Quantum Mechanics (1900-1927)

Quantum mechanics — developed by Planck, Einstein, Bohr, Heisenberg, and Schrodinger between 1900 and 1927 — revealed that at the subatomic level, nature behaves in ways completely unlike everyday experience: particles exist in superpositions, measurement changes the thing measured, and certain pairs of properties cannot simultaneously be known precisely. It is the most successfully tested theory in science and the foundation of transistors, lasers, MRI machines, and computing.