How can we be confident about universal properties, or anything for that matter, in astrophysics when we can’t actually do experiments on stars, distant planets, etc. ?

Question

How can we be confident about universal properties, or anything for that matter, in astrophysics when we can’t actually do experiments on stars, distant planets, etc. ?

In: 63

Answer 1

Because 2+2=4 everywhere in the universe as far as we can figure, maybe not inside black holes but I’m not going there now.