Professor David Hilbert, c mid-20th century

David Hilbert, born 23rd January 1862, died 14th February 1943. Hilbert was a German mathematician and philosopher of mathematics, and considered one of the greatest mathematicians of his period. He discovered a number of fundamental ideas within mathematics such as invariant theory, foundations of geometry, and proof theory and mathematical logic. He studied at the University of Königsberg, where he met Hermann Minkowski, who he formed a lifelong friendship with. He achieved his PhD in 1885, after which he worked at Königsberg for another 10 years, before moving to work at the University of Göttingen for the rest of his life. He married Käthe Jerosch (1864–1945) in 1892. They had one child, a son Franz Hilbert (1893-1969). He was elected to the American Philosophical Society in 1932. During the 1930s, the Nazis greatly affected the University of Göttingen by expelling all Jewish members of faculty and restaffing them, greatly impacting the university's Mathematics department. He died in 1943, aged 81.