- Person
- H. David Politzer
- Lived
- b. 1949
- Field
- Theoretical physics
- From
- American
The story
H. David Politzer was born in New York City in 1949; his parents had escaped Czechoslovakia in 1939 and came to the United States after the Second World War. He attended the Bronx High School of Science and the University of Michigan, and in the early 1970s was a graduate student at Harvard under Sidney Coleman.
Experiments at the Stanford Linear Accelerator Center had shown that protons contain quarks, and that when struck very hard, the quarks behave almost as if they were free. Yet no one had ever knocked a single quark loose. No known theory explained a force that was weak at close range and unbreakable at a distance. In theories like quantum electrodynamics, forces get stronger at shorter distances, and some physicists had presented evidence that every realistic theory must behave that way.
Politzer calculated how the strength of the force changes with distance in a class of theories, called non-Abelian gauge theories, in which the particles that carry the force themselves carry charge. He found that in such theories the force can weaken as particles come closer. His paper appeared in Physical Review Letters in June 1973, back to back with one by David Gross and his graduate student Frank Wilczek at Princeton, who had reached the same result independently. The property is called asymptotic freedom. The Nobel committee compared the force to a rubber band, slack when quarks are close and pulling harder as they move apart.
Asymptotic freedom made quantum chromodynamics, QCD, the theory of quarks and the gluons that bind them, into a working theory that could be calculated at high energies. With Thomas Appelquist, Politzer used it to predict charmonium, particles made of a charm quark and its antiquark, discovered in 1974. QCD became one of the pillars of the Standard Model and has been tested in great detail at CERN. Gross, Politzer and Wilczek shared the 2004 Nobel Prize in Physics.
Why it matters
QCD, made possible by asymptotic freedom, is the theory physicists use to understand the force that holds every atomic nucleus together and to predict what happens in collisions at accelerators such as the Large Hadron Collider.
About H. David Politzer
Caltech theorist who, as a 23-year-old graduate student, discovered asymptotic freedom, the property of the strong force that made quantum chromodynamics, the theory of quarks, work. Nobel 2004.
Sources
- Press release: The Nobel Prize in Physics 2004 NobelPrize.org
- Popular information: The Nobel Prize in Physics 2004 NobelPrize.org
- Hugh David Politzer Wikipedia
- H. David Politzer 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.