GELL-MANN, Murray

(b. 15 September 1929 in New York City), distinguished theoretical physicist whose influential research at the California Institute of Technology (Caltech), proposing the existence of quarks, advanced the study of particle physics and led to his being awarded the 1969 Nobel Prize in physics.

The younger of two sons born to Austrian immigrants Arthur Gell-Mann, a teacher and bank guard, and Pauline Reichstein, a homemaker, Gell-Mann exhibited a precocious intellect, which included the ability to multiply large numbers in his head by the age of three. Often bored with school, Gell-Mann nevertheless excelled in his studies. In 1944 he graduated at the age of fourteen from Columbia Grammar School. He was class valedictorian, and his graduation speech was the subject of a cartoon for The New Yorker. Following his father's wishes, Gell-Mann majored in physics and graduated from Yale in 1948 with a B.S. degree. In 1951 he received a Ph.D. in physics from the Massachusetts Institute of Technology.

In 1951 Robert Oppenheimer invited Gell-Mann to the Institute for Advanced Study in Princeton, New Jersey. While at the institute, Gell-Mann met Albert Einstein and collaborated on subatomic work with Francis Low. A year later Gell-Mann began researching "strange particles" at the University of Chicago. Gell-Mann developed the "strangeness" theory of quantum numbers, which explained the longevity of these subatomic particles. Gell-Mann then left Chicago to teach at Columbia University. In 1955 he married J. Margaret Dow; they had two children. The couple moved to southern California, where Gell-Mann had accepted a position at the California Institute of Technology.

At Caltech, Gell-Mann's work in subatomic physics quickly established his reputation as a brilliant, cautious, and competitive physicist whose eclectic interests included conservation, linguistics, and ornithology. Working alongside another well-regarded Caltech physicist, Richard Feynman, Gell-Mann's public popularity grew, and he was profiled in the New York Times, Newsweek, and Time.

In 1961 Gell-Mann introduced the eightfold way, a taxonomic system that organized the subatomic particles baryons and mesons into familial groups called multiplets. In 1964 scientists working with an accelerator in Brookhaven were able to prove the validity of the eightfold way model. That same year, Gell-Mann further extended this model when he published a concise yet radical paper titled "A Schematic Model of Baryons and Mesons." This paper introduced the concept of quarks, a term he borrowed from James Joyce's novel Finnegans Wake. According to Gell-Mann, quarks came in three varieties, which he later termed "up," "down," and "strange"; these varieties could be combined to create variously charged protons or neutrons.

Although Gell-Mann proposed the theoretical existence of quarks, he initially was hesitant to believe in their physical existence. In the mid-1960s Gell-Mann gave numerous lectures in which he dismissed the reality of these subatomic particles. Yet many physicists, including Gell-Mann, believed that even if quarks did not physically exist, they remained a useful theoretical tool. However, Gell-Mann's initial caution about the existence of quarks did not prevent other physicists from carrying out experiments designed to locate individual quarks.

In addition to his physics research, Gell-Mann played an active role in policy and politics. He was a member of the European Center for Nuclear Research, and in the late 1950s he was recruited to join a group of physicists who sought to influence federal governmental policy. This group, which was called Jason, and whose other members included Edward Teller and Francis Low, met once a year during the 1960s to advise the Pentagon on a variety of cold war military matters, including antiballistic missile systems, and on the Vietnam War. In addition, Gell-Mann frequently was asked by both United States and international groups to consult on issues such as science education and arms control. In 1968 President Richard M. Nixon named Gell-Mann to his science advisory committee.

In 1969, at the age of forty, Gell-Mann was awarded the Nobel Prize in physics. Citing Gell-Mann's "contributions and discoveries concerning the classification of elementary particles and their interactions," which advanced the study of subatomic particles, the Nobel Committee for Physics named Gell-Mann as the lone recipient of that year's prize.

Several years after Gell-Mann was awarded the Nobel Prize, the existence of quarks was confirmed by data gathered with the Stanford Linear Accelerator (SLAC). By the mid-1970s, quarks were considered the foundation of the Standard Model, which has been used in physics to account for all subatomic particles and nongravitational forces.

In the years following the Nobel Prize award, Gell-Mann remained active at Caltech and continued to serve as an advisory member on numerous committees. His later work included research into supergravity, and he also served as an advocate for environmental issues and public literacy in the sciences. Gell-Mann's wife died of cancer in 1981, and in 1992 he married Marcia Southwick. During the mid-1980s Gell-Mann applied his interest and skill in multidisciplinary research to establishing the Santa Fe Institute, where he worked throughout the 1990s. He retired from teaching at Caltech in 1993 and in the next year published a best-selling book, The Quark and the Jaguar: Adventures in the Simple and the Complex.

