I Does realism imply locality or vice versa?

[Denis]

Of course EPR elements of reality imply predetermination. Of every possible outcome! But that makes the assumption there is no observer dependency. They thought any other view was unreasonable.

Sorry, no. You obtain predeterminism only if you believe that the choice of Alice what to measure does not disturb, in any way, Bob's part of the way. If you believe that it does, the EPR criterion of reality is not applicable to this configuration, thus, gives you nothing. Only EPR combined with Einstein causality implies predetermination. The result of the measurement can be undetermined, say, depend on the hidden parameters of the measurement device too, and the interaction with Alice' device then distorts what happens with Bob's particle. The details of this interaction can be described like in dBB theory.

A less technical description of locality and realism can be found in Mermin's work. I reproduced his argument concerning the Hardy experiment here https://www.physicsforums.com/insig...elayed-choice-no-counterfactual-definiteness/ . Just scroll down to the paragraph starting with "The Hardy experiment is shown and explained in Figure 2 (reference therein)." The entire explanation is only one paragraph long.

Seen the whole thing about the Blockworld view. What could you recommend as the best reference to this BW metaphysics? "Best" in the sense of using the best justification of it in the most radical (most fatalistic) way?

 

[Simon Phoenix]

but I can't quite decide what convention of our two non-local masters, Demystier or DrChinese to follow

Follow either of them and you won't go far wrong :-)

But you don't have to 'follow' anybody here - you're only forced to make a choice if you want a theory which models the conditional probabilities using these extra, so-called hidden, variables. If you make that choice first, then you're faced with the issues of 'locality' and 'realism'.

Bell's theorem says is that IF we want to explain the correlations using some extra variables THEN the resulting theory can't be both 'local' AND 'realistic', if we wish agreement with the predictions of QM. Therefore QM cannot be replaced with a locally realistic hidden variable theory.

Note that this does NOT mean that QM must therefore be one of the other kinds of hidden variable theory (non-local, realistic, for example). It certainly could be (as the Bohmian treatment shows us), but we don't have to think of QM as a hidden variable theory at all.

Remember that the first step in the analysis is not the assumption of 'locality' or 'realism', but the assumption that there exist these extra variables.

Just stick with standard QM then you don't have to worry.

 

[fanieh]

Follow either of them and you won't go far wrong :-)

But you don't have to 'follow' anybody here - you're only forced to make a choice if you want a theory which models the conditional probabilities using these extra, so-called hidden, variables. If you make that choice first, then you're faced with the issues of 'locality' and 'realism'.

Bell's theorem says is that IF we want to explain the correlations using some extra variables THEN the resulting theory can't be both 'local' AND 'realistic', if we wish agreement with the predictions of QM. Therefore QM cannot be replaced with a locally realistic hidden variable theory.

Note that this does NOT mean that QM must therefore be one of the other kinds of hidden variable theory (non-local, realistic, for example). It certainly could be (as the Bohmian treatment shows us), but we don't have to think of QM as a hidden variable theory at all.

Remember that the first step in the analysis is not the assumption of 'locality' or 'realism', but the assumption that there exist these extra variables.

Just stick with standard QM then you don't have to worry.

After thinking it over. Demystifier was the correct one. Here's why. If no realism, no locality.. so nothing to be non local about. Therefore DrChinese must change the phase "non-local correlations" to "beyond Einstein locality corrections" to avoid more confusion. Won't you agree DrChinese?

What are the thinking of other non PF physicists?

 

[Simon Phoenix]

After thinking it over. Demystifier was the correct one. Here's why. If no realism, no locality.. so nothing to be non local about. Therefore DrChinese must change the phase "non-local correlations" to "beyond Einstein locality corrections" to avoid more confusion. Won't you agree DrChinese?

I can't speak for Demystifier, or DrChinese, but I certainly disagree with you here

It's clear from the analysis that the 'locality' here is referring to the condition imposed that changes of the device settings (assumed to be independent changes - so changes of the independent variables $a$ and $b$ that occur in the conditional probability $P(A,B | a,b)$ and the resulting marginals) do not affect the results obtained at some remote location.

As Bell pointed out we could have the variables $\lambda$ being 'non-local' (in a wider sense) and still be bounded by the inequality, provided we still maintain the locality condition imposed on the changes of device setting.

I see no reason why relaxing the condition of realism (properties exist independent of measurement), implies non-locality. I see no reason why relaxing the condition of locality (device settings affect remote results) implies non-realism.

But I agree there is confusion over the use of the word 'local' - which means something very specific in Bell's analysis - and sometimes (as I have done) we use the word 'local' to mean slightly different things even within the same sentence! That's life - it happens - it's them pesky words and their interpretations which plague physics and mathematics, where the same words can get used to mean different things in different contexts.

 

[Zafa Pi]

Why do you think so? I think he would, because he would not completely accept a proof based on a questionable assumption.

If 1 + 1 = 3 then I am the Pope. Perfectly valid theorem with a questionable hypothesis. I'm sure B.R. would agree.
But saying, "I think that actual physics is most likely non-local." is kind of weird. Could you elaborate?

