[Boogieman]

All discussions that physicists make about the universe take as a given that they are discussing the observable universe, not the universe as a whole. Just because they don't bother to restate that every time doesn't mean it isn't taken into account.

[UCANSEE2]

Just because they don't bother to restate that every time doesn't mean it isn't taken into account.

Agreed.

So, they are stating that the 'observable' universe is expanding. Then they assume that the non-observable universe must also be expanding. And they assume it's size. Neither of which is provable, at this point.

We have no more proof it is expanding than we do that it is collapsing (although the collapsing theory would eventually be 'prove-able').

What really happens is that as our technology improves, our 'understanding' of the universe evolves. We went from collapsing to expanding. It may end up that neither is true.