The Century-Long Pause in Fundamental Physics Most readers first encountered quantum mechanics through its interpretations debate: Copenhagen, Everett, Bohm, hidden variables, many-worlds. The debate is painted as one of physics's deepest unresolved puzzles. After 95 years the field cannot resolve which interpretation is correct, and there is no possibility of empirical resolution because all interpretations make the same predictions. The puzzle is much smaller once you separate two questions about it: a mathematical model reproduces measurements, while a physical theory says what in the world makes them come out that way. If QM were a physical theory, the persistence of the disagreement would be intolerable. If QM is a mathematical model (a probability calculus on a wave-mechanical system), the situation is unremarkable.…