Galileo Galilei
1564-1642
Italian Astronomer, Mathematician, and Physicist
Galileo Galilei, best known simply as Galileo, made fundamental discoveries in mechanics and observational astronomy as well as inventing the thermometer and improving the telescope. More significant, his emphasis on direct observation and mathematization of natural phenomena in conjunction with a refusal to allow science to be guided by metaphysical speculation had a transforming impact on scientific methodology.
Galileo was born on February 15, 1564, in Pisa, Italy. He enrolled at the University of Pisa to study medicine (1581), but his interests soon turned to mathematics. His first scientific discovery was made in 1582, when he realized a pendulum's period remains approximately the same regardless of the amplitude of oscillation. Galileo left Pisa in 1585 without finishing his degree. He continued his studies in Florence, where he completed his first scientific treatise, La bilancetta (1586), which describes his improved hydrostatic balance. As Professor of Mathematics at the University of Pisa (1589-92) he conducted experiments on falling bodies, which he published in De motu (1590). In 1592 Galileo assumed the chair of mathematics at the University of Padua.
In early 1609 Galileo heard reports of a device, invented in Holland the year before, consisting of two glass lenses that made objects at a distance appear closer. Based on this alone Galileo constructed his own telescope. His improvementsallowed him to produce a 30X instrument by year's end, and in early January 1610 he became one of the first, if not the first, to use the telescope to observe the heavens. Galileo announced his controversial discoveries in Sidereus nuncius (1610).
Galileo. (Archive Photos. Reproduced with permission.)Galileo's discovery of four satellites orbiting Jupiter contradicted the widely held belief that Earth was the center of rotation for all celestial bodies, and his observation of mountains and depressions on the lunar surface refuted the Aristotelian notion that the Moon was a perfect sphere. Galileo also resolved the Milky Way into a multitude of fixed stars. The existence of so many celestial objects invisible to the naked eye was difficult to understand if the universe had been created solely for man's benefit. Galileo later discovered the phases of Venus, which removed a serious objection to Nicolaus Copernicus's (1473-1543) heliocentrism—the idea that Earth revolves around the Sun—and independently discovered sunspots, which he realized provided evidence of solar axial rotation.
Rejecting a lifetime appointment at the University of Padua, Galileo returned to Florence in 1610 as mathematician and philosopher to the Grand Duke of Tuscany. Shortly thereafter a series of disputes with Dominican and Jesuit theologians over his support of Copernican heliocentrism brought him into conflict with the church. An edict was issued in 1616 declaring Copernicanism heretical, and Galileo was admonished not to defend Copernicanism in public. When Urban VIII became Pope in 1624, Galileo obtained permission to present an impartial discussion of the Copernican and Ptolemaic systems. The discussion, which appeared in Dialogue Concerning Two Chief World Systems (1632), was anything but impartial, marshaling as it did overwhelming empirical evidence in support of heliocentrism. Galileo was tried as a heretic, convicted, and sentenced to permanent house arrest.
Galileo's remaining years were spent preparing Two New Sciences (1638), which deals with the engineering science of strength of materials and kinematics. In the first the law of the lever is used to establish the breaking strength of materials. The second provides a mathematical treatment of motion in which Galileo introduces the idea of uniformly accelerated motion. He also established the law of free fall in a vacuum, deduced the terminal velocity for any body falling through air, and derived the parabolic trajectory of projectiles from uniform horizontal and accelerated vertical motions. Shortly after its publication Galileo went blind. He died four years later on January 8, 1642, at Arcetri, near Florence.
This is the complete article, containing 622 words
(approx. 2 pages at 300 words per page).
