Quantum calculations amount to sophisticated estimates. But in 1931, Hans Bethe intuited precisely how a chain of particles would behave — an insight that had far-reaching consequences. Hans Bethe pioneered a method that — when the stars align — allows physicists to perfectly understand the collective behavior of any number of quantum particles. Señor Salme for Quanta Magazine Introduction By 1928, quantum physicists seemed poised to unravel matter’s final secrets. The German researcher Walter ...