Gell-Mann entered the particle physics field when it was a nascent science, and his insights, especially during the 1960s, revolutionized the understanding of particles. This work significantly contributed to the growth of the field. His insistence on simplicity and elegance in constructing theories and models of the subatomic world helped introduce coherence and organization to an originally chaotic system of unpredictable and little-understood particles. Gell-Mann's seminal work sharply influenced the subsequent direction of particle research. In addition, his analogies of subatomic particle behavior often were embedded with whimsical, creative, and simplified imagery, which helped to capture public interest in subatomic physics.

A detailed biography of Gell-Mann is George Johnson, Strange Beauty: Murray Gell-Mann and the Revolution in Twentieth-Century Physics (1999). Histories of particle physics include Laurie Brown and Lillian Hoddesson, eds., The Birth of Particle Physics (1983); and Leon M. Lederman and David N. Schramm, From Quarks to the Cosmos (1989).

Julia GoodFox

Murray Gell-Mann

The American physicist Murray Gell-Mann (born 1929) coined the definition "quarks" to describe the triplets of particles that form the cores of atoms. The Nobel Prize winner for Physics in 1969, he helped to develop the Stanford model, which describes the behavior of subatomic particles and their forces.

Murray Gell-Mann was born on September 15, 1929, in New York City of Austrian immigrant parents. A precocious child, he attended a special school for gifted children, where he took a physics course. "It was the dullest course I've ever taken," he told Omni magazine in 1985, "and the only course I've ever done badly in!"

Early Academic Career

Gell-Mann graduated from school at the age of 15 and entered Yale University, where he sailed through a bachelor's degree to earn his diploma in 1948. Next came graduate study at the Massachusetts Institute of Technology (MIT), where he claims to have found out, for the very first time, what true scientific research can achieve. Totally committed to his work, he completed his doctorate in 1951, and proceeded to the Princeton Institute for Advanced Studies, where he had been awarded a research grant.

Gell-Mann's first academic appointment was in 1952 with the Institute for Nuclear Studies at the University of Chicago, where he started the work on elementary particles that was to bring him the Nobel Prize in physics in 1969. In 1955 he moved to the California Institute of Technology (CalTech). A member of the National Academy of Sciences and the American Academy of Arts and Sciences, Gell-Mann was the recipient of the Dannie Heineman Prize of the American Physical Society in 1959 and of numerous special lectureships and honors.

Order out of Chaos

Gell-Mann was one of the young physicists of the 1950s who tried to bring order into the chaotic field of elementary particles. In 1953 he proposed the invariant quality of "strangeness" to explain the behavior of some of the elementary particles. This quality, he noted, was conserved in strong and electromagnetic interactions but not in weak interactions. Strangeness proved useful in ordering the particles to form a classification chart somewhat analogous to the periodic table of elements. The chart not only listed families of particles, but by means of it Gell-Mann was able to predict the existence of a hitherto unknown particle, omega-minus, which was detected in 1964.

Physicists began using the term "strange particles" to describe a group of particles, inclusive for K-mesons and hyperons, that exhibited several peculiarities. To explain the anomalously long lifetimes of these particles, Gell-Mann advanced the theory of "associated production": the strong forces responsible for strange particles could act to create them only in batches of more than one at a time. Using his strangeness formulations, Gell-Mann also gave descriptions in detail of numerous decay events of strange particles, as well as prophesying the existence of the neutral xi particle.

In his continuing search for a more general elementary particle theory, Gell-Mann introduced a hypothetical particle, the quark, which is viewed as the fundamental stable constituent of the other particles and therefore is possibly the ultimate building block in the physical universe. Although quarks were not known to exist in the early 1960s when he began to work on particle physics, by the mid-1990s six types, forming three pairs, had been positively identified, and Gell-Mann does not rule out the possibility that there may be many more waiting for discovery.

During the Cold War years, Gell-Mann's work on particle physics was useful to the U.S. defense industries and the military. Notable among his assignments was his antisubmarine work for the Rand Corporation, and his service as a consultant to the Institute for Defense Analysis, especially with regard to the detection of nuclear test detonations.

His formal place of employment, however, was the University of Chicago, where he remained until 1955. The following year he took a professorship at CalTech.

A settled home on the coveted west coast notwithstanding, Gell-Mann left California in 1993 to work at the Santa Fe Institute—an institution he co-founded in 1984— to focus on complex adaptive systems, an interdisciplinary field.

Gell-Mann has written and co-authored many papers. His longer works include: The Discovery of Subatomic Particles, (1983) and The Quark and the Jaguar.

A Man of Many Interests

A man of wide interests, Gell-Mann speaks 13 languages fluently, is an accomplished ornithologist, and is very knowledgeable about the archeology of the Southwestern United States. A passionate conservationist, he helped to establish a nonprofit organization called the World Resources Institute.

