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

The same laws of physics that explain the motions of planets, moons, stars – which we can directly observe- also govern man-made satellites, like what makes your GPS work. Everything agrees very well.

We can recreate all sorts of conditions of all the physical phenomena we understand here – high temperature, low temperature, vacuum, high pressure, electromagnetic fields…things being different on other planets/stars would require some fundamental new phenomenon.

Plus, we haven’t ever seen evidence that universal properties don’t hold elsewhere, so the assumption that they do continues to gain momentum.