Quantum mechanics is the science of the very small: the body of scientific principles that explains the behavior of matter and its interactions with energy on the scale of atoms and subatomic particles. Classical physics explains matter and energy on a scale familiar to human experience, including the behavior of astronomical bodies. It remains the key to measurement for much of modern science and technology.
1838 Michael Faraday discovery of cathode rays
1859–60 Gustav Kirchhoff black-body radiation problem
1877 Ludwig Boltzmann energy states of a physical system could be discrete
1887 Heinrich Hertz discovery of the photoelectric effect
1900 Max Planck quantum hypothesis
1905 Albert Einstein explains the photoelectric effect
1926 Gilbert N. Lewis photons
1920 Max Born, Werner Heisenberg, and Wolfgang Pauli coined the term “quantum mechanics”
Max Planck, Albert Einstein, Niels Bohr, Louis de Broglie, Max Born, Paul Dirac, Werner Heisenberg, Wolfgang Pauli, Erwin Schrödinger, Richard Feynman.