Galileo: Difference between revisions
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'''Galileo Galilei''' (1564-1642), was an [[Italy|Italian]] physicist and [[astronomy|astronomer]], most noted for his work on astronomy and falling bodies. |
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Galileo Galilei (1564-1642), [[Italy|Italian]] physicist and [[astronomy|astronomer]], who, with the [[Germany|German]] astronomer Johannes [[Kepler]], initiated the [[sceince|scientific]] revolution that flowered in the work of the [[England|English]] physicist Sir Isaac Newton. Born Galileo Galilei, his main contributions were, in astronomy, the use of the telescope in observation and the discovery of sunspots, lunar mountains and valleys, the four largest satellites of [[Jupiter]], and the phases of [[Venus]]. In physics, he discovered the laws of falling bodies and the motions of [[projectile weapons|projectiles]]. In the history of culture, Galileo stands as a symbol of the battle against authority for freedom of inquiry. |
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Galileo showed that objects accelarated to the ground independent of their weight by rolling balls of different mass down inclined surfaces. According to the biography of Galileo's pupil Vincenzo Viviani his final proof of this theory involved dropping balls from the Leaning Tower of Pisa, although this is now generally accepted as being untrue, not least because wind resistance would have caused such an experiment to fail. |
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Galileo was born near [[Pisa]], on February 15, 1564. His father, Vincenzo Galilei, played an important role in the [[music]]al revolution from medieval polyphony to harmonic modulation. Just as Vincenzo saw that rigid theory stifled new forms in music, so his eldest son came to see [[Aristotle|Aristotelian]] physical [[theology]] as limiting scientific inquiry. Galileo was taught by [[monk]]s at Vallombrosa and then entered the [[University]] of Pisa in 1581 to study [[medicine]]. He soon turned to [[philosophy]] and [[mathematics]], leaving the university without a degree in 1585. For a time he tutored privately and wrote on hydrostatics and natural motions, but he did not publish. In 1589 he became professor of mathematics at Pisa, where he is reported to have shown his students the error of Aristotle’s belief that speed of fall is proportional to weight, by dropping two objects of different weight simultaneously from the Leaning Tower. His contract was not renewed in 1592, probably because he contradicted Aristotelian professors. The same year, he was appointed to the chair of mathematics at the University of [[Padua]], where he remained until 1610. |
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Galileo's strong support of the Copernican model of the Universe led him into trouble with the Papacy, and he spent the final years of his life under house arrest. |
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At Padua, Galileo invented a calculating “compass? for the practical solution of mathematical problems. He turned from speculative physics to careful measurements, discovered the law of falling bodies and of the parabolic path of projectiles, studied the motions of pendulums, and investigated mechanics and the strength of materials. He showed little interest in astronomy, although beginning in 1595 he preferred the [[Copernicus|Copernican]] theory that the earth revolves around the sun—to the Aristotelian and Ptolemaic assumption that planets circle a fixed [[earth]]. Only the Copernican model supported Galileo’s tide theory, which was based on motions of the earth. In 1609 he heard that a [[spyglass]] had been invented in [[Holland]]. In August of that year he presented a [[telescope]], about as powerful as a modern field [[glass]], to the doge of [[Venice]]. Its value for [[navy|naval]] and maritime operations resulted in the doubling of his salary and his assurance of lifelong tenure as a professor. |
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By December 1609, Galileo had built a telescope of 20 times magnification, with which he discovered mountains and craters on the [[moon]]. He also saw that the Milky Way was composed of [[stars]], and he discovered the four largest satellites of Jupiter. He published these findings in March 1610 in The Starry Messenger (trans. 1880). His new fame gained him appointment as court mathematician at [[Florence]]; he was thereby freed from teaching duties and had time for research and writing. By December 1610 he had observed the phases of [[Venus]], which contradicted Ptolemaic astronomy and confirmed his preference for the Copernican system. |
