In November 2002, a Russian mathematician named Grigori Perelman posted the first of three short preprints to the arXiv (an online repository for drafts of academic papers in math and science), offering a proof for the famous Poincare conjecture—one of the toughest remaining unsolved problems in mathematics, although partial solutions had been made over the decades since it was first proposed in 1904. Apparently he’d stumbled on his insight while working on something else; the short paper seemed almost like an afterthought, despite its world-shaking contents. Rumor had it that Perelman did not even plan to publish a formal paper.