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Galileo Galilei

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The "Academy of the Lynxes" seem to be an early version of the Royal Society; Shame Prince Cesi died before the publication of Dialogue Concerning The Two Chief World Systems.

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Community entry:Galileo Galilei

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Galilieo before the Inquisition 1632

Galileo Galilei was born in Pisa in 1564, the son of Vincenzo Galilei, well known for his studies of music, and Giulia Ammannati. He studied at Pisa, where he later held the chair in mathematics from 1589 - 1592. He was then appointed to the chair of mathematics at the University of Padua, where he remained until 1610. During these years he carried out studies and experiments in mechanics, and also built a thermoscope . He devised and constructed a geometrical and military compass, and wrote a handbook which describes how to use this instrument. In 1594 he obtained the patent for a machine to raise water levels . He invented the microscope, and built a telescope with which he made celestial observations, the most spectacular of which was his discovery of the satellites of Jupiter. In 1610 he was nominated the foremost Mathematician of the University of Pisa and given the title of mathematician to the Grand Duke of Tuscany. He studied Saturn and observed the phases of Venus. In 1611 he went to Rome. He became a member of the Accademia dei Lincei (Academy of the Lynxes) and observed the sunspots. In 1612 he began to encounter serious opposition to his theory of the motion of the earth that he taught after Copernicus. In 1614, Father Tommaso Caccini denounced the opinions of Galileo on the motion of the Earth from the pulpit of Santa Maria Novella, judging them to be erroneous. Galileo therefore went to Rome, where he defended himself against charges that had been made against him but, in 1616, he was admonished by Cardinal Bellarmino and told that he could not defend Copernican astronomy because it went against the doctrine of the Church. In 1622 he wrote the Saggiatore (The Assayer ) which was approved and published in 1623. In 1630 he returned to Rome to obtain the right to publish his Dialogue on the two chief world systems which was eventually published in Florence in 1632. In October of 1632 he was summoned by the Holy Office to Rome. The tribunal passed a sentence condemning him and compelled Galileo to solemnly abjure his theory. He was sent to exile in Siena and finally, in December of 1633, he was allowed to retire to his villa in Arcetri, the Gioiello. His health condition was steadily declining, - by 1638 he was completely blind, and also by now bereft of the support of his daughter, Sister Maria Celeste, who died in 1634. Galileo died in Arcetri on 8 January 1642.

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Galileo Galilei
(Pisa 1564 - Arcetri, Florence 1642)

Mechanics

The contributions made by Galileo to mechanics remain fundamental, despite the fact that this field of research met with less interest from the Medici Grand Dukes than Galileo's astronomical discoveries, perhaps because it was less spectacular. Galileo's investigations concerned the natural descent of bodies along planes of various inclinations, the formulation of the law which established the relationship between space traversed and time interval in free-fall, the isochronism of the oscillations of pendulums of equal lengths and, of particular importance, the motion of projectiles. At the end of the eighteenth century, from the necessity of displaying some of the mechanical principles discovered and demonstrated by Galileo, the Florentine Museum of Physics and Natural History had experimental devices constructed, such as the model of the inclined plane, the brachistochrone descent and the machine for raising water.

Astronomy

The observations of the sky which Galileo carried out with his telescope led to the discovery of the satellites of Jupiter and to Galileo's increased adherence the Copernican System . The phenomena which were revealed little by little due to the increased possibility of larger lenses were described and illustrated by Galileo in Sidereus Nuncius . The periods and frequencies of appearances of the satellites of Jupiter were studied by Galileo in order to develop a method for determining longitudes at sea .

The microscope

In the early years of the seventeenth century Galileo adapted a telescope for the viewing of extremely small objects. Between 1619 and 1624 he began to produce microscopes or "occhialini" as he called them. The Galileian microscope is made up of the tube of a telescope, of reduced size, furnished with two lenses. Galileo gave his "occhialino" to various people. He sent a letter to Federigo Cesi , accompanying the instrument, in which he explained the means by which it was focussed and the arrangement of objects for observation.

Thermometry

Viviani recounts that Galileo dedicated himself to research on heat at the end of the 16th century. The invention of the thermoscope seems, then, to belong to his Paduan period. This device was used to carry out experiments on the relationship between changes of temparature and variations of the level of the liquid. The work of the Accademia del Cimento which led to the birth of the Florentine thermometer had its origins in Galileo's early research.

Magnetism

Between 1600 and 1609 Galileo devoted himself to studying magnetism, inspired by William Gilbert 's De magnet. He attempted to increase the strength of loadstones by means of special armatures. One of these was given to Grand Duke Ferdinand II by Galileo.

Accademia dei Lincei

It was founded in 1603 by the young Prince Federico Cesi and his friends, Anastasio Di Filiis, Johannes Van Heeck, and Francesco Stelluti . It aimed at a radical renewal of scientific knowledge and it encouraged a vigorous critical approach to the dominant Aristotelian philosophy.

They chose the lynx as their emblem, to stress the importance of sharp and penetrating insight into nature. The Academy realized the revolutionary importance of the celestial discoveries that Galileo made with his new telescope in 1610. The Academy praised Galileo and elected him on December 25, 1611. The Academy defended Galileo in his controversies with leaders of the establishment and protected him when he was denounced to the ecclesiastical authorities. The Academy published at its own expense Galileo's Istoria e dimostrazione intorno alle macchie solari in 1613, and his Assayer in 1623.

The Academy did not survive the death of Prince Federico Cesi in 1630 and Galileo was left without influential help when his Dialogue concerning the Two Chief World Systems was attacked.

The Linceans produced an important collection of micrographs, or drawings made with the help of the newly invented microscope. After Cesi's death, the academy closed and the drawings were collected by Cassiano dal Pozzo, a Roman antiquarian, who sold them in 1763 to George III of the United Kingdom. The drawings were discovered in Windsor Castle in 1986 by art historian David Freedberg.

Sunspots

Apparent references to sunspots were made by first millennium AD Chinese astronomers, who probably could see the largest spot groups when the sun's glare was filtered by wind-borne dust from the various central Asian deserts. They were first observed telescopically by Frisian astronomers Johannes and David Fabricius in 1611; their discovery was overlooked however, and there soon arose a dispute between Christoph Scheiner and Galileo Galilei over who first saw sunspots -- both discovered them independently of each other within a few months of the Fabriciuses.

Dialogue Concerning The Two Chief World Systems

This work, published in Florence in 1632, was Galileo 's scientific and literary masterpiece. In it he discussed the relative merits of the Ptolemaic and Copernican systems by means of three interlocutors: Filippo Salviati (a committed Florentine Copernican), Giovanfrancesco Sagredo (an open-minded Venetian, initially neutral with respect to the theories) and the Aristotelian Simplicio (a defender of the Ptolemaic theory). The author imagines that the three speakers discuss the heliocentric system over four days. The work was written in Italian in order to increase its circulation and was condemned along with Galileo himself for the principles which it supported.