Physicist — Jean Baptiste Perrin (Lille 1870 – New York 1942) was a French physicist, Nobel Prize in Physics in 1926. Trained at the École normale supérieure, he taught at the Sorbonne in Paris. He is celebrated for having provided the definitive experimental proof of the existence of atoms and molecules, by studying the Brownian motion of suspended particles. By quantitatively verifying Einstein’s theoretical predictions on Brownian motion, he succeeded in accurately determining Avogadro’s number, putting an end to the doubts still widespread about atomic reality. A committed anti-fascist, he left occupied France and died in exile in the United States.
Trivia
His measurements of Brownian motion convinced even the last sceptics, such as Wilhelm Ostwald, to finally accept the real existence of atoms.
Theories and contributions
- Study of Brownian motion — Verified Einstein’s relation for the mean square displacement of particles: .
- Determination of Avogadro’s number — From his experiments he derived an accurate value of , proving the reality of atoms.
Featured in chapters
Linked atoms
3 linked atoms.
09 Teoria cinetica dei gas
- History: from the philosophical atom to the physical atom
- Atoms: from philosophical hypothesis to experimental evidence