 

[Denis]

I see no reason why relaxing the condition of realism (properties exist independent of measurement), implies non-locality. I see no reason why relaxing the condition of locality (device settings affect remote results) implies non-realism.

Indeed, above things would be nonsensical. If there is a connection, it would be the reverse one: relaxing realism would allow stronger locality, relaxing locality would allow realism.

But in fact the situation is the following:

If we throw away realism, weak "signal" locality remains. Strong, Einstein locality is, then, anyway meaningless, given that it is about real causal influences, but we have abandoned realism.

But weak "signal" locality is not endangered at all. It holds anyway, with or without realism. So giving up realism gains nothing.

So, the situation can be easily summarized: Reality is not Einstein-causal. To save the fundamental(ist) variant of relativistic symmetry - that everything has to be Lorentz-covariant - we have to reject realism.

 

[Demystifier]

But saying, "I think that actual physics is most likely non-local." is kind of weird. Could you elaborate?

I think I already did. See Sec. 5.3 in my paper
http://lanl.arxiv.org/abs/1703.08341
Each entry is a possible local interpretation of QM, and each entry contains a "but" which makes it quite unreasonable. Yet, neither of those "buts" is as unreasonable as your 1+1=3.

By the way, my avatar would not agree that 1+1=3 is obviously wrong. He needed 379 pages to prove it.
https://en.wikipedia.org/wiki/Principia_Mathematica

 

[RUTA]

Seen the whole thing about the Blockworld view. What could you recommend as the best reference to this BW metaphysics? "Best" in the sense of using the best justification of it in the most radical (most fatalistic) way?

My Insights series has arguments for Wilczek's "God's-eye" or block universe view of physical reality. If you're already familiar with the standard argument for block universe from SR, then skip to number 3 of that series https://www.physicsforums.com/insig...lications-part-3-general-relativity-big-bang/. At the top of that article there are links to articles 4 and 5. My colleagues and I have an entire book coming out with Oxford UP making this case. That's all I can say about it here, as it's not relevant to this thread. I just wanted to share Mermin's account of the Hardy experiment on realism versus locality which happened to be in that series.

 

[Zafa Pi]

I think I already did. See Sec. 5.3 in my paper
http://lanl.arxiv.org/abs/1703.08341
Each entry is a possible local interpretation of QM, and each entry contains a "but" which makes it quite unreasonable. Yet, neither of those "buts" is as unreasonable as your 1+1=3.

By the way, my avatar would not agree that 1+1=3 is obviously wrong. He needed 379 pages to prove it.
https://en.wikipedia.org/wiki/Principia_Mathematica

Blaylock claims MWI is local.
I didn't say 1 + 1 = 3 was wrong, that is indeed very deep as was shown by Whitehead. I said it was questionable.
You said physics was most likely nonlocal, but you never gave the odds.

 

[Zafa Pi]

but what interpretations can describe (i)

According to Blaylock MWI.

 

[Zafa Pi]

"Signal locality" is an established phrase, and means the impossibility to send signals FTL. I think this is clear enough. It is clearly a weaker notion than the "Bell locality" used in the BI proof, so naming them "weak" vs. "strong" seems also unproblematic. All I want is to have clear notions, which do not cause confusion.

I was searching on line for a couple hours and I find a quagmire of definitions of local and non-local whether physics is one or the other, which interpretations are one or the other, if realism or CFD is given up only then do we have non-locality, or maybe non-locality is always there. So many disagree with one another and everybody is sure. For example Blaylock and Maudlin.

Can't find a a clear definition of signal locality. Perhaps you could define you terms or provide links that are specific

 

[morrobay]

You intended to say if realism or CFD is given up then you can have locality.* Realism in the context of perfect (anti) correlations when detectors are aligned that infers pre defined, deterministic properties.
That then are applied when detectors are not aligned in deriving the inequality.
*Local relativistic causality(no FTL signal) that QM is consistent with.
The question I have is how do the linked cluster principle and consistent histories (both local and realistic) define a non locality,sometimes called quantum non locality (not FTL) that cause the correlations in a spacelike separated experimental setting.
As In following diagram (credit stevendaryl) where Alice and Bob are spacelike separated.

 

[Denis]

...if realism or CFD is given up only then do we have non-locality, or maybe non-locality is always there.

Can't find a a clear definition of signal locality. Perhaps you could define you terms or provide links that are specific

Never forget that realism and CFD are very different things (but often confused). CFD has to be given up, because of Bell as well as Kochen-Specker, and there is nothing to discuss. Realism does not have to be given up, with dBB as a counterexample.

Signal locality means that there are no statistical effects which distribute a local change with velocity FTL, so that the non-Einstein locality cannot be used to send signals FTL.
I would say Valentini's paper https://arxiv.org/abs/quant-ph/0106098 is specific enough, and proves even an interesting theorem about signal locality.

