Hermann Minkowski (1864-1909), Polish-German mathematician and relativity theorist. Minkowski was appointed professor at the universities of Konigsberg (1895), Zurich (1896) and Gottingen (1902). He taught Albert Einstein at Zurich. Minkowski's most important work was a mathematical description of spacetime, originally published in 1907. Spacetime uses four dimensions, the three space dimensions and a time dimension. Minkowski's spacetime was used by Einstein in his theory of special relativity. Minkowski also discovered a new branch of number theory, the geometry of numbers.