The Big Bang is a really misleading name for the expanding universe that we see. We see an infinite universe expanding into itself. The name Big Bang conveys the idea of a firecracker exploding at a time and a place - with a center. The universe doesn't have a center. The Big Bang happened everywhere at once and was a process happening in time, not a point in time. We know this because 1) we see galaxies rushing away from each other, not from a central point and 2) we see the heat that was left over from early times, and that heat uniformly fills the universe.