 

[morrobay]

The author in this paper also derives the same correlation function with locality (no faster than light signal)
from the conservation laws.
P(a,b)_con = P(a,b)_qm = - cos θ
https://arxiv.org/pdf/quant-ph/0407041.pdf

 

[Simon Phoenix]

I was searching on line for a couple hours and I find a quagmire of definitions of local and non-local whether physics is one or the other, which interpretations are one or the other, if realism or CFD is given up only then do we have non-locality, or maybe non-locality is always there. So many disagree with one another and everybody is sure.

Yes indeed, and it's rather easy to tie one's philosophical knickers in all sorts of knots worrying about the nuances of all the terms that get bandied about; locality, Einstein locality, Bell locality, causality, Einstein locality, signal locality, CFD, non-contextuality, realism and so on ad nauseam. I suppose it gives the philosophically minded something to do on a long winter's evening and keeps them off the streets.

I am, of course, being overly unkind here in order to make a point. The words, divorced from the analyses that spawned them, can so easily lead one astray. That's why I personally feel it's so important to ground oneself in the actual specific analysis and see what the terms actually mean - instead of trying to wade through pages of overblown rhetoric that obfuscate rather than elucidate.

So my advice is to take a derivation of a BI that you like and pick it apart. My own favourite is Bell's wonderful analysis of the CHSH inequality that is contained in his Bertlmann's socks paper. Bell's original inequality is in fact a special case of the more general CHSH version. It's the ideas and the physics in the analysis, rather than what we call these things, that is important I feel. So, sure, one author might use the term 'locality' whereas another might call the same thing 'Bell locality', or even 'Einstein causality', but underlying it all are the same ideas that are more clearly expressed in symbols. In an ideal world it would be nice if we could all agree on the same nomenclature, or even use nomenclature consistently - but we're all human and often try to cut corners and use shorthand.

So let's take the CHSH version and see what is involved.
(1) we have an experiment that allows us, after sufficiently many runs, to measure to a good approximation the joint conditional distributions $P(A,B | a,b)$
(2) we wish to attempt to explain the correlations and so we assume that there are some extra variables or quantities, all lumped into the symbol $\lambda$ for convenience, that explain the correlations in the following sense $P(A,B | a,b, \lambda) = P(A | a,b, \lambda)P(B | a,b, \lambda)$. The physical meaning here is that these extra variables, $\lambda$, account for the observed correlation so that any residual fluctuation in the measured quantities must be independent

But look at $P(A | a,b, \lambda)$ here, for example. It's telling us that the distribution of results obtained by Alice is dependent on the setting chosen by Bob at some remote location. How can that be? It would seem to run counter to our intuition and, if it were true, if we could also control the variables $\lambda$ it would certainly allow us to construct a FTL signalling scheme where we could transmit real information faster than we could send the information using light.

In order to avoid this unwelcome possibility (at least) the further assumption is made that :
(3) $P(A,B | a,b, \lambda) = P(A | a,b, \lambda)P(B | a,b, \lambda) = P(A | a, \lambda)P(B | b, \lambda)$.

The last step on the RHS is where the 'locality' considerations get imposed. Physically we're saying that the distribution of results at Alice depends only on Alice's setting, and the hidden variables - and do not depend on the choice of device setting at some remote place. Physics would be very strange indeed if we allowed this to be so - if the experiments we do here depend on whether someone a million miles away has twiddled with his knob or not we'd never be able to trust the results we obtained in our laboratory. Intuitively we can see that the only way for this to happen is if information about a device setting at some remote location was communicated (in some fashion) to our lab. Somehow our own system (device + measured object) must 'know' about some remote knob twiddling. That definitely doesn't seem right does it?

Apart from the purposes of communication and using consistent terminology does it really matter whether we term condition (3) 'locality', or 'Bell locality', or 'the anti knob-twiddling postulate'? The meaning and intent is crystal clear in the analysis - it can become less clear when we abstract this idea out of the analytical context and try to reason about it. But as long as we continually reference back to our grounded experiment (hypothetical or otherwise) and the assumptions we use in order to construct a plausible model, then everything should be clear enough - even if different people use the same words in subtly different ways.

 

[Zafa Pi]

Never forget that realism and CFD are very different things (but often confused). CFD has to be given up, because of Bell as well as Kochen-Specker, and there is nothing to discuss. Realism does not have to be given up, with dBB as a counterexample.

Yes, Blaylock also says CFD and realism are different, but comes to the opposite conclusion. I don't see the difference that well.

Signal locality means that there are no statistical effects which distribute a local change with velocity FTL, so that the non-Einstein locality cannot be used to send signals FTL.

"distribute"? Does this mean that the correlations that occur in separated measurements on entangled entities take a while to be seen?
Can't find "non-Einstein locality".
If you find this boring you need not respond and I will not feel hurt. There have been many threads on this topic and I'm a bit jaded. I have my own very elementary way of doing a Bell type result (close to CHSH) and what the lab shows and only mention QT at the end as a theory that predicts the lab results.

