Murray Gell-Mann circa 2014 (Photo: Minesh Bacrania for the Santa Fe Institute)

Murray Gell-Mann, a Nobel-laureate who revealed symmetry and order in the world of subatomic particles and leveled his genius at complex mysteries of life and mind, died peacefully May 24, 2019. He was 89 years old.

Though he was best known for his contributions to particle physics, for which he won the 1969 Nobel prize in physics, Gell-Mann wanted to understand the “chain of relationships” that connected the universal laws of physics to complex systems like economies and human cultures. He described these two extremes of interest in his 1994 book, The Quark and the Jaguar, as “two aspects of nature…on the one hand, the underlying physical laws of matter and the universe, and on the other, the rich fabric of the world that we perceive directly and of which we are a part.”

To enable a rigorous study of the latter aspect of reality — the fabric of the complex world around us — Gell-Mann co-founded the Santa Fe Institute in 1984, 15 years after winning the Nobel Prize in physics for his classification of elementary particles. At SFI he collaborated with economists, linguists, biologists, computer scientists, and with other physicists who shared his passion for finding fundamental principles in learning, evolving systems.

"Murray was thinking of complexity from his boyhood days onwards,” said SFI Distinguished Shannan Professor Geoffrey West in a 2015 ceremony honoring Gell-Mann. “It was a passion of his. And in some ways, despite his extraordinary contributions to high-energy physics, to the standard model, to supporting the String Theory effort, he always had this passion waiting in the wings of complexity, meaning how do we understand ... all the nonlinear interactions or the extraordinary phenomena growing on this earth. Where did that come from in regard to the fundamental laws of nature?”

Early years

“Almost everything I’m interested in now, except perhaps physics, was something I was interested in early on,” Gell-Mann told filmmaker Celia Lowenstein in an interview for “Simply Complex: The Life and Times of Murray Gell-Mann.”

Gell-Mann was born in 1929 to a family of immigrants in New York City. Growing up, he went birdwatching with his older brother Benedict (d. 2007), who taught the three-year-old Murray to read from a cracker box. Benedict described Murray as “precocious,” from a young age being able to multiply numbers in his head and perform other feats of "mental gymnastics that most people couldn’t do.” The brothers shared a fondness for birdwatching and coin collecting that Murray carried into adulthood, along with his love for languages and natural history, gleaned partly from his habit of reading encyclopedias.

After Gell-Mann graduated valedictorian of his high school at age 14, he enrolled at Yale University. There, he studied physics, having “compromised’ with his father in an argument as to whether he should pursue engineering at his father’s suggestion, or his own inclination towards archaeology or linguistics. He earned his bachelor’s degree in physics in 1948. He went on to obtain his Ph.D. in physics from the Massachusetts Institute of Technology (MIT) in 1951 at the age of 21.

“If a child grows up to be a scientist,” Gell-Mann once said, “he finds that he is paid to play all day at the most exciting game ever devised by mankind.”

Nobel prize & physics

After completing his Ph.D., Gell-Mann joined the University of Chicago's Institute for Nuclear Studies, where he worked “down the hall” from physicist Enrico Fermi. Gell-Mann introduced the concept of quantum “strangeness,” which explained the unexpectedly slow decay patterns in certain particles.

Gell-Mann joined the faculty at the California Institute of Technology (Caltech) in 1955. In 1958, he co-authored a paper on the fundamental symmetry structure of the weak nuclear force with Caltech colleague Richard Feynman. The theory underlies the radioactive decay of the neutron and was independently proposed by another team of physicists — George Sudarshan and Robert Marshak. Gell-Mann also contributed to the study of cosmic ray particles and began his interest in the classification of subatomic particles which would eventually earn him a Nobel prize in 1969.

The field of particle physics in the late 1950s and early 1960s was often described as a “particle zoo,” littered with more than 100 so-called elementary particles that had been either predicted by mathematical theory or observed in experiments with particle accelerators. In 1961, Gell-Mann and Yuval Ne’eman independently proposed a scheme for ordering these subatomic particles onto clusters of eight and ten based on a symmetry called SU(3). The “Eightfold Way,” which Gell-Mann poetically named after the Buddhist eightfold path to enlightenment, has been likened to the Mendele’ev Periodic Table of Elements in chemistry because it classified subatomic particles, like protons, neutrons, mesons, and baryons, into groups with similar and related properties. Furthermore, it described their interactions and, equally importantly, opened the door for predicting the existence of new particle states, which were subsequently discovered.

