On Tue, Sep 5, 2023 at 12:02 AM smitra <smi...@zonnet.nl> wrote: > On 04-09-2023 01:35, Bruce Kellett wrote: > > On Sun, Sep 3, 2023 at 11:37 AM smitra <smi...@zonnet.nl> 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRAH%2Bx8bUk_NihBihdBbgBdbpbFC_hU_oiCfKQJ0T3boQ%40mail.gmail.com.
