Re: Probability

From: rmiller <>
Date: Thu, 06 Nov 2008 14:45:07 -0600

At 10:54 AM 11/6/2008, Bruno Marchal wrote:

>On 06 Nov 2008, at 02:37, Thomas Laursen wrote:
> >
> > Hi everyone, I am a complete layman but still got the illusion that
> > maybe one day I would be able to understand the probability part of MW
> > if explained in a simple way. I know it's the most controversal part
> > of MW and that there are several competing understandings of
> > probability in MW, but still: none of them make sense to me! If every
> > line of history is realized then how can any line of history be more
> > probable than any other?
>Wolf's answer is probably correct, but certainly incomplete. If you
>take QM (without collapse) norma distribution and measure can be
>extracted from Gleason theorem. Born rule can be deduce from first
>person indeterminacy or more politically correct variant through
>decison theory (like Deutsch and Wallace). It is a whole field. My
>point in this list consists to show that if you assume the mechanist
>thesis (like Everett) then even if Deutsch proposal works it is not
>enough to justify the probabilities. There is a big work which remains
>to be done, but it has the advantage of taking into account the non
>communicable part of the experiments (usually known as "the
>experience"). But there are more abherant histories to evacuate (like
>infinities in field theories).
>Anna Wolf's answer can be wrong in case physics is eventually purely
>discrete, in which case probabilties should arise from pure relative
>proportion based on dircrete relative partitioning of the multiverse.
>I think the comp hyp excludes this though, like I think M theory, as
>far as I grasp something there, too. Loop gravity, if literally true,
>could lead to such ultimate discretization or provide models.
>For each position of an electron in your brain there is a (quantum)
>computational history going through that state, and probabilities are
>eventually all related self-indiscernibility relations (if it is
>Bruno Marchal
>First of all, Bruno, that answer seemed Palenesque in the extreme,
>even for someone whose job it is to know this stuff. The
>correspondent indicated his was a layman's perspective. How about
>another go at it without shortcut references to Born, David Deutsch,
>Wallace (who?) et al. As a firm believer in the adage that one who
>really knows the subject should be able to explain it in such a way
>that a bright ten-year-old can understand the concept.

>R Miller


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Received on Thu Nov 06 2008 - 15:45:22 PST

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