ELi5: Is the entire Universe (unobservable + observable) 13.8 billion years old or just the observable Universe 13.8 billion years old?

Question

ELi5: Is the entire Universe (unobservable + observable) 13.8 billion years old or just the observable Universe 13.8 billion years old?

In: Physics

Answer 1

There’s not any way to answer this since by definition we don’t have any idea what’s going on outside the observable universe. I will say that as far as I’m aware there’s no reason to assume it behaves any differently.