Further Reading

Information on Murray Gell-Man can be found in Omni (May, 1985) and The Scientific Life (1962), contains an interesting interview with Gell-Mann. For background information on elementary particle physics see David Park, Contemporary Physics (1964). □

GELL-MANN, MURRAY

GELL-MANN, MURRAY (1929– ), U.S. theoretical physicist. Born in New York City and educated at Yale, which he entered at the age of 15 (B.S. 1948), and Massachusetts Institute of Technology (Ph.D. 1951), Gell-Mann studied physics rather than the languages and archaeology he originally preferred, because his father, who ran a language school, warned him that he would never be able to make a living. Gell-Mann taught at the Institute for Nuclear Studies of the University of Chicago from 1952 to 1955, while studying under Enrico Fermi, and at California Institute of Technology from 1955 until his retirement as Robert Millikan Professor of Theoretical Physics, Emeritus, in 1993. He held numerous visiting professorships at American and European universities, was made a member of the National Academy of Sciences, a fellow of the American Physical Society and other academic institutions, and served on a number of official bodies including the President's Science Advisory Committee (1969–72), the Board of Regents of the Smithsonian Institution (1974–88), and the President's Committee of Advisors on Science and Technology (1994–2001). He was later a distinguished fellow at the Santa Fe Institute, a research foundation which he helped to found in 1982 in Santa Fe, New Mexico. He also taught part of the year at the University of New Mexico in Albuquerque.

Gell-Mann was awarded the Nobel Prize for physics in 1969 for his revolutionary work in particle physics, a field in which he was preeminent for over 20 years. The explanatory theory he formulated in 1963 accounted for the presence of the many particles discovered in atomic nuclei and posited that all such particles are composed of basic units that Gell-Mann named "quarks" (a word taken from one of his favorite books, James Joyce's Finnegans Wake), which his own and others' research indicated were one of three fundamental, irreducible building blocks of matter (the others are leptons and intermediate vector bosons). The existence of quarks, and the accuracy of Gell-Mann's theoretical prediction that there were likely six types, was confirmed by experimentation with particle accelerators in the 1980s and 1990s. Gell-Mann's work led to the development of the field theory of quantum chromodynamics, which describes the interactions of subatomic particles.

From the 1980s Gell-Mann, who had a well-deserved reputation as a polymath (he described his interests as including "natural history, historical linguistics, archaeology, history, depth psychology, and creative thinking, all subjects connected with biological evolution, cultural evolution, and learning and thinking"), tried to develop a theory of complex adaptive systems that would reflect his concerns about the environment: "restraint in population growth, sustainable economic development, and stability of the world political system." His 1994 book The Quark and the Jaguar, written for general readers rather than fellow scientists, had its origins in this concern. At the Santa Fe Institute he also headed the Evolution of Human Languages Program, which seedks to establish the historical relationships among human languages, on the assumption that all of them may belong to "superfamilies" derived from an original "proto-language" whose characteristics may be discovered.

Gell-Mann's publications include Lectures on Weak Interactions of Strongly Interfacing Particles (1961), The Eightfold Way: A Review with a Collection of Reprints (1964, with Yuval Ne'eman), The Quark and the Jaguar (1994), and two edited collections, The Evolution of Human Languages (1992, edited with John A. Hawkins) and Understanding Complexity in the Prehistoric Southwest (1994, edited with George J. Gumerman). In addition, a full-scale biography of Gell-Mann was published by George Johnson: Strange Beauty: Murray Gell-Mann and the Revolution in 20^th-Century Physics (1999).

[Drew Silver (2^nd ed.)]

Gell-Mann, Murray (1929- )

American physicist

Prior to the 1940s and 1950s, only a handful of fundamental particles—among them the proton, neutron, electron, and positron—had been discovered in particle physics research. The study of cosmic rays and particle accelerator reactions revealed that the composition of matter was much more complex than previously thought. Dozens, and then hundreds of new particles were discovered. Most appeared to meet the criterion of being a basic form of matter, but they often had unexpected properties. For example, some had lifetimes much longer (10⁻⁹ second) than was predicted for them, based on their mass. Because of these properties, they were collectively referred to as "strange" particles. Before long, physicists aggressively began searching for a way to organize and make sense out of the particle zoo they had discovered. A leading figure in this search was Murray Gell-Mann.

Gell-Mann was born in New York City in 1929. He earned his bachelor of science degree at Yale University at the age of nineteen and his Ph.D. from the Massachusetts Institute of Technology three years later. He worked briefly at the Institute for Advanced Studies and then taught at the University of Chicago from 1952 to 1954. Gell-Mann then moved to the California Institute of Technology, where he became R.A. Millikan professor of theoretical physics in 1966.

