Which areas of computer science have lots of overlap with physics? I'm an undergrad in computer science but I've always loved physics and its ability to constantly amaze and surprise us about our world. I am wondering if there are areas in graduate level computer science that one can get into which involve a lot of work on physics. The one I know of that is talked a lot about is Quantum computing. I've also heard of information theory, which involves the study of thermodynamics. Which other ones are there?
[The following is more an extended comment with pointers than a real answer.]

If you were in France, a good answer would be combinatorial physics.  I say "if you were in France" because, for reasons that escape me but that must be mostly historical, in France combinatorics is considered part of theoretical computer science :-)  In the rest of the world, combinatorics is considered to be a branch of mathematics, so I guess it is more correct to say that combinatorial physics is about interactions between physics and discrete math, rather than CS.

Anyway, in my lab (which is a CS lab) there's a research group which focuses on several aspects of combinatorics, in particular combinatorial physics.  This is by no means the only example in France of a combinatorics group in a CS lab whose research overlaps with physics; another example off the top of my head is this one in Bordeaux. Some of the members of these groups are theoretical physicists.

The "official" recognition of combinatorial physics as a research field of its own is very recent, as you may read in this blog post, which contains some pointers and basic info about it.  Computer science is explicitly mentioned a couple of times, although maybe not exactly in the sense you would expect, but I am sure that my colleagues from those research group would be able to give you more precise answers.  Maybe you can start checking out their web pages for additional info.