On this day, 153 years ago, January 23, 1872 (December 14, 1871, the lunar calendar), the famous French physicist Langevin was born. Paul Langevin (1872 - 1946) was a French physicist. Born in Paris on January 23, 1872, he was admitted to the École des Hautes des Physics and Chemistry in Paris and the École Normale Supérieur d'École in 1888 and 1893. In 1909, he was appointed a professor at the École Français. In 1934, he was elected as an academician of the French Academy of Sciences. In 1930 and 1933, he was twice elected Chairman of the Solvay Physics Conference. In 1905, the theory of magnetism was proposed, and the concept of elementary magnets was used to give a classic explanation of the paramagnetism and diamagnetism of matter. In 1908, the fluctuation theory of Brownian motion was developed. During the First World War, in order to detect submarines, ultrasonic waves in the water were obtained using piezoelectric vibrations of quartz. He firmly opposed fascism and aggression. During the Second World War, he was arrested and imprisoned by the German occupying forces. After the September 18th Incident in China, he carried out various activities in support of China and criticized the League of Nations for its connivance of the Japanese invaders. Lang Zhiwan died in Paris on December 19, 1946.