The Abel Prize, often described as a Nobel Prize for maths, has been awarded to two mathematicians for unifying swathes of mathematical theories that were once thought to be unrelated.

Sir Michael Atiyah and Isadore Singer worked together to create something called index theory, which helps to bring together branches of maths from topology to geometry. Their work can be described as a tool that helps scientists work out how many solutions there are to problems they are trying to unpick - such as how heat flows, or how an object moves.

"It is basically a formula that counts the number of solutions to another equation," says Atiyah.

"This theory is now a cornerstone of maths; it is one of the most fundamental results of the last 50 years," says Elmer Rees, a colleague of Atiyah's at Edinburgh University.

"It was as if an archaeologist had discovered exactly the same patterns on tombs in completely different parts of the world, proving that some underlying civilization had carved them all," says Marcus du Sautoy, a mathematician at Oxford University.

Atiyah and Singer devised index theory in the early 1960s, while Atiyah was based at Oxford University and Singer was at the Massachusetts Institute of Technology, Cambridge, where he still works.

Their theory also underpins the latest work on string theory, which tries to explain the fundamental nature of the universe by suggesting that matter is made of tiny 'strings' vibrating in many different dimensions.

## Abel reward

The Norwegian Academy of Science and Letters established the Abel Prize in 2002, to commemorate the nineteenth century mathematician Niels Henrik Abel. There is no Nobel Prize for mathematics; awards such as the Abel and the Fields Medal help to fill the gap. King Harald of Norway will present the £475,000 prize at a ceremony in Oslo on 25 May.

Atiyah is a former president of the Royal Society, and more recently helped to establish the Millennium Prize, also known as the Clay Prize, which offers a US$1 million reward for solutions to any of the seven most vexing problems in mathematics. He spends much of his time publicizing maths through radio broadcasts and public lectures.

Singer is a former member of the White House Science Council, and was vice-president of the American Mathematical Society in the 1970s.