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

[zonde]

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]

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.

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.

 

[SpectraCat]

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:

In interpretation of experiment wave nature of light is completely 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]

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]

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]

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]

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]

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]

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.

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]

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]

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 separate 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]

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

 

[DrChinese]

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.

 

[Frame Dragger]

@DevilsAvocado & @DrChinese: Thanks very much.

 

[DevilsAvocado]

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

Marshall "Over the Cliff" 1959SLPX
[PLAIN]http://mentalfloss.cachefly.net/wp-content/uploads/2006/10/SpinalTap_Edith_503.jpg

 

[DevilsAvocado]

... What came first?

Nothing?

 

[inflector]

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]

We can compare it with double slit experiment:

In interpretation of experiment wave nature of light is completely 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]

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]

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]

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]

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.

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

It is!

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...

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:

From the frame of reference of A, the light will reach the front and back of the train car at the same time.

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 going to be a Philosopher when I grow up, it seem like an easy piece of cake!

"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... ​

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!

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:

 

[DevilsAvocado]

Got it.
I am in "Denial Camp" definitely.

Great! One step forward!
I do have to warn you that 'backstage' we have formed a Denial of Denial Camps ! ()

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 https://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!

 

[DrChinese]

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]

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

"[URL Mermin's EPR gedanken experiment animated[/B]

[/URL]

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]

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 going to be a Philosopher when I grow up, it seem like an easy piece of cake!

"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... ​

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]

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]

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]

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!

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??

Sweet jeees... I’m feeling dizzy...

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

 

[Frame Dragger]

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!



>> 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??

Sweet jeees... I’m feeling dizzy...

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!