Nah, most of the random atoms floating around in space are going to be travelling very roughly as fast as the things (stars, planets, etc..) around them -- beca

Nah, most of the random atoms floating around in space are going to be travelling very roughly as fast as the things (stars, planets, etc..) around them -- because anything travelling much faster is likely to eventually bump into something and lose some of its momentum. There is the occasional weird exception though: https://en.wikipedia.org/wiki/Oh-My-God_particle https://en.wikipedia.org/wiki/Oh-My-God_particle