Physics: 1926

Perrin, Jean Baptiste, pronounced puh RAN, zhahn bah TEEST (1870-1942), a French physicist, was awarded the 1926 Nobel Prize for physics for studying the discontinuous structure of matter and for measuring the sizes of atoms.

In 1895, Perrin carried out an experiment that demonstrated that cathode rays consist of negatively charged particles. These particles are now known as electrons. Perrin then turned to the study of Brownian motion, a constant, random irregular motion often observed in very minute particles suspended in a liquid or gas, caused by the impact of the surrounding molecules. He devised an experiment that made it possible for the first time to measure the size of atoms.

Perrin published this work in Les Atomes (Atoms, 1913), which had sold 30,000 copies by 1936. His scientific papers include Rayons cathodiques et rayons X (Cathode rays and X rays, 1897) and Matiere et lumiere (Matter and Light, 1919). Perrin established the National Centre for Scientific Research; the Palace of Discovery, which was part of the 1937 International Exhibition in Paris; and the Astrophysics Institute.

Jean Baptiste Perrin was born in Lille, France, and received his degree from the Ecole Normal Superieure, Paris, in 1897. In 1910, Perrin became a professor at the Sorbonne, University of Paris. He served as an officer in the Engineer Corps of the French Army in World War I (1914-1918). In 1940, Perrin fled to the United States when Germany invaded France during World War II.