What examples can you give of books that contain discussions of advanced (graduate or research-level) mathematics, similar to what Greg Egan does in his novels (I suppose the majority of such books are hard sci-fi, though I'm not betting on it)? I'm trying to find out what has already been done in the area.
There's this in mathematics. Also, this website might be a good place to look, though most of its examples seem less advanced than what you are looking for.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.