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.