“The problem of the origin of the laws of physics is an acute one for physicists. Einstein's suggestion that they may turn out necessarily to possess the form that they do has little support. It is sometimes said that a truly unified theory of physics might be so tightly constrained logically that its mathematical formulation is unique. But this claim is readily refuted. It is easy to construct artificial universe models, albeit impoverished ones bearing only a superficial resemblance to the real thing, which are nevertheless mathematically and logically self-consistent.”