Murray Gell-Mann, one of the foremost figures in the development of the Standard Model of particle physics, and recipient of the 1969 Nobel prize in physics, passed away on 24 May at the age of 89. Gell-Mann was responsible for naming quarks, the elementary particles found within hadrons such as protons and neutrons: he borrowed the term from James Joyce’s Finnegans Wake.
In 1961, Gell-Mann had introduced a scheme called the Eightfold Way for classifying hadrons, based on the mathematical symmetry known as SU(3), for which he won the Nobel prize. Gell-Mann built upon this work in a new model that could successfully describe – among other phenomena – the magnetic properties of protons and neutrons. But Gell-Mann’s model required there to be three new elementary particles, which he called quarks, whose existence he proposed in 1964. Independently, and in the same year, Georg Zweig also described these elementary particles, calling them “aces”.
The existence of quarks was experimentally demonstrated in the late 1960s by experiments at the Stanford Linear Accelerator Center (SLAC). Subsequently, results from the Gargamelle bubble chamber at CERN contributed evidence showing that these particles have charges of ⅓ or ⅔ that of an electron or proton, as predicted by Gell-Mann and Zweig.
Numerous experiments at CERN are exploring the theory that describes quarks and their interactions, called quantum chromodynamics. At the Large Hadron Collider (LHC), physicists are still discovering novel combinations of Gell-Mann and Zweig’s particles, further testing the Standard Model.
Gell-Mann spent some time at CERN in the ’60s, and returned in the late-’70s, when he lectured on the grand unification of the different forces in nature. In his later life, Gell-Mann turned his curiosity and attention to linguistics, among other fields, and led the Evolution of Human Languages programme at the Santa Fe Institute, which he co-founded. He was also the Robert Andrews Millikan Professor Emeritus at Caltech.