A sewing-machine repairman’s son
Jerome Isaac Friedman was born in Chicago on March 28, 1930, the second of two sons of Selig and Lillian Friedman, née Warsaw, Jewish immigrants from Russia. His father came to the United States in 1913, served in the U.S. Army artillery in the First World War and then worked for the Singer Sewing Machine Company before starting his own small business repairing and selling used sewing machines. His mother crossed the Atlantic in 1914 on one of the last voyages of the Lusitania and supported herself in a garment factory until she married.
Neither parent had much formal schooling beyond English classes after they arrived, but both were self-taught and curious. His father read widely in science and political history, and the house was full of books; his mother, who had a lovely singing voice, loved opera. Friedman recalled that the education of their two boys was of paramount importance to them, and that even in hard times they found money for music and art lessons. They respected scholarship for its own sake, and they also told their sons that education opened doors in America.
The art student who chose physics
As a boy Friedman loved to draw and paint, and he entered a special art programme in high school that was almost an art school within a regular school. Then he read a short book called Relativity by Albert Einstein, and it opened, as he put it, a new vista. Offered a scholarship to the school of the Art Institute of Chicago, he turned it down against the strong advice of his art teacher and applied instead to the University of Chicago, chiefly because Enrico Fermi taught there. He won a full scholarship, without which, he said, his family could not have paid for university.
He entered the physics department in 1950, earned a master’s degree in 1953 and a doctorate in 1956. Fermi himself supervised him, and Friedman remembered being overwhelmed by his good fortune; Fermi’s crystal-clear lectures shaped the way he thought about physics for the rest of his life. When Fermi died in 1954, before the thesis was finished, John Marshall took over its supervision. As a postdoctoral researcher with Valentine Telegdi, Friedman was among the first to observe the violation of parity, a basic mirror symmetry, in the decay of the muon.
Learning to scatter electrons
In 1957 he joined Robert Hofstadter’s group at Stanford, where Hofstadter was using beams of electrons to measure the size and shape of atomic nuclei, work that would earn him a Nobel Prize. There Friedman learned the techniques of electron scattering and met Henry Kendall, a fellow researcher who became his lifelong collaborator. In 1960 Friedman joined the physics faculty of the Massachusetts Institute of Technology, and Kendall soon followed. Together they ran experiments at the Cambridge Electron Accelerator to test the theory of quantum electrodynamics.
The two-mile microscope
In 1963 Friedman and Kendall began working with Wolfgang Panofsky, Richard Taylor and others at the Stanford Linear Accelerator Center, SLAC, which was then building a two-mile-long accelerator to drive electrons to unprecedented energies of up to about 20 billion electron volts. For years the two MIT physicists commuted between Massachusetts and California, one of them almost always at SLAC.
From 1967 the SLAC-MIT team fired these electrons at targets of liquid hydrogen and deuterium and measured how they bounced off. The first experiments looked at the gentle, elastic scattering that earlier work had made familiar: protons behaved like soft, fuzzy balls that rarely deflected an electron far. Then the team looked at violent, so-called deep inelastic collisions, in which the electron lost much of its energy and the proton broke apart. Nobody expected anything new. Instead, far more electrons bounced off at large angles than a soft proton could explain. At first the physicists suspected a mistake in their corrections. After careful checking they concluded that the electrons were hitting small, hard, point-like objects inside the proton.
It was, the Nobel committee later said, a repetition at a deeper level of Ernest Rutherford’s discovery of the atomic nucleus. Theorists James Bjorken and Richard Feynman interpreted the hard centres as the quarks that Murray Gell-Mann and George Zweig had proposed as mathematical building blocks a few years earlier, objects that many physicists had doubted were real. Measurements on neutrons, completed by about 1975, filled in the picture and showed that the protons and neutrons also contain electrically neutral components, soon identified as gluons, the carriers of the force that binds quarks.
How the experiment worked
The experiment was, in principle, simple. Electrons with energies between about 4 and 21 billion electron volts were sent through a target of liquid hydrogen, whose nuclei are single protons, or of liquid deuterium, which adds neutrons. Two large magnetic spectrometers caught the scattered electrons, one at small angles of 6 and 10 degrees and the other at larger angles of 18, 26 and 34 degrees, and measured each electron’s energy. From the angle and the energy lost, the physicists could work out how hard the electron had struck, and what it had struck.
