Bell's Experiments & Hidden Variables

[gespex]

Hello everyone,

I was reading about Bell's theorem on Wikipedia. One thing I found particularly interesting:

E. T. Jaynes[27] pointed out two hidden assumptions in Bell Inequality that could limit its generality:
1. Bell interpreted conditional probability P(X|Y) as a causal inference, i.e. Y exerted a causal inference on X in reality. However, P(X|Y) actually only means logical inference (deduction). Causes cannot travel faster than light or backward in time, but deduction can.
2. Bell's inequality does not apply to some possible hidden variable theories. It only applies to a certain class of local hidden variable theories. In fact, it might have just missed the kind of hidden variable theories that Einstein is most interested in.

In particular number 2. The points he made can be found at http://bayes.wustl.edu/etj/articles/cmystery.pdf . While I did not understand all the steps from Bell's Theorem, I think I did understand the objections this document raised against Bell's Theorem.

I've got two questions:
1. Is there anything fundamentally wrong with that paper of E. T. Jaynes and if not, why is Bell's Theorem still being considered to be valid by most?
2. If the paper would be valid and a hidden variable theorem would be constructed, would Bell's Experiments not be pointless, as both the predictions by QM and the classical approach would be identical?

Thanks in advance

 

[bohm2]

I'd read all sides (of the meaning of Bell's theorem) and make a decision based on the merit of each side. You may find the original source to many of Bell's papers useful:

http://thenookofwisdom.files.wordpress.com/2011/09/bell-john-speakable-and-unspeakable-in-quantum-mechanics-cup-1987kt225s.pdf

A good secondary source/summary consitent with his views (with his quotes) can also be found here:

Note that everything in the above discussion refers to some particular candidate physical theory. For example, there is a tendency for misplaced skepticism to arise from Bell’s use of the concept of “beables” in the formulation of local causality. This term strikes the ears of those influenced by orthodox quantum philosophy as having a metaphysical character and/or possibly committing one (already, in the very definition of what it means for a theory to respect relativistic local causality) to something unorthodox like “realism” or “hidden variables.” Such concerns, however, are based on the failure to appreciate that the concept “beable” is theory-relative. “Beable” refers not to what is physically real, but to what some candidate theory posits as being physically real. Bell writes: “I use the term ‘beable’ rather than some more committed term like ‘being’ or ‘beer’ to recall the essentially tentative nature of any physical theory. Such a theory is at best a candidate for the description of nature. Terms like ‘being’, ‘beer’, ‘existent’, etc., would seem to me lacking in humility. In fact ‘beable’ is short for ‘maybe-able’.” Similar considerations apply to the notion of “completeness” that is, as stressed above, essential to Bell’s formulation. A complete specification of beables in some spacetime region simply means a specification of everything (relevant) that is posited by the candidate theory in question. There is no presumption that such a full specification actually correspond to what really exists in the relevant spacetime region, i.e., no presumption that the candidate theory in question is true.

Local Causality and Completeness: Bell vs. Jarrett
http://lanl.arxiv.org/PS_cache/arxiv/pdf/0808/0808.2178v1.pdf

Other papers arguing this interpretation of Bell's theorem:

My own first paper (Physics 1, 195 (1965.) on this subject starts with a summary of the EPR argument from locality to deterministic hidden variables. But the commentators have almost universally reported that it begins with deterministic hidden variables

Non-Local Realistic Theories and the Scope of the Bell Theorem
http://arxiv.org/ftp/arxiv/papers/0811/0811.2862.pdf

A Criticism of the article "An experimental test of non-local realism"
http://arxiv.org/abs/0809.4000

Against ‘Realism’
http://lanl.arxiv.org/PS_cache/quant-ph/pdf/0607/0607057v2.pdf

Quantum non-locality and relativity: metaphysical intimations of modern physics
http://books.google.ca/books/about/...d_relativity.html?id=dBkRiBzq4r4C&redir_esc=y

 

[Demystifier]

The Bell theorem is often interpreted that it is not possible to have both reality and locality. But there is a way to save both, provided that you are ready to swallow one philosophically unpopular idea:
http://xxx.lanl.gov/abs/1112.2034

 

[gespex]

Thanks for your answers guys!

 

[bohm2]

The Bell theorem is often interpreted that it is not possible to have both reality and locality. But there is a way to save both, provided that you are ready to swallow one philosophically unpopular idea:
http://xxx.lanl.gov/abs/1112.2034

Maybe I'm mistaken but that view presented in your paper sounds a bit like Leibniz's monadology?

 

[Demystifier]

I know nothing about Leibniz's monadology, so I couldn't say.
Anyway, in the paper I am not suggesting that this approach is better then the others. All I am saying is that such a possibility cannot be logically excluded. Whether one likes this approach or not, it's up to him/her. But IF you want both reality (in 3-space) and locality, and IF you don't want superdeterminism (fine tuned initial conditions) and backward causation, THEN it seems to be the only option that remains.