Galileo Galilei

Galileo Galilei

Born: 15 Feb 1564 in Pisa (now in Italy)

Died: 8 Jan 1642 in Arcetri (near Florence) (now in Italy)

Galileo Galilei's parents were Vincenzo Galilei and Guilia Ammannati. Vincenzo, who was born in Florence in 1520, was a teacher of music and a fine lute player. After studying music in Venice he carried out experiments on strings to support his musical theories. Guilia, who was born in Pescia, married Vincenzo in 1563 and they made their home in the countryside near Pisa. Galileo was their first child and spent his early years with his family in Pisa.

In 1572, when Galileo was eight years old, his family returned to Florence, his father's home town. However, Galileo remained in Pisa and lived for two years with Muzio Tedaldi who was related to Galileo's mother by marriage. When he reached the age of ten, Galileo left Pisa to join his family in Florence and there he was tutored by Jacopo Borghini. Once he was old enough to be educated in a monastery, his parents sent him to the Camaldolese Monastery at Vallombrosa which is situated on a magnificent forested hillside 33 km southeast of Florence. The Camaldolese Order was independent of the Benedictine Order, splitting from it in about 1012. The Order combined the solitary life of the hermit with the strict life of the monk and soon the young Galileo found this life an attractive one. He became a novice, intending to join the Order, but this did not please his father who had already decided that his eldest son should become a medical doctor.

Vincenzo had Galileo return from Vallombrosa to Florence and give up the idea of joining the Camaldolese order. He did continue his schooling in Florence, however, in a school run by the Camaldolese monks. In 1581 Vincenzo sent Galileo back to Pisa to live again with Muzio Tedaldi and now to enrol for a medical degree at the University of Pisa. Although the idea of a medical career never seems to have appealed to Galileo, his father's wish was a fairly natural one since there had been a distinguished physician in his family in the previous century. Galileo never seems to have taken medical studies seriously, attending courses on his real interests which were in mathematics and natural philosophy. His mathematics teacher at Pisa was Filippo Fantoni, who held the chair of mathematics. Galileo returned to Florence for the summer vacations and there continued to study mathematics.

In the year 1582-83 Ostilio Ricci, who was the mathematician of the Tuscan Court and a former pupil of Tartaglia, taught a course on Euclid's Elements at the University of Pisa which Galileo attended. During the summer of 1583 Galileo was back in Florence with his family and Vincenzo encouraged him to read Galen to further his medical studies. However Galileo, still reluctant to study medicine, invited Ricci (also in Florence where the Tuscan court spent the summer and autumn) to his home to meet his father. Ricci tried to persuade Vincenzo to allow his son to study mathematics since this was where his interests lay. Certainly Vincenzo did not like the idea and resisted strongly but eventually he gave way a little and Galileo was able to study the works of Euclid and Archimedes from the Italian translations which Tartaglia had made. Of course he was still officially enrolled as a medical student at Pisa but eventually, by 1585, he gave up this course and left without completing his degree.

Galileo began teaching mathematics, first privately in Florence and then during 1585-86 at Siena where he held a public appointment. During the summer of 1586 he taught at Vallombrosa, and in this year he wrote his first scientific book The little balance [La Balancitta] which described Archimedes' method of finding the specific gravities (that is the relative densities) of substances using a balance. In the following year he travelled to Rome to visit Clavius who was professor of mathematics at the Jesuit Collegio Romano there. A topic which was very popular with the Jesuit mathematicians at this time was centres of gravity and Galileo brought with him some results which he had discovered on this topic. Despite making a very favourable impression on Clavius, Galileo failed to gain an appointment to teach mathematics at the University of Bologna.

After leaving Rome Galileo remained in contact with Clavius by correspondence and Guidobaldo del Monte was also a regular correspondent. Certainly the theorems which Galileo had proved on the centres of gravity of solids, and left in Rome, were discussed in this correspondence. It is also likely that Galileo received lecture notes from courses which had been given at the Collegio Romano, for he made copies of such material which still survive today. The correspondence began around 1588 and continued for many years. Also in 1588 Galileo received a prestigious invitation to lecture on the dimensions and location of hell in Dante's Inferno at the Academy in Florence.

Fantoni left the chair of mathematics at the University of Pisa in 1589 and Galileo was appointed to fill the post (although this was only a nominal position to provide financial support for Galileo). Not only did he receive strong recommendations from Clavius, but he also had acquired an excellent reputation through his lectures at the Florence Academy in the previous year. The young mathematician had rapidly acquired the reputation that was necessary to gain such a position, but there were still higher positions at which he might aim. Galileo spent three years holding this post at the university of Pisa and during this time he wrote De Motu a series of essays on the theory of motion which he never published. It is likely that he never published this material because he was less than satisfied with it, and this is fair for despite containing some important steps forward, it also contained some incorrect ideas. Perhaps the most important new ideas which De Motu contains is that one can test theories by conducting experiments. In particular the work contains his important idea that one could test theories about falling bodies using an inclined plane to slow down the rate of descent.

