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Gell-Mann’s multi-dimensional genius

11 July 2019

Murray Gell-Mann was one of the great geniuses of the 20th century, says Lars Brink, and stands out among other Nobel laureates.

One of the 20th century’s most amazing brains has stopped working. Nobel laureate Murray Gell-Mann died on 24 May at the age of 89. It is impossible to write a complete obituary of him, since he had so many dimensions that some will always be forgotten or neglected.

Murray was the leading particle theorist in the 1950s and 1960s in a field that had attracted the brightest young stars of the post-war generation. But he was also a polyglot who could tell you any noun in at least 25 languages, a walking encyclopaedia, a nature lover and a protector of endangered species, who knew all the flowers and birds. He was an early environmentalist, but he was so much more. It has been one of the biggest privileges in my life to have worked with him and to have been a close friend of his.

Murray Gell-Mann was born into a Jewish immigrant family in New York six weeks before the stock-market crash of October 1929. He was a trailing child, with a brother who was nine years older and relatively aged parents. He used to joke that he had been born by accident. His father had failed his studies and, after Murray’s birth, worked as a guard in a bank vault. Murray was never particularly close to father, but often talked about him.

Child prodigy

According to family legend, the first words that Murray spoke were “The lights of Babylon”, when he was looking at the night sky over New York at the age of two. At three, he could read and multiply large numbers in his head. At five he could correct older people about their language and in discussions. His interest for numismatics had already begun: when a friend of the family showed him what he claimed was a coin from Emperor Tiberius’ time, Murray corrected the pronunciation and said it was not from that time. At the age of seven, he participated in – and won – a major annual spelling competition in New York for students up to the age of 12. The last word that only he could spell and explain was “subpoena”, also citing its Latin origins and correcting the pronunciation of the moderator.

By the age of nine he had essentially memorised the Encyclopaedia Britannica. The task sounds impossible, but some of us did a test behind his back once in the 1970s. The late Myron Bander had learnt and studied an incomprehensible word and steered the discussion on to it over lunch. Of course Murray knew what the word was. He even recalled the previous and subsequent entries on the page.

Murray’s parents didn’t know what to do with him, but his piano teacher (music was not his strong side) made them apply for a scholarship so that he could start at a good private school. He was three years younger than his classmates, yet they always looked to him to see if he approved of what the teachers said. His tests were faultless, except for the odd exception. Once he came home and had scored “only” 97%, to which his father said: How could you miss this? His brother, who was more “normal”, was a great nature lover and became a nature photographer and later a journalist. He taught Murray about birds and plants, which would become a lifelong passion.

At the age of 15, he finished high school and went to Yale. He did not know which subject he would choose as a major, since he was interested in so many subjects. It became physics, partly to please his father who had insisted on engineering such that he could get a good job. He then went to MIT for his doctoral studies, receiving the legendary Victor “Viki” Weisskopf as his advisor. Murray wanted to do something pioneering, but he didn’t succeed. He tried for a whole semester and at the same time studied Chinese and learnt enough characters to read texts. He finally decided to present a thesis in nuclear physics, which was approved but that he never wanted to talk about. When Weisskopf, later in life, was asked what his biggest contribution to physics was, he answered: “Murray Gell-Mann”.

At the age of 21 Murray was ready to fly and went to the Institute for Advanced Study (IAS) as one of Robert Oppenheimer’s young geniuses. In the next year he went to the University of Chicago under Enrico Fermi, first as an instructor and in a few years became an associate professor. Even though he had not yet produced outstanding work, when he came to Chicago he was branded as a genius. At the IAS he had started to work on particle physics. He collaborated with Francis Low on renormalisation and realised that the coupling constant in a renormalisable quantum field theory runs with energy. As would happen so often, he procrastinated with the publication until 1954, by which time Petermann and Stückelberg had published this result.

This was during the aftermath of QED and Gell-Mann wanted to attack the strong interactions. He started his odyssey to classify all the new particles and introduced the concept of “strangeness” to specify the kaons and the corresponding baryons. This was also done independently by Kazuhiko Nishijima. When he was back at the IAS in 1955, Murray solved the problem with KL and Ks, the two decay modes of the neutral kaons in modern language (better known as the τθ puzzle). According to him, he showed this to Abraham Pais who said, “Why don’t we publish it?”, which they did. They were never friends after that. Murray also once told me that this was the hardest problem that he had solved.

A cavalcade of results

Aged 26, he lectured at Caltech on his renormalisation and kaon work. Richard Feynman, who was the greatest physicist at the time, said that he thought he knew everything, but these things he did not know. Feynman immediately said that Murray had to come to Caltech and dragged him to the dean. A few weeks later, he was a full professor. A large cavalcade of new results began to come out. Because he had difficulty relinquishing his works, they numbered just a few a year. But they were like cathedrals, with so many new details that he came to dominate modern particle physics.

After the ground-breaking work of T D Lee and C N Yang on parity violation in the weak interactions, Gell-Mann started to work on a dynamical theory – as did Feynman. In the end the dean of the faculty forced them to publish together, and the V–A theory was born. George Sudarshan and Robert Marshak also published the same result, and there was a long-lasting fight about who had told who before. Murray’s part of the paper, which is the second half, is also a first sketch of the Standard Model, and every sentence is worth reading carefully. It takes students of exegetics to unveil all the glory of Murray’s texts. Murray was to physics writing what Joseph Conrad was to novel writing!

