Expert: Courtney Seligman - 8/5/2010

Question
Which of the following first created , big bang or space time?

Answer
As noted in my previous answer, our Universe presumably formed as the result of a quantum fluctuation at a single point of space-time in some previous Universe. As a result, there are two answers to your question.

The first answer, which I think is what you are getting at, is that at the moment of the Big Bang, there was only a single point of space-time, of zero size. That is, there was no space or time before that point in time, so the Big Bang was the start of everything (in our Universe), and all of space-time as we currently observe it was created as a result of the Big Bang. In this way of thinking about things, the Big Bang comes first, and then the rest of space-time.

The second answer is that, since our Universe was created from a point of space-time in a previous Universe, there was an infinite amount of space-time which existed before the Big Bang. However, because our Universe is completely separate from the one which "created" it, none of that space-time could ever be observed from our Universe -- not even at the moment of its creation, let alone anytime after that. In this way of thinking about things, there is as much or more space-time before the Big Bang, as after; but since there is no way to observe any of the "prior" space-time, for all practical purposes, it doesn't exist (at least, not in our Universe, or in any observable way).