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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 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 ...
who spent his professional career at the
California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
(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 ...
,
cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
physics, the beginnings of modern
particle physics Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
, 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 youn ...
,
infrared astronomy Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in be ...
, and millimeter- and submillimeter-wave
astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
. 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 Detroit ( , ; , ) is the largest city in the U.S. state of Michigan. It is also the largest U.S. city on the United States–Canada border, and the seat of government of Wayne County. The City of Detroit had a population of 639,111 at t ...
, where his father made precision dies for an automobile company. After moving to
Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest region o ...
the family broke up, and his father returned to Detroit. His mother moved to downtown
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world ...
, 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 Los Angeles City College (LACC) is a public community college in East Hollywood, Los Angeles, California. A part of the Los Angeles Community College District, it is located on Vermont Avenue south of Santa Monica Boulevard on the former campu ...
. 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 Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...
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. al ...
(1947) degrees from the institution. His doctoral dissertation explored the
specific heat In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...
of
face-centered cubic In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...
crystals A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
. 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 Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist, known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of the superfl ...
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 ''The Feynman Lectures on Physics'' is a physics textbook based on some lectures by Richard Feynman, a Nobel laureate who has sometimes been called "The Great Explainer". The lectures were presented before undergraduate students at the Cali ...
'' (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 Ralph (pronounced ; or ,) is a male given name of English, Scottish and Irish origin, derived from the Old English ''Rædwulf'' and Radulf, cognate with the Old Norse ''Raðulfr'' (''rað'' "counsel" and ''ulfr'' "wolf"). The most common forms ...
, 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 The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging fro ...
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 chamber A cloud chamber, also known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation. A cloud chamber consists of a sealed environment containing a supersaturated vapour of water or alcohol. An ...
s to identify and measure new products of
cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
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-mesons and recognized several of the
strange particle A strange particle is an elementary particle with a strangeness quantum number different from zero. Strange particles are members of a large family of elementary particles carrying the quantum number of strangeness, including several cases where the ...
s when
particle physics Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
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 The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...
, and he made the first measurement of the
energy spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...
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 decay In particle physics, particle decay is the spontaneous process of one unstable subatomic particle transforming into multiple other particles. The particles created in this process (the ''final state'') must each be less massive than the original, ...
s 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-meson KAON (Karlsruhe ontology) is an ontology infrastructure developed by the University of Karlsruhe and the Research Center for Information Technologies in Karlsruhe. Its first incarnation was developed in 2002 and supported an enhanced version of ...
s). 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 The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. 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 ...
and
Zeeman effect The Zeeman effect (; ) is the effect of splitting of a spectral line into several components in the presence of a static magnetic field. It is named after the Dutch physicist Pieter Zeeman, who discovered it in 1896 and received a Nobel pr ...
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 Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
telescope, which included a simple array of eight lead-sulfide
photocells A photoresistor (also known as a photocell, or light-dependent resistor, LDR, or photo-conductive cell) is a passive component that decreases resistance with respect to receiving luminosity (light) on the component's sensitive surface. The resi ...
. 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 Gerhart "Gerry" Neugebauer (3 September 1932 – 26 September 2014) was an American astronomer known for his pioneering work in infrared astronomy. Neugebauer was born in Göttingen, Germany and was the son of Otto Neugebauer, an Austrian-Amer ...
used the new telescope to sweep the roughly 70 percent of the sky visible from Mt. Wilson Observatory, collecting the data as squiggles on a strip-chart recorder. This began a new area of
infrared astronomy Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in be ...
. The resulting Two-Micron Sky Survey, published in 1969, contained 5,612
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
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 Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spa ...
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 The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
(JPL) for the Imaging Science Investigations on the
Mariner 4 Mariner 4 (together with Mariner 3 known as Mariner-Mars 1964) was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode. It was designed to conduct closeup scientific observations of Mars and to transmit the ...
, 6, and 7 missions to
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
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 Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative adva ...
system for use in deep space: the
Mariner 4 Mariner 4 (together with Mariner 3 known as Mariner-Mars 1964) was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode. It was designed to conduct closeup scientific observations of Mars and to transmit the ...
flyby of
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
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-dimensio ...
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 The American Institute of Aeronautics and Astronautics (AIAA) is a professional society for the field of aerospace engineering. The AIAA is the U.S. representative on the International Astronautical Federation and the International Council of ...
for the Mariner television experiments in 1967 and the
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
Exceptional Scientific Achievement Medal in 1971. In the 1970s, Leighton's interest shifted to the development of large, inexpensive
dish antenna A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or ...
which could be used to pursue
millimeter-wave Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz). It lies between the super high frequency band and the ...
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 o ...
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 The Caltech Submillimeter Observatory (CSO) was a 10.4-meter (34 ft) diameter submillimeter wavelength telescope situated alongside the 15-meter (49 ft) James Clerk Maxwell Telescope (JCMT) at Mauna Kea Observatories. It was engaged in ...
on
Mauna Kea Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak ...
,
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
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 Nat ...
and served on its Space Science Board. Leighton shared the
Rumford Prize Founded in 1796, the Rumford Prize, awarded by the American Academy of Arts and Sciences, is one of the oldest scientific prizes in the United States. The prize recognizes contributions by scientists to the fields of heat and light. These terms ...
in 1986 for advancements in
Infrared Astronomy Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in be ...
, and won the
James Craig Watson Medal 400px, James Craig Watson Medal The James Craig Watson Medal was established by the bequest of James Craig Watson, an astronomer the University of Michigan between 1863 and 1879, and is awarded every 1-4 years by the U.S. National Academy of Scien ...
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 ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'' published Leighton's obituary on 14 March 1997, five days after his death. The
Los Angeles Central Library Richard J. Riordan Central Library, also known as the Los Angeles Central Library, is the main branch of the Los Angeles Public Library (LAPL), in Downtown Los Angeles. It is named after Mayor of Los Angeles Richard Riordan. It consists of tw ...
, 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 Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
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