In 1591 Vincenzo Galilei, Galileo's father, died and since Galileo was the eldest son he had to provide financial support for the rest of the family and in particular have the necessary financial means to provide dowries for his two younger sisters. Being professor of mathematics at Pisa was not well paid, so Galileo looked for a more lucrative post. With strong recommendations from Guidobaldo del Monte, Galileo was appointed professor of mathematics at the University of Padua (the university of the Republic of Venice) in 1592 at a salary of three times what he had received at Pisa. On 7 December 1592 he gave his inaugural lecture and began a period of eighteen years at the university, years which he later described as the happiest of his life. At Padua his duties were mainly to teach Euclid's geometry and standard (geocentric) astronomy to medical students, who would need to know some astronomy in order to make use of astrology in their medical practice. However, Galileo argued against Aristotle's view of astronomy and natural philosophy in three public lectures he gave in connection with the appearance of a New Star (now known as 'Kepler's supernova') in 1604. The belief at this time was that of Aristotle, namely that all changes in the heavens had to occur in the lunar region close to the Earth, the realm of the fixed stars being permanent. Galileo used parallax arguments to prove that the New Star could not be close to the Earth. In a personal letter written to Kepler in 1598, Galileo had stated that he was a Copernican (believer in the theories of Copernicus). However, no public sign of this belief was to appear until many years later.

At Padua, Galileo began a long term relationship with Maria Gamba, who was from Venice, but they did not marry perhaps because Galileo felt his financial situation was not good enough. In 1600 their first child Virginia was born, followed by a second daughter Livia in the following year. In 1606 their son Vincenzo was born.

We mentioned above an error in Galileo's theory of motion as he set it out in De Motu around 1590. He was quite mistaken in his belief that the force acting on a body was the relative difference between its specific gravity and that of the substance through which it moved. Galileo wrote to his friend Paolo Sarpi, a fine mathematician who was consultor to the Venetian government, in 1604 and it is clear from his letter that by this time he had realised his mistake. In fact he had returned to work on the theory of motion in 1602 and over the following two years, through his study of inclined planes and the pendulum, he had formulated the correct law of falling bodies and had worked out that a projectile follows a parabolic path. However, these famous results would not be published for another 35 years.

In May 1609, Galileo received a letter from Paolo Sarpi telling him about a spyglass that a Dutchman had shown in Venice. Galileo wrote in the Starry Messenger (Sidereus Nuncius) in April 1610:-

About ten months ago a report reached my ears that a certain Fleming had constructed a spyglass by means of which visible objects, though very distant from the eye of the observer, were distinctly seen as if nearby. Of this truly remarkable effect several experiences were related, to which some persons believed while other denied them. A few days later the report was confirmed by a letter I received from a Frenchman in Paris, Jacques Badovere, which caused me to apply myself wholeheartedly to investigate means by which I might arrive at the invention of a similar instrument. This I did soon afterwards, my basis being the doctrine of refraction.

From these reports, and using his own technical skills as a mathematician and as a craftsman, Galileo began to make a series of telescopes whose optical performance was much better than that of the Dutch instrument. His first telescope was made from available lenses and gave a magnification of about four times. To improve on this Galileo learned how to grind and polish his own lenses and by August 1609 he had an instrument with a magnification of around eight or nine. Galileo immediately saw the commercial and military applications of his telescope (which he called a perspicillum) for ships at sea. He kept Sarpi informed of his progress and Sarpi arranged a demonstration for the Venetian Senate. They were very impressed and, in return for a large increase in his salary, Galileo gave the sole rights for the manufacture of telescopes to the Venetian Senate. It seems a particularly good move on his part since he must have known that such rights were meaningless, particularly since he always acknowledged that the telescope was not his invention!

By the end of 1609 Galileo had turned his telescope on the night sky and began to make remarkable discoveries. Swerdlow writes (see [16]):-

In about two months, December and January, he made more discoveries that changed the world than anyone has ever made before or since.

The astronomical discoveries he made with his telescopes were described in a short book called the Starry Messenger published in Venice in May 1610. This work caused a sensation. Galileo claimed to have seen mountains on the Moon, to have proved the Milky Way was made up of tiny stars, and to have seen four small bodies orbiting Jupiter. These last, with an eye to getting a position in Florence, he quickly named 'the Medicean stars'. He had also sent Cosimo de Medici, the Grand Duke of Tuscany, an excellent telescope for himself.

