurement operations. This is meant to rule out some kind of “cosmic conspiracy” that whenever an event of type C^{+-}_{ii} is instantiated, the experimenter would be “forced” to use certain measurement operations. This causal independence between C^{+-}_{ii} and the measurement operations is assumed to imply the corresponding statistical independence. The same is assumed to hold also for conjunctions of common cause event types. We refer to this condition as no conspiracy (NO-CONS).
So, I agree the inequality can only be assumed to hold if the choice of detector settings and the value of the hidden variables are statistically independent (which means the probability distribution P(λi) does not change depending on the detector settings), but this is explicitly included as an assumption in the more rigorous modern derivations. If you dispute that a "conspiracy" of the type being ruled out here would in fact have some very physically implausible features so that it's reasonable to rule it out, I can give you some more detailed arguments for why it's so implausible.

billschnieder

Jun25-10, 10:27 AM

You are wondering off now, JesseM. Try not to pre-empt the discussion. The question I asked should have a straightforward answer. The reason why P(λi) might be different shouldn't affect the answer you give to my question. If you believe P(λi) will be different when a conspiracy is involved, then you should have no problem admitting that Bell's inequalities do not apply to situations in which there is conspiracy.

Here it is again:

So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?

Do you believe P(λi) can different between the terms in a locally causal universe if and only if conspiracy is involved?

JesseM

Jun25-10, 12:50 PM

You are wondering off now, JesseM. Try not to pre-empt the discussion.
You are acting like a bully, Bill. You don't have dictatorial control over the terms of "the discussion", we are both allowed to contribute whatever we think is relevant. If you want to be a dictator who gets to tell me what I am and am not allowed to discuss, what questions from you I must answer, but who refuses to address topics/questions I think are relevant if you don't immediately spot the relevance yourself, I'm not going to participate in that sort of game.
The reason why P(λi) might be different shouldn't affect the answer you give to my question.
True, but for anyone following along it may still help their understanding of the physical meaning of what we're talking about to point out that the only way P(λi) could be different for the four expectation values would be if there are different probability distributions for different combinations of detector settings. We can show this with pure math, no physical reasoning whatsoever. After all, as I explained in post #855, E(a,b) for some specific pair of detector settings a and b is just defined as (sum over all possible values of A and B) of A*B*P(AB|a,b), or equivalently the same sum but for A*B*P(A,B,a,b)/P(a,b). And we can marginalize (http://en.wikipedia.org/wiki/Conditional_probability) P(A,B,a,b) over λ by setting it equal to \int P(A,B,\lambda,a,b)\,d\lambda, which by the chain rule of probability (http://en.wikipedia.org/wiki/Chain_rule_(probability)) is equal to \int P(A,B|\lambda,a,b)P(\lambda|a,b)P(a|b)P(b)\,d\lamb da, and P(a|b)P(b) = P(a,b) so this reduces to \int P(A,B|\lambda,a,b)P(\lambda|a,b)P(a,b)\,d\lambda. So, (sum over all possible values of A and B) of A*B*P(A,B,a,b)/P(a,b) is equal to (sum over all possible values of A and B) of (A*B/P(a,b))*\int P(A,B|\lambda,a,b)P(\lambda|a,b)P(a,b)\,d\lambda, and dividing out P(a,b) gives (sum over all possible values of A and B) of A*B\int P(A,B|\lambda,a,b)P(\lambda|a,b)\,d\lambda. This looks just like the sum of four integrals in #855 which I said was equivalent to the right side of equation (2) in Bell's paper, except with P(λ|a,b) substituted in for P(λ). Along the same lines, if you wanted to calculate the expectation value for a different pair of settings like a' and b', (sum over all possible values of A and B) of A*B\int P(A,B|\lambda,a',b')P(\lambda|a',b')\,d\lambda. So, if there was a different P(λ) for each version of equation (2) calculating the expectation value for each possible pair of detector settings, just using pure math we can see that the only way this could happen was if P(λ|a,b) for one pair of detector settings is different than P(λ|a',b') for a different pair of detector settings.
If you believe P(λi) will be different when a conspiracy is involved, then you should have no problem admitting that Bell's inequalities do not apply to situations in which there is conspiracy.
Didn't I already "admit" that in my last post? Read again:
So, I agree the inequality can only be assumed to hold if the choice of detector settings and the value of the hidden variables are statistically independent (which means the probability distribution P(λi) does not change depending on the detector settings)
Do you believe P(λi) can different between the terms if and only if conspiracy is involved?
Yes, since "conspiracy" is just defined as P(λ|a,b) being different from P(λ). I showed above using pure math (no physics) that P(λ) can be different between the integrals Bell uses to calculate expectation values only if P(λ|a,b) is different from P(λ), i.e if there is a "conspiracy".

billschnieder

Jun25-10, 01:36 PM

You are acting like a bully, Bill. You don't have dictatorial control over the terms of "the discussion"
I haven't twisted your arm to force you to comply with my requests. All I am trying to do is have a focused discussion, which apparently is very very difficult for you to do. You have been cooperating until now, why the sudden change of heart. I ask you a simple question to which you either agree or disagree, and you go back and pull already settled issues, raise new issues, with tons of equations into the response as if you want to drown the the real issue. I understand you like to write a lot and you have every right, but for once could you please make an effort to just stick to the point?

So then, I will assume that the last few posts did not happen, and I will consider that the responses moving forward are as follows:

So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?
... I agree ...
Do you believe P(λi) can different between the terms if and only if conspiracy is involved?
Yes ...

See how short and to the point this would have been. You would have saved yourself all the typing effort, and to boot, we don't have to start a new rabbit trail about the meaning of "conspiracy"! Your answer presented as precisely above would already have incorporated your view about what "conspiracy" means, but the fact that it is precise enables use to continue the discussion on topic. But if you now define conspiracy in a manner that I don't agree with, I will be forced to challenge it because if I don't it may appear as though I agree with that definition, then we end up 20 posts later, discussing whose definition of "conspiracy" is correct, having left the original topic. The more you write, the more things need to be challenged in your posts and the more off-topic the discussions will get. This is why I insist that the discussion be focused. I hope you will recognize and respect this, otherwise there is no point continuing this discussion.

JesseM

Jun25-10, 02:55 PM

I haven't twisted your arm to force you to comply with my requests.
The only way a person can "twist someone's arm" over the internet is by adopting a demanding or aggressive tone whenever the other person doesn't comply with their requests, and that's exactly what you've done.
All I am trying to do is have a focused discussion, which apparently is very very difficult for you to do. You have been cooperating until now, why the sudden change of heart. I ask you a simple question to which you either agree or disagree, and you go back and pull already settled issues, raise new issues, with tons of equations into the response as if you want to drown the the real issue.
Again, I bring these things up because I want anyone else reading the discussion to understand exactly what various conditions entail. I have answered your questions, and you are perfectly free to ignore the extra points I make if they don't seem relevant to you, so there is absolutely no need for you to berate me and imply I am trying to obscure the issue just because I don't confine myself to the shortest possible answers. Like I said, it just seems like bullying for the sake of bullying, unless you can give a practical rationale for why including some extra points in a post that already answers all the questions you asked is going to prevent you from developing whatever point you intend to make.
So then, I will assume that the last few posts did not happen, and I will consider that the responses moving forward are as follows:
So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?

... I agree ...

Do you believe P(λi) can different between the terms if and only if conspiracy is involved?

Yes ...
See how short and to the point this would have been. You would have saved yourself all the typing effort, and to boot, we don't have to start a new rabbit trail about the meaning of "conspiracy"!
There is no "rabbit trail" about the meaning, it's a technical term with a single well-defined meaning in the context of a discussion of assumptions needed in deriving Bell inequalities. "Conspiracy" in this context is defined in terms of P(λ) being different from P(λ|ab) (i.e. a statistical dependence between hidden variables and measurement state), I was just pointing out that this official definition is actually equivalent to your own comment about P(λ) being different for different expectation values, but it's not instantly obvious that they're equivalent, so for pedagogical reasons I was explaining why (again, even if this explanation is not interesting to you it may be helpful for others reading).

And speaking of "short and to the point", there's no need for you to elaborately berate me about how much time I could have saved or how you will "assume that the last few posts did not happen", you could just quote the part of the posts that are relevant to you and respond to that.
Your answer presented as precisely above would already have incorporated your view about what "conspiracy" means, but the fact that it is precise enables use to continue the discussion on topic.
But as I said, it wouldn't have made clear how the standard definition relates to the fact that P(λ) can only differ for different expectation values if a "conspiracy is involved" (which is not the standard way of defining it).
But if you now define conspiracy in a manner that I don't agree with, I will be forced to challenge it because if I don't it may appear as though I agree with that definition, then we end up 20 posts later, discussing whose definition of "conspiracy" is correct, having left the original topic.
There would be no need for an extended debate about the meaning of a technical term like "conspiracy", a condition that can be expressed as a simple equation, any more than there would about other technical terms that can be expressed in terms of equations like "energy" or "force". Our debate about "probability" was because we weren't debating the purely mathematical aspects (like the fact that the sum of probabilities of all possible outcomes must always be 1, and individual probabilities can never be negative), but were debating philosophical interpretations of the meaning of the mathematical symbols and how they apply to the real world.
The more you write, the more things need to be challenged in your posts and the more off-topic the discussions will get. This is why I insist that the discussion be focused. I hope you will recognize and respect this, otherwise there is no point continuing this discussion.
I don't recognize that the hypothetical you mention actually applies to this discussion. In fact you didn't need to challenge anything in my definition of the no-conspiracy assumption, so going on about how I need to keep it short is completely gratuitous here. In other situations where you have challenged me on less straightforward mathematical issues, I would say that the debates were central to the main issues we were disagreeing about, like how the frequentist definition of a "population" of hypothetical experiments shows why an Aspect-type experiment will naturally be a "fair sample", something you were continually asserting it wouldn't be unless we precisely controlled for the values of all hidden variables (just bringing this up as an example, the actual debate on this point can continue on the other thread).

billschnieder

Jun25-10, 10:47 PM

Well JesseM,
Thank you then for your cooperation so far, and I won't bother you again. Unfortunately I can not continue the discussion like this when you are unable to stay on topic. Despite my complaints, you continue in like manner as if though secretly hope I will abandon the discussion. So you get your wish. Anyone else following the discussion who is interested in finding out where I was going with the line of questioning is welcome to PM me.

JesseM

Jun25-10, 11:03 PM

Despite my complaints, you continue in like manner as if though secretly hope I will abandon the discussion. So you get your wish.
It's not my wish that the discussion stop, it's just that you haven't provided any practical justification for why I should change my posting style (as I already pointed out, I did answer all your questions so nothing is stopping you from just responding to the parts of my posts that are relevant to your argument and ignoring the rest), and your requests amount to little more than "shut up and answer exactly the way I tell you to, not the way you want to" (and the tone of your requests is only marginally more civil than that). Again it pretty much just seems like bullying to me, and while I'm happy to continue the discussion in a civil and adult manner, I'm not going to cede total control over my own posting style just because you bark orders at me.

ThomasT

Jun26-10, 12:12 AM

Could you please show me one title, link, or paper-id?One? There's a bunch, and they're legit. As ajw1 pointed out, you're the one who provided the links in the first place. (thanks again) You might consider clicking on the links to some of the papers and actually reading them.

--- snip ---

... Crackpot Kracklauer is just too much, and I will never back off from this, never.What is it? Do you have some personal history with this guy or something?

Supporting Crackpot Kracklauer must be against all and everything in Physics Forums Global Guidelines ...You've presented what so far seems to be a groundless personal attack on a physicist who's got some interesting papers (several in peer reviewed journals), the conclusions of which are, apparently, contrary to certain views which, apparently, you've emotionally bonded with. So, who's the crackpot deviating from the PF guidelines?

Now, DA, I'm not saying you're a crackpot, in fact my understanding is that you've gotten into the Bell-EPR stuff relatively recently. This was the case, at one time or another, for everyone (including Zeilinger, DrC, Kracklauer, RUTA, JesseM, and even Einstein and Bell) who's been interested in the implications of a certain, call it 'realistic', view of how theories of quantum experimental phenomena might be formulated. These considerations involve semantics, logic and physics. What I ask of you is that you not attack anyone as a 'crackpot' until you fully understand everything involved in their particular view. This will take some time. As DrC might confirm, I've revisited this topic several times, have changed my approach (my way of thinking about it) several times, and I'm still not sure that I fully understand everything involved. So, please, don't be so quick to dismiss someone as a 'crackpot' unless and until you fully understand exactly what it is that they're saying. And, when you do fully understand the arguments involved, then I think that you will just deal with the arguments.
I hope that you stay interested in this and continue to learn, as I hope to do.

In connection with this, I think it's important that I learn as much about OPDC as I can. That's my next agenda, and so after my next few posts in this thread I won't be contributing to it.

ThomasT

Jun26-10, 12:18 AM

DrC, thanks for your elaboration on your 'requirement' for candidate local realistic models of entanglement. I still don't understand what you're saying. I think the best thing to do is to start a new thread on this. Which I will do tonight.

ThomasT

Jun26-10, 12:19 AM

ThomasT

Jun26-10, 12:35 AM

... his statistics assumes that knowledge of detector settings is available at both detection sites.

This 'global' knowledge is available via the data processing and analysis. Isn't it?

I wrote him a detailed email explaining that experiments change polarization settings at very high frequencies precisely so info about Alice's detector settings is not available to Bob and vice versa.

While it's true that the settings are changed rapidly and randomly, it's also true that for any given time-matched pair of detection attributes there's an associated pair of polarizer settings. The statistics associated with any given run would include all of that. "Wouldn't they?

I've only just glanced at the paper so far. If you can point out where his error appears, that would be appreciated.

Sorry, I haven't been able to keep up with this thread. I'm out of town this week and without access to his papers, but a couple of people have asked me to explain where Kracklauer is mistaken.

Again, my last exchange with him was some years ago concerning one of his published papers. In that paper I pointed out to him that his statistics assumed information concerning the detector settings at all sites was available at all sites. He confirmed this was correct. I told him that there is no mystery if this is true (and sent him a quote from Mermin to this effect, since I'm not an authority). I told him that experimentalists understand that this would have to be avoided and change polarizer settings at very high frequencies so that information concerning settings at remote sites is not available prior to recording relevant outcomes. He said I didn't know what I was talking about, so I sent him a quote from one of Aspect's papers making this same claim and never heard from him again.

That's all I know about Kracklauer.

I may not be able to tend to PF in the immediate future because I'm teaching, doing research and preparing for a conference in July. I'll get back to you after my summer research students and class are finished :-)Please reply to my specific questions.

You stated that Kracklauer's "statistics assumed information concerning the detector settings at all sites was available at all sites." Isn't it true that at the conclusion of a run this info is available ... to the global observer, the experimenter? So, I'm suggesting that maybe Kracklauer's objection to your criticism was valid.

As I've asked, if you can point out the specific error in Kracklauer's analysis, then that woud be appreciated.

JesseM

Jun26-10, 08:25 AM

JesseM, thanks for your thoughtful post #842. I don't want to nitpick (but I will be thinking about the questions you've posed). I want you to understand why I don't understand why some people present Bell's theorem as implying that nature is nonlocal. I look at the experimental setups involved and I see a local optical 'explanation' for the observed correlations. I've talked to maybe two dozen working experimental physicists about this and they agree.
Well, can you present your local optical explanation in detail, either here or on a new thread? You'll need to present it in enough quantitative detail that we can calculate what measurement outcome will occur (or what the probability is for different outcomes) given knowledge of a detector settings and the local hidden variables at the location of the measurement (like the 'polarization vector' of the particle being measured, if that's your hidden variable).
As far as the form of Bell's (2) is concerned, it represents the experimental situation in a factorable form, which means that it reduces to an expression that the data sets A and B are independent. Is this how you see it?
No, A and B are not independent in their marginal probabilities (which determine the actual observed frequencies of different measurement outcomes), only in their probabilities conditioned on λ. I've asked whether you understand the distinction a bunch of times and you never answer. If you'd like to see a numerical example where there's a statistical dependence in marginal probabilities but not when conditioned on some other variable I could easily provide it.

RUTA

Jun26-10, 10:45 AM

Please reply to my specific questions.

You stated that Kracklauer's "statistics assumed information concerning the detector settings at all sites was available at all sites." Isn't it true that at the conclusion of a run this info is available ... to the global observer, the experimenter? So, I'm suggesting that maybe Kracklauer's objection to your criticism was valid.

As I've asked, if you can point out the specific error in Kracklauer's analysis, then that woud be appreciated.

That the information is available AFTER the fact doesn't bear on a possible CAUSE for the correlations. The point is that the detector setting at site A is NOT available to site B BEFORE the detection event occurs at site B. If this information is available prior to detection, the correlations in the outcomes can be orchestrated to violate Bell's inequality. No one disputes this fact -- you have to keep the outcome at each site dependent ONLY upon information AT THAT SITE to have the conundrum about their correlations.

Thus, there are generally two ways to account for EPR-Bell correlations. 1) The detection events are separable and you have superluminal exchange of information. 2) The detection events are not separable, e.g., the spin of the entangled electrons is not a property of each electron. The first property is often called "locality" and the second property "realism."

Kracklauer's statistics simply assumed detector setting information was available at each site prior to detection outcomes. When I discussed this with him at a conference, he was adamant that the outcome at each site was contingent upon outcomes and settings at other sites so the "proper" statistics had to contain this fact. His whole argument was that we needed to use the "proper" statistics and the mystery would disappear. His "proper" statistics just assume global knowledge of detector settings. But, unless he has a proposal for how this information is available, he has done nothing to resolve the mystery. How is this information available? FTL signals or nonseparability? Or both? What is the mechanism? All he had was a statistical counterpart to the mystery, although it could be published if no one else had pointed this out. But, nothing was "resolved."

DevilsAvocado

Jun26-10, 10:54 PM

One? There's a bunch, and they're legit. As ajw1 pointed out, you're the one who provided the links in the first place. (thanks again) You might consider clicking on the links to some of the papers and actually reading them.

Here’s the list (http://arxiv.org/find/all/1/all:+Kracklauer/0/1/0/all/0/1) of Crackpot Kracklauer’s 21 papers on arXiv.org. Where is the "bunch" of peer reviewed papers? These two are peer reviewed before 2000:

http://i49.tinypic.com/egz343.png

And the only one peer reviewed after 2000, is this one:

http://i47.tinypic.com/2whmntl.png

These 2 mumbling pages of a rebuttal of David Mermin (http://en.wikipedia.org/wiki/David_Mermin) can hardly be called a "bunch", can it? Crackpot Kracklauer is apparently against the whole scientific community, with his Non-loco Physics (http://www.nonloco-physics.000freehosting.com/), and this was his last paper that made it thru a scientific journal.

(Note that Foundations of Physics (http://www.springer.com/physics/journal/10701) had a serious controversy in the past (http://en.wikipedia.org/wiki/Foundations_of_Physics#Controversy_in_the_past), which resulted in the takeover of Gerard ‘t Hooft as Editor-in-Chief in 2007.)

What is it? Do you have some personal history with this guy or something?

The question is why you risk all your credibility for a 100% crackpot as A. F. Kracklauer? Didn’t you watch the video (http://video.google.com/videoplay?docid=-1112934842741515675)? Didn’t you visit his homepage (http://www.nonloco-physics.000freehosting.com/)? Crackpot Kracklauer thinks QM mainstream physics are wrong! And we are not talking a little 'disagreement' around Bell (2) – everything is wrong according to Crackpot Kracklauer!

A completely lost "independent researcher" with a crazy homepage at freehosting.com, and you are supporting this guy!? Why??

I know you dislike nonlocality very much, and are fighting to find a "solution". But don’t you think this is a 'little' too "far out"? This man has a mental problem:
A. F. Kracklauer - Non-loco Physics
"Loco'' (Spanish for 'crazy'). Contemporary Physics is vexed by some really "loco'' ideas, with nonlocality and asymmetric aging leading the list.
...
A second motivation is sociological. Some see a mutual interplay between fundamental science and the development of civilization. If this notion is accepted, then physics, as a social enterprise, has some responsibility to support those things making positive contributions to civilization by being the exemplar of rationality, contrary to the current fashion of spewing forth ever new and more exotic pop-psycho-sci-fi contrivances, i.e., loco ideas.

Convinced yet? No? How about this 'excellent' paper by Crackpot Kracklauer?

(Edit: Crackpot Kracklauer’s fancy host freehosting.com doesn’t allow direct linking to PDF, use Google link (http://www.google.com/search?hl=en&q=http%3A%2F%2Fwww.nonloco-physics.000freehosting.com%2Fws01.pdf&aq=f&aqi=&aql=&oq=&gs_rfai=) instead.)
"Complementarity" or Schizophrenia: is Probability in Quantum Mechanics Information or Onta? (http://www.nonloco-physics.000freehosting.com/ws01.pdf)
ABSTRACT. Of the various “complimentarities” or “dualities” evident in Quantum Mechanics (QM), among the most vexing is that afflicting the character of a ‘wave function,’ which at once is to be something ontological because it diffracts at material boundaries, and something epistemological because it carries only probabilistic information. Herein a description of a paradigm, a conceptual model of physical effects, will be presented, that, perhaps, can provide an understanding of this schizophrenic nature of wave functions. It is based on Stochastic Electrodynamics (SED), a candidate theory to elucidate the mysteries of QM. The fundamental assumption underlying SED is the supposed existence of a certain sort of random, electromagnetic background, the nature of which, it is hoped, will ultimately account for the behavior of atomic scale entities as described usually by QM.
In addition, the interplay of this paradigm with Bell’s ‘no-go’ theorem for local, realistic extentions of QM will be analyzed.

Have you ever heard of the "SCHIZOPHRENIC NATURE of wave functions" before????

Still not convinced? How about this?

(Edit: Crackpot Kracklauer’s fancy host freehosting.com doesn’t allow direct linking to PDF, use Google link (http://www.google.com/search?hl=en&q=http%3A%2F%2Fwww.nonloco-physics.000freehosting.com%2Fabort.pdf&btnG=Search&aq=f&aqi=&aql=&oq=&gs_rfai=) instead.)
The quantum mechanics of abortion (http://www.nonloco-physics.000freehosting.com/abort.pdf)
Does quantum mechanics have anything to do with abortion? Something, maybe. Quantum mechanics is the theory that encodes the mathematical patterns involved in the chemical bond. The chemical bond, in turn, writ big, or rather, writ oft, is the tool for assembling DNA, the crucial stuff of living matter. So, as the non plus ultra of life, the quantum mechanical chemical bond, may well have some relevance to abortion too, as an event affecting life.

When did you last hear a "scientist" speculate around quantum mechanics and ABORTION????

As I said – this is the worst crackpot I have ever seen, and I think you should make it very clear that you are not backing up this man and his totally crazy ideas. This is not science.

So, who's the crackpot deviating from the PF guidelines?

I think you owe me an apology.

my_wan

Jun27-10, 02:20 AM

As I said – this is the worst crackpot I have ever seen,...
There's worse, much worse... :rofl:

DevilsAvocado

Jun27-10, 07:12 AM

There's worse, much worse... :rofl:

Please! Don’t tell me! I don’t think I can take it anymore... :yuck:
(What’s next? A Bayesian 'cranky theory' "proving" that the Earth is flat and in the center of the Solar system and the Universe! :biggrin:)

JesseM

Jun27-10, 09:20 AM

A. F. Kracklauer - Non-loco Physics
"Loco'' (Spanish for 'crazy'). Contemporary Physics is vexed by some really "loco'' ideas, with nonlocality and asymmetric aging leading the list.
...
A second motivation is sociological. Some see a mutual interplay between fundamental science and the development of civilization. If this notion is accepted, then physics, as a social enterprise, has some responsibility to support those things making positive contributions to civilization by being the exemplar of rationality, contrary to the current fashion of spewing forth ever new and more exotic pop-psycho-sci-fi contrivances, i.e., loco ideas.
Just noticed this--apparently the guy wants to disprove relativistic time dilation as well! You can see him making some ridiculous arguments against time dilation experiments (which have established 'asymmetric aging' beyond any reasonable doubt) in publication 4, "analysis of and remedy for asymmetric aging (twin paradox)", on this page of his site (http://www.nonloco-physics.000freehosting.com/).

DrChinese

Jun27-10, 12:01 PM

Thus, there are generally two ways to account for EPR-Bell correlations. 1) The detection events are separable and you have superluminal exchange of information. 2) The detection events are not separable, e.g., the spin of the entangled electrons is not a property of each electron. The first property is often called "locality" and the second property "realism."

Great description, RUTA!

To those that try to dissect the words and formulae of Bell (and I count myself in that group sometimes): You can see from RUTA's description that locality and separability can have meanings and implications that can somewhat be interchanged by your choice of base definitions or perspectives.

For example: Norsen (mentioned earlier in the discussion here) sees Bell (2) as defining separability, and he equates that with locality. So separability is spatial/temporal. On the other hand, RUTA is classifying separability according to wave functions. Particles that share a wave function do not have independent (separable) observables - which leans towards the realistic side of the subject.

Further: Norsen sees lack of separability as automatically indicating we live in a non-local universe. Thus c is not a constraint on influences from elsewhere. On the other hand, RUTA (and I probably shouldn't supply words when RUTA can speak for himself) might tend to see lack of separability as indicative that the observer and observed systems are themselves not independent. This perspective was specifically mentioned in the 1935 EPR paper, although EPR rejected this option as not "reasonable" (because that would make the reality of one system dependent on the nature of observation made on another). Unreasonable or not, if it is considered as an option then there are no contradictions with Bell.

Lastly, there is the issue of mechanism. Once you reject local realism, can you account for the "how"? In the Bohmian view, there is action at a distance and c is not respected. Apparently, and I am not suitably versed in this department, the action potential of one particle upon another does not diminish with distance. In the view of RUTA (see more on Relational Blockworld at http://arxiv.org/abs/0908.4348 ): the mechanism can be accounted for without action at distance. However, there are elements whereby the future and the past interact; and this provides the basis for what might appear as action at a distance (even though c is fully respected). I don't think "interact" is the correct word as RBW is sorta Zen-like in its description; there are no events exactly. But I will ask RUTA to correct any misconceptions I have introduced; ditto on the Bohmian side: Maaneli, Demystifier?

So this is some very interesting stuff.

DrChinese

Jun27-10, 12:16 PM

I look at the experimental setups involved and I see a local optical 'explanation' for the observed correlations. I've talked to maybe two dozen working experimental physicists about this and they agree.

So you are saying that there are a number (24 that you know) of people who all are familiar with the same local realistic mechanism for explaining entanglement "optically". And yet I have never even heard of this. Does it have a name so I can look it up? Or is just "the mechanism everybody else knows about" that hasn't yet been published? Or maybe... just maybe... you should consider supplying a reference when you make claims like this.

billschnieder

Jun27-10, 03:04 PM

21 papers on arXiv.org. Where is the "bunch" of peer reviewed papers? These two are peer reviewed before 2000
...
And the only one peer reviewed after 2000, is this one:
...

Either you are just being dishonest, or you can not count, or maybe you do not know what a peer reviewed article means, or you do not know how to find peer reviewed articles. Here is a list from the page you linked to.

On the nature of information-erasing , Journal of Modern Optics, Volume 54, Numbers 16-17, November 2007 , pp. 2365-2371(7)
Nonlocality, Bell's Ansatz and Probability Optics and Spectroscopy. 103 (3) 451-450 (2007)
"What's wrong with this rebuttal,"Found. Phys. Lett. 19 (6) 625-629 (2006).
``Quantum'' beats in classical physics,, J. of Russian Laser Research 26 (6) 524-529 (2005)
Oh Photon, Photon, whither art thou gone?, in: Proceedings of SPIE, 5866 (2005).
EPR-B correlations: non-locality or geometry?, J. Nonlinear Math. Phys. 11(Supp.) 104-109 (2004).
EPR-B correlations: quantum mechanics or just geometry?, J. Opt. B (Semiclass. & Quant.) 6 S544-S548 (2004)
Exclusion of correlation in the theorem of Bell, in: Foundations of Probability and Physics-2, 385-398
One less quantum mystery, J. Opt. B (Semiclass. & Quant.) 4, S469-S472 (2002)
Is entanglement always entangled?, J. Opt. B (Semiclass. & Quant.) 4, S121-S126 (2002)
``Complementarity'' or Schizophrenia: is Probability in Quantum Mechanics Information or Onta?, in: Foundations of Probability and Physics, 219-235 (2001)
The Improbability of Non-locality, Phys. Essays, 15(2) 162-171 (2002)
La `theorem' de Bell, est-elle al plus grand meprise de l'histoire de la physique?, Ann. Fond. L. de Broglie 25(2) 193-207 (2000)
Pilot wave steerage: a mechanism and test, Found. Phys. Lett. 12(2) 441-453 (1999).
Objective Local Models for Would-be Nonlocal Physics, in: Instantaneous aad: Pro & Contra, 363-372 (1999).
An Intuitive Paradigm for Quantum Mechanics, Phys. Essays 5 (2) 226-234 (1992)
A theory of the electromagnetic two-body interaction. J. Math. Phys. 19(4) 838-841 (1978)
Comment on: Classical derivation of Planck Spectrum, Phys. Rev. D 14, 654-655 (1976)
On the Imaginable Content of de Broglie Waves, Scientia, 109 ,111-120 (1974).
Comment on: Derivation of Schroedinger's Equation from Newtonian Mechanics, Phys. Rev. D 10(4) 1358-1360 (1974).
A geometric proof of no-interaction theorems, J.Math Phys. 17(5) 693-694 (1974)

Ad-hominem http://dictionary.reference.com/browse/ad+hominem

1. appealing to one's prejudices, emotions, or special interests rather than to one's intellect or reason.
2. attacking an opponent's character rather than answering his argument.

http://en.wikipedia.org/wiki/Ad_hominem

Ad hominem abusive
Ad hominem abusive usually involves insulting or belittling one's opponent, but can also involve pointing out factual but ostensible character flaws or actions which are irrelevant to the opponent's argument. This tactic is logically fallacious because insults and even true negative facts about the opponent's personal character have nothing to do with the logical merits of the opponent's arguments or assertions.
...
Guilt by association
Guilt by association can sometimes also be a type of ad hominem fallacy, if the argument attacks a source because of the similarity between the views of someone making an argument and other proponents of the argument.
This form of the argument is as follows:

Source A makes claim P.
Group B also make claim P.
Therefore, source A is a member of group B.

Fallacy -- http://en.wikipedia.org/wiki/Fallacy

In logic and rhetoric, a fallacy is a misconception resulting from incorrect reasoning in argumentation. By accident or design, fallacies may exploit emotional triggers in the listener or interlocutor (e.g. appeal to emotion), or take advantage of social relationships between people (e.g. argument from authority). Fallacious arguments are often structured using rhetorical patterns that obscure the logical argument

my_wan

Jun27-10, 04:23 PM

Please! Don’t tell me! I don’t think I can take it anymore... :yuck:
(What’s next? A Bayesian 'cranky theory' "proving" that the Earth is flat and in the center of the Solar system and the Universe! :biggrin:)
http://theflatearthsociety.org/
You can also see their experimental evidence here:
http://www.theflatearthsociety.org/tiki/tiki-index.php
Oh, and that's not even the worst that can be found :uhh:

DevilsAvocado

Jun27-10, 04:23 PM

Just noticed this--apparently the guy wants to disprove relativistic time dilation as well! You can see him making some ridiculous arguments against time dilation experiments (which have established 'asymmetric aging' beyond any reasonable doubt) in publication 4, "analysis of and remedy for asymmetric aging (twin paradox)", on this page of his site (http://www.nonloco-physics.000freehosting.com/).

Well, what can I say?? The man is a "crackpot miracle"... It’s not only QM that’s "totally wrong"! Albert Einstein also goes down the Crackpot-Kracklauer-Drain!?!?

(I sure hope Crackpot Kracklauer doesn’t use GPS in his car, because this would not work without QM atomic clocks + SR/GR correction for time dilation effects and gravitational frequency shift!!)

This is remarkable... ThomasT & billschnieder thinks Crackpot Kracklauer is a "great scientist"...

JesseM, I really admire yours (and DrC’s) enormous patience and great skills, in trying to educate users like billschnieder. To me it looks like ThomasT has shown some willingness to an honest intellectual discussion and some openness to input and logical argumentation. But billschnieder on the other hand, is a wall of weird preconceptions, mainly based on the crazy ideas of Crackpot Kracklauer. That’s why your discussion ended the way it did. You did all you could – but it was a dead end from the beginning.

And there are other terrible examples of billschnieder’s 'technique' in other threads on PF (I tried to warn you).

I’m only a layman. I don’t have the great skills and deep knowledge you and many others here posses. But I do think I have one 'skill' – common sense and ability to judge what’s reasonable or not (which some "sophisticated gentlemen" in this thread apparently lacks).

Crackpot Kracklauer is not reasonable.

I must apologize to all "casual readers" for this "unpleasant episode" in this thread. I generally don’t find it interesting or productive to start "fights". But this was an exception, and someone had to push the "alarm button".

I hope we all can continue to discuss the matters of EPR and Bell's Theorem in an open, stimulating and productive way, as before.

I’m working on some "new" material from John Bell himself, never shown or discussed on PF. I think (hope) everyone will find it (very) interesting. I’m a little short of time at the moment, but I hope I can get it ready for 'publishing' ASAP.

Again – Sorry for the latest "mess".

/DA

DevilsAvocado

Jun27-10, 04:35 PM

Great description, RUTA!

I agree! Captain RUTA is a great teacher! And most of all I admire him for implementing this little 'tips':

"Everything should be made as simple as possible, but not simpler" -- Albert Einstein

DevilsAvocado

Jun27-10, 04:39 PM

Ad-hominem
Fallacy

Please billschnieder, you are making a fool of yourself.

DevilsAvocado

Jun27-10, 04:40 PM

http://theflatearthsociety.org/
You can also see their experimental evidence here:
http://www.theflatearthsociety.org/tiki/tiki-index.php
Oh, and that's not even the worst that can be found :uhh:

:rofl:

ThomasT

Jun28-10, 02:48 AM

... And the only one peer reviewed after 2000, is this one: ...Are you being intentionally dishonest about this? All anyone has to do is go to the guy's website and click on the links to see that what you're saying wrt the number of papers he's published (since 1999) in peer reviewed journals is false. There's at least 8 by my count, maybe more. A couple were published in the same journals that Stuckey (RUTA) has published in.

The question is why you risk all your credibility for a 100% crackpot as A. F. Kracklauer? ... A completely lost "independent researcher" with a crazy homepage at freehosting.com, and you are supporting this guy!? Why??Where did I say that I support his ideas? I did say that some of his stuff looked like it might be interesting, and that he seemed to have a clear writing style.

I don't like what I see as your personal attack on someone whose views you happen to oppose. I'm not familiar with Kracklauer's stuff, but I intend to get around to reading it. Until then, I can't speak to whether or not I think any of his ideas or arguments are right or wrong. But even if I eventually conclude that ALL of his ideas and arguments are wrong, I certainly won't be calling him names because of it.

For a while in this thread you were following a line of reasoning, and I was enjoying your posts (even if I didn't agree with all your reasoning or tentative conclusions -- though some I did agree with -- not that that matters). But I don't see the utility in your current line of personal attacks. You can pursue your political agenda in another forum (or maybe not). Anyway, this is a science forum, and this is a thread about the grounds for assuming that nature is nonlocal. If you want to make an argument, or present an idea about that, then fine, but the personal stuff is annoying. Bottom line, I don't care if Kracklauer is crazy or not. If he's got any good ideas then I want to know about them. Eventually, though probably not real soon, I'll find out for myself.

I know you dislike nonlocality very much, and are fighting to find a "solution".I couldn't care less if nonlocality or ftl exist or not. In fact, it would be very exciting if they did. But the evidence just doesn't support that conclusion.

The scientific method requires two basic questions be answered whenever some new property of reality or some paradigm changing, revolutionary view of reality is proposed. (1) What do you mean, and (2) how do you know? If you'd like to contribute to the effort to answer those questions, to discern the truth from the fiction wrt nonlocality and related considerations, then that would be a welcome change from your recent postings.

But don’t you think this is a 'little' too "far out"? This man has a mental problem:

A. F. Kracklauer - Non-loco Physics
"Loco'' (Spanish for 'crazy'). Contemporary Physics is vexed by some really "loco'' ideas, with nonlocality and asymmetric aging leading the list.
...
A second motivation is sociological. Some see a mutual interplay between fundamental science and the development of civilization. If this notion is accepted, then physics, as a social enterprise, has some responsibility to support those things making positive contributions to civilization by being the exemplar of rationality, contrary to the current fashion of spewing forth ever new and more exotic pop-psycho-sci-fi contrivances, i.e., loco ideas.Well, he's saying that physical science should be an exemplar of rationality. Nothing crazy about that. Now, I will say that my superficial impression of his ideas on asymmetric or differential aging seems to be contrary to the way I've learned to think about it. That is, I believe that differential aging is pretty much a demonstrated fact of nature. But, I haven't read his paper(s) on this yet. So, I don't know exactly what he's saying about this, or his arguments. By themselves, the above quotes don't seem crazy. Even if they're grossly wrong, that doesn't imply that the guy is crazy. And if he has an agenda, even a personal one, that influences his approach and reasoning, well, I don't think that's at all unusual, and certainly not an indicator of 'mental illness'. Maybe in your imagination there are scientists whose work isn't influenced by 'nonscientific' factors.

"Complementarity" or Schizophrenia: is Probability in Quantum Mechanics Information or Onta?
ABSTRACT. Of the various “complimentarities” or “dualities” evident in Quantum Mechanics (QM), among the most vexing is that afflicting the character of a ‘wave function,’ which at once is to be something ontological because it diffracts at material boundaries, and something epistemological because it carries only probabilistic information. Herein a description of a paradigm, a conceptual model of physical effects, will be presented, that, perhaps, can provide an understanding of this schizophrenic nature of wave functions. It is based on Stochastic Electrodynamics (SED), a candidate theory to elucidate the mysteries of QM. The fundamental assumption underlying SED is the supposed existence of a certain sort of random, electromagnetic background, the nature of which, it is hoped, will ultimately account for the behavior of atomic scale entities as described usually by QM.
In addition, the interplay of this paradigm with Bell’s ‘no-go’ theorem for local, realistic extentions of QM will be analyzed.I think the title was intended to get attention -- so that people would actually read the paper. Nothing crazy about that. Despite the fact that he might be, strictly speaking, using the term 'schizophrenia' incorrectly, I don't have an opinion wrt the merits of the content of the paper, not having read it yet. Have you read it?

The quantum mechanics of abortion
Does quantum mechanics have anything to do with abortion? Something, maybe. Quantum mechanics is the theory that encodes the mathematical patterns involved in the chemical bond. The chemical bond, in turn, writ big, or rather, writ oft, is the tool for assembling DNA, the crucial stuff of living matter. So, as the non plus ultra of life, the quantum mechanical chemical bond, may well have some relevance to abortion too, as an event affecting life.When I first read this, I thought that maybe the guy really is crazy -- like maybe another abortion nut or whatever. But since the paper was only one page, I read it. He seems to be making a very reasonable social commentary.

He concludes with:

In any case, in the end quantum mechanics throws little light on these standards, except from its essentially probabilistic nature. This feature tells us that bond formation needs no ‘breath of life,’ or other mystical ingredient, it is a random event, it just happens, sometimes for no good reason. All the above seems to imply that science and logic can not be used to unequivocably evaluate abortion ethically. For what it’s worth, the morally superior stance, surely is the one which, no matter how and when life starts and ends, tends to cause people to turn to it less often. Practically this means avoiding unwanted pregnancies beforehand by promoting reproductive hygiene, and then providing material and financial support for single or disadvantaged mothers who failed with prevention afterwards. It is regrettable that an all too common sort of mental confusion, especially in the voting booth, leads ‘right-to-lifers’ themselves to become opponents of these practical means to actually reduce the occasions for abortion, thereby serving effectively as champions of the ‘evil’ they themselves disparage!

When did you last hear a "scientist" speculate around quantum mechanics and ABORTION????

As I said – this is the worst crackpot I have ever seen, and I think you should make it very clear that you are not backing up this man and his totally crazy ideas. This is not science.Right. It's not science. Nor, I think, is it meant to be taken as such. It's an essay that presents some interesting and reasonable observations by a scientist with an active social conscience. Keep in mind that the US is full of Christian fanatics who would twist any scientific finding or paradigm to support their religious agendas. Kracklauer's program, it seems to me so far, is to oppose that sort of thing and also to oppose what some might see as an increasing tendency toward metaphysical constructions and 'mysticism' in 'mainstream' physics.

So, if that's all you've got, then 'case dismissed', as they say. From what I've seen so far, I think you owe Kracklauer and the contributors to, and observers of, this thread an apology. However, if you really just want to discredit the guy, then keep digging. That should at least keep you busy, and hopefully not posting your personal attacks, for a while. But keep in mind that your posts regarding Kracklauer are quite off topic. Maybe, eventually, some thoughtful moderator is going to inform you of that.

ThomasT

Jun28-10, 02:52 AM

Well, can you present your local optical explanation in detail, either here or on a new
thread? You'll need to present it in enough quantitative detail that we can calculate
what measurement outcome will occur (or what the probability is for different outcomes)
given knowledge of a detector settings and the local hidden variables at the location of
the measurement (like the 'polarization vector' of the particle being measured, if that's
your hidden variable).It isn't 'my' optical explanation. It's optics. There's two polarizers, a and b. They can both be on side A, or both be on side B, or one on each side. There's a randomly varying optical vector extending between the two polarizers. The resultant, measured, joint intensity of the light (the coincident photon flux) will vary as cos^2 (a-b). Of course the exact calculation will depend on the setup, but the point is that whenever crossed polarizers are jointly analyzing light from a random source, then this optical law applies.

I'm no expert, so if there's something essentially wrong with this, then let me know. If it's, in principle, ok, then I don't see any reason to suppose that anything nonlocal or ftl is happening.

Further, as DrC pointed out, a slight rotation of a wave plate is all that's necessary to produce polarization entanglement in certain OPDC Bell tests. Again, this doesn't suggest anything nonlocal or ftl to me. Does it to you?

So, this is the first problem I have with the assumption of nonlocality -- that there's nothing wrt Bell test setups and results, sans Bell's theorem (Bell inequalities) which warrants the assumption of nonlocality. If you put both polarizers on side A or side B, you get the same results as when you put one polarizer at A and one at B. But we don't think that anything nonlocal is going on when we have both polarizers on side A or side B. These are just simple polariscopic setups. But the joint results are the same as when we have one polarizer at A and one at B. So, why does this latter setup require a 'nonlocal' explanation? Well, the way I currently think about it, it doesn't.

The same sort of reasoning applies to OPDC setups where a slight rotation of a wave plate produces entanglement statistics wrt joint polarization measurements. Should I assume that this slight rotation has somehow precipitated nonlocal or ftl 'communications' in some realm underlying that of electromagnetic radiation? This just seems a bit silly to me. But if you can convince me otherwise, then I'm all ears, so to speak.

No, A and B are not independent in their marginal probabilities (which determine the
actual observed frequencies of different measurement outcomes), only in their
probabilities conditioned on Î». I've asked whether you understand the distinction a
bunch of times and you never answer.I don't think the distinction matters. No matter how it's parsed, or how one chooses to express probability analogs for Bell's (2), the bottom line is that the joint probability is being modelled as the product of the separate probabilities. So, no matter what was intended, the form of Bell's (2) effectively models the two resultant data sets as independent. This was Bell's explicit expression of locality. The problem is that its intended function as an expression of locality is superceded by its effective function as an expression of statistical independence between the data sets.

ThomasT

Jun28-10, 02:55 AM

So you are saying that there are a number (24 that you know) of people who all are familiar with the same local realistic mechanism for explaining entanglement "optically". And yet I have never even heard of this. Does it have a name so I can look it up? Or is just "the mechanism everybody else knows about" that hasn't yet been published? Or maybe... just maybe... you should consider supplying a reference when you make claims like this.I was referring to casual conversations over the course of 8 or 9 years. So, no, you wouldn't have heard of 'it'. I would describe an optical Bell test setup, recount the results, and ask them if they thought the results indicated that any sort of 'nonlocal' or ftl 'communication' was necessary to understand them, and they would say no. I don't know exactly how many physicists I engaged in these conversations, but the impression I got was that none of them thought that anything mysterious (beyond the mystery of light itself) was going on in the experiments we discussed. The consensus was that it's just optics as usual -- ie., the correlations are due to the joint analysis of random polarizations by crossed polarizers.

Positing the existence of disturbances propagating at > c^9 (or 'instantaneously', whatever that might mean) is a nifty way to account for the correlations in optical Bell tests, but it just seems to me, and apparently lots of others (including Mermin, Jaynes, 't Hooft, etc.), to be too simplistic a solution to the conundra presented by the various interpretations of Bell's theorem. Anyway, those who do choose to advocate nonlocality as an 'explanation' are then left with the formidable task of explaining the explanation. So far, it's just metaphysics. But don't get me wrong, I like metaphysical speculations. It's just that I like them to be well grounded in accepted physics -- and, unfortunately, nonlocality isn't.

...if you accept Malus - combined with the assumption that there is a specific but unknown polarization for entangled photons - then probably you would conclude that Bell (2) is false.Well, Malus Law is an empirically well established optical law. And since we know from experiments that, assuming that nature is evolving in accordance with the principle of local action, Bell's (2) is false, then what should we conclude? That there is some nonlocal or ftl 'mechanism' at work in entanglement situations, or that Bell's (2) simply misrepresents the experimental situation? What's being suggested is that the latter alternative is the more reasonable hypothesis, and that this hypothesis has yet to be definitively dismissed.

JesseM

Jun28-10, 07:06 AM

It isn't 'my' optical explanation. It's optics. There's two polarizers, a and b. They can both be on side A, or both be on side B, or one on each side. There's a randomly varying optical vector extending between the two polarizers. The resultant, measured, joint intensity of the light (the coincident photon flux) will vary as cos^2 (a-b)
Your claim here is completely ill-defined. What is "joint intensity" supposed to mean in the context of optics? It appears to be completely meaningless in the context of classical optics, where there are no probabilities and thus no joint probabilities. Now, it's true that if the polarization of a light beam is v and the angle of the polarizer is a, then in classical optics the reduction in intensity as the light goes through the polarizer will be cos^2(a-v), that's just Malus' law. In quantum physics intensity is proportional to photon number, so are you suggesting that for a beam with polarization v passing through a polarizer at angle a, each photon has a probability of cos^2(a-v) of passing through the polarizer? And then the "joint intensity" would be based on imagining photons are sent to the different detectors in pairs, so the probability both photons make it through the detectors would be cos^2(a-v)*cos^2(b-v)? If so, this would not give a probability of cos^2(a-b) that both photons make it through (I showed this in my third-to-last paragraph of this post (http://www.physicsforums.com/showthread.php?p=2761389#post2761389), a section you never responded to even when I reposted that paragraph in a later post).
I don't think the distinction matters. No matter how it's parsed, or how one chooses to express probability analogs for Bell's (2), the bottom line is that the joint probability is being modelled as the product of the separate probabilities.
Huh? The joint probability P(AB) is not being modelled as the product of P(A)*P(B) by Bell's equation. Do you disagree?

DrChinese

Jun28-10, 09:00 AM

I was referring to casual conversations over the course of 8 or 9 years. So, no, you wouldn't have heard of 'it'. I would describe an optical Bell test setup, recount the results, and ask them if they thought the results indicated that any sort of 'nonlocal' or ftl 'communication' was necessary to understand them, and they would say no. I don't know exactly how many physicists I engaged in these conversations, but the impression I got was that none of them thought that anything mysterious (beyond the mystery of light itself) was going on in the experiments we discussed. The consensus was that it's just optics as usual -- ie., the correlations are due to the joint analysis of random polarizations by crossed polarizers.

Once again, you completely ignored the fact that this is false and you have NO reference for an outlandish statement. I would like to see this from any textbook. Quit stating your opinion by placing it in the mouth of unnamed others.

Reference, citation = ???????

DrChinese

Jun28-10, 09:11 AM

Huh? The joint probability P(AB) is not being modelled as the product of P(A)*P(B) by Bell's equation. Do you disagree?

ThomasT doesn't follow this correctly and keeps returning to something that is completely wrong. So this is intended for ThomasT:

1) If optics were the ruling issue, we would see Product State statistics. And those are different than what are observed. Product State stats are .5(.5+cos^2(theta)).

2) Entangled state statistics APPEAR to match Malus but that is something of a coincidence. Yes, it is cos^2(theta). And that is the Malus formula. But that is where it ends. If Malus applied, you would actually get the formula in 1) above.

Entanglement is a PURELY quantum effect and there is NO optical analog. I don't know how many different ways I can say this to make ThomasT understand it.

my_wan

Jun28-10, 10:47 AM

DrC,
Perhaps you can be more clear. When you say:
1) If optics were the ruling issue, we would see Product State statistics.

Is this not essentially equivalent to saying, based on optics alone, that given theta = x then 2theta = 2x?, or some linear multiple for all theta. Malus law doesn't work this way even in standard optics.

I don't see using Malus law to show the same behavior pattern as relevant in resolving the issue, but neither does calling a one to one quantitative correspondence only an apparent match make much sense to me. As noted, by itself it doesn't resolve the realism issue, and standard optics allows a greater range of presumptions about how this result might be classical. The simplest of such presumptions being unequivocally ruled out by EPR correlation experiments. Yet perhaps you could be more specific in claiming an exact numerical match is an illusion.

Perhaps the rebuttal should involve the extra constraints BI imposes on possible mechanisms, rather than simply claiming the a quantitative correspondence is an illusion. Because I really don't think you can demonstrate that Malus law, standard optics, allows arbitrary choices of theta that leads to linear polarizer path statistics.

To illustrate, consider a standard polarized beam of light. Take the polarization of the light beam to be something other than theta = 0, and offset the polarizer/detector from the light beam on that same coordinate system. It breaks Malus law when you demand arbitrary coordinate choices, even in standard optics. This same demand that is insisted on to model EPR correlations that is also broken in standard optics.

Yes, I think these issues are fundamentally related. No, I don't think simply pointing out the relationship within standard optics, by itself, represents a resolution to the issue. The fact that it could be interpreted differently within the context of standard optics ignores the extra properties/things relationship constraints that EPR correlation experiments are sensitive to.

JesseM

Jun28-10, 11:10 AM

I don't see using Malus law to show the same behavior pattern as relevant in resolving the issue, but neither does calling a one to one quantitative correspondence only an apparent match make much sense to me.
"One to one quantitative correspondence" between what and what? the cos^2 in Malus' law is for the difference between the angle of a polarizer and the polarization angle of a beam hitting it at the same location, the cos^2 in entanglement experiments is for the difference in angles between two polarizers at completely different locations making measurements on different particles. There's no way to use the first cos^2 law to derive the second one, whatever ThomasT may think.
As noted, by itself it doesn't resolve the realism issue, and standard optics allows a greater range of presumptions about how this result might be classical.
Why a "greater range of presumptions"? Standard optics can be derived from Maxwell's laws, which is a perfect example of a local realist theory of physics, so Bell's theorem definitely applies to anything in optics (and it's impossible to use classical optics to get a violation of Bell inequalities).
To illustrate, consider a standard polarized beam of light. Take the polarization of the light beam to be something other than theta = 0, and offset the polarizer/detector from the light beam on that same coordinate system. It breaks Malus law when you demand arbitrary coordinate choices, even in standard optics. This same demand that is insisted on to model EPR correlations that is also broken in standard optics.
Malus' law is only based on the difference in angle between the beam and the polarizer, so it doesn't get violated depending on how your coordinate system defines the angle of the beam. Are you suggesting otherwise?

ThomasT

Jun28-10, 11:12 AM

Once again, you completely ignored the fact that this is false and you have NO reference for an outlandish statement.Ok, so you don't think that a randomly varying polarization vector being jointly analyzed by crossed polarizers is a good way to think about it? Then how about when you put both polarizers on the same side? How would you think about that situation?

1) If optics were the ruling issue, we would see Product State statistics. And those are different than what are observed. Product State stats are .5(.5+cos^2(theta)).
2) Entangled state statistics APPEAR to match Malus but that is something of a coincidence. Yes, it is cos^2(theta). And that is the Malus formula. But that is where it ends. If Malus applied, you would actually get the formula in 1) above.
3) Entanglement is a PURELY quantum effect and there is NO optical analog.
1) Well, these are optics experiments, so why wouldn't optics be the ruling issue?
2) Do you think that Malus Law doesn't apply in quantum optics?
3) Statements like this don't do it for me. The goal is to understand the correlations, not keep them mysterious. If you want to think that something nonlocal or ftl kicks in simply because single photons are being detected, or because a polarizer has been moved, or a wave plate adjusted, then ok. I guess we'll just have to agree to disagree about the prospects for a better understanding of quantum optical experiments, and quantum entanglement.

ThomasT

Jun28-10, 11:21 AM

Your claim here is completely ill-defined.I'm somewhat noted for that.

What is "joint intensity" supposed to mean in the context of optics?We're talking about optical Bell tests, right? I think I phrased it as the 'coincidental photon flux'.

In certain optical Bell tests the coincidence rate is proportional to cos^2(a-b). From your knowledge of quantum optics, do you think that that indicates or requires that something nonlocal or ftl is happening in those experiments?

The joint probability P(AB) is not being modelled as the product of P(A)*P(B) by Bell's equation. Do you disagree?My thinking has been that it reduces to that. Just a stripped down shorthand for expressing Bell's separability requirement. If you don't think that's ok, then how would you characterize the separability of the joint state (ie., the expression of locality) per Bell's (2)?

JesseM

Jun28-10, 11:25 AM

3) Statements like this don't do it for me. The goal is to understand the correlations, not keep them mysterious. If you want to think that something nonlocal or ftl kicks in simply because single photons are being detected, or because a polarizer has been moved, or a wave plate adjusted, then ok.
Bell's theorem doesn't depend on the fact that "single photons are being detected", but it does require that each measurement setting can yield one of two binary outcomes akin to "spin-up" and "spin-down". You are free to design your detectors in a classical optics experiment so that they can only yield two outcomes rather than a continuous range of intensities--for example, you design it so that if the intensity of the light that made it through the polarizer was above a certain threshold a red light would go off, and if the intensity was at or below that threshold a green light would go off. Likewise you might design the detector so the probability or a red light going off vs. a green light going off would depend on the reduction in intensity as the light went through the polarizer--say if the intensity was reduced by 70%, there'd be a 70% chance the red light would go off and a 30% chance the green light would go off.

But no matter how you design the experiment, as long as each detector setting can yield only one of two possible results, and the two measurements are made at a spacelike separation, no experiment which obeys the laws of classical optics will violate Bell's inequalities. Do you disagree? If you do, please give specifics on the design of the experiment you are imagining, detailing how the light's polarization and the detector setting determine which of two outcomes occur on each trial (as I did in the two examples above). If you can't fill in these basic details, then your claims that there is an "optical" explanation for Bell-inequality-violating quantum correlations are obviously not very well thought-out.

ThomasT

Jun28-10, 11:33 AM

There's no way to use the first cos^2 law to derive the second one, whatever ThomasT may think.I'm just trying to understand the correlation between the angular difference in the polarizer settings and coincidental detection. It doesn't 'seem' mysterious. That is, the optics principle that applies to the observed coincidence count when both polarizers are on one side, would seem to be applicable when there's one polarizer on each side.

ThomasT

Jun28-10, 11:51 AM

ThomasT

Jun28-10, 11:55 AM

To illustrate, consider a standard polarized beam of light. Take the polarization of the light beam to be something other than theta = 0, and offset the polarizer/detector from the light beam on that same coordinate system. It breaks Malus law when you demand arbitrary coordinate choices, even in standard optics. This same demand that is insisted on to model EPR correlations that is also broken in standard optics.
I don't understand what you're saying here.

DrChinese

Jun28-10, 12:17 PM

DrChinese

Jun28-10, 12:22 PM

I'm just trying to understand the correlation between the angular difference in the polarizer settings and coincidental detection. It doesn't 'seem' mysterious. That is, the optics principle that applies to the observed coincidence count when both polarizers are on one side, would seem to be applicable when there's one polarizer on each side.

Except that it doesn't apply to ordinary streams of identically polarized photon pairs coming from a PDC crystal. According to your ideas, it should. You would predict Entangled State stats (cos^2 theta) and you instead see Product State (.5*(.5+cos^2 theta)). So your prediction is flat out incorrect.

I re-iterate: where is your REFERENCE?

JesseM

Jun28-10, 12:25 PM

We're talking about optical Bell tests, right? I think I phrased it as the 'coincidental photon flux'.
Please review the context of this exchange. I said "Well, can you present your local optical explanation in detail, either here or on a new thread?" and you replied "It isn't 'my' optical explanation. It's optics." Naturally I took this to imply you thought there could be a local optical explanation for the cos^2(a-b) statistics seen in entanglement experiments, perhaps one involving Malus' law (which can indeed be derived from classical electromagnetism, a completely local theory). Did I misunderstand? Are you not claiming that the statistics can be explained in terms of local properties that travel along with the two beams (or the individual photons) that were assigned to them by the source?
In certain optical Bell tests the coincidence rate is proportional to cos^2(a-b). From your knowledge of quantum optics, do you think that that indicates or requires that something nonlocal or ftl is happening in those experiments?
It does require that if we adopt a "realist" view of the type I discussed in post #101 of the Understanding Bell's Logic thread (http://www.physicsforums.com/showpost.php?p=2765663&postcount=101), and if we assume each measurement has a single unique outcome (so many-worlds type explanations are out), and if the experiment meets various observable requirements like sufficiently high detector efficiency and a spacelike separation between measurements.
The joint probability P(AB) is not being modelled as the product of P(A)*P(B) by Bell's equation. Do you disagree?
My thinking has been that it reduces to that.
Yes, of course I disagree, you're just totally misunderstanding the most basic logic of the proof which is assuming a perfect correlation between A and B whenever both experimenters choose the same detector setting. It's really rather galling that you make all these confident-sounding claims about Bell's proof being flawed when you fail to understand something so elementary about it! Could you maybe display a tiny bit of intellectual humility and consider the possibility that it might not be that the proof itself is flawed and that you've spotted a flaw that so many thousands of smart physicists over the years have missed, that it might instead be you are misunderstanding some aspects of the proof?

If you want an example where two variables are statistically dependent in their marginal probabilities but statistically independent when conditioned on some other variable, you might consider the numerical example I provided in this post (http://www.physicsforums.com/showpost.php?p=2759757&postcount=28), where P(T,U) is not equal to P(T)*P(U) but P(T,U|V) is equal to P(T|V)*P(U|V):
in your example there seem to be two measured variables, T which can take two values {received treatment A, received treatment B} and another one, let's call it U, which can also take two values {recovered from disease, did not recover from disease}. Then there is also a hidden variable we can V, which can take two values {large kidney stones, small kidney stones}. In your example there is a marginal correlation between variables T and U, but there is still a correlation (albeit a different correlation) when we condition on either of the two specific values of V. So, let me modify your example with some different numbers. Suppose 40% of the population have large kidney stones and 60% have small ones. Suppose those with large kidney stones have an 0.8 chance of being assigned to group A, and an 0.2 chance of being assigned to group B. Suppose those with small kidney stones have an 0.3 chance of being assigned to group A, and an 0.7 chance of being assigned to B. Then suppose that the chances of recovery depend only one whether one had large or small kidney stones and is not affected either way by what treatment one received, so P(recovers|large kidney stones, treatment A) = P(recovers|large kidney stones), etc. Suppose the probability of recovery for those with large kidney stones is 0.5, and the probability of recovery for those with small ones is 0.9. Then it would be pretty easy to compute P(treatment A, recovers, large stones)=P(recovers|treatment A, large stones)*P(treatment A, large stones)=P(recovers|large stones)*P(treatment A, large stones)=P(recovers|large stones)*P(treatment A|large stones)*P(large stones) = 0.5*0.8*0.4=0.16. Similarly P(treatment A, doesn't recover, small stones) would be P(doesn't recover|small stones)*P(treatment A|small stones)*P(small stones)=0.1*0.3*0.6=0.018, and so forth.

In a population of 1000, we might then have the following numbers for each possible combination of values for T, U, V:

1. Number(treatment A, recovers, large stones): 160
2. Number(treatment A, recovers, small stones): 162
3. Number(treatment A, doesn't recover, large stones): 160
4. Number(treatment A, doesn't recover, small stones): 18
1. Number(treatment B, recovers, large stones): 40
2. Number(treatment B, recovers, small stones): 378
3. Number(treatment B, doesn't recover, large stones): 40
4. Number(treatment B, doesn't recover, small stones): 42

If we don't know whether each person has large or small kidney stones, this becomes:

1. Number(treatment A, recovers) = 160+162 = 322
2. Number(treatment A, doesn't recover) = 160+18 = 178
3. Number(treatment B, recovers) = 40+378 = 418
4. Number(treatment B, doesn't recover) = 40+42=82

So here, the data shows that of the 500 who received treatment A, 322 recovered while 178 did not, and of the 500 who received treatment B, 418 recovered and 82 did not. There is a marginal correlation between receiving treatment B and recovery: P(treatment B, recovers)=0.418, which is larger than P(treatment B)*P(recovers)=(0.5)*(0.74)=0.37. But if you look at the correlation between receiving treatment B and recovery conditioned on large kidney stones, there is no conditional correlation: P(treatment B, recovers|large stones) = P(treatment B|large stones)*P(recovers|large stones) [on the left side, there are 400 people with large stones and only 40 of these who also received treatment B and recovered, so P(treatment B, recovers|large stones) = 40/400 = 0.1; on the right side, there are 400 with large stones but only 80 of these received treatment B, so P(treatment B|large stones)=80/400=0.2, and there are 400 with large stones and 200 of those recovered, so P(recovered|large stones)=200/400=0.5, so the product of these two probabilities on the right side is also 0.1] The same would be true if you conditioned treatment B + recovery on small kidney stones, or if you conditioned any other combination of observable outcomes (like treatment A + no recovery) on either large or small kidney stones.
If you like I could also show you how something similar would be true in my scratch lotto example (http://www.physicsforums.com/showthread.php?t=355538), which is even more directly analogous to the situation being considered in Aspect-type experiments.
If you don't think that's ok, then how would you characterize the separability of the joint state (ie., the expression of locality) per Bell's (2)?
I would characterize it in terms of A and B being statistically independent only when conditioned on the value of the hidden variable λ. They are clearly not statistically independent otherwise, and Bell makes it explicit that he assumes there is a perfect correlation between their values when both experimenters choose the same detector setting. For example, in the introduction to the original paper (http://www.drchinese.com/David/Bell_Compact.pdf) he says:
Since we can predict in advance the result of measuring any chosen component of \sigma_2, by previously measuring the same component of \sigma_1, it follows that the result of any such measurement must actually be predetermined. Likewise in this paper (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) Bell writes on p. 11:
Let us summarize once again the logic that leads to the impasse. The EPRB correlations are such that the result of the experiment on one side immediately foretells that on the other, whenever the analyzers happen to be parallel. If we do not accept the intervention on one side as a causal influence on the other, we seem obliged to admit that the results on both sides are determined in advance anyway, independent of the intervention on the other side, by signals from the source and by the local magnet setting.
If the value of measurement A "immediately foretells" the value of measurement B when the settings on both sides are the same, that means there's a perfect correlation between the value of A and the value of B when conditioned only on the fact that both sides used the same setting (and not conditioned on any hidden variables)--do you disagree?

JesseM

Jun28-10, 12:33 PM

I'm just trying to understand the correlation between the angular difference in the polarizer settings and coincidental detection. It doesn't 'seem' mysterious.
Well, you are going to have to do some precise reasoning rather than just relying on feelings about how things "seem" if you want to understand Bell's arguments.
That is, the optics principle that applies to the observed coincidence count when both polarizers are on one side, would seem to be applicable when there's one polarizer on each side.
If you are doing an experiment which matches the condition of the Bell inequalities that says each measurement must yield one of two binary results (rather than a continuous range of intensities), then even if "both polarizers are on one side" it would be impossible to reproduce the cos^2 relationship between the angles of the two polarizers in classical optics, despite the fact that Malus' law applies in classical optics. Do you disagree? In post #896 I outlined some ways you might design a detector to yield one of two binary outcomes in an experiment based on classical optics:
You are free to design your detectors in a classical optics experiment so that they can only yield two outcomes rather than a continuous range of intensities--for example, you design it so that if the intensity of the light that made it through the polarizer was above a certain threshold a red light would go off, and if the intensity was at or below that threshold a green light would go off. Likewise you might design the detector so the probability or a red light going off vs. a green light going off would depend on the reduction in intensity as the light went through the polarizer--say if the intensity was reduced by 70%, there'd be a 70% chance the red light would go off and a 30% chance the green light would go off.
But no matter how you design your classical detector to give one of two binary outcomes based on how much light passes through it, you can never get a violation of the Bell inequalities in classical optics.

my_wan

Jun28-10, 01:18 PM

"One to one quantitative correspondence" between what and what? the cos^2 in Malus' law is for the difference between the angle of a polarizer and the polarization angle of a beam hitting it at the same location, the cos^2 in entanglement experiments is for the difference in angles between two polarizers at completely different locations making measurements on different particles. There's no way to use the first cos^2 law to derive the second one, whatever ThomasT may think.
Of course the polarizer at the same location in the classic optics case, with no path references for individual photons. That's one of the reasons EPR correlations are sensitive to certain realism claims that standard optics is not. The quantitative correspondence results when you apply the same same location rules to the photon polarizers interactions plus standard conservation requiring photon pairs be anticorrelated, if you insist on rotational invariance at every level. These two conditions lead to an apparent contradiction between the statics we invariable measure and the statistics and the statistics we apparently would have gotten using any other choice of settings besides what we actually measured, if the path through the polarizer was a real property of the photon.

Why a "greater range of presumptions"? Standard optics can be derived from Maxwell's laws, which is a perfect example of a local realist theory of physics, so Bell's theorem definitely applies to anything in optics (and it's impossible to use classical optics to get a violation of Bell inequalities).
The "greater range of presumptions" allowed is because the standards optics case alone does not have a reference case to question (in principle) how this set of photons would have been detected had we chosen detector settings differently. Maxwell's equations also described fields, leaving the particle behavior more or less out. How would you define the set of all individual variables such a field can define?

Note the original EPR paper hinged on conservation law. The randomized polarizations of the emitter alone statistically demands rotational invariance, irrespective of any underlying mechanism. Thus Malus law + conservation + statistical rotational invariance does lead to the same statistical contradictions.

We are left with a *fundamentally* statistical theory in which statistical outcomes can be deterministically determined in some cases, but lacks variables that can even in principle explain how the outcomes are predetermined.

Malus' law is only based on the difference in angle between the beam and the polarizer, so it doesn't get violated depending on how your coordinate system defines the angle of the beam. Are you suggesting otherwise?EXACTLY! Malus law is dependent only on the angle difference. Now note: A randomly polarized emitter physically must, irrespective of and underlying or lack of mechanism, be rotational invariant. So as long as 3 rules always apply, Malus law, rotational invariance, and conservation law, then BI violations must occur. If, statistically, rotational invariance applies, as it physically must for a randomly polarized beam, it does not mean the individual events defined by individual detections must also be rotational invariant, any more than Malus law.

I'm not entirely convinced by my own arguments, but I would appreciate more than hand waving the issues. Now, to argue against this, two things would be acceptable and appreciated:
1) Reject that rotational invariance can be induced simply by randomizing the polarization of the emitter, and explain why.
2) Accepting 1), explain why, if Malus law is dependent solely on angle difference and rotational invariance is dependent solely on randomized polarizations (not individual detection events), it could be expected that EPR correlations should depend on more than just the angle difference between the detector pairs.

You could also try to show that Malus law can be applied to any coordinate rotation rather than just a difference in rotation. You could also try to explain why Malus law + conservation + statistical rotational invariance does not lead to the same statistical contradictions.

JesseM

Jun28-10, 01:31 PM

The quantitative correspondence results when you apply the same same location rules to the photon polarizers interactions plus standard conservation requiring photon pairs be anticorrelated, if you insist on rotational invariance at every level.
Again, "quantitative correspondence" between what and what? Are you claiming that if we "apply the same same location rules to the photon polarizers interactions plus standard conservation requiring photon pairs be anticorrelated", that uniquely leads us to the statistics seen in QM? If so, what "same location rules" are you talking about, given that Malus' law deals with continuous decreases in intensity rather than the binary fact about whether a photon passes through a polarizer?
Note the original EPR paper hinged on conservation law. The randomized polarizations of the emitter alone statistically demands rotational invariance, irrespective of any underlying mechanism. Thus Malus law + conservation + statistical rotational invariance does lead to the same statistical contradictions.
Well, see above, it's not clear to me what you mean by "Malus law" in the context of detecting individual photons rather than looking at how the intensity of an electromagnetic wave changes when it passes through a polarizer.

my_wan

Jun28-10, 03:36 PM

Again, "quantitative correspondence" between what and what? Are you claiming that if we "apply the same same location rules to the photon polarizers interactions plus standard conservation requiring photon pairs be anticorrelated", that uniquely leads us to the statistics seen in QM? If so, what "same location rules" are you talking about, given that Malus' law deals with continuous decreases in intensity rather than the binary fact about whether a photon passes through a polarizer?
I'm only looking at how a photon responds to the polarizer it comes in contact with irrespective of what a distant correlated photon does, which requires Malus law in all cases. This also entails that a detector offset from the default photon polarization has some likelihood of passing that photon 'as if' it possessed that polarization. These odds defined by Malus law. Now to add an assumption: these photons have properties that predetermine how they will respond to any polarizer setting, such that an identical twin photon would have responded to a polarizer with the same arbitrary setting the same way. Opposite for anti-twins. Now, as long as the properties of the photons in the beam is, as a group, randomized such that rotational invariance must be maintained, and Malus law (with relative offsets) is required for all cases, the predeterminism assumption leads to BI violations, irrespective of any other consideration.

Here's the challenge: you CANNOT construct a local deterministic variable set, independent of QM, BI, etc., that respects Malus law for any arbitrary setting and rotational invariance without violating BI. You will invariably be stuck with the same relative offset requirements that Malus law is predicated on. This results without any reference to QM whatsoever. The effect may be local, at the point where photon meets polarizer, but the counterfactual requirement that the photon polarizer interaction is predetermined in all cases is effectively equivalent to what an anti-twin is doing light years away.

Are you seeing the difficulty here, when the impossibility logic is turned on its head? The same impossibility Bell demonstrated also points to an impossibility of maintaining Malus law without violating BI. Of course, as you noted, Malus law can be derived from Maxwell's equations, which is a classical field theory. So, unless you can deny the validity of the challenge, what does this say about the "reality" of classical fields? Perhaps the deterministic variables are transfinite? I don't know, but if you can successfully reject the validity of the challenge I'll be indebted to you.

DrChinese

Jun28-10, 03:43 PM

Are you seeing the difficulty here, when the impossibility logic is turned on its head? The same impossibility Bell demonstrated also points to an impossibility of maintaining Malus law without violating BI. Of course, as you noted, Malus law can be derived from Maxwell's equations, which is a classical field theory. So, unless you can deny the validity of the challenge, what does this say about the "reality" of classical fields? .

Yes, this is true (about Malus). However, this has nothing to do with some kind of "challenge" or impossiblity. Your logic does not work:

Malus-> Bell Inequality violation
QM-> Malus-> Bell Inequality violation

This is perfectly reasonable.

my_wan

Jun28-10, 04:50 PM

Yes, this is true (about Malus). However, this has nothing to do with some kind of "challenge" or impossiblity. Your logic does not work:

Malus-> Bell Inequality violation
QM-> Malus-> Bell Inequality violation

This is perfectly reasonable.

Not real sure I follow. Not even sure how to guess what you intended to say. My best guess is your saying "QM-> Malus-> Bell Inequality violation" is "perfectly reasonable", but still can't grok your intended meaning with any confidence.

If your summing up what I said as "Malus-> Bell Inequality violation" it's more than a little overly simplified, as is the implicit QM and BI issues. Are you saying that "Malus-> Bell Inequality violation" doesn't work, while "QM-> Malus-> Bell Inequality violation" does?

What I'm saying is that, even if you forget everything you know about QM, and merely try to construct a local realistic variable set that respects Malus law without violating BI, you can't do it. It is you who keeps insisting the similarity between Malus law and QM is an illusion, yet here I am presumptuously interpreting you to say Malus law is a QM law.

Here's an example of what you can't do. Define a set of photons with predefined properties which entails that 50% of all randomly polarized photons are predetermined to pass a polarizer at any angle. Then require the predetermined photon paths to switch paths through the polarizer according to Malus law as you rotate the polarizer. Now try and get this same predefined set of photons to continue honoring Malus law when you pick a pair of counterfactual detector setting in which neither setting is 0. It will not work, and this doesn't even involve correlations, only paths taken by a predefined set of photons through a variable polarizer setting. Without correlation you don't have a uniquely QM phenomena, yet BI violation persist in simple classical paths through a polarizer.

Does it now make sense why the QM requirement (I think) you imposed is not necessary for BI? Not even correlations are required, only assumptions of classical paths. Of course Maxwell's equations, in spite of being a classical construct, has no requirement of presuming photon trajectories represent a classical path, due to its field theoretic construction.

JesseM

Jun28-10, 04:53 PM

I'm only looking at how a photon responds to the polarizer it comes in contact with irrespective of what a distant correlated photon does, which requires Malus law in all cases.
How does Malus' law apply to individual photons, though? The classical version of Malus' law requires uniformly polarized light with a known polarization angle, are you talking about a photon that's known to be in a polarization eigenstate for a polarizer at some particular angle? In that case, whatever the angle v of the eigenstate, I think the probability the photon would pass through another angle at angle a would be cos^2(v-a). But when entangled photons are generated, would they be in such a known polarization eigenstate? If not it seems like you wouldn't be able to talk about Malus' law applying to individual members of the pair.
Of course, as you noted, Malus law can be derived from Maxwell's equations, which is a classical field theory. So, unless you can deny the validity of the challenge, what does this say about the "reality" of classical fields? Perhaps the deterministic variables are transfinite? I don't know, but if you can successfully reject the validity of the challenge I'll be indebted to you.
But with electromagnetic waves in Maxwell's equations there's no probabilities involved, Malus' law just represents a deterministic decrease in intensity. So there's no case where two detectors at different angles a and b have a probability cos^2(a-b) of opposite results, including the fact that they give opposite results with probability 1 with the detectors at the same angle. This is true even if you design the detectors to give one of two possible outputs depending on the decrease in intensity, as I suggested in post #896 to ThomasT. So no violations of BI and no reason Maxwell's laws can't be understood as a local realist theory, so I'm not sure why you have a problem with the reality of classical fields.

DrChinese

Jun28-10, 05:02 PM

Not real sure I follow. Not even sure how to guess what you intended to say. My best guess is your saying "QM-> Malus-> Bell Inequality violation" is "perfectly reasonable", but still can't grok your intended meaning with any confidence.

If your summing up what I said as "Malus-> Bell Inequality violation" it's more than a little overly simplified, as is the implicit QM and BI issues. Are you saying that "Malus-> Bell Inequality violation" doesn't work, while "QM-> Malus-> Bell Inequality violation" does?

What I'm saying is that, even if you forget everything you know about QM, and merely try to construct a local realistic variable set that respects Malus law without violating BI, you can't do it. It is you who keeps insisting the similarity between Malus law and QM is an illusion, yet here I am presumptuously interpreting you to say Malus law is a QM law.

Here's an example of what you can't do. Define a set of photons with predefined properties which entails that 50% of all randomly polarized photons are predetermined to pass a polarizer at any angle. Then require the predetermined photon paths to switch paths through the polarizer according to Malus law as you rotate the polarizer. Now try and get this same predefined set of photons to continue honoring Malus law when you pick a pair of counterfactual detector setting in which neither setting is 0. It will not work, and this doesn't even involve correlations, only paths taken by a predefined set of photons through a variable polarizer setting. Without correlation you don't have a uniquely QM phenomena, yet BI violation persist in simple classical paths through a polarizer.

Does it now make sense why the QM requirement (I think) you imposed is not necessary for BI? Not even correlations are required, only assumptions of classical paths. Of course Maxwell's equations, in spite of being a classical construct, has no requirement of presuming photon trajectories represent a classical path, due to its field theoretic construction.

OK, ask this: so what if Malus rules out local realistic theories per se? You are trying to somehow imply that is not reasonable. Well, it is.

We don't live in a world respecting BIs while we do live in one which Malus is respected. There is no contradiction whatsoever. You are trying to somehow say Malus is classical but it really isn't. It is simply a function of a quantum mechanical universe. So your logic needs a little spit polish.

billschnieder

Jun28-10, 07:40 PM

If you are doing an experiment which matches the condition of the Bell inequalities that says each measurement must yield one of two binary results....

This requirement by itself is unreasonable because according to Malus law, it is normal to expect that some photons will not go through the polarizer. Therefore Bell's insistence on having only binary outcomes (+1, -1) goes off the boat right from the start. He should have included a non-detection outcome too.

DevilsAvocado

Jun28-10, 07:43 PM

(my emphasis)
... Yes, of course I disagree, you're just totally misunderstanding the most basic logic of the proof which is assuming a perfect correlation between A and B whenever both experimenters choose the same detector setting. It's really rather galling that you make all these confident-sounding claims about Bell's proof being flawed when you fail to understand something so elementary about it! Could you maybe display a tiny bit of intellectual humility and consider the possibility that it might not be that the proof itself is flawed and that you've spotted a flaw that so many thousands of smart physicists over the years have missed, that it might instead be you are misunderstanding some aspects of the proof?

JesseM, thank you so very much for these very intelligent and well expressed words! You’ve hit the nail! THANKS!

And I can guarantee you that you are not the only one exasperated on ThomasT’s general attitude.

my_wan

Jun28-10, 08:04 PM

OK, ask this: so what if Malus rules out local realistic theories per se? You are trying to somehow imply that is not reasonable. Well, it is.

We don't live in a world respecting BIs while we do live in one which Malus is respected. There is no contradiction whatsoever. You are trying to somehow say Malus is classical but it really isn't. It is simply a function of a quantum mechanical universe. So your logic needs a little spit polish.

The claim that my logic needs a little spit polish is absolutely valid. That's part of why I debate these issues here, to articulate clear my own thinking on the matter.

I'm not making claims about what is or isn't reasonable. Here's the thing, so long as the terms "local" and "realistic" are well defined to be restricted to X and Y conceptions of those terms, I have no issue with the claim that X and/or Y conceptions are invalid. To generalize that claim as evidence that all conception of those terms is likewise invalid is technically dishonest. Reasonable? Perhaps.., but also presumptuous. It may not rise to the level of presumptuousness the realist in general tend toward, but I find it no less distasteful. It would likewise be a disservice to academically lock those terms as representative of certain singular conceptions.

Then there is a more fundamental theoretical issue. Correctly identifying the issues leading to certain empirical results can play an essential role in extending theory in unpredictable ways. To simply imply that if Malus alone can lead to BI violations is a vindication of some status quo interpretation is unwarranted. Your concretion is misplaced. Often the point of questioning the reason X is false is not to establish a claim of its truth value, but to gain insight to a wider range of questions. Teachers that would respond to enumerations of all the possible reasons something was false with: but the point is that it's false, missed the point entirely.

So, in spite of the justifications implied by Malus consequences lacking contradiction, what does it indicate when a preeminent classical theoretical construct predicts a consequence that violates BI? It certainly does NOT indicate that realism, as narrowly defined by EPR and Bell, erred in ruling out a particular form of realism. It does in fact question the generalization of BI to a broader range of conceptions of realism. It also directly brings into question the relevance of nonlocality, when the polarizer path version, resulting from a classical field construct, doesn't even have an existential partner to correlate with. The difficulties might even be a mathematical decomposition limitation, some akin to a la Gödel maybe? It also begs the question, if Maxwell's equations can produce a path version of BI violations, what besides quanta and the Born rule is fundamentally unique to QM, notwithstanding the claim of being fundamental?

I don't have the answers, but I'm not going to restrict myself to BI tunnel vision either.

JesseM

Jun28-10, 08:20 PM

This requirement by itself is unreasonable because according to Malus law, it is normal to expect that some photons will not go through the polarizer. Therefore Bell's insistence on having only binary outcomes (+1, -1) goes off the boat right from the start. He should have included a non-detection outcome too.
I'm pretty sure that in experiments with entangled photons, there is a difference between non-detection and not making it through the polarizer. For example, if you look at the description and diagram of a "typical experiment" in this section (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Example_of_typi cal_experiment) of the wikipedia article on Bell test loopholes, apparently if the two-channel polarizer like "a" doesn't allow a photon through to be detected at detector D+, it simply deflects it at a different angle to another detector D-, so the photon can be detected either way.

my_wan

Jun29-10, 02:16 AM

Had to get some sleep after that last post, I go too long sometimes.
How does Malus' law apply to individual photons, though? The classical version of Malus' law requires uniformly polarized light with a known polarization angle, are you talking about a photon that's known to be in a polarization eigenstate for a polarizer at some particular angle? In that case, whatever the angle v of the eigenstate, I think the probability the photon would pass through another angle at angle a would be cos^2(v-a). But when entangled photons are generated, would they be in such a known polarization eigenstate? If not it seems like you wouldn't be able to talk about Malus' law applying to individual members of the pair.
Yes, I'll restate this again. This is the statistics I have verified as an exact with Malus law expressed sole in terms of intensity for all pure or mixed polarization state beams, as well as cases of passage through arbitrary multiple polarizers. Malus consistency is predicated on modeling intensity, but it even perfectly models EPR correlations with the caveats given. It's a straight up assumption that individual photons, randomly polarized as a group or not, has a very definite default polarization. The default polarization is unique only in that it is the only polarization at which a polarizer with a matching setting effectively has a 100% chance of passing that photon. The odds of any given photon passing a polarizer that is offset from that default is defined by a straight up assumption that ∆I (intensity) constitutes a ∆p (odds), i.e., for any arbitrary theta offset from the individual photons default ∆I = ∆p.

But with electromagnetic waves in Maxwell's equations there's no probabilities involved, Malus' law just represents a deterministic decrease in intensity. So there's no case where two detectors at different angles a and b have a probability cos^2(a-b) of opposite results, including the fact that they give opposite results with probability 1 with the detectors at the same angle. This is true even if you design the detectors to give one of two possible outputs depending on the decrease in intensity, as I suggested in post #896 to ThomasT. So no violations of BI and no reason Maxwell's laws can't be understood as a local realist theory, so I'm not sure why you have a problem with the reality of classical fields.Yes, neither does Maxwell's equations explicitly recognize the particle aspect of photons, thus lacked any motivation for assigning probabilities to individual photons. But as noted, ∆I = ∆p perfectly recovers the proper Malus predicted intensities in all pure and mixed state beams, as well as ∆I in stacked (series) polarizer cases. The EPR case is a parallel case involving anti-twins.

At no point, in modeling Malus intensities or EPR correlation, did I use cos^2(a-b), where a and b represented different polarizers. I've already argued with ThomasT over this point. I used cos^2(theta), where theta is defined solely as the offset of the polarizer relative to the photon that actually comes in contact with that polarizer. In fact, since the binary bit field that predetermined outcomes already had cos^2(theta) statistically built in, I didn't even have to calc cos^2(theta) at detection time. I merely did a linear one to one count into the bit field defined by theta (between polarizer and the photon that actually came in contact with it) alone, took that bit and passed it if it was a 1, diverted if 0. I used precisely the same rules, in the computer models, in both Malus intensity and parallel EPR cases, and only compared EPR correlations after the fact.

To clarify, the bit field I used to predetermine outcomes, to computer model both Malus intensities and EPR parallel cases, set a unique bit for each offset, such that a photon that passed at a given offset could sometimes fail at a lesser offset. The difficulties arose only the the EPR modeling case when it only successfully modeled BI violations correlations when one or the other detector was defined as 0. Yet uniformly rotating the default polarizations of the randomly polarized beam changed which individual photons took what path it had no effect whatsoever on the BI violated statistics. The EPR case, like the Malus intensities, was limited to relative coordinates only wrt detector settings. Absolute values didn't work, in spite of the beam rotation statistical invariance with individual photon path variance.

Maxwell's equations didn't assign a unique particulate identity to individual photons. Yet, if consider classically distinct paths as a real property of a particulate photon (duality), you can construct BI violations from path assumptions required to model Malus law. It's easy to hand wave away when were talking a local path through a local polarizer, until you think about it. In fact the path version of BI violation only become an issue when you require absolute arbitrary coordinates, rather than relative offsets, to model. The same issue that is the sticking point in modeling EPR BI violations.

my_wan

Jun29-10, 03:14 AM

I was looking over DrC's Frankenstein particles and read the wiki page JesseM linked:
http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments
Where it mentions a possible failure of of rotational invariance and realized it should be possible, if the Malus law assumptions I used is valid, to construct a pair of correlated beams that explicitly fails rotational invariance.

I need to think through it more carefully, but it would involve using a PBS to split both channels from the source emitter. Use a shutter to selectively remove some percentage of both correlated pairs of a certain polarization, and recombine the remainder. Similar to DrC's Frankenstein setup. Done such that all remaining photons after recombination should have a remaining anti-twin, which, as a group, has a statistically prefered polarization. The only photons that can be defined as observed, and their partners, are no longer present in the beam to effect the correlation statistics. Then observe the effects on correlation statistics at various common detector settings and offsets. The possible variations of this is quiet large.

Edit: A difficulty arises when you consider that while photons are being being shuttered in one side of the polarized beam, before recombination, any photon that takes the other path at that time can be considered detected. Non-detection in QM can sometime qualify as a detection in QM.

ThomasT

Jun29-10, 04:40 AM

... it might instead be you are misunderstanding some aspects of the proof ...Of course, that's why I'm still asking questions.

The joint probability P(AB) is not being modelled as the product of P(A)*P(B) by Bell's equation.

My thinking has been that it reduces to that. Just a stripped down shorthand for expressing Bell's separability requirement. If you don't think that's ok, then how would you characterize the separability of the joint state (ie., the expression of locality) per Bell's (2)?

I would characterize it in terms of A and B being statistically independent only when conditioned on the value of the hidden variable λ. They are clearly not statistically independent otherwise ...

A and B are not independent in their marginal probabilities (which determine the actual observed frequencies of different measurement outcomes), only in their probabilities conditioned on λ.

Ok, you seem to be saying that P(AB)=P(A) P(B) isn't an analog of Bell's (2). You also seem to be saying that Bell's (2) models A and B as statistically independent for all joint settings except (a-b)=0. Is this correct?

My thinking has been that Bell's(2) is a separable representation of the entangled state, and that this means that it models the joint state in a factorable form. Is this correct? If so, then is this the explicit expression of Bell locality in Bell's (2).

DevilsAvocado

Jun29-10, 06:06 AM

JesseM, please correct me if I’m wrong, but haven’t you already answer the question above perfectly clear??

... Yes, and this was exactly the possibility that Bell was considering! If you don't see this, then you are misunderstanding something very basic about Bell's reasoning. If A and B have a statistical dependence, so P(A|B) is different than P(A), but this dependence is fully explained by a common cause λ, then that implies that P(A|λ) = P(A|λ,B), i.e. there is no statistical dependence when conditioned on λ. That's the very meaning of equation (2) in Bell's original paper, that the statistical dependence which does exist between A and B is completely determined by the state of the hidden variables λ, and so the statistical dependence disappears when conditioned on λ. Again, please tell me if you disagree with this.

Could we also make it as simple that even a 10-yearold can understand, by stating:

Bell's(2) is not about entanglement, Bell's(2) is only about the Hidden variable λ.

JesseM

Jun29-10, 07:30 AM

Of course, that's why I'm still asking questions.
I'm glad you're still asking questions, but if you don't really understand the proof, and you do know it's been accepted as valid for years by mainstream physicists, doesn't it make sense to be a little more cautious about making negative claims about it like this one from an earlier post?
I couldn't care less if nonlocality or ftl exist or not. In fact, it would be very exciting if they did. But the evidence just doesn't support that conclusion.
On to the topic of probabilities:
Ok, you seem to be saying that P(AB)=P(A) P(B) isn't an analog of Bell's (2). You also seem to be saying that Bell's (2) models A and B as statistically independent for all joint settings except (a-b)=0. Is this correct?
No. In any Bell test, the marginal probability of getting either of the two possible results (say, spin-up and spin-down) should always be 0.5, so P(A)=P(B)=0.5. But if you're doing an experiment where the particles always give identical results with the same detector setting, then if you learn the other particle gave a given result (like spin-up) with detector setting b and you're using detector setting a, then the conditional probability your particle gives the same result is cos^2(a-b). So if A and B are identical results, in this case P(AB)=P(B)*P(A|B)=0.5 * cos^2(a-b), so as long as a and b have an angle between them that's something other than 45 degrees (since cos^2(45) = 0.5), P(AB) will be different than P(A)*P(B), and there is a statistical dependence between them.
My thinking has been that Bell's(2) is a separable representation of the entangled state, and that this means that it models the joint state in a factorable form. Is this correct? If so, then is this the explicit expression of Bell locality in Bell's (2).
It shows how the joint probability can be separated into the product of two independent probabilities if you condition on the hidden variables λ. So, P(AB|abλ)=P(A|aλ)*P(B|bλ) can be understood as an expression of the locality condition. But he obviously ends up proving that this doesn't work as a way of modeling entanglement...it's really only modeling a case where A and B are perfectly correlated (or perfectly anticorrelated, depending on the experiment) whenever a and b are the same, under the assumption that there is a local explanation for this perfect correlation (like the particles being assigned the same hidden variables by the source that created them).

DrChinese

Jun29-10, 09:35 AM

The claim that my logic needs a little spit polish is absolutely valid. That's part of why I debate these issues here, to articulate clear my own thinking on the matter.

That is why I participate too. :smile:

DrChinese

Jun29-10, 09:37 AM

DrChinese

Jun29-10, 09:49 AM

I want to make an important statement that counters the essence of some of the arguments being presented about "non-detections" or detector effeciency.

A little thought will tell you why this is not much of an issue. If we have a particle pair A, B and we send them through a beam splitter with detectors at both output ports, we should end up with one of the following 4 cases:

1. A not detected, B not detected.
2. A detected, B not detected.
3. A not detected, B detected.
4. A detected, B detected.

However we won't actually know when case 1 occurs, correct? But unless the chance of 1 is substantially greater than either 2 or 3 individually (and probability logic indicates it should be definitely less - can you see why?), then we can estimate it. If case 4 occurs 50% of the time or more, then 1 should occur less than 10% of the time. This is in essence a vanishing number, since visibility is approaching 90%. That means cases 2 and 3 are happening only about 1 in 10, which would imply case 1 of about 1%.

So you have got to claim all of the "missing" photons are carrying the values that would prove a different result. And this number is not much. I guess it is *possible* if there is a physical mechanism which is responsible for the non-detections, but that would also make it experimentally falsifiable. But you should be aware of how far-fetched this really is. In other words, in actual experiments cases 2 and 3 don't occur very often. Which places severe constraints on case 1.

DevilsAvocado

Jun29-10, 10:01 AM

It shows how the joint probability can be separated into the product of two independent probabilities if you condition on the hidden variables λ. So, P(AB|abλ)=P(A|aλ)*P(B|bλ) can be understood as an expression of the locality condition. But he obviously ends up proving that this doesn't work as a way of modeling entanglement...it's really only modeling a case where A and B are perfectly correlated (or perfectly anticorrelated, depending on the experiment) whenever a and b are the same, under the assumption that there is a local explanation for this perfect correlation (like the particles being assigned the same hidden variables by the source that created them).

This must mean that my "10-yearold explanation" is correct, and hopefully this information can even make sense to ThomasT:

Bell's(2) is not about entanglement, Bell's(2) is only about the Hidden variable λ.

No. In any Bell test, the marginal probability of getting either of the two possible results (say, spin-up and spin-down) should always be 0.5, so P(A)=P(B)=0.5. But if you're doing an experiment where the particles always give identical results with the same detector setting, then if you learn the other particle gave a given result (like spin-up) with detector setting b and you're using detector setting a, then the conditional probability your particle gives the same result is cos^2(a-b). So if A and B are identical results, in this case P(AB)=P(B)*P(A|B)=0.5 * cos^2(a-b), so as long as a and b have an angle between them that's something other than 45 degrees (since cos^2(45) = 0.5), P(AB) will be different than P(A)*P(B), and there is a statistical dependence between them.

Could we make a 'simplification' of this also, and say:

According to QM predictions, all depends on the relative angle between the polarizers a & b. If measured parallel (0º) or perpendicular (90º) the outcome is perfectly correlated/anticorrelated. In any other case, it’s statistically correlated thru QM predictions cos^2(a-b).

Every outcome on every angle is perfectly random for A & B, with one 'exception' for parallel and perpendicular, where the outcome for A must be perfectly correlated/anticorrelated to B (still individually perfectly random).

Correct?

DevilsAvocado

Jun29-10, 10:20 AM

... However we won't actually know when case 1 occurs, correct?

DrC, could you help me out? I must be stupid...

If we use a beam splitter, then we always get a measurement, unless something goes wrong. Doesn’t this mean we would know that case 1 has occurred = nothing + nothing?? :uhh:

DrChinese

Jun29-10, 10:44 AM

DrC, could you help me out? I must be stupid...

If we use a beam splitter, then we always get a measurement, unless something goes wrong. Doesn’t this mean we would know that case 1 has occurred = nothing + nothing?? :uhh:

That is the issue everyone is talking about, except it really doesn't fly. Normally, and in the ideal case, a photon going through a beam splitter comes out either the H port or the V port. Hypothetically, photon Alice might never emerge in line, or might not trigger the detector, or something else goes wrong. So neither of the 2 detectors for Alice fires. Let's say that happens 1 in 10 times, and we can see it happening because one of the Bob detectors fires.

Ditto for Bob. There might be a few times in which the same thing happens on an individual trial for both Alice and Bob. If usual probability laws are applied, you might expect something like the following:

Neither detected: 1%.
Alice or Bob not detected, but not both: 18%.
Alice and Bob both detected: 81%.

I would call this visibility of about 90% which is about where things are at in experiments these days. But you cannot say FOR CERTAIN that the 1 case only occurs 1% of the time, you must estimate using an assumption. But if you *assert* that the 1 case occurs a LOT MORE OFTEN than 1% and you STILL have a ratio of 81% to 18% per above (as these are experimentally verifiable of course), then you have a lot of explaining to do.

And you will need all of it to make a cogent argument to that effect. Since any explanation will necessarily be experimentally falsifiable. The only way you get around this is NOT to supply an explanation. Which is the usual path when this argument is raised. So visibility is a function of everything involved in the experiment, and it is currently very high. I think around 85% + range but it varies from experiment to experiment. I haven't seen good explanations of how it is calculated or I would provide a reference. Perhaps someone else knows a good reference on this.

JesseM

Jun29-10, 11:08 AM

This must mean that my "10-yearold explanation" is correct, and hopefully this information can even make sense to ThomasT:

Bell's(2) is not about entanglement, Bell's(2) is only about the Hidden variable λ.
Basically I'd agree, although I'd make it a little more detailed: (2) isn't about entanglement, it's about the probabilities for different combinations of A and B (like A=spin-up and B=spin down) for different combinations of detector settings a and b (like a=60 degrees, b=120 degrees), under the assumption that there is a perfect correlation between A and B when both sides use the same detector setting, and that this perfect correlation is to be explained in a local realist way by making use of hidden variable λ.
Could we make a 'simplification' of this also, and say:

According to QM predictions, all depends on the relative angle between the polarizers a & b. If measured parallel (0º) or perpendicular (90º) the outcome is perfectly correlated/anticorrelated. In any other case, it’s statistically correlated thru QM predictions cos^2(a-b).

Every outcome on every angle is perfectly random for A & B, with one 'exception' for parallel and perpendicular, where the outcome for A must be perfectly correlated/anticorrelated to B (still individually perfectly random).

Correct?
By "perfectly random" you just mean that if we look at A individually or B individually, without knowing what happened at the other one, then there's always an 0.5 chance of one result and an 0.5 chance of the opposite result, right? (so P(A|a)=P(B|b)=0.5) And this is still just as true when talk about the "exception" case of parallel or perpendicular detectors (as you point out when you say 'still individually perfectly random'), so it could be a little misleading to call this an "exception", but otherwise I have no problem with your summary.

DevilsAvocado

Jun29-10, 11:18 AM

... I haven't seen good explanations of how it is calculated or I would provide a reference. Perhaps someone else knows a good reference on this.

Thanks for the info DrC.

DevilsAvocado

Jun29-10, 11:24 AM

... this perfect correlation is to be explained in a local realist way by making use of hidden variable λ.
Yes, this is obviously the key.
By "perfectly random" you just mean that if we look at A individually or B individually, without knowing what happened at the other one, then there's always an 0.5 chance of one result and an 0.5 chance of the opposite result, right? (so P(A|a)=P(B|b)=0.5) And this is still just as true when talk about the "exception" case of parallel or perpendicular detectors (as you point out when you say 'still individually perfectly random'), so it could be a little misleading to call this an "exception", but otherwise I have no problem with your summary.
Correct, that’s what I meant. Thanks!

billschnieder

Jun29-10, 02:08 PM

Not with beam splitters! (Non-detection is not an issue ever, as we talk about the ideal case. Experimental tests must consider this.)

1) Non-detection is present in every bell-test experiment ever performed
2) The relevant beam-splitters are real ones used in real experiments, not idealized ones that have never and can never be used in any experiment.

Bell should still have considered non-detection as one of the outcomes in addition to (-1, and +1). If you are right that non-detection is not an issue, the inequalities derived by assuming there are three possible outcomes right from the start, should also be violated. But if you do this and end up with an inequality that is no longer violated, then non-detection IS an issue.

billschnieder

Jun29-10, 02:57 PM

A little thought will tell you why this is not much of an issue. If we have a particle pair A, B and we send them through a beam splitter with detectors at both output ports, we should end up with one of the following 4 cases:

1. A not detected, B not detected.
2. A detected, B not detected.
3. A not detected, B detected.
4. A detected, B detected.

Correct.
In Bell's treatment, only case 4 is considered, the rest are simply ignored or assumed to not be possible.

However we won't actually know when case 1 occurs, correct? But unless the chance of 1 is substantially greater than either 2 or 3 individually (and probability logic indicates it should be definitely less - can you see why?), then we can estimate it. If case 4 occurs 50% of the time or more, then 1 should occur less than 10% of the time. This is in essence a vanishing number, since visibility is approaching 90%. That means cases 2 and 3 are happening only about 1 in 10, which would imply case 1 of about 1%.
This is not even wrong. It is outrageous. Case 1 corresponds to two photons leaving the source but none detected, cases 2-3 correspond to two photons leaving the source and only one detected on any of the channels. In Bell test experiments, coincidence-circuitry eliminates 1-3 from consideration because there is no way in the inequalities to include that information. The inequalities are derived assuming that only case 4 is possible.

To determine likelihood of each case from relative frequencies, you will need to count that specific case, and divide by the total number for all cases (1-5), or alternatively, all photon pairs leaving the source. Therefore, the relative frequency will be the total number of the specific case observed divided by the total number of photon pairs produced by the source.
ie: P(caseX) = N(caseX) / { N(case1) + N(case2) + N(case3) + N(case4)}

If you are unable to tell that case 4 has occurred, then you can never know what proportion of the particle pairs resulted in any of the cases, because N(case4) is part of the denominator!!

So when you say "if case 4 occurs 50% of the time", you have to explain what represents 100%.
for example consider the following frequencies, for the case in which 220 particle pairs are produced and we have:

case 1: 180
case 2: 10
case 3: 10
case 4: 20

Since according to you, we can not know when case 1 occurs, then our total is only (40)
according to you, P(case4) = 50% and P(case2) = 25% P(case 3) = 25%
according to you, P(case1) should be vanishingly small since P(case4) is high.

But as soon as you realize that our total is actually 220 not 40 as you mistakenly thought,
P(case1) now becomes 82%, for exactly the same experiment, just by correcting the simple error you made.
It is even worse with Bell because according to him, cases 1-3 do not exist so his P(case4) is 100%, since considering even only case 2 and 3 as you suggested would required including a non-detection outcome as well as (+1 and -1).

Now that this blatant error is clear, let us look at real experiments to see which approach is more reasonable, by looking at what proportion of photons leaving the source is actually detected.

For all Bell-test experiments performed to date, only 5-30% of the photons emitted by the detector have been detected, with only one exception. And this exception, which I'm sure DrC and JesseM will remind us of, had other more serious problems. Let us make sure we are clear what this means.

It means of almost all those experiments usually thrown around as proof of non-locality, P(case4) has been at most 30% and even as low as 30% in some cases. The question then is, where did the whopping 70% go?

Therefore it is clear first of all by common sense, then by probability theory, and finally confirmed by numerous experiments that non-detection IS an issue and should have been included in the derivation of the inequalities!

DrChinese

Jun29-10, 03:01 PM

1) Non-detection is present in every bell-test experiment ever performed
2) The relevant beam-splitters are real ones used in real experiments, not idealized ones that have never and can never be used in any experiment.

Bell should still have considered non-detection as one of the outcomes in addition to (-1, and +1). If you are right that non-detection is not an issue, the inequalities derived by assuming there are three possible outcomes right from the start, should also be violated. But if you do this and end up with an inequality that is no longer violated, then non-detection IS an issue.

Did you read what I said? I said non-detection DO matter in experiments. But not in a theoretical proof such as Bell.

billschnieder

Jun29-10, 03:30 PM

Did you read what I said? I said non-detection DO matter in experiments. But not in a theoretical proof such as Bell.

Therefore correlations observed in real experiments in which non-detection matters can not be compared to idealized theoretical proofs in which non-detection was not considered since those idealized theoretical proofs made assumptions that will never be fulfilled in any real experiments.

QM works because it is not an idealized theoretical proof, it actually incorporates and accounts for the experimental setup. It is therefore not surprising that QM and real experiments agree while Bell's inequalities are the only ones left hanging in the cold.

DrChinese

Jun29-10, 03:32 PM

Correct.
In Bell's treatment, only case 4 is considered, the rest are simply ignored or assumed to not be possible.

This is not even wrong. It is outrageous. Case 1 corresponds to two photons leaving the source but none detected, cases 2-3 correspond to two photons leaving the source and only one detected on any of the channels. In Bell test experiments, coincidence-circuitry eliminates 1-3 from consideration because there is no way in the inequalities to include that information. The inequalities are derived assuming that only case 4 is possible.

Oh really. Cases 2 and 3 are quite observed and recorded. They are usually excluded from counting because of the Coincidence Time Window, this is true. But again, this is just a plain misunderstanding of the process. You cannot actually have the kind of stats you describe because the probability p(1)=p(2)*p(3)=p(2)^2 and p(4)=1 - p(1). Now this is approximate and there hypothetically could be a force or something that causes deviation. But as mentioned, that would require a physically testable hypothesis.

As far as I can see, there is currently very high detection efficiencies. From Zeilinger et al:

These can be characterized individually by measured visibilities, which were: for the source, ≈ 99% (98%) in the H/V (45°/135°) basis; for both Alice’s and Bob’s polarization analyzers, ≈ 99%; for the fibre channel and Alice’s analyzer (measured before each run), ≈ 97%, while the free-space link did not observably reduce Bob’s polarization visibility; for the effect of accidental coinci-dences resulting from an inherently low signal-to-noise ratio (SNR), ≈ 91% (including both dark counts and multipair emissions, with 55 dB two-photon attenuation and a 1.5 ns coincidence window).

Violation by 16 SD over 144 kilometers.
http://arxiv.org/abs/0811.3129

Or perhaps:

(You just have to read this as it addresses much of these issues directly. Suffice it to say that they address the issue of collection of pairs from PDC very nicely.)

Violation by 213 SD.
http://arxiv.org/abs/quant-ph/0303018

DrChinese

Jun29-10, 03:34 PM

Therefore correlations observed in real experiments in which non-detection matters can not be compared to idealized theoretical proofs in which non-detection was not considered since those idealized theoretical proofs made assumptions that will never be fulfilled in any real experiments.

You know, if there were only 1 experiment ever performed you might be correct. But this issue has been raised, addressed and ultimately rejected as on ongoing issue over and over.

JesseM

Jun29-10, 03:34 PM

Did you read what I said? I said non-detection DO matter in experiments. But not in a theoretical proof such as Bell.
Yes, Bell's proof was just showing that the theoretical predictions of QM were incompatible with the theoretical predictions of local realism, not derive equations that were directly applicable to experiments. Though as I've already said, you can derive inequalities that include detector efficiency as a parameter, and there have been at least a few experiments with sufficiently high detector efficiency such that these inequalities are violated (though these experiments were vulnerable to the locality loophole).

A few papers I came across suggested that experiments which closed both the detector efficiency loophole and the locality loophole simultaneously would likely be possible fairly soon. If someone offered to bet Bill a large sum of money that the results of these experiments would continue to match the predictions of QM (and thus continue to violate Bell inequalities that take into account detector efficiency), would Bill bet against them?

billschnieder

Jun29-10, 03:44 PM

If someone offered to bet Bill a large sum of money that the results of these experiments would continue to match the predictions of QM (and thus continue to violate Bell inequalities that take into account detector efficiency), would Bill bet against them?
What has this got to do with anything. If there was a convincing experiment which fulfilled all the assumptions in Bell's derivation, I would change my mind. I am after the truth, I don't religiously follow one side just because I have invested my whole life to it. So why would I want to bet at all.

I am merely pointing out here that the so-called proof of non-locality is unjustified, which is not the same as saying there will never be any proof. it seems from your suggestion thatyou are already absolutely convinced of non-locality, so would you bet a large sum of money against the idea that non-locality will be found to be a serious misunderstanding?

billschnieder

Jun29-10, 03:56 PM

BTW,
Even if an experimenter ensured 100% detection efficiency, they still have to ensure cyclicity in their data, as illustrated http://www.physicsforums.com/showpost.php?p=2766980&postcount=110

Surprisingly, you both artfully avoid addressing this example which clearly shows a mechanism for violating the inequalities that has nothing to do with detection efficiency.

Bell derives inequalities by assuming that a single particle is measured at multiple angles. Experiments are performed in which many different particles are measured at multiple angles. Apples vs oranges. Comparing the two is equivalent to comparing the average height obtained by measuring a single person's height 1000000 times, with the average height obtained by measuring 1000000 different people each exactly one time.

The point is that certain assumptions are made about the data when deriving the inequalities, that must be valid in the data-taking process. God is not taking the data, so the human experimenters must take those assumptions into account if their data is to be comparable to the inequalities.

Consider a certain disease that strikes persons in different ways depending on circumstances. Assume that we deal with sets of patients born in Africa, Asia and Europe (denoted a,b,c). Assume further that doctors in three cities Lyon, Paris, and Lille (denoted 1,2,3) are are assembling information about the disease. The doctors perform their investigations on randomly chosen but identical days (n) for all three where n = 1,2,3,...,N for a total of N days. The patients are denoted Alo(n) where l is the city, o is the birthplace and n is the day. Each patient is then given a diagnosis of A = +1/-1 based on presence or absence of the disease. So if a patient from Europe examined in Lille on the 10th day of the study was negative, A3c(10) = -1.

According to the Bell-type Leggett-Garg inequality

Aa(.)Ab(.) + Aa(.)Ac(.) + Ab(.)Ac(.) >= -1

In the case under consideration, our doctors can combine their results as follows

A1a(n)A2b(n) + A1a(n)A3c(n) + A2b(n)A3c(n)

It can easily be verified that by combining any possible diagnosis results, the Legett-Garg inequalitiy will not be violated as the result of the above expression will always be >= -1, so long as the cyclicity (XY+XZ+YZ) is maintained. Therefore the average result will also satisfy that inequality and we can therefore drop the indices and write the inequality only based on place of origin as follows:

<AaAb> + <AaAc> + <AbAc> >= -1

Now consider a variation of the study in which only two doctors perform the investigation. The doctor in Lille examines only patients of type (a) and (b) and the doctor in Lyon examines only patients of type (b) and (c). Note that patients of type (b) are examined twice as much. The doctors not knowing, or having any reason to suspect that the date or location of examinations has any influence decide to designate their patients only based on place of origin.

After numerous examinations they combine their results and find that

<AaAb> + <AaAc> + <AbAc> = -3

They also find that the single outcomes Aa, Ab, Ac, appear randomly distributed around +1/-1 and they are completely baffled. How can single outcomes be completely random while the products are not random. After lengthy discussions they conclude that there must be superluminal influence between the two cities.

But there are other more reasonable reasons. Note that by measuring in only two citites they have removed the cyclicity intended in the original inequality. It can easily be verified that the following scenario will result in what they observed:

- on even dates Aa = +1 and Ac = -1 in both cities while Ab = +1 in Lille and Ab = -1 in Lyon
- on odd days all signs are reversed

In the above case
<A1aA2b> + <A1aA2c> + <A1bA2c> >= -3
which is consistent with what they saw. Note that this equation does NOT maintain the cyclicity (XY+XZ+YZ) of the original inequality for the situation in which only two cities are considered and one group of patients is measured more than once. But by droping the indices for the cities, it gives the false impression that the cyclicity is maintained.

The reason for the discrepancy is that the data is not indexed properly in order to provide a data structure that is consistent with the inequalities as derived.Specifically, the inequalities require cyclicity in the data and since experimenters can not possibly know all the factors in play in order to know how to index the data to preserve the cyclicity, it is unreasonable to expect their data to match the inequalities.

For a fuller treatment of this example, see Hess et al, Possible experience: From Boole to Bell. EPL. 87, No 6, 60007(1-6) (2009)

The key word is "cyclicity" here. Now let's look at various inequalities:

Bell's equation (15):
1 + P(b,c) >= | P(a,b) - P(a,c)|
a,b, c each occur in two of the three terms. Each time together with a different partner. However in actual experiments, the (b,c) pair is analyzed at a different time from the (a,b) pair so the bs are not the same. Just because the experimenter sets a macroscopic angle does not mean that the complete microscopic state of the instrument, which he has no control over is in the same state.

CHSH:
|q(d1,y2) - q(a1,y2)| + |q(d1,b2)+q(a1,b2)| <= 2
d1, y2, a1, b2 each occur in two of the four terms. Same argument above applies.

Leggett-Garg:
Aa(.)Ab(.) + Aa(.)Ac(.) + Ab(.)Ac(.) >= -1

JesseM

Jun29-10, 04:11 PM

What has this got to do with anything. If there was a convincing experiment which fulfilled all the assumptions in Bell's derivation, I would change my mind.
What do you mean by "assumptions", though? Are you just talking about the assumptions about the observable experimental setup, like spacelike separation between measurements and perfect detection of all pairs (or a sufficiently high number of pairs if we are talking about a derivation of an inequality that includes detector efficiency as a parameter)? Or are you including theoretical assumptions like the idea that the universe obeys local realist laws and that there is some set of local variables λ such that P(AB|ab)=P(A|aλ)*P(B|bλ)? Of course Bell would not expect that any real experiment could fulfill those theoretical assumptions, since he believed the predictions of QM were likely to be correct and his proof was meant to be a proof-by-contradiction showing these theoretical assumptions lead to predictions incompatible with QM under the given observable experimental conditions.
I am merely pointing out here that the so-called proof of non-locality is unjustified
You can only have "proofs" of theoretical claims, for empirical claims you can build up evidence but never prove them with perfect certainty (we can't 'prove' the Earth is round, for example). Bell's proof is not intended to be a proof that non-locality is real in the actual world, just that local realism is incompatible with QM. Of course you apparently doubt some aspects of this purely theoretical proof, like the idea that in any local realist universe it should be possible to find a set of local variables λ such that P(AB|ab)=P(A|aλ)*P(B|bλ), but you refuse to engage in detailed discussion on such matters. In any case I would say the evidence is strong that QM's predictions about Aspect-type experiments are correct, even if there are a few loopholes like the fact that no experiment has simultaneously closed the detector efficiency and locality loopholes (but again, I think it would be impossible to find a local realist theory that exploited both loopholes in a way consistent with the experiments that have been done so far but didn't look extremely contrived).
it seems from your suggestion thatyou are already absolutely convinced of non-locality, so would you bet a large sum of money against the idea that non-locality will be found to be a serious misunderstanding?
Personally I tend to favor the many-worlds interpretation of QM, which could allow us to keep locality by getting rid of the implicit assumption in Bell's proof that every measurement must have a unique outcome (to see how getting rid of this can lead to a local theory with Bell inequality violations, you could check out my post #11 on this thread ( http://www.physicsforums.com/showthread.php?t=206291) for a toy model, and post #8 on this thread (http://www.physicsforums.com/showthread.php?t=221870) gives references to various MWI advocates who say it gives a local explanation for BI violations). I would however bet a lot of money that A) future Aspect-type experiments will continue to match the predictions of QM about Bell inequality violations, and B) mainstream physicists aren't going to end up deciding that Bell's theoretical proof is fundamentally flawed and that QM is compatible with a local realist theory that doesn't have any of the kinds of "weird" features that are included as loopholes in rigorous versions of the proof (like many-worlds, or like 'conspiracies' in past conditions that create a correlation between the choice of detector setting and the state of hidden variables at some time earlier than when the choice is made)

DrChinese

Jun29-10, 04:13 PM

GeorgCantor

Jun29-10, 04:38 PM

24 000 hits and still going... Einstein is probably turning in his grave at the way the EPR argument is still going and going...

JesseM

Jun29-10, 04:49 PM

BTW,
Even if an experimenter ensured 100% detection efficiency, they still have to ensure cyclicity in their data, as illustrated http://www.physicsforums.com/showpost.php?p=2766980&postcount=110

Surprisingly, you both artfully avoid addressing this example which clearly shows a mechanism for violating the inequalities that has nothing to do with detection efficiency.
I did respond to that post, but I didn't end up responding to your later post #128 on the subject here (http://www.physicsforums.com/showpost.php?p=2771935&postcount=128) because before I got to it you said you didn't want to talk to me any more unless I agreed to make my posts as short as you wanted them to be and for me not to include discussions of things I thought were relevant if you didn't agree they were relevant. But since you bring it up, I think you're just incorrect in saying in post #128 that the Leggett-Garg inequality is not intrinsically based on a large collection of trials where on each trial we measure the same system at 2 of 3 possible times (as opposed to measuring two parts of an entangled system with 1 of several possible combinations detector settings as with other inequalities)--see this paper (http://www-thphys.physics.ox.ac.uk/people/ArdLouis/Thesis/appendix.ps) and this abstract (http://www.nature.com/nphys/journal/v6/n6/full/nphys1641.html) which both describe it using terms like "temporal inequality" and "inequality in time", for example. I also found the paper where you got the example with patients from different countries here (http://iopscience.iop.org/0295-5075/87/6/60007/fulltext), they explain in the text around equation (8) what the example (which doesn't match the conditions assumed in the Leggett-Garg inequality) has to do with the real Leggett-Garg inequality:
Realism plays a role in the arguments of Bell and followers because they introduce a variable λ representing an element of reality and then write

\Gamma = <A_a(\lambda)A_b(\lambda)> + <A_a(\lambda)A_c(\lambda)> + <A_b(\lambda)A_c(\lambda)> \, \geq -1 \, (8)

Because no λ exists that would lead to a violation except a λ that depends on the index pairs (a, b), (a, c) and (b, c) the simplistic conclusion is that either elements of reality do not exist or they are non-local. The mistake here is that Bell and followers insist from the start that the same element of reality occurs for the three different experiments with three different setting pairs. This assumption implies the existence of the combinatorial-topological cyclicity that in turn implies the validity of a non-trivial inequality but has no physical basis. Why should the elements of reality not all be different? Why should they, for example not include the time of measurement?
If you look at that first paper (http://www-thphys.physics.ox.ac.uk/people/ArdLouis/Thesis/appendix.ps) they mention on p. 2 that in deriving the inequality we assume each particle is assumed to be in one of the two possible states at all times, so each particle has a well-defined classical "history" of the type shown in the diagram at the top of p. 4, and we assume there is some well-defined probability distribution on the ensemble of all possible classical histories. They also mention at the bottom of p. 3 that deriving the inequality requires that we assume it is possible to make "noninvasive measurements", so the choice of which of 3 times to make our first measurement does not influence the probability of different possible classical histories. They mention that this assumption can also be considered a type of "locality in time". This assumption is a lot more questionable than the usual type of locality assumed when there is a spacelike separation between measurements, since nothing in local realism really should guarantee that you can make "noninvasive" measurements on a quantum system which don't influence its future evolution after the measurement. And this also seems to be the assumption the authors are criticizing in the quote above when they say 'Why should the elements of reality not all be different? Why should they, for example not include the time of measurement?' (I suppose the λ that appears in the equation in the quote represents a particular classical history, so the inequality would hold as long as the probability distribution P(λ) on different possible classical histories is independent of what pair of times the measurements are taken on a given trial.) So this critique appears to be rather specific to the Leggett-Garg inequality, maybe you could come up with a variation for other inequalities but it isn't obvious to me (I think the 'noninvasive measurements' condition would be most closely analogous to the 'no-conspiracy' condition in usual inequalities, but the 'no-conspiracy' condition is a lot easier to justify in terms of local realism when λ can refer to the state of local variables at some time before the experimenters choose what detector settings to use)

DrChinese

Jun29-10, 04:49 PM

...mainstream physicists aren't going to end up deciding that Bell's theoretical proof is fundamentally flawed and that QM is compatible with a local realist theory that doesn't have any of the kinds of "weird" features that are included as loopholes in rigorous versions of the proof (like many-worlds, or like 'conspiracies' in past conditions that create a correlation between the choice of detector setting and the state of hidden variables at some time earlier than when the choice is made)

True, not likely to change much anytinme soon.

The conspiracy idea (and they go by a lot of names, including No Free Will and Superdeterminism) is not really a theory. More like an idea for a theory. You would need to provide some kind of mechanism, and that would require a deep theoretical framework in order to account for Bell Inequality violations. And again, much of that would be falsifiable. No one actually has one of those on the table. A theory, I mean, and a mechanism.

If you don't like abandoning c, why don't you look at Relational Blockworld? No non-locality, plus you get the added bonus of a degree of time symmetry - no extra worlds to boot! :smile:

DevilsAvocado

Jun29-10, 05:44 PM

... However we won't actually know when case 1 occurs, correct? But unless the chance of 1 is substantially greater than either 2 or 3 individually (and probability logic indicates it should be definitely less - can you see why?), then we can estimate it. If case 4 occurs 50% of the time or more, then 1 should occur less than 10% of the time. This is in essence a vanishing number, since visibility is approaching 90%. That means cases 2 and 3 are happening only about 1 in 10, which would imply case 1 of about 1%.

OMG. I can only hope that < 10% of my brain was 'connected' when asking about this first time... :redface:

OF COURSE we can’t know when case 1 occurs! There are no little "green EPR men" at the source shouting – Hey guys! Here comes entangled pair no. 2345! ARE YOU READY!!

Sorry.

So you have got to claim all of the "missing" photons are carrying the values that would prove a different result. And this number is not much. I guess it is *possible* if there is a physical mechanism which is responsible for the non-detections, but that would also make it experimentally falsifiable. But you should be aware of how far-fetched this really is. In other words, in actual experiments cases 2 and 3 don't occur very often. Which places severe constraints on case 1.

Far-fetched?? To me this looks like something that Crackpot Kracklauer would use as the final disproval of all mainstream science. :smile:

Seriously, an unknown "physical mechanism" working against the reliability of EPR-Bell experiments!:bugeye:? If someone is using this cantankerous argument as a proof against Bell's Theorem, he’s apparently not considering the consequences...

That "physical mechanism" would need some "artificial intelligence" to pull that thru, wouldn’t it?? Some kind of "global memory" working against the fair sampling assumption – Let’s see now, how many photon pairs are detected and how many do we need to mess up, to destroy this silly little experiment?

Unless this "physical mechanism" also can control the behavior of humans (humans can mess up completely on their own as far as we know), it would need some FTL mechanism to verify that what should be measured is really measured = back to square one!

By the way, what’s the name of this interesting "AI paradigm"...?? :biggrin:

P.S. I checked this pretty little statement "QM works because it is not an idealized theoretical proof" against the The Crackpot Index (http://math.ucr.edu/home/baez/crackpot.html) and it scores 10 points!
"10 points for each claim that quantum mechanics is fundamentally misguided (without good evidence)."
Not bad!

billschnieder

Jun29-10, 11:13 PM

But since you bring it up, I think you're just incorrect in saying in post #128 that the Leggett-Garg inequality is not intrinsically based on a large collection of trials where on each trial we measure the same system at 2 of 3 possible times (as opposed to measuring two parts of an entangled system with 1 of several possible combinations detector settings as with other inequalities)

As I mentioned to you earlier, it is your opinion here that is wrong. Of course, the LGI applies to the situation you mention, but inequalities of that form were originally proposed by Boole in 1862 (see http://rstl.royalsocietypublishing.org/content/152/225.full.pdf+html) and had nothing to do with time. All that is necessary for it to apply is n-tuples of two valued (+/-) variables. In Boole's case it was three boolean variables. The inequalities result simply from arithmetic, and nothing else.
We perform an experiment in which each data point consists of triples of data such as (i,j,k). Let us call this set S123. We then decide to analyse this data by extracting three data sets of pairs such as S12, S13, S23. What Boole showed was essentially if i, j,k are two valued variables, no matter the type of experiment generating S123, the datasets of pairs extracted from S123 will satisfy the inequalities:

|<S12> +/- <S13>| <= 1 +/- <S23>

You can verify that this is Bell's inequality (replace 1,2,3 with a,b,c,). Using the same ideas he came up with a lot of different inequalities one of which is the LGI, all from arithmetic. So a violation of these inequalities by data, points to mathematically incorrect treatment of the data.

You may be wondering how this applies to EPR. The EPR case involves performing an experiment in which each point is a pair of two-valued outcomes (i,j), let us call it R12. Bell and followers then assume that they should be able to substitute Sij for Rij in the inequalities forgetting that the inequality holds for pairs extracted from triples, but not necessarily for pairs of two-valued data.

Note that each term in Bell's inequality is a pair from a set of triples (a, b, c), but the data obtained from experiments is a pair from a set of pairs.

I also found the paper where you got the example with patients from different countries here (http://iopscience.iop.org/0295-5075/87/6/60007/fulltext),
That is why I gave you the reference before, have you read it, all of it?

So this critique appears to be rather specific to the Leggett-Garg inequality, maybe you could come up with a variation for other inequalities but it isn't obvious to me (I think the 'noninvasive measurements' condition would be most closely analogous to the 'no-conspiracy' condition in usual inequalities, but the 'no-conspiracy' condition is a lot easier to justify in terms of local realism when λ can refer to the state of local variables at some time before the experimenters choose what detector settings to use)
This is not a valid criticism for the following reason:

1) You do not deny that the LGI is a Bell-type inequality. Why do you think it is called that?
2) You have not convincingly argued why the LGI should not apply to the situation described in the example I presented
3) You do not deny the fact that in the example I presented, the inequalities can be violated simply based on how the data is indexed.
4) You do not deny the fact that in the example, there is no way to ensure the data is correctly indexed unless all relevant parameters are known by the experimenters
5) You do not deny that Bell's inequalities involve pairs from a set of triples (a,b,c) and yet experiments involve triples from a set of pairs.
6) You do not deny that it is impossible to measure triples in any EPR-type experiment, therefore Bell-type inequalities do not apply to those experiments. Boole had shown 100+ years ago that you can not substitute Rij for Sij in those type of inequalities.

nismaratwork

Jun29-10, 11:33 PM

I can see why Dirac disdained this kind of pondering, which in the end has little or nothing to do with the work of physics and its applications in life.

my_wan

Jun30-10, 04:11 AM

I can see why Dirac disdained this kind of pondering, which in the end has little or nothing to do with the work of physics and its applications in life.
There's a real point here. If the motivation in defining a realistic mechanism is simply to sooth a preexisting philosophical disposition, then such debates have nothing to do with anything. However, some big game remains in physics, perhaps even the biggest available. If farther constraints can be established, or constraints that have been overly generalized better defined, it might turn out to be of value.

As DevilsAvocado put it, little "green EPR men" are not a very satisfactory theoretical construct. Realist want to avoid them with realistic constructs, with varying judgment on what constitutes realistic. Non-realist avoid them by denying the realism of the premise. In the end, the final product needs only a formal description with the greatest possible predictive value, independent of our philosophical sensibilities.

ThomasT

Jun30-10, 07:22 AM

I'm glad you're still asking questions, but if you don't really understand the proof, and you do know it's been accepted as valid for years by mainstream physicists, doesn't it make sense to be a little more cautious about making negative claims about it like this one from an earlier post?

I couldn't care less if nonlocality or ftl exist or not. In fact, it would be very exciting if they did. But the evidence just doesn't support that conclusion.I understand the proofs of BIs. What I don't understand is why nonlocality or ftl are seriously considered in connection with BI violations and used by some to be synonymous with quantum entanglement.

The evidence supports Bell's conclusion that the form of Bell's (2) is incompatible with qm and experimental results. But that's not evidence, and certainly not proof, that nature is nonlocal or ftl. (I think that most mainstream scientists would agree that the assumption of nonlocality or ftl is currently unwarranted.) I think that a more reasonable hypothesis is that Bell's (2) is an incorrect model of the experimental situation.

Which you seem to agree with:
It (the form of Bell's 2) shows how the joint probability can be separated into the product of two independent probabilities if you condition on the hidden variables ?. So, P(AB|ab?)=P(A|a?)*P(B|b?) can be understood as an expression of the locality condition. But he obviously ends up proving that this doesn't work as a way of modeling entanglement...it's really only modeling a case where A and B are perfectly correlated (or perfectly anticorrelated, depending on the experiment) whenever a and b are the same, under the assumption that there is a local explanation for this perfect correlation (like the particles being assigned the same hidden variables by the source that created them).

Why doesn't the incompatibility of Bell's (2) with qm and experimental results imply nonlocality or ftl? Stated simply by DA, and which you (and I) agree with:
Bell's(2) is not about entanglement, Bell's(2) is only about the Hidden variable .

JesseM

Jun30-10, 07:42 AM

I understand the proofs of BIs. What I don't understand is why nonlocality or ftl are seriously considered in connection with BI violations and used by some to be synonymous with quantum entanglement.
Yes, you don't understand it, but mainstream physicists are in agreement that Bell's equations all follow directly from local realism plus a few minimal assumptions (like no parallel universes, no 'conspiracies' in past conditions that predetermine what choice the experimenter will make on each trial and tailor the earlier hidden variables to those future choices), so why not consider the probability that the problem likely lies with your understanding rather than that of all those physicists for decades?
The evidence supports Bell's conclusion that the form of Bell's (2) is incompatible with qm and experimental results.
And (2) would necessarily be true in all local realist theories that satisfy those few minimal assumptions. (2) is not in itself a separate assumption, it follows logically from the postulate of local realism.
But that's not evidence, and certainly not proof, that nature is nonlocal or ftl. (I think that most mainstream scientists would agree that the assumption of nonlocality or ftl is currently unwarranted.)
They would agree that it's warranted to rule out local realist theories. Do you disagree with that? Of course this doesn't force you to believe in ftl, you are free to just drop the idea of an objective universe that has a well-defined state even when we're not measuring it (which is basically the option taken by those who prefer the Copenhagen interpretation), or consider the possibility that each measurement splits the experimenter into multiple copies who see different results (many-worlds interpretation), or consider the possibility of some type of backwards causality that can create the kind of "conspiracies" I mentioned.
I think that a more reasonable hypothesis is that Bell's (2) is an incorrect model of the experimental situation.
Local realism is an incorrect model, but (2) is not a separate assumption from local realism, it would be true in any local realist theory.
Why doesn't the incompatibility of Bell's (2) with qm and experimental results imply nonlocality or ftl?
It implies the falsity of local realism, which means if you are a realist who believes in an objective universe independent of our measurements, and you don't believe in any of the "weird" options like parallel worlds or "conspiracies", your only remaining option is nonlocality/ftl.

zonde

Jun30-10, 09:17 AM

As far as I can see, there is currently very high detection efficiencies. From Zeilinger et al:

These can be characterized individually by measured visibilities, which were: for the source, ≈ 99% (98%) in the H/V (45°/135°) basis; for both Alice’s and Bob’s polarization analyzers, ≈ 99%; for the fibre channel and Alice’s analyzer (measured before each run), ≈ 97%, while the free-space link did not observably reduce Bob’s polarization visibility; for the effect of accidental coinci-dences resulting from an inherently low signal-to-noise ratio (SNR), ≈ 91% (including both dark counts and multipair emissions, with 55 dB two-photon attenuation and a 1.5 ns coincidence window).

Violation by 16 SD over 144 kilometers.
http://arxiv.org/abs/0811.3129
What has visibility in common with detection efficiency. :bugeye:
Visibility=(coincidence-max - coincidence-min)/(coincidence-max + coincidence-min)
Efficiency=coincidence rate/singlet rate

zonde

Jun30-10, 09:25 AM

A few papers I came across suggested that experiments which closed both the detector efficiency loophole and the locality loophole simultaneously would likely be possible fairly soon. If someone offered to bet Bill a large sum of money that the results of these experiments would continue to match the predictions of QM (and thus continue to violate Bell inequalities that take into account detector efficiency), would Bill bet against them?
Interesting. And do those papers suggest at least approximately what kind of experiments they will be?
Or is it just very general idea?

Besides if you want to discuss some betting with money you are in the wrong place.

DrChinese

Jun30-10, 09:36 AM

I can see why Dirac disdained this kind of pondering, which in the end has little or nothing to do with the work of physics and its applications in life.

So true. It would be nice if while debating the placement of punctuation and the definition of words in the language we speak daily, we perhaps reminded ourselves of the importance of predictions and related experiments. Because every day, there are fascinating new experiments involving new forms of entanglement. That would be the same "action at a distance" as envisioned in this thread which some think they have "disproven".

And just to prove that, just check out the following link:

As of this morning, this represented 572 articles on the subject - many theoretical but also many experimental - on entanglement and Bell. (http://arxiv.org/find/quant-ph/1/abs:+OR+entanglement+OR+bell+epr/0/1/0/2010/0/1?per_page=100)

Oh, and that would be so far in 2010. Please folks, get a grip. You don't need to take my word for it. Read about 50 or 100 of these papers, and you will see that these issues are being tackled every day by physicists who wake up thinking about this. And you will also see mixed in many interesting alternative ideas which are out of the mainstream: these articles are not all peer reviewed. Look for a Journal Reference to get those, which tend to be mainstream and higher quality overall. Many experimental results will be peer reviewed.

DrChinese

Jun30-10, 10:28 AM

What has visibility in common with detection efficiency. :bugeye:
Visibility=(coincidence-max - coincidence-min)/(coincidence-max + coincidence-min)
Efficiency=coincidence rate/singlet rate

They are often used differently in different contexts. The key is to ask: what pairs am I attempting to collect? Did I collect all of those pairs? Once I collect them, was I able to deliver them to the beam splitter? Of those photons going through the beam splitter, what % were detected? By analyzing carefully, the experimenter can often evaluate these questions. In state of the art Bell tests, these can be important - but not always. Each test is a little different. For example, if fair sampling is assumed then strict evaluation of visibility may not be important. But if you are testing the fair sampling assumption as part of the experiment, it would be an important factor.

Clearly, the % of cases where there is a blip at Alice's station but not Bob's (and vice versa) is a critical piece of information where fair sampling is concerned. If you subtract that from 100%, you get a number. I believe this is what is referred to as visibility by Zeilinger but honestly it is not always clear to me from the literature. Sometimes this may be called detection efficiency. At any rate, there are several distinct issues involved.

Keep in mind that for PDC pairs, the geometric angle of the collection equipment is critical. Ideally, you want to get as many entangled pairs as possible and as few unentangled as possible. If alignment is not correct, you will miss entangled pairs. You may even mix in some unentangled pairs (which will reduce your results from the theoretical max violation of a BI). There is something of a border at which getting more entangled is offset by getting too many more unentangled. So it is a balancing act.

my_wan

Jun30-10, 10:28 AM

I understand the proofs of BIs. What I don't understand is why nonlocality or ftl are seriously considered in connection with BI violations and used by some to be synonymous with quantum entanglement.
In defining the argument, the assumptions and consequences had to be enumerated, regardless of how unlikely one or the other potential consequences might be from some point of view. IF something physical actually traverses that space, in the alloted time, to effect the outcomes as measured, realism is saved. Doesn't matter how reasonable or silly it might be, given the "IF" the fact follows, thus must be included in the range of potentials.

Yes, you don't understand it, but mainstream physicists are in agreement that Bell's equations all follow directly from local realism plus a few minimal assumptions (like no parallel universes, no 'conspiracies' in past conditions that predetermine what choice the experimenter will make on each trial and tailor the earlier hidden variables to those future choices), so why not consider the probability that the problem likely lies with your understanding rather than that of all those physicists for decades?
This is the worst possible argument possible. Almost precisely the same argument my friend, that turned religious, used to try to convert me. It's invalid in any context, no matter how solid the claim it's used to support. I cringe no matter how trivially true such a statement is used to support. So if the majority "don't understand", as you have stated for yourself, acceptance of this argument makes the majority acceptance a self fulfilled prophesy.

And (2) would necessarily be true in all local realist theories that satisfy those few minimal assumptions. (2) is not in itself a separate assumption, it follows logically from the postulate of local realism.
You call it a postulate of local realism, but fail to mention that this "postulate of local realism" is predicated on a very narrowly defined 'operational' definition, which even its originators (EPR) disavowed it, at the time it was proposed, as the only, sufficiently complete, etc., as a complete definition. It was a definition that I personally rejected at a very young age, before I ever heard of EPR or knew what QM was. Solely on classical grounds, but related to some ideas DrC used to reject Hume realism. Now such silly authority arguments, as provided above, is used to make demands that I drop "realism", because somebody generalized an 'operational' definition that I rejected in my youth, and proved it false. Am I supposed to be in awe of that?

It implies the falsity of local realism, which means if you are a realist who believes in an objective universe independent of our measurements, and you don't believe in any of the "weird" options like parallel worlds or "conspiracies", your only remaining option is nonlocality/ftl.
Unequivocally false. There are other options, unless you want to insist that one 'operational' definition is by academic definition the only available definition of realism available. Even then it doesn't make you right, you have only chosen a definition to insure you can't be wrong.

There are whole ranges of issues involved. Many of which may have some philosophical content that don't strictly belong in science, unless of course you can formalize it into something useful. Yet the "realism" claim associated with Bell is a philosophical claim, by taking a formalism geared toward a single 'operational' definition and expanding it over the entire philosophical domain of realism. It's a massive composition fallacy.

The composition fallacy runs even deeper. There's the assumption that the things we measure are existential in the sense of things. Even if every possible measurable we are capable of is provably no more real than a coordinate choice, it is NOT proof that things don't exist independent of being measured (the core assumption of realism). Or that a theoretical construct can't build an empirically consistent emergent system based on existential things. Empirical completeness and the completeness of nature is not synonymous. Fundamentally, realism is predicated on measurement independence, and cannot be proved false on the grounds that an act of measurement has effects. If it didn't have effects, measurements would be magical. Likewise, in a strict realist sense, an existential thing, independent variable, which has independent measurable properties is also a claim of magic.

So please, at least qualify local realism with "Einstein realism", "Bell realism", or some other suitable qualifier, so as not to make the absurd excursion into a blanket philosophical claim that the entire range of all forms of "realism" are provably falsified. It turns science into a philosophical joke, whether right or wrong. If this argument is overly philosophical, sorry, that what the blanket claim that BI violations falsifies local realism imposes.

DrChinese

Jun30-10, 10:32 AM

It turns science into a philosophical joke, whether right or wrong. If this argument is overly philosophical, sorry, that what the blanket claim that BI violations falsifies local realism imposes.

Does it help if we say that BI violations blanket falsify claims of EPR (or Bell) locality and EPR (or Bell) realism? Because if words are to have meaning at all, this is the case.

nismaratwork

Jun30-10, 10:46 AM

So true. It would be nice if while debating the placement of punctuation and the definition of words in the language we speak daily, we perhaps reminded ourselves of the importance of predictions and related experiments. Because every day, there are fascinating new experiments involving new forms of entanglement. That would be the same "action at a distance" as envisioned in this thread which some think they have "disproven".

And just to prove that, just check out the following link:

As of this morning, this represented 572 articles on the subject - many theoretical but also many experimental - on entanglement and Bell. (http://arxiv.org/find/quant-ph/1/abs:+OR+entanglement+OR+bell+epr/0/1/0/2010/0/1?per_page=100)

Oh, and that would be so far in 2010. Please folks, get a grip. You don't need to take my word for it. Read about 50 or 100 of these papers, and you will see that these issues are being tackled every day by physicists who wake up thinking about this. And you will also see mixed in many interesting alternative ideas which are out of the mainstream: these articles are not all peer reviewed. Look for a Journal Reference to get those, which tend to be mainstream and higher quality overall. Many experimental results will be peer reviewed.

I like this approach very much. We should never forget the need for what works, and how it works in the midst of WHY it works.

JesseM

Jun30-10, 12:17 PM

This is the worst possible argument possible. Almost precisely the same argument my friend, that turned religious, used to try to convert me. It's invalid in any context, no matter how solid the claim it's used to support. I cringe no matter how trivially true such a statement is used to support. So if the majority "don't understand", as you have stated for yourself, acceptance of this argument makes the majority acceptance a self fulfilled prophesy.
Huh? I said it was ThomasT who didn't understand Bell's proof, not the majority of physicists. And in technical subjects like science and math, I think it's perfectly valid to say that if some layman doesn't understand the issues very well but is confused about the justification for some statement that virtually all experts endorse, the default position of a layman showing intellectual humility should be that it's more likely the mistake lies with his/her own understanding, rather than taking it as a default that they've probably found a fatal flaw that all the experts have overlooked and proceeding to try to convince others of that. Of course this is just a sociological statement about likelihood that a given layman has actually discovered something groundbreaking, I'm not trying to argue that anyone should take the mainstream position on faith or not bother asking questions about the justification for this position. But if you don't take this advice there's a good chance you'll fall victim to the Dunning-Kruger effect (http://en.wikipedia.org/wiki/Dunning–Kruger_effect), and perhaps also become the type of "bad theoretical physicist" described by Gerard 't Hooft here (http://www.phys.uu.nl/~thooft/theoristbad.html).
You call it a postulate of local realism, but fail to mention that this "postulate of local realism" is predicated on a very narrowly defined 'operational' definition, which even its originators (EPR) disavowed it, at the time it was proposed, as the only, sufficiently complete, etc., as a complete definition.
I define "local realism" to mean that facts about the complete physical state of any region of spacetime can be broken down into a sum of local facts about the state of individual points in spacetime in that region (like the electromagnetic field vector at each point in classical electromagnetism), and that each point can only be causally influenced by other points in its past light cone. Do you think that this is too "narrowly defined" or that EPR would have adopted a broader definition where the above wasn't necessarily true? (if so, can you provide a relevant quote from them?) Or alternatively, do you think that Bell's derivation of the Bell inequalities requires a narrower definition than the one I've just given?
Unequivocally false. There are other options, unless you want to insist that one 'operational' definition is by academic definition the only available definition of realism available. Even then it doesn't make you right, you have only chosen a definition to insure you can't be wrong.
I don't know what you mean by "operational", my definition doesn't appear to be an operational one but rather an objective description of the way the laws of physics might work. If you do think my definition is too narrow and that there are other options, could you give some details on what a broader definition would look like?
There are whole ranges of issues involved. Many of which may have some philosophical content that don't strictly belong in science, unless of course you can formalize it into something useful. Yet the "realism" claim associated with Bell is a philosophical claim, by taking a formalism geared toward a single 'operational' definition and expanding it over the entire philosophical domain of realism. It's a massive composition fallacy.
In a scientific/mathematical field it's only meaningful to use terms like "local realism" if you give them some technical definition which may be different than their colloquial meaning or their meaning in nonscientific fields like philosophy. So if a physicist makes a claim about "local realism" being ruled out, it doesn't really make sense to say the claim is a "fallacy" on the basis of the fact that her technical definition doesn't match how you would interpret the meaning of that phrase colloquially or philosophically or whatever. That'd be a bit like saying "it's wrong to define momentum as mass times velocity, since that definition doesn't work for accepted colloquial phrases like 'we need to get some momentum going on this project if we want to finish it by the deadline'".
The composition fallacy runs even deeper. There's the assumption that the things we measure are existential in the sense of things.
Not sure what you mean. Certainly there's no need to assume, for example, that when you measure different particle's "spins" by seeing which way they are deflected in a Stern-Gerlach device, you are simply measuring a pre-existing property which each particle has before measurement (so each particle was already either spin-up or spin-down on the axis you measure).
Even if every possible measurable we are capable of is provably no more real than a coordinate choice
Don't know what you mean by that either. Any local physical fact can be defined in a way that doesn't depend on a choice of coordinate system, no?
it is NOT proof that things don't exist independent of being measured (the core assumption of realism).
Since I don't know what it would mean for "every possible measurable we are capable of is provably no more real than a coordinate choice" to be true, I also don't know why the truth of this statement would be taken as "proof that things don't exist independent of being measured". Are you claiming that any actual physicists argue along these lines? If so, can you give a reference or link?
Fundamentally, realism is predicated on measurement independence, and cannot be proved false on the grounds that an act of measurement has effects.
I don't see why, nothing about my definition rules out the possibility that the act of measurement might always change the system being measured.
So please, at least qualify local realism with "Einstein realism", "Bell realism", or some other suitable qualifier, so as not to make the absurd excursion into a blanket philosophical claim that the entire range of all forms of "realism" are provably falsified.
All forms compatible with my definition of local realism are incompatible with QM. I don't know if you would have a broader definition of "local realism" than mine, but regardless, see my point about the basic independence of the technical meaning of terms and their colloquial meaning.

JesseM

Jun30-10, 12:27 PM

Interesting. And do those papers suggest at least approximately what kind of experiments they will be?
Or is it just very general idea?
See for example this paper (http://arxiv.org/abs/quant-ph/0701191) and this one (http://arxiv.org/abs/0909.3171)...the discussion seems fairly specific.
Besides if you want to discuss some betting with money you are in the wrong place.
I was just trying to get a sense of whether Bill actually believed himself it was likely that all the confirmation of QM predictions in these experiments would turn out to be a consequence of a local realist theory that was "exploiting" both the detector efficiency loophole and the locality loophole simultaneously, or if he was just scoffing at the fact that experiments haven't closed both loopholes simultaneously for rhetorical purposes (of course there's nothing wrong with pointing out the lack of loophole-free experiments in this sort of discussion, but Bill's triumphant/mocking tone when pointing this out would seem a bit hollow if he didn't actually think such a loophole-exploiting local theory was likely).

my_wan

Jun30-10, 01:14 PM

Does it help if we say that BI violations blanket falsify claims of EPR (or Bell) locality and EPR (or Bell) realism? Because if words are to have meaning at all, this is the case.
That is in fact the case. BI violations do in fact rule out the very form of realism it was predicated on. "EPR local realism" would be fine, as that contains the source of the operational definition Bell did in fact falsify. Some authors already do this, like Adan Cabello spelled it out as "Einstein-Podolsky-Rosen element of reality" (Phys. Rev. A 67, 032107 (2003)). Perfectly acceptable.

As an aside, I really doubt that any given individual element of "physical" reality, assuming such exist and realism holds, corresponds to any physically measurable quantity. This does not a priori preclude a theoretical construct from successfully formalizes such elements. Note how diametrically opposed this is to the operational definition used by EPR:
“If, without in any way disturbing a system, we can predict with certainty (i.e., with probability equal to unity) the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity”

The original EPR paper gave a more general definition of realism that wasn't so contingent on the operational definition:
"every element of physical reality must have a counterpart in physical theory."
Though this almost certainly implicitly assumed some correspondence I consider more than a little suspect, it doesn't a priori assume an element of physical reality has a direct correspondence with observables. Neither do I consider an empirically complete theory incomplete on the grounds that unobservables may be presumed to exist yet not be defined by the theory. That also opposes Einstein's realism. However, certain issues, such as the vacuum catastrophe, GR + QM, dark matter/energy, etc., is a fairly good if presumptuous indicator of incompleteness.

These presumptions, which opposes the EPR definition, began well before I was a teenager or had any clue about EPR or QM, and was predicated on hard realism. Thus I can't make specific claims, I can only state that blanket philosophical claims of what BI violations falsifies is a highly unwarranted composition fallacy, not that the claim is ultimately false.

billschnieder

Jun30-10, 01:50 PM

I was just trying to get a sense of whether Bill actually believed himself it was likely that all the confirmation of QM predictions in these experiments would turn out to be a consequence of a local realist theory that was "exploiting" both the detector efficiency loophole and the locality loophole simultaneously, or if he was just scoffing at the fact that experiments haven't closed both loopholes simultaneously for rhetorical purposes
And as I explained, I do not engage in these discussions for religious purposes, so I'm surprised why you would expect me to bet on. A claim has been made about the non-locality of the universe. I and others, have raised questions about the premises used to supporting that claim. Rather than explain why the premises are true, you expect me rather to bet that the claim is not true. In fact the suggestion is itself maybe suggestive of your approach to these discussions, which I do not consider to be about winning or losing an argument but about understanding the truth of the issues infront of us.

The fact that QM and experiments agree is a big hint that the odd-man out (Bell inequalities) does not model the same thing as QM does, which is what is realized in real experiments. There is no question about this. I think you agree with this. So I'm not sure why you think by repeatedly mentioning the fact that numerous experiments have agreed with QM, it somehow advances your argument. It doesn't. Also the phrase "experimental loopholes" is a misnomer because it gives the false impression that there is something "wrong" with the experiments, such that "better" experiments have to be performed. This is a backward look at it. Every so-called "loophole" is actually a hidden assumption made by Bell in deriving his inequalities.

When I mentioned "assumption" previously, you seemed to express surprise, despite the fact that I have already pointed out to you several times hidden assumptions within Bell's treatment that make it incompatible with Aspect-type experiments. If any one or more of any assumptions in Bell's treatment are not met in the experiments, Bell's inequalities will not apply. The locality assumption is explicit in Bell's treatment, so Bell's proponents think violation of the inequalities definitely means violation of the locality principle. But there are other hidden assumptions such as:

1) Every photon pair will be detected (due to choice of only +/- as possible outcomes)
2) P(lambda) is equivalent for each of the terms of the inequality
3) Datasets of pairs are extracted from a dataset of triples
4) Non-contextuality
5) ...

And the others I have not mentioned or are yet to be discovered. So whenever you hear about "detection efficiency loophole", the issue really is a failure of hidden assumption (1). And the other example I just gave a few posts back about cyclicity and indexing, involves the failure of (2) and (3).

It is therefore not surprising that some groups have reported on locally causal explanations of many of these Bell-test experiments, again confirming that the problem is in the hidden assumptions used by Bell, not in the experimenters.

(of course there's nothing wrong with pointing out the lack of loophole-free experiments in this sort of discussion, but Bill's triumphant/mocking tone when pointing this out would seem a bit hollow if he didn't actually think such a loophole-exploiting local theory was likely).
I make an effort to explain my point of view, you are free to completely demolish it with legitimate arguments. I will continue to point out the flaws I see in your responses (as long as a relevant response can be descerned from them), and if your arguments are legitimate, I will change my point of view accordingly. But if you can not provide a legimate argument and you think the goal of discussion as one of winning/losing, you may be inclined to interprete my conviction about my point of view to be "triumphant/mocking". But that is just your perspective and you are entitled to it, even if it is false.

DrChinese

Jun30-10, 02:05 PM

It is therefore not surprising that some groups have reported on locally causal explanations of many of these Bell-test experiments, again confirming that the problem is in the hidden assumptions used by Bell, not in the experimenters.

When you say "explanations", I wonder exactly what qualifies as an explanation. The only local realistic model I am aware of is the De Raedt et al model, which is a computer simulation which satisfies Bell. All other local explanations I have seen are not realistic or have been generally refuted (e.g. Christian, etc). And again, by realistic, I mean per the Bell definition (simultaneous elements of reality, settings a, b and c).

