Is it possible that the Big Bang was caused by virtual particle creation? As far as I understand, it is understood that throughout the universe there exists, what is known as, a quantum field from which, due to its fluctuations, temporary (pairs of) virtual particles continuously appear in a random, unpredictable (or should I say probabilistic?) fashion.
For my idea to have any viability, I am assuming that this quantum field is an intrinsic part of reality, that existed "before" or rather at the time of the Big Bang already. Is this a correct assumption? Or is it believed that this quantum field was "formed" at the time, or perhaps even later than, the moment of the Big Bang? I hope not.
Assuming the former, and also understanding that those pairs of virtual particles typically annihilate each other almost instantaneously, but sometimes actually create real particles — for instance in Hawking radiation — is it a far stretch to think that the Big Bang was possibly started by the highly improbable (but in an "infinite" timespan of underlying reality, likely to occur), cataclysmic event of a huge amount of virtual particle all appearing, either "at the same time", or in such a sequential manner, that they couldn't annihilate each other anymore and were destined to actually form large quantities of real particles?
 A: The idea that the universe is a vacuum flucuation has been around a long time. The first public mention of the idea I know of is from Edward Tryon in 1973, but I bet it had been discussed long before that. Do you have access to old copies of Nature? If so have a look at "Is the Universe a Vacuum Fluctuation?" by Edward Tryon, Nature 246, 396 - 397 (14 December 1973).
Alexander Vilenkin developed the idea further in 1982, and his paper is available online at http://mukto-mona.net/science/physics/a_vilinkin/universe_from_nothing.pdf.
The bottom line is that we don't understand the physics well enough to know if there is any foundation to these ideas, and no-one has come up with any experimental way to test them. I should note that the various theories of quantum gravity have come up with scenarios in which the universe wasn't created at the Big Bang but has existed (potentially at least) forever. From String Theory we have the ekpyrotic universe, and from loop quantum cosmology the idea that there might have been a Big Bounce.
I suspect most physicists would regard the question as philosophy rather than physics.
A: The thing that appeals to me about this idea is , if there is some theoretical way the virtual pair can be kept apart, then we might assume an identical anti-universe was created.  This would neatly explain why we don't observe equal quantities of matter and anti- matter in our universe. All the anti-matter is in the other universe outside of our observable event horizon.
The Big Bang and inflation result from the supermassive universe particle decaying/condensing/phase changing into the zoo of particles we observe today.  