The Venetian Senate, perhaps realising that the rights to manufacture telescopes that Galileo had given them were worthless, froze his salary. However he had succeeded in impressing Cosimo and, in June 1610, only a month after his famous little book was published, Galileo resigned his post at Padua and became Chief Mathematician at the University of Pisa (without any teaching duties) and 'Mathematician and Philosopher' to the Grand Duke of Tuscany. In 1611 he visited Rome where he was treated as a leading celebrity; the Collegio Romano put on a grand dinner with speeches to honour Galileo's remarkable discoveries. He was also made a member of the Accademia dei Lincei (in fact the sixth member) and this was an honour which was especially important to Galileo who signed himself 'Galileo Galilei Linceo' from this time on.

While in Rome, and after his return to Florence, Galileo continued to make observations with his telescope. Already in the Starry Messenger he had given rough periods of the four moons of Jupiter, but more precise calculations were certainly not easy since it was difficult to identify from an observation which moon was I, which was II, which III, and which IV. He made a long series of observations and was able to give accurate periods by 1612. At one stage in the calculations he became very puzzled since the data he had recorded seemed inconsistent, but he had forgotten to take into account the motion of the Earth round the sun.

Galileo first turned his telescope on Saturn on 25 July 1610 and it appeared as three bodies (his telescope was not good enough to show the rings but made them appear as lobes on either side of the planet). Continued observations were puzzling indeed to Galileo as the bodies on either side of Saturn vanished when the ring system was edge on. Also in 1610 he discovered that, when seen in the telescope, the planet Venus showed phases like those of the Moon, and therefore must orbit the Sun not the Earth. This did not enable one to decide between the Copernican system, in which everything goes round the Sun, and that proposed by Tycho Brahe in which everything but the Earth (and Moon) goes round the Sun which in turn goes round the Earth. Most astronomers of the time in fact favoured Brahe's system and indeed distinguishing between the two by experiment was beyond the instruments of the day. However, Galileo knew that all his discoveries were evidence for Copernicanism, although not a proof. In fact it was his theory of falling bodies which was the most significant in this respect, for opponents of a moving Earth argued that if the Earth rotated and a body was dropped from a tower it should fall behind the tower as the Earth rotated while it fell. Since this was not observed in practice this was taken as strong evidence that the Earth was stationary. However Galileo already knew that a body would fall in the observed manner on a rotating Earth.

Other observations made by Galileo included the observation of sunspots. He reported these in Discourse on floating bodies which he published in 1612 and more fully in Letters on the sunspots which appeared in 1613. In the following year his two daughters entered the Franciscan Convent of St Matthew outside Florence, Virginia taking the name Sister Maria Celeste and Livia the name Sister Arcangela. Since they had been born outside of marriage, Galileo believed that they themselves should never marry. Although Galileo put forward many revolutionary correct theories, he was not correct in all cases. In particular when three comets appeared in 1618 he became involved in a controversy regarding the nature of comets. He argued that they were close to the Earth and caused by optical refraction. A serious consequence of this unfortunate argument was that the Jesuits began to see Galileo as a dangerous opponent.

Despite his private support for Copernicanism, Galileo tried to avoid controversy by not making public statements on the issue. However he was drawn into the controversy through Castelli who had been appointed to the chair of mathematics in Pisa in 1613. Castelli had been a student of Galileo's and he was also a supporter of Copernicus. At a meeting in the Medici palace in Florence in December 1613 with the Grand Duke Cosimo II and his mother the Grand Duchess Christina of Lorraine, Castelli was asked to explain the apparent contradictions between the Copernican theory and Holy Scripture. Castelli defended the Copernican position vigorously and wrote to Galileo afterwards telling him how successful he had been in putting the arguments. Galileo, less convinced that Castelli had won the argument, wrote Letter to Castelli to him arguing that the Bible had to be interpreted in the light of what science had shown to be true. Galileo had several opponents in FlorenceRome. However, after examining its contents they found little to which they could object. and they made sure that a copy of the Letter to Castelli was sent to the Inquisition in

The Catholic Church's most important figure at this time in dealing with interpretations of the Holy Scripture was Cardinal Robert Bellarmine. He seems at this time to have seen little reason for the Church to be concerned regarding the Copernican theory. The point at issue was whether Copernicus had simply put forward a mathematical theory which enabled the calculation of the positions of the heavenly bodies to be made more simply or whether he was proposing a physical reality. At this time Bellarmine viewed the theory as an elegant mathematical one which did not threaten the established Christian belief regarding the structure of the universe.

