Quote Originally Posted by Invader View Post
Care to elaborate a bit about that? I thought the conventional wisdom was that there was nothing before the event at all, which begs the question: How does quantum fluctuation happen in nothing? I'll reserve my other questions until you respond.
Sure. There is no way to say what was before the big bang or if it even makes sense to talk about a 'before' the big bang. So the best that we can say is that the universe as we know it began as a singularity and that guess is very well supported by observations. The quantum fluctuations would have been happening within the initial singularity. They answer the questions about what caused the singularity to not be a singularity anymore. This is possible because all the mass-energy of the universe, was compressed, along with the universe itself, to quantum scales so the whole thing was subject to quantum indeterminacy. So it could have found itself where the mass-energy was diffuse enough for some effect to cause further expansion. This is all happening 10^-12 seconds after the big bang and earlier. After that, known physics can pretty much handle it.

Confused? So am I. I was talking off the cuff when I called it common wisdom. That's just a phrase of speech. Common speculation would be better.

There are quantum fluctuations in "nothing" though. The closest that exists to a vacuum in nature is deep space and there QFT says that there are virtual particle pairs popping into existence and out of existence all the time. This is the basis of the unruh effect where an accelerating observer measures an increase in temperature. A non-accellerating observer wouldn't measure the virtual particles (this would contradict conservation of energy) but once you accelerate, enough energy is put into the system for them to be measured at the expense of whatever is accellerating the observer. That old saying that "nature abhors a vacuum" is more true than its originator could have imagined.