On Sun, May 15, 2022 at 1:17 AM smitra <[email protected]> wrote: > On 13-05-2022 21:59, Brent Meeker wrote: > > > Right CI doesn't explain the collapse and MWI doesn't explain the > > collapse either but assumes it can be explained without new physics. > > I hypothesize (not assume) that CI+ <non-zero minimum probability> can > > explain the collapse. I don't see any big advantage for MWI here. > > The big advantage is that decoherence is a well researched area of > (mathematical) physics, results like the density matrix becoming > approximately diagonal, and relations between decoherence to entropy > increase making it effectively irreversible are all rigorous results > that are uncontroversial. People may still have objections against the > MWI, but they'll still accept these results on decoherence. >
Yes. And decoherence says that with time, the off-diagonal elements of the density matrix become arbitrarily small. If there is a smallest non-zero probability, then eventually these off-diagonal elements become zero. This reduces the pure state to a mixture. Which is to say that there is a collapse; unitary evolution ceases, and we have reached a classical world. Non-zero minimum probability on its own, however, does not cause a > system to evolve in a non-unitary way. It does when decoherence is taken into account. See the above explanation. Bruce has not omitted anything. Bruce Bruce is omitting something here, > perhaps some limits in which the time evolution operator becomes > degenerate or something like that. But a product of two unitary > transforms is a unitary transform, so the nth power of a unitary > transform is also a unitary transform. There is no ay you can get > anything non-unitary out of this, unless possibly in the limit of n to > infinity. > -- 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/CAFxXSLSqWc3OwbenyDa_-0rjvBYVFqFSQhubXUEu6-Lxsb1XNw%40mail.gmail.com.
