Photo from the Nobel Foundation archive.
David J. Gross
The Nobel Prize in Physics 2004
Born: 19 February 1941, Washington, DC, USA
Affiliation at the time of the award: University of California, Kavli Institute for Theoretical Physics, Santa Barbara, CA, USA
Prize motivation: "for the discovery of asymptotic freedom in the theory of the strong interaction."
Prize share: 1/3
The atomic nucleus is held together by a powerful, strong interaction that binds together the protons and neutrons that comprise the nucleus. The strong interaction also holds together the quarks that make up protons and neutrons. This interaction is so strong that no free quarks have ever been observed. However, in 1973 David Gross, David Politzer, and Frank Wilczek came up with a theory postulating that when quarks come really close to one another, the attraction abates and they behave like free particles. This is called asymptotic freedom.