How dense does matter need to be to carry sound?

Question

Or not just sound, but to propagate any motion (which is sound). Sound won’t travel in space because there’s not enough of a medium, but where is the threshold? The atmosphere gets thinner and thinner the farther out you go – how far away from each other do the molecules need to be to not carry sound?

In: Physics

Answer 1

i’m sure there’s a physics equation that can answer exactly, but basically the molecules need to be close enough to hit each other when agitated