Paul Langevin (1871-1946), Relativity and quantum theory

This article is a short biography of the French physicist Paul Langevin. P.Langevin epitomizes the whole physics of the first half of the last century. His formation made him both an experimenter and a theorist of a great value. His fields of interest were: ionized gas, electron physics, radiation physics and the electrodynamics of moving bodies. P.Langevin was one of the first to fully understand the implications of the relativity theory set up by A.Einstein and he became a fervent supporter of new ideas in physics, he discussed and analysed the interpretations of quantum physics since the very beginning of this new branch of physics. (A.C.)