GALILEO GALILEI, "EPPUR SI MUOVE / AND YET IT MOVES"

Università di Pisa

Today, Joseph de Ca'th Lon and his friends have visited the University of Pisa, one of the most prestigious centres of knowledge and studies in Europe. Joseph likes Astronomy and Science in general and he has wanted to discover new information about Galileo Galilei the great figure of the 16th and 17th centuries.
 

Galileo Galilei (15 February 1564-8 January 1642) was a Tuscan astronomer, physicist and engineer, sometimes described as a polymath. Galileo has been called the father of observational astronomy, the father of modern physics, the father of the scientific method, and the father of modern science.

Galileo studied speed and velocity, gravity and free fall, the principle of relativity, inertia, projectile motion and also worked in applied science and technology, describing the properties of pendulums and hydrostatic balances, inventing the thermoscope and various military compasses, and using the telescope for scientific observations of celestial objects.

His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the observation of the four largest satellites of Jupiter, the observation of Saturn and the analysis of sunspots.

Galileo Gallilei

Galileo's championing of heliocentrism and Copernicanism was controversial during his lifetime, when most subscribed to geocentric models such as the Tychonic system. He met with opposition from astronomers, who doubted heliocentrism because of the absence of an observed stellar parallax. The matter was investigated by the Roman Inquisition in 1615, which concluded that heliocentrism was foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture.

Galileo later defended his views in Dialogue Concerning the Two Chief World Systems (1632), which appeared to attack Pope Urban VIII and thus alienated him and the Jesuits, who had both supported Galileo up until this point. He was tried by the Inquisition, found vehemently suspect of heresy, and forced to recant. He spent the rest of his life under house arrest. While under house arrest, he wrote Two New Sciences, in which he summarized work he had done some forty years earlier on the two sciences now called kinematics and strength of materials.

Galileo was born in Pisa, then part of the Duchy of Florence, on 15 February 1564, the first of six children of Vincenzo Galilei, a famous lutenist, composer, and music theorist, and Giulia, who had married in 1562.

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Galileo became an accomplished lutenist himself and would have learned early from his father a scepticism for established authority, the value of well-measured or quantified experimentation, an appreciation for a periodic or musical measure of time or rhythm, as well as the results expected from a combination of mathematics and experiment.

When Galileo Galilei was eight, his family moved to Florence, but he was left with Jacopo Borghini for two years. He was educated from 1575 to 1578 in the Vallombrosa Abbey, about 30 km southeast of Florence.

Galileo Galilei

Although Galileo seriously considered the priesthood as a young man, at his father's urging he instead enrolled in 1580 at the University of Pisa for a medical degree.

In 1581, when he was studying medicine, he noticed a swinging chandelier, which air currents shifted about to swing in larger and smaller arcs.

To him, it seemed, by comparison with his heartbeat, that the chandelier took the same amount of time to swing back and forth, no matter how far it was swinging. When he returned home, he set up two pendulums of equal length and swung one with a large sweep and the other with a small sweep and found that they kept time together. It was not until the work of Christiaan Huygens, almost one hundred years later, that the tautochrone nature of a swinging pendulum was used to create an accurate timepiece.

Up to this point, Galileo had deliberately been kept away from mathematics, since a physician earned a higher income than a mathematician. However, after accidentally attending a lecture on geometry, he talked his reluctant father into letting him study mathematics and natural philosophy instead of medicine. He created a thermoscope, a forerunner of the thermometer, and, in 1586, published a small book on the design of a hydrostatic balance he had invented, which first brought him to the attention of the scholarly world.

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Galileo also studied disegno, a term encompassing fine art, and, in 1588, obtained the position of instructor in the Accademia delle Arti del Disegno in Florence, teaching perspective and chiaroscuro. Being inspired by the artistic tradition of the city and the works of the Renaissance artists, Galileo acquired an aesthetic mentality. While a young teacher at the Accademia, he began a lifelong friendship with the Florentine painter Cigoli, who included Galileo's lunar observations in one of his paintings.

In 1589, he was appointed to the chair of mathematics in Pisa. In 1591, his father died, and he was entrusted with the care of his younger brother Michelagnolo. In 1592, he moved to the University of Padua where he taught geometry, mechanics, and astronomy until 1610.

The Dialogue by Galileo Galilei

During this period, Galileo made significant discoveries in both pure fundamental science, for example, kinematics of motion and astronomy, as well as practical applied science, for example, strength of materials and pioneering the telescope.

His multiple interests included the study of astrology, which at the time was a discipline tied to the studies of mathematics and astronomy.

In the whole world prior to Galileo's conflict with the Church, the majority of educated people subscribed either to the Aristotelian geocentric view that the earth was the center of the universe and that all heavenly bodies revolved around the Earth, or the Tychonic system that blended geocentrism with heliocentrism.

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On February 19, 1616, the Inquisition asked a commission of theologians, known as qualifiers, about the propositions of the heliocentric view of the universe.

In 1633 Galileo was ordered to stand trial on suspicion of heresy. He was interrogated while threatened with physical torture.

Galileo was found guilty, and the sentence of the Inquisition, issued on 22 June 1633.

According to popular legend, after recanting his theory that the Earth moved around the Sun, Galileo allegedly muttered the rebellious phrase And yet it moves"

It was while Galileo was under house arrest that he dedicated his time to one of his finest works, Two New Sciences. Here he summarised work he had done some forty years earlier, on the two sciences now called kinematics and strength of materials, published in Holland to avoid the censor.

Galileo continued to receive visitors until 1642, when, after suffering fever and heart palpitations, he died on 8 January 1642, aged 77.

The Grand Duke of Tuscany, Ferdinando II, wished to bury him in the main body of the Basilica of Santa Croce, next to the tombs of his father and other ancestors, and to erect a marble mausoleum in his honour.

More information: Galileo Galilei to trial against the Inquisition

Who would set a limit to the mind of man?

Who would dare assert that we know all there is to be known?

Galileo Galilei