On Tue, Sep 5, 2023 at 12:02 AM smitra <[email protected]> wrote: > On 04-09-2023 01:35, Bruce Kellett wrote: > > On Sun, Sep 3, 2023 at 11:37 AM smitra <[email protected]> wrote: > > > >> The time evolution according to > >> the Schrödinger equation is manifestly local, > > > > But unitary evolution according to the SE cannot account for the > > correlation of entangled particles. > > > > It can, just calculate it and don't collapse the wavefunction.
OK. So show me this calculation that gives a local explanation of the correlations. >> Another important thing to note here is that Bell's theorem only > >> applies to hidden variable theories, it does not apply to QM in general. > > > > Where on earth did you get that idea from? As John has pointed out, > > Bell's theorem does not require even quantum mechanics. It is just a > > piece of mathematics.It applies with complete generality to quantum > > mechanics, with or without hidden variables. > > > > Bell's theorem is about local hidden variables theories It is difficult to know how to respond to this absurd idea. I have read quite extensively on Bell's theorem and locality in quantum mechanics and I have never met this contention before. Maybe 'scerir' has some reference to it, but I have never seen such a suggestion. The point, it seems to me, is that Bell's theorem concludes that any hidden variable completion of quantum mechanics must be non-local. Since standard QM has no explanation for the correlations, it might be supposed that some hidden variable completion of the theory would work. However, Bell shows that even such a hidden variable completion of the theory must be non-local. But this is the case for any formulation of quantum mechanics -- one does not have to assume the existence of hidden variables in order to derive the Bell inequalities. The standard formulation of quantum mechanics explains the correlations non-locally. There is a simple argument for non-locality: A) All local systems are separable (factorizable). Hence all non-separable (non-factorizable) systems are non-local. The entangled singlet state is non-separable. Therefore it is non-local. What conclusions can we draw? If we assume that QM is not fundamental > and that there exists a hidden variables theory that reproduces QM > either exactly or to a good approximation, then we can conclude that > such a hidden variables theory cannot be local. > > Or we can conclude that QM is fundamental and that there is no deeper > hidden variables theory underlying QM. In this case the violation of > Bell's inequality does not imply non-locality. However, collapse is then > still a non-local mechanism. > If QM is fundamental and complete, then it must contain a local explanation of the Bell correlations. No-one has ever been able to produce such an explanation. Reality is, therefore, fundamentally non-local. > Again, As I pointed out to John, even if you assume that Bell's > > theorem does not apply to MWI (and of course it does), then it does > > not follow that the theory is local. It could be non-local for reasons > > unconnected with Bell's theorem. > > > Yes, but the only source of non-locality is collapse. Once you get rid > of collapse, the theory becomes local, because the Standard Model is a > local theory. > And the standard Model (with or without collapse) cannot explain the Bell-type correlations. You seem to pretend that it's a theorem of QM, in which case one would > start from the postulates of QM and derive bounds on correlations for > any system described by a local Hamiltonian. That's obviously not true. > Strange, then, that John Bell managed to do that. 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/CAFxXSLRAH%2Bx8bUk_NihBihdBbgBdbpbFC_hU_oiCfKQJ0T3boQ%40mail.gmail.com.
