- Person
- Jerome Friedman
- Lived
- b. 1930
- Field
- Particle physics
- From
- American
The story
Jerome Friedman was born in Chicago in 1930 to Jewish immigrants from Russia; his father repaired and sold sewing machines and his mother had worked in a garment factory. A gifted painter, he turned down an art scholarship to study physics at the University of Chicago under Enrico Fermi, and joined the faculty of the Massachusetts Institute of Technology in 1960.
In the 1960s physicists had proposed that protons and neutrons might be built from smaller particles called quarks, but many thought quarks were only a mathematical convenience. No one had seen one. From 1967 Friedman and his MIT colleague Henry Kendall, working with Richard Taylor and others at the Stanford Linear Accelerator Center, used the new two-mile-long accelerator as a giant microscope. It shot electrons with energies of up to about 21 billion electron volts into targets of liquid hydrogen and deuterium, and two large magnetic spectrometers measured the angles and energies of the electrons that bounced off.
The experiment was widely regarded as routine. But in violent, so-called deep inelastic collisions, far more electrons were scattered at large angles than anyone expected from a soft, fuzzy proton. After careful checks, the team concluded that the electrons were striking small, hard centres inside the proton. Theorists James Bjorken and Richard Feynman interpreted them as quarks. The results also showed that protons and neutrons contain electrically neutral components, soon identified as gluons, the carriers of the strong force.
The Nobel committee compared the discovery to Ernest Rutherford’s discovery of the atomic nucleus by the large-angle scattering of alpha particles, repeated one level deeper. It noted that more than 99 per cent of the matter on Earth, including our own bodies, consists of quarks and the gluons that bind them. Friedman, Kendall and Taylor shared the 1990 Nobel Prize in Physics. Deep inelastic scattering, the technique the team pioneered, is still one of the main ways physicists study the inside of the proton.
Why it matters
The SLAC-MIT experiments gave the first direct evidence that quarks are real, a cornerstone of the Standard Model that physicists use to understand all ordinary matter and to design experiments such as those at the Large Hadron Collider.
About Jerome Friedman
Chicago-born son of Russian Jewish immigrants whose electron-scattering experiments at Stanford gave the first direct evidence that protons and neutrons are made of quarks. Nobel Prize 1990.
Sources
- Press release: The Nobel Prize in Physics 1990 NobelPrize.org
- Jerome I. Friedman, Biographical NobelPrize.org
- Jerome Friedman Jewish Virtual Library
Another act 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.