If the Universe is infinite, then it has always been so even from the moment after the Big Bang; an infinite space can still expand.
It hadn’t quite sunk in until this article that looked at from a sum-over-histories point of view, only identical configurations interfere; that makes decoherence much easier to understand.
It’s not known whether the Universe is finite or infinite, this article gives more details:
http://en.wikipedia.org/wiki/Shape_of_the_Universe
If the Universe is infinite, then it has always been so even from the moment after the Big Bang; an infinite space can still expand.
It hadn’t quite sunk in until this article that looked at from a sum-over-histories point of view, only identical configurations interfere; that makes decoherence much easier to understand.