The most important scientist of the twentieth century, and its most important artist, went through their periods of greatest creativity almost simultaneously and in remarkably similar circumstances: Einstein\'s special theory of relativity and Picasso\'s Les Demoiselles d\'Avignon. It turns out they were both working on the same problem: the nature of space and time and, more particularly, simultaneity. When they produced these astonishing works, Einstein and Picasso were not the distinguished elderly figures that later became so familiar: they were in their twenties, unknown, feisty, dirt-poor, and prone to getting into trouble - their personal and creative beauty caused havoc.