 

[Zafa Pi]

Yes indeed, and it's rather easy to tie one's philosophical knickers in all sorts of knots worrying about the nuances of all the terms that get bandied about; locality, Einstein locality, Bell locality, causality, Einstein locality, signal locality, CFD, non-contextuality, realism and so on ad nauseam. I suppose it gives the philosophically minded something to do on a long winter's evening and keeps them off the streets.

Hear hear! Unfortunately it doesn't keep them off the internet. Thanks for the response.

So my advice is to take a derivation of a BI that you like and pick it apart. My own favourite is Bell's wonderful analysis of the CHSH inequality that is contained in his Bertlmann's socks paper. Bell's original inequality is in fact a special case of the more general CHSH version. It's the ideas and the physics in the analysis, rather than what we call these things, that is important I feel. So, sure, one author might use the term 'locality' whereas another might call the same thing 'Bell locality', or even 'Einstein causality', but underlying it all are the same ideas that are more clearly expressed in symbols. In an ideal world it would be nice if we could all agree on the same nomenclature, or even use nomenclature consistently - but we're all human and often try to cut corners and use shorthand.

As you can see from post #66 I long ago have taken your advise. My target is a freshman math or physics major and any technical term is only parenthetical.

I think that the presentation in Nielsen & Chuang is easier than the one you give and mine is easier/more elementary than theirs, though longer.

 

[Denis]

Yes, Blaylock also says CFD and realism are different, but comes to the opposite conclusion.

I will not comment Blaylock, for reasons connected with the netiquette. But, ok, look at the following quote:

Following this reasoning, some scientists insist that Bell’s inequality rests only on the assumption of locality, and that counterfactual definiteness, which is implied in the definition of “elements of reality,” is inferred rather than assumed. This line of thought neglects to realize that the single-reality assumption is already built into the definition of EPR’s “elements.” Multi-reality interpretations such as many worlds provide a contrasting viewpoint.

These "some scientists" include Bell, who wrote

It is important to note that to the limited degree to which determinism plays a role in the EPR argument, it is not assumed but inferred. What is held sacred is the principle of 'local causality' -- or 'no action at a distance'. ... It is remarkably difficult to get this point across, that determinism is not a presupposition of the analysis.

And is CFD implied in the "definition" of the EPR "elements of reality"? There is not really a definion there, instead, there is a criterion, the EPR criterion of reality. It is:

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.

So, it tells us nothing about the existence of some elements of reality, except in the case that we (for whatever reason) assume that we can make this prediction without in any way disturbing a system. And this clearly presupposes Einstein locality, in some version which forbids such a disturbance.

Regarding the possibility that elements of reality could depend on non-local effects, they concluded: “No reasonable definition of reality could be expected to permit this.”

Not really. The context is the following:

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.

This obviously already takes as already given that the process "does not disturb the second system in any way". It is a comment about the possibility that, despite this, the reality of P and Q depends on this.

"distribute"? Does this mean that the correlations that occur in separated measurements on entangled entities take a while to be seen?

Observation can never tell us that information is distributed with infinite velocity. What looks like infinite for us may appear finite but large in reality.

Can't find "non-Einstein locality".

Usually people use "nonlocal" instead. But the term nonlocality is misleading, because local theories with speed of information transfer greater then c would have to be named nonlocal, which is a little bit Orwellian.

 

[N88]

...
Usually people use "nonlocal" instead. But the term nonlocality is misleading, because local theories with speed of information transfer greater then c would have to be named nonlocal, which is a little bit Orwellian.

How about this clarification? "Local theories with speed of information transfer greater then c would best be named Einstein-nonlocal."

 

[Zafa Pi]

I will not comment Blaylock, for reasons connected with the netiquette.

Lol

These "some scientists" include Bell, who wrote

"It is important to note that to the limited degree to which determinism plays a role in the EPR argument, it is not assumed but inferred. What is held sacred is the principle of 'local causality' -- or 'no action at a distance'. ... It is remarkably difficult to get this point across, that determinism is not a presupposition of the analysis."

I find this a bit vague, but if HE is saying that CFD is not employed in his original argument then HE is correct (to a "limited degree") in saying, "It is remarkably difficult to get this point across", Because, I, for one, disagree with HIM. I see clearly where HE stealthily introduced CFD into HIS proof. I've been in two previous debates in this forum on this matter, and several others in different contexts. I invite you to heap on me all the nonetiquette abuse that your heart desires, I would find it an honor. Just watch out for the monitors.

And is CFD implied in the "definition" of the EPR "elements of reality"? There is not really a definion there, instead, there is a criterion, the EPR criterion of reality.

What is the definition of speeding on Montana highways? / What is the criterion for speeding on Montana highways?
I you wish to quibble over the difference, feel free, but I won't.

"it is not assumed but inferred." J.B.
After checking the historical record Alice inferred Dr. Bob was wrong. / After checking the historical record Alice assumed Dr. Bob was wrong.
I think that Alice thinks Dr. Bob is wrong. I think determinism plays a role in the EPR argument, to the limited degree of above -40^o.

