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 are in our infancy when it comes to understanding all of space and the universe. We are literally like kids in grade 3 confidentially discussing how something like an oil refinery works. We understand some broad concepts. But when you read things about expanding/contracting/dark matter/black holes/gravity/exotic particles/etc take it all with a huge grain of salt, it’s all very likely right in a broad sense but wrong in many of the details.