In 1964, Gell-Mann and George Zweig independently proposed the existence of “quarks" as the fundamental building blocks of subatomic particles that explained the regularities and their classification under the group SU(3). Although originally conceived by Gell-Mann as mathematical constructs that explained these regularities in the properties of the elementary particles, quarks as physical entities were later confirmed by experiments at the Stanford Linear accelerator in the late 1960s. Quarks as the building blocks of matter are now firmly established and just this year (2019) an exotic particle predicted by Gell-Mann, the “pentaquark” — composed of five quarks — was confirmed at CERN’s Large Hadron Collider.

Gell-Mann himself worked at CERN in the early 1970s and, with his collaborator Harald Fritzsch, developed the fundamental theory of the strong nuclear force — Quantum Chromodynamics (QCD) — that describes the basic interaction between quarks and gluons. It is a major component of the Standard Model of the Elementary Particles.

According to External Professor Jim Hartle (UC Santa Barbara), Gell-Mann’s Ph.D. student and long-time collaborator, “Murray had a broad interest in science which led him to work many different areas inside physics and without.” For instance, he worked decades with Hartle (UC Santa Barbara) on the foundations of quantum mechanics and its application to cosmology through their decoherent histories quantum theory.

In a speech delivered in 2014, when Gell-Mann was awarded Germany’s prestigious Helmholtz Medal, Hartle evoked an injunction often attributed to Erwin Schrödinger “The task is not to see what no one else has seen, but to think what no one else has thought, about that which everyone else has seen. That is Murray Gell-Mann.”

Complexity's great polymath

In his book, Gell-Mann described particles as immutable and interchangeable. “Elementary particles,” he wrote, “have no individuality.” He struggled with how to connect his understanding of these particles to his experience as an individual person, always feeling driven to learn more about individual cultures, individual languages, and individual species in the natural world.

“Losing Murray is like losing the Encyclopaedia Brittanica,” says author Cormac McCarthy, Gell-Mann’s longtime friend and a Fellow at the Santa Fe Institute. “He knew more things about more things than anyone I’ve ever met.”

Coincidentally, Gell-Mann served on the Encyclopedia Britannica’s board of directors, and also held advisory positions at a multitude of foundations and societies.*

Geoffrey West describes Gell-Mann as “a great polymath,” and “the 20th century’s renaissance man” for the breadth of interests he pursued. At the Santa Fe Institute, Gell-Mann continued to pursue physics alongside archaeology, economics, history, and linguistics. He observed that complexity often emerges from simple laws, and wrote that regularities in complex systems "arise from a combination of the simple fundamental laws and the operation of chance, which can produce frozen accidents.”

As an analogy, Gell-Mann cited the regular appearance of Henry VIII’s visage on coins and in documents as a predictable consequence of the accident of his older brother’s death.

At the Institute, Gell-Mann actively researched the evolution of human languages with Ilia Peiros, External Professor George Starostin (Russian State University for the Humanities), and numerous other collaborators around the world. Their ongoing analyses of language families across long time depths seeks to create a “family tree” connecting languages to their ancestors and to the possibility of a single “proto-language.” Gell-Man also worked on an evolutionary explanation for word order of subjects, verbs, and objects.

"Murray was a joint link, and a guiding presence that brought together the people working here in America and Russia,” Starostin says. "He set us up here at SFI which is a great environment, because you have a lot of people working here in complexity and statistical methods, they can look at it and tell us if [our analysis] makes statistical and mathematical sense.”

With External Professor Seth Lloyd (MIT), Gell-Mann worked to characterize complexity based on the length of a description of a complex system’s regularities.

Gell-Mann sought such regularities not only in languages but in human history and in the appearance of new technologies. He was also fascinated by the culture and world-views of the Southwest Puebloan peoples.

