9781422277614

problems in physics. They were to become his heroes, and were the only ancient thinkers for whom he later felt any respect. As his father had feared, Galileo left the University of Pisa in 1585 without a medical degree and without a job. He taught mathematics privately to anyone willing to pay. Eventually, the Marquis Guidobaldo del Monte, himself a great

writer on mechanics, used his influence on Galileo’s behalf. In 1589, at the age of twenty- five, Galileo started his scientific career as Professor of Mathematics at his former university. At Pisa, Galileo showed a fascination with the laws of motion. An unpublished book by him about motion still survives in manuscript form. Two well-known stories date from his time there. During the church services one evening, Galileo is said to have watched the movement of a chandelier in the cathedral. He began to time the swings by his pulse. He noticed that the chandelier always took exactly the same time to swing from one side that it took to swing to the other. Another story that Galileo’s assistant told many years later was about his experiment of dropping two weights from

Statue of the Greek mathematician Archimedes (ca. 287–212 bce ). He is most remembered for his discovery of the “Archimedes Principle” of bodies in water, and for his machines of war.

15