A reclusive Russian won the math world's highest honor Tuesday for solving a problem that has stumped some of the discipline's greatest minds for a century — but he refused the award.

Grigory Perelman, a 40-year-old native of St. Petersburg, won a Fields Medal — often described as math's equivalent of the Nobel prize — for a breakthrough in the study of shapes that experts say might help scientists figure out the shape of the universe.

John Ball, president of the International Mathematical Union, said that he had urged Perelman to accept the medal but Perelman said he felt isolated from the mathematics community and "does not want to be seen as its figurehead." Ball offered no further details of the conversation.

Besides shunning the award for his work in topology, Perelman also seems uninterested, according to colleagues, in a separate $1 million prize he could win for proving the Poincare conjecture, a theorem about the nature of multidimensional space.