In 1616 Galileo wrote the Letter to the Grand Duchess which vigorously attacked the followers of Aristotle. In this work, which he addressed to the Grand Duchess Christina of Lorraine, he argued strongly for a non-literal interpretation of Holy Scripture when the literal interpretation would contradict facts about the physical world proved by mathematical science. In this Galileo stated quite clearly that for him the Copernican theory is not just a mathematical calculating tool, but is a physical reality:-

I hold that the Sun is located at the centre of the revolutions of the heavenly orbs and does not change place, and that the Earth rotates on itself and moves around it. Moreover ... I confirm this view not only by refuting Ptolemy's and Aristotle's arguments, but also by producing many for the other side, especially some pertaining to physical effects whose causes perhaps cannot be determined in any other way, and other astronomical discoveries; these discoveries clearly confute the Ptolemaic system, and they agree admirably with this other position and confirm it.

Pope Paul V ordered Bellarmine to have the Sacred Congregation of the Index decide on the Copernican theory. The cardinals of the Inquisition met on 24 February 1616 and took evidence from theological experts. They condemned the teachings of Copernicus, and Bellarmine conveyed their decision to Galileo who had not been personally involved in the trial. Galileo was forbidden to hold Copernican views but later events made him less concerned about this decision of the Inquisition. Most importantly Maffeo Barberini, who was an admirer of Galileo, was elected as Pope Urban VIII. This happened just as Galileo's book Il saggiatore (The Assayer) was about to be published by the Accademia dei Lincei in 1623 and Galileo was quick to dedicate this work to the new Pope. The work described Galileo's new scientific method and contains a famous quote regarding mathematics:-

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in a dark labyrinth.

Pope Urban VIII invited Galileo to papal audiences on six occasions and led Galileo to believe that the Catholic Church would not make an issue of the Copernican theory. Galileo, therefore, decided to publish his views believing that he could do so without serious consequences from the Church. However by this stage in his life Galileo's health was poor with frequent bouts of severe illness and so even though he began to write his famous Dialogue in 1624 it took him six years to complete the work.

Galileo attempted to obtain permission from Rome to publish the Dialogue in 1630 but this did not prove easy. Eventually he received permission from Florence, and not Rome. In February 1632 Galileo published Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican. It takes the form of a dialogue between Salviati, who argues for the Copernican system, and Simplicio who is an Aristotelian philosopher. The climax of the book is an argument by Salviati that the Earth moves which was based on Galileo's theory of the tides. Galileo's theory of the tides was entirely false despite being postulated after Kepler had already put forward the correct explanation. It was unfortunate, given the remarkable truths the Dialogue supported, that the argument which Galileo thought to give the strongest proof of Copernicus's theory should be incorrect.

Shortly after publication of Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican the Inquisition banned its sale and ordered Galileo to appear in Rome before them. Illness prevented him from travelling to Rome until 1633. Galileo's accusation at the trial which followed was that he had breached the conditions laid down by the Inquisition in 1616. However a different version of this decision was produced at the trial rather than the one Galileo had been given at the time. The truth of the Copernican theory was not an issue therefore; it was taken as a fact at the trial that this theory was false. This was logical, of course, since the judgement of 1616 had declared it totally false.

Found guilty, Galileo was condemned to lifelong imprisonment, but the sentence was carried out somewhat sympathetically and it amounted to house arrest rather than a prison sentence. He was able to live first with the Archbishop of Siena, then later to return to his home in Arcetri, near Florence, but had to spend the rest of his life watched over by officers from the Inquisition. In 1634 he suffered a severe blow when his daughter Virginia, Sister Maria Celeste, died. She had been a great support to her father through his illnesses and Galileo was shattered and could not work for many months. When he did manage to restart work, he began to write Discourses and mathematical demonstrations concerning the two new sciences.

After Galileo had completed work on the Discourses it was smuggled out of Italy, and taken to Leyden in Holland where it was published. It was his most rigorous mathematical work which treated problems on impetus, moments, and centres of gravity. Much of this work went back to the unpublished ideas in De Motu from around 1590 and the improvements which he had worked out during 1602-1604. In the Discourses he developed his ideas of the inclined plane writing:-

I assume that the speed acquired by the same movable object over different inclinations of the plane are equal whenever the heights of those planes are equal.

He then described an experiment using a pendulum to verify his property of inclined planes and used these ideas to give a theorem on acceleration of bodies in free fall:-

The time in which a certain distance is traversed by an object moving under uniform acceleration from rest is equal to the time in which the same distance would be traversed by the same movable object moving at a uniform speed of one half the maximum and final speed of the previous uniformly accelerated motion.

After giving further results of this type he gives his famous result that the distance that a body moves from rest under uniform acceleration is proportional to the square of the time taken.

One would expect that Galileo's understanding of the pendulum, which he had since he was a young man, would have led him to design a pendulum clock. In fact he only seems to have thought of this possibility near the end of his life and around 1640 he did design the first pendulum clock. Galileo died in early 1642 but the significance of his clock design was certainly realised by his son Vincenzo who tried to make a clock to Galileo's plan, but failed.