JesseM

Jun30-10, 02:18 PM

As I mentioned to you earlier, it is your opinion here that is wrong.
Are you saying that Leggett and Garg themselves claimed that their inequality should apply to situations where the three values a,b,c don't represent times of measurement, including the scenario with doctors collecting data on patients from different countries? If so, can you quote from the paper since it doesn't seem to be available freely online? Or are you making some broader claim that the reasoning Leggett and Garg used could just as easily be applied to other scenarios, even if they themselves didn't do this?
Of course, the LGI applies to the situation you mention, but inequalities of that form were originally proposed by Boole in 1862 (see http://rstl.royalsocietypublishing.org/content/152/225.full.pdf+html) and had nothing to do with time. All that is necessary for it to apply is n-tuples of two valued (+/-) variables. In Boole's case it was three boolean variables. The inequalities result simply from arithmetic, and nothing else.
We perform an experiment in which each data point consists of triples of data such as (i,j,k). Let us call this set S123. We then decide to analyse this data by extracting three data sets of pairs such as S12, S13, S23. What Boole showed was essentially if i, j,k are two valued variables, no matter the type of experiment generating S123, the datasets of pairs extracted from S123 will satisfy the inequalities:

|<S12> +/- <S13>| <= 1 +/- <S23>
The paper by Boole you linked to is rather long and he doesn't seem to use the same notation, can you point me to the page number where he derives an equivalent equation so I can see the discussion leading up to it? I would guess he was assuming that we were picking which pairs to extract from each triple in a random way so that there'd be no possibility of a systematic correlation between our choice of which pair to extract and the values of all members of the triplet S123 (and even if Boole neglected to explicitly mention such an assumption I'd assume you could find later texts on probability which did). And this would be equivalent to the assumption Leggett and Garg made of "noninvasive measurement", that the choice of which times to measure a given particle or system aren't correlated with the probability of different hidden classical histories the particle/system might be following. So if you construct an example where we would expect a correlation between what pair of values are sampled and the underlying facts about the value for all three possibilities, then I expect neither Boole nor Leggett and Garg would finding it surprising or contrary to their own proofs that the inequalities would no longer hold.
You can verify that this is Bell's inequality (replace 1,2,3 with a,b,c,).
You mean equation (15) in his original paper (http://www.drchinese.com/David/Bell_Compact.pdf)? But in his derivations the hidden variable λ can represent conditions that occur before the experimenters make a random choice of detector settings (see p. 242 of Speakable and Unspeakable in Quantum Mechanics (http://books.google.com/books?id=FGnnHxh2YtQC&lpg=PA243&ots=3rRcOQrpT3&dq=%22Invoking%20local%20causality%2C%20and%20the% 20assumed%20completeness%22&pg=PA242#v=onepage&q=%22Invoking%20local%20causality,%20and%20the%20a ssumed%20completeness%22&f=false), so there's good justification for saying λ should be independent of detector settings, and in any case this is explicitly includes as the "no-conspiracy condition" in rigorous proofs of Bell's theorem.
So a violation of these inequalities by data, points to mathematically incorrect treatment of the data.
A violation of the inequalities by data which doesn't match the conditions Bell and Leggett-Garg and Boole assumed when deriving them doesn't indicate a flaw in reasoning which says the inequalities should hold if the conditions are met.
I also found the paper where you got the example with patients from different countries here (http://iopscience.iop.org/0295-5075/87/6/60007/fulltext),
That is why I gave you the reference before, have you read it, all of it?
You mentioned the name of the paper but didn't give a link, when I said I "found" it I just meant I had found an online copy. And no, I didn't read it all the way through, just enough sections that I thought I got the idea of how they thought the scenario with patients from different countries was supposed to be relevant to Leggett-Garg. If there is some particular section you think I should pay more attention to, feel free to point to it.
To this critique appears to be rather specific to the Leggett-Garg inequality, maybe you could come up with a variation for other inequalities but it isn't obvious to me (I think the 'noninvasive measurements' condition would be most closely analogous to the 'no-conspiracy' condition in usual inequalities, but the 'no-conspiracy' condition is a lot easier to justify in terms of local realism when λ can refer to the state of local variables at some time before the experimenters choose what detector settings to use)
This is not a valid criticism for the following reason:

1) You do not deny that the LGI is a Bell-type inequality. Why do you think it is called that?
Because the derivation is closely analogous and the conclusion (that QM is incompatible with certain assumptions about 'hidden' objective facts that determine measurement outcomes) is also quite similar. However, the assumptions in the derivation do differ from the assumptions in other Bell-type proofs even if they are very analogous (like the no-conspiracy assumption being replaced by the noninvasive measurement assumption).
2) You have not convincingly argued why the LGI should not apply to the situation described in the example I presented
I don't have access to the original Leggett-Garg paper, but this paper (http://www-thphys.physics.ox.ac.uk/people/ArdLouis/Thesis/appendix.ps) which I linked to before says:
In a paper provocatively entitled "Quantum Mechanics versus Macroscopic Realism: Is the Flux There when Nobody Looks? A. J. Leggett and A. Garg[1] proposed a way to determine whether the magnetic flux of a SQUID (superconducting quantum interference device) was compatible with the postulates:

(A1) Macroscopic Realism: "A macroscopic system with two or more macroscopically distinct states available to it will at all times be in one or the other of these states."

(A2) Noninvasive Measurability: "It is possible, in principle, to determine the state of the system with arbitrary small perturbation on its subsequent dynamics."
So, the quote after (A2) does indicate that they were assuming the condition that the choice of which two measurements to make isn't correlated with the values the system takes at each of the three possible times. An example which is constructed in such a way that there is a correlation between the two sample points and the three values for each data triplet would be one that isn't meeting this condition, and thus there'd be no reason to expect the inequality to hold for it, so it isn't a flaw in the derivation that you can point to such an example.
3) You do not deny the fact that in the example I presented, the inequalities can be violated simply based on how the data is indexed.
Unclear what you mean by "simply based on how the data is indexed". In the example, the Ab in AaAb was taken under consistently different observable experimental conditions than the Ab in AbAc; the first Ab always has a superscript 2 indicating a patient from Lyon, the second Ab always has a superscript 1 indicating a patient from Lille. And they also say:
On even dates we have Aa = +1 and Ac = −1 in both cities while Ab = +1 in Lille and Ab = −1 in Lyon. On odd days all signs are reversed.
So, in this case depending on whether you are looking at the data pair AaAb or AbAc on a given date, the value of Ab is different. And even if you don't know the date information, from an objective point of view (the point of view of an all-knowing omniscient being), this isn't a case where each sample is taken from a "data point" consisting of triplet of objective (hidden) facts about a,b,c, such that the probability distribution on triplets for a sample pair AaAb is the same as the probability distribution on triplets for the other two sample pairs AaAc and AbAc. In the frequentist understanding of probability, this means that in the limit as the number of sample pairs goes to infinity, the frequency at which any given triplet (or any given ordered pair of triplets if the two members of the sample pair are taken from different triplets) is associated with samples of type AaAb should be the same as the frequency at which the same triplet is associated with samples of type AaAc and AbAc. If the "noninvasive measurability" criterion is met in a Leggett-Garg test, this should be true of the measurements at different pairs of times of SQUIDS if local realism is true. Likewise, if the no-conspiracy condition is true in a test of the form Bell discussed in his original paper, this should also be true if local realism is true.
4) You do not deny the fact that in the example, there is no way to ensure the data is correctly indexed unless all relevant parameters are known by the experimenters
I would deny that, at least in the limit as the number of data points becomes very large. In this case they could could just pool all their data, and use a random process (like a coinflip) to decide whether each Aa should be put in a pair with an Ab data point or an Ac data point, and similarly for the other two.
5) You do not deny that Bell's inequalities involve pairs from a set of triples (a,b,c) and yet experiments involve triples from a set of pairs.
I certainly deny this too, in fact I don't know what you can be talking about here. Different inequalities involve different numbers of possible detector settings, but if you look at any particular experiment designed to test a particular inequality, you always find the same number of possible detector settings in the inequality as in the experiment. If you disagree, point me to a particular experiment where you think this wasn't true!
6) You do not deny that it is impossible to measure triples in any EPR-type experiment, therefore Bell-type inequalities do not apply to those experiments.
This one is so obviously silly you really should know better. The Bell-type inequalities are based on the theoretical assumption that on each trial there is a λ which either predetermines a definition outcome for each of the three detector settings (like the 'hidden fruits' that are assumed to be behind each box on my scratch lotto analogy), or at least predetermines a probability for each of the three which is not influenced by what happens to the other particle at the other detector (i.e. P(A|aλ) is not different from P(A|Bbaλ)). If this theoretical assumption were valid, and the probability of different values of λ on each trial did not depend on the detector settings a and b on that trial, then this would be a perfectly valid situation where these inequalities would be predicted to hold. Of course we don't know if these theoretical assumptions actually hold in the real world, but that's the point of testing whether the inequalities hold up in the real world--if they don't, and our experiments meet the necessary observable conditions that were assumed in the derivation, then this constitutes an experimental falsification of one of the predictions of our original theoretical assumptions.
Boole had shown 100+ years ago that you can not substitute Rij for Sij in those type of inequalities.
I don't know what you mean by "Rij".

my_wan

Jun30-10, 03:30 PM

Huh? I said it was ThomasT who didn't understand Bell's proof, not the majority of physicists.
Oops, my apologies.

Wrt the Dunning-Kruger effect I agree. However, if you applied the same standard to the best educated people of the past they would be subject to the same illusory superiority. Though they likely had the skills to overcome it with the right information. So for those who simply insist X is wrong, you have a point. I'm not denying the validity of Bell's theorem in conclusively ruling out a brand of realism. I'm denying the generalization of that proof to all forms of realism.

I have fallen victim to assuming X, which apparently entailed Y, and tried to maintain X by maintaining Y, only to realize X could be maintained without Y. It happens. But in an interesting subject it's not always in our best interest to take an authority at face value. Rather to question it. The denial and accusations that the authority is wrong, silly, etc., without a very solid and convincing argument is just being a crackpot. Yet authoritative sources can also overestimate the generality a given knowledge endows also.

I define "local realism" to mean that facts about the complete physical state of any region of spacetime can be broken down into a sum of local facts about the state of individual points in spacetime in that region (like the electromagnetic field vector at each point in classical electromagnetism), and that each point can only be causally influenced by other points in its past light cone. Do you think that this is too "narrowly defined" or that EPR would have adopted a broader definition where the above wasn't necessarily true? (if so, can you provide a relevant quote from them?) Or alternatively, do you think that Bell's derivation of the Bell inequalities requires a narrower definition than the one I've just given?
Ok, that works. But I got no response on what effects the non-commutativity of vector products, even classical vectors, has on the computational demands of modeling BI violations. If these elements are transfinite, what role might Hilbert's paradox of the Grand Hotel play in such effects? EPR correlations are certainly not unique in requiring relative offset verses absolute coordinate values. SR is predicated on it. If observables are projections from a space with an entirely different metric, which doesn't commute with a linear metric of the space we measure, that could impart computational difficulties which BI doesn't recognize. I didn't get any response involving Maxwell's equations either.

I'm not trying to make the point that Bell was wrong, he was absolutely and unequivocally right, within the context of the definition he used. I'm merely rejecting the over generalization of that definition. Even if no such realistic model exist, by any definition, I still want to investigate all these different principles that might be behind such an effect. The authoritative claim that Bell was right is perfectly valid, to over generalize that into a sea of related unknowns, even by authoritative sources, is unwarranted.

I don't know what you mean by "operational", my definition doesn't appear to be an operational one but rather an objective description of the way the laws of physics might work. If you do think my definition is too narrow and that there are other options, could you give some details on what a broader definition would look like?
Physics is contingent upon operational, not philosophical, claims. What did the original EPR paper say about it?
1) "far from exhausting all possible ways to recognize physical reality"
2) "Regarded not as a necessary, but merely as a sufficient, condition of reality"
3) A comprehensive definition of reality is, however, unnecessary for our purposes"

In other words they chose an definition that had an operational value in making the point more concise, not a definition which defined reality itself.

In a scientific/mathematical field it's only meaningful to use terms like "local realism" if you give them some technical definition which may be different than their colloquial meaning or their meaning in nonscientific fields like philosophy. So if a physicist makes a claim about "local realism" being ruled out, it doesn't really make sense to say the claim is a "fallacy" on the basis of the fact that her technical definition doesn't match how you would interpret the meaning of that phrase colloquially or philosophically or whatever. That'd be a bit like saying "it's wrong to define momentum as mass times velocity, since that definition doesn't work for accepted colloquial phrases like 'we need to get some momentum going on this project if we want to finish it by the deadline'".
True, technical definitions confuse the uninitiated quiet often. Locality is one of them, which is predicated on relativity. Thus it's in principle possible to violate locality without violating realism, as the stated EPR consequences recognizes. Yet if "realism" is technically predicated on the operational definition provided by EPR, why reject out of hand definitions counter to that EPR provided as a source of research? That is factually overstepping the technical bounds on which the "realism" used to reject it is academically defined. That's having your cake and eating it to.

Not sure what you mean. Certainly there's no need to assume, for example, that when you measure different particle's "spins" by seeing which way they are deflected in a Stern-Gerlach device, you are simply measuring a pre-existing property which each particle has before measurement (so each particle was already either spin-up or spin-down on the axis you measure).Unless observable are a linear projection from a space which has a non-linear mapping to our measured space of variables, to name just one. Nor does realism necessarily entail that pre-existing properties that are measurable. It doesn't even entail that independent variables have any independent measurable properties whatsoever.

Don't know what you mean by that either. Any local physical fact can be defined in a way that doesn't depend on a choice of coordinate system, no?
Yes, assuming the variables required are algorithmically compressible or finite. I never got this answer either: what does in mean when you can model a rotation of the beam in an EPR model and maintain BI violations while individual photon paths vary, yet the apparently physical equivalent of uniformly rotating the pair of detectors destroys it? Are they not physically the equivalent transform? Why are physically equivalent transforms not physically equivalent? Perhaps the issue of non-commutative classical vector products needs investigated.

All forms compatible with my definition of local realism are incompatible with QM. I don't know if you would have a broader definition of "local realism" than mine, but regardless, see my point about the basic independence of the technical meaning of terms and their colloquial meaning.
If that is your definition of local realism, fine. But you can't make claims that your definition precludes alternatives, or that alternatives are precluded by your definition. You want a broader "technical" definition of realism? It's not mine, it came from exactly the same source as yours did. "An element of reality that exist independent of any measurement". That's it. Whatever more you add, its relationship with what is measured or measurable, are presumptions that go beyond the general definition. So I would say that the very original source, on which you derive your claim of a "technical" definition, disavows that particular definition as sufficiently general to constitute a general technical definition. Even without being explicitly aware of the issues it now presents.

JesseM

Jun30-10, 03:51 PM

And as I explained, I do not engage in these discussions for religious purposes, so I'm surprised why you would expect me to bet on.
A nonreligious person can have intuitions and opinions about the likelihood of various possibilities, like the likelihood that improved gravitational wave detectors will in the near future show that general relativity's predictions about gravitational waves are false. If someone doesn't think this is very likely, I would think it a bit absurd for them to gloat about the lack of experimental confirmation of gravitational waves in an advocate with someone taking the mainstream view that general relativity is likely to be accurate at classical scales.
I and others, have raised questions about the premises used to supporting that claim. Rather than explain why the premises are true, you expect me rather to bet that the claim is not true.
As you no doubt remember I gave extended arguments and detailed questions intended to show why your claims that Bell's theorem is theoretically flawed or untestable don't make sense, but you failed to respond to most of my questions and arguments and then abruptly shut down the discussion, in multiple cases (As with my posts here (http://www.physicsforums.com/showpost.php?p=2706689&postcount=68) and here (http://www.physicsforums.com/showpost.php?p=2711170&postcount=78) where I pointed out that your argument about the failure of the 'principle of common cause' ignored the specific types of conditions where it failed as outlined in the Stanford Encyclopedia article you were using as a reference, and I asked you to directly address my argument about past light cones in a local realist universe without relying on nonapplicable statements from the encyclopedia article. Your response here (http://www.physicsforums.com/showpost.php?p=2711285&postcount=82) was to ignore all the specific quotes I gave you about the nature of the required conditions and declare that you'd decided we'd have to 'agree to disagree' on the matter rather than discuss it further...if you ever change your mind and decide to actually address the light cone argument in a thoughtful way, you might start by saying whether you disagree with anything in post #63 here (http://www.physicsforums.com/showthread.php?t=406372)).

Of course the point that Bell inequalities might not actually be violated with loophole-free tests is totally separate from the idea that the proof itself is flawed or that perfect tests are impossible in the first place unless we know the values of all hidden variables and can control for them (the arguments you were making earlier). Unlike with those earlier arguments I don't actually disagree with your basic point that they might not be violated with loophole free tests so there's no need for me to try to argue with you about that, I was just using the idea of betting to point to the absurdity of your gloating attitude about the lack of loophole-free tests. I think this gloating rather typifies your "lawyerly" approach to the subject, where you are trying to cast doubt on Bell using rhetorical strategies rather than examine the issues in a detailed and thoughtful manner.
The fact that QM and experiments agree is a big hint that the odd-man out (Bell inequalities) does not model the same thing as QM does, which is what is realized in real experiments.
Uh, the whole point of the Bell inequalities is to prove that the assumed conditions they are modeling (local realism) are incompatible with QM! Do you really not understand this after all this time, or is this just another example of "it sounds good rhetorically, who cares if it's really a plausible argument?"
So I'm not sure why you think by repeatedly mentioning the fact that numerous experiments have agreed with QM, it somehow advances your argument. It doesn't.
My "argument" is that Bell has a valid proof that local realism and QM are incompatible, and thus that experimental verification of QM predictions about Bell inequality violations also constitute experimental falsification of local realism. Do you really not understand the very basic logic of deriving certain predictions from theoretical assumptions, showing the predictions don't match reality, and therefore considering that this is experimental evidence that the theory doesn't describe the real world? This is just how any theory of physics would be falsified experimentally!
Also the phrase "experimental loopholes" is a misnomer because it gives the false impression that there is something "wrong" with the experiments, such that "better" experiments have to be performed. This is a backward look at it. Every so-called "loophole" is actually a hidden assumption made by Bell in deriving his inequalities.
The loopholes are just based on actual experiments not meeting the observable experimental conditions Bell was assuming would hold in the theoretical experiments that the inequalities are supposed to apply to, like the idea that there should be a spacelike separation between measurements (if an actual experiment doesn't conform to this, it falls prey to the locality loophole). None of them are based on whether the theoretical assumptions about the laws of physics used in the derivation (like the assumption that the universe follows local realist laws) are true or false.

To put it another way, Bell proved that (specified observable experimental conditions, like spacelike separation between measurements) + (theoretical assumptions about laws of physics, like local realism) = (Bell inequalities). So, if a real experiment matches all the observable experimental conditions but does not give results which satisfy the Bell inequalities, that's a good experimental falsification of the theoretical assumptions about the laws of physics that Bell made. On the other hand, if an experiment doesn't match all those observable conditions, then even if it violates Bell inequalities there may still be some remaining possibility that the theoretical assumptions actually do apply in our universe (so our universe might still obey local realist laws)
When I mentioned "assumption" previously, you seemed to express surprise, despite the fact that I have already pointed out to you several times hidden assumptions within Bell's treatment that make it incompatible with Aspect-type experiments.
And I've pointed out that some of the "hidden assumptions" you claimed were needed, like controlling for all the hidden variables, were not necessary. In this post (http://www.physicsforums.com/showthread.php?p=2767008#post2767008) you even seemed to be starting to get the point when you asked:
Is it your claim that Bell's "population" is defined in terms of "an infinite set of repetitions of the exact observable experimental conditions you were using"? If that is what you mean here then I fail to see the need to make any fair sampling assumption at all.
To which I responded in post #126 (http://www.physicsforums.com/showpost.php?p=2770199&postcount=126) on that thread:
In the part in bold I think I made clear that Bell's proof would only apply to the exact observable experimental conditions you were using if it was true that those conditions met the "basic criteria" I mentioned above. I allowed for the possibility that 100% detector efficiency might be one of the conditions needed--DrChinese's subsequent posts seem to say that the original Bell inequalities do require this assumption, although perhaps you can derive other inequalities if the efficiency lies within some known bounds, and he seemed to say that local realist theories which tried to make use of this loophole would need some other physically implausible features. As I said above in my response to #110 though, I would rather keep the issue of the detector efficiency loophole separate from your other critiques of Bell's reasoning, which would seem to apply even if we had an experiment that closed all these known loopholes (and apparently there was one experiment with perfect detector efficiency but it was vulnerable to a separate known loophole).
But of course that didn't go anywhere because you didn't respond to this, and ended up arguing that frequentist definitions of probability were so inherently horrible that you refused to adopt them even for the sake of argument, even if they were the type of probability likely being assumed by Bell in his proof.
If any one or more of any assumptions in Bell's treatment are not met in the experiments, Bell's inequalities will not apply. The locality assumption is explicit in Bell's treatment, so Bell's proponents think violation of the inequalities definitely means violation of the locality principle. But there are other hidden assumptions such as:

1) Every photon pair will be detected (due to choice of only +/- as possible outcomes)
This is an observable experimental condition (at least it's observable whether every detection at one detector is part of a coincidence with a detection at the other, and it shouldn't be possible to come up with a local hidden variables model where the hidden variables influence the chance of nondetection in such a way that if one photon isn't detected the other's guaranteed not to be either despite the random choice of detector settings, and have this lead to a Bell inequality violation).
2) P(lambda) is equivalent for each of the terms of the inequality
This is the no-conspiracy assumption, and given that lambda can represent local facts at a time before the experimenters make a choice of which detector setting to use (with the choice made using any random or pseudorandom method they like), it's not hard to see why a theory that violated this would have some very implausible features.
3) Datasets of pairs are extracted from a dataset of triples
As I said in my previous post:
The Bell-type inequalities are based on the theoretical assumption that on each trial there is a λ which either predetermines a definition outcome for each of the three detector settings (like the 'hidden fruits' that are assumed to be behind each box on my scratch lotto analogy), or at least predetermines a probability for each of the three which is not influenced by what happens to the other particle at the other detector (i.e. P(A|aλ) is not different from P(A|Bbaλ)). If this theoretical assumption were valid, and the probability of different values of λ on each trial did not depend on the detector settings a and b on that trial, then this would be a perfectly valid situation where these inequalities would be predicted to hold.
So, this just reduces to the assumption of local realism plus the no-conspiracy assumption, it's not an independent assumption.
4) Non-contextuality
As I argued in this post (http://www.physicsforums.com/showthread.php?p=2702947#post2702947), I think you're incorrect that this is necessary for Bell's proof:
In a local realist theory there is an objective truth about which variables are associated with a given point in spacetime (and the values of those variables). This would include any variables associated with the region of spacetime occupied by the moon, and any associated with the region of spacetime occupied by a human. The variables associated with some humans might correspond to a state that we could label "observing the moon", and the variables associated with other humans might correspond to a state we could label "not observing the moon", but the variables themselves are all assumed to have an objective state that does not depend on whether anyone knows about them.

A "contextual" hidden variables theory is one where knowledge of H is not sufficient to predetermine what results the particle will give for any possible measurement of a quantum-mechanical variable like position or momentum, the conditions at the moment of measurement (like the exact state of the measuring device at the time of measurement) can also influence the outcome--see p. 39 here on google books (http://books.google.com/books?id=BPj4DrsG9gQC&lpg=PP1&pg=PA39#v=onepage&q&f=false), for example. This doesn't mean that all fundamental variables (hidden or not) associated with individual points in spacetime don't have definite values at all times, it just means that knowing all variables associated with points in the past light cone of the measurement at some time t does not uniquely determine the values of variables in the region of spacetime where the measurement is made (which tell you the outcome of the measurement).
If we assume that the particles always give the same results (or opposite results) when the same detector settings are used, then we can derive from other assumptions already mentioned that this implies the results for each possible setting must be predetermined (making it a contextual theory), I can explain if you like. But Bell derived inequalities which don't depend on this assumption of predetermined results for each setting, see p. 12 of this paper (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) where he writes:
It was only in the context of perfect correlation (or anticorrelation) that determinism could be inferred for the relation of observation results to pre-existing particle properties (for any indeterminism would have spoiled the correlation). Despite my insistence that the determinism was inferred rather than assumed, you might still suspect somehow that it is a preoccupation with determinism that creates the problem. Note well then that the following argument makes no mention whatever of determinism.
5) ...

And the others I have not mentioned or are yet to be discovered. So whenever you hear about "detection efficiency loophole", the issue really is a failure of hidden assumption (1). And the other example I just gave a few posts back about cyclicity and indexing, involves the failure of (2) and (3).
As I point out above, there aren't really that many independent theoretical assumptions, and any theoretical assumptions beyond local realism would require some very weird conditions (like parallel universes, or 'conspiracies' in past conditions that predetermine what choice the experimenter will make on each trial and tailor the earlier hidden variables to those future choices) in order to be violated.
I make an effort to explain my point of view, you are free to completely demolish it with legitimate arguments. I will continue to point out the flaws I see in your responses (as long as a relevant response can be descerned from them)
Ah, so as long as you deem it not "relevant" you are free not to address my central arguments, like not explaining what flaws you saw in my reading of the specific quotes from the Stanford Encyclopedia of Philosophy article on the principle of common cause (since your entire refutation to my past light cone argument ended up revolving around quotes from that article), or not even considering whether the probabilistic statements Bell makes might make sense when interpreted in frequentist terms with the correct understanding of the "population" of experiments (with the 'population' being one defined solely in terms of observable experimental conditions with no attempt to 'control for' the value of hidden variables, so that by the law of large numbers any real experiment matching those conditions should converge on the ideal probabilities in a large number of trials if the basic theoretical assumptions like local realism were valid). Both of these were central to my counterarguments to two of your main anti-Bell arguments, the first being that Bell's equation (2) was not legitimately derivable from the assumption of local realism, the second being that it would be impossible in principle to test whether Bell's theoretical assumptions held in the real world without knowing the value of all hidden variables in each experiment and controlling for them. But since you decided these counterarguments weren't "relevant" you simply didn't give them any substantive response.
But if you can not provide a legimate argument and you think the goal of discussion as one of winning/losing, you may be inclined to interprete my conviction about my point of view to be "triumphant/mocking". But that is just your perspective and you are entitled to it, even if it is false.
I'll leave it to others to decide whether quotes like the following have a tone of "triumphant" dismissal or whether they simply express an attitude of caution about whether there is a slight possibility the universe obeys local realist laws that exploit both detection loopholes simultaneously:
Now that this blatant error is clear, let us look at real experiments to see which approach is more reasonable, by looking at what proportion of photons leaving the source is actually detected.

For all Bell-test experiments performed to date, only 5-30% of the photons emitted by the detector have been detected, with only one exception. And this exception, which I'm sure DrC and JesseM will remind us of, had other more serious problems. Let us make sure we are clear what this means.

It means of almost all those experiments usually thrown around as proof of non-locality, P(case4) has been at most 30% and even as low as 30% in some cases. The question then is, where did the whopping 70% go?

Therefore it is clear first of all by common sense, then by probability theory, and finally confirmed by numerous experiments that non-detection IS an issue and should have been included in the derivation of the inequalities!
(from post #930--part in bold sounds a bit 'mocking' to me, and note that the claim of 'only one exception' was posted after my post #152 on the 'Understanding Bell's Logic' thread where I told you that other experiments closing the detection loophole had been done)
Therefore correlations observed in real experiments in which non-detection matters can not be compared to idealized theoretical proofs in which non-detection was not considered since those idealized theoretical proofs made assumptions that will never be fulfilled in any real experiments.
(from post #932--a blanket dismissal of the relevance of all 'real experiments', no nuance whatsoever)
What has this got to do with anything. If there was a convincing experiment which fulfilled all the assumptions in Bell's derivation, I would change my mind. I am after the truth, I don't religiously follow one side just because I have invested my whole life to it.
(from #936--sounds rather mocking again, or was there no implication here that others like myself or DrChinese are religiously following one side because we've invested our lives in it?)
Don't know about that precise inequality, but as I mentioned in an earlier post:
DId I hear ONE with a but attached?
(from post #151 on 'Understanding Bell's Logic'--again, sounds completely dismissive, no actual interest in what the experiment might tell us about the likelihood of a loophole-exploiting hidden variables theory)

ThomasT

Jun30-10, 11:46 PM

DrChinese

Jul1-10, 12:02 PM

As you're well aware, there are many physicists quite familiar with Bell's work who don't agree with your statement of the choices entailed by violations of BIs.

You're saying that the "statement that virtually all experts endorse" is the dichotomy that nature is either nonlocal (taking, in keeping with the theme of this thread, the term 'nonlocality' to mean 'action-at-a-distance') or that there is no nature independent of observations. I'm saying that I think that virtually all experts would view that as a false dichotomy. This would seem to require some sort of poll.

JesseM indicated correctly. I don't know of a physicist in the field (other than a small group like Santos, Hess, Philipp, etc.) that does NOT agree with JesseM's assessment. Certainly you won't find any mention of dissent on this point in a textbook on the subject. I have given repeated references to roundups on the subject, including yesterday, which makes this clear. In light of JesseM's statement to you, he is politely asking you to quit acting as if your minority view is more widely accepted than it is. It confuses readers like JenniT and others.

You may consider it a "false dichotomy"; but as Maaneli is fond of pointing out, you don't have to take it as a dichotomy at all! You can take it as ONE thing as a whole too: local causality is rejected. That is a complete rejection of your position regardless.

A wise person would have no issue with being a bit more humble. You can express yourself without acting like you know it all. I appreciate that after reviewing the case for Bell/Bell tests, you reject the work of thousands of physicists because of your gut feel on the matter. But that is not something to brag about.

JesseM

Jul1-10, 12:51 PM

I define "local realism" to mean that facts about the complete physical state of any region of spacetime can be broken down into a sum of local facts about the state of individual points in spacetime in that region (like the electromagnetic field vector at each point in classical electromagnetism), and that each point can only be causally influenced by other points in its past light cone. Do you think that this is too "narrowly defined" or that EPR would have adopted a broader definition where the above wasn't necessarily true? (if so, can you provide a relevant quote from them?) Or alternatively, do you think that Bell's derivation of the Bell inequalities requires a narrower definition than the one I've just given?
Ok, that works. But I got no response on what effects the non-commutativity of vector products, even classical vectors, has on the computational demands of modeling BI violations. If these elements are transfinite, what role might Hilbert's paradox of the Grand Hotel play in such effects?
But Bell's proof is abstract and mathematical, it doesn't depend on whether it is possible to simulate a given hidden variables theory computationally, so why does it matter what the "computational demands of modeling BI violations" are? I also don't understand your point about a transfinite set of hidden variables and Hilbert's Hotel paradox...do you think there is some specific step in the proof that depends on whether lambda stands for a finite or transfinite number of facts, or that would be called into question if we assumed it was transfinite?
EPR correlations are certainly not unique in requiring relative offset verses absolute coordinate values. SR is predicated on it. If observables are projections from a space with an entirely different metric, which doesn't commute with a linear metric of the space we measure, that could impart computational difficulties which BI doesn't recognize.
I'm not sure what you mean by "projections from a space"...my definition of local realism above was defined in terms of points in our observable spacetime, if an event A outside the past light cone of event B can nevertheless have a causal effect on B then the theory is not local realist theory in our spacetime according to my definition, even if the values of variables at A and B are actually "projections" from a different unseen space where A is in the past light cone of B (is that something like what you meant?)
I didn't get any response involving Maxwell's equations either.
Response to which question?
Physics is contingent upon operational, not philosophical, claims. What did the original EPR paper say about it?
1) "far from exhausting all possible ways to recognize physical reality"
2) "Regarded not as a necessary, but merely as a sufficient, condition of reality"
3) A comprehensive definition of reality is, however, unnecessary for our purposes"

In other words they chose an definition that had an operational value in making the point more concise, not a definition which defined reality itself.
They did make the claim that there should in certain circumstances be multiple elements of reality corresponding to different possible measurements even when it is not operationally possible to measure them all simultaneously, didn't they?
True, technical definitions confuse the uninitiated quiet often. Locality is one of them, which is predicated on relativity. Thus it's in principle possible to violate locality without violating realism, as the stated EPR consequences recognizes.
Sure, Bohmian mechanics would usually be taken as an example of this.
Yet if "realism" is technically predicated on the operational definition provided by EPR, why reject out of hand definitions counter to that EPR provided as a source of research?
I don't follow, what "definitions counter to that EPR provided" are being rejected out of hand?
Not sure what you mean. Certainly there's no need to assume, for example, that when you measure different particle's "spins" by seeing which way they are deflected in a Stern-Gerlach device, you are simply measuring a pre-existing property which each particle has before measurement (so each particle was already either spin-up or spin-down on the axis you measure).
Unless observable are a linear projection from a space which has a non-linear mapping to our measured space of variables, to name just one.
What's the statement of mine you're saying "unless" to? I said "there's no need to assume ... you are simply measuring a pre-existing property which each particle has before measurement", not that this was an assumption I made. Did you misunderstand the structure of that sentence, or are you actually saying that if "observable are a linear projection from a space which has a non-linear mapping to our measured space of variables", then that would mean my statement is wrong and that there is a need to assume we are measuring pre-existing properties the particle has before measurement?
Don't know what you mean by that either. Any local physical fact can be defined in a way that doesn't depend on a choice of coordinate system, no?
Yes, assuming the variables required are algorithmically compressible or finite.
Why would infinite or non-compressible physical facts be exceptions to that? Note that when I said "can be defined" I just meant that a coordinate-independent description would be theoretically possible, not that this description would involve a finite set of characters that could be written down in practice by a human. For example, there might be some local variable that could take any real number between 0 and 1 as a value, all I meant was that the value (known by God, say) wouldn't depend on a choice of coordinate system.
I never got this answer either: what does in mean when you can model a rotation of the beam in an EPR model and maintain BI violations while individual photon paths vary, yet the apparently physical equivalent of uniformly rotating the pair of detectors destroys it? Are they not physically the equivalent transform?
As you rotate the direction of the beams, are you also rotating the positions of the detectors so that they always lie in the path of the beams and have the same relative angle between their orientation and the beam? If so this doesn't really seem physically equivalent to rotating the detectors, since their the relative angle between the detector orientation and the beam would change.
If that is your definition of local realism, fine. But you can't make claims that your definition precludes alternatives, or that alternatives are precluded by your definition. You want a broader "technical" definition of realism? It's not mine, it came from exactly the same source as yours did. "An element of reality that exist independent of any measurement". That's it.
But that's just realism, it doesn't cover locality (Bohmian mechanics would match that notion of realism for example). I think adding locality forces you to conclude that each basic element of reality is associated with a single point in spacetime, and is causally affected only by things in its own past light cone.

JesseM

Jul1-10, 01:21 PM

It (the nonviability of Bell's 2) implies the falsity of local realism, which means if you are a realist who believes in an objective universe independent of our measurements, and you don't believe in any of the "weird" options like parallel worlds or "conspiracies", your only remaining option is nonlocality/ftl.
I think this is a false dichotomy which is recognized as such by mainstream physicists. Otherwise, why wouldn't all physicists familiar with Bell's work believe that nature is nonlocal (the alternative being that nature simply doesn't exist independent of our measurements)?
Many physicists have a basically positivist (http://en.wikipedia.org/wiki/Positivism) attitude and don't think it's worth talking about questions that aren't experimentally testable (which by definition includes any questions about what's going on with quantum systems when we aren't measuring them). As I noted though, even if you do want to take a "realist" attitude towards QM, there are a few other "weird" options which allow you to avoid FTL, like the many-worlds interpretation (which is actually very popular among physicists who have opinions about the 'interpretation' of QM), or possibly some form of backwards causality which allows for violations of the no-conspiracy assumption (because the later choice of detector settings can have a backwards influence on the probability the source emits particles with different values of hidden variables). So most realist physicists would probably consider it an open question whether nature takes one of these other "weird" options as opposed to the "weird" option of FTL/nonlocal influences between particles. Either way, I think virtually every mainstream physicist would agree the non-"weird" option of local realism is incompatible with QM theoretically, and can be pretty safely ruled out based on experiments done so far even if none has been completely perfect.
You've said that Bell's(2) isn't about entanglement. Then how can it's falsification be telling us anything about the nature of entanglement (such as that entangled disturbances are communicating nonlocally)?
Because it's about constraints on the statistics in experiments which meet certain experimental conditions, given the theoretical assumption of local realism--since QM's predictions about entanglement say that these statistical constraints will be violated in experiments meeting those same specified experimental conditions, that shows that QM and local realism are incompatible with one another.
And, if it isn't a correct model of the underlying reality, which is one way of looking at it, then how can it's falsification be telling us that an underlying reality doesn't exist?
Because it's a general model of any possible theory that would qualify as "local realist" as physicists understand the term, which I take as basically equivalent to the definition I gave my_wan:
I define "local realism" to mean that facts about the complete physical state of any region of spacetime can be broken down into a sum of local facts about the state of individual points in spacetime in that region (like the electromagnetic field vector at each point in classical electromagnetism), and that each point can only be causally influenced by other points in its past light cone.
So, a falsification of the predictions of this general model constitutes a falsification of "local realism" as in my definition above.
As you're well aware, there are many physicists quite familiar with Bell's work who don't agree with your statement of the choices entailed by violations of BIs.
"Many" who aren't regarded as crackpots by the mainstream community? (i.e. not someone like Kracklauer who would fit 't Hooft's description of a bad theoretical physicist (http://www.phys.uu.nl/~thooft/theoristbad.html) very well) If so, can you give some examples? DrChinese, who's a lot more familiar with the literature on this subject than I, said:
I don't know of a physicist in the field (other than a small group like Santos, Hess, Philipp, etc.) that does NOT agree with JesseM's assessment. Certainly you won't find any mention of dissent on this point in a textbook on the subject. I have given repeated references to roundups on the subject, including yesterday, which makes this clear.
If, as has been suggested, a majority of physicists think that nature is nonlocal
I don't necessarily think a majority would endorse that positive conclusion, for the reasons I gave above. But virtually everyone would agree local realism can be ruled out, aside from a few "weird" variants like the ones I mentioned involving violations of various conditions that appear in rigorous versions of Bell's argument (like the no-conspiracy condition).
I respectfully have to reject your assessment of the meaning of Bell's(2)
You "reject" it without being willing to engage with my specific arguments as to why it's implied by local realism, like the one about past light cones in post #63 here (http://www.physicsforums.com/showthread.php?t=406372) which I've directed you to a few times, and also without being willing to answer my detailed questions about your claims to have an alternative model involving polarization vectors. This doesn't sound like the attitude of an open-minded inquirer into truth, but rather someone with an axe to grind against Bell based on gut feelings that there must be some flaw in the argument even if you can't quite pinpoint what it is.
and violations of BIs based on it, and your assessment of the mainstream view on this. My guess is that most physicists familiar enough with BIs to make an informed assessment of their physical meaning do not think that their violation implies either that nature is nonlocal or that there's no reality independent of measurements.
As I said, there are other options besides "nature is nonlocal" or "no reality independent of measurements", including both the popular many-worlds interpretation and the even more popular positivist attitude of not caring about any questions that don't concern measurements (or at least not thinking them subjects for science).
You're saying that the "statement that virtually all experts endorse" is the dichotomy that nature is either nonlocal (taking, in keeping with the theme of this thread, the term 'nonlocality' to mean 'action-at-a-distance') or that there is no nature independent of observations.
No, I had already mentioned other "weird" options like parallel universes or violations of the no-conspiracy condition in previous posts to you.
Local realism refers to the assumption that there is an objective (though unknown) reality underlying instrumental behavior, and that it's evolving in accordance with the principle of local causality. EPR's elements of reality, as defined wrt the specific experimental situation they were considering, represent a special case and subset of local realism.
Your definition of "local realism" seems to match the one I gave to my_wan, and Bell's proof is broad enough to cover all possible theories that would be local realist in this sense.
There are models of entanglement which are, ostensibly, local, but not realistic, or realistic, but not local, or, both local and realistic, which reproduce the qm predictions.
There are no "models of entanglement which are ... both local and realistic, which reproduce the qm predictions", at least not ones which match the other conditions in Bell's proof like each measurement having a unique outcome (no parallel universes) and no "conspiracies" creating correlations between random choice of detector settings and prior values of hidden variables (and again, his equation (2) is not an independent condition, it follows logically from the other conditions). If you disagree, please point to one!

billschnieder

Jul1-10, 05:28 PM

Are you saying that Leggett and Garg themselves claimed that their inequality should apply to situations where the three values a,b,c don't represent times of measurement, including the scenario with doctors collecting data on patients from different countries?
Your changing argument against this counter-example, has been mostly dismissive

First you tried to suggest that the inequality I provided was not the same as the one of Leggett and Garg, when a simple check of the LG original article should have revealed it right there. Then you tried suggesting that the inequality does not apply to the counter example I presented, pointing to an appendix of an unpublished thesis (and we are not even sure if the guy passed) as evidence to support your claim.

All along, you make no effort to actually understand what I am telling you. And this is the pattern with your responses. As soon as you see a word in an opposing post, you immediately think you know what the point is and you reproduce your pre-canned recipes of counter-arguments without making an effort to understand the specific opposing argument being made. And your recent diatribe about a previous discussion on PCC shows the same, combined with selective memory of those discussions which are in the open for anyone to read. The following analogy summarizes your approach.

Person1: " 1 apple + 1 orange is not equivalent to 2 pears"
JesseM: "1 + 1 = 2, I can prove it ... <insert 5 pages of extensive text and proofs> ... Do you disagree?"
Person1: "Your response is irrelevant to the issue"
JesseM: "Are you going to answer my question or not?
Person1: <ignores JesseM>
JesseM: <50 posts and 10 threads later> "The fact that you refused to respond to my question in post <##> shows that you are only interested in rhetoric"

Now back to the subject of LGI, I have repeatedly told you it doesn't matter what a,b,c are, any inequalities of that mathematical form will be violated if the data being compared to the inequalities are not correctly indexed to maintain the cyclicity. I have very clearly explained this numerous times. Don't you realise it is irrelevant to my argument to then try to prove to me that Leggett and Garg used ONLY time to derive their inequalities? Just because LG used time to arrive at their inequalities does not mean correctly indexing the data is not required. I have given you a reference to an article by Boole more than century ago in which he derived similar inequalities using just boolean algebra without any regard to time, yet you complain that the article is too long and you don't like Boole's notation. The language may be dated but the notation quite clear, if you actually read the text to find out what the symbols mean. Well, here is a simplified derivation using familiar symbols so that there can be no escape from the fact that such inequalities can be derived from a purely mathematical basis:

Define a boolean variable v such that v = 0,1 and \overline{v} = 1 - v
Now consider three such boolean variables x, y, z which can occur together in any experiment

It therefore follows that:
1 = \overline{xyz}+x\overline{yz}+x\overline{y}z+\over line{x}y\overline{z}+xy\overline{z}+\overline{xy}z +\overline{x}yz + xyz

We can then group the terms as follows so that each group in parentheses can be reduced to products of only two variables.

1 = \overline{xyz}+(x\overline{yz}+x\overline{y}z)+(\o verline{x}y\overline{z}+xy\overline{z})+(\overline {xy}z+\overline{x}yz) + xyz

Performing the reduction, we obtain:
1 = \overline{xyz}+(x\overline{y})+(y\overline{z})+(\o verline{x}z) + xyz

Which can be rearranged as:
x\overline{y}+y\overline{z}+\overline{x}z = 1 - (\overline{xyz} + xyz)

But since the last two terms on the RHS are either 0 or 1, you can write the following inequality:
x\overline{y}+y\overline{z}+\overline{x}z \leq 1

This is Boole's inequality and you can find similar ones on pages 230 and 231 of Boole's article.
In Bell-type situations, we are interested not in boolean variables of possible values (0,1) but in variables with values (+1, -1) so we can define three such variables a, b, c wheret a = 2x - 1 , b = 2y - 1 and c = 2z -1

Remembering that \overline{x} = 1 - x, and substituting in the above inequality maintaining on the LHS only terms involving products of pairs, you obtain the following inequality

-ab - ac - bc \leq 1

from which you can obtain the following inequality by replacing a with -a.

ab + ac - bc \leq 1

These two inequalities can be combined into the form

|ab + ac| \leq 1 + bc

Which is essentially Bell's inequality. If you doubt this result, you can try doing the math yourself and confirm that this is valid. Note that we have derived this from simply by assuming that we have three dichotomous variables occurring together from which we extract products of pairs, using simple algebra without any assumptions about time, locality, non-invasiveness, past light-cones or even hidden variables etc. Therefore their violation by data does not mean anything other than a mathematical problem with the way the data is treated. The counter-example I presented shows this very clearly, that is why when you keep focusing on "time", or "non-invasiveness", thinking that it addresses the issue, I do not take you seriously. So try and understand the opposing argument before you attempt countering it.

billschnieder

Jul1-10, 05:38 PM

A violation of the inequalities by data which doesn't match the conditions Bell and Leggett-Garg and Boole assumed when deriving them doesn't indicate a flaw in reasoning which says the inequalities should hold if the conditions are met.

Here again you are arguing that 1 + 1 = 2. Completely ignoring the point, which simply stated is this:
"Violation of the inequalities derived by using a series of assumptions (Ai, i=1,2,3,...,n) by data, means ONLY that one or more of the assumptions (Ai, i=1,2,3,...,n) is false!"
If A1 = "Locality", and you conclude that violation of the inequality implies non-locality, you are being intellectually dishonest, because you know very well that failure of any of the other assumptions can lead to violations even if the locality assumption is true. This is the whole point of the discussion! Again, if you were actually trying to understand my argument, you would have realized this a while ago.
If you insist that the inequalities were derived precisely to describe the Aspect-type experimental situation, as you have sometimes claimed previously, then I will argue that the inequalities are flawed because for the numerous reasons presented here and well recognized in the mainstream, no single experiment has yet satisfied all the assumptions inherent in their derivation. However, if you insist that the inequalities only apply to some ideal experiments which fulfill those assumptions, as I have mentioned many times previously and I doubt anyone here believes otherwise, then those idealized inequalities, however perfect they are, can not be compared to real experiments unless there is independent justification of correspondence between the data from these experiments and the terms within the inequalities. So in case you want to continue to provide proof that 1 + 1 = 2, read this paragraph again and make sure you understand the point.

... from an objective point of view (the point of view of an all-knowing omniscient being)
Again, you are trying to argue that 1 + 1 = 2. How many times will I tell you that experiments are not performed by omniscient observers before it will sink in? You can imagine all you want about an omniscient being, but your imagination will not be comparable to a real experiment by real experimenters.

In the frequentist understanding of probability, this means that in the limit as the number of sample pairs goes to infinity, the frequency at which any given triplet (or any given ordered pair of triplets if the two members of the sample pair are taken from different triplets) is associated with samples of type AaAb should be the same as the frequency at which the same triplet is associated with samples of type AaAc and AbAc,
...
this isn't a case where each sample is taken from a "data point" consisting of triplet of objective (hidden) facts about a,b,c, such that the probability distribution on triplets for a sample pair AaAb is the same as the probability distribution on triplets for the other two sample pairs AaAc and AbAc. In the frequentist understanding of probability, this means that in the limit as the number of sample pairs goes to infinity, the frequency at which any given triplet (or any given ordered pair of triplets if the two members of the sample pair are taken from different triplets) is associated with samples of type AaAb should be the same as the frequency at which the same triplet is associated with samples of type AaAc and AbAc. If the "noninvasive measurability" criterion is met in a Leggett-Garg test, this should be true of the measurements at different pairs of times of SQUIDS if local realism is true. Likewise, if the no-conspiracy condition is true in a test of the form Bell discussed in his original paper, this should also be true if local realism is true.
Are you making a point by this? You just seem to be rehashing here, exactly what is already mentioned in the paper, the fact that to a non-omniscient being without knowledge of all the factors in play, A1a is not different from Aa, which is precisely why the inequality is violated. So it is unclear what your point is.

4) You do not deny the fact that in the example, there is no way to ensure the data is correctly indexed unless all relevant parameters are known by the experimenters

I would deny that, at least in the limit as the number of data points becomes very large. In this case they could could just pool all their data, and use a random process (like a coinflip) to decide whether each Aa should be put in a pair with an Ab data point or an Ac data point, and similarly for the other two.
This is why I asked you to read the paper in full, because you do not know what you are talking about here. The experimenters did not suspect that the location of the test was an important factor so their data was not indexed for location. That means, they do not have anything data point such as A1a(n). All they have is Aa(n). So I'm not sure what you mean by the underlined text. Also note that they are calculating averages of all their data, so I'm not sure why you would think randomly selecting them will make a difference.

Imagine having a bit-mapped image, and you want to extract pixels from it, randomly. For each pixel you you record down a dataset of triples of properties (x position, y position, and color). From the final dataset of triples, you can reconstruct the image. Now instead of collecting one dataset of triples, you collect two datasets of pairs (x, y) and (y, color), what you are suggesting here is similar to the idea that you can still generate the image by randomly deciding which pair from the first dataset, should be matched with a pair from the second data set!

5) You do not deny that Bell's inequalities involve pairs from a set of triples (a,b,c) and yet experiments involve triples from a set of pairs.
I certainly deny this too, in fact I don't know what you can be talking about here.

In Bell's treatment the terms a, b, c represent a triple of angles for which it is assumed that a specific particle, will have values for specific hidden elements of reality. The general idea which DrC and yourself have mentioned several times, usually goes like this "the particle has a specific polarization/spin for those different settings which exists before any measurement is made" and you have often called this "the realism assumption". So according to Bell, for each pair of particles under consideration, at least in the context of Bell's inequalities, there are three properties corresponding to (a,b,c). From these, Bell derives the inequality of the form
1 + E(b,c) >= |E(a,b) - E(a,c)|
Clearly, each term in the inequality involves a pair extracted from the triple (a,b,c). You could say the inequality involves a triple of pairs extracted from an ideal dataset of triples. In an actual experiment, we have ONLY two stations, so we can only have two settings at a time. Experimenters then collect a dataset which involves just pairs of settings. Therefore, to generate terms for the above inequalities from the data, the triple of pairs will have to be extracted from a dataset of pairs. Bell proponents think it is legitimate to substitute pairs extracted from a dataset of triples with pairs extracted from a dataset of pairs. (Compare with the image analogy above)

1) You do not deny that it is impossible to measure triples in any EPR-type experiment, therefore Bell-type inequalities do not apply to those experiments.
This one is so obviously silly you really should know better. The Bell-type inequalities are based on the theoretical assumption that on each trial there is a λ which either predetermines a definition outcome for each of the three detector settings (like the 'hidden fruits' that are assumed to be behind each box on my scratch lotto analogy) ...
Another example of answering without understanding the point you are arguing against. First, I have already pointed out to you that you can not compare an idealized theoretical construct with an actual experiment unless you can demonstrate that the terms in your idealized theoretical construct, correspond to elements in the experiment. Secondly, I have explained why the fact that Aspect-type experiments only produce pairs of data points is a problem for anyone trying to compare those experiments with Bell inequalities. So, rather than throwing insults, if you know of an experiment in which a specific pair of entangled particles are measured at three different angles (a,b,c), then point it out.

I don't know what you mean by "Rij".
Try to derive the inequalities I derived above using the three variables but for which only two can occur together in any experiment. It can not be done. This demonstrates conclusively that you can not substitute a triplet of pairs extracted from a dataset of pairs, into an inequality involving a triplet of pairs extracted from a dataset of triples. (see the image analogy above)

DrChinese

Jul1-10, 06:07 PM

In Bell's treatment the terms a, b, c represent a triple of angles for which it is assumed that a specific particle, will have values for specific hidden elements of reality. The general idea which DrC and yourself have mentioned several times, usually goes like this "the particle has a specific polarization/spin for those different settings which exists before any measurement is made" and you have often called this "the realism assumption". So according to Bell, for each pair of particles under consideration, at least in the context of Bell's inequalities, there are three properties corresponding to (a,b,c). From these, Bell derives the inequality of the form

1 + E(b,c) >= |E(a,b) - E(a,c)|

Clearly, each term in the inequality involves a pair extracted from the triple (a,b,c). You could say the inequality involves a triple of pairs extracted from an ideal dataset of triples. In an actual experiment, we have ONLY two stations, so we can only have two settings at a time. Experimenters then collect a dataset which involves just pairs of settings. Therefore, to generate terms for the above inequalities from the data, the triple of pairs will have to be extracted from a dataset of pairs. Bell proponents think it is legitimate to substitute pairs extracted from a dataset of triples with pairs extracted from a dataset of pairs. (Compare with the image analogy above)

Yes, I think that is a fair assessment of some of the key ideas of Bell. I think it is well understood that there are some sampling issues but that for the most part, they change little. Again, I realize you think sampling is a big "loophole" but few others do.

The fact that doesn't change, no matter how you cut it, is the one item I keep bringing up: It is not possible to derive a dataset for ONE sample of particles that provides consistency with QM statistics. In other words, forget entangled pairs... that is merely a device to test the underlying core issue. Once you accept that no such dataset is possible, which I know you do, then really the entire local realistic house of cards comes down. I know you don't accept that conclusion, but that is it for most everyone else.

billschnieder

Jul1-10, 07:54 PM

The fact that doesn't change, no matter how you cut it, is the one item I keep bringing up: It is not possible to derive a dataset for ONE sample of particles that provides consistency with QM statistics. In other words, forget entangled pairs... that is merely a device to test the underlying core issue. Once you accept that no such dataset is possible, which I know you do, then really the entire local realistic house of cards comes down. I know you don't accept that conclusion, but that is it for most everyone else.

The QM statistics are predicting precisely the outcome of those experiments, the experiments agree with QM, so the data from those experiments is already a dataset which agrees with QM, what more do you want. You will have to define precisely the experiment you want us to produce a dataset for and also provide the QM prediction for the specific experiment you describe. Asking that we produce a dataset from one type of experiment (which can never actually be performed), which matches the predictions QM gives for another type of experiment, will not be serious.

zonde

Jul2-10, 03:03 AM

They are often used differently in different contexts. The key is to ask: what pairs am I attempting to collect? Did I collect all of those pairs? Once I collect them, was I able to deliver them to the beam splitter? Of those photons going through the beam splitter, what % were detected? By analyzing carefully, the experimenter can often evaluate these questions. In state of the art Bell tests, these can be important - but not always. Each test is a little different. For example, if fair sampling is assumed then strict evaluation of visibility may not be important. But if you are testing the fair sampling assumption as part of the experiment, it would be an important factor.
Wrong. You are confusing visibility with detection efficiency.
Visibility is roughly speaking signal/noise ratio. If visibility is too low then you don't violate Bell inequalities (or CHSH) even assuming fair sampling.
So visibility is always important.

Clearly, the % of cases where there is a blip at Alice's station but not Bob's (and vice versa) is a critical piece of information where fair sampling is concerned. If you subtract that from 100%, you get a number. I believe this is what is referred to as visibility by Zeilinger but honestly it is not always clear to me from the literature. Sometimes this may be called detection efficiency. At any rate, there are several distinct issues involved.
You might confuse (correlation) visibility with detection efficiency but there is absolutely no reason to assume that authors of the paper have such confusion.

Keep in mind that for PDC pairs, the geometric angle of the collection equipment is critical. Ideally, you want to get as many entangled pairs as possible and as few unentangled as possible. If alignment is not correct, you will miss entangled pairs. You may even mix in some unentangled pairs (which will reduce your results from the theoretical max violation of a BI). There is something of a border at which getting more entangled is offset by getting too many more unentangled. So it is a balancing act.
This concerns visibility. But to have high coincidence rate we should have high coupling efficiency and for that we should look at coupled photons versus uncoupled (single) photons (as opposed to entangled versus unentangled pairs).
If we observe high coincidence rate in result we certainly have high detection efficiency and high coupling efficiency. But of course we can have high detection efficiency but low coupling efficiency because of poor configuration of source and in that case there is no use from high detection efficiency because coincidence rate will be low anyways.

zonde

Jul2-10, 03:28 AM

See for example this paper (http://arxiv.org/abs/quant-ph/0701191) and this one (http://arxiv.org/abs/0909.3171)...the discussion seems fairly specific.
Well you see the problem here is that authors of these papers assume that detector efficiency is the only obstacle toward eliminating detection loophole.
But if you look at actual experiments the picture seems a bit different. There does not seem to be any improvement in coincidence detection rate for full setup when you use detectors with high efficiency. Coincidence detection rate is still around 10% for experiments with high coincidence visibility.
The crucial part in this is another peace of equipment that is used in experiments. There are frequency interference filters between PBS and detectors. If you remove them you increase coincidence detection rate but reduce visibility for measurements in +45°/-45° base.
And there are no suggestions how you could get rid of them (or move to another place) while preserving high visibility.

So there does not seem to be clear road toward loophole free experiments.
And my position is that there won't be such experiments in a year or ten years or ever.

DrChinese

Jul2-10, 04:12 PM

1. Well you see the problem here is that authors of these papers assume that detector efficiency is the only obstacle toward eliminating detection loophole.
But if you look at actual experiments the picture seems a bit different. There does not seem to be any improvement in coincidence detection rate for full setup when you use detectors with high efficiency. Coincidence detection rate is still around 10% for experiments with high coincidence visibility.

2. So there does not seem to be clear road toward loophole free experiments.
And my position is that there won't be such experiments in a year or ten years or ever.

1. I don't necessarily doubt the 10% figure, I just can't locate a reference that clearly states this. And I have looked. The number I am trying to find is:

Alice where there is a matching Bob / Total Alice
(and same for Bob)

To me, that leads to what I think of as visibility. That is probably not the right label, but I have had a difficult time getting a clear picture of how this is calculated and presented.

2. Although the so-called "loophole-free" experiments are scientifically desirable, their absence is not even close to meaning much at all. You are welcome to wait for that, for virtually everyone else the existing evidence is overwhelming. Local realism has failed every single test devised to date (when compared to QM). And that is quite a few.

JesseM

Jul2-10, 04:24 PM

But if you look at actual experiments the picture seems a bit different. There does not seem to be any improvement in coincidence detection rate for full setup when you use detectors with high efficiency. Coincidence detection rate is still around 10% for experiments with high coincidence visibility.
This may be true if you're talking about experiments with pairs of entangled photons, but other types of entanglement experiments have been performed where the detection efficiency was close to 100%, although these experiments are vulnerable to the locality loophole. See here (http://deepblue.lib.umich.edu/bitstream/2027.42/62731/1/409791a0.pdf) and here (http://prl.aps.org/abstract/PRL/v100/i15/e150404) for example. If you look at the papers proposing loophole-free experiments that I gave you links to earlier, the proposals are also ones that don't involve photon pairs but rather other types of entangled systems.

ThomasT

Jul3-10, 12:23 PM

Certainly you won't find any mention of dissent on this point in a textbook on the subject.The textbook that I learned qm from didn't say anything about nature being nonlocal.

In light of JesseM's statement to you, he is politely asking you to quit acting as if your minority view is more widely accepted than it is.My view is that Bell doesn't require me to assume that nature is nonlocal, which JesseM seems to indicate might well be the majority view:

I don't necessarily think a majority would endorse that positive conclusion (that nature is nonlocal).

It confuses readers like JenniT and others.I don't think that my simplistic, feeble minded observations, questions or assertions (note the intellectual humility) could possibly confuse anyone -- and certainly not JenniT. Your stuff, on the other hand, is either very deep or very confused. Either way I still have the utmost respect for your and JesseM's , and anyone else's for that matter, attempts to enlighten me wrt Bell-related stuff. If my 'know it all' style is sometimes annoying, then at least that part of my program is successful. Just kidding. Try to block that out and only focus on what I'm saying, or what you think I'm trying to say. The bottom line is that I really don't feel that I fully understand it. Am I alone in this? I don't think so. Anyway, we have these wonderful few threads here at PF actively dealing with Bell's stuff, and for the moment I'm in a sort of philosophy/physics Hillbilly Heaven of considerations of Bell's theorem. Not that the stuff in the thread(s) is (necessarily) all that profound, and not that I would know anyway (more intellectual humility), but that it's motivating me (and I'll bet others too) to research this in ways that I (and they) probably wouldn't take the time to do otherwise (without these threads).

You may consider it a "false dichotomy"; but as Maaneli is fond of pointing out, you don't have to take it as a dichotomy at all! You can take it as ONE thing as a whole too: local causality is rejected. That is a complete rejection of your position regardless.Ok, it's not a dichotomy. Then the nonlocality of nature is the inescapable conclusion following Bell. So why isn't this the general paradigm of physics? Why isn't this taught in physics classes? Why, as JesseM says he thinks, and as I would agree with, don't a majority of physicists endorse the conclusion that nature is nonlocal? Why bother with any 'mediating' physics at all if Bell has shown this to be impossible?

A wise person would have no issue with being a bit more humble.But I am humble. See above. And wise. See below.

You can express yourself without acting like you know it all. I appreciate that after reviewing the case for Bell/Bell tests, you reject the work of thousands of physicists because of your gut feel on the matter. But that is not something to brag about.I have the gut feeling that you might be exaggerating. Am I wrong? (Would 'hundreds of physicists' be a closer estimate? Or, maybe, 87?)

By the way DrC (and others), I'm going to be out blowing stuff up with various explosives and lighting things on fire with various lenses in commemoration of our independence or whatever. Plus lots of hotdogs with jalapenos, cheese and mustard -- and beer! HAPPY 4TH OF JULY!

ThomasT

Jul3-10, 12:40 PM

I define "local realism" to mean that facts about the complete physical state of any region of spacetime can be broken down into a sum of local facts about the state of individual points in spacetime in that region (like the electromagnetic field vector at each point in classical electromagnetism), and that each point can only be causally influenced by other points in its past light cone.

Local realism refers to the assumption that there is an objective (though unknown) reality underlying instrumental behavior, and that it's evolving in accordance with the principle of local causality. EPR's elements of reality, as defined wrt the specific experimental situation they were considering, represent a special case and subset of local realism.

Your definition of "local realism" seems to match the one I gave to my_wan, and Bell's proof is broad enough to cover all possible theories that would be local realist in this sense.That's the question: is Bell's proof broad enough to cover all possible LR theories?

Certainly, I agree with you, and understand why, Bell's theorem, as developed by Bell, disallows any and all LHV or LR theories that conform to Bell's explicit formulation of such theories. That is, such models, conforming to the explicit requirements of Bell, must necessarily be incompatible with qm (and, as has been demonstrated, with experiments). The ONLY question about this, afaik, concerns the generality of Bell's LHV or LR model. In connection with this consideration, LR models of entanglement have been proposed which do reproduce the qm predictions.

There are no "models of entanglement which are ... both local and realistic, which reproduce the qm predictions", at least not ones which match the other conditions in Bell's proof like each measurement having a unique outcome (no parallel universes) and no "conspiracies" creating correlations between random choice of detector settings and prior values of hidden variables (and again, his equation (2) is not an independent condition, it follows logically from the other conditions). If you disagree, please point to one!Ok. Here's one, posted in another (Bell) thread by Qubix, which I've taken some time to try to understand. I think it's conceptually equivalent to what I've been saying about the joint experimental context measuring something different than the individual experimental context.

Disproofs of Bell, GHZ, and Hardy Type Theorems and the Illusion of Entanglement
http://uk.arxiv.org/abs/0904.4259

No one has responded to it (in the thread "Bell's mathematical error") except DrC:

Christian's work has been rejected. But that is not likely to stop him. He fails test #1 with me: his model is not realistic.We're waiting for DrC to clarify his 'realism' requirement -- truly a puzzlement in its own right.

Yes, Christian's work (on this) has been 'rejected'. However, the supposed rebuttals have themselves been rebutted. As it stands now, there has been little or no interest in Christian's work, afaik, on Bell's theorem for about 3 years. Much like Bell's first (famous) paper in the 3 years following it's publication.

The abstract:
An elementary topological error in Bell's representation of the EPR elements of reality is identified. Once recognized, it leads to a topologically correct local-realistic framework that provides exact, deterministic, and local underpinning of at least the Bell, GHZ-3, GHZ-4, and Hardy states. The correlations exhibited by these states are shown to be exactly the classical correlations among the points of a 3 or 7-sphere, both of which are closed under multiplication, and hence preserve the locality condition of Bell. The alleged non-localities of these states are thus shown to result from misidentified topologies of the EPR elements of reality. When topologies are correctly identified, local-realistic completion of any arbitrary entangled state is always guaranteed in our framework. This vindicates EPR, and entails that quantum entanglement is best understood as an illusion.

And an excerpt from the Introduction:
Hence Bell’s postulate of equation (1) amounts to an implicit assumption of a specific topology for the EPR elements of reality. In what follows, we shall be concerned mainly with the topologies of the spheres S0, S1, S2, S3, and S7, each of which is a set of binary numbers parameterized by Eq. (3), but with very different topologies from one another. Thus, for example, the 1-sphere, S1, is connected and parallelizable, but not simply connected. The spheres S3 and S7, on the other hand, are not only connected and parallelizable, but also simply connected. The crucial point here is that—since the topological properties of different spheres are dramatically different from one another—mistaking the points of one of them for the points of another is a serious error. But that is precisely what Bell has done.

Hopefully, someone is going to actually read Christian's paper and make some knowledgeable comments wrt it's contentions -- rather than simply say that it's been rejected. Afaik, Christian's paper is unrefuted and generally unrecognized.

DrChinese

Jul3-10, 03:48 PM

1. The textbook that I learned qm from didn't say anything about nature being nonlocal.

My view is that Bell doesn't require me to assume that nature is nonlocal, which JesseM seems to indicate might well be the majority view:

2. But I am humble. See above. And wise. See below.

3. By the way DrC (and others), I'm going to be out blowing stuff up with various explosives and lighting things on fire with various lenses in commemoration of our independence or whatever. Plus lots of hotdogs with jalapenos, cheese and mustard -- and beer! HAPPY 4TH OF JULY!

1. There is a big difference in this and what I said. You aren't going to find textbooks promoting local realism, and you know it.

Whether nature is nonlocal or not is not what I am asserting. As I have said till I'm blue, nature might be nonrealistic. Or both. So you are being a bit misleading when you comment as you have.

A NOTE FOR EVERYONE: nonlocal could mean a lot of things. The Bohmian crew has one idea. Nonrealistic could mean a lot of things too. MWIers have an idea about this. But nonlocal could mean other things too - like that wave functions can be nonlocal, or that there are particles that travel FTL. So defining nonlocality still has a speculative element to it. I happen to subscribe to the kind of nonlocality that is consistent with the HUP. So if you think the HUP implies some kind of nonlocality, well, there's the definition. And that makes HUP believers into believers of a kind of nonlocality. I call that quantum nonlocality. And I think that is a fairly widespread belief, although I have nothing specific to back that up.

2. Perhaps your humility is one of your best traits. I know it is one of mine!

3. Have fun. And save a beer for me.

DrChinese

Jul3-10, 03:58 PM

1. We're waiting for DrC to clarify his 'realism' requirement -- truly a puzzlement in its own right.

I can see why it is hard to understand.

a) Fill any a set of hidden variables for angle settings 0, 120 and 240 degrees for a group of hypothetical entangled photons.
b) This should be accompanied by a formula that allows me to deduce whether the photons are H> or V> polarized, based on the values of the HVs.
c) The results should reasonably match the predictions of QM, a 25% coincidence rate, regardless of which 2 different settings I might choose to select. I will make my selections randomly, before I look at your HVs but after you have established their values and the formula.

When Christian shows me this, I'll read more. Not before, as I am quite busy: I must wash my hair tonight.

ThomasT

Jul3-10, 05:33 PM

Whether nature is nonlocal or not is not what I am asserting. As I have said till I'm blue, nature might be nonrealistic. Or both. So you are being a bit misleading when you comment as you have.If nature is nonrealistic, then it must necessarily be true that quantum correlations are nonlocal. So, as far as I can tell, that's what you're saying, ie., that Bell entails that there is no nature ... nothing ... underlying instrumental phenomena. But how could you, or Bell, or anybody, possibly know that? From a theorem? Maybe you've made a mistake somewhere in your thinking about this!

ThomasT

Jul3-10, 05:38 PM

I can see why it is hard to understand.

a) Fill any a set of hidden variables for angle settings 0, 120 and 240 degrees for a group of hypothetical entangled photons.
b) This should be accompanied by a formula that allows me to deduce whether the photons are H> or V> polarized, based on the values of the HVs.
c) The results should reasonably match the predictions of QM, a 25% coincidence rate, regardless of which 2 different settings I might choose to select. I will make my selections randomly, before I look at your HVs but after you have established their values and the formula.

When Christian shows me this, I'll read more. Not before, as I am quite busy: I must wash my hair tonight.Your 'realism' requirement remains a mystery. Christian's paper is there for you to critique. I don't think you understand it.

DevilsAvocado

Jul3-10, 05:43 PM

... I'm not trying to make the point that Bell was wrong, he was absolutely and unequivocally right, within the context of the definition he used. I'm merely rejecting the over generalization of that definition. Even if no such realistic model exist, by any definition, I still want to investigate all these different principles that might be behind such an effect. The authoritative claim that Bell was right is perfectly valid, to over generalize that into a sea of related unknowns, even by authoritative sources, is unwarranted.

my_wan, could we make a parallel to the situation when Albert Einstein, over a hundred years ago, started to work on his theory of relativity? (Note, I'm not saying that you are Einstein! :smile:)

Einstein did not reject the work of Isaac Newton. In most ordinary circumstances, Newton's law of universal gravitation is perfectly valid, and Einstein knew that. The theory of relativity is 'merely' an 'extension' to extreme situations, where we need finer 'instrumentation'.

Beside this fact; Einstein also provided a mechanism for gravity, which thus far had been a paradox, without any hope for a 'logical' explanation. As Newton put it in a letter to Bentley in 1692:

"That one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one another, is to me so great an absurdity that, I believe, no man who has in philosophic matters a competent faculty of thinking could ever fall into it."

If we look at the situation today, there are a lot of ('funny' "action at a distance") similarities. QM & SR/GR works perfectly fine side by side, in most 'ordinary' circumstances. It's only in very rare situations that we see clear signs of something that looks like an undisputable contradiction between Quantum mechanics and Relativity.

John Bell did absolutely not dispute the work of the grandfathers of QM & SR/GR - he was much too intelligent for that. It's only cranky "scientists" like Crackpot Kracklauer who, without hesitating, dismisses QM & SR/GR as a "foundation" for their "next paradigm" in physics.

Now, if we continue the parallel; it's easy to see that IF Einstein would have had the same "mentality" as Crackpot Kracklauer and billschnieder - he would NOT have been successful in formulating the theory of relativity.

A real crackpot would have started his work, in the beginning of the 1900-th century, by stating:

It's not plausible (I can feel it in my gut!), to imagine bodies affecting each other thru vacuum at a distance! Therefore I shall prove that the mathematical genius Isaac Newton made a terrible mistake when he used a comma instead of a vertical bar, and consequently, Newton's law of universal gravitation is all false. Gravity does not exist. Period.

I shall also prove that there are no experiments proving the existence of Newton's law that has closed all loopholes simultaneously, and there never will be.

I don't know about you, but to me - this is all pathetic. It's clear that billschnieder, with Crackpot Kracklauer as the main source of inspiration, are undoubtedly arguing along these cranky lines above. And to some extent, so does ThomasT, even if he has changed attitude lately.

So I agree, Bell's Theorem can very well be the sign for the "Next Einstein" to start working on an 'extension' to QM & SR/GR, that would make them 100% compatible, and besides this, also provide a mechanism for what we see in current theories and thousands of performed experiments.

This "Next Einstein" must without any doubts include ALL THE WORK OF THE GRANDFATHERS, since in all history of science THIS HAS ALWAYS BEEN THE CASE.

Looking for commas and vertical bars is a hilarious permanent dead-end.

my_wan

Jul3-10, 07:08 PM

my_wan, could we make a parallel to the situation when Albert Einstein, over a hundred years ago, started to work on his theory of relativity? (Note, I'm not saying that you are Einstein! :smile:)

Einstein did not reject the work of Isaac Newton. In most ordinary circumstances, Newton's law of universal gravitation is perfectly valid, and Einstein knew that. The theory of relativity is 'merely' an 'extension' to extreme situations, where we need finer 'instrumentation'.

I have not provided any well defined mechanisms to equate in such a way. Certainly any such future models can't simply reject the standard model on the grounds of some claim of ontological 'truth'. That is raw crackpottery, even if they are right in some sense. There's a term for that: "not even wrong".

The notion that a particular ontological notion of realism, predicated on equating properties with localized things (localized not meant in a FTL sense here), can be generalized over the entire class called realism simply exceeds what the falsification of that one definition, with it's ontological predicates, justifies.

The individual issues I attempted to discuss were considered incomprehensible when viewed from an ontological perspective they weren't predicated on. Well duh, no kidding. I only hoped to get some criticism on the points, irrespective of what it entailed in terms of realism, to help articulates such issues more clearly. But so long as responses are predicated on some singular ontological notion of realism, as if it fully defined "realism", the validity of BI within that ontological context insures the discussion will go nowhere. I'll continue to investigate such issues myself.

My core point, the overgeneralization of BI local realism to all realism classes, remains valid. Being convinced of the general case by a proof of a limited case is, at a fundamental level, tantamount to proof by lack of evidence. It is therefore invalid, but might not be wrong. I certainly haven't demonstrated otherwise.

DevilsAvocado

Jul4-10, 05:58 PM

I have not provided any well defined mechanisms to equate in such a way. Certainly any such future models can't simply reject the standard model on the grounds of some claim of ontological 'truth'. That is raw crackpottery, even if they are right in some sense. There's a term for that: "not even wrong".

I agree, I agree very much. I think your 'agenda' is interesting and healthy. billschnieder on the other hand... well, those words are not allowed here... :grumpy:

DevilsAvocado

Jul4-10, 07:48 PM

JesseM, regarding intellectual humility, don't ever doubt that I'm very thankful that there are educated people like you and DrC willing to get into the details, and explain your current thinking to feeble minded laypersons, such as myself, who are interested in and fascinated by various physics conundrums.

Welcome to club ThomasT! I'm glad that you have finally stepped down from the "sophisticated" throne and become an open-minded "wonderer" as many others in this thread, with respect for professionals with much greater knowledge. :wink:

You've said that Bell's(2) isn't about entanglement.

No, JesseM didn't say that - I made that laymanish simplification. JesseM wanted more details:

Basically I'd agree, although I'd make it a little more detailed: (2) isn't about entanglement, it's about the probabilities for different combinations of A and B (like A=spin-up and B=spin down) for different combinations of detector settings a and b (like a=60 degrees, b=120 degrees), under the assumption that there is a perfect correlation between A and B when both sides use the same detector setting, and that this perfect correlation is to be explained in a local realist way by making use of hidden variable λ.

The key is: Bell's (2) is about perfect correlation, explained in a local realist way, using the Hidden variable λ.

I understand the proofs of BIs. What I don't understand is why nonlocality or ftl are seriously considered in connection with BI violations and used by some to be synonymous with quantum entanglement.

The evidence supports Bell's conclusion that the form of Bell's (2) is incompatible with qm and experimental results. But that's not evidence, and certainly not proof, that nature is nonlocal or ftl. (I think that most mainstream scientists would agree that the assumption of nonlocality or ftl is currently unwarranted.) I think that a more reasonable hypothesis is that Bell's (2) is an incorrect model of the experimental situation.

...

Why doesn't the incompatibility of Bell's (2) with qm and experimental results imply nonlocality or ftl? Stated simply by DA, and which you (and I) agree with:

ThomasT, I see you and billschnieder spend hundreds of posts in trying to disprove Bell's (2) with various farfetched arguments, believing that if Bell's (2) can be proven wrong – then Bell's Theorem and all other work done by Bell will go down the drain, including nonlocality.

I'm only a layman, but I think this is terrible wrong, and I think I can prove it to you in a very simple way.

But first, let's start from the beginning – to be sure that we are indeed talking about the same matters:

After a long debate between Albert Einstein and Niels Bohr, about the uncertain nature of QM, Einstein finally formulated the EPR paradox in 1935 (together with Boris Podolsky and Nathan Rosen).

The aim of the EPR paradox was to show that there was a preexisting reality at the microscopic QM level - that the QM particles indeed had a real value before any measurements were performed (thus disproving Heisenberg uncertainty principle HUP).

To make the EPR paper extremely short; If we know the momentum of a particle, then by measuring the position on a twin particle, we would know both momentum & position for a single QM particle - which according to HUP is impossible information, and thus Einstein had proven QM to be incomplete ("God does not play dice").

Okay? Do you agree?

Einstein & Bohr could never solve this dispute between them as long as they lived (which bothered Bohr throughout his whole life). And as far as I understand, Einstein in his last years, became more at 'unease' with the signs of nonlocality, than the original question of the uncertain nature of QM.

Thirty years after the publication of the EPR paradox, John Bell entered the scene. To my understanding, Bell was hoping that Einstein was right, but as the real scientist as he was, he didn't hesitate to publish what he had found – even if this knowledge was a contradiction to his own 'personal taste'.

In the original paper from 1964, Bell formulates in Bell's (2) the mathematical probabilities representing the vital assumptions made by Einstein in 1949, on the EPR paradox:

"But on one supposition we should, in my opinion, absolutely hold fast: the real factual situation of system S2 is independent of what is done with system S1, which is spatially separated from the former."

In Bell's (3) he makes an equal QM expectation value, and then he states, in third line after Bell's (2):

"BUT IT WILL BE SHOWN THAT THIS IS NOT POSSIBLE"

(my caps+bold)

Do you understand why we get upset when you and billschnieder argue the way you do? You are urging PF users to read cranky papers - while you & billschnieder obviously hasn’t read, or understand, the original Bell paper that this is all about??

Do you really think that John Bell was incapable of formulating the probabilities for getting spin up/down from a local preexisting hidden variable? Or, the odds of getting a red/blue card out of a box? If applying Bell's (2) on the "card trick" we would get 0.25, according to billschnieder, instead of 0.5!? The same man who undoubtedly discovered something that both geniuses Albert Einstein and Niels Bohr missed completely??? Do you really think that this is a healthy non-cranky argument to spend hundreds of posts on!?!?!?

Never mind. Forget everything you have (not) "learned". Forget everything and start from scratch. Because now I'm going to show you that there is a problem with locality in EPR, with or without Bell & BI. And we are only going to use your personal favorite – Malus' law.

(Hoping that you didn’t had too many hotdogs & beers tonight? :rolleyes:)

Trying to understand nonlocality - only with Malus' law, and without BI!

Malus' law: I = I0 cos2 θi

Meaning that the intensity (I) is given by the initial intensity (I0) multiplied by cos2 and the angle between the light’s initial polarization direction and the axis of the polarizer (θi).

Translated to QM and one single photon, we get the probability for getting thru the polarizer in cos2(θi)

If 6 photons have polarization direction 0º, we will get these results at different polarizer angles:

Angle Perc. Result
----------------------
0º 100% 111111
22.5º 85% 111110
45º 50% 111000
67.5º 15% 100000
90º 0% 000000

1 denotes the photon got thru and 0 denotes stopped. As you can see, this is 100% compatible to Malus' law and the intensity of polarized light.

In experiments with entangled photons, the parameters are tuned and adjusted to the laser polarization, to create the state |ΨEPR> and the coincidence count for N(0º,0º) and N(90º,90º) and N(45º,45º) is checked to be accurate.

As you see, not one word about Bell or BI so far, it’s only Malus' law and EPR.

Now, if we run 6 entangled photons for Alice & Bob with both polarizers at 0º, we will get something like this:

A(0º) B(0º) Correlation
---------------------------
101010 101010 100%

The individual outcome for Alice & Bob is perfectly random. It's the correlation that matters. If we run the same test once more, we could get something like this:

A(0º) B(0º) Correlation
---------------------------
001100 001100 100%

This time we have different individual outcome, but the same perfect correlation statistics.

The angle of the polarizers is not affecting the result, as long as they are the same. If we set both to 90º we could get something like this:

A(90º) B(90º) Correlation
---------------------------
110011 110011 100%

Still 100% perfect correlation.

(In fact, the individual outcome for Alice & Bob can be any of the 64 combinations [26] on any angle, as long as they are identical, when the two angles are identical.)

As you might have guessed, there is absolutely no problem to explain what is happening here by a local "phenomena". I can write a computer program in 5 min that will perfectly emulate this physical behavior. All we have to do is give the entangled photon pair the same random preexisting local value, and let them run to the polarizers. No problem.

Now, let's make things a little more 'interesting'. Let's assume that Alice polarizer will stay fixed at angle 0º and Bob's polarizer will have any random value between 0º and 90º. To not make things too complicated at once, we will only check the outcome when Alice get a photon thru = 1.

What will the probabilities be for Bob, at all these different angles? Is it at all possible to calculate? Can we make a local prediction?? Well YES!

Bob Corr. Result
----------------------
0º 100% 111111
22.5º 85% 111110
45º 50% 111000
67.5º 15% 100000
90º 0% 000000

WE RUN MALUS' LAW! And it works!!

Obviously at angles 0º and 90º the individual photon outcome must be exactly as above. For any other angle, the individual photon outcome is random, but the total outcome for all 6 photons must match Malus' law.

But ... will this work even when we count Alice = 0 at 0º ... ??

Sure! No problem!

All we have to do is to check locally if Alice is 0 or 1, and mirror the probabilities according to Malus' law. If Alice = 0 we will get this for Bob:

Bob Corr. Result
----------------------
0º 100% 000000
22.5º 85% 100000
45º 50% 111000
67.5º 15% 111110
90º 0% 111111

Can I still write a computer program that perfectly emulates this physical behavior? Sure! It will maybe take 15 min this time, but all I have to do is to assign Malus' law locally to Bob's photon, in respect of Alice random value 1/0, and let the photons run to the polarizers. No problem.

We should note that Bob's photons in this scenario will not have a preexisting local value, before leaving the common source. All Bob's photons will get is Malus' law, 'adapted' to Alice preexisting local value 1 or 0.

I don't know if this qualify for local realism, but it would work mathematically, and could be emulated perfectly in a computer program.

And please note: Not one word about Bell or BI so far, only Malus' law and EPR.

BUT NOW IT'S TIME FOR THAT 'LITTLE THING' THAT CHANGES EVERYTHING! :devil:

Are you ready ThomasT? This is the setup:

Alice & Bob are separated by 20 km. The source creating entangled photon pairs is placed in the middle, 10 km from Alice and 10 km from Bob.

The polarizers at Alice & Bob are rotating independently random at very high speed between 0º and 90º.

It takes light 66 microseconds (10-6) to travel 20 km (in vacuum) from Alice to Bob.

The total time for electronic and optical processes in the path of each photon at the detector is calculated to be approximately 100 nanoseconds (10-9).

Now the crucial question is - Can we make anything at the local source to 'save' the statistics at polarizers separated by 20 km? Can we use any local hidden variable or formula, or some other unknown 'magic'?? Could we maybe use the 'local' Malus' law even in this scenario to 'fix it'!?!?

I say definitely NO. (What would that be?? A 20 km long Bayesian-probability-chain-rule???? :eek:)

WHY!?

BECAUSE WE DO NOT KNOW WHAT ANGLE THE TWO POLARIZERS SEPARATED BY 20 KM WILL HAVE UNTIL THE LAST NANOSECONDS AND IT TAKES 66 MICROSECONDS FOR ALICE & BOB TO EXCHANGE ANY INFORMATION.

ThomasT, I will challenge you on the 'easiest' problem we have here - to get a perfect correlation (100%) when Alice & Bob measures the entangled photon pairs at the same angle. That's all.

Could you write a simple computer program, or explain in words and provide some examples of the outcome for 6 pair of photons, as I have done above, how this could be achieved without nonlocality or FTL?

(Philosophical tirades on "joint probabilities" etc are unwarranted, as they don't mean anything practical.)

If you can do this, and explain it to me, I promise you that I will start a hunger strike outside the door of the Royal Swedish Academy of Sciences, until you get the well deserved Nobel Prize in Physics!!

AND REMEMBER – I HAVE NOT MENTIONED ONE WORD ABOUT BELL OR BI !!!

Good luck!

P.S. Did I say that you are not allowed to get perfect correlation (100%) anywhere else in your example, when the angles differ? And "weird" interpretations don’t count. :biggrin:

rabbitrabbit

Jul5-10, 01:49 PM

question about the double split experiment.

So detectors placed at the slits create the wave function collapse of the photon! why doesn't the actual slit experiment itself create the wave function collapse?

my_wan

Jul5-10, 06:34 PM

I'm curious if it's possible to create polarization entangled beams in which the each beam can have some statistically significant non-uniform polarization. The shutter idea I suggested breaks the inseparable condition, collapses the wavefunction so to speak. Yet still might be worth looking at in some detail.

Anybody know what kind of effects a PBS would have on the polarization of a polarized beam that is passed through it? Would each resulting beam individually retain some preferential polarization?

Rabbitrabbit,
Not real sure what your asking. It appears a bit off topic in this thread. The interference pattern, locations and distribution of the individual points of light, doesn't tell you which hole the photons came through. So how can it collapse the wave function of something that can't be known from the photon detections? This thread is probably not the best place for such a discussion.

my_wan

Jul5-10, 11:24 PM

Does BI violations require an oversampling, relative to the (max) classical limit, of the "full Universe" to account for? This may be an entirely separate argument from the local or realism issues, but the answer is no. Here's why.

Pick any offset, such as 22.5, and note the over-count relative to the (max) classical limit, 10.36% in this case. Now for every unique angle in which a coincidences exceed the classical limit, there exist a one to one correspondence to a unique angle that undercounts the (max) classical limit by that same percentage. In the example given it's 67.5. Quantitatively equivalent angles, of course, exist in each quadrant of the coordinate system, but a truly unique one to one correspondence exist in each quadrant alone, of a given coordinate choice.

This, again, doesn't involve or make any claims about the capacity for a classical model to mimic product state statistics. What it does prove is that a coincidence average over all possible settings, involving BI violations, does not exceed the coincidence average, over all settings, given a classical 'maximum' per Bell's ansatz. They are equal averaged over all settings.

The point of this is that I agree that the "unfair sample" argument isn't valid. By this I mean that the notion that you can account for the observed relative variations by assuming that a sufficient portion of the events go undetected is incongruent with experimental constraints. However, other forms of sampling arguments can also in general be defined as an "unfair sampling" argument. Which don't necessarily involve missing detections. Thus it may not always be valid to invoke the illegitimacy of the missing detection "unfair sampling" argument to every "fair sampling" argument.

In fact the only way to rule out all possible forms of a sampling argument is to demonstrate that the sum of all coincidences over all possible detector settings exceeds the classical maximum limit. Yet the above argument proves they are exactly equivalent in this one respect.

Any objections?

DevilsAvocado

Jul6-10, 10:38 AM

... ThomasT, I will challenge you on the 'easiest' problem we have here - to get a perfect correlation (100%) when Alice & Bob measures the entangled photon pairs at the same angle. That's all.

Could you write a simple computer program, or explain in words and provide some examples of the outcome for 6 pair of photons, as I have done above, how this could be achieved without nonlocality or FTL?
...
If you can do this, and explain it to me, I promise you that I will start a hunger strike outside the door of the Royal Swedish Academy of Sciences, until you get the well deserved Nobel Prize in Physics!!

OMG! I have to give the Nobel to myself! :rofl:

Sorry... :redface:

All we have to do is to assign Malus' to both Alice & Bob (mirrored randomly 1/0), and this will work fine for checking perfect correlation (100%) at the same angle:

Angle Bob Alice Correlation
-----------------------------------
0º 111111 111111 100%
22.5º 111110 111110 100%
45º 111000 111000 100%
67.5º 100000 100000 100%
90º 000000 000000 100%

The 'problems' only occurs when we have different angles for Alice & Bob (except 0º/90º):

A 67.5º B 22.5º Correlation
---------------------------
100000 111110 33%

Here the difference is 67.5 - 22.5 = 45º and the correlation should be 50%, and this is also depends on the individual outcome, since this will give 0% correlation (instead of the correct 50%):

A 67.5º B 22.5º Correlation
---------------------------
000001 111110 0%

Well, something more to consider... it’s apparently possible to solve the perfect correlation locally... and maybe that’s what Bell has been telling us all the time! :biggrin:

Sorry again. :blushing:

DevilsAvocado

Jul6-10, 11:05 AM

... In fact the only way to rule out all possible forms of a sampling argument is to demonstrate that the sum of all coincidences over all possible detector settings exceeds the classical maximum limit. Yet the above argument proves they are exactly equivalent in this one respect.

Any objections?

The "fair sampling assumption" is also called the "no-enhancement assumption", and I think that is a much better term. Why should we assume that nature has an unknown "enhancement" mechanism that filter out those photons, and only those, who would give us a completely different experimental result!?

Wouldn’t that be an even stranger "phenomena" than nonlocality?:bugeye:?

And the same logic goes for "closing all loopholes at once". Why nature should chose to expose different weaknesses in different experiments? That is closed separately??

It doesn’t make sense.

my_wan

Jul6-10, 11:43 AM

Here's a particular case were the fair sampling of full Universe objection may not be valid, in the thread:
Why the De Raedt Local Realistic Computer Simulations are wrong (http://www.physicsforums.com/showthread.php?t=369286)
Strangely, and despite the fact that it "shouldn't" work, the results magically appeared. Keep in mind that this is for the "Unfair Sample" case - i.e. where there is a subset of the full universe. I tried for 100,000 iterations. With this coding, the full universe for both setups - entangled and unentangled - was Product State. That part almost makes sense, in fact I think it is the most reasonable point for a full universe! What doesn't make sense is the fact that you get Perfect Correlations when you have random unknown polarizations, but get Product State (less than perfect) when you have fixed polarization. That seems impossible.

However, by the rules of the simulation, it works.

Now, does this mean it is possible to violate Bell? Definitely not, and they don't claim to. What they claim is that a biased (what I call Unfair) sample can violate Bell even though the full universe does not. This particular point has not been in contention as far as I know, although I don't think anyone else has actually worked out such a model. So I think it is great work just for them to get to this point.

Here "unfair sampling" was equated with a failure to violate BI, while the "full universe" was invoked to differentiate between BI and the and a violation of BI. Yet, as I demonstrated in post #988 (http://www.physicsforums.com/showthread.php?p=2788956#post2788956), the BI violations of QM, on average of all setting, does not contain a "full universe" BI violation.

Let's look at a more specific objection, to see why the "fair sampling" objection may not valid:
After examining this statement, I believe I can find an explanation of how the computer algorithm manages to produce its results. It helps to know exactly how the bias must work. :smile: The De Raedt et al model uses the time window as a method of varying which events are detected (because that is how their fair sampling algorithm works). That means, the time delay function must be - on the average - such that events at some angle settings are more likely to be included, and events at other angle setting are on average less likely to be included.

Here it was presented 'as if' event detections failures represented a failure to detect photons. This is absolutely not the case. The detection accuracy, of photons, remained constant throughout. Only the time window in which they were detected varied, meaning there was no missing detections, only a variation of whether said detections fell within a coincidence window or not. Thus the perfectly valid objection to using variations in detection efficiency (unfair sampling) does not apply to all versions of unfair sampling. The proof provided in post #988 (http://www.physicsforums.com/showthread.php?p=2788956#post2788956) tells us QM BI violations are not "full universe" BI violation either.

my_wan

Jul6-10, 12:04 PM

The "fair sampling assumption" is also called the "no-enhancement assumption", and I think that is a much better term. Why should we assume that nature has an unknown "enhancement" mechanism that filter out those photons, and only those, who would give us a completely different experimental result!?

Wouldn’t that be an even stranger "phenomena" than nonlocality?:bugeye:?

And the same logic goes for "closing all loopholes at once". Why nature should chose to expose different weaknesses in different experiments? That is closed separately??

It doesn’t make sense.

That depends on what you mean by "enhancement". If by "enhancement" you mean that a summation of all possible or "full universe" choice of measurements settings leads to an excess of detection events, then yes, I would agree. But the point of post #988 was that the BI violations defined by QM, and measured, do not "enhance" detection totals over the classical limit when averaged over the "full universe" of detector settings.

That is that for ever detector setting choice which exceeds the classical coincidence limit, there provably exist another choice where coincidences fall below classical coincidence limit, by the exact same amount.

22.5 and 67.5 is one pair such that cos^2(22.5) + cos^2(67.5) = 1. These detection variances are such that there exist an exact one to one ratio between overcount angles and quantitatively identical undercount angles, such that averaged over all possible setting QM and the classical coincidence limits exactly match.

my_wan

Jul6-10, 12:26 PM

my_wan

Jul6-10, 01:58 PM

There's a comparison I'd like to make between the validity of BI violations applied to realism and the validity of objections to fair sampling arguments.

When I claim that the implications of BI are valid but are often overgeneralized, the exact same thing happened, in which the demonstrable invalidity of "unfair sampling", involving detection efficiencies, is overgeneralized to improperly invalidate all "fair sampling" arguments.

The point here is that you are treading in dangerous territory when you attempt to apply a proof involving a class instance to make claims about an entire class. Doing so technically invalidates the claim, whether you are talking about the "fair sampling" class or the "realism" class. Class instances by definition contains constraints not shared by the entire class, and the set of all instances of a class remains undefined within science.

Of course you can try and object to my refutation of the invalidity of "fair sampling" when such "fair sampling" doesn't involve less than perfect detection efficiencies. :biggrin:

Gordon Watson

Jul6-10, 03:36 PM

Dmitry67

Jul6-10, 03:48 PM

You can find examples in the set theory.
This is a tricky subject closely connected to the Axiom of Choice (if I understood the idea correctly).

For example, you can write any real number, given you as input. However, as power of continuum is higher than the power of integers, there are infinitely many real numbers, which cant be given and an example. You can even provide a set of real numbers, defined in a tricky way so you cant give any examples of the numbers, belonging to that set, even that set covers [0,1] almost everywhere and it has infinite number of members!

Imagine: set of rational numbers. For example, 1/3
Set of transendent numbers, for example pi.
Magic set I provide: no example can be given

It becomes even worse when some properties belong exclusively to that 'magic' set. See Banach-Tarski paradox as an example. No example of that weird splitting can be provided (because if one could do it then the theorem could be proven without AC)

DevilsAvocado

Jul6-10, 03:53 PM

... Here it was presented 'as if' event detections failures represented a failure to detect photons. This is absolutely not the case. The detection accuracy, of photons, remained constant throughout. Only the time window in which they were detected varied, meaning there was no missing detections, only a variation of whether said detections fell within a coincidence window or not. Thus the perfectly valid objection to using variations in detection efficiency (unfair sampling) does not apply to all versions of unfair sampling. The proof provided in post #988 (http://www.physicsforums.com/showthread.php?p=2788956#post2788956) tells us QM BI violations are not "full universe" BI violation either.

Have seen the code?

In the case of the De Raedt Simulation there is no "time window", only a pseudo-random number in r0:

http://i49.tinypic.com/6oztpt.png

I don’t think this has much to do with real experiments – this is a case of trial & error and "fine-tuning".

One thing that I find 'peculiar' is the case that the angles of the of the detectors are not independently random, angle1 is random but angle2 is always at fixed value offset...?:confused:?

To me this does not look like the "real thing"...

' Initialize the detector settings used for all trials for this particular run - essentially what detector settings are used for "Alice" (angle1) and "Bob" (angle2)
If InitialAngle = -1 Then
angle1 = Rnd() * Pi ' set as being a random value
Else
angle1 = InitialAngle ' if caller specifies a value
End If
angle2 = angle1 + Radians(Theta) ' fixed value offset always
angle3 = angle1 + Radians(FixedOffsetForChris) ' a hypothetical 3rd setting "Chris" with fixed offset from setting for particle 1, this does not affect the model/function results in any way - it is only used for Event by Event detail trial analysis

...

For i = 1 To Iterations:

If InitialAngle = -2 Then ' SPECIAL CASE: if the function is called with -2 for InitialAngle then the Alice/Bob/Chris observation settings are randomly re-oriented for each individual trial iteration.
angle1 = Rnd() * Pi ' set as being a random value
angle2 = angle1 + Radians(Theta) ' fixed value offset always
angle3 = angle1 + Radians(FixedOffsetForChris) ' a hypothetical 3rd setting "Chris" with fixed offset from setting for particle 1, this does not affect the model/function results in any way - it is only used for Event by Event detail trial analysis
End If

...

Gordon Watson

Jul6-10, 03:58 PM

You can find examples in the set theory.
This is a tricky subject closely connected to the Axiom of Choice (if I understood the idea correctly).

For example, you can write any real number, given you as input. However, as power of continuum is higher than the power of integers, there are infinitely many real numbers, which cant be given AS an example. You can even provide a set of real numbers, defined in a tricky way so you cant give any examples of the numbers, belonging to that set, even IF that set covers [0,1] almost everywhere and it has infinite number of members!

Imagine: set of rational numbers. For example, 1/3
Set of transendent numbers, for example pi.
Magic set I provide: no example can be given

It becomes even worse when some properties belong exclusively to that 'magic' set. See Banach-Tarski paradox as an example. No example of that weird splitting can be provided (because if one could do it then the theorem could be proven without AC)

Dear Dmitry67, many thanks for quick reply. I put 2 small edits in CAPS above.

Hope that's correct?

But I do not understand your "imagine" ++ example.

Elaboration in due course would be nice.

Thank you,

JenniT

DevilsAvocado

Jul6-10, 04:26 PM

That depends on what you mean by "enhancement".
It means exactly the same as "fair sampling assumption": That the sample of detected pairs is representative of the pairs emitted.

I.e. we are not assuming that nature is really a tricky bastard, by constantly not showing us the "enhancements" that would spoil all EPR-Bell experiments, all the time. :biggrin:

the "full universe" of detector settings.
What does this really mean??

That is that for ever detector setting choice which exceeds the classical coincidence limit, there provably exist another choice where coincidences fall below classical coincidence limit, by the exact same amount.

22.5 and 67.5 is one pair such that cos^2(22.5) + cos^2(67.5) = 1. These detection variances are such that there exist an exact one to one ratio between overcount angles and quantitatively identical undercount angles, such that averaged over all possible setting QM and the classical coincidence limits exactly match.

my_wan, no offence – but is this the "full universe" of detector settings?:bugeye:?

I don’t get this. What on earth has cos^2(22.5) + cos^2(67.5) = 1 to do with the "fair sampling assumption"...?

Do you mean that we are constantly missing photons that would, if they were measured, always set correlation probability to 1?? I don’t get it...

DevilsAvocado

Jul6-10, 04:48 PM

... You have a single pair of photons. They are both detected within a time window, thus a coincidence occurs. Now suppose you chose different settings and detected both photons, but they didn't fall within the coincidence window. Now in both cases you had a 100% detection rate, so "fair sampling", defined in terms of detections efficiencies, is absolutely invalid. Yet, assuming the case defined holds, this was a "fair sampling" argument that did not involve detection efficiencies, and can not be ruled out by perfectly valid arguments against "fair sampling" involving detection efficiencies.

I could be wrong (as last time when promising a Nobel o:)). But to my understanding, the question of "fair sampling" is mainly a question of assuming – even if we only have 1% detection efficiency – that the sample we do get is representative of all the pairs emitted.

To me, this is as natural as when you grab hand of white sand on a white beach, you don’t assume that every grain of sand that you didn’t get into your hand... is actually black! :wink:

my_wan

Jul6-10, 04:50 PM

Have seen the code?

In the case of the De Raedt Simulation there is no "time window", only a pseudo-random number in r0:
I'm in the process of reviewing De Raedt's work. I'm not convinced of his argument, the physical interpretation is quiet a bit more complex. Even made the observation:
[QUOTE="http://arxiv.org/abs/1006.1728"]The EBCM is entirely classical in the sense that it uses concepts of the macroscopic world and makes no reference to quantum theory but is nonclassical in the sense that it does not rely on the rules of classical Newtonian dynamics.

My point does not depend on any such model, working or not, or even whether or not the claim itself was ultimately valid. I argued against the validity only of the argument itself, not it's claims. My point was limited to the over-generalization of interpreting the obvious invalidity of a "fair sampling" involving detection efficiencies to all "fair sampling" arguments that assumes nothing less than perfect detection efficiencies.

In this way, my argument is not dependent of De Raedt's work at all, and only came into play as an example involving DrC's rebuttal which inappropriately generalized "fair sampling" as invalid, on the basis that a class instance of "fair sampling" that assumes insufficient detection efficiencies is invalid.

I don’t think this has much to do with real experiments – this is a case of trial & error and "fine-tuning".

One thing that I find 'peculiar' is the case that the angles of the of the detectors are not independently random, angle1 is random but angle2 is always at fixed value offset...?:confused:?

To me this does not look like the "real thing"...
Yes, it appears to suffer in the same way my own attempts did, but I haven't actually got that far yet in the review. If the correspondence holds, then he accomplished algebraically what I did with a quasi-random distribution of a bit field. However, when you say angle2 is always at fixed value offset, what is it always offset relative to? You can spin the photon source emitter without effect, so it's not a fixed value offset relative to the source emitter. It's not a fixed value offset relative to the the other detector. In fact, the fixed offset is relative to an arbitrary non-physical coordinate choice, which itself can be arbitrarily chosen.

I still need a better argument to fully justify this non-commutativity between arbitrary coordinate choices, but the non-commutativity of classical vector products may pay a role.

Again, my latest argument is not predicated on De Raedt's work or any claim that BI violations can or can't be classically modeled. My argument was limited to, and only to, the use of applying the invalidity of an "unfair sampling" involving limited detection efficiencies to "unfair sampling" not involving any such limits in detection efficiencies. It's a limit of what can be claimed as a proof, and involves no statements about how nature is.

my_wan

Jul6-10, 05:06 PM

Dear my_wan;

This is very interesting to me. I would love to see some expansion on the points you are advancing, especially about this:

Class instances by definition contains constraints not shared by the entire class, and the set of all instances of a class remains undefined within science.

Many thanks,

JenniT
I give an example in post #993, when I described two different "fair sampling" arguments. One involving variations in detection statistics, the other involving variations involving detection timing. The point was not that either is a valid explanation of BI violations, the point was that proving the first instance is invalid in the EPR context does not rule out the second instance. Yet they are both members of the same class called "fair sampling" arguments. This was only an example, not a claim of a resolution to BI violations.

You can find examples in the set theory.
This is a tricky subject closely connected to the Axiom of Choice (if I understood the idea correctly).
Yes! I personally think it likely you have made fundamental connection that gets a bit deeper than what I could do more than hint at in the context of the present debate. :biggrin:

DrChinese

Jul6-10, 05:34 PM

[QUOTE=DevilsAvocado;2789893]Have seen the code?

In the case of the De Raedt Simulation there is no "time window", only a pseudo-random number in r0:
I'm in the process of reviewing De Raedt's work. I'm not convinced of his argument, the physical interpretation is quiet a bit more complex.

In this way, my argument is not dependent of De Raedt's work at all, and only came into play as an example involving DrC's rebuttal which inappropriately generalized "fair sampling" as invalid, on the basis that a class instance of "fair sampling" that assumes insufficient detection efficiencies is invalid.

The De Raedt simulation is an attempt to demonstrate that there exists an algorithm whereby (Un)Fair Sampling leads to a violation of a BI - as observed - while the full universe does not (as required by Bell). They only claim that their hypothesis is "plausible" and do not really claim it as a physical model. A physical model based on their hypothesis would be falsifiable. Loosely, their idea is that a photon might be delayed going through the apparatus and the delay might depend on physical factors. Whether you find this farfetched or not is not critical to the success of their simulation. The idea is that it is "possible".

My point has been simply that it is not at all certain that a simulation like that of De Raedt can be successfully constructed. So that is what I am looking at. I believe that there are severe constraints and I would like to see these spelled out and documented. Clearly, the constraint of the Entangled State / Product State mentioned in the other thread is a tought one. But as of this minute, I would say they have passed the test.

At any rate, they acknowledge that Bell applies. They do not assert that the full universe violates a BI.

my_wan

Jul6-10, 06:00 PM

It means exactly the same as "fair sampling assumption": That the sample of detected pairs is representative of the pairs emitted.
Yes, the "fair sampling assumption" does assume the sample of detected pairs is representative of the pairs emitted, and assuming otherwise is incongruent with the experimental constraints, thus invalid. An alternative "fair sampling assumption" assumes that the time taken to register a detection is the same regardless of the detector offsets. The invalidity of the first "fair sampling assumption" does not invalidate the second "fair sampling assumption". It's doesn't prove it's valid either, but neither is the claim that the invalidity of the first example invalidates the second.

I.e. we are not assuming that nature is really a tricky bastard, by constantly not showing us the "enhancements" that would spoil all EPR-Bell experiments, all the time. :biggrin:
Again, tricky how. We know it's tricky in some sense. Consider the event timing verses event detection rates in the above example. If you bounce a tennis ball off the wall, its return time is dependent on the angle it hits the wall in front of you. It's path length is also dependent on the angle it hits the wall. Is nature being "tricky" doing this? Is nature being "tricky" if it takes longer to detect a photon passing a polarizer at an angle, than it takes if the polarizer has a common, or more nearly common, polarization as the photon? I wouldn't call that "tricky", any more than a 2 piece pyramid puzzle is. In years only 1 person I met, that hadn't seen it before, was able to solve it without help.
http://www.puzzle-factory.com/pyramid-2pc.html
We already know the speed of light is different in mediums with a different index of refraction.

What does this really mean??
This was in reference to "full universe". DrC and I did use it in a slightly different sense. DrC used it to mean mean any possible 'set of' detector settings. I used it to mean 'all possible' detector settings. I'll explain the consequences in more detail below.

my_wan, no offence – but is this the "full universe" of detector settings?:bugeye:?

I don’t get this. What on earth has cos^2(22.5) + cos^2(67.5) = 1 to do with the "fair sampling assumption"...?

Do you mean that we are constantly missing photons that would, if they were measured, always set correlation probability to 1?? I don’t get it...
No, there are NO photon detections missing! Refer back to post #993. The only difference is in how fast the detection occurs, yet even this is an example, not a claim. If 2 photons hit 2 different detectors at the same time, but one of them takes longer to register the detection, then they will not appear correlated because they appeared to occur at 2 separate times. Not one of the detections is missing, only delayed.

Ok, here's the "full universe" argument again, in more detail.
The classical limit, as defined, sets a maximum correlation rate for any given setting offset. QM predicts, and experiments support, that for the offsets between 0 and 45 degrees the maximum classical limit is exceeded. QM also predicts that, for the angles between 45 and 90 degrees, the QM correlations are less than the classical limit. This is repeated on every 90 degree segment. If you add up all the extra correlations between 0 and 45 degrees, that exceed the classical limit, and add it to the missing correlations between 45 and 90 degrees, that the classical limit allows, you end up with ZERO extra correlations. Repeat for the other 3 90 degree segments and 4 x 0 = 0. QM does not predict any extra correlations when you average over all possible settings. It only allows you to choose certain limited non-random settings where the classical limit is exceeded, which presents problems for classical models.

my_wan

Jul6-10, 06:06 PM

DrC,
Please note that my argument has nothing to do with the De Raedt simulation. It was merely an example of overextending the lack of validity of a fair sampling argument involving limited detection efficiencies to fair sampling arguments that could remain valid even if detection efficiencies were always absolutely perfect.

my_wan

Jul6-10, 06:36 PM

DevilsAvocado

Jul6-10, 06:58 PM

However, when you say angle2 is always at fixed value offset, what is it always offset relative to?

angle2 = angle1 + Radians(Theta) ' fixed value offset always

And Theta is a (user) argument in to the main function.

Again, tricky how.
To me, this is as natural as when you grab hand of white sand on a white beach, you don’t assume that every grain of sand that you didn’t get into your hand... is actually black! :wink:

No, there are NO photon detections missing! Refer back to post #993. The only difference is in how fast the detection occurs, yet even this is an example, not a claim. If 2 photons hit 2 different detectors at the same time, but one of them takes longer to register the detection, then they will not appear correlated because they appeared to occur at 2 separate times. Not one of the detections is missing, only delayed.

Ahh! Now I get it! Thanks for explaining. My guess on this specific case, is that it’s very easy to change the detection window (normally 4-6 ns?) to look for dramatic changes... and I guess that in all of the thousands EPR-Bell experiments, this must have been done at least once...? Maybe DrC knows?

Ok, here's the "full universe" argument again, in more detail.
The classical limit, as defined, sets a maximum correlation rate for any given setting offset. QM predicts, and experiments support, that for the offsets between 0 and 45 degrees the maximum classical limit is exceeded. QM also predicts that, for the angles between 45 and 90 degrees, the QM correlations are less than the classical limit. This is repeated on every 90 degree segment.

Okay, you are talking about this curve, right?

http://i39.tinypic.com/2wr1cgm.jpg

DevilsAvocado

Jul6-10, 07:22 PM

If you add up all the extra correlations between 0 and 45 degrees, that exceed the classical limit, and add it to the missing correlations between 45 and 90 degrees, that the classical limit allows, you end up with ZERO extra correlations.

You could see it this way. You could also see it as the very tricky nature then has to be wobbling between "increasing/decreasing" unfair sampling, which to me makes the argument for fair sampling even stronger...

ThomasT

Jul6-10, 09:30 PM

DA, nice recent (long) post, #985. Sorry for the delay in replying. I've been busy with holiday activities. Anyway, I see that there have been some replies to (and amendents or revisions by you of) your post. I've lost count of how many times I've changed my mind on how to approach understanding both Bell and entanglement correlations. One consideration involves the proper interpretation of Bell's work and results wrt LHV or LR models of entanglement. Another consideration involves the grounds for assuming nonlocality in nature. And yet another consideration involves approaches to understanding how light might be behaving in optical Bell tests to produce the observed correlations, without assuming nonlocality. The latter involves quantum optics. Unfortunately, qo doesn't elucidate instrument-independent photon behavior (ie., what's going on between emission and filtration/detection). So, there's some room for speculation there (not that there's any way of definitively knowing whether a proposed, and viable, 'realistic' model of 'interim' photon behavior corresponds to reality). In connection with this, JenniT is developing an LR model in the thread on Bell's mathematics, and Qubix has provided a link to a proposed LR model by Joy Christian.

Anyway, it isn't like these are easy question/considerations.

Here's a paper that I'm reading which you might be interested in:

http://arxiv.org/PS_cache/arxiv/pdf/0706/0706.2097v2.pdf

And here's an article in the Stanford Encyclopedia of Philosophy on the EPR argument:

http://plato.stanford.edu/entries/qt-epr/#1.2

Pay special attention to Einstein on locality/separability, because it has implications regarding why Bell's LHV ansatz might be simply an incorrect model of the experimental situation rather than implying nonlocality in nature.

Wrt to your exercises illustrating the difficulty of understanding the optical Bell test correlations in terms of specific polarization vectors -- yes, that is a problem. It's something that probably most, or maybe all, of the readers of this thread have worked through. It suggests a few possibilities: (1) the usual notion/'understanding' of polarization is incorrect or not a comprehensive physical description, (2) the usual notion/'understanding' of spin is incorrect or not a comprehensive physical description, (3) the concepts are being misapplied or inadequately/incorrectly modelled, (4) the experimental situation is being incorrectly modelled, (5) the dynamics of the reality underlying instrumental behavior is significantly different from our sensory reality/experience, (6) there is no reality underlying instrumental behavior or underlying our sensory reality/experience, etc., etc. My current personal favorites are (3) and (4), but, of course, that could change. Wrt fundamental physics, while there's room for speculation, one still has to base any speculations on well established physical laws and dynamical principles which are, necessarily, based on real physical evidence (ie. instrumental behavior, and our sensory experience, our sensory apprehension of 'reality' -- involving, and evolving according to, the scientific method of understanding).

And now, since I have nothing else to do for a while, I'll reply to a few of your statements. Keep a sense of humor, because I feel like being sarcastic.

ThomasT, I see you and billschnieder spend hundreds of posts in trying to disprove Bell's (2) with various farfetched arguments, believing that if Bell's (2) can be proven wrong – then Bell's Theorem and all other work done by Bell will go down the drain, including nonlocality.My current opinion is that Bell's proof of the nonviability of his LHV model of entanglement doesn't warrant the assumption of nonlocality. Why? Because, imo, Bell's (2) doesn't correctly model the experimental situation. This is what billschnieder and others have shown, afaict. There are several conceptually different ways to approach this, and so there are several conceptually different ways of showing this, and several conceptually different proposed, and viable, LR, or at least Local Deterministic, models of entanglement.

If any of these approaches is eventually accepted as more or less correct, then, yes, that will obviate the assumption of nonlocality, but, no, that will not flush all of Bell's work down the drain. Bell's work was pioneering, even if his LHV ansatz is eventually accepted as not general and therefore not implying nonlocality.

The aim of the EPR paradox was to show that there was a preexisting reality at the microscopic QM level - that the QM particles indeed had a real value before any measurements were performed (thus disproving Heisenberg uncertainty principle HUP).

To make the EPR paper extremely short; If we know the momentum of a particle, then by measuring the position on a twin particle, we would know both momentum & position for a single QM particle - which according to HUP is impossible information, and thus Einstein had proven QM to be incomplete ("God does not play dice").The papers I referenced above have something to say about this.

Do you understand why we get upset when you and billschnieder argue the way you do?Yes. Because you're a drama queen. But we're simply presenting and analyzing and evaluating ideas. There should be no drama related to that. Just like there's no crying in baseball. Ok?

You are urging PF users to read cranky papers - while you & billschnieder obviously hasn’t read, or understand, the original Bell paper that this is all about??I don't recall urging anyone to read cranky papers. If you're talking about Kracklauer, I haven't read all his papers yet, so I don't have any opinion as to their purported (by you) crankiness. But, what I have read so far isn't cranky. I think I did urge 'you' to read his papers, which would seem to be necessary since you're the progenitor, afaik, of the idea that Kracklauer is a crank and a crazy person.

The position you've taken, and assertions you've made, regarding Kracklauer, put you in a precarious position. The bottom line is that the guy has some ideas that he's promoting. That's all. They're out there for anyone to read and criticize. Maybe he's wrong on some things. Maybe he's wrong on everything. So what? Afaict, so far, he's far more qualified than you to have ideas about and comment on this stuff. Maybe he's promoting his ideas too zealously for your taste or sensibility. Again, who cares? If you disagree with an argument or an idea, then refute it if you can.

As for billschnieder and myself reading Bell's papers, well of course we've read them. In fact, you'll find somewhere back in this thread where I had not understood a part of the Illustrations section, and said as much, and changed my assessment of what Bell was saying wrt it.

And of course it's possible, though not likely, that neither billschnieder nor I understand what Bell's original paper was all about. But I think it's much more likely that it's you who's missing some subleties wrt its interpretation. No offense of course.

Anyway, I appreciate your most recent lengthy post, and revisions, and most of your other posts, as genuine attempts by you to understand the issues at hand. I don't think that anybody fully understands them yet. So physicists and philosophers continue to discuss them. And insights into subtle problems with Bell's formulation, and interpretations thereof, continue to be presented, along with LR models of entanglement that have yet to be refuted.

Please read the stuff I linked to. It's written by bona fide respected physicists.

And, by the way, nice recent posts, but the possible experimental 'loopholes' (whether fair sampling/detection, or coincidence, or communication, or whatever) have nothing to do with evaluating the meaning of Bell's theorem. The correlation between the angular difference of the polarizers and coincidental detection must be, according to empirically established (and local) optical laws, a sinusoidal function, not a linear one.

billschnieder

Jul6-10, 10:35 PM

To make the difference between an experimentally invalid "unfair sampling" argument, involving detection efficiencies, and more general "fair sampling" arguments more clear, consider:

You have a single pair of photons. They are both detected within a time window, thus a coincidence occurs. Now suppose you chose different settings and detected both photons, but they didn't fall within the coincidence window. Now in both cases you had a 100% detection rate, so "fair sampling", defined in terms of detections efficiencies, is absolutely invalid. Yet, assuming the case defined holds, this was a "fair sampling" argument that did not involve detection efficiencies, and can not be ruled out by perfectly valid arguments against "fair sampling" involving detection efficiencies.

I think it is a mistake to think that "unfair sampling" is only referring to detection rate. The CHSH inequality is the following:

|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

It is true that in deriving this, Bell assumed every photon/particle was detected given that his A(.) and B(.) functions are defined as two-valued functions (+1, -1) rather than three-valued functions with a non-detection outcome included. An important point to note here is (1) there is a P(λ), implicit in each of the expectation value terms in that inequality, and Bell's derivation relies on the fact that P(λ) is exactly the same probability distribution for each and every term in that inequality.

Experimentally, not all photons are detected, so the "fair sampling assumption" together with "coincidence circuitry" is used to overcome that problem. Therefore the "fair sampling assumption" is invoked in addition to the coincidence counting to state that the detected coincident photons are representative of the full universe of photon pairs leaving the source.

The next important point to remember is this; (2) in real experiments each term in the inequality is a conditional expectation value, conditioned on "coincidence". The effective inequality being calculated in a real experiment is therefore:

|E(a,b|coinc) + E(a,b'|coinc) + E(a',b|coinc) - E(a',b'|coinc)| <= 2

So then looking at both crucial points above and remember the way experiments are actually performed we come to understand that "fair sampling assumption" entails the following:

1) P(coinc) MUST be independent of λ
2) P(coinc) MUST be independent of a and/or b (ie joined channel efficiencies must be factorizable)
3) P(λ) MUST be independent of a and/or b
4) If for any specific setting pair(a,b), the probability of "non-consideration" of a photon pair (ie, no coincidence) is dependent on the hidden parameter λ, then (1), (2) and (3) will fail, and together with them, the "fair sampling assumption" will fail.

The question then becomes, is it unreasonable to expect that for certain hidden λ, P(coinc) will not be the same in all 4 terms and therefore P(λ) can not be expected to always be the same for all 4 terms?

In fact (2) has been put to the test using real data from the Weihs et al experiment and failed. See the article here (http://arxiv4.library.cornell.edu/abs/quant-ph/0606122, J. Phys. B 40 No 1 (2007) 131-141)
Abstract:

We analyze optical EPR experimental data performed by Weihs et
al. in Innsbruck 1997-1998. We show that for some linear combinations of the
raw coincidence rates, the experimental results display some anomalous behavior
that a more general source state (like non-maximally entangled state) cannot
straightforwardly account for. We attempt to explain these anomalies by taking
account of the relative efficiencies of the four channels. For this purpose, we use the fair
sampling assumption, and assume explicitly that the detection efficiencies for the pairs
of entangled photons can be written as a product of the two corresponding detection
efficiencies for the single photons. We show that this explicit use of fair sampling cannot
be maintained to be a reasonable assumption as it leads to an apparent violation of
the no-signalling principle.

my_wan

Jul6-10, 11:19 PM

Note that I am describing classes of realistic constructs, to demonstrate the absurdity of generalizing the refutation of a single class instance of a realism class to represent a refutation of realism in general. It goes to the lagitamacy of this generalization of realism, as defined by EPR, not to any given class or class instance described.

The most surprising result of such attempts at providing examples realism models that explicitly at odds with realism as defined by EPR, is I'm often paraphrased as requiring what these example model classes are explicitly formulated to reject. Namely: 1) That observables are representative indicators of elements of reality. 2) Real observables are linear representative indicators of such elements. 3) Properties are pre-existing (innate) to such elements. These are all presumptuous, but are diametrically opposed to realism as defined by EPR, thus such constructive elements of reality are not addressed by BI, with or without locality.

But Bell's proof is abstract and mathematical, it doesn't depend on whether it is possible to simulate a given hidden variables theory computationally, so why does it matter what the "computational demands of modeling BI violations" are? I also don't understand your point about a transfinite set of hidden variables and Hilbert's Hotel paradox...do you think there is some specific step in the proof that depends on whether lambda stands for a finite or transfinite number of facts, or that would be called into question if we assumed it was transfinite?
I understand the mathematical abstraction BI is based on. It is because the mathematics is abstract that the consequent assumptions of the claims goes beyond validity of BI. Asher Peres notes that "element of reality" are identified with the EPR definition. He also notes the extra assumption that the sum or product of two commuting elements of reality also is an element of reality. In:
Recursive definition for elements of reality (http://www.springerlink.com/content/g864674334074211/)
He outlines the algebraic contradiction that ensues from these assumptions. On what basis is these notions of realism predicated? If "elements of reality" exist, how justified are we in presuming that properties are innate to these elements?

Our own DrC has written some insightful comments concerning realism, refuting Hume, in which it was noted how independent variables must be unobservable. If all fundamental variables are in some sense independent, how do we get observables? My guess is that observables are a propagation of events, not things. Even the attempt to detect an "elements of reality" entails the creation of events, where what's detected is not the "elements of reality" but the propagation observables (event sets) created by the events, not the properties of "elements of reality".

Consider a classical analog involving laminar verses turbulent flow, and suppose you could only define density in terms of the event rates (collisions in classical terms) in the medium. The classical notion of particle density disappears. This is at a fundamental level roughly the basis of many different models, involving both GR, QM, and some for QG. Erik Verlinde is taking some jousting from his colleagues for a preprint along roughly similar lines.

The point here is that associating properties are something owned by things is absurdly naive, and even more naive to assume real properties are commutative representations of things (think back to the event rate example). This is also fundamentally what is meant by "statistically complete variables" in published literature.

Now you can object to it not being "realistic" on the basis of not identifying individual "elements of reality", but if the unobservability argument above is valid, on what grounds do you object to a theory that doesn't uniquely identify unobservables (independent elements of reality)? Is that justification for a claim of non-existence?

I'm not sure what you mean by "projections from a space"...my definition of local realism above was defined in terms of points in our observable spacetime, if an event A outside the past light cone of event B can nevertheless have a causal effect on B then the theory is not local realist theory in our spacetime according to my definition, even if the values of variables at A and B are actually "projections" from a different unseen space where A is in the past light cone of B (is that something like what you meant?)
Consider a standard covariant transform in GR. A particular observers perspective is a "projection" of this curved space onto the Euclidean space our perceptions are predisposed to. Suppose we generalize this even further, to include the Born rule, |/psi|^2, such that a mapping of a set of points involves mapping them onto a powerset of points. Aside from the implications in set theory, this leads to non-commutativity even if the variables are commutative within the space that defines them. Would such a house of mirrors distortion of our observer perspective of what is commutative invalidate "realism", even when those same variables are commutative in the space that defined them?

Again, this merely points to the naivety of "realism" as has been invalidated by BI violations. What BI violations don't do is invalidate "realism", or refute that "elements of reality" exist that is imposing this house of mirrors effect on our observation of observables. Assuming we observe "reality" without effect on it is magical thinking from a realist perspective. Assuming we are a product of these variables, while assuming 'real' variables must remain commutative is as naive as the questions on this forum asking why doubling speed more than doubles the kinetic energy. But if your willing to just "shut up and calculate" it's never a problem.

They did make the claim that there should in certain circumstances be multiple elements of reality corresponding to different possible measurements even when it is not operationally possible to measure them all simultaneously, didn't they?
Yes, but that is only a minimal extension to the point I'm trying to make, not a refutation of it. This corresponds to certain classical contextuality schemes attempted to model BI violations. The strongest evidence against certain types of contextuality schemes, from my perspective, involves metamaterials and other such effects, not BI violations. I think Einstein's assumptions of what constraints realism imposes is overly simplistic, but that doesn't justify the claim that "elements of reality" don't exist.

I don't follow, what "definitions counter to that EPR provided" are being rejected out of hand?
Are you trying to say here that no "realism" is possible that doesn't accept "realism" as operationally defined by EPR? The very claim that BI violations refute "realism" tacitly makes this claim. If you predicate "realism" on the strongest possible realism, then the notion that a fundamental part has properties is tantamount to claiming it contains a magic spell. It would also entail that measuring without effect is telepathy, and at a fundamental level such an effect must be at least as big as what you want to measure. The Uncertainty Principle, as originally derived, was due to these very thought experiments involving realistic limits, not QM.

So as long as you insist that a local theory cannot be "realistic", even by stronger definitions of realism than EPR provided, then you are rejecting realism "definitions counter to that EPR provided". Have I not provided examples and justification for "realism" definitions that are counter to the EPR definition? Those examples are not claims of reality, they are examples illustrating the naivety of the constraints imposed on the notion of realism and justified on the EPR argument.

What's the statement of mine you're saying "unless" to? I said "there's no need to assume ... you are simply measuring a pre-existing property which each particle has before measurement", not that this was an assumption I made. Did you misunderstand the structure of that sentence, or are you actually saying that if "observable are a linear projection from a space which has a non-linear mapping to our measured space of variables", then that would mean my statement is wrong and that there is a need to assume we are measuring pre-existing properties the particle has before measurement?
I said "unless" to "there's no need to assume, [...], you are simply measuring a pre-existing property". This was only an example, in which a "pre-existing property" does not exist, yet both properties and "elements of reality do. I give more detail on mappng issue with the Born rule above. These examples are ranges of possibilities that exist within certain theoretical class instances as well as in a range of theoretical classes. Yet somehow BI violations is supposed to trump every class and class instance and disprove realism if locality is maintained. I don't think so.

You got the paraphrase sort of right until you presumed I indicated, "is a need to assume we are measuring pre-existing properties the particle has before measurement". No, I'm saying the lack of pre-existing properties says nothing about the lack of pre-existing "elements of reality". Nor does properties dynamically generated by "elements of reality" a priori entail any sort of linearity between "elements of reality" and properties, at any level.

Why would infinite or non-compressible physical facts be exceptions to that? Note that when I said "can be defined" I just meant that a coordinate-independent description would be theoretically possible, not that this description would involve a finite set of characters that could be written down in practice by a human. For example, there might be some local variable that could take any real number between 0 and 1 as a value, all I meant was that the value (known by God, say) wouldn't depend on a choice of coordinate system.
Why would infinite indicate non-compressible? If you define an infinite set of infinitesimals in a arbitrary region, why would that entail even a finite subset of that space is occupied? Even id a finite subset of that space was occupied, it still doesn't entail that it's a solid. Note my previous reference to Hilbert's paradox of the Grand Hotel. Absolute density wouldn't even have a meaning. Yes, a coordinate-independent description would be theoretically possible, yet commutativity can be dependent on a coordinate transform. You can make a gravitational field go away by the appropriate transform, but you can't make its effects on a given observers perspective go away. The diffeomorphism remains under any coordinate choice, and what appears linear in one coordinate choice may not be under another coordinate choice.

As you rotate the direction of the beams, are you also rotating the positions of the detectors so that they always lie in the path of the beams and have the same relative angle between their orientation and the beam? If so this doesn't really seem physically equivalent to rotating the detectors, since their the relative angle between the detector orientation and the beam would change.
Actually the detectors remain as the beams are rotated, such that the relative orientation of the emitter and photon polarizations changes wrt the detectors, without effecting the coincidence rate. The very purpose of rotating the beam is to change emitter and photons orientation wrt the detectors. Using the same predefined photons, it even changes which individual photons take which path through the polarizers, yet the coincidence rates remain. I can also define a bit field for any non-zero setting. I'm attempting to rotate the polarization of the photons to be located at different positions within the bit field, to mimic this effect on the fly. So the individual photons contain this information, rather than some arbitrarily chosen coordinate system. It will also require a statistical splitting of properties if it works, which I have grave doubts.

But that's just realism, it doesn't cover locality (Bohmian mechanics would match that notion of realism for example). I think adding locality forces you to conclude that each basic element of reality is associated with a single point in spacetime, and is causally affected only by things in its own past light cone.
Would a local theory with "elements of reality" which dynamically generate but do not posses pre-existing properties qualify as a "realistic" theory? I think your perception what I think about points in spacetime is distorted by the infinite density assumption, much like Einstein's thinking. Such scale gauges, to recover the hierarchical structure of the standard model, tend to be open parameters in deciding a theoretical construct to investigate. At a fundamental level, lacking any hierarchy, gauges lose meaning due to coordinate independence. The infinite density assumption presumes a pre-existing meaning to scale. It might be better to think in terms of non-standard calculus to avoid vague or absolutist (as in absolutely solid) notions of infinitesimals. Any reasonable conception of infinitesimals in set theory indicates the "solid" presumption is the most extreme case of an extreme range of possibilities. Whole transfinite hierarchies of limits exist in the interim.

my_wan

Jul6-10, 11:24 PM

I think it is a mistake to think that "unfair sampling" is only referring to detection rate.
Weird, that was the entire point of several post. Yet here I am making the mistake of claiming what I spent all these post refuting? Just weird.

billschnieder

Jul6-10, 11:42 PM

Weird, that was the entire point of several post. Yet here I am making the mistake of claiming what I spent all these post refuting? Just weird.
Oh not your mistake. I was agreeing with you from a different perspective, there is a missing also somewhere there!

my_wan

Jul6-10, 11:57 PM

Ahh! Now I get it! Thanks for explaining. My guess on this specific case, is that it’s very easy to change the detection window (normally 4-6 ns?) to look for dramatic changes... and I guess that in all of the thousands EPR-Bell experiments, this must have been done at least once...? Maybe DrC knows?
Yes, it may be possible to refute this by recording time stamps and analyzing any continuity in time offsets of detections that missed the coincidence time window.

The main point remains, irrespective of experimental validity of this one example. You can't generally apply a proof invalidating a particular class instance to invalidate the whole class.

Okay, you are talking about this curve, right?
Yes. You can effectively consider the curve above the x-axis as exceeding the classical 'max' limit, while the curve below the x-axis as falling short of the classical 'max' limit by the exact same amount it was exceeded in the top part.

Again. This doesn't demonstrate any consistency with any classical model of BI violations. It only indicates that in the "full universe" of "all" possible settings there are no excess of detections relative to the classical limit. Thus certain forms of "fair sampling" arguments are not a priori invalidated by the known invalid "fair sampling" argument involving detection efficiencies. Neither does it mean that such "fair sampling" arguments can't be ruled out by other means., as indicated above.

It's difficult to maintain my main point, which involves the general applicability of a proof to an entire class or range of classes, when such a proof is known to be valid in a given class instance. My example of cases where a given constraint is abrogated is too easily interpreted as a claim or solution in itself. Or worse, reinterpreted as a class instance of the very class instance it was specifically formulated not to represent.

my_wan

Jul7-10, 12:08 AM

You could see it this way. You could also see it as the very tricky nature then has to be wobbling between "increasing/decreasing" unfair sampling, which to me makes the argument for fair sampling even stronger...
Physically it's exactly equivalent to a tennis ball being bounced off a wall taking a longer route back as the angle it hits the wall increases. It only requires the assumption that the more offset a polarizer is the longer it takes the photon to tunnel through it. Doesn't really convince me either without some testing, but certainly not something I would call nature being tricky. At least not any more tricky than even classical physics is known to be at times. Any sufficiently large set of dependent variables are going to be tricky, no matter how simple the underlying mechanisms. Especially if it looks deceptively simple on the surface.

my_wan

Jul7-10, 12:14 AM

Oh not your mistake. I was agreeing with you from a different perspective, there is a missing also somewhere there!
Oh, my bad. I can read it with that interpretation now also. The "also" would have made it clear on the first read.

Dmitry67

Jul7-10, 05:56 AM

Dear Dmitry67, many thanks for quick reply. I put 2 small edits in CAPS above.

Hope that's correct?

But I do not understand your "imagine" ++ example.

Elaboration in due course would be nice.

Thank you,

JenniT

Some strings define real numbers. For example,

4.5555
pi
min root of the following equation: ... some latex code...

As any string is a word in finite alphabet, the set of all possible strings is countable, like integers. However, the set or real numbers has the power of continuum.

Call the set of all strings, which define real numbers E
Call the set of all real numbers, defined by E as X
Now exclude X from R (set of all real numbers). The result (set U) is not empty (because R is continuum and X is countable). It is even infinite.

So you have a set with infinite number of elements, for example... for example... well, if you can provide an example by writing a number itself (it is also a string) or defining it in any possible way, then you can find that string in E and the corresponding number in X. Hence there is no such number in U.

So you have a very weird set U. No element of it can be given as example. U not only illustrates that Axiom of Choice can be also contre-intuitive (while intuitively all people accept it). Imagine that some property P is true for only elements in U, and always false for elements in X. In such case you get these ghosts lke Banach-Tarski paradox...

yossell

Jul7-10, 06:32 AM

Some strings define real numbers. For example,

4.5555
pi
min root of the following equation: ... some latex code...

As any string is a word in finite alphabet, the set of all possible strings is countable, like integers. However, the set or real numbers has the power of continuum.

Is this quite right?

The fact that you include pi suggests that your understanding of `string' allows a string to be countably long. If so, then it is not true that the set of all possible strings is countable, even if the alphabet is finite: the set of all sequences of the two letter alphabet {1, 0} has the power of the continuum.

On the other hand, if we restrict our attention to finite strings, then the set of all finite strings in a finite alphabet *is* indeed countable. Indeed, the set of all finite strings in a *countable* alphabet is countable.

Dmitry67

Jul7-10, 06:46 AM

you can define PI using a finite string: you just dont need to write all digits, you can simple write string

sqrt(12)*sum(k from 0 to inf: (-3**(-k))/(2k+1))

yossell

Jul7-10, 06:58 AM

I see what you're saying now and what construction you're giving - 'string' refers to the two letter symbol `pi' rather than the infinite expansion. So the strings are finite.

I don't want to derail this thread - but I thought using the notion of definability without indexing it to a language ('definability-in-L', with this concept being part of the metalanguage) lead to paradoxes.

DrChinese

Jul7-10, 11:33 AM

DrC, two questions,
1) Do you agree that "fair sampling" assumptions exist, irrespectively of validity, that does not involve the assumption that photon detection efficiencies are less than perfect?
2) Do you agree that averaged over all possible settings, not just a choice some subset of settings, that the QM and classical correlation limit leads to the same overall total number of detections?

The Fair Sampling Assumption is: due to some element(s) of the collection and detection apparati, either Alice or Bob (or both) did not register a member of an entangled photon pair that "should" have been seen. AND FURTHER, that photon, if detected, was one which would support the predictions of local realism and not QM. The Fair Sampling concept makes no sense if it is not misleading us.

It is not the Fair Sampling Assumption to say that the entire universe is not sampled. That is a function of the scientific method and applies to all experiments. Somewhat like saying the speed of light is 5 km/hr but that experiments measuring the usual value are biased because we chose an unfair day to sample. The requirement for science is that the experiment is repeatable, which is not in question with Bell tests. The only elements of Fair Sampling that should be considered are as I describe in the paragraph above.

So I think that is a YES to your 1), as you might detect a photon but be unable to match it to its partner. Or it might have been lost before arriving at the detector.

For 2), I am not sure I follow the question. I think QM and LR would make the same predictions for likelihood of detection. But I guess that to make the LR model work out, you have to find some difference. But no one was looking for that until Bell tests started blowing away LR theories.

DrChinese

Jul7-10, 11:51 AM

my_wan

Jul7-10, 04:05 PM

I really really don't get the equivocation in your responses, unless it's to intentionally maintain a conflation. I'll demonstrate:
(Going to color code sections of your response, and index my response to those colors.)

The Fair Sampling Assumption is: due to some element(s) of the collection and detection apparati, either Alice or Bob (or both) did not register a member of an entangled photon pair that "should" have been seen. AND FURTHER, that photon, if detected, was one which would support the predictions of local realism and not QM. The Fair Sampling concept makes no sense if it is not misleading us.
{RED} - The question specifically avoided any detection failures whatsoever. It has no bearing whatsoever on the question, but ok. Except that you got less specific in blue for some reason.
{BLUE} - Here when you say "would support", by what model would the "would support" qualify? In fact one of the many assumptions contained in "would support" qualifier involves how you chose define the equivalence of simultaneity between two spatially separated time intervals. Yet with "would support" you are tacitly requiring a whole range of assumptions to be the a priori truth. It logically simplifies to the statement: It's true because I chose definitions to make it true.

It is not the Fair Sampling Assumption to say that the entire universe is not sampled. That is a function of the scientific method and applies to all experiments. Somewhat like saying the speed of light is 5 km/hr but that experiments measuring the usual value are biased because we chose an unfair day to sample. The requirement for science is that the experiment is repeatable, which is not in question with Bell tests. The only elements of Fair Sampling that should be considered are as I describe in the paragraph above.
{RED} - But you did not describe any element in the paragraph above. You merely implied such elements are contained in the term "would support", and left it to our imagination that since "would support" defines itself to contains proper methods and assumptions, and that "would support" contains it's own truth specifier, then it must be valid. Intellectually absurd.

So I think that is a YES to your 1), as you might detect a photon but be unable to match it to its partner. Or it might have been lost before arriving at the detector.
{RED} - I did not specify "a" partner was detected. I explicitly specified that BOTH partners are ALWAYS detected. Yet that still doesn't explicitly require the timing of those detections to match.
{BLUE} - Note the blue doesn't specify that the detection of the partner photon didn't fail. I explicitly specified that this partner detection didn't fail, and that only the time window to specify it as a partner failed.

So granted, you didn't explicitly reject that both partners were detected, but you did explicitly input interpretations which were explicitly defined not to exist in this context, while being vague on the both partner detections with correlation failures.

So, if I accept your yes answer, what does it mean? Does it mean both partners of a correlated pair can be detected, and still not register as a correlation? Does it mean you recognized the truth in the question, and merely chose to conflate the answer with interpretations that is by definition are invalid in the stated question, so that you can avoid an explicitly false answer while implicitly justifying the conflation of an an entirely different interpretation that was experimentally and a priori defined to be invalid?

I still don't know how to take it, and I think it presumptuous of me to assume a priori that "yes" actually accepts the question as stated. You did after all explicitly input what the question explicitly stated could not possibly be relevant, and referred to pairs in singular form while not acknowledging the success of the detection of both photons. This is a non-answer.

For 2), I am not sure I follow the question. I think QM and LR would make the same predictions for likelihood of detection. But I guess that to make the LR model work out, you have to find some difference. But no one was looking for that until Bell tests started blowing away LR theories.
True, I clearly and repeatedly, usually beginning with "Note", clarified that it did not in any way demonstrate the legitimacy of any particular LR model. All it does is demonstrate that, even if photon detection efficiency is 100%, then a model that only involves offsets in how the photon detection pairs are correlated need not result in excess or undercount of total photon detections. It was specifically designed, and failed, as an attempt to invalidate a "fair sampling" argument when that "fair sampling" argument did not involve missing detections.

There may be, as previously noted, other ways to rule out this type of bias. By recording and comparing the actual time stamps of the uncorrelated photon detections, then, if this is happening, the time window spread between near correlated photon pairs should statistically appear to increase as the angle difference was increased. If pairs of uncorrelated detections were truly uncorrelated, then there should be no statistical variance in the timing of the pairs of time stamps. The assumption that they are correlated, even when not measured to be so, is what would make such a statistical variance possible. May be worth investigating experimentally. Pre-existing raw data might be sufficient, depending on whether time stamps were recorded, or merely hit/misses recorded.

DrChinese

Jul7-10, 05:03 PM

There may be, as previously noted, other ways to rule out this type of bias. By recording and comparing the actual time stamps of the uncorrelated photon detections, then, if this is happening, the time window spread between near correlated photon pairs should statistically appear to increase as the angle difference was increased. If pairs of uncorrelated detections were truly uncorrelated, then there should be no statistical variance in the timing of the pairs of time stamps. The assumption that they are correlated, even when not measured to be so, is what would make such a statistical variance possible. May be worth investigating experimentally. Pre-existing raw data might be sufficient, depending on whether time stamps were recorded, or merely hit/misses recorded.

That is actually what I want to do in order to demonstrate the difficulties involved with the Unfair Sampling Hypothesis. There should be a pattern to the bias if it is tenable.

The time stamps are recorded at each station whenever a detection is made. There are 2 detectors for Alice and 2 for Bob, 4 total. That way there is no question. I have actual data but it is in raw form. I expect it will be a while before I have much to share with everyone.

In the meantime, I can tell you that Peter Morgan has done a lot of analysis on the same data. He has not looked for that specific thing, but very very close. He analyzed delay characteristics for anomalies. There were some traces, but they were far far too weak to demonstrate a Fair Sampling issue. Peter has not published his result yet, as I recall.

DrChinese

Jul7-10, 05:11 PM

{RED} - The question specifically avoided any detection failures whatsoever. It has no bearing whatsoever on the question, but ok. Except that you got less specific in blue for some reason.
{BLUE} - Here when you say "would support", by what model would the "would support" qualify? In fact one of the many assumptions contained in "would support" qualifier involves how you chose define the equivalence of simultaneity between two spatially separated time intervals. Yet with "would support" you are tacitly requiring a whole range of assumptions to be the a priori truth. It logically simplifies to the statement: It's true because I chose definitions to make it true.

If there are no detection failures, then where is the sampling coming into play? You have detected all there are to detect!

As to the supporting idea: obviously, if there is no bias, then you get the same conclusion whether you look at the sample or the universe. If you push LR, then you are saying that an unusual number of "pro QM" pairs are detected and/or an unusual number of "pro LR" pairs are NOT detected. (Except that relationship varies all over the place.) So I guess I don't see what that has to do with assumptions. Just seems obvious that there must be a bias in the collection if the hypothesis is to be tenable.

billschnieder

Jul7-10, 05:23 PM

By recording and comparing the actual time stamps of the uncorrelated photon detections, then, if this is happening, the time window spread between near correlated photon pairs should statistically appear to increase as the angle difference was increased. If pairs of uncorrelated detections were truly uncorrelated, then there should be no statistical variance in the timing of the pairs of time stamps. The assumption that they are correlated, even when not measured to be so, is what would make such a statistical variance possible. May be worth investigating experimentally. Pre-existing raw data might be sufficient, depending on whether time stamps were recorded, or merely hit/misses recorded.

Some work has been done towards this, and the results appear to support your suspicion. See Appendix A of this paper (starting at page 19 http://arxiv.org/abs/0712.2565, J. Phys. Soc. Jpn. 76, 104005 (2007))

DrChinese

Jul7-10, 05:49 PM

Some work has been done towards this, and the results appear to support your suspicion. See Appendix A of this paper (starting at page 19 http://arxiv.org/abs/0712.2565, J. Phys. Soc. Jpn. 76, 104005 (2007))

We are all working off the same dataset and this is a very complicated subject. But there is not the slightest evidence that there is a bias sufficient to account for a LR result. So, no, there is no basis - at this time - for my_wan's hypothesis. However, it is my intent to document this more clearly. As I mention, it is very complicated and not worth debating without going through the whole process from start to finish. Which is a fairly massive project.

All of the teams looking at this are curious as to whether there might be a very small actual bias. But if it is there, it is small. But any at all could mean a potential new discovery.

my_wan

Jul7-10, 06:03 PM

If there are no detection failures, then where is the sampling coming into play? You have detected all there are to detect!
Oh, so I was fully justified in thinking I was being presumptuous in taking your "yes" answer at face value.

Whether or not a coincidence is detected is independent of whether or not a photon is detected. Coincidence detection is wholly dependent on the time window, while photon detection is dependent only on detecting the photon at 'any' proper time. Thus, in principle, a correlation detection failure can occur even when both correlated photons are detected.

This is a bias, and qualifies as a "fair sampling" argument even when 100% of the photons are detected.

As to the supporting idea: obviously, if there is no bias, then you get the same conclusion whether you look at the sample or the universe. If you push LR, then you are saying that an unusual number of "pro QM" pairs are detected and/or an unusual number of "pro LR" pairs are NOT detected. (Except that relationship varies all over the place.) So I guess I don't see what that has to do with assumptions. Just seems obvious that there must be a bias in the collection if the hypothesis is to be tenable.
Again, I am specifically specifying a 100% detection rate. The "bias" is only in the time window in which those detections take place, not the failure of 'photon' detection, a failure of time synchronization to qualify a correlated pair of detections as correlated.

This is to illustrate the invalidity of applying empirical invalidity of one type of "fair sampling" bias to all forms of "fair sampling" bias. It's not a claim of a LR solution to BI violations. It may be a worthy investigation though, because it appears to have empirical consequences that might be checked.

Any number of mechanisms can lead to this, such as the frame dependence of simultaneity, a change in the refractive index of polarizers as the angle changes relative to a photons polarization, etc. The particular mechanism is immaterial to testing for such effects, and immaterial to the illegitimacy of assuming the lack of legitimacy of missing photon detections automatically rule out missing correlation detections even when both photon detections are recorded. Missing a time window to qualify as a correlation detection is an entirely separate issue from missing a photon detection.

That is actually what I want to do in order to demonstrate the difficulties involved with the Unfair Sampling Hypothesis. There should be a pattern to the bias if it is tenable.

The time stamps are recorded at each station whenever a detection is made. There are 2 detectors for Alice and 2 for Bob, 4 total. That way there is no question. I have actual data but it is in raw form. I expect it will be a while before I have much to share with everyone.

In the meantime, I can tell you that Peter Morgan has done a lot of analysis on the same data. He has not looked for that specific thing, but very very close. He analyzed delay characteristics for anomalies. There were some traces, but they were far far too weak to demonstrate a Fair Sampling issue. Peter has not published his result yet, as I recall.
This is interesting, and a logical next step for EPR issues. I haven't got such raw data. Perhaps, if the statistical signature is too weak, better constraints could be derived by a variance across various specific settings. The strongest correlations should occur the nearer the two detector settings are the same, but must differ some, in the ideal case, to get uncorrelated photon detection sets to compare. The variance of 'near hit' time stamps should increase as the relative angle increases. It would be useful to rule this out, but invalidating a fair sampling bias that involves missing detections doesn't do it. It still falls withing the "fair sampling" class of models, which is the main point I wanted to make.

DevilsAvocado

Jul8-10, 10:48 AM

You could see it this way. You could also see it as the very tricky nature then has to be wobbling between "increasing/decreasing" unfair sampling, which to me makes the argument for fair sampling even stronger...

So true. Seems sorta strange to suggest that some photons are over-counted and some are under-counted... and that depends on the angle between. And whether they support LR or QM as to whether they are over or under counted.

Physically it's exactly equivalent to a tennis ball being bounced off a wall taking a longer route back as the angle it hits the wall increases. It only requires the assumption that the more offset a polarizer is the longer it takes the photon to tunnel through it. Doesn't really convince me either without some testing, but certainly not something I would call nature being tricky. At least not any more tricky than even classical physics is known to be at times. Any sufficiently large set of dependent variables are going to be tricky, no matter how simple the underlying mechanisms. Especially if it looks deceptively simple on the surface.

my_wan & DrChinese, wouldn’t a very simple (almost silly) way of ruling out all these questions around the possible 'weaknesses' in the setup (angles / time window / etc), be to run one tests with not entangled pairs?

If there’s something 'wrong', the same biases must logically show for 'normal' photons also, right...??

(And if I’m right – this has of course already been done.)

DevilsAvocado

Jul8-10, 11:25 AM

The De Raedt simulation is an attempt to demonstrate that there exists an algorithm whereby (Un)Fair Sampling leads to a violation of a BI - as observed - while the full universe does not (as required by Bell).

I have only done a Q&D inspection of the code, and I’m probably missing something here, but to me it looks like angle2 is always at a fixed (user) offset to angle1:

angle2 = angle1 + Radians(Theta) ' fixed value offset always

Why? It would be fairly easy to save two independently random angles for angle1 & angle2 in the array for result, and after the run sort them out for the overall statistics...

Or, are you calling the main function repeatedly with different random values for argument Theta...? If so, why this solution...?

Or, is angle2 always at a fixed offset of angle1? If so, isn’t this an extreme weakness in the simulation of the "real thing"??

my_wan

Jul8-10, 11:37 AM

my_wan & DrChinese, wouldn’t a very simple (almost silly) way of ruling out all these questions around the possible 'weaknesses' in the setup (angles / time window / etc), be to run one tests with not entangled pairs?

If there’s something 'wrong', the same biases must logically show for 'normal' photons also, right...??

(And if I’m right – this has of course already been done.)
There may be ways to check specific mechanisms, like refractive index, but in this case the bias is not presumed to miss any photon detections. The only bias is in the time window that determines whether we define two correlated photons to be correlated or not. Thus the general case, involving how we test correlations, can only be tested with photons we can reasonably assume are correlated.

You might also try passing femtosecond pulses through a polarizer and checking how it effects the spread of the pulse. A mechanism may also involve something similar to squeezed light, which, due to the Uncertainty Principle, maximizes the uncertainty of measurables. The photons with the largest offsets relative to the polarizer may effectively be squeezed more, thus inducing a spread, higher momentum uncertainty, in the output.

Still, a general test must involve correlations, and mechanisms can be investigated once an effect is established. Uncorrelated photon sources may, in some cases, be able to test specific mechanism, but not the general case involving EPR correlation test.

DrChinese

Jul8-10, 11:55 AM

DrChinese

Jul8-10, 12:19 PM

There may be ways to check specific mechanisms, like refractive index, but in this case the bias is not presumed to miss any photon detections. The only bias is in the time window that determines whether we define two correlated photons to be correlated or not. Thus the general case, involving how we test correlations, can only be tested with photons we can reasonably assume are correlated.

You might also try passing femtosecond pulses through a polarizer and checking how it effects the spread of the pulse. A mechanism may also involve something similar to squeezed light, which, due to the Uncertainty Principle, maximizes the uncertainty of measurables. The photons with the largest offsets relative to the polarizer may effectively be squeezed more, thus inducing a spread, higher momentum uncertainty, in the output.

Still, a general test must involve correlations, and mechanisms can be investigated once an effect is established. Uncorrelated photon sources may, in some cases, be able to test specific mechanism, but not the general case involving EPR correlation test.

I don't see why you say that uncorrelated sources cannot be used in the general case. I think that should not be an issue, as you can change from uncorrelated to correlated almost at the flip of an input polarizer setting.

DrChinese

Jul8-10, 12:37 PM

I have only done a Q&D inspection of the code, and I’m probably missing something here, but to me it looks like angle2 is always at a fixed (user) offset to angle1:

angle2 = angle1 + Radians(Theta) ' fixed value offset always

Why? It would be fairly easy to save two independently random angles for angle1 & angle2 in the array for result, and after the run sort them out for the overall statistics...

Or, are you calling the main function repeatedly with different random values for argument Theta...? If so, why this solution...?

Or, is angle2 always at a fixed offset of angle1? If so, isn’t this an extreme weakness in the simulation of the "real thing"??

