Model used to refute Bell's theorem

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Discussion Overview

The discussion revolves around a recent paper that claims to refute Bell's theorem. Participants analyze the model presented in the paper, questioning its consistency with quantum mechanics (QM) and exploring the implications of its claims regarding local realism and contextual models.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants express skepticism about the model's consistency with QM, citing specific examples involving polarizer settings and resulting measurements.
  • Others argue that the model reproduces QM correlations and thus challenges Bell's theorem, suggesting that Bell's original assumptions do not account for contextual models.
  • A participant emphasizes that to disprove the model, one must demonstrate a contradiction, which they claim has not been done.
  • Concerns are raised about the implications of the model being non-local, with references to specific equations and their interpretations.
  • Some participants assert that acceptance of the paper by a journal does not guarantee its correctness, highlighting the need for rigorous scrutiny.
  • There are repeated assertions regarding the necessity to address all proofs of non-locality to establish compatibility of QM with locality.
  • Discussions include references to other non-locality proofs, such as GHZ and CHSH, and the implications of contextual models on Bell's theorem.

Areas of Agreement / Disagreement

Participants do not reach a consensus. There are competing views on the validity of the model and its implications for Bell's theorem, with some asserting it refutes Bell's theorem while others maintain that it does not align with QM principles.

Contextual Notes

Participants note that the model's implications depend on specific assumptions and interpretations of the equations presented. There are unresolved questions regarding the nature of locality and contextuality in relation to the model.

msumm21
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TL;DR
The model used to refute Bell's theorem in a recent paper doesn't seem to be consistent with QM
I’m looking over a recent paper mentioned in another thread. It claims to refute Bell’s theorem. At first glance, the model presented in the paper doesn’t appear consistent with QM. Here’s a simple example.

Suppose we set both polarizers to the same angle ##\alpha = \pi /4##. In the model presented, A=1 (photon 1 passes its polarizer) when ##\lambda \leq \cos^2(\pi/4-\varphi_1)##, and B=1 when ##\lambda \leq \cos^2(\pi/4-\varphi_2)##. Using the initial condition ##\varphi_1=0,\varphi_2=\pi/2## as in the examples in the paper both inequalities reduce to ##\lambda \leq 0.5##. So the two photons yield the same result when measured about the same axis. As shown in the paper around Eqn 8, they also give the same result when measured about orthogonal axes.

So it seems this model is not consistent with QM (or I made an arithmetic error).
 
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msumm21 said:
The model used to refute Bell's theorem in a recent paper doesn't seem to be consistent with QM
I suspected that too, I'm glad that someone actually checked it.
 
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msumm21 said:
Summary:: The model used to refute Bell's theorem in a recent paper doesn't seem to be consistent with QM

I’m looking over a recent paper mentioned in another thread. It claims to refute Bell’s theorem. At first glance, the model presented in the paper doesn’t appear consistent with QM. Here’s a simple example.

Suppose we set both polarizers to the same angle ##\alpha = \pi /4##. In the model presented, A=1 (photon 1 passes its polarizer) when ##\lambda \leq \cos^2(\pi/4-\varphi_1)##, and B=1 when ##\lambda \leq \cos^2(\pi/4-\varphi_2)##. Using the initial condition ##\varphi_1=0,\varphi_2=\pi/2## as in the examples in the paper both inequalities reduce to ##\lambda \leq 0.5##. So the two photons yield the same result when measured about the same axis. As shown in the paper around Eqn 8, they also give the same result when measured about orthogonal axes.

So it seems this model is not consistent with QM (or I made an arithmetic error).
In the 2nd case you have delta <0. Equations (2) and (3) hold for 0<delta<pi/2.
What to do with other values of delta is described below eq. (3). For the case mentioned above it turns out that B=-1.
 
msumm21 said:
It claims to refute Bell’s theorem.
The original thread title did, but in the course of the thread the OP admitted that that claim is not correct. That's why the thread was closed.
 