It was a sad end for so great a man to die condemned of heresy. His will indicated that he wished to be buried beside his father in the family tomb in the Basilica of Santa Croce but his relatives feared, quite rightly, that this would provoke opposition from the Church. His body was concealed and only placed in a fine tomb in the church in 1737 by the civil authorities against the wishes of many in the Church. On 31 October 1992, 350 years after Galileo's death, Pope John Paul II gave an address on behalf of the Catholic Church in which he admitted that errors had been made by the theological advisors in the case of Galileo. He declared the Galileo case closed, but he did not admit that the Church was wrong to convict Galileo on a charge of heresy because of his belief that the Earth rotates round the sun.

Article by: J J O'Connor and E F Robertson

Galileo Galilei
lahir : 15 pebruari 1564 di Pisa ( sekarang itali )
meninggal : 8 membunyikan 1642 di Arcetri ( dekat Florence ) ( sekarang itali )

Orangtua Galileo Galilei adalah Vincenzo Galilei dan Guilia Ammannati. Vincenzo, lahir di Florence tahun 1520, guru musik dan pengamen semacam kecapi. Setelah belajar musik di Venice dia membawa keluar percobaan di dawai-dawai ke teori komidi musik nya. Guilia, lahir di Pescia, menikah dengan Vincenzo tahun 1563 dan mereka membuat rumah di daerah pedalaman di dekat Pisa. Galileo anak pertama mereka dan menghabiskan tahun nya dengan keluarga nya di Pisa.

Tahun 1572, ketika Galileo berusia delapan tahun, keluarga nya kembali ke Florence, kota ayahnya. Bagaimanapun, Galileo tinggal di Pisa dan hidup selama dua tahun dengan Muzio Tedaldi saudara ibunya Galileo oleh perkawinan. Ketika dia mencapai usia sepuluh tahun, Galileo meninggalkan Pisa untuk bergabung dengan keluarga nya di Florence dan disana dia mengajar privat oleh Jacopo Borghini. Sekali dia cukup usia dididik di biara, para orang tua nya mengirim dia ke Biara Camaldolese di Vallombrosa yang mana letaknya di lereng bukit berhutan 33 tenggara km Florence. Perintah Camaldolese adalah perintah penting dari perintah Benedictine, pemisahan itu kira-kira 1012. Perintah ini mengkombinasikan hidup terpencil pertapa dengan hidup keras rahib dan dengan segera Galileo muda menemukan ini sebagai salah satu hidup yang menarik. Dia menjadi orang baru, berniat untuk bergabung dengan perintah, tetapi hal ini tidak menyenangkan bapak nya yang memutuskan anak lelaki tertua sulung nya harus menjadi dokter medis.

