The modern incarnation of this is the so-called 4D cube model of the universe. Again, these ideas only work for those who are willing to completely ignore the facts of computational complexity and the Heisenberg Uncertainty principle.
I think you and I are living in two completely different argument-universes here. :) I'm not arguing that our universe is computable. I'm not arguing that our universe can definitely be modeled as a 4D cube. I'm not arguing that only integers exist. The only reason why I keep using CA models is that they're extraordinarily easy to picture and understand, *and*, since I believe that SASs can exist even in very simple computable universes like CAs, it makes sense to use CA models when trying to probe certain philosophical questions about SASs, physical existence, and instantiation. Quantum physics and the Heisenberg Uncertainty principle are simply irrelevant to the particular philosophical questions that I'm concerned with.
Forget about our own (potentially non-computable) universe for a second. Surely you agree that we can imagine some large-but-finite 3+1D CA (it doesn't have to be anything like our own universe) in which the state of each bit is dependent on the states of neighboring bits one tick in the "future" as well as one tick in the "past". Surely you agree that we could search through all the possible 4D cube bit-strings, discarding those that don't follow our rule. (This would take a Vast amount of computation, but that's irrelevant to the particular questions I'm interested in.) Some of the 4D cubes that we're left with will (assuming we've chosen a good rule for our CA) contain patterns that look all the world like SASs, moving through their world, reacting to their environment, having a sense of passing time, etc.
This simple thought experiment generates some fascinating philosophical questions. Are those SASs actually conscious? If so, at what point did they become conscious? Was it at the moment that our testing algorithm decided that that particular 4D block followed our specified CA rule? Or is it later, when we "animate" portions of the 4D block so that we can watch events unfold in "realtime"? These are not rhetorical questions - I'd really like to hear your answers, because it might help me get a handle on your position. (I'd like to hear other people's answers as well, because I think it's a fascinating problem.)
Anyway, the point that I'm really trying to make is that, while these thought experiments have a lot of bearing on the question of mathematical existence vs. physical existence, they have nothing at all to do with quantum physics or Heisenberg uncertainty. The fact it seems so to you makes me think that we're not even talking about the same problem.
-- Kory
