Jon von Neumann

John [Johann, Jancsi, János] Louis von Neumann (Born December 28, 1903 in Budapest, Hungary; Died February 8, 1957 in Washington D.C.) was a highly influential mathematician whose work on quantum mechanics (published in 1932 as Mathematische Grundlagen der Quantenmechanik) dashed all hope of developing a deterministic quantum mechanics until his work was overturned by David Bohm, J.S. Bell, and others. He held a strong belief in the role of the observer in creating the collapse of the quantum wave[?] function.