Template:On This Day (nonfiction)/February 23
1583: Mathematician, astrologer, and astronomer Jean-Baptiste Morin born. Morin will champion the geocentric worldview, opposing Galileo and his ideas; Morin will also oppose Descartes' ideas after meeting the philosopher in 1638.
1855: Mathematician, astronomer, and physicist Carl Friedrich Gauss dies. He had an exceptional influence in many fields of mathematics and science and is ranked as one of history's most influential mathematicians.
1898: Émile Zola is imprisoned in France after writing "J'accuse", a letter accusing the French government of antisemitism and wrongfully imprisoning Captain Alfred Dreyfus.
1927: German theoretical physicist Werner Heisenberg writes a letter to fellow physicist Wolfgang Pauli, in which he describes his uncertainty principle for the first time.
1941: Plutonium is first produced and isolated by Dr. Glenn T. Seaborg.
1974: German diplomat and intelligence officer Hans Bernd Gisevius dies. Gisevius was a covert opponent of the Nazi regime, and a radical communist; he served as a liaison in Zürich between Allen Dulles, station chief for the American OSS, and the German Resistance forces in Germany.