1926
Schrödinger's Wave Mechanics
Physicists are still puzzled by that strange now-a-particle, now-a-wave nature of matter. But in 1926, Austrian physicist Erwin Schrödinger derives an equation capable of explaining the so-called "waveform" nature of matter. Through his equation, Schrödinger describes how matter exists as a probability wave. For example, an electron is a waveform that exists throughout all of space, but there's a higher probability of finding it in some places than in others. It's hard to believe, but the math works. Using the Schrödinger Equation, physicists can explain many atomic-scale mysteries—for instance, how electrons stay in orbit around the nucleus of an atom.