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An introduction to the life of galileo galilei

Many books have been written about Galileo, and, in particular, about his interaction with the Church. An excellent short biography is Galileo, Stillman Drake, Oxford. Drake has also written Galileo at Work: His Scientific Biography, Dover.

An enlightening book on the social context, and Galileo's adaptation to it, is Galileo Courtier by Mario Biagioli. I am certainly no expert in this complex field of study, and just present a collection of facts below to try to give the flavor of Galileo's life and times.

Actually, Vincenzio was a revolutionary musician—he felt the formal church music that then dominated the scene had become sterile, and that classic Greek poetry and myths had a power the church music lacked, that perhaps could be translated into modern music. He an introduction to the life of galileo galilei some of this, and his work began the development that culminated in Italian opera. To understand something of Galileo's early upbringing, here is a quote from his father, Vincenzio Galileo: I wish to question freely and to answer freely without any sort of adulation.

That well becomes any who are sincere in the search for truth. Dialogo della Musica Antica et della Moderna, Florence, 1581. I took the quote from Reston quoting J. Fahie, Galileo ,page 3. Now Vincenzio had studied music with the leading musical theorist of the day,Gioseffo Zarlino in Venice. Zarlino had a Pythagorean approach: Similarly, this is how appropriate intervals are determined for adjacent notes. But what about notes half a semitone apart?

Zarlino claimed that was impossible to divide a semitone evenly.

Life of Galileo

But Vincenzio Galileo ridiculed this theory—he could play a note just half way between! In other words, he took a practical rather than a theoretical approach to music: In fact, this was a very old argument: And, it wasn't difficult to believe: Vincenzio proved, by hanging weights on strings, that in fact the tension had to be quadrupled to have the same effect as halving the length.

So Galileo was brought up to believe that theoretical claims needed to be checked experimentally and, in particular, simple linear rules might not always be right.

At age 17, Galileo went to the University of Pisa. He enrolled as a medical student, following his father's advice, but turned to math, after persuading his father that he didn't want to be a doctor. His father allowed him to be tutored by the Tuscan court mathematician, Ricci, who designed fortifications, which no doubt impressed Galileo Reston, page 15. Pendulums and Pulses When he was eighteen, Galileo watched a lamp being lit in the cathedral at Pisa.

Fahie, an introduction to the life of galileo galilei 9; but apparently Fahie is wrong on one irrelevant! These cathedral lamps were very ornate affairs, with many candles. The lamplighter would pull the lamp towards himself, light the candles then let it go. Galileo watched the swinging lit lamp for some time.

He timed its swinging with his pulse, and realized that the period of one swing stayed the same, or very close to the same,as the swings became smaller and smaller. He realized this constancy of swing time could be used to measure a patient's pulse in hospital. This was before watches had been invented—even pendulum clocks came a little later, both Galileo and Huygens developed the concept. Anyway, Galileo, working with a physician friend Santorio, constructed a simple device, which became known as a pulsilogia, and became widely used.

Basically, it was a pendulum of adjustable length, the length being set by the physician so the swings coincided with the patient's pulse, a built-in ruler than read off the pulse rate.

At age 25, he was appointed to the Chair of Mathematics at Pisa. His job interview was to give two lectures to the Florentine Academy on mathematical topics. This Academy's main function was to glorify the Medicis, the ruling family, and of course Florence itself. In contrast to heaven, out there somewhere and doubtless made of aetherial material, Hell was constructed of familiar stuff, so could be mathematically analyzed, like any architectural construction.

Galileo presented his lecture as a description of two different plans of hell, one by Antonio Manetti, a Florentine, and one by Alessandro Vellutello, from Lucca, a rival city. He showed off some of his new mathematical results here: People had been skeptical of Manetti's hell, though: Galileo argued that this was no problem: The lectures went over very well, and he got the job. But then it dawned on him that he'd made a mistake, and his whole analysis, comparing the roof of hell with the cathedral, was seriously flawed.

He kept very quiet. We'll return to this important point later. At age 28, in 1592, Galileo moved to a better position at Padua, in the Venetian Republic, where he stayed until the age of 46. Wine, Women and Dialogue Reston's book certainly paints a vivid picture of the Venetian Republic at the time Galileo moved there!

Venice, a city of 150,000 people, apparently consumed 40 million bottles of wine annually. There were more courtesans than in Rome. In 1599, Galileo met one Marina Gamba, 21 years old. He had three children by her, greatly upsetting his mother. Galileo also spent a lot of time with Sagredo, a young Venetian nobleman, both in the town and at Sagredo's very fancy house, or palace. Another close friend during this period was Fra Paolo Sarpi, a Servite friar, and official theologian to the Republic of Venice in 1606, when Pope Paul put Venice under the interdict.

Tensions between Venice and Rome were partly generated because Venice wanted to be able to tax churches built in Venice by Rome. Sarpi advised the Venetians to ignore the interdict, and the Jesuits were expelled from Venice. A nearly successful attempt on Sarpi's life was generally blamed on the Jesuits from Drake, page 28.

