Re: Tegmark is too "physics-centric"

From: Hal Finney <hal.domain.name.hidden>
Date: Sat, 17 Jan 2004 16:48:40 -0800

Eric Hawthorne writes:
> 2. SAS's which are part of a 3+1 space may not have higher measure than
> SAS's in other spaces, but perhaps the SAS's
> in the other spaces wouldn't have "a decent way to make a living". In
> other words, maybe they'd have a hard time
> perceiving the things in their space, existing coherently "physically"
> in it, being able to "incrementally impact and survival-optimize"
> their surroundings in the space etc.
> In other words they'd be inhabiting (and trying to perceive and act on)
> a world of NOISE, or of LIMITED DEGREES OF FREEDOM AND EVOLUTION,
> or of UNRULY, untameable hyperbolic physical laws and functions.

I agree that this is what Tegmark is trying to say. If we look at it
in terms of measure, there are (broadly speaking) two ways for creatures
to exist: artificial or natural. By artificial I mean that there could
be some incredibly complex combination of laws and initial conditions
built into the simulated universe so that the creature's existence was in
effect pre-ordained. (If we ever build a simulation containing conscious
entities, our first attempts will almost certainly be of this type,
where we have carefully crafted the program to create consciousness.)
By natural I mean that we could have simple laws of physics and initial
conditions in which the creatures evolve over a long period of time,
as we have seen in our universe.

Universes of the natural type would seem likely to have higher measure,
because they are inherently simpler to specify. It is in those universes
where Tegmark's physics-based arguments come into play. For creatures
to evolve, to become complex, to optimize for survival, things like
dimensionality are very relevant. Tegmark goes into some detail on the
problems with other than 3+1 dimensional space.

Of course, there's always a risk in such arguments that we may be falling
victim to parochialism, thinking that our own way of life is the only
one possible. It may be that there are some possible life forms that
exist in a very different mode than we have imagined, in a universe with
different dimensionality, or perhaps one where dimensionality doesn't
even make sense. But I think overall Tegmark does a good job in avoiding
at least the most obvious flaws of parochialism and anthropomorphism.

Hal Finney
Received on Sat Jan 17 2004 - 19:50:17 PST