Originally posted by convect
What's the current state of the art of thinking on where the Universe itself came from? What was "before" the Big Bang, if such a term has meaning? How much of the current cosmological speculation is testable?
There are various hypotheses, including:
1. That there is no before, ie the big bang started from a singularity that was the beginning of time. Note that this does not entirely rule out the possibility of other universes or dimensions but thats another story. In this scenario, "before the Big Bang" has no meaning.
2. There was no singularity, and the universe had a history going back further than the big bang. One such hypothesis is in the October Scientific American and is called the big bounce. Basically the hypothesis is that there is a limit to how much energy can fit into a given volume of space and when a universe is contracting under gravity, it reaches the limit and bounces back out.
Certainly No 2 is testable, but possibly not with current equipment. The test would be either predictions made about the visible universe, or tests or predictions relating to the underlying concept that space has a maximum energy capacity.