# quantum theory

**quantum theory** The foundation of 20th-century physics, together with the theory of relativity. It concerns itself with the relationship between matter and energy at the elementary or subatomic level, and with the behaviour of elementary particles. The theory is the basis of quantum mechanics. See also quantum numbers

#### More From encyclopedia.com

Quantum , QUANTUM.
The German physicist Max Planck (1858–1947) introduced the quantum of action h (Planck's constant) into physics in his successful theory of… Hendrik Antoon Lorentz , Lorentz, Hendrik Antoon
Lorentz, Hendrik Antoon
theoretical physics.
Lorentz, father, Gerrit Frederik Lorentz, owned a nursery near Arnhem. His mothe… Albert Einstein , EINSTEIN, ALBERT
(b. Ulm, Germany, 14 March 1879;
d. Princeton, New Jersey, 18 April 1955)
physics. For the original article on Einstein see DSB, vol… Quantum Electrodynamics , Quantum Electrodynamics (QED)
Quantum electrodynamics (QED) is a scientific theory that is also known as the quantum theory of light. QED describes t… Ludwig Boltzmann , Boltzmann, Ludwig
Boltzmann, Ludwig
physics.
Boltzmann’s father. Ludwig, was a civil servant (Kaiserlich-Königlich Cameral-Concipist), his mother was… Niels Henrik David Bohr , Bohr, Niels Henrik David
Bohr, Niels Henrik David
A tradition common to many pioneers in science has been the combination of achievement in actual di…

#### You Might Also Like

#### NEARBY TERMS

**quantum theory**