Yes indeed, and it's rather easy to tie one's philosophical knickers in all sorts of knots worrying about the nuances of all the terms that get bandied about

I got entangled knots in my quantum knickers.

 

[stevendaryl]

"it is not assumed but inferred." J.B.

I agree with Bell on this. Here's my argument:

Suppose we have EPR with anti-correlated spins. Suppose for the sake of the story that Alice measures her particle's spin along the x-axis slightly before Bob measures his particle's spin along the x-axis.

Immediately after Alice measures her result, it is 100% certain what Bob's result will be: The opposite of Alice's. So we have two possibilities:

1. Bob's result was determined before Alice performed her measurement.
2. Bob's result was indeterminate before Alice's measurement, but became determinate immediately afterward.

In case #2, Alice's measurement seems to have had an effect on Bob's particle: it made a transition from an indeterminate state, where both results (spin-up or spin-down) are possible, to a determinate state, where only one result is possible. So possibility #2 would seem to violate the rule that Alice's actions can have no result on Bob's particle.

So case #1 is left. Of course, Bell's analysis proves that case #1 can't be true, either. So I don't know where that leaves us.

So I think it's completely wrong to say that Bell assumed determinism. What he assumed was what he called local realism, that Bob's results, deterministic or not, only depend on conditions near Bob.

 

[Denis]

How about this clarification? "Local theories with speed of information transfer greater then c would best be named Einstein-nonlocal."

That would be fine.

"It is important to note that to the limited degree to which determinism plays a role in the EPR argument, it is not assumed but inferred. What is held sacred is the principle of 'local causality' -- or 'no action at a distance'. ... It is remarkably difficult to get this point across, that determinism is not a presupposition of the analysis."

I find this a bit vague, but if HE is saying that CFD is not employed in his original argument then HE is correct (to a "limited degree") in saying, "It is remarkably difficult to get this point across", Because, I, for one, disagree with HIM.

We have the Bell proof, which goes roughly in the following way:

EPR criterion + Einstein locality -> CFD in this particular situation -> Bell inequalities.

Is CFD "employed" here? It doesn't matter. What matters is that presentations of Bell's theorem which forget about the first part, and present the theorem as

CFD -> Bell inequalities

and therefore arguing that all you have to do is to reject a CFD assumption (as it would have been made) are wrong.

I see clearly where HE stealthily introduced CFD into HIS proof.

I can see only a part where he proves that CFD holds for the particular case of the spin components in this particular state. A proof which is based on the EPR criterion of reality (which, taken alone, gives almost nothing, because it contains the very serious and essentially unprovable condition "without in any way disturbing the system") together with a very strong notion of Einstein causality (which forbids any distortion in any way FTL).

What is the definition of speeding on Montana highways? / What is the criterion for speeding on Montana highways?
I you wish to quibble over the difference, feel free, but I won't.
After checking the historical record Alice inferred Dr. Bob was wrong. / After checking the historical record Alice assumed Dr. Bob was wrong.

There are precise and clear differences in the meaning. A definition gives you all what is necessary and sufficient to be what is defined, a criterion only some sufficient condition. (Therefore, in case of disagreement about the definition, one can nonetheless often find some criterion.)
"Assumed" means the property is listed in the "If ..." part of a theorem. "Inferred" means it is not in the "if ..." part of the theorem. It may be used in the theorem, but only after being in the "then ..." part of a prior part of the proof. (Therefore it matters only as far as you doubt the proof. But if the proof is ok, you can forget about it.)

 

[fanieh]

Simon and others who are not realist or antirealist. If Bell's Theorem was discovered by Bohr.. would we have all these debates about realism? Bohr is anti-realist.. so in the event it's called Bohr's Theorem and there is Bohr's Inequality violation.. then it's automatically dispensing with realism, is this a right thing to think? The reason we have all these debates is because Bell happens to be a Bohmian and so the whole realism issues come out? Remember Copenhagen or the orthodox interpretation is anti-realism.. so without Bell, we won't have all these realism, counterfactual definiteness, etc stuff right? And Bohr's Theorem will be automatically dispensing reality. Just to understand it by these perspective.

I really think dispensing reality is more logical. Imagine you have two pixels in the monitor screen, does it make sense the two pixels are directly communicating non-locally. It makes more sense the two pixels (let's say representing two particles light years apart in the program) are vivified by the computer software and electron guns or electronics. Therefore for the two pixels, they are correlated not by direct nonlocal communication but behind the screen (or behind the scene stuff). This is bonafide Copenhagen and orthodox interpretation is it not where particles don't exist before measurement and they are called into existence by higher reality. Or is this not the orthodox at all? What is it then?

 

[Zafa Pi]

I agree with Bell on this. Here's my argument:

Suppose we have EPR with anti-correlated spins. Suppose for the sake of the story that Alice measures her particle's spin along the x-axis slightly before Bob measures his particle's spin along the x-axis.

