Theodore "Ted" Allen Welton (July 4, 1918 – November 14, 2010) was an American

theoretical A theory is a systematic and rational form of abstract thinking about a phenomenon, or the conclusions derived from such thinking. It involves contemplative and logical reasoning, often supported by processes such as observation, experimentation, ...

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

best known as the co-author of the

fluctuation dissipation theorem Fluctuation may refer to: Physics and mathematics * Statistical fluctuations, in statistics, statistical mechanics, and thermodynamics ** Thermal fluctuations, statistical fluctuations in a thermodynamic variable * Quantum fluctuation, arising fr ...

. During 1944 and 1945 he worked at

Project Y The Los Alamos Laboratory, also known as Project Y, was a secret scientific laboratory established by the Manhattan Project and overseen by the University of California during World War II. It was operated in partnership with the United State ...

Los Alamos, New Mexico Los Alamos (, meaning ''The Poplars'') is a census-designated place in Los Alamos County, New Mexico, United States, that is recognized as one of the development and creation places of the Nuclear weapon, atomic bomb—the primary objective of ...

on nuclear weapons in

Richard Feynman Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist. He is best known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of t ...

's T-4 Group after being recruited by Feynman. Welton was born in

Saratoga Springs, New York Saratoga Springs is a Administrative divisions of New York#City, city in Saratoga County, New York, United States. The population was 28,491 at the United States Census 2020, 2020 census. The name reflects the presence of mineral springs in the ...

and educated at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

, where he received a B.S. degree in 1939. He received his Ph.D. from the

University of Illinois The University of Illinois Urbana-Champaign (UIUC, U of I, Illinois, or University of Illinois) is a public university, public land-grant university, land-grant research university in the Champaign–Urbana metropolitan area, Illinois, United ...

in 1944. He worked at

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development Laboratory, laboratories of the United States Department of Energy National Laboratories, United States Department of Energy ...

on diffusion problems during the

Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...

and was present at the

Trinity Test Trinity was the first detonation of a nuclear weapon, conducted by the United States Army at 5:29 a.m. MWT (11:29:21 GMT) on July 16, 1945, as part of the Manhattan Project. The test was of an implosion-design plutonium bomb, or "gadg ...

. After

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

he taught at

MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...

and the

University of Pennsylvania The University of Pennsylvania (Penn or UPenn) is a Private university, private Ivy League research university in Philadelphia, Pennsylvania, United States. One of nine colonial colleges, it was chartered in 1755 through the efforts of f ...

. In 1948, he gave a simple qualitative description of the quantum electrodynamic corrections in atomic physics such as the

Lamb shift In physics, the Lamb shift, named after Willis Lamb, is an anomalous difference in energy between two electron orbitals in a hydrogen atom. The difference was not predicted by theory and it cannot be derived from the Dirac equation, which pre ...

as the interaction of non-relativistic treated electrons with stochastic quantum mechanical fluctuations of the electrodynamic field in the vacuum state, the mean value of which vanishes, but the standard deviation does not. In 1950 he worked at

Oak Ridge National Laboratory Oak Ridge National Laboratory (ORNL) is a federally funded research and development centers, federally funded research and development center in Oak Ridge, Tennessee, United States. Founded in 1943, the laboratory is sponsored by the United Sta ...

in the Theoretical Physics Division; and in the following year, with

Herbert Callen Herbert Bernard Callen (July 1, 1919 – May 22, 1993) was an American physicist specializing in thermodynamics and statistical mechanics. He is considered one of the founders of the modern theory of irreversible thermodynamics, and is the author ...

, he published the landmark fluctuation-dissipation theorem, showing that the explanations of

Brownian motion Brownian motion is the random motion of particles suspended in a medium (a liquid or a gas). The traditional mathematical formulation of Brownian motion is that of the Wiener process, which is often called Brownian motion, even in mathematical ...

and

Johnson noise Johnson may refer to: People and fictional characters *Johnson (surname), a common surname in English *Johnson (given name), a list of people * List of people with surname Johnson, including fictional characters *Johnson (composer) (1953–2011), ...

are specific examples of the more general theorem. Over the course of his career, Welton contributed to the development of nuclear reactors, and worked on particle physics and electron microscopy. In 1953, he became a

Fellow of the American Physical Society The American Physical Society honors members with the designation ''Fellow'' for having made significant accomplishments to the field of physics. The following lists are divided chronologically by the year of designation. * List of fellows of the ...

. He also received a

Humboldt Prize The Humboldt Research Award (), also known informally as the Humboldt Prize, is an award given by the Alexander von Humboldt Foundation of Germany to internationally renowned scientists and scholars who work outside of Germany in recognition of ...

for his work in physics. He was married twice and had four children from his first marriage.

References

Further reading