Mathematics of Eternity Prove The Universe Must Have Had A Beginning

I've found one useful way to think about the question "what was before the Big Bang" is to ponder "what is North of the North pole"?<p>Don't stretch the analogy too far - I'm not suggesting that spacetime is topologically shaped like that - but to me it's a useful example of a co-ordinate system which seems locally euclidean going whacky at/near the boundaries.<p>Roughly, "But there has to be something <i>before</i> the big bang, you just go back a bit further in the same direction!" == "But there has to be something North of the pole - you just go a bit further in the same direction!"

You can read John Rennie's excellent answer to this question (<a href="http://physics.stackexchange.com/questions/24018/how-can-something-happen-when-time-does-not-exist" rel="nofollow">http://physics.stackexchange.com/questions/24018/how-can-som...</a>) that always comes up during discussions on time.

"A universe from nothing" by Lawrence Krauss presents the possibility of a universe without a beginning, even one containing "nothing", yet still be compatible with present cosmology. My general impression is that by "nothing" he means "averaged out, zero energy" and with a set of laws (quantum mechanics) that can generate fluctuations. Out of these fluctuations you can have particles of various energy arising (which normally live short lives and decay back into nothingness).<p>But given enough time you could have a large enough fluctuation that generates a big bang, followed by very long inflation and cooling. Equally so, you could have a fluctuation that winks all the known universe into a void, suddenly and without warning.

this builds on an earlier theorem, which i haven't looked at (and probably wouldn't understand anyway) which apparently makes rigorous the intuitively attractive idea that if you trace back in time something that is getting bigger then at some point you reach zero.<p>the reason oscillating universes are caught out by this is that (apparently - this is all just my impression on a quick skim, having never understood things much and leaving astronomy - not even astrophysics - decades ago) even though they oscillate, they need to get systematically bigger to work around some problems with entropy.<p>another model they considered is a universe that "just sits there" like a seed, forever, until (randomly) deciding to grow. and that has problems with quantum mechanics (which you can imagine - how can something be stable for an infinite amount of time?).<p>one problem is that it's a paper that really only attacks current models. they don't <i>prove</i> that no other model could be thought up.<p>you could also argue another weakness of the paper is a reliance on our notions of basic physics (quantum and statistical mechanics) holding true even in the distant past. but then, what else can you do?

Creation of something from nothing seems rather functionally equivalent to destruction of a something into nothing with time reversed. Is there any known process or way to take something and destroy it utterly into nothing? If not, then what would make such an utter destruction possible given a reversed direction of time?<p>Except as an abstraction, it seems to me that no one has any real experience of nothing. As an empiricist, that gives me quite a bit of pause when anyone starts making claims about nothing (myself being no exception).

This is <i>my</i> theory.<p>After watching Steven Hawking's series on The Universe, he talked about Black Holes and how they keep growing and growing; sucking in more mass and getting denser and denser, whilst at the same time amasing more gravity.<p>i.e. the more mass something has, the more gravity it exerts, the more mass it attracts -- a viscious cirle.<p>So my theory, don't laugh, is that the universe if cyclical. After a Black Hole has consumed everything, including other Black Holes etc. it explodes and all that mass gets released creating the universe as we know it. And so on and so on over a <i>gazillion</i> years.<p>Is that absurd?<p>Edit: Many thanks for the informative replies...

Paper: <a href="http://arxiv.org/pdf/1204.4658v1.pdf" rel="nofollow">http://arxiv.org/pdf/1204.4658v1.pdf</a>

The question is not whether the universe had a beginning but rather how many times.

I'm a fan of the white-hole theory (big bang is opposite side of a super massive black hole in another universe)