Quarky theory wins Nobel Prize

The 2004 Nobel Prize for physics has been awarded to three American scientists, David Gross, David Politzer and Frank Wilczek, for their explanation of the strong force, or how quarks combine to form protons and neutrons.

The Nobel Jury said: "The discovery which is awarded this year's Nobel Prize is of decisive importance for our understanding of how the theory of one of nature's fundamental forces works, the force that ties together the smallest pieces of matter - the quarks."

The existence of quarks was first proposed in 1964. These fundamental particles are bound together so tightly that they are never seen in isolation, yet experiments on the Stanford Linear Accelerator (SLAC) indicate that within a proton, the particles are hardly bound together at all.

In 1973 Politzer was a graduate student at Harvard, and Frank Wilczek was David Gross's graduate student at Princeton. Working separately, both groups theorised that quarks actually become bound more tightly the farther they get from each other, an idea that became known as asymptotic freedom.

The analogy most used to explain this bizarre sounding behaviour is that of an elastic band: there is no energy in it until you stretch it, and the more you stretch it, the more it resists.

John Preskill, Caltech's MacArthur Professor of theoretical physics and a colleague of Politzer, said that their discovery "provided a highly satisfying resolution of this puzzle".

The discovery established quantum chromodynamics (QCD) as the accepted theory of the strong force, one of the four fundamental forces of nature. Because of its similarity to quantum electrodynamics, and the theory of the nuclear weak force, QCD hinted that there might be a common explanation underlying all three forces.

"Thanks to their discovery, David Gross, David Politzer and Frank Wilczek have brought physics one step closer to fulfilling a grand dream, to formulate a unified theory comprising gravity as well - a theory for everything," the Nobel committee said.

The three Physicists each get a medal and share a $1.3m prize. ®

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