Hi Stephen,
Can atoms exist in a 2D universe?
I remember having read that 17 sort of atoms can exist in some natural 2-dimensional QM. I don't know if this is related to the anyons and Hall effects where particles are squeezed in two dimensional trap (by powerful magnetic field).
I have independent reason that the 2-dim topological space (and 2 + 1) continuous deformation are quite important in fundamental physics. But this has not yet been extracted from comp (to be sure).
AFAIK, physics is very different when constrained to only 2D. My point is that the notion of computation is meaningless if there is no possibility of a stable structure on and in which to implement the computation.
This is false imo. A computation can be given a sense in pure arithmetic (if only by Godel's arithmetization device).
If you postulate a physical universe at the start, you need to postulate some ad-hoc highly non comp thesis to attach the first person to it.
Platonic Numbers or bit-strings have no ability to do anything by themselves (by definition!)
But numbers can do things by themselves relatively to other (universal) numbers. That is what computer science is all about, I think.
and thus appeals to their existence are vacuous.
? Best regards, Bruno http://iridia.ulb.ac.be/~marchal/