Immediately after Alice measures her result, it is 100% certain what Bob's result will be: The opposite of Alice's. So we have two possibilities:

1. Bob's result was determined before Alice performed her measurement.
2. Bob's result was indeterminate before Alice's measurement, but became determinate immediately afterward.

In case #2, Alice's measurement seems to have had an effect on Bob's particle: it made a transition from an indeterminate state, where both results (spin-up or spin-down) are possible, to a determinate state, where only one result is possible. So possibility #2 would seem to violate the rule that Alice's actions can have no result on Bob's particle.

So case #1 is left. Of course, Bell's analysis proves that case #1 can't be true, either. So I don't know where that leaves us.

So I think it's completely wrong to say that Bell assumed determinism. What he assumed was what he called local realism, that Bob's results, deterministic or not, only depend on conditions near Bob.

When I wrote "it is not assumed but inferred." J.B., I was taking it from, "It is important to note that to the limited degree to which determinism plays a role in the EPR argument, it is not assumed but inferred." in post #68. I assumed, or inferred (you choose) that Bell was thinking about EPR's argument, not his own. And I think EPR is loaded with determinism. And when Bell derived his inequality he uses CFD, which I consider a form of determinism.

 

[Zafa Pi]

There are precise and clear differences in the meaning. A definition gives you all what is necessary and sufficient to be what is defined, a criterion only some sufficient condition. (Therefore, in case of disagreement about the definition, one can nonetheless often find some criterion.)
"Assumed" means the property is listed in the "If ..." part of a theorem. "Inferred" means it is not in the "if ..." part of the theorem. It may be used in the theorem, but only after being in the "then ..." part of a prior part of the proof. (Therefore it matters only as far as you doubt the proof. But if the proof is ok, you can forget about it.)

I am happy for you finding such precision in the meaning of these words (ignoring the two pairs of sentences I provided in post #70).
But if you get to fret over these distinctions then so do I.

Usually people use "nonlocal" instead. But the term nonlocality is misleading, because local theories with speed of information transfer greater then c would have to be named nonlocal, which is a little bit Orwellian.

Orwellian usually refers to dystopian social issues. I think you should have used "Star Trekian"

 

[Demystifier]

Blaylock claims MWI is local.

As I explained in the paper, MWI is not non-local, but it does not imply that it is local. (I wonder what my avatar would say about that? )

 

[Demystifier]

Orwellian usually refers to dystopian social issues. I think you should have used "Star Trekian"

Maybe @Denis had the illogical Orwellian newspeak in mind, because "faster than light" is not the same as "non-local".

 

[Zafa Pi]

As I explained in the paper, MWI is not non-local, but it does not imply that it is local. (I wonder what my avatar would say about that? )

I accept anything you say about MWI, for two reasons:
1) You're smart and funny, in spite of sometimes defending some of your wrong opinions.
2) I put MWI in the same aesthetic garbage bag as superdeterminism, so have at it. (at least this is what this version of me thinks)

I think your avatar has a mean streak and never gave Frege a comforting hug.

 

[Demystifier]

1) You're smart and funny, in spite of sometimes defending some of your wrong opinions.

Having wrong opinions occasionally is a prerequisite for being smart. In a sense, it can even be derived from the Godel's theorems.

 

[Simon Phoenix]

Having wrong opinions occasionally is a prerequisite for being smart

I wish you hadn't used the word occasionally there. If simply getting things wrong was a qualification for being smart I'd be Gauss!

We all learn from our mistakes - so hurry up and make lots of mistakes

I think it was Weinberg who coined that. In a kind of similar vein I also like Edison's statement along the lines of "I haven't failed 10,000 times - I have succeeded in finding 10,000 things that don't work"

 

[Zafa Pi]

I wish you hadn't used the word occasionally there. If simply getting things wrong was a qualification for being smart I'd be Gauss!

We all learn from our mistakes - so hurry up and make lots of mistakes

I think it was Weinberg who coined that. In a kind of similar vein I also like Edison's statement along the lines of "I haven't failed 10,000 times - I have succeeded in finding 10,000 things that don't work"

The only thing I've learned from my mistakes is that I don't learn from my mistakes.

 

[Simon Phoenix]

The only thing I've learned from my mistakes is that I don't learn from my mistakes.

Lol - very Godellian

 

[Denis]

I am happy for you finding such precision in the meaning of these words (ignoring the two pairs of sentences I provided in post #70).

The meaning of these words may be quite vague and unclear, as suggested by your examples. But in this particular context, their meaning and the differences are quite clear and certain.

Orwellian usually refers to dystopian social issues. I think you should have used "Star Trekian"

The actual state of fundamental physics is imho a quite close to a dystopian scenario.

 

[Demystifier]

The actual state of fundamental physics is imho a quite close to a dystopian scenario.

So you don't believe that we already have the theory of everything?

 

[Denis]

The actual state of fundamental physics is imho a quite close to a dystopian scenario.

So you don't believe that we already have the theory of everything?

Sorry, I have forgotten to insert a "mainstream":

The actual state of mainstream fundamental physics is imho a quite close to a dystopian scenario.

Better?

