Heisenberg, Werner (vĕr`nər hī`zənbĕrk), 1901–76, German physicist. One of the founders of the quantum theory, he is best known for his uncertainty principle uncertainty principle, physical principle, enunciated by Werner Heisenberg in 1927, that places an absolute, theoretical limit on the combined accuracy of certain pairs of simultaneous, related measurements.
..... Click the link for more information. , or indeterminacy principle, which states that it is impossible to determine with arbitrarily high accuracy both the position and momentum (essentially velocity) of a subatomic particle like the electron. The effect of this principle is to convert the laws of physics into statements about relative probabilities instead of absolute certainties. In 1926, Heisenberg developed a form of the quantum theory quantum theory, modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
..... Click the link for more information. known as matrix mechanics, which was quickly shown to be fully equivalent to Erwin Schrödinger Schrödinger, Erwin (ĕr`vĭn shrö`dĭng-ər), 1887–1961, Austrian theoretical physicist.
..... Click the link for more information. 's wave mechanics. His 1932 Nobel Prize in Physics cited not only his work on quantum theory but also work in nuclear physics in which he predicted the subsequently verified existence of two allotropic forms of molecular hydrogen, differing in their values of nuclear spin.

Heisenberg was a student of Arnold Sommerfeld Sommerfeld, Arnold Johannes Wilhelm (är`nōlt yōhän`əs vĭl`hĕlm zôm`ərfĕlt)
..... Click the link for more information. , an assistant to Max Born Born, Max, 1882–1970, British physicist, b. Germany, Ph.D. Univ. of Göttingen, 1907. He was head of the physics department at the Univ. of Göttingen from 1921 to 1933.
..... Click the link for more information. , and later a close associate of Niels Bohr Harald August Bohr, 1887–1951, a mathematician, taught (1915–30) at the College of Technology in Copenhagen and in 1930 became professor at the Univ. of Copenhagen. His most noted contribution to mathematics was his formulation of the theory of almost periodic functions.
..... Click the link for more information. . He taught at the universities of Leipzig (1927–41) and Berlin (1942–45). During World War II he headed German efforts in nuclear fission research, which failed to develop a nuclear reactor or atomic bomb. Although he claimed after the war to have had qualms about building nuclear weapons, it seems likely that the reasons Germany failed to do so were technical and logistical.

In 1958 he became director of the Max Planck Institute for Physics and Astrophysics, now located in Munich. His later work concerned the so-called S-matrix approach to nuclear forces and the possibility that space and time are quantized, or granular, in structure. His Physics and Philosophy (1962) and Physics and Beyond (1971) remain popular accounts of the revolutions in modern physics.

Bibliography

See D. C. Cassidy, Uncertainty: The Life and Science of Werner Heisenberg (1993); R. P. Brennan, Heisenberg Probably Slept Here: The Lives, Times and Ideas of the Great Physicists of the 20th Century (1996).

Heisenberg, Werner (Karl)

(born Dec. 5, 1901, Würzburg, Ger.—died Feb. 1, 1976, Munich, W.Ger.) German physicist. Educated at Munich and Göttingen, he taught at the University of Leipzig (1927–41) and directed the Max Planck Institute for Physics (1942–76). In 1925 he solved the problem of how to account for the stationary discrete energy states of an anharmonic oscillator, a solution that launched the development of quantum mechanics. In 1927 he published his famous uncertainty principle. He also made important contributions to the theories of the hydrodynamics of turbulence, the atomic nucleus, ferromagnetism, cosmic rays, and subatomic particles. He was awarded the Nobel Prize for Physics in 1932 for his work on quantum mechanics. He led Germany's efforts in World War II (1939–45) to develop an atomic bomb.