Vincenzo Galileo kembalinya dari Vallombrosa ke Florence dan memberi gagasan bergabung dengan Perintah Camaldolese. Dia melanjutkan sekolahnya di Florence, bagaimanapun, sekolahnya di Camaldolese terputus. Tahun 1581 Vincenzo mengirim Galileo kembali ke Pisa dan hidup lagi dengan Muzio Tedaldi dan sekarang untuk didaftarkan pada universitas Pisa. Walaupun gagasan karir medis tak pernah nampak untuk Galileo, keinginan nya natural suatu kewajaran sejak abad sebelumnya disana dokter dibedakan keluarga nya. Galileo tak pernah nampak mempunyai keseriusan mengambil belajar medis, jalan menghadiri minat riil pada nya di matematika dan filosofi natural. Guru matematika nya di Pisa Filippo Fantoni , mengadakan kursi matematika. Galileo kembali ke Florence pada liburan musim panas dan disana melanjutkan belajar matematika.
Pada tahun 1582-83 Ostilio Ricci, siapa ahli matematika Tuscan pengadilan dan murid terdahulu Tartaglia, mengajar jalan elemennya pada Euclid pada universitas Pisa yang dihadiri Galileo. Selama musim panas 1583 Galileo kembali ke Florence dengan keluarga nya dan Vincenzo didukung dia untuk belajar medis lebih lanjut. Bagaimanapun Galileo masih segan belajar ilmu kedokteran, diundang Ricci (juga di Florence di mana Tuscan menghabiskan musim panas dan musim gugur) di rumah nya untuk bertemu bapak nya. Ricci dicoba untuk membujuk Vincenzo untuk membolehkan anak lelaki nya belajar matematika sejak ini di mana minat nya pasti Vincenzo lakukan tidak seperti gagasan dan betul-betul menentang tetapi secepatnya dia jalan memberi sedikit dan Galileo dapat belajar bekerja Euclid dan archimedes dari terjemahan italia yang Tartaglia buat. Jalan dia masih resmi didaftarkan sebagai siswa medis di Pisa. Tetapi secepatnya, Tahun 1585 , dia menemukan jalannya dan tanpa menunggu melengkapi derajat nya.
Galileo mulai mengajar matematika, pertama di Florence dan kemudian selama 1585-86 pada Siena di mana dia mengadakan pengangkatan publik. Selama musim panas 1586 dia mengajar pada Vallombrosa, dan di tahun ini dia menulis buku ilmiah pertama nya keseimbangan sedikit [ La Balancitta ] yang menguraikan metode Archimedes menemukan spesifik gravities ( yang sanak densities ) zat menggunakan keseimbangan. Di tahun ini dia pergi ke roma untuk mengunjungi Clavius guru besar matematika pada Jesuit disana romawi kolektif. Topik yang sangat populer dengan Jesuit ahli matematika pada waktu ini memusat berat dan Galileo membawa beberapa hasil yang dia temukan pada topik ini. Meskipun membuat kesan baik pada Clavius, Galileo gagal;kan ke keuntungan pengangkatan untuk matematika mengajar pada universitas Bologna.
Setelah meninggalkan Roma Galileo tinggal dengan Clavius oleh korespondensi dan Guidobaldo montase kelambatan juga wartawan reguler. Dalil pasti yang Galileo membuktikan memusat berat benda, dan kiri di roma, dibahas korespondensi ini. Itu juga mungkin yang Galileo mencatat acad diterima dari jalan yang mana memberi pada romawi kolektif, untuk dia menyalin membuat material seperti yang masih menyelamatkan hari ini. Mulai korespondensi sekitar 1588 dan melanjut untuk tahun baerikutnya. Juga pada 1588 Galileo diterima undangan bergengsi ke acad di ukuran dan tempat neraka di Dante Inferno pada akademi di Florence. Fantoni kiri kursi matematika pada universitas yang diambil di 1589 dan Galileo ditetapkan mengisi pos ( walaupun ini hanya kedudukan kata benda untuk mendukung finansial menyediakan untuk Galileo ). Tidak hanya lakukan dia menerima pujian kuat dari Clavius, tetapi dia juga peroleh terus reputasi ulung jabatan dosen nya pada Florence akademi di tahun sebelumnya. Ahli matematika yang diperoleh dengan cepat reputasi yang perlu seperti keuntungan kedudukan, tetapi disana masih kedudukan tinggi yang mana mungkin dia tuju. Galileo menghabiskan tiga tahun memegang posisi pada universitas Pisa dan selama waktu ini dia menulis De debu karangan rentetan di teori gerakan yang tak pernah dia terbitkan. Itu mungkin dia tak pernah menerbitkan materi ini sebab dia tak banyak mencukupi dengan itu, dan pekan raya ini untuk meskipun depan langkah-langkah penting berisi beberapa, itu juga gagasan tidak benar berisi beberapa. Barangkali paling penting gagasan baru De debu yang berisi satu dapat ujian theories dengan melaksanakan percobaan. Pada saat tertentu bekerja berisi gagasan penting nya yang satu dapat ujian theories tentang jatuh bodies menggunakan pesawat terbang menundukkan turun lambat ke tarip turun.
