Murray Gell-mann
Giant of theoretical physics who was awarded the Nobel Prize for his work on elementary particles
MURRAY GELL-MANN, the theoretical physicist, who has died aged 89, discovered and named the quark, the basic building block of atomic nuclei, though that was only a small part of his contribution to science.
From his early years, Gell-mann harboured an almost God-like ambition to discover the rules that link the determinism of particle physics with the unpredictable complexities seen in nature. Like Einstein he sought a unifying theory to enable the workings of the universe to be understood. He was not a laboratory scientist and liked to say that all he needed to understand the world was a pencil, some paper and a wastepaper basket.
Though Gell-mann did not succeed in finding the theory of everything, his quest led him to construct a series of predictive theories which have changed the way scientists see the world. He won the 1969 Nobel Prize for his work on the theory of elementary particles and was one of the principal architects of what is known as the “standard model” of the structure and properties of matter. “Our work is a delightful game,” he declared at the Nobel banquet.
Gell-mann made his first great scientific breakthrough during the 1950s when scientists working with new high-energy particle accelerators were baffled to find that cosmic ray particles raining down on earth did not seem to obey accepted laws of physics. Gell-mann proposed a quantifiable quality of “strangeness” – analogous to charge – to rationalise the unusual properties of these particles. This concept has enabled scientists to make predictions about the outcomes of natural processes.
His next achievement was to bring order to the baffling new science of particle physics. Scientists in the 1950s were discovering a bewildering assortment of seemingly unconnected subatomic particles, collectively known as the “particle zoo” as there seemed to be no logical way of classifying them into groups.
In 1961 Gell-mann suggested a unifying scheme which identified eight groups that shared common patterns. He produced a table similar to Mendeleev’s periodic table of the elements and with similar predictive qualities. This he called the “eight-fold way” – an ironic nod towards the Buddhist teaching that there are eight ways to achieve Nirvana.
The table contained gaps which, Gell-mann explained, foretold the
existence of particles that had not yet been detected. As the 1960s progressed, the particles were discovered precisely where they were supposed to be.
The question remained as to why these supposedly fundamental particles conformed to any pattern at all. In 1964 Gell-mann and George Zweig realised independently that the eightfold patterns would arise naturally if all the nuclear particles were built up from just three varieties of other particles, particles with a fractional electric charge – something hitherto considered impossible.
Gell-mann provisionally named these particles “quarks” to convey their strangeness; when he came across the phrase “Three quarks for Muster Mark!” in Finnegan’s Wake the matter was settled. Joyce, he observed, was “making a pun on quarts but I also thought the remark was appropriate to the quark because it combined in groups of three to make a neutron and proton”.
Gell-mann called his three quarks “up”, “down” and “strange”. He later thought that there might be a fourth, which he called “charm”. Soon others working postulated two more, “top” and “bottom”. By the mid-1970s the quark concept had been resoundingly confirmed by discoveries in more powerful particle accelerators. There are now known to be six varieties, or “flavours”, of quarks.
He suggested that quarks are confined within the atom by forces coming from the exchange of “gluons”. He and others constructed the quantum field theory of quarks and gluons, “quantum chromodynamics”, a theory that deals with the strong nuclear force binding protons and neutrons together at the heart of atoms.
In the 1970s Gell-mann turned his attention back to a childhood interest in languages and species. What is it, he wondered, that links a world where adaptation and learning has produced such diversity, to the basic subatomic particle determined by physical laws and to whose properties and behaviour history is completely irrelevant?
Gell-mann proposed a new theory called complexity theory. Complex systems, he suggested, are everywhere alike, from learning a language to the workings of the immune system, from evolution to an artist implementing a creative idea. All these processes involve testing models against reality then adjusting them to suit.
This complex adaptive process, he argued, could in theory be predicted using sophisticated mathematical and physical models which combine the laws of physics and a long series of chance events.
In 1984 he co-founded the Santa Fe Institute in New Mexico, a think tank where scientists were encouraged to break down barriers between disciplines to study complex adaptive systems with a view to discovering general rules and formulating predictive mathematical models.
Small and stooped, with white hair curling over a pink scalp, Gell-mann himself often seemed to be a walking example of complexity theory, combining a vast intellectual ambition with a mania for detail. He was fluent in 12 languages (he would correct the Ukrainian pronunciation of native Ukrainians and disparage the Swahili of Kenyans), and erudite on subjects ranging from prehistoric south-west American pottery to psychology and from Shakespeare to early 20th century poetry.
To say Gell-mann did not suffer fools gladly would be an understatement: “Are you asking that question for yourself or on behalf of some idiot?” he would bark at a questioner whose inquiry he did not like. By conventional standards he seemed obnoxious and intimidating, but this did not arise out of personal hostility but out of Gellmann’s love of debate for its own sake. Those few reasonably willing and able to cross swords with him found him great fun.
His relationships with fellow scientists tended to be conducted as a fierce game of intellectual oneupmanship. At the California Institute of Technology, where he taught from 1955 to 1993, Gell-mann liked nothing better than to argue theory with his fellow physicist, Richard Feynman.
The two scientists would engage in epic debates, scrapping for days in what they called “twisting the tail of the cosmos” and others termed the battle of the superegos. “We try to keep them apart as much as possible,” said Mrs Feynman after a particularly trying dinner party.
Murray Gell-mann was born on 15 September 1929, in New York, the son of Jewish immigrants from Austria. As a child he spent hours poring over books and pondering deep questions and was known in his neighbourhood as “the walking encyclopaedia”.
He had an extraordinary gift for mathematics and languages and wanted to study archaeology or linguistics. But his father persuaded him to study Physics and he entered Yale at 13. He completed a degree at 18 and a doctorate in 1950, aged 20, at the Massachusetts Institute of Technology. Soon he was at the cutting edge of theoretical physics, working at Princeton when Einstein was there.
In 1952 Gell-mann became a member of the Institute for Advanced Study at Princeton, and went on to teach at the University of Chicago and the California Institute of Technology.
He was a director of the JD and CT Macarthur Foundation, a member of the National Academy of Sciences and the American Academy of Arts and Sciences, a Fellow of the American Physical Society and a Foreign Member of the Royal Society of London.
He wrote the popular science book, The Quark and the Jaguar (1994), a compendium of breakthroughs in abstract thought – such as relativity, electromagnetism and natural selection – which had made the universe yield its secrets.
Murray Gell-mann married, in 1955, Margaret Dow, an Englishwoman. She died in 1981 and in 1992 he married Marcia Southwick, a fellow professor at the Santa Fe Institute, with whom he had a stepson; they divorced, and he is survived by his stepson, and by a son and daughter from his first marriage.