Originally Posted by tore

I don't fully agree here. According to the The Big Bang theory, our universe started with a "big bang" (or rapid expansion rather), but predicting what happened before that when you have all the matter of the universe in one place is not really simple. We don't know how the laws of physics would behave in such a place and explaining how they did may be outside the scope of physics. Who can really say that something like a big crunch didn't happen first that put all the universe's matter in that one place?

Perhaps there are many good arguments physicists could raise, but as far as I know, a big crunch preceding a big bang is still a valid hypothesis.