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Robert Benjamin Leighton (; September 10, 1919 – March 9, 1997) was a prominent
American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...
experimental physicist who spent his professional career at the California Institute of Technology (Caltech). His work over the years spanned
solid state physics Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state physics studies how the l ...
, cosmic ray physics, the beginnings of modern particle physics, solar physics, the
planets A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young ...
, infrared astronomy, and millimeter- and submillimeter-wave astronomy. In the latter four fields, his pioneering work opened up entirely new areas of research that subsequently developed into vigorous scientific communities.


Early life

Leighton was born in Detroit, where his father made precision dies for an automobile company. After moving to Seattle the family broke up, and his father returned to Detroit. His mother moved to downtown Los Angeles, where she worked as a maid in a hotel. Leighton grew up in Los Angeles and completed his first two years of undergraduate coursework at Los Angeles City College. He was accepted to Caltech as a junior in 1939 but continued to live at home, helping support his mother and himself with a job building X-ray equipment for the Kellogg Laboratory.


Education and Caltech

Leighton received his BS in
electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...
from Caltech in 1941. He then switched to physics and went on to obtain MS (1944) and
PhD PHD or PhD may refer to: * Doctor of Philosophy (PhD), an academic qualification Entertainment * '' PhD: Phantasy Degree'', a Korean comic series * ''Piled Higher and Deeper'', a web comic * Ph.D. (band), a 1980s British group ** Ph.D. (Ph.D. albu ...
(1947) degrees from the institution. His doctoral dissertation explored the specific heat of face-centered cubic crystals. He joined Caltech's faculty in 1949 and served as Division Chair of Physics, Mathematics and Astronomy from 1970 to 1975. Leighton was a renowned teacher at Caltech. His ''Principles of Modern Physics'', published in 1959, was a standard and influential textbook.


Relationships

Leighton and longtime Caltech colleague Richard Feynman were close personal friends. In the early 1960s, he spent more than two years reworking tape recordings of Feynman's Lectures in Physics course into '' The Feynman Lectures on Physics'' (1964-1966), which have enjoyed perennial success ever since. In addition, he co-authored, with Robbie Vogt, a set of problems to accompany the Feynman Lectures. One of Leighton's sons, Ralph, also collaborated with Feynman on several books.


