Expert: Steve Nelson - 11/5/2010

Question
I am having trouble understanding the big bang. How was it the beginning of time? If their was no time, then how could the big bang take occur in the first place? I was also thinking that we if represent time linearly as y=x, then it only makes sense that if time will continue on infinitely, then it should continue infinitely forward, too. Next, could scientists' perceived expansion of the universe just be because of our point of perspective on earth? Finally, if the universe is expanding, what is outside the point of expansion?

Answer
You really need a whole brief course on cosmology, hopefully with a lot of physics to back it up.  We project the history of the universe based on known physics and observation.  That projections leads us to the conclusion of the Big Bang.  No one ever said it was the definite "beginning of time," but our physics does not project beyond that point because we have no theoretical framework to do so.  Therefore, as far as we understand *now*, the Big Bang is the furthest back in time that we can understand.  Our point of observation is quite irrelevant to the observation of the expansion of the universe, however that is a very difficult concept to explain on such a limited forum.  There is nothing outside the universe, that we can define, it's a common misconception to try to define points in space where space is not defined.