Alfred Bucherer

Alfred Heinrich Bucherer (1863 to 1927) was a German physicist, born in Cologne and died in Bonn, who is known for his experiments on relativistic mass. He studied at the University of Hannover, Johns Hopkins University, the University of Strassburg, the University of Leipzig and the University of Bonn, habilitated at Bonn in 1899 and taught there until 1923. In 1903 he published the first German-language book to be completely based on vector calculus. In 1904 he developed a theory of electrons in which the electrons contract in the line of motion and expand perpendicular to it, a model very similar to one developed independently by Paul Langevin. His 1908 experiments seemed to confirm the Lorentz-Einstein theory, although it was shown in 1938 that such experiments were too imprecise to distinguish between the competing models. He was also the first to use the expression theory of relativity for Einstein's theory.