Scientific achievements

Leighton was known as a remarkably ingenious physicist and astrophysicist during his 58 years at Caltech. He found no instrumentation problem too difficult, especially if it might open a new part of the electromagnetic spectrum to observation. If he found an inexpensive solution, he would build the apparatus in his spare time, for use by others and by himself. Leighton built, improved, and used cloud chambers to identify and measure new products of cosmic ray collisions. He explored the
decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
s of
mu-meson A muon ( ; from the Greek alphabet, Greek letter mu (letter), mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 ''elementary charge, e'' and a spin-½, spin of , but with a m ...
s and recognized several of the strange particles when particle physics was at its beginning. Leighton played a key role in 1949 in showing that the mu-meson decay products are two neutrinos and an electron, and he made the first measurement of the energy spectrum of the decay electron (at the time, low statistics experiments suggested that only one neutrino was involved). In 1950 he made the first observation of strange particle decays after the initial discovery of two cases in England in 1947. Over the next seven years, he elucidated many of the properties, e.g., mass, lifetime, decay-modes and energies, of several of the new strange particles, in particular, the lambda, the xi, and what were then called the theta particles ( K-mesons). His subject matter evolved from physics to astrophysics as he helped astronomy take on its modern shape. About 1956, Leighton became interested in the physics of the outer layers of the Sun. With characteristic imagination and insight, he devised
Doppler shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
and Zeeman effect solar cameras. They were applied with striking success to the investigation of magnetic and velocity fields on the sun. With the Zeeman camera, Leighton mapped complicated patterns of the sun's magnetic field with excellent resolution. Even more striking were his discoveries of a remarkable five-minute oscillation in local surface velocities and of a "super-granulation pattern" of horizontal convection currents in large cells of moving material. These solar oscillations have subsequently been recognized as internally trapped acoustic waves, opening up the whole new fields of helioseismology and solar magneto convection. Leighton himself soon realized that solar magneto-convection cells would lead to an effective diffusion of flux on the solar surface (now called Leighton diffusion), and he included it in a dynamo model of the solar cycle. In the early 1960s, Leighton developed and fabricated a novel, inexpensive infrared telescope, which included a simple array of eight lead-sulfide photocells. These cells were surplus from the defense industry; they had been developed for the Sidewinder missile's heat-seeking guidance system. Starting in 1965, he and Gerry Neugebauer used the new telescope to sweep the roughly 70 percent of the sky visible from
Mt. Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observ ...
, collecting the data as squiggles on a strip-chart recorder. This began a new area of infrared astronomy. The resulting
Two-Micron Sky Survey Two-Micron Sky Survey, or IRC, or Caltech infrared catalog is the astronomical catalogue of the infrared sources published in the 1969 by Neugebauer and Leighton. Catalogue index consists of two numbers - declination rounded to multiplier of 10 d ...
, published in 1969, contained 5,612 infrared sources, the vast majority of which had been previously uncataloged. Some of these have been found to be new
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s still surrounded by their dusty pre-stellar shells, while others are supergiant stars in the last stages of their evolution, embedded in expanding dusty shells of matter ejected by the stars themselves. Leighton's development of photographic equipment during the mid-1950s had allowed him to obtain the best pictures of the planets ever attained anywhere to that time, from the 60 and 100-inch telescopes, and led to his work as Team Leader at the Jet Propulsion Laboratory (JPL) for the Imaging Science Investigations on the Mariner 4, 6, and 7 missions to Mars during the middle 1960s. As Team Leader and an experienced experimental physicist, Leighton played a key role in forming and guiding the development of JPL's first digital television system for use in deep space: the Mariner 4 flyby of Mars in 1964. He also contributed to the first efforts at
image processing An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...
and enhancement techniques made possible by the digital form of the imaging data. He received the Space Science Award from the American Institute of Aeronautics and Astronautics for the Mariner television experiments in 1967 and the NASA Exceptional Scientific Achievement Medal in 1971. In the 1970s, Leighton's interest shifted to the development of large, inexpensive dish antenna which could be used to pursue millimeter-wave
interferometry Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...
and submillimeter-wave astronomy. Once again, his remarkable experimental abilities opened a new field of science at Caltech which continues to be vigorously pursued at the Owens Valley Radio Observatory in California and the Caltech Submillimeter Observatory on
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, Hawaii using the "Leighton Dishes". Leighton was an elected member of the
National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...
and served on its Space Science Board. Leighton shared the Rumford Prize in 1986 for advancements in Infrared Astronomy, and won the James Craig Watson Medal in 1988, for his work as creator and exploiter of new instruments and techniques that opened whole new areas of astronomy — solar oscillations, infrared surveys, spun telescopes, and large millimeter-wave reflectors.


Late years

Leighton retired from teaching in 1985 and from research in 1990 as the William L. Valentine Professor of Physics, Emeritus. '' The New York Times'' published Leighton's obituary on 14 March 1997, five days after his death. The Los Angeles Central Library, where Leighton read mathematics and astronomy after school as a child, also presented a symposium and exhibit in Leighton's honor soon after his death. In 2009, a 66 km-diameter crater in the Syrtis Major region of Mars was named after him.


References


External links


National Academy of Sciences Biographical Memoirs V.75 (1998) - Robert B. Leighton, pp. 164-189. A biographical memoir by Jesse L. Greenstein, which describes the greater part of Leighton's scientific achievements.


* ttps://feynmanlectures.caltech.edu The Feynman Lectures on Physics {{DEFAULTSORT:Leighton, Robert 1919 births 1997 deaths 20th-century American physicists American astronomers California Institute of Technology alumni California Institute of Technology faculty Members of the United States National Academy of Sciences