eli5-how do we know for sure how big space is? and how do we know we are right about everything we know in space?

Question

eli5-how do we know for sure how big space is? and how do we know we are right about everything we know in space?

In: Planetary Science

Answer 1

Short answer: we don’t. That’s why it’s called the “observable universe”.

They can make guesses to the size to the universe by observing things like gravity, distant stars, etc. But all that, at best, is a guess.