Grigori Perelman solved an unsolvable problem and walked away
In 2010, the Clay Mathematics Institute offered him a million dollars for solving the Poincaré conjecture. He said no.
The Poincaré conjecture is a problem in topology — the mathematics of shape — that Henri Poincaré posed in 1904. It resisted every attempt at proof for nearly a century. In November 2002, a Russian mathematician named Grigori Perelman quietly posted three papers to an online preprint server. They solved it.
The mathematics community took two years to verify the proof. In 2006, Perelman was awarded the Fields Medal, the highest prize in mathematics. He was the first person in history to refuse it.
When the Clay Mathematics Institute followed in 2010 with its million-dollar Millennium Prize, Perelman declined that too. His stated reason was precise: he felt that the American mathematician Richard Hamilton, whose earlier work on Ricci flow had made the proof possible, deserved equal recognition. Since Hamilton was not being honored, Perelman did not want to be honored alone.
By then he had already resigned from the Steklov Mathematics Institute in St. Petersburg, reportedly telling colleagues he was disappointed in mathematics. He moved back in with his mother.
Mikhael Gromov, one of the great geometers of the twentieth century, said of Perelman: he holds moral principles and acts on them. What makes this remarkable, Gromov added, is how surprising people found it — as though honesty in a scientist were the aberration.