David Hilbert

David Hilbert (1862-1943) was a German mathematician who attempted to formalize mathematics in a methodical manner. He is most famous for listing the 23 greatest unsolved problems of mathematics in 1900, problems that included the Riemann hypothesis, the continuum hypothesis, Goldbach's conjecture, the well ordering of the reals, the transcendence of powers of algebraic numbers and the extension of Dirichlet's principle, in addition to his analogy for Cantorian infinite sets, known as 'Hilbert's Hotel'.

Later, after Hilbert did work in algebraic number theory and geometry, and created the "Hilbert space," he helped create the general theory of relativity by first publishing a derivation of the field equations. In 1934 and 1939 he published two works attempting to develop a "proof theory," which is a direct check for the consistency of mathematics. But in 1931 Kurt Godel had already proved that this goal was impossible.