John von Neumann, who was born in Budapest, Hungary, in 1903, was primarily a mathematician, and wrote numerous papers on both pure and applied math. He also made important contributions to a number of other fields of inquiry, including quantum physics, economics and computer science.

Von Neumann studied mathematics, physics and chemistry at German and Swiss universities for several years, finally receiving a Ph.D. in mathematics from the University of Budapest in 1926. He taught at Berlin and Hamburg from 1927 to 1930 and then emigrated to the United States to join the faculty at Princeton University. Three years later he took a position at the Institute of Advanced Studies at Princeton.

Until the outbreak of World War II, Von Neumann mostly did work in pure math, making important contributions to the fields of mathematical logic, set theory and operator theory. However, his work in operator theory had powerful applications in...