Subject: Infinite number of universes after the big bang?

It's possible that there were a finite or even infinite number of Universes before ours, but it looks unlikely that there will be another one.

One theory states that our Big Bang was not unique. Perhaps there is some Universe outside our own, a metaverse, and ours was created when some quantum fluctuation zigged instead of zagged. Perhaps our own Universe is the mother to many such other baby Universes, which we cannot detect because they drop out of time and space when they are formed. The problem is, since these Universes are undetectable, there isn't anything we can say about them!

Recent studies have shown that our Universe is not only expanding, but the expansion is accelerating. Our Universe looks like it will expand forever, so as far as the future goes, we're it. There will be no recollapse. If that's true, it seems to me unlikely that there have been a large number of Universes before ours, because what're the odds we happen to live in the last one? But again, without observations there's nothing we can say about these other Universes. You can read more about the accelerating Universe at my own Bad Astronomy website, or at the Astronomy Magazine website. For a more detailed and technical explanation, try Ned Wright's Cosmology website.

The recent discovery that neutrinos have mass caused a flurry of excitement that perhaps they are the missing mass, but it turns out that they are not massive enough to reverse the expansion of the Universe. For more about this discovery and its ramifications, try the Super Kamioande web page, where the discovery was made, or specifically their page about cosmology.