----- Original Message -----
From: "Bruno Marchal" <[EMAIL PROTECTED]>
To: "Saibal Mitra" <[EMAIL PROTECTED]>
Cc: "Jesse Mazer" <[EMAIL PROTECTED]>; "Stathis Papaioannou"
<[EMAIL PROTECTED]>; <firstname.lastname@example.org>
Sent: Monday, November 28, 2005 04:47 PM
Subject: Re: Quantum Immortality and Information Flow
> Le 27-nov.-05, à 02:25, Saibal Mitra a écrit :
> > The answer must be a) because (and here I disagree with Jesse), all
> > that
> > exists is an ensemble of isolated observer moments. The future, the
> > past,
> > alternative histories, etc. they all exist in a symmetrical way. It
> > don't
> > see how some states can be more ''real'' than other states.
> But then how could we ever explain why some states seem to be more
> *near*, or more probable than others from our point of view?
Well, even if you assume ''ordinary'' laws of physics, you can have this
view. Einstein tried to console a friend whose son had died, by saying that
although he isn't alive now, he is ''still'' alive in the past. Relativity
theory threats space and time in more or less symmetrical ways.It doesn't
make any difference if you assume that you are sampled from a probability
distribution (to be calculated from physics) over your experiences.
> Is the choice between Papaioannou's "a", "b" reflecting(*) the ASSA
> and RSSA difference?
> Recall: ASSA = absolute self-sampling assumption. RSSA = relative
> self-sampling assumption.
> (*) Stathis Papaioannou writes:
> > If on the basis of a coin toss the world splits, and in one branch I am
> > instantaneously killed while in the other I continue living, there are
> > several possible ways this might be interpreted from the 1st person
> > viewpoint:
> > (a) Pr(I live) = Pr(I die) = 0.5
> > (b) Pr(I live) = 1, Pr(I die) = 0
> > (c) Pr(I live) = 0, Pr(I die) = 1
> > Even on this list, there are people who might say (a) above is the case
> > rather than (b) or (c).
> > So, you must think of yourself at any time as being randomly sampled
> > from
> > the set of all possible observer moments.
> This could make sense in a pure third person perspective, but then it
> is no more a perspective. And, indeed, to predict the result of
> anything I decide to test, I need to take into account relations
> between observer-moments. Let me throw a dice. Are you saying to us
> that to predict the result I need to take into account all
> observer-moments and sample on them in some "uniform" way. Why should
> people buy lotto-tickets? They could make the big win by their OM being
> sampled on all OMs.
> I'm not saying you are false, but your absolute sample does not
> correspond tour first person experience (including physics) which we
> want to explain. It seems to me.
Well, the probability distribution has to be consistent with physics. In
case of throwing a dice, one should consider the set of OMs that are
experiencing the outcome of the throw.
> > To get to answer b) you have to
> > redefine your identity so that experiencing having done the experiment
> > becomes a necessary part of your identity.
> Not some absolute identity, but memories are part of our relative,
> mundane, identity.
> > But this is cheating because you
> > wouldn't say that if ''death'' were replaced by a partial memory
> > erasure
> > such that the experience of having done the experiment were wiped out
> > form
> > your memory.
> OK, but that is why the experiment is proposed with (absolute) death
> (if that exists) and not with memory erasure. This could change the
> probabilities a lot, and this can admit many different protocol for
> verifying the probability distributions. It is another experiment.
> Perhaps I miss your point.
Yes, that was my point. The probabilities become sensitive to the details of
the set up in a way that I find unphysical. If we just do conventional
quantum measurement of z-component of a spin polarized in the x-direction.
Then, in the MWI, you would say that there exists a world in which an
observer sees spin up and a world in which spin down is experienced.
Strictly speaking the two observers are not identical. Let's now modify the
experiment so that in case of spin down the observer is annihilated and
replaced by some arbitrary person. Then if we choose this person to be
''close'' to the original person then the probabilities are 1/2, but if I
move sufficiently ''far away'' from the person then it should somehow jump
to 1 for the original person.