 

[Demystifier]

The actual state of mainstream fundamental physics is imho a quite close to a dystopian scenario.

Can you elaborate?

 

[Denis]

Can you elaborate?

Fundamental physics has no experimental base, no conflict between observation and theory, thus, has only a few theoretical problems to be solved. This makes the domain highly speculative. This happens, in itself not a problem. The natural state of non-dystopian fundamental physics, and the optimal for finding the truth (given that in highly speculative domains most proposals will fail) would be a large number of very different proposals, each proposal supported by rather small groups.

What we see in reality are a very few directions: Strings, LQG, that is essentially already all. And this is a sociological problem: Even if you would have an alternative idea, you would have to recommend young scientists not to study it - because non-mainstream research, that means here everything outside strings and LQG, cannot offer grants and jobs, and make it much harder to publish, so you will be probably out of science after the actual grant finishes. Scientists have to follow established mainstream fads to survive as scientists.

And these mainstream fads, once in a position of power (control over grants), do not even have to care about progress. The main objections against string theory have been raised 10 years ago. Have you heard about a major progress which would have invalidated any of the objections? But string theory is alive yet.

So, even if somebody outside the mainstream would have developed an approach for a TOE, given these sociological aspects the probability is quite high that it would be simply ignored. If this is not close to dystopian, what is?

 

[stevendaryl]

When I wrote "it is not assumed but inferred." J.B., I was taking it from, "It is important to note that to the limited degree to which determinism plays a role in the EPR argument, it is not assumed but inferred." in post #68. I assumed, or inferred (you choose) that Bell was thinking about EPR's argument, not his own. And I think EPR is loaded with determinism. And when Bell derived his inequality he uses CFD, which I consider a form of determinism.

Here's the way I would put it: Bell (as did Einstein before him) was assuming a particular type of physical theory--locally realistic theories. These theories include both deterministic and nondeterministic theories, those that obey CFD and those that don't. So his notion of locally realistic theory does not assume determinism or CFD...However, you can show pretty easily that out of all the locally realistic theories, only CFD theories can predict perfect correlation/anti-correlation.

So given perfect correlation/anti-correlation, Bell had no need to consider nondeterministic locally realistic theories.

So it's not

• Locally realistic theory \Rightarrow determinism

It's

• Locally realistic theory + observations of perfect correlation/anticorrelation \Rightarrow determinism

An example of a theory that is locally realistic (in my opinion) but is not CFD would be a stochastic theory such as Brownian motion. If the world is nondeterministic, but the nondeterminism of distant parts of the world are independent, then that would be locally realistic. For example, I could have a nondeterministic theory of perfect coins, where flipping a coin nondeterministically results in heads or tails. But if this theory is locally realistic, then there would be no correlations between the results of distant coin-flips.

 

[stevendaryl]

Fundamental physics has no experimental base, no conflict between observation and theory, thus, has only a few theoretical problems to be solved. This makes the domain highly speculative. This happens, in itself not a problem. The natural state of non-dystopian fundamental physics, and the optimal for finding the truth (given that in highly speculative domains most proposals will fail) would be a large number of very different proposals, each proposal supported by rather small groups.

What we see in reality are a very few directions: Strings, LQG, that is essentially already all. And this is a sociological problem: Even if you would have an alternative idea, you would have to recommend young scientists not to study it - because non-mainstream research, that means here everything outside strings and LQG, cannot offer grants and jobs, and make it much harder to publish, so you will be probably out of science after the actual grant finishes. Scientists have to follow established mainstream fads to survive as scientists.

And these mainstream fads, once in a position of power (control over grants), do not even have to care about progress. The main objections against string theory have been raised 10 years ago. Have you heard about a major progress which would have invalidated any of the objections? But string theory is alive yet.

So, even if somebody outside the mainstream would have developed an approach for a TOE, given these sociological aspects the probability is quite high that it would be simply ignored. If this is not close to dystopian, what is?

I agree that progress on fundamental physics has been slow or even nonexistent in recent years. I actually don't blame the mainstream or the sociological aspects so much, though. To me, the situation is that we have an effective model, the standard model, that describes things so well that there is almost no observations that contradict it. Progress in physics happens when you see something that is incompatible with mainstream science. There was a golden age of fundamental physics during which every few years, a new particle was discovered, a new kind of decay. All those years of discovery led to the standard model. But now, we don't seem to be able to easily produce anything that isn't already predicted by the standard model.

There are certainly lots of puzzles left unsolved--explaining the large-scale structure of the universe, explaining why particles have the masses they have, explaining why coupling constants have the values they do, etc. And there is no shortage of people trying to explain these things. But their theories are little-better than speculation (speculation supported by really difficult mathematics, in lots of cases) if they don't predict a verifiable departure from the standard model.

 

[stevendaryl]

I accept anything you say about MWI, for two reasons:
1) You're smart and funny, in spite of sometimes defending some of your wrong opinions.
2) I put MWI in the same aesthetic garbage bag as superdeterminism, so have at it. (at least this is what this version of me thinks)

I think your avatar has a mean streak and never gave Frege a comforting hug.

