What was happening before the Big Bang? The biography of Stephen Hawking, co-authored by John Gribbin and Michael White, likes to draw the "North Pole analogy" in answering this one: if you were a few yards from the North Pole and walked due north, pretty soon you would be going south. You can't get any "norther." Similarly, Gribbin and White say, if you had a time machine and set the controls for the Big Bang, it would reach Planck time and then start moving forwards in time again. It reaches a barrier. There simply is no "before."
This is a difficult one to grasp. Time seems so integral to our world that it is hard for us to imagine it simply "beginning" 13.7 billion years ago. Maybe that is exactly the point: that it is integral to "our world." If we were travelling in a spaceship moving at the speed of light, we'd age slower than if we were to stay on earth, as in the famous "twin paradox," for instance.
There was an earnest Bishop long ago, bless him, James Ussher, who read the bible and calculated that the world started at 6pm Saturday 22 October 4004BC. He arrived at this notion by counting all the "begats." I once met a student who was writing a thesis on why he thought Ussher had it right. I don't know who was worse, the student himself, or the faculty that let him pursue such an absurd notion. Oh well, here's to academic freedom I suppose. And the freedom to waste time.
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