I'm hoping that some kind astronomer or astrophysicist here can tell me which physics law, or laws, (if any) mandate that many astronomical structures revolve or rotate, from asteroids though planets, pulsars, stars to galaxies. I guess they all develop with conserved angular momentum to a lesser or greater degree, but is there a mechanism for its acquisition, as it were, that is accepted in terms of specific features of physics laws? Those involving gravitational condensation, maybe? I'd prefer an answer other than "Why not?", or "Because it was so ordained" .