What is Paul Langevin?
[[File:Paul Langevin Wellcome2.jpg|thumb|Paul Langevin]] '''Paul Langevin''' (23 January 1872 – 19 December 1946) was a French physicist who was active at the beginning of the 20th century. He invented [[sonar]] and worked with [[Albert Einstein]]. {{bio-stub}} {{DEFAULTSORT:Langevin, Paul}} [[Category:1872 births]] [[Category:1946 deaths]] [[Category:French physicists]] [[Category:French inventors]]