Just to throw in a wobbly.
If you're into reading about the subject, try an alternative view by reading "The Big Bang Never Happened" by Eric J Lerner.
He claims a plasma-based motivating force, as opposed to gravity, for the evolved universe.
Personally, I incline to the old steady state theory of continuous creation, never having started, never ending.
The idea of running the universe backwards to explain its origin has always struck me as a naive concept.
Nature isn't linear like that, usually something happens to change all the rules. For instance, heat up a bar of metal and it gets longer in relation to the heat applied. But keep doing it and what happens? It melts and becomes a liquid. Heat it still further and it evaporates. Now its a gas.
Similarly, I can't believe that you can compress the universe homogeneously all the way to a pinpoint with it changing gear, so to speak.