I've been wondering about this for a while, and it could make for an interesting discussion (or a stupid one if the answer is obvious, but it isn't to me). My question is, is there good reason to think that Physics is unique? Now, obviously this question is impossible to answer because we do not even have a complete discription of nature yet - i.e. both the Standard Model and GR are known to be incomplete. However, assuming some complete description of nature does exist, which has absolute predictive power for any possible observation or measurement we choose to make (within certain limits on computability of course), then is it reasonable to expect that that description will be a unique one? It seems to me that it may be possible for there to be many theories which will agree to within any possible experimental precision, but which make fundamentally different assumptions about the basic aspects of nature, and which are different in their mathematical structure. If we could program a bunch of computers with the brilliance of Newton, and gave them each a vast array of experiemental data, would they each produce their own version of Physics? I'm inclined to think so, but it could be that it is necessary that there if there exists a complete mathematical desciption of nature, then it is a unique one. Perhaps this is closely related to the question of the "reality" of mathematics, which may border to close to Philosophy, if this thread doesn't already.