Gell-Mann has made a number of contributions to the effort to organize the "particle zoo." In 1953, he suggested that basic particles contain an intrinsic property known as "strangeness," not unlike charge or spin. He showed how the conservation of strangeness in a particle reaction could explain a number of observations made of these new particles. A similar concept was developed independently by the Japanese physicist, Kazuhiko Nishijima.

Gell-Mann next applied himself to the development of a system for placing the known elementary particles into a small number of groups. He observed that particles could be classified into a relatively small number of families of multiplets that have similar properties. Gell-Mann referred to his classification system as the eight-fold way, after the eight ways of right living taught by the Buddha.

Gell-Mann's scheme accomplished for elementary particles what Dmitri Mendeleev's periodic table had achieved for the elements. Furthermore, like the periodic table, the eight-fold way predicted the existence of new elementary particles. The discovery in 1964 of one such particle, the omega minus (Ω–) provided dramatic confirmation of Gell-Mann's ideas. The Israeli physicist, Yuval Ne'emann, independently proposed a similar system of classification at about the same time.

Finally, Gell-Mann suggested that the hundreds of elementary particles might, in fact, be composed of a very small number of even more basic particles. He called these particles quarks, from James Joyce's Finnegan's Wake, "Three quarks for Master Mark!" The first three quarks to be discovered were given the somewhat whimsical names of "up," "down," and "strange." Gell-Mann has also made important contributions to the theory of quantum chromodynamics, which attempts to explain interactions among quarks.

See also Atomic structure; Quantum theory and mechanics

Murray Gell-Mann

1929-

American Physicist

Following World War II, a new level of governmental support for high energy physics research in the United States and Europe led to the discovery of numerous new elementary particles, most being substantially heavier than the electron and many heavier than the proton. Murray Gell-Mann played a key role in bringing order to this "zoo" of newly discovered particles, first through the introduction of a new quantum number called "strangeness" and then through a unification named (partly in jest) the "eightfold way," which led to the "quark" model of the more massive subatomic particles. In his later career, Gell-Mann played an essential role in interesting physicists in a new interdisciplinary field devoted to the study of complex phenomena and in setting up the Santa Fe Institute as a center for research in this area.

Murray Gell-Mann was the son of Arthur Gell-Mann, the owner of an unsuccessful language school and a man learned in several scientific disciplines. A polymath and child prodigy, Gell-Mann entered Yale University at the age of 15 and received his Ph.D. in physics from the Massachusetts Institute of Technology at the age of 21. As Gell-Mann began his scientific career, the generation of physicists who had built the atomic bomb under the Manhattan Project were returning to academic research or working in new national laboratories. A major thrust of the research was understanding the forces at work within the atomic nucleus. Particle accelerators were built to create highly energetic beams of protons or electrons that could create substantial numbers of unstable particles when they collided with a target. These accelerators complemented a very limited number of observations made on cosmic rays, which are very energetic particles that collide with Earth's atmosphere.

Gell-Mann's first major contribution to physics involved the identification of a new quantum number, strangeness, needed to explain the unusual stability of newly discovered particles somewhat heavier than a proton. Gell-Mann correctly reasoned that strangeness was a property conserved under the strong nuclear force but not concerned with the weak nuclear force, which operates on a much slower time scale. Gell-Mann's main contribution to physics, however, is the classification of the heavier baryons (particles more massive than the proton) and the lower-mass meson according to an abstract set of symmetries described by Lie Groups, mathematical structures introduced almost a century earlier by the Norwegian mathematician, Marius Sophus Lie (1842-1899). Application of the Lie Group designated SU(3) suggested that elementary particles would occur in groups of eight or ten and made possible the prediction of new particles, particularly the omega-minus, which was discovered in 1964. The SU(3) symmetry also allowed for a set of three fundamental particles, particles Gell-Mann named "quarks" after a nonsensical line in the novel Ulysses by James Joyce. Although initially unpopular, the quark model has become an accepted part of quantum chromodynamics, the theory of the strong nuclear force.

Gell-Mann received the Nobel Prize for physics in 1969. Unlike most recent Nobel awards, this one was not shared with other scientists, thus recognizing Gell-Mann's overall career rather than any one particular achievement. He has maintained a broad range of intellectual interests, including biology and languages, and as many physicists became interested in the nature of complex and nonlinear phenomena in the 1980s he assumed a leadership role. In 1983 Gell-Mann was a featured speaker at a meeting intended to set the agenda for a new research institution, the Santa Fe Institute, which was designed to bring together researchers from a broad range of the social and natural sciences to study the common features of "complex systems." He continues to be a strong advocate of interdisciplinary research.

DONALD R. FRANCESCHETTI