Cardano, Girolamo

(1501-1576)

   Italian physician, mathematician, and natural philosopher. Born in Pavia and educated there and at Padua, he supported himself during his student years as a gambler. One of his later writings, Liber de ludo aleae / Book on Games of Dice, presented a sophisticated discussion of the mathematics of probability, though it had little influence since it was not published until the following century. After graduation, he practiced medicine near Padua and in 1534 moved to Milan, first as a teacher of mathematics and later as a medical practitioner. From 1543 to 1560 he was professor of medicine at the University of Pavia. Cardano's interests extended to many branches of natural philosophy, including mechanics, geology, and hydrodynamics. He realized that the trajectory of a projectile is a parabola; he noted that the presence of marine fossils on dry land proves that mountainous regions had once been ocean floor; he suggested that the earth's water is constantly recirculated from rain to rivers to oceans to clouds and back to rain.

   Cardano was especially gifted as a mathematician. His first mathematical publication, Practica arithmeticae / Arithmetical Practice (1539), showed great skill in manipulating equations. He was one of a number of contemporaries who studied quadratic equations, and his book Ars magna / The Great Art (1545) summarized his own work and that of several others on that topic, though it also involved him in a bitter controversy with Niccolo Tartaglia even though he gave Tartaglia full credit for his pioneering contributions. In 1560 Cardano moved from Pavia to Bologna. There he was imprisoned in 1570 by the Roman Inquisition on suspicion of heresy, but he was released and spent his final years at Rome, supported by a papal pension.