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[[Professor]]s of philosophy scorned Galileo’s discoveries because Aristotle had held that only perfectly spherical bodies could exist in the heavens and that nothing new could ever appear there. Galileo also disputed with professors at Florence and Pisa over hydrostatics, and he published a book on floating bodies in 1612. Four printed attacks on this book followed, rejecting Galileo’s physics. In 1613 he published a work on sunspots and predicted victory for the Copernican theory. A Pisan professor, in Galileo’s absence, told the [[Medici]] (the ruling family of [[Florence]] as well as Galileo’s employers) that belief in a moving earth was [[heresy|heretical]]. In 1614 a Florentine [[priest]] denounced Galileists from the [[pulpit]]. Galileo wrote a long, open letter on the irrelevance of biblical passages in scientific arguments, holding that interpretation of the [[Bible]] should be adapted to increasing knowledge and that no scientific position should ever be made an article of Roman [[Catholic]] faith. |
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Early in 1616, Copernican [[book]]s were subjected to censorship by edict, and the [[Jesuit]] [[cardinal]] Robert [[Bellarmine]] instructed Galileo that he must no longer hold or defend the concept that the earth moves. Cardinal Bellarmine had previously advised him to treat this subject only hypothetically and for scientific purposes, without taking Copernican concepts as literally true or attempting to reconcile them with the Bible. Galileo remained silent on the subject for years, working on a method of determining longitudes at sea by using his predictions of the positions of Jupiter’s satellites, resuming his earlier studies of falling bodies, and setting forth his views on scientific reasoning in a book on comets, The Assayer (1623; trans. 1957). |
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In 1624 Galileo began a book he wished to call “Dialogue on the Tides,? in which he discussed the [[Ptolemy|Ptolemaic]] and Copernican hypotheses in relation to the physics of tides. In 1630 the book was licensed for printing by Roman Catholic censors at [[Rome]], but they altered the title to Dialogue on the Two Chief World Systems (trans. 1661). It was published at Florence in 1632. Despite two official licenses, Galileo was summoned to Rome by the Inquisition to stand trial for “grave suspicion of heresy.? This charge was grounded on a report that Galileo had been personally ordered in 1616 not to discuss Copernicanism either orally or in writing. Cardinal Bellarmine had died, but Galileo produced a certificate signed by the cardinal, stating that Galileo had been subjected to no further restriction than applied to any Roman Catholic under the 1616 edict. No signed document contradicting this was ever found, but Galileo was nevertheless compelled in 1633 to abjure and was sentenced to life imprisonment (swiftly commuted to permanent house arrest). The Dialogue was ordered to be burned, and the sentence against him was to be read publicly in every university. |
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Galileo’s final book, Discourses Concerning Two New Sciences (trans. 1662-65), which was published at Leiden in 1638, reviews and refines his earlier studies of motion and, in general, the principles of mechanics. The book opened a road that was to lead Newton to the law of universal gravitation that linked Kepler’s planetary laws with Galileo’s mathematical physics. Galileo became blind before it was published, and he died at Arcetri, near Florence, on January 8, 1642. |
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Galileo’s most valuable scientific contribution was his founding of physics on precise measurements rather than on metaphysical principles and formal logic. More widely influential, however, were The Starry Messenger and the Dialogue, which opened new vistas in astronomy. Galileo’s lifelong struggle to free scientific inquiry from restriction by philosophical and theological interference stands beyond science. Since the full publication of Galileo’s trial documents in the 1870s, entire responsibility for Galileo’s condemnation has customarily been placed on the Roman Catholic church. This conceals the role of the philosophy professors who first persuaded theologians to link Galileo’s science with heresy. An investigation into the astronomer’s condemnation, calling for its reversal, was opened in 1979 by Pope John Paul II. In October 1992 a papal commission acknowledged the Vatican’s error. |
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Latest revision as of 01:33, 12 October 2007
Galileo Galilei (1564-1642), was an Italian physicist and astronomer, most noted for his work on astronomy and falling bodies.
Galileo showed that objects accelarated to the ground independent of their weight by rolling balls of different mass down inclined surfaces. According to the biography of Galileo's pupil Vincenzo Viviani his final proof of this theory involved dropping balls from the Leaning Tower of Pisa, although this is now generally accepted as being untrue, not least because wind resistance would have caused such an experiment to fail.
Galileo's strong support of the Copernican model of the Universe led him into trouble with the Papacy, and he spent the final years of his life under house arrest.