I wanted to graph every single degree from 0 to 90. Since it is a random test, it doesn't matter from trial to trial. I wanted to do X iterations for each theta, and sometimes I wanted fixed angles and sometimes random ones. The De Raedt setup sampled a little differently, and I wanted to make sure that I could see clearly the effect of changing angles. A lot of their plots did not have enough data points to suit me.

my_wan

Jul8-10, 12:55 PM

I don't see why you say that uncorrelated sources cannot be used in the general case. I think that should not be an issue, as you can change from uncorrelated to correlated almost at the flip of an input polarizer setting.

Of course I constantly switch between single beams that are polarized and unpolarized, as well as mixed polarizations, and from polarizer setting to stacked polarizers, to counterfactual assumptions with parallel polarizers, to correlations in EPR setups. Of course you can compare correlated and uncorrelated cases.

The problem is in the correlation case involving variances in time windows to establish such a correlation exist, any corresponding effect in uncorrelated cases is very dependent on the specific mechanism, realistic or not, inducing the time widow offsets in the EPR case. Thus testing time window variances in correlation detections test for the existence of the effect independent of the mechanism inducing such an effect. Testing uncorrelated beam cases can only test very specific sets of mechanism in any given test design. It may be there in the uncorrelated beam case, but I would want to know there was an effect to look for before I went through a myriad of uncorrelated beam test to search for it.

It's not unlike the PEAR group at Princeton deciding that they should investigate the applications of telekinesis without actually establishing such an effect exist. At least non-realist have a real effect to point at, and a real definition to work with. :biggrin:

DrChinese

Jul8-10, 12:59 PM

Oh, so I was fully justified in thinking I was being presumptuous in taking your "yes" answer at face value.

Whether or not a coincidence is detected is independent of whether or not a photon is detected. Coincidence detection is wholly dependent on the time window, while photon detection is dependent only on detecting the photon at 'any' proper time. Thus, in principle, a correlation detection failure can occur even when both correlated photons are detected.

This is a bias, and qualifies as a "fair sampling" argument even when 100% of the photons are detected.

OK, sure, I follow now. Yes, assuming 100% of all photons are detected, you still must pair them up. And it is correct to say that you must use a rule of some kind to do this. Time window size then plays a role. This is part of the experimentalist's decision process, that is true. And in fact, this is what the De Raedt model uses as its exploit.

I don't think there is too much here, but again I have not personally looked at the dataset (I am still figuring out the data format and have been too busy to get that done in past weeks). But I will report when I have something meaningful.

In the meantime, you can imagine that there is a pretty large time interval between events. In relative terms, of course. There may be 10,000 pairs per second, so perhaps an average of 10-100 million picoseconds between events. With a window on the order of 20 ps, you wouldn't expect to have a lot of difficulty pairing them up. On the other hand, as the window increases, you will end up with pairs that are no longer polarization entangled (because they are distinguishable in some manner). Peter tells me that a Bell Inequality is violated with windows as large as 100 ps.

My point being - again - that it is not so simple to formulate your hypothesis in the presence of so many existing experiments. The De Raedt simulation shows how hard this really is.

my_wan

Jul8-10, 02:55 PM

I don't think there is too much here, but again I have not personally looked at the dataset (I am still figuring out the data format and have been too busy to get that done in past weeks). But I will report when I have something meaningful.
I have significant doubts myself, for a myriad of reasons. Yet still having the actual evidence in hand would be valuable. The point in the debate here was the lagitamacy of applying the "fair sampling" no-go based on photon detections to time windows correlation coupling, which is also a form of "fair sampling", i.e., over-generalizing a no-go.

Peter tells me that a Bell Inequality is violated with windows as large as 100 ps.That, I believe, is about a 0.03 cm spread at light speed. I'm also getting a 100 million picosecond average between events, which you need significantly less than that time window to avoid significant errant correlation counts. Still, correlations being effectively washed out beyond 100 ps, about 1 millionth of the average event spread, seems awfully fast. I need to recheck my numbers. What's the wavelength of the light in this dataset?

It might be interesting to consider only the misses in a given dataset, with tight initial time window constraints, and see if a time window shift will recover a non-random percentage of correlations in just that non-correlated subset. That would put some empirical constraints on photon detection timing variances, for whatever physical reason. That correlations would be washed out averaged over enough variation is not surprising, my napkin numbers look a bit awkward.

My point being - again - that it is not so simple to formulate your hypothesis in the presence of so many existing experiments. The De Raedt simulation shows how hard this really is.
Yes it is hard, and interesting. I'm not one to make claims about what De Raedt's simulation actually mean. I'm only warning against presumptions about meaning based on over-generalizations of the constraints we do have, for the very difficulties stated. This was the point of formulating a "fair sampling" argument that explicitly avoided missing photon detections. It wasn't to claim a classical resolution to BI violations, but this caution also applies to the meaning of BI violations.

DevilsAvocado

Jul8-10, 05:49 PM

Pretty much all of these variations are run all the time, and there is no hint of anything like this. Unentangled and entangled photons act alike, except for correlation stats. This isn't usually written up because it is not novel or interesting to other scientists - ergo not too many papers to cite on it. I wouldn't publish a paper saying the sun came up this morning either.

You almost need to run variations with and without entanglement to get the apparatus tuned properly anyway. And it is generally pretty easy to switch from one to the other.

There may be ways to check specific mechanisms, like refractive index, but in this case the bias is not presumed to miss any photon detections. The only bias is in the time window that determines whether we define two correlated photons to be correlated or not. Thus the general case, involving how we test correlations, can only be tested with photons we can reasonably assume are correlated.

Pre-existing raw data might be sufficient, depending on whether time stamps were recorded, or merely hit/misses recorded.

Thanks guys. It looks like the sun will come up tomorrow as well. :smile:

By this we can draw the conclusion that all talk about "unfair angles" is a dead-end. All angles are treating every photon alike, whether it’s entangled or not.

I’ve found this (not peer reviewed) paper that thoroughly examine wide and narrow window coincidences on raw data from EPR experiments conducted by Gregor Weihs and colleagues, with tests on window sizes spanning from 1 ns to 75,000 ns using 3 different rules for identifying coincidences:

http://arxiv.org/abs/0906.5093 (http://arxiv.org/abs/0906.5093)

A Close Look at the EPR Data of Weihs et al
James H. Bigelow
(Submitted on 27 Jun 2009)

Abstract: I examine data from EPR experiments conducted in 1997 through 1999 by Gregor Weihs and colleagues. They used detection windows of 4-6 ns to identify coincidences; I find that one obtains better results with windows 40-50 ns wide. Coincidences identified using different windows have substantially different distributions over the sixteen combinations of Alice's and Bob's measurement settings and results, which is the essence of the coincidence time loophole. However, wide and narrow window coincidences violate a Bell inequality equally strongly. The wider window yields substantially smaller violations of no-signaling conditions.

DevilsAvocado

Jul8-10, 05:59 PM

I wanted to graph every single degree from 0 to 90. Since it is a random test, it doesn't matter from trial to trial. I wanted to do X iterations for each theta, and sometimes I wanted fixed angles and sometimes random ones. The De Raedt setup sampled a little differently, and I wanted to make sure that I could see clearly the effect of changing angles. A lot of their plots did not have enough data points to suit me.

Ahh! That makes sense! Thanks.

my_wan

Jul8-10, 07:01 PM

Thanks guys. It looks like the sun will come up tomorrow as well. :smile:

By this we can draw the conclusion that all talk about "unfair angles" is a dead-end. All angles are treating every photon alike, whether it’s entangled or not.
Not sure what an unfair angle is, but valid empirical data from any angle is not unfair :tongue2:

I’ve found this (not peer reviewed) paper that thoroughly examine wide and narrow window coincidences on raw data from EPR experiments conducted by Gregor Weihs and colleagues, with tests on window sizes spanning from 1 ns to 75,000 ns using 3 different rules for identifying coincidences:http://arxiv.org/abs/0906.5093

A Close Look at the EPR Data of Weihs et al
James H. Bigelow
(Submitted on 27 Jun 2009)

Abstract: I examine data from EPR experiments conducted in 1997 through 1999 by Gregor Weihs and colleagues. They used detection windows of 4-6 ns to identify coincidences; I find that one obtains better results with windows 40-50 ns wide. Coincidences identified using different windows have substantially different distributions over the sixteen combinations of Alice's and Bob's measurement settings and results, which is the essence of the coincidence time loophole. However, wide and narrow window coincidences violate a Bell inequality equally strongly. The wider window yields substantially smaller violations of no-signaling conditions.
Very cool! This is something new to me :!!)

A cursory glance and it's already intensifying curiosity. I don't even want to comment on the information in the abstract until I get a chance to review it more. Interesting :smile:

billschnieder

Jul8-10, 07:54 PM

OK, sure, I follow now. Yes, assuming 100% of all photons are detected, you still must pair them up. And it is correct to say that you must use a rule of some kind to do this. Time window size then plays a role. This is part of the experimentalist's decision process, that is true.

Even if you succeeded in pairing them up, It is not sufficient to avoid the problem I explained in post #968 here: http://www.physicsforums.com/showpost.php?p=2783598&postcount=968

A triplet of pairs extracted from a dataset of pairs, is not guaranteed to be equivalent to a triplet of pairs extracted from a dataset of triples. Therefore, even for a 100% detection with perfect matching of the pairs to each other, you will still not obtain a fair sample, fair in the sense that the terms within the CHSH inequality will correspond to the terms calculated from the experimental data.

I have shown in the above post, how to derive Bell's inequalities from a dataset of triples without any other assumptions. If a dataset of pairs can be used to generate the terms in the inequality, it should be easy to derive Bell's inequalities based only on the assumption that we have a dataset of pairs and anyone is welcome to try to do that -- it is not possible.

my_wan

Jul8-10, 09:49 PM

DrC,
Maybe this will reconcile some incongruencies in my napkin numbers. Is the dataset you spoke of from Weihs et al (1998) and/or (2007)? This would put the time windows in the ns range. The Weihs et al data was drawn from settings that were randomly reset every 100 ns, with 14 ns of data collected in the switching time discarded.

The data, as presented by the preprint DevilsAvocado posted a link to, in spite of justifying certain assumptions about detection time variances, still has some confounding features I'm not clear on yet.

I may have to get this raw data from Weihs et al and put it in some kind of database in raw form, so I can query the results of any assumptions.

DevilsAvocado

Jul9-10, 06:22 AM

Not sure what an unfair angle is, but valid empirical data from any angle is not unfair :tongue2:
Sorry, I meant unfair "tennis ball"... :tongue:

Very cool! This is something new to me :!!)
Yeah! It looks interesting!

I may have to get this raw data from Weihs et al and put it in some kind of database in raw form, so I can query the results of any assumptions.
Why not contact James H. Bigelow (http://www.rand.org/about/people/b/bigelow_james_h.html)? He looks like a nice guy:

http://www.rand.org/about/people/photos/b/bigelow_james_h.jpg

With a dead serious occupation in computer modeling and analysis of large data files, and modeling of training in Air Force fighter pilots! (+ Ph.D. in operations research + B.S. in mathematics)

(= As far as you can get from Crackpot Kracklauer! :rofl:)

DrChinese

Jul9-10, 09:39 AM

Even if you succeeded in pairing them up, It is not sufficient to avoid the problem I explained in post #968 here: http://www.physicsforums.com/showpost.php?p=2783598&postcount=968

A triplet of pairs extracted from a dataset of pairs, is not guaranteed to be equivalent to a triplet of pairs extracted from a dataset of triples. Therefore, even for a 100% detection with perfect matching of the pairs to each other, you will still not obtain a fair sample, fair in the sense that the terms within the CHSH inequality will correspond to the terms calculated from the experimental data.

I have shown in the above post, how to derive Bell's inequalities from a dataset of triples without any other assumptions. If a dataset of pairs can be used to generate the terms in the inequality, it should be easy to derive Bell's inequalities based only on the assumption that we have a dataset of pairs and anyone is welcome to try to do that -- it is not possible.

I re-read your post, and still don't follow. You derive a Bell Inequality assuming realism. Same as Bell. So that is a line in the sand. It seems that should be respected with normal triples. Perhaps if you provide a dataset of triples from which doubles chosen randomly would NOT represent the universe - and the subsample should have a correlation rate of 25%. That would be useful.

DevilsAvocado

Jul9-10, 09:41 AM

... put it in some kind of database in raw form

If you do get your hands on the raw data, maybe you should consider using something that’s a little more "standard" than AutoIt...?

One alternative is MS Visual Studio Express + MS SQL Server Express, which are both completely free. You will get the latest top of the line RAD environment, including powerful tools for developing Windows applications, and extensive help in IntelliSense (autocompletion), etc.

The language in Visual Basic Express has many similarities to the BASIC language in AutoIt.

SQL Server Express is a very powerful SQL DBMS, with the only real limit in the 10GB db size (compared to standard versions).

http://www.chaaps.com/wp-content/uploads/2010/04/VSE20101.png

Microsoft Visual Studio 2010 Express

http://www.microsoft.com/express/s/img/logo_VSE2010.png (http://www.microsoft.com/express/Windows/)

Microsoft SQL Server 2008 R2 Express

http://www.microsoft.com/express/s/img/logo_SQL2008R2.png (http://www.microsoft.com/express/database/)

(P.S. I’m not employed by MS! :wink:)

my_wan

Jul9-10, 10:23 AM

I run MySql (not MS), and Apache with PHP. I used to run Visual Studios (before dot net) and tried the express version. Don't really like it, though it was easy enough to program.

MySql would be fine, and will work with AutoIt, Dos, or PHP.

These days I use AutoIt alot simply because I can rapidly write anything I want, with or without a GUI, and compile or just run the script. It doesn't even have to be installed with an installer. It's functions can do things that takes intense effort working with API's to do in lower level languages, including Visual Studios. I can do things in an hour that would take me weeks in most other languages, and some things I've never figured out how to do in other languages. I've also run it with Linux under wine. Not the fastest or most elegant, but suits my needs so perfectly 99.9% of the time. Effectively impossible to hide source code from any knowledgeable person, but not something that concerns me.

DevilsAvocado

Jul9-10, 02:39 PM

suits my needs so perfectly 99.9% of the time
Okidoki, if you say so.
impossible to hide source code
My thought was to maybe make it easier to show the code to the world, if you find something very interesting... :rolleyes:

billschnieder

Jul10-10, 10:13 PM

You derive a Bell Inequality assuming realism. Same as Bell.
Absolutly NOT! There is no assumption about locality or realism. We have a dataset from an experiment, in which we collected data for three boolean variables x, y, z. That is, each data point consists of 3 values one each for x, y and z, with each value either 1 or 0. We could say, our dataset is (xyzi, i=1..n). Our task is then to derive inequalities which sums of products of pairs extracted from this dataset of triplets must obey. From our dataset we can generate pair products (xy, yz, xz). Note that there is no mention of the type of experiment, it could be anything, a poll in which we ask three (yes,no) question, or the EPR situation. We completely divorce ourselves from the physics or specific domain of the experiment and focus only on the mathematics. Note also, that there is no need for randomness here, we are using the full universe of the dataset to obtain our pair products. We do that and realize that the inequalities obtained are Bell-like. That is all there is to it.

The question then is, if a dataset violates these inequalities, what does it mean? Since there was no physical assumptions in their derivation, violation of the inequalities must mean ONLY that the dataset which violates the inequalities is not mathematically compatible with the dataset used to generate the inequalities.

The example I presented involving doctors and patients, shows this clearly.

Perhaps if you provide a dataset of triples from which doubles chosen randomly would NOT represent the universe - and the subsample should have a correlation rate of 25%. That would be useful.
I'm not sure you understand the point yet. The whole point is to show that any pairs extracted from a dataset of triples MUST obey the inequalities, but pairs from a dataset of just pairs will not! So your request is a bit strange. Do you agree that in Aspect type experiments, no triples are ever collected, only pairs? In other words, each data point consists of only two values of dichotomous variables, not three?

This shows that there is a simple mathematical reason why Bell-type inequalities are violated by experiments, which has nothing to do with locality or "realism" -- ie, Bell's inequalities are derived assuming values per data point (a,b,c), however in experiments only pairs are ever measured (a,b), therefore the dataset from the experiments is not mathematically compatible with the one assumed in Bell's derivation.

So if you are asking for a dataset of pairs which violates the inequalities, I will simply point you to all Bell-test experiments ever done in which only pairs of data points were obtained, which amounts to 100% of them.

Now, you could falsify the above in the following way:
1) Provide an experiment in which triples were measured and Bell's inequalities were violated
2) OR, derive an inequality assuming a dataset of pairs right from the start, and show that experiments still violate it

EDIT:
DrC,
It should be easy for you to simulate this and verify the above to be true since you are a software person too.

DougW

Jul11-10, 12:25 PM

Not to deliberately pull this thread in a different direction, but another thing to consider when discussing whether action at a distance is possible is the effect that multiple universe theory has on this concept.

I'm not an expert, but from what I have gathered about MU is that each time an entanglement is formed, each universe contains a matched set of entangled particles (i.e. in the universe where particle A is produced with spin 'up', entangled particle B will have spin 'down'). Since all possible outcomes are produced in correlation with the probability of the outcome, there will necessarily be universes with each possible 'combination' of entangled pairs. Then when we measure the entangled attributes of one of the particles, we are not actually having any effect on the other entangled particle at all. The 'effect' is local, and is on us, the observer, as we are now cut off from the other universes that contain the other results. So, for example, since we now observe only the universe where particle A has spin 'up', we know that when we observe entangled particle B (or someone else in our observable universe observes particle B and passes the information to us) we will see the complimentary measurement to our observed particle A.

So, in this theory, no spooky action at a distance, just local interaction between the observer and the observed particle, which occurs at lightspeed or slower.

my_wan

Jul11-10, 03:04 PM

Not to deliberately pull this thread in a different direction, but another thing to consider when discussing whether action at a distance is possible is the effect that multiple universe theory has on this concept.
Why consider it? The multiverse is just an ontological construct crafted so as not to actually say anything new (provide any actual physics), that QM doesn't already contain. So if were considering the set of all possible models consistent with QM, for the purposes of BI, then QM already covers this special case. Unless you can say exactly what it entails in terms of BI in a relevant way.

billschnieder

Jul11-10, 06:42 PM

Continuing from my last post, I am posting a simple simulation to illustrate my point. Python code is included.

Note we are trying to calculate the LHS of the following inequality which we will then compare with the RHS:
|ab + ac| - bc \leq 1
At each angle we record the channel (+1 or -1)
Scenario 1: Like in the derivation of Bell's inequality, each data point contains data for three angles a,b,c. Note that here we only only need one data point to calculate the LHS as each point contains all our combinations: In the following code, we iterate through all the possibilities and calculate the maximum value we can attain for the LHS

max_val = -999
for a in (-1,1):
for b in (-1,1):
for c in (-1,1):
v = abs(a*b + a*c) - b*c
if v > max_val: max_val = v
print 'LHS <=', max_val

OUTPUT:
LHS <= 1
As you can see, the inequality is obeyed here.

Scenario 2: Like in Bell-test experiments, each data point consists of only two angles. We therefore need three different data points to be able to calculate the LHS of our inequality, one point in which we collected for (a,b), say (a1, b1), a different one in which we collected for (a, c) say (a2, c2) and yet a different point for which we collected for (b, c), say (b3, c3). We now iterate through all the possibilities and calculate the maximum value we can get for the LHS of our inequalities.

max_val = -999
for a1 in (-1,1):
for b1 in (-1,1):
for a2 in (-1,1):
for c2 in (-1,1):
for b3 in (-1,1):
for c3 in (-1,1):
v = abs(a1*b1 + a2*c2) -b3*c3
if v > max_val: max_val = v
print 'LHS <=', max_val

OUTPUT:
LHS <= 3
Clearly, the second scenario, violates the inequalities!

DougW

Jul12-10, 09:09 AM

Why consider it? The multiverse is just an ontological construct crafted so as not to actually say anything new (provide any actual physics), that QM doesn't already contain. So if were considering the set of all possible models consistent with QM, for the purposes of BI, then QM already covers this special case. Unless you can say exactly what it entails in terms of BI in a relevant way.

Wow, I couldn't disagree more! The idea that you consider 'saying anything new' only as 'providing actual physics' is indicative of the lack of imagination in current physics. I wonder how many of the truly important theories we work with today would have been uncovered if everyone only thought in terms of the already established physics?

Multiple Universe theory is a way of explaining phenomenon, which I had thought was the ultimate goal of physics, and of all science. Take a step beyond the math involved and start asking some questions, such as 'when the quantum wave collapses, where do the virtually infinite number of particles that do not remain go?' Do we believe they never existed in the first place? Or can matter simply stop existing?

When considering how gravity relates to QM, Multiple Universes allows us to consider out-of-the-box ideas such as the relationship of gravity to the probability of change between adjacent universes (or to the amount of information needed to describe those changes). Could gravity be a force that spans multiple universes, and could that help answer some of the questions we have about why gravity doesn't always seem to behave the way we expect?

And, as I mentioned earlier, MU provides a common-sense explanation for the 'action at a distance' question that Einstien first puzzled over, and which has still not been satisfactorily answered.

Go back and read (or re-read) Flatland, and ask yourself the question, 'Should flatlanders limit their thinking to the dimensions in which they are constrained?' Should we then constrain ourselves to thinking only in terms of the physics we can measure? I'd prefer to be able to believe that we can imagine more that we can experience, and if we keep thinking about the larger picture, someone will come up with a way to measure or prove the theories we have that concern parts of existence that currently seem hidden to us.

my_wan

Jul12-10, 12:37 PM

Wow, I couldn't disagree more! The idea that you consider 'saying anything new' only as 'providing actual physics' is indicative of the lack of imagination in current physics. I wonder how many of the truly important theories we work with today would have been uncovered if everyone only thought in terms of the already established physics?
I would call it a lack of imagination to think one particular manner of constructing the ontological format of a theory is special. It's like thinking Engish is a proper language, but not Russian or other language, or that one is right making the other wrong.

Multiple Universe theory is a way of explaining phenomenon, which I had thought was the ultimate goal of physics, and of all science. Take a step beyond the math involved and start asking some questions, such as 'when the quantum wave collapses, where do the virtually infinite number of particles that do not remain go?' Do we believe they never existed in the first place? Or can matter simply stop existing?
The goal of physics is to make phenomena predictable. What constitutes an "explaination" differs from person to person and what they already understand. Personal theories quiet often are not even wrong, they merely locked onto a singular ontological notion to the exclusion of others, like the language example. Your notion of "explaination" is a human or perspective induced construct.

When considering how gravity relates to QM, Multiple Universes allows us to consider out-of-the-box ideas such as the relationship of gravity to the probability of change between adjacent universes (or to the amount of information needed to describe those changes). Could gravity be a force that spans multiple universes, and could that help answer some of the questions we have about why gravity doesn't always seem to behave the way we expect?
Already been done in string theory. But what does it predict? Nothing to date. Many people accuse it of not being physics, but that is technically a premature claim. If they tried to claim it as the standard model, then I would start complaining about the lack of physics it provides.

And, as I mentioned earlier, MU provides a common-sense explanation for the 'action at a distance' question that Einstien first puzzled over, and which has still not been satisfactorily answered.
A common sense explaination of medical verses poisonous plants and compounds in the past was the 'spirit' they contained. A common-sense explanation that provides no physics, but only common-sense explanation, is not science. It leads us back to the dark ages of "explaination". Perhaps, when we learn enough, we can format it in comprehensible ontological constructs. But lagitamacy is not dependent on it, lagitamacy is dependent on empirical predictability.

Go back and read (or re-read) Flatland, and ask yourself the question, 'Should flatlanders limit their thinking to the dimensions in which they are constrained?' Should we then constrain ourselves to thinking only in terms of the physics we can measure? I'd prefer to be able to believe that we can imagine more that we can experience, and if we keep thinking about the larger picture, someone will come up with a way to measure or prove the theories we have that concern parts of existence that currently seem hidden to us.
Another question you can ask, can flatlanders construct a 2D set of force laws that doesn't require adding dimensions outside their experience to "explain" all such effects? A Dimensions is nothing more or less than a coordinate designation, and our laws are generally expressed in coordinate independent formulations these days. It makes meaning go away in many cases because meaning can depend on the choice of coordinates. Yet if two choices of meaning agree with the coordinate independent formulism, they are equivalent, even if they appear to disagree in meaning. There's nothing particularly special in the "meaning" of extra dimensions.

Personally, I like foundational issues. This puts the importance of phenomenology ahead of the formulism. Yet, the empirical validity of the existing formulism must be strictly honored. If I tried to reject a formulism, on the grounds of some ontological twist I claimed as the correct ontology, it would be pure unadulterated crackpottery. Same if I take some pure explaination, lacking any unique empirical consequences, as if it was the one true explaination of things. These considerations may be useful in considering foundational issues, but they aren't uniquely valid, even if they are valid.

Back to EPR....

DrChinese

Jul12-10, 12:51 PM

Absolutly NOT! There is no assumption about locality or realism. We have a dataset from an experiment, in which we collected data for three boolean variables x, y, z. That is, each data point consists of 3 values one each for x, y and z, with each value either 1 or 0. We could say, our dataset is (xyzi, i=1..n). Our task is then to derive inequalities which sums of products of pairs extracted from this dataset of triplets must obey. From our dataset we can generate pair products (xy, yz, xz). Note that there is no mention of the type of experiment, it could be anything, a poll in which we ask three (yes,no) question, or the EPR situation. We completely divorce ourselves from the physics or specific domain of the experiment and focus only on the mathematics. Note also, that there is no need for randomness here, we are using the full universe of the dataset to obtain our pair products. We do that and realize that the inequalities obtained are Bell-like. That is all there is to it.

The question then is, if a dataset violates these inequalities, what does it mean? Since there was no physical assumptions in their derivation, violation of the inequalities must mean ONLY that the dataset which violates the inequalities is not mathematically compatible with the dataset used to generate the inequalities.

The example I presented involving doctors and patients, shows this clearly.

I'm not sure you understand the point yet. The whole point is to show that any pairs extracted from a dataset of triples MUST obey the inequalities, but pairs from a dataset of just pairs will not! So your request is a bit strange. Do you agree that in Aspect type experiments, no triples are ever collected, only pairs? In other words, each data point consists of only two values of dichotomous variables, not three?

This shows that there is a simple mathematical reason why Bell-type inequalities are violated by experiments, which has nothing to do with locality or "realism" -- ie, Bell's inequalities are derived assuming values per data point (a,b,c), however in experiments only pairs are ever measured (a,b), therefore the dataset from the experiments is not mathematically compatible with the one assumed in Bell's derivation.

No, you can show me wrong by an example. Show me the triples, I will pick the doubles randomly. They will have matches of at least 1/3. All sets of triples will have this attribute (considering sample size).

Now, somehow you think it is OK to consider doubles by themselves. Well, that's fine if you are NOT a local realist. I don't think there are well defined values for counterfactual experiments. So I agree that the triples are not viable, and so everything seems fine to me. But you're the one asserting something extra, not me.

DrChinese

Jul12-10, 01:04 PM

billschnieder

Jul12-10, 02:02 PM

Where is the dataset? Why do you hide behind the code? Answer: because you are completely mistaken. The question is NOT about what you are demonstrating above!!

Yes, the first scenario respects the Inequality. That shows the triples. The second is where you go wrong. You must show the matches are less than 1/3 for randomly selected pairs from the first scenario. Oops, you calc something else entirely.

Please take time and read carefully what I am saying here, because I don't think you understand the point yet.

The inequality |ab + ac| - bc <= 1, defines the maximum possible value obtainable. In other words, for every possible combination of values for (a,b,c) attainable within our experiment, that inequality will never be greater than 1.

The code posted, shows that the maximum possible value respects the inequality for the case with 3 values per data point, and violates the inequality for the case with 2 values per data point. This proves my point that a dataset of pairs is not equivalent to a dataset of triples.

So I don't know what you are talking about with respect to 1/3.

billschnieder

Jul12-10, 02:40 PM

No, you can show me wrong by an example. Show me the triples, I will pick the doubles randomly. They will have matches of at least 1/3. All sets of triples will have this attribute (considering sample size).

Now, somehow you think it is OK to consider doubles by themselves. Well, that's fine if you are NOT a local realist. I don't think there are well defined values for counterfactual experiments. So I agree that the triples are not viable, and so everything seems fine to me. But you're the one asserting something extra, not me.

Evidently, you must be trying hard not to understand what I am saying.

The facts are the following:
1) Bell's inequality is derived assuming 3 values per dataset point
2) Bell-test experiments measure 2 values per dataset point
3) Bell-test experiments violate Bell's inequalities

Do you deny any of those facts? Do you know of an experiment in which triples are measured? If your answer is NO, as it should be, then it is mind bogling why you keep asking me to give you a dataset of triples.

The only important question then is:
Why do the experiments violate the inequalities?

Some would say, because the experimental situation is non-local, or not-real as Bell assumed. But my argument here is that there is an entirely mathematical reason why the inequalities are violated it owes to the fact that Bell used triples in his derivation, while actual experiments only measure pairs. The code I posted, demonstrates this, first by showing that the inequalities are indeed valid for triples, then by showing that the inequalities are not valid for pairs. This is clear and simple enough for anyone interested in understanding the argument. You don't have to agree with it to understand it.

And if you do understand it, surely you must see that asking me to provide a dataset of triples so you can randomly pick pairs out of is nonsensical. To calculate the LHS of the inequality you need triples occuring together. Therefore, for a single data point triple (a,b,c), you already have (a,b), (a,c) and (b,c) ocuring together. You don't need any random picking, you can calculate the inequality for each point. My simulation has already shown you that triples obey the inequality; and they should because the inequalities were derived from triples. And note that I considered all posibilities.

Now for a dataset from a real experiment, you only have pairs, therefore to get terms for the inequality, you need three data points.
One data point for which (a,b) occured together, one in which (a,c) occured together and one in which (b,c) occured together. My simulation shows that this scenario violates the inequality just like Bell-test experiments do.

So the conclusion is clear: I have presented a simple mathematical reason why Bell-test experiments in which only pairs are recorded violates Bell inequalities in which triples are assumed.

The onus is no you to provide experimental data in which triples are recorded and Bell's inequality is still violated.

DrChinese

Jul12-10, 02:56 PM

Please take time and read carefully what I am saying here, because I don't think you understand the point yet.

The inequality |ab + ac| - bc <= 1, defines the maximum possible value obtainable. In other words, for every possible combination of values for (a,b,c) attainable within our experiment, that inequality will never be greater than 1.

The code posted, shows that the maximum possible value respects the inequality for the case with 3 values per data point, and violates the inequality for the case with 2 values per data point. This proves my point that a dataset of pairs is not equivalent to a dataset of triples.

So I don't know what you are talking about with respect to 1/3.

I know you don't, and that is MY point. I keep telling you that the requirement is two fold. a) the inequality is respected for the triples, and b) the QM expectation value is met for the doubles. You succeeded with a), not too hard that since it is always true. You ignore b).

On the other hand, you are asserting that there is something which doubles violate every time. I say you are presenting hogwash that is meaningless to this discussion. Show me a dataset of triples. Then surprise me with something about random doubles from that dataset. Because your program isn't doing it for me.

DrChinese

Jul12-10, 03:01 PM

The onus is no you to provide experimental data in which triples are recorded and Bell's inequality is still violated.

Hey, I'm not the one trying to assert there is a local realistic dataset.

P.S. I initially wrote dummy instead of "one" but realized that might be too harsh. :biggrin:

billschnieder

Jul12-10, 08:28 PM

I keep telling you that the requirement is two fold. a) the inequality is respected for the triples, and b) the QM expectation value is met for the doubles. You succeeded with a), not too hard that since it is always true. You ignore b).
You conveniently left out the very important fact that I have already proved the inequality is violated for doubles. If you want to deny that proof just say so, rather than pretend it is not relevant. My interest is to explain the reason for violation of Bell's inequalities by Bell-test experiments. It is a fact that both QM and experiments agree with each other but disagree with Bell. Not surprising, as you yourself acknowledged, both QM and the experiments are working with doubles, and Bell is working with triples. My focus here is to show that this oft neglected detail, results in the violation of Bell-type inequality, due to pure mathematics, without any reference to physical assumptions. I have done that and you do not deny the fact that I have proven this.
I set out to prove that a dataset of triples is not compatible with a dataset of pairs. And I have done that. You do not deny that I have proven this.

On the other hand, you are asserting that there is something which doubles violate every time.
I never said that. I said the inequality is not guaranteed to be obeyed for doubles. If you go back and read what I actually wrote, you will see that the result for doubles was L <= 3 and for triples was L <=1. Clearly, this is not saying doubles violate the inequality "every time" as you misinterpreted, so please look carefully before you jump.
I say you are presenting hogwash that is meaningless to this discussion. Show me a dataset of triples.
Oh it is very relevant: The crucial question I am answering is "Why are Bell-type inequalities violated?" For anyone who is interested in whether action at a distance is a possible conclusion of the EPR paradox, this question is the most important question. Do you deny that?

Your answer to the question, if I may guess your position, is that Bell-type inequalities are violated because either realism or locality or both are false, therefore action at a distance is possible.

My answer to the question, which you are desperately trying to avoid is:
1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by an experiment which only collects pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.

Now if you think my answer is wrong, be specific, about which of the above claims is false, and why it is false. What you can not do is pretend the above is not relevant to the discussion. If you can not be specific about what it is you think is wrong with my answer, it is you who is presenting hogwash.

Then surprise me with something about random doubles from that dataset. Because your program isn't doing it for me.
You still haven't gotten it have you. My program simulates two situations. Scenario 1 is the situation assumed in Bell's derivation, Scenario 2 is the situation actually measured in Bell-test experiments. And they disagree. Of course if you are trying to ignore my argument, you would say "it isn't doing it for me" without actually explaining what aspect of the simulation goes against what is actually measured in Bell-test experiments or assumed in Bell-inequalities.

The whole point of the simulation is to show that the dataset of triples disagrees with the dataset of doubles, thus giving you a framework for comparing Bell's inequalities (the dataset of triples) with Bell-test experiments (the dataset of doubles). The code presented showed both scenarios.

Now you must understand why asking me to give you a dataset of triples which disagrees with Bell and agrees with QM is nonsensical. Again in case you still do not understand, the whole point of the argument and the simulation is to show that Bell agrees with the triples but disagrees with the doubles, get it?

EDIT:
One thing that my treatment also shows is the following:
For a dataset of triples, Bell's inequality can never be violated, not even by spooky action at a distance! Since my proof does not make any physical assumptions, you can define the physical situation anyway you want, and even include spooky action at a distance and you will never violate Bell's inequality so long as you are dealing with a dataset of triples! In other words, it is mathematically impossible to violate the inequalities for a dataset of triples, irrespective of the physical situation generating the data, whether it is local causality or FTL.

As long as you have a dataset of only pairs, like in Bell-test experiments, all bets are off. What this proves is that Action at a distance is NOT a possible outcome of the EPR paradox.

DrChinese

Jul14-10, 03:57 PM

You conveniently left out the very important fact that I have already proved the inequality is violated for doubles. If you want to deny that proof just say so, rather than pretend it is not relevant. My interest is to explain the reason for violation of Bell's inequalities by Bell-test experiments. It is a fact that both QM and experiments agree with each other but disagree with Bell. Not surprising, as you yourself acknowledged, both QM and the experiments are working with doubles, and Bell is working with triples. My focus here is to show that this oft neglected detail, results in the violation of Bell-type inequality, due to pure mathematics, without any reference to physical assumptions. I have done that and you do not deny the fact that I have proven this.
I set out to prove that a dataset of triples is not compatible with a dataset of pairs. And I have done that. You do not deny that I have proven this.

...

As long as you have a dataset of only pairs, like in Bell-test experiments, all bets are off. What this proves is that Action at a distance is NOT a possible outcome of the EPR paradox.

Interesting that you are taking credit for something that Bell discovered. And yes, I deny that you have proven anything beyond that. Perhaps you can explain the part about "a dataset of triples is not compatible with a dataset of pairs" with an example dataset.

The idea would be that that each triplet a, b, c yields 3 doubles ab, bc, ac. You would merely demonstrate that randomly selected doubles (i.e. 1 double from each triplet) do NOT reflect the universe of all doubles (which is 3 times the size) within statistical parameters. You supply the dataset, I will randomly select.

Oh wait, we've been through this before. There is no such dataset of triplets. And you won't submit one for inspection. And yet, you claim to have PROVED there is!!

What gives?? :tongue:

billschnieder

Jul14-10, 05:50 PM

You probably missed this part, here it is again:

My Claims:
1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by an experiment which only collects pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.

Now if you think my answer is wrong, be specific, about which of the above claims is false, and why it is false.

...

For a dataset of triples, Bell's inequality can never be violated, not even by spooky action at a distance!

If you are interested in being specific, address these points and we can talk.

Bonge

Jul16-10, 04:21 AM

We have to agree that after EPR it seems that Space-Time itself is more clearly than ever an illusion on the quantum level.
The interesting thing is that if we link this absurd behavior to our other theories of QED you will find that in fact all light, electrons, quarks u and d, Ws, Photons etc, are in fact really being defined by their behaviour in time, aside from the time aspect of their rotational rate/ wavelength of amplitude etc the only characteristic of these subatomic entities that exists differently is their weight!
And based on special relativity wee can safely assume some sort of relativistic weight, especially when considering the nature of time itself on these particles.
In conclusion to this highly concise point, I believe that it is impossible to refute that in fact everything is the same, and I don't just mean entangled since the big bang, but in fact all particles are inherently the same thing, none are different just because of the fact that in the absurd world of quantum physics it is impossible to prove any of this to the contrary.
Until we know more, we just have to assume that Higgs particle is a quantum black hole caused b the dense weight of the subatomic particles in every atom! In fact all EPR speaks of worm-holes between all aspects of physicality, linking them at rates faster than the speed of TIME (and obviously light) and in fact if all of the space-time continuum is a web of wormholes linking every quantum of physicality then we must conclude that TIME as we experience it is an illusion, and so to is SPACE.
Is it impossible to suggest that the whole universe is infinitessimally small based on the web of entangled worm-holes? Well One thing we know is that nothing is too absurd to consider - so consider this!
The same way that the internet links the whole world's information on a web of a different proprietary nature to the information itself, but we know that it works and makes data available throughout the Earth at rates much faster than DHL can send it because of the short-cuts, so just go a step further to understand my hypothesis, if the ADSL broadband internet wires were worm holes, then the whole universe could be linked, and just like the internet is big in its transport ability but tiny in it's physical hardware size because all it needs to be is the P2P cable, so too this worm-hole web can be of ZERO SIZE.
Finally, it is very easy to presume that the laws of physics in a worm hole are different to the ones we observe, and C-the speed of light can certainly be much faster even if the size of the WHW (worm-hole-web) is not infinitessimally small.

Thanks
THoughts?

unusualname

Jul16-10, 08:06 AM

DougW

Jul16-10, 09:10 AM

^^ It's no good trying to derail this thread with wild flights of fancy, I already tried that tactic way back on page 17 or so :wink: :smile:

btw, the answer to the OP's question is, according to modern consensus, yes, action at a distance is possible as envisaged by the EPR Paradox.

(There is a minority who maintain otherwise)

Again, action at a distance is only 'possible' if you believe that you as the observer can not be affected. Multiple Universe allows that all of the 'action' taking place is local. When the observer measures the particle on one end of the entanglement the information they obtain changes their relationship with the multiverse...a local action which occurs at lightspeed. At that moment, the only version of the second particle of the entanglement that they can interact with is the one which corresponds with the first particle measured.

Think about it this way. Does donning a pair of polarized sunglasses send a messsage to a distant lightsource telling it to only emit light with a particular polarization? That would also be considered 'spooky action at a distance'. But, of course, with this example, we easily accept that the action is local, that we are filtering out some of the light from reaching our eyes. But, change the subject ever so slightly, and people find it difficult to make the next step. We can't imagine how 'information' can be filtered in this way. As Deustch has pointed out, we can see, and even measure, the effects of particles that clearly do not 'exist' in our universe the way we have always understood existence. Then after a measurement, we also can clearly see that our ability to measure these particles is gone. Did the particles stop existing, or is perhaps the information about these particles simply filtered from our senses?

my_wan's earlier insult to the MU theory notwithstanding (comparing it to 'spirits' in plants? Really? That is wrong on so many levels...), this theory actually causes fewer 'problems' with our understanding of classic physics that any other 'theory of everything' that has been proposed so far. Is it being rejected because it diminshes us phycologically (i.e. how important am I if there might be a near-inifinite number of copies of 'me' out there)?

Anyway, perhaps action at a distance hasn't been disproven, but it is a long way from proven.....

DrChinese

Jul16-10, 10:06 AM

You probably missed this part, here it is again:

3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples

If you are interested in being specific, address these points and we can talk.

I think I have asked every way possible. Show me an example of your 3). A dataset. DATA SET. D A T A S E T. Set du data.

I don't understand how 2 values alone are made to violate an inequality (as you claim), but I guess your example will show that. Of course, I don't actually expect you to produce anything remotely approaching your baseless claims.

QM predicts values for doubles, but does not predict anything for triples. For 120 degrees separated a, b, c that is a correlation rate of .25. You cannot come closer than .33 when I randomly select doubles from your triples.

Or consider this dataset:

a b
+ +
+ -
- +
+ -

Gosh, that is a correlation rate that matches QM's expectation .25. Notice how there is no c. Let's add c.

a b c
+ + -
+ - +
- + -
+ - -

ab=.25. But looky here: bc=.25 and ac=.50. Oops, an average of... .33. Just as I said. In a true experiment, there are no streams with .50. They are all .25. Come on bill, you know all this already. Now, how does nature manage to hide the ac stream from us all the time? THERE IS NO c!

unusualname

Jul16-10, 10:06 AM

A
Anyway, perhaps action at a distance hasn't been disproven, but it is a long way from proven.....

You can say that about every theory in science. :smile:

This particular "theory" allows for a lot of (so called) philosophical discussion because it's not known how the non-local mechanism works.

At the boundary of scientific knowledge you always get philosophical speculation and muddled analysis, which often looks silly with historical hindsight.

I'll be happy when string theory or some other higher dimensional model finally gives a convincing explanation for the non-local mechanism, but we'll just have to wait a little longer.

billschnieder

Jul16-10, 03:07 PM

Or consider this dataset:

a b
+ +
+ -
- +
+ -

No! Can you calculate the expression |ab + ac| - bc from that?
You still have not understood anything in my argument, nothing at all. So let me break it down for you.

(a,b,c) should refer to angles which Alice and Bob are allowed to change between at random, just like in a real Bell-test experiment. So the dataset from an experiment consists of two columns, 1 for Alice and 1 for Bob as follows:
(a=1, b=-1) ie, Alices angle was a and she got +1, Bobs angle was b and he got -1
(c=1, b=1) ie,Alices angle was c and she got +1 Bobs angle was b and he got 1
...
(b=-1, a=-1)

Each row contains 2 values, 1 for Bob and 1 for Alice, in other words, each data point is a pair. This is the meaning of a dataset of pairs. It doesn't mean you have only two angles in the whole dataset as you mistakenly thought. It means only two angles are collected at a time, get it?

Therefore, to calculate |ab + ac| - bc, you have to calculate the three terms just like they do for Bell-test experiments as follows
ab - look for a row in which Alice's angle was [a] and Bob's was [b] and multiply what they got
ac - look for a row in which Alice's angle was [a] and Bob's was [c] and multiply what they got
bc - look for a row in which Alice's angle was [b] and Bob's was [c] and multiply what they got

Again, now you hopefully understand that, there are three angles involved even if we have just a dataset of pairs. So the above is how Bell-test experiments proceed which is one part of my simulation and we got the valid inequality to be

|ab + ac| - bc <= 3

Now on to the part which covers Bell's derivation:
Bell assumes that there are values existing for three angles (a,b,c). So the dataset from an experiment consists of three columns, 1 for Alice and 1 for Bob as follows, plus a mythical Jane, ie, what Jane would have observed if she had measured at the same time as Alice and Bob. This is what you and JesseM have been calling the "realism assumption":
(a=1, b=-1, c=+1) ie, Alices angle was a and she got +1, Bobs angle was b and he got -1, Janes angle is c and she got +1
etc.
This is a dataset of triples.

Therefore, to calculate |ab + ac| - bc, you have to calculate the three terms just like Bell did. You already have all three combinations ab, ac and bc within a single data point of Bell's assumed dataset so for each point you just
ab - multiply the angle [a] outcome with the angle [b] outcome
ac - multiply the angle [a] outcome with the angle [c] outcome
bc - multiply the angle [b] outcome with the angle [c] outcome

So the above is how Bell's inequality is derived, and we do the simulation and indeed it confirms Bell's inequality

|ab + ac| - bc <= 1

There is 'c' in both scenarios, they both deal with 3 angles. The difference is, one is a dataset of pairs the other is a dataset of triples. I can not make it any easier than this. If you still do not understand this, you are on your own.

DrChinese

Jul16-10, 03:26 PM

There is 'c' in both scenarios, they both deal with 3 angles. The difference is, one is a dataset of pairs the other is a dataset of triples. I can not make it any easier than this. If you still do not understand this, you are on your own.

After all this, still no dataset.

Yours are some of the dopiest responses I can seriously imagine. So either you are one of the 5 smartest people in the world (since there are probably 4 more who agree with you) or you need to go hide in a cave until you see what is being asked.

And I was on my own long before you showed up! :rofl:

DrChinese

Jul16-10, 05:26 PM

For those following this discussion, billschnieder is basically addressing this question:

For a stream of particles, we'll call them Alice, does Alice have well defined polarization values for angle settings a=0, b=120 and c=240 degrees which match the QM expectation value of .25?

EPR says YES, Alice does, unless you unreasonably require this to be proven by simultaneous prediction of those values. Their explanation is that since a, b OR c can be predicted (but not all simultaneously), that should be adequate as proof. You can predict a, b or c of course by first observing Alice's twin partner, Bob.

Now the reason I choose the angle settings I did for a, b and c is that allows me to construct a very simple dataset to test for Alice, and then compare to the QM expectation value. Assuming 4 photons in Alice's stream (to get us started):

a b c
+ + -
+ - +
- + -
+ - -

So the above would be possible realistic values per EPR. I made these up, in an attempt to provide values that would be as close as possible to the Quantum Mechanical predictions. Obviously, 4 is way too few to be rigorous but yet is sufficient to discuss. So let's consider what Alice's twin Bob would look like:

a b c
+ + -
+ - +
- + -
+ - -

I.e. the same as Alice. So suppose we compare all the permutations of observing Alice and Bob at different angle pairs ab, bc, and ac. What would we see? And the answer is that even for as few as 4 items, it is not possible to get closer than a 33% average correlation rate.

ab=.25
bc=.25
ac=.50
------
average=.333333

QM would predict 25%, i.e. cos^2(theta=120 degrees). Obviously, you would have a standard deviation which is too large to be meaningful for this few items. But in a larger sample the actual experimentally observed value is in fact 25%. Using the EPR logic, something is clearly wrong.

Bill's argument has something to do with 3 observers and either 2 or 3 attributes (I am not really sure which). But the actual question is whether 1 particle has 3 well defined values. If 1 does, then 2 do too. And that is what is being considered in Bell tests. Whenever you question this point, simple consider that EPR is saying:

Alice stream =
a b c
+ + -
+ - +
- + -
+ - -

Bob stream =
a b c
+ + -
+ - +
- + -
+ - -

On the other hand, QM goes no farther than this:

Alice stream =
a b
+ +
+ -
- +
+ -

Bob stream =
a b
+ +
+ -
- +
+ -

Which matches QM just fine.

DevilsAvocado

Jul16-10, 06:07 PM

... you need to go hide in a cave ...

... Maybe we should hint billschnieder that Crackpot Kracklauer has lots of rooms for rent in his poco-loco cave ... AFAICT, very private and excellent for deep contemplation regarding the proposed schizophrenic nature of wave functions (!:bugeye:?), and exactly how quantum mechanics may be involved in abortion (!:bugeye:?).

:rofl:

DevilsAvocado

Jul16-10, 06:35 PM

For those following this discussion, billschnieder is basically addressing this question: ...

Great explanation DrC. Now... I just wonder... how billschnieder is going to mess-up this beautiful and simple explanation...? Huh? Maybe some "chains" of probability? Maybe some hilarious (Monty) Python code? Or maybe a groundless personal attack??

I’m going for the later: billschnieder are now going to accuse you for not answering his question, and writing too looooooooong posts (that takes hours for him to understand) about the totally wrong subject, and you are doing all these "bad things" just to avoid the fact that billschnieder is right and have proven a sensational fact that nobody knew before.

Let’s see... :grumpy:

DevilsAvocado

Jul16-10, 08:25 PM

... In fact all EPR speaks of worm-holes between all aspects of physicality, linking them at rates faster than the speed of TIME

Que? Speed of TIME ?:bugeye:?

The same way that the internet links the whole world's information on a web of a different proprietary nature to the information itself, but we know that it works and makes data available throughout the Earth at rates much faster than DHL can send it because of the short-cuts, so just go a step further to understand my hypothesis, if the ADSL broadband internet wires were worm holes, then the whole universe could be linked, and just like the internet is big in its transport ability but tiny in it's physical hardware size because all it needs to be is the P2P cable, so too this worm-hole web can be of ZERO SIZE.

Look, there are no ADSL-worm-holes-short-cuts on the internet. Just digital information transferred close to the speed of light. And I can guarantee you that if you were to collect all the hardware that makes up the internet infrastructure – it would not be "tiny". And there are no "P2P cables" (peer-to-peer), just twisted-pair cables (Cat-5, Cat-5e, Cat-6, etc), and these cables are not the internet, since they only work properly on distances < 100 meters (= LAN).

Internet is a hardware and software infrastructure that provides connectivity between computers.

http://i32.tinypic.com/vigzyw.jpg

THoughts?

I admire your imagination, but I doubt this has anything to do with real science...

DevilsAvocado

Jul16-10, 08:53 PM

... my_wan's earlier insult to the MU theory

There is no such thing called the "MU theory", unless you just made it up. Are you talking about the Many-worlds interpretation (MWI), or the Ultimate Ensemble hypothesis?

I hope you do know the difference between theory/hypothesis/interpretation?

DevilsAvocado

Jul17-10, 07:31 AM

... Yours are some of the dopiest responses I can seriously imagine. So either you are one of the 5 smartest people in the world (since there are probably 4 more who agree with you) or you need to go hide in a cave until you see what is being asked.

I wish billschnieder would read and understand this quote:

"One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision." -- Bertrand Russell

billschnieder

Jul17-10, 08:55 PM

For those following this discussion, billschnieder is basically addressing this question:
...

This is bait-and-switch. Those following the discussion know exactly what I am addressing which is different from your misrepresentation of my position.

The question I am addressing is the clearly the following:
"Is action at a distance a possible conclusion from Bell's inequalities and the results of Bell-test experiments?"
In other words,
"Why are Bell's inequalities violated by Bell-test experiments, and what can we conclude from this violation?"

My answer to the above question can be summarized in the following points which remain unchallenged:
1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!

Now if anyone thinks my answer is wrong, be specific, about which of the above claims is false, and why it is false.

Here are the detailed explanations:
Claim 1: Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
We have three binary variables (x, y, z) (ie, each can have a value of 0 or 1 and such that \overline{x} = 1 - x)
For our three variables, the triple products of all possible combinations must obey the following equation:

1 = \overline{xyz}+x\overline{yz}+x\overline{y}z+\over line{x}y\overline{z}+xy\overline{z}+\overline{xy}z +\overline{x}yz + xyz

We can then group the terms as follows so that each group in parentheses can be reduced to products of only two variables.

1 = \overline{xyz}+(x\overline{yz}+x\overline{y}z)+(\o verline{x}y\overline{z}+xy\overline{z})+(\overline {xy}z+\overline{x}yz) + xyz

Performing the reduction, we obtain:

1 = \overline{xyz}+(x\overline{y})+(y\overline{z})+(\o verline{x}z) + xyz

Which can be rearranged as:

x\overline{y}+y\overline{z}+\overline{x}z = 1 - (\overline{xyz} + xyz)

But since the last two terms on the RHS are either 0 or 1, we can write the following inequality:

x\overline{y}+y\overline{z}+\overline{x}z \leq 1

In Bell's treatment, we are interested not in boolean variables of possible values (0,1) but in variables with values (+1, -1). So we define three such two-valued variables (a,b,c), which are simply transformations of our x, y, z as follows: a = 2x - 1 , b = 2y - 1 and c = 2z - 1

Remembering that \overline{x} = 1 - x, and substituting for a, b,c in the above inequality and maintaining on the LHS only terms involving products of pairs, you obtain the following inequality

-ab - ac - bc \leq 1

Replacing a with -a and you obtain the following inequality

ab + ac - bc \leq 1

Combine the above two into the form

|ab + ac| - bc \leq 1

Which is Bell's inequality, except derived without any assumptions about locality or realism. This inequality MUST therefore be obeyed by any three 2-valued variables with possible values, NO MATTER the physical meaning ascribed to them. You could even assume that the three values represent measurements at three different galaxies, with non-local signalling, or even backward signalling between them and it would not make a difference, the inequality MUST still be obeyed. You can verify this by randomly picking three values from the set (-1, +1) and calculate this inequality. It is always obeyed. The only assumption is that we have three such variables, and each one can only have values (-1, or +1).

Claim 2: In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)

Continuing from claim 1, in Bell-test experiments, our three variables (a,b,c) correspond to the 3 angles. Values (-1, +1) correspond to the channels at each arm of the experiment Bob has two channels (-1, +1) and Alice has two channels (-1, +1). An assignment such as (a=-1) means, the photon reached the (-1) channel when measured with the setting at angle (a). To calculate a correlation between two settings (a, b), all we need to do is multiply together the values obtained for that angle.Therefore C(a,b) = ab. To see this, if a=-1, and b=-1, then C(a,b) = 1 which is perfect correlation, but if a=1 and b=-1, C(a,b) = -1 which is perfect anti-correlation.

Prior to the start of the experiment, Alice and Bob are each given the three angles which they are going to randomly switch between. The possible angle combinations are therefore for Alice (first) and Bob (second) are (aa), (ab), (ac), (bb), (ba), (bc), (cc), (ca), (cb). Pairs of photons are then emitted from the source and one heads to Alice, the other to Bob. At each arm, Alice and Bob set their random angle and make a reading which the record down. At the end of the experiment, they meet and tally their results into something as follows:

(c=-1, a=+1)
(b=+1, a=+1)
...

Each row simply corresponds to the results for a single photon pair and contains only two settings even though for the whole experiment they are randomly changing between THREE angles. Therefore their dataset can be called a dataset of pairs. This is how Bell-test experiments are always done. The only insignificant difference in some cases, is when they decide to use FOUR angles rather than three. In that case, a different Bell-type inequality with 4 terms has to be used.

Claim 3: A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
We now have our experimental data of pairs. But since Bell-test experiments are done in order to test Bell's-inequality, we need to calculate the LHS of the inequality (ie |ab + ac| - bc <= 1) using our experimental data. In Bell-test experiments we calculate each of the terms (ab), (ac) and (bc) from our data. However, for each photon pair we only have two angles so we need three data points to be able to calculate all the terms. We calculate (ab) from the data point where the angles chosen at Alice and Bob were (a,b) respectively, and the same for the other two terms. Since we know all the possibilities, that can be realized in an actual experiment, ie, 9 possible angle pairs, each yielding 4 possible value pairs (++, +-, -+, --), we have a total of 36 distinct possible data points for our dataset of pairs. The question then is Is Bell's inequality obeyed for any combination of 3 angles angles extracted from within this dataset of pairs? We can answer this by calculating the LHS of our inequality for all the possibilities. The following Python code does the calculation:

max_val = -999
for a1 in (-1,1):
for b1 in (-1,1):
for a2 in (-1,1):
for c2 in (-1,1):
for b3 in (-1,1):
for c3 in (-1,1):
v = abs(a1*b1 + a2*c2) -b3*c3
if v > max_val: max_val = v
print 'LHS <=', max_val

And it tells us that the inequality is violated, since we obtain |ab + ac| - bc <= 3, instead of |ab + ac| - bc <= 1. This proves that for any dataset involving THREE two-valued variables, but for which you have ONLY pairs of variables per data point, like in Bell-test experiments, the correct inequality is |ab + ac| - bc <= 3 and NOT |ab + ac| - bc <= 1. In other words, for purely mathematical reasons, Bell's inequality is not a valid model for the dataset obtained in Bell-test experiments. The two are mathematically incompatible. This means, violation of Bell's inequality by Bell-type experiments is simply due to a mathematical discrepancy between the meaning of the terms, and not due to anything physical. Which means, even if we assumed spooky action at a distance was in play, Bell-test experiments will still violate Bell's inequality.

Note:
- There is no mention about QM in the above, as the above is valid for purely mathematical reasons, no matter what QM says or does not say. So any counter argument trying to claim that QM says "this" or "that", is moot.
- The above describes what is actually done in Bell-test experiments and the simulation actually generates a dataset. So any counter argument trying to claim that I still need to provide a dataset is moot. Anyone serious bout countering this, can run the code and obtain the dataset.
- The above derives Bell's inequality without any physical assumption, therefore any claim that violation of such inequalities implies anything physical is moot.

So again, for any Bell proponent who thinks I am wrong, point out where exactly and provide a coherent explanation as to why you think the above is wrong.

I'm sure DevilsAvocado with all his Bell expertise will provide a point by point rebuttal which makes sense. I await it.
-----------------------
Brådköp ångerköp

DevilsAvocado

Jul17-10, 09:27 PM

OMG! I’m dying!! I was right!!! (http://www.physicsforums.com/showthread.php?p=2803101#post2803101) DrC didn’t answer the question!!!! This is tooooooooooo much!!!!! HAHAHAH!!!!!! :rofl: :rofl: :rofl: :rofl: :rofl: :rofl:

P.S. Advise to any reader – Don’t bother to run the Monty Python code unless you want a good laugh. There are no initialized variables, and 0*0 is always zero, zip, nada, zilch. HAHAHAHAH!!! :rofl: :rofl:

my_wan

Jul18-10, 04:24 AM

my_wan's earlier insult to the MU theory notwithstanding (comparing it to 'spirits' in plants? Really? That is wrong on so many levels...), this theory actually causes fewer 'problems' with our understanding of classic physics that any other 'theory of everything' that has been proposed so far. Is it being rejected because it diminshes us phycologically (i.e. how important am I if there might be a near-inifinite number of copies of 'me' out there)?
(I'm guessing MU stands for 'Multiple Universe' as in MWI.)

I was not insulting any theory. I was making a factual statement about the value of 'explanation' when that explanation provides absolutely nothing except an interpretation of post-facts.

The MWI is quiet good at supplying a coherent interpretation of QM, and I can't claim it to be factually false. But it is not even a theory, it's an interpretation. Look at it this way: if without QM we were given a complete explanation of the MWI, it would tell us nothing about QM. It includes none of the predictions of QM, much less QM itself. The same cannot be said of the Uncertainty Principle, Born rule, Pauli exclusion principle, etc. It does not add any predictive power to any part of science.

These various interpretations are far from being useless. I'm as interested in them as I am the science, hopefully they'll even help us to extend science. But once you start mistaking interpretation for science it's no better than trying to identify which god blew the volcano. No, this is not an insult to those interpretations, which I think even the most outrageous are quiet valuable. The insult, if any, is reserved for the conflation between theory and interpretation.

Dmitry67

Jul18-10, 05:45 AM

The MWI is quiet good at supplying a coherent interpretation of QM, and I can't claim it to be factually false. But it is not even a theory, it's an interpretation. Look at it this way: if without QM we were given a complete explanation of the MWI, it would tell us nothing about QM. It includes none of the predictions of QM, much less QM itself. The same cannot be said of the Uncertainty Principle, Born rule, Pauli exclusion principle, etc. It does not add any predictive power to any part of science.

I dont agree.
MWI made very important falsifiable prediction - there is no collapse - at any scale.
Experiments with C60, with superconductive rings etc prove it
While collapse theories (CI, TI) are now the history

billschnieder

Jul18-10, 08:13 AM

OMG! I’m dying!!
... of ignorance.
P.S. Advise to any reader – Don’t bother to run the Monty Python code unless you want a good laugh. There are no initialized variables, and 0*0 is always zero, zip, nada, zilch.
Python is free (http://www.python.org/download/), and it takes 1 minute to install and test my code. Anyone with more than one braincell will actually run the code BEFORE triumphantly proclaiming their idiocy with an outburst such as yours

DrChinese

Jul19-10, 01:23 PM

... of ignorance.

...of Dataset. Why program when data is not ambiguous? Ah, because there is no data matching the claim. Otherwise, the programmer would merely execute his program and show us the dataset.

DevilsAvocado

Jul19-10, 02:09 PM

Why program when data is not ambiguous?

OMG! I’m dying x 2!! :rofl: :rofl:

DevilsAvocado

Jul19-10, 04:27 PM

Great explanation DrC. Now... I just wonder... how billschnieder is going to mess-up this beautiful and simple explanation...? Huh? Maybe some "chains" of probability? Maybe some hilarious (Monty) Python code? Or maybe a groundless personal attack??

I’m going for the later: billschnieder are now going to accuse you for not answering his question, ...
This is bait-and-switch. Those following the discussion know exactly what I am addressing which is different from your misrepresentation of my position.
Of course I’m laughing in triumph. I was right!

Only a totally deranged oddball, locked in the Cranky Cave of Grandmaster Crackpot Kracklauer, would repeatedly continue this head-banging lunacy, which we now are experiencing in this and other threads on PF. You have by far driven this brainless "tactic" over the edge of hilarious parody, and I can assure you – I’m not the only one laughing out loud.

Python is free (http://www.python.org/download/), and it takes 1 minute to install and test my code. Anyone with more than one braincell will actually run the code BEFORE triumphantly proclaiming their idiocy with an outburst such as yours

Please Mr. BS, don’t be mad. Once again you have misinterpreted everything about everything. The numeric example "0*0" was not referring to your silly little code, but your brain cells. The recommendation to not even spend even 1 minute on this intellectual fraud still remains solid, because you’re trying to "prove" something that solely exists inside your own crooked head, and not outside, in the real world of balanced and sincere scientists.

The question I am addressing is the clearly the following:
"Is action at a distance a possible conclusion from Bell's inequalities and the results of Bell-test experiments?"

And here we go again. Not even wrong. You’re all over the place with your skewed picture of mainstream science. Deliberately or not, you’re leaving out the most important part in Bell's theorem:
"No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."

Consequently, your "personal theories" is an attack on the predictions of quantum mechanics, more than anything else, and I do hope you truly realize what this means, and how utterly ridiculous 10 lines of iterative Python code are in the light of this fact. That’s why we are all laughing.

But, maybe this oddball "approach" is perfectly "natural" to you, having Crackpot Kracklauer as the one and only guiding "star".
My answer to the above question can be summarized in the following points which remain unchallenged:
1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!

Now if anyone thinks my answer is wrong, be specific, about which of the above claims is false, and why it is false.

Maybe someone thinks I’m too harsh, accusing you for being an intellectual fraud. But, here’s the proof:

1) Bell's ansatz (equation 2 in his paper) correctly represent those local-causal hidden variables
2). Bell's ansatz necessarily lead to Bell's inequalities
3). Experiments violate Bell's inequalities
Conclusion: Therefore the real physical situation of the experiments is not Locally causal.

There is no doubt in my mind that statement (2) has been proven mathematically since I do not know of any mathematical errors in Bells derivation. Similarly, there is very little doubt in my mind that experiments have effectively demonstrated that Bell's inequalities are violated. I say little doubt because no loophole-free experiments have yet been performed but for the sake of this discussion we can assume that loopholes do not matter.

No mathematical errors in Bells derivation. Well, well, well, what happened here??

What happened is that JesseM proved, by immense patience and great skills, that your "chains of probability" where dead wrong. Then you changed your madcap "approach" to the "triplet mess". Once again JesseM where about to prove you wrong, and to get out of this, you started a totally groundless personal attack on JesseM:
I did respond to that post, but I didn't end up responding to your later post #128 on the subject here (http://www.physicsforums.com/showpost.php?p=2771935&postcount=128) because before I got to it you said you didn't want to talk to me any more unless I agreed to make my posts as short as you wanted them to be and for me not to include discussions of things I thought were relevant if you didn't agree they were relevant.
As you no doubt remember I gave extended arguments and detailed questions intended to show why your claims that Bell's theorem is theoretically flawed or untestable don't make sense, but you failed to respond to most of my questions and arguments and then abruptly shut down the discussion, in multiple cases (As with my posts here (http://www.physicsforums.com/showpost.php?p=2706689&postcount=68) and here (http://www.physicsforums.com/showpost.php?p=2711170&postcount=78) where I pointed out that your argument about the failure of the 'principle of common cause' ignored the specific types of conditions where it failed as outlined in the Stanford Encyclopedia article you were using as a reference, and I asked you to directly address my argument about past light cones in a local realist universe without relying on nonapplicable statements from the encyclopedia article. Your response here (http://www.physicsforums.com/showpost.php?p=2711285&postcount=82) was to ignore all the specific quotes I gave you about the nature of the required conditions and declare that you'd decided we'd have to 'agree to disagree' on the matter rather than discuss it further...if you ever change your mind and decide to actually address the light cone argument in a thoughtful way, you might start by saying whether you disagree with anything in post #63 here (http://www.physicsforums.com/showthread.php?t=406372)).

Then you continued the crazy "triplet mess", knowing that JesseM would prove your initial attack on Bell dead wrong:
The facts are the following:
1) Bell's inequality is derived assuming 3 values per dataset point
2) Bell-test experiments measure 2 values per dataset point
3) Bell-test experiments violate Bell's inequalities

JesseM showed patience:
So this critique appears to be rather specific to the Leggett-Garg inequality, maybe you could come up with a variation for other inequalities but it isn't obvious to me ...

But you continued your wacky crankiness:
This is not a valid criticism for the following reason:

1) You do not deny that the LGI is a Bell-type inequality. Why do you think it is called that?
2) You have not convincingly argued why the LGI should not apply to the situation described in the example I presented
3) You do not deny the fact that in the example I presented, the inequalities can be violated simply based on how the data is indexed.
4) You do not deny the fact that in the example, there is no way to ensure the data is correctly indexed unless all relevant parameters are known by the experimenters
5) You do not deny that Bell's inequalities involve pairs from a set of triples (a,b,c) and yet experiments involve triples from a set of pairs.
6) You do not deny that it is impossible to measure triples in any EPR-type experiment, therefore Bell-type inequalities do not apply to those experiments. Boole had shown 100+ years ago that you can not substitute Rij for Sij in those type of inequalities.

JesseM tried to explain:

5) You do not deny that Bell's inequalities involve pairs from a set of triples (a,b,c) and yet experiments involve triples from a set of pairs.

I certainly deny this too, in fact I don't know what you can be talking about here. Different inequalities involve different numbers of possible detector settings, but if you look at any particular experiment designed to test a particular inequality, you always find the same number of possible detector settings in the inequality as in the experiment. If you disagree, point me to a particular experiment where you think this wasn't true!

6) You do not deny that it is impossible to measure triples in any EPR-type experiment, therefore Bell-type inequalities do not apply to those experiments. Boole had shown 100+ years ago that you can not substitute Rij for Sij in those type of inequalities.

This one is so obviously silly you really should know better. The Bell-type inequalities are based on the theoretical assumption that on each trial there is a λ which either predetermines a definition outcome for each of the three detector settings (like the 'hidden fruits' that are assumed to be behind each box on my scratch lotto analogy), or at least predetermines a probability for each of the three which is not influenced by what happens to the other particle at the other detector (i.e. P(A|aλ) is not different from P(A|Bbaλ)). If this theoretical assumption were valid, and the probability of different values of λ on each trial did not depend on the detector settings a and b on that trial, then this would be a perfectly valid situation where these inequalities would be predicted to hold. Of course we don't know if these theoretical assumptions actually hold in the real world, but that's the point of testing whether the inequalities hold up in the real world--if they don't, and our experiments meet the necessary observable conditions that were assumed in the derivation, then this constitutes an experimental falsification of one of the predictions of our original theoretical assumptions.

But you are still continuing your ridiculous crusade against John Bell, without listening to professionals.

If we just take one step back, and look at your new main cranky "argument":
If your silly little code, by a grand miracle, proves that the Leggett–Garg inequality (http://en.wikipedia.org/wiki/Leggett%E2%80%93Garg_inequality) is wrong, then you are hoping to run Bell's theorem down the drain as well, right?

(To those who don’t know: Sir Anthony James Leggett (http://en.wikipedia.org/wiki/Anthony_James_Leggett) got the Nobel Prize in Physics 2003)

There’s only one 'little' problem with this "advanced crackpot approach" – Bell's theorem was formulated in 1964 and the Leggett–Garg inequality is from 1985, published in the paper: Quantum mechanics versus macroscopic realism: Is the flux there when nobody looks? (http://prl.aps.org/abstract/PRL/v54/i9/p857_1)

Are you claiming that John Bell used a time machine in 1964 that made Bell's theorem unconditionally depending on something that were to happen in 1985!?!?

Or are you claiming that George Boole was working on a "Leggett–Garg inequality" already in 1840, and this is the real reason for John Bell’s claimed failure in 1964!?!?

I know you & Crackpot Kracklauer have some really crazy ideas, but this is (hopefully) a little too absurd even to you...

I don’t know why you are doing the bizarre stuff you do, but too the casual reader – this is not science.

To me, this looks like a severe case of the Dunning–Kruger effect (http://en.wikipedia.org/wiki/Dunning–Kruger_effect) + the Savant syndrome (http://en.wikipedia.org/wiki/Savant_syndrome).

I’m not going to spend more time on you, since there is undoubtedly NO hope.

billschnieder

Jul19-10, 06:44 PM

1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!

Now if anyone thinks my answer is wrong, be specific, about which of the above claims is false, and why it is false.

Still no response. Lots of insults and grand-standing but no response. I wonder why?

P.S. Advise to any reader – Don’t bother to run the Monty Python code unless you want a good laugh. There are no initialized variables, and 0*0 is always zero, zip, nada, zilch. HAHAHAHAH!!!
Once again you have misinterpreted everything about everything. The numeric example "0*0" was not referring to your silly little code, but your brain cells.

:bugeye: Liar

And you can add that to the following list, my comments in square brackets:

- I am a layman/amateur. [obviously]
- I have no real education in cosmology or physics (one introduction-course in astronomy). [obviously]
- I read popular-science. [obviously]
- I spend time on the web, searching and reading about cosmology & physics. [apparently not very much ]
- I do not understand the advanced math, required for modern science. [it shows]
- I admire all hardworking people who spend a great part of their lives, struggle to solve the mysteries of nature – to the benefit for all of us (guys drinking beer and watching football). [I doubt it]
- I do accept physics as practiced by the scientific community (of course). [except when you don't like it]
- I am not religious, and I believe that religion should not have any part in science (or politics). [yeah right]
- I think it is important that scientist do all possible to communicate new science to the public. [except the ones you don't like should shut up]
- I like to question subjects (that could be questioned by a layman), if they don't make sense to me. [and obviously also the ones you have no clue about]
- My only hope in the complexity of science: "If you can't explain it simply, you don't understand it well enough." -- Albert Einstein [at least we agree on something]
- I am curious [are you sure?]
...
- A deterministic law of physics sounds a little 'disturbing'. I like my free will.. [it shows]

-----
Småväxt man är högfärdig.

DrChinese

Jul20-10, 09:13 AM

Still no response. Lots of insults and grand-standing but no response. I wonder why?

Show us a dataset. How hard can it be? Such as this hypothetical local realistic one showing values at polarization angle settings a, b and c:

Alice:

a b c
+ + -
+ - +
- + -
+ - -
etc

Bob (her entangled twin):

a b c
+ + -
+ - +
- + -
+ - -
etc

According to EPR, there are elements of reality to Alice because we can predict Alice with certainty by observing Bob. We do this by observing Bob's a when we want to predict Alice's a; Bob's b when we want to predict Alice's b; etc.

So far, so good: QM and Local Realism (LR) in sync as to predictions. But here is where it all goes wrong. Per above (and for larger samples too), LR predicts average coincidence rate of no less than 33% when the angles are different (such as a separation of 120 degrees). QM predicts a coincidence rate of 25% for that separation.

Experiments plainly support QM and reject LR, without exception. So the above dataset I presented is flawed because the values a, b and c are not simultaneously well defined independent of observation. EPR felt that was unreasonable, but they did not know about Bell and they did not know about Bell tests.

-------

Bar är broderlös bak.

DevilsAvocado

Jul21-10, 10:05 AM

... So far, so good: QM and Local Realism (LR) in sync as to predictions.

Your explanation on a b c is rock-solid and crystal-clear to everyone who wishes to understand, and I guess that even a gifted 10-yearold could do it, with some help.

I don’t know how old billschnieder is, but undoubtedly he’s fishing for something else. He’s obviously scared to death by anything that looks like Spukhafte Fernwirkung, and he doesn’t care that much about the R in Local Realism.

AFAICT, the example with a b c is excellent to explain the impossibility of objects having pre-existing values (= Einsteinian Realism).

Since billschnieder now has run into the wall with his first attempt to disprove Bell's theorem by Bayesian probability + the Chain rule (claiming that the "Big Problem" is that Bell used a comma instead of a vertical bar in Bell (2)) – he now thinks he has found the "Big Flaw" in triples.

billschnieder for real thinks that Bell's theorem REQUIRES three (3) simultaneous values, and since we always get two (2) entangled values in real EPR-Bell experiments – Bell's theorem can NEVER be proven right by real experiments. billschnieder is therefore supremely convinced that he has made a new groundbreaking scientific discovery.

He "builds" this majestic "scientific discovery" solely on the Leggett–Garg inequality:
Wikipedia - Leggett–Garg inequality (http://en.wikipedia.org/wiki/Leggett%E2%80%93Garg_inequality)

The simplest form of the Leggett–Garg inequality derives from examining a system that has only two possible states. These states have corresponding measurement values Q=\pm 1. The key here is that we have measurements at two different times, and one or more times between the first and last measurement. The simplest example is where the system is measured at three successive times t1 < t2 < t3.

And the rest of the world knows that Bell's theorem is from 1964 and the Leggett–Garg inequality is from 1985.

... pure madness ... don’t know if to laugh or weep ...

P.S. Your Swedish footnote is cool! "Others" did not have the same luck with Google Translate and I’m laughing hilarious tears. :biggrin:

-----------------------
Почему 100? Если я ошибся, один было бы достаточно.

DrChinese

Jul21-10, 11:12 AM

Your explanation on a b c is rock-solid and crystal-clear to everyone who wishes to understand, and I guess that even a gifted 10-yearold could do it, with some help.

Thanks, in fact *I* am a gifted 10 year old. In a slightly more used body, however.

One of the things that it is easy to lose sight of - in our discussions about spin/polarization - is that a Bell Inequality can be created for literally dozens of attributes. Anything that can be entangled is a potential source. Of course there are the other primary observables like momentum, energy, frequency, etc. But there are secondary observables as well. There was an experiment showing "entangled entanglement", for example. Particles can be entangled which have never interacted, as we have discussed in other threads.

And in all of these cases, a realistic assumption of some kind leads to a Bell Inequality; that Inequality is tested; the realistic hypothesis is rejected; and the predictions of QM are confirmed.

None of which fits with our "common sense" view of the moon being there when not observed. And yet every variation shows the same result. You have to respect nature for being so consistent. :smile:

questions,yes

Jul21-10, 11:27 AM

DrChinese

Jul21-10, 12:13 PM

So a tree falls down and no one hears it, did it make a sound?

The math says not(?)

It's impossible to prove it did(?)

Should we "just stop worrying and calculate"?

...or has the tree just hit me?

Welcome to PhysicsForums, questions,yes!

Impossible to prove it did make a sound, I say. And the tree hit me on the way down too!!

skippy1729

Jul21-10, 01:53 PM

So a tree falls down and no one hears it, did it make a sound?

My favourite answer to this question:

"What is observed, certainly exists; about what is not observed we are still free to make suitable assumptions. This freedom is then used to avoid paradoxes."

von Weizsäcker, C. H., 1971, in Quantum Theory and Beyond, ed. T. Bastin, (Cambridge University Press, London) page 26.

Skippy

DevilsAvocado

Jul21-10, 03:11 PM

Thanks, in fact *I* am a gifted 10 year old. In a slightly more used body, however.

You are welcome. Why do I feel some entanglement here...?? Especially the body part... :smile: The critical difference must be that some suspect I have only one brain cell. But what do I care; I’m only a layman here to learn, not a pseudo professor trying to run over Nobel Laureates. :biggrin:

And in all of these cases, a realistic assumption of some kind leads to a Bell Inequality; that Inequality is tested; the realistic hypothesis is rejected; and the predictions of QM are confirmed.

Excellent explanation again! For a 1-brain-cell 10-yearold like me; could we say that a Bell Inequality is like a "speed limit", if we exceed (violate) this "speed limit" we are caught with something that doesn’t fit our everyday experience.

Like driving a Volkswagen Beetle 400 mph on Autobahn, and then being stopped by the Autobahnpolizei to deliver a "realistic hypothesis" for the car and the speed.

If this is correct, then there is nothing "spooky" about a Bell Inequality – it’s the violation of this inequality that mess up our classical conception about the (microscopic) reality, right?

DevilsAvocado

Jul21-10, 03:16 PM

So a tree falls down and no one hears it, did it make a sound?

Welcome questions,yes

Sometimes it’s hard to hear the wood for all the falling trees... how about a good old tape recorder... :smile:

(struck by the whole wood, one brain cell left...)

questions,yes

Jul21-10, 05:07 PM

... how about a good old tape recorder... :smile:

Presumably that would qualify as "hearing" it?

Has acausality been ruled out?

DevilsAvocado

Jul21-10, 06:00 PM

Presumably that would qualify as "hearing" it?

Yeah, I know... but the funny thing is: How does the tree know if the tape recorder is on or off, or if the tape is damaged, etc?? The tree must know all these things before it starts falling... :smile:

DougW

Jul21-10, 06:05 PM

There is no such thing called the "MU theory", unless you just made it up. Are you talking about the Many-worlds interpretation (MWI), or the Ultimate Ensemble hypothesis?

I hope you do know the difference between theory/hypothesis/interpretation?

Sigh.... MU was just shorthand for Multiple Universe, which I had written a few times earlier in the post. I had also mentioned David Deustch by name, so I assumed you would get what I was saying.

ThomasT

Jul22-10, 12:55 AM

Sigh.... MU was just shorthand for Multiple Universe, which I had written a few times earlier in the post. I had also mentioned David Deustch by name, so I assumed you would get what I was saying.I've been reading (at least trying to) Deutsch's "The Fabric of Reality". It might take me months (or even years) to honestly agree or disagree with his contentions. He's a genius of sorts. Adept at seeing connections that most of us don't see. But, I think that there might be a simpler reason for not assuming nonlocality (even though I like the idea of the SE and resultant wavefunctions as approximating the underlying reality) than the MUI or MWI represent. Anyway, it's fascinating reading.

Check out my subsequent postings for some rather more 'down to earth' reasons why violations of BIs don't imply nonlocality (or anything else about nature).

ThomasT

Jul22-10, 01:10 AM

Show us a dataset.It isn't clear to me what you mean by this 'dataset' of yours. Models/theories of entanglement (including QM and LR models) predict rates of detection, not datasets. So where does this dataset come from? What are you talking about?

ThomasT

Jul22-10, 01:58 AM

billschnieder's recent arguments are based on the papers cited below:

Possible Experience: from Boole to Bell
http://arxiv.org/PS_cache/arxiv/pdf/0907/0907.0767v2.pdf
Published in: EPL, 87 (2009) 60007

Extended Boole-Bell inequalities applicable to quantum theory
http://arxiv.org/PS_cache/arxiv/pdf/0901/0901.2546v2.pdf

The second paper, still in the works, on the extended Boole-Bell inequalities, provides a detailed account of why BIs are violated and why their violation doesn't imply nonlocality in nature.

While we love them both, I doubt that DrC understands these arguments, and I know that the wild and wacky DevilsAvocado doesn't. So, erstwhile reader, as you're vacillating between believing that violations of BIs 'prove' nonlocality or not, consider this -- the authors of the above papers are established, well respected, and bona fide professors in their respective fields. Hess is a well known and well respected physicist. On the other hand, the people arguing in favor of nonlocality are DrC, who is a computer programmer of unknown competence, and DevilsAvocado (he isn't even confident enough to reveal his real identity) an admitted physics novice and amateur.

The only working physicist (RUTA) who has contributed to this thread is decidedly against the idea that nonlocality is a fact of nature.

If you have the expertise to follow and render opinions regarding the above-reference papers, then render them. If you don't, then wouldn't it be wise to follow the conclusions of the professionals who wrote those papers?

DevilsAvocado

Jul22-10, 06:28 AM

Well, I have to inform the "casual reader" that this thread now is "gifted" with two (2) intellectual swindlers:
When I first entered the foundations community (1994), there were still a few conference presentations arguing that the statistical and/or experimental analyses of EPR-Bell experiments were flawed. Such talks have gone the way of the dinosaurs. Virtually everyone agrees that the EPR-Bell experiments and QM are legit, so we need a significant change in our worldview. There is a proper subset who believe this change will be related to the unification of QM and GR :-)
Science has not proven nonlocality. I'm a physicist who believes the Bell experiments are legit, but these experiments don't prove nonlocality; they prove nonlocality and/or nonseparability. So, it's possible that we have nonseparability and locality.

(And it’s of course not RUTA.)

DevilsAvocado

Jul22-10, 06:51 AM

Sigh.... MU was just shorthand for Multiple Universe, which I had written a few times earlier in the post. I had also mentioned David Deustch by name, so I assumed you would get what I was saying.

I know. It’s the theory in "MU theory" that caught my interest. David Deutsch calls it multiverse hypothesis, which is something else:
"Wikipedia - A scientific theory is constructed to conform to available empirical data about such observations, and is put forth as a principle or body of principles for explaining a class of phenomena."

This is one of those "little things" that our two intellectual swindlers in this thread would exploit to bamboozle the "casual reader".

ThomasT

Jul22-10, 07:43 AM

Well, I have to inform the "casual reader" that this thread now is "gifted" with two (2) intellectual swindlers:DA, we all know that you're a novice and that you don't understand, well, pretty much anything. So, this might be a good time for you to take a break. :rolleyes: No ... really. I mean it. Just ... have a time out or whatever they have you do in school when you're naughty. Do that.

For anyone else: I said that "the only working physicist (RUTA) who has contributed to this thread is decidedly against the idea that nonlocality is a fact of nature."

Here are some RUTA quotes provided by, yes that's right, the DA itself:

When I first entered the foundations community (1994), there were still a few conference presentations arguing that the statistical and/or experimental analyses of EPR-Bell experiments were flawed. Such talks have gone the way of the dinosaurs. Virtually everyone agrees that the EPR-Bell experiments and QM are legit, so we need a significant change in our worldview. There is a proper subset who believe this change will be related to the unification of QM and GR :-)

Science has not proven nonlocality. I'm a physicist who believes the Bell experiments are legit, but these experiments don't prove nonlocality; they prove nonlocality and/or nonseparability. So, it's possible that we have nonseparability and locality.

Let's see now, RUTA says that "science has not proven nonlocality", " [Bell] experiments don't prove nonlocality", "it's possible that we have nonseparability and locality", and, guess what, RUTA has co authored a theory in which quantum entanglement is depicted as a nonseparable, local phenomenon.

So, I must thank the DA for supporting my contention regarding RUTA (the ONLY ...the ONLY? ... yes, the ONLY working physicist who has contributed to this thread). :smile:

DougW

Jul22-10, 07:45 AM

I know. It’s the theory in "MU theory" that caught my interest. David Deutsch calls it multiverse hypothesis, which is something else:
"Wikipedia - A scientific theory is constructed to conform to available empirical data about such observations, and is put forth as a principle or body of principles for explaining a class of phenomena."

This is one of those "little things" that our two intellectual swindlers in this thread would exploit to bamboozle the "casual reader".

LOL, you're right, I have noticed how some people will beat down discussion with umimportant details like that. The point I was trying to make was simply this:

The movement of the sun, moon and stars could not be truly understood (or predicted by mathemetical formulas) until someone took the leap to consider whether they might not be orbiting around the earth. Likewise, when Galileo dropped his two balls from the top of the tower of Pisa, he was making a move away from a framework of assumptions about the universe that allowed us to come up with new experiments, make new predictions and ultimately 'discover' new laws of physics.

For some reason, many people assume that there are no more leaps of that caliber left to be made, that we understand all there is to understand about the universe. So when a quandry like 'spooky action at a distance' comes up, we want to explain it only within the framework of what we have previously labeled 'the known universe'. And what we are missing is that this may simply not be possible.

It may be that under specific local conditions that C is a fixed velocity, but when viewed from a different framework (other dimensions? warped timespace?) it may be possible to exceed that limit. The most interesting things being done in physics today concern areas where the limit of our understanding is being expanded: Information Theory, Brane Theory, the Study of Complexity, Quantum Computing, etc.

The role of physics in this is to find ways to disprove these theories, discard those that won't stand up to experiment, and then make deeper assumptons (based on logic, not wild flights of fancy like 'spirits' in plants giving them healing properties) and develop new experiments to attempt to disprove these additional assumptions.

As for this forum, it's good to see that there are at least a few people who are courteous enough to treat everyone civilly. It would be pretty sad to think that this forum's reason for existence is so that a bunch of really smart people could remind themselves how much more they know than everyone else....

DougW

Jul22-10, 07:47 AM

DA, we all know that you're a novice and that you don't understand, well, pretty much anything. So, this might be a good time for you to take a break. :rolleyes: No ... really. I mean it. Just ... have a time out or whatever they have you do in school when you're naughty. Do that.

For anyone else: I said that "the only working physicist (RUTA) who has contributed to this thread is decidedly against the idea that nonlocality is a fact of nature."

Here are some RUTA quotes provided by, yes that's right, the DA itself:

Let's see now, RUTA says that "science has not proven nonlocality", " [Bell] experiments don't prove nonlocality", "it's possible that we have nonseparability and locality", and, guess what, RUTA has co authored a theory in which quantum entanglement is depicted as a nonseparable, local phenomenon.

So, I must thank the DA for supporting my contention regarding RUTA (the ONLY ...the ONLY? ... yes, the ONLY working physicist who has contributed to this thread). :smile:

Wow, I hope you had an adequate supply of kleenex handy after that post......

ThomasT

Jul22-10, 07:58 AM

Wow, I hope you had an adequate supply of kleenex handy after that post......OK Doug :uhh:

DevilsAvocado

Jul22-10, 08:28 AM

DA, we all know that you're a novice and that you don't understand, well, pretty much anything. So, this might be a good time for you to take a break. :rolleyes: No ... really. I mean it. Just ... have a time out or whatever they have you do in school when you're naughty. Do that.

For anyone else: I said that "the only working physicist (RUTA) who has contributed to this thread is decidedly against the idea that nonlocality is a fact of nature."
they prove nonlocality and/or nonseparability

Well, I have to inform the "casual reader" that the two (2) intellectual swindlers follow the same pattern over and over again. When proven wrong in simple English, understandable by a 10-yearold, they turn in to personal attacks and name calling, in lack of any real arguments. We have seen this number of times by now.

The funny thing is that they accuse others for being "drama queens" and "liars", etc. What can one do but laugh.

I can’t wait for RUTA to comment on this deliberate corruption of his scientific position in EPR-Bell. It will be pure entertainment.

nismaratwork

Jul22-10, 08:42 AM

I've been reading this thread, but fellows, if this insulting keeps up I doubt it will go on. Please, go back to an exchange of ideas and not vitriol.

DrChinese

Jul22-10, 09:00 AM

It isn't clear to me what you mean by this 'dataset' of yours. Models/theories of entanglement (including QM and LR models) predict rates of detection, not datasets. So where does this dataset come from? What are you talking about?

Read EPR. According to EPR, there are elements of reality to values which can be predicted with certainty. That would be, per their definition, values for any angles a, b and c I care to chose. If they have those values, what are they? Any local realist should be able to provide an example dataset. I have provided my own, for example, and demonstrated that it leads to outcomes which are inconsistent with observation. LR is inconsistent, QM is not.

Ergo, those EPR elements of reality don't exist.

DevilsAvocado

Jul22-10, 09:08 AM

I've been reading this thread, but fellows, if this insulting keeps up I doubt it will go on. Please, go back to an exchange of ideas and not vitriol.
I agree. But what’s your advice when some people in this thread deliberately try to delude the "casual reader"? Should we keep quiet?
Please reply to my specific questions.

You stated that Kracklauer's "statistics assumed information concerning the detector settings at all sites was available at all sites." Isn't it true that at the conclusion of a run this info is available ... to the global observer, the experimenter? So, I'm suggesting that maybe Kracklauer's objection to your criticism was valid.

As I've asked, if you can point out the specific error in Kracklauer's analysis, then that woud be appreciated.

That the information is available AFTER the fact doesn't bear on a possible CAUSE for the correlations. The point is that the detector setting at site A is NOT available to site B BEFORE the detection event occurs at site B. If this information is available prior to detection, the correlations in the outcomes can be orchestrated to violate Bell's inequality. No one disputes this fact -- you have to keep the outcome at each site dependent ONLY upon information AT THAT SITE to have the conundrum about their correlations.

Thus, there are generally two ways to account for EPR-Bell correlations. 1) The detection events are separable and you have superluminal exchange of information. 2) The detection events are not separable, e.g., the spin of the entangled electrons is not a property of each electron. The first property is often called "locality" and the second property "realism."

Kracklauer's statistics simply assumed detector setting information was available at each site prior to detection outcomes. When I discussed this with him at a conference, he was adamant that the outcome at each site was contingent upon outcomes and settings at other sites so the "proper" statistics had to contain this fact. His whole argument was that we needed to use the "proper" statistics and the mystery would disappear. His "proper" statistics just assume global knowledge of detector settings. But, unless he has a proposal for how this information is available, he has done nothing to resolve the mystery. How is this information available? FTL signals or nonseparability? Or both? What is the mechanism? All he had was a statistical counterpart to the mystery, although it could be published if no one else had pointed this out. But, nothing was "resolved."

Personally, I will focus on the interesting facts concerning EPR-Bell, and maybe someone else can act "swindler cleanup", and chase scams like this one:
On the other hand, the people arguing in favor of nonlocality are DrC, who is a computer programmer of unknown competence, and DevilsAvocado (he isn't even confident enough to reveal his real identity) an admitted physics novice and amateur.
Virtually everyone agrees that the EPR-Bell experiments and QM are legit, so we need a significant change in our worldview.

nismaratwork

Jul22-10, 04:09 PM

I agree. But what’s your advice when some people in this thread deliberately try to delude the "casual reader"? Should we keep quiet?

Personally, I will focus on the interesting facts concerning EPR-Bell, and maybe someone else can act "swindler cleanup", and chase scams like this one:

I'm a casual reader, and I've already formed the opinion that DrChinese is very knowledgeable, you are in the process of learning and are very curious and willing to admit your faults, RUTA has some real experience, and ThomasT is cracked. Don't worry, the text speaks for itself.

ThomasT

Jul22-10, 04:53 PM

ThomasT

Jul22-10, 04:56 PM

According to EPR, there are elements of reality to values which can be predicted with certainty.Ok, the 'certain' prediction would be the deduction following the application of, say, some conservation law. All this says is that if we can make an accurate prediction by deduction, then we can assume that there was in fact 'something' propagating between the emitter and the detector, and that it had some definite value of a conserved property which caused the detection and allowed us to correctly predict that detection via deduction. The conservation law just specifies a relationship between some property of the co-emitted disturbances. But that doesn't give us any clue about what the precise values of the disturbances incident on polarizer a and polarizer b are.

That would be, per their definition, values for any angles a, b and c I care to chose. If they have those values, what are they? Any local realist should be able to provide an example dataset.This is the 'unrealistic' requirement that an LR model predict a particular dataset. However, it's the experiments that produce the datasets, and there are LR models of entanglement which correctly predict the rates of detection, but they can't predict the datasets any more than qm can.

I agree that if you try to model entanglement in terms of 'instruction sets', or Herbert's 'coded messages', or just definite values for some property of the polarizer-incident disturbances, then you get inconsistencies. But these aren't the only ways to construct an LR model. That Bell's LR formulation follows the nonviable course means that the violation of BIs rules out the sorts of LR models that follow that prescription, or proscription. You've been presented with LR models wrt which your dataset requirement doesn't apply. I would hope that somewhere along the line you would actually look closely at them. Maybe you'll decide that they aren't local or realistic for some other reason.

Before that however don't forget to read the papers I linked to in post #1098. They're relevant to the argument that billschnieder has been presenting recently.

DevilsAvocado

Jul22-10, 06:27 PM

I'm a casual reader, and I've already formed the opinion that DrChinese is very knowledgeable, you are in the process of learning and are very curious and willing to admit your faults, RUTA has some real experience, and ThomasT is cracked. Don't worry, the text speaks for itself.

Thanks nismaratwork, good to know that I didn’t scare you away. o:)

I think we should add that JesseM has real solid knowledge, and a very fine ability to pinpoint the hilarious character of our good old swindler:
[ThomasT] You are simply wrong here (and given your own lack of knowledge of physics, it's ridiculous that you act so confident), the mainstream view is that the "totality of local realistic conceptions" have indeed been shown to be incompatible with violations of Bell inequalities.

:biggrin:

DrChinese

Jul22-10, 06:43 PM

Regarding the issue of the EPR elements of reality:

Suppose you look at the most basic interpretation: If you can predict only 1 attribute at a time, then there is realism to that attribute. Under that restrictive requirement, QM and LR would agree, and a dataset might look like this:

Alice:
a
+
-
+
-

Because we had Bob as:

a
+
-
+
-

Now suppose we had the idea that there was simultaneous reality to both Alice a and Bob b (by hypothesis):

Alice:
a b
+ -
- +
+ +
- +

Bob:
a b
+ -
- +
+ +
- +

Who could say this wasn't feasible for both QM and LR? This was the situation EPR envisioned. And it is not clear a Local Realistic theory - one more "complete" than QM - might not exist in this scenario. In the above case, the coincidence rate of 25% is as QM predicts when a and b are 120 degrees apart.

But when you take it a step further - as Bell did - it becomes clear that NO local realistic theory can provide a dataset matching the QM predictions with an a, b and c.

DrChinese

Jul22-10, 07:04 PM

I thought we were just having some fun. Sorry if I hurt your feelings DA. Hey, I don't even know what 'vitriol' means.

Indeed. I'm glad you're such a good sport.

I like the kinder, gentler ThomasT. :smile:

nismaratwork

Jul22-10, 07:26 PM

ThomasT

Jul23-10, 05:32 AM

... it becomes clear that NO local realistic theory can provide a dataset matching the QM predictions with an a, b and c.Theories don't provide datasets, they predict rates of detection.

If you consider detection attributes as being in one to one correspondence with an underlying reality, then of course you'll get inconsistencies. This is clearly illustrated by GHZ as well as Bell.

But this tells us nothing about reality, because it isn't required that detection attributes be in one to one correspondence with an underlying reality.

ThomasT

Jul23-10, 05:43 AM

I'm a casual reader, and I've already formed the opinion that DrChinese is very knowledgeable, you are in the process of learning and are very curious and willing to admit your faults, RUTA has some real experience, and ThomasT is cracked.
So you start out by calling people names? What happened to all that stuff about "an exchange of ideas not vitriol".

DevilsAvocado

Jul23-10, 06:09 AM

But when you take it a step further - as Bell did - it becomes clear that NO local realistic theory can provide a dataset matching the QM predictions with an a, b and c.

Thanks DrC, for bringing this down to earth again.

I’m trying to get this into my little 1-brain-cell-head, and you know I like it simple. :smile:

Could a analogous view on the situation EPR envisioned be that if the polarizers a & b are aligned parallel (0º,0º / 0º,180º) or perpendicular (0º,90º) – it is not possible to violate Bell's Inequality, and the Einsteinian Local Realism (LR) still holds.

The genius move of John Bell was to extend the 'test' to all possible relative angles (0º-360º) between a & b, and by this he did violate Bell's Inequality, thus proving that nonlocality and/or nonseparability is a fact.

(One thing that still puzzles me: Why didn’t Einstein or Bohr think of that...?:bugeye:?)

DevilsAvocado

Jul23-10, 06:28 AM

DrChinese

Jul24-10, 09:08 AM

If you consider detection attributes as being in one to one correspondence with an underlying reality, then of course you'll get inconsistencies. This is clearly illustrated by GHZ as well as Bell.

But this tells us nothing about reality, ...

According to EPR, it does. The realism assumption is directly deduced from that. The question is whether or not the requirement the elements of reality be simultaneously predictable is reasonable. EPR thinks NO, they do not need to be simultaneously predictable.

You, on the other hand, think they should be simultaneously predictable because otherwise there is nothing but the results of measurements. That would put you squarely in the quantum mechanical camp. According to standard QM, there is no deeper reality than what can be observed (i.e. nothing deeper than the limits of the HUP). Glad to see this more sensible side to this discussion from you. You can call officially yourself a Bohr Local Realist. :smile:

DrChinese

Jul24-10, 09:13 AM

ThomasT

Jul24-10, 09:41 AM

I just did a miraculous scientific discovery!! I made my own little "theory" by assigning Malus' to both (not entangled) Alice & Bob, and guess what?? IT DID PROVIDE ME WITH A DATASET!! OH MY GOD!!! :surprised

Angle Malus' Alice Bob
------------------------------
0º 100% 111111 111111
22.5º 85% 111110 111110
45º 50% 111000 111000
67.5º 15% 100000 100000
90º 0% 000000 000000

:rofl:Why this doesn't work has been quite extensively discussed in this thread. This is a misapplication of Malus Law. It doesn't predict individual results. Attributing specific values to polarization vectors causes Malus Law to break down.

LR and QM models of entanglement don't predict datasets. They predict rates of detection.

Entanglement stats are produced by entanglement experiments (or valid simulations). This is the only source for datasets that might be used to evaluate the relative accuracy of competing models.

nismaratwork

Jul24-10, 10:03 AM

Why this doesn't work has been quite extensively discussed in this thread. This is a misapplication of Malus Law. It doesn't predict individual results. Attributing specific values to polarization vectors causes Malus Law to break down.

LR and QM models of entanglement don't predict datasets. They predict rates of detection.

Entanglement stats are produced by entanglement experiments (or valid simulations). This is the only source for datasets that might be used to evaluate the relative accuracy of competing models.

How on earth does Malus' Law apply to this in the slightest?

DrChinese

Jul24-10, 10:20 AM

DevilsAvocado

Jul24-10, 11:38 AM

Why this doesn't work has been quite extensively discussed in this thread. This is a misapplication of Malus Law. It doesn't predict individual results. Attributing specific values to polarization vectors causes Malus Law to break down.

I don’t agree. Yes, Malus' gives a percentage for the probability at a certain angle, but does this fact make it impossible to predict individual results? Definitely no, it’s possible indeed to predict the individual results.

For the first angle 0º we only 1 possible combination, 100% all the time:
111111

For the second angle 22.5º we have 6 different combinations:
111110
111101
111011
110111
101111
011111

For the third angle 45º we have 20 different combinations:
111000
110100
110010
110001
101100
101010
101001
100110
100101
100011
011100
011010
011001
010110
010101
010011
001110
001101
001011
000111

For the forth angle 67.5º we have the same combinations as for angle 22.5º, i.e. 6 different combinations.

For the fifth angle 90º we have the same combinations as for angle 0º, i.e. 1 combination.

This gives us a total of 1 x 6 x 20 x 6 x 1 = 720 combinations.

I know, and you know that it’s very possible to print these different combinations, and predict with 100% certainty every time we run this test, that one of the combinations will occur.

It’s like winning on the lottery every day! :smile:

(Maybe someone who is better in math than I am, could tell me if it’s just a fluke that 6! = 720 ?:bugeye:?)

DevilsAvocado

Jul24-10, 11:51 AM

Cool. I wonder why some people have such a hard time of it. Heh.

There are more things in heaven and earth, than are dreamt of in philosophy. :wink:

DevilsAvocado

Jul24-10, 11:54 AM

How on earth does Malus' Law apply to this in the slightest?

cos^2(a-b) :wink:

nismaratwork

Jul24-10, 07:01 PM

cos^2(a-b) :wink:

:biggrin: I think you covered the relevance of how it doesn't interfere with the results a couple of posts ago.

ThomasT

Jul28-10, 01:10 AM

LR and QM models of entanglement don't predict datasets. They predict rates of detection.
I think DevilsAvocado has proven you wrong. Cause there is one for us to look at right there on the page. I see it. If that model is not a QM consistent dataset, perhaps you will point out the elements which fail.
So, what are you saying DrC, that qm predicts the results of individual measurements? That's silly. Or do you just say these sorts of things to confuse people?

Your 'dataset' requirement for LR models is nonsense. It's nonsense, it has nothing to do with any of this. If you think it does, then write a paper on it and get it peer reviewed. Otherwise, stop presenting it in these forums.

And for DA's idea that specific values of polarization vectors are in one to one correspondence with experimental results -- I'm sorry but we have no way of knowing if that's the case.

So, I'll repeat MY mantra. LR and QM models of entanglement predict rates of coincidental detection. No more, and no less.

DrChinese

Jul28-10, 09:09 AM

1. Your 'dataset' requirement for LR models is nonsense. It's nonsense, it has nothing to do with any of this. If you think it does, then write a paper on it and get it peer reviewed. Otherwise, stop presenting it in these forums.

2. So, I'll repeat MY mantra. LR and QM models of entanglement predict rates of coincidental detection. No more, and no less.

1. :rofl: You can consider my dataset requirement more of a crackpot filter. And I think it's working!

2. Then perhaps you will show us your LR formula, and by the way, why don't you give us a sample dataset so we can see it in action. I will gladly do the same for QM's model.

DevilsAvocado

Jul28-10, 11:34 AM

a crackpot filter. And I think it's working!

:rofl:

DevilsAvocado

Jul28-10, 11:43 AM

And for DA's idea that specific values of polarization vectors are in one to one correspondence with experimental results -- I'm sorry but we have no way of knowing if that's the case.

So, I'll repeat MY mantra. LR and QM models of entanglement predict rates of coincidental detection. No more, and no less.

Okay, I’m not stubborn, running over people with my own little skewed view.

Let’s do it real simple:
Angle Alice Bob
--------------------
0º 100% 100%
22.5º 85% 85%
45º 50% 50%
67.5º 15% 15%
90º 0% 0%

This is the "prediction rates of coincidental detection", or the correlation between Alice & Bob. Angle is the relative angle between Alice & Bob. And there are no individual results, just statistics.

Happy?

Now, please deliver your LR model and percentage for the correlation, as above.

P.S. Please, don’t forget to explain in detail how this will be achieved in the real world!

ThomasT

Jul28-10, 02:48 PM

1. :rofl: You can consider my dataset requirement more of a crackpot filter. And I think it's working!Your dataset requirement is itself crackpotty. You're requiring models of entanglement to do something that they're not designed to do. To reiterate, neither LR nor QM models of entanglement predict datasets. They predict rates of detection.

In another recent thread you used your 'dataset requirement' to 'show' that LR models of individual results are incompatible with QM -- a 'result' which stands in direct contradiction to Bell. None of the other posters in that thread had any idea what you were talking about either.

2. Then perhaps you will show us your LR formula, and by the way, why don't you give us a sample dataset so we can see it in action.You've been given the opportunity to look at and critique several purported LR models, but you've refused to do so. Maybe you can present an argument that they're not local or not realistic, or that they're neither. But you can't do it by requiring them to produce datasets, because they don't predict datasets -- any more than QM does. What they do is match the QM prediction regarding rate of coincidental detection.

I will gladly do the same for QM's model.Well, that will be a neat trick, since afaik QM doesn't predict datasets, but only detection rates.

ThomasT

Jul28-10, 02:54 PM

Now, please deliver your LR model and percentage for the correlation, as above.There have been at least a couple, authored by working physicists, already presented in this thread.

P.S. Please, don’t forget to explain in detail how this will be achieved in the real world!They predict the same results that QM does for applicable experiments. As I mentioned to DrC, you might present some reason(s) why they shouldn't be considered LR models.

JesseM

Jul28-10, 03:11 PM

There have been at least a couple, authored by working physicists, already presented in this thread.
What posts are you referring to? Are you talking about models that exploit loopholes, or are you claiming there are local realist models that predict BI violations even in loophole-free experiments of the type imagined by Bell?

DrChinese

Jul28-10, 03:15 PM

There have been at least a couple, authored by working physicists, already presented in this thread.

Let's see a peer reviewed reference when it comes to non-standard science. I missed any that meet that criteria.

DevilsAvocado

Jul28-10, 04:00 PM

There have been at least a couple, authored by working physicists, already presented in this thread.
Oh yeah, could please give me a link, or are we exercising that famous swindlin' again?

Edit: I think I’ve found it:
... So, there's some room for speculation there (not that there's any way of definitively knowing whether a proposed, and viable, 'realistic' model of 'interim' photon behavior corresponds to reality). In connection with this, JenniT is developing an LR model in the thread on Bell's mathematics, and Qubix has provided a link to a proposed LR model by Joy Christian.

Okay, so JenniT (a PF user) is the "working physicists" + Joy Christian alias "Mr. Disproofs", who have no working LR model, but a whole list of disproofs (http://arxiv.org/find/all/1/all:+AND+Joy+Christian/0/1/0/all/0/1)...?

Anyway, it isn't like these are easy question/considerations.

Well, this statement seems to be a contradiction to the first line in this post: "There have been at least a couple, authored by working physicists, already presented in this thread."

... Wrt to your exercises illustrating the difficulty of understanding the optical Bell test correlations in terms of specific polarization vectors -- yes, that is a problem. It's something that probably most, or maybe all, of the readers of this thread have worked through. It suggests a few possibilities: (1) the usual notion/'understanding' of polarization is incorrect or not a comprehensive physical description, (2) the usual notion/'understanding' of spin is incorrect or not a comprehensive physical description, (3) the concepts are being misapplied or inadequately/incorrectly modelled, (4) the experimental situation is being incorrectly modelled, (5) the dynamics of the reality underlying instrumental behavior is significantly different from our sensory reality/experience, (6) there is no reality underlying instrumental behavior or underlying our sensory reality/experience, etc., etc. My current personal favorites are (3) and (4), but, of course, that could change. Wrt fundamental physics, while there's room for speculation, one still has to base any speculations on well established physical laws and dynamical principles which are, necessarily, based on real physical evidence (ie. instrumental behavior, and our sensory experience, our sensory apprehension of 'reality' -- involving, and evolving according to, the scientific method of understanding).

A lot of personal speculations, but still no working LR model. If there is one, please provide the link.
They predict the same results that QM does for applicable experiments.

Interesting, could you please describe where the "on/off button" for entangled/not entangled pairs is situated in your LR model? And how does it work?

I take it for granted that you are aware that not entangled pairs produce completely different statistics, and I wanna know what your LRM has to say about that?

(If you refer to earlier posts without linking, I take it for granted you have no answer.)

ThomasT

Jul30-10, 08:48 AM

There have been at least a couple, authored by working physicists, already presented in this thread.
Oh yeah, could please give me a link, or are we exercising that famous swindlin' again?
Swindle these:

Failure of Bell's Theorem and the Local Causality of the Entangled Photons
Joy Christian (Oxford)
http://arxiv.org/abs/1005.4932

Disproofs of Bell, GHZ, and Hardy Type Theorems and the Illusion of Entanglement
Joy Christian (Oxford)
http://arxiv.org/abs/0904.4259

Can Bell's Prescription for Physical Reality Be Considered Complete?
Joy Christian (Oxford)
http://arxiv.org/abs/0806.3078

Disproof of Bell's Theorem: Further Consolidations
Joy Christian (Perimeter and Oxford)
http://arxiv.org/abs/0707.1333

Disproof of Bell's Theorem: Reply to Critics
Joy Christian (Perimeter and Oxford)
http://arxiv.org/abs/quant-ph/0703244

Disproof of Bell's Theorem by Clifford Algebra Valued Local Variables
Joy Christian (Oxford)
http://arxiv.org/abs/quant-ph/0703179

Possible Experience: from Boole to Bell
K. Hess (Beckman Institute, Department of Electrical Engineering and Department of Physics, University of Illinois)
K Michielsen (Institute for Advanced Simulation, Julich Supercomputing Centre, Research Centre Julich)
H. De Raedt (Department of Applied Physics, Zernike Institute of Advanced Materials)
Published in: EPL, 87 (2009) 60007
http://arxiv.org/abs/0907.0767

Extended Boole-Bell inequalities applicable to quantum theory
H. De Raedt (Department of Applied Physics, Zernike Institute of Advanced Materials)
K. Hess (Beckman Institute, Department of Electrical Engineering and Department of Physics, University of Illinois)
K. Michielsen (Institute for Advanced Simulation, Julich Supercomputing Centre, Research Centre Julich)
http://arxiv.org/abs/0901.2546

Bell's Inequality: Physics meets Probability
Andrei Khrennikov (International Center for Mathematical Modelling in Physics and Cognitive Sciences, Linnaeus University)
http://arxiv.org/abs/0709.3909

A Mathematician's Viewpoint to Bell's theorem: In Memory of Walter Philipp
Andrei Khrennikov (International Center for Mathematical Modelling in Physics and Cognitive Sciences, Linnaeus University)
http://arxiv.org/abs/quant-ph/0612153

Quantum nonlocality or nonergodicity? A critical study of Bell's arguments
Andrei Khrennikov (International Center for Mathematical Modelling in Physics and Cognitive Sciences, Linnaeus University)
http://arxiv.org/abs/quant-ph/0512178

Quantum correlations from local amplitudes and the resolution of the Einstein-Podolsky-Rosen nonlocality puzzle
C. S. Unnikrishnan (Gravitation Group, Tata Institute of Fundamental Research)
http://arxiv.org/abs/quant-ph/0005103

There is no spooky action-at-a-distance in quantum correlations: Resolution of the EPR nonlocality puzzle
C. S. Unnikrishnan (Gravitation Group, Tata Institute of Fundamental Research)
http://arxiv.org/abs/quant-ph/0001112

Three-particle GHZ correlations without nonlocality
C. S. Unnikrishnan (Gravitation Group, Tata Institute of Fundamental Research)
http://arxiv.org/abs/quant-ph/0004089

Law of Malus and Photon-Photon Correlations: A Quasi-Deterministic Analyzer Model
Bill Dalton (SCSU)
http://arxiv.org/abs/quant-ph/0101127

Bell's inequality violation due to misidentification of spatially non stationary random processes
Journal-ref: Journal of Modern Optics, 2003, Vol. 50, No. 15-17, 2465-2474
Louis Sica (Naval Research Laboratory, Washington, D. C.)
http://arxiv.org/abs/quant-ph/0305071

Bell's inequalities I: An explanation for their experimental violation
Journal-ref: Optics Communications 170 (1999) 55-60
Louis Sica (Naval Research Laboratory, Washington, D. C.)
http://arxiv.org/abs/quant-ph/0101087

Bell's inequalities II: logical loophole in their interpretation
Journal-ref: Optics Communications 170 (1999) 61-66
Louis Sica (Naval Research Laboratory, Washington, D. C.)
http://arxiv.org/abs/quant-ph/0101094

Correlations for a new Bell's inequality experiment
Journal-ref: Foundations of Physics Letters, Vol. 15, No. 5, 473 (2002).
Louis Sica (Naval Research Laboratory, Washington, D. C.)
http://arxiv.org/abs/quant-ph/0211031

There are a couple of purported LR models in the bunch. When you've finished reading and critiquing these, and given us your conclusions and recommendations, then I have some more for you to look at. Some of them go back quite a few years, but then Bell's papers were published almost half a century ago.

Of course, nobody was too worried about nature being nonlocal pre Bell, and it seems that nobody's too worried about it post Bell either. After all, there's really no way to know. It's all in how one interprets the logic involved. So, be sure to pay particular attention to the papers that address that.

Anyway, it isn't like these are easy question/considerations.
Well, this statement seems to be a contradiction to the first line in this post: "There have been at least a couple, authored by working physicists, already presented in this thread."Exactly how do these statements contradict each other? Logic, or rather illogic, of this sort will undoubtedly lead you down the wrong path.

A lot of personal speculations, but still no working LR model. If there is one, please provide the link.They've been in the thread for quite a while. Why am I not surprised that you didn't read them? They're included in the links above. After you read them, to be fair, I think that we might both agree that calling them LR models is a bit of a stretch. Anyway, whether an LR model of entanglement is possible isn't going to tell us that nature is local any more than a nonlocal model of entanglement tells us that nature is nonlocal. The important question is: how can we infer anything about fundamental reality from the arithmetized Boolean logic constituting Bell, GHZ, and Hardy type theorems? And the point of most of the papers linked to is that we can't. This is actually good news for those who have chosen to believe that nature is nonlocal. It means that they can remain steadfast in their belief, or rather faith, that nature is nonlocal (whatever that might possibly mean). It's also impossible to 'prove' that entanglement correlations are or aren't caused by really fast sub-quantum bike messengers -- though there are some very good reasons not to believe that, just as there are some very good reasons to believe that entanglement correlations can happen via fundamental dynamics constrained by the principle of local action.

They predict the same results that QM does for applicable experiments.
Interesting, could you please describe where the "on/off button" for entangled/not entangled pairs is situated in your LR model? And how does it work?I don't have an LR model, and don't recall ever saying that I did. However, some professional physicists do. Their models are linked to above.

(If you refer to earlier posts without linking, I take it for granted you have no answer.)Well, now you have some stuff to look at. Have fun.

DrChinese

Jul30-10, 09:11 AM

Swindle these:

...

However, some professional physicists do. Their models are linked to above.

That's actually a very poor list, but I will give you this: it's about as good as you could possibly come up with. So you get an A-. I can give you some more names if you like. In fact, Khrennikov had a new paper this week on how 4th order effects cause photons not to be detected.

Most of those are the same authors, and only a few are peer reviewed. The only one I think worth reading is the De Raedt, and that is simply because it is a computer model. If you study it, you will realize how difficult the modeling issue really is. Bell is respected with it - the only one of the lot I believe. Which is to say that their model does not claim to match QM.

DevilsAvocado

Jul30-10, 09:57 AM

Swindle these:

Why 19 papers? If I were wrong, then one would have been enough! :smile:

Exactly how do these statements contradict each other? Logic, or rather illogic, of this sort will undoubtedly lead you down the wrong path.

Well, if you do have 19 papers proving the same (or 19 different) fully functional LR models, the LRM subject could hardly be characterized as: "Anyway, it isn't like these are easy question/considerations."

You, I and anyone else would then completely natural have stated: "Well, it may look like a difficult question, but that fact is that there are 19 papers proving a working LR model, in detail. So the LRM question is already solved, and perfectly clear to the scientific community."

Capice?

They've been in the thread for quite a while. Why am I not surprised that you didn't read them? They're included in the links above.

Why should I read all these 19 papers?

After you read them, to be fair, I think that we might both agree that calling them LR models is a bit of a stretch.

Ahh! Sorry, you’ve already gave me the answer: "calling them LR models is a bit of a stretch"

Conclusion: There is absolutely no reason for me to spend time, looking for a working LR model in your 19 papers – because there is none. Thanks for saving me the time!

I don't have an LR model, and don't recall ever saying that I did. However, some professional physicists do. Their models are linked to above.

I do think you need that break you were mentioning here (http://www.physicsforums.com/showpost.php?p=2820096&postcount=24), because now you are making contradictory statements in the same post:
calling them LR models is a bit of a stretch

?:bugeye:?

Well, now you have some stuff to look at. Have fun.

I don’t want to hurt your feelings – but I’m laughing already! :smile:

Take a break. Think it over. Come back as a new man, in possession of that wonderful word "Maybe".

Take care! :wink:

billschnieder

Jul30-10, 10:37 PM

Most of those are the same authors, and only a few are peer reviewed. The only one I think worth reading is the De Raedt, and that is simply because it is a computer model. If you study it, you will realize how difficult the modeling issue really is. Bell is respected with it - the only one of the lot I believe. Which is to say that their model does not claim to match QM.

Huh?

Shuang Zhao · Hans De Raedt · Kristel Michielsen
"Event-by-Event Simulation of Einstein-Podolsky-Rosen-Bohm Experiment"
Found Phys (2008) 38: 322–347
http://arxiv.org/abs/0712.3693

Abstract:
We construct an event-based computer simulation model of the Einstein-Podolsky-Rosen-Bohm experiments with photons. The algorithm is a one-to-one copy of the data gathering and analysis procedures used in real laboratory experiments. We consider two types of experiments, those with a source emitting photons with opposite but otherwise unpredictable polarization and those with a source emitting photons with fixed polarization. In the simulation, the choice of the direction of polarization measurement for each detection event is arbitrary. We use three different procedures to identify pairs of photons and compute the frequency of coincidences by analyzing experimental data and simulation data. The model strictly satisfies Einstein's criteria of local causality, does not rely on any concept of quantum theory and reproduces the results of quantum theory for both types of experiments. We give a rigorous proof that the probabilistic description of the simulation model yields the quantum theoretical expressions for the single- and two-particle expectation values.

H. De Raedt, K. De Raedt, K. Michielsen, K. Keimpema, S. Miyashita
J. Comp. Theor. Nanosci. 4, 957 - 991, (2007)
"Event-by-event simulation of quantum phenomena: Application to Einstein-Podolosky-Rosen-Bohm experiments"
http://arxiv.org/abs/0712.3781

We review the data gathering and analysis procedure used in real Einstein-Podolsky-Rosen-Bohm experiments with photons and we illustrate the procedure by analyzing experimental data. Based on this analysis, we construct event-based computer simulation models in which every essential element in the experiment has a counterpart. The data is analyzed by counting single-particle events and two-particle coincidences, using the same procedure as in experiments. The simulation models strictly satisfy Einstein's criteria of local causality, do not rely on any concept of quantum theory or probability theory, and reproduce all results of quantum theory for a quantum system of two $S=1/2$ particles. We present a rigorous analytical treatment of these models and show that they may yield results that are in exact agreement with quantum theory. The apparent conflict with the folklore on Bell's theorem, stating that such models are not supposed to exist, is resolved. Finally, starting from the principles of probable inference, we derive the probability distributions of quantum theory of the Einstein-Podolsky-Rosen-Bohm experiment without invoking concepts of quantum theory.

K. Michielsen, S. Yuan, S. Zhao, F. Jin, H. De Raedt
"Coexistence of full which-path information and interference in Wheelers delayed choice experiment with photons"
Physica E, Volume 42, Issue 3, January 2010, Pages 348-353
http://arxiv.org/abs/0908.1032
We present a computer simulation model that is a one-to-one copy of an experimental realization of Wheeler's delayed-choice experiment that employs a single photon source and a Mach–Zehnder interferometer composed of a 50/50 input beam splitter and a variable output beam splitter with adjustable reflection coefficient R [V. Jacques, E. Wu, F. Grosshans, F. Treussart, P. Grangier, A. Aspect, J.-F. Roch, Phys. Rev. Lett. 100 (2008) 220402]. For 0<=R<=0.5, experimentally measured values of the interference visibility V and the path distinguishability D, a parameter quantifying the which-path information (WPI), are found to fulfill the complementary relation V2+D2less-than-or-equals, slant1, thereby allowing to obtain partial WPI while keeping interference with limited visibility. The simulation model that is solely based on experimental facts that satisfies Einstein's criterion of local causality and that does not rely on any concept of quantum theory or of probability theory, reproduces quantitatively the averages calculated from quantum theory. Our results prove that it is possible to give a particle-only description of the experiment, that one can have full WPI even if D=0, V=1 and therefore that the relation V^2+D^2<=1 cannot be regarded as quantifying the notion of complementarity.

Extended Boole-Bell inequalities applicable to quantum theory
Authors: Hans De Raedt, Karl Hess, Kristel Michielsen
http://arxiv.org/abs/0901.2546
In conclusion:

We have shown in a series of papers42,43,47,48,59 that it is possible to construct models, that is algorithms, that are locally causal in Einstein’s sense, generate the data set Eq. (126) and reproduce exactly the correlation that is characteristic for a quantum system in the singlet state. These algorithms can be viewed as concrete realizations of Fine’s synchronization model8. According to Bell’s theorem, such models do not exist. This apparent paradox is resolved by the work presented in this paper: There exists no Bell inequality for triples of pairs, there are only EBBI for pairs extracted from triples.
...
The central result of this paper is that the necessary conditions and the proof of the inequalities of Boole for n-tuples of two-valued data (see Section II) can be generalized to real non negative functions of two-valued variables (see Section III) and to quantum theory of two-valued dynamical variables (see Section IV). The resulting inequalities, that we refer to as extended Boole-Bell inequalities (EBBI) for reasons explained in the Introduction and in Section III, have the same form as those of Boole and Bell. Equally central is the fact that
these EBBI express arithmetic relations between numbers that can never be violated by a mathematically correct treatment of the problem: These inequalities derive from the rules of arithmetic and the non negativity of some functions only. A violation of these inequalities is at odds with the commonly
accepted rules of arithmetic or, in the case of quantum theory, with the commonly accepted postulates of quantum theory.
...
A violation of the EBBI cannot be attributed to influences at a distance. The only possible way that a viola-
tion could arise is if grouping is performed in pairs (see Section VII A).

I will just assume that you did not know what you were talking about. And in case you forgot, you still have not addressed a single point of my argument.

DevilsAvocado

Jul31-10, 08:30 AM

http://upload.wikimedia.org/wikipedia/commons/3/3d/Horse_simulator_WWI.jpg
Wooden mechanical horse simulator during WWI.

RUTA

Jul31-10, 11:11 AM

billschnieder

Jul31-10, 02:05 PM

billschnieder,

I read

Shuang Zhao · Hans De Raedt · Kristel Michielsen
"Event-by-Event Simulation of Einstein-Podolsky-Rosen-Bohm Experiment"
Found Phys (2008) 38: 322–347
http://arxiv.org/abs/0712.3693

I did not spend the hrs it would take me to reproduce all the calculations, so maybe I'm missing something. If so, hopefully you can correct me. Here is what I understand from the paper:

1. Given the manner by which experiments X and Y were carried out and the data analyzed, one cannot rule out local realism (LR).

2. They prove this by constructing an LR simulator which produces data that, when analyzed per the techniques of X and Y, violates Bell's inequality, i.e., gives |S| > 2.

3. They have NOT shown that it is possible to obtain |S| > 2 with an LR model in theory. What they HAVE shown is that it's impossible to rule out an LR model in experiments X and Y which found |S| > 2.

1) and 2) You are correct. In that paper you referred to, they constructed a LR model which violates Bell inequality and agrees with QM.

3) Not quite. In the last I pointed to, they have shown that for purely mathematical reasons, it is not possible to apply Bell-type inequalities to the original EPRB type experiments where only pairs of data are recorded. They have shown by extending the thought experiment such that triples can be measured, and demonstrated that the inequalities are never violated even by QM.

They conclude (page 29):

In the original EPRB though experiment, one can measure pairs of data only, making de-facto impossible to use Boole's inequalities properly. This obstacle is remove in the extended EPRB though experiment discussed in Section VIC. In this extended EPRB experiment, one can measure both pairs and triples and consequantly, it is impossible for the data to violate Boole's inequalities. This statement is generally true: It does not depend on whether the internal dynamics of the apparatuses induces some correlations among different triples or that there are influences at a distance. The fact that this experiment yields triples of two-valued numbers is sufficient to guarantee that Boole's inequalities cannot be violated

The rigorous quantum theoretical treatment of a quantum flux tunneling problem (see Section V) and the EPRB experiment (see Section VI) provide explicit examples that quantum theory can never give rise to violations of the extended boole-bell inequalities

DevilsAvocado

Jul31-10, 05:27 PM

I did not spend the hrs it would take me to reproduce all the calculations, so maybe I'm missing something.

I think what you may have missed is that Mr. BS is a very big fan of Crackpot Kracklauer:

http://i32.tinypic.com/1174vo9.jpg

And he will say and do anything to deceive you there is a real functional LR model. At least ThomasT has the decency to give you a hint ...
calling them LR models is a bit of a stretch
... on what this is all about ...

3. They have NOT shown that it is possible to obtain |S| > 2 with an LR model in theory. What they HAVE shown is that it's impossible to rule out an LR model in experiments X and Y which found |S| > 2.

Absolutely correct. As we all know – this is a computer simulation, nothing more nothing less. And I must say they use very "fancy" words:
Abstract:
We construct an event-based computer simulation model of the Einstein-Podolsky-Rosen-Bohm experiments with photons. The algorithm is a one-to-one copy of the data gathering and analysis procedures used in real laboratory experiments.

I don’t know about the algorithm in the paper, but the algorithm in the actual computer program is NOT "a one-to-one copy of the data gathering and analysis procedures used in real laboratory experiments".

There is actually one little line of code that does all the "magic":

http://i49.tinypic.com/6oztpt.png

There is absolutely no real "time window", only a pseudo-random number in r0, and this has nothing to do with real experiments – it’s just a case of trial & error and fine-tuning.

Don’t waste your time looking for a real LR model in this computer simulation – you never gonna find it.

RUTA

Jul31-10, 05:49 PM

1) and 2) You are correct. In that paper you referred to, they constructed a LR model which violates Bell inequality and agrees with QM.

3) Not quite. In the last I pointed to, they have shown that for purely mathematical reasons, it is not possible to apply Bell-type inequalities to the original EPRB type experiments where only pairs of data are recorded. They have shown by extending the thought experiment such that triples can be measured, and demonstrated that the inequalities are never violated even by QM.

Let's keep the conversation focused on Found Phys (2008) 38: 322–347. We can discuss the last paper later. Is this correct:

They have NOT shown that it is possible to obtain |S| > 2 with an LR model in theory. What they HAVE shown is that it's impossible to rule out an LR model in experiments X and Y which found |S| > 2.

nismaratwork

Jul31-10, 06:13 PM

Let's keep the conversation focused on Found Phys (2008) 38: 322–347. We can discuss the last paper later. Is this correct:

They have NOT shown that it is possible to obtain |S| > 2 with an LR model in theory. What they HAVE shown is that it's impossible to rule out an LR model in experiments X and Y which found |S| > 2.

That is a beautiful example of rendering nearly a page of bluster down to a single coherent principle. As a reader of this thread, I thank you.

RUTA

Jul31-10, 06:33 PM

Don’t waste your time looking for a real LR model in this computer simulation – you never gonna find it.

I doubt they have an LR model that yields |S| > 2. If someone had managed to create such a model, it would've sent at very least a ripple though the foundations community and I haven't heard anything about it. I've only read the 2008 FoP paper, so I can only comment on that paper at this time.

In that paper they don't claim to have an LR model that yields |S| > 2. You have to read the paper very carefully so as not to misinterpret their statements. What they DO have is an LR model that generates data which, when subjected to data analysis per a couple of legit EPR-Bell experiments, yields |S| > 2. So, what can you conclude from this? Well, you CANNOT conclude that LR models can violate Bell's inequality. Only that LR models can APPEAR to violate Bell's inequality under certain experimental conditions.

If in fact their calculations are correct (again, I didn't check them, but they were published so I'm willing to give the referees and editor of FoP some credit), I think their work is very good physics and deserved to be published. Their conclusion, while not the "LR savior" anti-EPR advocates are looking for, is not insignificant. I'm going to speculate, hoping someone can correct me if I'm way off (I may be).

The "loop hole" they found has to do with the fact that there is a low coincidence frequency, i.e., the experiment has hundreds of thousands of events but only about 13,000 coincidences. Superficially, of course, that means your LR model need only yield |S| > 2 for the "right" 13,000-element subset of its data. Anyone disagree?

I actually think their work is "cool" and I'm glad someone is doing this dirty "police" work. If I had refereed this paper and found all the calculations to be correct, I would've recommended publication. I think this kind of work is important.

DevilsAvocado

Jul31-10, 07:33 PM

I doubt they have an LR model that yields |S| > 2. If someone had managed to create such a model, it would've sent at very least a ripple though the foundations community and I haven't heard anything about it. I've only read the 2008 FoP paper, so I can only comment on that paper at this time.

Yeah, and why not a front page in Nature or Scientific American!? :wink:

In that paper they don't claim to have an LR model that yields |S| > 2.

This is something Mr. BS must have missed...!:uhh:? (:biggrin:)

You have to read the paper very carefully so as not to misinterpret their statements. What they DO have is an LR model that generates data which, when subjected to data analysis per a couple of legit EPR-Bell experiments, yields |S| > 2. So, what can you conclude from this? Well, you CANNOT conclude that LR models can violate Bell's inequality. Only that LR models can APPEAR to violate Bell's inequality under certain experimental conditions.

Very interesting! I know DrC is working hard on this, and he made a version for Excel (http://www.physicsforums.com/showpost.php?p=2724402&postcount=389) to analyze the data.

The "loop hole" they found has to do with the fact that there is a low coincidence frequency, i.e., the experiment has hundreds of thousands of events but only about 13,000 coincidences. Superficially, of course, that means your LR model need only yield |S| > 2 for the "right" 13,000-element subset of its data. Anyone disagree?

I can’t say for certain, but I know DrC is going to love to discuss this. As far as I understand, they are exploiting the "time window" in a way that the angle is 'responsible' for the amount of random "add-ons". But I can definitely be wrong. We have to wait for DrC.

I actually think their work is "cool" and I'm glad someone is doing this dirty "police" work. If I had refereed this paper and found all the calculations to be correct, I would've recommended publication. I think this kind of work is important.

Yes, it’s cool, but I don’t think it’s cool what Mr. BS is doing – claiming this is proof of a real LR model.

RUTA

Jul31-10, 09:07 PM

Yes, it’s cool, but I don’t think it’s cool what Mr. BS is doing – claiming this is proof of a real LR model.

It's no proof of an LR model for Bell inequality violations. It's value resides in that it shows why a particular pair of experiments cannot rule out LR models. At least that's what I see.

billschnieder

Aug1-10, 10:43 AM

They have NOT shown that it is possible to obtain |S| > 2 with an LR model in theory. What they HAVE shown is that it's impossible to rule out an LR model in experiments X and Y which found |S| > 2.

It is clear to me from their paper that
a) They have provided an "LR model" of the experiments under consideration. (Section V)
b) For the two types of experiments they considered, they showed that their model agrees with the QM prediction and violates Bell for some values of d. (Section IV)

Let us assume that we can analyze our simulation model, described in Section V, by
replacing the deterministic sequence of pseudo-random numbers by the mathematical con-
cept of independent random variables, as defined in the (Kolmogorov) theory of probabil-
ity [29, 30]. Under this assumption, each event constitutes a Bernouilli trial [29, 30] and we
can readily obtain analytical expressions for the expectation values that we compute with
the simulation model.
This section serves three purposes. First, it provides a rigorous proof that for up to first
order in W and for d = 4, the probabilistic description of the simulation model exactly
reproduces the single particle averages and the two-particle correlations of quantum theory
for the system under consideration. Second, it illustrates how the presence of the time-
window introduces correlations that cannot be described by the original Bell-like “hidden-
variable” models [14]. Third, it reveals a few hidden assumptions that are implicit in the
derivation of the specific, factorized form of the two-particle correlation that is essential to
Bell’s work.

The authors are not ambiguous about what they claim to have demonstrated. At least to me, it is clear that they have a LR model which violates Bell's inequalities but agrees with QM.

Summarizing: We have demonstrated that a simulation model that strictly satisfies Ein-
stein’s criteria of locality can reproduce, event-by-event, the quantum theoretical results for
EPRB experiments with photons, without using any concept from quantum theory. We
have given a rigorous proof that this model reproduces the single-particle expectations and
the two-particle correlation of two S = 1/2 particles in the singlet state and product state.

If you do not think they have presented an LR model which agrees with QM and disagrees with Bell for the two types of experiments they considered, you will have to clarify what you mean by
1) LR Model
2) obtain |S| > 2 in theory

DevilsAvocado

Aug1-10, 11:01 AM

OMG, here we go again. Perception and logic at the level of a 10-yearold, now we can "look forward" to >100 posts on this...

JesseM

Aug1-10, 11:04 AM

It is clear to me from their paper that
a) They have provided an "LR model" of the experiments under consideration. (Section V)
b) For the two types of experiments they considered, they showed that their model agrees with the QM prediction and violates Bell for some values of d. (Section IV)
The two types of experiments they considered are ones that contain experimental loopholes. They do not show in that paper that a LR model could violate Bell inequalities even in a loophole-free experiment that satisfied all the experimental conditions assumed by Bell. Note on p. 4 where they say:
The crucial
point of the present and of our earlier work [15, 21, 22, 23] is that we simulate a model of
the real EPRB experiments, not of the simpliﬁed, gedanken-type version that is commonly
used [17, 18, 19].
Also note that DrChinese did a detailed analysis of the De Raedt model on this thread (http://www.physicsforums.com/showthread.php?t=369286), and concluded in post #47:
I have been working with the De Raedt team for several months to address the issue identified in this thread. Thanks especially to Dr. Kristel Michielsen for substantial time and effort to work with me on this.

The issue I identified was rectified very quickly using what they call their "Model 2" algorithm. My earlier analysis was using their older "Model 1" algorithm. After getting to the point where we were able to compare statistics for a jointly agreed upon group of settings, I am satisfied that they have a simulation which accomplishes - in essence - what they claim.

...

Please keep in mind that the De Raedt model is a computer simulation which exploits the coincidence time window as a means to achieve a very interesting result: It is local realistic. Therefore, it is able to provide event by event detail for 3 (or more) suimultaneous settings (i.e. it is realistic). It does this with an algorithm which is fully independent (i.e. local/separable). It does not violate a Bell Inequality for the full universe but does (somewhat) for the sample.
So, seems to be exploiting some variant of the detector efficiency loophole.

billschnieder

Aug1-10, 11:20 AM

The two types of experiments they considered are ones that contain experimental loopholes. They do not show in that paper that a LR model could violate Bell inequalities even in a loophole-free experiment that satisfied all the experimental conditions assumed by Bell.

I take it you believe it is possible to perform an EPRB experiment which is 100% faithful to all of Bell's assumptions. For reasons I have already explained, I do not share that belief. The fact that no such experiment has ever been performed is definitely telling.

And since non-localists rely on the same "loopholed experiments" to proclaim the demise of locality, a locally causal explanation of those same experiments however "loopholed" they are, is an effective counter argument. So contrary to what you might think, the fact that the experiments so modelled, are not loophole free, is not a serious response to the model.

So, seems to be exploiting some variant of the detector efficiency loophole.
No. Read the paper! I should also say I simply enjoy your choice of words here: "exploiting .. loophole". When
Weihs et al. did their experiments and published the result, I did not hear non-localists clamouring that they "exploited ... loophole".

Also note that DrChinese did a detailed analysis of the De Raedt model on this thread, and concluded in post #47:
You mean the same DrChinese who said contrary to what the authors themselves explicitly claimed in the paper that:
The only one I think worth reading is the De Raedt,... Bell is respected with it - the only one of the lot I believe. Which is to say that their model does not claim to match QM.

JesseM

Aug1-10, 11:38 AM

I take it you believe it is possible to perform an EPRB experiment which is 100% faithful to all of Bell's assumptions.
It would be possible (in principle) to perform an experiment 100% faithful to all his assumptions about the observable conditions of the experiment, yes. Of course the experiment need not match the theoretical assumptions about hidden variables, since the whole point would be to compare a real experiment which matches these observable experimental conditions to what LR hidden-variables theories would predict about an experiment which matches these observable experimental conditions.

And since theorists have come up with modified Bell inequalities that deal with imperfect detector efficiency, it's really only necessary to perform an experiment where the detector efficiency is above a certain threshold, it doesn't have to be perfect as assumed in the original Bell inequalities. As we've discussed before, there have been experiments that got the detector efficiency above such a threshold, although they didn't simultaneously close the locality loophole (and we've also discussed why I think it's very unlikely the true laws of physics would be a hidden-variable theory that exploits both loopholes simultaneously, and why I think it's likely that experiments closing both loopholes will be possible in the near future).
And since non-localists rely on the same "loopholed experiments" to proclaim the demise of locality, a locally causal explanation of those same experiments however "loopholed" they are, is an effective counter argument.
Not if the De Raedt model fails to simultaneously exploit the locality loophole (or it does but requires a very contrived and complicated algorithm).
So, seems to be exploiting some variant of the detector efficiency loophole.
No. Read the paper!
I'm trusting DrChinese's analysis, unless you can show where it's wrong--do you claim there is some section of the paper that demonstrates that every simulated photon emitted by the source is actually detected? If so, perhaps you could quote that section?
You mean the same DrChinese who said contrary to what the authors themselves explicitly claimed in the paper that:
The only one I think worth reading is the De Raedt,... Bell is respected with it - the only one of the lot I believe. Which is to say that their model does not claim to match QM.
Where do the authors "explicitly claim" otherwise? Keep in mind the context, DrChinese would presumably say here that a model which violates the Bell inequalities in experiments with loopholes but respects them in loophole-free experiments is still a model where "Bell is respected". So the fact that the authors may talk about how Bell inequalities are violated doesn't mean that they would disagree that "Bell is respected" in the sense which DrChinese meant that phrase.

DevilsAvocado

Aug1-10, 11:54 AM

So, seems to be exploiting some variant of the detector efficiency loophole.

I can only tell about the version DrC made for Excel, which you can download here (http://www.physicsforums.com/showpost.php?p=2724402&postcount=389), and I assume it’s their older "Model 1" algorithm.

The one and only 'thing' that can be responsible for the achieved result, is in what they call the "time window", and a pseudo-random number in r0 that is altered depending on the current angle:

http://i49.tinypic.com/6oztpt.png

I guess that only Mr. BS would call this a real LR model, explaining a real underlying theory in nature...

billschnieder

Aug1-10, 12:00 PM

It would be possible (in principle) to perform an experiment 100% faithful to all his assumptions about the observable conditions of the experiment, yes.
I disagree that this is possible, as I explained in post #1076:
http://www.physicsforums.com/showpost.php?p=2804344&postcount=1076

And since theorists have come up with modified Bell inequalities that deal with imperfect detector efficiency ...
Completely irrelevant. The simulation model is not dealing with detection efficiency loophole. It deals with the coincidence time window, or if you prefer "coincidence time loophole".

Not if the De Raedt model fails to simultaneously exploit the locality loophole (or it does but requires a very contrived and complicated algorithm).

Huh? What are you talking about?

I'm trusting DrChinese's analysis, unless you can show where it's wrong--do you claim there is some section of the paper that demonstrates that every simulated photon emitted by the source is actually detected? If so, perhaps you could quote that section?
Again this doesn't make sense because De Raedt were modelling an actual experiment, so expecting them make their model so it deliberately does not correspond to what is actually done and observed in the real experiment is queer. If in a real experiment only 5% of photons are detected, and a model is presented for the experiment in which 100% of photons are detected, that will be grounds for invalidating the model. This is simple logic and how science is normally done.
We construct an event-based computer simulation model of the Einstein-Podolsky-Rosen-Bohm
experiments with photons. The algorithm is a one-to-one copy of the data gathering and analysis
procedures used in real laboratory experiments. We consider two types of experiments, those with a source emitting photons with opposite but otherwise unpredictable polarization and those with a source emitting photons with fixed polarization. In the simulation, the choice of the direction of polarization measurement for each detection event is arbitrary. We use three different procedures to identify pairs of photons and compute the frequency of coincidences by analyzing experimental data and simulation data. The model strictly satisfies Einstein’s criteria of local causality, does not rely on any concept of quantum theory and reproduces the results of quantum theory for both types of experiments. We give a rigorous proof that the probabilistic description of the simulation model yields the quantum theoretical expressions for the single- and two-particle expectation values.

Feel free to trust DrC's analysis. To me the simple fact that he misrepresents their explicitly stated claims is disqualifying.

You can swindle "Bell is respected with it ... Which is to say that their model does not claim to match QM" all you want. The authors' claims are pretty clear. Read the paper yourself and see if you still agree with DrC that their model does not claim to match QM.
Summarizing: We have demonstrated that a simulation model that strictly satisfies Ein-
stein’s criteria of locality can reproduce, event-by-event, the quantum theoretical results for
EPRB experiments with photons, without using any concept from quantum theory. We
have given a rigorous proof that this model reproduces the single-particle expectations and
the two-particle correlation of two S = 1/2 particles in the singlet state and product state.

JesseM

Aug1-10, 12:41 PM

It would be possible (in principle) to perform an experiment 100% faithful to all his assumptions about the observable conditions of the experiment, yes. Of course the experiment need not match the theoretical assumptions about hidden variables, since the whole point would be to compare a real experiment which matches these observable experimental conditions to what LR hidden-variables theories would predict about an experiment which matches these observable experimental conditions.
I disagree that this is possible, as I explained in post #1076:
http://www.physicsforums.com/showpost.php?p=2804344&postcount=1076
Your argument there is based on a failure to distinguish "assumptions about the observable conditions of the experiment" from "theoretical assumptions about hidden variables"--this sort of confusion is common in your arguments, which is exactly why I phrased my comment in the way I did.

In a case like the Leggett-Garg inequality, the "observable conditions of the experiment" include the idea that on each trial we measure the system at two out of three possible times. Then an inequality is derived based on the theoretical assumption that the system has a well-defined state at all three times (and that the state isn't influenced by your measurements), even the time that we don't actually measure. So if you want to test the theoretical assumption, you do an experiment that matches the specified "observable conditions", and if you find the inequality is violated, that falsifies the theoretical assumption that each measured system had a well-defined state at all three times which wasn't influenced by the measurements.

You earlier showed that you understood the idea of my scratch lotto card example--in that example, each experimenter had a card with three possible boxes (for a total of six boxes), but the experiment only involved each scratching one box (a total of two boxes revealed). The theoretical assumption being tested was that there was an unchanging "hidden fruit" behind all six boxes, and the conclusion was that if experiments always found the same fruit on trials where both experimenters chose the same box, then on trials where both experimenters chose different boxes they should find the same fruit at least 1/3 of the time. If they perform this experiment many times (with perfect 'efficiency' so no cards have to be thrown out) and find that they only get the same fruit 1/4 of the time when they choose different boxes, isn't this a valid falsification of the hypothesis that there was an unchanging hidden fruit behind all six boxes? You wouldn't say the experiment failed to show anything because they assumed six variables with well-defined values but only sampled two, would you?
Completely irrelevant. The simulation model is not dealing with detection efficiency loophole. It deals with the coincidence time window, or if you prefer "coincidence time loophole".
Does the computer model assume every emitted photon is detected? If not, why are you so sure they aren't exploiting this loophole? Anyway, you may be right that they exploit the coincidence-time loophole, a slightly different experimental loophole I hadn't been thinking of (discussed here (http://arxiv.org/abs/quant-ph/0312035)). I think you could view it as a type of detector efficiency loophole in any case, since it means that the detectors aren't correctly identifying all entangled pairs as pairs.
Not if the De Raedt model fails to simultaneously exploit the locality loophole (or it does but requires a very contrived and complicated algorithm).
Huh? What are you talking about?
I was responding to your statement 'since non-localists rely on the same "loopholed experiments" to proclaim the demise of locality, a locally causal explanation of those same experiments however "loopholed" they are, is an effective counter argument.' A model is not an "effective counter argument" if it can't actually explain all the different types of experimental results seen so far, including the experiments where the detector efficiency loophole was closed but the locality loophole was not.
I'm trusting DrChinese's analysis, unless you can show where it's wrong--do you claim there is some section of the paper that demonstrates that every simulated photon emitted by the source is actually detected? If so, perhaps you could quote that section?
Again this doesn't make sense because De Raedt were modelling an actual experiment, so expecting them make their model so it deliberately does not correspond to what is actually done and observed in the real experiment is queer.
I'm not "expecting them" to do anything different than what they did. I was responding to your comment "No. Read the paper!" in response to my comment "seems to be exploiting some variant of the detector efficiency loophole." If you were denying that they exploited the detector efficiency loophole, wouldn't that mean you were claiming that their model assumed conditions of perfectly efficient detection?
Feel free to trust DrC's analysis. To me the simple fact that he misrepresents their claims is disqualifying.
But he doesn't misrepresent their claims, his claim is perfectly correct if you understand what he means by "Bell is respected" (namely, that their model would obey Bell inequalities in an experimental setup that actually matched the observable experimental conditions assumed by Bell). If you're just saying that the claim "Bell is respected" would be wrong if we had a different interpretation of the meaning of that phrase, then you're just quibbling over DrChinese's choice of language, not saying his discussion is wrong in any more substantive sense.

RUTA

Aug1-10, 01:20 PM

It is clear to me from their paper that
a) They have provided an "LR model" of the experiments under consideration. (Section V)
b) For the two types of experiments they considered, they showed that their model agrees with the QM prediction and violates Bell for some values of d. (Section IV)

The authors are not ambiguous about what they claim to have demonstrated. At least to me, it is clear that they have a LR model which violates Bell's inequalities but agrees with QM.

If you do not think they have presented an LR model which agrees with QM and disagrees with Bell for the two types of experiments they considered, you will have to clarify what you mean by
1) LR Model
2) obtain |S| > 2 in theory

I suspect we agree on what constitutes an LR model and that indeed they have an LR model. We should also agree that the data provided by their LR model yields |S| > 2 when subjected to the analysis in question. Where we might disagree is on whether or not they have an LR model that yields |S| > 2 in theory.

That is to say, their LR model can produce unambiguous pairs of events, so there is no need in theory to use the experimental procedure for finding correlated events -- they can easily program their data so that every pair of events is correlated (whereas only a tiny fraction of those under experimental analysis are correlated). Under this type of analysis their LR model will not produce |S| > 2.

So, again, they have not found an LR model that violates Bell's inequality. What they have found is a loop hole in these two particular experiments whereby an LR model can appear to violate Bell's inequality because of the analysis that must be used in a real experiment when you don't know which pairs of events are correlated. Again, this limitation is NOT applicable to their LR model because they CAN know which events are correlated in their model and, using this knowledge, they can easily show that their LR model doesn't violate Bell's inequality.

billschnieder

Aug1-10, 02:00 PM

Your argument there is based on a failure to distinguish "assumptions about the observable conditions of the experiment" from "theoretical assumptions about hidden variables"--this sort of confusion is common in your arguments, which is exactly why I phrased my comment in the way I did.
My argument is broken down into points as follows:

1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!

If you are now seriously considering responding to it, please clearly point out which of the above points is wrong and why it is wrong. I could not discern a clear response against any of the above points in anything you have written.

Does the computer model assume every emitted photon is detected? If not, why are you so sure they aren't exploiting this loophole?
Had you read the paper, you will have understood this. They have a single parameter dwhich corresponds to the coincidence time window, and they clearly show that with values of d similar to what is used in real experiments, Bell is violated and the simulation agrees with QM but if no coincidence time window is introduced ie d = 0, which is NOT what is done in real experiments, the simulation respects Bell and disagrees with QM, even though not all photons are detected. So yeah, I am pretty sure that their simulation has nothing to do with detection efficiency, and you will be too if only you read the article.

A model is not an "effective counter argument" if it can't actually explain all the different types of experimental results seen so far, including the experiments where the detector efficiency loophole was closed but the locality loophole was not.
Again, despite your wishes, this model has nothing to do with detector efficiency.

his claim is perfectly correct if you understand what he means by "Bell is respected" (namely, that their model would obey Bell inequalities in an experimental setup that actually matched the observable experimental conditions assumed by Bell).
Exactly zero such experimental setups have been realized to date. They present a model of a real experimental setup and THEY CLAIM that their model agrees with QM as evidenced by their own words which I have quoted to you. You can disagree with their claims but you certainly can not say they claim the opposite to what they actually claim, by introducing some other setup, which has never been realized and which they never set out to model. Dr C is free to state that in his opinion, their model agrees with Bell and disagrees with QM. But to say their model does not claim to match QM is false. The former states an opinion about their model, the latter purports to represent their claims but does not. This is obvious, and no amount of quibbling can change this. So feel free to continue the quibbling but count me out of it.

billschnieder

Aug1-10, 02:26 PM

I suspect we agree on what constitutes an LR model and that indeed they have an LR model. We should also agree that the data provided by their LR model yields |S| > 2 when subjected to the analysis in question. Where we might disagree is on whether or not they have an LR model that yields |S| > 2 in theory.

That is to say, their LR model can produce unambiguous pairs of events, so there is no need in theory to use the experimental procedure for finding correlated events -- they can easily program their data so that every pair of events is correlated (whereas only a tiny fraction of those under experimental analysis are correlated). Under this type of analysis their LR model will not produce |S| > 2.

So, again, they have not found an LR model that violates Bell's inequality.
Would you say the Weihs et al experiment violated Bell's inequality and agreed with QM, or would you say the Weihs et al experiment appeared to violate Bell's inequality because it exploited the coincidence time loophole? If you have no problem with this interpretation of the Weihs et all experiment, which they are modelling, I see not reason to expect anything different about their model.

What they have found is a loop hole in these two particular experiments whereby an LR model can appear to violate Bell's inequality because of the analysis that must be used in a real experiment when you don't know which pairs of events are correlated. Again, this limitation is NOT applicable to their LR model because they CAN know which events are correlated in their model and, using this knowledge, they can easily show that their LR model doesn't violate Bell's inequality.
Sure, you can say that. But they are modelling the experiment, and their model of the experiment violates Bell and agrees with QM. I think you would agree that d=0 does not correspond to the experiments they were modelling.