Di 1591 Vincenzo Galilei, bapaknya Galileo, meninggal dan sejak itu Galileo anak lelaki sulung tertua untuk dukung finansial menyediakan untuk beristirahat keluarga dan itu berarti finansial perlu untuk menyediakan dowries untuk perusahaan muda nya. Menjadi guru besar di Pisa tidak membayar baik, sangat Galileo dilihat untuk lebih menguntungkan. Dengan pujian kuat dari Guidobaldo montase kelambatan, Galileo ditetapkan guru besar matematika pada universitas Padua ( universitas republik Venice ) di 1592 dengan gaji tiga kalinya di Pisa. Pada 7 desember 1592 dia memberi acad upacara inaugurasi nya dan mulai periode tahun belas pada universitas, tahun yang mana kemudian dia uraikan sebagai bahagia dari hidup nya. Pada Padua tugas-tugas besarnya untuk mengajar ukurnya Euclid dan standar ( geosentris ) astronomi ke siswa medis, siapa akan memerlukan ke astronomi beberapa mengetahui di perintah untuk membuat menggunakan astrologi praktek medis mereka. Bagaimanapun, Galileo dibantah melawan melihatnya Aristotle astronomi dan filosofi natural tiga jabatan dosen publik dia memberi di hubungan dengan penampilan bintang baru ( sekarang mengenal sebagai 'Kepler's supernova' supernova' ) di 1604 . kepercayaan pada waktu ini yang Aristotle, yaitu yang semua perubahan di langit untuk terjadi di akhir region lunar untuk bumi, bidang bintang ditetapkan menjadi keriting permanent. Perbedaan pendapat Galileo paralaks digunakan untuk membuktikan bintang baru tidak dapat akhir untuk bumi. Di surat pribadi menulis untuk Kepler di 1598, Galileo menyatakan yang dia Copernican ( penganut di theories Copernicus ). Bagaimanapun, tanda publik ini bukan kepercayaan untuk sampai nampak banyak di tahun kemudian. Pada Padua, Galileo mulai hubungan masa panjang dengan gambit mariuwana, dari Venice, tetapi mereka tidak menikah barangkali sebab Galileo merasakan situasi finansial nya tidak cukup baik. Tahun 1600 anak pertama mereka lahir, diikuti oleh pucat kelabu anak perempuan kedua mengikuti di tahun berikutnya. Tahun 1606 anak lelaki mereka Vincenzo lahir yang diatas menyebutkan kesalahan di teorinya Galileo gerakan sebagai kumpulan luar di De debu sekitar 1590. Dia sungguh kesalahan kepercayaan nya yang kekuatan bertindak pada badan perbedaan sanak diantara berat spesifik nya dan zat yang mana itu memindahkan. Galileo menulis untuk teman nya Paolo Sarpi, ahli matematika consultor untuk pemerintah venesia, di 1604 dan itu bersih dari surat nya dengan ini waktu dia menyadari kesalahan nya. Di fakta dia kembalikan untuk bekerja di teori gerakan di 1602 dan mengikuti dua tahun lebih, terus dia belajar menundukkan pesawat terbang dan bandul, dia merumuskan hukum benar jatuh bodies dan bekerja luar yang proyektil mengikuti alur parabola. Bagaimanapun, hasil ini tidak akan terkenal dan diterbitkan 35 tahun kemudian.
Pada 1609, Galileo menerima surat dari Paolo Sarpi menceritakan teropong dia kira-kira yang belanda menunjukkan di Venice. Galileo menulis di pesuruh berbintang-bintang ( Sidereus Nuncius ) di april 1610:-
Tentang bulan sepuluh yang lalu laporan dicapai jarak pendengaran saya yang pasti Fleming membangun teropong oleh berarti yang mana object kelihatan, meskipun demikian sangat jauh dari mata peninjau, melihat jelas jika dekat. Efek ini sungguh-sungguh luar biasa berhubungan beberapa pengalaman, yang mana saat beberapa orang percaya yang lain menolak mereka kemudian hari sedikit laporan ditetapkan oleh surat saya menerima dari perancis di paris Jacques Badovere, yang menyebabkan saya menerapkan diriku wholeheartedly untuk berarti menyelidiki dengan yang mana saya mungkin tiba pada penemuan instrumen serupa. iIi saya lakukan segera sesudah itu, basis saya menjadi doktrin pembiasan.
Dari laporan ini, dan menggunakan kecakapan teknis milik nya sebagai ahli matematika dan sebagai ahli, Galileo mulai untuk membuat rentetan teleskop siapa performan dengan mata lebih banyak dari yang instrumen negri belanda. Teleskop pertama nya membuat dari tersedia lenses dan memberi perbesaran kira-kira empat kali. Untuk memperbaiki pada ini Galileo dipelajari bagaimana menggerinda dan menyemir lensa milik nya dan oleh augustus 1609 instrumen nya dengan perbesaran sekitar delapan atau sembilan. Galileo seketika melihat iklan dan aplikasi militer dari teleskop nya ( yang mana dia memanggil perspicillum ) untuk di laut. Dia menjaga Sarpi memberi tahu dari kemajuan nya dan Sarpi diatur demonstrasi untuk senat venesia. Mereka sangat mengesankan dan, sekembalinya untuk pertambahan besar gaji nya, Galileo memberi hak kaki untuk mempaberik teleskop untuk senat venesia. Itu nampak gerak baik bagian pada nya sejak dia harus mengenal hak yang seperti tak berarti, sekali sejak dia selalu mengakui teleskop tidak penemuan nya oleh akhir 1609 Galileo memutar teleskop nya di langit malam dan mulai untuk luar biasa membuat discoveries. Swerdlow