G Galileo Galilei (1564–1642) astronomer, mathematician, and physicist Galileo Galilei was the most important physical scientist of his time His father, Vincenzo Galilei, performed significant experiments in musical science After entering the University of Pisa in 1581 as a medical student, Galileo discovered mathematics and promptly became enraptured The ancient Greek mathematician Archimedes became his intellectual hero He supplemented classes in natural philosophy at Pisa with private mathematical study in Florence He left Pisa without a degree in 1585 and became a mathematics tutor in Florence, where he established the isochronous nature of the pendulum—the fact that the frequency of a pendulum is a constant In 1589, his Archimedes-inspired work won him the mathematics chair at Pisa In 1592, Galileo became professor of mathematics at the University of Padua, Europe’s leading scientific university Whatever the personal and financial stresses of the Padua years, they were Galileo’s most intellectually fruitful time He moved from a highly mathematical approach to knowledge to a greater interest in experiment He began to elaborate a non-Aristotelian approach to the problems of moving bodies His most famous result was the discovery that the distance covered by a falling body varies with the square of the time of the fall—the “law of falling bodies.” Galileo’s work with the telescope in the early 17th century catapulted him to European fame From what information he could gather, he designed his own, superior to the contemporary Dutch telescopes, in 1609 He observed the previously unknown moons of Jupiter These were the first satellites of a planet (other than the Moon) ever known The fact that the system of the planets could have more than one center helped support the Copernican theory Galileo’s other discoveries included the mountains of the Moon, the phases of Venus, and the composition of the Milky Way out of innumerable stars Galileo wanted to move to Tuscany in Florence The naming of Jupiter’s moons the “Medicean stars” after the ruling Medici family of Tuscany was a brilliant stroke to win the duke’s favor, securing Galileo’s appointment as court mathematician Galileo insisted that he be given the title not merely of mathematician, but philosopher as well Since the actual physical nature of the universe was the province of natural philosophers, Galileo as a philosopher could make cosmological claims that he could not make as a mere mathematician It was from Rome that Galileo faced what would prove to be the greatest challenge of his career, that of the church’s condemnation of Copernicanism Church authorities were increasingly opposed to Copernican ism and Galileo as its principal Catholic champion Copernicus’s On the Revolution of the Celestial Spheres was placed on the church’s Index of Forbidden Books in 1616 Galileo argued that Copernicanism had no relevance to theology, but church authorities did not accept this position Galileo’s works were still not specifically condemned 143