I am not a scientician, nor do I have even the slightest illusions of thoroughly understanding physics. That said, if you are reasonably literate on such matters and you want to have your mind positively fucking blown out of both ears and your nose at the same time, watch Prof. Brian Greene give a lecture describing Superstring Theory in (relative) layman's terms.

I was pretty good at the hard sciences as a younger person, including physics, but I hit a road block when exposed to theories beyond relativity. Perhaps my mind is too linear (or not linear enough). I simply can't comprehend things getting shorter and more massive when they move, particles traveling back in time, multiple dimensions, and parallel universes. I am unequipped mentally to handle academic endeavors based on fundamental but unexplained, and possibly inexplicable, phenomena. There is something comforting about a field in which, whenever we get stumped, "Because people are stupid" serves as an effective all-purpose explanation.