Alex,
We can't prove or disprove that "nothing" existed before the bang. However, we do have cosmic radiation measurements of a big bang 13.7 billion years ago, and other physical evidence that supports expansion. But we cannot (currently) measure what existed before the big bang. Sure, we can argue what "was" or "wasn't", but it would all be pure speculation. Given that most of what we DO know about the universe is less than 50 years old and that we are regularly discovering that we actually know bugger all (eg. "event horizons"), it's safe to say we've probably discovered only a fraction anyway
Re: "perception" vs. "real" time dilation, the view that makes the most sense to me in this thread is this by AGarvin on the previous page :
Basically, it centres around the fact that the speed of light is the same for all observers. The stationary observer will see the light travel further than the person in the ship will for the same event. If the distance is further, but the velocity is the same, then the time taken must be 'longer', or dilated.
To me, this is not a perception. Assuming that C is definitely constant, the observer will actually live longer than the traveller during the period of the experiment. But if nothing can move faster than C, then we get the paradoxes mentioned earlier, like not being able to "see" your hand in front of you travelling at C.
... As I said, we know bugger all... but tallking about it is a *great* way to produce sparks!