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Who Was Galileo?

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A controversial and intellectually courageous character, Galileo Galilei is recognized as the founder of modern 'scientific method', which he insisted should replace the Aristotelian philosophy prevalent during his time. He emphasized that the only valid test of hypotheses was extensive experimentation and not deductive philosophising.

Galileo's achievements remain outstanding in the history of science. He began studying medicine but soon applied himself to the realms of mathematics, physics and astronomy. His first notable observation, that a pendulum takes the same time to swing through its arc no matter how large or small this is (isochronism), led to the application of the pendulum in accurately measuring time.

Gravity fascinated Galileo. He discovered that all falling bodies descend with equal velocity regardless of their size. He also measured the specific gravity of solids using a hydrostatic balance by which density could be determined. His writings on motion led Sir Isaac Newton to formulate his first two laws of motion.

After finding out in 1609 that a ****telescope**** had been invented, Galileo soon built and improved his own telescopes with which he proceeded to make many controversial discoveries. These included the fact that the moon shone because of light reflected from the sun shining on the earth and that there were valleys and mountains on its surface, rather than it being a perfectly smooth, self-luminous sphere as was thought at the time.

He stated that the Milky Way was made up of countless stars, discovered four satellites orbiting Jupiter and found dark 'sun spots' on the surface of the sun which helped him discover that the sun itself was rotating. These findings reinforced Galileo's acceptance of Copernicus's theory that the sun was the centre of the solar system and that the earth rotated around it, which was completely contrary to the established theory of the time. Since the second century AD Ptolemy's earth-centred universe had been dogmatically accepted by all and especially by the Christian church.

Galileo's support of Copernicus's 'cosmological' theory brought him into serious >>>conflict with the church<<<. After agreeing to relinquish this 'heresy' when admonished by Pope Paul V, he went on to propound and defend it in his <i>Dialogue on the Two Chief Systems of the World</i> (1632). He was brought before the Inquisition at Rome in 1633 and forced to recant. His book was condemned and its sale banned.

Forced to move to Florence, Galileo was given support by the Medici family, famous for their patronage of Renaissance artists. He began to be troubled by failing sight and hearing (becoming totally blind in 1637) but continued with his investigations. He discovered that projectiles move in a parabolic path, stated that air had weight and unsuccessfully tried to measure it and discovered the annual and monthly librations of the moon when more of its surface can be seen from earth because of its changing relative position to earth (nine per cent more than the 50 per cent usually visible).

Galileo held two academic posts during his life, as Professor of Mathematics at the universities of Pisa and Padua, and he attracted students from all over Europe to his lectures.

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