He kept an “astounding” collection of ancestral Pueblo pottery at his home in Santa Fe. External Professor Scott Ortman (CU Boulder), an archaeologist, spent several days cataloging the collection with a student. Ortman remarked: "I couldn’t help but notice the correspondences between his display and the periodic table — a prototypical example of every variety, arranged in rows and columns according to their colors and symmetries. It was a wonderful expression of his belief in the unity of complex systems everywhere you find them.”

As he ranged from one complex system to another while working at the Santa Fe Institute, Gell-Mann nevertheless contributed to his “primary” field of physics. He published work on entropy with External Professor Constantino Tsallis (Centro Brasileiro de Pesquisas Fisicas) and contributed to work on scaling laws and renormalization with West and External Professor Juan Perez-Mercader (Harvard).

Gell-Mann’s most recent published paper, which appeared in 2016 in the journal Chaos, sought to re-conceptualize a fundamental approach to evaluating “gambles” in economics, such as whether to make a bet. External Professor Ole Peters (London Mathematical Laboratory) the paper’s lead author, first expressed the idea during an SFI seminar in 2010, which Gell-Mann attended.

“Working with Murray was fabulous,” Peters recalls. "He was someone who could completely detach himself from his own thoughts and creations. Even though we were separated by about two generations, hundreds of honors,** and a Nobel prize, in our interactions that didn’t exist. We were just two friends sitting down and trying to figure out a puzzle. … [Murray] was in it for the joy of intellectual discovery and absolutely nothing else."

In response to learning of Gell-Mann's death, SFI President David Krakauer wrote:

"I have often heard it said that after the 19th century it was no longer possible to be both deep and broad — that we had optimistically seen the last of the great polymaths in Hermann von Helmholtz who died 1894 or more pessimistically with the earlier passing of Johann Wolfgang von Goethe in 1832. But I know this cynicism to be misplaced because I have benefited from the multitudinous accomplishments of John Von Neumann (who died in 1957) and personally known a living polymath of equal, monumental, distinction — a mind both cavernous and extensive — animated by the most intense fire of roguish curiosity that I have ever beheld. This is Murray Gell-Mann who passed away this morning after having revolutionized physics, established the foundations of complexity science, and helped found the Santa Fe Institute. And in large part as a consequence of his example and his cognitive pattern, the world will benefit from future minds discontent with the strictures of the disciplines, the moats of the academies,  and proceed animated by the insight of one of his favorite writers, Jorge Luis Borges who wrote, “There is no pleasure more complex than that of thought and we surrendered ourselves to it.”

Murray Gell-Mann is survived by his son Nicolas Gell-Mann and daughter Elizabeth Gell-Mann.

Readers who knew Gell-Mann are invited to share remembrances over social media. Comments can be added to SFI's announcements on Twitter and on Facebook and can also be emailed to news@santafe.edu.

Notes

*Gell-Mann was a director of the John D. and Catherine T. MacArthur Foundation (1979 – 2002); a board member of the Wildlife Conservation Society (1994-2006), and a Citizen Regent of the Smithsonian Institution (1974-1978).  He belonged to the National Academy of Sciences, the American Academy of Arts and Sciences, the American Philosophical Society, and the Council on Foreign Relations; and was also a Foreign Member of the Royal Society of London. He also served on the U.S. President’s Science Advisory Committee (1969-1972) and the President’s Committee of Advisors on Science and Technology (1994 to 2001).

**In addition to his 1969 Nobel prize, Gell-Mann was listed on the United Nations Environmental Program’s Roll of Honor for Environmental Achievement, The Global 500 (1988), and shared the 1989 Ettore Majorana “Science for Peace” prize (1989). Earlier, he was given the Ernest O. Lawrence Memorial Award of the Atomic Energy Commission, the Franklin Medal of the Franklin Institute, the Research Corporation Award, and the John J. Carty Medal of the National Academy of Sciences. Gell-Mann was awarded the Albert Einstein Medal (2005) and has received honorary degrees from many universities, including Cambridge, Columbia, Oxford, the University of Chicago, the University of Florida, and Yale. 

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[Updated Jun 18, 2019]