Well, there's a bunch of hypotheses. I can't remember where I read it, exactly, but one summed it up perfectly; our minds are simply just not capable of understanding the way the universe came to be. In all likelihood it has something to do with dimensional stuff. We can't really comprehend a world in five dimensions or six dimensions or what have you because we simply don't exist in such a state, just as a creature of two dimensions couldn't comprehend our third.
At least, not with present science, we can't.
At least, not with present science, we can't.