RUTA

Aug1-10, 02:54 PM

Would you say the Weihs et al experiment violated Bell's inequality and agreed with QM, or would you say the Weihs et al experiment appeared to violate Bell's inequality because it exploited the coincidence time loophole? If you have no problem with this interpretation of the Weihs et all experiment, which they are modelling, I see not reason to expect anything different about their model.

Sure, you can say that. But they are modelling the experiment, and their model of the experiment violates Bell and agrees with QM. I think you would agree that d=0 does not correspond to the experiments they were modelling.

Nature is producing the experimental data and, unlike the LR model, we don't know how She's doing that. Thus, we say simply that Weil's experiment violated Bell's inequality and agreed with QM, just like we can (and I did) say the LR model violated Bell's inequality and agreed with QM (although, I had to add the qualifier -- "using the analysis of this experiment"). The reason for the qualifier is that we KNOW if the LR model is programmed to produce correlated pairs unambiguously, which it can do, then it will NOT violate Bell's inequality and NOT agree with QM.

I'm not trying to play semantic games, there is a distinction between the following two claims:

1. I have an LR model that produces data which when analyzed per experiment X violates Bell's inequality and agrees with QM.

2. I have an LR model that violates Bell's inequality and agrees with QM.

You have to choose your words carefully so as not to conflate these two claims.

Gordon Watson

Aug1-10, 03:19 PM

Nature is producing the experimental data and, unlike the LR model, we don't know how She's doing that. Thus, we say simply that Weil's experiment violated Bell's inequality and agreed with QM, just like we can (and I did) say the LR model violated Bell's inequality and agreed with QM (although, I had to add the qualifier -- "using the analysis of this experiment"). The reason for the qualifier is that we KNOW if the LR model is programmed to produce correlated pairs unambiguously, which it can do, then it will NOT violate Bell's inequality and NOT agree with QM.

I'm not trying to play semantic games, there is a distinction between the following two claims:

1. I have an LR model that produces data which when analyzed per experiment X violates Bell's inequality and agrees with QM.

2. I have an LR model that violates Bell's inequality and agrees with QM.

You have to choose your words carefully so as not to conflate these two claims.

Dear RUTA,

Sorry, but (for me) this is NOT your clearest piece of writing (which I value). Could you take more words, please, to make your points more clearly and expansively?

They seem to be important; though I am sure to be in disagreement, even when they have been clarified.

PS: Could you explain, and elaborate fairly fully, why you capitalized KNOW here?

The reason for the qualifier is that we KNOW if the LR model is programmed to produce correlated pairs unambiguously, which it can do, then it will NOT violate Bell's inequality and NOT agree with QM.

What do we KNOW here, and how do we KNOW IT, please?

PPS: Please clear your PF mail box.

Thank you very much,

JenniT

billschnieder

Aug1-10, 03:34 PM

I'm not trying to play semantic games, there is a distinction between the following two claims:

1. I have an LR model that produces data which when analyzed per experiment X violates Bell's inequality and agrees with QM.

2. I have an LR model that violates Bell's inequality and agrees with QM.

You have to choose your words carefully so as not to conflate these two claims.
I see your point. My point though is the following: Claim (1) and (2) are not different within the context of the paper we are discussing so I do not see why you insist on making a distinction. The authors did not claim to be deriving "an LR model" in a general sense. Their focus in that paper is to present "an LR model of the experiment" and in that context you can not separate their model from the constraints imposed by the experimental situation being modelled. It seems from your phrasing of (1) that you prefer to to do that. But do you apply the same standard to QM? QM only gives predictions for clearly stated experimental setups. I don't think you will expect QM to generate a dataset which you will then analyze according to experiment X.

DevilsAvocado

Aug1-10, 04:28 PM

I'm not trying to play semantic games

Well, I’m afraid you’ll have to... Semantic games are Mr. BS favorite engagement. The more completely meaningless words he produces, the happier he gets. Just watch and learn...

JesseM

Aug1-10, 04:31 PM

My argument is broken down into points as follows:
1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!
If you are now seriously considering responding to it, please clearly point out which of the above points is wrong and why it is wrong. I could not discern a clear response against any of the above points in anything you have written.
3) is ambiguous. It's true a dataset of pairs can be made to violate inequalities from a set of triples under certain sampling conditions, but not under the conditions assumed by Bell, where the choice of which two values to measure is random on each trial, and there is no correlation between the probability of a given triple and the choice of which pair to measure on a given trial.
Had you read the paper, you will have understood this. They have a single parameter dwhich corresponds to the coincidence time window, and they clearly show that with values of d similar to what is used in real experiments, Bell is violated and the simulation agrees with QM but if no coincidence time window is introduced ie d = 0, which is NOT what is done in real experiments, the simulation respects Bell and disagrees with QM, even though not all photons are detected. So yeah, I am pretty sure that their simulation has nothing to do with detection efficiency, and you will be too if only you read the article.
Suppose the simulation was altered so that 100% of all photons were detected by the simulated detectors--would the model continue to violate Bell inequalities? If not, I would say that by definition it is exploiting the detector efficiency loophole, even if it is also exploiting the coincidence time loophole.
his claim is perfectly correct if you understand what he means by "Bell is respected" (namely, that their model would obey Bell inequalities in an experimental setup that actually matched the observable experimental conditions assumed by Bell).
Exactly zero such experimental setups have been realized to date.
Do you think this is relevant to judging whether DrChinese's claim is correct or not? Bell's original proof did not concern any experiment, it was about comparing the theoretical predictions of local realism to the theoretical predictions of QM, and noting that their predictions must differ in certain theoretically-possible experimental setups. So, it's worth pointing out (as DrChinese did) that the model in the paper does not disprove Bell's theoretical claims, since it would obey the Bell inequalities in the theoretically-possible experimental setup Bell was discussing.
They present a model of a real experimental setup and THEY CLAIM that their model agrees with QM as evidenced by their own words which I have quoted to you.
They only claim that it agrees with QM for the specific experiments they analyze. I doubt they claim it would agree with QM in all the Aspect-type experiments that have been done to date, let alone in any experiment which is theoretically possible in QM
Dr C is free to state that in his opinion, their model agrees with Bell and disagrees with QM. But to say their model does not claim to match QM is false.
When he says it "disagrees with QM", I think he means that it would not make the same predictions as QM in all theoretically-possible experiments. Assuming that this is what he meant, then if your criticism is meant to be something more than a semantic quibble about the words he used to express this idea, do you think anything the authors said contradicts the claim that there model would not make the same predictions as QM in all theoretically-possible experiments?

RUTA

Aug1-10, 04:53 PM

I see your point. My point though is the following: Claim (1) and (2) are not different within the context of the paper we are discussing so I do not see why you insist on making a distinction. The authors did not claim to be deriving "an LR model" in a general sense. Their focus in that paper is to present "an LR model of the experiment" and in that context you can not separate their model from the constraints imposed by the experimental situation being modelled. It seems from your phrasing of (1) that you prefer to to do that. But do you apply the same standard to QM? QM only gives predictions for clearly stated experimental setups. I don't think you will expect QM to generate a dataset which you will then analyze according to experiment X.

I'm not a good writer. In fact, I'm not a good communicator in general. Sorry, I'll try again. Keep in mind that I'm conveying my opinion about their work. If you know that my opinion is wrong, maybe you could explain that to me.

I like your phrase, "an LR model of the experiment." That's right on the money. Now, the experiment is also in agreement with QM. Does that mean the LR model and QM are equivalent? No. What's the difference between QM and the LR model? If you wrote a computer program to simulate a perfect set of QM data, i.e., no guess work as to which pairs of events are correlated, then it would give |S| > 2. If you do the same with the LR model, it will not give |S| > 2.

Therefore, what the LR model shows is that you cannot use this experiment to claim, "We have proof that QM's prediction of |S| > 2 is right," because a computer simulator (their LR model) which doesn't give |S| > 2 does create data which give |S| > 2 when analyzed via this experiment.

How's that?

DevilsAvocado

Aug1-10, 05:02 PM

RUTA, JesseM and DrC,

I see that Mr. BS is back on track with the "Bell's Inequalities Triples Scam - BITS". Can you please verify if I’m a moron and Alain Aspect is a liar – or if it’s billschnieder who possess both these noble attributes.

This is a slide from Alain Aspect himself, showing the measurements of the first famous EPR-Bell experiment which violated Bell's Inequality in 1982:

http://i42.tinypic.com/r6xwxz.jpg

I see "Measured value" and the violation of "Bell's limits", but I don’t see Alain Aspect measuring "entangled triples"...?:bugeye:?

So, what do you think...?:uhh:?

Gordon Watson

Aug1-10, 05:09 PM

Is action at a distance possible as envisaged by the EPR Paradox?

Dear Deepak,

Answering your OP in my terms:

Is action at a distance possible?

No; no way!

PS: Though it is immaterial to my general response above, I'd be happy to learn what this phrase might mean: ... as envisaged by the EPR Paradox?

With best regards,

JenniT

billschnieder

Aug1-10, 05:11 PM

3) is ambiguous. It's true a dataset of pairs can be made to violate inequalities from a set of triples under certain sampling conditions, but not under the conditions assumed by Bell, where the choice of which two values to measure is random on each trial, and there is no correlation between the probability of a given triple and the choice of which pair to measure on a given trial.

I will let you respond to this one by yourself:
Bell's original proof did not concern any experiment, it was about comparing the theoretical predictions of local realism to the theoretical predictions of QM
An inequality such as X <= Y, means that "X" MUST always be less than or equal to "Y". If it is shown that in some cases X is greater than Y, the inequality is violated. It is the same as saying X can be greater than Y. There is nothing ambiguous there. It just means X is not necessarily less than Y as the inequality states.

I also notice that you actually agree with my point (3), except you claim that there are certain sampling assumptions in Bell's work which I have not taken into account. As you admitted in your later statement, Bell was never concerned about any actual experimental measurements or trials, so your earlier statement suggesting that Bell assumed data to be sampled in pairs and measured randomly on each trial is flatly wrong. There are no such claimed sampling assumptions in Bell's work which my point(3) supposedly violates. If you disagree point it out with a quote from Bell's work. Even if there was such an assumption, my point (3) still does not violate such a requirement.

I had hoped you would have a more substantive critique of those points.

JesseM

Aug1-10, 06:04 PM

I will let you respond to this one by yourself:
Bell's original proof did not concern any experiment, it was about comparing the theoretical predictions of local realism to the theoretical predictions of QM
I meant any real experiment that had actually been done. Obviously Bell's proof did concern a theoretical experiment, otherwise conditions like there being a spacelike separation between the measurements don't make any sense.
An inequality such as X <= Y, means that "X" MUST always be less than or equal to "Y".
If you specify some conditions which are necessary for the inequality to hold, then obviously you're only saying that X will be less than or equal to Y under those specific conditions.
I also notice that you actually agree with my point (3), except you claim that there are certain sampling assumptions in Bell's work which I have not taken into account. As you admitted in your later statement, Bell was never concerned about any actual experimental measurements or trials
Again, he was certainly concerned with some conditions that the experiments he was considering in theory should satisfy. Surely you aren't failing to understand something so extremely basic about Bell's proof? Do you think Bell would claim that the inequality would still be guaranteed to hold if there was no spacelike separation between measurements, for example?
so your earlier statement suggesting that Bell assumed data to be sampled in pairs and measured randomly on each trial is flatly wrong. There are no such claimed sampling assumptions in Bell's work which my point(3) supposedly violates. If you disagree point it out with a quote from Bell's work.
Look for example at p. 9 of this paper (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers), where Bell uses the sock analogy:
Suppose, however, that the socks come in pairs. And suppose that we know by experience that there is little variation between the members of a pair, in that if one member passes a given test then the other also passes that same test if it is performed. Then from d'Espagnat's inequality we can infer the following:

(the number of pairs in which one could pass at 0 degrees and the other not at 45 degrees)

plus

(the number of pairs in which one could pass at 45 degrees and the other not at 90 degrees)

is not less than

(the number of pairs in which one could pass at 0 degrees and the other not at 90 degrees)

This is not yet empirically testable, for although the two tests in each bracket are now on different socks, the different brackets involv a different tests on the same sock. But we now add the random sampling hypothesis: if the sample of pairs is sufficiently large and if we choose at random a big enough subsample to suffer a given pair of tests, then the pass/fail fractions of the subsample can be extended to the whole sample with high probability.
Even if there was such an assumption, my point (3) still does not violate such a requirement.
How about the assumption that there is no correlation between the choice of two measurements on a particular trial and the probability of different possible combinations of three hidden variables? If you don't violate that assumption, I don't see how you can get a violation of the inequalities.

DevilsAvocado

Aug1-10, 06:17 PM

Is action at a distance possible?

No; no way!

Finally a real convincing scientific proof, this is what we have all been waiting for! Thanks!

DevilsAvocado

Aug1-10, 08:51 PM

I’m tired.

I’m tired of all this anti-intellectual propaganda. Hillbillies screaming out their stubborn ignorance – No way! Wrong! Read the paper!

How stupid can it get? And the worst thing of all – it’s contagious.

(This does not apply to DrC, RUTA, JesseM and my_wan, thank god.)

I just have to do this... for the "casual reader"... finally some balanced scientific intellectual reasoning, where "maybe" is not an invective... as an answer to OP, finally after +1100 posts:

http://arxiv.org/abs/quant-ph/0609163 (http://arxiv.org/abs/quant-ph/0609163)

Quantum mechanics: Myths and facts
Hrvoje Nikolic
Theoretical Physics Division, Rudjer Boskovic Institute
Journal reference: Found.Phys.37:1563-1611,2007
...

6.3 (Non)locality without hidden variables?

Concerning the issue of locality, the most difficult question is whether QM itself, without hidden variables, is local or not. The fact is that there is no consensus among experts on that issue. It is known that quantum effects, such as the Einstein-Podolsky-Rosen-Bell effect or the Hardy effect, cannot be used to transmit information. This is because the choice of the state to which the system will collapse is random (as we have seen, this randomness may be either fundamental or effective), so one cannot choose to transmit the message one wants. In this sense, QM is local. On the other hand, the correlation among different subsystems is nonlocal, in the sense that one subsystem is correlated with another subsystem, such that this correlation cannot be explained in a local manner in terms of preexisting properties before the measurement. Thus, there are good reasons for the claim that QM is not local.

Owing to the nonlocal correlations discussed above, some physicists claim that it is a fact that QM is not local. Nevertheless, many experts do not agree with this claim, so it cannot be regarded as a fact. Of course, at the conceptual level, it is very difficult to conceive how nonlocal correlations can be explained without nonlocality. Nevertheless, hard-orthodox quantum physicists are trying to do that (see, e.g., [24, 25, 26, 27]). In order to save the locality principle, they, in one way or another, deny the existence of objective reality. Without objective reality, there is nothing to be objectively nonlocal. What remains is the wave function that satisfies a local Schrödinger equation and does not represent reality, but only the information on reality, while reality itself does not exist in an objective sense. Many physicists (including myself) have problems with thinking about information on reality without objective reality itself, but it does not prove that such thinking is incorrect.

To conclude, the fact is that, so far, there has been no final proof with which most experts would agree that QM is either local or nonlocal. (For the most recent attempt to establish such a consensus see [40].) There is only agreement that if hidden variables (that is, objective physical properties existing even when they are not measured) exist, then they must be nonlocal. Some experts consider this a proof that they do not exist, whereas other experts consider this a proof that QM is nonlocal. They consider these as proofs because they are reluctant to give up either of the principle of locality or of the existence of objective reality. Nevertheless, more open-minded (some will say – too open-minded) people admit that neither of these two “crazy” possibilities (nonlocality and absence of objective reality) should be a priori excluded.

P.S. action at a distance = nonlocality

billschnieder

Aug1-10, 09:11 PM

If you specify some conditions which are necessary for the inequality to hold, then obviously you're only saying that X will be less than or equal to Y under those specific conditions.
Point (1) which you did not respond or object to deduces that the only condition necessary is existence of triples of two-valued variables.
Again, he was certainly concerned with some conditions that the experiments he was considering in theory should satisfy.
No EPRB experiment in theory can produce triples of two-valued variables. You do not deny this, which is point (2).
Do you think Bell would claim that the inequality would still be guaranteed to hold if there was no spacelike separation between measurements, for example?
Bell does not have to claim it for it to be true. This is claim (6), and if you are objecting to it say so and lets have a little mathematical exercise to verify it. Are you contesting claim (6)?
How about the assumption that there is no correlation between the choice of two measurements on a particular trial and the probability of different possible combinations of three hidden variables? If you don't violate that assumption, I don't see how you can get a violation of the inequalities
Again I point you to claim (1) which establishes the minimum requirement for deriving Bell-type inequalities, and claim (2) which clearly states that the requirement is not met in any bell-test experiment. Are you now contesting claim (1) and/or (2)? If you are, simply say so.

RUTA

Aug1-10, 10:00 PM

JesseM

Aug1-10, 11:37 PM

Point (1) which you did not respond or object to deduces that the only condition necessary is existence of triples of two-valued variables.
That's true if you are considering an inequality where all values of the triples are known, and the pairs that appear in the inequality deal with every single triple that satisfies it. For example, this page (http://www.upscale.utoronto.ca/PVB/Harrison/BellsTheorem/BellsTheorem.html) states an inequality that's guaranteed to hold if you know the value of three variables A,B,C for some collection of objects:
The result of the proof will be that for any collection of objects with three different parameters, A, B and C:

The number of objects which have parameter A but not parameter B plus the number of objects which have parameter B but not parameter C is greater than or equal to the number of objects which have parameter A but not parameter C.

We can write this more compactly as:

Number(A, not B) + Number(B, not C) greater than or equal to Number(A, not C)
If we have a collection of objects and we know whether each object has A/not A, B/not B, and C/not C, then Number(A, not B) could include every object in the collection which has (A, not B), and likewise for the other pairs. In this case, the inequality is guaranteed to hold with no additional assumptions. On the other hand, if for each triplet we only sample two out of three properties, so Number(A, not B) would only be the number of triplets where the two properties we checked were A and B (so we didn't check C) and the result was (A, not B), and likewise for the other pairs, in this case it's no longer guaranteed that the inequality will hold, you need additional assumptions (particularly the assumption that the sampling was done in such a way that there should be no correlation between which two variables were sampled and the probability of the triplet having different possible combinations of all three variables).

So, if you are claiming in (1) that you could derive the inequality even in conditions where we only sample two of the three values for each triplet, then I would certainly object to that, although I would say that the inequality can be justified with additional assumptions like the one I mentioned about the choice of sample having no correlation to the full values of the triplet.
No EPRB experiment in theory can produce triples of two-valued variables. You do not deny this, which is point (2).
Right, I don't deny that. The assumption of triples is a theoretical assumption of hidden variables theories, but one cannot measure all three.
Do you think Bell would claim that the inequality would still be guaranteed to hold if there was no spacelike separation between measurements, for example?
Bell does not have to claim it for it to be true. This is claim (6), and if you are objecting to it say so and lets have a little mathematical exercise to verify it. Are you contesting claim (6)?
Yes, I'm contesting it in the case where the different pairs are only based on the subset of objects where those two variables were sampled, though I wouldn't contest it in the case where the pairs in the inequality like Number(A, not B) represent all objects that satisfy that pair (i.e. all objects in the collection that have property A but not B, as opposed to just the ones where we measured A and B and found A, not B).

And what Bell claimed is relevant to your own statement "As you admitted in your later statement, Bell was never concerned about any actual experimental measurements or trials". Again, do you deny that Bell's proof assumes certain experimental conditions for the theoretical experiment under consideration, like the condition of a spacelike separation between measurements?

billschnieder

Aug2-10, 11:13 AM

This last post of yours is a masterpiece of obfuscation. So let us untangle it shall we. Here again for reference are the claims you are responding to:

1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption
2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)
3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.
6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of of spooky action at a distance is mandated!

Now let us go through one by one and see how you have responded so far

(1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption

That's true if you are considering an inequality where all values of the triples are known, and the pairs that appear in the inequality deal with every single triple that satisfies it.

And it is false when exactly? If all values in a triple are not known then you do not have a triple. The claim states clearly that Bell's inequality is an arithmetic relationship between triples of numbers each of which can take values of (+1 or -1). The claim is essentially that it is impossible to find triples of numbers obeying this requirement which will violate the inequality, irrespective of physical or statistical considerations. If you agree with it, simply saying so will do rather than go through a long winding rabbit trail that has nothing to do with the claim itself. If you disagree, use whatever method you like to provide me a triple of numbers each with values of (+1 or -1) which violates the inequality. Note, if you can not produce such a list of triples then not only are you admitting claim (1), you will also be admitting claim (6).

(2) In Bell-test experiments only pairs of values are ever collected at a time (a dataset of pairs)

Right, I don't deny that. The assumption of triples is a theoretical assumption of hidden variables theories, but one cannot measure all three.

So you agree with (2), but I noticed how you sneaked in the underlined statement as if to suggest that claim (1) is only true for hidden variable theories. Claim (2) is about experiments not theories. Claim (1) is not concerned with any physical theory. It is a universally valid arithmetic relationship between any three variables with values (+1 or -1). This is why I say you are a master at obfuscation. So I strike the underlined text.

(3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons

So, if you are claiming in (1) that you could derive the inequality even in conditions where we only sample two of the three values for each triplet, then I would certainly object to that

Huh? An ingenious way of agreeing with claim (3) while appearing to object. You phrased your agreement with claim (3) as an objection to claim (1). Claim (3) states essentially that you can not derive the inequalities as an arithmetic relationship between only pairs of values. Remember, claim (1) is dealing with triples not pairs. Claim (3) is dealing with pairs not triples. Of course you say that claim (1) will not be valid for pairs, which is exactly what claim (3) says!!! I take it from the above you agree with claim (3).

(4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation

...

(5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising, it is expected for purely mathematical reasons, having nothing to do with realism or locality.

...

(6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of spooky action at a distance is mandated!

Yes, I'm contesting it in the case where the different pairs are only based on the subset of objects where those two variables were sampled, though I wouldn't contest it in the case where the pairs in ...

Another masterpiece at obfuscation. Claim (6) is dealing with a dataset of triples not pairs, did you see the word pairs anywhere there? So by contesting a dataset of pairs, you are responding to something other than claim (6). Do you claim that dataset of triples from a situation in which there was non-local communication between the devices generating the data will violate Bell's inequality. If you do, say so rather than put up the strawman of pairs in order to appear to be contesting the claim when you are not.

Again, do you deny that Bell's proof assumes certain experimental conditions for the theoretical experiment under consideration, like the condition of a spacelike separation between measurements?

I will draw your attention back to claim (1). That is why claim (1) is so important because it demonstrates conclusively that you do not need any locality, probability, factorization etc assumptions to derive Bell's inequalities. All those assumptions are peripheral to the fact that the resulting inequalities are universally valid arithmetic relationships between triples of numbers with values (+1 or -1). As I mentioned to you earlier in this thread, these relations have been known for 100+ years. As soon as Bell assumed that properties existed simultaneously at three angles (a,b,c), he was guaranteed to obtain those relationships. It is completely peripheral, the reason for the three angles. He could have as well assumed that non-local communication was involved between space-like and it wouldn't have changed the resulting inequalities. Clearly, this means the inequalities are not relationships that must exist only for local hidden variable scenarios. They are valid for all possible scenarios involving three variables with values (+1 or -1). If you disagree, provide the triples of values which violate it using any assumption of your choosing, you can even assume FTL for all I care, just give me the triples and we can calculate.

DevilsAvocado

Aug2-10, 01:47 PM

Nikolic's opinion is what I sense in the community as well. Something "big" has to happen to bring consensus. Shortly after introducing Relational Blockworld at Bub's conference "New Directions in the Foundations of Physics" and at Price's conference "Time-Symmetric QM," I was naively enthusiastic. Aharonov quickly bust my bubble :-) Not to be mean, of course, he just wanted me to understand what I was up against. He had introduced his two vector formalism years ago and even used it to devise new experiments. He said the experiments were all the physics community at large cared about, and they weren't all that interested in them b/c they didn't disprove QM or nonlocality, etc. That's why I think it's got to be something "big," e.g., a new theory of physics, to break the log jam.

Thanks RUTA,

Your interesting thoughts certainly help breaking the log jam in this thread. :smile:

Yes, it’s pretty obvious that something "BIG" has to happen to bring consensus and progress. This has always been the case in the history of science, and now the signs are flashing in the sky again. One major "lighthouse" (not on Shutter Island :wink:) is EPR-Bell, another is Quantum Gravity (QG).

I’m amazed of the "denial process" practiced in this thread right now. What are they afraid of? That KGB or CIA will read their minds "at a distance"?? What also amazes me is the fact that the denialers find the solution for everything around 1800 - 1850??

Anyhow, your story about Yakir Aharonov (http://en.wikipedia.org/wiki/Yakir_Aharonov) is exciting! Aharonov worked with David Bohm (http://en.wikipedia.org/wiki/David_Bohm) in 1959, when they proposed the Aharonov-Bohm Effect (http://en.wikipedia.org/wiki/Aharonov-Bohm_Effect), and David Bohm worked closely with Albert Einstein!

This is the closest to "God" I will ever get!! :smile:

P.S. What possible 'candidates' do you see for a "new theory of physics"?

JesseM

Aug2-10, 02:01 PM

(1) Bell's inequalities can be derived from triples of dichotomous variables without any physical assumption

And it is false when exactly? If all values in a triple are not known then you do not have a triple.
Here we again see the type of basic confusion I referred to in post #1158 (http://www.physicsforums.com/showpost.php?p=2822691&postcount=1158), between "assumptions about the observable conditions of the experiment" and "the theoretical assumptions about hidden variables". It may well be that our experimental conditions are such that we only sample a pair of properties for each object, but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties (which could be known by a hypothetical omniscient observer, even if we don't sample all three ourselves).

You accuse me of "obfuscation" but it's not clear you understand what I'm talking about here, so let me give a simple example. Suppose we have a collection of 9 objects, each of which can be tested on three properties A, B, C, and for a test of A we'd get either result A+ or A-, for a test of B we'd get B+ or B-, and for a test of C we'd get either C+ or C-. For each of the 9 objects, here is a list comparing the actual full set of three values known by an omniscient observer with the two properties we chose to sample for each object:

1. Actual values: A+,B+,C-. We sampled A and B, got (A+,B+).
2. Actual values: A-,B-,C-. We sampled B and C, got (B-,C-)
3. Actual values: A+,B-,C-. We sampled A and C, got (A+,C-).
4. Actual values: A-,B-,C+. We sampled A and B, got (A-,B-).
5. Actual values: A-,B+,C-. We sampled B and C, got (B+,C-).
6. Actual values: A+,B+,C-. We sampled A and C, got (A+,C-).
7. Actual values: A+,B-,C+. We sampled A and B, got (A+,B-).
8. Actual values: A-,B-,C+. We sampled B and C, got (B-,C+).
9. Actual values: A+,B-,C-. We sampled A and C, got (A+,C-).

Now consider the following inequality:

(Total number of objects with properties A+ and B-) + (Total number of objects with properties B+ and C-) greater than or equal to (Total number of objects with properties A+ and C-)

By dividing each term by the total number of objects (9 in this case), we get an almost-identical inequality, which I will call inequality #1:

(Fraction of all nine objects with properties A+ and B-) + (Fraction of all nine objects with properties B+ and C-) greater than or equal to (Fraction of all nine objects with properties A+ and C-)

Assuming that all objects have well-defined unchanging values for all three properties, we can prove as a purely mathematical matter that this inequality must hold (the proof is trivial--every triplet with A+ and C- must either be of type A+B+C- or type A+B-C-, and if the former it will also contribute to the number with B+ and C-, if the latter it will also contribute to the number with A+ and B-). And indeed you can see that in the example it does hold:

--Objects 3, 7 and 9 had A+ and B-, so (Fraction of all nine objects with properties A+ and B-) = 3/9

--Objects 1, 5, and 6 had B+ and C-, so (Fraction of all nine objects with properties B+ and C-) = 3/9

--Objects 1, 3, 6 and 9 had A+ and C-, so (Fraction of all nine objects with properties A+ and C-) = 4/9

And, it is indeed true that 3/9 + 3/9 is greater than or equal to 4/9.

On the other hand, consider the following different inequality #2 which concerns only properties that were actually sampled:

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

You can see that this inequality is violated in this example, because:

--Objects 1, 4 and 7 were sampled for A,B and of these only 7 gave result A+,B- so (Fraction of A,B samples which gave result A+, B-) = 1/3

--Objects 2, 5 and 8 were sampled for B,C and of these only 5 gave result B+,C- so (Fraction of B,C samples which gave result B+, C-) = 1/3

--Objects 3, 6 and 9 were sampled for A,C and 3, 6 and 9 all gave result A+,C- so (Fraction of A,C samples which gave result A+, C-) = 3/3

Since it's not true that 1/3 + 1/3 is greater than or equal to 3/3, the inequality is violated.

The Bell inequalities derived by Bell and other physicists are all inequalities where the terms deal with the variables that are sampled in some theoretical experiment (like the second inequality I wrote above), not with the full set of three values that are theorized to exist in local realism (like the first inequality above). But if you add some additional assumptions beyond local realism (assumptions which can themselves be justified by the details of how the experiment is conducted plus the assumption of local realism), like the assumption that the probability of different hidden triplets is not correlated with the two you actually choose to sample, then you can show that in the limit as your sample size approaches infinity, the probability that this inequality will be respected approaches 1:

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)
The claim states clearly that Bell's inequality is an arithmetic relationship between triples of numbers each of which can take values of (+1 or -1). The claim is essentially that it is impossible to find triples of numbers obeying this requirement which will violate the inequality, irrespective of physical or statistical considerations. If you agree with it, simply saying so will do rather than go through a long winding rabbit trail that has nothing to do with the claim itself.
But your claim above seems to have two parts:

1a) If we have a set of triplets, we can derive a purely arithmetic inequality where each term represents the fraction of all triplets that have a certain pair of properties, and this inequality is guaranteed to hold mathematically.
1b) Bell's own inequality is an inequality of this type (implied by the part where you say 'Bell's inequality is an arithmetic relationship...")

I would agree with 1a but not with 1b, for the reasons explained above. Perhaps you did not actually mean for your claim 1) to include the subclaim 1b), in which case please clarify.
If you disagree, use whatever method you like to provide me a triple of numbers each with values of (+1 or -1) which violates the inequality.
I don't deny that for this type of arithmetic inequality it's impossible to find a set of triples which violate it, I just deny that Bell's own inequality is this type of inequality.
(3) A dataset of pairs can be made to violate inequalities derived from a dataset of triples for purely mathematical reasons
So, if you are claiming in (1) that you could derive the inequality even in conditions where we only sample two of the three values for each triplet, then I would certainly object to that
Huh? An ingenious way of agreeing with claim (3) while appearing to object.
No, it just depends on what kind of "inequalities" you are talking about when you say "a dataset of pairs can be made to violate inequalities derived from a dataset of triples." If you're talking about inequalities where each term deals with the fraction of all triplets which have a certain pair of properties, like this one:

(Fraction of all objects with properties A+ and B-) + (Fraction of all objects with properties B+ and C-) greater than or equal to (Fraction of all objects with properties A+ and C-)

...in that case (3) is incorrect, it's impossible for pairs of this form to violate the inequalities if each pair is the correct fraction of triples that have the stated properties.

On the other hand, if you're talking about an inequality of this form:

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

...then in that case I agree with (3), such pairs can violate the inequalities. However, if we impose some additional conditions like that appear in derivations of Bell inequalities, we can show that the probability this inequality will be violated approaches zero in the limit as the number of samples approaches infinity.
(4) I have provided mathematical proof of (1), (2) is an accepted fact. I have provided proof of (3) via simulation
The simulation is only relevant to Bell's proof if your pairs are based on sampling a pair of values from a triple, where each term of the inequality is of a form like (Fraction of A,B samples which gave result A+, B-), and where you have included the appropriate conditions of the proof like the condition that the probability of different possible triplets is independent of which two variables are sampled.
(5) Therefore, the violation of Bell's inequalities derived from triples, by experiments such as Bell-test experiments which only collect pairs, is not surprising
It should be very surprising for any advocate of local realism, since as I said if you include the (reasonable) conditions of Bell's proof like the no-conspiracy assumption (which can themselves be justified using the conditions of the experiment and the assumption of local realism), you find that the probability of the inequality being violated approaches zero as your sample gets very large.
(6) Therefore, Bell's inequality can never be violated by a dataset of triples, even if the physical assumption of spooky action at a distance is mandated!
True if we assume the values for all three values of a triple are unchanging, but if the choice of which property to sample first can alter the values of the other three properties (which, for spacelike-separated measurements would require spooky action at a distance), then the inequality can certainly be violated. Would you like a numerical example of this?
All those assumptions are peripheral to the fact that the resulting inequalities are universally valid arithmetic relationships between triples of numbers with values (+1 or -1). As I mentioned to you earlier in this thread, these relations have been known for 100+ years. As soon as Bell assumed that properties existed simultaneously at three angles (a,b,c), he was guaranteed to obtain those relationships.
Not if you allow for the possibility that the properties can change over time, or that there could be a correlation between the values of the three properties and the choice of which two to sample. That's why deriving the Bell inequalities isn't as simple as deriving the simple arithmetic inequality, you need to invoke additional physical assumptions about the experimental setup.

DevilsAvocado

Aug2-10, 02:31 PM

Here we again see the type of basic confusion I referred to in post #1158 (http://www.physicsforums.com/showpost.php?p=2822691&postcount=1158), between "assumptions about the observable conditions of the experiment" and "the theoretical assumptions about hidden variables". It may well be that our experimental conditions are such that we only sample a pair of properties for each object, but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties (which could be known by a hypothetical omniscient observer, even if we don't sample all three ourselves).

JesseM, I’m afraid this is a much more severe dysfunction than "basic confusion". DrC has explained this rock-solid and crystal-clear to everyone who wishes to understand, several times, but it just doesn’t work for Mr. BS. I think there is no hope...

For those following this discussion, billschnieder is basically addressing this question:

For a stream of particles, we'll call them Alice, does Alice have well defined polarization values for angle settings a=0, b=120 and c=240 degrees which match the QM expectation value of .25?

EPR says YES, Alice does, unless you unreasonably require this to be proven by simultaneous prediction of those values. Their explanation is that since a, b OR c can be predicted (but not all simultaneously), that should be adequate as proof. You can predict a, b or c of course by first observing Alice's twin partner, Bob.

Now the reason I choose the angle settings I did for a, b and c is that allows me to construct a very simple dataset to test for Alice, and then compare to the QM expectation value. Assuming 4 photons in Alice's stream (to get us started):

a b c
+ + -
+ - +
- + -
+ - -

So the above would be possible realistic values per EPR. I made these up, in an attempt to provide values that would be as close as possible to the Quantum Mechanical predictions. Obviously, 4 is way too few to be rigorous but yet is sufficient to discuss. So let's consider what Alice's twin Bob would look like:

a b c
+ + -
+ - +
- + -
+ - -

I.e. the same as Alice. So suppose we compare all the permutations of observing Alice and Bob at different angle pairs ab, bc, and ac. What would we see? And the answer is that even for as few as 4 items, it is not possible to get closer than a 33% average correlation rate.

ab=.25
bc=.25
ac=.50
------
average=.333333

QM would predict 25%, i.e. cos^2(theta=120 degrees). Obviously, you would have a standard deviation which is too large to be meaningful for this few items. But in a larger sample the actual experimentally observed value is in fact 25%. Using the EPR logic, something is clearly wrong.

Bill's argument has something to do with 3 observers and either 2 or 3 attributes (I am not really sure which). But the actual question is whether 1 particle has 3 well defined values. If 1 does, then 2 do too. And that is what is being considered in Bell tests. Whenever you question this point, simple consider that EPR is saying:

Alice stream =
a b c
+ + -
+ - +
- + -
+ - -

Bob stream =
a b c
+ + -
+ - +
- + -
+ - -

On the other hand, QM goes no farther than this:

Alice stream =
a b
+ +
+ -
- +
+ -

Bob stream =
a b
+ +
+ -
- +
+ -

Which matches QM just fine.

RUTA

Aug2-10, 02:59 PM

P.S. What possible 'candidates' do you see for a "new theory of physics"?

I read the threads in "Beyond the Standard Model" looking for candidates, but haven't seen any to my liking. It seems the unification community isn't addressing foundational issues and the foundations community isn't addressing unification. I think Smolin was right when he said the foundational problems of quantum mechanics probably constitute “the most serious problem facing modern science" and this problem “is unlikely to be solved in isolation; instead, the solution will probably emerge as we make progress on the greater effort to unify physics.” [Smolin, L., The Trouble with Physics, Houghton Mifflin, Boston, 2006.] Unfortunately, I think most unification researchers take this to mean the foundational problems of QM will be solved in a unification theory, but they won't have any bearing on the construct of the theory. Even Smolin didn't know how LQG would bear on EPR-Bell when I asked him at the Wheeler Symposium in 2002. He wasn't dismissive, however, saying that was something he planned to look into. I guess I got my answer in the aforementioned book :smile:

As I said in an earlier post, we are currently working on a new approach to classical gravity (essentially nonseparable Regge calculus) based on what started as an interpretation of QM (Relational Blockworld). But, if you've ever worked with Regge calculus, you can appreciate that I'm hoping for something better :smile:

billschnieder

Aug2-10, 05:53 PM

sample[/i] a pair of properties for each object, but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties (which could be known by a hypothetical omniscient observer, even if we don't sample all three ourselves).
You are the one confused. A dataset of triples means just that. If you know only pairs you have a dataset of pairs even if you assume that there was a third value for each pair which you do not know. Simply because you can not directly calculate the LHS of Bell's inequality without the a third value and if you are calculating the LHS using a separate experiment for each term, you can not claim to have a dataset of triples. If you assume that the three values exist and you would like to consider them together theoretically as triples (like Bell did), then you have a dataset of triples not pairs. So for all your explanations, you have not provided anything of contrary to my claim. Claim (1) is dealing with datasets of triples not pairs despite your wishes. Again if you agree with it just say you do. If you disagree say so as well.

The Bell inequalities derived by Bell and other physicists are all inequalities where the terms deal with the variables that are sampled in some theoretical experiment[u]
In the theoretical experiment, the values exist as triples, the terms in the inequality are obtained from the triples and in this case the inequality can never be violated even if FTL is involved. You aren't saying anything interesting here that is supposed to counter what I said.

Go back to Bell's original work from equation (14) onwards where he introduces the third angle and follow the derivation from there. You will realize that everything prior to that point is peripheral. So contrary to your claims, Bell's inequality is in fact an arithmetic relationship between triples. I have provided mathematical proof by deriving the exact same equation without any other assumption than the presence of triples. Bell also assumes the presence of triples and he obtains the same mathematical relationship. Is this a coincidence? Note also that you fail to specify the extra assumption without which Bell's inequality can not be derived, provided you already have triples like Bell assumed.

Now if you are ready to admit claim (1) but want to argue that under certain conditions a dataset of pairs will also satisfy the inequality, but not under every condition, then that is understandable but non earth-shattering because my claim (1) already lays out the conditions under which those terms involving pairs will obey the inequality -- ie, when they are extracted from a dataset of triples!! And my claim (3) already states that not all datasets of pairs will obey the inequality. So you will be admitting both claims (1) and (3) here. In this case then,the discussion will be to examine whether those conditions are met in the Bell test experiments in which only pairs are measured (claim (2)). I show below that the conditions are not met.

But your claim above seems to have two parts:

1a) If we have a set of triplets, we can derive a purely arithmetic inequality where each term represents the fraction of all triplets that have a certain pair of properties, and this inequality is guaranteed to hole mathematically.
1b) Bell's own inequality is an inequality of this type (implied by the part where you say 'Bell's inequality is an arithmetic relationship...")

I would agree with 1a but not with 1b, for the reasons explained above. Perhaps you did not actually mean for your claim 1) to include the subclaim 1b), in which case please clarify.

I don't deny that for this type of arithmetic inequality it's impossible to find a set of triples which violate it, I just deny that Bell's own inequality is this type of inequality.

So you accept claim (1) but deny that the inequality so derived is Bell's inequality. I suggest you stick to Bell's inequality rather than your toy version):
I have proven the arithmetic relationship
|ab+ac|-bc <= 1
from which it immediately follows that if you have a list of triples of numbers of any length where each number can take values (+1 or -1), the following is also true
|<ab> + <ac>| - <bc> <= 1

Bell's variables (a,b,c) constitute a triple of variables each of which can take values (+1 or -1), each symbol in the inequality has exactly the same meaning, the same as the input to my derivation. Is it your claim that using variables with the same meaning, and properties like Bell's and obtaining the inequalities like Bell without any other assumption is accidental? Yes or No?

If you disagree, provide a dataset of [u]triples which obeys Bell's inequalities but violates the one I derived or vice versa. It should be easy for you to do. Since you claim there are other assumptions in Bell's inequality that makes my claim (1) inapplicable to Bell's inequalities, all you need do is use one of those assumptions to provide a dataset or even a single data point where both disagree. I will consider your failure to do that as an admission of my claim (1). Then we can go on to discuss the areas where you have genuine disagreement.

No, it just depends on what kind of "inequalities" you are talking about when you say "a dataset of pairs can be made to violate inequalities derived from a dataset of triples." If you're talking about inequalities where each term deals with the fraction of all triplets which have a certain pair of properties, like this one:

(Fraction of all objects with properties A+ and B-) + (Fraction of all objects with properties B+ and C-) greater than or equal to (Fraction of all objects with properties A+ and C-)

...in that case (3) is incorrect, it's impossible for pairs of this form to violate the inequalities if each pair is the correct fraction of triples that have the stated properties.

Huh? I'm talking about Bell's inequality not your toy version. Your version bears no resemblance to what Bell actually did, or to any actual Bell-test experimental situation. You will have to rephrase your objection in Bell's form or the form of what is actually done in Bell test experiments so that we can examine it if it makes any sense. The current version is just obfuscation and is far removed from what we are discussing.

...then in that case I agree with (3), such pairs can violate the inequalities. However, if we impose some additional conditions like that appear in derivations of Bell inequalities, we can show that the probability this inequality will be violated approaches zero in the limit as the number of samples approaches infinity.
As I have demonstrated and I hope you now agree, so long as you have a list of triples in hand with values restricted to (+1 or -1), whether theoretical or measured, no matter how the list was generated, Bell's inequality is never violated (claim 6).

Now let us examine how the experiments are actually performed. For reference, we have the inequality
|<ab> + <ac>| - <bc> <= 1
In actual experiments each term from the above is actually from a different experiment. In one run (say run 1), the experimenters measure <ab> (call it <a1b1>), from the next run, they measure <a2c2> and from the third run, they measure <b3c3>. Now you certainly will not deny that this is how such experiments are typically performed. If you disagree, say so.

Your argument, as much as one can be discerned, is that in the limit as N becomes large, the fact that three different experiments are used does not matter. But that is short-sighted and misses the point of my argument.

Note that in the inequality
|<ab> + <ac>| - <bc> <= 1

a,b,c within angled brackets represent lists of numbers +1, -1. This equation can be factored as:

|<a(b+c)>| - <bc> <= 1

The above implies that if <bc> = -1, then <(b+c)> must be zero, otherwise the inequality will be violated. Obviously it is easy to see that whenever bc = -1, (b+c) is zero for. Now, in the experimental situation describe above, the LHS being calculated is

|<a1b1> + <a2c2>| - <b3c3>

in order to be able to factor this like we did above and ensure that the inequality is true for any finite list of numbers measurable in an experiment, a1 within the angled brackets must be the same as a2, similarly b1 must be the same as b3 and c2 must be the same as c3. This means, not only must a1 have the exact same number of +1's and -1's as a2, the exact sequence must also match (same for b1,b3 and c2,c3).
You may naively think that it is possible to sort the numbers so that the sequence matches but note the following:

We take our first pair from the first run (a1,b1), we then sort our second pair (a2,c2) such that the a2 and a1 exactly match. Note we now have (a1,b1,a2,c2) four columns of data, but two columns are identical so we can drop a2 altogether and we now have our dataset of triples (a1,b1,c2). This dataset NEVER violates Bell's inequalities because we can calculate

|<a1b1> + <a1c2>| - <b1c2>
|<a(b1+c2)>| - <b1c2>
But this is not what is done in Bell test experiments, so let us try to continue our sorting to incorporate the third dataset. We immediately face a difficulty! We have a list of triples (a1, b1, c2), we need to sort (b3,c3) so that not only does b3 line up with b1, but also c3 lines up with c2! This is a practically impossible task. It is obvious from the above that the third term is not independent of the first two but is directly derived from it.

It should be very surprising for any advocate of local realism, since as I said if you include the (reasonable) conditions of Bell's proof like the no-conspiracy assumption (which can themselves be justified using the conditions of the experiment and the assumption of local realism), you find that the probability of the inequality being violated approaches zero as your sample gets very large.
Be my guest, provide a dataset of triples which violates |ab+ac|-bc <= 1. Feel free to include conspiracy, non-locally communication and any other kind of assumption you like in generating the dataset. You will never violate the inequality. If you can not do that, you must admit that the inequality has no bearing on presence or absence of locality, conspiracy, or any other physical assumption you might think of.

True if we assume the values for all three values of a triple are unchanging, but if the choice of which property to sample first can alter the values of the other three properties (which, for spacelike-separated measurements would require spooky action at a distance), then the inequality can certainly be violated. Would you like a numerical example of this?
I would love to see your dataset of triples which violates the inequality. Make any assumption you like, non-locality, spooky action, consipiracy, time-variation etc while generating the list. All I ask is that you give me a list of triples of numbers each with values (+1, -1) which violates |<ab>+<ac>|-<bc> <= 1 for the whole list, or |ab+ac|-bc <= 1 for each individual triple.

If you can not generate such a dataset, then you can not with a straight face claim that experiments violate genuine Bell inequalities. It simply points to a discrepancy with the way the data from experiments are treated as I have outlined above.

DevilsAvocado

Aug2-10, 06:31 PM

I read the threads in "Beyond the Standard Model" looking for candidates

Wow! Why did I miss this forum!? :surprised
Thanks! Now I need some "gadget" the will give me time2... :smile:

It seems the unification community isn't addressing foundational issues and the foundations community isn't addressing unification. I think Smolin was right when he said the foundational problems of quantum mechanics probably constitute “the most serious problem facing modern science" and this problem “is unlikely to be solved in isolation; instead, the solution will probably emerge as we make progress on the greater effort to unify physics.” [Smolin, L., The Trouble with Physics, Houghton Mifflin, Boston, 2006.] Unfortunately, I think most unification researchers take this to mean the foundational problems of QM will be solved in a unification theory, but they won't have any bearing on the construct of the theory.

This seems like a BIG problem for something "BIG" to happen... I just wonder if all this is too much for a "New Einstein" to handle alone...? On the other hand, QM was not a one-man-show... :uhh:

Even Smolin didn't know how LQG would bear on EPR-Bell when I asked him at the Wheeler Symposium in 2002. He wasn't dismissive, however, saying that was something he planned to look into. I guess I got my answer in the aforementioned book

Cool that you’ve discussed EPRB with Smolin! :cool: Loop Quantum Gravity (LQG) looks promising. Can LQG "generate" classical spacetime that matches GR? And its predictions of violation of the constancy of the speed of light could maybe be a possible 'answer' to EPRB...!?

Anyhow, to layman like me, this is all very simple: You just have to figure out what space is, exactly. And then do the same for gravity and matter + some simple formulas for the overall interaction between The Three Musketeers. And your done, bada bing bada boom! o:)

(sorry, bad joke :redface:)

As I said in an earlier post, we are currently working on a new approach to classical gravity (essentially nonseparable Regge calculus) based on what started as an interpretation of QM (Relational Blockworld). But, if you've ever worked with Regge calculus, you can appreciate that I'm hoping for something better

This is all very interesting, and I think you deserve a medal just for trying. I hope you will be successful!

(Asking me about Regge calculus, is like asking me for a weather report for the Moon... :biggrin:)

Thanks for the info, very interesting!

JesseM

Aug2-10, 08:35 PM

You are the one confused. A dataset of triples means just that.
Bell's proof does not assume a "dataset of triples" if by "dataset" you mean the experimental data that each term in the inequality is assumed to be based on. In some variants of the proof it may assume there is some objective truth about all three members of the triple even if we can't measure them all, but the inequality only deals with measurable pairs.
If you know only pairs you have a dataset of pairs even if you assume that there was a third value for each pair which you do not know.
Yes, exactly! And the Bell inequality is a prediction about the statistics on such a dataset of pairs, given some assumptions about how they were gathered and the laws of physics that determine their values.
Simply because you can not directly calculate the LHS of Bell's inequality without the a third value and if you are calculating the LHS using a separate experiment for each term, you can not claim to have a dataset of triples. If you assume that the three values exist and you would like to consider them together theoretically as triples (like Bell did), then you have a dataset of triples not pairs.
Not sure what you mean by "consider them together theoretically as triples", if this is an important part of your argument you'll have to explain in more detail. We may be assuming theoretically the pairs are sampled from triples, but a term in the inequality like (Fraction of A,B samples which gave result A+, B-) still deals with a collection of measured pairs (specifically the pairs where we measured A,B). Do you disagree?
So for all your explanations, you have not provided anything of contrary to my claim. Claim (1) is dealing with datasets of triples not pairs despite your wishes. Again if you agree with it just say you do. If you disagree say so as well.
Based on your comment above I no longer know what you mean when you say "datasets of triples", you seem to be using that phrase in a rather odd way that you have never defined. According to my commonsense use of the term, you only have a "dataset of triples" if you actually measured three properties of each "object" (the 'thing' being a pair of entangled particles in most cases, or a short time interval where we can measure a SQUID ring at any of three times in the case of the Leggett-Garg inequality), if you only measured two for each "object" then by definition you have a dataset of pairs. So, for example, the inequality I mentioned earlier:

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

...would be an inequality dealing with a dataset of pairs, even though I explicitly assumed each pair was drawn from a well-defined triple. If you disagree, please give a careful definition of what you mean by the phrases "dataset of pairs" and "dataset of triples".
In the theoretical experiment, the values exist as triples, the terms in the inequality are obtained from the triples and in this case the inequality can never be violated even if FTL is involved.
I don't know what you mean by "the terms in the inequality are obtained from the triples" either. In the theoretical experiment I described, only two properties were measured from each object, and a term in the inequality like (Fraction of A,B samples which gave result A+, B-) dealt only with the subset of triples where A and B were sampled, not with the full set of triples. I showed explicitly how the inequality was violated in this case. Do you disagree that the terms in Bell's inequality also deal only with subsets of all the entangled particle pairs that were measured, so that for example a term like P(experimenter A found spin-up at 0 degrees, experimenter B found spin-down at 45 degrees) would deal only with the particle pairs that were actually measured with detector settings of 0 for A and 45 for B? So if we can't make the theoretical assumption that the full values of the triple are uncorrelated with the choice of detector settings, it would be possible for Bell's inequality to be violated too even in a local realist universe? (for example, if the detectors are actually set in the past light cone of the source emitting the particles, it's conceivable the source would "know" which settings the particles will encounter on each trial and tailor the triple of values to that, in just the right way to violate the inequality)
Go back to Bell's original work from equation (14) onwards where he introduces the third angle and follow the derivation from there. You will realize that everything prior to that point is peripheral.
Bell's "original work" is highly condensed, written for an audience of physicists who can be expected to understand his implicit assumptions, it's silly to ignore all his later writings where he stated the assumptions more explicitly, like the paper I quoted in post #1171 where he referred to the need to assume a "random sampling hypothesis" (also, since we are dealing with scientific ideas rather than religious scriptures, it is perfectly legitimate to consider the derivation of Bell inequalities by authors other than Bell). And even in that original paper (http://www.drchinese.com/David/Bell_Compact.pdf), if you examine his equations you see he does assume that the probabilities of different hidden variables λ (which in his original proof completely determine the triplet of predtermined values for each detector setting) are not in any way correlated to the choice of detector settings a and b, even if he doesn't state this explicitly (for example, in equation (21) note that he uses the same probability distribution \rho(\lambda) in calculating P(a,b) and P(a,c)). As I mentioned way back in post #861 on page 54 of this thread (http://www.physicsforums.com/showthread.php?t=395509&page=54), that's what later authors have called the "no-conspiracy assumption".
So contrary to your claims, Bell's inequality is in fact an arithmetic relationship between triples.
So what do you think he was talking about in that quote from post #1171 where he talked about the need for a "random sampling hypothesis"?
I have provided mathematical proof by deriving the exact same equation without any other assumption than the presence of triples.
In physics, you can't assume one equation is the "exact same" as the other just because they are written in the same abstract form. For example, the two inequalities in my example:

(Fraction of all nine objects with properties A+ and B-) + (Fraction of all nine objects with properties B+ and C-) greater than or equal to (Fraction of all nine objects with properties A+ and C-)

and

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

Can both be written as:

F(A+,B-) + F(B+,C-) >= F(A+,C-)

...but their meaning is very different! The first is guaranteed to hold due to basic arithmetical considerations, but the second is not, and I explicitly showed it was violated in my example. If you make some additional assumptions like the no-conspiracy assumption and the assumption of a very large number of trials, you can show that the second should hold as well, but it's clearly a different inequality than the first since it requires different assumptions to derive.
Bell also assumes the presence of triples and he obtains the same mathematical relationship. Is this a coincidence? Note also that you fail to specify the extra assumption without which Bell's inequality can not be derived, provided you already have triples like Bell assumed.
One of the extra assumptions is the no-conspiracy assumption, which is what I was referring to in the previous post when I said "But if you add some additional assumptions beyond local realism (assumptions which can themselves be justified by the details of how the experiment is conducted plus the assumption of local realism), like the assumption that the probability of different hidden triplets is not correlated with the two you actually choose to sample"...
Now if you are ready to admit claim (1)
Nope, not if (1) includes the idea that Bell's inequality has the same meaning as the arithmetical inequality just because it can be written in the same form.
but want to argue that under certain conditions a dataset of pairs will also satisfy the inequality, but not under every condition, then that is understandable but non earth-shattering because my claim (1) already lays out the conditions under which those terms involving pairs will obey the inequality -- ie, when they are extracted from a dataset of triples!!
Would you say the pairs in my example were "extracted from a dataset of triples"? The pairs were all extracted from a list of triples which would be known by an omniscient observer, though they weren't known by the experimenter so I wouldn't call them a "dataset". But if you would say that the pairs were "extracted from a datset of triples" then this is an explicit counterexample to your claim above, since the resulting pairs violated the inequality.
So you accept claim (1) but deny that the inequality so derived is Bell's inequality.
I thought it seemed to be part of claim (1) that the "inequality so derived is Bell's inequality", since part of claim (1) was "Bell's inequality is an arithmetic relationship between triples of numbers". I did ask for clarification on this point when I said "Perhaps you did not actually mean for your claim 1) to include the subclaim 1b), in which case please clarify." When I ask for clarification I'm not being rhetorical, I can't really discuss my opinion on a statement of yours if I'm unclear on what you're actually saying.
I suggest you stick to Bell's inequality rather than your toy version):
How is mine a "toy version"? A, B and C could stand for polarizer angles, with A+ and A- meaning spin-up or spin-down at some angle, for example. In that case

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

...is one of various Bell inequalities (it's exactly the one he was discussing in the quote from post #1171).
I have proven the arithmetic relationship
|ab+ac|-bc <= 1
from which it immediately follows that if you have a list of triples of numbers of any length where each number can take values (+1 or -1), the following is also true
|<ab> + <ac>| - <bc> <= 1
But it's only guaranteed to be true arithmetically if you actually know ab, ac and bc for every member of the list. If for each member of the list you can only sample two, so <ab> only refers to the average result on the subset of the list where you actually sampled a and b, then it's no longer guaranteed to be true. Do you disagree?
Bell's variables (a,b,c) constitute a triple of variables each of which can take values (+1 or -1), each symbol in the inequality has exactly the same meaning, the same as the input to my derivation. Is it your claim that using variables with the same meaning, and properties like Bell's and obtaining the inequalities like Bell without any other assumption is accidental? Yes or No?
No, it's not accidental, as any proof of a Bell-type inequality like this:

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

...would make use of the a more basic arithmetical inequality like this:

(Fraction of all triples with properties A+ and B-) + (Fraction of all triples with properties B+ and C-) greater than or equal to (Fraction of all triples with properties A+ and C-)

However, although proving the bottom inequality would be a necessary condition for deriving the top one, it would not be sufficient to derive the top one, to do so you need some additional assumptions like the no-conspiracy assumption.
If you disagree, provide a dataset of triples which obeys Bell's inequalities but violates the one I derived or vice versa.
Of course, no collection of unchanging triples could violate a basic arithmetical inequality like the one you derived. The problem is the opposite: if we are sampling pairs of variables from a collection of triples, it is possible to see a violation of a Bell inequality (which deals with observed statistics in the pairs we sampled) even when the collection of triples does not violate the more basic arithmetical inequality. My example was of exactly this type.
It should be easy for you to do. Since you claim there are other assumptions in Bell's inequality that makes my claim (1) inapplicable to Bell's inequalities, all you need do is use one of those assumptions to provide a dataset or even a single data point where both disagree.
I already showed that for the arithmetical inequality I was dealing with, are you saying you don't believe I can do something analogous for your inequality? In other words, are you saying I can't come up with a set of triples, along with a choice for each triple of which two variables are sampled by the experimenter, that violates this relation?

|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1

On the other hand, if you agree that it is possible for the above relation to be violated, despite the fact that this arithmetic relation never can be:

|(average value of a*b for all triples) + (average value of a*c for all triples)| - (average value of b*c for all triples) <= 1

...then that's exactly the point I am making, that Bell's inequality is of the first type rather than the second, so proving the second alone isn't sufficient to prove Bell's inequality.

Huh? I'm talking about Bell's inequality not your toy version. Your version bears no resemblance to what Bell actually did
There are plenty of Bell inequalities, and the one I was talking about was in fact an inequality discussed by Bell. Again see this paper (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) which I referred to in post #1171, where in equation (9) on p. 10 of the pdf he writes:
(The probability of being able to pass at 0 degrees and not able at 45 degrees)
plus
(The probability of being able to pass at 45 degrees and not able at 90 degrees)
is not less than
(The probability of being able to pass at 0 degrees and not able at 90 degrees)
Aside from the fact that I talked about fractions with a pair of properties and here he is talking about the probability of having a pair of properties, this is exactly the same as the inequality I wrote.

Anyway, like I said, I'd be happy to come up with a similar example tailored to your inequality if you really need it.
You will have to rephrase your objection in Bell's form or the form of what is actually done in Bell test experiments so that we can examine it if it makes any sense. The current version is just obfuscation and is far removed from what we are discussing.
You love to jump to the conclusion that I am "obfuscating", don't you? The thought doesn't even cross your mind that there might be some gap in your knowledge and understanding of all things Bell-related (like not knowing that my inequality is one of the Bell inequalities, as explained above), so my examples and arguments might have some relevance that just hasn't occurred to you? You really are ridiculously uncharitable when it comes to interpreting other people's arguments, you always jump to the conclusion that they are saying something foolish rather than asking questions to see if you might be missing something.
As I have demonstrated and I hope you now agree, so long as you have a list of triples in hand with values restricted to (+1 or -1), whether theoretical or measured, no matter how the list was generated, Bell's inequality is never violated (claim 6).
Disagree, since once again the Bell inequalities deal with the probabilities of measuring a given pair of values, not with the probability that all triples have a given pair of values even if those weren't the two you measured.

JesseM

Aug2-10, 08:35 PM

(continued)

Now let us examine how the experiments are actually performed. For reference, we have the inequality
|<ab> + <ac>| - <bc> <= 1
In actual experiments each term from the above is actually from a different experiment. In one run (say run 1), the experimenters measure <ab> (call it <a1b1>), from the next run, they measure <a2c2> and from the third run, they measure <b3c3>. Now you certainly will not deny that this is how such experiments are typically performed. If you disagree, say so.
Why would I disagree, when this is exactly the point I keep trying to underscore? When <ab> refers to the average of a*b only over those trials where a and b was measured, not to the average of a*b over all triples regardless of which two were measured, then the inequality is no longer guaranteed to hold by arithmetic alone, you need additional assumptions.
Your argument, as much as one can be discerned, is that in the limit as N becomes large, the fact that three different experiments are used does not matter.
Here you seem to be talking about conditions under which an inequality like this:

|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1

...can be derived. This is an entirely separate issue from the other point I was arguing, which was just the idea that the above inequality is not guaranteed to hold in spite of the fact that its arithmetical analogue is guaranteed:

|(average value of a*b for all triples) + (average value of a*c for all triples)| - (average value of b*c for all triples) <= 1

Anyway, if you agree that these types of inequalities are conceptually separate, that Bell's inequality was of the top type, and that a proof of the bottom one doesn't constitute a proof of the top (even if we assume that there were well-defined triples on each run despite the fact that we only sampled too), then at least we'd be getting somewhere. In that case we could move onto the separate question, what assumptions are needed to justify the top type of inequality, which matches the type of inequalities derived by Bell? In this case the assumption of a large number of trials is part of it, but a more important part is the idea that the probability of having a given hidden triple on each trial is not correlated to the choice of which two values were actually measured on that trial.
But that is short-sighted and misses the point of my argument.

Note that in the inequality
|<ab> + <ac>| - <bc> <= 1

a,b,c within angled brackets represent lists of numbers +1, -1. This equation can be factored as:

|<a(b+c)>| - <bc> <= 1
It doesn't make sense to me to factor <ab> + <ac> as <a(b+c)>. Suppose that a1b1 means on run #1 you measured properties a and b and got results a1 and b1, likewise a2c2 would mean on run #2 you measured properties a and c and got results a2 and c2, etc. Let's imagine a very short experiment where we measured a and b on the first three runs, and measured a and c on the next three runs, followed by b and c on the last three. Then <ab> + <ac> would be equivalent to:

(a1b1 + a2b2 + a3b3)/3 + (a4c4 + a5c5 + a6c6)/3

Or equivalently

(a1b1 + a2b2 + a3b3 + a4c4 + a5c5 + a6c6)/3

But with the averages written out in this explicit form, I don't see how it makes sense to reduce this to <a(b+c)>. If you think it does make sense, can you show what that factorization would look like written out in the same sort of explicit form?
The above implies that if <bc> = -1, then <(b+c)> must be zero, otherwise the inequality will be violated.
That doesn't seem to be true either, not if by <(b+c)> you mean the following:

(b1 + b2 + b3 + c4 + c5 + c6)/3

In that case suppose we have the following data:

a1=-1, b1=+1, a2=+1, b2=+1, a3=+1, b3=-1, a4=+1, c4=+1, a5=+1, c5=-1, a6=+1, c6=+1, b7=+1, c7=-1, b8=-1, c8=+1, b9=-1, c9=+1

In this case, <bc> = (b7c7 + b8c8 + b9c9)/3 = ((+1*-1) + (-1*+1) + (-1*+1))/3 = -1

And |<ab> + <ac>| = |(a1b1 + a2b2 + a3b3 + a4c4 + a5c5 + a6c6)/3| =
|((-1*+1) + (+1*+1) + (+1*-1) + (+1*+1) + (+1*-1) + (+1*+1))/3| = 0

So, the inequality is satisfied, since |<ab> + <ac>| - <bc> 0 - (-1) = +1

But if <(b + c)> = (b1 + b2 + b3 + c4 + c5 + c6)/3, this is equal to:

((+1) + (+1) + (-1) + (+1) + (-1) + (+1))/3 = 2/3, not zero.

Be my guest, provide a dataset of triples which violates |ab+ac|-bc <= 1. Feel free to include conspiracy, non-locally communication and any other kind of assumption you like in generating the dataset.
Again, are you just asking me to show triplets which violate this inequality?

|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1

billschnieder

Aug2-10, 10:54 PM

Bell's proof does not assume a "dataset of triples" if by "dataset" you mean the experimental data that each term in the inequality is assumed to be based on. In some variants of the proof it may assume there is some objective truth about all three members of the triple even if we can't measure them all, but the inequality only deals with measurable pairs.
You are just quibbling here. If you did not understand what I meant why were you objecting? Bell's inequality is derived by assuming the existence of triples (a,b,c) and the inequality imposes constraints on how the pairs (a,b), (a,c) and (b,c) from these triples should behave. You start out with the triples and the terms involving pairs are extracted from the triples. If you have arbitrary datasets of pairs (i,j), (k,l),(m,n) you can not calculate anything comparable to Bell's inequality UNLESS you rearrange them such that they form pairs derived from a triples just like Bell did. This is not rocket science.

And the Bell inequality is a prediction about the statistics on such a dataset of pairs, given some assumptions about how they were gathered and the laws of physics that determine their values.
Wrong. I have proven that you do not need any laws of physics to determine the same constraints between (a,b,c). Others have done it as well. Your only response to that is the claim that my derived inequality is different from Bell's. But that is hot air and you know it. I have exactly the same inequality like Bell, ALL the terms in my inequality mean exactly the same as that of Bell. Yet for some mysterious reason, you claim the two are different just because they were derived differently. That is outrageous. You have not, and can not point out any valid difference between the two inequalities because there is none. You continue to obfuscate by bringing in tangential issues. Why don't you deal with the exact equation I presented? Why do you find the need to bring in your own equation with terms defined as you like, other than to obfuscate the issue?

Not sure what you mean by "consider them together theoretically as triples", if this is an important part of your argument you'll have to explain in more detail.
Oh, I am sure you understand very well what I mean. It is exactly what Bell meant when he said on page 406 of his original article that:

It follows that c is another unit vector
P(a,b) - P(a,c) = ...

Contrary to what you seem to be claiming here, according to Bell (a,b,c) are existing together. So when he goes on to derive his inequality half a page later to be

1 + P(b,c) >= |P(a,b) -P(a,c)|

he has nothing in mind other than that those terms originate from the triple (a,b,c) which exist together. You should know this.

We may be assuming theoretically the pairs are sampled from triples, but a term in the inequality like (Fraction of A,B samples which gave result A+, B-) still deals with a collection of measured pairs (specifically the pairs where we measured A,B). Do you disagree?
Please enough of the "fraction of A,B samples ... blah blah". Bell isn't dealing with any fractions and neither am I, so why obfuscate with this nonsense. Deal with the inequality I presented or Bell's which is stated above.

According to my commonsense use of the term, you only have a "dataset of triples" if you actually measured three properties of each "object"
If you are suggesting that dataset only means something that is actually measured, then why do you insist that Bell was modelling a dataset of pairs. Bell did not actually measure anything in order to obtain his inequalities did he? He considered triples of properties ad his inequalities are defined over these triples. That is all I need. No need to obfuscate by dragging us into discussions about SQUID etc.

I don't know what you mean by "the terms in the inequality are obtained from the triples" either.
Read page 406 of Bell's original paper. He assumes that there exist 3 vectors (a,b,c), also known as a TRIPLE then he derives the inequalities

1 + P(b,c) >= | P(a,b) - P(a,c)|

Each term in the above contains only two vectors from the same TRIPLE. In other words, the symbols (a,b,c) MUST mean exactly the same thing in each term!

So if we can't make the theoretical assumption that the full values of the triple are uncorrelated with the choice of detector settings, it would be possible for Bell's inequality to be violated too even in a local realist universe? (for example, if the detectors are actually set in the past light cone of the source emitting the particles, it's conceivable the source would "know" which settings the particles will encounter on each trial and tailor the triple of values to that, in just the right way to violate the inequality)
Rubbish. Provide me a dataset of triples which violates the above inequality, for which the terms (a,b,c) mean exactly the same thing in each term. Use whatever assumptions of conspiracy or "source knowing settings" that you like. All I want is for you back up your claim that it is possible for the inequality to be violated without extra assumptions in addition to the existence of triples (a,b,c). I have been asking you this for the last 3-4 posts and you haven't provided one, yet you keep claiming that without your extra assumptions the inequality can be violated.

Bell's "original work" is highly condensed, written for an audience of physicists who can be expected to understand his implicit assumptions, it's silly to ignore all his later writings where he stated the assumptions more explicitly, like the paper I quoted in post #1171
...
In physics, you can't assume one equation is the "exact same" as the other just because they are written in the same abstract form.

What is silly is to suggest that two inequalities which are exactly identical, down to the meanings of the terms are in fact different because they were derived differently. That is silly in any field of science including physics.

For example, the two inequalities in my example:

(Fraction of all nine objects with properties A+ and B-) + (Fraction of all nine objects with properties B+ and C-) greater than or equal to (Fraction of all nine objects with properties A+ and C-)

and

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

Can both be written as:

F(A+,B-) + F(B+,C-) >= F(A+,C-)

More obfuscation masterpiece. The symbols don't mean the same thing for both cases. The terms in my inequality mean exactly the same as those in Bell's.

But it's only guaranteed to be true arithmetically if you actually know ab, ac and bc for every member of the list. If for each member of the list you can only sample two, so <ab> only refers to the average result on the subset of the list where you actually sampled a and b, then it's no longer guaranteed to be true. Do you disagree?

Huh? Isn't this what I have been telling you and you've been objecting? Isn't that exactly what my claim (1) and claim (3) are talking about? Why would you claim to object to something you actually agree with unless you like quibbling.

However, although proving the bottom inequality would be a necessary condition for deriving the top one, it would not be sufficient to derive the top one, to do so you need some additional assumptions like the no-conspiracy assumption.
All I ask is that you give conspiracy-infested dataset which violates Bell's inequality. Remember, (a,b,c) must mean the same thing in each term of the inequality, unless by conspiracy you mean failure to make sure (a,b,c) mean the same in each term, such as by using a different "a's" for different terms.

Of course, no collection of unchanging triples could violate a basic arithmetical inequality like the one you derived.
Is it your claim that they can violate Bell's inequality? And by unchanging do you mean the meanings (a,b,c) is changing from one term to the next? If that is what you mean, then that is strange because according to Bell, (a,b,c) must mean the same thing for all terms, so changing the value from term to term is not being faithful to Bell.

I already showed that for the arithmetical inequality I was dealing with, are you saying you don't believe I can do something analogous for your inequality? In other words, are you saying I can't come up with a set of triples, along with a choice for each triple of which two variables are sampled by the experimenter, that violates this relation?
You can not come up with a dataset of triples for which Bell's inequality will be violated no matter how the triples are generated, no matter the physical conditions you apply. Provide the dataset of triples and we can talk. This is my claim (1) and claim (6).
On the other hand, it is possible to come up with a dataset of pairs for which Bell's inequality will be violated. This is my claim (3). And the reason why this dataset of pairs will violate the inequality is entirely mathematical and has to do with the fact that the symbols will not mean exactly the same thing in all terms of the inequality like Bell assumed.

...then that's exactly the point I am making, that Bell's inequality is of the first type rather than the second, so proving the second alone isn't sufficient to prove Bell's inequality.
So far you seem to be agreeing with all of my claims and the so called objections are mere appearances.

Anyway, like I said, I'd be happy to come up with a similar example tailored to your inequality if you really need it.
All I ask is that you provide the dataset of triples which violates Bell's inequality. You can impose any physical constrains of your choosing, such as non-locality, conspiracy, and any other feature of your choosing. Just provide the dataset of triples. If you can not, then don't be surprised when I claim that not even FTL can violate Bell's inequalities (claim 6).

You love to jump to the conclusion that I am "obfuscating", don't you?
Because I have noted your special expertise before and I am on the lookout for it. Let's just say I know your tactics, I'm not stupid.

The thought doesn't even cross your mind that there might be some gap in your knowledge and understanding of all things Bell-related
This sounds very much like your autobiography.

(like not knowing that my inequality is one of the Bell inequalities, as explained above), so my examples and arguments might have some relevance that just hasn't occurred to you?
It clearly occurs to me that if somebody brings out every obscure form of Bell's inequalities in a discussion where simply sticking to the form being discussed will be clearer, such is an attempt either at obfuscation

You really are ridiculously uncharitable when it comes to interpreting other people's arguments, you always jump to the conclusion that they are saying something foolish rather than asking questions to see if you might be missing something.
This also sound very much like your autobiography. For example, see the following statement of yours which purports to be responding to a claim of mine but is actually not because I never argued anything of the sort being alledged.

measuring[/i] a given pair of values, not with the probability that all triples have a given pair of values even if those weren't the two you measured.

billschnieder

Aug3-10, 01:16 AM

Why would I disagree, when this is exactly the point I keep trying to underscore? When <ab> refers to the average of a*b only over those trials where a and b was measured, not to the average of a*b over all triples regardless of which two were measured, then the inequality is no longer guaranteed to hold by arithmetic alone, you need additional assumptions.

If by this you mean the inequality in which (a,b,c) mean something different from term to term needs extra assumptions to be valid, then you are not saying anything relevant to what Bell derived or what I derived. In Bell's case as in mine, (a,b,c) must mean exactly the same thing for each term. I still do not see an actual objection to my claims despite your many words. You build a straw man and then knock it down and when I point out to you that what you are knocking down is not my claim, you express surprise.

Here you seem to be talking about conditions under which an inequality like this:

|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1

...can be derived. This is an entirely separate issue from the other point I was arguing, which was just the idea that the above inequality is not guaranteed to hold in spite of the fact that its arithmetical analogue is guaranteed:

|(average value of a*b for all triples) + (average value of a*c for all triples)| - (average value of b*c for all triples) <= 1

You are confused. If I have a dataset of triples such as:
a b c
1: + + -
2: + - +
3: + - -
4: - + -
5: - - +
...

in iteration (1), if the experimenter measured (a,b) they will obtain (++) and if they measured (b,c) they would have obtained (+-). So contrary to your statements above, there is no difference between
"average value of a*b for the all triples" and "average value of a*b for all triples for which the experimenter measured a and b". So the distinction you are trying to impose on the inequalities is not there. That is why you are unable to provide a dataset of triples which satisfies one but not the other. Except of course you do not have a dataset of triples and I have explained to you what you must do in that case to get the dataset of triples from separate datasets of pairs. Otherwise the symbols in:
|<ab> + <ac>| - <bc> < = 1
will not mean the same thing from term to term! The only way you can ever violate the above inequality is if the symbols do not mean the same from term to term. If you disagree provide a dataset of triples for which the symbols in the terms mean the same thing but the inequality is violated.

It doesn't make sense to me to factor <ab> + <ac> as <a(b+c)>. Suppose that a1b1 means on run #1 you measured properties a and b and got results a1 and b1, likewise a2c2 would mean on run #2 you measured properties a and c and got results a2 and c2, etc. Let's imagine a very short experiment where we measured a and b on the first three runs, and measured a and c on the next three runs, followed by b and c on the last three. Then <ab> + <ac> would be equivalent to:

(a1b1 + a2b2 + a3b3)/3 + (a4c4 + a5c5 + a6c6)/3

Or equivalently

(a1b1 + a2b2 + a3b3 + a4c4 + a5c5 + a6c6)/3

But with the averages written out in this explicit form, I don't see how it makes sense to reduce this to <a(b+c)>.
The factorization <ab> + <ac> = <a(b+c)> is not my idea, it is Bell's. Look at page 406 of his original paper, the section leading up to equation (15) and shortly there after. And that is why you need to sort them because without doing that, you can not factorize it!

Also, you are confusing runs with iterations. Note that within angled brackets, terms such as a1,b1, etc are lists of numbers with values (+1,-1) since we are calculating averages. So if you performed three runs of the experiment in which you measured (a,b) on the first, (a,c) on the second and (b,c) on the third the averages from each run will be

<a1*b1> for run 1
<a2*c2> for run 2
<b3*c3> for run 3

The numbers after the letter correspond to the run number, not the iteration.

Again you are agreeing while appearing to disagree with me. My argument is that you can not apply Bell's inequality to dataset of pairs obtained in this way UNLESS you sort them such that a1 becomes equivalent to a2 and b2 to b3 etc. If you do not do that, you do not have terms that can be used in Bell's inequality or the one I derived.

That doesn't seem to be true either, not if by <(b+c)> you mean the following:

(b1 + b2 + b3 + c4 + c5 + c6)/3

In that case suppose we have the following data:

a1=-1, b1=+1, a2=+1, b2=+1, a3=+1, b3=-1, a4=+1, c4=+1, a5=+1, c5=-1, a6=+1, c6=+1, b7=+1, c7=-1, b8=-1, c8=+1, b9=-1, c9=+1

In this case, <bc> = (b7c7 + b8c8 + b9c9)/3 = ((+1*-1) + (-1*+1) + (-1*+1))/3 = -1

And |<ab> + <ac>| = |(a1b1 + a2b2 + a3b3 + a4c4 + a5c5 + a6c6)/3| =
|((-1*+1) + (+1*+1) + (+1*-1) + (+1*+1) + (+1*-1) + (+1*+1))/3| = 0

So, the inequality is satisfied, since |<ab> + <ac>| - <bc> 0 - (-1) = +1

Essentially you have the datasets of pairs as follows:

Run1:
a1b1
-+
++
+-

Run2:
a2c3
++
+-
++

Run3:
b3c3
+-
-+
-+

<a1b1> = -1/3
<a2c2> = 1/3
<b3c3> = -1

Note that the symbols in the inequality do not mean the same thing so we can not factor them the way Bell did. You can only factor them if you have a dataset of triples, or you resort the dataset of pairs so that it becomes a dataset of triples. Using your dataset above, let us focus the last two runs. we can write them down as follows:
a2 c2 b3 c3
+ + + -
+ - - +
+ + - +
Clearly we can resort the last two columns so that the c2 column matches the c3 column to get
a2 c2 b3 c3
+ + - +
+ - + -
+ + - +

And since c2 and c3 are now equivalent, we can drop the c3 column altogether and we now have our dataset of triples which can never violate the inequality. We do not even need the first dataset of pairs.
a c b
+ + -
+ - +
+ + -

<ab> = -1/3
<ac> = 1/3
<bc> = -1

It is now obvious why this contrived example obeyed the inequality even though the symbols were not the same.

But note now that after sorting

<a(b+c)> = <ab> + <ac> = 0

In any case, I wasn't asking you to give me a dataset of pairs which obeys the inequality. I was asking you to give me a dataset of triples which violates it.

DevilsAvocado

Aug3-10, 09:45 AM

Again, are you just asking me to show triplets which violate this inequality?

Yes, this is really what this genius is expecting.
I was asking you to give me a dataset of triples which violates it.

Mr. BS is probably the only man on this planet who sees this magnificent disproval of Bell's Theorem – where a dataset of TRIPLES is required from an entangled PAIR of TWO photons.

Absolutely brilliant.

Mr. BS has not only proven John Bell, Alain Aspect & Anton Zeilinger wrong, but also the whole board of the Wolf Foundation. Professor Alain Aspect, a member of the French Academy of Sciences and French Academy of Technologies, received together with professor Anton Zeilinger the 2010 Wolf Prize in physics (http://www.wolffund.org.il/cat.asp?id=25&cat_title=PHYSICS):
For their fundamental conceptual and experimental contributions to the foundations of quantum physics, specifically an increasingly sophisticated series of tests of Bell’s inequalities or extensions there of using entangled quantum states.

The Wolf Prizes in physics and chemistry are often considered the most prestigious awards in those fields after the Nobel Prize.

It’s absolutely amazing that one unknown man, Mr. BS, posses all this knowledge and superior intelligence.

This groundbreaking discovery must result in the 2010 Nobel Prize in Physics!

JesseM

Aug3-10, 01:02 PM

You are just quibbling here. If you did not understand what I meant why were you objecting?
Because I thought I understood, but then you objected to my statement:
It may well be that our experimental conditions are such that we only sample a pair of properties for each object, but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties (which could be known by a hypothetical omniscient observer, even if we don't sample all three ourselves).
by saying:
You are the one confused. A dataset of triples means just that. If you know only pairs you have a dataset of pairs even if you assume that there was a third value for each pair which you do not know. Simply because you can not directly calculate the LHS of Bell's inequality without the a third value and if you are calculating the LHS using a separate experiment for each term, you can not claim to have a dataset of triples. If you assume that the three values exist and you would like to consider them together theoretically as triples (like Bell did), then you have a dataset of triples not pairs.
So, that response made me realize that I didn't really understand what you were talking about.
Bell's inequality is derived by assuming the existence of triples (a,b,c) and the inequality imposes constraints on how the pairs (a,b), (a,c) and (b,c) from these triples should behave. You start out with the triples and the terms involving pairs are extracted from the triples. If you have arbitrary datasets of pairs (i,j), (k,l),(m,n) you can not calculate anything comparable to Bell's inequality UNLESS you rearrange them such that they form pairs derived from a triples just like Bell did. This is not rocket science.
Well, yes, your description of starting with theoretical triples and then extracting measured pairs seems to be identical to what I said in the quote above: "our experimental conditions are such that we only sample a pair of properties for each object, but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties". But your response to that was to say I was confused. So, were you disagreeing with my claim that Bell's proof (one version of it anyway) starts with the theoretical assumption of triples (a,b,c) whose values might be known by an omniscient observer (or by us if we're writing down a hypothetical example like the one I gave) but aren't known by the experimenter, and then assumes that "we only sample a pair of properties" for each triple, like (a,c)?
Wrong. I have proven that you do not need any laws of physics to determine the same constraints between (a,b,c). Others have done it as well. Your only response to that is the claim that my derived inequality is different from Bell's. But that is hot air and you know it. I have exactly the same inequality like Bell, ALL the terms in my inequality mean exactly the same as that of Bell.
No, they don't. The terms in the purely arithmetical inequality are of this form:

(Fraction of all triples with properties A+ and B-)

While the terms in Bell inequalities are of this form:

(Fraction of A,B samples which gave result A+, B-)

This does make a significant difference, since as I already showed, given a set of triples an inequality with terms of the first form can never be violated, but given a set of triples and a choice of which pair to sample from each triple, a similar inequality with terms of the second form can be violated. Instead of nebulous insults like "that is hot air and you know it", you might actually address what you think is wrong, specifically, with this claim. Do you disagree that even if an inequality with terms of the first form is impossible to violate, an identical-looking inequality with terms of the second form can be violated? Do you disagree that the terms in Bell's inequalities are understood to be of the second form rather than the first form? Without specifics like this I have no idea what you think is wrong with my claims.

edit: if you're going to object to my talking about 'fractions of triples' since this makes sense for other Bell inequalities but not the one you want to discuss, consider the other two forms I discuss below, comparing (average value of a*b for all triples) with (average value of a*b for all triples where experimenter sampled a and b)
Not sure what you mean by "consider them together theoretically as triples", if this is an important part of your argument you'll have to explain in more detail.
Oh, I am sure you understand very well what I mean.
Again with the uncharitable assumptions, basically accusing me of lying. As before, the reason the phrase was confusing was because it was couched as an objection to my own statement which was saying nothing more than that we were assuming theoretically the triples existed but also assuming that only a pair was sampled by the experimenter. You objected to something in my statement, and your argument involved the sentence "If you assume that the three values exist and you would like to consider them together theoretically as triples". If it wasn't for the context I would assume I did understand what this sentence meant--that at a theoretical level we assume the existence of triples, even if we don't assume they're known to the theoretical experimenter--but since this was part of an objection to my statement which said exactly the same thing, that suggested my interpretation of the meaning was wrong, leaving me unsure about what you did mean. Of course it's also possible you just misunderstood the statement of mine you were objecting to, so if you actually understood what I meant you wouldn't object.

Communication isn't always easy, but it's easier if each person asks for clarifications and doesn't instantly leap to uncharitable interpretations (including the interpretation that the other person must be lying if he claims not to understand something) and object strenuously on the basis of those interpretations.
It is exactly what Bell meant when he said on page 406 of his original article that:
It follows that c is another unit vector
P(a,b) - P(a,c) = ...
Contrary to what you seem to be claiming here, according to Bell (a,b,c) are existing together.
Sure, what sentence of mine could possibly make you think I was "claiming" otherwise? In the comment of mine you objected to, I said "but we can still consider the theoretical consequence of the assumption that each object actually had well-defined values for all three properties". So, of course I was assuming theoretically that predetermined values for each of the three detector angles (a,b,c) are existing together, even if only two are sampled by the experimenter.
So when he goes on to derive his inequality half a page later to be

1 + P(b,c) >= |P(a,b) -P(a,c)|

he has nothing in mind other than that those terms originate from the triple (a,b,c) which exist together.
Of course they "originate from the triple", that's exactly what I said in the comment you objected to.
Please enough of the "fraction of A,B samples ... blah blah". Bell isn't dealing with any fractions and neither am I, so why obfuscate with this nonsense.
Bell's inequalities typically deal with probabilities--how do you think we measure values for probabilities empirically in a Bell-type experiment? Obviously a term like P(A+, B-) would be determined empirically by looking at the fraction of A,B samples where the result was A+ and B-.

It seems like you are solely interested in considering Bell's original paper rather than any of his subsequent papers or derivations by other physicists--personally I think this is a bad idea, since as I said we are considering science rather than religious scriptures so there's nothing special about the "original" presentation of a given result, and Bell's later papers along with derivations by other authors give presentations that are more clear in assumptions Bell originally left implicit. But if you insist on considering only Bell's original paper, then it's true that in that paper a term like P(a,b) would not actually refer to a probability, but rather to an expectation value. An expectation value is just a prediction about the average value of (experimenter #1's result on with setting a)*(experimenter #2's result with setting b) in the limit of a large number of trials (to save space I'll abbreviate as the average value of a*b even though strictly speaking a and b were detector angles rather than the results for those angles). Which means in any empirical experiment you'd be considering an average of your data on sampled pairs. So if you don't like my talk about fractions (even though it's completely relevant to other Bell inequalities), you can instead consider the distinction between terms of this type:

(average value of a*b for all triples)

vs. terms of this type:

(average value of a*b for all triples where experimenter sampled a and b)

Then my claim would be that if you have a theoretical list of triples along with a pair sampled by the experimenter from each triple, you can prove by pure arithmetic that an inequality of this form is guaranteed to hold:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

But on the other hand, you can come up with such a list where an inequality of this form is violated:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

Do you disagree? If not, do you disagree that Bell's inequality is meant to be of the second form, since obviously the experimenter doesn't know the average value of b*c for all triples, including ones where he sampled a and b or a and c?

edit: before replying to this, make sure you first read post #1191 since you seem to have some confusion about what I mean by terms like (average value of b*c for all triples) and (average value of b*c for all triples where experimenter sampled b and c)--they are not equivalent, as I explain in that post.
If you are suggesting that dataset only means something that is actually measured,
That was just one interpretation of what it might mean--if you wish to specify that a purely theoretical list of triples is a "dataset of triples" that's OK with me as long as we're clear.
then why do you insist that Bell was modelling a dataset of pairs. Bell did not actually measure anything in order to obtain his inequalities did he?
Because his model included the idea of a theoretical experimenter, so he was dealing with the pairs that would actually be measured by this theoretical experimenter. "Actually" is relative to the hypothetical world you're considering, like if I said "in how many of Sherlock Holmes' cases did Watson actually make any significant contribution to solving it?"
Read page 406 of Bell's original paper. He assumes that there exist 3 vectors (a,b,c), also known as a TRIPLE then he derives the inequalities

1 + P(b,c) >= | P(a,b) - P(a,c)|

Each term in the above contains only two vectors from the same TRIPLE. In other words, the symbols (a,b,c) MUST mean exactly the same thing in each term!
In Bell's original paper the vectors a, b, c are just the detector angles, whereas P(b,c) refers to the expectation value for the products of their results (each result being +1 or -1) on trials where the first experimenter picks detector angle b and the second picks detector angle c. You can see from the form of equation (2) that P(a,b) must be an expectation value, since he takes the product of experimenter A's result (determined by the function A(a,λ)) and experimenter B's result (determined by the function B(b,λ)) and multiplies these by the probability density on that value of λ, then integrating over all possible values of λ. This means that even though the product of the two experimenter's results on a given trial (given by A(a,λ)*B(b,λ) for whatever value of λ occurs on that trial) is guaranteed to be either +1 or -1, P(a,b) can be any real number between +1 and -1, which shows that it must deal with averages over an arbitrarily large set of trials rather than results on individual trials. He also notes immediately after equation (2) that "this should equal the quantum mechanical expectation value ... But it will be shown that this is not possible" (i.e. the expectation value derived from the assumption of local hidden variables cannot possibly equal the quantum-mechanical expectation value".

I'm not sure if this contradicts what you say in the quote above. It sounded like you were saying that the equation dealt with the results we'd get for a single triple of predetermined results like (+1 on a, -1 on b, -1 on c), but I may be misinterpreting you.
Rubbish. Provide me a dataset of triples which violates the above inequality, for which the terms (a,b,c) mean exactly the same thing in each term.
Does "mean exactly the same thing in each term" suggest you want each term to deal with the results for the same single triple? If not, what does it mean? Again, what I am saying is that Bell intended his inequality to say that in a local realist universe where we're doing an experiment of a certain type, in the limit of a large number of trials we should expect the following to hold:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

...and I am saying that it is possible to come up with a list of theoretical triples (or 'dataset of triples' if you don't mean 'dataset' to imply the data known by the theoretical experimenter) where the above is violated (and if you have a mathematical rule specifying a correlation between the detector settings on each trial and the probability of getting different possible triples on each trial, in violation of the no-conspiracy assumption, you can show that the above will be violated even in the limit as the number of trials becomes arbitrary large). Do you disagree with that?
All I want is for you back up your claim that it is possible for the inequality to be violated without extra assumptions in addition to the existence of triples (a,b,c). I have been asking you this for the last 3-4 posts and you haven't provided one, yet you keep claiming that without your extra assumptions the inequality can be violated.
I already gave you an example for a different inequality, one which Bell also referred to. Again, I can give an example for the specific inequality you ask about, but I want to make sure in advance that it's OK with you if each term is of the form:

(average value of b*c for all triples where experimenter sampled b and c)

rather than the form:

(average value of b*c for all triples)

If you do think it's impossible even with the top form, then just say so and I'm happy to provide an example which proves you wrong. On the other hand, if you do agree it's possible to come up with a list of triples (along with a list of which pair were sampled for each triple) that violates the inequality with the top form, then we are in agreement about what can and can't be proved impossible with pure arithmetic, and then the question we should debate is which form Bell was implicitly assuming in his own inequality.
In physics, you can't assume one equation is the "exact same" as the other just because they are written in the same abstract form.
What is silly is to suggest that two inequalities which are exactly identical, down to the meanings of the terms are in fact different because they were derived differently.
Well, good thing I wasn't suggesting that then eh? I was suggesting that the two inequalities are not identical because the "meaning of their terms" is not identical. I think I made that pretty clear when I said (immediately after the sentence you just quoted) the following:
For example, the two inequalities in my example:

(Fraction of all nine objects with properties A+ and B-) + (Fraction of all nine objects with properties B+ and C-) greater than or equal to (Fraction of all nine objects with properties A+ and C-)

and

(Fraction of A,B samples which gave result A+, B-) + (Fraction of B,C samples which gave result B+, C-) greater than or equal to (Fraction of A,C samples which gave result A+,C-)

Can both be written as:

F(A+,B-) + F(B+,C-) >= F(A+,C-)

...but their meaning is very different!
Would you disagree the physical meaning of F(A+,B-) depending on whether we interpret it to mean (Fraction of all nine objects with properties A+ and B-) or if we interpret it to mean (Fraction of A,B samples which gave result A+, B-)?

Now, I know you have a habit of refusing to discuss any of the inequalities which appeared in papers other than the very first paper Bell ever wrote about the inequality, so I can rephrase this by comparing the following inequalities:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

vs.

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

Would you agree the meaning of these inequalities is different, even though they can both be written in the abstract form 1 + P(b,c) >= |P(a,b) - P(a,c)| ?

JesseM

Aug3-10, 01:02 PM

(response to post #1186 continued)
The terms in my inequality mean exactly the same as those in Bell's.
In your inequality, does P(b,c) refer to "average value of b*c for all triples where experimenter sampled b and c"? If it does, then it's not hard to find a set of triples that violates your inequality. And if it doesn't, then no, the terms in your inequality don't mean the same thing as those in Bell's.
But it's only guaranteed to be true arithmetically if you actually know ab, ac and bc for every member of the list. If for each member of the list you can only sample two, so <ab> only refers to the average result on the subset of the list where you actually sampled a and b, then it's no longer guaranteed to be true. Do you disagree?
Huh? Isn't this what I have been telling you and you've been objecting? Isn't that exactly what my claim (1) and claim (3) are talking about? Why would you claim to object to something you actually agree with unless you like quibbling.
I don't know what your overall point is supposed to be since your whole argument appears rather confused to me, so my objection wasn't to any overall point you were trying to make but rather to the specific claim you made in (1) (and possibly in (3) too, although I explained in post #1179 that I thought the meaning of (3) was ambiguous and asked for clarification which you didn't provide), considered on their own and not in the context of your whole argument. I already explained that I disagree with (1) because Bell's inequality is not just an arithmetic inequality, the meaning of the terms in his inequality is different--in a purely arithmetic inequality with the same equation each term would have a meaning like (average value of b*c for all triples), but in Bell's inequality each term has a meaning like (average value of b*c for all triples where experimenter sampled b and c). And because of this difference in meaning, proofs of the Bell inequality require a few additional physical assumptions beyond what's required to prove the arithmetic inequality.
All I ask is that you give conspiracy-infested dataset which violates Bell's inequality. Remember, (a,b,c) must mean the same thing in each term of the inequality, unless by conspiracy you mean failure to make sure (a,b,c) mean the same in each term, such as by using a different "a's" for different terms.
If "a" refers to a choice of detector angle then I am assuming the same a for each term (and as I noted before, I use the notation a*b to refer not to the product of the two detector angles, but the product of the two experimenter's results when they choose detector angles a and b). On the other hand, if "a" refers to the predetermined value of a given triple for setting a or something along those lines, then I'm not clear on what you mean by 'using different "a's" for different terms". In this inequality, would you say I am using different "a's" for different terms or not?

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

If you would say I am using different "a's" here that's fine, but then my point is that this is the meaning of the terms in Bell's inequality. So, in that case it seems what you're asking for is not a "conspiracy-infested dataset which violates Bell's inequality", but rather a data set which violates some inequality where the terms have a different meaning than they do in Bell's, like this one:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

...but I have said all along that you can prove by pure arithmetic that it's impossible to find a collection of unchanging triples that violates this inequality. The point is that this is not Bell's inequality since the terms have the wrong meaning, which is why I objected to (1).
And by unchanging do you mean the meanings (a,b,c) is changing from one term to the next?
No, I meant that the triplet hidden variables associated with the three detector settings a,b,c may be changing with time for a single pair of particles, so that if you measure the first particle with detector setting a, that may change the three hidden variables associated with the second particle if you measure it at a slightly later time. If there is not a spacelike separation between the two measurements, then you can have a local hidden variables theory of this form which seems to violate some Bell inequality by exploiting the "locality loophole".
On the other hand, it is possible to come up with a dataset of pairs for which Bell's inequality will be violated. This is my claim (3).
Again, I need clarification on this claim before I can tell you if I agree or disagree. Are you assuming that the "dataset of pairs" is derived from a list of triples in some way, or are we just making up pairs in a totally arbitrary way? If the pairs are derived from a list of triples in some way, how exactly?
And the reason why this dataset of pairs will violate the inequality is entirely mathematical and has to do with the fact that the symbols will not mean exactly the same thing in all terms of the inequality like Bell assumed.
Also not clear on what "the symbols will not mean exactly the same thing in all terms of the inequality" means. For the inequality 1 + P(b,c) >= |P(a,b) - P(a,c)|, would you say the symbols mean the same thing in all the terms if we interpret the meaning like this?

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

How about if we interpret the meaning like this?

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|
Because I have noted your special expertise before and I am on the lookout for it. Let's just say I know your tactics, I'm not stupid.
In other words, you assume that my genuine confusion about your arguments must be a deceptive "tactic"--that's exactly what I mean by "uncharitable interpretation". In fact it's not true, I genuinely am not sure what the hell you are trying to say half the time, but you have such a reactionary/paranoid mindset that I don't imagine I can ever convince you otherwise.
(like not knowing that my inequality is one of the Bell inequalities, as explained above), so my examples and arguments might have some relevance that just hasn't occurred to you?
It clearly occurs to me that if somebody brings out every obscure form of Bell's inequalities in a discussion where simply sticking to the form being discussed will be clearer, such is an attempt either at obfuscation
You didn't make clear at the outset that "the form being discussed" was the one in his original paper, in this recent discussion of ours I was the first one to bring up a specific mathematical inequality, first in post #1171 where I quoted a paper from Bell and then again in post #1176 where I talked about

Number(A, not B) + Number(B, not C) greater than or equal to Number(A, not C)

Then in post #1179 I again referred to that inequality, showing that the purely arithmetic version of the inequality can't be violated by a series of triples, but a Bell-type inequality with the same equation can be. It wasn't until post #1182 that you brought up the inequality |ab+ac|-bc <= 1. It's not really fair that you should have total control over the terms of the discussion in this way, but as seen above I'm fine with discussing this inequality too. Still it's a bit much that you now accuse me of an attempt at obfuscation because I brought up a specific example in what had previously been an overly abstract discussion, and then I didn't immediately drop that example when you brought up a slightly different one.

Also, the inequality I mention is hardly "obscure", if you didn't have a single-minded interest in Bell's original paper only and instead looked at discussions of Bell's inequality by other authors, you'd see that this inequality is mentioned more often in introductory discussions of Bell's proof than the one in the original paper, perhaps because it's so much simpler to see how it's derived (I gave a quick derivation in post #1179 when I said 'the proof is trivial--every triplet with A+ and C- must either be of type A+B+C- or type A+B-C-, and if the former it will also contribute to the number with B+ and C-, if the latter it will also contribute to the number with A+ and B-'). I already gave a link to one website (http://www.upscale.utoronto.ca/PVB/Harrison/BellsTheorem/BellsTheorem.html) which uses it as a starting point, and wikipedia refers to this inequality as Sakurai's Bell inequality (http://en.wikipedia.org/wiki/Sakurai's_Bell_inequality) because it appeared in Sakurai's widely-used 1994 textbook on QM (the wikipedia article mentions a number of other well-known papers and books on Bell's proof that have used it).
You really are ridiculously uncharitable when it comes to interpreting other people's arguments, you always jump to the conclusion that they are saying something foolish rather than asking questions to see if you might be missing something.
This also sound very much like your autobiography. For example, see the following statement of yours which purports to be responding to a claim of mine but is actually not because I never argued anything of the sort being alledged.
Disagree, since once again the Bell inequalities deal with the probabilities of measuring a given pair of values, not with the probability that all triples have a given pair of values even if those weren't the two you measured.
This was in response to your statement:
As I have demonstrated and I hope you now agree, so long as you have a list of triples in hand with values restricted to (+1 or -1), whether theoretical or measured, no matter how the list was generated, Bell's inequality is never violated (claim 6).
Are you saying that you would agree with both the following claims A and B?

(A) In Bell's inequality 1 + P(b,c) >= |P(a,b) - P(a,c)|, the correct interpretation of the meaning of the terms would be:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

(B) With that interpretation of the meaning, it is possible to find a list of triples with values restricted to (+1 or -1) that violates the inequality

If you disagree with either of those, then it seems there was no fault in my understanding of (6) or the "As I have demonstrated..." quote, since my comment "Disagree, since once again the Bell inequalities deal with the probabilities of measuring a given pair of values" was meant as an assertion of point (A), and I had already explained earlier in the post about why I believed point (B).

In any case, on the subject of "uncharitable" interpretations, you can probably find occasional examples where I jumped to an erroneous conclusion about what you were saying, but I think you can find many more examples where I said what I thought you might be saying but then asked questions to check if I was misinterpreting. For example, just from the post you were responding to above:
Not sure what you mean by "consider them together theoretically as triples", if this is an important part of your argument you'll have to explain in more detail. We may be assuming theoretically the pairs are sampled from triples, but a term in the inequality like (Fraction of A,B samples which gave result A+, B-) still deals with a collection of measured pairs (specifically the pairs where we measured A,B). Do you disagree?
Based on your comment above I no longer know what you mean when you say "datasets of triples", you seem to be using that phrase in a rather odd way that you have never defined ... If you disagree, please give a careful definition of what you mean by the phrases "dataset of pairs" and "dataset of triples".
I don't know what you mean by "the terms in the inequality are obtained from the triples" either ... Do you disagree that the terms in Bell's inequality also deal only with subsets of all the entangled particle pairs that were measured
Now if you are ready to admit claim (1)
Nope, not if (1) includes the idea that Bell's inequality has the same meaning as the arithmetical inequality just because it can be written in the same form. [that 'if' refers to my earlier request for clarification about (1) which you haven't responded to]
Would you say the pairs in my example were "extracted from a dataset of triples"? The pairs were all extracted from a list of triples which would be known by an omniscient observer, though they weren't known by the experimenter so I wouldn't call them a "dataset". But if you would say that the pairs were "extracted from a datset of triples" then this is an explicit counterexample to your claim above, since the resulting pairs violated the inequality.
I thought it seemed to be part of claim (1) that the "inequality so derived is Bell's inequality", since part of claim (1) was "Bell's inequality is an arithmetic relationship between triples of numbers". I did ask for clarification on this point when I said "Perhaps you did not actually mean for your claim 1) to include the subclaim 1b), in which case please clarify." When I ask for clarification I'm not being rhetorical, I can't really discuss my opinion on a statement of yours if I'm unclear on what you're actually saying.
But it's only guaranteed to be true arithmetically if you actually know ab, ac and bc for every member of the list. If for each member of the list you can only sample two, so <ab> only refers to the average result on the subset of the list where you actually sampled a and b, then it's no longer guaranteed to be true. Do you disagree?
I already showed that for the arithmetical inequality I was dealing with, are you saying you don't believe I can do something analogous for your inequality? In other words, are you saying I can't come up with a set of triples, along with a choice for each triple of which two variables are sampled by the experimenter, that violates this relation?
So, in this single post you can see a lot of examples where I don't just leap to uncharitable conclusions about what you're saying, but instead ask questions to try to clarify. I think if we looked over a bunch of your previous posts we'd find very few instances where you thought I might be saying something foolish but asked for clarifications rather than immediately jumping to the conclusion I was. So even though you can probably find some instances of me jumping to uncharitable conclusions, I think it's safe to say that the degree to which you do this to me is a lot greater. And likewise you are now getting into nasty comments about my motives and suggesting that any comments of mine that don't immediately reach the correct conclusion about what you were saying must be a deliberate "tactic" (as if I really did understand you perfectly well but was pretending not to in order to annoy you)--it would more charitable to just assume I was a bit thick! But of course the most charitable and fair assumption is that communication about complex issues like these is sometimes difficult and arguments that may seem clear to you can seem genuinely ambiguous to intelligent readers who aren't privy to all your thought processes.

JesseM

Aug3-10, 02:11 PM

If by this you mean the inequality in which (a,b,c) mean something different from term to term needs extra assumptions to be valid,
See my most recent response to your post #1186 for a request for clarification on what you mean by "something different from term to term."
You are confused. If I have a dataset of triples such as:
a b c
1: + + -
2: + - +
3: + - -
4: - + -
5: - - +
...

in iteration (1), if the experimenter measured (a,b) they will obtain (++) and if they measured (b,c) they would have obtained (+-). So contrary to your statements above, there is no difference between
"average value of a*b for the all triples" and "average value of a*b for all triples for which the experimenter measured a and b".
Sure there's a difference. Suppose our dataset consisted only of the five you mention, and that for each iteration the pair measured was as follows:

a b c
1: + + - (measured a,b)
2: + - + (measured b,c)
3: + - - (measured a,c)
4: - + - (measured a,b)
5: - - + (measured b,c)

In this case, "average value of a*b for all triples" = [(value of a*b for #1) + (value of a*b for #2) + (value of a*b for #3) + (value of a*b for #4) + (value of a*b for #5)]/5 =
[(+1) + (-1) + (-1) + (-1) + (+1)]/5 = -1/5

On the other hand, "average value of a*b for all triples for which the experimenter measured a and b" would only include triple #1 and triple #4, so it'd be [(value of a*b for #1) + (value of a*b for #4)]/2 = [(+1) + (-1)]/2 = 0.

Using pure arithmetical reasoning, we can prove this inequality must hold for all datasets of triples, including the above:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

But without additional assumptions we cannot prove this inequality:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

Do you disagree?
The factorization <ab> + <ac> = <a(b+c)> is not my idea, it is Bell's. Look at page 406 of his original paper, the section leading up to equation (15) and shortly there after.
I don't see anything on that page where he does a factorization like P(a,b) + P(a,c) = P(a*(b+c)), can you quote the line you're referring to?
Also, you are confusing runs with iterations. Note that within angled brackets, terms such as a1,b1, etc are lists of numbers with values (+1,-1) since we are calculating averages. So if you performed three runs of the experiment in which you measured (a,b) on the first, (a,c) on the second and (b,c) on the third the averages from each run will be

<a1*b1> for run 1
<a2*c2> for run 2
<b3*c3> for run 3
You mean each "run" consists of multiple pairs of particles that are each measured with the same detector settings? And that notation like a1 only refers to the "run" and not the iteration? That's fine with me, but we are still free to introduce some more detailed notation like a1,3 to mean "the third iteration of the first run", and then my objections to your math could be rephrased in terms of this new notation. For example, if each run consisted of only three iterations, then notation like <a1*b1> could be written out in "long form" as:

(a1,1*b1,1 + a1,2*b1,2 + a1,3*b1,3)/3

...and then I still wouldn't know what to make of the notation <ab> + <ac> = <a(b+c)>. To rephrase my previous comments in terms of this notation

Then <a1*b1> + <a2*c2> would be equivalent to:

(a1,1*b1,1 + a1,2*b1,2 + a1,3*b1,3)/3 + (a2,1*c2,1 + a2,2*c2,2 + a2,3*c2,3)/3

But with the averages written out in this explicit form, I don't see how it makes sense to reduce this to <a(b+c)>. If you think it does make sense, can you show what that factorization would look like written out in the same sort of explicit form?
Again you are agreeing while appearing to disagree with me. My argument is that you can not apply Bell's inequality to dataset of pairs obtained in this way UNLESS you sort them such that a1 becomes equivalent to a2 and b2 to b3 etc. If you do not do that, you do not have terms that can be used in Bell's inequality or the one I derived.
I'm not clear on what you mean by "sort them such that a1 becomes equivalent to a2 and b2 to b3 etc.", but later you do give an example of such "sorting" so I'll wait until later to ask questions about it.

In any case, my disagreement once again lies with your claims that Bell's inequality is nothing more than the type of purely arithmetical inequality that we can prove must hold, of this type:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

Rather, Bell's inequality is of this type:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

...and of course some lists of pairs sampled from triplets can violate this second inequality, but the inequality can nevertheless be justified with some additional physical assumptions, which are exactly the ones made in derivations of Bell's inequality.
Essentially you have the datasets of pairs as follows:

Run1:
a1b1
-+
++
+-

Run2:
a2c3
++
+-
++

Run3:
b3c3
+-
-+
-+

<a1b1> = -1/3
<a2c2> = 1/3
<b3c3> = -1

Note that the symbols in the inequality do not mean the same thing so we can not factor them the way Bell did. You can only factor them if you have a dataset of triples, or you resort the dataset of pairs so that it becomes a dataset of triples. Using your dataset above, let us focus the last two runs. we can write them down as follows:
a2 c2 b3 c3
+ + + -
+ - - +
+ + - +
Clearly we can resort the last two columns so that the c2 column matches the c3 column to get
a2 c2 b3 c3
+ + - +
+ - + -
+ + - +

And since c2 and c3 are now equivalent, we can drop the c3 column altogether and we now have our dataset of triples which can never violate the inequality.
OK, so here you're talking about combining a's and c's from the second run (where a and c were measured) with b's from the third run (where b and c were measured) and treating them all as "triples". In effect you're just showing that if we have 3 runs of N iterations each, then we can prove in a purely arithmetic way that this inequality must hold:

1 + \mbox{$ 1/N \sum_{i=1}^N $} bj,i*ck,i (where j represents the run where the experimenter sampled b and c, while k represents the run where a and c were sampled)
>= |\mbox{$ 1/N \sum_{i=1}^N $} ak,i*bj,i (where j represents the run where the experimenter sampled b and c, while k represents the run where a and c were sampled) - \mbox{$ 1/N \sum_{i=1}^N $} ak,i*ck,i (where k represents the run where a and c were sampled)|

But of course this is totally different from Bell's inequality! Bell's inequality takes this form:

1 + \mbox{$ 1/N \sum_{i=1}^N $} bj,i*cj,i (where j represents the run where the experimenter sampled b and c)
>= |\mbox{$ 1/N \sum_{i=1}^N $} ak,i*bk,i (where k represents the run where the experimenter sampled a and b) - \mbox{$ 1/N \sum_{i=1}^N $} al,i*cl,i (where l represents the run where the experimenter sampled a and c)|

...and neither Bell nor any other physicist would claim that an inequality like this could be derived in a purely arithmetic manner! You can derive it using additional physical assumptions, which would be mentioned in any really rigorous derivation of a Bell inequality, although Bell's original paper left some things implicit (and perhaps some necessary conditions hadn't occurred to him yet).

DevilsAvocado

Aug3-10, 02:34 PM

JesseM, let me tell you what is going to happen next. Mr BS is now going to accuse you for not answering his questions, and writing to long posts, and dealing with the wrong subjects that Mr. BS did not 'approved', etc, etc.

After yet another posts, the personal attacks will boost from Mr BS.

And finally it all breaks down in an: "Agreement not to agree."

And after a couple of days (when you are not around), Mr BS will triumphantly conclude that he has indeed proved that Bell's Theorem is faulty, and that no one can prove him wrong.

Funny isn’t it?

JesseM, I truly admire your will to help users here on PF, to learn new important things about science. It’s a very likeable attitude. And I really mean it.

But this is something else. Your discussion with Mr. BS is not about learning and it’s definitely not about science. It’s about obsession, preconceptions and pure madness.

Mr. BS has already decided that Bell's Theorem is dead wrong no matter what – and there is absolutely nothing whatsoever you, or anyone else, can do about it. It’s a fact, in fact the only fact about Mr. BS.

Mr. BS 'approach' is extremely similar to Crackpot Kracklauer and his "Non-loco Physics (http://www.nonloco-physics.000freehosting.com/)", which is nothing more than a crusade against contemporary physics - Quantum Mechanics and Relativity:
``Loco'' (Spanish for `crazy'). Contemporary Physics is vexed by some really ``loco'' ideas, with nonlocality and asymmetric aging leading the list. (The title is an obvious play on the word ``nonlocal,'' which, in this writer's opinion, is the epitome of a `loco' idea.)

This webpage publicizes an independent research project, the goal of which is to purge selected 'loco' ideas from the discipline of Physics. Why? There are two reasons. One is strictly internal to the profession; it is to foster the unification of Quantum Mechanics and Relativity. It is widely recognized, that despite considerable success so far, the job is not done. Most obviously, gravity is not yet included. What's worse really: there is no accepted covariant wave equation for multiple, interacting particles; and, it turns out that, the obstacles to writing such an equation are just those features leading to nonlocality and asymmetric aging. For those interested, the background story:
...
It was with all this in mind, that this research program was undertaken. As a concrete matter, this effort has focused on two features characterized by goofy conceptualism and faulty math: non-locality and asymmetric aging. Below, the progress made attacking these `loco' ideas will be delineated in some detail.

Do I need to say that billschnieder is a big fan of Crackpot Kracklauer...

I truly hope you see what’s "at crazy stake" here? If "independent researcher" Crackpot Kracklauer can prove nonlocality and asymmetric aging wrong – he will find TOE! :rofl:

And I’m pretty sure Mr. BS agrees...

Open your eyes JesseM.

JesseM

Aug3-10, 05:20 PM

Mr. BS 'approach' is extremely similar to Crackpot Kracklauer and his "Non-loco Physics (http://www.nonloco-physics.000freehosting.com/)", which is nothing more than a crusade against contemporary physics - Quantum Mechanics and Relativity:
In this case I think his arguments are more likely to be inspired by Possible Experience: from Boole to Bell (http://arxiv.org/abs/0907.0767) which I have discussed with him in the past (see post 941 (http://www.physicsforums.com/showpost.php?p=2780659&postcount=941) and post 961 (http://www.physicsforums.com/showpost.php?p=2781956&postcount=961) on this thread (http://www.physicsforums.com/showthread.php?t=395509&page=61)). His odd notions about Bell's inequality being purely arithmetical, and about the idea of "resorting" the data which I responded to in post #1191, seem inspired by the discussion in that paper, which showed how a certain inequality superficially similar to one of Bell's can be derived, but if you have the freedom to arbitrarily relabel which values of a are multiplied by which value of b and so forth, then you can violate that inequality. Bill seems to have taken this as some kind of general argument against all versions of Bell's theorem, even though these derivations make more specific assumptions which results from a and b are multiplied (i.e. the ones that actually represent measurements from a single pair of entangled particles with detector settings a and b), so all that the paper really shows is that if you violate some of the assumptions in Bell inequality derivations you can produce violations of those inequalities under local realism. Anyway, if Bill is bothered by the length of my responses he can always ignore the first two and just concentrate on my post #1191 where I focused on this issue of "resorting" and what the exact meaning of the terms in Bell's inequality is supposed to be.

Incidentally, you're probably right that I won't be able to change his mind, but there's a chance I could get him to modify at least some of his arguments, and in any case as long as he keeps posting these anti-Bell arguments it may be useful to other readers to have someone to point out the flaws in these arguments.

DevilsAvocado

Aug3-10, 06:56 PM

In this case I think his arguments are more likely to be inspired by Possible Experience: from Boole to Bell which I have discussed with him in the past (see post 941 and post 961 on this thread). His odd notions about Bell's inequality being purely arithmetical, and about the idea of "resorting" the data which I responded to in post #1191, seem inspired by the discussion in that paper, which showed how a certain inequality superficially similar to one of Bell's can be derived, if you have the freedom to arbitrarily relabel which values of a are multiplied by which value of b and so forth, then you can violate that inequality. Bill seems to have taken this as some kind of general argument against all versions of Bell's theorem, even though these derivations make more specific assumptions which results from a and b are multiplied (i.e. the ones that actually represent measurements from a single pair of entangled particles with detector settings a and b), so all that the paper really shows is that if you violate some of the assumptions in Bell inequality derivations you can produce violations of those inequalities under local realism.

Yes, that’s probably correct about "Boole to Bell", and also "some kind of general argument against all versions of Bell's theorem" seems to be spot on. Bill started his 'career' in PF like this:
Trying to Understand Bell's reasoning
...
1) Bell's ansatz (equation 2 in his paper) correctly represent those local-causal hidden variables
2). Bell's ansatz necessarily lead to Bell's inequalities
3). Experiments violate Bell's inequalities
Conclusion: Therefore the real physical situation of the experiments is not Locally causal.

There is no doubt in my mind that statement (2) has been proven mathematically since I do not know of any mathematical errors in Bells derivation. Similarly, there is very little doubt in my mind that experiments have effectively demonstrated that Bell's inequalities are violated. I say little doubt because no loophole-free experiments have yet been performed but for the sake of this discussion we can assume that loopholes do not matter.

There is nothing wrong in changing one’s mind about these questions, but the problem is that he cannot explain this mathematical "U-turn" in a convincing way.

As I see it, you punctured his first argument against Bell, and then he needed a new one, and on the way – he made a contradiction to himself!

(Also the extremely farfetched assumption that John Bell was incapable of calculate the probability of getting one red or one white card out of a box, at least makes me laugh.)

Anyway, if Bill is bothered by the length of my responses he can always ignore the first two and just concentrate on my post #1191 where I focused on this issue of "resorting" and what the exact meaning of the terms in Bell's inequality is supposed to be.

I don’t think Bill is really bothered by the length of your responses. He is bothered by that you have more knowledge and intelligence than him. That’s why he’s upset – you beat him on every point. And as you say – the scrollbar is always there and it does not cost one penny to use (which makes these kinds of 'complaints' hilarious :smile:).

Incidentally, you're probably right that I won't be able to change his mind, but there's a chance I could get him to modify at least some of his arguments, and in any case as long as he keeps posting these anti-Bell arguments it may be useful to other readers to have someone to point out the flaws in these arguments.

Please note Jesse – my last post was absolutely no critic about you, or your posts. It’s just admirable that you have the determination to continue the 'discussion' with Bill!

I just felt... well how should I put it... almost "sorry" (don’t take it wrong) for you... spending all this time and energy on Bill, when probably nothing in this world will change his mind...

But you are absolutely right – all unjustified arguments should be challenged.

I just can’t get in to my head how Bill’s "logic" works... To me this looks like an "Apollo Moon Hoaxer" starting his "mission" by trying to find a mathematical flaw in Newton's law of universal gravitation – "They could never have left the planet in the first place!!"

Megalomania...?

DevilsAvocado

Aug4-10, 05:49 AM

DevilsAvocado

Aug4-10, 07:45 AM

I just have to share this quote, from Demystifier's Blog (http://www.physicsforums.com/blog.php?b=1816), which seems to be tailored for "one" in this thread:

"Scientists are clever, but the problem with them is that sometimes they are too clever to see the obvious." -- Hrvoje Nikolic

:smile:

JesseM

Aug4-10, 10:18 AM

JesseM, if you have the time:

What will happen if we run an EPR-Bell experiment, with entangled photons, and decide to never measure Bob’s photons?

Will Alice photons be measured in the same way as unpolarized light, i.e. a random 50/50 distribution over all angles?

And if the above is correct - Is there any way to distinguish the random 50/50 distribution above from one where we do measure Bob’s photons (without comparing Alice & Bob’s results)?
Yup, Alice's photons alone should show a random 50/50 distribution for a polarizer at any given angle, and I don't think there's any way to tell, just by measuring the polarization of Alice's photons alone, whether they're entangled. However, there are other cases where if you only measure one half of a collection of entangled pairs, you can deduce that they were entangled--for example, if the two photons are entangled in such a way that a measurement of the position of photon B could allow you to deduce which of two slits photon A went through, then the probability distribution for A alone would not show an interference pattern, whereas if you sent a photon through a double-slit without any way of measuring which slit it went through the probability distribution would show interference as in the standard double-slit experiment (there's a discussion on this thread (http://www.physicsforums.com/showthread.php?t=278921) for example).

DevilsAvocado

Aug4-10, 10:57 AM

Yup, Alice's photons alone should show a random 50/50 distribution for a polarizer at any given angle, and I don't think there's any way to tell, just by measuring the polarization of Alice's photons alone, whether they're entangled. However, there are other cases where if you only measure one half of a collection of entangled pairs, you can deduce that they were entangled

Right there I almost spilled my coffee all over the place – FTL messaging! :surprised

(:smile:)

But then I realized you are talking about the Delayed choice quantum eraser (http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser), right?

http://upload.wikimedia.org/wikipedia/commons/thumb/2/21/Kim_EtAl_Quantum_Eraser.svg/500px-Kim_EtAl_Quantum_Eraser.svg.png

Thanks for the info. Just a small follow-up:

We can regard the two entangled photons in EPR-Bell as unpolarized light. That must mean that there is no "coordinate system" that the photons must "obey". When we talk about calibrating the polarizers, it’s just for our own "convenience" when measuring at 0º, 22.5º, 45º, etc, right?

Or to put it frank – the entangled photons doesn’t "care" about the actual individual angles on the polarizers, it’s the relative angle between the two polarizers that makes all the difference, right?

DrChinese

Aug4-10, 12:01 PM

Oh, I am sure you understand very well what I mean. It is exactly what Bell meant when he said on page 406 of his original article that:

...

Contrary to what you seem to be claiming here, according to Bell (a,b,c) are existing together. So when he goes on to derive his inequality half a page later to be

1 + P(b,c) >= |P(a,b) -P(a,c)|

he has nothing in mind other than that those terms originate from the triple (a,b,c) which exist together. You should know this.
Read page 406 of Bell's original paper. He assumes that there exist 3 vectors (a,b,c), also known as a TRIPLE then he derives the inequalities

1 + P(b,c) >= | P(a,b) - P(a,c)|

Each term in the above contains only two vectors from the same TRIPLE. In other words, the symbols (a,b,c) MUST mean exactly the same thing in each term!

Rubbish. Provide me a dataset of triples which violates the above inequality, for which the terms (a,b,c) mean exactly the same thing in each term. Use whatever assumptions of conspiracy or "source knowing settings" that you like. All I want is for you back up your claim that it is possible for the inequality to be violated without extra assumptions in addition to the existence of triples (a,b,c). I have been asking you this for the last 3-4 posts and you haven't provided one, yet you keep claiming that without your extra assumptions the inequality can be violated.

...

All I ask is that you provide the dataset of triples which violates Bell's inequality. You can impose any physical constrains of your choosing, such as non-locality, conspiracy, and any other feature of your choosing. Just provide the dataset of triples. If you can not, then don't be surprised when I claim that not even FTL can violate Bell's inequalities (claim 6).

I am glad we are on the same page. :smile: If you assume that the triple is simultaneously well defined, you always come into problems - just as you say. I am not certain that is resolved even with an FTL influence - just as you say. (After all, what was the 3rd value and when does it gain, lose or change its value?)

If on the other hand, you insist that (measured) pairs from the triple are all that are real... well, that goes against EPR's criterion in favor of the Bohr approach.

JesseM

Aug4-10, 12:21 PM

But then I realized you are talking about the Delayed choice quantum eraser (http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser), right?
Yup, that's what I was thinking of, although there are other similar experimental setups where the same is true--basically any setup with the basic form seen in Fig. 2 of this paper (http://www.hep.yorku.ca/menary/courses/phys2040/misc/foundations.pdf) (on p. 3 of the pdf)
We can regard the two entangled photons in EPR-Bell as unpolarized light. That must mean that there is no "coordinate system" that the photons must "obey". When we talk about calibrating the polarizers, it’s just for our own "convenience" when measuring at 0º, 22.5º, 45º, etc, right?

Or to put it frank – the entangled photons doesn’t "care" about the actual individual angles on the polarizers, it’s the relative angle between the two polarizers that makes all the difference, right?
Right, only the relative angles matter, each angle is defined relative to an arbitrary choice of coordinate system.

DevilsAvocado

Aug4-10, 04:18 PM

Right, only the relative angles matter, each angle is defined relative to an arbitrary choice of coordinate system.

Thanks Jesse, that is how I have pictured it. But... I don’t really get why we talk about entangled photons like up/down spin... if polarization is a result of spin... and they are unpolarized...??

Or is the explanation that polarized light looks something like this (where the electric force moves up and down perpendicular to the ray direction):

http://www.colorado.edu/physics/2000/polarization/images/electroArrow.gif

And unpolarized light looks something like this:

http://www.colorado.edu/physics/2000/polarization/images/arrowThickAnim.gif

But why are we talking about up/down spin...

JesseM

Aug4-10, 05:01 PM

Thanks Jesse, that is how I have pictured it. But... I don’t really get why we talk about entangled photons like up/down spin... if polarization is a result of spin... and they are unpolarized...??
In classical electromagnetism, I think "polarized" light would just be a beam where if you pick the correct angle for your polarizer 100% of the light will pass through, whereas "unpolarized" would mean no matter what angle you set your polarizer, the intensity would be reduced when the beam passes through it. With individual photons, they have a quantum state which determines the probability they'll make it through a polarizer at any given angle--thinking about it some more, I may have been mistaken to say that they'd always have a 50% chance of passing through a polarizer if their polarization hadn't been previously measured, it might be that even though no polarization measurement had ever been made, knowledge of the properties of the source would give you an initial quantum state that would have different probabilities at different angles, I'm not sure exactly how the initial quantum state of an entangled pair would be defined for a given type of source. Anyway, the main point is that once a photon has passed through a polarizer at a given angle, then it's guaranteed with probability 1 to pass through another polarizer at the same angle (or to have a probability 0 of passing through a polarizer at a 90 degree angle to the first) provided nothing is done to it in between, like passing it through a polarizer at a different angle (if you do that it means there is there is now some finite probability it will pass through a polarizer at a right angle to the first, which can be seen in the very counterintuitive Dirac three polarizers experiment (http://www.informationphilosopher.com/solutions/experiments/dirac_3-polarizers/) where you have two polarizers at right angles that don't allow any light to get through so they look black, but then if you put another polarizer in between them, you see light coming through all three in the area covered by the middle one). And for photons with entangled polarizations, if one member of the pair passes through a polarizer at a given angle, then you can predict with certainty whether the other will pass through a polarizer at the same angle (or at 90 degrees relative to the first).

DevilsAvocado

Aug4-10, 05:24 PM

Thanks Jesse, I have to check out the Dirac experiment and think some more. I'll get back tomorrow.

billschnieder

Aug4-10, 09:27 PM

No, they don't. The terms in the purely arithmetical inequality are of this form:
(Fraction of all triples with properties A+ and B-)
While the terms in Bell inequalities are of this form:
(Fraction of A,B samples which gave result A+, B-)

Here again you are referring to your strawman inequality, not the inequality I derived for which the terms are exactly the same as Bell's. It's not worth another response. If you are serious about pursuing this, deal with Bell's exact inequality from his original paper, not some toy version which obfuscates the issue.

If it wasn't for the context I would assume I did understand what this sentence meant--that at a theoretical level we assume the existence of triples, even if we don't assume they're known to the theoretical experimenter
This is just another reason why I say you are confused. You say with the left side of your mouth that you have triples theoretically, then say on your right side that the theoretical experimenter does not have triples. And you attribute such conspiracy to Bell.

Bell did not consider two different theoretical situations. He had one theoretical situation in which properties existed simultaneously for 3 angles. His inequality is derived from this ONLY. There is no mention in his paper about a theoretical experimenter not knowing the third value.

The issue with experimenters not being able to measure simultaneously the third property is a practical issue with data gathering in real actual experiments. So your reference to Bell's later papers where he acknowledges this issue does not change the fact that it does not arise in the derivation of Bell's inequalities.

Without triples, you can not calculate anything comparable to Bell's inequality. For Bell's derivation, this problem is non-existent because he is not considering an actual experiment but a theoretical situation and he in fact simply assumed that a third property existed simultaneously at a third angle and proceeded to derive his inequality. So if you expect me to believe that Bell assumed a theoretical experimenter did not know the third value, and somehow this assumption is very important for the inequality he derived, even though he did not mention it, you are out of luck. In fact, if you must suggest that Bell was dealing with measurements by a theoretical experimenter, then you must also admit that only one of pairs, (a,b) mentioned by Bell is measured and the other two {(a,c), and (b,c)} are deduced from it by theoretical reasoning that there is a third property at angle c! Bell was absolutely not deriving an inequality for a situation in which each pair is measured separately in a different run of the experiment. So if you actually understand Bell's work as you claim to, then this line of argumentation has no other purpose than obfuscation.

So if you don't like my talk about fractions (even though it's completely relevant to other Bell inequalities), you can instead consider the distinction between terms of this type:
(average value of a*b for all triples)
vs. terms of this type:
(average value of a*b for all triples where experimenter sampled a and b)

I have already explained to you why this distinction is artificial for the inequality I derived, and the one Bell derived. The situation may be different for your toy version in which the (a,b,c) do not mean exactly the same thing in each term. But I'm not interested in your toy version. I am only interested in Bell's inequality and the one I derived in which the terms (a,b,c) mean exactly the same thing between terms. In Bell's inequality the the "a" in the first two terms are exactly the same. Same thing for the "b" in the first and last term and same for the "c" in the last two terms. Anything else is not Bell's inequality. The only type of inequality for which your stated difference above exists, is one in which the symbols are different between terms and Bell's inequality is not one of such. Neither is the one I derived. In fact, earlier, you seem to understand this when you said:

Fast forward to then to the resulting CHSH inequality
|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

In your opinion then, is the P(λi) the same for each of the above terms, or do you believe it doesn't matter.

The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).

Are you trying to recant that admission, or is this new line of argumentation just for argument sake?

If you think the terms in my inequality are different from Bell's explain it using my inequality and Bell's rather than picking two strawmen inequalities of your own in which the terms differ. Why do you shy away from using the directly relevant inequalities?! I refuse to discuss a contrived strawman when you could have simply used the directly relevant inequality.

In your inequality, does P(b,c) refer to "average value of b*c for all triples where experimenter sampled b and c"? If it does, then it's not hard to find a set of triples that violates your inequality. And if it doesn't, then no, the terms in your inequality don't mean the same thing as those in Bell's.

1 + <bc> = |<ab> - <ac>|

This is only guaranteed for a situation in which a dataset of triples can be obtained. If you start off with triples like Bell, there is no problem. But if you start off with datasets of pairs, the above can only be guaranteed if the pairs can be resorted to obtain a dataset of triples. It doesn't mean you need to resort it in order to calculate the terms. It just means being able to resort the data is evidence that the symbols are equivalent. It is just another way of saying the symbols ("a", "b" and "c") mean exactly the same thing from term to term.

Once you have this triple, there is no distinction between "average value of b*c for all triples" and "average value of b*c for all triples where experimenter sampled b and c", It doesn't matter matter how you obtained the triples, whether you started directly with triples, or you resorted the separate pairs. Your distinction between the two is so ridiculous I wonder why you keep insisting on it. If an experimenter measured a certain number of b and c, say M iterations:
- average value of b*c for all triples is:
\frac{1}{M}\sum_{i}^{M} a_{i}b_{i}

- average value of b*c for triples for which the experimenter measure b*c is:
\frac{1}{M}\sum_{i}^{M} a_{i}b_{i}

Or do you expect "all" in the first case to mean the experimenter can calculate an average over values he did not measure? Note also that you are trying to force a distinction where there is none, in an attempt to imply that my inequality is different from Bell's inequality. So if you think "all" in the first case means more cases than were measured, state clearly which case corresponds to Bell's and which one to mine. Is it your claim that Bell's inequality involves averaging over unmeasured terms (an impossibility), or is it your claim that my inequality involves averaging over unmeasured terms? And when you answer that, also answer whether you think actual experimenters ever average over unmeasured terms.

Sure there's a difference. Suppose our dataset consisted only of the five you mention, and that for each iteration the pair measured was as follows:

a b c
1: + + - (measured a,b)
2: + - + (measured b,c)
3: + - - (measured a,c)
4: - + - (measured a,b)
5: - - + (measured b,c)

What you present above are dataset of pairs from the measurements. We are interested in what was measured. If it wasn't measured, the experimenter does not have it and can not calculate from it. So let us examine this. For clarity and following from the example you were responding to here are the three datasets of pairs

a b
1:+ +
4:- +

b c
2:- +
5:- +

a c
3:+ -

As you can see already, it is not possible to apply this data to Bell's inequality because we can not sort it in order to obtain a dataset of triples. We can not sort by "b" because the two lists of b's are completely different, same for "a" and "c".
The first term involving ab, is calculated with only positive b terms, the second term with only negative b terms, so each symbol (a,b,c) means something different from term to term. This type of data is not guaranteed to obey Bell's inequality nor the one I derived. What your example shows clearly is the fact that it is possible to violate Bell's inequality using a dataset of pairs (my claim 3) UNLESS it is also possible to sort the dataset of pairs to generate a dataset of triples (my claim 1).

Is it your claim that Bell's inequality is supposed to apply to this kind of data as well? If that is what you believe please say so clearly.

JesseM

Aug5-10, 02:38 AM

Here again you are referring to your strawman inequality, not the inequality I derived for which the terms are exactly the same as Bell's. It's not worth another response. If you are serious about pursuing this, deal with Bell's exact inequality from his original paper, not some toy version which obfuscates the issue.
The inequality is neither a strawman nor a "toy version", as I already pointed out:
You didn't make clear at the outset that "the form being discussed" was the one in his original paper, in this recent discussion of ours I was the first one to bring up a specific mathematical inequality, first in post #1171 where I quoted a paper from Bell and then again in post #1176 where I talked about

Number(A, not B) + Number(B, not C) greater than or equal to Number(A, not C)

Then in post #1179 I again referred to that inequality, showing that the purely arithmetic version of the inequality can't be violated by a series of triples, but a Bell-type inequality with the same equation can be. It wasn't until post #1182 that you brought up the inequality |ab+ac|-bc <= 1. It's not really fair that you should have total control over the terms of the discussion in this way, but as seen above I'm fine with discussing this inequality too. Still it's a bit much that you now accuse me of an attempt at obfuscation because I brought up a specific example in what had previously been an overly abstract discussion, and then I didn't immediately drop that example when you brought up a slightly different one.

Also, the inequality I mention is hardly "obscure", if you didn't have a single-minded interest in Bell's original paper only and instead looked at discussions of Bell's inequality by other authors, you'd see that this inequality is mentioned more often in introductory discussions of Bell's proof than the one in the original paper, perhaps because it's so much simpler to see how it's derived (I gave a quick derivation in post #1179 when I said 'the proof is trivial--every triplet with A+ and C- must either be of type A+B+C- or type A+B-C-, and if the former it will also contribute to the number with B+ and C-, if the latter it will also contribute to the number with A+ and B-'). I already gave a link to one website (http://www.upscale.utoronto.ca/PVB/Harrison/BellsTheorem/BellsTheorem.html) which uses it as a starting point, and wikipedia refers to this inequality as Sakurai's Bell inequality (http://en.wikipedia.org/wiki/Sakurai's_Bell_inequality) because it appeared in Sakurai's widely-used 1994 textbook on QM (the wikipedia article mentions a number of other well-known papers and books on Bell's proof that have used it).
This is just another reason why I say you are confused. You say with the left side of your mouth that you have triples theoretically, then say on your right side that the theoretical experimenter does not have triples. And you attribute such conspiracy to Bell.

Bell did not consider two different theoretical situations. He had one theoretical situation in which properties existed simultaneously for 3 angles. His inequality is derived from this ONLY. There is no mention in his paper about a theoretical experimenter not knowing the third value.
As I said before, his original paper (http://www.drchinese.com/David/Bell_Compact.pdf) was written for an audience of scientists, the argument was fairly condensed and certain things were left implicit because he assumed the audience would understand. Reading the paper carefully, any physicist would understand that when he writes terms like P(a,b), he is referring to the expectation value for a pair of measurements on an entangled pair with detectors setting a and b (and each result being +1 or -1), which is equivalent to the average measurement result over a very large (approaching infinity) series of measurements with detector settings a and b.

Note that he does refer explicitly to a pair of measurements on the first page:
Measurements can be made, say by Stern-Gerlach magnets, on selected components of the spins \sigma_1 and \sigma_2. If measurement of the component \sigma_1 \cdot a, where a is some unit vector, yields the value +1 then, according to quantum mechanics, measurement of \sigma_2 \cdot a must yield the value -1 and vice versa
Do you doubt that here he is talking about a single pair of measurements on a single pair of particles, rather than averages or "resorted" pairs of measurements taken from two distinct pairs of entangled particles, since that's the only case where the results are guaranteed to be +1 and -1? If you don't disagree with this, note where he goes on to say that this implies that "the result of any such measurement must actually be predetermined", the implication here is that if we are choosing between three measurement angles 1, 2, 3, then any given pair of entangled particles must have a triplet of "predetermined" measurement results for each angle. He goes on to say that the parameters predetermining these measurement results can be encapsulated in the variable λ, and that:
The result A of measuring \sigma_1 \cdot a is then determined by a and λ, and the result B of [b]measuring \sigma_2 \cdot b in the same instance is determined by b and λ, and

A(a,λ) = ±1, B(b,λ) = ±1
So here he clearly is talking about a pair of measurement results (by a hypothetical experimenter or team of experimenters), given the assumption that the two results are determined by the two detector angles a and b and the value of λ which represents all the hidden variables with that single pair of entangled particles (where each specific value of λ gives a triplet of 'predetermined' results if the experimenters have three possible detector angles they're choosing from). Then he goes on to say:
If \rho(\lambda) is the probability distribution of λ then the expectation value of the product of the components \sigma_1 \cdot a and \sigma_2 \cdot b is

P(a,b) = \int d\lambda \rho(\lambda) A(a,\lambda)B(b,\lambda) (2)
So remembering that A(a,λ) and B(b,λ) each represented a "result" of "measuring" a member of an entangled pair, with detector angles a and b respectively, you can tell from this integral that he's calculating an "expectation value" (his words) for the product of a pair of measurements (by a hypothetical experimenter or team of experimenters). In general, if you have some finite number N of possible results Ri for a given measurement, and you know the probability P(Ri) for each result, the "expectation value" is just:

E = \sum_{i=1}^N R_i * P(R_i )

If you perform a large number of measurements of this type, the average result over all measurements should approach this expectation value.

If we imagine that λ can only take a finite set of values, so we can write a discrete version of Bell's integral (2) above, it's more clear why it has the form of an expectation value:

\sum_{i=1}^N [A(a,\lambda_i)*B(b,\lambda_i)] * P(\lambda_i)

...so if you perform a large number of measurements with detector angles a and b, and for each trial/iteration you calculate the product of your pair of measurement results (assumed to be determined by the value of λ which is assumed to give a triplet of predetermined results for the three possible detector angles you're choosing from), then if you take the average of the product of the two measurement results over all these trials/iterations with detector angles a and b, it should approach the "expectation value". This is why the inequality 1 + P(b,c) >= |P(a,b) -P(a,c)| can be understood as a prediction that theoretical experimenters in a theoretical universe with local realist laws should see, in the limit as the number of trials/iterations with each pair of detector angles becomes very large, that

1 + (average value of product of measurement results for all particle pairs where experimenters used detector angles b and c)
>= |(average value of product of measurement results for all particle pairs where experimenters used detector angles a and b) - (average value of product of measurement results for all particle pairs where experimenters used detector angles a and c)|

Bell does make the theoretical assumption that in a local realist universe, the fact that they always get opposite results when they choose the same detector angle implies that each particle pair was associated with a λ that gave it a triple of predetermined results for all three angles a,b,c. But this is just an assumption made in the derivation of the inequality, the inequality itself deals only with expectation values for pairs of measurement results seen by the theoretical experimenters on each trial/iteration of the experiment.

If you think my interpretation of his words and equations is incorrect (and I guess you probably will since you always find some reason to disagree with whatever I say, but as I said to DevilsAvocado I'm mainly writing for the purpose of showing other readers why your claims don't make sense), then please point out precisely where, and give your own interpretation of whatever quote/equation you think I have misinterpreted.
The issue with experimenters not being able to measure simultaneously the third property is a practical issue with data gathering in real actual experiments. So your reference to Bell's later papers where he acknowledges this issue does not change the fact that it does not arise in the derivation of Bell's inequalities.
Well, see above. The assumption of triples is used in the derivation, but the final inequality he derives concerns only expectations about pairs of measurement results, which is why it can be checked against actual real-world measurement results even though we can never measure more than two angles for a given entangled pair.
Without triples, you can not calculate anything comparable to Bell's inequality. For Bell's derivation, this problem is non-existent because he is not considering an actual experiment but a theoretical situation
The theoretical situation concerns expectation values in a theoretical series of measurements. If this wasn't the case there would be no way to make a theoretical comparison with the expectation values in QM, since QM only gives expectation values for measurement results, not for any hidden variables.
In fact, if you must suggest that Bell was dealing with measurements by a theoretical experimenter, then you must also admit that only one of pairs, (a,b) mentioned by Bell is measured and the other two {(a,c), and (b,c)} are deduced from it by theoretical reasoning that there is a third property at angle c!
No. In equation (13) he deduces from the fact that the experimenters always get opposite results when they choose the same angle that A(a,λ)=-B(a,λ) (and since a can stand for any angle, it naturally follows from this that A(b,λ)=-B(b,λ) and A(c,λ)=-B(c,λ)). This means that equation (2) which I quoted earlier could be rewritten as:

P(a,b) = -\int d\lambda \rho(\lambda) A(a,\lambda)A(b,\lambda)

And by the same token, you can see from the equation for P(a,b) - P(a,c) at the top of p. 406 that he is assuming P(a,c) is derived theoretically in exactly the same way:

P(a,c) = -\int d\lambda \rho(\lambda) A(a,\lambda)A(c,\lambda)

So just like P(a,b), P(a,c) is an "expectation value" for the product of two measurements with the detectors set to angles a and c, and as I already pointed out, any "expectation value" can be understood as the average for a very large number of measurements of the desired quantity (i.e. 'the product of two measurements with detectors set to angles a and c).

Then a few lines down he writes an equation whose right side is \int d\lambda \rho(\lambda) [1 - A(b,\lambda)A(c,\lambda)] and then says "The second term on the right is P(b,c)", which indicates he is also assuming that

P(b,c) = -\int d\lambda \rho(\lambda) A(b,\lambda)A(c,\lambda)

So, what I just said about P(a,c) also applies to P(b,c).
Bell was absolutely not deriving an inequality for a situation in which each pair is measured separately in a different run of the experiment.
Oh, but he absolutely was, and if you ask any other non-crackpot who is knowledgeable about Bell's theorem (DrChinese, say) I'm sure they'll tell you the same thing. I'm pretty sure I could also find you other papers on Bell's theorem, by other physicists or perhaps Bell himself, which would make more clear that this is widely understood as the physical meaning of expectation values that appear in Bell inequalities--would you like me to try, or are you going to stick with the fundamentalist strategy of only looking at one holy text in isolation, ignoring any wider context (like the understanding of other physicists through the years) that might make more clear the meaning of any ambiguous parts?
The situation may be different for your toy version in which the (a,b,c) do not mean exactly the same thing in each term. But I'm not interested in your toy version. I am only interested in Bell's inequality and the one I derived in which the terms (a,b,c) mean exactly the same thing between terms. In Bell's inequality the the "a" in the first two terms are exactly the same.
"a" is just a detector angle rather than a result like +1 or -1, the text makes that clear, so of course it means the same thing everywhere. But P(a,b) is an expectation value (he called it that himself), which can be understood as the average value of the product of two measurements on a pair of entangled particles with detectors at angles a and b, in the limit as the number of particle pairs measured in this way goes to infinity.
The only type of inequality for which your stated difference above exists, is one in which the symbols are different between terms and Bell's inequality is not one of such.
The symbols a,b,c refer to angles and so don't have different meanings between terms, but each of P(a,b) and P(b,c) and P(a,c) is an expectation value, and to connect that to real or theoretical measurements you have to imagine P(a,b) is the average of the product of results in a run with detectors at angles a and b, P(b,c) is the average for a run with detectors at angles b and c, etc. If you argue this point you're not just arguing with me, you're arguing against the interpretation physicists have had for years about what the inequality is predicting about measurement results, an interpretation which Bell could have corrected if he disagreed with it (and if we looked through enough of his writings I bet we could find explicit confirmation this was his interpretation of the meaning of the terms as well)
Neither is the one I derived. In fact, earlier, you seem to understand this when you said:
Fast forward to then to the resulting CHSH inequality
|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

In your opinion then, is the P(λi) the same for each of the above terms, or do you believe it doesn't matter.
The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).
Are you trying to recant that admission, or is this new line of argumentation just for argument sake?
Why do you think that contradicts anything I have been saying recently? If P(λi) is the same for each of the above terms, that just means the frequencies of getting different values of λi on a near-infinite run of trials with detector settings a and b should be the same as the frequencies of different values of λi on a near-infinite run of trials with detector settings a and b', and so forth. For example, if on the first run with detectors set to a and b it was true (though not known to the experimenters) that 2.3% of trials/iterations had hidden variables described by λ1 and 3.8% of trials/iterations had hidden variables described by λ2, then we are making the theoretical assumption that on the second run with detectors set to a and b' it was also true that 2.3% of trials/iterations had hidden variables described by λ1 and 3.8% of trials/iterations had hidden variables described by λ2. So in no way does this contradict the idea that each expectation value concerns a different run of trials.
If you think the terms in my inequality are different from Bell's explain it using my inequality and Bell's rather than picking two strawmen inequalities of your own in which the terms differ.
I have done that several times, whenever I point out that the terms in your inequality have a meaning of this type (with the understanding that here I use notation like b*c to refer not to the product of two detector angles, but the product of the predetermined results +1 or -1 for b and c in a given triple):

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

while the terms in Bell's inequality have a meaning of this type

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

JesseM

Aug5-10, 02:39 AM

(continued)

1 + <bc> = |<ab> - <ac>|

This is only guaranteed for a situation in which a dataset of triples can be obtained. If you start off with triples like Bell, there is no problem. But if you start off with datasets of pairs, the above can only be guaranteed if the pairs can be resorted to obtain a dataset of triples.
No, there is another way besides your bizarre notions about "resorting". An inequality of this type:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

Is obviously not guaranteed to hold for an arbitrary list of triples with a choice of which pair were measured for each triple, but it will hold if you make two additional assumptions

1. The subset of triples (the 'run') where experimenter sampled b and c is very large (approaching infinity), and likewise for the subset where experimenter sampled a and b, and the subset where experimenter sampled a and c

2. the process that generates the list of triples for each subset has the same probability of generating a given triple (like a=+1, b=-1, c=+1) for each new entry on the list, regardless of which two measurements are made in that subset

With these two additional assumptions you do have a basis for deriving an inequality of the form I wrote, despite the fact that each term deals with averages for a different subset of triples, rather than each term being based on the same set of triples.
It doesn't mean you need to resort it in order to calculate the terms. It just means being able to resort the data is evidence that the symbols are equivalent. It is just another way of saying the symbols ("a", "b" and "c") mean exactly the same thing from term to term.
I still don't know what you mean by "mean exactly the same thing from term to term". a, b and c are just placeholders, for each triple each one can take value +1 or -1, for example in the first triple on your list you might have a=+1 while on the second triple you might have a=-1. Do you just mean that each term deals with averages from exactly the same list of triples, rather than each term dealing with averages from a separate list of triples?
Once you have this triple, there is no distinction between "average value of b*c for all triples" and "average value of b*c for all triples where experimenter sampled b and c"
I don't get how you can say "no distinction" when I gave you a clear example of what I meant by this:
a b c
1: + + - (measured a,b)
2: + - + (measured b,c)
3: + - - (measured a,c)
4: - + - (measured a,b)
5: - - + (measured b,c)

In this case, "average value of a*b for all triples" = [(value of a*b for #1) + (value of a*b for #2) + (value of a*b for #3) + (value of a*b for #4) + (value of a*b for #5)]/5 =
[(+1) + (-1) + (-1) + (-1) + (+1)]/5 = -1/5

On the other hand, "average value of a*b for all triples for which the experimenter measured a and b" would only include triple #1 and triple #4, so it'd be [(value of a*b for #1) + (value of a*b for #4)]/2 = [(+1) + (-1)]/2 = 0.
Your response consisted of somehow saying that if the theoretical experimenter only sampled pairs, then this was really a "list of pairs" despite the fact that they were drawn from triples which we (playing the role of an omniscient being looking down on the lowly human experimenter) do know. But in that case I have no idea what you could possibly mean by the phrase "average value of b*c for all triples where experimenter sampled b and c", if you don't mean something like what I did above (you must have something definite in mind or you hopefully wouldn't have said there was 'no difference' between this and 'average value of b*c for all triples') So can you explain how you interpret the phrase "average value of b*c for all triples where experimenter sampled b and c", preferably with a simple example like mine above?

