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. 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/CAFxXSLTh9Vbi%2BXrwpuwcuNMAi%2BH5L6kgEaM1BtwKrhshk0DW6g%40mail.gmail.com.
