> On 9 Feb 2020, at 05:40, Bruce Kellett <[email protected]> wrote: > > On Sun, Feb 9, 2020 at 2:33 PM 'Brent Meeker' via Everything List > <[email protected] <mailto:[email protected]>> > 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.
Because as long as you have not distinguish a branch, you belong simultaneously on all the branches. It is more a differentiation than a branching (both in arithmetic and with the SWE). Bruno > 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 [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/CAFxXSLRX_voaHipakw9qdv2MPQuzYxRvTU1oNC83BhDqPKkm2g%40mail.gmail.com > > <https://groups.google.com/d/msgid/everything-list/CAFxXSLRX_voaHipakw9qdv2MPQuzYxRvTU1oNC83BhDqPKkm2g%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- 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/1931B5E5-92D2-4111-B929-0559E30E0A96%40ulb.ac.be.
