Eli5 if the universe is everything but it is constantly expanding, what is it expanding into?

Question

Eli5 if the universe is everything but it is constantly expanding, what is it expanding into?

In: 22

Answer 1

There is no “into”, there is only nothing. No space, matter. Literally nothing. Unfortunately this concept is hard to wrap our brains around because our whole existence is based on the opposite of nothing so we can’t really picture nothing (because there’s nothing to picture).

Also, don’t think of the universe as a place. The universe is a thing. The universe is the collective of everything that exists.