Anyway, I think you now understand what I mean when I say "(average value of b*c for all triples where experimenter sampled b and c)", so even if you don't like my phrasing I'll ask you not to willfully misread me by substituting in the meaning you think that phrase "should" have. Hopefully you now agree that an inequality like this:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

...cannot be derived from arithmetic alone, although with some additional theoretical assumptions like the one that says a given triple is equally likely to occur regardless of what the experimenter sampled, you can derive it (and that's exactly what derivations of Bell inequalities do).
It doesn't matter matter how you obtained the triples, whether you started directly with triples, or you resorted the separate pairs.
No one but you would interpret the terms of Bell's inequality in terms of "resorting" experimental data on pairs (whether theoretical experiments or actual experiments) to create triples, that's just a weird misconception you probably got from Da Raedt's paper. Trust me, no mainstream physicist who has ever done their own derivation of Bell's theorem was ever thinking in terms of that kind of resorting (i.e. multiplying +1's and -1's from different trials/iterations). If they thought about how the terms would relate to experimental data at all (as opposed to just thinking of them as abstract 'expectation values' which can be compared to quantum-mechanical expectation values), they were thinking of something along the lines of my "(average value of b*c for all triples where experimenter sampled b and c)".
Your distinction between the two is so ridiculous I wonder why you keep insisting on it. If an experimenter measured a certain number of b and c, say M iterations:
- average value of b*c for all triples is:
\frac{1}{M}\sum_{i}^{M} a_{i}b_{i}

- average value of b*c for triples for which the experimenter measure b*c is:
\frac{1}{M}\sum_{i}^{M} a_{i}b_{i}

Or do you expect "all" in the first case to mean the experimenter can calculate an average over values he did not measure?
No, because when I say "(average value of b*c for all triples) I'm not talking about what the experimenter calculates at all, I'm just dealing with a model where we take the role of an omniscient being who knows the value of all triples even though the hypothetical experimenter does not. If you object to this, just remember that Bell's whole proof is based on figuring out some constraints on what would be calculated if we could know impossible-to-know-in-practice facts like the \rho(\lambda) (under the assumption that there is some objective truth about such things, whether experimenters know it or not).
Note also that you are trying to force a distinction where there is none, in an attempt to imply that my inequality is different from Bell's inequality. So if you think "all" in the first case means more cases than were measured
It just means "all" the triples. It doesn't matter whether the triples are assumed to represent the real truth about predetermined results for all three angles on a single trial/iteration involving a single pair of particles, or whether the triples are weird Frankenstein monsters created be stitching together measurements from two or more different pairs of particles (your idiosyncratic 'resorting' idea, which again is not what any mainstream physicists are thinking of when they write down Bell inequalities).
Is it your claim that Bell's inequality involves averaging over unmeasured terms (an impossibility), or is it your claim that my inequality involves averaging over unmeasured terms? And when you answer that, also answer whether you think actual experimenters ever average over unmeasured terms.
"no" to all of the above. Again, your inequality is of this form:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

...but I understand that you aren't talking about triples representing all three predetermined values on a single trial/iteration (since all three can't be measured), but rather about Frankentriples created by "resorting". Meanwhile, the terms in Bell's inequality are expectation values, so for a large number of trials/iterations they can be understood as:

1 + (average value of b*c for all triples where experimenter sampled b and c)
>= |(average value of a*b for all triples where experimenter sampled a and b) - (average value of a*c for all triples where experimenter sampled a and c)|

Here the "triples" are not known by the experimenters, only the value for b and c is known on trials/iterations where b and c were sampled, etc. So, you could rewrite Bell's inequality as:

1 + (average value of b*c for trials/iterations where experimenter sampled b and c)
>= |(average value of a*b for trials/iterations where experimenter sampled a and b) - (average value of a*c for trials/iterations where experimenter sampled a and c)|

However, the assumption that there are triples associated with each particle even if we don't know them (and that the probability of a given triple occurring each time does not depend on which pair are sampled) is important to deriving the inequality, though
What you present above are dataset of pairs from the measurements. We are interested in what was measured. If it wasn't measured, the experimenter does not have it and can not calculate from it.
No, but we can derive statistical constraints on what the experimenters will see based on the assumption that their results are coming from a set of preexisting triples, even if we don't know the value of all three--that's what derivations of Bell inequalities are all about.
So let us examine this. For clarity and following from the example you were responding to here are the three datasets of pairs

a b
1:+ +
4:- +

b c
2:- +
5:- +

a c
3:+ -

As you can see already, it is not possible to apply this data to Bell's inequality because we can not sort it in order to obtain a dataset of triples.
Although the assumption of triples is involved in deriving Bell's inequality, to check whether data satisfies the inequality or not we don't need a "dataset of triples", this is just your weird misconception. P(a,b) is the expectation value for the product of two measurement results with detectors set to a and b, so we'd take a dataset of pairs which each represent two measurements on a pair of entangled particles with detectors set to a and b, and calculate the average of each pair. Likewise for P(b,c) and P(a,c). That's what everyone understands a test of Bell's inequality against real data to involve, no one thinks in terms of constructing artificial Frankentriples. Think about it: if they did first use the data to construct a single list of triples and then calculate 1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|, it would be mathematically impossible for such an inequality to be violated by a single list of triples, and yet experimenters report violations of Bell inequalities all the time!
This type of data is not guaranteed to obey Bell's inequality nor the one I derived.
Yes it is, you just have to add some additional assumptions beyond just the idea that each data pair was obtained from a triple of preexisting values. I mentioned the assumptions at the top of this post. And to get back to the start, this is why your (1) is wrong--Bell's inequality is not the type of purely arithmetic inequality you're thinking of, it's an inequality dealing with pairs, and additional assumptions beyond basic arithmetic are used to derive it.

DevilsAvocado

Aug5-10, 08:45 AM

which can be seen in the very counterintuitive Dirac three polarizers experiment where you have two polarizers at right angles that don't allow any light to get through so they look black, but then if you put another polarizer in between them, you see light coming through all three in the area covered by the middle one

Yes, this is cool and we can run this Polarizers Applet (http://www.lon-capa.org/~mmp/kap24/polarizers/Polarizer.htm) to verify. First set the 3 polarizers to:

Ang1 = 90
Ang2 = 90
Ang3 = 0

0.0% light will get thru. Now change to:

Ang1 = 90
Ang2 = 45
Ang3 = 0

12.50% light will get thru!

In classical electromagnetism, I think "polarized" light would just be a beam where if you pick the correct angle for your polarizer 100% of the light will pass through, whereas "unpolarized" would mean no matter what angle you set your polarizer, the intensity would be reduced when the beam passes through it. With individual photons, they have a quantum state which determines the probability they'll make it through a polarizer at any given angle

Of course you’re right. It was a mistake by me to bring in the wave–particle duality (http://en.wikipedia.org/wiki/Wave-particle_duality)... we have enough "perplexity" in this thread already:smile:, sorry.

Spin of light beams is one thing. Spin of photons another...

http://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Poincar%C3%A9_sphere.svg/250px-Poincar%C3%A9_sphere.svg.png

I probably get back on this, but...

thinking about it some more, I may have been mistaken to say that they'd always have a 50% chance of passing through a polarizer if their polarization hadn't been previously measured, it might be that even though no polarization measurement had ever been made, knowledge of the properties of the source would give you an initial quantum state that would have different probabilities at different angles, I'm not sure exactly how the initial quantum state of an entangled pair would be defined for a given type of source.

I did think this thru once more, and afaict they must always have a 50% chance, no matter what... otherwise there’s an obvious risk of FTL messaging.

Let’s say that we set Alice at 22.5º and Bob at 0º, but we decide not to measure Bob’s photons. If we run 6 pairs of entangled photons, we could get something like this for Alice:

Angle Corr. Measure
--------------------------------
Alice 22.5º ? 101010

Now, if we had the possibility to do time travel, and could rewind the experiment, we would see that Bob’s measurement must have looked something like this:

Angle Corr. Measure
--------------------------------
Alice 22.5º 85% 101010
Bob 0º 85% 101011

(cos^2(22.5) = 85% ≈ 5/6)

Now, let’s say we do not always have the 50% random probability, we could get "tidy" results like this, and thereby determine if Bob are measuring his photons, or not, thus it would provide a mechanism for FTL messaging...

Angle Corr. Measure
--------------------------------
Alice 22.5º 85% 111111
Bob 0º 85% 111110

All this is of course extremely simplified, and will only be valid on a large sampling of photons.

Agree? Or do you see any weakness in my reasoning...?

billschnieder

Aug6-10, 12:01 AM

P(a,b), he is referring to the expectation value for a pair of measurements on an entangled pair with detectors setting a and b (and each result being +1 or -1), which is equivalent to the average measurement result over a very large (approaching infinity) series of measurements with detector
Note the underlined texts as we will come back to it. Now let us consider our previous discussion about this in post #857.

Is the equation as it stands indicating that the numerical value represents what is obtained by measuring a specific pair of settings (ai, bi) a large number of times, or is it indicating that expectation value is what will be obtained my measuring a large number of different pairs of angles (ai,bi)?

The first, I think he's calculating the expectation value for some specific pair of settings. If he wanted to talk about the expectation value for a variety of different ai's I think he'd need to have a sum over different values of i in there.

So then, let us consider a specific pair of settings (a, b), and presume that we have calculated an expectation value from equation (2) of Bell's paper, say E(a,b). From what you have explained above, there is going to be a specific probability distribution P(λi) over which E(a,b) was obtained, since the corresponding P(AB|ab) which you obtained your E(a,b) from, was obtained by marginalizing over a specific P(λi) . Do you agree?

Fast forward to then to the resulting CHSH inequality
|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2
In your opinion then, is the P(λi) the same for each of the above terms, or do you believe it doesn't matter.

The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).

So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?

If you remember, our previous discussion fell apart at the point where you refused to give a straight answer to the last question above.

You say, Bell is refering to the measurement of AN entangled pair with detectors set at a and b. I agree. You also say, in order to obtain the expectation value for this pair of angles, Bell integrates over all λi, so that there is a λi probability distribution. I agree also. This is precisely why I asked you all those questions earlier and you also agreed with me that this λi probability distribution must be exactly the same for all expectation value terms in Bell's inequality.

Now please pay attention and make sure you actually understand what I am saying next before you respond.
The reason why the probability distribution of λi must be the same is the following (using the equations you presented, except using E for expectation to avoid confusion with Probability notation).
E(a,b) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(b,\lambda )
E(a,c) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(c,\lambda )
E(b,c) = -\int d\lambda\rho (\lambda )A(b,\lambda )A(c,\lambda )

Note a few things about the above. There are two factorable terms inside the integral, one for each angle. You can visualize this integral in the following descrete way. We have a fixed number of λi, say (λ1, λ2, λ3, ... λn). To calculate the integral, we multiply A(a,λ1)A(b,λ1)*P(λ1) and add it to A(a,λ2)A(b,λ2)*P(λ2) ... all the way to λn. In other words, the above will not work if we did A(a,λ1)A(b,λ5)*P(λ3) or any such.

Secondly, once we have our inequality:

|E(a,b) - E(a,c)| - E(b,c) <= 1

To say the probability distribution of λi must be the same means that, if we obtained E(a,b) by integrating over a series of λi values, say (λ1, λ2, λ4), the same must apply to E(a,c) and E(b,c). In other words, it is a mathematical error to use E(a,b) calculated over (λ1, λ2, λ4), with E(a,c) calculated over (λ6, λ3, λ2) and E(b,c) calculated over (λ5, λ9, λ8) in the above inequality, because in that case ρ(λi) will not be the same across the terms the way Bell intended and we agree that he did. Note also that even if the set of λ's is the same, we still need each λ to be sampled the exact same number of times for each term.

Now what I have just describe here are the specific experimental conditions that should apply for Bell's inequality to be applicable to data obtained from any experiment.

This brings us to the sorting I mentioned earlier which you are having difficulty with.
Suppose in any actual experiment, the experimenter also had along side each pair of measurements in each run, the specific value of λ for that run. He will now have a long list of pairs of +'s and/ -'s plus one indexed λ each. Such that for the three runs of the experiment he will have three lists which look something similar to the following, except the actuall sequence of +'s and/ -'s and λ's will be different

+ - λ1
- + λ9
+ + λ6
- + λ3
...

In such a case, it will be easy to verify if his data meets the requirement that ρ(λi) is the same for each term, as you agreed to previously. He could simply sort each of the three lists according to the λ column and compare if the λ column from all three runs are the same. If they are not, ρ(λi) is different and Bell's inequality can not be applied to the data for purely mathematical reasons. In other words, if they insisted to calculate the LHS of the inequality with that data, the inequality is not guaranteed to be obeyed, for purely mathematical reasons.

(Note I am using the term "run" here to describe the three lists of already separated out data. ie, run one constitutes all the data used for calculating the E(a,b) term, run 2 the E(a,c) etc even though the experimenters may have been doing random switching from angle to angle.)

However, experimenters do not have the λ's so how can they make sure their data is compatible? If it is assumed that each specific λ contains all properties that will deterministically result in the outcome, then we do not need the λs to sort our data. We can just sort the actual result pairs so that the "a" colum of the (a,b) pair matches the "a" column of the (a,c) pair and the "b" and "c" columns also match. If we can do that, then we can be sure that ρ(λi) is the same for all three terms of the inequality and Bell's inequality should apply to our data. If we can not, it means ρ(λi) is different, and the data is mathematically not compatible with the inequality.

Let us look at this slightly differently. Consider our first list which included the λ's. After sorting all three runs by the λ's we will find that we only need three columns of +'s and/ -'s out of the 6 (2 from each run). This is because each column will be duplicated. This simply means for each λ, there are 3 simultaneously existing properties at the angles.

Now, what if instead of collecting three runs of pairs we collected a single run of triples so that the data from our experiment is
a b c
+ - + λ1
- + + λ9
+ + - λ6
- + + λ3
...

We do not need any sorting here because we can calculate all our terms from the same single run with the same ρ(λi). So we can compare ANY dataset of this type with Bell's inequality. Note, this is not the same as saying we can do the same thing even if we only measured pairs so long as triples are assumed to exist. Of course triples are assumed to exist. That is what gave us the inequalities. We are only interested now in the question of whether our dataset obtained in an experiment can fulfil the requirement of uniform ρ(λi). However, since it is not possible to measure triples in any experiment, the requirement to be able to sort the dataset applies to all datasets involving multiple runs of pairs.

Now, let us go back to the underlined text above. Since you agreed with me that ρ(λi) must be the same for each term in the inequality, how do you make sure of that in an experiment? Is that what you were alluding to with the underlined text: "which is equivalent to the average measurement result over a very large (approaching infinity) series of measurements"? In other words, why is it important that the number of measurements be very large? Please I need a specific answer to this question, assuming you are still willing to contest this issue after my very detailed explanation above.

As an aside:
You seem to have an issue with my use of

| <ab> + <ac> | - <bc> <= 1

In which I have replaced E(a,b) in Bell's notation with <ab> in mine. Where a,b represent the outcomes at angles a and b and I was referring to the fact that in calculating the averages, it is not allowed for the list of a's in the first term to contain a different number of +'s and/ -'s from that in the second term and same for "c" and "b".
You objected and said:

"a" is just a detector angle rather than a result like +1 or -1, the text makes that clear, so of course it means the same thing everywhere. But P(a,b) is an expectation value (he called it that himself), which can be understood as the average value of the product of two measurements on a pair of entangled particles with detectors at angles a and b, in the limit as the number of particle pairs measured in this way goes to infinity.

But then later, you used exactly the same notation.

I have done that several times, whenever I point out that the terms in your inequality have a meaning of this type (with the understanding that here I use notation like b*c to refer not to the product of two detector angles, but the product of the predetermined results +1 or -1 for b and c in a given triple)

This tactic of yours combined with lack of willingness to actually understand the opposing view, combined with a severe case of irrelevant argumentum ad verbosium, is the reason I do not take you seriously.

DevilsAvocado

Aug6-10, 05:44 AM

JesseM, I’m sorry to say that if it continues this way, I probably have to charge you some kind of "Oracle fee (http://www.physicsforums.com/showpost.php?p=2825463&postcount=1192)"... :biggrin:

"a severe case of irrelevant argumentum ad verbosium"
This very fine and sophisticated grievance can only be deduced to a severe case of argumentum ad hominem abusive.

LOL! Pathetic BS is still nothing more than pathetic BS! :rofl: :rofl:

So, what’s up next? Well, Mr. BS already smells the defeat, and his only "hope" is semantic games and personal attacks in disguise of silly words, and after yet another 2-3 posts, the attacks will boost significantly.

And then comes the grand finale in an: "Agreement not to agree."

Jesse, we take you seriously, and Mr. BS is nothing more than a pathetic joke.

argumentum ad nauseam

billschnieder

Aug6-10, 08:28 AM

One more thing.

This is easier to see if you suppose λ can only take a discrete set of values from 0 to N, so the integral on the right side of (2) can be replaced by the sum \sum_{i=0}^N A(a,\lambda_i)*B(b,\lambda_i)*P\\lambda_i) .

You must agree therefore that the following is Bell's inequality.

|\sum_{i} A(a, \lambda_{i} )A(b,\lambda_{i} ) P(\lambda_{i} ) + \sum_{i} A(a, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} )| - \sum_{i} A(b, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} ) \leq 1

Which can be factored in this form.

|\sum_{i} P(\lambda_{i} )A(a, \lambda_{i} )\left [ A(b,\lambda_{i} ) + A(c,\lambda_{i} )\right ]| - \sum_{i} A(b, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} ) \leq 1

Bell himself did a similar factorization. Therefore if for any dataset the two equations above produce different results, it means the dataset is not compatible with Bell's inequality for purely mathematical reasons. Do you agree? If you don't please explain clearly.

billschnieder

Aug7-10, 01:19 PM

In case there is any doubt left. Let us now go through Bell's paper and show step by step, and show that the physical assumptions are peripheral to the derivation of the inequality.

We start by recognizing that Bell has defined a deterministic function A(.,.) which is a two valued function with values (+1 or -1) for a single particle. This is done in equation (1) of his original paper, as follows:

A(a,\lambda ) = \pm 1, B(b,\lambda ) = \pm 1

Let us show set up our own definitions side by side. Let us pick two arbitrary variables a', b' with values (+1 or -1). For our purpose, it is not important what the physical situation is between a', or b' or whether there is remote dependence between a' and b'. All that is important for us is that we have two such arbitrary variables without any regard as to what physical process may be producing them. Please do not confuse our variables a' and b', with Bell's vectors (a and b). a' and b' are rather analogous to Bell's two-valued functions A(.,.) and B(.,.). We will harmonize the notation later. In our case, the analogy of Bell's equation (1) above is the following:
a' = \pm 1, b' = \pm 1

Now let us go to Bell's equation (2) where he defines his expectation values

E(a,b) = \int d\lambda \rho (\lambda )A(a,\lambda )B(b,\lambda )

Note, what Bell is doing here is calculating the weighted average of the product A(a,λ)*B(b,λ) for all λ. Which is essentially the expectation value. Theoretically the above makes sense, where you measure each A(a,.), B(b,.) pair exactly once for a specific λ, and simply multiply with the probability of realizing that specific λ and then add up subsequent ones to get your expectation value E(a,b). But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities. Practically, this is the only way available to obtain expectation values, since no experimenter has any idea what the λ's are or how many of them there are. All they can do is assume that by measuring a large number of points, their data will be as representative as illustrated above.(This is the fair sampling assumption which is however not the focus of this post.) So then in this case, assuming discrete λ's, that Bell's equation (2) is equivalent to the following simple average:
E(a,b) = \frac{1}{N} \sum_{i}^{N} A(a,\lambda _i)B(b,\lambda _i)
Since in any real experiment we do not know which λ is realized for any specific iteration, we can drop lambda from the equation altogether without any impact, where we have simply absorbed the λ into the specific variant of the functions A,B operating for iteration i (that is Ai and Bi)
E(a,b) = \frac{1}{N} \sum_{i}^{N} A(a)_{i}B(b)_{i}
And we could adopt a simplified notation in which we replace the function A(a)_i with the outcome \alpha _i and B(b)_i with \beta _i. Note that the outcomes of our functions are restricted to values (+1 or -1) and we could say \alpha = \pm 1, \beta = \pm 1

To get:
E(a,b) = \frac{1}{N} \sum_{i}^{N} \alpha _{i} \beta _{i} = <\alpha \beta >
Let us then develop our analogy involving our a' and b' to the same point. Remember our first assumption was that we had two such arbitrary variables a' and b' with values (+1 or -1). Now consider the situation in which we had a list of pairs of such variables of length N. Let us designate our list [(a',b')] to indicate that each entry in the list is a pair of (a',b') values. Let us define the expectation value of the pair product for our list as follows:
E(a',b') = \frac{1}{N} \sum_{i}^{N} {a}'_{i} {b}'_{i} = <a'b'>
For all practical purposes, this equation is exactly the same as the previous one and the terms a' and b' are mathematically equivalent to α and β respectively. What this shows is that the physical assumptions about existence of hidden variables, locality etc are not necessary to obtain an expression for the expectation values for a pair product. We have obtained the same thing just by defining two variables a', b' with values (+1 and -1) and calculating the expectation value for the paired product of a list of pairs of these variables. You could say the reason Bell obtained the same same expression is because he just happened to be dealing with two functions which can have values (+1 and -1) for physical reasons and experiments producing a list of such pairs. And he just happened to be interested in the pair product of those functions for physical reasons. But the structure of the calculation of the expectation value is determined entirely by the mathematics and not the physics. Once you have two variables with values (+1 and -1) and a list of pairs of such values, the above equations should arise no matter the process producing the values, whether physical, mystical, non-local, spooky, super-luminal, or anything you can dream about. That is why I say the physical assumptions are peripheral.

Note a few things about the above equation. a'_i and b'_i must be multiplied with each other. If we independently reorder the columns in our list so that we have different pairings of a'_i and b'_i, we will obtain the same expectation value only in the most improbable of situations. To see this, consider the simple list below

a' b'
+ -
- +
- +
+ -

<a'b'> = -1/4

If we rearrange the b' column so that the pairing is no longer the same, we may have something like the following were we have the same number of +'s and -'s but their pairing is different:

a' b'
+ +
- -
- -
+ +

<a'b'> = 1/4
Which tells us that we are dealing with an entirely different dataset.

billschnieder

Aug7-10, 01:21 PM

JesseM

Aug7-10, 04:56 PM

(reply to post #1208, part 1)
Note the underlined texts as we will come back to it. Now let us consider our previous discussion about this in post #857.
The same probability distribution should apply to each of the four terms, but the inequality should hold regardless of the specific probability distribution (assuming the universe is a local realist one and the specific experimental conditions assumed in the derivation apply).
So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?
If you remember, our previous discussion fell apart at the point where you refused to give a straight answer to the last question above.
Well, no, you are completely misremembering why our previous discussion "fell apart". In fact I did give you a clear answer to this question in post #861 (http://www.physicsforums.com/showthread.php?p=2775291#post2775291):
When you suggest the possibility that P(λi) could be "different for at least one of the terms in the inequality", that would imply that P(λi) depends on the choice of detector settings, since each expectation value is defined relative to a particular combination of detector settings. Am I understanding correctly, or are you talking about something else?

If I am understanding you right, note that it's generally accepted that one of the assumptions needed in Bell's theorem is something called the "no-conspiracy assumption", which says the decisions about detector settings should not be correlated with the values of the hidden variables.

...

So, I agree the inequality can only be assumed to hold if the choice of detector settings and the value of the hidden variables are statistically independent (which means the probability distribution P(λi) does not change depending on the detector settings), but this is explicitly included as an assumption in the more rigorous modern derivations. If you dispute that a "conspiracy" of the type being ruled out here would in fact have some very physically implausible features so that it's reasonable to rule it out, I can give you some more detailed arguments for why it's so implausible.
Then in post #862 you said:
You are wondering off now, JesseM. Try not to pre-empt the discussion. The question I asked should have a straightforward answer. The reason why P(λi) might be different shouldn't affect the answer you give to my question. If you believe P(λi) will be different when a conspiracy is involved, then you should have no problem admitting that Bell's inequalities do not apply to situations in which there is conspiracy.
And in post #863 I responded to the last sentence (...'then you should have no problem admitting that Bell's inequalities do not apply to situations in which there is conspiracy') by saying:
Didn't I already "admit" that in my last post? Read again:
So, I agree the inequality can only be assumed to hold if the choice of detector settings and the value of the hidden variables are statistically independent (which means the probability distribution P(λi) does not change depending on the detector settings)
So, I made quite clear that my answer to your question was "yes", I agreed that the inequality can only be assumed to hold if the probability distribution P(λi) is assumed to be the same for each of the terms E(a,b), E(a,b'), E(a',b) and E(a',b'). But I additionally explained that assuming the probability distribution was the same for each term was equivalent to the no-conspiracy assumption, i.e. P(λi) = P(λi | a,b) = P(λi | a,b') = P(λi | a',b) = P(λi | a',b'). Your complaint in subsequent posts was not that I had failed to give clear answers to any of your questions, but just a complaint that you didn't like the fact that I made additional commentary about the reasoning behind my answers, commentary which I thought would help people reading the thread to better understand the issues being discussed. You wanted me to shut up and not make any additional comments I deemed relevant, and restrict myself only to short answers to your questions. For example in post #864 you made it clear that you did understand I had answered your questions, and just wanted me to snip out all the surrounding commentary about my answers:
So then, I will assume that the last few posts did not happen, and I will consider that the responses moving forward are as follows:
So then, if it was found that it is possible in a local realist universe for P(λi) to be different for at least one of the terms in the inequality, above, then the inequality will not apply to those situations where P(λi) is not the same. In other words, the inequalities above are limited to only those cases for which a uniform P(λi) can be guaranteed between all terms within the inequality. Do you disagree?
... I agree ...
Do you believe P(λi) can different between the terms if and only if conspiracy is involved?
Yes ...

See how short and to the point this would have been. You would have saved yourself all the typing effort, and to boot, we don't have to start a new rabbit trail about the meaning of "conspiracy"!
Then later in that same post you made clear that your actual objection was to my additional explanatory commentary, and threatened to end the discussion if I wouldn't agree to restrict my comments only to short answers to your questions:
But if you now define conspiracy in a manner that I don't agree with, I will be forced to challenge it because if I don't it may appear as though I agree with that definition, then we end up 20 posts later, discussing whose definition of "conspiracy" is correct, having left the original topic. The more you write, the more things need to be challenged in your posts and the more off-topic the discussions will get. This is why I insist that the discussion be focused. I hope you will recognize and respect this, otherwise there is no point continuing this discussion.
It is certainly reasonable to expect that one's discussion partner will give clear answers to any questions you ask, but it's not reasonable to expect that they restrict themselves only to short answers to your questions and not make any additional commentary they think is relevant. That unreasonable expectation on your part was why the earlier discussion shut down, not because I didn't "give a straight answer" to any of the questions you asked.

Sorry to spend so much time rehashing old disagreements but I don't like being accused of refusing to answer any question, that's something I will always try my best to do. Moving on to the substance of your current post:
You say, Bell is refering to the measurement of AN entangled pair with detectors set at a and b. I agree.
So, you agree that "resorting" the data, in the way you did in post #1187 (http://www.physicsforums.com/showthread.php?p=2824701#post2824701), is out of the question? That no physicist would interpret a term like E(a,b) to possibly involve taking the result from a detector with setting a during a trial where the two detectors were set to a,b' and multiplying it by the result from a detector with setting b during a trial where the two detectors were set to a',b?
You also say, in order to obtain the expectation value for this pair of angles, Bell integrates over all λi, so that there is a λi probability distribution. I agree also. This is precisely why I asked you all those questions earlier and you also agreed with me that this λi probability distribution must be exactly the same for all expectation value terms in Bell's inequality.
Yes, I did agree, giving you "a straight answer" to this question even though I added some additional commentary about why it is reasonable to expect the probability distribution to be the same regardless of detector settings.
Now please pay attention and make sure you actually understand what I am saying next before you respond.
The reason why the probability distribution of λi must be the same is the following (using the equations you presented, except using E for expectation to avoid confusion with Probability notation).
E(a,b) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(b,\lambda )
E(a,c) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(c,\lambda )
E(b,c) = -\int d\lambda\rho (\lambda )A(b,\lambda )A(c,\lambda )
I don't understand how you can say that those equations are "the reason why" the probability distribution is the same. Are you suggesting that those equations can be taken as definitions of E(a,b) and E(a,c) and E(b,c), and thus it is true by definition that the probability distribution \rho (\lambda ) is the same in each case? I would say that a term like E(a,b) is understood to be defined as the expectation value for the product of two measurements on a pair of entangled particles when the detectors are set to a and b, and that Bell then tries to physically justify why we would expect E(a,b) to be given by the equation above in a local realist universe. So any feature of the equations, like \rho (\lambda ) being the same in each, cannot be justified by pointing to the equations themselves, there has to be a physical justification for it or else someone following the derivation would have no reason to agree that the equations above are actually correct in a local realist universe. Do you agree that the derivation depends on the idea that there's a physical justification for assuming \rho (\lambda ) is the same in each of those three equations, that we can't just point to the equations themselves to explain the "reason" that \rho (\lambda ) is the same?

If you disagree with that, I would just point you again to Bell's paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) which I brought up earlier in post #1171 when showing that the simple Bell inequality I originally brought up was one that Bell had actually discussed. On p. 15 of the pdf file (p. 14 of the paper itself) he does bring up the other inequality we had been discussing before you refused to continue if I didn't keep my answers short:

|E(a,b) + E(a,b') + E(a',b) - E(a',b')| <= 2

Then on p. 16 of the pdf (p. 15 of the paper), in the "Envoi" section, he discusses possible objections one might have to his conclusion that the inequality should be obeyed in a local realist universe. And at the bottom of this page, he explicitly brings up the possibility that \rho(\lambda) could be different from term to term, and gives a physical argument for why he considers this very implausible:
Secondly, it may be that it is not permissible to regard the experimental settings a and b in the analyzers as independent variables, as we did. We supposed them in particular to be independent of the supplementary variable λ, in that a and b could be changed without changing the probability distribution \rho(\lambda). Now even if we have arranged that a and b are generated by apparently random radioactive devices, housed in separate boxes and thickly shielded, or by Swiss national lottery machines, or by elaborate computer programmes, or by apparently free willed experimental physicists, or by some combination of all of these, we cannot be sure that a and b are not significantly influenced by the same factors λ that influence A and B. But this way of arranging quantum mechanical correlations would be even more mind boggling than one in which causal chains go faster than light. Apparently separate parts of the world would be deeply and conspiratorially entangled, and our apparent free will would be entangled with them.
So, clearly he doesn't think that E(a,b) and E(a,b') can be said to have the same probability distribution on λ by definition, rather he provides a physical argument to justify this idea.
Note a few things about the above. There are two factorable terms inside the integral, one for each angle. You can visualize this integral in the following descrete way. We have a fixed number of λi, say (λ1, λ2, λ3, ... λn). To calculate the integral, we multiply A(a,λ1)A(b,λ1)*P(λ1) and add it to A(a,λ2)A(b,λ2)*P(λ2) ... all the way to λn. In other words, the above will not work if we did A(a,λ1)A(b,λ5)*P(λ3) or any such.
Agreed--note that if you mixed them up in that way you would no longer be computing an "expectation value" for the product of the two measurement results on a single pair of entangled particles, since it's assumed that on each trial with a single pair, λ takes a single value on that trial (its value is supposed to be determined by the values of all hidden variables on a given trial)

JesseM

Aug7-10, 04:58 PM

(reply to post #1208, part 2)

Secondly, once we have our inequality:

|E(a,b) - E(a,c)| - E(b,c) <= 1

To say the probability distribution of λi must be the same means that, if we obtained E(a,b) by integrating over a series of λi values, say (λ1, λ2, λ4), the same must apply to E(a,c) and E(b,c). In other words, it is a mathematical error to use E(a,b) calculated over (λ1, λ2, λ4), with E(a,c) calculated over (λ6, λ3, λ2) and E(b,c) calculated over (λ5, λ9, λ8) in the above inequality, because in that case ρ(λi) will not be the same across the terms the way Bell intended and we agree that he did.
True, but now you're talking about a completely different sense of what it would mean for ρ(λi) to "not be the same across the terms" than what I was talking about. I wasn't talking about only adding some values of λ in the sums for each term, I was just talking about how each term could involve a different probability distribution on all possible values of λi, i.e. one might use a probability distribution P1(λ) such that P1(λ5) = 0.03% while another might use a different probability distribution P2(λ) such that P2(λ5) = 1.7%. That is what it would mean to violate the no-conspiracy assumption, it doesn't have anything to do with only adding some values of λ in the sum for each term. Even if the no-conspiracy assumption was violated, the discrete case in a local realist universe (where the result A was always completely predetermined by the value of λ and the choice of detector setting a, b, or c) where there were N possible values of λ would still look like this:

E(a,b) = - \sum_{i=1}^N A(a,\lambda_i)*A(b,\lambda_i)*P_1 (\lambda_i)
E(b,c) = - \sum_{i=1}^N A(b,\lambda_i)*A(c,\lambda_i)*P_2 (\lambda_i)
E(a,c) = - \sum_{i=1}^N A(a,\lambda_i)*A(c,\lambda_i)*P_3 (\lambda_i)

You can see that the only difference here is that the three sums have different probability distributions on λ--P1, P2, and P3--but each sum still includes every possible value of λ (i.e. λ1, λ2, λ3, ... , λN)

Perhaps you are worried that even if we assume the probability distribution P(λ) is the same for each term, there could be trillions of values of λ and thus the subset of trials where we used detector angles a,b might involve a totally different collection of λi's than the subset of trials where we used detector angles b,c or the subset where we used detector angles a,c. If so, this objection is misguided, and once again the reason has to do with the Law of large numbers (http://en.wikipedia.org/wiki/Law_of_large_numbers). "Expectation values" are theoretical calculations about what the average result of some experiment would be in the limit as the number of trials goes to infinity. And one can show mathematically that if you're dealing with an experiment that only has two possible results +1 and -1, then for a reasonably large number of trials (say, 1000) the probability that the average experimental result will differ significantly from the expectation value becomes astronomically small, regardless of how many possible values can be taken by other variables "behind the scenes" which determine whether the final result +1 or -1. This was the point I made back in post #51 on the 'Understanding Bell's Logic' thread (http://www.physicsforums.com/showthread.php?p=2761085#post2761085), which you never responded to:
I'm fairly certain that the rate at which the likelihood of significant statistical fluctuations drops should not depend on the number of λn's in the integral. For example, suppose you are doing the experiment in two simulated universes, one where there are only 10 possible states for λ and one where there are 10,000 possible states for λ. If you want to figure out the number N of trials needed so that there's only a 5% chance your observed statistics will differ from the true probabilities by more than one sigma, it should not be true that N in the second simulated universe is 1000 times bigger than N in the first simulated universe! In fact, despite the thousandfold difference in possible values for λ, I'd expect N to be exactly the same in both cases. Would you disagree?

To see why, remember that the experimenters are not directly measuring the value of λ on each trial, but are instead just measuring the value of some other variable which can only take two possible values, and which value it takes depends on the value of λ. So, consider a fairly simple simulated analogue of this type of situation. Suppose I am running a computer program that simulates the tossing of a fair coin--each time I press the return key, the output is either "T" or "H", with a 50% chance of each. But suppose the programmer has perversely written an over-complicated program to do this. First, the program randomly generates a number from 1 to 1000000 (with equal probabilities of each), and each possible value is associated with some specific value of an internal variable λ; for example, it might be that if the number is 1-20 that corresponds to λ=1, while if the number is 21-250 that corresponds to λ=2 (so λ can have different probabilities of taking different values), and so forth up to some maximum λ=n. Then each possible value of λ is linked in the program to some value of another variable F, which can take only two values, 0 and 1; for example λ=1 might be linked to F=1, λ=2 might be linked to F=1, λ=3 might be linked to F=0, λ=4 might be linked to F=1, etc. Finally, on any trial where F=0, the program returns the result "H", and on any trial where F=1, the program returns the result "T". Suppose the probabilities of each λ, along with the value of F each one is linked to, are chosen such that if you take [sum over i from 1 to n] P(λ=i)*(value of F associated with λ=i), the result is exactly 0.5. Then despite the fact that there may be a very large number of possible values of λ, each with its own probability, this means that in the end the probability of seeing "H" on a given trial is 0.5, and the probability of seeing "T" on a given trial is also 0.5.

Now suppose that my friend is also using a coin-flipping program, where the programmer picked a much simpler design in which the computer's random number generator picks a digit from 1 to 2, and if it's 1 it returns the output "H" and if it's 2 it returns the output "T". Despite the differences in the internal workings of our two programs, there should be no difference in the probability either of us will see some particular statistics on a small number of trials! For example, if either of us did a set of 30 trials, the probability that we'd get more than 20 heads would be determined by the binomial distribution (http://en.wikipedia.org/wiki/Binomial_distribution), which in this case says there is only an 0.049 chance of getting 20 or more heads (see the calculator here (http://stattrek.com/Tables/Binomial.aspx)). Do you agree that in this example, the more complex internal set of hidden variables in my program makes no difference in statistics of observable results, given that both of us can see the same two possible results on each trial, with the same probability of H vs. T in both cases?

For a somewhat more formal argument, just look at this textbook chapter on the law of large numbers (http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/Chapter8.pdf), particularly the equation that appears on p. 3 after the sentence that starts "By Chebyshev's inequality ..." If you examine the equation and the definition of the terms above, you can see that if we look at the the average value for some random value X after n trials (the S_n / n part), the probability that it will differ from the expectation value \mu by an amount greater than or equal to \epsilon must be smaller than or equal to \sigma^2 / n\epsilon^2, where \sigma^2 is the variance in the value of the original random variable X. And both the expectation value for X and the variance of X depend only on the probability that X takes different possible values (like the variable F in the coin example which has an 0.5 chance of taking F=0 and an 0.5 chance of taking F=1), it shouldn't matter if the value of X on each trial is itself determined by the value of some other variable λ which can take a huge number of possible values.
Note also that even if the set of λ's is the same, we still need each λ to be sampled the exact same number of times for each term.
No, see above. The expectation value is the average value we'd expect theoretically in the limit as the number of trials approaches infinity, and my argument from post #51 of "Understanding Bell's logic" explains why, if we do say three runs with 1000 trials each for all three possible combinations of different detector settings, it'd be astronomically unlikely for the average results seen experimentally in each run to differ significantly from the expectation values (assuming that the theoretical assumptions about the laws of physics that went into deriving expressions for the expectation values are actually correct), even if there happen to be 200 googolplex possible values of λ. If you disagree, perhaps you should actually address my example with the coin-flipping program rather than just dismissing it as irrelevant like you did on the "Understanding Bell's logic" thread.
Now what I have just describe here are the specific experimental conditions that should apply for Bell's inequality to be applicable to data obtained from any experiment.
Nope, there is no need for each run to sample all values of λi (or for different runs to sample the same values of λi), just as there wouldn't be such a need in the coin-flipping simulation example where the result "heads" or "tails" on each flip depends on the value of an internal random variable λ which can take a huge number of possible values, but the total probability of getting "heads" or "tails" on each flip is still 0.5 (so the theoretical expectation value if heads=+1 and tails=-1 would be 0), and the law of large numbers still says that if you do a few hundred flips the probability that the fraction of "heads" will be significantly different from 0.5 (or the probability that the average value with heads=+1 and tails=-1 is significantly different from 0) will be astronomically small, even if you sampled only a tiny fraction of the possible values of the internal variable λ.

This brings us to the sorting I mentioned earlier which you are having difficulty with.
Suppose in any actual experiment, the experimenter also had along side each pair of measurements in each run, the specific value of λ for that run. He will now have a long list of pairs of +'s and/ -'s plus one indexed λ each. Such that for the three runs of the experiment he will have three lists which look something similar to the following, except the actuall sequence of +'s and/ -'s and λ's will be different

+ - λ1
- + λ9
+ + λ6
- + λ3
...

In such a case, it will be easy to verify if his data meets the requirement that ρ(λi) is the same for each term, as you agreed to previously. He could simply sort each of the three lists according to the λ column and compare if the λ column from all three runs are the same.
Again, you misunderstood what I meant when I agreed "ρ(λi) is the same for each term", see the discussion above starting with the paragraph that begins "True, but now you're talking about a completely different sense..." I just meant that the "true" probability distribution for a given pair of settings like a,b, which in frequentist terms can be understood as giving the fraction of trials/iterations with each value of λi that would be obtained in the limit as the number of trials/iterations with those settings went to infinity, would be identical to the "true" probability distribution for a different pair of settings like b,c. Then the law of large numbers indicates that even if you only do 3 runs with 1000 iterations each, and the λi's were completely different on each run, it's still astronomically improbable that the average values you obtain for each run will differ significantly from the "true" expectation values for each setting which can be calculated from the "true" probability distribution ρ(λi).
If they are not, ρ(λi) is different and Bell's inequality can not be applied to the data for purely mathematical reasons.
No, you're confusing the theoretical ρ(λi) which appears in the equations calculating expectation values with the actual truth about the fraction of trials/iterations with each value of λi on some finite set of runs, which might better be denoted F(λi). If the number of trials/iterations is not much larger than the number of possible values of λi, then F(λi) might well be wildly different than ρ(λi), but exactly the same would be true in my coin flip simulation example and it wouldn't change the fact that if you do 1000 simulated flips, the chance you will have gotten a number of heads significantly different than 500 is astronomically small. If you think it's actually necessary to sample every value of λi in order to be highly confident that our average result was very close to the "true" expectation value, then you're just misunderstanding how the law of large numbers works.
In other words, if they insisted to calculate the LHS of the inequality with that data, the inequality is not guaranteed to be obeyed, for purely mathematical reasons.
Even if all the theoretical assumptions used in the expectation value equations are correct, there's some small probability that experimental data won't satisfy the inequality, but for a reasonably large number of trials/iterations on each run (say, 1000), this probability becomes astronomically small (the probability that the experimental average differs by a given amount from the expectation value can be calculated using the binomial distribution (http://stattrek.com/Tables/Binomial.aspx)).

JesseM

Aug7-10, 04:58 PM

(reply to post #1208, part 3)

However, experimenters do not have the λ's so how can they make sure their data is compatible? If it is assumed that each specific λ contains all properties that will deterministically result in the outcome, then we do not need the λs to sort our data. We can just sort the actual result pairs so that the "a" colum of the (a,b) pair matches the "a" column of the (a,c) pair and the "b" and "c" columns also match. If we can do that, then we can be sure that ρ(λi) is the same for all three terms of the inequality and Bell's inequality should apply to our data.
I'm not sure I follow what you mean here. Suppose we do only 4 iterations with each pair of different detector settings, and get these results (with the understanding that notation like a=+1 means 'the result with detector set to angle a was +1):

For run with setting (a,b):
1. (a=+1, b=-1)
2. (a=-1, b=-1)
3. (a=-1, b=+1)
4. (a=+1, b=-1)

For run with setting (b,c):
1. (b=-1, c=+1)
2. (b=-1, c=-1)
3. (b=-1, c=+1)
4. (b=+1,c=-1)

For run with setting (a,c):
1. (a=+1, c=-1)
2. (a=+1, c=+1)
3. (a=-1, c=-1)
4. (a=-1, c=+1)

Then we can arrange these results into four rows of three iterations from three runs, such that in each row the value of a is the same for both iterations that sampled a, in each row the value of b is the same for both iterations that sampled b, and in each row the value of c is the same for both iterations that sampled c:

1. (a=+1, b=-1) 3. (b=-1, c=+1) 2. (a=+1, c=+1)
2. (a=-1, b=-1) 1. (b=-1, c=+1) 4. (a=-1, c=+1)
3. (a=-1, b=+1) 4. (b=+1,c=-1) 3. (a=-1, c=-1)
4. (a=+1, b=-1) 2. (b=-1, c=-1) 1. (a=+1, c=-1)

So, we could "resort" the iteration labels for the second run (middle column) such that the former third iteration was now labeled the first, the former first iteration was now labeled the second, the former fourth iteration was now labeled the third, and the former second iteration was now labeled the fourth. Likewise for the third run (right column) we could say the former second iteration was now labeled the first, the former fourth iteration was now labeled the second, the third iteration remained the third, and the former first iteration was now labeled the fourth. Is this the type of "resorting" you mean?

If so, I don't see how this ensures that "ρ(λi) is the same for all three terms of the inequality", or what you even mean by that. For example, isn't it possible that if the number of possible values of λ is 1000, then even though iteration #1 of the first run has been grouped in the same row as iteration #3 of the second run and iteration #2 of the third run (according to their original labels), that doesn't mean the value of λ was the same for each of these three iterations? For example, might it not have been the case that iteration #1 of the first run had λ203, iteration #3 of the second run had λ769, and iteration #2 of the third run had λ488?

As a separate issue it is of course true that if your full set of data can be resorted in this way, that's enough to guarantee mathematically that the data will obey Bell's inequality. But this is a very special case, I think it would be fairly unlikely that the full set of iterations from each run could be resorted such that every row would have the same value of a,b,c throughout, even if the data was obtained in a local realist universe that obeyed Bell's theoretical assumptions, and even if the overall averages from each run actually did obey the Bell inequality.
If we can not, it means ρ(λi) is different, and the data is mathematically not compatible with the inequality.
But again that doesn't seem to be true (if I am interpreting your meaning correctly), the prediction that experimental data is highly unlikely to violate the inequality in a local realist universe doesn't require that the values of λ matched on the three experimental runs with different pairs of detector settings. The law of large numbers means that if the equations giving the theoretical expectation values are correct, and the theoretical expectation values obey some inequality, then the probability that experimental data from a finite series of runs would violate the inequality will become astronomically small for a reasonable number (say, a few hundred or a few thousand) trials/iterations, even if this number is vastly smaller than the number of possible values of λ, whose value (along with the detector settings) determines the results on each trial.
Let us look at this slightly differently. Consider our first list which included the λ's. After sorting all three runs by the λ's we will find that we only need three columns of +'s and/ -'s out of the 6 (2 from each run). This is because each column will be duplicated. This simply means for each λ, there are 3 simultaneously existing properties at the angles.
Each value of λ is associated with a triplet of predetermined results for settings a,b,c, so if you could somehow know the value of λ on each trial and you knew what settings were used on that trial, that would be sufficient to tell you the results obtained on that trial. Is that basically what you're saying here, or are you making some additional point?
Now, what if instead of collecting three runs of pairs we collected a single run of triples so that the data from our experiment is
a b c
+ - + λ1
- + + λ9
+ + - λ6
- + + λ3
...

We do not need any sorting here because we can calculate all our terms from the same single run with the same ρ(λi). So we can compare ANY dataset of this type with Bell's inequality.
You could only "compare it with Bell's inequality" by changing the meaning of the terms in Bell's inequality, which deal with expectation values for experiments where the experimenter only collected a pair of results on each trial, with some specific pair of detector settings. As I've said before, it is of course true that you can prove an inequality like this in a purely mathematical way:

1 + (average value of b*c for all triples)
>= |(average value of a*b for all triples) - (average value of a*c for all triples)|

But that's not Bell's inequality! The terms in Bell's inequality have a meaning like this:

1 + (average value of b*c for all trials where experimenter sampled b and c)
>= |(average value of a*b for all trials where experimenter sampled a and b) - (average value of a*c for all trials where experimenter sampled a and c)|
However, since it is not possible to measure triples in any experiment, the requirement to be able to sort the dataset applies to all datasets involving multiple runs of pairs.
No, this is not a "requirement" unless you adopt the strawman position that the inequality is supposed to be guaranteed to hold with probability 1, even for a finite number of trials. But no physicist would claim that, the claim is just that in a local realist universe the actual averages should approach the ideal expectation values as the number of trials becomes large, so in a local realist universe matching Bell's theoretical assumptions, an experiment matching his experimental conditions should have a very tiny probability of yielding data that violates the inequality.
Now, let us go back to the underlined text above. Since you agreed with me that ρ(λi) must be the same for each term in the inequality
As noted above I may have meant something different by this than you do, I was talking about the "true" probability distribution and not the actual fraction of trials/iterations with a given value of λi (I used the notation F(λi) to distinguish this second from the first).
Is that what you were alluding to with the underlined text: "which is equivalent to the average measurement result over a very large (approaching infinity) series of measurements"? In other words, why is it important that the number of measurements be very large? Please I need a specific answer to this question, assuming you are still willing to contest this issue after my very detailed explanation above.
It's important because true probabilities are understood to be different from actual frequencies on a finite number of trials in the frequentist view, and I don't think there's any sensible way to interpret the probabilities that appear in Bell's proof in non-frequentist terms. An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity, and likewise the ideal probability distribution ρ(λi) would in frequentist terms give the fraction of all trials where λ took the specific value λi, again in the limit as the number of trials goes to infinity. Then you can show theoretically that given Bell's physical assumptions, we can derive an inequality like this one:

1 + E(b,c) >= |E(a,b) - E(a,c)|

Then by the law of large numbers, you can show that the likelihood of a significant difference between the "true" expectation value E(b,c) and the experimental average (average for product of two results on all trials where detectors were set to b and c) becomes tiny as the number of trials becomes reasonably large (say, 1000), regardless of whether the ideal probability distribution ρ(λi) is very different from the actual function F(λi) describing the fraction of trials with each value of λi (both functions would be unknown to the experimenter but they should have some true objective value which might be known to an omniscient observer). So, from this we can conclude that with a reasonably large number of trials, it'd be astronomically unlikely in a local realist universe for the experimental data to violate this inequality:

1 + (average value of b*c for all trials where experimenter sampled b and c)
>= |(average value of a*b for all trials where experimenter sampled a and b) - (average value of a*c for all trials where experimenter sampled a and c)|

What specific step(s) in this reasoning do you have an objection to?
As an aside:
You seem to have an issue with my use of

| <ab> + <ac> | - <bc> <= 1

In which I have replaced E(a,b) in Bell's notation with <ab> in mine. Where a,b represent the outcomes at angles a and b and I was referring to the fact that in calculating the averages, it is not allowed for the list of a's in the first term to contain a different number of +'s and/ -'s from that in the second term and same for "c" and "b".
OK, the phrase I bolded above now helps clarify what you meant when you said "the symbols ("a", "b" and "c") mean exactly the same thing from term to term", but there was really no way I could have been expected to deduce that without you spelling it out explicitly! Your requirement that we be able to "resort" the data from all three runs such that every row of three iterations from three runs has the same values of a,b,c throughout is a completely idiosyncratic idea no physicist ever brings up in discussions of Bell's theorem, and before post #1208 you hadn't explained it (your previous example involving 'resorting' didn't involve lining up three iterations from three runs, rather it involved creating a fake 'triple' from an iteration of the second run where a and c were measured and an iteration from the third run where b and c were measured, combining the values of a and c from the first iteration with the value of b from the second...see the end of my post #1191 for a discussion of this).
You objected and said:
"a" is just a detector angle rather than a result like +1 or -1, the text makes that clear, so of course it means the same thing everywhere. But P(a,b) is an expectation value (he called it that himself), which can be understood as the average value of the product of two measurements on a pair of entangled particles with detectors at angles a and b, in the limit as the number of particle pairs measured in this way goes to infinity.
But then later, you used exactly the same notation.
The point of my objection was that I [i]didn't understand what you meant when you said 'In Bell's inequality the the "a" in the first two terms are exactly the same.' Whenever I used notation like a*b, I always explained that this was really meant to be a shorthand for the product of two measurement results (each either +1 or -1) on a single pair of particles with detectors set to angles a and b. But that doesn't help to understand what you might mean by 'the "a" in the first two terms are exactly the same', and you didn't explain the meaning before, how was I supposed to know you were talking about reordering each list of iterations such that the value of a in the ith iteration of the run with settings a,b would always match the value of a in the ith iteration of the run with settings a,c? (assuming I have finally understood what you meant, if not please explain) Like I said this is a very idiosyncratic notion of yours and I'm not a mind reader so unless you spell it out I'm not gonna know what you're talking about. I didn't assume that the "a" in your phrase 'the "a" in the first two terms are exactly the same' did refer to the detector angle, I just didn't know what it meant and was expressing confusion, and I explicitly asked you for a clarification on this in the second part of my reply (post #1206) when I said:
It doesn't mean you need to resort it in order to calculate the terms. It just means being able to resort the data is evidence that the symbols are equivalent. It is just another way of saying the symbols ("a", "b" and "c") mean exactly the same thing from term to term.
I still don't know what you mean by "mean exactly the same thing from term to term". a, b and c are just placeholders, for each triple each one can take value +1 or -1, for example in the first triple on your list you might have a=+1 while on the second triple you might have a=-1. Do you just mean that each term deals with averages from exactly the same list of triples, rather than each term dealing with averages from a separate list of triples?
This tactic of yours combined with lack of willingness to actually understand the opposing view, combined with a severe case of irrelevant argumentum ad verbosium, is the reason I do not take you seriously.
Again, this is very uncharitable, not to mention paranoid. When I express confusion about a vague phrase of yours, you act as though it's some sort of sneaky "tactic", and you imagine your posts to be such models of clear exposition that any failure to immediately grok what you are saying must reveal a "lack of willingness to actually understand the opposing view" (speaking of lack of willingness, I do try to address all your arguments as best I can, whereas you immediately dismiss anything that you don't immediately see the relevance of like my coin-flipping simulation example from the 'Understanding Bell's logic' thread...what's more, addressing all your arguments itself requires long posts, and then you interpret this too in a hostile mocking way as 'argumentum ad verbosium'). If you would move away from such a hostile/paranoid mindset, and consider that there might be some truth in what I said at the end of post #1190:
But of course the most charitable and fair assumption is that communication about complex issues like these is sometimes difficult and arguments that may seem clear to you can seem genuinely ambiguous to intelligent readers who aren't privy to all your thought processes.
...then this discussion would probably proceed a lot more smoothly and with less hostility.

JesseM

Aug7-10, 05:18 PM

You must agree therefore that the following is Bell's inequality.

|\sum_{i} A(a, \lambda_{i} )A(b,\lambda_{i} ) P(\lambda_{i} ) + \sum_{i} A(a, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} )| - \sum_{i} A(b, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} ) \leq 1

Which can be factored in this form.

|\sum_{i} P(\lambda_{i} )A(a, \lambda_{i} )\left [ A(b,\lambda_{i} ) + A(c,\lambda_{i} )\right ]| - \sum_{i} A(b, \lambda_{i} )A(c,\lambda_{i} ) P(\lambda_{i} ) \leq 1

Bell himself did a similar factorization. Therefore if for any dataset the two equations above produce different results, it means the dataset is not compatible with Bell's inequality for purely mathematical reasons. Do you agree? If you don't please explain clearly.
If by "dataset" you mean some finite collection of experimental results, then I don't agree. The above equations are correct only insofar as they refer to the "true" probabilities and expectation values, which in frequentist terms can be understood in terms of fractions of trials with different possible results in the limit as the number of trials goes to infinity. But as I said in the following section of post #1215, Bell's proof is primarily about these ideal "true" probabilities and expectation values, then if you want to connect this with experimental data you have to invoke the law of large numbers (which is really implicit in all physical predictions involving probabilities, so physicists typically don't state this explicitly):
true probabilities are understood to be different from actual frequencies on a finite number of trials in the frequentist view, and I don't think there's any sensible way to interpret the probabilities that appear in Bell's proof in non-frequentist terms. An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity, and likewise the ideal probability distribution ρ(λi) would in frequentist terms give the fraction of all trials where λ took the specific value λi, again in the limit as the number of trials goes to infinity. Then you can show theoretically that given Bell's physical assumptions, we can derive an inequality like this one:

1 + E(b,c) >= |E(a,b) - E(a,c)|

Then by the law of large numbers, you can show that the likelihood of a significant difference between the "true" expectation value E(b,c) and the experimental average (average for product of two results on all trials where detectors were set to b and c) becomes tiny as the number of trials becomes reasonably large (say, 1000), regardless of whether the ideal probability distribution ρ(λi) is very different from the actual function F(λi) describing the fraction of trials with each value of λi (both functions would be unknown to the experimenter but they should have some true objective value which might be known to an omniscient observer). So, from this we can conclude that with a reasonably large number of trials, it'd be astronomically unlikely in a local realist universe for the experimental data to violate this inequality:

1 + (average value of b*c for all trials where experimenter sampled b and c)
>= |(average value of a*b for all trials where experimenter sampled a and b) - (average value of a*c for all trials where experimenter sampled a and c)|

billschnieder

Aug7-10, 08:31 PM

JesseM

Aug7-10, 09:39 PM

Now let us go to Bell's equation (2) where he defines his expectation values
E(a,b) = \int d\lambda \rho (\lambda )A(a,\lambda )B(b,\lambda )
Perhaps I am over-interpreting your use of the word "defines", but as I argued towards the end of post #1213 (starting with the paragraph that begins 'I don't understand how you can say...'), this paragraph cannot be taken as the definition of E(a,b), rather E(a,b) is understood to be defined in a physical way as the expectation value for the product of two measurements on an entangled particle pair with detector settings a and b. This expectation value is understood as a sum of the different possible measurement outcomes weighted by their "true" probabilities:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

And here the probabilities are the "objective" ones that would correspond in frequentist terms to the frequencies in the limit as the number of trials went to infinity.

Bell then gives some physical arguments as to why we'd expect the expectation value to take this form:

E(a,b) = \int d\lambda \rho (\lambda )A(a,\lambda )B(b,\lambda )

And here as before, \rho(\lambda) is assumed to be the "objective" probability distribution, not something we need to measure or even make guesses about in practice. We don't need to know anything about the details of this probability distribution to derive a general inequality that is expected to apply to the "true" probabilities of different measurement results under any set of local realist laws, and then we can use the law of large numbers to conclude that if we do some sufficient number of trials, our actual experimental averages are astronomically unlikely to differ from the expectation values determined by the "true" probabilities. Once again, here's my summary of the logic from post #1215:
true probabilities are understood to be different from actual frequencies on a finite number of trials in the frequentist view, and I don't think there's any sensible way to interpret the probabilities that appear in Bell's proof in non-frequentist terms. An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity, and likewise the ideal probability distribution ρ(λi) would in frequentist terms give the fraction of all trials where λ took the specific value λi, again in the limit as the number of trials goes to infinity. Then you can show theoretically that given Bell's physical assumptions, we can derive an inequality like this one:

1 + E(b,c) >= |E(a,b) - E(a,c)|

Then by the law of large numbers, you can show that the likelihood of a significant difference between the "true" expectation value E(b,c) and the experimental average (average for product of two results on all trials where detectors were set to b and c) becomes tiny as the number of trials becomes reasonably large (say, 1000), regardless of whether the ideal probability distribution ρ(λi) is very different from the actual function F(λi) describing the fraction of trials with each value of λi (both functions would be unknown to the experimenter but they should have some true objective value which might be known to an omniscient observer). So, from this we can conclude that with a reasonably large number of trials, it'd be astronomically unlikely in a local realist universe for the experimental data to violate this inequality:

1 + (average value of b*c for all trials where experimenter sampled b and c)
>= |(average value of a*b for all trials where experimenter sampled a and b) - (average value of a*c for all trials where experimenter sampled a and c)|
If you disagree with any of the above, please go back and address my specific arguments in posts #1213-1215.
Note, what Bell is doing here is calculating the weighted average of the product A(a,λ)*B(b,λ) for all λ. Which is essentially the expectation value. Theoretically the above makes sense, where you measure each A(a,.), B(b,.) pair exactly once for a specific λ, and simply multiply with the probability of realizing that specific λ and then add up subsequent ones to get your expectation value E(a,b). But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities. Practically, this is the only way available to obtain expectation values, since no experimenter has any idea what the λ's are or how many of them there are.
The comment above is completely misguided, since the basic definition of "expectation value" in this experiment has nothing at all to do with knowing the value of λ, it is just understood to be:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

Bell argues on a theoretical basis that E(a,b) should also be given by the integral involving \rho(\lambda), but the above should be understood as the basic meaning of an "expectation value". And by the law of large numbers, if you repeat the experiment a fairly large number of times (say 1000), the chances that the fraction of trials where you got some particular result (say, +1 with setting a and +1 with setting b) is significantly different from the "true probability" of that result (in this case P(detector with setting a gets result +1, detector with setting b gets result +1)) would become astronomically small, even if the number of trials was tiny compared to the number of possible values of λ. I gave a bunch of argument for this claim about the law of large numbers in post #1214, so if you disagree please go back and address that post. If you don't disagree, then you can see why in order to compare the inequality with experimental data we don't have to consider λ at all, we just have to use our dataset of pairs to find the average for the product of two results on each of the three combinations of different detector settings.
All they can do is assume that by measuring a large number of points, their data will be as representative as illustrated above.
They assume the averages from their data are close to the "true" expectation values E(a,b), E(b,c) and E(a,c), which can be justified by the law of large numbers, but there is no need to assume that the (unknown) frequencies of different values of λi which occurred in the particle pairs they sampled was anything like the "true" probability distribution p(λi). Do you disagree?
So then in this case, assuming discrete λ's, that Bell's equation (2) is equivalent to the following simple average:
E(a,b) = \frac{1}{N} \sum_{i}^{N} A(a,\lambda _i)B(b,\lambda _i)
How is it equivalent? It's quite possible that P(λ2) could be very different from P(λ3), for example, in which case you need to weigh the terms A(a,λ2)*B(b,λ2) and A(a,λ3)*B(b,λ3) by the probabilities of those values if you want to get an accurate expectation value. The correct discrete version would have to look like this:
E(a,b) = \frac{1}{N} \sum_{i}^{N} A(a,\lambda _i)*B(b,\lambda _i)*P(\lambda_i)
Since in any real experiment we do not know which λ is realized for any specific iteration, we can drop lambda from the equation altogether without any impact, where we have simply absorbed the λ into the specific variant of the functions A,B operating for iteration i (that is Ai and Bi)
E(a,b) = \frac{1}{N} \sum_{i}^{N} A(a)_{i}B(b)_{i}
Well, the i's in λi weren't supposed to be iterations, but rather were just a way of indexing all physically possible values that the hidden variables could take on that type of experiment--there could well be more possible values of i than particles in the observable universe! So if i in the equation above is supposed to refer to iterations you've significantly changed the meaning of the index, from something theoretical to something empirical. And again, Bell's reasoning is based on the "true" or "objective" probabilities of different outcomes which give the "true" expectation value, which is different from the empirical average which you are computing above, although the law of large numbers means that the difference between the two becomes small for a reasonably large number of trials (again see post #1214 on this point). Still, it's important to distinguish theoretical from empirical, so let's use E(a,b) to be the "true" expectation value for the product of the measurements with settings a and b, and Avg(a,b) to be the empirical average of all the products of measurement results on a run with settings a and b, and then we can say that in the limit as the number of trials/iterations in a run goes to infinity, Avg(a,b) should approach E(a,b) with probability 1. In this case I would rewrite the above as:

Avg(a,b) = \frac{1}{N} \sum_{i}^{N} A(a)_{i}B(b)_{i}
And we could adopt a simplified notation in which we replace the function A(a)_i with the outcome \alpha _i and B(b)_i with \beta _i. Note that the outcomes of our functions are restricted to values (+1 or -1) and we could say \alpha = \pm 1, \beta = \pm 1

To get:
E(a,b) = \frac{1}{N} \sum_{i}^{N} \alpha _{i} \beta _{i} = <\alpha \beta >
Which I would rewrite as:

Avg(a,b) = \frac{1}{N} \sum_{i}^{N} \alpha _{i} \beta _{i} = <\alpha \beta >
Let us then develop our analogy involving our a' and b' to the same point. Remember our first assumption was that we had two such arbitrary variables a' and b' with values (+1 or -1). Now consider the situation in which we had a list of pairs of such variables of length N. Let us designate our list [(a',b')] to indicate that each entry in the list is a pair of (a',b') values. Let us define the expectation value of the pair product for our list as follows:
E(a',b') = \frac{1}{N} \sum_{i}^{N} {a}'_{i} {b}'_{i} = <a'b'>
Again this doesn't work as a theoretical expectation value since i refers to some number of iterations, whereas a theoretical expectation value for an experiment which can give any one of N results R1, R2, ..., RN always has the form E(R) = \sum_{i=1}^N R_i * P(R_i). However, it does work as a way of computing the average for the product of a' and b' for a list of values, so in my notation:

Avg(a',b') = \frac{1}{N} \sum_{i}^{N} {a}'_{i} {b}'_{i} = <a'b'>

For all practical purposes, this equation is exactly the same as the previous one and the terms a' and b' are mathematically equivalent to α and β respectively. What this shows is that the physical assumptions about existence of hidden variables, locality etc are not necessary to obtain an expression for the expectation values for a pair product.
As I said, you are not really computing an expectation value but just an average, which in the limit as the number N of iterations went to infinity would approach the true expectation value with probability 1.
We have obtained the same thing just by defining two variables a', b' with values (+1 and -1) and calculating the expectation value for the paired product of a list of pairs of these variables. You could say the reason Bell obtained the same same expression is because he just happened to be dealing with two functions which can have values (+1 and -1) for physical reasons and experiments producing a list of such pairs. And he just happened to be interested in the pair product of those functions for physical reasons. But the structure of the calculation of the expectation value is determined entirely by the mathematics and not the physics. Once you have two variables with values (+1 and -1) and a list of pairs of such values, the above equations should arise no matter the process producing the values, whether physical, mystical, non-local, spooky, super-luminal, or anything you can dream about. That is why I say the physical assumptions are peripheral.
Physical assumptions are peripheral to calculating averages from experimental data, it's true, and they're also peripheral to writing down expectation values in terms of the "true" probabilities as I did when I wrote E(R) = \sum_{i=1}^N R_i * P(R_i), with the following equation as a special case of this general form:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...but you can't derive useful inequalities like 1 + E(b,c) >= |E(a,b) - E(a,c)| from such simple definitions! For that you need to make some physical assumptions which allow you to show that the "true" expectation values can also be written in some more specific form, such as:

E(a,b) = - \sum_{i=1}^N A(a,\lambda_i)*A(b,\lambda_i)*P(\lambda_i)
E(b,c) = - \sum_{i=1}^N A(b,\lambda_i)*A(c,\lambda_i)*P(\lambda_i)
E(a,c) = - \sum_{i=1}^N A(a,\lambda_i)*A(c,\lambda_i)*P(\lambda_i)

...and then it's from these more specific forms that you derive the inequalities.
Note a few things about the above equation. a'_i and b'_i must be multiplied with each other. If we independently reorder the columns in our list so that we have different pairings of a'_i and b'_i, we will obtain the same expectation value only in the most improbable of situations. To see this, consider the simple list below

a' b'
+ -
- +
- +
+ -

<a'b'> = -1/4

If we rearrange the b' column so that the pairing is no longer the same, we may have something like the following were we have the same number of +'s and -'s but their pairing is different:

a' b'
+ +
- -
- -
+ +

<a'b'> = 1/4
Which tells us that we are dealing with an entirely different dataset.
OK, sure, if you are allowed to resort pairs at will you can get different averages for the products of pairs. But in Bell's theorem it's assumed that all the "products of two measurement results" are each from pairs of measurements on a single pair of entangled particles, you're not allowed to resort the data in this way.

JesseM

Aug7-10, 10:47 PM

(continued from the last post)

So far we have dealt with pairs, just like Bell up to his equation (14). Let us then, following in Bell's footsteps introduce the third variable (see page 406 of his original paper).
It follows that c is another unit vector
E(a,b) - E(a,c) = -\int d\lambda \rho (\lambda )[A(a,\lambda )A(b,\lambda )-A(a,\lambda )A(c,\lambda )]
using (1), whence
\left | E(a,b)-E(a,c) \right |\leq \int d\lambda \rho [1 - A(b,\lambda)A(c,\lambda )]
The second term on the right is E(b,c), whence
1 + E(b,c) >= |E(a,b) - E(a,c)| ... (15)
Note a few things here: Bell factorizes at will within the integral. ρ(λ) is a factor of every term under the integral. That is why I explained in my previous detailed post that ρ(λ) must be the same for all three terms.
And I explained in #1213 that it doesn't make any sense to use these equations as the reason why ρ(λ) should be the same in all three terms, since the equations he writes down for E(a,b) and E(b,c) and E(a,c) are not meant to be definitions of the expectation values, but rather conclusions about how the expectation values can be written down in a universe that obeys local realist laws along with the no-conspiracy assumption. See everything in post #1213 starting with the paragraph that begins "I don't understand how you can say..."

Anyway, if we accept Bell's physical argument that in a local realist universe we should be able to write the expectation values as follows:

E(a,b) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(b,\lambda )
E(a,c) = -\int d\lambda\rho (\lambda )A(a,\lambda )A(c,\lambda )
E(b,c) = -\int d\lambda\rho (\lambda )A(b,\lambda )A(c,\lambda )

...then we can see why the factorization he does in the equations you wrote above should be justified. But he does need to make that physical argument to justify it.

Also, there is some ambiguity in what you mean when you say "ρ(λ) must be the same for all three terms", I discussed this at the start of post #1214. I was interpreting it just as a statement that the "true" or "objective" probability distributions on different values of λ (which would give the frequencies of different values of λ that would be expected in the limit as the number of trials went to infinity) should not depend on the detector settings. If you mean something different, like that the actual finite run of trials on each detector setting should involve the same frequencies of different values of λ, then I disagree that Bell's equation implies anything of the sort since it only deals with "true" probabilities and not empirical results, but again see post #1214 for the detailed discussion on this point.
Secondly, Bell derives the expectation value term E(b,c) by factoring out the corresponding A(b,.) and A(c,.) terms from E(a,b) and E(a,c). Therefore, E(b,c) does not contain different A(b,.) and A(c,.) terms but the exact same ones present in E(a,b) and E(a,c).
I don't know why you have replaced terms like A(b,λ) with notation like A(b,.)--easier to type, or some deeper significance? Anyway, Bell is assuming that for any given value of λi, A(a,λi) is the same regardless of whether the other detector was on setting b or setting c, and so forth for A(b,λi) and A(c,λi). In other words, the result at a given detector depends only on that detector's setting and the value of all hidden variables on that trial, it doesn't depend on the other detector's setting (and we wouldn't expect it to in a local realist universe!) Is this all you're saying, or do you think the factorization has some further implications?
In other words, in order to obtain all three expectation values E(a,b), E(a,c) and E(b,c), we ONLY need three lists of outcomes corresponding to A(a,.), A(b,.), A(c,.) or in simpler notation, we only need a single list of triples [(a',b',c')] to calculate all terms for

1 + <b'c'> >= |<a'b'> - <a'c'>|
No, again it seems like you are confusing theoretical terms with empirical results. E(a,b) doesn't depend on what results we got on any finite series of trials, it's the "true" expectation value that can be defined as

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

Where each of the P's represents the "true" or "objective" probability for that pair of results, as distinguished from the fraction of some finite number of trials where that pair of results was seen (as always, in frequentist terms the objective probabilities would be the fraction of trials with that pair of results in the limit as the number of trials goes to infinity).
So then, we are destined to obtain this inequality for any list of triples of two valued variables (or outcomes of two-valued functions) were the allowed values are (+1 or -1), no matter the physical, metaphysical or mystical situation generating the triples.
But that's not the situation with Bell's theorem. Rather, with Bell's theorem we have three runs with different combinations of detector settings (a,b), (b,c) and (a,c), and considering the average from each run. Bell is showing that if we know the true expectation values for each individual run, in a local realist universe they should obey:

1 + E(b,c) >= |E(a,b) - E(a,c)|

Since each expectation value is for a different run, even if you assume that every iteration of every run is determined by a set of triples, you can't derive the above equation from arithmetic alone since each expectation value would deal with a different collection of triples. So, you do need to consider the "physical, metaphysical or mystical situation generating the triples". And once you are convinced that the above equation should hold for the true expectation values, then by the law of large numbers you can conclude that if you do 1000 trials on each run, in a local realist universe you are astronomically unlikely to see a violation of the following inequality on your data:

1 + (average for product of results on the run with settings b and c) >=
|(average for product of results on the run with settings a and b) -
(average for product of results on the run with settings a and c)|

Suppose now that we generate from our list of triples, three lists of pairs corresponding to [(a',b')], [(a',c')] and [(b',c')], we can simply calculate our averages and be done with it. It doesn't matter if the order of pairs in the lists are randomized so long as the pairs are kept together. In this case, we can still sort them as described in my previous detailed description, to regenerate our list of triples from the three lists of pairs.
See my questions and arguments about your "resorting" procedure in post #1215. First I clarified what I thought you meant by this form of "resorting" at the start of the post with a simple example, perhaps you can tell me if I've got it right or not. If I have got it right, then please address my subsequent comments and questions:
If so, I don't see how this ensures that "ρ(λi) is the same for all three terms of the inequality", or what you even mean by that. For example, isn't it possible that if the number of possible values of λ is 1000, then even though iteration #1 of the first run has been grouped in the same row as iteration #3 of the second run and iteration #2 of the third run (according to their original labels), that doesn't mean the value of λ was the same for each of these three iterations? For example, might it not have been the case that iteration #1 of the first run had λ203, iteration #3 of the second run had λ769, and iteration #2 of the third run had λ488?

As a separate issue it is of course true that if your full set of data can be resorted in this way, that's enough to guarantee mathematically that the data will obey Bell's inequality. But this is a very special case, I think it would be fairly unlikely that the full set of iterations from each run could be resorted such that every row would have the same value of a,b,c throughout, even if the data was obtained in a local realist universe that obeyed Bell's theoretical assumptions, and even if the overall averages from each run actually did obey the Bell inequality.
Now the way Bell-test experiments are usually done, is analogous to collecting three lists of pairs randomly with the assumption that these three lists are representative of the three lists of pairs which we would have obtain from a list of triple, had we been able to measure at three angles simultaneously.
Yes, that's true. Since there are only eight possible distinct triples, and the value of λ on each trial completely determines the type of triple on that trial, and we assume the true probability distribution P(λ) is the same regardless of the detector settings, then with some reasonably large number of trials (say 1000) on each run we do expect that:

Fraction of trials on first run where the hidden triple was a=+1, b=-1 and c=+1

is very close to

Fraction of trials on second run where the hidden triple was a=+1, b=-1 and c=+1

and to

Fraction of trials on third run where the hidden triple was a=+1, b=-1 and c=+1

And likewise for the fractions of the other seven types of triples that occurred on each run. Do you agree this is a reasonable expectation thanks to the law of large numbers?
And if each list was sufficiently long, the averages will be close to those of the ideal situation assumed by Bell. Again, remember that within each list of pairs actually measured, the individual pairs such as (a',b')_i measured together are assumed to have originated from a specific theoretical triple, (a',c')_j from another triple, and (b',c')_k from another triple. Therefore, our dataset from a real experiment is analogous to our three theoretical lists above, where we randomized the order but kept the pairs together while randomizing. Which means, it should be possible to regenerate our single list of triples simply by resorting the three lists of pairs while keeping the individual pairs together, as I explained previously.
Even if the data was drawn from triples, and the probability of different trials didn't depend on the detector settings on each run, there's no guarantee you'd be able to exactly resort the data in the manner of my example in post #1215, where we were able to resort the data so that every row (consisting of three pairs from three runs) had the same value of a,b,c throughout. You might be able to sort it so that most rows of three pairs had the same value of a,b,c throughout, but probably not all. This would at least give a way of roughly estimating the frequencies of different types of triples, though.
If we can not do this, it means either that:
a) our data is most likely of the second kind in which randomization did not keep the pairs together or
Well, we know this does not apply in Bell tests, where every data pair is always from a single trial with a single pair of measurements on a single pair of entangled particles.
b) each list of pairs resulted from different lists of triples and/or
If the frequencies of each of the 8 types of triples differed significantly in three runs with a significant (say, 1000 or more) number of trials in each, this would imply either an astronomically unlikely statistical miracle or it would imply that the no-conspiracy assumption is false and that the true probabilities of different triples actually does change depending on the detector settings.
c) our lists of pairs are not representative of the list of triples from which they arose
Not sure I follow what you mean here. Are you suggesting that even if we had a triple like a=+1, b=-1, c=+1 we might still get result -1 with detector setting a? If so what would be the point of assuming the data arose from triples in the first place? Remember that Bell's assumption of predetermined results on each axis came from the fact that whenever both particles were measured on the same axis they always gave opposite results--in a local realist universe where the decisions about the two detector settings can have a spacelike separation, it seems impossible to explain this result otherwise (though some of Bell's later proofs dropped the assumption of always getting opposite or identical results when both experimenters used the same setting).
In any of these cases, Bell's inequality does not and can not apply to the data. In other words, it is simply a mathematical error to use the inequality in such situations.
No, the fact that Bell's inequality is observed not to work is empirical evidence that one of the assumptions used in the derivation must be false, like the assumption that local realism is true (with the conclusion of predetermined triples following from this assumption along with the observation that using the same angle always yields opposite results), or the no-conspiracy assumption. Unless you want to argue (and you probably do) that even if we assume the validity of those theoretical assumptions, this does not necessarily imply Bell's inequality should hold for the type of experiment he describes.
Also note that these represent the only scenarios in which "average value of a*b for all triples" is different from "average value of a*b for measured pairs only". And in this case, the fair sampling assumption can not hold.
What do you mean by "fair sampling assumption"? This page (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Detection_effic iency_loophole_and_the_fair_sampling_assumption) says "It states that the sample of detected pairs is representative of the pairs emitted", but that could be true and Bell's inequality could still fail for some other reason like a violation of the no-conspiracy assumption.

JesseM

Aug7-10, 10:51 PM

The points made in your recent posts have already been pre-empted and rebutted in my posts
#1211 and #1212 so consider those as responses. You probably did not see them before developing your recent responses. If there are any points you still contest after reading those two posts, please indicate and I will re-explain in yet simpler terms.
Having replied to these, I saw nothing in them that could be considered a rebuttal of any of the points I made in #1213-#1215. I indicated in my replies to #1211 and #1212 where I thought various claims made in those posts had been disputed or questioned in #1213-#1215, so if you disagree with some of the things I say in my recent replies you can go back and address the corresponding arguments/questions in the earlier posts.

billschnieder

Aug8-10, 10:20 AM

Now let us go to Bell's equation (2) where he defines his expection values ...

Perhaps I am over-interpreting your use of the word "defines", but as I argued towards the end of post #1213 (starting with the paragraph that begins 'I don't understand how you can say...'), this paragraph cannot be taken as the definition of E(a,b), rather E(a,b) is understood to be defined in a physical way as the expectation value for the product of two measurements on an entangled particle pair with detector settings a and b.

You are grasping at straws here. First of all, I said the equation is Bell's definition of HIS expectation values for the situation he is working with.
Secondly, nobody said anything about the probabilities in the equation not being true probabilities, so you are complaining about an inexistent issue. Thirdly, you object to my statement but go on to say the exact same thing. This is what I said after the equation:

Note, what Bell is doing here is calculating the weighted average of the product A(a,λ)*B(b,λ) for all λ. Which is essentially the expectation value. Theoretically the above makes sense, where you measure each A(a,.), B(b,.) pair exactly once for a specific λ, and simply multiply with the probability of realizing that specific λ and then add up subsequent ones to get your expectation value E(a,b). But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities.

And this is how it is described on Wikipedia:

http://en.wikipedia.org/wiki/Expected_value
In probability theory and statistics, the expected value (or expectation value, or mathematical expectation, or mean, or first moment) of a random variable is the integral of the random variable with respect to its probability measure.

For discrete random variables this is equivalent to the probability-weighted sum of the possible values.

For continuous random variables with a density function it is the probability density-weighted integral of the possible values.

The term "expected value" can be misleading. It must not be confused with the "most probable value." The expected value is in general not a typical value that the random variable can take on. It is often helpful to interpret the expected value of a random variable as the long-run average value of the variable over many independent repetitions of an experiment.

The expected value may be intuitively understood by the law of large numbers: The expected value, when it exists, is almost surely the limit of the sample mean as sample size grows to infinity.

So when you say:

This expectation value is understood as a sum of the different possible measurement outcomes weighted by their "true" probabilities:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...

The comment above is completely misguided, since the basic definition of "expectation value" in this experiment has nothing at all to do with knowing the value of λ, it is just understood to be:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

It clearly shows that you do not understand probability or statistics. Clearly the definition of expectation value is based on probability weighted sum, and law of large numbers is used as an approximation, that is why it says in the last sentence above that the expectation values is "almost surely the limit of the sample mean as the sample size grows to infinity"

You are trying to restrict the definition by suggesting that expection value is defined ONLY over the possible paired outcomes (++, --, +-, -+) and not possible λ's, but that is naive, and short-sighted but also ridiculous as we will see shortly. Now let us go back to the first sentence of the wikipedia definition above and notice the last two words "probability measure". In case you do not know what that means, a probability meaure is simply any real valued function which assigns 1 to the entire probablity space and maps events into the range from 0 to 1. An expectation value can be defined over any such probabiliy measure, not just the one you pick and choose for argumentation purposes. In Bell's equation (2),
\int d\lambda \rho (\lambda ) = 1
Therefore ρ(λ) is a probability measure over the paired products A(a,λ)A(b,λ) and Bell's equation (2) IS defining an expectation value for paired products irrespective of any physical assumptions. There is no escape for you here.

billschnieder

Aug8-10, 10:23 AM

If you disagree with any of the above, please go back and address my specific arguments in posts #1213-1215

Of course I disagree with a lot of it, for reasons I have already explained in above, I do not see the need to respond specifically. Anyone following the discussion will immediately recognize this fact. For example, you argued earlier that there was a difference between "average value of b*c for all measurements" and "average value of b*c for all triples" with the former one being the one applicable to Bell's inequality:

Here you seem to be talking about conditions under which an inequality like this:

|(average value of a*b for all triples in which experimenter measured a and b) + (average value of a*c for all triples in which experimenter measured a and c)| - (average value of b*c for all triples in which experimenter measures b and c) <= 1

...can be derived. This is an entirely separate issue from the other point I was arguing, which was just the idea that the above inequality is not guaranteed to hold in spite of the fact that its arithmetical analogue is guaranteed:

|(average value of a*b for all triples) + (average value of a*c for all triples)| - (average value of b*c for all triples) <= 1

Anyway, if you agree that these types of inequalities are conceptually separate, that Bell's inequality was of the top type, and that a proof of the bottom one doesn't constitute a proof of the top

You continued to object despite my argument that as far as Bell's inequality is concerned, the two are equivalent. But now as your argument morphs to try and avoid the trap which requires ρ(λ) to be the same between terms, you are now claiming that the two are really really the same with a probability close to 1, because of the law of large numbers.

Then by the law of large numbers, you can show that the likelihood of a significant difference between the "true" expectation value E(b,c) and the experimental average (average for product of two results on all trials where detectors were set to b and c) becomes tiny as the number of trials becomes reasonably large (say, 1000), regardless of whether the ideal probability distribution ρ(λi) is very different
There is no escape for you here either.

All they can do is assume that by measuring a large number of points, their data will be as representative as illustrated above.
They assume the averages from their data are close to the "true" expectation values E(a,b), E(b,c) and E(a,c), which can be justified by the law of large numbers, but there is no need to assume that the (unknown) frequencies of different values of λi which occurred in the particle pairs they sampled was anything like the "true" probability distribution p(λi). Do you disagree?
Yes I disagree. Again here you are grasping at straws. The law of large number is only able to approximate the true expectation value, precisely because ρ(λi) for the ver large sample will almost always not be significantly different from the true probability distribution. If it differs significantly, the law of large numbers will definitely not produce the true expectation value. Just by measuring an extremely large number does not guarantee a representative sample.

So by assuming a that the expectation values are the same for a very large number of measurements, they are in effect also assuming that the probability distribution ρ(λi) in the sample is representative of the true distribution. From these silly mistakes and your recent discussion with RUTA in another thread, I am convinced that you do not understand probability and statistics. Unless you really understand it but are just trying to obfuscate.

E(a,b)= \frac{1}{N} \sum_{i}^{N}A(a,\lambda _i)B(b,\lambda _i)

How is it equivalent? It's quite possible that P(λ2) could be very different from P(λ3), for example, in which case you need to weigh the terms A(a,λ2)*B(b,λ2) and A(a,λ3)*B(b,λ3) by the probabilities of those values if you want to get an accurate expectation value. The correct discrete version would have to look like this
E(a,b)= \frac{1}{N} \sum_{i}^{N}A(a,\lambda _i)*B(b,\lambda _i)*P(\lambda _i)

You were not following when I explained earlier the following:

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities. Practically, this is the only way available to obtain expectation values, since no experimenter has any idea what the λ's are or how many of them there are. All they can do is assume that by measuring a large number of points, their data will be as representative as illustrated above.(This is the fair sampling assumption which is however not the focus of this post.) So then in this case, assuming discrete λ's, that Bell's equation (2) is equivalent to the following simple average

So your objection above is short-sighted because practically in any experiment P(λ) can not be known so the expectation value can not be calculated using P(λ), but can be calculated as a simple average from a large number of samples which is representative in the sense that the relative frequencies of realizing specific λ's are not significantly different from the true probability of the specific λ's. So your "correction" above is wrong because, you failed to understand the part where I explained that the realizations of the λ's is not unique. In other words, each specific λ, occurs multiple times with the relative frequency corresponding to it's probability.

Still, it's important to distinguish theoretical from empirical, so let's use E(a,b) to be the "true" expectation value for the product of the measurements with settings a and b, and Avg(a,b) to be the empirical average of all the products of measurement results on a run with settings a and b, and then we can say that in the limit as the number of trials/iterations in a run goes to infinity, Avg(a,b) should approach E(a,b) with probability 1.
That is an completely artificial distinction. Bell is calculating expectation values, and the only time when a simple average can be substituted for the expectation value is when it is calculated over a representative/fair sample. So your insistence on relabelling the term is just grasping at straws. If you insist on pursuing this ridiculous idea, I ask that you write down the expression for the expectation value for the following example:

You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product. Once you have done that, try and swindle your way out of the fact that
a) The structure of the expression so derived does not depend on the actual value N. ie, N could be 5, 100, or infinity.
b) The expression so derived is a theoretical expression not "empirical".
c) The expression so derived is the same as the simple average of the paired products.

Again this doesn't work as a theoretical expectation value since i refers to some number of iterations, whereas a theoretical expectation value for an experiment which can give any one of N results R1, R2, ..., RN
Again this is not a serious objection because any serious person would not suggest that because we used i as the iterator in one equation means it must have the exact same meaning in a different equation. I already explained and you understood, that in the first case where we were doing a weighted average over λ's, i was iterating over each λ, with each specific λ occurring exactly once. In the second case which is a simple average, i is iterating over each case instance in a representative sample with the understanding that a specific λ will occur multiple times with the relative frequency corresponding to it's probability. Where the actual value of N does not matter so long as the relative frequencies of ALL λ's in our theoretical list is representative of the "true" probability distribution. The two expressions so calculated are exactly equivalent and both are expectation values. So there is no genuine objection here, and no way to escape either.

billschnieder

Aug8-10, 10:43 AM

...but you can't derive useful inequalities like 1 + E(b,c) >= |E(a,b) - E(a,c)| from such simple definitions! For that you need to make some physical assumptions

This is what your entire argument boils down to. You are still struggling to suggest that physical assumptions are needed to derive Bell's inequality. But as I have explained, all you need are the following purely mathematical requirements:

1) a theoretical list of triples (a,b,c) of two-valued variables restricted in value to +/-1
2) Expressions of the expectation value of cyclical paired-products extracted from the list of triples E(a*b), E(a*c) and E(b*c), which I have shown convincingly to be equivalent to <ab>, <ac> and <bc> respectively.

That is all needed. I have shown that the expression for the expectation values E(a,b) is similar to Bell's. I will now show using notation analogous to that at the top of page 406 of Bell's paper that that the above necessarily lead to the inequalities obtained by Bell, without any physical assumptions. Note that despite your claims, you haven't actually pointed to any point in the derivation in which a physical assumption is required.

<a'b'> - <a'c'> = - \frac{1}{N}\sum_{i}^{N}({a}'_i{b}'_i - {a}'_i{c}'_i)
since b' = 1/b' (from b' = +/-1) it follows that
= \frac{1}{N}\sum_{i}^{N}{a}'_i{b}'_i(\frac{c'_i}{b' _i}-1)
and since a'b' = +/-1 it follows that the RHS is maximum when a'b'=1, therefore:
|<a'b'> - <a'c'>| \leq \frac{1}{N}\sum_{i}^{N}(1 - {b}'_i{c}'_i)
|<a'b'> - <a'c'>| + <b'c'> \leq 1
Note, and you can replace a' with -a' or b' with -b' or c' with -c' in the above and get the full family of Bell's original inequalities.

The above mirrors exactly what Bell did at the top of page 406! Now if you continue to argue that there is a physical assumption hidden in there, please show me using Bell's derivation of page 406 AND show above where you think I sneaked in a physical assumption in order to obtain the same expression. Note also, if you do not understand the above derivation, it means you clearly do not understand Bell's derivation at top of page 406

And I explained in #1213 that it doesn't make any sense to use these equations as the reason why ρ(λ) should be the same in all three terms.

Any serious person following Bell's derivation would have noticed that the integral on the right hand side of the first equation on page 406 is obtained by subtracting two different integrals for E(a,b) and E(a,c) and joining the integral signs into a single integral over λ. In mathematics, this is normally understood by any serious student worthy of a pass grade to mean that E(a,b) and E(a,c) are defined over the same distribution of λ. Also, on the third expression (1st inequality) on page 406 where Bell factors out and recombines the A(b,λ) originally from the E(a,b) term and the A(c,λ) originally from the E(a,b) to generate a new A(c,λ)(b,λ) term all under the same integral over λ, and subsequently separates the RHS into two integrals over the same λ, with the first part yielding 1 and the othe yielding the E(b,c) term. Any person seriously trying to understand my argument rather than just quibble, would understand that the requirement for ρ(λ) to be the same between all the terms is inherent in the derivation. Duh! No doubt you do not yet recognize that your so-called objections were rebutted by Bell himself, even before you thought about them. Sorry no escape here either.

In other words, in order to obtain all three expectation values E(a,b), E(a,c) and E(b,c), we ONLY need three lists of outcomes corresponding to A(a,.), A(b,.), A(c,.) or in simpler notation, we only need a single list of triples [(a',b',c')] to calculate all terms for

1 + <b'c'> >= |<a'b'> - <a'c'>|

No, again it seems like you are confusing theoretical terms with empirical results.
...
But that's not the situation with Bell's theorem. Rather, with Bell's theorem we have three runs with different combinations of detector settings (a,b), (b,c) and (a,c), and considering the average from each run. Bell is showing that if we know the true expectation values for each individual run, in a local realist universe they should obey:

1 + E(b,c) >= |E(a,b) - E(a,c)|

Since each expectation value is for a different run, even if you assume that every iteration of every run is determined by a set of triples, you can't derive the above equation from arithmetic alone since each expectation value would deal with a different collection of triples.

You do not understand Bell's work. Look again at page 406 and tell me how many distinct A(.,λ) type functions do you see. I can identify only three A(a,λ), A(b,λ), A(c,λ), not 6, which is what you are claiming Bell used in his derivation. The 3 expectation values E(a,b), E(a,c) and E(b,c) are merely cyclical combinations of these same terms. So you are off base here. There is no justification in Bell's work for suggesting that Bell is dealing with three 6 separate terms corresponding to three separate runs. You have provided no proof, either mathematical or logical to justify the ridiculous idea that Bell's inequality is derived from 6 separate terms rather than just 3.

However, as I have been pointing out to you over and over, the reason we can not guarantee that an actual experiment will obey Bell's inequality is due to the fact that actual experiments measure 6 different terms while Bell's derivation mandates the use of only 3. So at least here you seem to be seeing the light, only backwards.

billschnieder

Aug8-10, 10:45 AM

See my questions and arguments about your "resorting" procedure in post #1215. First I clarified what I thought you meant by this form of "resorting" at the start of the post with a simple example, perhaps you can tell me if I've got it right or not. If I have got it right, then please address my subsequent comments and questions
Yes you claimed to have "clarified" what I mean by resorting, even though I had explained with a detailed example back in post #1187 what I meant. In any case you say:

I'm not sure I follow what you mean here. Suppose we do only 4 iterations with each pair of different detector settings, and get these results (with the understanding that notation like a=+1 means 'the result with detector set to angle a was +1):

For run with setting (a,b):
1. (a=+1, b=-1)
2. (a=-1, b=-1)
3. (a=-1, b=+1)
4. (a=+1, b=-1)

For run with setting (b,c):
1. (b=-1, c=+1)
2. (b=-1, c=-1)
3. (b=-1, c=+1)
4. (b=+1,c=-1)

For run with setting (a,c):
1. (a=+1, c=-1)
2. (a=+1, c=+1)
3. (a=-1, c=-1)
4. (a=-1, c=+1)

Then we can arrange these results into four rows of three iterations from three runs, such that in each row the value of a is the same for both iterations that sampled a, in each row the value of b is the same for both iterations that sampled b, and in each row the value of c is the same for both iterations that sampled c:

1. (a=+1, b=-1) 3. (b=-1, c=+1) 2. (a=+1, c=+1)
2. (a=-1, b=-1) 1. (b=-1, c=+1) 4. (a=-1, c=+1)
3. (a=-1, b=+1) 4. (b=+1,c=-1) 3. (a=-1, c=-1)
4. (a=+1, b=-1) 2. (b=-1, c=-1) 1. (a=+1, c=-1)

Let us call your three runs (runs 1, 2, 3) and calculate <ab>, <ac> and <bc> from each one.
<a1b1> = -1/4
<a2c2> = -1/4
<b3c3> = 0

Now looking at your resorted list with 6 columns: a1, b1, a2, c2, b3, c3, we can verify that
<a1b1> = <a1b3> = <a2b3> = <a2b1> = -1/4
and
<a2c2> = <a1c2> = <a2c3> = <a1c3> = -1/4
and
<b3c3> = <b1c3> = <b1c2> = <b3c2> = 0

The reason this holds is because after resorting, we see that all the a columns are identical, just like the b and c. So your dataset of 6 columns is in fact just a dataset of 3 columns with each column repeated once. If a dataset cannot be sorted like you did above, all those terms are not guaranteed to be the same. And if they are not the same, Bell's inequality can not be applied to the dataset.

If so, I don't see how this ensures that "ρ(λi) is the same for all three terms of the inequality", or what you even mean by that. For example, isn't it possible that if the number of possible values of λ is 1000, then even though iteration #1 of the first run has been grouped in the same row as iteration #3 of the second run and iteration #2 of the third run (according to their original labels), that doesn't mean the value of λ was the same for each of these three iterations?

Please, pay attention for once: Every pair of outcomes at those angles is deterministically determined by the specific λ being realized for that iteration. So if for example we had only 5 possible λ's (λ1, λ2, λ3, λ4, λ5), the only possible outcomes are (++, +-, -+, --) which means some of the λ's must result in the same outcome. If say λ5 and λ3 each result in the same outcome (++) deterministically, and each of them was realized in the experiment exactly once, when you resort it, it doesn't matter whether the (++) at the top of the resorted list corresponds to λ5 or λ3 for the following reasons. If in your large number of iterations, λ5 and λ3 are fairly represented, you will still have the right number of (++)'s for both λ5 and λ3 and it doesn't matter if the specific (++) you got at the top is a λ5 ++ or a λ3 ++. Also, if for the three angles under consideration a,b,c a number of λ's deterministically resulted in the same outcomes for (a,b), (b,c) and (a,c) those lambdas are effectively equivalent as far as the experiment is concerned and you could combine them, updating the combined P(λ) appropriately. Finally as clearly explained in my posts #1211 and #1212, being able to sort the data is a test to see if the data meets the mathematical consistency required by Bell's derivation, in which the (b,c) term is derived by factoring out the b from the (a,b) term and factoring out the c from the (a,c) term and multiplying them together. Such factorization imposes a consistency requirement that unless you can do that, the inequality can not be derived and any data which can not be factored likewise, is mathematically incompatible with the inequality.

Even if the data was drawn from triples, and the probability of different trials didn't depend on the detector settings on each run, there's no guarantee you'd be able to exactly resort the data in the manner of my example in post #1215, where we were able to resort the data so that every row (consisting of three pairs from three runs) had the same value of a,b,c throughout

That is why I cautioned you earlier not to prematurely blurb your claim that conspiracy must be involved for ρ(λi) to be different. Now we get an admission, however reluctantly that it is possible for ρ(λi) to be different without conspiracy. You see, the less you talk (write), the less you will have to recant later as I'm sure you are realizing.

billschnieder

Aug8-10, 10:46 AM

If the frequencies of each of the 8 types of triples differed significantly in three runs with a significant (say, 1000 or more) number of trials in each, this would imply either an astronomically unlikely statistical miracle or it would imply that the no-conspiracy assumption is false and that the true probabilities of different triples actually does change depending on the detector settings.
First I would like for you to explain from where you pulled the 1000 number. What rule of mathematics, statistics, or any other field of science enabled you to suggest that 1000 or more was a significantly large number of trials???????
Secondly I already explained to you in my response to your Scratch lotto example that, all you need to violate that requirement is for the probability of detection to vary with angle. In other words, a biased sample will do that without any conspiracy. Since the rest of the arguments above have failed, I will predict that you will hang on this one and try to change the discussion to one about scratch lotto cards. Let's wait and see ...

Not sure I follow what you mean here. Are you suggesting that even if we had a triple like a=+1, b=-1, c=+1 we might still get result -1 with detector setting a?
Why would you choose the most improbable of meanings. I mean that the list of pairs is not representative of the list of triples. Which clearly means that the relative frequency of each specific pair in the list of pairs is not the same as the relative frequency of the same pair in the list of triples.

In any of these cases, Bell's inequality does not and can not apply to the data. In other words, it is simply a mathematical error to use the inequality in such situations.
No, the fact that Bell's inequality is observed not to work is empirical evidence that one of the assumptions used in the derivation must be false, like the assumption that local realism is true
Hehe, you are again grasping at straws here, trying to sneak in a physical assumption. I have just exhaustively and conclusively explained to you that the requirement to be able to sort the data, and for ρ(λi) to be the same accross the three terms is a mathematical requirement of Bell's derivation. In other words, Bell could not have been able to derive his inequalities if these were false. I have also pointed out and you agreed that in any real experiment, these mathematical requirements are not guaranteed to be obeyed. So contrary to your claim that the reason experiments violate Bell's inequality is due to failure of some other physical assumption which you haven't demonstrated to be material for deriving the inequality, the real reason is failure to meet the mathematical conditions that must apply for the inequality to apply to the data.

If we can not do this, it means either that:
a) our data is most likely of the second kind in which randomization did not keep the pairs together or

Well, we know this does not apply in Bell tests, where every data pair is always from a single trial with a single pair of measurements on a single pair of entangled particles.

You do not understand Bell test experiments then. Contrary to your claims, it applies because experimenters are not always sure which particle on one arm corresponds to which particle on the other arm. Have you ever heard of the coincidence time window?

Also note that these represent the only scenarios in which "average value of a*b for all triples" is different from "average value of a*b for measured pairs only". And in this case, the fair sampling assumption can not hold

What do you mean by "fair sampling assumption"? This page says "It states that the sample of detected pairs is representative of the pairs emitted", but that could be true and Bell's inequality could still fail for some other reason like a violation of the no-conspiracy assumption.
Another objection for objection sake. You object but then present a definition which is essentially what I have given.

c) our lists of pairs are not representative of the list of triples from which they arose

If you see a difference, illustrate it.

Having replied to these, I saw nothing in them that could be considered a rebuttal of any of the points I made in #1213-#1215. I indicated in my replies to #1211 and #1212 where I thought various claims made in those posts had been disputed or questioned in #1213-#1215, so if you disagree with some of the things I say in my recent replies you can go back and address the corresponding arguments/questions in the earlier posts.
All I saw was quibbling, unsubstantiated claims and nothing substantive as I have illustrated in the last few posts.

JesseM

Aug8-10, 12:25 PM

First of all, I said the equation is Bell's definition of HIS expectation values for the situation he is working with.
But then you use that to come to the absurd conclusion that in order to compare with empirical data, we need to make some assumptions about the distribution of values of λ on our three runs. We don't--Bell was writing for an audience of physicists, who would understand that whenever you talk about an "expectation value", the basic definition is always just a sum over each possible measurement result times the probability of that result, so to compare with empirical measurements you just take the average result on all your trials, nothing more. Bell obviously did not mean for his integrals to be the definitions of E(a,b) and E(b,c) and E(a,c), implying that you can only compare them with empirical data if you have actually confirmed that \rho(\lambda) was the same for each run--rather he was making an argument that the "expectation values" as conventionally understood would also be equal to those integrals.
Secondly, nobody said anything about the probabilities in the equation not being true probabilities, so you are complaining about an inexistent issue.
You understand that the "true probabilities" represent the frequencies of different outcomes in the limit as the number of trials goes to infinity, and not the actual frequencies in our finite series of trials? So for example, if one run with settings (a,b) included three trials where λ took the value λ3, while another run with settings (b,c) included no trials where it took the value λ3, this wouldn't imply that ρ(λi) differed in the integrals for E(a,b) and E(b,c)? Because your comment at the end of post #1224 suggests you you are still confusing the issue of what it means for the "true probabilities" ρ(λi) to differ depending on the detector settings and what it means for the actual frequencies of different values of λi to differ on runs with different detector settings:
Even if the data was drawn from triples, and the probability of different trials didn't depend on the detector settings on each run, there's no guarantee you'd be able to exactly resort the data in the manner of my example in post #1215, where we were able to resort the data so that every row (consisting of three pairs from three runs) had the same value of a,b,c throughout
That is why I cautioned you earlier not to prematurely blurb your claim that conspiracy must be involved for ρ(λi) to be different. Now we get an admission, however reluctantly that it is possible for ρ(λi) to be different without conspiracy. You see, the less you talk (write), the less you will have to recant later as I'm sure you are realizing.
So, kinda seems like this is not actually a dead issue. You may have noticed I discussed exactly this distinction between the "true probability distribution" ρ(λi) differing from one run to another and the actual frequencies of different λi's differing from one run to another at the very start of post #1214, but since you didn't respond I don't know if you even read that or what you thought of the distinction I was making there.
Thirdly, you object to my statement but go on to say the exact same thing. This is what I said after the equation:
[quote]Theoretically the above makes sense, where you measure each A(a,.), B(b,.) pair exactly once for a specific λ, and simply multiply with the probability of realizing that specific λ and then add up subsequent ones to get your expectation value E(a,b). But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)
You really think that this is the "exact same thing" as what I was saying? Here your "practical" average requires us to know which value of λ occurred on each trial, and what the probability of each value was! Of course this is nothing like what I mean when I talk about comparing the theoretical expectation value to actual experimental data. Again, a definition of the expectation value involving "true probabilities" would be:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

So if you want to compare with empirical data on a run where the detector settings were a and b, it'd just be:

(+1*+1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result -1)

...which is equivalent to just computing the product of the two measurements on each trial, and adding them all together and dividing by the number of trials to get the empirical average for the product of the two measurements on all trials in the run.

You quote my simple equation for E(a,b) above and say:
It clearly shows that you do not understand probability or statistics. Clearly the definition of expectation value is based on probability weighted sum,
Which mine is--I'm multiplying each possible result by the probability of that result, for example the result (+1*-1) is multiplied by P(detector with setting a gets result +1, detector with setting b gets result -1)
and law of large numbers is used as an approximation, that is why it says in the last sentence above that the expectation values is "almost surely the limit of the sample mean as the sample size grows to infinity"
Of course. In the limit as the number of trials goes to infinity, we would expect this:

(+1*+1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result -1)

to approach this:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...where all the probabilities in the second expression represent the "true probabilities", i.e. the fraction of trials with that outcome in the limit as the number of trials goes to infinity!

So, it's not clear why you think the wikipedia definition of expectation value is somehow different from mine, or that I "do not understand probability or statistics". Perhaps you misunderstood something about my definition.
You are trying to restrict the definition by suggesting that expection value is defined ONLY over the possible paired outcomes (++, --, +-, -+) and not possible λ's, but that is naive, and short-sighted but also ridiculous as we will see shortly.
No, all expectation values are just defines as a sum over all possible results times the probability of each possible result. And in this experiment the value of λ is not a "result", the "result" on each trial is just +1 or -1.
Now let us go back to the first sentence of the wikipedia definition above and notice the last two words "probability measure". In case you do not know what that means, a probability meaure is simply any real valued function which assigns 1 to the entire probablity space and maps events into the range from 0 to 1. An expectation value can be defined over any such probabiliy measure, not just the one you pick and choose for argumentation purposes. In Bell's equation (2),
\int d\lambda \rho (\lambda ) = 1
Therefore ρ(λ) is a probability measure over the paired products A(a,λ)A(b,λ)
No, ρ(λ) is a probability measure over values of λ, and it happens to be true (according to Bell's physical assumptions) that the value of λ along with the detector angles completely determines the results on each trial. But you can also define a probability measure on the results themselves, that would just be a measure that assigns probabilities between 0 and 1 to each of the four possible results:

1. (detector with setting a gets result +1, detector with setting b gets result +1)
2. (detector with setting a gets result +1, detector with setting b gets result -1)
3. (detector with setting a gets result -1, detector with setting b gets result +1
4. (detector with setting a gets result -1, detector with setting b gets result -1)

With the sum of the four probabilities equalling one. That's exactly the sort of probability measure I was assuming when I wrote down my equation:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

And when trying to compare an equation involving expectation values to actual empirical results, every physicist would understand that you don't need to even consider the question of what values λ may have taken on your experimental runs, instead you'd just compute something like this:

(+1*+1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result -1)

...which, by the law of large numbers, is terrifically unlikely to differ significantly from the "true" expectation value if you have done a large number of trials. If you think a physicists comparing experimental data to Bell's inequality would actually have to draw any conclusions about the values of λ on the experimental trials, I guarantee you that your understanding is totally idiosyncratic and contrary to the understanding of all mainstream physicists who talk about testing Bell's inequality empirically.

If equation (2) was supposed to be the definition of the expectation value, rather than just an expression that he would expect the expectation value (under its 'normal' meaning, the one I've given above involving only actual measurable results and the probabilities of each result) to be equal to, then why do you think he would need to make physical arguments as to why equation (2) should be the correct form? Do you deny that he did make physical arguments for the form of equation (2), like in the first paper where he wrote:
[quote]Now we make the hypothesis, and it seems one at least worth considering, that if the two measurements are made at places remote from one another the orientation of one magnet does not influence the result obtained with the other. Since we can predict in advance the result of measuring any chosen component of \sigma_2, by previously measuring the same component of \sigma_1, it follows that the result of an such measurement must actually be predetermined. Since the initial quantum mechanical wave function does not determine the result of an individual measurement, this predetermination implies the possibility of a more complete specification of the state.

Let this more complete specification be effected by means of parameters λ ... the result A of measuring \sigma_1 \cdot a is then determined by a and λ, and the result B of measuring \sigma_2 \cdot b in the same instance is determined by b and λ
Do you disagree that here the first paragraph is providing physical justification for why A is a function only of a and λ but not b, and why B is a function of b and λ but not a, along with a justification for why we should believe the result A can be completely determined by a and the hidden parameters λ in the first place? Likewise, in the paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers), would you deny that this section from p. 16 of the pdf (p. 15 of the paper) is trying to provide physical justification for why the same function ρ(λ) appears in different integrals for different expectation values like E(a,b) and E(b,c)?
Secondly, it may be that it is not permissible to regard the experimental settings a and b in the analyzers as independent variables, as we did. We supposed them in particular to be independent of the supplementary variable λ, in that a and b could be changed without changing the probability distribution ρ(λ). Now even if we have arranged that a and b are generated by apparently random radioactive devices, housed in separate boxes and thickly shielded, or by Swiss national lottery machines, or by elaborate computer programmes, or by apparently free willed experimental physicists, or by some combination of all of these, we cannot be sure that a and b are not significantly influenced by the same factors λ that influence A and B. But this way of arranging quantum mechanical correlations would be even more mind boggling than one in which causal chains go faster than light. Apparently separate parts of the world would be deeply and conspiratorially entangled, and our apparent free will would be entangled with them.
If you don't disagree that these sections are attempts to provide physical justification for the form of the integrals he writes, why do you think he would feel the need to provide physical justification if he didn't have some independent meaning of "expectation values" in mind, like the meaning I talked about above involving just the different results and the probabilities of each one?

billschnieder

Aug8-10, 03:30 PM

You understand that the "true probabilities" represent the frequencies of different outcomes in the limit as the number of trials goes to infinity, and not the actual frequencies in our finite series of trials?

You do not understand probability either. Say I give you the following list of

++
--
-+
+-

And ask you to calculate P(++) from it. Clearly the probability is the number of times (++) occurs in the list divided by the number of entries in the list. The list does not have an infinite number of entries, there is no need to perform an infinite number of trials in order to deduce the probability. And even if you did perform a large number of trials, you will not get exactly the true probability which is 1/4. So your "law of large numbers" cop-out is an approximation of the true probability not it's definition. You need to learn some basic probability theory here because you are way off base.

But then you use that to come to the absurd conclusion that in order to compare with empirical data, we need to make some assumptions about the distribution of values of λ on our three runs. We don't--Bell was writing for an audience of physicists, who would understand that whenever you talk about an "expectation value", the basic definition is always just a sum over each possible measurement result times the probability of that result
Sorry JesseM but that bubble has already been burst, when I proved conclusively that you do not know the meaning of "expectation value". To show how silly this adventitious argument of yours is, I asked you a simple question and dare you to answer it:

You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product. Once you have done that, try and swindle your way out of the fact that
a) The structure of the expression so derived does not depend on the actual value N. ie, N could be 5, 100, or infinity.
b) The expression so derived is a theoretical expression not "empirical".
c) The expression so derived is the same as the simple average of the paired products.

So for example, if one run with settings (a,b) included three trials where λ took the value λ3, while another run with settings (b,c) included no trials where it took the value λ3, this wouldn't imply that ρ(λi) differed in the integrals for E(a,b) and E(b,c)? Because your comment at the end of post #1224 suggests you you are still confusing the issue of what it means for the "true probabilities" ρ(λi) to differ depending on the detector settings and what it means for the actual frequencies of different values of λi to differ on runs with different detector settings
You are sorely confused. Note I use ρ(λi) not P(λi) to signify that we are dealing with a probability distribution, which is essentially a function defined over the space of all λ, with integral over all λ equal to 1.

If the (a,b) run included N iterations with three of those corresponding to λ3, P(λ3) for our dataset = 3/N. But if in a different run of the experiment (b,c) none of the λ's was λ3, P(λ3) = 0 for our dataset. It therefore means the proability distribution of ρ(λi) can not be same for E(a,b) and E(b,c). If this is still too hard for you, let me simplify further.

According to Bell, E(a,b) calculated by the following sum

a1*b1*P(λ1) + a2*b2*P(λ2) + ... + an*bn*P(λn) where n is the total number of possible distinct lambdas. ρ(λ) is a function which maps a specific λi to its probability P(λi). By definition therefore, if the function ρ(λ) is the same for two runs of the experiment, it must produce the same P(λi) for both cases. In other words, if it produced different values of P(λi) such as 3/N in one case and 0 in another, it means ρ(λ) is necessarily different between the two and the runs can not be used together as a valid source of terms for comparing with Bell's inequality.

Note, what Bell is doing here is calculating the weighted average of the product A(a,λ)*B(b,λ) for all λ. Which is essentially the expectation value. Theoretically the above makes sense, where you measure each A(a,.), B(b,.) pair exactly once for a specific λ, and simply multiply with the probability of realizing that specific λ and then add up subsequent ones to get your expectation value E(a,b). But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities. Practically, this is the only way available to obtain expectation values, since no experimenter has any idea what the λ's are or how many of them there are.

You really think that this is the "exact same thing" as what I was saying? Here your "practical" average requires us to know which value of λ occurred on each trial
Oh come on! At least be honest about what you claim I am saying! Why would you need to know λ for each trial if you are calculating a simple average!? Go back and answer the example I requested for the expectation value for N pairs of real-valued numbers x and y and if you still do not understand how ridiculous this sounds, ask a gain and I will explain it using yet simpler terms assuming it is possible to simplify this any further.

billschnieder

Aug8-10, 03:32 PM

So if you want to compare with empirical data on a run where the detector settings were a and b, it'd just be:

(+1*+1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*(fraction of trials where detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*(fraction of trials where detector with setting a gets result -1, detector with setting b gets result -1)

...which is equivalent to just computing the product of the two measurements on each trial, and adding them all together and dividing by the number of trials to get the empirical average for the product of the two measurements on all trials in the run.

Despite your empty protests, you are still unable to show why the above will be different from a simple average <ab>. Oh wait, you actually agree with my statement that:

But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes

So yeah, you are saying the exact same thing after objecting to it!

So, it's not clear why you think the wikipedia definition of expectation value is somehow different from mine, or that I "do not understand probability or statistics"
It is different because your restricts expectation values to only the possible outcomes (++, --, +-, +-) even though expectation values are definied for any probability measure. ρ(λ) is a probability measure over all outcomes, therefore, Bell's equation (2) is a standard mathematical expression for an expectation value, contrary to your morphing claims.

No, all expectation values are just defines as a sum over all possible results times the probability of each possible result. And in this experiment the value of λ is not a "result", the "result" on each trial is just +1 or -1.
...
No, ρ(λ) is a probability measure over values of λ

Hehe, this is precisely an example of why I say you do not understand probability theory and statistics. In Bell's equation (2), the pair [A(a,λ)B(b,λ)] defines an event, the probability of the event [A(a,λ)B(b,λ)] occuring is P(λ), therefore ρ(λ) IS a probability measure over [A(a,λ)B(b,λ)] whether you like it or not. There are lots of references online. Find me one which says otherwise. No physical assumption is required to obtain this blatant mathematical definition.

But you can also define a probability measure on the results themselves, that would just be a measure that assigns probabilities between 0 and 1 to each of the four possible results:

1. (detector with setting a gets result +1, detector with setting b gets result +1)
2. (detector with setting a gets result +1, detector with setting b gets result -1)
3. (detector with setting a gets result -1, detector with setting b gets result +1
4. (detector with setting a gets result -1, detector with setting b gets result -1)

With the sum of the four probabilities equalling one. That's exactly the sort of probability measure I was assuming when I wrote down my equation:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

This is an admission that you were wrong to suggest that Bell's equation (2) is not a valid expectation value unless physical assumptions are also made. Nobody is arguing that there no other valid mathematical expressions for expectation value. You were the one arguing that mathematically defined expectation value must be the one you chose and not the one Bell chose. I'm happy you are now backtracking from that ridiculous position.

If you think a physicists comparing experimental data to Bell's inequality would actually have to draw any conclusions about the values of λ on the experimental trials, I guarantee you that your understanding is totally idiosyncratic and contrary to the understanding of all mainstream physicists who talk about testing Bell's inequality empirically.
Grasping at straws here to make it look like there is something I said which you object to. Note that you start the triumphant statement with an IF and then go ahead to hint that what you are condemning is actually something I think but you provide no quote of mine in which I said anything of the sort. I thought this kind of tactics was relagated to talk-show tv and political punditry.

billschnieder

Aug8-10, 03:33 PM

If equation (2) was supposed to be the definition of the expectation value, rather than just an expression that he would expect the expectation value (under its 'normal' meaning, the one I've given above involving only actual measurable results and the probabilities of each result) to be equal to, then why do you think he would need to make physical arguments as to why equation (2) should be the correct form? Do you deny that he did make physical arguments for the form of equation (2) ...
Duh! The whole point is that no physical assumptions are needed! This issue would be dead had you not argued vehemently that without extra physical assumptions, Bell's equation (2) will not be a standard mathematical expression for the expectation value of paired products.

You apparently did not see the following in my earlier post #1211:

You could say the reason Bell obtained the same same expression is because he just happened to be dealing with two functions which can have values (+1 and -1) for physical reasons and experiments producing a list of such pairs. And he just happened to be interested in the pair product of those functions for physical reasons. But the structure of the calculation of the expectation value is determined entirely by the mathematics and not the physics. Once you have two variables with values (+1 and -1) and a list of pairs of such values, the above equations should arise no matter the process producing the values, whether physical, mystical, non-local, spooky, super-luminal, or anything you can dream about. That is why I say the physical assumptions are peripheral.

So while it is true that Bell discussed the physical issues of local causality, those issues are peripheral as I have already explained.

If you don't disagree that these sections are attempts to provide physical justification for the form of the integrals he writes, why do you think he would feel the need to provide physical justification if he didn't have some independent meaning of "expectation values" in mind, like the meaning I talked about above involving just the different results and the probabilities of each one?

Because the meaning of the expression is clear from the expression Bell wrote himself. He is multiplying the paired product A(a,λ)A(b,λ) with their probability P(λ) and integrating over all λ. That is the mathematical definition of an expectation value. You are the one trying to impose on Bell's equation a meaning he did not intend as is evident from what he himself wrote in his original paper. You can't escape this one.

For example:

Let us define A(a,λ) = +/-1 , B(a,λ) just like Bell and say that the functions represent the outcome of two events on two stations one on earth (A) and another (B) on planet 63, and in our case λ represents non-local mystical processes which together with certain settings on the planets uniquely determine the outcome. We also allow in our spooky example for the setting a on earth to remotely affect the choice of b instantaneously and vice versa. Note in our example, there is no source producing any entangled particles, everything is happening instantaneously.

The expectation value for the paired product of the outcomes at the two stations is exactly the same as Bell's equation (2). If you disagree, explain why it would be different or admit that the physical assumptions are completely peripheral.

charlylebeaugosse

Aug8-10, 05:11 PM

EPR represents only conservation (in the line of the question:also in there issues that are quite different, e.g., "is QM a complete theory?"). For a classical pair, magnetic momentum (for instance) would be conserved along ANY but also along ALL directions. In QM, only one direction at once makes sense, so the spin projection is conserved along ANY direction but NOT ALONG ALL directions. Think of the Uncertainty Principle with reversed time, as proved in 1931 by Einstein, Tolman, and Podolsky. Bell's theorem assumes a form of realism not proven to make sense in the microcosm, at least for the type of coordinates we know (Einstein lie Schodinger thought that one should use other variables, but would have considered the hidden variables of Bell very naive). Assuming like Bell a form of naive microscopic realism that would let one make sense, e.g., of spin projections along at least 3 directions, John Bell proved an inequality already known by Boole in the late ninetieth century for macroscopic properties, but only realism counts there. The (nice) experiments supposed to "prove action at a distance" ONLY proved QM to be right, something that competent people did not doubt so much about anyway: they prove that realism and locality (absence of action at distance so to speak) cannot both hold true, but the only interesting question is to know whether realism (at least in the classical form, i.e., valid for all observables) holds true in the microcosm. A proof has just appeared in the European Journal of Physics to the effect that a Bell theorem holds true without assuming locality, en route to prove that (classical) realism is false, perhaps.

nismaratwork

Aug8-10, 05:20 PM

Bill, from reading the last two pages, this seems like a pretty straightforward example of you being mistaken, and JesseM being correct. Posting in bulk isn't changing this, or obscuring that fact in any way from those of us reading this this thread. I just thought you might want that reality check-in.

DevilsAvocado

Aug8-10, 05:40 PM

Posting in bulk isn't changing this

Yeah, and the extremely funny thing is that Bill are accusing others for writing too loooooooooong posts!? :surprised

(:biggrin:)

DevilsAvocado

Aug8-10, 05:43 PM

A proof has just appeared in the European Journal of Physics to the effect that a Bell theorem holds true without assuming locality, en route to prove that (classical) realism is false, perhaps.

Extremely interesting! Any links?

P.S. Welcome to PF charlylebeaugosse! :wink:

billschnieder

Aug8-10, 10:57 PM

Extremely interesting! Any links?

http://dx.doi.org/10.1140/epjd/e2010-00122-8

DrChinese

Aug9-10, 01:15 PM

http://dx.doi.org/10.1140/epjd/e2010-00122-8

I don't think this is exactly the same paper due to the dates, but it is very similar (same title, different abstract, same basic argument).

http://arxiv.org/abs/quant-ph/0608008

Also, this author has written other articles claiming that Bell leads to a rejection of what he calls "weak realism".

DevilsAvocado

Aug9-10, 02:22 PM

... Also, this author has written other articles claiming that Bell leads to a rejection of what he calls "weak realism".

I don’t know... but there seems to be other things that are a little "weak" also...? Like this:
"As a consequence classical realism, and not locality, is the common source of the violation by nature of all Bell Inequalities."

I may be stupid, but I always thought one has to make a choice between locality and realism? You can’t have both, can you?

And what is this?
"We prove versions of the Bell and the GHZ theorems that do not assume locality but only the effect after cause principle (EACP) according to which for any Lorentz observer the value of an observable cannot change because of an event that happens after the observable is measured."

To me this is contradictory. If you accept nonlocality, you must accept that the (nonlocal) effect comes before the cause (at speed of light)?

DrChinese

Aug9-10, 02:54 PM

DevilsAvocado

Aug9-10, 03:06 PM

Keep in mind that in Delayed Choice setups, you can have after the fact entanglement. So that pretty much wrecks his EACP anyway.

Thanks DrC. Great to have you back as the "Concierge" in this messy thread... :wink:

DrChinese

Aug9-10, 03:34 PM

Thanks DrC. Great to have you back as the "Concierge" in this messy thread... :wink:

More like the con rather than the concierge. :smile:

Hey, look at my post count! Although JesseM has been smearing me lately on post length...

DevilsAvocado

Aug9-10, 03:38 PM

More like the con

But not on Shutter Island, right!? :surprised

(:biggrin:)

DevilsAvocado

Aug9-10, 03:57 PM

Message to the Casual Reader

Maybe you are confused by what’s going on in this thread. And maybe you don’t know what to think about extensive and overcomplicated mathematical formulas, claiming to be a serious "rebuttal" of Bell's inequality.

Don’t worry. You are not alone. Let's untie this spurious "Gordian knot".

As already said – all this can be understood by a gifted 10-yearold (which includes DrC & Me, where the former is gifted :smile:).

Let’s start from the beginning, with Bell's theorem:
Wikipedia – Bell's theorem (http://en.wikipedia.org/wiki/Bell's_theorem)

In theoretical physics, Bell's theorem (AKA Bell's inequality) is a no-go theorem, loosely stating that:
No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.

It is the most famous legacy of the late physicist John S. Bell.

Bell's theorem has important implications for physics and the philosophy of science as it proves that every quantum theory must violate either locality or counterfactual definiteness.

Right there we can see that "some" in this thread have totally misinterpreted the very basics about Bell's theorem/Bell's inequality – Quantum Mechanics must violate either locality or counterfactual definiteness.

Bell's Theorem is not a diehard proof of nonlocality, never was, never will be.

Counterfactual definiteness (CFD) is another word for objective Realism, i.e. the ability to assume the physical existence of objects and properties of objects defined, whether or not it is measured (or observed or not).

Therefore we can say: Bell's Theorem proves that QM must violate either Locality or Realism.

If we combine Locality and Realism, we get Local Realism (LR), i.e. an object is influenced directly only by its immediate surroundings, and have an objective existence even when not measured.

Now we can see that: Bell's Theorem proves that QM violates Local Realism (LR).

Local Realism just doesn’t work with current understanding of Quantum Mechanics. Note that this is a totally different thing than faster than light (FTL) messaging.

Furthermore we can see that, for example billschnieder, is convinced that Bell's Theorem is an empirical "law of nature", and if he can find a mathematical flaw in this "law of nature", all goes down the drain, including 45 years of hard work, which is of course utterly silly and stupid, because it’s not a "law of nature", it’s a Theorem:
Wikipedia – Theorem (http://en.wikipedia.org/wiki/Theorem)

Theorems have two components, called the hypotheses and the conclusions. The proof of a mathematical theorem is a logical argument demonstrating that the conclusions are a necessary consequence of the hypotheses, in the sense that if the hypotheses are true then the conclusions must also be true, without any further assumptions. The concept of a theorem is therefore fundamentally deductive, in contrast to the notion of a scientific theory, which is empirical.

Deductive reasoning constructs or evaluates deductive arguments, which attempts to show that a conclusion necessarily follows from a set of premises.

Quantum mechanics, on the other hand, is an empirical scientific theory, where information is gained by means of observation, experience, or experiment.

billschnieder is comparing apples and oranges, without knowing what he's doing – in a last hysterical attempt to find some "flaw" in Bell's Theorem:
For a dataset of triples, Bell's inequality can never be violated, not even by spooky action at a distance! ... In other words, it is mathematically impossible to violate the inequalities for a dataset of triples, irrespective of the physical situation generating the data, whether it is local causality or FTL.

Pretty obvious, isn’t it? He’s fighting in the dark, totally obsessed with FTL, and completely in ignorance of the other half in Local Realism.

billschnieder is also convinced that he is in possession of the highest IQ of all times. That his simple "High School Freshman Discovery" has been overlooked by thousands of extremely brilliant scientist – including Nobel Laureates – where none of them saw this very simple "rebuttal": To violate Bell's inequality we need a dataset of TRIPLES from TWO entangled objects!

Besides totally hilarious, it’s an inevitable fact that we are dealing with a clear case of the dreadful Dunning–Kruger effect (http://en.wikipedia.org/wiki/Dunning–Kruger_effect).

Bell's Inequality is a concept, an idea, how to finally settle the long debate between Albert Einstein and Niels Bohr regarding the EPR paradox. Bell's Inequality is not one single mathematical solution – it can be defined in many ways – as DrChinese points out very well:
One of the things that it is easy to lose sight of - in our discussions about spin/polarization - is that a Bell Inequality can be created for literally dozens of attributes. Anything that can be entangled is a potential source. Of course there are the other primary observables like momentum, energy, frequency, etc. But there are secondary observables as well. There was an experiment showing "entangled entanglement", for example. Particles can be entangled which have never interacted, as we have discussed in other threads.

And in all of these cases, a realistic assumption of some kind leads to a Bell Inequality; that Inequality is tested; the realistic hypothesis is rejected; and the predictions of QM are confirmed.

There is not one single "Holy Grail of Inequality", as billschnieder assumes, and I’m going to prove it in a very simple example.

billschnieder thrives from complexity - the longer his futile equations gets – the happier he gets, and that goes for his semantic games as well. billschnieder rejects everything that’s beautiful in its simplicity, where there is no room for his erratic ideas.

This example, by Nick Herbert, is known as one of the simplest proofs of Bell's Inequality (and I already know billschnieder gonna hate it :devil:):

The setup is standard, one source of entangled pair of photons, and two polarizers that we can position independently at different angles.
http://i35.tinypic.com/13z71hi.png
The entangled source is of that kind, that if both polarizers are set to 0º, we will get perfect agreement, i.e. if one photon gets thru one polarizer the other photon gets thru the other polarizer, and if one is stopped the other is also stopped, i.e. 100% match and 0% discordance.

To start, we set first polarizer at +30º, and the second polarizer at 0º:
http://i37.tinypic.com/16jlw1g.png
If we calculate that discordance (i.e. the number of measurements where we get a mismatching outcome thru,stop / stop,thru), we get 25% according to QM and experiments.

Now, if we set first polarizer to 0º, and the second polarizer to -30º:
http://i37.tinypic.com/106jwrd.png
And calculate this discordance we will naturally get 25% according to QM, this time also.

Now let’s use some of John Bell’s brilliant logic, and ask ourselves:

– What will the discordance be if we set the polarizers to +30º and -30º ...??
http://i33.tinypic.com/2zjm5jk.png
Well that isn’t hard, is it ...!:uhh:?

If we assume a local reality, that nothing we do to one polarizer can affect the outcome of the other polarizer, we can formulate this simple Bell Inequality:
N(+30°, -30°) ≤ N(+30°, 0°) + N(0°, -30°)

The symbol N represents the number of discordance (or mismatches).

This inequality is as good as any other you’ve seen in this thread, anybody stating different is a crackpot liar.

(The "is less than or equal to" sign is just to show that there could be compensating changes where a mismatch is converted to a match, but this is not extremely important.)

We can make this simple Bell Inequality even simpler, for let’s say a gifted 10-yearold :smile::
50% = 25% + 25%

This is the obvious local realistic assumption.

But this wrong!!! According to QM and physical experiments we will now get 75% discordance!!! :surprised
sin2(60º) = 75%

This is completely crazy!? How can the setting of one polarizer affect the discordance of the other, if reality is local?? It just doesn’t make sense!!

But John Bell demonstrated by means of very brilliant and simple tools that our natural assumption about a local reality is by over 25% incompatible with the predictions of Quantum Mechanics and all performed physical experiments so far.

We can simplify our inequality even further and say:
25 + 25 = 50

And divide by 25, to get this extremely simple local realistic Bell Inequality:
1 + 1 = 2

How simple can it be ?:tongue:?

Now we can see that QM predictions and experiments violate this simple inequality:
1 + 1 = 3 !:devil:!

Conclusion: We do not need dataset of triples, or miles of Bayesian probability, or conspiracy theories, or any overcomplicated math whatsoever – BECAUSE IT’S ALL VERY SIMPLE AND BEAUTIFUL.

Hope this was helpful, and that you now clearly see who the liar in this thread is.

Thanks for the attention.

GeorgCantor

Aug9-10, 05:03 PM

Local Realism[/B] just doesn’t work with current understanding of Quantum Mechanics.

Bell's words:

"-My theorem answers some of Einstein's questions in a way that Einstein would have liked the least."

responding to Einstein's:

"-On this I absolutely stand firm. The world is not like this."

DrChinese

Aug9-10, 05:06 PM

As already said – all this can be understood by a gifted 10-yearold (which includes DrC & Me, where the former is gifted :smile:).

Let’s start from the beginning, with Bell's theorem:

...

Great post!

And I am gifted, because I got a present for my birthday! (The 10 year old part represents my emotional age, by the way.)

nismaratwork

Aug9-10, 05:46 PM

Bell's words:

"-My theorem answers some of Einstein's questions in a way that Einstein would have liked the least."

responding to Einstein's:

"-On this I absolutely stand firm. The world is not like this."

History has shown that the opinions of such men are less important than the work they leave behind. I think even dogs know at this point that Einstein was an uncompromising figure in the latter half of his life, searching for something which now seems even less likely. Should I raise a family in the manner of Dirac because he was brilliant? Bell's assertion is meaningless without his theorem, and Einstein's rebuttal is meaningless without a foundation.

Gordon Watson

Aug9-10, 05:47 PM

GeorgCantor

Aug9-10, 06:45 PM

Georg, Sources, please?

Thank you, JenniT

"Bell, in his first
article on hidden variables and contextuality [9], wrote
“the Einstein-Podolsky-Rosen paradox is resolved in the
way which Einstein would have liked least.”

Page 1 of:

"Einstein, Podolsky, Rosen, and Shannon"
Asher Peres
Department of Physics, Technion—Israel Institute of Technology, 32000 Haifa, Israel

http://arxiv.org/PS_cache/quant-ph/pdf/0310/0310010v1.pdf

The quote can also be found in "Quantum Reality" by N.Herbert with the insistence about spooky action "On this I absolutely stand firm. The world is not like this."

GeorgCantor

Aug9-10, 06:51 PM

History has shown that the opinions of such men are less important than the work they leave behind. I think even dogs know at this point that Einstein was an uncompromising figure in the latter half of his life, searching for something which now seems even less likely. Should I raise a family in the manner of Dirac because he was brilliant? Bell's assertion is meaningless without his theorem, and Einstein's rebuttal is meaningless without a foundation.

You are arguing with yourself or an imaginary version of "me". It must be your fantasy that drives your misguided belief I implied their work wasn't important. I said no such thing.

nismaratwork

Aug9-10, 07:00 PM

You are arguing with yourself or an imaginary version of "me". It must be your fantasy that drives your misguided belief I implied their work wasn't important. I said no such thing.

What was your point exactly?

JesseM

Aug9-10, 09:50 PM

You do not understand probability either. Say I give you the following list of

++
--
-+
+-

And ask you to calculate P(++) from it. Clearly the probability is the number of times (++) occurs in the list divided by the number of entries in the list.
No, you can't calculate the probability just from the information provided, not if we are talking about objective frequentist probabilities rather than subjective estimates. After all, the nature of the physical process generating this list might be such that frequency of ++ in a much greater number of trials would be something other than 0.25, and according to the frequentist definition P(++) is whatever fraction of trials would yield result ++ in the limit as the number of trials went to infinity.
So your "law of large numbers" cop-out is an approximation of the true probability not it's definition. You need to learn some basic probability theory here because you are way off base.
Again your argument seems to involve a casual dismissal of the frequentist view of probability, when it is an extremely mainstream way of defining the notion of "probability", and regardless of whether you like it or not, it's a pretty safe bet that Bell was tacitly assuming the frequentist definitions in his proofs since they become fairly incoherent with any more subjective definition of probability (because they deal with "probabilities" of hidden variables that would be impossible for experimenters to measure)
But then you use that to come to the absurd conclusion that in order to compare with empirical data, we need to make some assumptions about the distribution of values of λ on our three runs. We don't--Bell was writing for an audience of physicists, who would understand that whenever you talk about an "expectation value", the basic definition is always just a sum over each possible measurement result times the probability of that result
Sorry JesseM but that bubble has already been burst, when I proved conclusively that you do not know the meaning of "expectation value".
So you deny that the "expectation value" for a test which can yield any of N possible results R1, R2, ..., RN would just be 1/N \sum_{i=1}^N R_i * P(R_i )? (where P(R) is the probability distribution function that gives the probability for each possible Ri) This is the definition of "expectation value" I used, and if you deny that this is true for a test with a finite set of possible results (like the measurement of spin for two entangled particles), then it is you who fails to understand the basic meaning of the term "expectation value". If you agree with this definition but think I have somehow been failing to use it in my own arguments, then you are misunderstanding something, please clarify.
To show how silly this adventitious argument of yours is, I asked you a simple question and dare you to answer it:

You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product.
It's impossible to write down the correct objective/frequentist expectation value unless we know the sample space of possible results (all possible pairs, which might include possibilities that don't appear on the list of N pairs) along with the objective probabilities of each result (which may be different from the frequency with which the result appears on your list, although you can estimate the objective probability based on the empirical frequency if N is large...it's better if you have some theory that gives precise equations for the probability like QM though).
Once you have done that, try and swindle your way out of the fact that
"Swindle", nice. You stay classy Bill!
a) The structure of the expression so derived does not depend on the actual value N. ie, N could be 5, 100, or infinity.
If you know the objective probabilities, then it doesn't even depend on the results that happen to appear on the list! But if you're just trying to estimate the true probabilities based on the frequencies on the list, than the accuracy of your estimates (as compared to the actual true probabilities) is likely to be higher the greater N is.
b) The expression so derived is a theoretical expression not "empirical".
If you are estimating the probabilities based on the frequencies on the list, then I would call this an empirical estimate of the expectation value, which may be different from the true expectation value. For example, if I know based on theory that a certain test has an 0.5 chance of giving result +1 and an 0.5 chance of giving result -1, then the expectation value is (+1)*(0.5) + (-1)*(0.5)=0. On the other hand, if I don't know the true probabilities of +1 and -1 and am just given a list of results with 51 results that are +1 and 49 results that are -1, then my estimate of the expectation value would be (+1)*(0.51) + (-1)*(0.49) = 0.02, close to the theoretically-derived expectation value of 0 but slightly off.
c) The expression so derived is the same as the simple average of the paired products.
Not if you know (or can calculate theoretically) the true probabilities of different results, and they are different from the fraction of trials with each result that appear on the list.
So for example, if one run with settings (a,b) included three trials where λ took the value λ3, while another run with settings (b,c) included no trials where it took the value λ3, this wouldn't imply that ρ(λi) differed in the integrals for E(a,b) and E(b,c)? Because your comment at the end of post #1224 suggests you you are still confusing the issue of what it means for the "true probabilities" ρ(λi) to differ depending on the detector settings and what it means for the actual frequencies of different values of λi to differ on runs with different detector settings
You are sorely confused. Note I use ρ(λi) not P(λi) to signify that we are dealing with a probability distribution, which is essentially a function defined over the space of all λ, with integral over all λ equal to 1.
P(λi) is also a type of probability distribution, the only difference between ρ(λi) and P(λi) is that ρ(λi) is a continuous probability density function (http://en.wikipedia.org/wiki/Probability_density_function) (based on the assumption that λ can take a continuous range of values) while P(λi) is a discrete probability distribution (http://en.wikipedia.org/wiki/Discrete_probability_distribution)--I have in some posts made the simplifying assumption that λ can only take a finite set of possible values rather than being a continuous variable, it makes no real difference to Bell's argument which one we assume.
If the (a,b) run included N iterations with three of those corresponding to λ3, P(λ3) for our dataset = 3/N. But if in a different run of the experiment (b,c) none of the λ's was λ3, P(λ3) = 0 for our dataset. It therefore means the probability distribution of ρ(λi) can not be same for E(a,b) and E(b,c)
No, it doesn't mean that, because the ρ(λi) that appears in Bell's equations (along with the P(λi) that appears in the discrete version) is pretty clearly supposed to be an objective probability function of the frequentist type. Anyone who understands what it means to say that for a fair coin P(heads)=0.5 even if an actual series of 20 flips yielded 11 heads and 9 tails should be able to see the difference between the two.

Again, no one is asking you to agree that frequentist definitions are the "best" ones to use in ordinary situations where we are trying to come up with probability estimates from real data, but you can't really deny they are widely used in theoretical arguments involving probabilities, so you might at least consider whether Bell's arguments make sense when interpreted in frequentist terms. If you simply refuse to even talk about the frequentist notion of probability because you have such a burning hatred for it, then probably you're not really interested in trying to understanding Bell's argument in its own terms (i.e., how Bell and other physicists would conceive the argument), but are just trying to make a rhetorical case against it based on showing that it becomes incoherent when we interpret the probabilities in non-frequentist terms.
According to Bell, E(a,b) calculated by the following sum

a1*b1*P(λ1) + a2*b2*P(λ2) + ... + an*bn*P(λn) where n is the total number of possible distinct lambdas.
Sure.
ρ(λ) is a function which maps a specific λi to its probability P(λi).
Huh? P(λi) is already a function that maps each specific λi to a probability. Bell just uses the greek letter \rho to indicate he's talking about a probability density function on a variable λ which is assumed to be continuous--the "probability density" for a specific value of λ would then not be an actual probability, instead if you want to know the probability that λ was in some finite range (say, between 0.4 and 0.5) you'd integrate the probability density function in that range, and that would give the probability. That's why Bell writes "It is a matter of indifference in the following whether λ denotes a single variable or a set, or even a set of functions, and whether the variables are discrete or continuous. However, we write as if λ were a single continuous parameter ... ρ(λ) is the probability distribution of λ". It's common in QM to use ρ to refer to a probability density, see here (http://en.wikipedia.org/wiki/Probability_current) and here (http://arxiv.org/abs/0912.4659) for example.
By definition therefore, if the function ρ(λ) is the same for two runs of the experiment, it must produce the same P(λi) for both cases. In other words, if it produced different values of P(λi) such as 3/N in one case and 0 in another, it means ρ(λ) is necessarily different between the two and the runs can not be used together as a valid source of terms for comparing with Bell's inequality.
Not if we are defining probabilities in a frequentist sense, and I think any physicist reading Bell's work would understand that in his theoretical proof he is indeed using the frequentist definition, so having the same probability distribution for different detector settings need not imply that the frequency of a given λi would actually be exactly the same for two finite runs with different detector settings (just like the claim that two fair coins both have P(heads)=0.5 does not imply that two runs of ten flips with each coin will each produce exactly five heads).
But practically, you could obtain the same E(a,b) by calculating a simple average over a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability. ie

For example, if we had only 3 possible λ's (λ1, λ2, λ3) with probabilities (0.3, 0.5, 0.2) respectively. The expectation value will be
E(a,b) = 0.3*A(a,λ1)*B(b,λ1) + 0.5*A(a,λ2)*B(b,λ2) + 0.2*A(a,λ3)*B(b,λ3)

Where each outcome for a specific lambda exists exactly once. OR we can calculate it using a simple average, from a dataset of 10 data points, in which A(a,λ1),B(b,λ1) was realized exactly 3 times (3/10 = 0.3), A(a,λ2), B(b,λ2) was realized 5 times, and A(a,λ3), B(b,λ3) was realized 2 times; or any other such dataset of N entries where the relative frequencies are representative of the probabilities. Practically, this is the only way available to obtain expectation values, since no experimenter has any idea what the λ's are or how many of them there are.
You really think that this is the "exact same thing" as what I was saying? Here your "practical" average requires us to know which value of λ occurred on each trial
Oh come on! At least be honest about what you claim I am saying! Why would you need to know λ for each trial if you are calculating a simple average!?
OK, I missed the bolded sentence, but I don't understand how the stuff that preceded it can possibly be consistent with the idea that the experimenter doesn't know what the λ's are. How does the experimenter know that "A(a,λ1),B(b,λ1) was realized exactly 3 times" if he has no idea whether λ1 or some other λ occurred on a given trial? How would you know whether your outcomes were "a representative set of outcomes in which the frequency of realization of a specific λ, is equivalent to it's probability" if you had no idea what the frequency was that each specific λ was realized? Once again your explanation is totally confusing to me, and I suspect to other readers as well, but anytime I misunderstand instead of helpfully correcting me you immediately jump down my throat and accuse me of not being "honest".

Also, what does it even mean to say that a set of outcomes is "representative" if "the frequency of realization of a specific λ, is equivalent to it's probability" when you are using a non-frequentist definition of probability? If we have a set of 3000 outcomes and we somehow know that λ1 occurred on 30 of those, are you using a definition of "probability" where that would automatically imply that the probability of λ1 given that data must be 0.01? (that's what seemed to be implied by your comment quoted at the start that 'Clearly the probability is the number of times (++) occurs in the list divided by the number of entries in the list') For a frequentist the "true" probability of λ1 could certainly be different from 0.01 since the fraction of outcomes with λ1 might approach some other value in the limit as the number of trials approached infinity, but from the way you are defining probabilities it seems like the fraction of trials where λ1 occurs is by definition said to be the "probability" of λ1, so I don't see how any set of outcomes could fail to be "representative". If you are not defining the probability of an event as just the fraction of trials in the dataset where that event occurred, please clarify your definition.

And once again, regardless of your definition, will you at least consider whether Bell's proof makes sense if the probabilities are interpreted in frequentist terms? It seems like most of your critique is based on the assumption that he is defining probabilities in terms of actual outcomes on some finite set of trials, but if he was assuming more "objective" frequentist definitions then this would be a giant strawman argument.

billschnieder

Aug10-10, 01:04 AM

No, you can't calculate the probability just from the information provided, not if we are talking about objective frequentist probabilities rather than subjective estimates. After all, the nature of the physical process generating this list might be such that frequency of ++ in a much greater number of trials would be something other than 0.25, and according to the frequentist definition P(++) is whatever fraction of trials would yield result ++ in the limit as the number of trials went to infinity.
Who said anything about a physical process. I've given you an abstract mathematical list, and you can't bring yourself to admit that you were wrong, to the point you are making yourself look foolish. P(++) for the list I gave you is 1/4, even a cave man can understand that level of probability theory Jesse!!! Are you being serious, really?

So your "law of large numbers" cop-out is an approximation of the true probability not it's definition. You need to learn some basic probability theory here because you are way off base.
Again your argument seems to involve a casual dismissal of the frequentist view of probability, when it is an extremely mainstream way of defining the notion of "probability"

Who said anything about frequentist view. All I did was point out to you a basic mainstream fact in probability theory:

Wikipedia (http://en.wikipedia.org/wiki/Law_of_large_numbers):
In probability theory, the law of large numbers (LLN) is a theorem that describes the result of performing the same experiment a large number of times. According to the law, the average of the results obtained from a large number of trials should be close to the expected value, and will tend to become closer as more trials are performed.

So you are way off base and I am right to say that you do not understand probability theory.

So you deny that the "expectation value" for a test which can yield any of N possible results R1, R2, ..., RN would just be
1/N \sum_{i=1}^N R_i * P(R_i ) ?

(where P(R) is the probability distribution function that gives the probability for each possible Ri)

Again you are way off base. In probability theory When using the probability of an R as a weight in calculating the expectation value, you do not need to divide the sum by N again. That will earn you an F grade. The correct expression should be:

\sum_{i}^{N} R_i * P(R_i )

For example, if N is 3 and the probabilities of R1, R2 and R3 are (0.3, 0.5, 0.2) the expectation value will R1*0.3 + R2*0.5 + R3*0.2 NOT (R1*0.3 + R2*0.5 + R3*0.2)/3 !!!!

billschnieder

Aug10-10, 01:11 AM

You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product.
It's impossible to write down the correct objective/frequentist expectation value unless we know the sample space of possible results (all possible pairs, which might include possibilities that don't appear on the list of N pairs) along with the objective probabilities of each result (which may be different from the frequency with which the result appears on your list, although you can estimate the objective probability based on the empirical frequency if N is large...it's better if you have some theory that gives precise equations for the probability like QM though).

Wow! The correct answer is <xy>

Wikipedia:
http://en.wikipedia.org/wiki/Mean

In statistics, mean has two related meanings:

* the arithmetic mean (and is distinguished from the geometric mean or harmonic mean).
* the expected value of a random variable, which is also called the population mean.

There are other statistical measures that use samples that some people confuse with averages - including 'median' and 'mode'. Other simple statistical analyses use measures of spread, such as range, interquartile range, or standard deviation. For a real-valued random variable X, the mean is the expectation of X.

You really do not know anything about probability.

"Swindle", nice. You stay classy Bill!
I didn't think it was possible to swindle that one. But you found a way. Foolish me for thinking a blatant fact will be too difficult for you to swindle.

No, it doesn't mean that, because the ρ(λi) that appears in Bell's equations (along with the P(λi) that appears in the discrete version) is pretty clearly supposed to be an objective probability function of the frequentist type.

Oh, so now you are abandoning your law of large numbers again because it suits your argument. Remember the the underlined text because it will haunt you later when you try to argue that expectation values calculated from three different runs of an experiment can be used as terms for comparing with Bell's inequality. You are way off base as you recognize yourself in the following comment:

Again, no one is asking you to agree that frequentist definitions are the "best" ones to use in ordinary situations where we are trying to come up with probability estimates from real data...
Right after arguing that the probabilities I got from real data are not the correct ones, you go right ahead and argue that the frequentist view (which btw, is what I used in the statement you were objecting to), is the "best" one to use. But yet, you still manage to imply that I disagree with the frequentist view !?! Only JesseM can do this kind of swindling. It is professional grade indeed.

From the number of times you have suddenly invoked the word "frequentist" in the latest post of yours, it seems you would rather we abandon this discussion and start one about definitions of probability of which your favorite is frequentist. But I'm not interested in that discussion, thank you for asking subtly though. I understand that you plan to argue next that unless the frequentist view is used, Bell's work can not be understood correctly. Even though I will not agree with such a narrow view, let me pre-empt that and save you a lot of effort by pointing you to the fact that in my arguments above explaining Bell's work, I have been using the frequentist view.

billschnieder

Aug10-10, 01:14 AM

nismaratwork

Aug10-10, 07:45 AM

JesseM

Aug10-10, 10:05 AM

Who said anything about a physical process. I've given you an abstract mathematical list, and you can't bring yourself to admit that you were wrong, to the point you are making yourself look foolish. P(++) for the list I gave you is 1/4, even a cave man can understand that level of probability theory Jesse!!! Are you being serious, really?
Yes, Bill. Would you deny, for example, that a physical process that had P(++)=0.3, P(+-)=0.2, P(-+)=0.15, and P(--)=0.35 (with all of these numbers being the frequentist probabilities that would represent the fraction of trials with each value in the limit as the number of trials goes to infinity) could easily generate the following results on 4 trials?

++
--
-+
+-
Who said anything about frequentist view.
I did. It's the only notion of "probability" that I've been using the whole time, perhaps if you go back and look at some of the posts of mine you thought didn't make sense and read them in this light you will understand them better (also, note that I'm not talking about 'finite frequentism', but 'frequentism' understood in terms of the limit as the number of trials goes to infinity--see below for a link discussing the difference between the two). For example, if we are talking about the frequentist view of probability, the mere fact that you got ++ once on a set of four trials does not imply P(++)=0.25...do you disagree?
All I did was point out to you a basic mainstream fact in probability theory:

Wikipedia (http://en.wikipedia.org/wiki/Law_of_large_numbers):
In probability theory, the law of large numbers (LLN) is a theorem that describes the result of performing the same experiment a large number of times. According to the law, the average of the results obtained from a large number of trials should be close to the expected value, and will tend to become closer as more trials are performed.So you are way off base and I am right to say that you do not understand probability theory.
Note that the wikipedia article says "close to the expected value", not "exactly equal to the expected value". And note that this is only said to be true in a large number of trials, the article does not suggest that if you have only four trials the average on those four trials should be anywhere near the expectation value. Finally, note that in the forms (http://en.wikipedia.org/wiki/Law_of_large_numbers#Forms) section of the article they actually distinguish between the "sample average" and the "expected value", and say that the "sample average" only "converges to the expected value" in the limit as n (number of samples) approaches infinity. So, it seems pretty clear the wikipedia article is using the frequentist definition as well.
So you deny that the "expectation value" for a test which can yield any of N possible results R1, R2, ..., RN would just be 1/N \sum_{i=1}^N R_i * P(R_i )? (where P(R) is the probability distribution function that gives the probability for each possible Ri)
Again you are way off base. In probability theory When using the probability of an R as a weight in calculating the expectation value, you do not need to divide the sum by N again. That will earn you an F grade. The correct expression should be:

\sum_{i}^{N} R_i * P(R_i )
Yes, here you did catch me in an error, I wrote down the expression too fast without really thinking carefully, I guess I got confused by all the other sums which did include 1/N on the outside. Before you brandish this as proof that I "don't know probability", note that in previous posts I did write it down correctly, for example in post #1205:
In general, if you have some finite number N of possible results Ri for a given measurement, and you know the probability P(Ri) for each result, the "expectation value" is just:

E = \sum_{i=1}^N R_i * P(R_i )

If you perform a large number of measurements of this type, the average result over all measurements should approach this expectation value.
And in post #1218:
Physical assumptions are peripheral to calculating averages from experimental data, it's true, and they're also peripheral to writing down expectation values in terms of the "true" probabilities as I did when I wrote E(R) = \sum_{i=1}^N R_i * P(R_i),
Anyway, now that we seem to be agreed that the correct form for the expectation value is E = \sum_{i=1}^N R_i * P(R_i ) (though I am sure we would disagree on the meaning of P(Ri) since I define it in frequentist terms as the fraction of trials that would give result Ri in the limit as the number of trials goes to infinity), can you tell me if you think I was incorrect to write the expectation value as follows?

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

This equation does have the form E = \sum_{i=1}^N R_i * P(R_i ) does it not? If you don't object to the claim that the above is at least one way of defining E(a,b), then why in post #1221 did you object as follows?
So when you say:
This expectation value is understood as a sum of the different possible measurement outcomes weighted by their "true" probabilities:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...

The comment above is completely misguided, since the basic definition of "expectation value" in this experiment has nothing at all to do with knowing the value of λ, it is just understood to be:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)
It clearly shows that you do not understand probability or statistics. Clearly the definition of expectation value is based on probability weighted sum, and law of large numbers is used as an approximation, that is why it says in the last sentence above that the expectation values is "almost surely the limit of the sample mean as the sample size grows to infinity"
You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product.
It's impossible to write down the correct objective/frequentist expectation value unless we know the sample space of possible results (all possible pairs, which might include possibilities that don't appear on the list of N pairs) along with the objective probabilities of each result (which may be different from the frequency with which the result appears on your list, although you can estimate the objective probability based on the empirical frequency if N is large...it's better if you have some theory that gives precise equations for the probability like QM though).
Wow! The correct answer is <xy>

Wikipedia:
http://en.wikipedia.org/wiki/Mean
In statistics, mean has two related meanings:

* the arithmetic mean (and is distinguished from the geometric mean or harmonic mean).
* the expected value of a random variable, which is also called the population mean.

