Failure of Quantum Mechanics without Relativity

Philosophical questions aside, in the 1930s and 1940s quantum mechanics was like an unstoppable Mack truck barreling down a highway, flattening all the problems that had puzzled physicists for centuries. One brash young quantum physicist, Paul Dirac, ruffled the feathers of many chemists when he had the nerve to say that quantum mechanics could reduce all of chemistry to a set of mathematical equations.