Bell's theorem mathematical content

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Discussion Overview

The discussion centers on the mathematical content of Bell's theorem, particularly focusing on its algebraic, group theoretic, and geometric aspects. Participants explore the foundational assumptions and mathematical structures underlying Bell's theorem, as well as the implications for quantum mechanics and local hidden-variable theories.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests reducing the premise of Bell's theorem to its mathematical content, referencing Bell's original 1964 paper and its equations, particularly focusing on the spinorial representation of rotations.
  • Another participant expresses confusion about the initial claims and outlines three parts of Bell's proof, questioning the relevance of spinors to the derivation of quantum predictions for the EPR experiment.
  • A later reply clarifies that the focus should be on the mathematical specification leading to the inequality in Bell's theorem, emphasizing the derivation of probabilities from the mathematical setting.
  • Another participant presents a rigorous statement of Bell's theorem, detailing the conditions and the proof without invoking spinors or group theory, asserting that classical probabilities suffice for the construction of the Bell inequality.
  • One participant reiterates the interest in describing the construction of the probability space and random variables used in Bell's theorem, emphasizing the application of classical probabilities and the Born rule for quantum predictions.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the necessity of spinors and group theory in the context of Bell's theorem. While some argue for a purely mathematical approach, others question the relevance of certain mathematical structures, leading to an unresolved discussion about the foundational assumptions.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the mathematical structures and the definitions of the probability space. The relationship between spinors and the derivation of probabilities remains a point of contention.

  • #31
RockyMarciano said:
Once again this thread is not about that, it discusses something previous to laying out the abstract probabilistic conditions that a theory fulfilling the EPR experiment must have. What the theorem says is not that all theories satisfying the inequality must be of certain type,

No, that's backwards. It proves that all theories of a certain type satisfy the inequality.

but rather that those that want to replicate all QM predictions (confirmed empirically) must violate them

He proved that all theories of a certain type satisfy a particular inequality. EPR experiments do not satisfy that inequality. Therefore, EPR experiments cannot be explained by a theory of that type.

There is nothing in Bell's argument that relies on any property of quantum mechanics. The fact that EPR violates his inequality is an empirical matter.
 
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  • #32
zonde said:
Maybe it's trivial, but think it is good idea to put conditions of Bell theorem into mathematical form before doing the same thing with assumptions. So I propose these conditions:
  1. We can produce series of paired events ##A_\alpha## and ##B_\beta## where ##\alpha## and ##\beta## are freely changeable parameters. ##A_\alpha## and ##B_\beta## each can be split into two subevents: ##A_\alpha=\pm 1## and ##B_\beta=\pm 1##.
  2. For every i-th pair of events ##A_{\alpha i}## and ##B_{\beta i}## in series, ##P(A_{\alpha i}=+1, B_{\beta i}=+1)=0## and ##P(A_{\alpha i}=-1, B_{\beta i}=-1)=0## whenever ##\alpha = \beta##.
@RockyMarciano, do these seem fine to you?
Again, the goal of this thread is not directly concerned with the probabilities that lead to the Bell inequalities other than for the fact that all the physical theories with the minimal common mathematical description I'm trying to reach consensus about will certainly satisfy the inequalities when using classicall probabilities on them. The advantage is that by identifying the principal features of this physical theories spaces and mathematical objects in them that directly lead to satisfying the inequality(because that is a feature of EPR math models) it would be so much easier to discard from the beguinning a lot of mathematical models for physics that are not compatible with experiment.
 
  • #33
RockyMarciano said:
Again, the goal of this thread is not directly concerned with the probabilities that lead to the Bell inequalities

Your first post asked what is "the best way to characterize the main assumption from which the probabilities are constructed?"
 
  • #34
Wait, first let's clarify what I mean by EPR experiment and EPR mode, I refer to Einstein's so called "local realist" model, and to the gedanken experiment operational requirements and assumptions not to the actual Aspect type experiments outcomes showing the violations.

stevendaryl said:
No, that's backwards. It proves that all theories of a certain type satisfy the inequality.
And therefore that those that don't satisfy them like the QM predictions or those appparently compatible with nature don't. This is what I'm saying. It is not backwards.

He proved that all theories of a certain type satisfy a particular inequality. EPR experiments do not satisfy that inequality. Therefore, EPR experiments cannot be explained by a theory of that type.
Sure, look tho the possible source of confusion here above.
There is nothing in Bell's argument that relies on any property of quantum mechanics. The fact that EPR violates his inequality is an empirical matter.
Of course. Again there might be some trivial misunderstanding here, see the first commnet of this post.
 
  • #35
RockyMarciano said:
Wait, first let's clarify what I mean by EPR experiment and EPR mode, I refer to Einstein's so called "local realist" model, and to the gedanken experiment operational requirements and assumptions not to the actual Aspect type experiments outcomes showing the violations.
Yes, please clarify these operational requirements of gedanken experiment in mathematical form as it seems you are not satisfied with my attempt in post #29.
 
  • #36
This thread doesn't show much chance of being productive.

In particular, I would like to remind everyone that PhysicsForums is not aimed at the development of physics, but rather at helping understand it.

Thread closed.
 

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