U.S. scientists David Gross, David Politzer and Frank Wilczak have won the 2004 Nobel Prize in Physics for their work on quarks. The three researchers will share the $1.3 million that accompany the award.
Quarks are the smallest building blocks of nature. And the three U.S. scientists were cited by the Royal Swedish Academy of Sciences, which announced the award in Stockholm, for what it called an important theoretical discovery in the field.
It relates to how the so-called "strong force" that is dominant inside the nucleus of an atom acts between the quarks inside the proton and the neutron.
The academy says the discovery by the trio more than 30 years ago has brought science closer to its dream of formulating a unified description of all forces of nature, what the citation calls "a theory for everything".
The academy says that what the three scientists discovered was something that, at first sight, seemed contradictory. They found that the closer the quarks are to each other, the weaker was the force tying them together. Conversely, when the distance between the quarks increases, the force becomes stronger.
The jury, in announcing the award, says the relevance of the discovery for daily life can appear hard to grasp. But, using the example of a coin spinning on a table, it says 80 percent of the coin's weight is due to the interaction between quarks.
Mr. Gross works at the University of California in Santa Barbara, Mr. Politzer at the California Institute of Technology, and Mr. Wilczek at the Massachusetts Institute of Technology.
On Monday, two other Americans, Richard Axel and Linda Buck, won the Nobel Prize in medicine for their pioneering work on mammals' sense of smell.