  1. This move upset his friends in Venice who had worked so hard to secure his promotion at Padua only months before.
  2. Nevertheless, in February 1616, the Copernican System was condemned. Possibly he thinks that philosophy is a book of fiction by some author, like the Iliad...
  3. Incidentally, Galileo was thinking about quite a different series of physics problems at this same time-trying to understand when things will float and when they sink.
  4. But what about notes half a semitone apart? Another document, however, which was unsigned and therefore perhaps of questionable accuracy , stated that the Commissary of the Inquisition, in the name of the pope, ordered that Galileo could no longer hold, defend or teach the two propositions Drake, page 67.
  5. Galileo published his findings in 1613, with a preface asserting his priority of discovery. That would account correctly for the phases of Venus.

By naming the moons of Jupiter after the Medici family, Galileo landed the job of Mathematician and Philosopher meaning Physicist to the Grand Duke of Tuscany, and was able to return to his native land. This move upset his friends in Venice who had worked so hard to secure his promotion at Padua only months before. Of course, Galileo's belief that his discoveries with the telescope strongly favored the Copernican world view meant he was headed for trouble with the Church.

In fact, his Venetian friends warned him that it might be dangerous to leave the protection of the Venetian state. Nevertheless, in 1611, Galileo went to Rome and met with the Jesuit astronomers. Probably he felt that if he could win them over, he would smooth his path in any future problems with the Church. Father Clavius, author of Gregorian Calendar and undisputed leader of Jesuit astronomy had a hard time believing there were mountains on the moon, but he surrendered with good grace on looking through the telescope Sant.

  • He kept very quiet;
  • Galileo wrote in his old age, in his own copy of the Dialogue;
  • By naming the moons of Jupiter after the Medici family, Galileo landed the job of Mathematician and Philosopher meaning Physicist to the Grand Duke of Tuscany, and was able to return to his native land;
  • He mocked the pope himself, by putting Urban's suggestion see above in the mouth of Simplicio, then dismissing it contemptuously Reston, page 195.

Bellarmine wrote in a letter to A. Foscarini, 12 April 1615: But I will not believe that there is such a demonstration, until it is shown me. Somewhat earlier—Dec 1613—Galileo had written a letter to Castelli a Benedictine abbot and former pupil of Galileo's saying in essence that Scripture cannot contradict what we see in nature, so scripture, written for the business of saving souls and readable by everybody, sometimes is metaphorical in describing nature.

It seems that Bellarmine and Galileo might have been able to come to some agreement on a world view. Incidentally, Galileo was thinking about quite a different series of physics problems at this same time-trying to understand when things will float and when they sink.

He believed Archimedes' Principle, that denser objects than water sink in water. To be precise, the Principle states that the buoyant supporting force from the water on an immersed object is equal to the weight of the water displaced by the object. That is, it is equal to the weight of a volume of water equal to the volume of the object. So if the object is denser than water, its weight is greater than the buoyancy force and it sinks.

It was pointed out to him that a ball made of ebony sinks in water, but a flat chip of ebony floats. We now understand this in terms of surface tension, but that had not been understood in Galileo's time. Nevertheless, Galileo gave an essentially correct answer: Galileo discussed problems of this kind with a Florentine patrician, Filippo Salviati, and a group of his acquaintances.

As usual, Galileo's style and ability to pulverize the opposition did not win many friends. Salviati appears as one of the three disputants in Galileo's Dialogue.

Since 1611, Galileo had been observing the motion of sunspots: They were observed independently at about the same time by Christopher Scheiner, a German Jesuit from Ingoldstadt. It is possible that Scheiner had somehow heard of Galileo's observations. Scheiner thought they were small dark objects circling the sun at some distance, Galileo correctly surmised they were actually on the sun's surface, another blow to the perfect incorruptibility of a heavenly body.

Galileo published his findings in 1613, with a preface asserting his priority of discovery. This greatly upset Scheiner. About this time, some members of another order of the Church, the Dominicans, were becoming aware of the Copernican world view, and began to preach against it. In 1613, Father Nicolo Lorini, a professor of ecclesiastical history in Florence, inveighed against the new astronomy, in particular "Ipernicus".

One more step

He wrote a letter of apology after being reproved. In 1614, another Dominican, Father Tommaso Caccini, who had previously been reprimanded for rabble-rousing, preached a sermon with the text "Ye men of Galilee, why stand ye gazing up into the heaven? In the popular mind, mathematician tended to mean astrologer.

It should be added that these two were by no means representative of the order as a whole. The Dominican Preacher General, Father Luigi Maraffi, wrote Galileo an apology, saying "unfortunately I have to answer for all the idiocies that thirty or forty thousand brothers may or actually do commit". According to De Santillana page 45 in 1615 Father Lorini sends an altered copy of Galileo's letter to Castelli mentioned above to the Inquisition.

He made two changes, one of which was to go from "There are in scripture words which, taken in the strictly literal meaning, look as if they differ from the truth" to "which are false in the literal meaning".