Paul Langevin: His life and family

2022 marks the 150^th Anniversary of the birth of Paul Langevin, the originator of ultrasonics. He was born, lived, and died in Paris. His parents were of modest means. He was a humanist and a rationalist. Scientifically precocious, he was taught by Pierre Curie and spent a year at the Cavendish Laboratory, Cambridge. He gained a professorship at the ESPCI eventually becoming Director there. He also was Professor at the Collége de France, where his talent as a teacher gained wide recognition. He married Jeanne Desfosses in1898 and his children were as important to him as his science. They had two sons, Jean and André, both physicists, and two daughters Madeleine and Hélène. Paul-Gilbert, son of his scientific co-worker Eliane Montel, became a physicist and musicologist. In the interwar years he was an anti-Fascist activist. Imprisoned in 1940, he was then placed under house arrest in Troyes. After escaping to Switzerland in 1944, he returned to huge acclaim in liberated Paris. Elected as a Councilor for the Communist Party, he led the Committee for the Reorganization of Education in France, in spite of failing health. He died in 1946 and is interred in the Pantheon.