I actually think that there is a sense in which MWI, Bohmian mechanics, consistent histories and the "minimal interpretation" (Copenhagen without objective collapse) are in some sense, basically the same theory. It's just different ways of describing the same thing, like the old fable about the blind men and the elephant.

 

[fanieh]

Simon and others who are not realist or antirealist. If Bell's Theorem was discovered by Bohr.. would we have all these debates about realism? Bohr is anti-realist.. so in the event it's called Bohr's Theorem and there is Bohr's Inequality violation.. then it's automatically dispensing with realism, is this a right thing to think? The reason we have all these debates is because Bell happens to be a Bohmian and so the whole realism issues come out? Remember Copenhagen or the orthodox interpretation is anti-realism.. so without Bell, we won't have all these realism, counterfactual definiteness, etc stuff right? And Bohr's Theorem will be automatically dispensing reality. Just to understand it by these perspective.

I really think dispensing reality is more logical. Imagine you have two pixels in the monitor screen, does it make sense the two pixels are directly communicating non-locally. It makes more sense the two pixels (let's say representing two particles light years apart in the program) are vivified by the computer software and electron guns or electronics. Therefore for the two pixels, they are correlated not by direct nonlocal communication but behind the screen (or behind the scene stuff). This is bonafide Copenhagen and orthodox interpretation is it not where particles don't exist before measurement and they are called into existence by higher reality. Or is this not the orthodox at all? What is it then?

In short. Without Bell, we won't have any of these problems about realisms, is it not? Bohr has already declared that in the absence of measurements of the positions of particles, there are no positions.

 

[Denis]

Of course, if you have no problem to reject realism without sufficient reason (say, if you think Bohr's opinion is sufficient to reject realism), then, indeed, you will have no reason to care about all these debates about realism. Once Bohr has declared this ... or maybe once Pope Benedict has declared this ...

I prefer to care about arguments. Those proposed, say, by Bohm, or Bell, or those papers one is forbidden to link here, not because of the authority of Bohm or Bell or those evil nonconformists, but because of the content of their arguments.

And the content which is relevant is that there exists theories and interpretation for everything which are compatible with realism.

 

[fanieh]

If realists are Demystifier, Denis
and anti-realists are DrChinese
what about the statistical essemblers like Bill Hobba and Vanhees71, are these considered Realists too or agnostics (neither realists or anti-realists)?

 

[Denis]

They have to decide themselves. But the statistical ensemble interpretation is not in conflict with realism. Realism is not determinism, thus, completely comfortable with a statistical description.

 

[OCR]

The only thing I've learned from my mistakes is that I don't learn from my mistakes.

HA! . The only time I've ever been wrong, was once... when I thought I'd made a mistake ! . .

 

[forcefield]

So we have two possibilities:

1. Bob's result was determined before Alice performed her measurement.

So case #1 is left. Of course, Bell's analysis proves that case #1 can't be true, either. So I don't know where that leaves us.

I think what Bell proved was that the possible determinism was not like Bertlmanns' socks. I also think that Bertlmanns' socks type of determinism is close to Bohr's realism (whatever that is).

I am left with FTL effects assuming philosophical realism.

 

[Simon Phoenix]

Without Bell, we won't have any of these problems about realisms, is it not?

Isn't that a bit like blaming Newton for breaking the glass you've just dropped?

Anyway, there was already something of a sinking feeling regarding 'realism' well before Bell - I mean one only has to attempt (and usually fail) to understand Bohr's dense ramblings to see that a big spanner had already been chucked in the works regarding any 'classical' worldview. Bell just used it to tighten the nuts

 

[fanieh]

Isn't that a bit like blaming Newton for breaking the glass you've just dropped?

Anyway, there was already something of a sinking feeling regarding 'realism' well before Bell - I mean one only has to attempt (and usually fail) to understand Bohr's dense ramblings to see that a big spanner had already been chucked in the works regarding any 'classical' worldview. Bell just used it to tighten the nuts

Isn't that a bit like blaming Newton for breaking the glass you've just dropped?

Anyway, there was already something of a sinking feeling regarding 'realism' well before Bell - I mean one only has to attempt (and usually fail) to understand Bohr's dense ramblings to see that a big spanner had already been chucked in the works regarding any 'classical' worldview. Bell just used it to tighten the nuts

How do you relate the factorization or preferred basis problems in MWI to the realism/antirealism thing in Bell's? Conventionally, MWI supports realism.. but with the preferred basis problem and any solution, can it become anti-realism or still realism?

 

[Simon Phoenix]

How do you relate the factorization or preferred basis problems in MWI to the realism/antirealism thing in Bell's?

I don't.

Generally I try to think about MWI as little as I possibly can

 

[fanieh]

Are all MWI variants pro-realisms and pro-locality?
Or are there MWI variants that are non-local?

I think I read somewhere that BM is when you consider only a single branch of the MWI.. so does this mean MWI is fully realistic like BM?