There are other statistical measures that use samples that some people confuse with averages - including 'median' and 'mode'. Other simple statistical analyses use measures of spread, such as range, interquartile range, or standard deviation. For a real-valued random variable X, the mean is the expectation of X.

You really do not know anything about probability.
Here the wikipedia article is failing to adequately distinguish between the "mean" of a finite series of trials (or any finite sample) and the "mean" of a probability distribution (edit: See for example this book (http://books.google.com/books?id=3wCWS4VnLJMC&lpg=PA65&dq=%22population%20mean%22%20%22sample%20mean%22&pg=PA65#v=onepage&q=%22population%20mean%22%20%22sample%20mean%22&f=false) which distinguishes the 'sample mean' \bar X from the 'population mean' \mu, and says the sample mean 'may, or may not, be an accurate estimation of the true population mean \mu. Estimates from small samples are especially likely to be inaccurate, simply by chance.' You might also look at this book (http://books.google.com/books?id=1uLGa4eQ05gC&lpg=PA309&dq=%22population%20mean%22%20probability%20distrib ution&pg=PA309#v=onepage&q=%22population%20mean%22%20probability%20distribu tion&f=false) which says 'We use \mu, the symbol for the mean of a probability distribution, for the population mean', or this book (http://books.google.com/books?id=2JfLi3RKRV8C&lpg=PA115&dq=mean%20%22probability%20distribution%22&pg=PA115#v=onepage&q=mean%20%22probability%20distribution%22&f=false) which says 'The mean of a discrete probability distribution is simply a weighted average (discussed in Chapter 4) calculated using the following formula: \mu = \sum_{i=1}^n x_i P[x_i ]'). If you think the expectation value is exactly equal to the average of a finite series of trials, regardless of whether the number of trials is large or small, then you are disagreeing with the very wikipedia quote you posted earlier from the Law of Large Numbers page:
In probability theory, the law of large numbers (LLN) is a theorem that describes the result of performing the same experiment a large number of times. According to the law, the average of the results obtained from a large number of trials should be close to the expected value, and will tend to become closer as more trials are performed.
According to you, would it be more correct to write "the average of the results obtained from any number of trials would be exactly equal to the expected value"? If you do, then your view is in conflict with the quote above. And if you don't think the average from a finite number of trials is exactly equal to the expectation value, then you were incorrect to write "Wow! The correct answer is <xy>" above.
No, it doesn't mean that, because the ρ(λi) that appears in Bell's equations (along with the P(λi) that appears in the discrete version) is pretty clearly supposed to be an objective probability function of the frequentist type.
Oh, so now you are abandoning your law of large numbers again because it suits your argument.
Um, how am I doing that? I said "objective probability function of the frequentist type" above (and again, you can assume that all my comments about probabilities assumed a frequentist definition, it might help you avoid leaping to silly false conclusions about what I'm arguing), do you understand that this would be a function where the "probability" it assigns to any outcome is equal to the fraction of trials where that outcome would occur in the limit as the number of trials went to infinity? And if I'm defining probabilities in terms of the limit as the number of trials goes to infinity, I'm pretty clearly making use of the law of large numbers, no?
Remember the the underlined text because it will haunt you later when you try to argue that expectation values calculated from three different runs of an experiment can be used as terms for comparing with Bell's inequality.
You can't calculate "expectation values" from three runs with a finite series of trials, not in my way of thinking (I have never said otherwise, if you think I did you misread me). You can only calculate the sample average from a finite run of trials. However, by the law of large numbers, the bigger your sample, the smaller the probability that your sample average will differ significantly from the "true" expectation value determined by the "true" probabilities (again with 'true' probabilities defined in frequentist terms)
Again, no one is asking you to agree that frequentist definitions are the "best" ones to use in ordinary situations where we are trying to come up with probability estimates from real data...
Right after arguing that the probabilities I got from real data are not the correct ones, you go right ahead and argue that the frequentist view (which btw, is what I used in the statement you were objecting to), is the "best" one to use.
Again, the usual modern meaning of the "frequentist" view is that the probability of some outcome is just the fraction of trials with that outcome in the limit as the number of trials goes to infinity, not in any finite series of trials (see here (http://en.wikipedia.org/wiki/Frequency_probability) and here (http://books.google.com/books?id=Q1AUhivGmyUC&lpg=PA80&dq=frequentism&pg=PA80#v=onepage&q=frequentism&f=false) and p.9 here (http://www.google.com/url?sa=t&source=web&cd=6&ved=0CDUQFjAF&url=http%3A%2F%2Fwww-group.slac.stanford.edu%2Fsluo%2Flectures%2Fstat_l ecture_files%2Flyons_colloquium_Stat2007.pdf&rct=j&q=frequentism&ei=S2JhTKXWEofksQOlkOTxBw&usg=AFQjCNFy0P1gaD6o1HHEho8cArCuTYnWhQ&cad=rja) for example...the Stanford Encyclopedia of Philosophy article (http://plato.stanford.edu/entries/probability-interpret/#FreInt) also refers to something called 'finite frequentism', but modern authors usually use 'frequentism' to mean the definition involving the limit as number of trials approaches infinity, and in any case this is what I have always meant by 'frequentism', I'm certainly not talking about finite frequentism)

And I am only arguing that the frequentist view is the "best" one to use for understanding the meaning of the probabilities in Bell's theoretical argument, not for estimating probabilities based on empirical data. All I want to know is whether you are willing to consider whether your argument about the limited applicability of Bell's proof (that it can't be applied to three separate lists of pairs which can't be resorted in the way you discussed in #1208) would not apply if we interpret the probabilities in Bell's argument in frequentist terms. Can you please tell me, yes or no, are you willing to consider whether Bell's proof might allow us to make broad predictions about three runs which each yield a distinct list of pairs, if we do indeed interpret the probabilities in his theoretical argument in (non-finite) frequentist terms?
From the number of times you have suddenly invoked the word "frequentist" in the latest post of yours, it seems you would rather we abandon this discussion and start one about definitions of probability of which your favorite is frequentist.
I don't want a discussion of definitions of probability. Whenever I have been talking about probabilities I have been assuming frequentist definitions, and only lately have I noticed that your argument seems to depend critically on the fact that you are using non-frequentist definitions (or 'finite frequentist' definitions if you prefer), which is why I have started trying to be explicit about it. Even if you don't like the frequentist definition in general, all I'm asking is that you consider the possibility that Bell's own probabilities might have been intended to be interpreted in frequentist terms, and that the supposed problems with his argument might disappear if we do interpret symbols like ρ(λ) in this light.
I understand that you plan to argue next that unless the frequentist view is used, Bell's work can not be understood correctly. Even though I will not agree with such a narrow view, let me pre-empt that and save you a lot of effort by pointing you to the fact that in my arguments above explaining Bell's work, I have been using the frequentist view.
Your arguments may have been assuming the "finite frequentist" view, but as I said that's not what I'm talking about. I'm talking about the more common "frequentist" view that defines objective probabilities in terms of the limit as the number of trials goes to infinity. Are you willing to discuss whether Bell's argument makes sense (and doesn't have the problem of limited applicability that you point to) if we assume the probabilities in his theoretical argument were also meant to be understood in the same "frequentist" sense that I'm talking about here?

charlylebeaugosse

Aug10-10, 10:28 AM

I don’t know... but there seems to be other things that are a little "weak" also...? Like this:
"As a consequence classical realism, and not locality, is the common source of the violation by nature of all Bell Inequalities."

I may be stupid, but I always thought one has to make a choice between locality and realism? You can’t have both, can you?

And what is this?
"We prove versions of the Bell and the GHZ theorems that do not assume locality but only the effect after cause principle (EACP) according to which for any Lorentz observer the value of an observable cannot change because of an event that happens after the observable is measured."

To me this is contradictory. If you accept nonlocality, you must accept that the (nonlocal) effect comes before the cause (at speed of light)?

The Effect After Cause Principle (EACP) states ONLY that:
For any Lorentz observer O, once an effect E of cause C is observed by observer O, no fiddling with C can change E.

Now the cause could happen after the effect despite the EACP if Non-Locality would hold true. Only the cause would have to be a cause that is compatible with the observed effect. Most physicists would admit that an observation once made cannot be changed, even if these physicists believe that non-locality holds true. So the EACP once understood properly (and stated properly for that effect) should not be a problem for most (should I say "any"?) physicists.

This being said, citing delayed choice experiments against the EACP (as someone has done in this thread) after the superb analysis of the question "Resolution to the Delayed choice quantum eraser?" presented by Cthugha is really missing the point of what is the meaning of the EACP (and the illusory nature of the delay of the cause in delayed erasure experiments, since one is only speaking of generating measurements that can be done in coincidence (Wheeler's type delay experiment are another matter altogether, even if Jacques et al. use delayed erasure to perform what they call an instance of Wheeler's delayed measurement experiments: I'll have to check if there is a thread on that)). But I confess that the EACP is not as easy as concept to grab as one would like. The proof of Bell compatible with the EACP is indeed delicate, and msot Bell inequalities cannot be proved when one replaces the locality assumption by the (much) weaker EACP assumption.

Now coming back to the first point of the quote from DevilsAvocado, of course one knows from Bell's Theorem and Quantum Mechanics that "locality" and "realism" cannot be both true (where "realism" means classical realism, i.e., the observables have values before measurement, and in particular observables make sense before measurement). The point of the paper is to make progress toward the fact that it is "realism" and not "locality" that is the problem generating contradictions.

PRELUDE TO A QUESTION (since we are mentioning "realism"): The older attack on "realism" that I know ([B] using QM arguments [\B] ) is a 1931 paper by (and I cite in reverse order w.r.t. what is on the paper): Podolsky, Tolman....
and Einstein (the ETP paper). This at a time when Bohr and Heisenberg where admitting retrodictive ([I] i.e, [\I] backward in time, but I may have the spelling wrong) violation of the Uncertainty Principle (Heisenberg apparently doing that because of Bohr). So much for Einstein as naively realist. Now, this being said, there is a little catch in the ETP paper: the argument works for generic particles, but not for some special particles such as the EPR particles that are both very special to QM and (but this is less well known) more classical than generic particles, as for instance, if created in pairs such that the total momentum is conserved, they do not generate interference when going through a setting that would generate interferences with generic particles. (I do not believe that Einstein was always right, but why create mistakes that he did not make, especially when he was right or had at least a view worse taking into consideration? Some people like to tell of his supposed mistakes to tell that they understand better, which is not the way this preamble to a question should be taken: the question indeed follows).

QUESTION: Can anyone tell me of a PHYSICS argument against "realism" older than ETP?

billschnieder

Aug10-10, 10:30 AM

Bill, give it up, I don't know where you're getting the ideas you espouse here, but JesseM is tearing them apart.
Hehehe, Evidently you are not on the same planet as the one this discussion is taking place in. You may be a member of the JesseM fan club but it is not up to you what I can or can not argue in this thread. So if you have anything of import to say about any of the specific facts I have posted here, all backed up by standard mathematics, post it and be prepared to defend it as well rather than shy away and pretend to be a thread police.

I'll say it again, you can post in bulk, but it doesn't change that your posts are rambling and borderline-crackpot, whereas JesseM is sticking to the science.
Again give one example where I was wrong and JesseM was right and be prepared to back it up. If you think throwing words like "crackpot" around will have any impact on my determination to vehemently defend what I know to be accurate, you haven't been speaking with DevilsAvocado enough. He has tried and failed.

The more crap like yours there is to respond to, the more posts I will post. I do not like long posts so I break down my posts into pieces which address a specific point. You do not like that, tough luck. I tried sticking to the essentials but JesseM kept throwing bulk at me, so I decided from now on I will not leave any stone uncovered.

You keep saying things such as, "[JesseM] doesn't know anything about probability," which having read the last 20 pages or so, is laughable!
Because you do not know anything about probability yourself so you can not independently understand anything being said. And since you already sold all your property and bought JesseM stock a while back, you defer all your judgement to him. Anything he says is 100% accurate to you. You are not the only one.

You are talking pure crap, and he's calling you on every point.
Like which one?

As one of the "casual readers" DevilsAvocado refers to, please, take your personal Quixote complex to PMs and let this thread become readable again. I for one am tired of JesseM having to go through your endless multiple posts, line by line to try and reason with you.
There are casual readers who matter and there are the fan-boys who don't. You can guess which class you belong to. But if you do not like the thread, don't read it, nobody voted you president of the casual readers. Other casual readers have brains and can follow a discussion without being patronized by the likes of you and DA. Besides if JesseM was calling out my crap as you claim he was, you won't be trying to stop me. Your comments suggest the opposite is the case and you are beginning to regret your premature investment.

You can keep harping on \lambda, but it's only in the context of what seems to be your own nearly religious belief here. You clearly have no idea what the significance of Bell or a BSM is, and your own concocted standards for what "the whole point" is, has no bearing on the current science. Why not start a blog where you can rant and rail to your heart's content, and spare the thread the clutter.
Why do you think I posting on this thread, because I like getting in the skin of people like you who make ridiculous claims without knowing squat about what you are talking about? Why don't you start a blog so that you can police all the comments to your hearts content?

DrChinese

Aug10-10, 10:42 AM

The Effect After Cause Principle (EACP) states ONLY that:
For any Lorentz observer O, once an effect E of cause C is observed by observer O, no fiddling with C can change E.

Now the cause could happen after the effect despite the EACP if Non-Locality would hold true. Only the cause would have to be a cause that is compatible with the observed effect. Most physicists would admit that an observation once made cannot be changed, even if these physicists believe that non-locality holds true. So the EACP once understood properly (and stated properly for that effect) should not be a problem for most (should I say "any"?) physicists.

This being said, citing delayed choice experiments against the EACP (as someone has done in this thread) after the superb analysis of the question "Resolution to the Delayed choice quantum eraser?" presented by Cthugha is really missing the point of what is the meaning of the EACP (and the illusory nature of the delay of the cause in delayed erasure experiments, since one is only speaking of generating measurements that can be done in coincidence (Wheeler's type delay experiment are another matter altogether, even if Jacques et al. use delayed erasure to perform what they call an instance of Wheeler's delayed measurement experiments: I'll have to check if there is a thread on that)). But I confess that the EACP is not as easy as concept to grab as one would like. The proof of Bell compatible with the EACP is indeed delicate, and msot Bell inequalities cannot be proved when one replaces the locality assumption by the (much) weaker EACP assumption.

Not sure I would agree here that delayed choice experiments are not relevant. What is the meaning of EACP if you have the future affecting the past? And you cannot be certain that is not happening once you look at those experiments.

I personally cannot see that EACP is a "weaker" assumption than locality. I mean, it seems a subjective assessment.

JesseM

Aug10-10, 11:13 AM

but I don't understand how the stuff that preceded it can possibly be consistent with the idea that the experimenter doesn't know what the λ's are. How does the experimenter know that "A(a,λ1),B(b,λ1) was realized exactly 3 times" if he has no idea whether λ1 or some other λ occurred on a given trial?
You do not get it. It is their only hope if they are trying to obtain empirical estimates of the true expectation value.
What do you mean by "true expectation value"? Are you using the same definition I have been using--the average in the limit as the number of trials goes to infinity--or something else?

Also, when you say "it is their only hope", what is "it"? Are you saying their only hope is to make some assumptions about the values of λ in their experiment, such as the idea that the distribution of different λi's in their sample is similar to the one given by the probability distribution function (in the discrete case I label this function P(λi), in the continuous case we'd need a probability density function which I would label ρ(λ))? And if you are saying physicists have to make some assumption about the values of λ in their experiment, why did you object so venomously at the end of post #1228 to a statement of mine which just suggested this was what you were saying, namely:
If you think a physicists comparing experimental data to Bell's inequality would actually have to draw any conclusions about the values of λ on the experimental trials, I guarantee you that your understanding is totally idiosyncratic and contrary to the understanding of all mainstream physicists who talk about testing Bell's inequality empirically. Grasping at straws here to make it look like there is something I said which you object to. Note that you start the triumphant statement with an IF and then go ahead to hint that what you are condemning is actually something I think but you provide no quote of mine in which I said anything of the sort. I thought this kind of tactics was relagated to talk-show tv and political punditry.
This is the whole point! They can't just measure crap and plug it into Bell's equations unless they can ascertain that it is a damn good estimate of the true expectation values!
Yes, but to get a "damn good estimate of the true expectation values", all that's necessary is that the actual frequencies of different measurement results were close to the "true probabilities" (in frequentist terms) in equations like this one:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

As long as the fraction of trials where they got a given pair of results like (+1 on detector with setting a, +1 on detector with setting b) is close to the corresponding "true probability" P(detector with setting a gets result +1, detector with setting b gets result +1), then the sample average of all the products of measured pairs will be close to the expectation value. And the law of large numbers says that the measured fractions are likely to be close to the true probabilities for a reasonably large number of trials (a few thousand or whatever), even if the number of trials is small compared to the number of possible values of λ so that the frequencies of different λi's in the particles they sampled were very different from the frequencies in the limit of an infinite number of trials, which is what is given by the probability distribution on λ. Do you disagree with that "even if"? If so, this might be a good time for you to finally address the "coin-flip simulation" argument from post #1214 (http://www.physicsforums.com/showthread.php?p=2831006#post2831006) which you never responded to.
If it is a very good estimate, then the probability distribution of λ in their sample will not be significantly different from the true probability distribution of λ. A representative sample is one in which those two probabilty distributions are the not significantly different. That is why the fair sampling assumption is made!
The fair sampling assumption discussed on wikipedia (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Detection_effic iency_loophole_and_the_fair_sampling_assumption) doesn't say anything about the full set of all hidden variables associated with the particles, it just says the fair sampling assumption "states that the sample of detected pairs is representative of the pairs emitted", i.e. if 2000 pairs were emitted but only 1000 pairs were detected and recorded, then if 320 of those pairs gave result (+1 on detector with setting a, -1 with detector with setting b), then the fair sampling assumption would say that about 640 of the pairs emitted would have been predetermined to give result (+1 on detector with setting a, -1 with detector on setting b). Aside from those two predetermined results, the fair sampling assumption doesn't assume anything else about the hidden variables in your sample being "representative" of all those emitted.
Again that is the whole point. Without knowing λ, the experimenters have no way of making sure that the sample they used is representative, the best they can do is ensure that empirical probability distributions in the datasets used to calculate their three terms are not significantly different. And they can make sure of that by sorting the data the way I described. In that case, Bell's inequality is guaranteed to be obeyed. So they can not make sure of it, but they can verify it.
On the subject of "resorting", I haven't yet responded to your post #1224 (and I do want to get back to that one), but your reply there was your usual unending supply of negativity and hostility about everything I said, with no comment along the lines of "yes, it looks like your example finally indicates that you understand what I mean by 'resorting'" or "no, your example still indicates a misunderstanding, here is where your example needs to be modified". So can you just tell me yes or no, was I right to think that by "resorting" you meant renumbering the iterations on each of the three runs, in such a way that if we look at the ith iteration of runs with settings (a,b) and (a,c) they both got the same result for setting a, if we look at the ith iteration of runs with settings (a,b) and (b,c) they both got the same result for setting b, and if we look at the ith iteration of runs with settings (b,c) and (a,c) they both got the same result for setting c?

If this is correct, then I'll just note that even if you can do this resorting, it doesn't guarantee that the "hidden triples" associated with the ith iteration of all three runs were really the same, much less that the value of λ (which can encompass many more details than just three predetermined results for each setting) was really the same on all three. Of course if you can do such a resorting it shows that it is hypothetically possible that your dataset could have been generated by hidden variables which were the same for the ith iteration of all three runs, and if you can do such a resorting it also guarantees that your data will obey the inequality. Is that all you're claiming, or are you claiming something more about the significance of "resorting"?
I hope that you will find time out of your busy schedule to comment on this example I presented:
For example:

Let us define A(a,λ) = +/-1 , B(a,λ) just like Bell and say that the functions represent the outcome of two events on two stations one on earth (A) and another (B) on planet 63, and in our case λ represents non-local mystical processes which together with certain settings on the planets uniquely determine the outcome. We also allow in our spooky example for the setting a on earth to remotely affect the choice of b instantaneously and vice versa. Note in our example, there is no source producing any entangled particles, everything is happening instantaneously.

The expectation value for the paired product of the outcomes at the two stations is exactly the same as Bell's equation (2). If you disagree, explain why it would be different or admit that the physical assumptions are completely peripheral.
First of all, it's a physical assumption that the result A on Earth depends only on a and λ and can therefore be written A(a,λ)--if you allow "spooky" influences, why can't the result A on Earth depend on the setting b, so that if on Earth we have setting a1 and hidden variables in state λ5, and on the other planet the experimenter is choosing from settings b1 and b2, then it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1? It's also a physical assumption that the measurement result is a deterministic function of the detector settings and some set of hidden variables prior to measurement, it could be a probabilistic function like P(A=+1|a1, λ5)=0.7 and P(A=-1|a1, λ5)=0.3. It's also a physical assumption that the probability distribution function on different values of λ, which I write as P(λi) in the case that λ takes a discrete set of values and ρ(λ) in the case that it takes a continuous set, would be the same in the integrals for E(a,b) and E(b,c) and E(a,c)--it's quite conceivable that the true probabilities (in the frequentist sense) of different values of λ could change depending on what detector settings were chosen. All the above violations of Bell's assumptions, which would make his equations incorrect, could easily be programmed into a computer simulation which would produce lists of pairs for different detector settings. So it's clearly not true that the equations in Bell's paper require no physical assumptions to ensure their validity.

charlylebeaugosse

Aug10-10, 01:35 PM

So we went from "Is action at a distance possible as envisaged by the EPR Paradox." to a discussion of Bell and in particular whether some experiments provide an experimental verification of the violation by QM.

Of course, Bell's inequality do not apply to QM and we all understand that what this is all about is the conjunction of "locality" and "realism". To make the experiments possibly meaningful, you need a special form of the Boole inequalities (no misprint here) and this is what CHH provides, together with supplementary hypotheses, such as fair sampling (also discussed by CHSH, Bell, and others). So Clauser-Aspect-ect. type of experiments "prove" (in a physicist's sense) that:
IF local realism
1) Holds true,
2) Has some extra properties,
THEN, assuming furthermore that:
3) the "loopholes" are irrelevant,
one of 1), 2) and 3) has to be relinquished.

In fact these experiments mostly prove QM right once more, and where there was no much surprise, except perhaps for Louis de Broglie, but after all that he has given to science, one can perhaps forgive a small blunder, isn't it? The sad thing is that people like Aspect refuse to see conservation rules and Malus law where they belong as this would trivialize a bit the
context of the experiments. Sad also the mis-representation of Einstein after so much work has been done by Jammer, Fine and others. I invite everyone to read the Bell 1964 paper on the inequalities and the EPR paper, and what Einstein writes about de Broglie and Bell, and what Rosen wrote about HV in the 50th anniversary of EPR meeting, and compare that to what Bell write of the content of EPR and the beliefs and intents of the authors. I got into QM because I did find non-locality beautiful, and then I opened the literature and find collections of misrepresentations of the truth (something almost equal to a 3 letters word that starts with an L and ends with an .... but I digress).

Now, telling that 1) is false could just mean that "realism" is false, the quasi claim of the paper I have mentioned and that has been now documented, or that "locality is false", unfortunately now the leading belief among physicists related to QM (or so it seems, despite the opinion of Sir Anthony Leggett, an authority on most of what we discuss here), or that both are false. I believe that only locality is false but I'd like proofs, even if the Europ. J. of Phys. paper which I have mentioned as an indication to this effect turns out to be a proof acceptable by physicists (the realm of proofs being logic and math, or math including logic).

I do believe that further experiments can be designed to make the truth of "realism" ( i.e., [\I] I recall pre-existence of observable values to measurement: in fact I prefer "weak realism" which means that but before any time when some measurement is actually made, which is the minimal assumption in the realism vein to allow the proof of a Bell Theorem)) an issue in physics and no more only in philosophy (of course some beliefs would have to be involved as physics is not pure math). Hence I believe that discussing too much Bell's theory is a distraction (Bell was a realist and the net effect of his paper, which should have been progress, has a big part of regression as NAIVE hidden variables, of a type that Einstein would never had accepted (he found the theories of de Broglie and Bohm very naive). Reasonable Hidden Variable (HVs) should be compatible with the uncertainty principle and should not give meaning to two conjugate variables at once. No Bell theorem could be written with such HVs. Similarly, if the EPR condition of reality had been taken seriously by Podolsky who wrote the EPR paper, meaning if all quantities would me measured somehow, at most 2 spin projections would make sense in the EPRB context.
Perhaps the worst "crime" of Bell was to start his 1964 inequalities paper by a misquotation of the EPR paper, then answering in a dishonest way to Jammer who had noticed that Einstein (at least after 1927) never supported HVs (at least the naive one that Bell let us assume the authors supported)). Even if in 1964 Bell did not know ho wrote the EPR paper nor Einstein's discussion of the completeness problem, he learned it or did hard work to avoid that. We are now (and not because of Bell only of course) in a situation where the level of honesty in citations and even quotes in physics is so low that no other discipline would resist. This at a time when many groups attack science violently.

But the question was:
"Is action at a distance possible as envisaged by the EPR Paradox."?
To that I would answer that Einstein version of the EPR matter does not involve action at a distance (the paper neither, but it is so oddly written as detailed, for instance by Arthur Fine in The Shaky Game..): what one has there is conservation, and much weaker in fact than in the classical case when in case of conservation, say of the magnetic momentum, all its projection would be conserved where conjugacy consideration prevent that in the quantum case. Even if you accept non-locality (for which no evidence has been given and which should probably be once and for all eliminated, except perhaps to let one have even better arguments that what one has now), nothing like action at distance is enabled by EPR nor by the context of EPR. At best, the value of some observables would depend of the setting of apparatus that is used so that there is space separation between the apparatus measurement and the related observables measurements, BUT it has been many time proved that such effect of non-locality (assuming again that non-locality holds true) would not permit any sueprluminal message transmission). Now it follows from the paper that I have cited from Europ J of Phys that if there are HVs then if for these HVs Non-locality does
not enable Super-Luminal Message transmission, then some Boole (or Bell) type inequalities hold true without assuming locality. So non-locality does not cure anything and one can thus know that the cause of inequalities violated by physics is nothing but "realism" (or even "weak realism") so that non-locality (as well as "weak realism" goes away from physics. Remains to explains how the macrocosm generates realism, and also geometry. In brief, to the question:

"Re: Is action at a distance possible as envisaged by the EPR Paradox."? (the "?" is mine, but otherwise, it's not a question), I answer:

"This is not a rightful question as there is no action at a distance envisaged by the EPR Paradox."

Furthermore, any sort of "action at a distance possible as inspired by miss-reading of the EPR Paradox" and that would permit as much as super-luminal message transmission is impossible according to physics as we know it in 2010.

FACT (to support what comes after "Furthermore, any sort...": Some extremely good physicists and mathematicians (active and/or retired) are crackpots (and I have belonged for years to both professions, so that I witnessed the oddest scenes I could ever imagine). Since rumors do not even require a good scientist near the origin of said rumor, anything that sound weird should be [I]a-priori considered as weird until proven otherwise.

DrChinese

Aug10-10, 02:25 PM

1. I invite everyone to read the Bell 1964 paper on the inequalities and the EPR paper, and what Einstein writes about de Broglie and Bell...

2. ...has a big part of regression as NAIVE hidden variables, of a type that Einstein would never had accepted (he found the theories of de Broglie and Bohm very naive). Reasonable Hidden Variable (HVs) should be compatible with the uncertainty principle and should not give meaning to two conjugate variables at once. No Bell theorem could be written with such HVs. Similarly, if the EPR condition of reality had been taken seriously by Podolsky who wrote the EPR paper, meaning if all quantities would me measured somehow, at most 2 spin projections would make sense in the EPRB context.

3. Perhaps the worst "crime" of Bell was to start his 1964 inequalities paper by a misquotation of the EPR paper, then answering in a dishonest way to Jammer who had noticed that Einstein (at least after 1927) never supported HVs (at least the naive one that Bell let us assume the authors supported)). Even if in 1964 Bell did not know ho wrote the EPR paper
...

1. I think the EPR & Bell source papers are wonderful, I have copies available on my site for those who wish to read them. I have read a bit here or there about Einstein on Bohm (I am sure you didn't mean Bell), but perhaps you are referring to some specific comnment? I am not sure I follow your point here.

2. Einstein gave us the "the moon is there when not looking at it" comment, so I am not sure I quite agree if you are saying that Einstein was not a "naive" realist. (Although I personally don't care for the use of the word naive as it comes off as an insult.) But I would be interested in a quote that clearly expresses a) what realism looks like which is NOT naive; and more importantly b) any evidence Einstein subscribed to that view. Given his "moon" comment, which is pretty clearly in the "naive" school.

In my mind: the HUP flies in the face of all versions of realism. I mean, the word just doesn't have much meaning if you reject "simultaneous elements of reality" as too naive.

3. Einstein's name was on the 1935 paper, not really sure why there would be a need to back away from it. It was a great paper, and is quite important even while being wrong (in its final conclusion).

charlylebeaugosse

Aug10-10, 02:25 PM

Not sure I would agree here that delayed choice experiments are not relevant. What is the meaning of EACP if you have the future affecting the past? And you cannot be certain that is not happening once you look at those experiments.

I personally cannot see that EACP is a "weaker" assumption than locality. I mean, it seems a subjective assessment.

DrChines, thanks for the answers: once more, I reply first to the last "question" (in fact you made a statement, but there is an implicit question, I presume). In what follow, I start from the view-point that Locality is an hypothesis stronger that Non-locality. The (or should I say "one" ?) proof that the EACP assumption is weaker than Locality lies in the fact that when assuming the EACP, one can ALSO either assuming Locality, or Non-Locality, or not make any assumption of that sort. If one assumes the EACP and non-locality, it becomes trivial not only to prove that the EACP is weaker than Locality, but also that most of the correlations that are easy to compute when assuming Locality are not any more eas to compute, and in fact cannot at all be evaluated from QM, weak realism, the EACP and Non-locality (for instance the quantity of the for <Y,X'> or <Y',X> where a prime means that tehnobservable only exist by realism and X, Y correspond to teh two observation stations (say Alice has X and X', Bob has Y and Y'). The paper that I have cited mention several comparisons of the EACP with Locality. For instance, in a universe without "realism",
the negation of the EACP permit Super Luminal Signaling while it is known that the contrary of Locality does not (or there would probably be more supporters of Einstein against Non-locality). I will not try to copy that paper here.

As for the story of delay, I meant delayed erasure (including thus the supposed realisation of Wheeler's experiment by Jacques et al which in fact uses delayed erasure). As I said, Cthugha has beautifully explained the delayed erasure of Kim et al: there erasure only permits the re-appearance of a structure in the coincidence between D2 OR D3 and D1.
It is a co-structure so to speak that one gets by erasing the marking of the paths. Indeed, if one would consider D2+D3 vs D1, the wavy structure in the coincidence count would be washed out. This couples with a weakness of the Copenhagen interpretation to provide a weird story, but you can even stick to Copenhagen and realize that all funny effects of delays are illusory (I mean, the funny-ness, so to speak, is illusory, the effects are there, but need to be clearly understood, and again, Cthugha did a great work on that). In fact, he, you and a few others convinced me by the quality of the posts, to come back to this Forum after trying it for one day or so some time ago and convincing myself then that it was useless. Now I understand that perhaps I got my first copies of Bell 1964 and EPR thanks to you (which is true if you did post them as the sources, initially with a very heavy copy of Bell's paper): if so, I have to (and I do) thank you very much as this is what convinced me that the reason why I initially decided to come back to my youth-dream -subject was, essentially at least,.... a fraud. I have seen some pieces of you where you defend what I also consider as what needs to be defended, and feel confident that here were we seem to disagree, we will end up on the same side once I put my act/words together. As for Wheeler type delay, we need another thread as, contrary to what happens for delayed erasure, one has to slightly take on Copenhagen.
I do not know how to meet you on another thread that you or me would create.
b.t.w., there are some questions that I would like to post and that may be new threads.
I will now look into that as, indeed, for Wheeler's delay proper, there is much to say that I do find crucial for the overall story, and that would probably warrant another thread if such a thread is not there yet (assuming that details on Bell type theory do belong to (naive) questions on EPR such as "Is action at a distance possible as envisaged by the EPR Paradox?" (where I have added a "?" myself to have a bona-fide question, to which I have proposed my answer in segment I have just posted).

DrChinese

Aug10-10, 02:33 PM

1. Now I understand that perhaps I got my first copies of Bell 1964 and EPR thanks to you (which is true if you did post them as the sources, initially with a very heavy copy of Bell's paper):

2. I do not know how to meet you on another thread that you or me would create.
b.t.w., there are some questions that I would like to post and that may be new threads.

1. You are welcome if so! I used to have a worse (darker) copy and then someone helped me get a better one.

2. We could discuss the Tresser paper and related in a new thread, no prob there. If you want I can start it. I tend to hold onto locality so the Tresser ideas are pretty interesting. His work has been on my radar for a while although I have not read closely.

charlylebeaugosse

Aug10-10, 03:34 PM

1. I think the EPR & Bell source papers are wonderful, I have copies available on my site for those who wish to read them. I have read a bit here or there about Einstein on Bohm (I am sure you didn't mean Bell), but perhaps you are referring to some specific comnment? I am not sure I follow your point here.

2. Einstein gave us the "the moon is there when not looking at it" comment, so I am not sure I quite agree if you are saying that Einstein was not a "naive" realist. (Although I personally don't care for the use of the word naive as it comes off as an insult.) But I would be interested in a quote that clearly expresses a) what realism looks like which is NOT naive; and more importantly b) any evidence Einstein subscribed to that view. Given his "moon" comment, which is pretty clearly in the "naive" school.

In my mind: the HUP flies in the face of all versions of realism. I mean, the word just doesn't have much meaning if you reject "simultaneous elements of reality" as too naive.

3. Einstein's name was on the 1935 paper, not really sure why there would be a need to back away from it. It was a great paper, and is quite important even while being wrong (in its final conclusion).

On 1. (Just discovered that it is easier to answer first t the last question but that you can do that respecting there numbering in the way the answers are displayed. Indeed I should perhaps use WORD: any advice????) I was just meaning a link giving access to the paper of Bell and EPR, where originally at least (when I used that link), the copy of Bell was an heavy image from a scan with some markings. This was my own first access to the original versions of Bell and EPR (as I had no access to an university library), and I thank very much whoever posted these access (in a page telling about EPR, or EPR-Bohm, or Bell, I cannot remember).

On 2. Not sure if you believe that the moon is not there when you do not look a it: if, as I assume from what you write elsewhere, you do believe that the moon is here even when nobody looks at it BUT yet think that Einstein's question to Pais was naive, then I will explain. If you do not believe that the moon is here when.... then, I give up (but again, I trut you have the sane point of view, like A.E. indeed). I need your help: what is HUP?
(sorry for he low level of this question, but I prefer to understand all that is written). In fact, even if I understood HUP, I would still have problems with "the HUP flies in the face of all versions of realism". Please remember that the effective language of science is not English, but broken English as many of us did not grow up in an English speaking country.

On 3. See the book of Fine and especially, read what Einstein wrote on that (starting in about 1933 when he already used the word paradox). If the paper is beautiful, it is hard and had hidden in it a "proof" that QM is false, causing part of the difficulty to understand Bohr's answer. Einstein's standards were such that he would not go public on his opinion of the EPR paper, but see Fins's "The Shaky Game" and use that to find other writings by S.E. himself. The paper EPR is interesting but Einstein's treatment of the completeness question is at an Einsteinian level. This being said, on time I expect to:
-(a) Explain why the main official thesis of EPR is right
- (b) Explain the relation of EPR with another paper (Einstein, Tolman, Podolsky 1931) so that in some sense, Podolsky is also right in his main agenda.
-(c) Explain why a proper use of the reality element (in the spirit of what is written before they are defined) would not permit a Bell-type result, while the way Podolsky uses the elements of reality allowed Richard Friedberg to get such inaqualities (at a time Bell's work was known by a minority: see the main book by Jammer on QM).
- (d) Defend that the completeness issue is no more relevant and try to explain why it was then, especially for Einstein.

All that I promise is a bit of history and a bit of physics. I would not like to spend too much time on history, so that I may take some time to deliver (a) to (d). I have not thought at the ordering f these points, hence do not know in which order I will answer, not if some other issues will have to be covered as well to make my exposition comprehensible (harder because English is not my native tong, as the English speakers will have caught).

Besides:

- I hate "your" statement about "Einstein's name was on the 1935 paper": it has happened to me to have a paper submitted without my imprimatur: it is VERY painful. I write "I hate" because it is not only your statement: many people have told me the
same thing, but nobody for whom a similar experience was painful.

- As for your "not really sure why there would be a need to back away from it", you'll see in what I have quoted above (probably a very incomplete list in fact) that this is worth the pain and the time.

- As for your "It was a great paper, and is quite important even while being wrong (in its final conclusion)", I'll defend the conclusion in the way I said, but the fact that it was a great paper cannot be (reasonably) disputed, be it by its impact on Bohr, but of course, there is much more as we know. (Note: You may know that in 1985, Rosen considered the proof in the paper correct but the paper incorrect because he had been convinced that physics is non-local, which is why I hate the way presented the whole story along the years, often keeping his hidden agenda close to his vest to the point that Wigner considered Bell 1964 as the nicest proof of the non-existence of HVs where Bell was laying a stone to build the "non-locality and realism" household. btw, the paper by Wigner on Bell's Theorem is worthwhile reading, be it only because the preferred proof on no HV of his close friend John von Neuman can probably only be found in that paper (in a note), i.e., in particular it was not the pseudo-proof proven to be wanting by Bell in the first paper that he wrote on HVs.

DrChinese

Aug10-10, 05:35 PM

(harder because English is not my native tong, as the English speakers will have caught).

Your English is fine. :smile: HUP is my abbreviation for the Heisenberg Uncertainty Principle.

If you have any links to the material you are referencing, that would be helpful. Or alternately if you can give verbatim quotes with a little more context. Thanks!

I don't believe the moon is there when it is not being looked at, and I mean that strictly in the sense that I deny the existence of simultaneous elements of reality a la EPR. So if that puts me in the "hopeless" category for you, well, so be it. :smile:

I do believe the official conclusion of EPR is correct: the part about the Alice's reality is dependent on the nature of the observation by Bob. But they considered this unreasonable (an opinion which turned out to be experimentally incorrect a la Aspect).

RUTA

Aug10-10, 06:20 PM

On 2. Not sure if you believe that the moon is not there when you do not look a it: if, as I assume from what you write elsewhere, you do believe that the moon is here even when nobody looks at it BUT yet think that Einstein's question to Pais was naive, then I will explain. If you do not believe that the moon is here when.... then, I give up (but again, I trut you have the sane point of view, like A.E. indeed).

I'm with DrC, I also don't believe "the Moon is there when nobody looks." By "when nobody looks" I mean "when not interacting with anything." [Some people use the term "screened off" for this situation.] Perhaps those who believe otherwise have met Harvey :smile:

DevilsAvocado

Aug10-10, 06:45 PM

Hey, look at my post count!

+3,000 posts!! :cool: Respect and congratulations!

http://www.webweaver.nu/clipart/img/misc/fireworks/fireworks3.gifhttp://www.webweaver.nu/clipart/img/misc/fireworks/fireworks.gif

charlylebeaugosse

Aug10-10, 06:47 PM

Your English is fine. :smile: HUP is my abbreviation for the Heisenberg Uncertainty Principle.

If you have any links to the material you are referencing, that would be helpful. Or alternately if you can give verbatim quotes with a little more context. Thanks!

I don't believe the moon is there when it is not being looked at, and I mean that strictly in the sense that I deny the existence of simultaneous elements of reality a la EPR. So if that puts me in the "hopeless" category for you, well, so be it. :smile:

I do believe the official conclusion of EPR is correct: the part about the Alice's reality is dependent on the nature of the observation by Bob. But they considered this unreasonable (an opinion which turned out to be experimentally incorrect a la Aspect).

I'll think about an answer that may be helpful for you and for people who believe that the moon pre-existed humans presence on earth. I'll hgave also to defend EPR. As for teh quotes, before I am organized, I can be asked for references when I am not precise enough giving them... But I'll need some time.

DevilsAvocado

Aug10-10, 06:50 PM

Bell's words:

"-My theorem answers some of Einstein's questions in a way that Einstein would have liked the least."

responding to Einstein's:

"-On this I absolutely stand firm. The world is not like this."

Yes, this is very true. Einstein’s own argument boomeranged on him:
no action on a distance (polarisers parallel) ⇒ determinism
determinism (polarisers nonparallel) ⇒ action on a distance

But to be fair we must say that also Niels Bohr was somewhat 'wrong'. If it turns out that nonlocality is fact, then QM must be considered 'incomplete'... or ...?:uhh:?

There is no doubt in my mind that Einstein, if he was alive, would have accepted the work of Bell as starting point for "something new", not a starting point for an old man to get 'grumpy'. :wink:

DevilsAvocado

Aug10-10, 06:54 PM

Great post!

Thanks DrC.
(And don’t forget: I’ve learned mostly everything from you, RUTA, JesseM and the other very skilled people here on PF. :smile:)

P.S: very skilled <> billschnieder :zzz:

DevilsAvocado

Aug10-10, 07:11 PM

Bill, give it up, I don't know where you're getting the ideas you espouse here, but JesseM is tearing them apart. I'll say it again, you can post in bulk, but it doesn't change that your posts are rambling and borderline-crackpot, whereas JesseM is sticking to the science.

I agree, of course, but trying to talk reasonable to Bill is a waste of time. He lives in his own little bubble; firmly convinced he represents the "universe", when the fact is that he’s totally lost and totally alone in his "reasoning".

As usual, Bill misunderstands everything about everything, and he for real thinks he has an undisputable right to do what he wants here at PF, and he apparently don’t understand simple English. When I informed him about the Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=414380), and that: "Poorly formulated personal theories, unfounded challenges of mainstream science, and overt crackpottery will not be tolerated anywhere on the site."

His answer was, of course, "brilliant and out of this world":
Let us see what the document you linked to says:
When posting a new topic do not use the CAPS lock (all-CAPS), bold, oversized, or brightly colored fonts, or any combination thereof. They are hard to read and are considered yelling. When replying in an existing topic it is fine to use CAPS or bold to highlight main points.

What can one say? The "genius" has spoken. :biggrin: + :cry: + :grumpy:

But don’t worry nismaratwork, this is the fact:
Use of this Forum and your comments is not a right. It is a privilege granted you by Physics Forums under the terms of this agreement and can be revoked at any time without warning.

And sooner or later we will see this:

http://i38.tinypic.com/fomx6q.png

He’s getting cocky...

DevilsAvocado

Aug10-10, 07:33 PM

The Effect After Cause Principle (EACP) states ONLY that:
For any Lorentz observer O, once an effect E of cause C is observed by observer O, no fiddling with C can change E.

Okay charly, thanks for info.

How do EACP handle more than one observer in different frames of reference and RoS?

DevilsAvocado

Aug10-10, 08:05 PM

I'm with DrC, I also don't believe "the Moon is there when nobody looks."

I guess I agree... one thing that bothers me though... How does the Moon know if someone is looking??

I mean, it’s no problem for the Owl Nebula, it has eyes!

http://seds.org/messier/Pics/More/m97rosse.jpg

:smile:

billschnieder

Aug10-10, 11:07 PM

Yes, Bill. Would you deny, for example, that a physical process that had P(++)=0.3, P(+-)=0.2, P(-+)=0.15, and P(--)=0.35 (with all of these numbers being the frequentist probabilities that would represent the fraction of trials with each value in the limit as the number of trials goes to infinity) could easily generate the following results on 4 trials?

I gave you an abstract list. No mention of anything such as trial. No mention of anything such a physical process. I asked you to give me the probability of one of the entries from the list, and you told me it was impossible despite the fact that this is what is done everyday in your favorite frequentist approach to probability. When ever you say the probability of Heads and Tails is 0.5 you are doing it, whenever you say the probability of one face of a die is 1/6, you are doing the exact same thing you now claim is impossible. Go figure.

I already gave you the answer which is 1/4. Now you want to ask me about a completely different question than the one I asked you.

Note that the wikipedia article says "close to the expected value", not "exactly equal to the expected value". And note that this is only said to be true in a large number of trials, the article does not suggest that if you have only four trials the average on those four trials should be anywhere near the expectation value.

First of all, you were the one arguing that Bell's equation (2) is not a definition of expectation value which according to you is defined according to the law of large numbers:
true probabilities are understood to be different from actual frequencies on a finite number of trials in the frequentist view, and I don't think there's any sensible way to interpret the probabilities that appear in Bell's proof in non-frequentist terms. An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity, and likewise the ideal probability distribution ρ(λi) would in frequentist terms give the fraction of all trials where λ took the specific value λi, again in the limit as the number of trials goes to infinity. Then you can show theoretically that given Bell's physical assumptions, we can derive an inequality like this one:
So I see an admission that you were wrong here.

Secondly, I gave you an abstract list, no mention of trials. The context of the question is entirely within the list you were given. The list is the population. There is no need for any trials. This is the frequentist view. With a coin or a die, you can give a probability without any trials. You do not need a single trial. You are way way of base here.

Finally, note that in the forms section of the article they actually distinguish between the "sample average" and the "expected value", and say that the "sample average" only "converges to the expected value" in the limit as n (number of samples) approaches infinity. So, it seems pretty clear the wikipedia article is using the frequentist definition as well.
Again, nothing to see here. No mention about "samples" in my question to you, just an abstract list, I did not expect you to use any other definition than the frequentist one. My abstract list I gave you is the population just like (Heads, Tails) is the population for a coin, and (1,2,3,4,5,6) are the population for a die. The true probability is the one in the population. The law of large numbers is only meaningful for samples taken from the population. You can visualize it by thinking that if you would randomly pick an entry from the the list I gave you, the relative frequency in these trials will approach the true probability in the list as the number of trials tends towards infinity. But I gave you an abstract list and asked you for the true probability of the list, and you dodged it because you saw the impact of the question to your ridiculous position.

Here the wikipedia article is failing to adequately distinguish between the "mean" of a finite series of trials and the "mean" of a probability distribution. If you think the expectation value is exactly equal to the average of a finite series of trials, regardless of whether the number of trials is large or small, then you are disagreeing with the very wikipedia quote you posted earlier from the Law of Large Numbers page
Wah JesseM, who said anything about trials! Now according to you it is the wikipedia article that is "failing"? On the contrary, it is you who is failing to understand basic statistics and probability theory. The question I asked you was the following:

You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product.

and your answer was:

It's impossible to write down the correct objective/frequentist expectation value unless we know the sample space of possible results

The law of large numbers says if you would randomly pick a large number of pairs from our given abstract list, the average value will get close to the true expectation value as the number of pairs you pick tends towards infinity. It does not say the true expectation value for the list can not be known unless the size of the list is infinity. The true expectation value for the list I gave is <xy>. This is the value, you will approach if you were to randomly pick a very large number of pairs from our list and calculated their average. Capice?

billschnieder

Aug10-10, 11:07 PM

According to you, would it be more correct to write "the average of the results obtained from any number of trials would be exactly equal to the expected value"?

No! You are not paying attention, and it is you who is confusing the theoretical and the empirical. You keep bringing up the word "trials" which is tripping you up. Just because I give you an abstract list does not mean the list represents "trials" in an experiment. If I wanted the list to represent results of trials, I would state that clearly. For a coin N = 2, for a die, N=6, yet you can still calculate the expectation value without any infinite trials! You still do not get the distinction between a sample from a population, and a population. In statistics, if you are given the population, you can calculate the true probabilities without any trials. It is done every day in the frequentist approach, which you claim to understand!

Your arguments may have been assuming the "finite frequentist" view, but as I said that's not what I'm talking about. I'm talking about the more common "frequentist" view that defines objective probabilities in terms of the limit as the number of trials goes to infinity.
So now you are no longer talking about "frequentist view" but some special version of the frequentist view? This is just plain wrong, as the section of Wikipedia I quoted to you clearly explains. The law of large numbers gives you an approximation to the "true" probability and that approximation get's more accurate as the number of trials increases. It does not define an objective probability. The objective probability is defined by the actual population content and the population size can be any number.

What do you mean by "true expectation value"? Are you using the same definition I have been using--the average in the limit as the number of trials goes to infinity--or something else?
Bah! Do you have short-term memory issues or something. What have we been discussing these past 5 pages of posts?

Did you not see this definition I posted from Wikipedia: http://en.wikipedia.org/wiki/Expected_value

In probability theory and statistics, the expected value (or expectation value, or mathematical expectation, or mean, or first moment) of a random variable is the integral of the random variable with respect to its probability measure.

For discrete random variables this is equivalent to the probability-weighted sum of the possible values.

For continuous random variables with a density function it is the probability density-weighted integral of the possible values.
...
The expected value may be intuitively understood by the law of large numbers: The expected value, when it exists, is almost surely the limit of the sample mean as sample size grows to infinity.

Also, when you say "it is their only hope", what is "it"?
In case you have forgotten, we are discussin Bell's inequality

|E(a,b) + E(a,c)| - E(b,c) <= 1

According to Bell, E(a,b), E(a,c) and E(b,c) are "true" expectation values with a uniform ρ(λ) for all three terms, or if you prefer "objective" expectation values for the paired product of outcomes at two stations. Those expectation values are defined by Bell in equation (2) of his paper, using the standard mathematical definition of expectation values for continous variables.

Experimenters measure "something". From this "something" they calculate certain empirical expectation values E(a1,b1), E(a2,c2) and E(b3,c3) where the numbers corresponds to the run of the experiment. They then plug these empirical expectation values into the LHS of the above inequality and obtain a value which they compare with the RHS and notice that the inequality is violated.

In case you forgot, this whole discussion is about whether those empirical expectaion values are appropriate terms to be used in Bell's inequality. If those empirical expectation values are not good enough estimates of the true expectation values, they are not good enough to be used since Bell's inequality will not guaranteed to be obeyed. But without knowing anything about the λ's, it is not possible to design experiments which will ensure that the expectation values are good enough. So the only hope left for experimenters doing such experiments is to verify whether the data they obtained in their experiments at least provides a uniform ρ(λ) for all three terms, by re-sorting the datasets of pairs together. If it does not, Bell's inequality can not be applied to the data, if it can, Bell's inequality MUST be obeyed.

billschnieder

Aug10-10, 11:09 PM

billschnieder

Aug10-10, 11:11 PM

So can you just tell me yes or no, was I right to think that by "resorting" you meant renumbering the iterations on each of the three runs, in such a way that if we look at the ith iteration of runs with settings (a,b) and (a,c) they both got the same result for setting a, if we look at the ith iteration of runs with settings (a,b) and (b,c) they both got the same result for setting b, and if we look at the ith iteration of runs with settings (b,c) and (a,c) they both got the same result for setting c?
Yes.

If this is correct, then I'll just note that even if you can do this resorting, it doesn't guarantee that the "hidden triples" associated with the ith iteration of all three runs were really the same, much less that the value of λ (which can encompass many more details than just three predetermined results for each setting) was really the same on all three.
I already answered this:

Every pair of outcomes at those angles is deterministically determined by the specific λ being realized for that iteration. So if for example we had only 5 possible λ's (λ1, λ2, λ3, λ4, λ5), the only possible outcomes are (++, +-, -+, --) which means some of the λ's must result in the same outcome. If say λ5 and λ3 each result in the same outcome (++) deterministically, and each of them was realized in the experiment exactly once, when you resort it, it doesn't matter whether the (++) at the top of the resorted list corresponds to λ5 or λ3 for the following reasons. If in your large number of iterations, λ5 and λ3 are fairly represented, you will still have the right number of (++)'s for both λ5 and λ3 and it doesn't matter if the specific (++) you got at the top is a λ5 ++ or a λ3 ++. Also, if for the three angles under consideration a,b,c a number of λ's deterministically resulted in the same outcomes for (a,b), (b,c) and (a,c) those lambdas are effectively equivalent as far as the experiment is concerned and you could combine them, updating the combined P(λ) appropriately. Finally as clearly explained in my posts #1211 and #1212, being able to sort the data is a test to see if the data meets the mathematical consistency required by Bell's derivation, in which the (b,c) term is derived by factoring out the b from the (a,b) term and factoring out the c from the (a,c) term and multiplying them together. Such factorization imposes a consistency requirement that unless you can do that, the inequality can not be derived and any data which can not be factored likewise, is mathematically incompatible with the inequality.

Of course if you can do such a resorting it shows that it is hypothetically possible that your dataset could have been generated by hidden variables which were the same for the ith iteration of all three runs, and if you can do such a resorting it also guarantees that your data will obey the inequality. Is that all you're claiming, or are you claiming something more about the significance of "resorting"?

I am claiming that the derivation of Bell's inequality and the factorization steps involved demand that any datasets of pairs used for calculating the terms for the inequalities, must be resortable as I explained and you understood, and if they can not, Bell's inequality is not guaranteed to be obeyed for no other reason than violation of mathematical consistency requirements. So being able to resort the data, is a necessary condition for the dataset to be usable as a source of terms for the inequality. This does not mean it is a sufficient condition, but it is necessary. You are right that being able to resort does not ensure that ρ(λ), is uniform. However, not being able to resort, is definite proof that ρ(λ) is not uniform. So resorting is a necessary but not necessarily a sufficient condition if ρ(λ) is uniform.

First of all, it's a physical assumption that the result A on Earth depends only on a and λ and can therefore be written A(a,λ)--if you allow "spooky" influences, why can't the result A on Earth depend on the setting b, so that if on Earth we have setting a1 and hidden variables in state λ5, and on the other planet the experimenter is choosing from settings b1 and b2, then it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1?
You did not understand. A(a,λ) is a function that maps a given value of a and λ to an outcome of +/-1. The function has nothing to do with probability. A(a,λ), "a" can depend on "b". All that the notation A(a,λ) = +/-1 means is that given a specific value of "a" and a specific value of "λ", we get a specific value of either +1 or -1. It is a function of two variables not three and there is nothing in the notation itself that should suggest to you that dependence on "b" is not allowed.

then it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1?
Wrong. "a1" depends on "b2" means that if you looked at how the values of "a" and "b" varied with time after the fact, it will not be random, but certain values of "a" will always be paired with certain values of "b" due to the instant communcation when the settings were being made. It doesn't mean a specific value of "a" will give a different result depending on which value of "b" existed on the opposite side.

It's also a physical assumption ...
You completely missed the point. Despite the fact that the "physical assumptions" in this example are completely contrary to Bell's, we still obtained the exact same expression for the expectation value of the paired product. Which means the "physical assumptions" are peripheral.

JesseM

Aug11-10, 01:23 AM

I gave you an abstract list. No mention of anything such as trial. No mention of anything such a physical process. I asked you to give me the probability of one of the entries from the list, and you told me it was impossible despite the fact that this is what is done everyday in your favorite frequentist approach to probability.
Not if we are excluding "finite frequentism", which I already told you I was doing. If you want to quibble over terminology, I'll just bypass that by using the term "limit frequentist probability" to refer to the notion of probability I have been using consistently throughout this discussion, where a "limit frequentist" probability is understood to mean the frequency in the limit as the sample size goes to infinity. Does your list of four give us enough information to know the frequency of ++ in the limit as the sample size goes to infinity? If not, then there is not enough information to estimate the "limit frequentist probability".
When ever you say the probability of Heads and Tails is 0.5 you are doing it, whenever you say the probability of one face of a die is 1/6, you are doing the exact same thing you now claim is impossible. Go figure.
No, in those cases I am just using the physical symmetry of the object being flipped/rolled to make a theoretical prediction about what the limit frequency would be, perhaps along with the knowledge that empirical tests do show each option occurs with about equal frequency in large samples, and that the law of large numbers says there is only a small probability the frequency in large samples would differ much from the "limit frequentist probability"
I already gave you the answer which is 1/4.
Yes, and that answer is incorrect if we are talking about the "limit frequentist probability", as I already made clear I was doing.
Note that the wikipedia article says "close to the expected value", not "exactly equal to the expected value". And note that this is only said to be true in a large number of trials, the article does not suggest that if you have only four trials the average on those four trials should be anywhere near the expectation value.
First of all, you were the one arguing that Bell's equation (2) is not a definition of expectation value which according to you is defined according to the law of large numbers:
true probabilities are understood to be different from actual frequencies on a finite number of trials in the frequentist view, and I don't think there's any sensible way to interpret the probabilities that appear in Bell's proof in non-frequentist terms. An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity, and likewise the ideal probability distribution ρ(λi) would in frequentist terms give the fraction of all trials where λ took the specific value λi, again in the limit as the number of trials goes to infinity. Then you can show theoretically that given Bell's physical assumptions, we can derive an inequality like this one
So I see an admission that you were wrong here.
Um, how do you figure? The two statements of mine are entirely compatible, obviously you are misunderstanding something here but if you don't explain your "logic" I have no idea why you think they are incompatible. Both statements are defining "expectation value" in terms of a sum of possible outcomes weighted by their "limit frequentist probabilities" (which is what I meant by 'true probabilities' in the first statement), which means they are defined in terms of the limit as the number of trials goes to infinity. The first statement is just pointing out that an average over a finite number of trials is never guaranteed to be equal to the "limit frequentist" expectation value which is defined in terms of the limit as the number of trials goes to infinity, although the larger the finite number, the higher the probability that it's close to the "limit frequentist" expectation value.
Secondly, I gave you an abstract list, no mention of trials. The context of the question is entirely within the list you were given.
Yes, and with that context there isn't enough information to estimate the limit frequentist probability, which is the only notion of probability I want to use because it's the only one I think is relevant to Bell's proof. Anyway, Bell's proof does not assume we have an abstract list, it assumes we have a physical process which can yield various outcomes on as many trials as we care to perform, so do you actually have a point relevant to the discussion of Bell's theorem here, or are you just on a quest to prove that I "don't understand probability"?
You can visualize it by thinking that if you would randomly pick an entry from the the list I gave you
Well, that's an entirely separate question, because then you are dealing with a process that can repeatedly pick entries "randomly" from the list for an arbitrarily large number of trials. But you didn't say anything about picking randomly from the list, you just presented a list of results and asked what P(++) was.
Here the wikipedia article is failing to adequately distinguish between the "mean" of a finite series of trials and the "mean" of a probability distribution.
Now according to you it is the wikipedia article that is "failing"?
Failing to do the specific thing I said it should do, yes. Do you deny that in probability theory it is commonly understood that there is a difference between the "sample mean" and the "population mean"? (the latter can also be referred to as the 'mean of the probability distribution, and either way it's usually denoted with the symbol \mu) You may have missed the references discussing this distinction which I added in an edit to my post:
(edit: See for example this book (http://books.google.com/books?id=3wCWS4VnLJMC&lpg=PA65&dq=%22population%20mean%22%20%22sample%20mean%22&pg=PA65#v=onepage&q=%22population%20mean%22%20%22sample%20mean%22&f=false) which distinguishes the 'sample mean' \bar X from the 'population mean' \mu, and says the sample mean 'may, or may not, be an accurate estimation of the true population mean \mu. Estimates from small samples are especially likely to be inaccurate, simply by chance.' You might also look at this book (http://books.google.com/books?id=1uLGa4eQ05gC&lpg=PA309&dq=%22population%20mean%22%20probability%20distrib ution&pg=PA309#v=onepage&q=%22population%20mean%22%20probability%20distribu tion&f=false) which says 'We use \mu, the symbol for the mean of a probability distribution, for the population mean', or this book (http://books.google.com/books?id=2JfLi3RKRV8C&lpg=PA115&dq=mean%20%22probability%20distribution%22&pg=PA115#v=onepage&q=mean%20%22probability%20distribution%22&f=false) which says 'The mean of a discrete probability distribution is simply a weighted average (discussed in Chapter 4) calculated using the following formula: \mu = \sum_{i=1}^n x_i P[x_i ]').
The law of large numbers says if you would randomly pick a large number of pairs from our given abstract list, the average value will get close to the true expectation value as the number of pairs you pick tends towards infinity.
Again, you said nothing about "randomly picking" from a list, you just gave a list itself and asked for the probabilities of one entry on that list. If you want to add a new condition about "randomly picking", with "randomly" meaning that you have an equal limit frequentist probability of picking any of the four entries on the list, then in that case of course I agree that P(++)=1/4...well duuuuh! But that wasn't the question you asked.

JesseM

Aug11-10, 01:55 AM

No! You are not paying attention, and it is you who is confusing the theoretical and the empirical. You keep bringing up the word "trials" which is tripping you up. Just because I give you an abstract list does not mean the list represents "trials" in an experiment. If I wanted the list to represent results of trials, I would state that clearly.
Well, excuse me for thinking your question was supposed to have some relation to the topic we were discussing, namely Bell's theorem. It didn't occur to me to think that it had no relation at all to Bell's theorem (where the only "lists" we might deal with would be lists of results from repeated measurements of entangled particles), and that you were just on a quest to prove I "don't understand probabilities" by asking me a bizarre question of a kind that would never appear in any statistics textbook. Can I play this game too? Here's an "abstract list" of letters (or is it a list of words?):

The quick brown fox jumped over the lazy dog

Quick now, what's the probability of "ox"?
For a coin N = 2, for a die, N=6, yet you can still calculate the expectation value without any infinite trials!
Only if you assume by symmetry that it's a "fair" die or coin, in which case you have a reasonable theoretical basis for believing the "limit frequency" of each result would appear just as often as every other one. If you had an irregularly-shaped coin (say, one that had been partially melted) it wouldn't be very reasonable to just assume the limit frequency of "heads" is 0.5.
In statistics, if you are given the population, you can calculate the true probabilities without any trials. It is done every day in the frequentist approach, which you claim to understand!
Not in the "limit frequentist" approach where we are talking about frequencies in the limit as number of times the population is sampled approaches infinity (unless we make some auxiliary assumptions about how the population is being sampled, like the assumption we're using a process which has an equal probability of picking any member of the population)
Your arguments may have been assuming the "finite frequentist" view, but as I said that's not what I'm talking about. I'm talking about the more common "frequentist" view that defines objective probabilities in terms of the limit as the number of trials goes to infinity.
So now you are no longer talking about "frequentist view" but some special version of the frequentist view?
Yes, I think I have explained a bunch of times now that I am talking about "probability" defined as the frequency in the limit as the number of trials (or the 'sample size' if you prefer) goes to infinity. There is also such a thing as "finite frequentism" which just says if you have a finite set of N trials, and a given result occurred on m of those trials, then the "probability" is automatically defined as m/N (see frequency interpretations (http://plato.stanford.edu/entries/probability-interpret/#FreInt) from the Stanford Encyclopedia article on probability for more on 'finite frequentism')...this is not a definition I have ever been using, but I thought perhaps you were, since you gave a list with 4 entries and said the "probability" of an entry that appeared once on the list was 1/4.
This is just plain wrong, as the section of Wikipedia I quoted to you clearly explains.
What is just plain wrong? That there are multiple meanings of "frequentism", and that there is such a thing as "finite frequentism" as distinct from what I'm here calling "limit frequentism"? If you think that's wrong, go read the Stanford Encyclopedia article. If it's some other thing you think I was claiming, can you be specific?
The law of large numbers gives you an approximation to the "true" probability and that approximation get's more accurate as the number of trials increases. It does not define an objective probability.
Sure, that's what I've been saying all along, again with the understanding that by "true" probability I mean the limit frequentist probability.
The objective probability is defined by the actual population content and the population size can be any number.
I don't know what you mean by "defined by the actual population". By "population" do you mean the sample space of possible outcomes, or do you mean a "population" of trials (or picks or whatever) from the sample space? (you may remember from a previous discussion that wikipedia does at times use 'population' to refer to a large set of trials, see here (http://en.wikipedia.org/wiki/Sampling_%28statistics%29#Population_definition)) If you're talking about a population of trials, then the limit frequentist probability would require us to consider the limit as the population size approaches infinity. If you're just talking about the outcomes in the sample space, are you claiming that if there were N outcomes the "objective probability" would automatically be 1/N?
What do you mean by "true expectation value"? Are you using the same definition I have been using--the average in the limit as the number of trials goes to infinity--or something else?
Bah!
Humbug!
Do you have short-term memory issues or something.
Not that I can recall!
What have we been discussing these past 5 pages of posts?
Bell's theorem, and your odd criticisms of it which seem to presuppose a notion of probability different from the limit frequentist notion (for example, at the end of post #1224 you acted as though my comment that we might not be able to 'resort' the data from a finite series of trials in the way you suggested was equivalent to an 'admission' that it is 'possible for ρ(λi) to be different'). Which is why I ask if you are "using the same definition I have been using--the average in the limit as the number of trials goes to infinity--or something else?" I have asked a few times if you are willing to use this definition at least for the sake of analyzing Bell's proof to see if it makes more sense that way, but you have never given me a clear answer. Can you take a quick break from venting hostility at me and just answer yes or no, is this the definition you've been using? And if not, would you be willing to use it for the sake of discussion, to see if the problems you have with the applicability of Bell's results might go away if we assume he was using this type of definition?
Did you not see this definition I posted from Wikipedia: http://en.wikipedia.org/wiki/Expected_value
I saw, but you have a tendency to interpret quotes from other sources in odd ways that differ from how I (or any physicist, I'd wager) would interpret them, like with much of your interpretation of Bell's paper. So can you please just answer the question: are you using (or are you willing to use for the sake of this discussion) the limit frequentist notion of probability, where "probability" is just the frequency in the limit as the number of trials goes to infinity?
Also, when you say "it is their only hope", what is "it"?
In case you have forgotten, we are discussin Bell's inequality

|E(a,b) + E(a,c)| - E(b,c) <= 1

According to Bell, E(a,b), E(a,c) and E(b,c) are "true" expectation values with a uniform ρ(λ) for all three terms, or if you prefer "objective" expectation values for the paired product of outcomes at two stations.
Yes.
Those expectation values are defined by Bell in equation (2) of his paper, using the standard mathematical definition of expectation values for continous variables.
No, the "standard mathematical definition" of an expectation value involves only the variable whose value you want to find the expectation value for, in this case the product of the two measurement results. The standard definition is to take each possible value for this variable (not some other variable like λ), and multiply by the probability of that value, giving a weighted sum of the form \sum_{i=1}^N R_i P(R_i ). In the standard definition would give us:

E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

Bell is not trying to provide a totally new definition of "expectation value", instead he's just giving a physical argument that the expectation value as conventionally understood (i.e. the definition above) would be equal to the expression he's giving in equation (2). But that equation isn't how he "defines" the expectation value, it would just be silly to try to provide a new definition of such a commonly used term.
Experimenters measure "something". From this "something" they calculate certain empirical expectation values E(a1,b1), E(a2,c2) and E(b3,c3) where the numbers corresponds to the run of the experiment. They then plug these empirical expectation values into the LHS of the above inequality and obtain a value which they compare with the RHS and notice that the inequality is violated.
Yes, I agree (although I think 'empirical expectation value' is a confusing phrase, I would just use 'empirical average' or something like that).
In case you forgot, this whole discussion is about whether those empirical expectaion values are appropriate terms to be used in Bell's inequality.
Since the E(a,b), E(b,c) and E(a,c) in Bell's inequality are defined in the conventional way, i.e.

E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...with the probabilities in that equation understood as the "limit frequentist" probabilities, it follows from the law of large numbers that the bigger the sample size, the smaller the probability that there will be any significant difference between the "limit frequentist" expectation values and the empirical averages of this form:

Avg(a,b) = (+1)*(fraction of trials in run where detector with setting a got result +1, detector with setting b got result +1) + (-1)*(fraction of trials in run where detector with setting a got result +1, detector with setting b got result -1) + (-1)*(fraction of trials in run where detector with setting a got result -1, detector with setting b got result +1) + (-1)*(fraction of trials in run where detector with setting a got result -1, detector with setting b got result -1)

Hopefully you at least agree that in the limit as the number of trials becomes large, the expression for the empirical average below should approach my definition (which I claim is of the standard form) for the expectation value above. In that case, does your whole argument hinge on the fact that you think Bell's equation (2) was giving an alternate definition of "expectation value", one which would actually differ from the one I give?

JesseM

Aug11-10, 03:27 AM

Are you saying their only hope is to make some assumptions about the values of λ in their experiment, such as the idea that the distribution of different λi's in their sample is similar to the one given by the probability distribution function
I'm not saying that, nor do I need to say that because they ALREADY make the assumption ("fair sampling assumption") that the sample of measured pairs is representative of the population of emitted pairs, which is exactly the assumption that the sample ρ(λ) is the same as the population ρ(λ).
Assuming that "the sample ρ(λ) is the same as the population ρ(λ)" is an assumption that "the distribution of different λi's in their sample is similar to the one given by the probability distribution function", and therefore an "assumption about the values of λ in their experiment", at least it would be in my way of speaking. So there was really no need to jump down my throat (and compare me to a political pundit, ouch!) at the end of post #1228 for saying "If you think a physicists comparing experimental data to Bell's inequality would actually have to draw any conclusions about the values of λ on the experimental trials..."?
Because you claimed I was saying, physicists need to know the values of λ, in order to calculate expectation values
No, I said "draw any conclusions about the values of λ", which would include conclusions about the statistics of different values of λi in all three runs. Maybe you shouldn't rush to assume that the most negative interpretation of my words is the correct one.
Yes, but to get a "damn good estimate of the true expectation values", all that's necessary is that the actual frequencies of different measurement results were close to the "true probabilities" (in frequentist terms) in equations like this one

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)
False! The above equation does not appear in Bell's work and is not the expectation value he is calculating in equation (2).
True! Bell was writing for an audience of physicists, who would understand that he didn't mean for (2) to indicate he was totally rewriting the standard meaning of "expectation value", but was just making the argument that the expectation value as conventionally understood (i.e., equal to my equation above) would in this case be equal to the integral in (2).

In any case, even if you persist in the wrongheaded belief that (2) was meant to be a definition rather than a physical conclusion, it's not hard to see that (2) can be reduced to my expression above anyway. I showed this way back in post #855 (http://www.physicsforums.com/showthread.php?p=2773354#post2773354):
Remember, though, Bell is assuming that the value of A and B is completely determined by the values of a, b, and λ. So, the integral on the right of (2) is exactly equivalent to the following weighted sum of four integrals:

(+1)*(+1)\int P(A=+1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda +
(+1)*(-1)\int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda +
(-1)*(+1)\int P(A=-1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda +
(-1)*(-1)\int P(A=+1, B=+1|a,b,\lambda)P(\lambda)\,d\lambda

The reason this works is because for any given value of λ, say λ=λi, three of the probabilities in the four integrals above will be equal to zero, while the other probability will be equal to 1. So by splitting up the single integral into the four above, you aren't overcounting or undercounting A*B*P(λ) for any specific value of λ, you're counting it exactly once. This is easier to see if you suppose λ can only take a discrete set of values from 0 to N, so the integral on the right side of (2) can be replaced by the sum \sum_{i=0}^N A(a,\lambda_i)*B(b,\lambda_i)*P(\lambda_i). Then if a,b,λ completely determine the values of A and B (which each take one of two values +1 or -1), that means the four-term sum (+1)*(+1)*P(A=+1,B=+1|a,b,λi) + (+1)*(-1)*P(A=+1,B=-1|a,b,λi) + (-1)*(+1)*P(A=-1,B=+1|a,b,λi) + (-1)*(-1)*P(A=-1,B=-1|a,b,λi) will always be equal to A(a,λi)B(b,λi) for each specific value of λi [for example, if a,b,λi determine that A=+1 and B=-1, then (+1)*(+1)*P(A=+1,B=+1|a,b,λi) + (+1)*(-1)*P(A=+1,B=-1|a,b,λi) + (-1)*(+1)*P(A=-1,B=+1|a,b,λi) + (-1)*(-1)*P(A=-1,B=-1|a,b,λi) = (+1)*(+1)*0 + (+1)*(-1)*1 + (-1)*(+1)*0 + (-1)*(-1)*0 = (+1)*(-1) = A(a,λi)B(b,λi)]. So, if we substitute the four-term sum in for the individual term A(a,λi)B(b,λi) in the sum over all possible values of λ I wrote above, we get:

\sum_{i=0}^N [(+1)*(+1)*P(A=+1,B=+1|a,b,\lambda_i)+\,(+1)*(-1)*P(A=+1,B=-1|a,b,\lambda_i)+ \,(-1)*(+1)*P(A=-1,B=+1|a,b,\lambda_i)+\,(-1)*(-1)*P(A=-1,B=-1|a,b,\lambda_i)]*P(\lambda_i)

Which can be split up into the following four sums:

\sum_{i=0}^N (+1)*(+1)*P(A=+1,B=+1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (+1)*(-1)*P(A=+1,B=-1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (-1)*(+1)*P(A=-1,B=+1|a,b,\lambda_i)*P(\lambda_i) +
\sum_{i=0}^N (-1)*(-1)*P(A=-1,B=-1|a,b,\lambda_i)*P(\lambda_i)

...which is just the discrete version of the four integrals I wrote before.

So, the left side is an expectation value which can be broken up into a weighted sum of four probabilities of the form P(AB|ab), and the right side can be broken up into a weighted sum of four integrals or sums over all possible values of λ of terms of the form P(AB|a,b,λ). For example, on the left side one of the four weighted probabilities is (+1)*(-1)*P(A=+1,B=-1|ab), and on the right side one of the four weighted integrals is (+1)*(-1)\int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda. So if you take the marginalization equation P(A=+1,B=-1|a,b) = \int P(A=+1, B=-1|a,b,\lambda)P(\lambda)\,d\lambda and then multiply both sides by A*B=(+1)*(-1) and add this equation to three other marginalization equations where both sides have been multiplied by the corresponding value of A*B, you get something mathematically equivalent to equation (2) in Bell's proof.
As long as the fraction of trials where they got a given pair of results like (+1 on detector with setting a, +1 on detector with setting b) is close to the corresponding "true probability" P(detector with setting a gets result +1, detector with setting b gets result +1) then the sample average of all the products of measured pairs will be close to the expectation value. And the law of large numbers says that the measured fractions are likely to be close to the true probabilities for a reasonably large number of trials (a few thousand or whatever)
Since you continue to insist on this ridiculous idea, explain how they can know what the "true probability" is.
They can't, but they can know that whatever the true probability is, the law of large numbers says their measured frequencies become increasingly unlikely to differ significantly from the true probabilities as the number of trials gets larger and larger.
And in case you are going to respond with the "large numbers" argument, make sure you also explain how they can be sure that the number of trials is large-enough.
Large enough for what? It's up to them how statistically strong they want their result to be.
But if you do N trials and get a given result on m of those trials, you can find an epsilon and p such that P(number of positive results on N trials is m or greater | true probability is smaller than m/N by p or more) < epsilon, and the larger the number of trials the smaller you can make p and epsilon (and obviously you can write a similar equation to cover the possibility that the true probability is greater than m/N by p or more)
I remember asking you where you got "1000 or more" from and you did not answer, so remember to answer it this time.
Please phrase your requests in a more civil manner than "remember to answer it this time", I'll let this go but in future I will ignore bullying commands, it's not that hard to type the word "please". Anyway, 1000 is just an example (that's why I always used phrases like 'say, 1000 trials' or 'a few thousand trials or whatever'), it's a number of trials where the probability of significant differences between observed frequencies and actual probabilities tends to become pretty small, provided the frequencies aren't as small as 1/1000 or so. For example, say the actual probability is 0.3, what are the chances that the observed frequency will be more than 10% larger, i.e. more than 330? Well, in this case we can use the binomial calculator (http://stattrek.com/Tables/Binomial.aspx), it shows that the probability of getting more than 330 in this case is only about 1.8%. So if you get a result of 331, or an observed frequency of 0.331 in your sample of 1000, you know the probability of getting that result in any case where the actual probability is 0.3 or lower must be 1.8% or lower. And if that's not statistically strong enough for you, you can always increase the number of trials.
even if the number of trials is small compared to the number of possible values of λ so that the frequencies of different λi's in the particles they sampled were very different from the frequencies in the limit of an infinite number of trials, which is what is given by the probability distribution on λ. Do you disagree with that "even if"?
I absolutely disagree. In Bell's work, the expectation values are obtained by integrating over ρ(λ), the derivation of the inequalities relies on the fact that ρ(λ) is the same for all three terms. If this requirement is not met, the inequalities CAN NOT be derived. It is common sense to realize the fact that, if in any sample ρ(λ) is not the same for all three terms, that sample does not conform to the mathematical requirements inherent in the derivation of Bell's inequality.
But when you write ρ(λ), is that intended to be a probability distribution where the probabilities are interpreted in "limit frequentist" terms? If so, it is trivial to see that two runs drawn from the same "limit frequentist probability distribution" may have a different actual frequency of different λi's, just like two runs of 10 flips of a fair coin with "limit frequentist probability distribution" P(heads)=0.5 and P(tails)=0.5 may end up having a different number of heads on each run.
The fair sampling assumption discussed on wikipedia doesn't say anything about the full set of all hidden variables associated with the particles, it just says the fair sampling assumption "states that the sample of detected pairs is representative of the pairs emitted"
Huh? What do you think the underlined statement means.
It means that the actual data observed in your sample is representative of the data you would have gotten if all emitted pairs had been detected. If you're doing a run with detectors set to a and b, then as long as the "emitted but undetected pairs" have the same statistics on their predetermined results for detectors a and b as the actual observed results for detected pairs with these settings, the fair sampling assumption is satisfied. It doesn't matter if other hidden variables had different statistics for the "emitted but undetected" group and the detected group, all that matters is the actual results for the detected group and the corresponding predetermined results for the undetected group (the results you would have gotten had you actually detected them).
The underlined words are clearly an admission that the fair sampling assumption can not be divorced from the requirement that ρ(λ) not be significantly different between the population and the sample.
And again, you are apparently not using "limit frequentist" definitions here, since it is quite possible for two finite samples of particles to have differing frequencies of different λi's despite the fact that both samples were drawn from the same "limit frequentist" probability distribution.

In any case, as I said, the fair sampling assumption only requires that the statistics of predetermined results in the "emitted but undetected" group match the actual results in the detected group. The number of possible values of λi may be vastly larger than the number of possible combinations of predetermined results on two axes (which just amounts to four combinations: a=+1,b=+1 and a=+1,b=-1 and a=-1,b=+1 and a=-1,b=-1), so it's quite possible for the statistics of results/predetermined results to match in the two groups while the statistics of λi's do not.
How else will they be predetermined. Remember in Bell's notation, the outcomes are given by the functions:
A(a,λ)=+/-1, B(b,λ)=+/-1 with the understanding that the terms in parenthesis are deterministically resulting in the outcomes. So you are arguing with yourself here.
What does the fact that the outcomes are predetermined by the detector setting and the value of λi have to do with the idea that the fair sampling assumption only requires that the statistics of predetermined results match the measured results, but that it doesn't otherwise require the statistics of values of λi match in the measured/unmeasured group?
If ρ(λ) in the sample is not significantly different from ρ(λ) in the population, then the distribution of the outcomes will not be significantly different. However, just because the distribution of the outcomes is not significantly different is not proof that ρ(λ) is the same. It is a necessary but not a sufficient condition as you still must be able to resort the data.
Please answer my question about whether you are willing to just use the "limit frequentist" notion of probability in this discussion--and if you are, do you see why with this understanding it doesn't make sense to say "ρ(λ) in the sample is not significantly different from ρ(λ) in the population" when you are really just talking about the frequencies of different values of λi in the finite sample, not the frequencies that would be found if we took an infinite sample under the same conditions?

JesseM

Aug11-10, 04:24 AM

If this is correct, then I'll just note that even if you can do this resorting, it doesn't guarantee that the "hidden triples" associated with the ith iteration of all three runs were really the same, much less that the value of λ (which can encompass many more details than just three predetermined results for each setting) was really the same on all three.I already answered this:
Your answer only seems to address the part that your ability to do this "resorting" doesn't guarantee the value of λ was really the same for all three (and you basically seemed to agree but say it doesn't matter), but you didn't address the point that even the "hidden triples" may be different than the imaginary triples you created via resorting. For example, suppose after resorting we find the 10th iteration of the first run is a=+1,b=-1, the 10th iteration of the second run is b=-1,c=-1 and the 10th iteration of the third is a=+1,c=-1. Then we are free to self-consistently imagine that each run had the same triple for iteration #10, namely a=+1,b=-1,c=-1. However, in reality this might not be the case--for example, the 10th iteration of the first run might actually have been generated from the triple a=+1,b=-1,c=+1. So, the statistics of the imaginary triples you come up with after resorting might not match the statistics of actual triples on each run, or on all three runs combined.

Maybe you'd agree with this point about the statistics but say it's irrelevant, that all you care about is the fact that "resorting" means Bell's inequality is mathematically guaranteed to be obeyed. I agree it means that, but of course I would say Bell's inequality doesn't require that the data be "resortable" in order to have a high probability of being satisfied in a local realist universe. The reason, once again, is that all the expectation values that appear in the inequality are understood to relate to the "limit frequentist probabilities" of different outcomes in the way I've described:

E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

So if these expectation values can be shown to satisfy the Bell inequality |E(a,b) + E(a,c)| - E(b,c) <= 1 in a local realist universe, then for a large sample size it's unlikely those ideal expectation values will differ significantly from the corresponding empirical sample averages, and so it's unlikely the sample averages will fail to satisfy the inequality in a local realist universe either (the larger the sample size, the more unlikely it becomes).

Is the only part of this you disagree with the claim that Bell's expectation values E(a,b), E(b,c) and E(a,c) were understood by him (and every other physicist) to be equal to the expression I write above? In other words, if you could be convinced that his expectation values are equal to that expression (along with the expression Bell wrote in equation (2), based on various physical assumptions), then would you agree if he successfully shows that expectation values defined this way should satisfy |E(a,b) + E(a,c)| - E(b,c) <= 1 in a local realist universe, that implies (by the law of large numbers) that empirical sample averages would also be highly unlikely to violate the inequality for a large sample in a local realist universe?
You are right that being able to resort does not ensure that ρ(λ), is uniform. However, not being able to resort, is definite proof that ρ(λ) is not uniform.
If we interpret ρ(λ) in "limit frequentist terms", it is quite possible all three samples (i.e. the three runs) could be drawn from the same ρ(λ) and yet the actual data on these finite samples could not be resorted--do you disagree?
First of all, it's a physical assumption that the result A on Earth depends only on a and λ and can therefore be written A(a,λ)--if you allow "spooky" influences, why can't the result A on Earth depend on the setting b, so that if on Earth we have setting a1 and hidden variables in state λ5, and on the other planet the experimenter is choosing from settings b1 and b2, then it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1?
You did not understand. A(a,λ) is a function that maps a given value of a and λ to an outcome of +/-1.
Are you just declaring that this is a starting assumption in your example, so we're not allowed to question it? I'm not interested in discussing your example unless it's supposed to be analogous to what Bell was doing--do you disagree that in Bell's equation, A just stood for the result of a measurement on a particle by one experimenter (let's call her Alice), so it was a physical assumption Bell made that A could be written as a deterministic function of only a and λ? Do you deny it's logically possible that if Alice is measuring a particle which always yields result +1 or -1, then her outcome might depend not only on her detector angle a and some variables associated with the particle λ, but also on the choice of detector angle b used by a distant experimenter Bob? If you agree this is logically possible, you should be able to see why Bell needs to invoke physical arguments (specifically, local realism and the fact that Alice and Bob are far apart) to justify the claim that Alice's result A depends only on a and λ but not on b.
The function has nothing to do with probability. A(a,λ), "a" can depend on "b". All that the notation A(a,λ) = +/-1 means is that given a specific value of "a" and a specific value of "λ", we get a specific value of either +1 or -1. It is a function of two variables not three and there is nothing in the notation itself that should suggest to you that dependence on "b" is not allowed.
Again, if this is supposed to apply to Bell's paper, then you can't treat Bell's equations as definitions, rather they represent physical conclusions he argues for, like the conclusion that the result A couldn't depend on a distant detector setting b in a local realist universe. If you just want to discuss your own example, I don't really see the point unless it is meant to be analogous to what Bell was doing.
then it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1?
Wrong. "a1" depends on "b2" means that if you looked at how the values of "a" and "b" varied with time after the fact, it will not be random, but certain values of "a" will always be paired with certain values of "b" due to the instant communcation when the settings were being made. It doesn't mean a specific value of "a" will give a different result depending on which value of "b" existed on the opposite side.
This would be a very cogent criticism if I had ever said that my equation was meant to describe a situation where "a1 depends on b2", but since I never claimed anything of the sort I have no idea what statement of mine this is supposed to be in response to. I just said that it's logically possible that the result A might depend on the distant setting b, in which case it could be true that A(a1, λ5, b1)=+1 but A(a1, λ5, b2)=-1...since this is logically possible, it means Bell has to invoke physical assumptions to justify the notion that the result A depends solely on a and λ.
You completely missed the point. Despite the fact that the "physical assumptions" in this example are completely contrary to Bell's, we still obtained the exact same expression for the expectation value of the paired product. Which means the "physical assumptions" are peripheral.
Sounds like bizarro logic to me. Your example seemed to consist of little more than you declaring that various conditions were true, like the condition that A was a function only of a and λ...how does this prove anything about whether Bell needs physical assumptions to actually justify similar equations in the experiment he's describing? If I can come up with some contrived example where the motion of a toy train on its track is described by the same equations that describe elliptical orbits of planets (because I designed the example to work that way, picking an elliptical track shape and carefully controlling the speed of the train), have I thereby proved that "physical assumptions are peripheral" in deriving the result that planets have elliptical orbits?

zonde

Aug11-10, 04:32 AM

2. Einstein gave us the "the moon is there when not looking at it" comment, so I am not sure I quite agree if you are saying that Einstein was not a "naive" realist. (Although I personally don't care for the use of the word naive as it comes off as an insult.) But I would be interested in a quote that clearly expresses a) what realism looks like which is NOT naive; and more importantly b) any evidence Einstein subscribed to that view. Given his "moon" comment, which is pretty clearly in the "naive" school.
You can find something about this in Wikipedia Ensemble Interpretation (http://en.wikipedia.org/wiki/Ensemble_Interpretation):

Probably the most notable supporter of such an interpretation [Ensemble Interpretation] was Albert Einstein:
"The attempt to conceive the quantum-theoretical description as the complete description of the individual systems leads to unnatural theoretical interpretations, which become immediately unnecessary if one accepts the interpretation that the description refers to ensembles of systems and not to individual systems."

Although I think that reading EPR paper with that quote in mind can provide better understanding about the role of "reduction of wave packet" in EPR argument.

DevilsAvocado

Aug11-10, 06:07 AM

If there is anyone who believes there is any relevance in billschnieder’s dopy posts, the answer is here (http://www.physicsforums.com/showpost.php?p=2833234&postcount=1241).

RUTA

Aug11-10, 08:11 AM

I guess I agree... one thing that bothers me though... How does the Moon know if someone is looking??

In Relational Blockworld, if the entity "isn't there," i.e., is "screened off," it doesn't exist at all. So, the answer to your question is that there is no Moon to wonder :smile:

DevilsAvocado

Aug11-10, 08:41 AM

In Relational Blockworld, if the entity "isn't there," i.e., is "screened off," it doesn't exist at all. So, the answer to your question is that there is no Moon to wonder :smile:

Okay, sounds fair... it must mean that if someone, let’s say billschnieder, was blinking his eyes rapidly towards the Moon... it would exist and non-exist quite rapidly...?

And we could say that Bill is actually creating the Moon... maybe he is The Man in the Moon...?:uhh:?

:smile:

DevilsAvocado

Aug11-10, 09:07 AM

Probably the most notable supporter of such an interpretation [Ensemble Interpretation] was Albert Einstein:

I love Einstein, he’s my hero. The question is – do you think that he would have rejected Bell's Theorem and EPR-Bell experiments?

And how does the Ensemble Interpretation explain if we decide to have very long intervals between every entangled pair in EPR-Bell experiments, let’s say weeks or months? Where is the "Global RAM" situated in a case like this? That fixes the experimentally proved QM statistics, for the whole 'spread out' ensemble??

charlylebeaugosse

Aug11-10, 09:11 AM

a) Yes, this is very true. Einstein’s own argument boomeranged on him:
no action on a distance (polarisers parallel) ⇒ determinism
determinism (polarisers nonparallel) ⇒ action on a distance

But to be fair we must say that also Niels Bohr was somewhat 'wrong'. If it turns out that nonlocality is fact, then QM must be considered 'incomplete'... or ...?:uhh:?

b) There is no doubt in my mind that Einstein, if he was alive, would have accepted the work of Bell as starting point for "something new", not a starting point for an old man to get 'grumpy'. :wink:

I have added a) and b) to the quote to answer point by point.
a) In a) it seems to me that you forget that in a classical pair, there would be more quantities being conserved than can be given simultaneous meaning in the QM case (and probably in the microscopic case. What is bizarre here from the historic point of view is that Einstein did NOT consider the values of measurement. His argument in Alice-Bob terms
was:

Assume Alice chooses a measurement n particle p1, say position or momentum while p2, the other particle of the pair, is spatially remote so that no action on p1 should affect p2. Then the Psi function (we now say wave function) of p2 would depend on that choice of measurement (no output mentioned) while such choice cannot have a remote action if one accept spatial separation. This one statement of the pair
(QM is complete, no influence on spatially remote objects)
has to be relinquished.

To the contrary of what Einstein wrote about completeness of QM in many places from 1933 to 1952 at least, in the EPR paper, written by Podolsky "because of language" (probably meaning the logic language as used by Godel in the proof of his Non-completeness Theorem since the only native English speaker was Rosen, and poor English shows up in the title of the EPR paper: see the book of Fine - and I am not an overall Fine fan, but his book is fan-tastic), values of coordinates are used so that in effect Podolsky "proves" non-completeness by first proving QM false as a particles end up having values for conjugate variables (to my own opinion, the structure of the EPR argument (again, see Fine's book:"The Shaky Game")
participates to the schizophrenic appearance of Bohr's reply since Bohr does take care of defending that QM is not false at the same time that he answer the completeness question.
Notice that Fine does not state that Podolsky used the falsity detour: he says that Podolsky thought he proved that the position and momentum coexist, and this is what I term "QM false" (but Podolsky's proof is shaky - Fine tells us and there is the issue of coexistence backward in time that makes things compliated). I have written in a previous post that I would explain (as part of a list (a to d) of self assigned items) why Podolsky may be right, but in a way that can be contested. But this will take time and I should perhaps respond to questions and posts before I choose my own items. Also, Einstein never used the elements of reality (EoR), but Podilsky used them without taking into account himself that they should be rooted in experience: if any observable being used must be measured, then at most 2 spin projections can be measured on a pair, and there is not enough room for Bell inequalities for such "complete EoR". But Podolsky used incomplete EoR's (i.e., without the need for any one making sense to be measured) and with those, Richard Friedberg showed in an unpublished work quoted by Jammer in his book on the Philosophy of QM that EPR's
EoR lead to a Bell inequality (without the name as Friedberg did not know then about Belll's work. Unfortunately, no one seems to have pointed out the condition self imposed (but not used) by Podolsky who had his own agenda as he wanted to prove QM wrong (and wrote to the NY time about the fact that Einstein and co-worker had proven that, which infuriated Einstein, as documented by at least one of Jammer and Fine.

b) If Einstein would have live till 1964+ and had looked at this then obscure publication of Bell, he would probably have noticed that the realism (in teh form of Pr3edictive HV compatible with QM) being used was as heavy as in the work of de Broglie and Bohm that he was often making fun of (despite respect for the part of their works that he considered valuable: after all Einstein supported de Broglie when initially no one thought his thesis had value, but he through away the attempt he made himself in 1927 at a naive HV theory). Now if you start from something physically false (for Einstein) such as naive HVs, you can of course deduce anything idiotic that you can think about. But since Bell did not prove HV wrong (something that cannot be proved, perhaps, but physics is not the world of proofs)
he could not prove all one can think about, but "only" one consequence: non-locality. In 1955, when Einstein died, HVs had been disposed by the community of physicists despite a few dissidents, and I do not take von Neumann's "proofs" since that is not most physicist function. Consequently, proving that there cannot be local realism while the absence of realism AT THE MICROSCOPIC LEVEL had been essentially accepted by the profession could not be so exciting. But 9 years later, in fact a bit more as it took time for Bell's work to be noticed, people on both sides of the Iron Curtain were no more thinking about the foundation or interpretation of QM and concentrated on solving the puzzle of the 4 fundamental forces and the particles and resonances that where popping out from the new machines at the various particle labs in CERN , in the US etc. So someone as smart as Bell and from CERN, could certainly move people and generate passion where no grand master was paying attention: see the modest interest attached to Aspect's experiment by Gell Man in his popular book and the story circulating about Feyman throwing Clauser out of his office. Now these two people and Anton Zeilinger got together a Wolf Prize: one can document that the old masters knew better. The 1931 Einstein, Tolman, Podolsky paper show an UP backward in time, so that an observable value cannot pre-exist it's measurement (I have already mentioned that the argument applies to generic particles, but not to EPR (or in particular EPR-B) particles). So understanding that many spin projections cannot coexist, how could have Einstein be excited. How could he have not be upset by a paper that fully misrepresent the EPR paper. Assuming that he had seen his own version documented by others, and knowing that Bell could not ignore that, how could he not have been upset by Bell's attitude on Einstein supposed support for HV's? In 1935, Einstein stopped communication with Podolsky: using the words grumpy and old man in one sentence is a form of discrimination: better grumpy than naive when i comes to physics and its history. Demystifiers have to pay attention of not being carried by the massive flows of mystification such as what is going on about Bell. Bell assumed the false hypothesis that there is as much realism at the microscopic level as used in classical physics (whatever you think of the moon's dependence on your person) and locality that seems to belong to the spirit of relativity and that has never been challenged in itself by any experience to find a Boole inequality that means that said wrong hypothesis and locality form a pair that contains at least one false statement. The only virtue of that
(and an important one for me as it conditions my work for 5 years at least) is that it invites us to better found non-realism (whatever we think of it at the macroscopic level), and I mean the absence of classical realism at the microscopic level, so that Quantum-Compatible realism (in the form of he CQT of Griffith, Omnes, Gell-Man, Hartle (even if I am not a fan of that), or in the form envisioned but not spelled out because they did not know by Shrödinger and Einstein) is OK from this point of view at least. Perhaps the work of the hyper realist Bell (the champion of Bohm and de Broglie (after all)) will have the main virtue of making non-existence of microscopic realism one of those thing that went from the real of pure philosophy to that other sub-realm of philosophy called "physics". But there is still work to be done (with little reward to be expected).

charlylebeaugosse

Aug11-10, 09:36 AM

If there is anyone who believes there is any relevance in billschnieder’s dopy posts, the answer is here (http://www.physicsforums.com/showpost.php?p=2833234&postcount=1241).

I looked there. This is factually exact (but see *), but does not reflect the push toward "QM non-local" that resulted from Bell's theorem: the summaries of what physics has lost and won from there is for the least incomplete.

Since realism was not believed in the progress brought by Bell's theorem is not that big. But, for me:
- (as I developed in a recent post) it invites at proving once and for all that realism is the villain and that we can continue to hold on to locality.
- it has motivated the work on techniques that may prove useful, even if the great value of Q crypto and Q computation remain to be established. I am personally sure that Q crypto will be fine, at least if one accept that detection of eavesdropper is enough.

*Bell's inequality, and the other forms such as CHSH is a form of Boole's inequality.
Bell's theorem is not Bell's Inequalities, it is the statement of incompatibility of QM with a pair of hypothesis as stated in the link mentioned in the quote. Thus, GHZ is another, perhaps better, form of Bell's theorem but there is no inequality in there. Altogether one needs to be very precise and without the historical context at the time Bell wrote his paper, and what believed the great masters of QM, I find the link rather misleading even if the main statement are not false. The global result of Bell's work over the years is that, contrary to what the great Sir Anthony Leggett things, people around Scully have tested (to their disarray) that more people believe that non-locality hold true tan people who relinquish realism! AND YOU CALL THAT A POSITIVE EFFECT ON PHYSICS? (especially when science is again assailed by the back powers of blind beliefs and anti-science powers!).

If indeed the glove is picked up and we prove non-realism at the microscopic level (I leave the moon level to others, but what if a chimp looks a the moon?) because it was doubted upon as a consequence of Bell's work, them I will admit that after all it was a good move to point out this weakness in the tool-box of physics.

nismaratwork

Aug11-10, 09:43 AM

If there is anyone who believes there is any relevance in billschnieder’s dopy posts, the answer is here (http://www.physicsforums.com/showpost.php?p=2833234&postcount=1241).

Well, his last little rant aside, I'm just relieved that he's taking a break. Whatever he chooses to believe about this being some "JesseM vs. Him" or "[insert name] doesn't understand probability", I don't really care anymore... as long as he stops cluttering the thread with transparent crap.

RUTA

Aug11-10, 10:15 AM

Okay, sounds fair... it must mean that if someone, let’s say billschnieder, was blinking his eyes rapidly towards the Moon... it would exist and non-exist quite rapidly...?:smile:

If bill was the ONLY thing interacting with the Moon, yes. Of course, the Moon is interacting with MANY things, even things that don't "see." It's not an issue of consciousness, the issue is interaction.

charlylebeaugosse

Aug11-10, 10:25 AM

1. You are welcome if so! I used to have a worse (darker) copy and then someone helped me get a better one.

2. We could discuss the Tresser paper and related in a new thread, no prob there. If you want I can start it. I tend to hold onto locality so the Tresser ideas are pretty interesting. His work has been on my radar for a while although I have not read closely.

Seems you were right to wait as a new preprint clarifies the Bell part of that paper (leaving the GHZ mostly untouched).

DrChinese.
How do I start a new thread? I do not even know how to easily go to this thread on EPR, nor how to navigate without hopping each time for a miracle to lead me where I need to go: can someone provide a link to where I could learn the basics of Physics Forums? e.g., I just uploaded 2 files (or so did I think), but have no idea of what are the ways for others or me to access them (assuming that the upload functioned). Sorry for these beginner's questions that do not belong to a thread, but then where should I ask (even if that question does not belong either).

Besides, when you asked for more precise indications, was it about Wigner's paper or else?
And if I find a paying link, such as a journal, can I just give that (perhaps I must do that?) or do I have to (or should I) find a link to free access or provide a copy from my files when I can? Perhaps that's in the rules... Sorry to be such a schmuck and I apologize for cluttering the thread with that.

charlylebeaugosse

Aug11-10, 10:42 AM

If bill was the ONLY thing interacting with the Moon, yes. Of course, the Moon is interacting with MANY things, even things that don't "see." It's not an issue of consciousness, the issue is interaction.

But who cares about macroscopic objects that interact with nothing. The question of Einstein was simple: "Do you think that the moon is not there when you do not look at it?" (quoted from memory). Too many people have deduced from this question and similar ones that Einstein believed in naive realism (e.g., as in the theories of de Broglie and Bohm). IF Einstein believed in HVs, those would not have let one predict values on pairs of conjugate variables in usual coordinates. But if one knows what Einstein was making fun of (see for instance his correspondence with Born (where Born gives to the reader his opinion , but clearly from those letters, Born never understood the completeness issue, in the EPR paper or the way Einstein stated it) and also the books of Jammer and Fine, there is little that I know of about progress that he or Shrödinger would have made in that direction, assuming any progress was made for one of them. Unfortunately, the search for such HVs, or the effort to prove them illusory has been pushed aside by a rear-guard fight on naive HVs of the kind that most physicists had dismissed much before 1964, and even before 1955 when Einstein died (I have posted elsewhere a few positive effects that I know of Bell's work, as well as some other negative comments). How do you guys/girls do: I type slowly (thanks god some will say) and will need to stop as my fingers hurt.

DevilsAvocado

Aug11-10, 10:42 AM

I have added a) and b) to the quote to answer point by point.

Please correct me if I’m wrong, but I interpret this as: You are saying Bell was wrong and Einstein was right?

DevilsAvocado

Aug11-10, 10:48 AM

... that more people believe that non-locality hold true tan people who relinquish realism!

I agree on that. This is the popular science (profitable) headlines: The world is NOT local!!

You should talk to RUTA about realism. He’s a professional physicist with great knowledge, instead of realism, he uses the term Holism and Nonseparability (http://plato.stanford.edu/entries/physics-holism/) (which I made fun of by 'translating' to Alco-Holism and Nonsense-parability :smile:, sorry... :redface:):

Thus, there are generally two ways to account for EPR-Bell correlations. 1) The detection events are separable and you have superluminal exchange of information. 2) The detection events are not separable, e.g., the spin of the entangled electrons is not a property of each electron. The first property is often called "locality" and the second property "realism."

This is a slightly different approach, I think...

(I leave the moon level to others, but what if a chimp looks a the moon?)

I hope you get that "the moon" is not literally...?:bugeye:?

DevilsAvocado

Aug11-10, 10:49 AM

I'm just relieved that he's taking a break.

It ain't over 'til the fat lady sings... :wink:

DevilsAvocado

Aug11-10, 10:53 AM

DevilsAvocado

Aug11-10, 11:06 AM

the issue is interaction.

(Let’s skip "the moon" for awhile :smile:) If we assume that nothing exist without interaction, and BB is correct.

How can anything start to interact (exist) if it has nothing to interact with??

(I have to go, there’s real thunderstorm outside...)

RUTA

Aug11-10, 11:27 AM

Okay! Now I’m making a fool of myself... You are taking "the moon" literally?? :surprised

I don't know of any limit to the size of something that can be "screened off" in principle. In practice? Well, that's another matter :smile:

RUTA

Aug11-10, 11:32 AM

But who cares about macroscopic objects that interact with nothing.

Exactly! What does that even mean in an empirical enterprise such as physics?

The question of Einstein was simple: "Do you think that the moon is not there when you do not look at it?" (quoted from memory). Too many people have deduced from this question and similar ones that Einstein believed in naive realism (e.g., as in the theories of de Broglie and Bohm). IF Einstein believed in HVs, those would not have let one predict values on pairs of conjugate variables in usual coordinates. But if one knows what Einstein was making fun of (see for instance his correspondence with Born (where Born gives to the reader his opinion , but clearly from those letters, Born never understood the completeness issue, in the EPR paper or the way Einstein stated it) and also the books of Jammer and Fine, there is little that I know of about progress that he or Shrödinger would have made in that direction, assuming any progress was made for one of them. Unfortunately, the search for such HVs, or the effort to prove them illusory has been pushed aside by a rear-guard fight on naive HVs of the kind that most physicists had dismissed much before 1964, and even before 1955 when Einstein died (I have posted elsewhere a few positive effects that I know of Bell's work, as well as some other negative comments). How do you guys/girls do: I type slowly (thanks god some will say) and will need to stop as my fingers hurt.

I would love to hear Einstein's thoughts about the situation now, given the vast experimental evidence in support of QM over "Einsteinian reality."

charlylebeaugosse

Aug11-10, 12:35 PM

I would love to hear Einstein's thoughts about the situation now, given the vast experimental evidence in support of QM over "Einsteinian reality."

What evidence, or rather what do yu mean is proven, especially over "Einsteinian reality". Most of what one reads as "Einsteinian reality" is false attribution (like doing as if the EPR paper had his imprimatur, if not represented the way he thought) or lack of comprehension. As I have developed in previous posts, on the basis of writings of Einstein, Fine, and Jammer, Einstein was not a naive realist, at least after 1927, and in fact provided the first (only so far) proof of non-realism in 1931 with Tolman and Podolsky. He considered that as long as one uses the classical observables, the UP is here to stay (DrChinese would write HUP, but I have advocated using UP before since the first general version was not under the hand pf Heisenberg, as far as I know: in fact Jean-Marc Levy-Leblond would explain to us that we should rather said Indeterminacy principle that one could represent for short as IP). Please attack on more precise statements that I have made, mostly earlier today, if you disagree on the fact that legend and and not history serves as the major way one now believe Einstein thought of all matters that concern QM (the subject he most thought about did he say at least once). The experimentalists such as Aspect who think having proved Einstein wrong have generally miss-represented his thinking about the matters relevant to said experiments. Honesty has not been the trademark of such attacks. I can document, but prefer sticking to physics. I was myself abused and went into this field (one of my youth goals) because I felt that non-locality was too cool, too green would they say in the 5th element (a fun movie filled with serious non-local events). Well, reading the original sources and the history books (be it as sources of originals citations) I realized that dishonesty had taken command of the subject most central to physics: Quantum Mechanics. So please, look into what I clam and negate with basis if needed. I may be wrong thinking I was wrong in the first place (but I read a lot to see the light, starting with Fine's book although for now I only by his analysis and history part: no idea about his prism nor his philosophy, although I saw him being VERY sharp).

RUTA

Aug11-10, 12:41 PM

What evidence, or rather what do yu mean is proven, especially over "Einsteinian reality". Most of what one reads as "Einsteinian reality" is false attribution (like doing as if the EPR paper had his imprimatur, if not represented the way he thought) or lack of comprehension. As I have developed in previous posts, on the basis of writings of Einstein, Fine, and Jammer, Einstein was not a naive realist, at least after 1927, and in fact provided the first (only so far) proof of non-realism in 1931 with Tolman and Podolsky. He considered that as long as one uses the classical observables, the UP is here to stay (DrChinese would write HUP, but I have advocated using UP before since the first general version was not under the hand pf Heisenberg, as far as I know: in fact Jean-Marc Levy-Leblond would explain to us that we should rather said Indeterminacy principle that one could represent for short as IP). Please attack on more precise statements that I have made, mostly earlier today, if you disagree on the fact that legend and and not history serves as the major way one now believe Einstein thought of all matters that concern QM (the subject he most thought about did he say at least once). The experimentalists such as Aspect who think having proved Einstein wrong have generally miss-represented his thinking about the matters relevant to said experiments. Honesty has not been the trademark of such attacks. I can document, but prefer sticking to physics. I was myself abused and went into this field (one of my youth goals) because I felt that non-locality was too cool, too green would they say in the 5th element (a fun movie filled with serious non-local events). Well, reading the original sources and the history books (be it as sources of originals citations) I realized that dishonesty had taken command of the subject most central to physics: Quantum Mechanics. So please, look into what I clam and negate with basis if needed. I may be wrong thinking I was wrong in the first place (but I read a lot to see the light, starting with Fine's book although for now I only by his analysis and history part: no idea about his prism nor his philosophy, although I saw him being VERY sharp).

I'm using the term "Einsteinian reality" generically to mean "local and separable." I have no idea what he would say, I wouldn't even begin to argue that.

charlylebeaugosse

Aug11-10, 12:49 PM

(responding to Devils...) I don't know of any limit to the size of something that can be "screened off" in principle. In practice? Well, that's another matter :smile:
Ruta, Devilsavocado, DrChinese, etc. (people of good will and not realist): it seems to me that

- 1) Phase one is making sure of non-existence of classical realism at the miscroscopic scale.

- 2) Next, deciding if quantal realism holds true or not (I mean here a form of realism defended by some advocates of CQT (Consistent Quantum Theory))

- 3)Later then seeing the issue about the moon.

- 4) Even later, or any time but this is hard, checking if HVs compatible with QM (a theory that would permit exact predictions, but never on both members of conjugate pairs) can be constructed, if they would help, and how to do it: at some point we will have to negate or support scientifically the belief of Heisenberg and others that "one should not look for other variables". As long as one speaks of the HVs of de Broglie, Bohm, or Bell, no question left in my mind, but for some that respect the UP, I do not know if they can exist nor if they could help in anything if found. Solving that positively would be an immense achievement, but the other questions seems more in present time reach, at least the first one.

The above is a proposal for emergencies ordering (1 to 4, but I may have forgotten steps or independent questions that should belong here), but if anyone can solve the later items before the earlier ones, that is fine: I just would not like to spend time defending vague ideas about the moon while the crucial problem of local realism calls for a solution (thanks to Dr Bell planting a doubt in many minds, but as I said, if the issue can be decided by physics, it was worthwhile the big confusion about locality and the miss - attributions to Einstein starting with Bell).

RUTA

Aug11-10, 12:58 PM

Ruta, Devilsavocado, DrChinese, etc. (people of good will and not realist): it seems to me that

Phase one is making sure of non-existence of classical realism at the miscroscopic scale.

Next, deciding if quantal realism holds true or not.

Later then seeing the issue about the moon.

This is a proposal for emergencies ordering, but if anyone can solve the later items before the earlier ones, that is fine: I just would not like to spend time defending vague ideas about the moon while the crucial problem of local realism calls for a solution (thanks to Dr Bell planting a doubt in many minds, but as I said, if the issue can be decided by physics, it was worthwhile the big confusion about locality and the miss - attributions to Einstein starting with Bell).

Agreed, the issue will only be decided by physics. I think the goal of threads like this isn't to decide the issue, but merely debate the possibilities.

charlylebeaugosse

Aug11-10, 01:14 PM

I'm using the term "Einsteinian reality" generically to mean "local and separable." I have no idea what he would say, I wouldn't even begin to argue that.

Ruta, you see, "local and separable" is precise. "Einsteinian reality" to the contrary depends on what you know of Einstein's writing, and others, including misinformation propagated by people who want to show themselves better than Einstein (what would be the public value of being better than Podolsky?). Also, in "Einsteinian reality" there is reality, and while I (we?) love locality and separability, reality is for me THE ENEMY, so attributing him to the great guy does not help, except the glory of people who have greatly contributed t the confusion (see the book of Asher Peres, and let me know if he does not hint at QM being non-local, or look at the very public writings of the great Roger Penrose that deal with Bell's Theory, and let me know if he does not propagate the dark forces?). If no-locality was only defended by imbeciles, we would not have to worry. Bell was a crypto-realist who revealed himself later as realist, this pushed hard the fact that QM is non-local.
Now: look at Bell 1964, and check by yourself that Bell claim that QM had been proved to be non-local so that one should try HVs to restore its locality: see the 2 first sentences.
Now the Bell Theorem as state it there is about predictive HVs compatible with QM, but isn't non-locality suggested as a way out? So please be precise here, e.g., if you have students (graduate or else) or read papers that have some success. Lack of truth or words that can help that have to chased actively.

charlylebeaugosse

Aug11-10, 01:26 PM

Agreed, the issue will only be decided by physics. I think the goal of threads like this isn't to decide the issue, but merely debate the possibilities.

I wont mind being part of a group that solves a question (but perhaps I do not care about having publication with one or few authors). In fact, groups formed over the www might be the best chance of progress in some very hard questions, including precise questions in physics. This being said, when you write "the issue will only be decided by physics", do you mean that you are sure that physics can solve that or that if there is a solution it can only come from physics (sorry for the mad precision, but I have spent a few years in pure math before coming back to physics (but not mathematical physics that is for me a branch of applied math that requires talents that I do not have)). I do believe though that it would be useful to all be as precise as we can, be it only to avoid unnecessary confusions and disputes due only to misunderstanding. I feel some convergence, despite apparent divergences of writing: we might mostly need to adjust vocabulary.

RUTA

Aug11-10, 01:45 PM

This being said, when you write "the issue will only be decided by physics", do you mean that you are sure that physics can solve that or that if there is a solution it can only come from physics.

Both: I'm confident that physics can solve this and the solution will, ipso facto, come from physics.

unusualname

Aug11-10, 02:15 PM

I wont mind being part of a group that solves a question (but perhaps I do not care about having publication with one or few authors). In fact, groups formed over the www might be the best chance of progress in some very hard questions, including precise questions in physics. This being said, when you write "the issue will only be decided by physics", do you mean that you are sure that physics can solve that or that if there is a solution it can only come from physics (sorry for the mad precision, but I have spent a few years in pure math before coming back to physics (but not mathematical physics that is for me a branch of applied math that requires talents that I do not have)). I do believe though that it would be useful to all be as precise as we can, be it only to avoid unnecessary confusions and disputes due only to misunderstanding. I feel some convergence, despite apparent divergences of writing: we might mostly need to adjust vocabulary.

Hardly any remaining questions in physics have been or will be solved by people who aren't competent in mathematical physics. At the very least you should be aware of the existing models and their dificiencies before attempting to "solve" any questions.

Bell's result attracts amateurs and crackpots since it can be understood without a huge investment of effort into learning real mathematics and physics. Unfortunately, the resulting discussions are mostly an amusing illustration of mental difficulties rather than anything worthwhile.

charlylebeaugosse

Aug11-10, 04:13 PM

Hardly any remaining questions in physics have been or will be solved by people who aren't competent in mathematical physics. At the very least you should be aware of the existing models and their dificiencies before attempting to "solve" any questions.

Bell's result attracts amateurs and crackpots since it can be understood without a huge investment of effort into learning real mathematics and physics. Unfortunately, the resulting discussions are mostly an amusing illustration of mental difficulties rather than anything worthwhile.

TYVM. I do have over 120 papers, collaboration with some of leading figures in math, a long past in physics as well, and about 80 patents. Yet I have seen in these pages, besides stupid remarks, posts by a few people who either are smart professionals, or that we miss in the labs. Most of the stupid hings about Bell Theory were written by pros: I have no much patience with those papers, and even less with non-professional writings, except if it of very good quality. The same applies to delayed choice, delayed erasure, interferences in general, but of course Bell and related matter is the main crackpots attractor. Yet I think it worthwhile to see if collective thinking can lead us to otherwise hard or get results. I have collaborated all my life and am curious of the value of large scale collaboration (on a single well defined theory problem). We'll see....

JesseM

Aug11-10, 04:23 PM

As I have developed in previous posts, on the basis of writings of Einstein, Fine, and Jammer, Einstein was not a naive realist, at least after 1927, and in fact provided the first (only so far) proof of non-realism in 1931 with Tolman and Podolsky.
When you say he was not a "naive realist", is that in contrast with some other form of realism, or do you think he was not a realist of any kind? And you mention Jammer, is that Max Jammer's book "Einstein and Religion" or some other publication? (if it is that book, do you know what pages discuss Einstein's views on realism?) Also, what publications of Einstein and Fine are you referring to?

RUTA

Aug11-10, 06:05 PM

TYVM. I do have over 120 papers, collaboration with some of leading figures in math, a long past in physics as well, and about 80 patents. Yet I have seen in these pages, besides stupid remarks, posts by a few people who either are smart professionals, or that we miss in the labs. Most of the stupid hings about Bell Theory were written by pros: I have no much patience with those papers, and even less with non-professional writings, except if it of very good quality. The same applies to delayed choice, delayed erasure, interferences in general, but of course Bell and related matter is the main crackpots attractor. Yet I think it worthwhile to see if collective thinking can lead us to otherwise hard or get results. I have collaborated all my life and am curious of the value of large scale collaboration (on a single well defined theory problem). We'll see....

My PhD was in general relativity, but I've been working in the foundations community since 1994. It's just my impression (and I'm a nobody ... ), but I haven't seen any real collaboration, per se. There are some general "groups," the largest seems to be Many Worlds, then the Bohmians, followed by variations on backwards causation, but within any "group" it's pretty much a collection of independent researchers -- nothing unified like research in string theory. I don't know the social dynamics, all I can report is what I perceive. The point is, I wouldn't hold out much hope of generating a large scale unified assault on this problem :smile:

Let me ask you, what approach are you looking to advance?

charlylebeaugosse

Aug11-10, 07:11 PM

My PhD was in general relativity, but I've been working in the foundations community since 1994. It's just my impression (and I'm a nobody ... ), but I haven't seen any real collaboration, per se. There are some general "groups," the largest seems to be Many Worlds, then the Bohmians, followed by variations on backwards causation, but within any "group" it's pretty much a collection of independent researchers -- nothing unified like research in string theory. I don't know the social dynamics, all I can report is what I perceive. The point is, I wouldn't hold out much hope of generating a large scale unified assault on this problem :smile:

Let me ask you, what approach are you looking to advance?

I think about some experiments (thought and/or real) that may help establish or help significantly the non-realist point of view (to be co-authored by all people whose contribution is used, more or less, and in anonymous form if people insist-in which case the PF pseudos would be acknowledged as representing contributors. I have several lines of ideas in mind, probably some based on mistakes of mine. I would propose a few from one line to start with. OR I would start with a less ambitious project such as the analysis of Wheeler Delay type experiments (and then would hope to have Cthugha for instance on board - I am relatively new to QM (6 years) where I hope to bring my experience in qualitative methods acquired in non-linear dynamics (mostly, both math and physics): I am bad at what most pros are good at and better in arcane methods and view points. In fact, what I am most interested in is try this idea that the www can help create big collective brains. This is more important that the first question(s) that would be solved as then, many other could follow. The main reason to have soon a few teams on a few subjects would be to explore what rules work best. We could perhaps even begin with two threads on the same basic subject (two questions about said subject), one with full freedom, one where a subgroup would soon form a sort of police on what is relevant or not and taking care of re-launching the life when needed. That might be more fun and contribution than solving one physics question (of course, not great for people still looking for a job, or a Ph. D.). Maybe I am turning into a relatively young crackpot after all.

DevilsAvocado

Aug11-10, 07:22 PM

Ruta, Devilsavocado, DrChinese, etc. (people of good will and not realist):

...

I wont mind being part of a group that solves a question

I think RUTA and unusualname has some really good points here. Yes, it would be marvelous to put together a group and solve some real mysteries in science, but I think that is to underestimate the problem, to say at least... Right now, in this very thread, we are experiencing "one" who has wander off into "The Hazy Swamp of Crackpots of No Return", believing he has solved "everything" alone, using nothing else but probability. While the real probability for doing just that is not good, not good at all, at least if you are alone...

Fundamentally, EPR-Bell is not a question (or fight) between locality/realism/FTL/LHVT, etc – it’s much bigger than that (and I think RUTA agrees?). The genius(es) that solves this question are going to present the next paradigm in physics, where QM + GR + Gravity = True, and perhaps even TOE.

To me EPR-Bell is a parallel to the Michelson–Morley experiment, and what followed after that, but even more complicated (to solve at least).

I don’t think this is something one solves in a discussion over internet. It’s just too big.

Furthermore, I think it’s a big mistake to make any hasty conclusions on what is right or wrong, if you plan to solve this... no offense, but talking about "dark forces" and "THE ENEMY" and so on, can’t be fruitful before we know for sure, can it?

Also if we look back, it all becomes a little 'amusing'. For many nonlocality is repulsive, unnatural, etc, but it was not that long ago that one of the brightest minds in history, Isaac Newton, found his own law of gravity and the notion of "action at a distance" deeply uncomfortable, so uncomfortable that he made a reservation in 1692:
That one body may act upon another at a distance through a vacuum without the mediation of anything else, by and through which their action and force may be conveyed from one another, is to me so great an absurdity that, I believe, no man who has in philosophic matters a competent faculty of thinking could ever fall into it.

This is funny! And future generations will of course laugh at us and our current 'limitations'! :smile:

And it also fun to discuss this and learn more, so let’s continue! :wink:

charlylebeaugosse

Aug11-10, 07:33 PM

When you say he was not a "naive realist", is that in contrast with some other form of realism, or do you think he was not a realist of any kind? And you mention Jammer, is that Max Jammer's book "Einstein and Religion" or some other publication? (if it is that book, do you know what pages discuss Einstein's views on realism?) Also, what publications of Einstein and Fine are you referring to?
Max Jammer indeed, but the book is (in Amazon):

The Philosophy of Quantum Mechanics: The Interpretations of Quantum Mechanics in Historical Perspective by Max Jammer (Hardcover - June 1974)
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Fines book is:
The Shaky Game (Science and Its Conceptual Foundations series) by Arthur Fine (Paperback - Dec. 15, 1996)
Buy new: $25.00 $22.28

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There is from there an easy way to get to original writings by Einstein.

As for Einstein's realism, he did believe that the Moon did not even need apes I would bet.
But the real issue, I think, is realism at the microscopic level. But I would not like to be considered as an unconditional supporter of A.E., since I am not. I am only bothered a lot by all lies and false info that have lead us to a situation where more physicist (in or close to QM) would relinquish locality and not realism at the miscroscopic level.
For me, it is like having Algebra under the control of bandits, or biology controlled by the creationists. I have posted a lot on my views of Einstein's realism so I would rather stop on that for a while. Also, I only add my physicist's sensitivity to real work done by Jammer and Fine (see also the conference where Fine (?), Jammer, Peirls and Rosen contributed for the 50th anniversary of EPR and other paper here and there, mostly the correspondence of Einstein (mainly with Born, but there are other gems), the Schlipp book, and one pocket book on AE's views on the world where there is more politics than physics but some good pieces anyway) and as much reading of Einstein as I could put my hands on. But as I do not read German, I loose lots of first hand material.

DevilsAvocado

Aug11-10, 07:44 PM

I don't know of any limit to the size of something that can be "screened off" in principle. In practice? Well, that's another matter :smile:

Okay, thanks. I think I have a question regarding "screened off" + BB + CMB... but I must think it over. Hope to see you tomorrow!

charlylebeaugosse

Aug11-10, 09:03 PM

Furthermore, I think it’s a big mistake to make any hasty conclusions on what is right or wrong, if you plan to solve this... no offense, but talking about "dark forces" and "THE ENEMY" and so on, can’t be fruitful before we know for sure, can it?

Also if we look back, it all becomes a little 'amusing'. For many nonlocality is repulsive, unnatural, etc, but it was not that long ago that one of the brightest minds in history, Isaac Newton, found his own law of gravity and the notion of "action at a distance" deeply uncomfortable, so uncomfortable that he made a reservation in 1692:

This is funny! And future generations will of course laugh at us and our current 'limitations'! :smile:

And it also fun to discuss this and learn more, so let’s continue! :wink:

Action at a distance was very odd indeed, like the lack of realism (even if only microscopic) is now. That is what I have read too. I do believe that the reason why locality is more abandoned than realism by professionals of quantum physics is as follows:
Realism is coded in our brain for millions of years, or at least 100,00 years or about, while
the discovery of finite speed of light is very new.
Modern physics has been marked by the destruction of credos (simultaneity, continuity, parity, etc...). Destroying realism by physicist argument, for good (and not as a new credo) would be great. Perhaps more modest goals should be tried first.

BTW: Someone wrote about the need of mathematical physicists in order to solve any big problem. What have they brought to physics that is acknowledged by the rest of the physicists? I have great respect for them, some of the best ones are my friends, but their contributions are more considered as math. There is a funny story about Simon and Feynman where RF asked BS "who are you young man" to which "BS" answered "I am BS", to which it was replied: and "what is your field?". adn BS comments: can you imagine that F did not know about my work? i.e., for me: BS did not even understand that RF couldn't care less about the type of things he was doing.

I hope that mathematical Physicist will have some recognition as physicists some day. Some of them have deep physical intuition beside tremendous technical power, but so far, ....

The power of collective thinking is worthwhile trying if the crackpots are kept away de-facto by ignoring them and if we get some of the people I have seen in my short experience with Phys-Forum. 99% of chance of failure, perhaps 99.99%. But solving one problem would be great, and perhaps those interested in the experience should find 1 or 2 problems that are "a bit" less ambitious than the issue of microscopic realism. Anyway I have spent some of my life trying to solve questions with ow odd for solutions, which helped me solving lesser questions. I would not advise a grad student to spend (much) time on that, but think of the reward if we even only begin to understand how to solve hard question as an open group we can get in other threads to advertise those with questions being attacked, can't we? Now for the "enemy" and the "dark forces", it is not defined by the position but by the use (knowing the truth) or not of false information. I was a realist most of my life and a supporter of non-locality when I heard about the subject and talked to some of the lead authors: this is what brought me into the field. I would not consider badly people with provably wrong positions if I am convinced that they do that by ignorance. Anyway, I do not expect everyone to be exited by trying, and I am prepared to failure, as when I tackle "hard problems" (or very hard ones). I do not expect people to spend much energy before some hope of success becomes a bit more reasonable.

billschnieder

Aug11-10, 11:56 PM

I gave you an abstract list. No mention of anything such as trial. No mention of anything such a physical process. I asked you to give me the probability of one of the entries from the list, and you told me it was impossible despite the fact that this is what is done everyday in your favorite frequentist approach to probability.

Not if we are excluding "finite frequentism", which I already told you I was doing.

So you you are saying if you were not exclusing "finite frequentism" you will be able to give an answer? So, you are effectively picking and triming your definition of probability for argumentative purposes as more of your statements will show below. You are not being serious.

Does your list of four give us enough information to know the frequency of ++ in the limit as the sample size goes to infinity?
Bah! This list is the entire context of the question! The list is the population. True probability of the (++) in the list, is the relative frequency of (++) in the list. This is the frequentist approach, which you now want to abandon in order to stay afloat.

When ever you say the probability of Heads and Tails is 0.5 you are doing it, whenever you say the probability of one face of a die is 1/6, you are doing the exact same thing you now claim is impossible. Go figure.

No, in those cases I am just using the physical symmetry of the object being flipped/rolled to make a theoretical prediction about what the limit frequency would be[/u], perhaps along with the knowledge that empirical tests do show each option occurs with about equal frequency in large samples

Hehe! Do you know of anybody who has ever performed an infinite number of coin or die tosses? I think not. So you can not know what the limit will be as the number of tosses tends toward infinity. And since you have continued to insist on your ridiculous idea that the "true probability" must be defined as the limit as the number of trials tends towards infinity, the above response is very telling.

Furthermore, did you really think I will not notice the fact that you have now abandoned your favorite frequentist approach and now you are using the bayesian approach (see underlined text above) to decide that the P(Heads) = 0.5. If you can use symmetry of the coin to decide that P(Heads) = 0.5, why couldn't you also use symmetry of my abstract list to decide that P(++) is 1/4?? I'm sure if I looked, I will not need to look hard to find a post in which you wrote a list not very different from mine and also wrote P(++) to be 1/4 or similar, without having performed an infinite number of damned "trials". So as I mentioned earlier, you are not being serious, just finding anything you can hang-on to, even if it means contradicting yourself.

I already gave you the answer which is 1/4.

Yes, and that answer is incorrect if we are talking about the "limit frequentist probability", as I already made clear I was doing.

You say it is impossible to calculate an answer, then when I give you the answer, you then say the answer is wrong. How do you know it is wrong, if you are unable to calculate the correct one? You are way off base, and the answer is correct in ANY probabilistic approach.

The relative frequency of (++) in my list is 1/4. Since my list is the population, P(++)=1/4 you do not need any trials to determine this.

Note that the wikipedia article says "close to the expected value", not "exactly equal to the expected value".

An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity

Um, how do you figure? The two statements of mine are entirely compatible, obviously you are misunderstanding something here
It is quite clear from the two statements that if average from the law of large numbers is close to but not equal to the true expectation value, it can not be the definition of the expectation value! Which one is it? The definition of the expectation value can not at the same time be only approximately equal to it!?

Yes, and with that context there isn't enough information to estimate the limit frequentist probability which is the only notion of probability I want to use
...
You can visualize it by thinking that if you would randomly pick an entry from the the list I gave you
Well, that's an entirely separate question, because then you are dealing with a process that can repeatedly pick entries "randomly" from the list for an arbitrarily large number of trials. But you didn't say anything about picking randomly from the list, you just presented a list of [b]results and asked what P(++) was.

It is not an entirely separate question. I did not mention any trials in my question. But you have stated that the only notion of probability you want to use is the "limit frequentist probability", even though initially you just said "frequentist", but if you want to stick to that limited approach, which is only interested in "trials", you could still have provided an answer to the question by imagining what the limit will be if you actually randomly picked items from my list. Is it your claim that this is also impossible?

Secondly, despite my repeated correction of your false statements that I presented "results" or "trials", you keep saying it. You quickly jumped to claim I never mentioned trials, yet in the next sentence, you say I presented "results", even though I never characterized the list as such, and corrected your attempts to characterize it as such multiple times! You are not being honest.

billschnieder

Aug11-10, 11:57 PM

Failing to do the specific thing I said it should do, yes.

According to you, the wikipedia article is wrong. Why don't you correct it. It is obvious you are the one who is way off base and you know it. All the grandstanding is just a way to stay afloat, not a serious argument agains the well accepted meaning of expectation value.

Wikipedia: http://en.wikipedia.org/wiki/Mean
In statistics, mean has two related meanings:
* the arithmetic mean (and is distinguished from the geometric mean or harmonic mean).
* the expected value of a random variable, which is also called the population mean.

Wikipedia: http://en.wikipedia.org/wiki/Expected_value

In probability theory and statistics, the expected value (or expectation value, or mathematical expectation, or mean, or first moment) of a random variable is the integral of the random variable with respect to its probability measure.

That you continue to pursue this strange objection to standard mathematics is very telling.

The law of large numbers says if you would randomly pick a large number of pairs from our given abstract list, the average value will get close to the true expectation value as the number of pairs you pick tends towards infinity.
Again, you said nothing about "randomly picking" from a list, you just gave a list itself and asked for the probabilities of one entry on that list.

Yes, that is exactly what I did, and you answered that it was impossible to do because you wanted to use ONLY a probability approach that involved "trials". So I said, if you really were serious about using ONLY a probability approach that involved "trials", you would have imagined randomly picking an infinite number of pairs from the given list, and still be able to give an answer very close to the "true expectation" I wanted which is simply the relative frequency of (++) in my list, obtained without any trials. You do the same thing for dice and coins and you have done the same thing in you famous scratch-lotto examples, but when doing it here would have proven fatal to your line of argument, you balked.

Well, excuse me for thinking your question was supposed to have some relation to the topic we were discussing, namely Bell's theorem.
While discussing Bell's INEQUALITIES, Not Bell's theorem which we haven't discussed at all, you claimed, and continue to claim that Bell's equation (2) is not a standard mathematical definition for the expectation value of a paired product. So we went down this rabbit trail in order to force you to admit that you are wrong, or be humiliated in the process of trying to defend the ridiculous claim. And you know very well that once you admit that you were wrong, you have no valid response to the rest of my argment, so you are standing your ground. Even though you know fully well that what you are arguing is wrong and borderline dishonest.

Only if you assume by symmetry that it's a "fair" die or coin, in which case you have a reasonable theoretical basis for believing the "limit frequency" of each result would appear just as often as every other one. If you had an irregularly-shaped coin (say, one that had been partially melted) it wouldn't be very reasonable to just assume the limit frequency of "heads" is 0.5.

I gave you the list [(++), (+-), (-+), (--)] and you claimed it was impossible to calculate the probability of (++) in the list. So had I given you [(++), (++), (+-), (-+), (--)] and asked the same question, you will still have claimed it was impossible. But any one who has ever heard anything about probability will immediately realize that each item in the list occurs once and since there are 4 items, P(++) must be 1/4 in the list, for the second one, P(++) will be 2/5. I haven't done anything here other than use the symmetry which is present in the given list to calculate the probability. But you already said those values are wrong, which is very telling.

In statistics, if you are given the population, you can calculate the true probabilities without any trials. It is done every day in the frequentist approach, which you claim to understand!

Not in the "limit frequentist" approach where we are talking about frequencies in the limit as number of times the population is sampled approaches infinity (unless we make some auxiliary assumptions about how the population is being sampled, like the assumption we're using a process which has an equal probability of picking any member of the population)

Oh so now you are saying if given a population from which you can easiliy calculate relative frequencies, you will still not be able to use your favorite "limit frequentist" approach to obtain estimates of true probabilities because the process used to sample the population might not be fair. Wow! You have really outdone yourself. If the "limit frequentist" approach is this useless, how come you stick to it, if not just for argumentation purposes?

There is also such a thing as "finite frequentism" which just says if you have a finite set of N trials, and a given result occurred on m of those trials, then the "probability" is automatically defined as m/N

I have already explained to you multiple times that the list I gave you in the question is an abstract list, not a "result" of "trials". So what you say above is a straw-man argument. And you agreed that I never said anything about trials. So for the last time, be honest about what I asked.

billschnieder

Aug11-10, 11:58 PM

Bell's theorem, and your odd criticisms of it which seem to presuppose a notion of probability different from the limit frequentist notion
We have been discussing Bell's inequality, NOT Bell's theorem. There is a difference.

So can you please just answer the question: are you using (or are you willing to use for the sake of this discussion) the limit frequentist notion of probability, where "probability" is just the frequency in the limit as the number of trials goes to infinity?

No! I am not willing to pick and choose the definition of probability for argumentation purposes. First you said it was ONLY the "frequentist" view you wanted. Now it is ONLY a particular variant of frequentism that you want, except when it involves coins and dice, you really use the "bayesian" view. I'm not interested in that type of pointless excercise.

No, the "standard mathematical definition" of an expectation value involves only the variable whose value you want to find the expectation value for, in this case the product of the two measurement results.
...
In the standard definition would give us:
\sum{i=1}^{N}R_i P(R_i)

Wikipedia: http://en.wikipedia.org/wiki/Expected_value

In general if X is a random variable defined on a probability space (Ω, Σ, P), then the expected value of X, denoted by E(X), <X>, \overline{x}, or E(X), is defined as

E(X) = \int_{\Omega}XdP

...

The expected value of an arbitrary function of X, g(X), with respect to the probability density function f(x) is given by the inner product of f and g:
E(g(X))\int_{-\infty}^{\infty} g(X)f(X)

You are way off base. Bell's equation two is the standard mathematical definition.The only difference between Bell's equation (2) and the last equation above, is that the symbols:
X = λ
g(X) = g(λ) = A(a,λ)*B(b,λ)
f(X) = ρ(λ)

Bell is not trying to redefine anything. He is simply using the standard mathematical definition of expectation value for the paired product. Word games will not save you here.

For the last time, you are the one misrepresenting Bell:

E(a,b) = \int \rho (\lambda ) A(a,\lambda )B(b,\lambda ) d\lambda

Note the dλ, at the end of the expression! There is no expression in Bell's paper as the following:
E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

Your claim that such an expression is missing, because Bell was simplifying for physicists is a cop-out. Furthermore, there is no mention of "limit frequentist", let alone "frequentist" in Bell's paper. You are invoking those terms now only to escape humiliation.

Hopefully you at least agree that in the limit as the number of trials becomes large, the expression for the empirical average below should approach my definition
Your so called definition is not a definition, but an approximation of a certain expectation value, which is different from the one used by Bell. Bell's expectation value is obtained by integrating over all λ as equation (2) of his paper clearly shows. Yours is discretely added over outcomes without regard for λ. It is a non-starter deliberately designed to avoid the pitfall of the uniform ρ(λ) requirement which you know is fatal to your argument.

In that case, does your whole argument hinge on the fact that you think Bell's equation (2) was giving an alternate definition of "expectation value", one which would actually differ from the one I give?
You wish. But NO! I have explained my argument very clearly in point-by-point form and in detail. It is your argument which hinges on the hope that Bell's equation (2) is something other than the application of the standard mathematical definition of the expectation value of a paired product to his situation of interest.

billschnieder

Aug12-10, 12:00 AM

True! Bell was writing for an audience of physicists, who would understand that he didn't mean for (2) to indicate he was totally rewriting the standard meaning of "expectation value"
You have provided no proof that equation (2) from Bell's paper is not simply an application of the standard definition of expectation value of a paired product of functions of λ as the wikipedia article clearly shows:
The expected value of an arbitrary function of X, g(X), with respect to the probability density function f(x) is given by the inner product of f and g:
E(g(X))\int_{-\infty}^{\infty} g(X)f(X)

Please answer my question about whether you are willing to just use the "limit frequentist" notion of probability in this discussion--and if you are, do you see why with this understanding it doesn't make sense to say "ρ(λ) in the sample is not significantly different from ρ(λ) in the population" when you are really just talking about the frequencies of different values of λi in the finite sample, not the frequencies that would be found if we took an infinite sample under the same conditions?

Translation: My argument doesn't make sense in the alternate universe in which your limited frequentist view is what I'm using to make my argument?! Is that the best you can do? I'm done with this rubbish!

Your answer only seems to address the part that your ability to do this "resorting" doesn't guarantee the value of λ was really the same for all three (and you basically seemed to agree but say it doesn't matter), but you didn't address the point that even the "hidden triples" may be different than the imaginary triples you created via resorting. For example, suppose after resorting we find the 10th iteration of the first run is a=+1,b=-1, the 10th iteration of the second run is b=-1,c=-1 and the 10th iteration of the third is a=+1,c=-1. Then we are free to self-consistently imagine that each run had the same triple for iteration #10, namely a=+1,b=-1,c=-1. However, in reality this might not be the case--for example, the 10th iteration of the first run might actually have been generated from the triple a=+1,b=-1,c=+1. So, the statistics of the imaginary triples you come up with after resorting might not match the statistics of actual triples on each run, or on all three runs combined.

You missed this part

If ρ(λ) in the sample is not significantly different from ρ(λ) in the population, then the distribution of the outcomes will not be significantly different. However, just because the distribution of the outcomes is not significantly different is not proof that ρ(λ) is the same. It is a necessary but not a sufficient condition as you still must be able to resort the data.

zonde

Aug12-10, 01:28 AM

I would love to hear Einstein's thoughts about the situation now, given the vast experimental evidence in support of QM over "Einsteinian reality."
Einstein was die hard empiricist. Take for example this remark from his essay (http://www.marxists.org/reference/subject/philosophy/works/ge/einstein.htm):
"To his [Margenau] Sec. I: "Einstein's position . . . contains features of rationalism and extreme empiricism...." This remark is entirely correct."

You should not expect that Einstein as extreme empiricist would have left matters of interpretation of experiments into hands of Aspect and Zeilinger and would not have formulated his own viewpoint.

zonde

Aug12-10, 02:22 AM

I love Einstein, he’s my hero. The question is – do you think that he would have rejected Bell's Theorem and EPR-Bell experiments?
Let me give longer quote from Einstein essay (http://www.marxists.org/reference/subject/philosophy/works/ge/einstein.htm):
"One arrives at very implausible theoretical conceptions, if one attempts to maintain the thesis that the statistical quantum theory is in principle capable of producing a complete description of an individual physical system. On the other hand, those difficulties of theoretical interpretation disappear, if one views the quantum-mechanical description as the description of ensembles of systems.

I reached this conclusion as the result of quite different types of considerations. I am convinced that everyone who will take the trouble to carry through such reflections conscientiously will find himself finally driven to this interpretation of quantum-theoretical description (the Psi-function is to be understood as the description not of a single system but of an ensemble of systems).

Roughly stated the conclusion is this: Within the framework of statistical quantum theory there is no such thing as a complete description of the individual system. More cautiously it might be put as follows: The attempt to conceive the quantum-theoretical description as the complete description of the individual systems leads to unnatural theoretical interpretations, which become immediately unnecessary if one accepts the interpretation that the description refers to ensembles of systems and not to individual systems. In that case the whole "egg-walking" performed in order to avoid the "physically real" becomes superfluous. There exists, however, a simple psychological reason for the fact that this most nearly obvious interpretation is being shunned. For if the statistical quantum theory does not pretend to describe the individual system (and its development in time) completely, it appears unavoidable to look elsewhere for a complete description of the individual system; in doing so it would be clear from the very beginning that the elements of such a description are not contained within the conceptual scheme of the statistical quantum theory. With this one would admit that, in principle, this scheme could not serve as the basis of theoretical physics. Assuming the success of efforts to accomplish a complete physical description, the statistical quantum theory would, within the framework of future physics, take an approximately analogous position to the statistical mechanics within the framework of classical mechanics. I am rather firmly convinced that the development of theoretical physics will be of this type; but the path will be lengthy and difficult."

As you can see direction taken by EPR-Bell experiments is exactly the one Einstein was talking (dreaming) about. They try to investigate behavior of individual particles.
However their interpretation is mainly based on assumption that QM is valid description of individual systems contrary to what Einstein believed.

So I think that Einstein would have discarded without regret any restrictions placed by orthodox QM on local realistic interpretation.

Restriction I am talking about is that the same measurement settings at both sites should give the same outcome with probability of 1.

And how does the Ensemble Interpretation explain if we decide to have very long intervals between every entangled pair in EPR-Bell experiments, let’s say weeks or months? Where is the "Global RAM" situated in a case like this? That fixes the experimentally proved QM statistics, for the whole 'spread out' ensemble??
If we view Ensemble Interpretation as physically realistic interpretation and not as some other metaphysical interpretation we of course can not talk about some "Global RAM".
We can talk only about some "local RAM" that is justifiable by physical dynamics inside equipment used in experiments.

If we decide to have very long intervals between every entangled pair we should expect complete decoherence of entanglement.

ThomasT

Aug12-10, 03:38 AM

... trying to talk reasonable to Bill is a waste of time. He lives in his own little bubble; firmly convinced he represents the "universe", when the fact is that he’s totally lost and totally alone in his "reasoning".DA, I don't know if you know this, but billschnieder is a working scientist. I don't think that either DrC or JesseM are.

I admire your honest efforts to understand the conundra surrounding Bell's theorem. I think that billschnieder, and JesseM, and DrC, and all of us are interested in understanding this stuff. And, honestly, I don't think that any of us have a definitive way of expressing anything about the nature of reality.

billschnieder's expertise and knowledge exceeds yours, and I think you should take that into account, just as you apparently do wrt JesseM and DrC.

These are not easy considerations. If they were, then notable physicists and mathematicians wouldn't still be arguing about them. And, while I appreciate your input and your apparent interest, I think you should focus on the precise arguments being made. I'm not sure they're good arguments. Maybe you can sort it out, and clarify it, for all of us. But, please, focus on the the arguments. They're there to be refuted. So, refute them, or agree with them, or just say that you don't understand them -- and ask some questions. But, please, you and nismaratwork, stop with the 'fanboy' stuff.

ThomasT

Aug12-10, 03:41 AM

I'm with DrC, I also don't believe "the Moon is there when nobody looks." By "when nobody looks" I mean "when not interacting with anything."And when is it ever the case that something is not interacting with anything?

In Relational Blockworld, if the entity "isn't there," i.e., is "screened off," it doesn't exist at all. So, the answer to your question is that there is no Moon to wonder.Come on RUTA, are you saying that your Relational Blockworld is a description of the physical reality?

RUTA

Aug12-10, 07:03 AM

And when is it ever the case that something is not interacting with anything?

When it exhibits wave-like behavior. Once it interacts with its environment, it acquires definite position (particle-like behavior) per decoherence.

RBW is not the only interpretation in which "non-interacting" means "non-existent." I got that idea from Bohr, Ulfbeck and Mottelson. Zeilinger has also been credited with that claim regarding photons.

Come on RUTA, are you saying that your Relational Blockworld is a description of the physical reality?

Absolutely, RBW is an ontological interpretation of QM. What in particular strikes you as unreasonable about this ontology? The non-existence of non-interacting entities (manifested as nonseparability of the experimental equipment)? Or, blockworld?

DrChinese

Aug12-10, 09:19 AM

I'm done with this rubbish!

I can only hope...

An interesting note for those still reading: GHZ theorem, another no-go theorem for local realism, shows that EVERY trial will have QM and local realism giving opposite predictions. I.e.

LR=+1, +1, +1, ...
QM=-1, -1, -1, ...

Guess which is experimentally demonstrated? No statistics required! No ensemble interpretation required!

zonde

Aug12-10, 09:39 AM

An interesting note for those still reading: GHZ theorem, another no-go theorem for local realism, shows that EVERY trial will have QM and local realism giving opposite predictions. I.e.

LR=+1, +1, +1, ...
QM=-1, -1, -1, ...

Guess which is experimentally demonstrated? No statistics required! No ensemble interpretation required!
Are you familiar with GHZ experiments at all?

Anyways
from this paper - Experimental Violation of Local Realism by Four-Photon Greenberger-Horne-Zeilinger Entanglement (http://prl.aps.org/abstract/PRL/v91/i18/e180401)

"In conclusion, we have demonstrated the statistical and nonstatistical conflicts between QM and LR in fourphoton GHZ entanglement. However, it is worth noting that, as for all existing photonic tests of LR, we also had to invoke the fair sampling hypothesis due to the very low detection efficiency in our experiment."

Guess what? Fair sampling hypothesis does not quite hang together with ensemble interpretation.

charlylebeaugosse

Aug12-10, 09:42 AM

I can only hope...

An interesting note for those still reading: GHZ theorem, another no-go theorem for local realism, shows that EVERY trial will have QM and local realism giving opposite predictions. I.e.

LR=+1, +1, +1, ...
QM=-1, -1, -1, ...

Guess which is experimentally demonstrated? No statistics required! No ensemble interpretation required!

Not many places where the use of locality in the usual derivation of GHZ is explicitly explained: do you know any, some, many?
I am talking about Mermin's version using 3 particles, not the original 4 particles configuration.
The use of realism is obvious, of course.
(I will not tell who (among the great expert) thought that locality was not used in GHZ.)

By the way, GHZ is often called: Bell Theorem without Inequality (I mentioned that before as one reason why one should not equate Bell Inequalities
(a form of Boole's inequalities, as pointed out long ago by Itamar Pitowsky in several papers getting deeper and deeper into that matter - this is related to earlier work by Fine) and Bell Theorem as was claimed in a link related to a dispute around billschnieder.

DrChinese

Aug12-10, 10:00 AM

Are you familiar with GHZ experiments at all?

Anyways
from this paper - Experimental Violation of Local Realism by Four-Photon Greenberger-Horne-Zeilinger Entanglement (http://prl.aps.org/abstract/PRL/v91/i18/e180401)

"In conclusion, we have demonstrated the statistical and nonstatistical conflicts between QM and LR in fourphoton GHZ entanglement. However, it is worth noting that, as for all existing photonic tests of LR, we also had to invoke the fair sampling hypothesis due to the very low detection efficiency in our experiment."

Guess what? Fair sampling hypothesis does not quite hang together with ensemble interpretation.

What does Fair Sampling have to do with my comment? If I predict a -1 every time, and you predict +1 every time, and it always comes up -1... Then it doesn't really much matter how often that occurs.

As I have said a million times :smile: all science involves the fair sampling assumption. There is nothing special about GHZ or Bell tests in that regard.

And as I have also said too many times to count: if the GHZ result is due to some unknown weird bias... what is the dataset we are sampling that produces such a result? I would truly LOVE to see you present that one! Let's see:

LR=+1, +1, +1, ...
QM=-1, -1, -1, ...
Actual sample=Oops!

DrChinese

Aug12-10, 10:20 AM

Actually, I had the predictions of LR and QM reversed in my little sample. It should be more like:

QM=+1, +1, +1, ...
LR=-1, -1, -1, ...

See this article from Zeilinger and Pan:

Multi-Photon Entanglement and Quantum Non-Locality (2002) (http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf)

"Comparing the results in Fig. 16.7, we therefore conclude that our experimental results verify the quantum prediction while they contradict the local-realism prediction by over 8standard deviations; there is no local hidden-variable model which is capable of describing our experimental results."

JesseM

Aug12-10, 01:33 PM

DA, I don't know if you know this, but billschnieder is a working scientist. I don't think that either DrC or JesseM are.
In what field? Search arxiv.org (http://arxiv.org/) for author "Bill Schnieder" turns up no results. Likewise, a general google search for "Bill Schnieder" and "abstract" doesn't seem to turn up any papers with abstracts (and most papers these days have at least the abstracts online). Can you link to any work by him?

JesseM

Aug12-10, 02:52 PM

So you you are saying if you were not exclusing "finite frequentism" you will be able to give an answer?
Only if your list was understood as a statistical sample (either a sample drawn from a larger population, or the results of a series of trials), or if you add some conditions like that an experimenter is picking a sample from the "population" represented by the list. In the first case we could use finite frequentism to give probabilities, in the second case we could even use "limit frequentism" if we added the condition that the experimenter was picking randomly using a method that was equally probable (in the limit frequentist sense) to give any entry on the list.

