John von Neumann (December 28, 1903 - February 8, 1957) was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including mathematics (set theory, functional analysis, ergodic theory, geometry, numerical analysis, and many other mathematical fields), physics (quantum mechanics, hydrodynamics, and fluid dynamics), economics (game theory), computer science (linear programming), and statistics. He is generally regarded as one of the greatest mathematicians in modern history. Von Neumann was a pioneer of the application of operator theory to quantum mechanics, in the development of functional analysis. As principal member of the Manhattan Project his main contribution to the atomic bomb itself was in the concept and design of the explosive lenses needed to compress the plutonium core of the Trinity test device and the "Fat Man" weapon that was later dropped on Nagasaki. He was a key figure in the development of game theory and the concepts of cellular automata the universal constructor, and the digital computer. Von Neumann's mathematical analysis of the structure of self-replication preceded the discovery of the structure of DNA. In 1955, von Neumann was diagnosed with what was either bone or pancreatic cancer. He died in 1957 at the age of 57 while under military security lest he reveal military secrets while heavily medicated.