Research of Galieo.

Galileo Galilei, a pioneer of modern physics and telescopic astronomy, was born near Pisa, Italy, on Feb. 15, 1564. In 1581 he entered the University of Pisa as a medical student, but he soon became interested in mathematics and left without a degree in 1585. After teaching privately at Florence, he was made professor of mathematics at Pisa in 1589. There he is said to have demonstrated from the Leaning Tower that Aristotelian physics was wrong in assuming that speed of fall was proportional to weight. He also wrote a treatise on motion, emphasizing mathematical arguments. In 1592, Galileo became professor of mathematics at the University of Padua, where he remained until 1610. He devised a calculating device now called the sector, worked out a mechanical explanation of the tides based on the Copernican motions of the Earth (see Copernicus, Nicolaus), and wrote a treatise on mechanics showing that machines do not create power but merely transform it.

In 1602, Galileo resumed his investigations of motion along inclined planes and began to study the motion of pendulums. By 1604 he had formulated the basic law of falling bodies, which he verified by careful measurements.

Late in 1604 a supernova appeared, and Galileo became involved in a dispute with philosophers who held (with Aristotle) that change could not occur in the heavens. Applying the mathematics of parallax, Galileo found the star to be very distant, in the supposedly unchangeable regions of the cosmos, and he attacked Aristotelian qualitative principles in science. Returning to his studies of motion, he established quantitatively a restricted inertial principle and determined that projectiles move in parabolic paths. In 1609 he was writing a mathematical treatise on motion when news arrived of the newly invented Dutch telescope. He was so excited by its possible scientific applications that he put other work aside and began to construct his own telescopes.

Drake, Stillman. "Galileo Galilei." Grolier Multimedia Encyclopedia. Grolier Online, 2014. Web. 10 Nov. 2014.