**John von Neumann** was a Hungarian-born American mathematician who made major contributions to a vast range of fields including set theory, functional analysis, quantum mechanics, ergodic theory, continuous geometry, economics and game theory, computer science, numerical analysis, hydrodynamics , and statistics, as well as many other mathematical fields. He is generally regarded as one of the foremost mathematicians of the 20th century. Most notably, von Neumann was a pioneer of the application of operator theory to quantum mechanics, a member of the Manhattan Project and the Institute for Advanced Study in Princeton , and a key figure in the development of game theory and the concepts of cellular automata and the universal constructor. Along with Edward Teller and Stanislaw Ulam, von Neumann worked out key steps in the nuclear physics involved in thermonuclear reactions and the hydrogen bomb.