By request, I'm going to share my agnostic take on the origin of the universe. First, let me simplify this as much as possible by pointing out that there are really only two possibilities. I'll discuss them both.
The first possibility is that at one point, there was absolute nothingness. Void. Oblivion. And somehow, the universe simply sprung forth from this oblivion. As of this writing, armed with only our current knowledge and understanding of the universe and how things work, there is absolutely no way to explain how that's possible. And so, typically, this is where the faithful will say "God did it." However, I'm not prone to equate "absolutely no explanation" with "God must have done it." And so my take on this possibility is that it's the less likely of the two.
The second possibility, however, is very difficult for many to accept. The second possibility is that there WAS NO BEGINNING. The universe has simply always been, endlessly cycling through self-destruction and re-creation. If you don't know why I say that, read up on the big-bang theory. It eventually folds back in on itself, the universe collapses and then explodes again, repeating the entire process.
The reason the second possibility is hard to accept is because infinity is beyond human comprehension. It defies our laws of nature that something could have no beginning and no end. It's difficult for us to even imagine such a thing. In our mind, all things MUST have a beginning and an end. Infinity, to our mind, is impossible. And so this possibility is dismissed by most (especially the faithful who, as far as they're concerned, already have a better explanation :P)
So really, it boils down to two equally unbelievable answers. Infinity, or God. To me, it's a simple choice of which of those seems more likely and more believable to you. While I don't dismiss the possibility that there is a God and that he created the universe, I look back on the history of mankind and see us using that same answer to explain earthquakes and hurricanes before we understood those. And so I try to avoid using that answer wherever I have another choice.
And for lack of another explanation of how the universe could spring forth from oblivion, I'm left with the theory of infinity. And while I'm not immune to the disbelief that something could possibly have no beginning, and that all of existence stretches on back for eternity, that still seems to me a more acceptable explanation than the machinations of an all-powerful being (or beings) who can do absolutely anything, imaginable or unimaginable.
Also, just to expand on this a bit more (though the rest of this is a bit more fantastic), the idea of existence having no beginning brings the question of time into the picture. Think about the big bang theory... the universe constantly expanding until it finally begins to implode and recycle itself. We'll ignore, for now, the theories of what could lie beyond the universe's outer limits... pure nothingness. True oblivion... and perhaps, other universes. The possibilities there are endless, and discussing them is for another time and another blog :).
But, with space constantly expanding and imploding like that, it begs the question of what kind of effect that must have. The expansion and compression of space. What side-effects could that cause? What about all the theories about what happens when you bend or fold time and space? Black holes, wormholes, teleportation, time travel. That last one in particular interests me. What if the universe isn't the only thing constantly self-destructing and recycling itself? What if the consequences of bending space like that are creating wormholes and black holes? Wouldn't these holes also be sucked in when the universe implodes?
And so, at the moment the big bang happens again, it wouldn't just be endless matter trapped in there, but countless wormholes as well, constantly pulling matter through themselves. One could argue the possibility that time itself could be affected.... and so what I'm suggesting is, what if every time the big bang recycles itself it's not just repeating the process, but rewinding everything as well? What if time itself is repeating, and every time the big bang recycles, it's all the exact same thing happening over and over again exactly as it has countless times before?
I wonder how many times I've written this blog?