On Fri, Nov 22, 2019 at 10:50 AM John Clark <[email protected]> wrote:
> On Thu, Nov 21, 2019 at 5:01 PM Bruce Kellett <[email protected]> > wrote: > > *> I can provide many references which claim that Bell did assume >> counterfactual definiteness, and this is the reason why his theorem does >> not apply in many-worlds theory. One prominent example is a paper by >> Baylock (arXiv:0902.3827).* >> > > The abstract says "*The view presented in this paper is that the minimal > assumptions behind Bell's inequality are locality and counterfactual > definiteness*", so if Bell can derive his Inequality from those > assumptions but exparament proves that the Inequality is not true then one > or both of those assumptions must be false. That was Bell's entire point, > he proposed an exparament to determine if the assumptions were true or not. > It turned out they were not. > But my point was that Bell did not assume counterfactual definiteness. All he assumed was that any possible hidden variables were local. So it is locality that is disproven by the experimental results. Nothing about counterfactual definiteness or realism, since Bell did not assume either of these things. > *Baylock thinks that counterfactual definiteness is one of the minimal >> assumptions behind the derivation of Bell's inequality.* >> > > Of course he thinks that, everybody thinks that! > No, not everybody. The most informed and authoritative view is as I have stated it above -- Bell did not assume realism or counterfactual definiteness. In his recent book (Philosophy of Physics: Quantum Mechanics, 2019), Maudlin makes this point as strongly as he can. "Often, when reporting these crucial results, the term 'realist' or 'realistic' is snuck in. Bell, we are told, ruled out all local realistic theories, for example. And that locution strongly suggests that one can avoid non locality and evade Bell's result by saying that 'realism' is what ought to be abandoned. But this suggestion is nonsensical. Bell proves that no local theory, full stop, can predict violations of his inequality. Whether some person's attitude toward the theory is one of scientific realism or not is neither here nor there. If I had my druthers, 'realist' and 'anti-realist' would be banned from these foundational discussions. And in my own book, I have my druthers, so I will not mention these terms again." (Introduction, xiii) > *But Baylock's attempt to show exactly how Bell's supposed assumption of >> counterfactual definiteness led him astray* > > > Led Astray? Bell knew exactly what he was assuming, and Baylock's paper > came out 10 years ago but it might just as well have fallen into a Black > Hole for all the effect it had on the physics community. It wasn't exactly > earth shattering. > Yes, Baylock's paper has not received much attention -- basically because it is obvious nonsense. > *> You equate 'realism' with counterfactual definiteness. That means, of >> course, that quantum mechanics is not a realist theory -- which is a rather >> extreme view, given the empirical success of the theory.* >> > > What the hell?! When quantum physicists use the term "not realistic" it > has a precise technical meaning, they do not mean the theory does not fit > the empirical facts, and they are not talking about a Harry Potter story. > You are entitled to your own opinions. But you are not entitled to your own facts. Physicists do not use the term 'realism' to mean 'counterfactual definiteness'. As Maudlin points out, such abuse of Bell's argument has led to endless stupidity in these discussions. Bruce > John K Clark > > >> To claim that it does not represent reality is a rather absurd claim. >> Maudlin (arXiv:1408.1826) points out that it has become fashionable to say >> that another way to avoid Bell's result and retain locality is to abandon >> 'realism'. I think you have said much the same on occasion. Maudlin goes on >> "But such claims never manage to make clear at the same time just what >> 'realism' is supposed to be, and just how Bell's derivation presupposes it." >> >> I think it is better to stick to the commonly accepted view of scientific >> realism -- the definition I previously gave from Wikipedia. In which case, >> as Carroll and most others claim, many-worlds is the paradigm 'realist' >> approach to quantum mechanics the wave function encapsulates what the >> external world is 'really' like. >> >> Bruce >> > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLTuXWzW0S9wabyA9cwOTL9Y51R9ci9mOw77yN91qK%2B_QA%40mail.gmail.com.
