Where does the extra space come from as the universe expands? and if it’s just stretching, does that mean it somehow is getting thinned out?

Question

Where does the extra space come from as the universe expands? and if it’s just stretching, does that mean it somehow is getting thinned out?

In: 47

Answer 1

The space is added uniformly in the existing space. The mass remains the same so the density is reduced overall.

So here’s what happens with you add a little space inside the Earth. Gravity is still a thing, so gravity returns the Earth to it’s proper size, leaving a tiny bit of extra space just outside the region of the Earth’s influence.