The comparison with Rutherford was apt. In 1909 Hans Geiger and Ernest Marsden, working in Rutherford’s laboratory in Manchester, found that a few alpha particles fired at thin metal foil were deflected through large angles, which Rutherford explained in 1911 by a small, hard nucleus at the centre of the atom. Sixty years later the SLAC-MIT team found unexpectedly frequent large-angle scattering again, one level deeper, and the hard centres inside the proton were quarks. Nobody had expected it: electron scattering from nucleons had been studied for two decades, and the new experiment was widely regarded as routine.
Why quarks matter
The SLAC-MIT experiments were the first direct evidence that quarks exist, and they changed physics. Their results pointed the way to quantum chromodynamics, the theory of the strong force, and so to the Standard Model, the framework that now describes every known particle of matter and three of nature’s four forces. As the Nobel committee noted, more than 99 per cent of the matter on Earth, including our own bodies, consists of quarks and the gluons that bind them.
That knowledge underpins much of modern physics. It is used to design and interpret the experiments at CERN’s Large Hadron Collider, where protons are smashed together and the debris of their quarks and gluons is studied, and it is the basis for calculations of how nuclei behave inside stars and reactors. Deep inelastic scattering, the technique Friedman, Kendall and Taylor pioneered, became one of the main ways physicists study the inside of the proton, and laboratories still use it today.
Teacher and statesman of science
After SLAC, Friedman’s group went on to experiments at Fermilab, including a large neutrino detector whose results in the early 1980s confirmed predictions of the Standard Model. He directed MIT’s Laboratory for Nuclear Science from 1980 and headed its physics department from 1983 to 1988, then happily returned to full-time teaching and research. He became an Institute Professor, MIT’s highest faculty rank, and served on many advisory panels, including the Department of Energy’s High Energy Physics Advisory Panel and as chair of the scientific policy committee of the planned Superconducting Super Collider.
He has spoken out for public support of science. In 2008 he was one of 20 American physics Nobel laureates who wrote to President George W. Bush urging him to reverse cuts to basic research funding, and he sits on the board of sponsors of the Bulletin of the Atomic Scientists, which works to reduce the danger of nuclear weapons. In 2016 Japan awarded him the Grand Cordon of the Order of the Rising Sun; he served on the board of governors of the Okinawa Institute of Science and Technology.
Jewish roots
Friedman’s story is a classic one of a child of Jewish immigrants in America. His parents left the Russian Empire in the great wave of Jewish emigration before the First World War, worked in sewing machines and garment factories, and poured everything into their sons’ education. The free and scholarship-funded education that carried him from a Chicago public high school to Fermi’s classroom was the same ladder that lifted so many children of Jewish immigrants into science.
He is not religious: he signed the Humanist Manifesto III in 2003, one of 22 Nobel laureates to do so, and has described himself as an atheist. The Jewish Virtual Library counts him among Jewish Nobel laureates in physics.
Painter, collector and legacy
Friedman never gave up the art he set aside for physics. He paints, studies Asian ceramics and enjoys theatre, music and ballet. He is married to Tania Letetsky-Baranovsky, whom he credits with broadening his horizons and with bearing his many absences at distant accelerators, and the family has four grown children. He has also shown a sense of humour about his fame, appearing in an episode of Da Ali G Show in which the comedian Sacha Baron Cohen interviewed him in character.
His legacy is a fact that every physics student now learns: the proton is not a fundamental particle but a busy bundle of quarks and gluons. Friedman has always stressed that the discovery was a group effort and thanked his students and colleagues by name. For a sewing-machine repairman’s son who nearly became a painter, it was a picture of nature drawn with electron beams.
Sources & further reading
Jerome I. Friedman, Biographical, NobelPrize.org · Press release: The Nobel Prize in Physics 1990, NobelPrize.org · Jerome Friedman, Jewish Virtual Library · Jerome Isaac Friedman, Wikipedia · Researched from the sources above and checked against them. Spotted an error? Tell us.
A life of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.