On Fri, Nov 22, 2024 at 3:23 PM smitra <[email protected]> wrote: > > Bell's theorem says that no local deterministic hidden variable theory > can explain the correlations that QM predicts. So, Bell's theorem > doesn't say anything about QM itself, it says something about hidden > variable theories that seek to explain the correlations observed in QM > experiments. So, you modify QM and assume that QM is explained by a > classical deterministic hidden variable theory and then you obliged to > take non-locality on board, or else your hidden variable theory will > fail to reproduce at least some of the correlations predicted by QM. > > Nothing in here implies that QM is non-local. >
The results of Bell's theorem imply exactly that. Bell assumes that the theory is local, and shows that the QM results violate particular inequalities. The theorem is NOT about non-local theories since Bell does not assume a non-local theory. > Everett introduces the splits as an effective description appropriate > for describing macroscopic observers. He introduces density matrices so > it should be clear that this isnt an exact qjuantum emchancial > description and it will certainly fail to correctly describe subtle > effects due to entanglement. > Density matrices are not an approximate form of QM. There are no independent branches. > That is what decoherence is supposed to give you. > > That is not the case. Everettian quantum mechanics says that they both > > split on to two branches, and there is no clear way in the formalism > > to see how the branches for the two individuals are related. In any > > model, in which both outcomes are necessarily realized for every > > measurement, there is no way to relate the outcomes. > > > > Everettian QM says that this is what effectively happens, but it's > obviously not an exact description and will fail to take into account > subtle effects due to entanglement. > In other words, Everettian QM, or many-worlds, is not able to give an account of the correlations. You are saying that that is because it is not an exact theory. This is a pretty extreme way of getting out of the difficulty that I have pointed out. If Everett is not just a version of exact QM, it is of no use for anything. My claim is that it cannot reproduce the observed correlations, therefore it is not a version of standard QM, and is of no use for anything. 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 visit https://groups.google.com/d/msgid/everything-list/CAFxXSLQMRcefzw1Jfb6VCrkDeaVWZHAtK09BCe_-b%3D9Ho%3DiyFQ%40mail.gmail.com.
