| Wilhelm Blaschke | |
| Birth Date: | 13 September 1885 |
| Birth Place: | Graz |
| Death Place: | Hamburg |
| Nationality: | Austrian |
| Fields: | Mathematics |
| Workplaces: | University of Hamburg |
| Alma Mater: | University of Vienna |
| Doctoral Advisor: | Wilhelm Wirtinger |
| Doctoral Students: | Shiing-Shen Chern Luis Santaló Emanuel Sperner Gerhard Thomsen |
| Notable Students: | Alberto Dou Mas de Xaxàs |
| Known For: | Blaschke product Blaschke selection theorem Blaschke–Santaló inequality |
Wilhelm Johann Eugen Blaschke (13 September 1885 – 17 March 1962) was an Austrian mathematician working in the fields of differential and integral geometry.
Blaschke was the son of mathematician Josef Blaschke, who taught geometry at the Landes Oberrealschule in Graz.After studying for two years at the Technische Hochschule in Graz, he went to the University of Vienna, and completed a doctorate in 1908 under the supervision of Wilhelm Wirtinger. His dissertation was Über eine besondere Art von Kurven vierter Klasse.
After completing his doctorate he spent several years visiting mathematicians at the major universities in Italy and Germany. He spent two years each in positions in Prague, Leipzig, Göttingen, and Tübingen until, in 1919, he took the professorship at the University of Hamburg that he would keep for the rest of his career. His students at Hamburg included Shiing-Shen Chern, Luis Santaló, and Emanuel Sperner.
In 1933 Blaschke signed the Vow of allegiance of the Professors of the German Universities and High-Schools to Adolf Hitler and the National Socialistic State.[1] However, he defended Kurt Reidemeister against the Nazis and, in the early 1930s, campaigned against Ludwig Bieberbach for leadership of the German Mathematical Society, arguing that the society should remain international and apolitical in opposition to Bieberbach's wish to "enforce Nazi policies on German mathematics and race". However, by 1936 he was supporting Nazi policies, called himself "a Nazi at Heart", and was described by colleagues as "Mussolinetto" for his fascist beliefs. He officially joined the Nazi Party in 1937.[2]
After the war, Blaschke was removed from his position at the University of Hamburg for his Nazi affiliation, but after an appeal his professorship was restored in 1946. He remained at the university until his retirement in 1953.
In 1916 Blaschke published one of the first books devoted to convex sets: Circle and Sphere (Kreis und Kugel). Drawing on dozens of sources, Blaschke made a thorough review of the subject with citations within the text to attribute credit in a classical area of mathematics.
Blaschke's name has been lent as an eponym to a number of mathematical theorems and concepts:
"The only Wiedersehen manifolds in any dimension are the standard Euclidean spheres."