Neil Turok offers us a fascinating and mostly comprehensible article on the present state of cosmological investigation into the origin of the universe. Turok writes at Edge where he explains that his own theory is that the universe is embedded in a huge "brane", short for membrane, that sits in space oscillating slowly back and forth (Imagine a huge, flexible pane of plastic suspended in space upon which are tiny dots representing galaxies). At an infinitesimally small distance from our brane there is another which also oscillates very slowly. This second brane is invisible to us because light only travels along our brane. Throughout the infinite past the two branes have collided with each other an infinite number of times, each collision producing an incredible release of energy in an event similar to the Big Bang.
It all sounds very bizarre, but the theory apparently has won a number of cosmologists to its side and may well be the consensus explanation a decade from now. For my part, however, I have a difficult time accepting any theory which posits an infinite number of collisions over an infinite amount of time. I also wonder how these branes come to have the properties they do, but read the article for yourself. It's very well done.
RLC