On Fri, Oct 16, 2020 at 04:49:35PM +1100, Bruce Kellett wrote: > On Fri, Oct 16, 2020 at 3:38 PM Russell Standish <[email protected]> > wrote: > > On Fri, Oct 16, 2020 at 10:07:32AM +1100, Bruce Kellett wrote: > > > > It is refuted by the idea of unitary evolution in QM. Unitary evolution > means > > that everything is reversible, If new microstates are created as the > universe > > expands, then this expansion cannot be reversed: the creation of such > > microstates gives an absolute arrow of time. This is generally rejected, > > because physicists tend to believe in unitary dynamics. If dynamics are > not > > unitary, then the universe is not governed by the Schrodinger equation, > and > > arguments for the multiverse collapse. > > I'm not sure the last point follows, perhaps you can expand on it. But > it is an interesting argument that the Layzer style "increase in > microstates" > should be enough to prevent a Hawking style "wavefunction of the > universe". > > > I was talking about the Everett-style quantum many worlds. Other types of > multiverse (such as the existence of other cosmological Hubble volumes) are > not > necessarily affected. Hawking's "wave function of the universe" is a definite > casualty if unitary evolution is denied. > > > > Could the ideas be made compatible by have the number of accessible > microstates increasing over time, due to the expansion of the > universe, but that the total number remains constant, or is even > infinite? Or does that place us right back at the original problem of > having a low entropy initial state. > > > I don't really understand this. An infinite number of microstates makes little > sense in standard thermodynamics. >
Quite true. It would have to involve some sort of limiting process, which would definitely be non-standard thermodynamics. But that's never stopped anyone before :). I was more speculating along the lines of the usual way of reconciling irreversible processes with a reversible multiverse. Where the interesting stuff happens in a finite dimensional subspace of an infinite dimensional Hilbert space, but that dimensionality grows in time due to "splitting", or "decoherence" or what have you. -- ---------------------------------------------------------------------------- Dr Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders [email protected] http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- 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/20201016060333.GH6315%40zen.
