There are often heated discussions about the Big Bang. The Big Bang is well defined as the high density state that you get if you extrapolate the today observable cosmic Hubble expansion backward into the past. This definition has been the same one all along; it did not change; it is still valid today.

What does this entail?
1) The Big Bang tells you nothing about the absolute size of the universe at any time! As far as the definition is concerned, it may have been infinite all along. The Big Bang is not where the universe has zero size.