“The second law states that a force is proportional to an object’s mass and its acceleration. But since the 1980s, some physicists have eyed the law with suspicion, arguing that subtle changes to it at extremely small accelerations could explain the observed motion of stars in galaxies.” Also on the subject of spinning, a new experiment finds a way to test Modified Newtonian Dynamics (MOND) on Earth, which, if successful, could revise Newton’s heretofore ironclad 2nd law…and explain away the longstanding dark matter problem. (By way of my new favorite Twitter feed, @newscientist.)