On the other hand, I've never heard of any authority on statistics talking about determining a "probability" from an "abstract list" which is not interpreted as either a sample or a population. If you want to continue with the "abstract list" argument, please find a source where some authority does something like this.
So, you are effectively picking and triming your definition of probability for argumentative purposes as more of your statements will show below.
I had already stated clearly that I was only interested in talking about probabilities defined in the "frequency in limit as number of trials/sample size goes to infinity", since I think these are the only types of probabilities relevant to Bell's derivation. Again, are you willing to at least consider whether Bell's derivation might make sense (and not have the problems of limited applicability you argue for) when his probabilities are interpreted in these terms, or are you basically refusing to consider the possibility of an interpretation of the paper different from your own, suggesting you are not really interested in trying to understand Bell's argument in its own terms but just in making a lawyer-like rhetorical case against him?
Does your list of four give us enough information to know the frequency of ++ in the limit as the sample size goes to infinity?
Bah! This list is the entire context of the question! The list is the population.
You didn't specify that when you first posted the list, and given that all your previous examples of lists of + and -'s involved a series of trials from a run of a given experiment, there was no reason for me to think the list was intended to be something totally different.
True probability of the (++) in the list, is the relative frequency of (++) in the list. This is the frequentist approach, which you now want to abandon in order to stay afloat.
This is just a ridiculous criticism, Bill. I have always been using what I now call the "limit frequentist approach" to avoid your quibbling about finite frequentism (most scientists nowadays also just talk about 'frequentism' when they mean limit frequentism), you can see that in every post where I talked about frequentism I explained I was talking about the limit as the number of trials approached infinity. Go on, find a single post of mine where my own use of probability involved anything other than limit frequentist probabilities; you won't be able to, showing that your "you now want to abandon" comment is either based on totally misreading what I've been saying all along, or knowingly misrepresenting it.
Hehe! Do you know of anybody who has ever performed an infinite number of coin or die tosses? I think not. So you can not know what the limit will be as the number of tosses tends toward infinity.
No, you can never know with absolute certainty what the "limit frequentist" probabilities are, but you can have a high degree of confidence that they are close to some value based on both theoretical arguments (like the symmetry of fair coins) and empirical averages with large numbers of trials. In any case, Bell's derivation does not require us to actually know what the limit frequentist probabilities of anything are, it just assumes they have some objective values (encapsulated in a function like ρ(λ)) and that these objective values have certain properties (like ρ(λ) being independent of the detector settings), and derives inequalities for the expectation values (themselves just weighted sums of objective probabilities for different combinations of results) based on that. If all of Bell's theoretical assumptions about the objective probabilities were correct, then given the law of large numbers it should be very unlikely that the empirical averages for an experiment with a great many trials would violate the inequality if the "true" expectation values (determined by limit frequentist probabilities) obey it.
Furthermore, did you really think I will not notice the fact that you have now abandoned your favorite frequentist approach and now you are using the bayesian approach (see underlined text above) to decide that the P(Heads) = 0.5.
No. First of all, I'm not saying that the P(heads) is actually guaranteed to equal 0.5, just that it's physically plausible that it would be--that's my hypothesis about the true probability, as distinguished from the true probability itself. A theorist who uses limit frequentist definitions when making theoretical arguments about probabilities (like Bell's) is free to use Bayesian methods when trying to come up with an empirical estimate about what the objective probabilities are. But a Bayesian would say the "probability" is just your best estimate (a more 'subjective' definition of the meaning of probability), while a limit frequentist would distinguish between the estimate and the "true" probability.

Second of all, I'm not using the symmetry of the sample space as a basis for my estimate that P(heads)=0.5, I'm using the actual physical symmetry of the coin itself. If I had an irregular coin with more weight on one side than the other I wouldn't make this estimate, despite the fact that the sample space still contains only two possible outcomes so a Bayesian (or Jaynesian) might say the principle of indifference demands our prior distribution assign each outcome an equal probability.

In any case Bell's derivation does not require any estimates of the true limit frequentist probabilities given by ρ(λ). Only once we have derived the inequality do we have to worry about empirical measurements, and here a limit frequentist can just argue that by the law of large numbers, our sample averages are unlikely to differ significantly from the "true" expectation values (determined by the 'true' limit frequentist probabilities) if the number of trials is large enough.
I'm sure if I looked, I will not need to look hard to find a post in which you wrote a list not very different from mine and also wrote P(++) to be 1/4 or similar, without having performed an infinite number of damned "trials".
Nope, you won't be able to, I have been quite consistent about understanding probabilities in terms of the limit frequentist approach, since some of my earliest discussions with you--for example see post #91 from the 'Understanding Bell's Logic' thread (http://www.physicsforums.com/showthread.php?p=2763871#post2763871), posted back in June, where I said:
It's still not clear what you mean by "the marginal probability of successful treatment". Do you agree that ideally "probability" can be defined by picking some experimental conditions you're repeating for each subject, and then allowing the number of subjects/trials to go to infinity (this is the frequentist interpretation (http://en.wikipedia.org/wiki/Frequency_probability) of probability, its major rival being the Bayesian interpretation (http://en.wikipedia.org/wiki/Bayesian_probability)--see the article Frequentists and Bayesians (http://www.statisticalengineering.com/frequentists_and_bayesians.htm)) ... Do you think there are situations where even hypothetically it doesn't make sense to talk about repetition under the same experimental conditions (so even a hypothetical 'God' would not be able to define 'probability' in this way?) If so, perhaps you'd better give me your own definition of what you even mean by the word "probability", if you're not using the frequentist interpretation that I use.
Even earlier than my discussions with you, in January of 2009 I explained to a different poster that I understood derivations of Bell inequalities to involve frequentist probabilities defined in the limit as the number of trials goes to infinity, see this post (http://www.physicsforums.com/showthread.php?p=2026340#post2026340):
I didn't say anything about you knowing the objective facts. Again, the frequentist idea is to imagine a God's-eye perspective of all the facts, and knowing the causal relations between the facts, figure out what the statistics would look like for a very large number of trials.

...

If you believe there are objective facts in each trial, even if you don't know them, then it should be possible to map any statement about subjective probabilities into a statement about what this imaginary godlike observer would see in the statistics over many trials--do you disagree? For example, suppose there is an urn with two red balls and one white ball, and the experiment on each trial is to pick two balls in succession (without replacing the first one before picking the second), and noting the color of each one. If I open my hand and see that the first one I picked was red, and then I look at the closed fist containing the other and guess if it'll be red or white, do you agree that I should conclude P(second will be white | first was red) = 1/2? If you agree, then it shouldn't be too hard to understand how this can be mapped directly to a statement about the statistics as seen by the imaginary godlike observer. On each trial, this imaginary observer already knows the color of the ball in my fist before I open it, of course. However, if this observer looks at a near-infinite number of trials of this kind, and then looks at the subset of all these trials where I saw that the first ball was red, do you agree that within this subset, on about half these trials it'll be true that the ball in my other hand was white? (and that by the law of large numbers, as the number of trials goes to infinity the ratio should approach precisely 1/2?)

If you agree with both these statements, then it shouldn't be hard to see how any statement about subjective probabilities in an objective universe should be mappable to a statement about the statistics seen by a hypothetical godlike observer in a large number of trials. If you think there could be any exceptions--objectively true statements of probability which cannot be mapped in this way--then please give an example. It would be pretty earth-shattering if you could, because the frequentist interpretation of probabilities is very mainstream, I'm sure you could find explanations of probability in terms of the statistics over many trials in virtually any introductory statistics textbook.
So I think it's safe to say I have been quite consistent in my understanding of what "probability" means in the context of Bell's derivation, and any notion of yours that I've been waffling is just another example of your leaping to an uncharitable conclusion when you see any ambiguity in the way I have expressed myself.
You say it is impossible to calculate an answer, then when I give you the answer, you then say the answer is wrong. How do you know it is wrong, if you are unable to calculate the correct one?
What I said (http://www.physicsforums.com/showthread.php?p=2833607#post2833607) in my original response (post #1249) was "No, you can't calculate the probability just from the information provided, not if we are talking about objective frequentist probabilities rather than subjective estimates." If we have some additional information about what the list represents, like that it is a population and we have an experimenter picking a random sample from the population (using a method that we are told has an equal probability of picking any of the four entries, with 'probability' understood in the limit frequentist sense), then we can certainly calculate the probability. I already made this point in post #1277 (http://www.physicsforums.com/showthread.php?p=2835072#post2835072):
Again, you said nothing about "randomly picking" from a list, you just gave a list itself and asked for the probabilities of one entry on that list. If you want to add a new condition about "randomly picking", with "randomly" meaning that you have an equal limit frequentist probability of picking any of the four entries on the list, then in that case of course I agree that P(++)=1/4...well duuuuh! But that wasn't the question you asked.
Now, can we get back to discussing Bell's theorem, and not some silly irrelevant example you came up with to prove I "don't understand probability"?
Note that the wikipedia article says "close to the expected value", not "exactly equal to the expected value".
An "expectation value" like E(a,b) would be interpreted in frequentist terms as the expected average result in the limit as the number of trials (on a run with detector settings a,b) goes to infinity
Um, how do you figure? The two statements of mine are entirely compatible, obviously you are misunderstanding something here
It is quite clear from the two statements that if average from the law of large numbers is close to but not equal to the true expectation value, it can not be the definition of the expectation value! Which one is it? The definition of the expectation value can not at the same time be only approximately equal to it!?
I don't understand the phrase "average from the law of large numbers". The average from any finite number of trials N can be different from the true expectation value, no matter how large of a finite number N we pick. However, the law of large numbers says that in the limit as N approaches infinity, the average approaches the expectation value with probability 1. Another way of putting this is that if we pick some specific real number epsilon between 0 and 1, then no matter how small of an epsilon we pick, the probability that the empirical average (the 'sample mean') differs from the expectation value by an amount greater than or equal to epsilon should become smaller and smaller with greater values of N, approaching 0 in the limit as N approaches infinity. If you're familiar with the official calculus definition of a "limit" in terms of the "epsilon-delta" definition (see here (http://mathworld.wolfram.com/Limit.html)), this should look pretty familiar.
You can visualize it by thinking that if you would randomly pick an entry from the the list I gave you
Well, that's an entirely separate question, because then you are dealing with a process that can repeatedly pick entries "randomly" from the list for an arbitrarily large number of trials. But you didn't say anything about picking randomly from the list, you just presented a list of results and asked what P(++) was.
It is not an entirely separate question.
It is because my original objection was that your problem didn't give enough "information" for any definite answer, and here you are providing more information (the idea that we are randomly picking entries from the list and want to know the probability of picking a given entry).
I did not mention any trials in my question. But you have stated that the only notion of probability you want to use is the "limit frequentist probability", even though initially you just said "frequentist", but if you want to stick to that limited approach, which is only interested in "trials", you could still have provided an answer to the question by imagining what the limit will be if you actually randomly picked items from my list. Is it your claim that this is also impossible?
No, I already told you at the end of post #1277 (http://www.physicsforums.com/showthread.php?p=2835072#post2835072) that this was fine, although you would have to specify that you were picking in a way that gave an equal probability (in limit frequentist terms) of selecting any of the four items on the list, since it's perfectly possible to conceive a method of selection that would make some entries on the list more probable than others (for example, start at the top of the list, if it's 'heads' pick the top entry and if it's 'tails' move to the next entry and repeat this procedure until you either get a heads or get to the last entry on the list...this method gives a probability of 1/2 for picking the first entry, 1/4 for picking the second, 1/8 for picking the third and 1/8 for picking the fourth).
Secondly, despite my repeated correction of your false statements that I presented "results" or "trials", you keep saying it. You quickly jumped to claim I never mentioned trials, yet in the next sentence, you say I presented "results", even though I never characterized the list as such, and corrected your attempts to characterize it as such multiple times! You are not being honest.
Yes bill, every time I colloquially use a word like "result" in a way that could possibly be interpreted as a mischaracterization of something you have said, it proves I am a devious snake who is "not being honest" rather than just that I am an ordinary human who sometimes speaks a bit sloppily. Here I did not intend "result" to explicitly mean the results of a series of trials, it could be any list of data (including a list representing a population of possible 'results' that an experimenter might get when picking randomly from the population)

unusualname

Aug12-10, 03:02 PM

BTW: Someone wrote about the need of mathematical physicists in order to solve any big problem. What have they brought to physics that is acknowledged by the rest of the physicists? I have great respect for them, some of the best ones are my friends, but their contributions are more considered as math. There is a funny story about Simon and Feynman where RF asked BS "who are you young man" to which "BS" answered "I am BS", to which it was replied: and "what is your field?". adn BS comments: can you imagine that F did not know about my work? i.e., for me: BS did not even understand that RF couldn't care less about the type of things he was doing.

I hope that mathematical Physicist will have some recognition as physicists some day. Some of them have deep physical intuition beside tremendous technical power, but so far, ....

Is that supposed to be funny? Modern theoretical physics is mainly mathematical physics, in fact it's been that way for a century or so, the last great achievements by non-mathematicians was probably back in Faraday's time.

The foundations of QM have been debated for nearly a century by many great thinkers, and the conclusion is that nothing will get resolved by "word" arguments about interpretations, there needs to be a model to back up the argument and that model has to be in the language of mathematics.

Of course we need experimental results from which to check our models, and in relation to the question of this thread we have Bell experiments of Aspect et al, GHZ and delayed choice erasure experiments all of which suggest non-locality unless you are a deluded person who thinks a classical explanation makes sense. (The other explanations in terms of reinterpreting reality may have their time, but let's give the physics a chance before opening the gates for the philosophical hordes)

The most promising current model that might account for non-locality seems to be the Holographic Principle, but to properly understand that you need to understand its origins in the work of Bekenstein and Hawking in the 70s on Black Hole Thermodynamics, then you need to understand how it works with current models in String Theory, LQG etc.

This is difficult stuff, with a heavy dose of mathematical formalism. It is the arena where the useful debate about understanding the universe is taking place, not the pseudo philosophical word-play that goes on in these forums.

If you ask the current great Physicists about QM interpretations they will probably admit we are no nearer a resolution, but they do at least know what they're talking about, here's what Joe Polchinski has to say about the fact that String Theory does not attempt to solve the interpretation problem:
This is an interesting question, to which there is no definite answer. On the one hand, since it was possible to quantize the other three interactions without changing the interpretation of QM, it is not obvious that one should not be able to do the same for gravity. If we restrict to `laboratory’ experiments with gravity (even building black holes in the lab), there is no sharp paradox that would require us to modify QM. QM makes us queasy, but if it gives consistent predictions for all processes we may just have to live with that. Things are much less clear when you get to cosmology. Chaotic inflation, for example, does seem to lead to paradoxes, which might be the clue to a deeper understanding of QM

Where in the last sentence he hints at MWI, but as you can see he's more interested in hard physics, not philosophical fluff, (quote taken from his comments in this blog entry (http://blogs.discovermagazine.com/cosmicvariance/2007/05/21/guest-post-joe-polchinski-on-science-or-sociology/) replying to Smolin's The Trouble with Physics)

billschnieder

Aug12-10, 04:00 PM

Nope, you won't be able to, ...

It took me 2 minutes to find this, and it looks worse than I had thought. Pay attention to how you characterized Bell's expectation value. Also pay attention to how you are factorizing ρ(λ), within the summation. There is no escape.

When scratched, any given box will reveal either a cherry or a lemon. Once Alice and Bob have both found the fruit behind the box they choose, they can adopt the convention that a cherry is represented by a +1 and a lemon is represented by a -1, and multiply their respective numbers together to produce a single number for each trial (and that single number will itself be +1 if they both got the same fruit, and -1 if they got different fruits). Then we are interested in the "expectation value" for a given choice of boxes--for example, E(a,b') means the average result Alice and Bob will get after multiplying their numbers together on the subset of trials where Alice chose to scratch box a and Bob chose to scratch box b'. The CHSH inequality then states that if we define the value S by S=E(a,b) - E(a,b') + E(a',b) + E(a',b'), then -2 \leq S \leq 2.

As for the hidden states, there are 16 different possibilities (and here I am replacing each fruit with the number they've chosen to represent it, so a=+1 means that the hidden fruit in box a on Alice's card is a cherry):

1: a=+1, a'=+1, b=+1, b'=+1
2: a=+1, a'=+1, b=+1, b'=-1
3: a=+1, a'=+1, b=-1, b'=+1
4: a=+1, a'=+1, b=-1, b'=-1
5: a=+1, a'=-1, b=+1, b'=+1
6: a=+1, a'=-1, b=+1, b'=-1
7: a=+1, a'=-1, b=-1, b'=+1
8: a=+1, a'=-1, b=-1, b'=-1
9: a=-1, a'=+1, b=+1, b'=+1
10: a=-1, a'=+1, b=+1, b'=-1
11: a=-1, a'=+1, b=-1, b'=+1
12: a=-1, a'=+1, b=-1, b'=-1
13: a=-1, a'=-1, b=+1, b'=+1
14: a=-1, a'=-1, b=+1, b'=-1
15: a=-1, a'=-1, b=-1, b'=+1
16: a=-1, a'=-1, b=-1, b'=-1

In this case, define something like A(a,12) to mean "the value Alice gets if she picks a and the hidden state of the two cards is 12", so going by the above we'd have A(a,12)=-1. Similarly B(b',7)=+1, and so forth. And we can assume that there must be well-defined probabilities for each of the possible hidden states, which can be represented with notation like p(8) and p(15) etc.

Since the expectation value E(a,b) is the average value Alice and Bob get when they multiply their results together in the subset of trials where Alice picks box a and Bob picks box b, we should have: E(a,b) = \sum_{N=1}^{16} A(a,N)*B(b,N)*p(N). Likewise, we should also have E(a,b') = \sum_{N=1}^{16} A(a,N)*B(b',N)*p(N). Combining these gives:

E(a,b) - E(a,b') = \sum_{N=1}^{16} [A(a,N)*B(b,N) - A(a,N)*B(b',N)]*p(N)

With a little creative algebra you can see the above can be rewritten as:

E(a,b) - E(a,b')
.
\ = \sum_{N=1}^{16} A(a,N)*B(b,N)*[1 \pm A(a',N)*B(b',N)]*p(N)
.
\ - \sum_{N=1}^{16} A(a,N)*B(b',N)*[1 \pm A(a',N)*B(b,N)]*p(N)

RUTA

Aug12-10, 04:05 PM

If you ask the current great Physicists about QM interpretations they will probably admit we are no nearer a resolution, but they do at least know what they're talking about, here's what Joe Polchinski has to say about the fact that String Theory does not attempt to solve the interpretation problem:

Where in the last sentence he hints at MWI, but as you can see he's more interested in hard physics, not philosophical fluff, (quote taken from his comments in this blog entry (http://blogs.discovermagazine.com/cosmicvariance/2007/05/21/guest-post-joe-polchinski-on-science-or-sociology/) replying to Smolin's The Trouble with Physics)

Typical response about QM from someone working in unification. I've received similar responses from Witten and Ashtekar (and Smolin in 2002, but his 2006 book shows he's given it more thought since). They're buried in the technical problems associated with the pursuit of a different beast -- unification of the forces and/or quantization of gravity. We need people working on all fronts, but the fronts are too big for any one person to master them all. Likewise, you might ask the author of a particular interpretation of QM how it bears on unification and receive an equally vague answer. In general, both camps (unification and foundations) agree their problems have a common resolution, they're just working on that resolution from different directions.

unusualname

Aug12-10, 04:15 PM

Typical response about QM from someone working in unification. I've received similar responses from Witten and Ashtekar (and Smolin in 2002, but his 2006 book shows he's given it more thought since). They're buried in the technical problems associated with the pursuit of a different beast -- unification of the forces and/or quantization of gravity. We need people working on all fronts, but the fronts are too big for any one person to master them all. Likewise, you might ask the author of a particular interpretation of QM how it bears on unification and receive an equally vague answer. In general, both camps (unification and foundations) agree their problems have a common resolution, they're just working on that resolution from different directions.

I would think the resolution to QM interpretation will fall out rather easily once the "unification" people hit on the correct microscopic description of reality. I can't see how there could be much useful input the other way.

Of course, once it's all resolved someone will point to a passage in Kant which explained it all hundreds of years ago. :rolleyes:

JesseM

Aug12-10, 04:30 PM

According to you, the wikipedia article is wrong.
No, just that it was failing to adequately distinguish between two notions of the "mean" which could lead to certain readers (you) becoming confused. There weren't any statements that were clearly incorrect.
Why don't you correct it.
Your wish is my command. I have edited the opening section of the article to more clearly distinguish between the "sample mean" and the "population mean", and make clear that the expected value is equal to the population mean, not the sample mean:
For a data set, the mean is the sum of the values divided by the number of values. The mean of a set of numbers x1, x2, ..., xn is typically denoted by \bar{x}, pronounced "x bar". This mean is a type of arithmetic mean. If the data set was based on a series of observations obtained by sampling a statistical population, this mean is termed the "sample mean" to distinguish it from the "population mean". The mean is often quoted along with the standard deviation: the mean describes the central location of the data, and the standard deviation describes the spread. An alternative measure of dispersion is the mean deviation, equivalent to the average absolute deviation from the mean. It is less sensitive to outliers, but less mathematically tractable.

If a series of observations is sampled from a larger population (measuring the heights of a sample of adults drawn from the entire world population, for example), or from a probability distribution which gives the probabilities of each possible result, then the larger population or probability distribution can be used to construct a "population mean", which is also the expected value for a sample drawn from this population or probability distribution. For a finite population, this would simply be the arithmetic mean of the given property for every member of the population. For a probability distribution, this would be a sum or integral over every possible value weighted by the probability of that value. It is a universal convention to represent the population mean by the symbol μ.[1] In the case of a discrete probability distribution, the mean of a discrete random variable x is given by taking the product of each possible value of x and its probability P(x), and then adding all these products together, giving \mu = \sum x P(x).[2]

The sample mean may be different than the population mean, especially for small samples, but the law of large numbers dictates that the larger the size of the sample, the more likely it is that the sample mean will be close to the population mean.[3]
As an experiment, let's now see if anyone edits it on the ground that it's incorrect (as opposed to edits for stylistic or other reasons). No fair editing it yourself!
It is obvious you are the one who is way off base and you know it.
So, you wish to completely ignore the quotes from various statistics texts I provided? You trust a user-edited site like wikipedia over published texts? Here they are again:
(edit: See for example this book (http://books.google.com/books?id=3wCWS4VnLJMC&lpg=PA65&dq=%22population%20mean%22%20%22sample%20mean%22&pg=PA65#v=onepage&q=%22population%20mean%22%20%22sample%20mean%22&f=false) which distinguishes the 'sample mean' \bar X from the 'population mean' \mu, and says the sample mean 'may, or may not, be an accurate estimation of the true population mean \mu. Estimates from small samples are especially likely to be inaccurate, simply by chance.' You might also look at this book (http://books.google.com/books?id=1uLGa4eQ05gC&lpg=PA309&dq=%22population%20mean%22%20probability%20distrib ution&pg=PA309#v=onepage&q=%22population%20mean%22%20probability%20distribu tion&f=false) which says 'We use \mu, the symbol for the mean of a probability distribution, for the population mean', or this book (http://books.google.com/books?id=2JfLi3RKRV8C&lpg=PA115&dq=mean%20%22probability%20distribution%22&pg=PA115#v=onepage&q=mean%20%22probability%20distribution%22&f=false) which says 'The mean of a discrete probability distribution is simply a weighted average (discussed in Chapter 4) calculated using the following formula: \mu = \sum_{i=1}^n x_i P[x_i ]').
All the grandstanding is just a way to stay afloat, not a serious argument agains the well accepted meaning of expectation value.

Wikipedia: http://en.wikipedia.org/wiki/Mean

Wikipedia: http://en.wikipedia.org/wiki/Expected_value
Neither of these sources claim that the expected value is equal to the "sample mean" (i.e. the average of the results obtained on a series of trials), which is what I thought you were claiming when you said:
You are given a theoretical list of N pairs of real-valued numbers x and y. Write down the mathematical expression for the expectation value for the paired product.

...

Wow! The correct answer is <xy>
Of course if the "theoretical list" is supposed to represent a population rather than results from a series of trials, and we assume we are picking randomly from the population using a method that has an equal probability of returning any member from the list, in that case I would agree the answer is <xy>. But once again your statement of the problem didn't provide enough information, because the list could equally well be interpreted as a sample, and in that case the expectation value for the paired product would not necessarily be equal to <xy> since <xy> would just be the sample mean--do you disagree?
Again, you said nothing about "randomly picking" from a list, you just gave a list itself and asked for the probabilities of one entry on that list.
Yes, that is exactly what I did, and you answered that it was impossible to do because you wanted to use ONLY a probability approach that involved "trials".
No I didn't, I just said not enough information was provided. If you specify that the list is intended to be a population and we are picking randomly from the population, that's A-OK with me. I already told you this was fine with me at the end of post #1277.
You do the same thing for dice and coins and you have done the same thing in you famous scratch-lotto examples
In the scratch lotto example I explicitly specified that on each trial the experimenters were picking a box at random to scratch, and at some point I bet I even pedantically specified that "at random" means "equal probability of any of the three boxes". With coins and dice it's generally an implicit assumption that each result is equally probable unless the coin/die is specified to be weighted or something.
Well, excuse me for thinking your question was supposed to have some relation to the topic we were discussing, namely Bell's theorem.
While discussing Bell's INEQUALITIES, Not Bell's theorem which we haven't discussed at all
Bell's theorem is just that Bell's inequalities must be obeyed in any local hidden variables theory, and since QM theoretically predicts they will be violated in some circumstances, QM is theoretically incompatible with local hidden variables. Anyway, if you want to be pedantic we're discussing the entirety of Bell's derivation of the inequalities, and whether an analysis of the derivation implies that the inequality is only applicable under some limited circumstances (like it only being applicable to data where it is possible to "resort" in the manner you suggested). My claim is that the correct interpretation of the probabilities in Bell's derivation is that they were meant to be "limit frequentist" probabilities, and that if you look at the derivation with this interpretation in mind it all makes sense, and it shows the final inequalities do not have the sort of limited applicability you claim.
and continue to claim that Bell's equation (2) is not a standard mathematical definition for the expectation value of a paired product.
Nope, it's not. The standard mathematical definition for the expectation value of some variable x (whether it is obtained by taking a product of two other random variables A and B or in some other way) is just a sum or integral over all possible values of x weighted by their probabilities or probability densities, i.e. either \mu = \sum_{i=1}^N x_i P(x_i) or \int x \rho(x) \, dx. You can see that this standard expression for the expectation value involves no variables besides x itself. Now depending on the nature of the specific situation we are considering, it may be that functions like P(x) or ρ(x) can themselves be shown to be equal to some functions of other variables, and this is exactly where Bell's equation (2) comes from. Here, I'll give a derivation:

If x is the product of the two measurement results A and B with detector settings a and b, then according to what I said above the "standard form" for the expectation value should be \mu = \sum_{i=1}^N x_i P(x_i), and since we know that this is an expectation value for a certain pair of detector angles a and b, and that the two measurement results A and B are themselves always equal to +1 or -1, this can be rewritten as:

(+1)*P(x=+1|a,b) + (-1)*P(x=-1|a,b) = (+1)*[P(A=+1, B=+1|a,b) + P(A=-1, B=-1|a,b)] + (-1)*[P(A=+1, B=-1|a,b) + P(A=-1, B=+1|a,b)]

Then in that last expression, each term like P(A=+1, B=+1|a,b) can be rewritten as P(A=+1, B=+1, a, b)/P(a,b). So by marginalization (http://en.wikipedia.org/wiki/Conditional_probability) (and assuming for convenience that λ is discrete rather than continuous), we have:

P(A=+1, B=+1|a,b) = \sum_{i=1}^N \frac{P(A=+1, B=+1, a, b, \lambda_i )}{P(a,b)}

And P(A=+1, B=+1, a, b, λi) = P(A=+1, B=+1|a, b, λi)*P(a, b, λi) = P(A=+1, B=+1|a, b, λi)*P(λi | a, b)*P(a,b), so substituting into the above sum gives:

P(A=+1, B=+1|a,b) = \sum_{i=1}^N P(A=+1, B=+1 | a, b, \lambda_i )*P(\lambda_i | a, b)

And if we make the physical assumption that P(λi | a, b) = P(λi) (the no-conspiracy assumption which says the probability of different values of hidden variables is independent of the detector settings), this reduces to

P(A=+1, B=+1|a,b) = \sum_{i=1}^N P(A=+1, B=+1 | a, b, \lambda_i )*P(\lambda_i )

Earlier I showed that the expectation value, written in its standard form, could be shown in this scenario to be equal to the expression

(+1)*[P(A=+1, B=+1|a,b) + P(A=-1, B=-1|a,b)] + (-1)*[P(A=+1, B=-1|a,b) + P(A=-1, B=+1|a,b)]

So, we can rewrite that as

(+1)*[ \sum_{i=1}^N P(A=+1, B=+1 | a, b, \lambda_i )*P(\lambda_i ) + \sum_{i=1}^N P(A=-1, B=-1 | a, b, \lambda_i )*P(\lambda_i )] + (-1)*[ \sum_{i=1}^N P(A=+1, B=-1 | a, b, \lambda_i )*P(\lambda_i ) + \sum_{i=1}^N P(A=-1, B=+1 | a, b, \lambda_i )*P(\lambda_i )]

Or as a single sum:

\sum_{i=1}^N P(λi) * [(+1*+1)*P(A=+1, B=+1|a,b,λi) + (-1*-1)*P(A=-1, B=-1|a,b,λi) + (+1*-1)*P(A=+1, B=-1|a,b,λi) + (-1*+1)*P(A=-1, B=+1|a,b,λi)]

And naturally if the value of a along with the specific choice of λi completely determine the value of A, and likewise the value of b along with the specific choice of λi completely determines the value of B (another physical assumption), then for any given i in the sum above, three of the conditional probabilities will be 0 and the other will be 1, so it's not hard to see (tell me if you want this step explained further) why the above can be reduced to:

\sum_{i=1}^N A(a,\lambda_i ) B(b, \lambda_i ) P(\lambda_i )

...which is just the discrete form of Bell's equation (2). So, hopefully you require no further proof that although Bell's equation (2) gives one form of the expectation value, it was not meant to contradict the idea that the expectation value can also be written in the standard form:

(+1)*P(product of A and B is +1) + (-1)*P(product of A and B is -1)

...which given the knowledge that both A and B are always either +1 or -1, and A is the result for the detector with setting a while B is the result for the detector with setting b, can be written as:

E(a,b) = (+1*+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (+1*-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1*+1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (-1*-1)*P(detector with setting a gets result -1, detector with setting b gets result -1)

...which is the equation I have been bringing up over and over. Last time I brought it up, you responded in post #1275 with:
False! The above equation does not appear in Bell's work and is not the expectation value he is calculating in equation (2).
Hopefully the above derivation shows you why Bell's equation (2) is entirely consistent with the above "standard form" of the expectation value, given the physical assumptions he was making. If you still don't agree, please show me the specific step in my derivation that you think is incorrect.
Oh so now you are saying if given a population from which you can easiliy calculate relative frequencies, you will still not be able to use your favorite "limit frequentist" approach to obtain estimates of true probabilities because the process used to sample the population might not be fair. Wow! You have really outdone yourself. If the "limit frequentist" approach is this useless, how come you stick to it, if not just for argumentation purposes?
It's useful in theoretical proofs involving probabilities, such as the derivation of the conclusion that Bell's inequality should apply to the "limit frequentist" expectation values in any local realist universe. And for experimental data, as long as the sample size is large we can use empirical frequencies to estimate a range for the limit frequentist probabilities with any desired degree of confidence, even though we can never be 100% confident the true limit frequentist probability lies in that range (but that's just science for you, you can never be 100% sure of any claim based on empirical evidence, even though you can be very very confident).

JesseM

Aug12-10, 04:47 PM

It took me 2 minutes to find this, and it looks worse than I had thought. Pay attention to how you characterized Bell's expectation value. Also pay attention to how you are factorizing ρ(λ), within the summation. There is no escape.
So you had to look to a discussion with a different person from 2009 to find an example? Anyway, if you look closely you'll see that I did mention the assumption that Alice and Bob were picking which box to scratch at random:
The problem is that if this were true, it would force you to the conclusion that on those trials where Alice and Bob picked different boxes to scratch, they should find the same fruit on at least 1/3 of the trials. For example, if we imagine Bob and Alice's cards each have the hidden fruits A+,B-,C+, then we can look at each possible way that Alice and Bob can randomly choose different boxes to scratch, and what the results would be
Maybe I should have been more explicit about the fact that there was a probability of 1/3 that Alice would scratch a given box on any trial, and likewise for Bob, but that was certainly my implicit assumption. And I have spelled it out more explicitly in other posts, for example this one (http://www.physicsforums.com/showthread.php?p=2775568#post2775568) from a discussion with you in June:
That description is fine, though one thing I would add is that in order to derive the inequality that says they should get the same fruit 1/3 or more of the time, we are assuming each chooses randomly which box to scratch, so in the set of all trials the probability of any particular combination like 12 or 22 is 1/9, and in the subset of trials where they picked different boxes the probability of any combination is 1/6.
So yes, I have always assumed the limit frequentist notion of probability in any of my discussions of the lotto card example, and the post you quoted makes perfect sense with that interpretation if you keep in mind that there is a probability (in limit frequentist terms) of 1/9 that Alice and Bob will pick any given combination of boxes on each trial.

As an aside, can you please edit your post to remove the LaTex code after the words "With a little creative algebra you can see the above can be rewritten as"? The equation there is stretching the window badly, making this page hard to read.

ThomasT

Aug12-10, 06:09 PM

When it exhibits wave-like behavior. Once it interacts with its environment, it acquires definite position (particle-like behavior) per decoherence.I like to muse that reality is waves in a hierarchy of media, that the true god's eye view would just see a bunch of interacting waveforms, some bounded or particle-like, and some not, some more persistent than others, etc.

However, at the level of our experience, we see cars and computers and planets and ... moons. I don't think it makes much sense to say that the moon pops into and out of existence depending on whether we happen to be looking at it. The whole quantum-speak thing can get quite silly -- detectors, moons, cats in various 'superpositions' of existing and not existing, of being here and there.

RBW is not the only interpretation in which "non-interacting" means "non-existent." I got that idea from Bohr, Ulfbeck and Mottelson. Zeilinger has also been credited with that claim regarding photons.It seems a bit silly to say that there's nothing moving from emitter to detector. Certainly the more sensible inference or hypothesis, and the one that practical quantum physics is based on, is that quantum experimental phenomena result from the instrumental probings of an underlying reality -- a reality which is presumably behaving according to some set of physical principles and which exists whether it's being probed or not.

Einstein's spooky action at a distance entails spacelike separated events determining, instantaneously, each other's existence. This is, prima facie, a nonsensical notion -- and Einstein was right to dismiss it.

Absolutely, RBW is an ontological interpretation of QM. What in particular strikes you as unreasonable about this ontology? The non-existence of non-interacting entities (manifested as nonseparability of the experimental equipment)? Or, blockworld?It's not unreasonable. Especially if you're a GR person. I just find it conceptually unappealing. Anyway, is there any way to know to what extent some theoretical construction is a description of 'reality'?

JesseM

Aug12-10, 06:34 PM

So can you please just answer the question: are you using (or are you willing to use for the sake of this discussion) the limit frequentist notion of probability, where "probability" is just the frequency in the limit as the number of trials goes to infinity?
No! I am not willing to pick and choose the definition of probability for argumentation purposes.
It's not "for argumentation purposes", it's for trying to understand what Bell actually meant, and how the probabilities in his derivation are interpreted by physicists. Your own argument which claims to show the derivation has very limited applicability is based on using a non-limit-frequentist interpretation of the probabilities in Bell's derivation. My claim is that this problem of limited applicability vanishes if we interpret the probabilities in his derivation in limit frequentist terms. Which is more likely a priori, that some guy posting on the internet is the first one to ever discover a major hole in Bell's derivation which never occurred to Bell or any other physicist, or that Bell and other physicists interpreted the probabilities in limit frequentist terms? (which again is a very common way to think about the meaning of probabilities, not some obscure notion I'm dragging up for the sake of being difficult) Are not even willing to consider that he might have been interpreting probabilities this way, to see if the problem of limited applicability would disappear in this case?
First you said it was ONLY the "frequentist" view you wanted. Now it is ONLY a particular variant of frequentism that you want
In post #1330 I linked back to an earlier discussion with you where I made clear that I was using "frequentist" probabilities to mean frequencies in the limit as the number of trials goes to infinity (what I am now calling 'limit frequentism' in hopes of avoiding exactly the sort of quibbling you're doing above), and an even earlier discussion with another poster from 2009 where I said the same thing, before you even started posting here. Hopefully this puts to rest the notion that I am somehow shifting my position, and if these posts don't convince you I again challenge you to find any posts by me discussing Bell inequalities where I haven't been talking in limit frequentist terms.
except when it involves coins and dice, you really use the "bayesian" view.
Nope, see the three paragraphs in post #1330 starting with "No. First of all, I'm not saying that the P(heads) is actually guaranteed..."
No, the "standard mathematical definition" of an expectation value involves only the variable whose value you want to find the expectation value for, in this case the product of the two measurement results.
...
In the standard definition would give us:
\sum_{i=1}^N R_i P(R_i )
Wikipedia: http://en.wikipedia.org/wiki/Expected_value

E(g(X))\int_{-\infty}^{\infty} g(X)f(X)

The wikipedia equation calculates an expectation value for a function of X rather than X itself, but the important thing is that the expectation value equations always can be reduced to a sum/integral over the product (possible value of variable in question)*P(variable takes that value), summed or integrated over all possible values. For example, if we define a new variable Y=g(X), then it can be shown that the above equation reduces to E(Y) = \int Y * P(Y), which is the "basic form" I have been talking about. This is easier to see if we consider a discrete X and Y, so we want to show that this:

\sum_i g(x_i )f(x_i )

reduces to this:

\sum_j Y_j * P(Y_j )

First consider the case in which each xi gives a unique Yj when plugged into g(x). Then in that case, the probability of a given Yj is naturally going to be the same as the probability of the corresponding xi, and Yj is equal to xi, so the above will be satisfied. On the other hand, suppose there are multiple possible values of xi which, when plugged into g(x), would give the same Yj. Then for that value of j, it is true that P(Yj) = (sum over all values of i for which g(xi)=Yj) f(xi). So in that case, it must be true that for a specific value of j, Yj*P(Yj) = (sum over all values of i for which g(xi)=Yj) g(xi)*f(xi). So from this it's not hard to see why \sum_i g(x_i )f(x_i ) reduces to \sum_j Y_j * P(Y_j )...I don't feel like writing out a formal proof, but if you don't see why what I said above guarantees it, just imagine we have five possible values of x, namely x1, x2, x3, x4, x5, and only two possible values of Y, Y1 and Y2, such that g(x1) = g(x3) = g(x4) = Y1, and g(x2) = g(x5) = Y2. Then if we write out \sum_i g(x_i )f(x_i ) it would be:

g(x1)*f(x1) + g(x2)*f(x2) + g(x3)*f(x3) + g(x4)*f(x4) + g(x5)*f(x5)

And since g(x1) = g(x3) = g(x4) and g(x2) = g(x5), we can gather together terms as follows:

g(x1)*[f(x1) + f(x3) + f(x4)] + g(x2)*[f(x2) + f(x5)]

And since g(x1)=Y1 and g(x2) = Y2, and since P(Y1) = [f(x1) + f(x3) + f(x4)] and P(Y2) = [f(x2) + f(x5)], the above reduces to:

Y1*P(Y1) + Y2*P(Y2)

...which is just \sum_j Y_j * P(Y_j ). Hopefully you can see how this would generalize to arbitrary sums \sum_i g(x_i )f(x_i ) and \sum_j Y_j * P(Y_j ), where every g(xi) yields some Yj.
You are way off base. Bell's equation two is the standard mathematical definition.The only difference between Bell's equation (2) and the last equation above, is that the symbols:
X = λ
g(X) = g(λ) = A(a,λ)*B(b,λ)
f(X) = ρ(λ)
The simplest mathematical definition deals not with the expectation value of a function of a random variable, but an expectation value of the random variable itself; i.e. not E(g(X)) = \int_{-\infty}^{\infty} g(X)f(X) but rather E(Y) = \int Y*P(Y). In any case, I don't really want to discuss the definition of "simple", my claim is just that all expectation values must reduce to that last form, and this is true of Bell's equation (2) as I showed in the derivation near the end of post #1335.
Bell is not trying to redefine anything. He is simply using the standard mathematical definition of expectation value for the paired product.
Any mathematician would understand that whatever form we choose to write an "expectation value", it can always be reduced to the form E(Y) = \int Y*P(Y). Since Bell was ultimately computing the expectation value for the product of the two measurements, if we let Y equal the sum of the two measurements it must be true that his expression can be reduced to (sum over all possible values of Y) Y*P(Y). And I showed that such a reduction is in fact possible (given Bell's physical assumptions) in post #1335.
Note the dλ, at the end of the expression! There is no expression in Bell's paper as the following:
E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)
Your claim that such an expression is missing, because Bell was simplifying for physicists is a cop-out.
No, it's just something that would be understood implicitly by anyone well-versed in probability theory, it isn't necessary to state the obvious. But since it's not obvious to you, again see the explicit derivation in post #1335.
Furthermore, there is no mention of "limit frequentist", let alone "frequentist" in Bell's paper. You are invoking those terms now only to escape humiliation.
I have already linked to posts dating way back where I explained that I interpreted Bell's probabilities in terms of the frequencies in the limit as number of trials goes to infinity, so the idea that I am changing my tune to "escape humiliation" is silly. And no, Bell doesn't mention limit frequentism, but he also doesn't mention any other notion of probability like finite frequentism or Bayesianism, so it's up to readers to interpret the meaning of "probability" in Bell's paper. Again, limit frequentism is pretty much the default assumption in theoretical proofs involving probabilities in science, but even if this weren't true, the mere fact that his derivation has some major holes when his probabilities interpreted in non-limit-frequentist terms, but these holes might disappear when we interpret his probabilities in limit frequentist terms (that is my assertion anyway), is good enough reason for you to at least consider that he might have meant the probabilities in this way before triumphantly proclaiming you have found a flaw in Bell's reasoning that has somehow escaped the notice of every physicist who studied it until now. At least, you should consider this possibility if you have any intellectual integrity and want to do your best to figure out what Bell meant, as opposed to just wanting to make a rhetorical case against him by picking an interpretation designed to make him look bad.

RUTA

Aug12-10, 07:15 PM

I would think the resolution to QM interpretation will fall out rather easily once the "unification" people hit on the correct microscopic description of reality. I can't see how there could be much useful input the other way.

That's certainly the majority opinion. I think the best the foundations community can hope for is to find a new approach to unification, whereas a unified theory would certainly resolve all foundational issues.

As an example of how work in the foundations community might bear on the unification effort, our QM interpretation (Relational Blockworld) suggests a nonseparable Regge calculus approach to classical gravity (where nonseparable means "direct action" in the path integral approach). Obviously, changing classical gravity from Regge calculus (discrete, path integral version of GR) to nonseparable (direct action) Regge calculus, changes the quantum gravity program. It also changes what is meant by "unification," since the dynamical perspective, and therefore forces, are no longer part of a fundamental approach.

I didn't bring up unification per RBW to debate its merits, but merely to point out how the foundations community might contribute to the larger program of unification.

RUTA

Aug12-10, 07:26 PM

However, at the level of our experience, we see cars and computers and planets and ... moons. I don't think it makes much sense to say that the moon pops into and out of existence depending on whether we happen to be looking at it. The whole quantum-speak thing can get quite silly -- detectors, moons, cats in various 'superpositions' of existing and not existing, of being here and there.

For most of us the phrase "not there when nobody looks" is simply a metaphor for the non-existence of non-interacting entities.

It seems a bit silly to say that there's nothing moving from emitter to detector. Certainly the more sensible inference or hypothesis, and the one that practical quantum physics is based on, is that quantum experimental phenomena result from the instrumental probings of an underlying reality -- a reality which is presumably behaving according to some set of physical principles and which exists whether it's being probed or not.

Einstein's spooky action at a distance entails spacelike separated events determining, instantaneously, each other's existence. This is, prima facie, a nonsensical notion -- and Einstein was right to dismiss it.

Well, if QM is right, one (or both) of these things has to go -- you can't have realism and locality. In our interpretation, we punt on realism, i.e., separability.

It's not unreasonable. Especially if you're a GR person. I just find it conceptually unappealing.

Most do :smile:

Anyway, is there any way to know to what extent some theoretical construction is a description of 'reality'?

That's a thorny epistemological question. Better leave that for another thread.

JesseM

Aug12-10, 09:07 PM

There is no expression in Bell's paper as the following:
E(a,b) = (+1)*P(detector with setting a gets result +1, detector with setting b gets result +1) + (-1)*P(detector with setting a gets result +1, detector with setting b gets result -1) + (-1)*P(detector with setting a gets result -1, detector with setting b gets result +1) + (+1)*P(detector with setting a gets result -1, detector with setting b gets result -1)
Your claim that such an expression is missing, because Bell was simplifying for physicists is a cop-out.
Incidentally, in case Bill or anyone else has any further doubts on this point, note that on p. 14 of the paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) Bell does write the expectation value in a basically identical form in equation (13):

E(a,b) = P(yes, yes|a,b) + P(no, no|a,b) - P(yes, no|a,b) - P(no, yes|a,b)

nismaratwork

Aug12-10, 10:46 PM

Incidentally, in case Bill or anyone else has any further doubts on this point, note that on p. 14 of the paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) Bell does write the expectation value in a basically identical form in equation (13):

E(a,b) = P(yes, yes|a,b) + P(no, no|a,b) - P(yes, no|a,b) - P(no, yes|a,b)

I think you need more, like killing a werewolf... take the heart, the head, and burn the body. Even then, I somehow doubt that billy will concede anything. I enjoyed reading the paper however.

ThomasT: Why does the appealing or unappealing nature of an ontology matter? The only thing that is relevant is matching with empirical evidence, the science, and the math. I find the inevitability of death quite unappealing, but I don't doubt it as a result.

zonde

Aug13-10, 02:42 AM

What does Fair Sampling have to do with my comment? If I predict a -1 every time, and you predict +1 every time, and it always comes up -1... Then it doesn't really much matter how often that occurs.
In this experiment photons are created in H/V base but measurements are performed in +45/-45 base (measurement x) and L/R base (measurment y).
If you measure linearly polarized light in base that is rotated by 45° you get completely uncertain result - +1 and -1 have equal probabilities.
If you measure linearly polarized light in circular polarization base you get completely uncertain result as well - +1 and -1 have equal probabilities.
So without detection bias prediction for any measurement in this case is 0.5. That means that composed result from all involved measurements (mind you not output but calculation composed of many different outputs and provided you have algorithm for that) half of the time gives -1 and half of the time gives +1 without detection bias.

Because both involved measurements does not give definite result without detection bias GHZ is comparison of two different detection biases.
So this type of experiments is pure test of fair sampling without involvement of definite outcomes based on particle properties.

As I have said a million times :smile: all science involves the fair sampling assumption. There is nothing special about GHZ or Bell tests in that regard.
I can not claim that I have said this a million times but I have responded like this at least once already:

Yes, that's right. All the science rely on different approximations including fair sampling assumption. But all the science except QM does not blame reality, causality and whatever else when it discovers contradiction in it's conclusions. Instead it admits error and reexamines it's assumptions (including fair sampling assumption) one by one until it resolves contradiction.
So all the science involves the fair sampling assumption but all the science have quite strict rules when to give up fair sampling assumption.

And as I have also said too many times to count: if the GHZ result is due to some unknown weird bias... what is the dataset we are sampling that produces such a result? I would truly LOVE to see you present that one! Let's see:

LR=+1, +1, +1, ...
QM=-1, -1, -1, ...
Actual sample=Oops!

Actually, I had the predictions of LR and QM reversed in my little sample. It should be more like:

QM=+1, +1, +1, ...
LR=-1, -1, -1, ...
From the article you linked:
"First, one performs yyx, yxy, and xyy experiments. If the results obtained are in agreement with the predictions for a GHZ state, then the predictions for an xxx experiment for a local realist theory are exactly opposite to those for quantum mechanics."

So the dataset consists of outcomes for each of yyx, yxy, xyy and xxx experiments.
There are 8 possible different outcomes for each of those 4 experiments that are not even conducted at the same time. 16 of those possible different outcomes (8 outcomes * 4 experiments) are observed much more frequently than other 16. So please provide an algorithm how you get your "output" from 32 different outputs observed in experiment at different times for different setups.

See this article from Zeilinger and Pan:

Multi-Photon Entanglement and Quantum Non-Locality (2002) (http://www.drchinese.com/David/Bell-MultiPhotonGHZ.pdf)

"Comparing the results in Fig. 16.7, we therefore conclude that our experimental results verify the quantum prediction while they contradict the local-realism prediction by over 8standard deviations; there is no local hidden-variable model which is capable of describing our experimental results."
From the same article:
"If we assume the spurious events are just due to experimental errors, we can thus conclude within the experimental accuracy that for each photon, 1, 2 and 3, quantities corresponding to both x and y measurements are elements of reality. Consequently, a local realist, if he accepts that reasoning, would thus predict that for a xxx experiment only the combinations V'V'V',H'H'V',H'V'H', and V'H'H' will be observable (Fig. 16.6b)."

This type of reasoning is not only dispensable for ensemble interpretation but it is even contradicting ensemble interpretation. That's because it completely ignores the role of ensemble in determining outcome of measurement.

DrChinese

Aug13-10, 09:12 AM

So this type of experiments is pure test of fair sampling without involvement of definite outcomes based on particle properties. So all the science involves the fair sampling assumption but all the science have quite strict rules when to give up fair sampling assumption.

From the article you linked:
"First, one performs yyx, yxy, and xyy experiments. If the results obtained are in agreement with the predictions for a GHZ state, then the predictions for an xxx experiment for a local realist theory are exactly opposite to those for quantum mechanics."
...

So I predict that every boy is male and you predict every boy is female. These are the kind of opposite predictions we make (it's an analogy :smile: ). I provide a random but potentially biased sample which consists of all male boys to 8 standard deviations. Now, exactly how is it that we always get male boys? For this to be science - your claim that is - you need to show me a reeeeeeeeeeeeeally big batch of female boys. Where are they?

This is the strict requirement you speak of. It applies to YOU, my friend. You can't claim it is science without showing something!! Absence of evidence actually is evidence of absence when it comes to sampling.

zonde

Aug13-10, 09:34 AM

In this experiment photons are created in H/V base but measurements are performed in +45/-45 base (measurement x) and L/R base (measurment y).
If you measure linearly polarized light in base that is rotated by 45° you get completely uncertain result - +1 and -1 have equal probabilities.
If you measure linearly polarized light in circular polarization base you get completely uncertain result as well - +1 and -1 have equal probabilities.
So without detection bias prediction for any measurement in this case is 0.5.
What about this you do not understand?

So I predict that every boy is male and you predict every boy is female. These are the kind of opposite predictions we make (it's an analogy :smile: ). I provide a random but potentially biased sample which consists of all male boys to 8 standard deviations. Now, exactly how is it that we always get male boys? For this to be science - your claim that is - you need to show me a reeeeeeeeeeeeeally big batch of female boys. Where are they?

This is the strict requirement you speak of. It applies to YOU, my friend. You can't claim it is science without showing something!! Absence of evidence actually is evidence of absence when it comes to sampling.
Yes of course. You tell me what I predict and then easily refute my prediction.
You know how this is called?
A strawmen.

DrChinese

Aug13-10, 10:08 AM

1. What about this you do not understand?

2. Yes of course. You tell me what I predict and then easily refute my prediction.
You know how this is called?
A strawmen.

1. Nothing. What's your point?

2. You are the local realist, what do YOU predict for the xxx case? Does it match QM or not?

JesseM

Aug13-10, 10:24 AM

Max Jammer indeed, but the book is (in Amazon):

The Philosophy of Quantum Mechanics: The Interpretations of Quantum Mechanics in Historical Perspective by Max Jammer (Hardcover - June 1974)
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Fines book is:
The Shaky Game (Science and Its Conceptual Foundations series) by Arthur Fine (Paperback - Dec. 15, 1996)
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There is from there an easy way to get to original writings by Einstein.

As for Einstein's realism, he did believe that the Moon did not even need apes I would bet.
But the real issue, I think, is realism at the microscopic level.
So you think that he would not have been a microscopic realist in the EPR sense? Specifically, if two entangled particles can each be measured on either of two or more noncommuting properties X and Y (like position and momentum), and measuring the value of property X for particle #1 allows us to determine with probability 1 what the value of property X would be for particle #2 if we measured property X for particle #2, then I understand the EPR paper to suggest this means there must be a local "element of reality" associated with particle #2 that predetermines the result it would give for a measurement of property X, even if we actually measure property Y for particle #2.

This quote by Einstein from p. 5 of Bell's paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) does suggest to me he favored microscopic realism in the EPR sense:
If one asks what, irrespective of quantum mechanics, is characteristic of the world of ideas of physics, one is first of all struck by the following: the concepts of physics relate to a real outside world ... It is further characteristic of these physical objects that they are thought of as arranged in a space time continuum. An essential aspect of this arrangement of things in physics is that they lay claim, at a certain time, to an existence independent of one another, provided these objects "are situated in different parts of space".

The following idea characterizes the relative independence of objects far apart in space (A and B): external influence on A has no direct influence on B ...

There seems to me no doubt that those physicists who regard the descriptive methods of quantum mechanics as definitive in principle would react to this line of thought in the following way: they would drop the requirement ... for the independent existence of the physical reality present in different parts of space; they would be justified in pointing out that the quantum theory nowhere makes explicit use of this requirement.

I admit this, but would point out: when I consider the physical phenomena known to me, and especially those which are being so successfully encompassed by quantum mechanics, I still cannot find any fact anywhere which would make it appear likely that (that) requirement will have to be abandoned.

I am therefore inclined to believe that the description of quantum mechanism ... has to be regarded as an incomplete and indirect description of reality, to be replaced at some later date by a more complete and direct one.
I am only bothered a lot by all lies and false info that have lead us to a situation where more physicist (in or close to QM) would relinquish locality and not realism at the miscroscopic level.
Do you really think it's true that "most physicists" would prefer to relinquish locality and not realism? If that were the case I would think Bohmian mechanics would be much more popular! Instead it seems to me that both the Copenhagen interpretation (which abandons 'realism') and the Many-worlds interpretation (whose 'realist' status depends somewhat on how you define 'realism', but it is an interpretation that many advocates say is a completely local one, see my post #8 on this thread (http://www.physicsforums.com/showthread.php?p=1647627#post1647627) for some references along with my own toy model illustrating how a local interpretation involving multiple copies of each experimenter can explain Bell inequality violations without being non-local) are a lot more popular, see some of the polls linked to here (http://en.wikipedia.org/wiki/Many-worlds_interpretation#Reception).
Also, I only add my physicist's sensitivity to real work done by Jammer and Fine (see also the conference where Fine (?), Jammer, Peirls and Rosen contributed for the 50th anniversary of EPR and other paper here and there, mostly the correspondence of Einstein (mainly with Born, but there are other gems), the Schlipp book, and one pocket book on AE's views on the world where there is more politics than physics but some good pieces anyway) and as much reading of Einstein as I could put my hands on. But as I do not read German, I loose lots of first hand material.
Any chance you could post some of Einstein's quotes that you think show he was not a "naive realist" or would not have agreed with the ideas in the EPR paper? If it would take too long to find them and type them up, I will understand of course.

charlylebeaugosse

Aug13-10, 10:26 AM

So I predict that every boy is male and you predict every boy is female. These are the kind of opposite predictions we make (it's an analogy :smile: ). I provide a random but potentially biased sample which consists of all male boys to 8 standard deviations. Now, exactly how is it that we always get male boys? For this to be science - your claim that is - you need to show me a reeeeeeeeeeeeeally big batch of female boys. Where are they?

This is the strict requirement you speak of. It applies to YOU, my friend. You can't claim it is science without showing something!! Absence of evidence actually is evidence of absence when it comes to sampling.

DrC is so right here: see the papers or books on GHZ. The contradiction occurs on every occurrence. Contrary to Bell's inequality- based Bell's Theorem, the GHZ sort, "Bell's Theorem without inequalities" does not use any statistical hypothesis as the story is:
Realism + Locality => An false equality (for each samplE, rather than for some ideal samplING).

No I had asked if anyone has seen a nice explanation of how locality is used. Any hint?

charlylebeaugosse

Aug13-10, 10:33 AM

Is that supposed to be funny? Modern theoretical physics is mainly mathematical physics, in fact it's been that way for a century or so, the last great achievements by non-mathematicians was probably back in Faraday's time.

The foundations of QM have been debated for nearly a century by many great thinkers, and the conclusion is that nothing will get resolved by "word" arguments about interpretations, there needs to be a model to back up the argument and that model has to be in the language of mathematics.

Of course we need experimental results from which to check our models, and in relation to the question of this thread we have Bell experiments of Aspect et al, GHZ and delayed choice erasure experiments all of which suggest non-locality unless you are a deluded person who thinks a classical explanation makes sense. (The other explanations in terms of reinterpreting reality may have their time, but let's give the physics a chance before opening the gates for the philosophical hordes)

The most promising current model that might account for non-locality seems to be the Holographic Principle, but to properly understand that you need to understand its origins in the work of Bekenstein and Hawking in the 70s on Black Hole Thermodynamics, then you need to understand how it works with current models in String Theory, LQG etc.

This is difficult stuff, with a heavy dose of mathematical formalism. It is the arena where the useful debate about understanding the universe is taking place, not the pseudo philosophical word-play that goes on in these forums.

If you ask the current great Physicists about QM interpretations they will probably admit we are no nearer a resolution, but they do at least know what they're talking about, here's what Joe Polchinski has to say about the fact that String Theory does not attempt to solve the interpretation problem:

Where in the last sentence he hints at MWI, but as you can see he's more interested in hard physics, not philosophical fluff, (quote taken from his comments in this blog entry (http://blogs.discovermagazine.com/cosmicvariance/2007/05/21/guest-post-joe-polchinski-on-science-or-sociology/) replying to Smolin's The Trouble with Physics)
I was a bit jocking, but how many Nobel prizes in physics cover papers whose main content was one or more theorems (in a sense accepted by mathematicians). And isn't it true that most mathematical physicists are homed in math dept (a bit less since super-string took control of the budgets in HEPhysics, but
1) what proportion of physicists consider superstring .
2) what proportion of physicists consider superstring as physics.
My main points was in fact that such statements and questions (including mine here) seem far from the subject, and far from physics. As I said, I have an immense consideratio for mathematical physicists.

DevilsAvocado

Aug13-10, 11:10 AM

Let me give longer quote from Einstein essay:

But... this is an essay from 1949. How can this relate to Bell's Theorem?

So I think that Einstein would have discarded without regret any restrictions placed by orthodox QM on local realistic interpretation.

I don’t agree. As you state yourself:

Einstein was die hard empiricist.

I absolutely do not think Einstein would start looking for farfetched loopholes etc. He was way too smart for that. I think he would have accepted the situation, for the start of something new.

Restriction I am talking about is that the same measurement settings at both sites should give the same outcome with probability of 1.

Well, this is pretty obvious, isn’t it?? The completely "new thing" is when polarizers are nonparallel!? Einstein would of course immediately have realized that his own argument had boomeranged on him:
no action on a distance (polarisers parallel) ⇒ determinism
determinism (polarisers nonparallel) ⇒ action on a distance

If we view Ensemble Interpretation as physically realistic interpretation and not as some other metaphysical interpretation we of course can not talk about some "Global RAM".
We can talk only about some "local RAM" that is justifiable by physical dynamics inside equipment used in experiments.

If we decide to have very long intervals between every entangled pair we should expect complete decoherence of entanglement.

Are you saying that if we run an EPR-Bell experiment as I proposed, we "should expect complete decoherence of entanglement" and the experiment would fail? No expected QM statistics??

charlylebeaugosse

Aug13-10, 12:59 PM

A) So you think that he would not have been a microscopic realist in the EPR sense? Specifically, if two entangled particles can each be measured on either of two or more noncommuting properties X and Y (like position and momentum), and measuring the value of property X for particle #1 allows us to determine with probability 1 what the value of property X would be for particle #2 if we measured property X for particle #2, then I understand the EPR paper to suggest this means there must be a local "element of reality" associated with particle #2 that predetermines the result it would give for a measurement of property X, even if we actually measure property Y for particle #2.

B) This quote by Einstein from p. 5 of Bell's paper Bertlmann's socks and the nature of reality (http://cdsweb.cern.ch/record/142461/files/198009299.pdfpapers) does suggest to me he favored microscopic realism in the EPR sense:

(C) Do you really think it's true that "most physicists" would prefer to relinquish locality and not realism? If that were the case I would think Bohmian mechanics would be much more popular! Instead it seems to me that both the Copenhagen interpretation (which abandons 'realism') and the Many-worlds interpretation (whose 'realist' status depends somewhat on how you define 'realism', but it is an interpretation that many advocates say is a completely local one, see my post #8 on this thread (http://www.physicsforums.com/showthread.php?p=1647627#post1647627) for some references along with my own toy model illustrating how a local interpretation involving multiple copies of each experimenter can explain Bell inequality violations without being non-local) are a lot more popular, see some of the polls linked to here (http://en.wikipedia.org/wiki/Many-worlds_interpretation#Reception).

Any chance you could post some of Einstein's quotes that you think show he was not a "naive realist" or would not have agreed with the ideas in the EPR paper? If it would take too long to find them and type them up, I will understand of course.

The EPR paper, say "EPR" for short, was not written, and not even given imprimatur by Einstein, who considered the effect of choosing a measurement, not the outcome of measurements in his own analysis of the completeness of QM. Einstein never used the elements of reality as defined in "EPR". The way "EPR" uses the elements of reality would permit to deduce Bell's ineauality and Richard Friedberg did that as I said and cited in the book of Jammer you emntioned. Yet "EPR" say that elements of reality should be rooted in experiments. If one consider together only what can be measured on ONE pair, then one has at most 2 projections of the spin (in the Bohm-Bell setting), i.e., one measurement per particle, hence not enough data to have a Bell type inequality.

B) Now Einstein had some dose of realism, but so did Heisenberg, Bohr, etc... Einstein gave in 1931 a proof that microscopic realism is false when Bohr and Heisenberg believed in retrodictive compatibility of exact values for conjugate variables. It is about time to not attribute the mistakes of "EPR" to Einstein. See the book of Fine (the Shaky game) beside the book of Jammer. You may find one or two citations of Einstein where he violates microscopic realism in the sense of observables pre-existing measurement (something that happens to have been proven experimentally for EPR particles, but not for enough observables at once to get a Bell type story, of course). Why should I follow you in defining microscopic in the incomplete way used by Podolsky in "EPR"? (since I consider that "It is about time to not attribute the mistakes of "EPR" to Einstein." ) Perhaps I'd be happy with the element of reality if you accept that measurement must be made on one particle at least for any value to make sense as Podolsky hints at but does not do. Invoking a great name for a mistake once may be ok, and even valuable (e.g., to relaunch an issue mistreated by that person where that was not noticed by anyone ), but assuming Einstein was really wrong on realism, why associate his name to that? It would be better to work on science than on means for people to prove themselves smarter that Einstein (not implying you do that, but there is a bad collective behavior).

(C) The situation is a bit more complex than that as most people who declares themselves as "non-realist" have been over the years convinced that the villain that causes the contradiction between Bell's inequalities and nature is locality. Bell did not state his theorem as proving QM non-local: he knew well what he was doing, but, again, read the begining of his 1964 paper, where he implies that that QM had been proven non-local by "EPR". Now there are many more Bohmian than I feel comfortable with and Bell is their hero (see the writtings of Sheldon Goldstein). No if you want to drag me to coocoo land, I would tell you that when I almost died (which lasted a month at least) I could not believe in god, but could not get satisfaction in many world either. I'll see later you post #8 as my navigation prowess is very limited (which is why I hopped DrC would open a vouple of new thread or tell me where to learn how to do that, and why I asked how to upload a file so that I can give reference to it, or post it in some other way).

charlylebeaugosse

Aug13-10, 01:14 PM

But... this is an essay from 1949. How can this relate to Bell's Theorem?

One of the 2 main hypothesis of Bell theorem is that a form of microscopic realism holds trye (a strong form indeed, but let us not be too precise here). By 1931 already, most of the masters of QM, including Einstein, who was more than one of the founding fathers as he participated for a long time, and even his attacks where considered as precious bu Bohr) had been convinced that such microscopic realism did not exist in nature. This was still the main belief in 1949, and the fact that von Neumann (JVN) theorem had a false proof was irrelevant to most of these people (in fact the theories of de Broglie, later to be redone by Bohm, was implicit proof that the proof if not the statement of the non existence of HV by JVN was false). So no more that many great masters in 1964, but how did Feynman (e.g., ) react to that? The official story is that he through Clauser out of his office. Now even that second generation of masters is gone, or in part gone cucu with a few very lucid survivors and Clauser gets a Wolf Price with Aspect and Zeilinger. Thanks whoever, at least these are experimentalists (although not only for Zeilinger at least). But it seems to me that I repeat my posts over and over again.

JesseM

Aug13-10, 01:41 PM

See the book of Fine (the Shaky game) beside the book of Jammer.
The book by Jammer is a bit expensive, but I found an older edition (http://www.amazon.com/Shaky-Game-Einstein-Conceptual-Foundations/dp/0226249476) of the Fine book selling for just a little over three dollars, so I ordered that. Thanks for pointing me to this book, Einstein's life and thought have always interested me and this looks like an interesting reference.
You may find one or two citations of Einstein where he violates microscopic realism in the sense of observables pre-existing measurement (something that happens to have been proven experimentally for EPR particles, but not for enough observables at once to get a Bell type story, of course).
But what exactly do you mean by "observables pre-existing measurement"? For example, if we find that two entangled particles always have opposite spins when measured on the same axis A, one conclusion a local realist might make is that the particles already had a well-defined value for the property "spin on axis A" prior to measurement, and measurement simply revealed it. But a more general local realist conclusion would just be that the particles had properties prior to measurement which predetermined what result they would give if they were measured on axis A, without the assumption that the properties prior to measurement actually bear any resemblance to "spin". I don't necessarily think Einstein would have endorsed the first but I think the Einstein quote from Bell's paper that I posted suggests he would probably have endorsed the second.
No if you want to drag me to coocoo land, I would tell you that when I almost died (which lasted a month at least) I could not believe in god, but could not get satisfaction in many world either.
Well, regardless of whether many-worlds is "satisfying" on a philosophical or spiritual level (and in a certain way I think it could be, but that's probably a topic for the philosophy forum (http://www.physicsforums.com/forumdisplay.php?f=112)), it might at least offer hope for a local interpretation of QM that is "realist" in the sense of offering an objective picture of the world.
I'll see later you post #8 as my navigation prowess is very limited
To see the post you only need to click the link (http://www.physicsforums.com/showthread.php?p=1647627#post1647627).
(which is why I hopped DrC would open a vouple of new thread or tell me where to learn how to do that, and why I asked how to upload a file so that I can give reference to it, or post it in some other way).
If you want to start a new thread, just press the "New Topic" button at the upper left of the list of thread titles on the main quantum physics forum page (http://www.physicsforums.com/forumdisplay.php?f=62). For some instructions on how to include code in your posts that makes links to other pages, see this page (http://www.themcfox.com/THE-NET/uBB-vBB-code.htm). If you want to link to a file you'll have to upload it to some internet page first, you could use a free file-hosting service like Easy Share (http://www.easy-share.com/) to do this.

DrChinese

Aug13-10, 01:56 PM

I'll see later you post #8 as my navigation prowess is very limited (which is why I hopped DrC would open a vouple of new thread or tell me where to learn how to do that, and why I asked how to upload a file so that I can give reference to it, or post it in some other way).

New thread started per your request! :smile:

nismaratwork

Aug13-10, 04:04 PM

What about this you do not understand?

Yes of course. You tell me what I predict and then easily refute my prediction.
You know how this is called?
A strawmen.

That isn't a strawman, it's an analogy. There is a difference, and I'd like to hear your response to it. I've been reading about this "fair sampling bias" as it seems to be a major bone of contention in this thread for dozens of pages... I don't see how Dr. Chinese's question is a diversion, just an attempt to get a straight answer.

charlylebeaugosse

Aug13-10, 09:08 PM

New thread started per your request! :smile:
Thanks a lot. What is the title of that thread (not meaning that people stick to the "subject".

charlylebeaugosse

Aug13-10, 09:32 PM

But what exactly do you mean by "observables pre-existing measurement"? For example, if we find that two entangled particles always have opposite spins when measured on the same axis A, one conclusion a local realist might make is that the particles already had a well-defined value for the property "spin on axis A" prior to measurement, and measurement simply revealed it. But a more general local realist conclusion would just be that the particles had properties prior to measurement which predetermined what result they would give if they were measured on axis A, without the assumption that the properties prior to measurement actually bear any resemblance to "spin". I don't necessarily think Einstein would have endorsed the first but I think the Einstein quote from Bell's paper that I posted suggests he would probably have endorsed the second.

EPR particles are quite particular as there are conservation laws, but those manufest themselves only when a measurement is made. For instance, if Alice measures the normalized spin projection along axis a, Bob will for sure find the opposite value along the same axis. Since Bob can also make a measurement, say along b, one can infer (by a lengthy argument) that both particles had some definite spins, but only along these two axes, and retrodictively. Now Bohr, and in its trace, Heisenberg , admitted retrodictive coexistence of conjugate variables, not even mentioning that EPR particles was the context. To teh contrary, for particles that could hardly have been EPR particles, Einstein, Tolman and Podolsky proved in a Phys Rev Paper of 1931 that such retrodictive coexistence, and even pre-existence of a single observable to its measurement, could not be as otherwise the UP would be violated. They essentially proved a reverse time UP by showing that otherwise, an usual UP would be violated. So the confusion comes from
-a) forgetting the conservation principle, purposely, since
-b) otherwise all projections of the spin would make sense.
BUT, b) is a mistake as the pre-existence is only along directions along the observable make sense, which requires a measurement and when it comes to spin projections, for an EPR pair, at most two spin projections can be measured (one per particle).

This seems odd, but let us compare with Classical Mechanics (CM) and a better known part of QM. If a particle with total momentum zero separates in two in CM, the sum of the projections on the two particles will be zero for ALL directions (at once). In QM, the same zero sum is true for ANY direction, and any is not all. Now, thinl about measurements: in CM, if any measurement can be made, ALL measurements can be made, but by the UP, in QM, any measurement (among spin projection) but not ALL measurements of spin projevtion can be made. When it comes to QM, any is not all !.

This is only a piece of answer to your concerns, but perhaps enough for you to see the light.
I'd be delighted to explain any part that would be weak from the pedagogical point of view. But perhaps other who got that point can help making that clearer with different words. I might have though too much about that thes last years to measure what is clear and what is not, be it only because so many legends have taken control of the main pillar of physics.
(I have already told in one or more posts that in fact I came back to QM because I fell in the trap of non-locality and all the fairy tales that go with it and that only reading for months told me that I had indeed fallen in a trap. With that I disagree with Fine or at lest do not follow him , at least not yet, I must say that his book was the first trace of sanity I could find. His book then indicated others, Jammer and a series of things written by Einstein himself, instead of Podolsky, Bell, or others who played dangerous games with intentions and credos attributed to A.E. (of whom I am absolutely not an unconditional).

JesseM

Aug13-10, 09:40 PM

Thanks a lot. What is the title of that thread (not meaning that people stick to the "subject".
That would be A Bell Theorem with no locality assumption? (http://www.physicsforums.com/showthread.php?t=422089)

JesseM

Aug13-10, 09:56 PM

EPR particles are quite particular as there are conservation laws, but those manufest themselves only when a measurement is made. For instance, if Alice measures the normalized spin projection along axis a, Bob will for sure find the opposite value along the same axis. Since Bob can also make a measurement, say along b, one can infer (by a lengthy argument) that both particles had some definite spins, but only along these two axes, and retrodictively. Now Bohr, and in its trace, Heisenberg , admitted retrodictive coexistence of conjugate variables, not even mentioning that EPR particles was the context. To teh contrary, for particles that could hardly have been EPR particles, Einstein, Tolman and Podolsky proved in a Phys Rev Paper of 1931 that such retrodictive coexistence, and even pre-existence of a single observable to its measurement, could not be as otherwise the UP would be violated.
You mean this paper (http://authors.library.caltech.edu/2129/1/EINpr31.pdf)? But as far as I can tell the paper doesn't show that the particle couldn't have had hidden variables which predetermined what results it would give when its momentum was measured, just that the result of measuring its momentum would be different than its momentum before measurement (the act of measurement changes the momentum). But the concept "particle has hidden variables that predetermine what result it will give to each possible measurement" is logically different from the concept "measurement simply reveals the preexisting value for the variable being measured", my understanding is that Einstein would have endorsed the first but not the second. This is exactly the distinction I was making earlier when I said:
But what exactly do you mean by "observables pre-existing measurement"? For example, if we find that two entangled particles always have opposite spins when measured on the same axis A, one conclusion a local realist might make is that the particles already had a well-defined value for the property "spin on axis A" prior to measurement, and measurement simply revealed it. But a more general local realist conclusion would just be that the particles had properties prior to measurement which predetermined what result they would give if they were measured on axis A, without the assumption that the properties prior to measurement actually bear any resemblance to "spin". I don't necessarily think Einstein would have endorsed the first but I think the Einstein quote from Bell's paper that I posted suggests he would probably have endorsed the second.

ThomasT

Aug15-10, 03:26 AM

For most of us the phrase "not there when nobody looks" is simply a metaphor for the non-existence of non-interacting entities.Ok, but I still have a slight problem with that. It's either that we assume that there's an underlying reality affecting instrumental behavior, or we assume that there isn't. What do you think should be assumed?

It seems a bit silly to say that there's nothing moving from emitter to detector. Certainly the more sensible inference or hypothesis, and the one that practical quantum physics is based on, is that quantum experimental phenomena result from the instrumental probings of an underlying reality -- a reality which is presumably behaving according to some set of physical principles and which exists whether it's being probed or not.

Einstein's spooky action at a distance entails spacelike separated events determining, instantaneously, each other's existence. This is, prima facie, a nonsensical notion -- and Einstein was right to dismiss it.

Well, if QM is right, one (or both) of these things has to go -- you can't have realism and locality.One or both of what things? EPR simply maintained that it's nonsensical to assume that the reality of one particle of an entangled pair is a function of the detection of the other particle. I don't think that the approximate correctness of qm entails that a local realistic description, or intuitive understanding, of entanglement is impossible. But then, a definitive local realistic model of entanglement hasn't been presented yet.

In our interpretation, we punt on realism, i.e., separability.So, what, nonseparability (or inseparability) necessarily entails nonrealism? So, how would you characterize your theory/model/interpretation? As nonrealistic, but local? But this makes no sense. If it isn't, in some sense, realistic, then what does it mean to call it 'local'? Or, are you not calling it either realistic or local? Anyway, didn't you say that your model/interpretation is meant as a realistic description of the underlying ontology? This is the only problem I have with how you talk about it. If you just say that it's a simplification, perhaps even an oversimplification, of the underlying reality, which, given certain mathematical constructions and manipulations, can recover the statistical predictions of standard qm, then I have no problem with a charactarization of that sort.

(your RBW model is) not unreasonable. Especially if you're a GR person. I just find it conceptually unappealing.

Most do.Well, given your obvious talents, are you working on anything that the rest of us might some day be able to actually understand?

Anyway, is there any way to know to what extent some theoretical construction is a description of 'reality'?
That's a thorny epistemological question. Better leave that for another thread.But the main line of argumentation in this thread is about some people saying that Bell's stuff allows inferences about an underlying reality, and others saying that it doesn't. So, where exactly do you stand on this? Does it, or doesn't it? If Bell's stuff is just about models, and a certain class of models at that, then I can't argue with that. What's your opinion? Is it informing us about 'reality', or just informing us about what we can say about 'reality' in a certain form?

ThomasT

Aug15-10, 03:29 AM

ThomasT: Why does the appealing or unappealing nature of an ontology matter?By this I mean its understandability. And understanding has to do with visualizability. Why assume that the fundamental principles of our universe aren't visualizable? After all, we are part of reality. Why not assume that the principles that govern our physical universe pervade and permeate all scales of behavior and interaction? Whether you know it or not, qm is very much based on analogies from ordinary experience. A 'block' conception of reality, vis GR, contradicts our experience. Our universe appears to be evolving. Why not just assume that it 'is' evolving -- that 'change' or 'time' isn't just an illusion, but is real? Why not assume that the fundamental physical principles govern physical behavior at all scales?

Anyway, to get back to your question, if an ontological or epistemological description of 'reality' is at odds with our experience, then I think it should be seriously questioned. I think that this orientation accords with the best traditions of the scientific method. If you think otherwise, then I'm open to learning.

The only thing that is relevant is matching with empirical evidence, the science, and the math.Wrt predicting the results of experiments, I agree. However, this isn't the only thing relevant to 'understanding' or really 'explaining' why things are as they are and why things behave as they do. Just because you can predict something doesn't mean that you understand how and why it happens. Standard qm is an example of this. The problem with the various interpretations of qm as they might relate to your question is that, ultimately, all of the various interpretations of standard qm revert or resort, in one way or another, to the statistical methods of standard qm in order to recover the predictions of standard qm. So, really, nothing is gained except a more or less acceptable, to whomever, 'realistic view', in a certain limited sense -- none of which is a definitive world view precisely because there are other 'world views' which predict exactly the same experimental results.

Wrt the OP of this thread, the question is, does the detection of a particle at detector A, spacelike separated from the 'possible' detection of a particle at detector B, determine the 'existence' of an underlying reality that, it might be assumed, determines the detection attribute registered by detector B? If you think that the answer to this must be, obviously, no, then you agree with EPR, and Einstein. Otherwise, you're a nonlocalist or spookyactionatadistanceist, in which case the onus is on you to demonstrate the physical existence of the spooky (or merely ftl?) propagations/interactions between A and B, or B and A, or whatever.

charlylebeaugosse

Aug15-10, 09:33 AM

You mean this paper (http://authors.library.caltech.edu/2129/1/EINpr31.pdf)? But as far as I can tell the paper doesn't show that the particle couldn't have had hidden variables which predetermined what results it would give when its momentum was measured, just that the result of measuring its momentum would be different than its momentum before measurement (the act of measurement changes the momentum). But the concept "particle has hidden variables that predetermine what result it will give to each possible measurement" is logically different from the concept "measurement simply reveals the preexisting value for the variable being measured", my understanding is that Einstein would have endorsed the first but not the second. This is exactly the distinction I was making earlier when I said:

Non-existence of local realism means of course absence of HV a la Bell/Boh/de Broglie, since those HV are a strong form of microscopic realism (non only one has pre-existence of observable meaning and values to measurement but one also has predictability). Now, HV that are compatible with QM and such that not only what is measured but also whatever makes sense obeys he UP would be acceptable. Scrödinger and Einstein both thought that their contemporaries were too shy by sticky to the usual coordinates, and Fine explain how and why it could be legit to consider them more advanced about the next generation physics that the Copenhagen crowd, and not the contrary. Of course, they only had hopes and not a hint on how to get there, assuming that there is a there. Einstein would not have been long to dismiss the hypothesis of Bell's Theorem as not more physical than the theories of Bohm and de Broglie how which he made fun often. So Born is probably right in thinking that Einstein believed in HVs, but for sure not in the classical ones that Bell used but this is not sure as eh correspondance with Einstein shows that he did not understand anything of the EPR story. AND I cannot imagine Einstein not being saddened by someone putting words in his mouth as Bell does in the introduction of the 1964 paper and in many other places. I mean Bell did not even say "I think that Einstein believed this or that": he claims stuff as facts, a crime against basic scholarly acceptable attitudes and practices. The distinction naive-non-nave HV is for me absolutely crucial. Failing to do it lead simply to a false story and a false description of the physics models that people of importance in the field had in mind. Again, I am not a blind supporter of Einstein: I do not even consider it a big deal that a theory be not complete and I even expect that from any non-trivial theory supposed to cover a big chunk of physics. I also see good reasons to side with Bohr et al, except on the religious asp[ect of their credo and except for the fact that I consider that Schrödinger and Einstein were possibly right about the need to non-trivial new variable to get to some predictability, but a predictability that would not permit to predict nor even to give sense to conjugate variables in the generic case (EPR/ EPRB stories being special because of the conservation laws that provide an ephemeral quasi classic aspect to these particles, till first interactions (which is why such particles do not interfere as do the generic ones).

Hope that this gets clearer or that other may chip in as perhaps I am not clear enough in my English writing (you cross a border and you loose 30% on your IQ , have I been told... but what happens when you go back and forth?????). All that is clear in my mind now, but I have doubt about being understood, or perhaps people do not read well enough (which is often my problem too).

PS: Thanks for the paper: I'll find the time to check, read, and answer about that. In fact, I may have to read more closely what you wrote too.
CleBG

RUTA

Aug15-10, 10:30 AM

Ok, but I still have a slight problem with that. It's either that we assume that there's an underlying reality affecting instrumental behavior, or we assume that there isn't. What do you think should be assumed?

In our view, there is an "underlying reality" responsible for the experimental outcomes, but that "underlying reality" is not "screened off/non-interacting entities" propagating from the source to the detector. The outcomes reflect relations composing the experimental equipment, i.e., relations are fundamental, not "things" like the equipment (or trees or people, etc). In our ontology, there is a rule for the manner in which the experimental equipment ("things" in general) is constructed in the 4D "block." The RBW ontology can be depicted, see Figures 1-4 of arXiv 0908.4348, but it is non-dynamical, which I understand from a previous post you dislike. So, I wouldn't try to convince you that the RBW ontology is a powerful explanatory mechanism :smile:

One or both of what things? EPR simply maintained that it's nonsensical to assume that the reality of one particle of an entangled pair is a function of the detection of the other particle. I don't think that the approximate correctness of qm entails that a local realistic description, or intuitive understanding, of entanglement is impossible. But then, a definitive local realistic model of entanglement hasn't been presented yet.

It is largely agreed within the foundations community that the violation of Bell's inequality entails non-locality and/or non-separability (aka "realism"). The RBW philosopher of science tells me the use of "separability" rather than "realism" is nontrivial, i.e., there is much written about it. I'm not a philosopher, so I just use the terminology as he suggests.

So, what, nonseparability (or inseparability) necessarily entails nonrealism? So, how would you characterize your theory/model/interpretation? As nonrealistic, but local? But this makes no sense. If it isn't, in some sense, realistic, then what does it mean to call it 'local'? Or, are you not calling it either realistic or local? Anyway, didn't you say that your model/interpretation is meant as a realistic description of the underlying ontology? This is the only problem I have with how you talk about it. If you just say that it's a simplification, perhaps even an oversimplification, of the underlying reality, which, given certain mathematical constructions and manipulations, can recover the statistical predictions of standard qm, then I have no problem with a charactarization of that sort.

Yes, RBW is non-separable but causally local. Yes, "non-separable" means "not realism." You have to be careful here not to conflate causal locality with geometric locality, i.e., that used in differential geometry.

Well, given your obvious talents, are you working on anything that the rest of us might some day be able to actually understand?

RBW is counterintuitive but not conceptually challenging. Formally, it's a nightmare (have you ever tried to do Regge calculus?), but its ontology can be depicted -- again, see Fig 1-4 of arXiv 0908.4348. While only an arXiv paper, it has been accepted for presentation at the 2010 PSA meeting (they only take about 10% of all submissions) and it's in the "revise and resubmit" phase at Foundations of Physics, so it has received a couple favorable reviews anyway :smile:

But the main line of argumentation in this thread is about some people saying that Bell's stuff allows inferences about an underlying reality, and others saying that it doesn't. So, where exactly do you stand on this? Does it, or doesn't it? If Bell's stuff is just about models, and a certain class of models at that, then I can't argue with that. What's your opinion? Is it informing us about 'reality', or just informing us about what we can say about 'reality' in a certain form?

I use physics to make ontological inferences. In fact, that's why I do physics. Can I argue that it's reasonable to do so? I wouldn't even try.

charlylebeaugosse

Aug15-10, 12:51 PM

One funny aspect of all that is that it is the absence of realism that permits strong correlations. Assume the observable values correlated to each other on each particles, as when one assumes locality. Then if three spin projections make sense at once, on eget another form of Bell Theorem. I one has one projection per particles (alone or in a pair), no Bell inequality but at most trivial and true ones. If one has at most two projections for a pair, still no Bell inequality but trivial and true ones.

Other funny thing, that makes me rather sad indeed: if one abandon realism, no good reason to have non-locality. So one has to violate, without any experimental baking,
- realism that intuitively should come with the superposition principle and the uncertainty principle,
- and locality that is natural with relativity

where just abandoning local realism would do. The general practice of physics should have eradicated the realism and non-locality for a long time. It was eradicated till Bell, except for a few isolated examples. Now, we have to work hard to come back to non-realism (always in the microscopic -and classical-sense -where "and classical" is to not dismiss, at least not now, the people from CQT who follow Griffith, Omnes, Hartle, Gell-Mann and now Hohenberg) and locality. One good thing is that non-realism should be taken much more seriously than ever before, as a discussion of "Interferences (the usual ones), Wheeler's delayed choice and related delayed choice issues" would reveal, I am sure.

RUTA

Aug15-10, 02:14 PM

Other funny thing, that makes me rather sad indeed: if one abandon realism, no good reason to have non-locality. So one has to violate, without any experimental baking,
- realism that intuitively should come with the superposition principle and the uncertainty principle,
- and locality that is natural with relativity

where just abandoning local realism would do.

I assume you mean to say "if one abandons realism, there is no good reason to have locality." Then you conclude "one has to violate ... locality that is natural in relativity."

In Relational Blockworld we have locality and separability in the classical (statistical) limit of an underlying graphical spacetime structure. There is non-separability at the level of individual relations (graphical level), but Poincare invariance (which includes Lorentz invariance) holds at the graphical level.

So, the point is, you can create a model that is non-separable ("not realism") and local at the quantum level while becoming separable in a statistical limit (classical limit).

DevilsAvocado

Aug15-10, 02:51 PM

By this I mean its understandability. And understanding has to do with visualizability. Why assume that the fundamental principles of our universe aren't visualizable? After all, we are part of reality. Why not assume that the principles that govern our physical universe pervade and permeate all scales of behavior and interaction? Whether you know it or not, qm is very much based on analogies from ordinary experience. A 'block' conception of reality, vis GR, contradicts our experience. Our universe appears to be evolving. Why not just assume that it 'is' evolving -- that 'change' or 'time' isn't just an illusion, but is real? Why not assume that the fundamental physical principles govern physical behavior at all scales?

Very nice post TT.

I agree; we all want the world to be logical and understandable. No one wants it to be horrible, incomprehensible or 'magical'. We want to know that it all works the way we 'perceive' it. We also want nature to be 'homogeneous' on all scales. It’s very logical and natural, and I agree.

But I think it could be a mistake... or at least lead to mistakes.

A classical mistake is when one of the brightest minds in history, Albert Einstein, did not like what his own field equations for theory of general relativity revealed – the universe cannot be static.

Albert Einstein was very dissatisfied, and made a modification of his original theory and included the cosmological constant (lambda: Λ) to make the universe static. Einstein abandoned the concept after the observation of the Hubble Redshift, and called it the '"biggest blunder" of his life.

(However, the discovery of cosmic acceleration in the 1990s has renewed interest in a cosmological constant, but today we all know that the universe is expanding, even if that was not Albert Einstein’s logical hypothesis.)

Another classical example is Isaac Newton, who found his own law of gravity and the notion of "action at a distance" deeply uncomfortable, so uncomfortable that he made a strong reservation in 1692.

We must learn from this.

I think that humans have a big "ontological weakness" – we think that the human mind is "default" and the "scientific center" of everything in the universe, and there are even some who are convinced that their own brain is greatest of all :smile:. But there is no evidence at all that this is the case (please note: I’m not talking about "God").

One extremely simple example is "human colors". Do they exist? The answer is No. Colors only exist inside our heads. In the "real world" there is only electromagnetic radiation of different frequency and wavelength. A scientist trying to visualize "logical colors" in nature will not go far.

Anyway, to get back to your question, if an ontological or epistemological description of 'reality' is at odds with our experience, then I think it should be seriously questioned. I think that this orientation accords with the best traditions of the scientific method. If you think otherwise, then I'm open to learning.

Have you ever tried to visualize a four-dimensional space-time? Or visualize the bending and curving of that 4D space-time?? To my understanding, not even the brightest minds can do this?? Yes, it works perfectly in the mathematical equations, but to imagine an "ontological description" that fits "our experience"... is this even possible?? Yet, we know it’s there, and we can take pictures of it in the form of gravitational lensing on the large cosmological scale:

http://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Gravitationell-lins-4.jpg/500px-Gravitationell-lins-4.jpg
Abell 1689 is a galaxy cluster in the constellation Virgo

Does this fits your picture of a "logical reality"...?
– What’s the weather today honey?
– I don’t know... it looks BENT!?!?

Wrt predicting the results of experiments, I agree. However, this isn't the only thing relevant to 'understanding' or really 'explaining' why things are as they are and why things behave as they do. Just because you can predict something doesn't mean that you understand how and why it happens.

I don’t think mainstream science claims the full understanding of EPR-Bell experiments, it’s still a paradox. What is a fact though is that either locality and/or realism have to go if QM is correct (and QM is the most precise theory we got so far):
Bell's Theorem proves that QM violates Local Realism.

Wrt the OP of this thread, the question is, does the detection of a particle at detector A, spacelike separated from the 'possible' detection of a particle at detector B, determine the 'existence' of an underlying reality that, it might be assumed, determines the detection attribute registered by detector B? If you think that the answer to this must be, obviously, no, then you agree with EPR, and Einstein. Otherwise, you're a nonlocalist or spookyactionatadistanceist, in which case the onus is on you to demonstrate the physical existence of the spooky (or merely ftl?) propagations/interactions between A and B, or B and A, or whatever.

This is spot on the problem, in several "dimensions". There seems to be some in this thread that for real thinks that Einstein would have stuck to his original interpretation of the EPR paradox, despite the work of John Bell and the many experimentalists who are verifying QM predictions and Bell's Theorem, time after time. I’m pretty sure that this would not have been the case. Just look at the cosmological constant and Hubble Redshift. Einstein changed his mind immediately. He did not start looking for "loopholes" in Hubble's telescope or any other farfetched 'escape' – he was a diehard empiricist.

We already know that there are problems in getting full compatibility between QM and GR when it comes to gravity in extreme situations, and EPR-Bell is just another verification of this incompatibility. If we try to solve the EPR-Bell situation as a "spookyactionatadistanceist" we get problems with SR and Relativity of Simultaneity (RoS) (http://en.wikipedia.org/wiki/Relativity_of_simultaneity) + problems with QM and the No-communication theorem (http://en.wikipedia.org/wiki/No-communication_theorem). If we try to solve it as a "surrealist" (non-separable/non-realism) we get the problems RUTA is struggling with.

So this question is definitely NOT solved, and it’s definitely NOT easy.

But, let’s not make it too easy by saying the problem doesn’t exist at all, because there’s still QM-incompatible gravity dragging us down, and it will never go away... :wink:

charlylebeaugosse

Aug15-10, 07:52 PM

I assume you mean to say "if one abandons realism, there is no good reason to have locality." Then you conclude "one has to violate ... locality that is natural in relativity."

In Relational Blockworld we have locality and separability in the classical (statistical) limit of an underlying graphical spacetime structure. There is non-separability at the level of individual relations (graphical level), but Poincare invariance (which includes Lorentz invariance) holds at the graphical level.

So, the point is, you can create a model that is non-separable ("not realism") and local at the quantum level while becoming separable in a statistical limit (classical limit).

No I conclude that the Occam Razor would tell us to abandon realism so that there would not be any reason to invoke non-locality to escape the contradiction that results from Bell's inequalities. Abandoning realism would not let one have GHZ either. Hot having realism brings us back to what people thought till 1963. Now of course, the opinion of the masters (who created QM and its origins, except for de Broglie who remained realist) on realism is no more enough and to get rid of the weak statements about local realism, we have to show that microscopic realism is indeed false as the Copenhagen school though and as Einstein partly proved already in 1931 with Tolman and Podolky (then all statements against local realism would be obsolete: if there is no realism, of course there is no "local realsim", no " blue realism'; adjectives beside realism become moot , and this is what I want to prove, as a few others. But physics is not math and one often needs several "proofs" to cover as many philosophical points of view as one can: one proof of non existence of realism will convince some but not other. Decisive proofs belong to the realm of mathematics (including logic) and in physics , one has more or less decisive arguments, usually resting on experiments some of which being possibly thought experiments.

Sometimes, for very weak statements such as "local realism is false" where one would like "realism is false" (very weak because from 1927 to 1963 the admitted status was" local (naive) realism is not what one has in nature"), one can get a contradiction with experiment so obvious that one does not need many "proofs" to convince enough people. The problem here is that so many legends, misquotations etc have spoiled the subject that many people got confused, to the points that many leading experts of the next generations after the founding fathers have said and written very false statements about non-locality, e.g., that non-locality follows from the type of experiments that Clauser, Aspect, Gisin, Zeilinger, their teams and other teams have done on the Bphm-Bell version of EPR pairs.

I have realized only recently that the strength of the arguments against local realism indicate by itself that the result is probably too weak (which I claim for many reasons). This being said, when one says "proof" one should recall that one deals with proofs in the sense of Physics. For instance fair sampling is not proven, et there are better known issues.
What is clear is that the description of history that accompany Bell's theory is very much lacking precision and accuracy and this has caused many misconceptions and false statements.

This is about the very beginning of the quote. I cannot make sense of the rest as there are other things that should also be the contrary of what is written: for instance, separability relates to locality and not to realism. This being said, getting macroscopic realism out of microscopic realism is something that I believe happens but that I would be happy to see a proof of, even if a very simple model if the discussion os precise and rigorous enough: does a reference exist?

charlylebeaugosse

Aug15-10, 08:35 PM

Any chance you could post some of Einstein's quotes that you think show he was not a "naive realist" or would not have agreed with the ideas in the EPR paper? If it would take too long to find them and type them up, I will understand of course.

The book of Fine, the Shaky Game, that you have bought contains examples and references to more. I have cited many times the ETP paper of 1931 which has been uploaded by someone these last days (perhaps you(???) after the post that I quote now). In teh Born Einstein correspondence, one see Einstein making fun twice of the theories of de Brolie and Bohm, which EXACTLY means that he considered the type of microscopic realism used by Bell for his 1964 theorem way too naive to correspond to the laws of nature. AND Einstein gave several versions of the main point of the EPR paper (or "EPR"), that he mostly formulated as "either there is non-locality (something unacceptable to Bohr according to Popper who discussed with Bohr, many times I think (???) or QM is incomplete. he considered the version of Podolsky, i.e., "EPR" too obscure and missing the main point(s). In all these proofs/arguments that Einstein wrote on QM non complete (in letters or published) he NEVER used elements of reality. As proofs belong to math including logic, you do not expect that I will prove my views on Einstein's opinion, but see Fine's book on that matter and Einstein's writing including the 1931 ETP paper and
the report of the state of the EPR subject as described by Einstein in 1933 (2 years before "EPR") given by Rosenfeld, Bohr's close collaborator where you will learn that Einstein used himself the word "paradox" in the context of the problem covered by "EPR", while many contemporary "masters" state that the word "paradox" got eventually attacked to that matter by the community of physicists who understood that something was wrong with the argument, or other nonsenses of the same kind. Some of these new "masters" got me excited with non-locality and it took me a few weeks if not a few months of intensive reading originals and books such as Fine's and some by Jammer for instance (but also other sources) to see how deeply and widely polluted the subject was. Many disciplines would collapse with that level of non-professionalism by the masters. I cannot imagine something of that kind happening in math (and this is not directly because of the difference of nature between math and physics). Well, I prefer to write about physics issues as I am not an historian anyway.

RUTA

Aug15-10, 09:03 PM

This is about the very beginning of the quote. I cannot make sense of the rest as there are other things that should also be the contrary of what is written: for instance, separability relates to locality and not to realism.

Separability relates to realism, not causal locality. Are you thinking "locality" in the sense of a differentiable manifold being locally homeomorphic to the reals? That's constitutive locality, not causal locality.

This being said, getting macroscopic realism out of microscopic realism is something that I believe happens but that I would be happy to see a proof of, even if a very simple model if the discussion os precise and rigorous enough: does a reference exist?

We get macroscopic separability from microscopic nonseparability in arXiv 0908.4348. We can't discuss that paper here, it's still under review (revise & resubmit stage). I only made reference to it as an example of nonseparable and local going to separable and local in a statistical sense. I have trouble following your posts and (mistakenly?) thought you were claiming that one couldn't have a nonseparable and local underlying theory.

zonde

Aug16-10, 04:15 AM

1. Nothing. What's your point?
I was explaining what is prediction for full sample from LR perspective.

2. You are the local realist, what do YOU predict for the xxx case? Does it match QM or not?
In case of full sample LR prediction is that all possible outcomes happen with equal probabilities:
P(H'H'H')=1/8
P(H'H'V')=1/8
P(H'V'H')=1/8
P(H'V'V')=1/8
P(V'H'H')=1/8
P(V'H'V')=1/8
P(V'V'H')=1/8
P(V'V'V')=1/8
It matches QM with complete decoherence.

QM prediction for ideal case (no decoherence at all) was:
P(H'H'H')=1/4
P(H'H'V')=0
P(H'V'H')=0
P(H'V'V')=1/4
P(V'H'H')=0
P(V'H'V')=1/4
P(V'V'H')=1/4
P(V'V'V')=0

Observed result was roughly:
P(H'H'H')=7/32
P(H'H'V')=1/32
P(H'V'H')=1/32
P(H'V'V')=7/32
P(V'H'H')=1/32
P(V'H'V')=7/32
P(V'V'H')=7/32
P(V'V'V')=1/32

DevilsAvocado

Aug16-10, 05:18 AM

zonde, it would be interesting if you could reply to the last question in this post (http://www.physicsforums.com/showpost.php?p=2837946&postcount=1350).

DevilsAvocado

Aug16-10, 06:20 AM

In Relational Blockworld, if the entity "isn't there," i.e., is "screened off," it doesn't exist at all. So, the answer to your question is that there is no Moon to wonder :smile:

RUTA, I have been thinking (for once :smile:).

If everything that is "screened off" does not exist, I guess that photons emitted in an earlier "process", "traveling" thru vacuum without any interaction, do not exist, right?

But if the photons in the Cosmic Microwave Background (http://en.wikipedia.org/wiki/CMB) (CMB) that have been traveling thru the space since the "last scattering", 400 000 years after the Big Bang, did not exist until they bumped in to one of humans apparatus – How can the CMB be stretched out (redshifted) during billions of years if it DID NOT EXIST...?:bugeye:?

We do have pretty good data of the CMB from COBE (http://en.wikipedia.org/wiki/Cosmic_Background_Explorer), WMAP (http://en.wikipedia.org/wiki/WMAP) and now lately Planck (http://en.wikipedia.org/wiki/Planck_(spacecraft)):

http://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/PLANCK_FSM_03_Black.jpg/800px-PLANCK_FSM_03_Black.jpg

How do you explain this?

zonde

Aug16-10, 06:44 AM

But... this is an essay from 1949. How can this relate to Bell's Theorem?

I don’t agree. As you state yourself:

I absolutely do not think Einstein would start looking for farfetched loopholes etc. He was way too smart for that. I think he would have accepted the situation, for the start of something new.
Well, you was asking about hypothetical "what if" situation.
There are no solid arguments to defend either position so I think that we can safely leave it at that - we disagree.

Well, this is pretty obvious, isn’t it?? The completely "new thing" is when polarizers are nonparallel!? Einstein would of course immediately have realized that his own argument had boomeranged on him:
no action on a distance (polarisers parallel) ⇒ determinism
determinism (polarisers nonparallel) ⇒ action on a distance
Here I would not agree that this ("polarisers nonparallel") is completely new thing because it is essentially HUP.

You are trying to ascribe to Einstein non-contextual determinism a la Bell. But that was not position of Einstein. His position was Ensemble Interpretation and it's essence is contextuality. Ensemble is a factor in determining measurement outcome for individual photon so it is related to context of individual measurement.

Are you saying that if we run an EPR-Bell experiment as I proposed, we "should expect complete decoherence of entanglement" and the experiment would fail? No expected QM statistics??
Yes, experiment would fail.
When you take theoretical QM predictions you disregard experimental imperfections. That is so more or less everywhere in theory.
But when you come to experimental verification you substitute idealized theoretical prediction with something like: theoretical prediction + experimental imperfections, with the aim to minimize these experimental imperfections.
For QM one of possible experimental imperfections has a name "decoherence" except if you specifically explore decoherence.
So when the effect from "experimental imperfections" is too high experiment is a failure. But it does not falsify theory. It is simply not useful in this case.

So the answer to your question: "No expected QM statistics?" is that result of experiment would not allow to determine QM statistics as decoherence would be too high.

JesseM

Aug16-10, 06:53 AM

Non-existence of local realism means of course absence of HV a la Bell/Boh/de Broglie,
But is there any reason to think Einstein believed in the "non-existence of local realism"?
since those HV are a strong form of microscopic realism (non only one has pre-existence of observable meaning and values to measurement but one also has predictability). Now, HV that are compatible with QM and such that not only what is measured but also whatever makes sense obeys he UP would be acceptable.
But what does it even mean for hidden variables to obey the uncertainty principle? For example, suppose we believe that measurement invariably alters the momentum of a particle, so that the momentum you measure at time T is always different from the momentum immediately before measurement. But suppose that before measurement, there were already hidden variables associated with the particle that predetermined what momentum would be measured if the particle's momentum was measured at time T. Would Einstein have said that such a theory was impossible? What if it was impossible to measure all the hidden variables simultaneously, so it was impossible to use them to determine both the position and momentum at a single time?

Anyway, did Einstein consider the uncertainty principle to be "sacred", not to be overturned even in future theories? Some of his thought-experiments with Bohr tried to find ways to violate it, though perhaps Bohr's answers convinced him that it was a basic principle of nature.
Einstein would not have been long to dismiss the hypothesis of Bell's Theorem as not more physical than the theories of Bohm and de Broglie how which he made fun often.
Bohm and de Broglie was a speculative idea about non-local hidden variables, but Bell gave a general proof that a wide class of local hidden variables theories were incompatible with QM--do you think Einstein would have denied this conclusion?
So Born is probably right in thinking that Einstein believed in HVs, but for sure not in the classical ones that Bell used but this is not sure as eh correspondance with Einstein shows that he did not understand anything of the EPR story.
What do you mean by "classical ones"? What would a non-classical hidden variables theory look like?

DevilsAvocado

Aug16-10, 07:57 AM

Here I would not agree that this ("polarisers nonparallel") is completely new thing because it is essentially HUP.

Is this really correct?? According to Wikipedia:
In quantum mechanics, the Heisenberg uncertainty principle states by precise inequalities that certain pairs of physical properties, like position and momentum, cannot simultaneously be known to arbitrary precision. That is, the more precisely one property is measured, the less precisely the other can be measured. In other words, the more you know the position of a particle, the less you can know about its velocity, and the more you know about the velocity of a particle, the less you can know about its instantaneous position.

And the statistics of nonparallel polarizers is all about the QM version of Malus' law: cos^2(a-b)

I don’t get it? Are saying that Einstein had already discovered the "things" Bell did later???

Yes, experiment would fail.

Unless you are saying that every EPR-Bell experiment will fail every time no matter what the "interval" and setup – according to you – this is very strange.

If you are not saying this I can, even as a layman, guarantee you that the QM statistics will be the same regardless if the intervals between the entangled pairs is 100 microseconds, 100 seconds, 100 minutes, 100 days, or 100 months. Expecting anything else is not very bright. It’s like expecting different probabilities from throwing dice with 1 min intervals, or 1 hour intervals...

If you are saying that every EPR-Bell experiment will fail every time no matter what, I can only conclude that this is not the opinion in mainstream science:
Stanford Encyclopedia of Philosophy – Bell's Theorem (http://plato.stanford.edu/entries/bell-theorem/)
...
In the face of the spectacular experimental achievement of Weihs et al. and the anticipated result of the experiment of Fry and Walther there is little that a determined advocate of local realistic theories can say except that, despite the spacelike separation of the analysis-detection events involving particles 1 and 2, the backward light-cones of these two events overlap, and it is conceivable that some controlling factor in the overlap region is responsible for a conspiracy affecting their outcomes. There is so little physical detail in this supposition that a discussion of it is best delayed until a methodological discussion in Section 7.

But let’s put like this, to get by this little "problem", suppose sometime in the future there will be 100% detection efficiency in EPR-Bell experiments.

How would the Ensemble Interpretation handle EPR-Bell experiments with very long intervals between the entangled pairs, where is the "memory" located that handle the QM statistics correct?

Or even worse: If a very advanced civilization in the future decided to setup 1000 individual EPR-Bell experiments, separated by 1 lightyear, and fire one entangled pair at relative angle 22.5º, in the same moment, and then gather the 1000 individual results to check the collective QM statistics (they will of course get cos^2(22.5) = 85%).

The obvious question: How do you handle this scenario in the Ensemble Interpretation??

RUTA

Aug16-10, 08:27 AM

RUTA, I have been thinking (for once :smile:).

If everything that is "screened off" does not exist, I guess that photons emitted in an earlier "process", "traveling" thru vacuum without any interaction, do not exist, right?

But if the photons in the Cosmic Microwave Background (http://en.wikipedia.org/wiki/CMB) (CMB) that have been traveling thru the space since the "last scattering", 400 000 years after the Big Bang, did not exist until they bumped in to one of humans apparatus – How can the CMB be stretched out (redshifted) during billions of years if it DID NOT EXIST...?:bugeye:?

We do have pretty good data of the CMB from COBE. How do you explain this?

Very good question! I understand that Wheeler and Feynman gave up on direct action for cosmological reasons, i.e., the universe is so empty that most photons will never hit anything and therefore will never contribute to the action. I saw a talk on direct action at Imperial College last month where the speaker was trying to resolve this "problem" via horizons. After my talk, that speaker was very interested to know how we handled this problem. He was surprised when I told him we don't have photons, so we don't have to account for "non-interacting entities." The CMB represents relations between "here and now" and "there and then." That's all there is to it.

Now of course, we have to change GR accordingly and that's nontrivial. We're using direct action Regge calculus (which is NOT how it was intended to be used) and that approach is nasty. We're only now working on the 2-body freefall problem. We'll study that solution to obtain a direct action explanation for redshift (which also gives us time difference). Once we have that, we'll do the 2-body orbital problem to see what we have to say about dark matter.

Our nonseparable approach to classical gravity will be empirically distinct from GR. Exactly how it differs is what we're working on now. If it passes existing empirical data, then we'll propose an experiment where it differs. If it passes that test, then perhaps we'll understand why GR thwarted quantization. You realize how unlikely these things are? We have a much better chance of winning the mega lottery :smile:

zonde

Aug16-10, 09:17 AM

Is this really correct?? According to Wikipedia:

And the statistics of nonparallel polarizers is all about the QM version of Malus' law: cos^2(a-b)

I don’t get it? Are saying that Einstein had already discovered the "things" Bell did later???
No, I don't think Einstein had discovered contradictions that Bell discovered. But it might be that he didn't considered anything like naive model of Bell as anything plausible.

Unless you are saying that every EPR-Bell experiment will fail every time no matter what the "interval" and setup – according to you – this is very strange.
No, I am not saying this.

If you are not saying this I can, even as a layman, guarantee you that the QM statistics will be the same regardless if the intervals between the entangled pairs is 100 microseconds, 100 seconds, 100 minutes, 100 days, or 100 months. Expecting anything else is not very bright. It’s like expecting different probabilities from throwing dice with 1 min intervals, or 1 hour intervals...
Dice throwing does not suffer from decoherence where observing QM statistics does.

If you are saying that every EPR-Bell experiment will fail every time no matter what, I can only conclude that this is not the opinion in mainstream science:

But let’s put like this, to get by this little "problem", suppose sometime in the future there will be 100% detection efficiency in EPR-Bell experiments.

How would the Ensemble Interpretation handle EPR-Bell experiments with very long intervals between the entangled pairs, where is the "memory" located that handle the QM statistics correct?

Or even worse: If a very advanced civilization in the future decided to setup 1000 individual EPR-Bell experiments, separated by 1 lightyear, and fire one entangled pair at relative angle 22.5º, in the same moment, and then gather the 1000 individual results to check the collective QM statistics (they will of course get cos^2(22.5) = 85%).

The obvious question: How do you handle this scenario in the Ensemble Interpretation??
You are mixing in 100% detection efficiency but I don't understand what role it plays in you argument. In case of 100% detection efficiency you will observe complete decoherence between H and V modes. So QM statistics will reduce to product state statistics (they are QM statistics as well).

About "global RAM" I explained that there is no such thing so if some of the pairs are not within each other's coherence interval inside common measurement equipment you can not observe entanglement but only QM statistics that describe product state.

DevilsAvocado

Aug16-10, 03:31 PM

You are mixing in 100% detection efficiency but I don't understand what role it plays in you argument. In case of 100% detection efficiency you will observe complete decoherence between H and V modes. So QM statistics will reduce to product state statistics (they are QM statistics as well).

About "global RAM" I explained that there is no such thing so if some of the pairs are not within each other's coherence interval inside common measurement equipment you can not observe entanglement but only QM statistics that describe product state.

Okay, we probably misunderstand each other. Could you in simple English briefly describe how the Ensemble Interpretation explains what happens in an EPR-Bell experiment (let’s pretend it’s 100% perfect to avoid the logjam about loopholes etc)? And what is included in the "Ensemble"?

DevilsAvocado

Aug16-10, 03:42 PM

Very good question!

Thanks RUTA! It’s the first time a Professor of Physics gave me credit! I’m buying champagne for tonight!! :smile:

I understand that Wheeler and Feynman gave up on direct action for cosmological reasons, i.e., the universe is so empty that most photons will never hit anything and therefore will never contribute to the action.

Wow!:eek:! Wheeler and Feynman did struggle with this!? (now I have to buy two bottles :biggrin:) Pardon a layman, but what is "direct action"? Is it a part of the time-symmetric Wheeler–Feynman absorber theory (http://en.wikipedia.org/wiki/Wheeler%E2%80%93Feynman_absorber_theory)?

I saw a talk on direct action at Imperial College last month where the speaker was trying to resolve this "problem" via horizons. After my talk, that speaker was very interested to know how we handled this problem. He was surprised when I told him we don't have photons,

Hehe, kinda understand the speaker :smile: ... "we don't have photons" ... huh?:uhh:?

Now of course, we have to change GR accordingly and that's nontrivial. We're using direct action Regge calculus (which is NOT how it was intended to be used) and that approach is nasty. We're only now working on the 2-body freefall problem. We'll study that solution to obtain a direct action explanation for redshift (which also gives us time difference). Once we have that, we'll do the 2-body orbital problem to see what we have to say about dark matter.

This is very interesting. I can see that you have a lot of work to do. Modifying GR is probably not an easy task. Is this the 2-body freefall problem (http://en.wikipedia.org/wiki/Two-body_problem) you are working on? (Edit: Below is of course the 2-body orbital problem, sorry... :redface:)

http://upload.wikimedia.org/wikipedia/commons/0/0e/Orbit5.gif

then perhaps we'll understand why GR thwarted quantization

Great! Amazing! Exciting! I admire you guys!

You realize how unlikely these things are? We have a much better chance of winning the mega lottery :smile:

Well, people win a lot of money on the lottery every day. It’s just a matter of probability (and bet). :wink:

Loren Booda

Aug16-10, 11:29 PM

Can Planck black holes be shown to violate the Bell inequality?

zonde

Aug17-10, 03:35 AM

Okay, we probably misunderstand each other. Could you in simple English briefly describe how the Ensemble Interpretation explains what happens in an EPR-Bell experiment (let’s pretend it’s 100% perfect to avoid the logjam about loopholes etc)? And what is included in the "Ensemble"?
Well, first about source used in EPR-Bell experiments. Most common source used is Parametric Downconversion Crystal. It produces photon beams that consist of mixture of H/V and V/H photon pairs (or H/H and V/V in case of PDC Type I).

From basic laws about photon polarization we can conclude that if polarizer is perfectly aligned with say H photon polarization axis then all H photons will go through but all V photons will be filtered out.
But if polarizer is at 45° in respect to H photons then half of H photons and half of V photons are going through. So it means that photon polarization does not play any role in determining whether it will go through or will be filtered in 45° case.
However in this 45° case we have some other "thing" that allows us to measure correlations between photons of the same pair.

From perspective of Ensemble Interpretation this "thing" is not property of individual photon but some relation between photons from different pairs. One common example for such a "thing" would be phase. Obviously we can say something about phase of some oscillator only when we compare it with another oscillator that oscillates at the same frequency.
Now to have some measurement of phase we have to combine two photons in single measurement so that they can interfere constructively or destructively and measurement will give "click" in first case and will give no "click" in second case.

However if we get "click" in all cases when we get photon (100% efficiency) there is no way how we can obtain some information about their relative phase. Even more - when detector produces a "click" it's state will be reset to some initial (random) state and interference between two photon arriving one after another can not form.
So while in case of 100% efficiency we can have correlations for polarization measurement at 0° or 90° we can't have correlations for +45° or -45° measurement in this case.

Another way to look at this is that entanglement QM statistics are observable only when we combine polarization measurement with some other measurement of different type. But pure polarization measurement produces only product state statistics (probability at angle "a" x probability at angle "b").

I would like to add to this description that in order to produce correlations with this other measurement after polarizer it has to be that polarization measurements at +45° and -45° change this other "thing" (say phase) in antisymmetric way. Say relative phase between H and V modes changes in opposite ways if we compare +45° and -45° polarization measurements in counterfactual manner.

I hope I described my viewpoint clearly enough.

DevilsAvocado

Aug17-10, 11:21 AM

I hope I described my viewpoint clearly enough.

zonde, I’m only a layman, and I am not saying this to be rude, but with all due respect – I think you may have missed the very core of Bell's Theorem and EPR-Bell experiments.

This is the point I was trying to address earlier:
From perspective of Ensemble Interpretation this "thing" is not property of individual photon but some relation between photons from different pairs.

According to QM; it’s all about probability and statistics. I think that we all can agree that the probability and statistics of throwing dice is not dependent on the context or situation, right? If I throw a dice 1000 times in a row at home, I will get the same statistics as if we gathered 1000 PF user at different global locations throwing a dice once, and then collective check the statistics. Do you agree?

Now, my point is that if we run a "collective" EPR-Bell experiment in the same way as the "1000 PF users", we should of course get the same QM statistics as in one single EPR-Bell experiment. Do you agree?

My crucial conclusion of above is: The Ensemble Interpretation is going to run into some severe difficulties with the "1000 PF users" example, since there is no ensemble present in one single entangled pair, and still we will get the violation of the local realistic inequality when we compare the collective statistics of the 1000 single entangled pairs.

I guess you will not agree with my last conclusion, but I can’t see how you could explain this with the Ensemble Interpretation?

From basic laws about photon polarization we can conclude that if polarizer is perfectly aligned with say H photon polarization axis then all H photons will go through but all V photons will be filtered out.
But if polarizer is at 45° in respect to H photons then half of H photons and half of V photons are going through. So it means that photon polarization does not play any role in determining whether it will go through or will be filtered in 45° case.
However in this 45° case we have some other "thing" that allows us to measure correlations between photons of the same pair.

Here I think you are missing to whole point. When the polarizers are perfectly aligned parallel, even I can write a simple little computer program that proves Local Realism by the means of predefined LHV's. All I have to do is to (randomly) predefine the perfect correlations (1,1) or (0,0). No problem.

And in the case of 45º it’s even simpler. There is no correlation what so ever – it’s always 100% random! You couldn’t prove anything at this angle, could you!:bugeye:?

So while in case of 100% efficiency we can have correlations for polarization measurement at 0° or 90° we can't have correlations for +45° or -45° measurement in this case.

I’m totally confused?? If we skip the 'faultiness' on parallel and perpendicular, are you saying that an EPR-Bell experiment with 100% efficiency cannot produce the statistics we see today!?:eek:!?:bugeye:!?:confused:!?

(If this is what you are saying, it must be the most mind-blowing comment so far in this thread...)

I would like to add to this description that in order to produce correlations with this other measurement after polarizer it has to be that polarization measurements at +45° and -45° change this other "thing" (say phase) in antisymmetric way. Say relative phase between H and V modes changes in opposite ways if we compare +45° and -45° polarization measurements in counterfactual manner.

As I already said, 45º is totally disqualified as a decisive factor due to its 100% randomness. It won’t tell us anything about the Ensemble Interpretation, LHVT or Bell's Theorem.

Let’s instead take one of the simplest proofs of Bell's Inequality, by Nick Herbert:
If both polarizers are set to 0º, we will get perfect agreement, i.e. 100% matches and 0% discordance.
http://i35.tinypic.com/13z71hi.png
To start, we set first polarizer at +30º, and the second polarizer at 0º:
http://i37.tinypic.com/16jlw1g.png
If we calculate the discordance (i.e. the number of mismatching outcome), we get 25% according to QM and experiments.

Now, if we set first polarizer to 0º, and the second polarizer to -30º:
http://i37.tinypic.com/106jwrd.png
This discordance will also naturally be 25%.

Now let’s ask ourselves:

– What will the discordance be if we set the polarizers to +30º and -30º??
http://i33.tinypic.com/2zjm5jk.png
If we assume a local reality, that NOTHING we do to one polarizer can affect the outcome of the other polarizer, we can formulate this simple Bell Inequality:
N(+30°, -30°) ≤ N(+30°, 0°) + N(0°, -30°)

The symbol N represents the number of discordance (or mismatches).

This inequality is as good as any other you’ve seen in this thread.

(The "is less than or equal to" sign ≤ is just to show that there could be compensating changes where a mismatch is converted to a match.)

We can make this simple Bell Inequality even simpler:
50% = 25% + 25%

This is the obvious local realistic assumption.

But this wrong! According to QM and physical experiments we will now get 75% discordance!
sin^2(60º) = 75%

Thus John Bell has demonstrated by the means of very brilliant and simple tools that our natural assumption about a local reality is by over 25% incompatible with the predictions of Quantum Mechanics and physical experiments.

How are you going to explain this with the Ensemble Interpretation? If we run 1000 separate single experiments at (+30°, -30°) to verify the QM prediction of 75% discordance??

THERE IS NO ENSEMBLE!?

RUTA

Aug17-10, 05:06 PM

Wow!:eek:! Wheeler and Feynman did struggle with this!? (now I have to buy two bottles :biggrin:) Pardon a layman, but what is "direct action"? Is it a part of the time-symmetric Wheeler–Feynman absorber theory (http://en.wikipedia.org/wiki/Wheeler%E2%80%93Feynman_absorber_theory)?

"Direct action" means all sources are connected to sinks so there are no "free field" contributions to the Lagrangian. That doesn't mean Wheeler and Feynman thought there were no photons -- I'm not really sure what their motives were for using this approach.

In Relational Blockworld, we have a mathematical rule for the divergence-free graphical co-construction of sources, space and time, that's why we don't have free fields in our action.

Hehe, kinda understand the speaker :smile: ... "we don't have photons" ... huh?:uhh:?

Exactly. It wasn't my idea, but I'm just as crazy for using it as those who proposed it (Bohr, Ulfbeck, Mottelson, Zeilinger) :smile:

In its defense, it's a very powerful means of dismissing lots of conceptual issues in quantum physics (QM and QFT), but it does entail corrections to GR -- you can imagine that "direct connections" are fine in flat spacetime, but in curved spacetime between sources at distances where curvature is significant, this idea won't marry up with GR.

This is very interesting. I can see that you have a lot of work to do. Modifying GR is probably not an easy task. Is this the 2-body freefall problem (http://en.wikipedia.org/wiki/Two-body_problem) you are working on? (Edit: Below is of course the 2-body orbital problem, sorry... :redface:)

http://upload.wikimedia.org/wikipedia/commons/0/0e/Orbit5.gif

Yes, that's the orbital problem we have to solve. I can't begin to tell you how much more complicated the math for Regge calculus is than simply solving Newtonian gravity or even GR numerically. So, we're just trying to do the case where the two bodies free fall directly towards one another first.

Loren Booda

Aug18-10, 12:59 AM

Can one embed in spacetime a geometry which manifests the quantum mechanical observations of all Bell-type experiments therein?

zonde

Aug18-10, 03:50 AM

Now, my point is that if we run a "collective" EPR-Bell experiment in the same way as the "1000 PF users", we should of course get the same QM statistics as in one single EPR-Bell experiment. Do you agree?
Strange but I believe I have states clearly enough this in my previous posts.
No, I disagree!

This discussion is not going anywhere if I will have to state it in every reply to you that I disagree about outcome of "collective" EPR-Bell experiment consisting of individual experiments with single pair.

This is similar to "collective" double slit experiment involving individual experiments with single particle. Even from orthodox QM perspective this question will be quite dubious because you need coherent source of photons to observe interference. But there is no coherence for single photon.

RUTA

Aug18-10, 07:37 AM

Can one embed in spacetime a geometry which manifests the quantum mechanical observations of all Bell-type experiments therein?

Our contention with Relational Blockworld is that a causally local but nonseparable reality solves all the QM "weirdness."

[See “Reconciling Spacetime and the Quantum: Relational Blockworld and the Quantum Liar Paradox,” W.M. Stuckey, Michael Silberstein & Michael Cifone, Foundations of Physics 38, No. 4, 348 – 383 (2008), quant-ph/0510090 (revised December 2007).

“Why Quantum Mechanics Favors Adynamical and Acausal Interpretations such as Relational Blockworld over Backwardly Causal and Time-Symmetric Rivals,” Michael Silberstein, Michael Cifone & W.M. Stuckey, Studies in History & Philosophy of Modern Physics 39, No. 4,
736 – 751 (2008).]

However, this interpretation implies a fundamental theory whereby the current "spacetime + matter" is to be replaced by "spacetimematter," e.g., one consequence of this view is that GR vacuum solutions are only approximations. So, it's incumbent upon us to produce this "theory X" (as Wallace calls it) and that's what we're working on now. To see our current attempt at how this might work, see Figures 1-4 of arXiv 0908.4348.

DevilsAvocado

Aug18-10, 11:25 AM

Strange but I believe I have states clearly enough this in my previous posts.
No, I disagree!

Sorry, my fault. I will not ask about this again. I get your point now.

This discussion is not going anywhere if I will have to state it in every reply to you that I disagree about outcome of "collective" EPR-Bell experiment consisting of individual experiments with single pair.

Yes, we disagree on this, and this is the whole point. Although I'm sure that I can prove to you that your assumption is wrong, thus I will also show that the Ensemble Interpretation is wrong (unless you have missed something in your explanation).

Let me ask you: What is the time-limit (between the pairs) for you to consider a stream of entangled photons an "Ensemble"? Is it 1 nanosecond, 1 microsecond, 1 millisecond, 1 second, or what??

There must clearly be some limit (according to you), since you have stated that coherence is lost for a "single pair", and then the EPR-Bell experiment will fail.

So, what's the difference in time between two "single pairs" and two "coherent pairs" in an "Ensemble"??

This is similar to "collective" double slit experiment involving individual experiments with single particle. Even from orthodox QM perspective this question will be quite dubious because you need coherent source of photons to observe interference. But there is no coherence for single photon.

And here is where you got it all wrong. Your view is the old classical view on interference, where the effect originates from several photons interfering with each other. But this is proven wrong. The interference originates from one wavefunction of one photon interfering with itself! As the Nobel Laureate Paul Dirac (http://en.wikipedia.org/wiki/Paul_Dirac) states:

Wikipedia – Probability for a single photon – Paul Dirac (http://en.wikipedia.org/wiki/Photon_dynamics_in_the_double-slit_experiment#Probability_for_a_single_photon)
...
Some time before the discovery of quantum mechanics people realized that the connexion between light waves and photons must be of a statistical character. What they did not clearly realize, however, was that the wave function gives information about the probability of one photon being in a particular place and not the probable number of photons in that place. The importance of the distinction can be made clear in the following way. Suppose we have a beam of light consisting of a large number of photons split up into two components of equal intensity. On the assumption that the beam is connected with the probable number of photons in it, we should have half the total number going into each component. If the two components are now made to interfere, we should require a photon in one component to be able to interfere with one in the other. Sometimes these two photons would have to annihilate one another and other times they would have to produce four photons. This would contradict the conservation of energy. The new theory, which connects the wave function with probabilities for one photon gets over the difficulty by making each photon go partly into each of the two components. Each photon then interferes only with itself. Interference between two different photons never occurs.

— Paul Dirac, The Principles of Quantum Mechanics, Fourth Edition, Chapter 1

I guess your last hope is to say that Paul Dirac was wrong and that you are right, but then you run into next problem - physical proofs. This video by Akira Tonomura at Hitachi Ltd shows a double slit experiment involving individual electrons distributed as an interference pattern:

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</object>

As you can see, you are obviously wrong, and we could of course extend the time between every electron to 1 second, or 1 minute, or 1 hour, or 1 day, or 1 month, and still get exactly the same result as above!

This double slit experiment could of course also be distributed at different geographic locations, and when we later assemble the individual results, we would of course get the same collective picture as above. It's exactly the same mechanism as throwing dice - probability.

Even if you disagree, you can’t deny physical proofs can you...

DevilsAvocado

Aug18-10, 02:43 PM

"Direct action" means all sources are connected to sinks so there are no "free field" contributions to the Lagrangian. That doesn't mean Wheeler and Feynman thought there were no photons -- I'm not really sure what their motives were for using this approach.

In Relational Blockworld, we have a mathematical rule for the divergence-free graphical co-construction of sources, space and time, that's why we don't have free fields in our action.

This is really hard for me... I can only guess my way thru "the haze of complexity"... I guess what you are saying is that if we have no photons, then naturally also the force carrier of one of the four fundamental interactions, electromagnetism, also has to go, and this must in some (very strange to me) way be replaced by a "Direct action", right?? (And that also goes for the rest of the 3 fundamental interactions? :uhh:)

Very weird indeed, every part in physics should be affected by this... (if I’m correct)

Exactly. It wasn't my idea, but I'm just as crazy for using it as those who proposed it (Bohr, Ulfbeck, Mottelson, Zeilinger) :smile:

In its defense, it's a very powerful means of dismissing lots of conceptual issues in quantum physics (QM and QFT), but it does entail corrections to GR -- you can imagine that "direct connections" are fine in flat spacetime, but in curved spacetime between sources at distances where curvature is significant, this idea won't marry up with GR.

Ohh yeah, "crazy" is the term... :smile:

Yes, that's the orbital problem we have to solve. I can't begin to tell you how much more complicated the math for Regge calculus is than simply solving Newtonian gravity or even GR numerically. So, we're just trying to do the case where the two bodies free fall directly towards one another first.

I have serious trouble just understanding the metric on Minkowski space... so this is actually very easy for me to relate to... :redface:

Seriously, can one look on RBW as a "digitalization", or maybe "sampling", or just "quantization" of everything in nature (I’m thinking of the "blocks")? Just as digital music on a CD, or sounds on a sampler, is just small blocks of an original analog continuing signal, or is this totally wrong (and silly)...?:uhh:?

If I’m correct, will this (hopefully) be the "key" to the quantization of gravity (which is maybe the most "analog" and "continuing", in distance, we have).

Just some personal thoughts... or whatever... :rolleyes:

DevilsAvocado

Aug18-10, 02:56 PM

Can Planck black holes be shown to violate the Bell inequality?

I don’t know anything about Micro black holes, but you must have Quantum entanglement in some way to violate a Bell inequality.

...thinking more about it... this could maybe be a really cool way of "stealing" information from a Black hole by sending in one part of an entangle pair...?? :cool:

nismaratwork

Aug18-10, 07:04 PM

I don’t know anything about Micro black holes, but you must have Quantum entanglement in some way to violate a Bell inequality.

...thinking more about it... this could maybe be a really cool way of "stealing" information from a Black hole by sending in one part of an entangle pair...?? :cool:

I don't know what it is you'd entangle, and anyway, the information can't leave the event horizon. Even if they are String Theory Fuzzballs, the event horizon is still "no return"... the ultimate in decoherence.

zonde

Aug19-10, 09:45 AM

Yes, we disagree on this, and this is the whole point. Although I'm sure that I can prove to you that your assumption is wrong, thus I will also show that the Ensemble Interpretation is wrong (unless you have missed something in your explanation).
How do you intend to do that without actual experimental results?

Let me ask you: What is the time-limit (between the pairs) for you to consider a stream of entangled photons an "Ensemble"? Is it 1 nanosecond, 1 microsecond, 1 millisecond, 1 second, or what??

There must clearly be some limit (according to you), since you have stated that coherence is lost for a "single pair", and then the EPR-Bell experiment will fail.

So, what's the difference in time between two "single pairs" and two "coherent pairs" in an "Ensemble"??
You question is quite reasonable but I have to admit that I don't have clear answers.
I tried to look at this using different experiments that involve observation of HOM (Hong-Ou_Mandel) dip and I have to say that "coherent pairs" should be those that use this "memory" the same way i.e. results are correlated not just random. But allowed time offset before coherence is lost is very small - in the scale of picoseconds.
But the time limit for preservation of "memory" content should be much bigger.

And here is where you got it all wrong. Your view is the old classical view on interference, where the effect originates from several photons interfering with each other. But this is proven wrong. The interference originates from one wavefunction of one photon interfering with itself! As the Nobel Laureate Paul Dirac (http://en.wikipedia.org/wiki/Paul_Dirac) states:

But look at your quote. Dirac says: "The new theory, which connects the wave function with probabilities for one photon gets over the difficulty by making each photon go partly into each of the two components. Each photon then interferes only with itself. Interference between two different photons never occurs."
But he doesn't tell what is result physically for constructive and destructive interference.
What happens when photon interferes with itself destructively? Does it disappears or jumps to another place or what?
What happens when photon interferes with itself constructively? Does it just stays the way it is or what?
He is just going away from physical context of question to avoid the need for giving answer in physical sense.

This matter is not so simple. Take a look for example at this Feynman quote: (there was discussion about this quote here (http://www.physicsforums.com/showthread.php?t=406161))
"It is to be emphasized that no matter how many amplitudes we draw, add, or multiply, our objective is to calculate a single final amplitude for the event. Mistakes are often made by physics students at first because they do not keep this important point in mind. They work for so long analyzing events involving a single photon that they begin to think that the wavefunction or amplitude is somehow associated with the photon. But these amplitudes are probability amplitudes, that give, when squared, the probability of a complete event. Keeping this principle in mind should help the student avoid being confused by things such as the "collapse of the wavefunction" and similar magic."

Why interpretations of QM can not do away with single bare photon in single world?
Why do we need superposition or pilot-wave or many worlds?
If I would have to give one single word for what is common in all these interpretations I will say that it's context of measurement.

nismaratwork

Aug19-10, 10:07 AM

How do you intend to do that without actual experimental results?

You question is quite reasonable but I have to admit that I don't have clear answers.
I tried to look at this using different experiments that involve observation of HOM (Hong-Ou_Mandel) dip and I have to say that "coherent pairs" should be those that use this "memory" the same way i.e. results are correlated not just random. But allowed time offset before coherence is lost is very small - in the scale of picoseconds.
But the time limit for preservation of "memory" content should be much bigger.

But look at your quote. Dirac says: "The new theory, which connects the wave function with probabilities for one photon gets over the difficulty by making each photon go partly into each of the two components. Each photon then interferes only with itself. Interference between two different photons never occurs."
But he doesn't tell what is result physically for constructive and destructive interference.
What happens when photon interferes with itself destructively? Does it disappears or jumps to another place or what?
What happens when photon interferes with itself constructively? Does it just stays the way it is or what?
He is just going away from physical context of question to avoid the need for giving answer in physical sense.

This matter is not so simple. Take a look for example at this Feynman quote: (there was discussion about this quote here (http://www.physicsforums.com/showthread.php?t=406161))
"It is to be emphasized that no matter how many amplitudes we draw, add, or multiply, our objective is to calculate a single final amplitude for the event. Mistakes are often made by physics students at first because they do not keep this important point in mind. They work for so long analyzing events involving a single photon that they begin to think that the wavefunction or amplitude is somehow associated with the photon. But these amplitudes are probability amplitudes, that give, when squared, the probability of a complete event. Keeping this principle in mind should help the student avoid being confused by things such as the "collapse of the wavefunction" and similar magic."

Why interpretations of QM can not do away with single bare photon in single world?
Why do we need superposition or pilot-wave or many worlds?
If I would have to give one single word for what is common in all these interpretations I will say that it's context of measurement.

Ignoring context and Interpretations of QM, I don't see how you can see anything like locality or realism with the violations of BI's. As for how a photon interferes with itself destructively, I would guess it would be a net loss of energy, but who knows. Does it matter? That doesn't really effect non-locality in the context of Bell. The bottom line is that the results of these experiments are incompatible with ANY LHV theory, and the only other local theory on offer is deBB, which personally I don't buy (although it's viable for now).

RUTA

Aug19-10, 10:22 AM

This is really hard for me... I can only guess my way thru "the haze of complexity"... I guess what you are saying is that if we have no photons, then naturally also the force carrier of one of the four fundamental interactions, electromagnetism, also has to go, and this must in some (very strange to me) way be replaced by a "Direct action", right?? (And that also goes for the rest of the 3 fundamental interactions? :uhh:)

Yes, at the fundamental level there are no "forces." The notion of "force" has to do the deviation of a worldline (matter) from geodesy in a background spacetime. In our approach, spacetime and matter are fused into spacetimematter, and the WHOLE thing is co-constructed. It's like GR where you can view the ontology as free of gravitational force. The difference is that in GR you can have vacuum solutions, i.e., it's meaningful to talk about empty spacetime. In our approach, spatio-temporal distances are defined only between sources, so there is no vacuum solution. This solves problems with closed time-like curves in GR, btw.

I have serious trouble just understanding the metric on Minkowski space... so this is actually very easy for me to relate to... :redface:

Seriously, can one look on RBW as a "digitalization", or maybe "sampling", or just "quantization" of everything in nature (I’m thinking of the "blocks")? Just as digital music on a CD, or sounds on a sampler, is just small blocks of an original analog continuing signal, or is this totally wrong (and silly)...?:uhh:?

If I’m correct, will this (hopefully) be the "key" to the quantization of gravity (which is maybe the most "analog" and "continuing", in distance, we have).

Quantization of "everything" is probably the best metaphor. We use our fundamental rule to yield a partition function over the spacetimematter graph (local and nonseparable). The probability for any particular quantum outcome (graphical relation evidenced by a single detector click) can be obtained per the partition function. Thus, sets of many relations center statistically around the most probable outcome and one obtains classical physics. So, we don't start with classical physics (local and separable) and "quantize it." We start with a quantum physics (local and nonseparable) and obtain classical physics in the statistical limit.

DevilsAvocado

Aug19-10, 07:06 PM

How do you intend to do that without actual experimental results?

Nema problema! :wink:

You question is quite reasonable but I have to admit that I don't have clear answers.
I tried to look at this using different experiments that involve observation of HOM (Hong-Ou_Mandel) dip and I have to say that "coherent pairs" should be those that use this "memory" the same way i.e. results are correlated not just random. But allowed time offset before coherence is lost is very small - in the scale of picoseconds.
But the time limit for preservation of "memory" content should be much bigger.

And I have to admit that your answer is somewhat unclear...

Immediately you run into several difficulties. To start with, spontaneous parametric down-conversion in BBO crystals is due to random vacuum fluctuations, and it’s not a very effective process. One out of 106 photons converts into two entangled photons, one in a million.

Then you have coincidence counting, and time window, and delays occurring in the electronics and optics, in the experimental setup.

All this results in roughly 1.5 entangled pair per millisecond:
Violation of Bell's inequality under strict Einstein locality conditions (http://arxiv.org/abs/quant-ph/9810080)
Weihs, Jennenwein, Simon, Weinfurter, and Zeilinger

...
The total of the delays occurring in the electronics and optics of our random number generator, sampling circuit, amplifier, electro-optic modulator and avalanche photodiodes was measured to be 75 ns.
...
A typical observed value of the function S in such a measurement was S = 2.73±0.02 for 14700 coincidence events collected in 10 s. This corresponds to a violation of the CHSH inequality of 30 standard deviations assuming only statistical errors.

There goes your "correlated" picoseconds.

And I am extremely interested in your "memory". What is this? How does it work? To me it looks at least as spooky as non-locality... This physical "entity" must have enormous "computing power" – keeping track of every microscopic probability in the whole universe... and not only on every present probability, "it" must remember all it "did" in the past to produce the correct correlated data... in real-time without delays... How on earth is this ever possible??

Another interesting problem: If Alice & Bob are separated by 20 km and big a stream of not entangled photons, mixed with a few entangled photons, are running towards their random polarizers and measuring apparatus, to be time tagged – how can your "memory" know if one specific photon is entangled or not???? This is something that is established later when data from both Alice & Bob is compared.

For your "memory" to know this at the exact measuring moment – "it" would need TRUE FTL communication!?:bugeye:!?

Let’s admit, this doesn’t work, does it????

But he doesn't tell what is result physically for constructive and destructive interference.
What happens when photon interferes with itself destructively? Does it disappears or jumps to another place or what?
What happens when photon interferes with itself constructively? Does it just stays the way it is or what?
He is just going away from physical context of question to avoid the need for giving answer in physical sense.

This is so easy that even I can give you a correct answer: What happen is that the single wavefunction for one photon goes thru both slits, just as a single water wave, and after the slits starts creating an interference pattern, just as a single water wave. When the wavefunction reaches the detector there are destructive and constructive amplitudes of probability for the photon to be detected. Naturally, more single photons will be detected in those areas where there are constructive amplitudes of probability (= higher probability).

It’s very simple.

http://upload.wikimedia.org/wikipedia/commons/2/2c/Two_sources_interference.gif

nismaratwork

Aug19-10, 08:06 PM

Nema problema! :wink:

And I have to admit that your answer is somewhat unclear...

Immediately you run into several difficulties. To start with, spontaneous parametric down-conversion in BBO crystals is due to random vacuum fluctuations, and it’s not a very effective process. One out of 106 photons converts into two entangled photons, one in a million.

Then you have coincidence counting, and time window, and delays occurring in the electronics and optics, in the experimental setup.

All this results in roughly 1.5 entangled pair per millisecond:

There goes your "correlated" picoseconds.

And I am extremely interested in your "memory". What is this? How does it work? To me it looks at least as spooky as non-locality... This physical "entity" must have enormous "computing power" – keeping track of every microscopic probability in the whole universe... and not only on every present probability, "it" must remember all it "did" in the past to produce the correct correlated data... in real-time without delays... How on earth is this ever possible??

Another interesting problem: If Alice & Bob are separated by 20 km and big a stream of not entangled photons, mixed with a few entangled photons, are running towards their random polarizers and measuring apparatus, to be time tagged – how can your "memory" know if one specific photon is entangled or not???? This is something that is established later when data from both Alice & Bob is compared.

For your "memory" to know this at the exact measuring moment – "it" would need TRUE FTL communication!?:bugeye:!?

Let’s admit, this doesn’t work, does it????

This is so easy that even I can give you a correct answer: What happen is that the single wavefunction for one photon goes thru both slits, just as a single water wave, and after the slits starts creating an interference pattern, just as a single water wave. When the wavefunction reaches the detector there are destructive and constructive amplitudes of probability for the photon to be detected. Naturally, more single photons will be detected in those areas where there are constructive amplitudes of probability (= higher probability).

It’s very simple.

http://upload.wikimedia.org/wikipedia/commons/2/2c/Two_sources_interference.gif

Postoji problem. Mislim da je problem, Zonde's approach and endlessly reductionist requirements. Nearly 90 pages and a couple people (not naming names) seems to be chasing their tails. Your .gif picture is very eloquent, and really doesn't it say it all?! What more is needed, a frying pan inset with "No LHV!!" to beat some about the head? This fair sampling complaint, then offshoots (by another) to endless talk of Malus' Law, then back to demands for evidence that is self-evident, or on the other hand impossible (FTL verification without classical means). I'm ready to believe this is all going to end with Abbot & Costello asking "Who's on first?"

ThomasT

Aug20-10, 02:56 AM

Thanks for the informative replies RUTA. Some comments below:

1. I've begun a second, much slower, reading of your main RBW paper, arXiv 0908.4348. I have the feeling that it might turn out to be somewhat influential. Who knows. In any case, as I mentioned, insofar as I understand the rationale of your approach it does seem quite reasonable, even if certain (necessary?) formal aspects of it are somewhat alien to my, admittedly pedestrian, way of thinking. Hopefully, I'll be able to ask you some worthwhile questions about it in the future -- definitely in a different thread, and probably in a different subforum.

2. Wrt the OP of this thread, I was asking if you assume (not just wrt RBW, but in your general thinking as a theoretical physicist and natural philosopher) the observation-independent existence of an 'underlying reality'. I mean, do you think that this a reasonable inference from observations, or isn't it?

Wrt the OP, "action at a distance ... as envisaged by the EPR Paradox" entails that there's no underlying reality.

Keeping in mind that there's a difference between saying that there's no way of talking, objectively, about an underlying reality (or any subset thereof such as, say, a light medium), and that an underlying reality doesn't exist, then what would you advise readers like me to believe -- that no underlying reality exists independent of observation, or that it's reasonable to assume that an underlying reality independent of observation exists but there's just no way to objectively talk about it?

If it's assumed that no observation-independent underlying reality exists, then the answer to the OP's question is that "action at a distance ... as envisaged by the EPR Paradox" isn't just possible, it's all there is. Alternatively, if it's assumed that an observation-independent underlying reality exists (even if we have no way of objectively talking about it), then the answer to the OP's question is no, "action at a distance ... as envisaged by the EPR Paradox" isn't possible.

In the course of answering the OP's question, it's been suggested that violations of BIs (and GHZ inconsistencies, etc.) inform us that either an observation-independent underlying reality doesn't exist, or, if it exists, then it's nonlocal in the EPR sense. But nonlocality, "as envisiged by the EPR Paradox", entails that an observation-independent reality doesn't exist. So, the suggestion becomes, violations of BIs show that there is no reality underlying instrumental behavior. This would seem to render any and all 'interpretations' of the qm formalism as simply insipid exercises in the manipulation of agile terms.

Of course, there's another, more reasonable way to interpret BI violations -- that they're not telling us anything about the nature of reality, but rather that they have to do with how certain experimental situations might be formalised. In which case, the answer, in my view, to the OP's question is simply that there is, currently, no definitive answer to his question -- but that the most reasonable assumptions, based on what is known, entail that, no, it's not possible.

ThomasT

Aug20-10, 03:08 AM

Thanks for the thoughtful reply DA. I'm not sure I totally agree with (or maybe I don't fully understand) some of your points. Comments below:

I agree; we all want the world to be logical and understandable. No one wants it to be horrible, incomprehensible or 'magical'. We want to know that it all works the way we 'perceive' it. We also want nature to be 'homogeneous' on all scales. It’s very logical and natural, and I agree.Not strictly "'homogeneous' on all scales", keeping in mind that there do seem to be certain 'emergent' organizing principles that pertain to some physical 'regimes' and not others, but rather that there might be some fundamental, or maybe a single fundamental, dynamical principle(s) that pervade(s) all scales of behavior.

But I think it could be a mistake... or at least lead to mistakes.Sure, it could. But maybe not. Modern particle physics has proceeded according to a reductionist program -- in the sense of 'explaining' the macroscopic world in terms of properties and principles governing the microscopic and submicroscopic world. But there's another approach (also a sort of reductionism) that aims at abstracting dynamical principles that are relevant at all scales of behavior -- perhaps even reducing to one basic fundamental wave dynamic.

A classical mistake is when one of the brightest minds in history, Albert Einstein, did not like what his own field equations for theory of general relativity revealed – the universe cannot be static.

Albert Einstein was very dissatisfied, and made a modification of his original theory and included the cosmological constant (lambda: ?) to make the universe static. Einstein abandoned the concept after the observation of the Hubble Redshift, and called it the '"biggest blunder" of his life.

(However, the discovery of cosmic acceleration in the 1990s has renewed interest in a cosmological constant, but today we all know that the universe is expanding, even if that was not Albert Einstein’s logical hypothesis.)Einstein made a logical judgement, given what was known at the time, and then changed his mind given observational evidence of the expansion. It's quite possible that the mainstream paradigms of both fundamental physics and cosmology might change significantly in the next, say, 100 to 200 years.

Another classical example is Isaac Newton, who found his own law of gravity and the notion of "action at a distance" deeply uncomfortable, so uncomfortable that he made a strong reservation in 1692.Newton formulated some general mathematical relationships which accorded with observations. His reservation wrt to his gravitational law was that he wasn't going to speculate regarding the underlying reason(s) for its apparent truth. Then, a couple of centuries after Newton, Einstein presented a more sophisticated (in terms of its predictive accuracy) and more explanatory (in terms of its geometric representation) model. And, I think we can assume that GR is a mathematical/geometrical simplification of the fundamental physical reality determining gravitational behavior. Just as the Standard Model is a simplification, and qm is a simplification.

We must learn from this.I agree. And the main thing we learn from is observation. Relatively recent and fascinating cosmological observations have led to inferences regarding the nature of 'dark energy' and 'dark matter'. But, in keeping with the theme of your reply to my reply to nismaratwork, these apparent phenomena don't necessarily entail the existence of anything wholly unfamiliar to our sensory reality. Dark energy might be, fundamentally, the kinetic energy of the universal expansion. The apparent acceleration of the expansion might just be a blip in the overall trend. It might be taken as evidence that gravity isn't the dominant force in our universe. I'm not familiar with the current mainstream views on this.

Our universe appears to be evolving. Why not just assume that it 'is' evolving -- that 'change' or 'time' isn't just an illusion, but is real? Why not assume that the fundamental physical principles govern physical behavior at all scales? If there's a fundamental physical principle, say, in the form of a fundamental wave dynamic, and if it makes sense to assume that it's present at all scales, then conceptualizing the boundary of our universe in terms of an expanding spherical (ideally) shell, the mother of all waveforms, so to speak, then the discovery of the cosmic-scale expansion becomes maybe the single most important scientific discovery in history.

And dark matter might be waves in a medium or media of unknown structure. Is there any particular reason to assume that wave behavior in media that we can't see is 'fundamentally' different from wave behavior in media that we can see? It might be argued that standard qm is based on the notion that the wave mechanics of unknown media is essentially the same as the wave mechanics of known media.

I think that humans have a big "ontological weakness" – we think that the human mind is "default" and the "scientific center" of everything in the universe, and there are even some who are convinced that their own brain is greatest of all . But there is no evidence at all that this is the case (please note: I’m not talking about "God").I certainly agree that this seems to be the general orientation. Whereas, the more scientifically sophisticated worldview would seem to be that what our sensory faculties reveal to us is not the fundamental 'reality'. Perhaps we're just complex, bounded waveforms, persisting for a virtual instant as far as the life of the universe as a whole is concerned -- or however one might want to talk about it.

One extremely simple example is "human colors". Do they exist? The answer is No. Colors only exist inside our heads. In the "real world" there is only electromagnetic radiation of different frequency and wavelength. A scientist trying to visualize "logical colors" in nature will not go far.Well, colors do exist. But, as you've noted, it's really important to specify the context within which they can be said to exist. We humans, and moons and cars and computers, exist, but these forms that are a function of our sensory faculties aren't the fundamental form of reality.

And the way that all of our sensory faculties seem to function (vibrationally) gives us another clue (along with quantum phenomena, and the apparent behavior of dark matter, etc.) wrt the fundamental nature of reality. It's wavelike. Particles and particulate media emerge from complex wave interactions. Now, wrt my statement(s), is there any reason to suppose that wave behavior in particulate media is governed by different fundamental dynamical principles than wave behavior in nonparticulate media? Of course, I have no idea.

Have you ever tried to visualize a four-dimensional space-time?I don't want to. I think that it's a simplification of underlying complex wave behavior.

Or visualize the bending and curving of that 4D space-time??No. But consider the possibility that 'gravitational lensing' is further evidence in favor of a wave interpretation of fundamental reality. (And keep in mind that insofar as we entertain the idea of a fundamental reality that exists whether we happen to be probing it or not, then we can't logically entertain the possibility of EPR-envisaged spooky action at a distance per the OP.)

To my understanding, not even the brightest minds can do this?? Yes, it works perfectly in the mathematical equations, but to imagine an "ontological description" that fits "our experience"... is this even possible??Sure, there's wave activity in a medium or media that we can't detect that's affecting the light.

Yet, we know it’s there, and we can take pictures of it in the form of gravitational lensing on the large cosmological scale:
Does this fits your picture of a "logical reality"...?Yes.

I don’t think mainstream science claims the full understanding of EPR-Bell experiments, it’s still a paradox. What is a fact though is that either locality and/or realism have to go if QM is correct (and QM is the most precise theory we got so far): Bell's Theorem proves that QM violates Local Realism.I agree that objective realism is a pipe dream. There's simply no way to know, definitively, what the underlying reality is or, definitively, how it behaves. It is, nonetheless, a wonderful speculative enterprise. And I do think that informed speculations about the nature of reality will help fundamental physics advance.

But if we opt for nonlocality, per EPR and the OP, then there is no underlying reality -- and I find that a very limiting and boring option.

There seems to be some in this thread that for real thinks that Einstein would have stuck to his original interpretation of the EPR paradox, despite the work of John Bell and the many experimentalists who are verifying QM predictions and Bell's Theorem, time after time. I’m pretty sure that this would not have been the case. Just look at the cosmological constant and Hubble Redshift. Einstein changed his mind immediately. He did not start looking for "loopholes" in Hubble's telescope or any other farfetched 'escape' – he was a diehard empiricist.Bell experiments are one thing. Interpretations of Bell experiments are quite another. Do they inform us about the nature of reality? How, especially when one interpretation is that BI violations tell us that an underlying reality doesn't even exist? And if that's the case, then what is there to 'discover'?

The acceptance that the cosmological expansion is real is much less problematic than the acceptance that there's no reality underlying instrumental behavior.

I don't know what the mainstream view is, but, if it's that qm and experiments are incompatible with the predictions of LR models of a certain form specified by Bell, then I currently agree with that. And the experiments tell us nothing about any necessary qualitative features of the reality underlying the instrumental behavior, except maybe that the correlation between detector behavior and emitter behavior would seem to support the assumption that there's something moving from emitter to detector, which would seem to support the assumption that there's an underlying real 'whatever', produced by the emission process, which exists prior to and independent of filtration and detection, which would support the contention that the correct answer to the OP's question is, no, "action at a distance ... as envisaged by the EPR Paradox" is not possible.

