Big Bang

[AChimp]

I seem to recall reading about one physicist's theory that if you were to travel in a massive circle around the universe at the speed of light, you could travel through time, depending on the size of the circle. I think he was disproven, though. :/

Another interesting point is that they don't think that the Universe will collapse anymore, but keep expanding and breaking down until it essentially burns out in several hundred billion years.