One of the most important scientists of the story is Galileo Galilei. This mathematician, Italian physicist and astronomer lived between 1564 and 1642. He studied at the University of Pisa and was still very young invented the hydrostatic balance is used to verify the principle of Archimedes, enunciated the law of the oscillations of the pendulum and wrote a treatise on the specific weight of bodies. As a college professor in Pisa underwent a teaching method based on observation of phenomena. With this method, experimental science was born, based on the practical verification of each law stated. In 1609 he built a tool by which he could explore space: the telescope. The latter helped him to discover the satellites of Jupiter, sunspots, the rings of Saturn, the craters on the Moon and the accuracy of the heliocentric theory of Copernicus who said that the Sun was the center of the planetary system.
Galileo's theories are counterposed to the doctrine of the Church in 1616. The court ordered not to teach or defend their theories, which condemned.
Among his most important works are: The Mechanics, written between 1593 and 1599, Sidereus Nuncius, 1610, Address to the Most Serene Don Cosimo II, 1612, and Letter to G. Baliani, 1614.