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

We don’t.

What we have are models and observations.

As long as observations match with models (to the accuracy of the observation), we can assume the model is correct. Until there’s a contradiction with new observations.

And right now the model that best matches observations is one that says the observable universe is 96 billion lightyears across.