Pierre Biquard (born 30.08.1901) is a French physicist. He graduated from the School of Physics and Chemistry in Paris, where he worked and was a professor. His research concerned ultrasonics and the history of physics. In 1932, together with R. Lucas (independently of P. Debye), he detected the diffraction of light by ultrasound. He studied the absorption of ultrasound in liquids, and also in single crystals of silver and copper placed in a strong magnetic field at the temperature of liquid helium. He derived a formula for the coefficient of absorption of ultrasound by liquids.
He is the author of books on P. Langevin and F. Joliot-Curie. An active participant in the peace movement, he has been a member of the World Peace Council since 1956 and since 1976 vice-president of the World Federation of Scientific Workers (for a long time its general secretary).