Murray Gell-Mann (; September 15, 1929 – May 24, 2019) was an American theoretical physicist who played a preeminent role in the development of the theory of particle physics. Gell-Mann introduced the concept of quarks as the fundamental building blocks of the strongly interacting particles, and the renormalization group as a foundational element of quantum field theory and statistical mechanics. Murray Gell-Mann received the 1969 Nobel Prize in Physics for his contributions and discoveries concerning the classification of elementary particles and their interactions.
Gell-Mann played key roles in developing the concept of chirality in the theory of the and spontaneous chiral symmetry breaking in the strong interactions, which controls the physics of the light . In the 1970s he was a co-inventor of quantum chromodynamics (QCD) which explains the confinement of quarks in mesons and and forms a large part of the Standard Model of elementary particles and forces.
Propelled by an intense boyhood curiosity and love for nature and mathematics, he graduated valedictorian from the Columbia Grammar & Preparatory School aged 14 and subsequently entered Yale College as a member of Jonathan Edwards College. At Yale, he participated in the William Lowell Putnam Mathematical Competition and was on the team representing Yale University (along with Murray Gerstenhaber and Henry O. Pollak) that won the second prize in 1947.
Gell-Mann graduated from Yale with a bachelor's degree in physics in 1948 and intended to pursue graduate studies in physics. He sought to remain in the Ivy League for his graduate education and applied to Princeton University as well as Harvard University. He was rejected by Princeton and accepted by Harvard, but the latter institution was unable to offer him needed financial assistance. He was then accepted by the Massachusetts Institute of Technology (MIT) and received a letter from Victor Weisskopf urging him to attend MIT and become Weisskopf's research assistant. This would provide Gell-Mann with the financial assistance he required. Unaware of MIT's eminent status in physics research, Gell-Mann was "miserable" and in characteristic dark irony, said he first considered suicide.
Gell-Mann received his Ph.D. in physics from MIT in 1951 after completing a doctoral dissertation, titled "Coupling strength and nuclear reactions", under the supervision of Weisskopf. Subsequently, Gell-Mann was a postdoctoral fellow at the Institute for Advanced Study at Princeton in 1951, and a visiting research professor at the University of Illinois at Urbana–Champaign from 1952 to 1953. He was a visiting associate professor at Columbia University and an associate professor at the University of Chicago in 1954–1955, before moving to the California Institute of Technology, where he taught from 1955 until he retired in 1993.
Gell-Mann died on May 24, 2019, at his home in Santa Fe, New Mexico.
Gell-Mann was on sabbatical at the Collège de France for the academic year 1958–1959. Gell-Mann spent several periods at CERN, the laboratories of the European Organization for Nuclear Research in Geneva, Switzerland, including time as a fellow of the John Simon Guggenheim Memorial Foundation fellow.
In 1984 Gell-Mann was one of several co-founders of the Santa Fe Institute—a non-profit theoretical research institute in Santa Fe, New Mexico intended to study various aspects of a complex system and disseminate the notion of a separate interdisciplinary study of complexity theory.
In his 1994 popular book The Quark and the Jaguar: Adventures in the Simple and the Complex, Gell-Mann acknowledged financial support from Jeffrey Epstein, who contributed via the Santa Fe Institute.Reviews of The Quark and the Jaguar:
In 2003, Gell-Mann also contributed a letter to The First Fifty Years, a collection of birthday greetings for Epstein. Years later, in 2011, Gell-Mann reportedly attended the "Mindshift Conference" on Epstein’s private island, Little Saint James. The gathering was organized by Epstein and science promoter Al Seckel. Gell-Mann’s name also appeared in Epstein’s so-called "black book," a personal address book listing Epstein’s close contacts.
George Johnson has written a biography of Gell-Mann, Strange Beauty: Murray Gell-Mann, and the Revolution in 20th-Century Physics (1999), Although Gell-Mann himself criticized Strange Beauty for some inaccuracies, with one interviewer reporting him wincing at the mention of it, the book was acclaimed by a number of his colleagues.
In a review in the Caltech magazine Engineering & Science, Gell-Mann's colleague, the physicist David Goodstein, wrote: "I don't envy Murray the weird experience of reading so penetrating and perceptive a biography of himself. George Johnson has written a fine biography of this important and complex man". .
