Re: Devil's advocate against Max Tegmark's hypothesis

From: Russell Standish <>
Date: Thu, 8 Jul 1999 16:01:51 +1000 (EST)

> Higgo James wrote:
> >
> > Let's be clear about the flying rabbit: we have chosen it as a proxy
> > for something very unusual. Otherwise we would have said 'flying bat' which
> > is unusual but not very unusual. So we are really asking, 'why is something
> > we have chosen to be very unusual, very unusual?'. I fail to see the
> > relevance of this piece of circular reasoning.
> >
> > All it amounts to is asking why there is any stability in our
> > observations, and I think you need nothing more than the weak anthropic
> > principle to explain stability.
> I disagree with this, although it is very well put. It is true that
> the question "why is something we have chosen to be very unusual, very
> unusual?" is circular and useless. But that's not the way I read the
> "flying rabbit" problem. Let me try to be precise about the way I
> interpret the problem. I'd very much like it if people could comment
> on this, since I don't feel that I'm very clear, yet, about the
> terminology used on this group, in particular, relative
> strong-Self-Sampling Assumption (SSSA)" and "Strong SSSA" (did you
> really mean "strong strong self-sampling assumption, Bruno?).
> No matter what is meant by the term "existence", one can say that
> there is some number, probably infinite, of conscious observer
> moments in existence. The weak anthropic principle would suggest
> that we find ourselves in a set of those which are "not very special".
> This is the SSA. So the natural next step is to examine the

Actually, this is the strong SSA. The SSA assumes that our birth rank
is not particularly special. Relative strong SSA relates to some kind
of consistency requirement on what observer moments must follow
others. In fact, if you follow the QTI camp, the observer moment you
find yourself in must become increasingly improbable, contradicting
the SSSA.

> properties of ourselves that we can identify, and try to determine if
> that principle holds.
> To define "not very special", we need to establish some kind of
> measure over the set of possible universes, and thus, in theory, over
> the set of all existing observer-moments (I just made the assumption
> that possible == exists, which is a tenent of this group). This
> brings us to the question which was posed in the very first post to
> this group, by Wei Dai: how do we establish this measure?
> Now, one of the properties of our conscious existence which is
> identifiable is that causal relations seem to hold. That is, we don't
> see flying rabbits, because in flying is caused by flapping wings, and
> rabbits don't have wings (to quote Monty Python, they don't so much
> fly, as plummet). But modern physics tells us that causal relations
> only hold in a statistical sense. That is, our science can only give
> relative probabilities that things will happen. This is true in the
> quantum as well as in the classical domain, it's just that in the
> classical domain, the probabilities become ridiculously large (or
> small) depending on the phenomenon that is studied.
> But why should causal relations *seem* to hold at all? This was the
> problem posed by Hume. Why should there be any connectedness between
> one moment of time and another, or between our memories and physical
> reality? It would seem plausible that among the set of all possible
> (hence existing) conscious observer moments, there are a fair number
> that just are, without having been caused by anything, and that are
> in existence in nonsense universes. Even in this universe, there
> is a non-vanishing probability that a rabbit will materialize out of
> the thin air, and fly (for however brief a moment) through the room.
> Why is it be that the probability of this is what it is, i.e.
> extremely low? Granted we picked, on purpose, a scenario which we
> know to be unlikely. But the question is, why are the probabilities
> what they are?
> So the "flying rabbit" problem is just a restatement of the "why are
> there physical laws" question, which has also been debated on this
> list myriads of times. I do agree with Jacques M. Mallah that this
> group desperately needs a FAQ, especially to tie different approaches
> to the same questions together.
> --
> Chris Maloney
> "Knowledge is good"
> -- Emil Faber

Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 7123
Room 2075, Red Centre
Received on Wed Jul 07 1999 - 23:04:20 PDT

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