Sometimes there are people born with all the neurons in the right place

Murray then turned back to the strong interactions and, with Maurice Lévy, developed the non-linear sigma model for pion physics to formulate the partially conserved axial vector current (PCAC). This was published within days of Yoichiro Nambu’s ground-breaking paper where he understood pion physics and PCAC in terms of spontaneous breaking of the chiral symmetry. In a note added to the proof they introduced a “funny” angle to describe the decay of 14O, which a few years later became the Cabibbo angle in Nicola Cabibbo’s universal treatment of the weak interactions.

Gell-Mann then made the great breakthrough when he classified the strongly interacting particles in terms of families of SU(3), a discovery also made by Yuval Ne’eman. The paper was never published in a journal and he used to joke that one day he would find out who rejected it. With this scheme he could predict the existence of the triply strange Ω baryon, which was discovered in 1964 right where he predicted it would be. It paved the way for Gell-Mann’s suggestion in 1963 that all the baryons were made up of three fundamental particles, which in the published form he came to call quarks, after a line in James Joyce’s Finnegans Wake, “three quarks for Muster Mark”. The same idea was also put forward by George Zweig who called them “aces”. It was a very difficult thing for Murray to propose such a wild idea, and he formulated it extremely carefully to leave all doors open. Again, his father’s approval loomed in the background.

With the introduction of current algebra he had laid the ground for the explosion in particle theory during the 1970s. In 1966, Weisskopf’s 60th birthday was celebrated, and somehow Murray failed to show up. When he later received the proceedings, he was so ashamed that he did not open it. Had he done so, he would have found Nambu’s suggestion of a non-abelian gauge field theory with coloured quarks for the strong interactions. Nambu did not like fractional charges so he had given the quarks integer charges. Murray later said that, had he read this paper, he would have been able to formulate QCD rather quickly.

Legacy

When, at the age of 40 in 1969, he received the Nobel Prize in Physics as the sole recipient, he had been a heavily nominated candidate for the previous decade. Next year the Nobel archives for this period will be open, and scholars can study the material leading up to the prize. Unfortunately, his father had died a few weeks before the prize announcement. Murray once said to me, “If my father had lived two weeks longer, my life would have been different.”

During the 1950s and 1960s Gell-Mann had often been described in the press as the world’s most intelligent man. With a Nobel Prize in his pocket, the attraction to sit on various boards and committees became too strong to resist. His commitment to conserving endangered species also took up more of his time. Murray had also become a great collector of pre-Columbian artefacts and these were often expensive and difficult to obtain.

In the 1970s, he was displaced from the throne by people from the next generation. Murray was still the one invited to give the closing lectures at major conferences, but his own research started to suffer somewhat. In the mid-1970s, I came to Caltech as a young postdoctoral fellow. I had met him in a group before, but trembled like an aspen leaf when I first met him there. He had, of course, found out from where in Sweden I came and pronounced my name just right, and demanded that everyone else in the group do so. Pierre Ramond also arrived as a postdoc at that time, having been convinced by Murray to leave his position at Yale. After a few months we started to work together on supergravity. We did the long calculations, since Murray was often away. But he always contributed and could spot any weak links in our work immediately. Once, when we were in the middle of solving a problem after a period of several days, he came in and looked at what we did and wrote the answer on the board. Two days later we came to exactly that result. John Schwarz, who was a world champion in such calculations, was impressed and humbled.

When I left Caltech I got a carte blanche from Murray to return as often as I wanted, during which I worked with Schwarz and Michael Green developing string theory. Murray was always very positive about our work, which few others were. It was entirely thanks to him that we could develop the theory. Eventually, I couldn’t go to the US quite as often. Murray had also lost his wife in the early 1980s and never really recovered from this. In the mid-1980s he got the chance to set up a new institute in Santa Fe, which became completely interdisciplinary. He loved nature in New Mexico and here he could work on the issues that he now preferred, such as linguistics and large-scale order in nature. He dropped particle physics but was always interested in what happened in the field. Edward Witten had taken over the leadership of fundamental physics and Murray could not compete there.

Being considered the world’s most intelligent person did not make Murray very happy. He had trouble finding real friends among his peers. They were simply afraid of him. I often saw people looking away. The post-war research world is a single great world championship. For us who were younger, it was so obvious that he was intellectually superior to us that we were not disturbed by it. All the time, though, the shadow of his father was sitting on his shoulder, which led him too often to show off when he did not need to.

Sometimes people are born with all the neurons in the right place. We sometimes hear about the telephone-directory geniuses or people who know railway schedules by heart, but who otherwise are intellectually normal, if not rather weak. The fact that a few of them every century also get the neurons to make them intellectually superior is amazing. Among all Nobel laureates in physics, Murray Gell-Mann stands out. Others have perhaps done just as much in their research in physics and may be remembered longer, but I do not think that anyone had such a breadth in their knowledge. John von Neumann, the Hungarian–American mathematician who, among other things, was the first to construct a computer was another such universal genius. He could show off knowing Goethe by heart and on his death bed he cited the first sentence on each page of Faust for his brother. Murray was certainly a pain for American linguists, as he could say so many words in so many languages that he could always gain control over a discussion.

There are so many more stories that I could tell. Once he told me “Just think what I could have done if I had worked more with physics.” His almost crazy interest in so many areas took a lot of time away from physics. But he will still be remembered, I hope, as one of the great geniuses of the 20th century.

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