The leading theory right now comes from M-Theory. You can read up on it with some search on the internet but you will quickly discover that unless you have one helluva a good education it gets pretty high over your head very quickly.

In short the theory states that two membrane walls from other universes collided and the energy from the collision resulted in another universe (ie ours). There are a number of things which support M-theory the most practical of which is the fact that the formulas which have been worked out to accompany it have been applied to other problem areas of science such as the weakness of gravity and the result is that a number of previous problems can be gracefully explained by M-Theory.

They have either recently or will soon send up a deep space probe in an attempt to measure background radiation. Basically M-Theory makes a bunch of predictions about the types and levels of background radiation that would have to be present and up until recently we didn't have equipment sensitive enough to measure for it. Now that we do we also need to get the equipment far enough away from not only earth but our solar system in order for that reading to be clean from interferrence. Ideally within 5 to 6 years we could have an up or down confirmation on the whole matter.

There is simply too much information to go into in this format but if you're interested and motivated enough you can easily lose 2 years worth of weekends and late nights in this stuff. Quite fascinating really, but very very complex and ridiculously math intensive.

Oh, here is a great source for discussion on these topics:

http://www.scienceforums.net/forum/

A lot of very smart folks on those forums and just about anything math and science based is game. Just remember to be respectful and gracious for the assistance, my experience is that they don't put up with a lot of crap from new members.

I'm going to go to that site and start a thread about Videogame sales

If you want to learn about the universe and things like that but don't want to be giving too many details that you won't understand watch the show "The Universe" it has alot of things about space. The other day there was an episode about dark matter/dark energy. This discovery could determine how and even when the universe will end.

 LoL Well I think this thread was inspired by the Evidence That God is Real thread. 

@dtekdahl00

Strangely enough quantum physics has a very round about answer to that. The expansion, by the way its not an explosion its an expansion there was nothing to explode in. It wasn't a point in space time it was all matter, energy, and space time collapsed into a very small point.

The explanation Quantum Mechanics seems to give us is this. The expansion is a byproduct of a mathematical probability. Technically anything that can happen will eventually happen. The probability is never zero, and if it take a trillion times the life span of our universe it still could happen today or tomorrow, or end up having happened yesterday.

Frankly I put more stock in the more modern theories, but the anarchist in me finds something quixotic about the notion that, because something can happen it eventually must happen. Ironically if there was a clock going on during all of this. Nobody was there to watch it so it seems completely timely to us. Like someone waiting twenty years in a room waiting for you to show up. When you come in the timing seems sublime to you, and you can't really appreciate that the person actually spent twenty years waiting for you to come along.

There really isn't a satisfying answer I am afraid. We are still chasing the chicken and the egg analogy. Even if you spin up alternate universes you still have to justify those universes, and how all the universes got spun up in the first place. By invoking probabilities, or multiple universes, or whatever new theory comes along you just seem to refine and push back the clock a few more inches until you have to explain the next chain in events.

Thanks Dodece, thats a pretty well explained response and logical.

In fairness a multi-verse could in and of itself explain it all on its own. Making the assumption that the laws of our universe prevail across a multi-verse is very likely a false assumption. There very well could be a universe with laws that could feasibly explain a lack of beginning to time or a beginning itself. While I would agree believing in it just to believe in something is silly I would also say that discounting it simply because you cannot see the light at the end of the proverbial "tunnel of knowledge" is also silly.

Interestingly a point Dodece hit on is also the the basis for a theory that our universe will rip itself apart.

He covered the idea that space itself was expanding but what most people don't understand is that its expanding from within and not from the edges. Basically the theory is "The Big Rip" or in short the universe will eventually tear itself apart.

Basically because each part of space is expanding there is constantly more and more space to expand and thus it expands faster and faster. Bleak stuff really.

<3 Family Guy