I'm torn between self interest and forcing myself to learn different things which would be good for me. I'm debating to look at fundamental problems in Quantum Mechanics... like sort of why we look at psi^2 and not some other psi. This is what I'm really interested in. The other project is on "Dumb Holes" or Unruh's Dumb Holes. I'd be working experimental and modelling the fluid aspects of it. It's the fluid analog of black and white holes. I haven't taken GR or fluids so I'd be forcing myself to learn things which I don't mind too too much but I don't know... Any advice? Both are with the same professor.