Tegmark is too "physics-centric"

From: Kory Heath <kory.heath.domain.name.hidden>
Date: Sat, 17 Jan 2004 05:09:27 -0500

I greatly enjoyed Tegmark's "Is 'the theory of everything' merely the
ultimate ensemble theory?", and there are parts of it that I agree with
wholeheartedly (for instance, his arguments against the idea that the AUH
is "wasteful"). However, whenever he talks about the testability of the
AUH, his views seem unjustifiably physics-centric to me.

For instance, he seems impressed by the fact that versions of our physics
with more than 3 dimensions are insufficiently stable to support atoms (and
presumably, therefore, self-aware substructures), and those with less than
3 dimensions are insufficiently complex to support SASs. These are
interesting facts, but I fail to see their importance when you consider the
entire ensemble of possible mathematical structures. For instance, consider
the infinitely many cellular automata that exist in the Mathiverse. We know
of very simple 1D, 2D, and 3D cellular automata that are computation
universal, and therefore (I believe) capable of containing SASs.
Undoubtedly there an infinite number of 4D cellular automata that are
computation universal and contain SASs that perceive their surroundings as
4D. Ditto for CA with dimensions higher than 4.

Perhaps it's true that within the ensemble of all quantum-physical
universes in Mathspace, only those with 3+1 dimensionality contain SASs.
But what possible reason do we have for believing that these SASs (or the
observer-moments of those SASs) have a greater measure than those in the
ensemble of all cellular automata?

-- Kory
Received on Sat Jan 17 2004 - 05:12:07 PST