Paul Erdős

Paul Erdős owned almost nothing and knew almost everyone. Born in Budapest in 1913, he spent his adult life moving, case in hand, from one mathematician's home to another across four continents, arriving unannounced to announce 'My brain is open' and departing when the problem was solved or the host was exhausted. He produced somewhere near fifteen hundred mathematical papers—more than any mathematician in history with the possible exception of Euler—and he did it almost entirely through other people: over five hundred co-authors, a collaboration network so vast that mathematicians still measure their distance from him in Erdős numbers. He was, in the shape of his life, a distributed intelligence: capability that lived in the connections rather than in any one node. His signature mathematical contribution—the probabilistic method—established the existence of mathematical objects not by constructing them but by showing that a randomly chosen object would, with positive probability, have the desired property, making