Big Bang...How Did it Happen?

Navy10E writes:I simply want to know everyone's theory on the "Big Bang", how it happened, could it happen, etc. Start it out basicly.

Gabriele Veneziano writes:The first, known as the pre-big bang scenario, which my colleagues and I began to develop in 1991, combines T-duality with the better-known symmetry of time reversal, whereby the equations of physics work equally well when applied backward and forward in time. The combination gives rise to new possible cosmologies in which the universe, say, five seconds before the big bang expanded at the same pace as it did five seconds after the bang. But the rate of change of the expansion was opposite at the two instants: if it was decelerating after the bang, it was accelerating before. In short, the big bang may not have been the origin of the universe but simply a violent transition from acceleration to deceleration.The beauty of this picture is that it automatically incorporates the great insight of standard inflationary theory--namely, that the universe had to undergo a period of acceleration to become so homogeneous and isotropic. In the standard theory, acceleration occurs after the big bang because of an ad hoc inflaton field. In the pre-big bang scenario, it occurs before the bang as a natural outcome of the novel symmetries of string theory.
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.So, when did time begin? Science does not have a conclusive answer yet, but at least two potentially testable theories plausibly hold that the universe--and therefore time--existed well before the big bang. If either scenario is right, the cosmos has always been in existence and, even if it recollapses one day, will never end.

General Nazort writes:Some progress has been made in this area - for example, the Heisenberg uncertainty principle has been succesfully described with classical physics.