Re: Many Pasts? Not according to QM...

From: aet.radal ssg <>
Date: Thu, 26 May 2005 11:02:19 -0500

For some reason I didn't get the original post about the suicide paradox, so if someone could resend it, sans any "everything" computer lingo, I would appreciate it.

The subject of the thread - "Many Pasts? - Not according to QM"  taken on its face seems false, at least from the standard MWI model. If you have parallel worlds you have parallel pasts. In fact, that's why MWI is supposed to be the solution to time travel paradoxes. Take an arbitrary moment, when a measurement, or any other trigger, causes a decoherence, move forward in time from that moment and look back - you have parallel pasts that begin from the point of decoherence.

----- Original Message -----
From: "Saibal Mitra"
Subject: Re: Many Pasts? Not according to QM...
Date: Wed, 25 May 2005 01:24:23 +0200

> ----- Oorspronkelijk bericht -----
> Van: "Patrick Leahy"
> Aan:
> Verzonden: Wednesday, May 18, 2005 05:57 PM
> Onderwerp: Many Pasts? Not according to QM...
> > Of course, many of you (maybe all) may be defining pasts from an
> > information-theoretic point of view, i.e. by identifying all
> > observer-moments in the multiverse which are equivalent as perceived by
> > the observer; in which case the above point is quite irrelevant. (But you
> > still have to distinguish the different branches to find the total measure
> > for each OM).
> This is indeed my position. I prefer to define an observer moment as the
> information needed to generate an observer. According to the ''everything''
> hypothesis (I've just seen that you don't subscibe this) an observer moment
> defines its own universe. But this universe is very complex and therefore
> must have a very low measure. It is thus far more likely that the observer
> finds himself embedded in a low complexity universe.
> One of the arguments in favor of the observer moment picture is that it
> solves Tegmark's quantum suicide paradox. If you start with a set of all
> possible observer moments on which a measure is defined (which can be
> calculated in principle using the laws of physics), then the paradox never
> arises. At any moment you can think of yourself as being randomly drawn from
> the set of all possible observer moments. The observer moment who has
> survived the suicide experiment time after time after time has a very very
> very low measure.
> Even if one assumes only a single universe described by the MWI, one has to
> consider simulations of other universes. Virtual observers living in such a
> simulated universe will perceive their world as real. The measure of such
> embedded universes will probably decay exponentialy with complexity....
> Saibal


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Received on Thu May 26 2005 - 12:11:57 PDT

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