Richard Edler von Mises (April 19, 1883 - July 14, 1953) was a scientist and mathematician who worked on solid mechanics, fluid mechanics, aerodynamics, aeronautics, statistics and probability theory. He held the position of Gordon-McKay Professor of Aerodynamics and Applied Mathematics at Harvard University. He described his work in his own words shortly before his death as being on, "... practical analysis, integral and differential equations, mechanics, hydrodynamics and aerodynamics, constructive geometry, probability calculus, statistics and philosophy." In aerodynamics, he made notable advances in boundary-layer-flow theory and airfoil design. He developed the Distortion energy theory of stress, which is one of the most important concepts used by engineers in material strength calculations. In solid mechanics, he made an important contribution to the theory of plasticity by formulating what has become known as the Von Mises yield criterion. In probability theory, he was the person who originally proposed the now famous "birthday problem" (in a set of n randomly chosen people, some pair of them will have the same birthday). He also defined the impossibility of a gambling system. He died in 1953 at the age of 70.