Physicist and Nobel laureate Philip Anderson, called the book "a masterpiece of scientific explication for the layman" and a "must read" in a review for the Times Higher Education Supplement and in his chapter on Gell-Mann from a 2011 book.
Gell-Mann's work in the 1950s involved recently discovered cosmic ray particles that came to be called and . Classifying these particles led him to propose that a quantum number, called strangeness, would be conserved by the strong and the electromagnetic interactions, but not by the weak interaction. Another of Gell-Mann's ideas is the Gell-Mann–Okubo formula, which was, initially, a formula based on empirical results, but was later explained by his quark model. Gell-Mann and Abraham Pais were involved in explaining this puzzling aspect of the neutral kaon mixing.
Murray Gell-Mann's fortunate encounter with mathematician Richard Earl Block at Caltech, in the fall of 1960, "enlightened" him to introduce a novel classification scheme, in 1961, for . A similar scheme had been independently proposed by Yuval Ne'eman, and has come to be explained by the quark model. Gell-Mann referred to the scheme as the eightfold way, because of the octets of particles in the classification (the term is a reference to the Eightfold Path of Buddhism).
Gell-Mann, along with Maurice Lévy, developed the sigma model of , which describes low-energy pion interactions.
In 1964, Gell-Mann and, independently, George Zweig went on to postulate the existence of , particles which make up the of this scheme. The name "quark" was coined by Gell-Mann, and is a reference to the novel Finnegans Wake, by James Joyce ("Three quarks for Muster Mark!" book 2, episode 4). Zweig had referred to the particles as "aces", but Gell-Mann's name caught on. Quarks, antiquarks, and were soon established as the underlying elementary objects in the study of the structure of hadrons. He was awarded a Nobel Prize in Physics in 1969 for his contributions and discoveries concerning the classification of elementary particles and their interactions. Simple listing of Nobel Prize in Physics, 1969 Retrieved February 15, 2017
In the 1960s, he introduced current algebra as a method of systematically exploiting symmetries to extract predictions from quark models, in the absence of reliable dynamical theory. This method led to model-independent sum rules confirmed by experiment, and provided starting points underpinning the development of the Standard Model (SM), the widely accepted theory of elementary particles.
In 1972 Gell-Mann, together with Harald Fritzsch, Heinrich Leutwyler and William A. Bardeen, considered a Yang-Mills theory of "quark color," and coined the term quantum chromodynamics (QCD) as the gauge theory of the strong interaction. The quark model is a part of QCD, and it has been robust enough to accommodate in a natural fashion the discovery of new "flavors" of quarks, which has superseded the eightfold way scheme.
Gell-Mann was responsible, with Pierre Ramond and Richard Slansky,M. Gell-Mann, Pierre Ramond and Richard Slansky, in Supergravity, ed. by D. Freedman and P. Van Nieuwenhuizen, North Holland, Amsterdam (1979), pp. 315–321. and independently of Peter Minkowski, Rabindra Mohapatra, Goran Senjanović, Sheldon Glashow, and Tsutomu Yanagida, for proposing the seesaw mechanism. This produces masses at the large scale in any theory with a right-handed neutrino. He is also known to have played a role in keeping string theory alive through the 1970s and early 1980s, supporting that line of research at a time when it was a topic of niche interest.
Gell-Mann was a proponent of the consistent histories approach to understanding quantum mechanics, which he advocated in papers with James Hartle.
Gell-Mann's extensive interests outside of physics included archaeology, numismatics, birdwatching and linguistics. Along with Sergei Starostin, he established the Evolution of Human Languages project at the Santa Fe Institute. As a Humanism and an Agnosticism, Gell-Mann was a Humanist Laureate in the International Academy of Humanism. The International Academy of Humanism at the website of the Council for Secular Humanism. Retrieved October 18, 2007. Some of this information is also at the International Humanist and Ethical Union website Novelist Cormac McCarthy saw Gell-Mann as a polymath who "knew more things about more things than anyone I've ever met...losing Murray is like losing the Encyclopædia Britannica."
Universities that gave Gell-Mann honorary doctorates include Cambridge, Columbia, the University of Chicago, Oxford and Yale.
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