How much stuff is in a light-year?Fraser Cain — Universe Today1/31/14 9:40am45EditPromoteDismissUndismissHideGo to permalinkImagine taking the distance that light travels in an entire year. Now turn that distance into a cube, each side one light-year across. How much "stuff" would be in there? And how empty would it be? It all depends on where you put your massive cube.