Mathematics works with Mathematics. It can be corresponded to
   the physical Universe very successfully. Hence, it is very
   useful in Physics, even in fantasy physics.

   But if I draw a picture of a cat, no mater how sophisticated,
   it's not a cat. The Universe isn't Math, no matter what Tegmark
   says. It may be very well described by math - extremely well,
   but they're still distinct. Of course. Mathematics is very
   pragmatic. So is heuristics. They're tools humans use to help
   describe and shape reality.