Profession: physicist

Physicist who received the Nobel Prize for his work confirming the structure of matter. The Curies were next-door neighbours and professional colleagues (though Perrin, younger and better-connected, was awarded a position they coveted). Einstein wrote complementing him on the precision of his observations of Brownian motion (which assisted in Einstein’s own work). Lévi-Strauss knew him right at the end of his life, in New York, where they helped set up an institution for exiled French academics.

Foucault was a schoolfriend; they both abandoned medical studies for physics. Fizeau studied with Arago and Regnault. He and Foucault worked together on the velocity of light following ideas suggested by Arago, whose eyesight was failing, but parted ways shortly before the crucial experiments (Fizeau got there first). They also took the first clear photo of the moon’s surface.

Einstein wrote to Perrin enthusiastically about Brownian motion. Curie was a good long-term friend and correspondent, Valéry met him several times, Bose and Schrödinger were important collaborators, Zweig (whom he admired) hosted him in Austria and co-signed a petition for arms limitation. Chaplin took Einstein (a fan) to the première of ‘City Lights’, Bohr and he held a long-running debate (they differed about randomness), Mann was a New Jersey neighbour, and Born (a great friend) played Beethoven duets with him. His conversation with Tagore was advertised as “two planets having a chat.”