I've been thinking about the origin of the Big Bang and came with an interesting conclusion (I think). We often say that before the Big Bang there was nothing and that therefore, the Big Bang came from nothing. Well, that sentence seems to me to give the answer: the Big Bang came from nothing. What if, if in presence of an absolute nothingness (no matter, no energy, no field, no gravity, no flow of time, no space-time, nada, rien) a Big Bang will occur? What if, if it is only a simple law of nature as simple as gravity, that Nature forbids the existence of nothingness? That would explain the presence of dark energy that permeates all of space. Since we had a Big Bang, there is no such thing as nothingness anymore in our universe and dark energy is a consequence of that law. I don't try to explain its properties but only the reason of its presence. That would also explain the existence of virtual particles and vacuum fluctuations. As you get closer and closer to a perfect nothingness, Nature seems to fight back. We can also link this to black holes in a way. If nothing is the starting point of everything, then in presence of infinite density, it is the end point of everything (time, matter, energy, space-time). Well, this theory is impossible to test (we would need a perfect nothingness, which is unacheivable) but it makes logical sense rather than just saying "the origin of the Big Bang is an unsanswerable question" or that God created the Big Bang. I don't think black holes generate big bangs in other universes since the amount energy present in a black hole is very far from equaling the amount of energy released during the big bang. Well Mike, I wanted to have you opinion on this.
I agree that we can't expect all of our theories to be fully testable, but it sure is nice to have some sort of partial test. I don't see that with this one.
The problem of "what came before the Big Bang" is just starting to leave the realm of philosophy and join the realm of science. The crazy singularity at the origin of a pure General Relativistic picture is removed in various theories which attempt to put GR in the quantum framework. Our universe then becomes one region of a broader spacetime manifold. What's more amazing than that limited theoretical progress is that different pictures of how to embed the universe in the broader manifold have different predictions, especially for small ripples in cosmic microwave background radiation. Paul Steinhardt has a nice new Scientific American article (April, 2011) on that. Some of this may get sorted out in the next few years.
(published on 04/22/2011)