Profession: physicist

Bohr studied with Thomson in Cambridge, but they didn’t get on well, so he went to work with Rutherford in Manchester: they stayed friends for life. Valéry counted Bohr among his many scientist friends. Heisenberg was his student, but their strong long-lasting friendship deteriorated during WWII in circumstances never fully explained. Dirac (for whom Bohr was a father-figure) and Pauli were among his other protégés. Feynman was unawed by him, pointing out when he thought he was wrong. Ehrenfurt shared in Bohr’s famous dialogue about quantum physics with Einstein, when Einstein declared that God did not play dice.

Fizeau and Foucault were schoolfriends, both abandoning medical studies for physics. Donné had been his professor at medical school; together they produced a book on microscopic anatomy that pioneered the use of photography in printed publications. He worked together with Regnault on binocular vision, and met Thomson in Regnault’s laboratory. Arago, whose eyesight was failing, suggested the work Foucault and Fizeau did on the velocity of light; the two also produced the first photo of the sun’s surface. Thomson was working in Regnault’s laboratory when Foucault met him.

Maurice de Broglie was his brother and occasional collaborator. Langevin was a colleague, Bose worked with him when he first came to Europe, and Le Lionnais and he jointly founded an Association of Writers on Science. Among his correspondents were Valéry (a personal friend) and Einstein (who had great respect for him). He threatened to sue Freymann for withholding publication of a book, but Freymann died and the book got published.

Silliman published Henry’s research into electromagnetism and was responsible for his appointment to the Princeton faculty, despite his lack of formal education. Alexander was his brother-in-law. He met Faraday, Babbage, Wheatstone, Becquerel, Biot, Arago, de la Rive and Gay-Lussac on a visit to Europe. Baird worked with him at the nascent Smithsonian Institution, and followed him as director, though they differed on policy matters. Morse wrote to him on Gale’s suggestion, seeking advice and public endorsement; Henry obliged generously. Gray and Henry corresponded copiously; Torrey was another correspondent.