Original Message -----

From: "Saibal Mitra" <[EMAIL PROTECTED]>

To: "Stathis Papaioannou" <[EMAIL PROTECTED]>

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

Date: Fri, 27 May 2005 14:29:07 +0200

>

> ----- Oorspronkelijk bericht -----

> Van: "Stathis Papaioannou" <[EMAIL PROTECTED]>

> Aan: <[EMAIL PROTECTED]>

> CC: <[EMAIL PROTECTED]>;

> Verzonden: Friday, May 27, 2005 01:44 AM

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

>

>

> > Saibal Mitra wrote:

> >

> > >Quoting Stathis Papaioannou <[EMAIL PROTECTED]>:

> > >

> > > > On 25th May 2005 Saibal Mitra wrote:

> > > >

> > > > >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.

> > > >

> > > > I'm not sure what you mean by "the paradox never arises" here. You

> have

> > > > said

> > > > in the past that although you initially believed in QTI, you later

> > >realised

> > > >

> > > > that it could not possibly be true (sorry if I am misquoting you, this

> > >is

> > > > from memory). Or are you distinguishing between QTI and QS?

> > > >

> > >That's correct. In both QTI and QS one assumes conditional probabilities.

> > >You just

> > >throw away the branches in which you don't survive and then you conclude

> > >that you

> > >continue to survive into the infinitely far future (or after performing

> an

> > >arbitrary

> > >large number of suicide experiments) with probability 1.

> > >

> > >But if you use the a priori probability distribution then you see that

> you

> > >the measure

> > >of versions of you that survive into the far future is almost zero.

> >

> > What does "the measure of versions of you that survive into the far future

> > is almost zero" actually mean? The measure of this particular version of

> me

> > typing this email is practically zero, considering all the other versions

> of

> > me and all the other objects in the multiverse. Another way of looking at

> it

> > is that I am dead in a lot more places and times than I am alive. And yet

> > undeniably, here I am! Reality trumps probability every time.

>

>

> You have to consider the huge number of alternative states you could be in.

>

> 1) Consider an observer moment that has experienced a lot of things. These

> experiences are encoded by n bits. Suppose that these experiences were more

> or less random. Then we can conclude that there are 2^n OMs that all have a

> probability proportional to 2^(-n). The probability that you are one of

> these OMs isn't small at all!

>

> 2) Considering perforing n suicide experiments, each with 50% survival

> probability. The n bits have registered the fact that you have survived the

> n suicide experiments. The probability of experiencing that is 2^(-n). The

> 2^(n) -1 alternate states are all unconscious.

>

>

> So, even though each of the states in 1 is as likely as the single state in

> 2, the probability that you'll find yourself alive in 1 is vastly more

> likely than in 2. This is actually similar to why you never see a mixture of

> two gases spontaneously unmix. Even though all states are equally likely,

> there are far fewer unmixed states than mixed ones.

>

> Saibal

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