Well I'm just going to leave mine here for now. I like the idea of learning more about field theory, because that seems to be one of those topics that is really central to a lot of physics. Symmetry would be another key concept that I'd like to hear more about. On that note, a couple of more specific physics questions come to mind.
I've read/heard on a number of occasions that electric and magnetic forces have been unified into a single fundamental force, which we call the electromagnetic force. Likewise, these together with the weak force have been unified into the electroweak force, and efforts are being made to unify these with the strong nuclear force and gravity. It's never really become quite clear to me what that means. Does it mean that the forces literally become the same single force at the unification energy? If they are at that point completely indistinguishable, what is it that physicists think initially broke the symmetry between them during the early moments of the universe? That is, why did they "fracture" into separate forces? Were they really distinct all along, but just not measurably so? And finally, I've heard vague explanations of this, but perhaps you guys know a clearer answer: why is it so much harder to unify gravity and the strong/color force with the others?
Here's another one that I don't think I have a good handle on: What, if anything, "is" completely empty space, if you take away all the things in that space such as the matter and the fields that permeate it? Can such a thing even exist, or does space only exist by the grace of the things (clearly not matter, but maybe fields?) that are in it? If we can talk about spacetime, does that mean that time is the same kind of "thing" as space, except that we can only move through it in one direction? If not, what's the difference?