We already know that there are problems in getting full compatibility between QM and GR when it comes to gravity in extreme situations, and EPR-Bell is just another verification of this incompatibility. If we try to solve the EPR-Bell situation as a "spookyactionatadistanceist" we get problems with SR and Relativity of Simultaneity (RoS) + problems with QM and the No-communication theorem. If we try to solve it as a "surrealist" (non-separable/non-realism) we get the problems RUTA is struggling with.

So this question is definitely NOT solved, and it’s definitely NOT easy.

But, let’s not make it too easy by saying the problem doesn’t exist at all, because there’s still QM-incompatible gravity dragging us down, and it will never go away... I agree. And the QM-GR, RBW-GR formal problems are beyond my comprehension. However, this thread is (ok, it sort of was at one time) about answering the question, "Is action at a distance possible as envisaged by EPR?". And here's my not quite definitive answer to that:

If there's no underlying reality, then it's possible.
Experiments suggest that there's an underlying reality.
Therefore, it's not possible.

Or, in the words of Captain Beefheart:

The stars are matter,
We are matter,
But it doesn't matter.

zonde

Aug20-10, 03:15 AM

This is so easy that even I can give you a correct answer: What happen is that the single wavefunction for one photon goes thru both slits, just as a single water wave, and after the slits starts creating an interference pattern, just as a single water wave.

***
When the wavefunction reaches the detector there are destructive and constructive amplitudes of probability for the photon to be detected.
***

Naturally, more single photons will be detected in those areas where there are constructive amplitudes of probability (= higher probability).

It’s very simple.
Incredible!!!
You have got it!

So if we hypothetically detect all photons even those with miserable detection probability we loose any idea about interference pattern.
That's what I call unfair sampling but you can call it whatever way you want.

Forget about ensemble interpretation. I can explain it to you using orthodox QM in much simpler way.

Just to check that we are on the same line. Consider Mach–Zehnder interferometer (http://en.wikipedia.org/wiki/Mach-Zehnder_interferometer).

http://upload.wikimedia.org/wikipedia/commons/2/2d/Mach-zender-interferometer.png

After we count all the phase shifts inside different mirrors Wikipedia says that: "there is no phase difference in the two beams in detector 1, yielding constructive interference." So detector 1 fires when photon arrives there (constructive interference) but detector 2 does not fire when photon arrives there (destructive interference).
So photons arrive at both detectors but because of interference one detector fires but the other don't.

Are we still on the same line here?

RUTA

Aug20-10, 07:52 AM

Consider Mach–Zehnder interferometer (http://en.wikipedia.org/wiki/Mach-Zehnder_interferometer).

http://upload.wikimedia.org/wikipedia/commons/2/2d/Mach-zender-interferometer.png

After we count all the phase shifts inside different mirrors Wikipedia says that: "there is no phase difference in the two beams in detector 1, yielding constructive interference." So detector 1 fires when photon arrives there (constructive interference) but detector 2 does not fire when photon arrives there (destructive interference).

So photons arrive at both detectors but because of interference one detector fires but the other don't.

Most people would say that no photons arrive at detector 2.

nismaratwork

Aug20-10, 08:22 AM

Most people would say that no photons arrive at detector 2.

After finally reading this entire thread, I feel confident saying that Zonde is not most people... :rolleyes:

DevilsAvocado

Aug20-10, 09:12 AM

So if we hypothetically detect all photons even those with miserable detection probability we loose any idea about interference pattern.
That's what I call unfair sampling but you can call it whatever way you want.
...
Are we still on the same line here?

I’m afraid we don’t even agree on "what’s a line"... as I said, it’s extremely simple. If we block one of the slits, we will not get the interference pattern, with or without "unfair sampling". This is an undeniable fact that should make sense even to a 10-yearold.

The physical proofs are right in front of you nose, where you step by step can see with your own eyes what happens when the "sampling increases":

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zonde

Aug20-10, 09:33 AM

Most people would say that no photons arrive at detector 2.
What most people will say about this Feynman quote?
"It is to be emphasized that no matter how many amplitudes we draw, add, or multiply, our objective is to calculate a single final amplitude for the event. Mistakes are often made by physics students at first because they do not keep this important point in mind. They work for so long analyzing events involving a single photon that they begin to think that the wavefunction or amplitude is somehow associated with the photon. But these amplitudes are probability amplitudes, that give, when squared, the probability of a complete event. Keeping this principle in mind should help the student avoid being confused by things such as the "collapse of the wavefunction" and similar magic."

Most people will make smart face but will think by themselves: "What the heck he is talking about? Why I should avoid magic? I love magic! It gives colors to world. It makes me feel special after all. If it's not magic I don't want to understand it at all."

Well first of all to solve the problem it should be recognized as a problem. If there is no problem there is nothing to solve. :biggrin:

DevilsAvocado

Aug20-10, 09:34 AM

Yes, at the fundamental level there are no "forces." The notion of "force" has to do the deviation of a worldline (matter) from geodesy in a background spacetime. In our approach, spacetime and matter are fused into spacetimematter, and the WHOLE thing is co-constructed.

This is interesting. Do you need to "redefine" any existent physical laws to make it all work...?

Quantization of "everything" is probably the best metaphor.
... We start with a quantum physics (local and nonseparable) and obtain classical physics in the statistical limit.

This is very cool. You start with quantized blocks of everything, and then plug it into the "classical player", and out comes wonderful "analog" classical "music"! :cool:

If this works, I know one guy Nick Bostrom (http://en.wikipedia.org/wiki/Nick_Bostrom), who’s going to jump up and down! This will fit his Simulation hypothesis (http://en.wikipedia.org/wiki/Simulation_hypothesis) perfectly – it’s all small "digital" blocks of information! :smile:

unusualname

Aug20-10, 09:48 AM

gee, is this thread never going to end?

The answer is that spacetime is patchwork of manifolds mapping the underlying quantum Hilbert space via a holographic mechanism.

http://arxiv.org/abs/0907.2939

Lubos Motl explains it all here (http://motls.blogspot.com/2009/07/mark-van-raamsdonk-entanglement-glue.html)

Admittedly the details of the mechanism which gives rise to these emergent spacetime "patches" hasn't been fully worked out but it's only a matter of time...

So you can all stop arguing now. :wink: :biggrin:

DevilsAvocado

Aug20-10, 10:04 AM

However, this thread is (ok, it sort of was at one time) about answering the question, "Is action at a distance possible as envisaged by EPR?". And here's my not quite definitive answer to that:

If there's no underlying reality, then it's possible.
Experiments suggest that there's an underlying reality.
Therefore, it's not possible.

Or, in the words of Captain Beefheart:

The stars are matter,
We are matter,
But it doesn't matter.

Not that it matter that much :smile:, but we could make it simple and say...

If QM is correct, then we are left with these options:

locality + non-realism

non-locality + realism

non-locality + non-realism

"When it is obvious that the goals cannot be reached, don't adjust the goals, adjust the action steps." -- Confucius :wink:

DevilsAvocado

Aug20-10, 10:07 AM

gee, is this thread never going to end?

NO!! WHY!?!? :grumpy:

(:rofl: :rofl: :rofl:)

DevilsAvocado

Aug20-10, 10:31 AM

Postoji problem. Mislim da je problem

Nastrovje! :smile:

What more is needed, a frying pan inset with "No LHV!!" to beat some about the head?

This is probably the most accurate solution this far! :biggrin:

I'm ready to believe this is all going to end with Abbot & Costello asking "Who's on first?"

HAHA! LOL!! Let’s try it and see what happens!!! :rofl:

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RUTA

Aug20-10, 12:13 PM

This is interesting. Do you need to "redefine" any existent physical laws to make it all work...?

The only change to existing physics would be to understand GR as a separable approximation to spacetimematter.

This is very cool. You start with quantized blocks of everything, and then plug it into the "classical player", and out comes wonderful "analog" classical "music"! :cool:

If this works, I know one guy Nick Bostrom (http://en.wikipedia.org/wiki/Nick_Bostrom), who’s going to jump up and down! This will fit his Simulation hypothesis (http://en.wikipedia.org/wiki/Simulation_hypothesis) perfectly – it’s all small "digital" blocks of information! :smile:

I don't know if our idea is in concert with his. Ok, that was bad :smile:

DevilsAvocado

Aug20-10, 03:10 PM

I don't know if our idea is in concert with his. Ok, that was bad :smile:

Not bad, not bad at all, if you do not know what you are talking about (= me :smile:), the best you can do is try "Acting" in concert ... but most of the time the damned violin is broken (= terrible noise + bleeding fingers :biggrin:) ...

charlylebeaugosse

Aug21-10, 12:23 PM

Incredible!!!
You have got it!

So if we hypothetically detect all photons even those with miserable detection probability we loose any idea about interference pattern.
That's what I call unfair sampling but you can call it whatever way you want.

Forget about ensemble interpretation. I can explain it to you using orthodox QM in much simpler way.

Just to check that we are on the same line. Consider Mach–Zehnder interferometer (http://en.wikipedia.org/wiki/Mach-Zehnder_interferometer).

http://upload.wikimedia.org/wikipedia/commons/2/2d/Mach-zender-interferometer.png

After we count all the phase shifts inside different mirrors Wikipedia says that: "there is no phase difference in the two beams in detector 1, yielding constructive interference." So detector 1 fires when photon arrives there (constructive interference) but detector 2 does not fire when photon arrives there (destructive interference).
So photons arrive at both detectors but because of interference one detector fires but the other don't.

Are we still on the same line here?

NO: where the interference is destructive, no photon arrives in the sense of detection, the only valuable meaning here. On the other side, the photon can be detected (and will be if the detection is perfect). The problem is that such counting (in more general context) may hide something else than what one wants to illustrate. I propose to modify the MZ to adapted diffusers on both branches. Then the overlap of the 2 sets of classical path has positive measure, as in a two slit experiment and one can use a scree or an array of detectors. Many misinterpretations of experiments with delay (delayed measurement and/or delayed erasure) originate in the failure of defining PRECISELY what one means by interference and by using counters and technique from fourth order interferences in a context where second order is what is the issue, creating misinterpretations that lead to confusion and otherwise respectable people speaking of actions backward in time.

Black magic has invaded physics, and in recent posts I have seen again people imagining that Aspect and other similar experiments establish non-locality.
Again, the hypothesis to have Bell inequalities meaning anything of interest in physics is that one has Realism+Locality. For the experiments to have something to have anything to do with Bell theory, one must assume Realism+Locality+Fair Sampling (say R+L+FS).
Now the incompatibility of the experimentally verified quantum correlation (a twisted form of Malus' law) with the mathematically trivial Bell inequalities "prove" in the sense of physics that (R+L+FS) is false. Hence R+L+FS is false, meaning that one at least of
R, L, and FS is false.

Since QM tries to tell us in many way that realism in the form needed by Bell Theory (or in this discussion in particular) is false (something share starting 19930 by Copenhagen and by Einstein and Shrödinger -for whom both, at least Einstein for sure, realism could only be with new, yet unknown variables that contrary to what Bell used , would not permit to give simultaneous values to mutually incompatibles observables as used so far) there is no reason to consider an hypothesis as black-magical as non-locality, an hypothesis that is furthermore such that is cannot get to be verified and that violates the spirit of special relativity that has cured the well known stupidity of instant action (more violent than action at a distance and something that trouble Newton and many others, but fortunately not enough the appropriate corrections would have been well known and testing General relativity would have been harder).

Otherwise stated, if realism is false (as von Neumann thought he had proven in a weak form, but with a false proof while he had a better proof -the one he liked- who appeared much later in Wigner's paper on Bell'inequality, but physicists do not need proof and should not as physics is not the realm of proofs (which is ,ath including logic), and the truth or not of von Neumann's argument was not to trouble people like Bohr, Dirac, Einstein, etc... and even Shrödinger who did read von Neumann's book, as did Dirac I presume (? someone knows for sure: reference please)), there is no place for non-locality by Occam's razor, at least.

Another thread, recently launched by DrC to my request as I do not know how to do and he is well known in these columns, treats the issue of whether Bell's Theorem can be establish without locality. I have posted some pre/re-prints that I have there. But I am saddened to see so many physicists trapped in the maze of misinformation reading them to believe that QM is non local and the nature as well. Bell has really succeeded in mixing people up[ here. He did support both realism and non-locality. While for Wigner, Bel''s theorem is the best proof known till his time that HVs do NOT exist (and again, without HV, or whatever form of microscopic realism, why on earth would one invoke something as baroque as non-locality? There is enough difficulty in the laws of nature to not have to invoke crazy hypotheses to give the sauce a better taste. I like my food extra hot, and find physics even hotter even without assuming that the setting of an instrument changes the output of another instrument at the other end (so to speak) of the Universe. The real physics of that is already difficult enough to understand.

charlylebeaugosse

Aug21-10, 12:25 PM

Most people would say that no photons arrive at detector 2.
You are right: I could have dispensed of a long post. Hope that it has interest t some anyhow.

ThomasT

Aug22-10, 05:19 AM

If there's no underlying reality, then it's possible.
Experiments suggest that there's an underlying reality.
Therefore, it's not possible.

... we could make it simple and say...

If QM is correct, then we are left with these options:

* locality + non-realism

* non-locality + realism

* non-locality + non-realism

How is this simpler? You present three alternatives. I presented only two, and offered a logical conclusion. How to decide among them? Note, we'll stipulate that qm is correct.

Note also that the OP isn't asking whether certain formulations are viable. He's asking whether EPR-type action at a distance is possible (which entails that the observation of something or other is, instantaneously, dependent on the observation of something else, which might be a million light years away).

Bell proved that a certain type of LHV formulation of individual results is compatible with the statistical predictions of qm. Subsequent experiments have verified that Bell-type LHV formulations agree with individual results.
So, Bell showed, and experiments have verified, that individual experimental results are due to properties of underlying disturbances, incident on filters and detectors, that exist prior to and independent of filtration and detection.

On the other hand, Bell also showed, and experiments have verified, that the same Bell LHV formulations which are compatible with individual results are incompatible with joint results.

So, we're faced with what might be called Bell's Paradox: individual results are produced by an observer-independent underlying reality, but joint results (vis the same representation) show that an underlying reality cannot exist.

So, what's the bottom line, the best conclusion regarding what Bell tests (or any quantum experiments for that matter) show? Well, for my money, I think that they show the undeniable existence of an underlying reality. And, of course, if there's an underlying reality, then it exists (necessarily, by definition) whether we happen to be probing it or not, ie., it exists independent of observation -- in which case EPR-type action at a distance is ruled out, ie., impossible.

Of course, there are number of other sorts of nonlocalities. But they're not properly the subject of this thread.

RUTA

Aug22-10, 08:11 AM

If there's no underlying reality, then it's possible.
Experiments suggest that there's an underlying reality.
Therefore, it's not possible.

This is not a deductively valid argument. You (tacitly) assume if and only if in premise one. For example:

P1. If you're shot in the head, you die.
P2. You weren't shot in the head.
C. You're not dead.

But, you could've been stabbed, poisoned, run over by a truck, etc., and be dead even if you weren't shot in the head, so the conclusion is invalid.

Bell proved that a certain type of LHV formulation of individual results is compatible with the statistical predictions of qm. Subsequent experiments have verified that Bell-type LHV formulations agree with individual results.
So, Bell showed, and experiments have verified, that individual experimental results are due to properties of underlying disturbances, incident on filters and detectors, that exist prior to and independent of filtration and detection.

If experiments indicated the existence of "disturbance-causing entities," I doubt Bohr, Ulfbeck, Mottelson, and Zeilinger would have claimed otherwise. Certainly, our interpretation would not have been accepted as a possibility by the foundations community if this was held to be true.

DevilsAvocado

Aug22-10, 08:36 AM

This is not a deductively valid argument. You (tacitly) assume if and only if in premise one. For example:

P1. If you're shot in the head, you die.
P2. You weren't shot in the head.
C. You're not dead.

But, you could've been stabbed, poisoned, run over by a truck, etc., and be dead even if you weren't shot in the head, so the conclusion is invalid.

I think ThomasT has mixed up Counterfactual Definiteness (CFD) with Counterfactual Conditional (http://en.wikipedia.org/wiki/Counterfactual_conditional) ... :rolleyes:
The difference between indicative and counterfactual conditionals can be illustrated with a pair of examples:

If Oswald did not shoot Kennedy, then someone else did.
If Oswald had not shot Kennedy, then someone else would have.

The first sentence is an indicative conditional that is intuitively true. The second is a counterfactual conditional that is not necessarily true.

Maybe we do need that frying pan inset with "No LHV!!" (http://www.physicsforums.com/showpost.php?p=2845966&postcount=1395) ...? :biggrin:

charlylebeaugosse

Aug22-10, 10:12 AM

How is this simpler? You present three alternatives. I presented only two, and offered a logical conclusion. How to decide among them? Note, we'll stipulate that qm is correct.

Note also that the OP isn't asking whether certain formulations are viable. He's asking whether EPR-type action at a distance is possible (which entails that the observation of something or other is, instantaneously, dependent on the observation of something else, which might be a million light years away).

Bell proved that a certain type of LHV formulation of individual results is compatible with the statistical predictions of qm. Subsequent experiments have verified that Bell-type LHV formulations agree with individual results.
So, Bell showed, and experiments have verified, that individual experimental results are due to properties of underlying disturbances, incident on filters and detectors, that exist prior to and independent of filtration and detection.

On the other hand, Bell also showed, and experiments have verified, that the same Bell LHV formulations which are compatible with individual results are incompatible with joint results.

So, we're faced with what might be called Bell's Paradox: individual results are produced by an observer-independent underlying reality, but joint results (vis the same representation) show that an underlying reality cannot exist.

So, what's the bottom line, the best conclusion regarding what Bell tests (or any quantum experiments for that matter) show? Well, for my money, I think that they show the undeniable existence of an underlying reality. And, of course, if there's an underlying reality, then it exists (necessarily, by definition) whether we happen to be probing it or not, ie., it exists independent of observation -- in which case EPR-type action at a distance is ruled out, ie., impossible.

Of course, there are number of other sorts of nonlocalities. But they're not properly the subject of this thread.

What are the references of the results of Bell that are quoted: this does not resemble what I know. If this has to do with Bell1964(Physics) , then please explain the relation between this work of Bell and the proposed interpretation.
Thanks,
CleBG

DevilsAvocado

Aug22-10, 10:31 AM

How is this simpler? You present three alternatives. I presented only two, and offered a logical conclusion. How to decide among them? Note, we'll stipulate that qm is correct.

I don’t know how many times we have to mangle this back and forth before the message goes thru. If we have two mutually dependent variables and we don’t know which is true or false, the only possible options are these:

true/false
false/true
false/false
true/true
Now, Bell's Theorem has proven that if QM is correct we can’t have locality=true/realism=true, i.e. Local Realism (LR) or Local Hidden Variables (LHV), therefore we are left with these three options:

locality=true/realism=false

locality=false/realism=true

locality=false/realism=false
Note also that the OP isn't asking whether certain formulations are viable. He's asking whether EPR-type action at a distance is possible (which entails that the observation of something or other is, instantaneously, dependent on the observation of something else, which might be a million light years away).

I can’t see how the three remaining options don’t make this absolutely clear to OP...??

Bell proved that a certain type of LHV formulation of individual results is compatible with the statistical predictions of qm.

This is mumbo-jumbo and dead wrong. This is what Bell's Theorem says:
No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics.

So, Bell showed, and experiments have verified, that individual experimental results are due to properties of underlying disturbances, incident on filters and detectors, that exist prior to and independent of filtration and detection.

Sophisticated mumbo-jumbo and dead wrong.

On the other hand, Bell also showed, and experiments have verified, that the same Bell LHV formulations which are compatible with individual results are incompatible with joint results.

Well, this is the whole point, isn’t it!?!? How on earth can you say anything about locality by running your nose into ONE polarizer???? I thought you took a break to study this thoroughly...?:bugeye:?

So, we're faced with what might be called Bell's Paradox: individual results are produced by an observer-independent underlying reality, but joint results (vis the same representation) show that an underlying reality cannot exist.

There is nothing called "Bell's Paradox". If you mean Bell's spaceship paradox (http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox) it’s not about EPR or entanglement, it’s about the physical reality of length contraction.

Bell's Theorem do not say anything definite about "an underlying reality", it just says that Local Realism (or Local Hidden Variables) is not compatible with current understanding of QM. You could have Non-Local Hidden Variables (NLHV) for example, and that would be compatible with QM.

So, what's the bottom line, the best conclusion regarding what Bell tests (or any quantum experiments for that matter) show? Well, for my money, I think that they show the undeniable existence of an underlying reality. And, of course, if there's an underlying reality, then it exists (necessarily, by definition) whether we happen to be probing it or not, ie., it exists independent of observation -- in which case EPR-type action at a distance is ruled out, ie., impossible.

Dead wrong again, If QM is correct you can’t have Locality + Realism, it’s incompatible with QM.

I think we all can agree that RUTA is the only working scientist in this thread, and as a member of the scientific community, and as PhD Professor of Physics, I think we can trust in that what he has to say:

When I first entered the foundations community (1994), there were still a few conference presentations arguing that the statistical and/or experimental analyses of EPR-Bell experiments were flawed. Such talks have gone the way of the dinosaurs. Virtually everyone agrees that the EPR-Bell experiments and QM are legit, so we need a significant change in our worldview.
That the information is available AFTER the fact doesn't bear on a possible CAUSE for the correlations. The point is that the detector setting at site A is NOT available to site B BEFORE the detection event occurs at site B. If this information is available prior to detection, the correlations in the outcomes can be orchestrated to violate Bell's inequality. No one disputes this fact -- you have to keep the outcome at each site dependent ONLY upon information AT THAT SITE to have the conundrum about their correlations.

Thus, there are generally two ways to account for EPR-Bell correlations. 1) The detection events are separable and you have superluminal exchange of information. 2) The detection events are not separable, e.g., the spin of the entangled electrons is not a property of each electron. The first property is often called "locality" and the second property "realism."
Violations of Bell inequalities imply nonlocality and/or nonseparability.

So, nonseparability alone would do the trick, thereby saving locality (no FTL causal connections).
Science has not proven nonlocality. I'm a physicist who believes the Bell experiments are legit, but these experiments don't prove nonlocality; they prove nonlocality and/or nonseparability. So, it's possible that we have nonseparability and locality.

And everything that RUTA says lead unquestionably to these three (3) options, again:

locality=true/realism=false

locality=false/realism=true

locality=false/realism=false

For those who do not understand this, I recommend Abbot & Costello "Who's on first?" (http://www.physicsforums.com/showpost.php?p=2846608&postcount=1407).

RUTA

Aug22-10, 11:34 AM

I think we all can agree that RUTA is the only working scientist in this thread, and as a member of the scientific community, and as PhD Professor of Physics, I think we can trust in that what he has to say

Well, my research resides in the foundations of physics and I try to convey here what I've learned from interacting with that community. However, I'm not a leader in this field by any means, so if any of my statements conflict with those of Zeilinger, Price, Vaidman, Hardy, etc., you know who to believe :smile:

unusualname

Aug22-10, 01:11 PM

DevilsAvocado

Aug22-10, 04:40 PM

Well, my research resides in the foundations of physics and I try to convey here what I've learned from interacting with that community. However, I'm not a leader in this field by any means, so if any of my statements conflict with those of Zeilinger, Price, Vaidman, Hardy, etc., you know who to believe :smile:

It’s great to have you around RUTA. It doesn’t matter that you’re not the leader in this field – you are the "warranty" in this thread for one of the central points in PF Global Guidelines:
Physicsforums.com strives to maintain high standards of academic integrity. There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound.

Thanks! o:)

DevilsAvocado

Aug22-10, 04:53 PM

don't forget

locality=true/realism=true

and we also have superdeterminism (ie the correlations are predetermined)

Though that is too depressing to contemplate.

Yes, you are right. And it’s not only the correlations that are predetermined – everything is predetermined, including this conversation.

If I "decide" to type this: %&”¤%&”(=)(“()=!=?
And then "change" my mind to type this: oiwuiowurioweuwerp

You could ask – what the heck is the "predetermined meaning" of this???? And I can’t find a good answer... other than it’s completely crazy, and I can’t see how science could survive this doom...

And why are we discussing something that’s already predetermined??

Also MWI will give us locality=true/realism=true, but I don’t know how to "weigh" unproven interpretations and "wild" hypothesis... maybe RUTA can tell...

Once we resolve the true nature of reality, I feel these debates will seem very naive,

Of course you are absolutely right. It will seem exactly as naive as when Newton made a strong reservation to his own law of gravity and the notion of "action at a distance".

That’s why these "personal feelings" on what is "right & wrong" almost makes me laugh. What do nature care about us and our "personal feelings" on how "things" should work?? It’s just silly.

especially if we're living in some kind of holographic construction of spacetime, with the hilbert space of QM mapping onto our perceived 3D reality in an incredibly devious manner...

Does it really have to be "incredibly devious"? Couldn’t it also be "incredibly obvious" as well? If you bake spacetime into 2D, Alice & Bob would be positioned along a straight line. If the "QM world" is 1D, then Alice & Bob would be in the same place (looking at the line from the "edge"), right?

Just some "personal thoughts"... :rolleyes:

unusualname

Aug22-10, 07:04 PM

Does it really have to be "incredibly devious"? Couldn’t it also be "incredibly obvious" as well? If you bake spacetime into 2D, Alice & Bob would be positioned along a straight line. If the "QM world" is 1D, then Alice & Bob would be in the same place (looking at the line from the "edge"), right?

Just some "personal thoughts"... :rolleyes:

I sometimes wish it does turn out to be as nice and simple as that, but you've got to believe that the obvious models have been dismissed for good reasons (rather like all the simple "proofs" of fermat's last theorem never worked)

Unfortunately it's looking like it will be a bit more involved, eg:
Holography and non-locality in a closed vacuum-dominated universe (http://arxiv.org/abs/gr-qc/0609128)

It's frustrating to live in a time with so much still unknown.

nismaratwork

Aug22-10, 07:16 PM

I sometimes wish it does turn out to be as nice and simple as that, but you've got to believe that the obvious models have been dismissed for good reasons (rather like all the simple "proofs" of fermat's last theorem never worked)

Unfortunately it's looking like it will be a bit more involved, eg:
Holography and non-locality in a closed vacuum-dominated universe (http://arxiv.org/abs/gr-qc/0609128)

It's frustrating to live in a time with so much still unknown.

I'm a big fan of the Holographic Principle; it resolves so many of those unknowns, but one thing... isn't it better to be deviled by questions than have every answer? I love the fodder for curiosity, and since omniscience isn't an option, I'll take a period of record progress and learning.

RUTA

Aug22-10, 09:16 PM

It's frustrating to live in a time with so much still unknown.

“In the past, fundamental new discoveries have led to changes – including theoretical, technological, and conceptual changes – that could not even be imagined when the discoveries were first made. The discovery that we live in a universe that, deep down, allows for Bell-like influences strikes me as just such a fundamental, important new discovery. … If I am right about this, then we are living in a period that is in many ways like that of the early 1600s. At that time, new discoveries, such as those involving Galileo and the telescope, eventually led to an entirely new way of thinking about the sort of universe we live in. Today, at the very least, the discovery of Bell-like influences forces us to give up the Newtonian view that the universe is entirely a mechanistic universe. And I suspect this is only the tip of the iceberg, and that this discovery, like those in the 1600s, will lead to a quite different view of the sort of universe in which we live.” Worldviews: An Introduction to the History and Philosophy of Science, Richard DeWitt, Blackwell Publishing, 2004, p 304.

I think it's an exciting time to be a physicist!

ThomasT

Aug22-10, 09:31 PM

I can’t see how the three remaining options don’t make this absolutely clear to OP...??The OP is asking about what's possible in reality, not what sorts of theories are possible. Your three options are about models, not reality. They don't address the OP's question.

In order to answer the OP's question we just need to answer one question: do (any) quantum experimental phenomena indicate the existence of an underlying reality? Do, say, optical Bell tests indicate that the detectors are detecting disturbances transmitted by the filters, and that the filters are analyzing disturbances emitted by the emitters and which propagate from emitter to filter? I think they do.

Does anybody know the qualitative nature of these disturbances? Not afaik. Does it make any sense to say that they don't exist? I don't think so -- and if the emitters are producing disturbances which propagate to the filters to be transmitted or not to the detectors, then the answer to the OP's question has to be NO.

--------------------------------------------------------------------------------------------

There is nothing called "Bell's Paradox".Bell's Paradox is that individual results, vis Bell, are compatible with the idea of an underlying reality, but entangled results, vis Bell, seem not to be. Afaik, I coined this usage, so don't bother looking it up.

Bell's Theorem does not say anything definite about "an underlying reality" ... I agree. It's really irrelevant wrt the OP's question.

charlylebeaugosse

Aug23-10, 11:16 AM

don't forget

locality=true/realism=true

and we also have superdeterminism (ie the correlations are predetermined)

Though that is too depressing to contemplate.

Once we resolve the true nature of reality, I feel these debates will seem very naive, especially if we're living in some kind of holographic construction of spacetime, with the hilbert space of QM mapping onto our perceived 3D reality in an incredibly devious manner...

Wrong: realism (+locality) is enough (and compatibility with the stats of QM): no need of determinism as in Bell 1964. To my knowledge (and apparently to Leggett's and Bernhardt as well, among others) this was first observed by Stapp who introduced an hypothesis called contrafactual definiteness, then a weaker form of realism was used by Leggett who proved it weaker than Stapp's hypothesis and by Tresser who present that as the weakest form of realism needed a Bell type theorem: value of observables are pre-existent to measurement if measurement could be made and some observable is measured. There is also something that Leggett calls microscopic realism, so three concepts at least can be used, none of which require predetermination other than what is required by realism anyway.

RUTA

Aug23-10, 02:17 PM

The OP is asking about what's possible in reality, not what sorts of theories are possible. Your three options are about models, not reality. They don't address the OP's question.

In order to answer the OP's question we just need to answer one question: do (any) quantum experimental phenomena indicate the existence of an underlying reality? Do, say, optical Bell tests indicate that the detectors are detecting disturbances transmitted by the filters, and that the filters are analyzing disturbances emitted by the emitters and which propagate from emitter to filter? I think they do.

Does anybody know the qualitative nature of these disturbances? Not afaik. Does it make any sense to say that they don't exist? I don't think so -- and if the emitters are producing disturbances which propagate to the filters to be transmitted or not to the detectors, then the answer to the OP's question has to be NO.

The original post was simply, "Is action at a distance possible as envisaged by the EPR Paradox?" The short answer is "yes." Nonetheless, PF has generated 89 web pages of responses so far :smile:

JesseM

Aug23-10, 04:04 PM

In order to answer the OP's question we just need to answer one question: do (any) quantum experimental phenomena indicate the existence of an underlying reality? Do, say, optical Bell tests indicate that the detectors are detecting disturbances transmitted by the filters, and that the filters are analyzing disturbances emitted by the emitters and which propagate from emitter to filter? I think they do.

Does anybody know the qualitative nature of these disturbances? Not afaik. Does it make any sense to say that they don't exist? I don't think so -- and if the emitters are producing disturbances which propagate to the filters to be transmitted or not to the detectors, then the answer to the OP's question has to be NO.
Bell's theorem logically deals with all possible "disturbances" that match the assumptions of local realism. If you assume that A) the "disturbances" are in local variables that travel along with the particle (or wave, or whatever it is that travels from source to detector), and B) these local variables are only causally influenced by events in their past light cones (so the value of variables associated with particle/wave A after passing through a filter can be influenced by properties of that filter, but not by the orientation of another filter whose orientation was chosen at a space-like separation from event of A passing through its own filter), and C) the result at one detector only depends on local variables associated with the particle/wave at the moment it reaches the detector along with local variables associated with the detector itself, then any theory involving a "disturbance" matching these conditions would satisfy Bell inequalities. The theoretical proof of this doesn't depend on the specific details of what the local variables are or how they are "disturbed", it holds for any theory which is "local realist" in the sense above.

unusualname

Aug23-10, 07:22 PM

New Scientist have a feature article on QM this week:

Is quantum theory weird enough for the real world? (http://www.newscientist.com/article/mg20727741.300-is-quantum-theory-weird-enough-for-the-real-world.html?full=true)

Lubos Motl has posted a slightly hysterical commentary (http://motls.blogspot.com/2010/08/new-scientist-attacks-quantum-physics.html) (he mostly hates NS since it promotes climate change arguments so passionately), check out the comments section for some epr/bell related links.

A couple of journal papers linked to in the NS article are available on arXiv:

A limit on nonlocality in any world in which communication complexity is not trivial (http://arxiv.org/abs/quant-ph/0508042)
All reversible dynamics in maximally non-local theories are trivial (http://arxiv.org/abs/0910.1840)

ThomasT

Aug24-10, 01:07 AM

You (tacitly) assume if and only if in premise one.Yes, I should have stated it something like this:
EPR-type action at a distance is possible iff there's no deep reality.
Experiments suggest the existence of a deep reality, ie., that this is the most reasonable assumption.
Therefore, EPR-type action at a distance is, most reasonably, not possible.

Of course, the existence or nonexistence of a deep reality can't be proven. It can only be inferred (or not, as one might choose) from instrumental behavior.

We can ask: are the various possible answers to the OP's question equally tenable? I don't think they are. The assumption of the existence of a deep reality seems to me to be an essential part of fundamental physics.

If experiments indicated the existence of "disturbance-causing entities," I doubt Bohr, Ulfbeck, Mottelson, and Zeilinger would have claimed otherwise.We can assume that emitters don't emit anything, filters don't filter anything, and detectors don't detect anything -- ie., that there's no deep reality that's ultimately affecting and determining instrumental results. In which case, EPR-type action at a distance would be necessary, and the answer to the OP's question would be yes.

Certainly, our interpretation would not have been accepted as a possibility by the foundations community if this was held to be true.Are you saying that the acceptance of your interpretation by the foundations communitiy is based on a generally held assumption that instrumental behavior is not determined by the existence and behavior of a reality deeper than the instrumental level?

The original post was simply, "Is action at a distance possible as envisaged by the EPR Paradox?" The short answer is "yes."The short answer is also "no", depending on what's inferred/assumed. Of course, the most sensible answer is "we don't know", which we might express as a "definite maybe" regarding the possible answers to the OP's question.

Nonetheless, PF has generated 89 web pages of responses so far :smile:.Yes, isn't it awesome that there are so many interesting (more or less) considerations associated with the OP's question?

ThomasT

Aug24-10, 01:18 AM

In order to answer the OP's question we just need to answer one question: do (any) quantum experimental phenomena indicate the existence of an underlying reality? Do, say, optical Bell tests indicate that the detectors are detecting disturbances transmitted by the filters, and that the filters are analyzing disturbances emitted by the emitters and which propagate from emitter to filter? I think they do.

Does anybody know the qualitative nature of these disturbances? Not afaik. Does it make any sense to say that they don't exist? I don't think so -- and if the emitters are producing disturbances which propagate to the filters to be transmitted or not to the detectors, then the answer to the OP's question has to be NO.

Bell's theorem logically deals with all possible "disturbances" that match the assumptions of local realism. If you assume that A) the "disturbances" are in local variables that travel along with the particle (or wave, or whatever it is that travels from source to detector), and B) these local variables are only causally influenced by events in their past light cones (so the value of variables associated with particle/wave A after passing through a filter can be influenced by properties of that filter, but not by the orientation of another filter whose orientation was chosen at a space-like separation from event of A passing through its own filter), and C) the result at one detector only depends on local variables associated with the particle/wave at the moment it reaches the detector along with local variables associated with the detector itself, then any theory involving a "disturbance" matching these conditions would satisfy Bell inequalities. The theoretical proof of this doesn't depend on the specific details of what the local variables are or how they are "disturbed", it holds for any theory which is "local realist" in the sense above.What does this have to do with my statements that you seem to be replying to, or the OP's question?

JesseM

Aug24-10, 04:51 AM

What does this have to do with my statements that you seem to be replying to, or the OP's question?
I would think my point was pretty obvious. Bell's theorem proves that any "realist" picture of what is going on--which presumably includes your rather concrete-sounding notion of the results being dependent on some sort of physical "disturbances"--cannot be a local one. You seemed to be saying that since we don't know the exact details of the supposed "disturbances" we can't give an affirmative answer to the OP:
Does anybody know the qualitative nature of these disturbances? Not afaik. Does it make any sense to say that they don't exist? I don't think so -- and if the emitters are producing disturbances which propagate to the filters to be transmitted or not to the detectors, then the answer to the OP's question has to be NO.
But the point is, Bell's reasoning doesn't require us to know anything specific about the "qualitative nature" of what's going on with the local hidden variables (including how they might be disturbed upon passing through a filter), it shows that all local realist theories are incompatible with QM's predictions. So, if the "disturbances" are meant to be disturbances in local realistic variables, then hell yes it "makes sense to say that they don't exist", that's exactly what Bell's theorem proves!

zonde

Aug24-10, 08:28 AM

NO: where the interference is destructive, no photon arrives in the sense of detection, the only valuable meaning here.
The problem here is that QM does not say this.
Only thing that QM says is that no photons are detected. You have to associate detection with photon in order to say that no photons arrived at detector. But that step brings you out of orthodox QM domain.

Btw, what do you mean by realism and violation of realism? Do you mean that measurements are contextual or something else?

zonde

Aug24-10, 08:48 AM

I would think my point was pretty obvious. Bell's theorem proves that any "realist" picture of what is going on--which presumably includes your rather concrete-sounding notion of the results being dependent on some sort of physical "disturbances"--cannot be a local one. You seemed to be saying that since we don't know the exact details of the supposed "disturbances" we can't give an affirmative answer to the OP:

But the point is, Bell's reasoning doesn't require us to know anything specific about the "qualitative nature" of what's going on with the local hidden variables (including how they might be disturbed upon passing through a filter), it shows that all local realist theories are incompatible with QM's predictions. So, if the "disturbances" are meant to be disturbances in local realistic variables, then hell yes it "makes sense to say that they don't exist", that's exactly what Bell's theorem proves!
Bell's theorem proves that any "realist" picture of what is going on cannot be a local one under hypothetical experimental conditions described in his theory.
But because this hypothetical experimental conditions are too far from reality you have to establish some correspondence between this theory and feasible real experiments. That is done by CHSH inequalities. But in order to apply CHSH inequalities to real experiments you need fair sampling assumption and before this fair sampling assumption is experimentally investigated the link between Bell's theorem and physical reality is broken and Bell's theorem has quite limited bearing on possible interpretations of physical reality.

One thing that it proves (with the help of CHSH inequalities and experiments) is that non-contextual LHVs are ruled out. But that can be inferred from HUP anyways. It's just more obvious with help of Bell.

DevilsAvocado

Aug24-10, 10:51 AM

I sometimes wish it does turn out to be as nice and simple as that, but you've got to believe that the obvious models have been dismissed for good reasons (rather like all the simple "proofs" of fermat's last theorem never worked)

Yes, you are probably right – if it were simple, it would already been solved.

But let’s at least hope it’s fairly logical and "beautiful" when completed, like when Kepler’s Mysterium Cosmographicum was explained (almost) by Newton's genius law:

F = G \frac{m_1 m_2}{r^2},\

DevilsAvocado

Aug24-10, 10:57 AM

“In the past, fundamental new discoveries have led to changes – including theoretical, technological, and conceptual changes – that could not even be imagined when the discoveries were first made. The discovery that we live in a universe that, deep down, allows for Bell-like influences strikes me as just such a fundamental, important new discovery. … If I am right about this, then we are living in a period that is in many ways like that of the early 1600s. At that time, new discoveries, such as those involving Galileo and the telescope, eventually led to an entirely new way of thinking about the sort of universe we live in. ...”

YES! This is exactly what I believe too!

I think it's an exciting time to be a physicist!

(Even as layman I) AGREE! The Future's So Bright, I Gotta Wear Shades! :smile:

http://30.media.tumblr.com/tumblr_kz11bcLl0r1qza4ndo1_400.jpg

DevilsAvocado

Aug24-10, 11:07 AM

The OP is asking about what's possible in reality, not what sorts of theories are possible. Your three options are about models, not reality. They don't address the OP's question.

They don’t...?:uhh:?
"Is action at a distance possible as envisaged by the EPR Paradox."

YES, action at a distance is possible as predicted by the EPR Paradox, because these are the 3 options:

locality=true/realism=false

locality=false/realism=true

locality=false/realism=false

(locality=false --> action at a distance)

I could be wrong, but I thought that OP wanted us to describe the state of current professional mainstream science – not personal guessing...

DevilsAvocado

Aug24-10, 11:08 AM

DevilsAvocado

Aug24-10, 11:20 AM

New Scientist have a feature article on QM this week:

Is quantum theory weird enough for the real world? (http://www.newscientist.com/article/mg20727741.300-is-quantum-theory-weird-enough-for-the-real-world.html?full=true)

Great article!
New Scientist – Is quantum theory weird enough for the real world? (http://www.newscientist.com/article/mg20727741.300-is-quantum-theory-weird-enough-for-the-real-world.html?full=true)

...
"Quantum mechanics is, in our range of experience, a correct theory. It is sort of fine and we don't know what is better." But there are niggles that make him and others itch for something new. One is the great unfinished business of unifying quantum theory with general relativity, Einstein's resolutely classical theory of gravity. "Quantum mechanics and general relativity don't like each other," says Plenio.
...
So how do we set about finding what makes quantum theory tick? Most of the recent work has homed in on one central yet unexplained feature of quantum physics- the degree of "correlation" between the states of unconnected bodies that the theory does, or does not,
...
In 1964, John Bell of the CERN particle physics laboratory near Geneva, Switzerland, described the degree of correlation that classical theories allow. Bell's result relied on two concepts: realism and locality.
...
Realism amounts to saying that the properties of an object exist prior to, and independent of, measurement. In the classical world, that second sock in my drawer is red regardless of whether or not I "measure" its state by looking at it. Locality is the assumption that these properties are independent of any remote influence.

Great description of Bell's Inequality! And in the light of this – If we look back on the hundred of posts billschnieder produced on the theme that it’s impossible to formulate a Bell Inequality – YOU GOT TO LAUGH! :rofl:

Lubos Motl has posted a slightly hysterical commentary (http://motls.blogspot.com/2010/08/new-scientist-attacks-quantum-physics.html) (he mostly hates NS since it promotes climate change arguments so passionately), check out the comments section for some epr/bell related links.

Hehe, "slightly" is very diplomatic... Luboš Motl seems to have several problems with the climate, girls, strange Slavic names, name of magazines... As far as I know the Czech Republic is Slavic, and Luboš Motl can be strange to some... :wink:

I wish an extremely intelligent girl, with an extremely strange name, from Bulgaria, come along and give us the new paradigm in physics – that would make both Luboš Motl & Lawrence Summers drop their jaws and fall off their chairs! :biggrin:

DevilsAvocado

Aug24-10, 11:22 AM

... Of course, the most sensible answer is "we don't know", ...

Great TT! I’m with you all the way on this! :!!)

charlylebeaugosse

Aug24-10, 11:39 AM

The original post was simply, "Is action at a distance possible as envisaged by the EPR Paradox?" The short answer is "yes." Nonetheless, PF has generated 89 web pages of responses so far :smile:

The answer is in fact NO. No one as acted in any way on an event spatially remote. There is no good reasons to believe that what Einstein called spooky action is possible, and ALL conclusions to the contrary are based on erroneous reading of Bell, Aspect, etc... or misquotes by these people themselves. Many time people have recalled that QM is non-local and only realist interpreters need non-locality, a phenomenon with no measurable effect that cannot be interpreted more simply otherwise.

charlylebeaugosse

Aug24-10, 11:48 AM

YES! :smile:

Give ONE example where influence on a spatially remote object can be proven without invoking realism of micro-physics, please, and then you can honestly say yes. I can unfortunately give countless examples of mis-quotation, wrong attributions, circular reasoning etc... from all of the tenors of remote action, even typical examples of dishonesty.
I challenge the reciprocity for the people who like Leggett, think that the wrong hypothesis in the realism-locality pair is realism. If realism (at the microscopic level) goes, all "arguments" in favor of remote action fall. Another thread is devoted to Bell theorem without locality assumption, less known of course than the work of Leggett but aiming also at booting realsim out of microphysics.

JesseM

Aug24-10, 11:57 AM

Bell's theorem proves that any "realist" picture of what is going on cannot be a local one under hypothetical experimental conditions described in his theory.
But because this hypothetical experimental conditions are too far from reality you have to establish some correspondence between this theory and feasible real experiments. That is done by CHSH inequalities. But in order to apply CHSH inequalities to real experiments you need fair sampling assumption and before this fair sampling assumption is experimentally investigated the link between Bell's theorem and physical reality is broken and Bell's theorem has quite limited bearing on possible interpretations of physical reality.

One thing that it proves (with the help of CHSH inequalities and experiments) is that non-contextual LHVs are ruled out. But that can be inferred from HUP anyways. It's just more obvious with help of Bell.
There is a version of the CHSH inequality (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Detection_effic iency_loophole_and_the_fair_sampling_assumption) that incorporates the fact that not all particle pairs are detected, although it requires that at least 82% of particle pairs are detected for the inequality to be violated (67% in the case of the Clauser-Horne test (http://en.wikipedia.org/wiki/CHSH_inequality#Derivation_from_Clauser_and_Horne. 27s_1974_inequality)), which is higher than most experiments can do. But in fact a few experiments have closed the "detector efficiency loophole" (the loophole which depends on the idea that the measured particles may not be a 'fair sample' of all particles emitted), see here (http://deepblue.lib.umich.edu/bitstream/2027.42/62731/1/409791a0.pdf) and here (http://prl.aps.org/abstract/PRL/v100/i15/e150404). Neither of these experiments managed to simultaneously close the locality loophole (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Locality), but I think it would require a very contrived local realist theory to exploit both loopholes at once (i.e. exploit the locality loophole in experiments that closed the detector efficiency loophole, and exploit the detector efficiency loophole in experiments that closed the locality loophole), as I argued here (http://www.physicsforums.com/showthread.php?p=2816638#post2816638):
In contrast, I think lots of very smart physicists would agree with the intuition that a local realist theory consistent with all past experiments but which predicted no Bell inequality violation in ideal loophole-free experiments would have to be rather "contrived". Perhaps one reason for this is that we know what is required to exploit each loophole individually--exploiting the detector efficiency loophole requires that in some pairs of particles, one of the pair has a hidden variable that makes it impossible to detect (see billschnieder's example in posts #113 and #115 on this thread (http://www.physicsforums.com/showthread.php?t=409161&page=8)), whereas exploiting the locality loophole requires that whichever member of the pair is detected first will send out some sort of signal containing information about what detector setting was used, a signal which causes the other particle to change its own hidden variables in just the right way as to give statistics that agree with QM predictions.
Also, there are a number of papers that claim it will be possible to close both loopholes simultaneously in experiments that may be doable in the near future, see here (http://arxiv.org/abs/quant-ph/0701191) and here (http://arxiv.org/abs/0909.3171).

RUTA

Aug24-10, 12:04 PM

Yes, I should have stated it something like this:
EPR-type action at a distance is possible iff there's no deep reality.
Experiments suggest the existence of a deep reality, ie., that this is the most reasonable assumption.
Therefore, EPR-type action at a distance is, most reasonably, not possible.

Of course, the existence or nonexistence of a deep reality can't be proven. It can only be inferred (or not, as one might choose) from instrumental behavior.

We can ask: are the various possible answers to the OP's question equally tenable? I don't think they are. The assumption of the existence of a deep reality seems to me to be an essential part of fundamental physics.

I'm probably misunderstanding you, but you can correct me if that's the case. When you say "the existence of a deep reality" I picture "microscopic" or "hidden" entities at work among, and distinct from, the elements of the experimental equipment.

We can assume that emitters don't emit anything, filters don't filter anything, and detectors don't detect anything -- ie., that there's no deep reality that's ultimately affecting and determining instrumental results. In which case, EPR-type action at a distance would be necessary, and the answer to the OP's question would be yes.

In RBW, there are no "microscopic" or "hidden" entities at work among, and distinct from, the elements of the experimental equipment, but there is no action at a distance either. That's because it's not a dynamical ontology, i.e., explanation isn't based on cause and effect, but on a nonseparable "4Dism."

Are you saying that the acceptance of your interpretation by the foundations communitiy is based on a generally held assumption that instrumental behavior is not determined by the existence and behavior of a reality deeper than the instrumental level?

The acceptance is based simply on its logical possibility (as shown by relevant calculations). Do they subscribe to it? No, by and large they hate it :smile:

The short answer is also "no", depending on what's inferred/assumed. Of course, the most sensible answer is "we don't know", which we might express as a "definite maybe" regarding the possible answers to the OP's question.

Perhaps we have different interpretations of the OP question. I read it, "Is non-locality possible given EPR phenomena?" Since it is generally agreed that EPR-Bell phenomena imply non-locality and/or nonseparability, the short answer is "yes, non-locality is a possibility."

Yes, isn't it awesome that there are so many interesting (more or less) considerations associated with the OP's question?

I've sure had a lot of fun with this thread!

RUTA

Aug24-10, 12:12 PM

The answer is in fact NO. No one as acted in any way on an event spatially remote. There is no good reasons to believe that what Einstein called spooky action is possible, and ALL conclusions to the contrary are based on erroneous reading of Bell, Aspect, etc... or misquotes by these people themselves. Many time people have recalled that QM is non-local and only realist interpreters need non-locality, a phenomenon with no measurable effect that cannot be interpreted more simply otherwise.

As far as I know the DeBroglie-Bohm interpretation has not been ruled out by the foundations community. Therefore, non-locality as a possible consequence of EPR-Bell phenomena has not been ruled out by the foundations community. I haven't heard anyone argue for the dismissal of non-locality in general. Is someone championing this view in the foundations community? As someone with a local, nonseparble interpretation of QM, I'd like to read their work.

Lampshade132

Aug24-10, 03:19 PM

DevilsAvocado

Aug24-10, 04:34 PM

I just read something interesting about entanglement that I have not seen discussed before. What is everyones thoughts on thinking of two entangled objects as single higher dimensional object passing through our 3D universe at two different locations. Much like how a 3D object could appear at separate locations, thus appearing like two objects in a 2D plane.

Welcome to PF Lampshade132!

Maybe this link from unusualname can be helpful:
Unfortunately it's looking like it will be a bit more involved, eg:
Holography and non-locality in a closed vacuum-dominated universe (http://arxiv.org/abs/gr-qc/0609128)

DevilsAvocado

Aug24-10, 04:54 PM

Give ONE example where influence on a spatially remote object can be proven without invoking realism of micro-physics, please,
...
I challenge the reciprocity for the people who like Leggett, think that the wrong hypothesis in the realism-locality pair is realism. If realism (at the microscopic level) goes, all "arguments" in favor of remote action fall.

I think that we both agree that nothing is proven definitely, right? So to say; "I’m sure of this or that", is no more than personal speculations, right?

And just because "realism goes" does not prove beyond all doubts that locality is true, right?

So, one of these three options must be correct:

locality=true/realism=false

locality=false/realism=true

locality=false/realism=false

Right?

Then I don’t think it’s unfair to say: YES - action at a distance is a possibility, until we know better.

(To avoid any "translation errors" – We are not talking about faster than light communication! The outcome of EPR-Bell experiments is always 100% random.)

charlylebeaugosse

Aug24-10, 07:17 PM

As far as I know the DeBroglie-Bohm interpretation has not been ruled out by the foundations community. Therefore, non-locality as a possible consequence of EPR-Bell phenomena has not been ruled out by the foundations community. I haven't heard anyone argue for the dismissal of non-locality in general. Is someone championing this view in the foundations community? As someone with a local, nonseparble interpretation of QM, I'd like to read their work.
See the comments of of Pauli and Einstein on deB-B theory. Anyway, why spend time on a theory so violently incompatible with Lorentz invariance, beside the attacks of Wolfgang P.
Many false theories are around, such as many version of Kaluza-Klein, Weyl, variations on super-strings: at least with those progress in math have been made. In fact, Wigner would have said (and he did, but in more general form covering all HV theories satisfying the hypothesis of Bell1964) that "Bell's Theorem is the nicest proof that HVs are false". Non-locality is not physics and cannot lead to any observation that is not a consequence of an a-priori stand on pre-existence of observable values to measurement. The fact that there is a club making themselves happy with dBB makes not dBB part of physics. There are such clubs in most disciplines. The problem is that more and more crazy viewpoints of QM (many words, many minds, many schmucks, etc...) are winning more and more support. Science is in danger when the most central piece of the most central discipline is under serious attack and the evil forces of magic and fantasy become the ruling (compare the extent of Bell theory vs elementary particles or thermodynamics on the www: see how many tenors of physics claim that actions can be taken upon the past). It is true that the Copenhagen team opened the doors to the flood by allowing religious stands where perpetual re-examination and progress should be the way to go. The interpretation by Wheeler of delayed measurement was the door open to violation of the time arrow at macroscopic scale. But the errors of the past should not excuse new errors but should rather make us more cautious. What would have happened to math if seeing mistakes in rigor by the old masted would have been an excuse for more lack of rigor instead of devising methods and language to allow modern analysis and its various applications? Math would be dead by now and physics is certainly in grave danger: it may soon come under control of engineering if we accept non-sense such as dBB as something else than anecdotes on what physics could have looked like.

charlylebeaugosse

Aug24-10, 07:25 PM

I think that we both agree that nothing is proven definitely, right? So to say; "I’m sure of this or that", is no more than personal speculations, right?

And just because "realism goes" does not prove beyond all doubts that locality is true, right?

So, one of these three options must be correct:

locality=true/realism=false

locality=false/realism=true

locality=false/realism=false

Right?

Then I don’t think it’s unfair to say: YES - action at a distance is a possibility, until we know better.

(To avoid any "translation errors" – We are not talking about faster than light communication! The outcome of EPR-Bell experiments is always 100% random.)

We have to be extra cautious: in similar circumstance, when a viewpoint is odd cannot be falsified, one gets rid of it by using Occam's razor, AND here we also have the work of Leggett and a (couple of) paper(s) discussed elsewhere on PF about Bell without locality assumption which is not far from proving that realism is the only issue since an hypothesis whose negation yields super-luminal info transmission when restricted to observed quantities replaces locality to get one Bell Theorem.

Saying YES is wrong here: we could say; the YES has not yet been ruled out but standard practice of physics lead to consider that the correct answer is "NO until otherwise proven", of something of that kind.

zonde

Aug25-10, 05:10 AM

There is a version of the CHSH inequality (http://en.wikipedia.org/wiki/Loopholes_in_Bell_test_experiments#Detection_effic iency_loophole_and_the_fair_sampling_assumption) that incorporates the fact that not all particle pairs are detected, although it requires that at least 82% of particle pairs are detected for the inequality to be violated (67% in the case of the Clauser-Horne test (http://en.wikipedia.org/wiki/CHSH_inequality#Derivation_from_Clauser_and_Horne. 27s_1974_inequality)), which is higher than most experiments can do.
You don't have to reach theoretical limit of elimination of fair sampling assumption to investigate it's validity.
That can be done by performing experiments with different detection efficiencies and different coincidence rates that show trends (or no trends if fair sampling is valid) in observed results. Moreover such experiment is quite trivial comparing it to all the different photon entanglement experiments performed nowadays.

But still there are no such experiments so all the talk about extrapolating results of low efficiency Bell photon experiments to high efficiency case is unjustifiable.

In contrast, I think lots of very smart physicists would agree with the intuition that a local realist theory consistent with all past experiments but which predicted no Bell inequality violation in ideal loophole-free experiments would have to be rather "contrived". Perhaps one reason for this is that we know what is required to exploit each loophole individually--exploiting the detector efficiency loophole requires that in some pairs of particles, one of the pair has a hidden variable that makes it impossible to detect (see billschnieder's example in posts #113 and #115 on this thread), whereas exploiting the locality loophole requires that whichever member of the pair is detected first will send out some sort of signal containing information about what detector setting was used, a signal which causes the other particle to change its own hidden variables in just the right way as to give statistics that agree with QM predictions.
You are not proponent of local realism so you viewpoint about what is required to exploit each loophole does not really count, right?

Lets see it in more details.
You say: "exploiting the detector efficiency loophole requires that in some pairs of particles, one of the pair has a hidden variable that makes it impossible to detect"
This model does not lead to unfair sampling if "detection-HV" is attached to particle at source. Fair sampling still applies.

However we can have a different view. First PBS can't measure polarization of particle when we perform measurement (+45/-45 base) that is non-commuting with polarization measurement (H/V base) because in that case two measurements will be commuting.
So we have to have second measurement that performs phase measurement between H and V modes (where PBS only alters phase of photons depending from their polarization). That second measurement device can be detector or alternatively interference filter.
This fits orthodox QM quite well.

You say: "exploiting the locality loophole requires that whichever member of the pair is detected first will send out some sort of signal containing information about what detector setting was used"
This of course is not quite creditable as particles would have to produce other particles to carry information to second member.

However we again can have a different view. First experiments with efficient detection utilize fermions or at least particles that are confined to equipment. So these particles don't share the same context and all correlations between them are classical i.e. they are not entangled at all.
In that case only option left is crosstalk between measurement processes. For example if we look at Rowe's et al experiment we can see that scattered photons are allowed to interfere at detector but it is just assumed that it hasn't any effect on different measurement combinations (again fair sampling assumption). In experiment performed by Matsukevich et al manipulations of ions are done using microwave pulses but microwaves are definitely subject to crosstalk. But here we can test how reasonable is assumption of independence of two measurements by varying distance between two measurement places and observing presence or absence of any trends in results.

So you see that your argument about "contrived" LHV model is very subjective.

DevilsAvocado

Aug25-10, 08:04 AM

We have to be extra cautious: in similar circumstance, when a viewpoint is odd cannot be falsified, one gets rid of it by using Occam's razor, AND here we also have the work of Leggett and a (couple of) paper(s) discussed elsewhere on PF about Bell without locality assumption which is not far from proving that realism is the only issue since an hypothesis whose negation yields super-luminal info transmission when restricted to observed quantities replaces locality to get one Bell Theorem.

I’m afraid this is just more personal speculations. We have physical experiments and rigorous QM predictions saying the same thing, and you are using Occam's razor to "prove" that it’s false??

I don’t get this? Let’s say you are right and locality=true/realism=false. How "spooky" is that?? Well, your body and brain and thoughts do not exist at the most fundamental level. It’s all a "spooky holography projection" on a "screen" that does not exist... And WHO is running the "projector"!?!?

This looks very spooky to me...?:bugeye:?

http://upload.wikimedia.org/wikipedia/commons/thumb/8/84/Hologrammit.jpg/450px-Hologrammit.jpg

I don’t think Occam's razor can save us in this case...

I’m also afraid you have missed some very fundamental facts regarding EPR-Bell experiments:
"since an hypothesis whose negation yields super-luminal info transmission"

There is NO super-luminal info transmission in EPR-Bell experiments. We all know that this is impossible, it would create completely crazy paradoxes of Causality, i.e. first you get a terrible headache and then you see the stone hitting your head.
EPR-Bell action at a distance <> super-luminal info transmission

Saying YES is wrong here: we could say; the YES has not yet been ruled out but standard practice of physics lead to consider that the correct answer is "NO until otherwise proven", of something of that kind.

The problem with this reasoning is that to be rational you must also say NO to realism=false "until otherwise proven", and then you end up with something that Bell' Theorem and QM has proven wrong. One or both must be false, that’s a fact: Local Hidden Variable Theory (LHVT) is as dead as the Norwegian Blue Parrot (http://www.physicsforums.com/showpost.php?p=2709354&postcount=241). :smile:

charlylebeaugosse

Aug25-10, 10:00 AM

I’m afraid this is just more personal speculations. We have physical experiments and rigorous QM predictions saying the same thing, and you are using Occam's razor to "prove" that it’s false?

I don’t get this? Let’s say you are right and locality=true/realism=false. How "spooky" is that?? Well, your body and brain and thoughts do not exist at the most fundamental level. It’s all a "spooky holography projection" on a "screen" that does not exist... And WHO is running the "projector"!?!?

This looks very spooky to me...?:bugeye:?

http://upload.wikimedia.org/wikipedia/commons/thumb/8/84/Hologrammit.jpg/450px-Hologrammit.jpg

I don’t think Occam's razor can save us in this case...

I’m also afraid you have missed some very fundamental facts regarding EPR-Bell experiments:
"since an hypothesis whose negation yields super-luminal info transmission"

There is NO super-luminal info transmission in EPR-Bell experiments. We all know that this is impossible, it would create completely crazy paradoxes of Causality, i.e. first you get a terrible headache and then you see the stone hitting your head.
EPR-Bell action at a distance <> super-luminal info transmission

The problem with this reasoning is that to be rational you must also say NO to realism=false "until otherwise proven", and then you end up with something that Bell' Theorem and QM has proven wrong. One or both must be false, that’s a fact: Local Hidden Variable Theory (LHVT) is as dead as the Norwegian Blue Parrot (http://www.physicsforums.com/showpost.php?p=2709354&postcount=241). :smile:

Preamble in the for of an Apology. There is a misquotation and use of ridicule about non-realism in the post to which I respond (and a logical chain at the end that I cannot make sense of): this cannot be answered shortly (even if I do not respond to what I did not understand) . A "devilish" accumulation of malpractices in science. ? DevilsAvocado had (mostly at least) given me quite another image so far (so that perhaps my bad English only is to blame).

Misquotation: when I write "an hypothesis whose neegation...." I do not imply that non-locality implies Super Luminal Transmition (SLT): as you I know that it has been proven over and over again that non-locality does not imply SLT. People who want to explore what I mean can learn about the so called Effect After Cause Principle, an hypothesis that can be used to prove a Bell Theorem, in another thread about a Bell Theorem without locality assumption. I did mention that thread and did ever tell that non-locality implies SLT.

Now more serious stories (although misquotation is quite serious and is pervasive in the scientific literature around Bell's theorem"): of course lack of realism looks spooky, but lack of realism is "only" about "observables used both in macroscopic physics and to qualify particle by measurement".
Thus: Lack of realism does not mean limbo. Now Bernhardt Riemann in his thesis defended under Gauss, already noticed that it was quite possible that geometry does not make PHYSICAL sense at microscopic scale. Physics is a science, hence an experimental science. So lets us try to give experimental meaning to geometry at small scale. Most people expect problems at Plank scale, but the smallest clock with functions needed to develop relativity (even Special) is much larger than an atom, even if atoms are used in atomic clocks: a nice question here is "What is the smallest size of such a clock?". Same for the smallest tool to measure distances. Small distances and small times can be measured by interferometry, but the tools to do that are huge.
Now, notice that Copenhagen forbids us from trying other QM-compatible coordinates ( QM-compatible meaning in particular "that would be unable to produce a Bell Theorem" since "these coordinates would not allow to give simultaneous meaning to conjugate usual observables"). This type of QM-compatible, hence Bell-incompatible HVs are the things Shrödinger and Einstein were hopping for (which explains why Einstein was making fun of dBB realist theories, qualifying them as "too naive"). The existence of such QM-compatible HVs, as well as how to build on such ideas has eluded everyone so far and the extra dimensions of super-strings are probably not it (and again, perhaps this was all dreams of these two masters, and perhaps super-string will one day dispense us of trying that old idea). Anyway, Copenhagen was acting more like a church than a scientific center in this matter, with all due respect to its main priests.
- ANYWAY, non-realism (defended by Copenhagen in an unambiguous way, and in a way independent of the religious aspect around that which can be seen, e.g., the Heisenberg book on philosophy of physics) is not synonymous of reality depending on someone looking at it: it is only about observables.
- ANYWAY, we know that the UP already put severe limitation on the number of observable that make sense at once. If you feel comfortable with only momentum or position having a precise value at best, it does not seem such a big deal. After all, if particle P is in the superposition of two eigenvectors, say p1 and p2, what is the value of that observable for P just before measurement is made? Do YOU think that this observable make sense then?
That is not the way Bohr, Heisenberg, Dirac, Pauli, Born, Jordan,.... and even Einstein (after 1930 at least) would have seen physics but they might have been wrong. Yet except perhaps for CQT (Griffith, Omnes, Gell-Mann, Hartle), there is no much way in QM to give meaning to values of observable. Of course some invoke dBB but violates so much Lorentz invariance that I do not understand why some say that it is still part of physics (instead of being only a tiny part of its history).

At last, the experiment that proves...: those experiments (at least teh form used by Aspect et al. and repeated by Gisin and others) show "only" that a relatively simple correlation property predicted by QM holds true. This has consequences on 3 hypotheses taken together (and not two as in the theory that does not need "fair sampling"): more precisely we know that realism+locality+ fair sampling is false since (big surprise??) QM is once more right. Now since there is serious reasons to not believe in the type of realism needed in this conjunction of three hypothesis, Occam's razor (which has shaped ALL sciences as we know them by forcing the simplest explanation out of two that cannot be distinguished by experiments nor by otherwise decidable direct conclusions and logical consequences and theories built upon these two hypothesis) tells us tells us that unless there are good reasons to do otherwise, we should stick to the simpler view and consider like almost all the creators of QM (except for dB, who by the way almost destroyed French Physics, but this is another story) that it is realism that is the problem (so that there is no point in consider other hypotheses).

Now the camp telling otherwise (i.e., that we are in a non local world) has done repeatedly
misquotations and use of bad faith to defend its positions. For instance, trying for some, to forbid invoking conservation laws to (simply) explain (as: conservation +Malus law) what is going on in the correlation between two entangled particles. Or like in the post to which I respond, trying to say that we have a theory +experiments to support the views opposed to mine.

Now coming back to: "Is action at a distance possible as envisaged by the EPR Paradox."
1) The EPR paradox precisely rejected the possibility of action at a distance.
2) The action at a distance if any would be of a type that does not permit to transmit information faster than the speed of light, and the same applies of course to matter (even in energy form).
3) Many misquotation have invaded this part of physics where many actors are of bad faith or lack professional rigor by committing a huge number of:
- Wrong citations,
- Misquotations,
- Telling of imaginary histories, e.g., of who did what or who said what.
This explains why a question like "Is action at a distance possible as envisaged by the EPR Paradox." can be asked (in good faith I am sure) while the authors of the EPR Paradox precisely "envisaged" action at a distance to tell that it was impossible.

For instance, many heroes of the school defending non-locality (and I care here only about people who have done excellent physics indeed) have written that the word "Paradox" was attached to the EPR story (in the paper form, or the quote different form used by Einstein, but most people do not make this important distinction) by physicists that saw something wrong with that paper or more generally by what was related to it. In fact Einstein had a preliminary version of all that as far back at least as 1933 (in a form very close indeed from the way he described the issue himself (remember: the EPR paper was written by Podolsky and was not agreed to by Einstein, as explained by Jammer and Fine for instance)).

According to Rosenfeld's recollection, when in 1933 Einstein spoke about that to Rosenfeld, a very close close collaborator of Bohr, he used the word paradox. He did the same in writing many time starting at least in 1935 when discussing the matter by letters exchanged with Schrödinger.

charlylebeaugosse

Aug25-10, 10:26 AM

Originally Posted by DevilsAvocado (1451)
"that’s a fact: Local Hidden Variable Theory (LHVT) is as dead as the Norwegian Blue Parrot. "

False: this only applies to the type of local hidden variables used by Bell, which are not compatible with HVs. Other local HVs might only predict at most one of a pair of conjugate variables. In tehcase of teh EPR-Bohm setting, only one spin projection per particle could be given meaning, so two spin projections for an EPRB pair in the singlet state, not enough to get a Bell inequality that would be of any use, not enough thus to be ruled out that way. As Einstein said after 1930, the UP is here to stay (otherwise, he would not have used his influence to get the Nobel price to Heisenberg rather than to Schrödinger, I presume: in fact I am not sure of this causla relation and would like to know better) any way, the UP is here to stay, so other variables (HV in the sense that we do not know what they are, but also probably because only theory can be made with them, theories that would then be judged by prediction about the variables that we can have access to) can only respect the UP and should not give meaning to many spin projections at once.

I do not know if such local HVs exist and can be hopped for: certainly the ban on looking for them enunciated by the Copenhagen school did not help. Dirac besides Einstein and Schödinger believed that there were such variables have i read recently (can someone validate that position of Dirac or its negation: for the two others, see Fine's book and references therein). Now, I have paid a high price in the beginning of both of my careers as physicist and mathematician that opinions of world expert are worse nothing much: they know what they know and their beliefs are just beliefs. Even if a pool among physicist would indicate a direction we would not know: such variables need to be proven to not exist (like the local dBB-Bell HVs are using Bell's Theorem) or one has to build a theory and make a non-trivial falsifiable prediction. Perhaps we need to make the thery relativistic before we get the right setting and trying to start from QM is almost as bad as trying to start from Classical Mechanics,... who knows? But one thing is sure: Local HVs have not been proven to not exist. It is Local and non QM-compatible HVs that are ruled out by Bell + verification of the twisted Malus law for singlets. Sorry DevilsAdocado (But you have taken me also in positions where I wrote more extreme conclusions than I wanted to.. and I do not mean in my previous post, nor in the present one).

DrChinese

Aug25-10, 10:56 AM

DevilsAvocado

Aug25-10, 11:34 AM

Misquotation: when I write "an hypothesis whose neegation...." I do not imply that non-locality implies Super Luminal Transmition (SLT):

I’m terribly sorry for "misquoting" you, I copied the text and then... well, I don’t know what happened...

But, could you please tell me exactly what you mean (instead of telling me what you don’t mean)?
We have to be extra cautious: in similar circumstance, when a viewpoint is odd cannot be falsified, one gets rid of it by using Occam's razor, AND here we also have the work of Leggett and a (couple of) paper(s) discussed elsewhere on PF about Bell without locality assumption which is not far from proving that realism is the only issue since an hypothesis whose negation yields super-luminal info transmission when restricted to observed quantities replaces locality to get one Bell Theorem.

I interpret this as the negation of locality (non-locality) yields super-luminal info transmission, and I think I’m not alone...

But one thing is sure: Local HVs have not been proven to not exist. It is Local and non QM-compatible HVs that are ruled out by Bell + verification of the twisted Malus law for singlets. Sorry DevilsAdocado (But you have taken me also in positions where I wrote more extreme conclusions than I wanted to.. and I do not mean in my previous post, nor in the present one).

Don’t be sorry. I think it’s pretty obvious that you have a very personal version of science and EPR-Bell... You say you are a professional scientist, but honestly, I don’t know what to think...

Could you please, in simple English, without long historical anecdotes from the 1930s, tell me exactly what you mean by this?
Local HVs have not been proven to not exist. It is Local and non QM-compatible HVs that are ruled out by Bell

What is "Local and non QM-compatible HVs" and in what way are they different from "Local HVs"??

verification of the twisted Malus law for singlets.

What on earth is "the twisted Malus law for singlets"?? Please, explain in simple English, without historical anecdotes.

charlylebeaugosse

Aug25-10, 11:46 AM

charlylebeaugosse

Aug25-10, 11:54 AM

What on earth is "the twisted Malus law for singlets"?? Please, explain in simple English, without historical anecdotes.

Sorry for the shortcut: singlets was short for EPRB pair in a singlet state.

Now for such a pair (say (e,p)), there is conservation of total projection of the spin on any axis. If s is measured on particle e, say, then -s will always measured on particle e on the same axis, so that, by conservation, measuring on one particle essentially prepares the other particles along the symmetric state. Now apply Malus law to the second particle, you get minus the usual Malus law (<s1,s2>=cos(axis for s1, axis for s2) ), the minus sign being the reason to call the composition of conservation and Malus law "Twisted Malus Law", I presume.

DrChinese

Aug25-10, 11:54 AM

What is "Local and non QM-compatible HVs" and in what way are they different from "Local HVs"??

This is technically accurate but somewhat confusing. You could put forth a LHV theory which does not match the predictions of QM. Of course, those can usually be dispatched quickly on the basis of their disagreement with experiment. The De Raedt model is such an example, although I don't consider it an actual theory.

nismaratwork

Aug25-10, 11:57 AM

charlylebeaugosse

Aug25-10, 12:03 PM

This is technically accurate but somewhat confusing. You could put forth a LHV theory which does not match the predictions of QM. Of course, those can usually be dispatched quickly on the basis of their disagreement with experiment. The De Raedt model is such an example, although I don't consider it an actual theory.

Notice that the HVs of Bell are not compatible with QM in the sense that several conjugate observable make sense at once. While this is only impossible by the spirit of the usual UP, it is actually impossible from another piece of QM, i.e., the time -reversed UP of Einstein, Tolman and Podolsky. Which is why several people are not very impressed by Bell's theory: it has an hypothesis that was already weak in 1964 (indeed in 1931). Unfortunately, the ETP which made initially a big impact is now vastly not known about by most people. Of course, the issue is that the front of QM is busy with superstrings, Higgs boson, etc. while back then, the foundation and front of science were at the same place.
Q-Information and Q-computation may change that, but Information is perhaps too simple while computation is perhaps too hard.... Lets wait and see as speculation would not help much, except perhaps in helping young fellows in choosing their path.

charlylebeaugosse

Aug25-10, 12:34 PM

Don’t be sorry. I think it’s pretty obvious that you have a very personal version of science and EPR-Bell... You say you are a professional scientist, but honestly, I don’t know what to think...

This was not about science in general but about logic: the hypotheses of Bell involve not only that observable value pre-exit measurement but also that they pre-exist (or at least co-exist) the measurement of other quantities (or read the paper again). Now, while pre-existence of one observable to its own measurement shocks the opinion of the founding fathers of QM (except for deBroglie), the other form, that is what is needed to have a Bell Theorem, i.e., that co-exist the measurement of other quantities is in direct conflict with the time -reversed UP of Einstein, Tolman, and Podolsky (that someone has posted recently I think, or let m know if you need it). Thus it is not a matter of opinion, but of logic: if the hypotheses of Bell1964 violate QM, a form of HVs that would not produce such violation is NOT ruled out by Bell's Theorem +Aspect (and in fact as you know, one needs teh CHSH form and a fair sampling hypothesis). Now, this does not mean that such a HV theory can be built.

Personally, I have a view like in Plato's myth of the cavern, but who cares as long as I cannot make it of any use.

Now, having personal views on science is (almost) the only way to avance science by non-trivial moves (and the same applies to math), no? And I will not get into a fight (on who has the longest... list of often cited publications) since you seem to often have a point, and I mostly approve of your posts, whether or not you are a professional (and after all, Fermat was not), and our respective ages may be unfairly in my advantage. Just, please, recognize that originality is not a plague for scientists, professional or not.

RUTA

Aug25-10, 04:17 PM

See the comments of of Pauli and Einstein on deB-B theory.

I've read a few books on the historical development of quantum physics and I enjoyed reading them, but I'm not asking what the founding fathers thought in this case. Einstein was dead before Bell's inequality and the numerous experiments in accord with variations thereof. I was asking whether you knew of someone who had actually proven that non-locality was not the culprit. Or, less rigorously, perhaps some papers presenting credible arguments for locality over separability. I've talked to Don Howard and read some of his work and he's in our camp, but he doesn't have any "arguments" per se against non-locality. His position is more like Relational Blockworld in that it simply favors nonseparability.

Anyway, why spend time on a theory so violently incompatible with Lorentz invariance, beside the attacks of Wolfgang P.

SR got me to major in physics and I did my PhD in GR, so Relational Blockworld is local and nonseparable. You're preaching to the choir here :smile:

But, I'd say dBB is the second most popular QM interpretation (behind MW), so anyone presenting a credible argument against non-locality would definitely get the attention of the foundations community.

Many false theories are around, such as many version of Kaluza-Klein, Weyl, variations on super-strings: at least with those progress in math have been made. In fact, Wigner would have said (and he did, but in more general form covering all HV theories satisfying the hypothesis of Bell1964) that "Bell's Theorem is the nicest proof that HVs are false". Non-locality is not physics and cannot lead to any observation that is not a consequence of an a-priori stand on pre-existence of observable values to measurement. The fact that there is a club making themselves happy with dBB makes not dBB part of physics. There are such clubs in most disciplines. The problem is that more and more crazy viewpoints of QM (many words, many minds, many schmucks, etc...) are winning more and more support. Science is in danger when the most central piece of the most central discipline is under serious attack and the evil forces of magic and fantasy become the ruling (compare the extent of Bell theory vs elementary particles or thermodynamics on the www: see how many tenors of physics claim that actions can be taken upon the past). It is true that the Copenhagen team opened the doors to the flood by allowing religious stands where perpetual re-examination and progress should be the way to go. The interpretation by Wheeler of delayed measurement was the door open to violation of the time arrow at macroscopic scale. But the errors of the past should not excuse new errors but should rather make us more cautious. What would have happened to math if seeing mistakes in rigor by the old masted would have been an excuse for more lack of rigor instead of devising methods and language to allow modern analysis and its various applications? Math would be dead by now and physics is certainly in grave danger: it may soon come under control of engineering if we accept non-sense such as dBB as something else than anecdotes on what physics could have looked like.

Maybe you should write a formal argument against non-locality, present it in the appropriate venues and get it published. I'll be glad to read it and offer comments before you submit.

DevilsAvocado

Aug25-10, 07:51 PM

DEVILSAVOCADO
"I interpret this as the negation of locality (non-locality) yields super-luminal info transmission, and I think I’m not alone..."

NO: the meaning is that the new hypothesis (called EACP= Effect After Cause Principle) is weaker than locality since:

Non(Locality) =/=> SLT
while
Non(EACP restricted to observed quantities) ==>SLT

This is what I call "A Personal Version of Science"

You don’t have to be a genius to check these things. If I Google "Effect After Cause Principle" I get 10 results, where one is this thread, and one is a double, giving a total of 8 unique results. The actual arXiv paper was submitted on 1 Aug 2006 – "A Bell Theorem with no locality assumption".

Now, you are telling me that Charles Tresser has found the solution to the paradox that Einstein & Bohr argued about for 20 years, followed by +40 years of intensive research and attention among the brightest minds in the scientific community – AND THE BIG SOLUTION TO ALL THIS GIVES 8 RESULTS ON GOOGLE, 4 YEARS AFTER THE "DISCOVERY" !:eek:? !:eek:?

Do you really want me to believe in this???????????????

It doesn’t make sense, does it?

This is what I call "A Personal Version of Science"

This thread has been more or less terrorized by dishonest and cranky troglodytes, that will say and do absolutely anything to get as far as possible from what Physics Forums Global Guidelines characterize as current professional mainstream science, and after 4 months of this, I’m not sure if I can handle a new case of anti-intellectual smokescreens.

First you say:Altogether one needs to be very precise
And then you say:the minus sign being the reason to call the composition of conservation and Malus law "Twisted Malus Law", I presume.

And I presume that this is your own little "homemade expression", right?
And I presume you know that "Twisted" has several meanings, right?
to combine, as two or more strands or threads, by winding together; intertwine.

to distort the meaning or form of; pervert: He twisted my comment about to suit his own purpose.

Personally, I think that the later fits your homemade "Twisted Malus Law" perfectly.

To me this kind of "argumentation" is just ridiculous and unprofessional, but there are many anonymous readers who will misinterpret your "clever ambiguity", and that is bad, real bad.

This is what I call "A Personal Version of Science"

RUTA is a real scientist. He says CLEARLY what he has learned is true and does not hide stupid agendas behind ambiguous games of words:
obscure publication of Bell
- I hate "your" statement about "Einstein's name was on the 1935 paper"

This last quote makes me laugh. This idea that you and Charles Tresser promote, that Einstein disliked the EPR paper, and he was "kidnapped" by Podolsky to put his name on a paper that he did not believed in??

How likely is this?? And why didn’t Einstein publish a refuting paper??

The fairly unknown Podolsky used Albert Einstein as a "sidekick" for his own cranky personal ideas...?:bugeye:??:bugeye:?

This crazy conspiracy theory just doesn’t make sense, especially if you are claiming to be a serious and professional scientist.

Finally, please read the whole thread before reintroducing the "unfair sampling loophole", we have been over and over this subject several times, and anyone who claims any validity in this is not a part of current professional mainstream science:
Stanford Encyclopedia of Philosophy – Bell's Theorem (http://plato.stanford.edu/entries/bell-theorem/)
...
In the face of the spectacular experimental achievement of Weihs et al. and the anticipated result of the experiment of Fry and Walther there is little that a determined advocate of local realistic theories can say except that, despite the spacelike separation of the analysis-detection events involving particles 1 and 2, the backward light-cones of these two events overlap, and it is conceivable that some controlling factor in the overlap region is responsible for a conspiracy affecting their outcomes. There is so little physical detail in this supposition that a discussion of it is best delayed until a methodological discussion in Section 7.

Personally, I don’t think that non-locality is "the biggest threat" against physics - I think dishonest cranks with a "dogmatic-religious" approach is a much bigger threat than anything in nature can ever be.

ThomasT

Aug25-10, 09:03 PM

I'm probably misunderstanding you, but you can correct me if that's the case. When you say "the existence of a deep reality" I picture "microscopic" or "hidden" entities at work among, and distinct from, the elements of the experimental equipment.Yes, that's what I'm picturing. But only for the purpose of the conjecture I was making regarding how the OP's question might be answered. I'm not saying that that is a candidate for a true picture of reality. I'm not saying that that's the best metaphysical picture of reality that can be conjured. I'm not saying that picturing things that way is the best way to approach formulating a viable interpretation of qm (your RBW way is obviously better in that respect). And, I myself don't actually picture reality in such a 'separable' way. (How I 'picture' it is much too abstract and, well, fuzzy to be of any use theoretically. It's a picture of an unresolvable chaotic cacaphony of simple and complex waveforms in a hierarchy of 3 dimensionally interspersed particulate media all, ultimately, governed by a single fundamental wave dynamic and built, ultimately, from wavelike disturbances in a fundamental structureless, ie. nonparticulate, medium. In this, overall, view the moon really isn't there. We aren't really there. There are no 'physical objects' per se. We are we and the moon is the moon and ponderable objects are ponderable objects because of the resonant properties that characterize us and the moon and any complex bounded, and more or less persistent, wave structures that constitute our continually moving, and evolving, universe. This is a wholistic and nonseparable view of reality, though I'm not sure it accords with your specific RBW view because it's also, necessarily, a dynamical view -- ie. the universal configuration is in a constant state of flux, the universal configuration that characterized 'yesterday' no longer exists, ie. it really no longer exists.)

Anyway wrt the OP's question, we assume that emitters are emitting submicroscopic or hidden wavelike disturbances in some unknown medium, some medium of unknown structure. The emissions might even be particles in the sense of bounded, and at least somewhat persistent, complex waveforms. Like, say, the light (photons) that is being emitted, analyzed and detected in optical Bell tests (or any quantum optical tests for that matter -- but optical Bell tests are particularly relevant wrt to considerations of the OP's question, even if Bell's theorem might not be). For our purposes here, I'm calling some picture, any picture, of 'something' propagating from emitter to filter to detector the 'deep reality' that exists whether we probe it with filters and detectors or not.

I stated that the existence or nonexistence of a deep reality can't be proven. It can only be inferred (or not, as one might choose) from instrumental behavior. I also stated that the assumption of the existence of a deep reality seems to me to be an essential part of fundamental physics. That is, quantum physics seems to be grounded on the assumption, based on inferences from observations of instrumental behavior, that such a deep reality exists. So I asked if the various possible answers to the OP's question are equally tenable, and answered that I don't think they are because of inferences by mainstream physicists regarding the existence, and certain characteristics, of a deep reality based on quantum experimental phenomena which have become an integral part of the development of qm and the standard model.

In other words, regardless of Zeilinger's, or whoever's, momentary expression of things, it seems to me that the mainstream development of fundamental physics is based on the assumption that there is something real with real and persistent properties that's produced via emission processes and that is moving from emitter to filter, then interacting with the filter, then moving from the filter to the detector and interacting with the detector.

And the contention is that if this assumption accords with reality (and of course we have no way of knowing, definitively, if this accords with reality), then EPR-type action at a distance has to be ruled out, because EPR-type action at a distance says that the deep reality of particle B is dependent on the macroscopically recorded reality of particle A, and vice versa.

In any case, EPR-type action at a distance is, prima facie, paradoxical and nonsensical -- so, EPR rightly dismissed it, even if not for precisely that reason, as not worthy of consideration.

So, I tentatively (pending you or someone else pointing out mistakes in how I'm thinking about this) conclude that EPR-type action at a distance isn't possible given the observations and inferences of modern physics, and some simple (maybe too simple?) logic.

By the way, can I look at certain parts (the parts that might be at odds with my own 'realistic' view of things) of your RBW construction as just necessary mathematical conveniences? I really am beginning to understand, and like, your approach and rationale, even if I still don't understand some parts of your construction.

Continuing with the main theme (is there a main theme?) of this thread, I stated:

We can assume that emitters don't emit anything, filters don't filter anything, and detectors don't detect anything -- ie., that there's no deep reality that's ultimately affecting and determining instrumental results. In which case, EPR-type action at a distance would be necessary, and the answer to the OP's question would be yes.Wrt which, given my 'definition' of EPR-type action at a distance above, this statement of mine doesn't seem to make much sense now. I'm learning, refining, thinking a little and modifying my view as I go. It's quite possible that I'll adopt an entirely different way of looking at things in the next few pages (I sense that this thread is far from over.). I hope that you don't find that too annoying.

In any case, given the first part (the assumption, not the conclusion) of my last quote-shaded statement, then this would seem to entail some sort of action at a distance, even if not, strictly speaking, the EPR-type.

To which you replied:

In RBW, there are no "microscopic" or "hidden" entities at work among, and distinct from, the elements of the experimental equipment, but there is no action at a distance either.To which my initial response was "how can that be"?.

And then I read your next statement:

That's because it's not a dynamical ontology, i.e., explanation isn't based on cause and effect, but on a nonseparable "4Dism."And then I could only say, "oh, ok then" -- still (while liking it's rhetorical possibilities, and beginning to vaguely appreciate it's theoretical necessariness) not fully understanding how your "nonseparable 4Dism" can be nondynamical or adynamical while my pedestrian "nonseparable 3Dism" plus time/change = "nonseparable 4Dism" seems, to me to be, so necessarily dynamical. And then it hit me. While I'm simply musing about 'fundamental reality' based on some possibly quite 'loose' associations, you and your associate authors of RBW have actually constructed a viable physical theory/interpretation.

Until I fully understand and appreciate RBW, and maybe even after, can I think of RBW as being essentially an instrumentalist approach?

If so, and not to put you on the spot (as if I could), then what about the notion that standard qm (the bare formalism with the basic probabilistic interpretation) is already essentially an instrumentalist approach?

Ok, I do think that you've added some illuminating and constructive stuff. Your rationale and conceptual approach is somewhat compelling. So, have I answered that particular question adequately, or might you add something to aid my, and others, understanding?

And, if not, then nevermind, and any elaboration you might offer is appreciated.

Are we getting away from the OP theme? Does it matter?

Are you saying that the acceptance of your interpretation by the foundations communitiy is based on a generally held assumption that instrumental behavior is not determined by the existence and behavior of a reality deeper than the instrumental level?

The acceptance is based simply on its logical possibility (as shown by relevant calculations).Ok, so at some point your conceptual approach sort of segues into the probability calculus of standard qm? Even so, a consistent 'conceptual' approach and rationale would seem to be an advance. Would you say that RBW in some sense, in any sense, reconciles GR with QM?

Are you and your group planning or now working on any revisions?

Do they subscribe to it? No, by and large they hate it.I think you're just being modest. Didn't Bub like it? Or, did he just offer that eventually, after several epiphanies, he understood it -- not that he actually liked it?

The short answer is also "no", depending on what's inferred/assumed. Of course, the most sensible answer is "we don't know", which we might express as a "definite maybe" regarding the possible answers to the OP's question.

Perhaps we have different interpretations of the OP question. I read it, "Is non-locality possible given EPR phenomena?"Perhaps. I read it as the OP wrote it. "Is action at a distance possible as envisaged by the EPR paradox?" Which might be condensed to, "Is EPR-type action at a distance possible?". Which then requires that we define EPR-type action at a distance. And when we do that we find that it's different than other types of action at a distance. Specifically, it requires that the deep reality of a particle (or wave or whatever), b, assumed to be incident on a filter or detector, B, is dependent on an instrumental event, A, spacelike separated from the predicted instrumental events at B. And when we consider that the deep reality of, a, assumed to be incident on a filter or detector, A, is also dependent on an instrumental event, B, then we have a bit of a problem. Or do we? I don't really know. Help?

Since it is generally agreed that EPR-Bell phenomena imply non-locality and/or nonseparability, the short answer is "yes, non-locality is a possibility."But, what sort of nonlocality? Given the inability to describe the entanglement correlations in a detailed local realistic way, there are at least two different sorts of nonlocality that we can consider to, at least quantitatively, account for the observed results. If EPR-type nonlocality is ruled out, then the answer to the OP's question is no.

I've sure had a lot of fun with this thread!I'm glad you have that attitude. It's certainly appreciated that a physicist such as yourself is willing to take the time to answer questions from people like me who are not even remotely as knowledgeable as you, but are nonetheless fascinated by this stuff. Of course, that's part of what PF is all about. And also of course, I'll bet that you would really like it if some heavyweight bona fide working physicists would come down from their self-erected, but nonetheless justified, thrones for a time and make some comments about your interpretation/theory. Or are they already doing that in another, more technically oriented, thread (most of the comments within which I probably, at this time, would, generally, not understand)?

charlylebeaugosse

Aug25-10, 10:31 PM

This is what I call "A Personal Version of Science"

You don’t have to be a genius to check these things. If I Google "Effect After Cause Principle" I get 10 results, where one is this thread, and one is a double, giving a total of 8 unique results. The actual arXiv paper was submitted on 1 Aug 2006 – "A Bell Theorem with no locality assumption".

Now, you are telling me that Charles Tresser has found the solution to the paradox that Einstein & Bohr argued about for 20 years, followed by +40 years of intensive research and attention among the brightest minds in the scientific community – AND THE BIG SOLUTION TO ALL THIS GIVES 8 RESULTS ON GOOGLE, 4 YEARS AFTER THE "DISCOVERY" !:eek:? !:eek:?

Do you really want me to believe in this???????????????

It doesn’t make sense, does it?

This is what I call "A Personal Version of Science"

This thread has been more or less terrorized by dishonest and cranky troglodytes, that will say and do absolutely anything to get as far as possible from what Physics Forums Global Guidelines characterize as current professional mainstream science, and after 4 months of this, I’m not sure if I can handle a new case of anti-intellectual smokescreens.

First you say:
And then you say:

And I presume that this is your own little "homemade expression", right?
And I presume you know that "Twisted" has several meanings, right?
to combine, as two or more strands or threads, by winding together; intertwine.

to distort the meaning or form of; pervert: He twisted my comment about to suit his own purpose.

Personally, I think that the later fits your homemade "Twisted Malus Law" perfectly.

To me this kind of "argumentation" is just ridiculous and unprofessional, but there are many anonymous readers who will misinterpret your "clever ambiguity", and that is bad, real bad.

This is what I call "A Personal Version of Science"

RUTA is a real scientist. He says CLEARLY what he has learned is true and does not hide stupid agendas behind ambiguous games of words:

This last quote makes me laugh. This idea that you and Charles Tresser promote, that Einstein disliked the EPR paper, and he was "kidnapped" by Podolsky to put his name on a paper that he did not believed in??

How likely is this?? And why didn’t Einstein publish a refuting paper??

The fairly unknown Podolsky used Albert Einstein as a "sidekick" for his own cranky personal ideas...?:bugeye:??:bugeye:?

This crazy conspiracy theory just doesn’t make sense, especially if you are claiming to be a serious and professional scientist.

Finally, please read the whole thread before reintroducing the "unfair sampling loophole", we have been over and over this subject several times, and anyone who claims any validity in this is not a part of current professional mainstream science:

Personally, I don’t think that non-locality is "the biggest threat" against physics - I think dishonest cranks with a "dogmatic-religious" approach is a much bigger threat than anything in nature can ever be.

Insults are cheap: read the historians such as Jammer and Fine instead of propaganda to the glory of the realist point of view: cite a serious historian who disagrees what I say about Einstein and the EPR paper, and notice that this historian would have to explain what kind of sickness hit Einstein to make him write to Schrodinger that Podolsky wrote the paper and that he was not happy. Fine explains why Einstein did not react. Did you know about the letter of Podolsky to the New York Time. Citing the Stanford dictionary will not help. Most of what is there but what is from Fine (and perhaps a few others) was written by tenors supporting Bell's ideas. But in good circles, one cites people and not encyclopedia (except to show what is in popular accounts). Again, find one historian who agrees with you and not with me. No need to comment your other comments before that.

Making fun of the truth is the first step toward totalitarian thinking.
CleBG

ThomasT

Aug25-10, 11:34 PM

JesseM, thanks for the reply, sorry for the delay in answering.
You seemed to be saying that since we don't know the exact details of the supposed "disturbances" we can't give an affirmative answer to the OPMy thinking is that if we assume any reality underlying instrumental behavior, then we can't give an affirmative answer to the OP.

Of course, we don't have to assume that. Maybe reality is just emitters and filters and detectors.

But in that case we still can't give an affirmative answer to the OP, because EPR-nonlocality entails that a detection event at A instantaneously determines the reality of an underlying disturbance, or particle, b, incident on B. The particle, b, simply didn't exist before the detection, A. And, of course, vice versa. Do you see the problem here, and how it relates my first statement above?

... if the "disturbances" are meant to be disturbances in local realistic variables, then hell yes it "makes sense to say that they don't exist", that's exactly what Bell's theorem proves!Ok, then maybe they don't exist. Maybe emitters and filters and detectors is it. But what about the 'light' in, say, optical Bell tests. Are emitters emitting it? Are filters filtering it? Are detectors detecting it?

What do we have in optical Bell tests? Initiate the emission process, then record individual detection events at A and individual detection events at B. Then turn off the emission process and combine the detection attributes at A and the detection attributes at B according to some criterion, usually time-stamping of the detection attributes. Low and behold, they're correlated, not just wrt the time-stamping but also wrt an optical law that says that the rate of coincidental detection will vary as the cos^2 of the angle between the crossed polarizers. But this can't be just optics. It must be due to instantaneous or at least ftl communication of some sort between the ... between what? ... who knows, it's like magic. Let's call it nonlocality, and deem it the new paradigm in physics.

Look, nonlocality, physical nonlocality, is never demonstrated. It isn't even inferred by violations of BIs, even given that the BIs might be endowed with some meaning relating to the deep nature of reality. It's simply, "we have no local mechanistic explanation for these correlations". That's it. So, we bestow upon them a nonmechanistic nonlocal 'explanation'. Which, of course, is no explanation at all. But then, it does simplify the 'physics', doesn't it?

'Nonlocality' as it relates to standard qm or dbb is simply a "formal" phenomenon.

Anyway, ok I'll stipulate that 'nonlocality' exists. Whatever you want 'nonlocality' to refer to, in some metaphysical 'picture' of reality. So what?

As I said in a previous post, the 'definitive' answer to the OP's question is that we have absolutely no way of knowing. On the other hand, the most sensible answer to the OP's question is, no, EPR-type nonlocality isn't possible given extant observations and what can be logically inferred from them.

ThomasT

Aug26-10, 12:04 AM

What are the references of the results of Bell that are quoted: this does not resemble what I know. If this has to do with Bell1964(Physics) , then please explain the relation between this work of Bell and the proposed interpretation.
Thanks,
CleBGHi Charley, I think there might have been a typo in there somewhere. Do you know what I mean?

By the way, welcome to the thread. I've enjoyed reading your stuff even though I must say that some of it confuses me, and some of it I have no idea what you're talking about. So, you should fit in quite well with the general tenor of the thread.

But of course, much of what you've written is quite understandable and informative. So thanks for the contributions.

charlylebeaugosse

Aug26-10, 12:05 AM

I gave an argument showing that the Bell+Aspect story disprove only local realism that would conflict the UP. Deviladvocado responds by personal attacks and judgment based on thin air, even making fun of history statements without giving references for the thesis he defends against me (who gave references, many times). Worse, he puts words in my mouth (and over again after mocking me by providing fake excuses), last time by insinuating that I was appealing to a "fair sampling loophole" while I only mentioned that, while Bell's Theorem only needs realism + locality (at least in original form), the relevance of Aspect experiment also requires fair sampling.

I have no idea of who is that person (who find him/her-self good enough to attribute stars and injures to people whose footprint on math and science he has no idea about, and whom I naively thought honest for a (short) while), but if he/she agrees to take, say DrC, or Ruta, or Thomas T, assuming one of them accepts, as a judge who would keep us anonymous and unknown from each other, I'd be happy to have such a (willing) judge comparing our respective scientific impacts. On the other hand, it is not me but Tresser who is attacked by Deviladvocado when he counts (as in the last post of him that I have seen) the impact of a paper by Tresser: Tresser's work has been cited in the description of the work of two people who got field medals, and has solved himself with others a long standing conjecture of Smale, and formulated conjectures that have animated many great scientists and mathematicians (answering himself to many questions and pointing out new ones). He has collaborated with John Milnor, proving a conjecture of Milnor (one of major mathematicians of the the 20th century and still alive) a conjecture that was a goal for many of the tenors of dynamics. He is or has been on several editorial boards, he has a total; of about 200 papers and granted US patents (with more in the pipeline). He has collaborated with about 80 people in science and mathematics (half of them chosen by their grate fame (Milnor, Sullivan, Bass, Libchaber, Procaccia, Coullet, Spiegel, Young, Adler, Shub, Pugh, Martens, Lanford, Misiurewicz, Mackay, Gambaudo, Iooss, Llibre, Kitchens Alseda, etc... the other chosen by their young age and lack of experience, to create a bridge between those and the former), and about the same number in technology. He has launched several sub-subjects of dynamics, both as a physicist and as a mathematician. This can be seen from the www and has more statistical value than the fact that ONE paper (that if true is quite original snd so much of a problem for he establishment) takes time to gain recognition. I know several people who were almost kicked out of science to see their work eventually recognized: none of them was close to be as known then (when they made their decisive contributions to science) as Tresser is known now. Since Tresser has also left a trail of modesty (before his leave for disability a few years ago), it is not surprising that a work of his, especially in a field new to him, takes time to attract attention. Popularity is not truth, and vice versa truth does not mean popularity. Originality is not a plague for scientists. Devilavocado has an attitude problem as he/she seems to equate reason and/or being right with the result of a popularity contest. Galois, Post are examples of fame that came too late and as great scientists are a bit artists, one can expect that such things happen rather often even for people not quiet as good as these two.

Making fun of truth is the type of attitude that has sent many people in my family to their death: you can make fun of friends or of yourself, not of people with whom you are in a conflict of ideas, or any other sort of conflict for that matter. If it is science, or the honesty that must go with it, that is sent to its death, it is also sad for the future of human kind. For instance, Devilavocado picks a sentence of mine about "an obscure paper of Bell" from a section where I was explaining that for some time the paper was obcure enough for Richard Friedberg to redo it all using EPR's elements of reality instead of predictive HVs.

What would be my IQ if I claimed that Bell 1964 is an obscure paper now, as the fragment of Deviladvocado suggests?

And is there anything more pathetic than counting by citations on the www what is the value of a scientific paper. Counting pages for a mature scientist has a meaning as a statistical tool, but for instance, I have had all my best papers rejected by journals accepting much lesser papers of mine, and I have a paper with little science in it that has hundreds of citations (an aspect of the statistical value only of brutal counting). Abramov, when received as member of the French Academy of Sciences, mentioned the counting habit and pointed out that his most cited paper had this status because it contained a mistake that was rediscovered by successive generations of young physicists very proud to make him wrong.

At last, Deviladvocado seems to imply that I should have read all the thread, but he attacks me on the fact that Einstein did not give his imprimatur to the EPR paper, subject on which I had recently responded to DrC with gory details and sources for my non-professional knowledge as I am not an historian (although anyone can check that in his most public accounts of the completeness issue, Einstein never used "elements of reality" and neither the complicated line of arguments that Podolsky used and that is described for instance by Fine (Jammer counted at least 3 people who studied the formal structure of the argument in the EPR paper, a practice rather rare in physics as Jammer pointed out).

I also mentioned to Devilavocado that I was waiting for reference to back his making fun of the knowledge I shared in this thread about Einstein and EPR: this part of the history of science is important (and the attitude of Devilavocado proves it) because of the number of people who use false info about Einstein to position themselves and their own work (and or opinions) in a way that may abuse people who think a priori that scientists are honest: we will see if he can back his mockeries by solid references. I have provided mine many time, and offered to post what I can access and that others want but cannot get.

charlylebeaugosse

Aug26-10, 12:10 AM

Hi Charley, I think there might have been a typo in there somewhere. Do you know what I mean?

By the way, welcome to the thread. I've enjoyed reading your stuff even though I must say that some of it confuses me, and some of it I have no idea what you're talking about. So, you should fit in quite well with the general tenor of the thread.

But of course, much of what you've written is quite understandable and informative. So thanks for the contributions.

Thanks: if I am not clear enough, let me know. When on speaks about things one has thought a lot about, one has a tendency to use jargon (words and/or sentences or pieces of them). Now if I contribute, I expect to be understandable but make it my responsibility if I am not: please do not hesitate to ask for clarification, references, details, etc... For references, I'll do what I can, for the rest, no excuse if I cannot explain so that many if not all can understand clearly.

charlylebeaugosse

Aug26-10, 12:31 AM

I've read a few books on the historical development of quantum physics and I enjoyed reading them, but I'm not asking what the founding fathers thought in this case. Einstein was dead before Bell's inequality and the numerous experiments in accord with variations thereof. I was asking whether you knew of someone who had actually proven that non-locality was not the culprit. Or, less rigorously, perhaps some papers presenting credible arguments for locality over separability. I've talked to Don Howard and read some of his work and he's in our camp, but he doesn't have any "arguments" per se against non-locality. His position is more like Relational Blockworld in that it simply favors nonseparability.

SR got me to major in physics and I did my PhD in GR, so Relational Blockworld is local and nonseparable. You're preaching to the choir here :smile:

But, I'd say dBB is the second most popular QM interpretation (behind MW), so anyone presenting a credible argument against non-locality would definitely get the attention of the foundations community.

Maybe you should write a formal argument against non-locality, present it in the appropriate venues and get it published. I'll be glad to read it and offer comments before you submit.

I have nothing ready yet, a lot in preparation (but I am looking for collaborators as I always hatted to work alone and have kept projects for years before closing them, sometimes alone when at the end, I still could not find one or more partners). Meanwhile, I have proposed to DrC to initiate a thread on Bell's Theorem without locality, about 2 papers from the same author, one in preprint form I must say, that I have posted and where arguments are made against non-locality (but no claim of a decisive blow is made there, a definite blow (or many of them) being what I hope myself to do... soon enough I hope). DrC has kindly opened that Thread (I am still new and did not know where to find instructions to do that). Your opinion on those papers would be most appreciated. You seem to know a lot about the philosophy of the foundation of QM, something which is my own weakest point probably: I would really love to have your assessment of that pair of papers by Tresser. I have begun to read some of your posts and they are quite substantial in content: is there a way to have a global view on them? (perhaps if I go to you page I can follow the patrh of what you wrote.... I'll let you know if I need help). With the trauma of Devilavocado attacks on me, I will need to get back to other science work and leave the pleasure of PF for later, but as soon as I have time, I'll go to your material: what is the firat post of yours? do you remember???

ThomasT

Aug26-10, 12:52 AM

I think ThomasT has mixed up Counterfactual Definiteness (CFD) with Counterfactual Conditional ... It's certainly possible DA, especially since I have no idea what any of that means.

Perhaps counterdefinite factualness might be a more appropriate designation of the general tone of my replies. And then again, perhaps not!!

In any case, I shall now seek out and reply to any and all of your replies to me that I might reply to.

Ah, I've found one that I don't think I've replied to yet.

I could be wrong, but I thought that OP wanted us to describe the state of current professional mainstream science – not personal guessing... I could be wrong too, but my impression was that the OP wanted us to do a lot of personal guessing. In any case, I think he(she?) has gotten much more than he(she?) probably predicted. By the way, have we heard from the OP in, say, the last month or so? Does it matter?

And yet another!

Great TT! I’m with you all the way on this!Ah, the "we don't know" thing. Well of course. Everyone likes this. Have some fritos. Pass the beer. But don't get too comfortable. I'm not done looking yet.

Here's another (not in a reply to me):

Then I don’t think it’s unfair to say: YES - action at a distance is a possibility, until we know better.I do agree, sort of. But look, we're never going to "know better". The point is that it's really just a matter of taste. We can posit the existence of nonlocality or not. It really doesn't matter wrt physical theories. Or maybe it does. I have no idea.

Well, that wasn't so bad was it? Let me know if I missed anything DA.

And spank you very much Helpy Helperton.

ThomasT

Aug26-10, 01:15 AM

Clearly, we know from Bell that there cannot be "predetermined" hidden variables outside of what can be observed.Really? How do we know that? What does a detection attribute associated with a unit vector tell you?

Now, before you rip me to shreds on this I want you to bear in mind that I've consumed LOTS of popcorn (and, oh yeah, a few beers).

So, if you could send along some of your latest software with the imminent rebuttal it would be most appreciated, and would certainly ease the pain.

ThomasT

Aug26-10, 01:20 AM

nismaratwork

Aug26-10, 07:05 AM

ThomasT, from what I've read DevilsAvocado is funny, but the jester in the classic sense would be you and Zonde, in terms of your espoused beliefs.

charlylebeaugosse

Aug26-10, 08:37 AM

DrChinese:"Clearly, we know from Bell that there cannot be "predetermined" hidden variables outside of what can be observed."

Really? How do we know that? What does a detection attribute associated with a unit vector tell you?

Now, before you rip me to shreds on this I want you to bear in mind that I've consumed LOTS of popcorn (and, oh yeah, a few beers).

So, if you could send along some of your latest software with the imminent rebuttal it would be most appreciated, and would certainly ease the pain.
To be rigorous, one has to specify that the HVs that are ruled out are naive ones (dBB and Bell) that were supposed to remove the indeterminacy from microphysics: HVs that would respect the UP, but that would be predictive on one at most of any pair of conjugate variable (and any of the two if that one ha not already a conjugate on which a prediction exists) are NOT ruled out by Bell's Theorem. From the way Einstein was making fun of
dBB theory (see his letter to Born) and his correspondence with Schrödinger (see Fine's book), we can infer that it is only about such type of HVs that Einstein was thinking, at least after 1927 when he abandoned his own attempt at dBB type variables, realizing it was too naive. Now, no one has so far produced such a HVs theory, and perhaps none exist. Copenhagen forbids us from even trying. If only I had an idea, frankly I would try.
BTW, notice that Einstein, with Tolman and Podolsky, wrote the first paper I now (ETP in1931) where microscopic realism is attacked by science and not only by a philosophical opinion. While Bohr, and eventually Heisenberg as well, accepted retrodictive violations of the UP, the ETP paper rules them out (although one can to check the proof does not cover EPR particles, but there is a good reason to treat those separately: I'll explain why if anyone is interested), so that Eistein who opposed the UP a last time at Solvay VI in 1930(*) became the main proponent of them in 1931, recognizing that, with usual coordinates, thy were here to stay (but he knew well that dBB-Bell type of HVs were not respecting the UP).

(*) He attacked in 1939, but according to Bohr, he is the one who concluded the computation involving General Relativity to kill his own shutter argument, as well as (as far as I understand from Bohr, Jammer, Fine) he always helped Bohr establish the truth, be it by destroying his former theses.
(**) Hope you enjoyed the Pop Corn (and the beer).

charlylebeaugosse

Aug26-10, 08:43 AM

Charly, don't give no nevermind to the DevilsAvocado (the DA) -- unless he posts an informative ... post. He's sort of the thread jester. Wait, perhaps I have assumed that role, temporarily of course, and the DA is vying for preeminent protagonist. Yes, that's it. And you are his primary nemisis. It's all so clear now. Well, as a former physicist, or whatever, you shouldn't have any problems. Just try not to take us to the point of confusion. Regarding other contributors, DrC seems to have a reasonably good grasp of this stuff (he's either very very deep or just as confused as I am, I haven't really decided yet), RUTA is a professional physicist, JesseM is a skilled and diligent researcher, I am an ignorant layman, and I'm not sure about the other more or less regular posters in this thread.

Anyway, the DA does regularly produce some nice posts, and I do believe that he is sincerely interested in learning. So try not to be offended by anything he might say, even if it's actually offensive (and, oh yes, it will be). Just let him know, matter of factly, how you're thinking about something and you'll probably get a sincere reply. Or maybe not.

Anyway, I don't care if you're wrong or right. (Is there any wrong or right in this??) It's just interesting to hear different perspectives.

Thanks, A LOT (but I am back to physics for many years: I just stopped for a while when I turned to math and had not the strength to make a deep learning-based transition while continuing front line research in physics, a field where it is easy to produce zero value paper, that are merely exercises, not even false). But thanks again: some people attack others without knowing what impact bad words can have, and what can I say?, It made me feel good to see the quote post of yours.

DrChinese

Aug26-10, 09:25 AM

Now, before you rip me to shreds on this I want you to bear in mind that I've consumed LOTS of popcorn (and, oh yeah, a few beers).

:biggrin:

DevilsAvocado

Aug26-10, 10:34 AM

With the trauma of Devilavocado attacks on me, I will need to get back to other science work and leave the pleasure of PF for later, but as soon as I have time, I'll go to your material

Please charlylebeaugosse, I apologize if I caused you a trauma. I absolutely do not want to scare you away from PF.

All I’m asking for is that we follow the recommendations in Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=414380), and keep the discussion intellectually sound and stick to what can be regarded as current professional mainstream science.

That’s all, and I apologize if my critic was too harsh.

As for the 1935 EPR paper, this is what Einstein later expressed to Erwin Schrödinger:
"For reasons of language this [paper] was written by Podolsky after much discussion. Still, it did not come out as well as I had originally wanted; rather the essential thing was, so to speak, smothered by the formalism."

(page 147)

Bringing the Human Actors Back On Stage: The Personal Context of the Einstein-Bohr Debate (http://web.mit.edu/dikaiser/www/Kaiser.AENB.pdf)
British Journal for the History of Science 27 (1994): 129-152.

David Kaiser - Associate Professor MIT (http://web.mit.edu/dikaiser/www/)

With all due respect, to me this is not 'compatible' with the picture you have painted in this thread.

But that’s just my opinion, and I may be wrong...

(P.S. Don’t listen too much to ThomasT, he lives on popcorn & beers, and it’s a pure miracle he can write a nice post, once in a while...)

DevilsAvocado

Aug26-10, 10:39 AM

ThomasT, from what I've read DevilsAvocado is funny, but the jester in the classic sense would be you and Zonde, in terms of your espoused beliefs.

This is the best analysis in this thread! Thanks nismaratwork! :biggrin:

RUTA

Aug26-10, 03:57 PM

Yes, that's what I'm picturing. But only for the purpose of the conjecture I was making regarding how the OP's question might be answered. I'm not saying that that is a candidate for a true picture of reality. I'm not saying that that's the best metaphysical picture of reality that can be conjured.
Anyway wrt the OP's question, we assume that emitters are emitting submicroscopic or hidden wavelike disturbances in some unknown medium, some medium of unknown structure. The emissions might even be particles in the sense of bounded, and at least somewhat persistent, complex waveforms. Like, say, the light (photons) that is being emitted, analyzed and detected in optical Bell tests (or any quantum optical tests for that matter -- but optical Bell tests are particularly relevant wrt to considerations of the OP's question, even if Bell's theorem might not be). For our purposes here, I'm calling some picture, any picture, of 'something' propagating from emitter to filter to detector the 'deep reality' that exists whether we probe it with filters and detectors or not.

Ok, I understood you correctly. Thanks for clearing that up.

I stated that the existence or nonexistence of a deep reality can't be proven. It can only be inferred (or not, as one might choose) from instrumental behavior. I also stated that the assumption of the existence of a deep reality seems to me to be an essential part of fundamental physics. That is, quantum physics seems to be grounded on the assumption, based on inferences from observations of instrumental behavior, that such a deep reality exists. So I asked if the various possible answers to the OP's question are equally tenable, and answered that I don't think they are because of inferences by mainstream physicists regarding the existence, and certain characteristics, of a deep reality based on quantum experimental phenomena which have become an integral part of the development of qm and the standard model.

In other words, regardless of Zeilinger's, or whoever's, momentary expression of things, it seems to me that the mainstream development of fundamental physics is based on the assumption that there is something real with real and persistent properties that's produced via emission processes and that is moving from emitter to filter, then interacting with the filter, then moving from the filter to the detector and interacting with the detector.

Your view is absolutely in the majority.

And the contention is that if this assumption accords with reality (and of course we have no way of knowing, definitively, if this accords with reality), then EPR-type action at a distance has to be ruled out, because EPR-type action at a distance says that the deep reality of particle B is dependent on the macroscopically recorded reality of particle A, and vice versa.

In any case, EPR-type action at a distance is, prima facie, paradoxical and nonsensical -- so, EPR rightly dismissed it, even if not for precisely that reason, as not worthy of consideration.

Hmmm, I'm trying to understand your point here. I believe I get it in a later statement, so I'll respond there.

By the way, can I look at certain parts (the parts that might be at odds with my own 'realistic' view of things) of your RBW construction as just necessary mathematical conveniences? I really am beginning to understand, and like, your approach and rationale, even if I still don't understand some parts of your construction.

... And then I could only say, "oh, ok then" -- still (while liking it's rhetorical possibilities, and beginning to vaguely appreciate it's theoretical necessariness) not fully understanding how your "nonseparable 4Dism" can be nondynamical or adynamical while my pedestrian "nonseparable 3Dism" plus time/change = "nonseparable 4Dism" seems, to me to be, so necessarily dynamical. And then it hit me. While I'm simply musing about 'fundamental reality' based on some possibly quite 'loose' associations, you and your associate authors of RBW have actually constructed a viable physical theory/interpretation.

Until I fully understand and appreciate RBW, and maybe even after, can I think of RBW as being essentially an instrumentalist approach?

RBW definitely strikes people as "nothing but" instrumentalism. The reason for that is we claim QM describes distributions of relations comprising the experimental equipment, but until this last paper (arXiv 0908.4348) we didn't paint an ontological picture with a consistent underlyling formalism. So, since introducing RBW, I've worked to produce said formalism. The candidate for such a formalism, as outlined in the arXiv paper, did intrigue PSA and the referee at Foundations. But, we've yet to present at PSA and the revised version of that FoP manuscript has been under review since mid March and still no final verdict, so the jury is still out as to whether or not it's a bunch of hot air :smile:

Overall, I'd say we paint (commit to) enough of an ontological picture in the arXiv paper to get us out of the instrumentalist camp. You're free to disagree of course :smile:

If so, and not to put you on the spot (as if I could), then what about the notion that standard qm (the bare formalism with the basic probabilistic interpretation) is already essentially an instrumentalist approach?

Per RBW, QM is a statistics providing the distribution of relations comprising the experimental equipment. Accordinlgy, the most fundamental elements of reality (our version of "deep reality") are relations, not "'something' propagating from emitter to filter to detector." So, given the RBW understanding of QM, which contains no further articulation of the "relational ontology," yes, some (most?) people would conclude QM is a form of instrumentalism.

Ok, so at some point your conceptual approach sort of segues into the probability calculus of standard qm? Even so, a consistent 'conceptual' approach and rationale would seem to be an advance. Would you say that RBW in some sense, in any sense, reconciles GR with QM?

Are you and your group planning or now working on any revisions?

In our form of nonseparability, GR must be corrected (this is explained in the conclusion of the arXiv paper). We're working on the implied correction to GR now using "direct action" Regge calculus, i.e., all legs in the thatch (spacetime network) connect sources, so every leg is associated with non-zero energy-momentum. Anyway, if this actually works (which means it must replace GR! ... ya, right), "quantum gravity" would be a very different animal than anything currently pursued. The good news (if there is any) is that quantum gravity would be "all over but the shouting."

Didn't Bub like it? Or, did he just offer that eventually, after several epiphanies, he understood it -- not that he actually liked it?

We had many discussions with him because Cifone (co-author on our early papers) was his student. He never said he didn't like it and seemed to appreciate it as an intellectual novelty, but his quantum information program doesn't require him to commit to any particular ontology, so there's nothing else he need say about it.

Perhaps. I read it as the OP wrote it. "Is action at a distance possible as envisaged by the EPR paradox?" Which might be condensed to, "Is EPR-type action at a distance possible?". Which then requires that we define EPR-type action at a distance. And when we do that we find that it's different than other types of action at a distance. Specifically, it requires that the deep reality of a particle (or wave or whatever), b, assumed to be incident on a filter or detector, B, is dependent on an instrumental event, A, spacelike separated from the predicted instrumental events at B. And when we consider that the deep reality of, a, assumed to be incident on a filter or detector, A, is also dependent on an instrumental event, B, then we have a bit of a problem. Or do we? I don't really know. Help?

Ok, it looks to me like your idea of "action at a distance" is some form of nonseparability, rather than causal non-locality.

But, what sort of nonlocality? Given the inability to describe the entanglement correlations in a detailed local realistic way, there are at least two different sorts of nonlocality that we can consider to, at least quantitatively, account for the observed results. If EPR-type nonlocality is ruled out, then the answer to the OP's question is no.

In fact, Healey uses the terms "constitutive non-locality" and "causal non-locality" in his discussions of the AB effect. It looks to me like you're thinking of constitutive non-locality, which I associate with nonseparability.

In any event, I'm not sure you can rule out the logical possibility of either given EPRB phenomena, that's why I answered the OP's question affirmatively.

I'm glad you have that attitude. It's certainly appreciated that a physicist such as yourself is willing to take the time to answer questions from people like me who are not even remotely as knowledgeable as you, but are nonetheless fascinated by this stuff. Of course, that's part of what PF is all about. And also of course, I'll bet that you would really like it if some heavyweight bona fide working physicists would come down from their self-erected, but nonetheless justified, thrones for a time and make some comments about your interpretation/theory. Or are they already doing that in another, more technically oriented, thread (most of the comments within which I probably, at this time, would, generally, not understand)?

I learn to teach and teach to learn -- just the way I'm made -- and PF is a great place to do that!

As for help, I realize that no one is going to jump into the mathematical quagmire of RBW unless highly motivated to do so, i.e., until it generates new physics. I wouldn't, it's a freakin' nightmare :smile:

charlylebeaugosse

Aug26-10, 04:48 PM

Please charlylebeaugosse, I apologize if I caused you a trauma. I absolutely do not want to scare you away from PF.

All I’m asking for is that we follow the recommendations in Physics Forums Global Guidelines (http://www.physicsforums.com/showthread.php?t=414380), and keep the discussion intellectually sound and stick to what can be regarded as current professional mainstream science.

That’s all, and I apologize if my critic was too harsh.

As for the 1935 EPR paper, this is what Einstein later expressed to Erwin Schrödinger:

With all due respect, to me this is not 'compatible' with the picture you have painted in this thread.

But that’s just my opinion, and I may be wrong...

(P.S. Don’t listen too much to ThomasT, he lives on popcorn & beers, and it’s a pure miracle he can write a nice post, once in a while...)
The facts that need to be added are that Einstein was very noble in some sense at ;east and never complained publicly about co-workers, but Podolsky had a hidden agenda: to kill QM, as he did (or so he thought) in the paper. If you read the logical analysis of the
EPR paper (by Fine or others), you will see that in one step of the argument to prove that QM s incomplete, there is a step that implies that QM is false. Then, Jammer and/or Fine tell us that Podolsky wrote to the NY Time that Einstein and co-workers had proven QM false, something that infuriated Einstein who essentially ceased all relations with Podolsky.

There is more of that but perhaps that transforms the picture, especially f you take into account the facts I have reported previously, e.g., that Einstein never used elements of reality, and had his own version of QM nont complete, telling to Schrodinger for instance that coexistence of two observable was irrelevant to him. I also already mentioned that Einstein never gave his imprimatur to the version that went to Phys Rev....

Enough of that, as for standard science etc..., beside spending time with PF, I am an active scientist and my carrier is mostly made of elements that broke with previous knowledge.
My role as journal editor is in part to filtrate crank pseudo-papers, and the fact is that I have more read misquotations around EPR and Bell (including by professionals, including by my heroes) than in any other field that I have worked in. Notice that I source my divergence of opinions on the history of the field, and for where my scientific opinion differ, I provide arguments.

I will consider for now that you only read the part about Einstein-Podolsky that you chose to mention and did not read the rest, which would have made your appreciation of my own description inappropriate.
CleBG

RUTA

Aug26-10, 06:06 PM

I have nothing ready yet, a lot in preparation (but I am looking for collaborators as I always hatted to work alone and have kept projects for years before closing them, sometimes alone when at the end, I still could not find one or more partners). Meanwhile, I have proposed to DrC to initiate a thread on Bell's Theorem without locality, about 2 papers from the same author, one in preprint form I must say, that I have posted and where arguments are made against non-locality (but no claim of a decisive blow is made there, a definite blow (or many of them) being what I hope myself to do... soon enough I hope). DrC has kindly opened that Thread (I am still new and did not know where to find instructions to do that). Your opinion on those papers would be most appreciated. You seem to know a lot about the philosophy of the foundation of QM, something which is my own weakest point probably: I would really love to have your assessment of that pair of papers by Tresser. I have begun to read some of your posts and they are quite substantial in content: is there a way to have a global view on them? (perhaps if I go to you page I can follow the patrh of what you wrote.... I'll let you know if I need help). With the trauma of Devilavocado attacks on me, I will need to get back to other science work and leave the pleasure of PF for later, but as soon as I have time, I'll go to your material: what is the firat post of yours? do you remember???

I don't believe my work will be of any use for your project, i.e., showing that non-locality has nothing to with EPR-Bell phenomena. I'll ask my philosophy of science colleague if he can suggest a good starting point for a literature search. Once you get up to speed in that subset of the foundations community, you'll know how to construct and pitch your argument. Again, I'll read it and offer feedback for you when it's done.

phywjc

Aug27-10, 03:09 AM

It's not just possible, it has been experimentally demonstrated. Read up on some of the entanglement threads that have been running on here for a while. Or you could just visit Dr Chinese's website ...

something may be changed in specific situation~

nismaratwork

Aug27-10, 07:08 AM

something may be changed in specific situation~

Not to be too blunt, but like what?

charlylebeaugosse

Aug28-10, 12:56 AM

It's not just possible, it has been experimentally demonstrated.
This quote being about the original question. Of course this is only misinterpretation of facts.
Aspect's experiment showed that QM correlations are as one expected, i.e., minus the value given by Malus law, for reasons not too hard to understand. So in order to come close to the question from the experiment, one has to invoke 3 hypothesis conjointly. While one (fair sampling) does not cause problems except if one believes little green man plot to sabotage physics, the other ones are realism, condemned by the very creators of QM, and locality, supported by all of them. So there has been lots of PR around non-locality, but the masters of modern sciences thought that the false hypothesis was realism, without which what happen in a superposition is hard to grasp. Of course, the two hypotheses could be false, but that is where Occam's razor, that has shaped all sciences as we know them, come to tell us to make the minimal changes for similar predictive power. Here the minimal change consists in fact in not making changes to QM and realize that all the crazy hysteria about non-locality was due only to one single false hypothesis, realism.
Now, one realist interpretation of QM was developed, at least twice, by de Broglie and then by Bohm: it is so violently non-Lorentz invariant that many consider that it is not physics, and Pauli and others gave other arguments. One of the nicest discussion of Bell theory was given by Wigner, one of the few old masters still around to discuss that: guess what. For Wigner, Bell's Theorem was the most elegant proof that there are no HVs (although) he should have been more cautious as strange HVs not covered by Bell's Theory are not disqualified, but no one has built such a theory.

This can be made fun of, but what about a scientific discussion? For instance, about dealing with realism when considering a superposition associated to different paths in an interference experiment????

charlylebeaugosse

Aug28-10, 01:14 AM

I don't believe my work will be of any use for your project, i.e., showing that non-locality has nothing to with EPR-Bell phenomena. I'll ask my philosophy of science colleague if he can suggest a good starting point for a literature search. Once you get up to speed in that subset of the foundations community, you'll know how to construct and pitch your argument. Again, I'll read it and offer feedback for you when it's done.
Not my project: Leggett (well known across physics but no thread bout him running that I could see / but I am new) and Tresser (not known in QM but with a thread now associated to papers of his: Devilavocado judged this work false-or-something-like-that (at least implicitly), by the measured impact on www) seem to have well advanced that. So I am more interested in killing what remains of realism after the attacks by Leggett, and then proceed to get rid of any trace of actions backward in time, whether or not they allow SLT (rather not since those which permit SLT are killed by the kill one's father paradox, in my view).

This being said you seem to have some intimacy with the philosophers, among which I only can get those who deal with history, except for some who indeed do math or physics. I wanted to see if your work gives access to what I know least in what I know that I want to know)

+ I know how to get work published: produce non interesting epsilon steps. Each I tried, it worked (unwillingly in facT: in all cases or about, I only realized later the epsilon-type
character of my work). Best indication of such work: an easy and fast publication, although there is no easy publication- trivial work equivalence, of course.

RUTA

Aug28-10, 10:22 AM

Not my project: Leggett (well known across physics but no thread bout him running that I could see / but I am new) and Tresser (not known in QM but with a thread now associated to papers of his: Devilavocado judged this work false-or-something-like-that (at least implicitly), by the measured impact on www) seem to have well advanced that. So I am more interested in killing what remains of realism after the attacks by Leggett, and then proceed to get rid of any trace of actions backward in time, whether or not they allow SLT (rather not since those which permit SLT are killed by the kill one's father paradox, in my view).

I could call it "the idea you're passionate about and want to argue." Or, we could dispense with semantic arguments and you can understand my use of the phase "your project" to mean "the idea you're passionate about and want to argue."

This being said you seem to have some intimacy with the philosophers, among which I only can get those who deal with history, except for some who indeed do math or physics. I wanted to see if your work gives access to what I know least in what I know that I want to know)

We don't argue for or against realism or locality, but you may find what we cite to justify RBW of value to your project. See G. Kaiser, J. Math. Phys. 22, 705-714 (1981); A. Bohr & O. Ulfbeck, Rev. Mod. Phys. 67, 1-35 (1995); A. Bohr, B. Mottelson & O. Ulfbeck, Found. Phys. 34, #3, 405-417 (2004).

+ I know how to get work published: produce non interesting epsilon steps. Each I tried, it worked (unwillingly in facT: in all cases or about, I only realized later the epsilon-type character of my work). Best indication of such work: an easy and fast publication, although there is no easy publication- trivial work equivalence, of course.

I'm not suggesting publication for the sake of publication, I've never done so (not at an R1 institute, so I didn't have to) and I wouldn't advocate it in this case. As I said, a good argument against non-locality would be of interest to the foundations community. The best way to disseminate such an argument is through the publication process.

I infer from your posts that the idea of non-locality is something you feel strongly opposed to. I also disagree with non-locality and, while not head on, my research agenda reflects that. I'm willing to help another line of attack by offering critical reading of preprints. The offer stands.

nismaratwork

Aug28-10, 10:31 AM

I could call it "the idea you're passionate about and want to argue." Or, we could dispense with semantic arguments and you can understand my use of the phase "your project" to mean "the idea you're passionate about and want to argue."

We don't argue for or against realism or locality, but you may find what we cite to justify RBW of value to your project. See G. Kaiser, J. Math. Phys. 22, 705-714 (1981); A. Bohr & O. Ulfbeck, Rev. Mod. Phys. 67, 1-35 (1995); A. Bohr, B. Mottelson & O. Ulfbeck, Found. Phys. 34, #3, 405-417 (2004).

I'm not suggesting publication for the sake of publication, I've never done so (not at an R1 institute, so I didn't have to) and I wouldn't advocate it in this case. As I said, a good argument against non-locality would be of interest to the foundations community. The best way to disseminate such an argument is through the publication process.

I infer from your posts that the idea of non-locality is something you feel strongly opposed to. I also disagree with non-locality and, while not head on, my research agenda reflects that. I'm willing to help another line of attack by offering critical reading of preprints. The offer stands.

What makes your posts so interesting compared to some others... cough... is that as you say, you're not simply railing AGAINST non-locality, but strenuously arguing for a different framework.

Charlyebeaugoss: I'd take RUTA up on his offer if I were you; the best way to learn how to publish in any field is with a taste of peer review, and RUTA is a worthy peer (even though I respectfully disagree with his conclusions).

DevilsAvocado

Aug28-10, 03:31 PM

What makes your posts so interesting compared to some others... cough... is that as you say, you're not simply railing AGAINST non-locality, but strenuously arguing for a different framework.

This must be a proof* of non-local mind reading!! :surprised

Great nismaratwork!! I couldn’t have said it better myself!

...hope the message gets thru... cough...

(*joke)

DevilsAvocado

Aug30-10, 10:36 AM

The facts that need to be added are that Einstein was very noble in some sense at ;east and never complained publicly about co-workers, but Podolsky had a hidden agenda: to kill QM, as he did (or so he thought) in the paper.

When you do statements like "hidden agenda: to kill QM", that could be thought of as 'remarkable' by some, it would be great if you could provide a reference, or clarify if this is your own conclusions/research.

To me, it seems like you are maybe making too 'drastic' conclusions on the history of EPR.
Stanford Encyclopedia of Philosophy – The Einstein-Podolsky-Rosen Argument in Quantum Theory (http://plato.stanford.edu/entries/qt-epr/)
...
Whatever their precursors, the ideas that found their way into EPR were worked out in a series of meetings with Einstein and his two assistants, Podolsky and Rosen. The actual text, however, was written by Podolsky and, apparently, Einstein did not see the final draft (certainly he did not inspect it) before Podolsky submitted the paper to Physical Review in March of 1935, where was sent for publication the day after it arrived, without changes. Right after it was published Einstein complained that his central concerns were obscured by the overly technical nature of Podolsky's development of the argument.
For reasons of language this [paper] was written by Podolsky after several discussions. Still, it did not come out as well as I had originally wanted; rather, the essential thing was, so to speak, smothered by the formalism [Gelehrsamkeit]. (Letter from Einstein to Erwin Schrödinger, June 19, 1935. In Fine 1996, p. 35.)

It is probably correct that Einstein never complained publicly about co-workers, but this was a private letter to Erwin Schrödinger. Don’t you think that it’s plausible that Einstein would at least have indicated to Schrödinger that Podolsky made a terrible fraud, and put Einstein’s name on paper that he totally rejected (according to you)?

Since Einstein was not perfectly happy with the 1935 EPR paper, he almost immediately started to work on a clearer and more focused version of the argument. He began that process within few weeks of EPR, in the June 19 letter to Schrödinger:
Stanford Encyclopedia of Philosophy – The Einstein-Podolsky-Rosen Argument in Quantum Theory (http://plato.stanford.edu/entries/qt-epr/)
...
In the letter to Schrödinger of June 19, Einstein sketches a simple argument for the dilemma, roughly as follows.

Consider an interaction between the Albert and Niels systems that conserves their relative positions. (We need not worry about momentum, or any other quantity.) Consider the evolved wave function for the total (Albert+Niels) system when the two systems are far apart. Now assume a principle of locality-separability (Einstein calls it a Trennungsprinzip—separation principle): Whether a physical property holds for Niels' system does not depend on what measurements (if any) are made locally on Albert's system. If we measure the position of Albert's system, the conservation of relative position implies that we can immediately infer the position of Niels'; i.e., we can infer that Niels' system has a determinate position. By locality-separability it follows that Niels' system must already have had a determinate position just before Albert began that measurement. At that time, however, Niels' system has no independent state function. There is only a state function for the combined system and that total state function does not predict with certainty the position one would find for Niels' system (i.e., it is not a product one of whose factors is an eigenstate for the position of Niels' system). Thus the description of Niels' system afforded by the quantum state function is incomplete. A complete description would say (definitely yes) if a physical property were true of Niels' system. (Notice that this argument does not even depend on the reduction of the total state function for the combined system.) In this formulation of the argument it is clear that locality-separability conflicts with the eigenvalue-eigenstate link, which holds that a quantity of a system has an eigenvalue if and only if the state of the system is an eigenstate of that quantity with that eigenvalue (or a mixture of such eigenstates). The “only if” part of the link would need to be weakened order to interpret quantum state functions as complete descriptions (see entry on Modal Interpretations).

Although this simple argument concentrates on what Einstein saw as the essentials, stripping away most technical details and distractions, he had another slightly more complex argument that he was also fond of producing. (It is actually buried in the EPR paper, p. 779.) This second argument focuses clearly on the interpretation of quantum state functions and not on any issues about simultaneous values (real or not) for incompatible quantities. It goes like this.

Suppose, as in EPR, that the interaction between the two systems preserves both relative position and zero total momentum and that the systems are far apart. As before, we can measure either the position or momentum of Albert's system and, in either case, we can infer the position or momentum for Niels' system. It follows from the reduction of the total state function that, depending on whether we measure the position or momentum of Albert's system, Niels' system will be left (respectively) either in a position eigenstate or in a momentum eigenstate. Suppose too that separability hold for Niels; that is, that Niels' system has some real physical state of affairs. If locality holds as well, then the measurement of Albert's system does not disturb the assumed “reality” for Niels' system. However, that reality appears to be represented by quite different state functions, depending on which measurement of Albert's system one chooses to carry out. If we understand a “complete description” to rule out that one and the same physical state can be described by state functions with distinct physical implications, then we can conclude that the quantum mechanical description is incomplete. Here again we confront a dilemma between separability-locality and completeness. Many years later Einstein put it this way (Schilpp 1949, p. 682);
[T]he paradox forces us to relinquish one of the following two assertions:
(1) the description by means of the psi-function is complete
(2) the real states of spatially separate objects are independent of each other

It appears that the central point of EPR was to argue that in interpreting the quantum state functions we are faced with these alternatives.

As we have seen, in framing his own EPR-like arguments for the incompleteness of quantum theory, Einstein makes use of separability and locality, which are also tacitly assumed in the EPR paper.

There are other sources, saying more or less the same thing:
http://arxiv.org/abs/quant-ph/0310010 (http://arxiv.org/abs/quant-ph/0310010)

Einstein, Podolsky, Rosen, and Shannon
Asher Peres (http://en.wikipedia.org/wiki/Asher_Peres)
Department of Physics, Technion—Israel Institute of Technology, 32000 Haifa, Israel

Foundations of Physics, Vol. 35, No. 3, March 2005 (© 2005)
DOI: 10.1007/s10701-004-1986-6

...
Entangled wave-functions were not new at that time: you can find one, for example, in Eq. (10) of Rosen’s 1931 seminal paper on the ground state of the hydrogen molecule [7], which is probably more famous among chemists than the EPR paper is among physicists.

Some time after that work, Rosen became a post-doc of Einstein at the Institute of Advanced Studies in Princeton. One day, at the traditional 3 o’clock tea, Rosen mentioned to Einstein a fundamental issue of interpretation related to entangled wave-functions. Einstein immediately saw the implications for his long standing disagreement with Bohr. As they discussed the problem, Boris Podolsky joined the conversation, and later proposed to write an article. Einstein acquiesced. When he later saw the text, he disliked the formal approach, but agreed to its publication. Then, as soon as the EPR article appeared, Podolsky relased its contents to the New York Times (4 May 1935, page 11) in a way implying that the authors had found that quantum mechanics was faulty. This infuriated Einstein, who after that no longer spoke with Podolsky.

Again, with all due respect, the picture you have painted in this thread, regarding Einstein & EPR, is (to me) not 'compatible' with the above.
There is more of that but perhaps that transforms the picture, especially f you take into account the facts I have reported previously, e.g., that Einstein never used elements of reality, and had his own version of QM nont complete,

I have to be frank and tell you – I have no idea what you are talking about...

Unless we should regard the 30 years of Bohr–Einstein debates as "misquoted", it’s clear that Einstein presupposed the objectively existing real world. Einstein strove to include this ultimate reality, independent of what we observe, in our physical theories. He wrote:
"Without the belief that it is possible to grasp reality with our theoretical constructions... there would be no science."

"Physics is an attempt conceptually to grasp reality as it is thought independently of its being observed. In this sense one speaks of “physical reality”."

Einstein believed that all of reality was open to rational consideration, guided by visualizeable mathematical models. The ultimate goal of science for Einstein was to be able to bring all of these rational investigations into a single unified Weltbild (conception of the world).

Einstein’s discontent with the 1935 EPR paper is that he did not only consider quantum mechanics to be incomplete, but fundamentally inadequate. Einstein believed that quantum theory was not the appropriate starting point for constructing the new theory he thought was needed.

Yes, Einstein was one of the architects behind QM, but; when Werner Heisenberg in 1925 introduced matrix equations that removed space and time from any underlying reality, and when Max Born in 1926 proposed that QM was to be understood as a probability without any causal explanation, and when Heisenberg and Born declared at the Solvay Conference in 1927 that the revolution was over and nothing further was needed – Einstein's skepticism turned to dismay.

In 1926 he wrote a letter to Max Born, and made a remark that is now famous:
"Quantum mechanics is certainly imposing. But an inner voice tells me it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the Old One. I, at any rate, am convinced that He does not throw dice."

I love Einstein, he is my hero, but he was only human and humans do make mistakes – God does play dice with the universe, according to Stephen Hawking:
"Einstein's view was what would now be called, a hidden variable theory. Hidden variable theories might seem to be the most obvious way to incorporate the Uncertainty Principle into physics. They form the basis of the mental picture of the universe, held by many scientists, and almost all philosophers of science. But these hidden variable theories are wrong. The British physicist, John Bell, who died recently, devised an experimental test that would distinguish hidden variable theories. When the experiment was carried out carefully, the results were inconsistent with hidden variables. Thus it seems that even God is bound by the Uncertainty Principle, and can not know both the position, and the speed, of a particle. So God does play dice with the universe. All the evidence points to him being an inveterate gambler, who throws the dice on every possible occasion."

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Niels_Bohr_Albert_Einstein_by_Ehrenfest.jpg/300px-Niels_Bohr_Albert_Einstein_by_Ehrenfest.jpg

DevilsAvocado

Aug30-10, 11:00 AM

Tresser (not known in QM but with a thread now associated to papers of his: Devilavocado judged this work false-or-something-like-that (at least implicitly), by the measured impact on www)

I just considered these Google facts:
Entanglement 29,400,000 results
Albert Einstein 14,800,000 results
EPR-Bell 1,740,000 results
John S. Bell 410,000 results

And that the solution to all this, the "Effect After Cause Principle", render 8 results on Google after 4 years...?

It must be one of the most "secret" discoveries in history of science...

naturale

Aug31-10, 08:16 AM

It is possible to formulate a consistent relativistic field theory of quantum mechanics without assuming any hidden-variable in the theory and using essentially deterministic mechanics (Compact time and determinism: foundation; Found. Phys, arXiv:0903.3680). The quantization is obtained by imposing a periodic boundary conditions to solve the relativistic wave equation. It is similar to the quantization of a particle in a box where the quantized energies are obtained by imposing boundary conditions to the matter waves. In this way there are not local hidden variable at all. The EPR problem and Bell theorem are bypassed.

DevilsAvocado

Aug31-10, 02:57 PM

naturale, not assuming any hidden-variable in the theory is probably very wise...

The final nail in the coffin for Detection Loopholes and Hidden Variables ...?

A test with a stable isotope (http://en.wikipedia.org/wiki/Isotopes_of_calcium) of Calcium (http://en.wikipedia.org/wiki/Calcium) (a soft gray alkaline earth metal), a pair of 40Ca+ ions (http://en.wikipedia.org/wiki/Ions) (20 neutrons) is trapped in a linear Paul trap. Optical pumping initializes ions with a qubit state fidelity of 99.5%, to experimentally demonstrate a state-independent conflict with non-contextuality, according to the Kochen-Specker theorem (http://en.wikipedia.org/wiki/Kochen%E2%80%93Specker_theorem).
http://arxiv.org/abs/0904.1655 (http://arxiv.org/abs/0904.1655)

State-independent experimental test of quantum contextuality
G. Kirchmair, F. Zähringer, R. Gerritsma, M. Kleinmann, O. Gühne, A. Cabello, R. Blatt, C. F. Roos

(Submitted on 10 Apr 2009 (v1), last revised 5 May 2009 (this version, v2))
Journal reference: Nature 460, 494 (2009)
DOI: 10.1038/nature08172 (http://www.nature.com/nature/journal/v460/n7254/full/nature08172.html)

The question of whether quantum phenomena can be explained by classical models with hidden variables is the subject of a long lasting debate. In 1964, Bell showed that certain types of classical models cannot explain the quantum mechanical predictions for specific states of distant particles. Along this line, some types of hidden variable models have been experimentally ruled out. An intuitive feature for classical models is non-contextuality: the property that any measurement has a value which is independent of other compatible measurements being carried out at the same time. However, the results of Kochen, Specker, and Bell show that non-contextuality is in conflict with quantum mechanics. The conflict resides in the structure of the theory and is independent of the properties of special states. It has been debated whether the Kochen-Specker theorem could be experimentally tested at all. Only recently, first tests of quantum contextuality have been proposed and undertaken with photons and neutrons. Yet these tests required the generation of special quantum states and left various loopholes open. Here, using trapped ions, we experimentally demonstrate a state-independent conflict with non-contextuality. The experiment is not subject to the detection loophole and we show that, despite imperfections and possible measurement disturbances, our results cannot be explained in non-contextual terms.

nismaratwork

Aug31-10, 02:58 PM

DevilsAvocado

Aug31-10, 03:07 PM

You’re welcome Nismar. ;)

charlylebeaugosse

Aug31-10, 10:20 PM

I just considered these Google facts:
Entanglement 29,400,000 results
Albert Einstein 14,800,000 results
EPR-Bell 1,740,000 results
John S. Bell 410,000 results

And that the solution to all this, the "Effect After Cause Principle", render 8 results on Google after 4 years...?

It must be one of the most "secret" discoveries in history of science...
I could not find a www version of what got printed, so these four years cover other papers even if a title is misleading. But this is science and not the schoolyard: stop counting google entries (that include those that you hate most) and start analyzing argument: didn't you write somewhere that your read the paper twice and could not find a mistake?

Do you want to see serious problems with conventional treatments or even in texts written by some VERY prominent people? Some people form the PF crowd could then help you, others would help me but each of us could reject help we do not find scientifically sound.

As for the very long post on history, again you put words in my mouth by amplifying statements that I make and other transformations.

Just two examples telling ho science history may be delicate: as analyzed by Fine, when Einstein mention the language as the reason why Podolsky wrote, it is not about English but about the technical language of Godel's theory on which Godel was lecturing at the institute, lecures that Podolsky only was following. The very issue of the EPR paper is indeed "Godelian" rather than typical in Physics. As for the English, see that Podolsky use phrases that indicate his Russian origin. Rosen was born and raised in the USA and if language as usual had been the issue, he would have written.
None of all the history is mine: I am a Mathematicia and a physicis, not a historian. What I report comes from Jammer, Fine, Einstein, Poper, Born, Rosen (in a 1985 conference paper on 50 years after EPR), Rosenfeld in a book about Bohr, a story copied in Wheeler-Zurek and a few others (a few physics papers have exact citations and exact quotes). Only some guesses on how Enstein would have mocked Bell are mine but the source of that is quite direct and the hypothesis rater obvious.

The New York time story is largely documented but may have been known to Einstein after the letter to Shrodinger: anyway, Einstein had been a protector of Podolsky since at least 1931, and was probably not to revert quickly the way he spoke of him to anyone else.
But get into Jammer (books and papers) and Fine (book and papers) and I do not advertise for their philosophical stands, none of which I like: just basic facts and simple analyzes, with enough different sources to double check (and more) and look for consistency
Here also you can ask me point by point instead of trying to win by kill or by submersion (I am too frail now to get into an endurance war. You may well discourage me, but is it what you want? Fairness is crucial for us all, since science is besieged by many enemies. We have to be fair, precise, honest, accurate, suspicious of any place unclear etc. if we want to help science and not only help ourselves.

Now for the science, you can check that Einstein version of EPR in 1933 (Rosenfeld in Wheeler-Zurek) was very close to what he told Shrodinger, and later Born, and many others till almost his end.He never used "elements" of reality.

By the way, encyclopedias are not a great primary source, except if the article has a known author.

If only you had quietly reported the material you collected and proposed that we go over it, everyone being able to add her/his own sources, further comments, further data so that we end up recognizing the polluted sources, perhaps even understanding the reasons and.or mechanisms for pollution....won't this be more profitable than destroying CleBG or killing a paper that has barely come out and that no-one seem to have analyzed yet.
As for me I understand why the EACP is not Locality: remains to understand if Realism + ECP => A Bell Theorem.

There are also side issues such as what allows o compute which correlation: worth exploring?
Well I have found some good science on other threads and will go there if no serious discussion or info, or answer to many questions I have asked along my posts (e.g., asking for corroborations in many instances when I had unchecked sources only and real science I guess). Nice to know that such threads exist, and too bad if this one does not use the rich mixture of its participants to let us all progress (and learning a new joke IS definitely progress for me , but i English, I can often appreciate but hardly be the source.

.

naturale

Sep1-10, 08:32 AM

DevilsAvocado

Sep1-10, 09:16 AM

You’re welcome naturale. I’ll check out 'your' paper ASAP.

DevilsAvocado

Sep1-10, 09:57 AM

:bugeye: ... what did I do wrong now??

Please charlylebeaugosse, I did apologize for my post #1463, twice. I thought this was a discussion between adults on a scientific subject, not personal at all...

Frankly, I have no idea where you get your 'impression' and words like; "hate", "win by kill", "submersion", "discourage", "enemies"... this is very odd to me...

I know you are fairly new on PF, but I think I can promise you that basically all users here are friends, in one way or another. Yes, we can have different opinions about different matters, but I don’t think I have ever seen anyone hating anyone literally...

For heaven's sake, even ThomasT and I are friends! (Even though he have made several really rough personal attacks on me, and then regretted everything. You just have to trust that people basically are kind, and when adding popcorn+beers+keyboards an 'accident' may happen before you know it... :smile:)

As new on PF, you maybe also 'misinterpret' when we shift between serious and humorous? I know I am guilty to this 'ambivalence' (sorry, something is probably slightly 'wrong' in the upper storey...).

If you see a smiley like this :smile: it’s most probably humorous. If you see a smiley like this :biggrin: it’s unquestionably humorous.

If RUTA says: "Is action at a distance possible as envisaged by the EPR Paradox?" The short answer is "yes." :smile:

And I answer: YES! :smile:

It means that we are partly smiling at our own 'stubbornness'! Get it? The EPR-Bell question is not finally and definite solved yet, and then it becomes slightly amusing to be stubbornly sure about the answer. And if you include the fact that many have declared a very definite "NO!" and "YES!" during the ~1,500 posts in this thread... then maybe it is funny. Get it?

One important thing that you should know; many PF users are laymen or students, here to learn. As far as I know RUTA is the only true professional in this thread (besides you).

Don’t take it too darned serious, it is what it is.

You have read zillions more books on mathematics and physics, than me, and of course you know these things better. On the other hand, I don’t think it’s unreasonable to have an opinion on subjects that to me, on logical basis, seems 'strange'.

I will not get into Podolsky vs. Einstein, and "reality" again. I leave it to the reader to judge what is plausible or not.

But I think I have to comment on your critics on internet and Google. The World Wide Web was invented at CERN by MIT professor Sir Tim Berners-Lee, who publicly introduced the project in December 1990:
"The World-Wide Web (W3) was developed to be a pool of human knowledge, and human culture, which would allow collaborators in remote sites to share their ideas and all aspects of a common project."

Yes, today there is a lot of BS on the web, but to call it a "schoolyard" is maybe not accurate. As far as I understand, the web and internet is very important tools for professional scientists, in communicating and spreading information globally.

Trillions of web pages and documents (including PDF) are indexed by Google, who has over one million servers in data centers around the world, and processes over one billion search requests and twenty petabytes of user-generated data every day. Companies and governments buy advertising and statistics from Google. It is a billion dollar industry, and pretty big for being a "schoolyard"...

I’m afraid you are wrong about the paper "A Bell Theorem with no locality assumption", it was submitted on 1 Aug 2006. Click the link and check for yourself http://arxiv.org/abs/quant-ph/0608008.

Now, my maybe very silly "layman intuition" tells me that if the "Effect After Cause Principle" is the final solution to the EPR paradox, that will tells us if the world is mysterious non-local or shockingly non-real, it would not only render thousands of documents on the web, but it will also be on TV primetime news. But as I said, this is only my "layman vision" on the subject, and you probably know better...

Besides that, I also have the natural feeling the "Effect After Cause Principle" is not very 'revolutionary'... effect is always after the cause, just by definition... unless we are talking faster-than-light (superluminal or FTL) communication? And we all agree that this is not the case in EPR-Bell.

So, I honestly don’t see how Charles Tresser is going to save your day...

But why not talk me thru, step by step, my example halfway down in post #1241 (http://www.physicsforums.com/showpost.php?p=2833234&postcount=1241) (<-- click on the link), and show me how the "Effect After Cause Principle" can explain the violation of this simple Bell Inequality:
N(+30°, -30°) ≤ N(+30°, 0°) + N(0°, -30°)

Cheers! :wink: