Re: Is the universe computable?

From: Federico Marulli <marulli.domain.name.hidden>
Date: Tue, 4 Nov 2003 17:40:04 +0100 (CET)

Federico Marulli <federico.marulli.domain.name.hidden>

David Barrett-Lennard wrote:
> In the thread "a possible paradox", there was talk about a vanishingly
> small number of "magical" universes where strange things happen.
> However, it seems to me that the bigger risk is that a "normal"
> universe like ours will be the atypical in the ensemble!

I completely agree with you,
but I haven't understood yet why everyone speaking about this topic is
so interested in the number of these "magic universes". I don't
understand what would be the problem! Also if there was only a very
small fraction of these "magic universes" (anyway infinite in number)
there would be a paradox. I believe the point is that we have to
understand if the observers living in this strange part of our
multiverse may be considered just unlucky or, more probably, if we have
to accept the fact that these observers may be perfectly equivalent to
us.

Matt King wrote:
> The fact that physical systems in our universe do obey
probabilistic
> laws like thermodynamics is therefore extremely good evidence that we
> are not in such a 'magical' universe.

but I think this possible explanation carries some problems and I'm
still waiting a Matt answer to my questions:

>Tegmark and other people think that mathematical existence = physical
>existence. But we are saying that there are infinite observers for whom
>the physical evidence always (or almost) contradict the mathematical
law
>of probability. What could these other observers think? Could they
think
>that, by coincidence, the mathematical existence is always (or almost)
in
>contraddiction with physical existence? And, if so, how could they
study
>the universe? Maybe through other "types" of mathematics? May "our"
>mathematics is not so fondamental? May we have "our" mathematics only
>because we live in this part of the multiverse? Or math is truly
universal
>and consequently the assumption "mathematical existence = physical
>existence" is not so truly universal?

What do you think about it?
Federico
Received on Tue Nov 04 2003 - 12:02:11 PST