This year's Crafoord Prize, a sort of alternative Nobel, has been awarded to a mathematician and two physicists whose work ranges from the mathematics of string theory to the details of how black holes suck in matter. The mathematical half is shared by Maxim Kontsevich of the Institut des Hautes Études Scientifiques (IHÉS) in France and Edward Witten of the Institute for Advanced Study in Princeton, New Jersey, for contributions inspired by modern theoretical physics. The astronomical half goes to Rashid Alievich Sunyaev of the Space Research Institute and the Max Planck Institute for Astrophysics in Garching, Germany, for his work on black holes and neutron stars and on the structure of the cosmic background radiation.

"They're very worthy recipients," says Michael Rowan-Robinson, president of the Royal Astronomical Society in London. "Sunyaev is extremely influential in his field. A great figure." Cosmologist Martin Rees, Britain's Astronomer Royal and president of the Royal Society in London, describes the award as "excellent" and says Witten is "the greatest theoretical physicist in the world."

The Crafoord Prize, first awarded in 1982, was instituted by Anna-Greta and Holger Crafoord and honors fields that are not covered by the Nobels, including astronomy, mathematics, geosciences, and biosciences. The Royal Swedish Academy of Sciences administers the award and presents it to a different field each year.

Witten is a leading figure in the development of string theory, an effort to unify the four fundamental forces of nature. The theory holds that the particles we see are manifestations of "strings," objects that exist in many more dimensions than the three we are familiar with. To carry out calculations in the many dimensions required by string theory is very difficult, but Witten devised new mathematical techniques that made previously impossible calculations possible. Kontsevich went on to show that such techniques inspired by physics function more widely in mathematics and give correct results.

Witten says he was "totally startled" to find that his achievements in mathematics had won attention rather than his physics. "I'm extremely honored that my work was recognized in this way," he says. Kontsevich says there has been "very fruitful interaction between maths and physics that has changed our subject over the past 15 years." Considering the list of past mathematicians who have won the Crafoord Prize, Kontsevich says, "it's a great honor to be among them."

Rees says Sunyaev has been "very influential for a long time." He won recognition today for two pieces of work: The first describes how matter falling into a black hole or a neutron star coalesces into a thin disc and emits radiation. This is how we know the location of black holes, even though they are not visible themselves. His other achievement was discovering clues in the structure of the cosmic microwave background radiation--the afterglow of the big bang--that tell us about events in the early universe. Sunyaev, who turns 65 this year, is still active in both areas.

Sunyaev will receive half of the $500,000 prize, and Kontsevich and Witten will share the other half.

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