This is not true. I did not admit the claim is not correct. The claim is still to refute Bell' theorem.
The reason is that Bell had claimed no local realistic model were possible at all without referring to his assumptions which don't cover thinkable contextual models. So the model presented in the paper which reproduces the QM correlations refutes Bell's theorem.
This was accepted by EPL (Europhysics Letters)
 
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emuc said:
This is not true.
Sorry, but this was discussed in the previous thread. That discussion is off topic in this thread. This thread is about whether the model presented in the paper is consistent with QM.

emuc said:
This was accepted by EPL (Europhysics Letters)
Acceptance of a paper by a journal is no guarantee that the paper is correct.
 
PeterDonis said:
Acceptance of a paper by a journal is no guarantee that the paper is correct.
So far nobody has found a bug in my paper
 
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emuc said:
So far nobody has found a bug in my paper
You mean, nobody found a bug that you accepted to be a bug.
 
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If you say there was a bug, you should describe it precisely so that everyone can understand what you mean.
 
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  • #10
emuc said:
If you say there was a bug, you should describe it precisely so that everyone can understand what you mean.
I did it in the closed thread. I've got many likes, so I think many (but not all) understood my points and agreed with me.
 
  • #11
emuc said:
So far nobody has found a bug in my paper
Was your paper accepted in the first journal to which you submitted it? If not, would you dare to tell us in how many journals the paper was rejected? Would you share the referee reviews from those journals? Perhaps some of those spotted some bugs that you didn't accept as such.
 
  • #12
In order to disprove the model of the paper one has to refer to it and prove a contradiction. Nobody has done it so far.
 
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  • #13
emuc said:
In order to disprove the model of the paper one has to refer to it and prove a contradiction. Nobody has done it so far.
To prove that QM is compatible with locality, in principle you need to disprove all proofs of non-locality, it's not sufficient to disprove just one of the Bell's proofs. For instance, can you disprove the GHZ proof of nonlocality? That is, can you construct a local contextual model compatible with QM predictions for the GHZ state? For a simple presentation of the GHZ proof see my http://thphys.irb.hr/wiki/main/images/a/a1/QFound2.pdf pages 11-13.
 
  • #14
Demystifier said:
To prove that QM is compatible with locality, in principle you need to disprove all proofs of non-locality, it's not sufficient to disprove just one of the Bell's proofs.
The opposite is the case as I wrote already in the closed tread:

Bell's theorem was refuted because he ignored contextual models in his reasoning. This also applies to any other theorem that claims that no local realistic model for quantum effects is possible, if they fail to rule out contextual models. These include, for example, the theorems of CHSH, GHZ and Hardy.
 
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  • #15
emuc said:
Bell's theorem was refuted because he ignored contextual models in his reasoning.
But I explained you (in the closed thread) that he did not ignore contextual models in his reasoning.
 
  • #16
Call it as you like it, he definitely ignored the kind of my model as this reproduces the QM correlations.
 
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  • #17
I think your model is in fact nonlocal. This is seen in the paragraph around Eq. (9). In particular, before (9) you say that you use
$$\delta=\alpha + \pi/2 -\beta$$
It's not clear to me how exactly did you get this formula, but this formula is nonlocal. It is nonlocal because ##\alpha## is a property of one particle, while ##\beta## is a property of the other particle. Or if you still claim that this formula has a local origin, it would help if you could better explain how did you obtain this formula, because to me it's not clear from the paper.
 
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  • #18
emuc said:
Call it as you like it, he definitely ignored the kind of my model as this reproduces the QM correlations.
Bell's inequality holds for contextual models as well. If your model reproduces the QM predictions, then it must take one of the known outs, such as non-locality, superdeterminism or retrocausality. There are other models like this, so it would be nothing new or spectacular.
 
  • #19
Nullstein said:
If your model reproduces the QM predictions, then it must take one of the known outs, such as non-locality, superdeterminism or retrocausality.
My post #17 indicates that his model is in fact non-local.
 
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  • #20
@emuc, repeated assertion is not argument. Nor is ignoring the actual statements made in the OP of this thread about the paper. Since you are either unable or unwilling to actually address what others are saying, this thread is closed. Further attempts on your part to make claims about your paper will receive a warning.
 

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