On 2 March 2015 at 17:24, Bruce Kellett <bhkell...@optusnet.com.au> wrote:
> Russell Standish wrote: > >> On Sun, Mar 01, 2015 at 07:48:49PM -0800, meekerdb wrote: >> >>> On 3/1/2015 6:29 PM, Russell Standish wrote: >>> >>>> I remain unconvinced that that probabilities are undefined. >>>> >>>> Tegmark gave an interesting version of how to get Born's rule from >>>> MWI, which seemed to have legs. Deutsch gave one based on decision >>>> theory that is admittedly unsatisfying. >>>> >>>> My own derivation simply assumed that observers had measure. The >>>> probability of an outcome is proportional to the measure of the >>>> observers >>>> >>> What's "the measure of the observers"? That's usually where the >>> implicit assumption of Born's rule sneaks in. >>> >>> >> It's not implicit, but quite explicit that observers are drawn from an >> ensemble of all possible observers with an associated >> measure. Somewhat later, we identify that measure with the complex >> magnitude of the QM state vector. It is still problematic that the >> measure turns out to be complex, rather than say quaternionic or >> something more general, though. >> >> I don't see it as implicitly assuming Born's rule, though. The exact >> functional dependence of probability on the observer's state could be >> anything, but it turns out it has to be given by Born's rule (assuming >> Kolmogorov's probability axioms, of course). >> > > In other words, it doesn't appear to avaoid the problem with MWI pointed > out by Dawid and Thebault: > > http://philsci-archive.pitt.edu/9542/1/Decoherence_Archive.pdf > > You effectively assume the Born rule in order to get your ensemble of > observers out of the superposition. Do superpositions still occur in the MWI? I thought they were supposed to be branches (which are perhaps able to recombine) ? -- 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 post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
