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

We don’t know. We don’t know if something outside of the universe exists in the first place. The big bang possibly created space itself, so asking so “where” isn’t a meaningful question outside of the universe.

What we know is that the distance between us and far away stars becomes bigger. Space itself is somehow growing.