I have heard statements made that at the instant of the Big Bang, the entire universe was condensed into an incredibly tiny space (a "singularity"). But I've also heard it said that space-time began with the Big Bang. So the singularity did not exist within a Newtonian absolute space. How, then, can it make sense to talk about how big the universe was? Perhaps this is related to the question of how the universe could expand if there is no Newtonian space into which it expands?