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The Ending Of The Big Bang?
Pedrito writes "CNN is running a story here about a new theory that competes with the Big Bang. I figured it would already be up here. The theory goes that the universe "existed" before as a vacuous space, devoid of matter or energy. Two universes collided and the collision brought matter and energy to the void. The theory explains some things that the Big Bang doesn't. It's also partially based in String theory, of which I'm a big believer."
Don't get me wrong...Mr. Hawking and his peers think more before breakfast than I do in an average year, but without falsifiable hypotheses, a lot of cosmology has more to do with faith than with fact. This is not necessarily a bad thing, but one has to realize it for what it is.
Models of the universe's creation actually do produce a surprising number of testable predictions.
We see space permeated by 3K blackbody radiation. The big bang model neatly explains this (the universe was once very hot and compact). Steady-state models don't. Scratch the steady-state models.
We see a universe that is apparently geometrically "flat" (Euclidean). This eliminates a wide range of big bang models, and suggests (among other things) that the universe may have started with zero net energy (and thus be the result of a quantum fluctuation).
We see matter clumping on a small scale, but amazingly uniform on a larger scale. The degree and patterns of clumping observed suggest a period of extremely rapid expansion while the universe was very small. Thus, the various inflationary models of the universe. Some produce predicted mass distributions that match the universe's; some don't. Scratch the ones that don't.
Our models of physics at the extreme temperatures and densities that the universe looks like it had in its youth are not well-defined. Some options suggest that we'd get zillions of black holes permeating space. Do we see any? No, so scratch that range of physics models. Other options suggest gigantic artifacts like "cosmic strings" or "great walls". Do we see any? No walls, and strings are inconclusive (putting an upper limit on the number present, if any). This narrows the range of physical theories even more, which in turn gives us a better idea of how the universe would have behaved under early conditions, which lets us refine our predictions of what an old universe would look like under a given model, which lets us further prune models according to observations.
In summary, while speculation indeed occurs, when a model is selected it's usually selected based on the testable predictions it makes.
Again, a library search will turn up most of this.