Gaileo Galilei’s father, Vincenzo Galilei (1520-1591), who described himself as a nobleman of Florence, was a professional musician. He carried out experiments on strings to support his musical theories. Galileo studied medicine at the university of Pisa, but his real interests were always in mathematics and natural philosophy. He is chiefly remembered for his work on free fall, his use of the telescope and his employment of experimentation.
After a spell teaching mathematics, first privately in Florence and then at the university of Pisa, in 1592 Galileo was appointed professor of mathematics at the niversity of Padua (the university of the Republic of Venice). There his duties were mainly to teach Euclids geometry in order to make use of astrology in their medical practice. However, Galileo apparently discussed more unconventional forms of astronomy and natural philosophy in a public lecture he gave in connection with the appearance of a New Star (now known as “Kepler’s supernova”) in 1604.
In a personal letter written to Kepler (1571 – 1630) in 1598, Galileo had stated that he was a Copernican (believer in the Theories of Copernicus). No public sign of this belief was to appear until many years later. In the summer of 1609, Galileo heard about a spyglass that a Dutchman had shown -1- in Venice. From these reports, and using his own technical skills as a mathematicians and a workman, Galileo made a series of telescopes whose optical performance was much better than that of the Dutch instrument.
The astronomical discoveries he made with his telescopes were described in a short book called Message from the Stars published in Venice in May 1610. It caused a sensation. Galileo claimed to have seen four small odies orbiting Jupiter. These last, with an eye on getting a job in Florence, he promptly named the “the Medicean stars. ” It worked, Soon afterwards, Galileo became “mathematician and Natural philosopher,” to the Grand Duke of Tuscany. In Florence he continued his work on mation and on mechanics, and began to get in disputes about Copernicanism..
In 1613 he discovered that when seen in a telescope that Venus that Venus showed phases like those of the moon, and therefore must orbit the Sun and not the Earth. This did not enable one person to ecided between Copernician system, in which everything goes around the sun, the Tychonic the one in which everything but the Earth and Moon goes around the sun which in turn goes around the Earth. Most astronomers of the time in fact favored the Tychonic System.
However Galileo showed a marked tendency to use all of his discoveries as evidence for Copernicanism, and to do with great verbal as well as mathematical skill. He seemed to make a lot of by making his opponents look like fools. Moreover not all of them were fools. -2- These eventually followed some expressions of interest by the Inquisition. Prima facie, Copernicanism was in contradiction with Scripture, and in 1616 Galileo was given some kind of secret, but official, warning that he was not to defend Copernicanism.
Just what was said on this occasion was to become a subject for dispute when Galileo was accused of departing from this undertaking in his Dialogue concerning the two greatest world systems, published in Florence in 1632. Galileo, who was not in the best of health, was summoned to Rome, found to be vehemently suspected of heresy, and eventually condemned to house arrest, for life, at his villa at Arcetri. He was also forbidden to ublish books. By the standards of the time he had got off rather lightly.
Galileo’s sight was failing, but he had devoted pupils, and he found it possible to write up his studies on motion and the strength of his evidence. The book Discourses on two new sciences, was smuggled out of Italy and published in Leiden in the Netherlands in 1638. Galileo wrote most of his later works in vernacular, probably to distance himself from the conventional learning of university teachers. However, his books were translated into Latin for the international market, and they proved to be immensely influential.