The first law of thermodynamics states that the energy of the universe is constant, but the universe is constantly expanding, so how does the energy stay constant considering the expansion?

Question

I think this is physics based(?), but I thought of this question during my summer chemistry course, so I wasn’t sure of the flair.

In: Physics

Answer 1

The answer that makes sense for me is that it’s not that things are moving farther apart, it’s that space itself is expanding. It’s like you have an object that’s a meter long, space stretches so that the object appears 2 meters long, but the mass doesn’t change