Kory Heath wrote:
Well here's the thing: The onus on you is to produce a "physical theory" that describes some subset of the computations of a 4D CA
Tegmark goes into some detail on the problems with other than 3+1 dimensional space.
Once again, I don't see how these problems apply to 4D CA. His arguments are extremely physics-centric ones having to do with what happens when you tweak quantum-mechanical or string-theory models of our particular universe.
and which can explain (or posit or hypothesize if you will) properties of observers (in that kind of world), and properties of the space
that they observe, which would be self-consistent and descriptive of "interesting, constrained, lifelike behaviour and interaction
with environment and sentient representation of environment aspects" etc.
My guess is that that physical theory (and that subset of computations or computed states) would end up being proven to
be essentially equivalent to the physical theory of OUR universe. In other words, I believe in parochialism, because
I believe everywhere else is a devilish, chaotic place.
You can't just say "there could be life and sentience in this (arbitrarily weird) set of constraints" and then not bother to
define what you mean by life and sentience. They aren't self-explanatory concepts. Our definitions of them only apply
within universes that behave at least roughly as ours does.
You'll have to come up with the generalized criteria for generalized N-D SAS's (what would constitute one)
before saying "they could exist."