What is even more confusing is that experts can't even agree on what some of the theorems imply. The recent PBR is one example but Bell's theorem is another one. For instance, there are some physicists including Bell himself who question whether Bell's theorem has anything to do with realism/hidden variables. They suggest it means non-locality irrespective of "realism" issues:
Quote:
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/pd ... 2178v1.pdfQuote:
What really matters is the fact that the derivation of Bell’s inequality in no way whatsoever needs an assumption of realism. In spite of this fundamental fact, which everybody can verify by going carefully through the proof, a large part of the scientific community shares the completely wrong opinion that realism is among the basic assumption needed for the derivation of Bell’s result. Bell himself has stressed this aspect and has remarked that it is extremely difficult to eradicate this prejudice...
"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." (Bell)
This being the situation we must conclude that in no way whatsoever Bell’s inequality has something to do with realism. It simply identifies in a straightforward and lucid way that what quantum phenomena impose to us is to accept the unescapable fact that natural processes involving entangled states of composite and far-away systems turn out to be unavoidably non-local.
The interpretation of quantum mechanics: where do we stand?
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 0958v1.pdfQuote:
As I have tried to show in the preceding sections, there is a strong prejudice surrounding the foundational meaning of the Bell theorem, a prejudice that seems to survive intact through the years, in spite of the clear statements to the contrary repeatedly expressed—to begin with—by the inventor of the theorem itself, namely John S. Bell. This prejudice not only survives but in the last years has become even stronger, supported as it is by an emphasis on quantum computation that tends to dissolve all deep conceptual problems of standard quantum theory into a new information-theoretic orthodoxy. According to this prejudice, the core of the Bell theorem concerns a philosophical notion—realism—and proves that such notion is untenable on physical grounds, namely holding to it implies quantitative predictions that are contradicted by the quantum predictions. This interpretation sounds very much like the ultimate death sentence for realism, and such a sentence seems hard to resist since it is physics which pronounces it, namely the queen of the hard sciences. As argued above, this approach overlooks the circumstance that, in order to assess the implications of a theorem, we have to be clear about the conditions under which the theorem can be proved, and one need not be a physicist to acknowledge it. What logical soundness and physical reasonableness suggest (Sects. 3–5) is that the role of Bell’s theorem is not to set constraints on how ‘realist’ we are allowed to be about quantum systems but rather, much more interestingly, to characterize a structural property of any theory that aims to cover the domain of validity covered so far by quantum mechanics, namely non-locality. As a consequence, whether a theory aiming to supersede quantum theory will be ‘realist’, ‘non-realist’, ‘half-realist’ or ‘one-third realist’, this will concern the further conceptual and formal resources of that theory and not at all the Bell theorem.
Non-Local Realistic Theories and the Scope of the Bell Theorem
http://www.springerlink.com/content/h20 ... lltext.pdf
A Criticism of the article "An experimental test of non-local realism"
http://arxiv.org/abs/0809.4000
Against ‘Realism’
http://arxiv.org/PS_cache/quant-ph/pdf/ ... 7057v2.pdf
17 Dec 2011, 11:51 am
