On Sun, Feb 9, 2020 at 2:33 PM 'Brent Meeker' via Everything List < everything-list@googlegroups.com> wrote:
> On 2/8/2020 6:53 PM, Bruce Kellett wrote: > > But it is implicit, or even explicit in Bruno's model. It's also >> consistent with Barbour's model. >> > > It can be consistent with as many models as you like. It is simply not > Everettian QM. It is some ad hoc concoction that totally undermines the > point that was the basic attraction to Everett in the first place. People > like Carroll and Wallace laud Everett because they see it as quantum > mechanics in the raw -- the Schrodinger equation without extraneous > additional assumptions. You seem bent on adding all these extraneous > assumption, most of which are not even consistent with the Schrodinger > equation, and still claim that you are talking about the same model. > > > I think Everett assumed Born's rule as a kind of weight attached to each > branch; so there was only one branch per result and the Born rule was > assumed. > Well, Everett did have something that he considered a derivation of the Born rule. He looked for a weight to attach to each branch and assumed that it was a function of the branch amplitudes. The squared modulus of the amplitude gave an additive measure that he took as a probability. But the argument that I have given shows that attaching such a measure or weight to each branch achieves nothing, since the branching structure with one branch for each component of a superposition does not leave any room for such a label attached to each branch to have any operational effect. Whatever label one attaches to branches, one still gets the same set of branches and the same limitations apply. It is only later that the purists, who wanted to say MWI is only the > Schroedinger equation, have undertaken to prove the Born rule follows from > it with only some "obvious" additional assumption (like the decision > theoretic "proofs"). As far as I know, all of them have begged the > question in that their additional obvious assumption is no better than just > assuming the Born rule...which at least follows from Gleason's theorem once > you assume the theory returns a probability. > I agree that the purist attempts to derive the Born rule from the SE plus some simple assumptions have generally failed. Adrian Kent and David Albert have devoted some effort to showing how they failed -- especial the Deutsch-Wallace ideas based on decision theory. But this is a bit beside the point too. My main concern was to show that the basic Everett idea with one branch per possible outcome does not lead to a viable physical theory. The full details are given in the excepts from Adrian Kent that I started this discussion with. 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/CAFxXSLRX_voaHipakw9qdv2MPQuzYxRvTU1oNC83BhDqPKkm2g%40mail.gmail.com.
