On Tue, Oct 1, 2019 at 2:50 AM 'Brent Meeker' via Everything List < everything-list@googlegroups.com> wrote:
> On 9/29/2019 6:53 PM, Bruce Kellett wrote: > > On Thu, Sep 26, 2019 at 10:32 AM 'Brent Meeker' via Everything List < > everything-list@googlegroups.com> wrote: > >> I think the alternative is something suggested by Zurek. He shows that >> decoherence plus einselection will make the reduced density matrix strictly >> diagonal, i.e. he solves the preferred basis and derivation of the Born >> rule. Then he suggests, but doesn't really argue, that the universe cannot >> have enough information to realize all the non-zero states on the diagonal >> and so only a few can be realized and that realization is per the Born >> rule. This is what Carroll would dismiss as a "disappearing world >> interpretation"; but it would provide a physical principle for why worlds >> disappear, i.e. branches of lowest probability are continually pruned. >> > > I don't think this is exactly what Zurek is arguing. He mentions > Halliwell, but is concerned more with Quantum Darwism, which is an account > of the records left in the environment by the system, than with the effects > of decoherence on the system itself -- as would be the case if the limits > on environmental information set some probabilities to zero. He says: > > "Copying yields branches of records inscribed in subsystems of E. Initial > superposition yields superposition of branches, so there is no literal > collapse. However, fragments of E can reveal only one branch (and not their > superposition). Such evidence will suggest 'quantum jump' from > superposition to a single outcome...." > > So it is the fact that our access is limited to only fragments of the the > entire environment that leads to the perception of collapse -- our > inability to see the superposition, or to reverse the measurement. If you > take only a portion of the complete state you certainly reduce the pure > state to a mixture. This is not a particularly new position, being in line > with the IGUS ideas of Gell-Mann and others. > > > That seems to be the same as MWI. Our access is limited because we are in > a relative state...so each copy me has limited access. Yet he refers to > "the myth of multiple worlds". > Our access is limited because we are finite beings, with limited information capacity. Sure, you can imagine that the other "relative states" exist in the same way that we do, but I would take the view that since we cannot in principle access these other states, and they can, in principle, have no effect on us and our physics, then they are essentially non-existent. Or rather, their existence is a metaphysical matter, not a subject of physics. There was a time when I thought that MWI might mean more than this, because many MWI enthusiasts claim that many worlds does away with Bell non-locality -- giving a purely local explanation for violations of the Bell inequalities. This, to my mind, was the last gasp of MWI realists -- and that hope has been dashed. First, because Bruno has resolutely been unable to give any such local account, even in MWI; and second, extensive searches of the MWI literature have shown many claims, and also the same number of failed analyses. The final straw came recently when I read David Wallace's 2012 book, "The Emergent Multiverse". In Sections 8.5 and following of that book he confidently proclaims that Everett banishes non-locality, but he totally wimps out on giving any sort of an account, even a half-plausible one. Section 8.7 is one of the most disappointing accounts of Aspect's experiments that I have ever read. So MWI has no practical application -- it is pure metaphysics, and can be relegated to the dustbin of history, along with celestial spheres and phlogiston. 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/CAFxXSLTX_bPywFyYpuGMxmctkYYpTS5U4Ri6EvbGKQGHDmWTqQ%40mail.gmail.com.