tulis ( melihat [ 16 ] ) :- kira-kira dua bulan, desember dan januari, dia membuat lebih discoveries yang mengubah dunia dari seseorang pernah membuat sebelum atau sejak. astronomi discoveries dia membuat dengan teleskop nya uraikan di buku elec dipanggil pesuruh berbintang-bintang diterbitkan di Venice boleh 1610. ini bekerja disebabkan sensasi. Galileo diklaim mempunyai pegunungan melihat di bulan, telah dibuktikan jalan seperti susu membuat bintang kecil sekali , dan mempunyai melihat empat kecil bodies orbiting musytari . ini terakhir , dengan mata untuk menjadi kedudukan di Florence , dia cepat dinamakan 'the Medicean stars' . dia juga mengirim Cosimo de dokter , adipati besar Tuscany , teleskop ulung untuk dirinya
senat venesia , barangkali menyadari yang hak untuk teleskop mempaberik yang Galileo memberi mereka tidak berharga , membekukan gaji nya . bagaimanapun dia berhasil;menggantikan dalam mengesankan Cosimo dan , di bulan juni 1610 , hanya bulan setelah buku sedikit terkenal nya diterbitkan , Galileo berhenti pos nya pada Padua dan ahli matematika kepala menjadi pada universitas yang diambil ( apa saja tanpa tugas-tugas mengajar ) dan 'Mathematician dan Philosopher' untuk adipati besar Tuscany . di 1611 dia roma mengunjungi di mana dia perlakukan sebagai kemasyuran memimpin romawi kolektif menaruh pada makan malam besar dengan speeches ke menghormati luar biasanya Galileo discoveries . dia juga membuat anggota Accademia melumerkam Lincei ( di fakta anggota keenam ) dan ini menghormati yang mana penting terutama untuk Galileo yang menandatangani dirinya 'Galileo Galilei Linceo' dari ini waktu pada . saat di roma , dan setelah kembalinya nya untuk Florence , Galileo dilanjut untuk pengamatan membuat dengan teleskop nya . di pesuruh berbintang-bintang dia periode rough memberi empat batu-bulan musytari , tetapi lebih perhitungkan tepat pasti tidak gampang sejak itu sukar ke mengidentifikas dari pengamatan yang mana bulan saya , yang mana II , yang mana III , dan yang mana IV . dia membuat rentetan panjang pengamatan dan dapat untuk periode teliti memberi oleh 1612 . pada satu panggung di perhitungkan dia menjadi sangat membingungkan sejak data dia merekam tidak konsekwen nampak , tetapi dia melupakan untuk mengambil ke dalam account gerakan ronde bumi matahari . Galileo pertama diputar teleskop nya di zohal pada 25 bulan juli 1610 dan itu nampak sebagai tiga bodies ( teleskop nya tidak cukup baik untuk menunjukan pinggir gelanggang tetapi membuat mereka nampak sebagai cuping pada manapun sisi planit ) . pengamatan dilanjut membingungkan tentu saja untuk Galileo sebagai bodies pada manapun sisi zohal lenyap ketika sistim cincin tepi pada . juga di 1610 dia menemukan yang , ketika melihat di teleskop , bintang johar planit seperti tahap ditunjukkan itu bulan , dan karena itu harus orbit matahari tidak bumi . ini lakukan tidak memungkinkan satu untuk menentukan diantara Copernican sistim , yang mana segalanya pergi ronde matahari , dan yang mengusulkan oleh Tycho Brahe yang mana segalanya tetapi bumi ( dan bulan ) pergi ronde matahari yang mana di giliran pergi ronde bumi . banyak ahli astronomi waktu di fakta disokong sistimnya Brahe dan tentu saja pembeda diantara dua oleh percobaan melebihi instrumen hari . bagaimanapun , Galileo mengenal yang semua nya fakta-fakta untuk Copernicanism , walaupun tidak bukti . di fakta itu teori nya jatuh bodies yang mana paling penting ini rasa hormat , untuk lawan bumi bergerak dibantah itu jika bumi berputar dan badan diteteskan dari menara itu harus di belakang jatuh menara sebagai bumi saat berputar itu menebang . sejak ini tidak mengamati di praktek ini mengambil sebagai fakta-fakta kuat yang bumi tak . bagaimanapun Galileo mengenal yang badan akan jatuh di cara diamati pada bumi berputar
yang lain pengamatan membuat oleh Galileo dicakup pengamatan pada matahari . dia melaporkan ini di pidato pada mengapung bodies yang mana dia menerbitkan di 1612 dan lebih penuh di surat di pada matahari yang mana nampak di 1613 . di tahun mengikuti anak perempuan nya masuk biara fransiskan St Matthew sebelah luar Florence , keperawanan mengambil surgawi mariuwana saudara perempuan nama dan pucat kelabu saudara perempuan nama Arcangela . sejak mereka sebelah luar lahir perkawinan , Galileo percaya yang mereka diri mereka semua harus tak pernah menikah . walaupun Galileo depan menaruh banyak benar revolusioner theories , dia tidak benar semua kasus . di tertentu ketika tiga bintang berekor nampak di 1618 dia menjadi dilibatkan di kontroversi mengenai alami bintang berekor . dia membantah yang mereka akhir untuk bumi dan menyebabkan oleh pembiasan dengan mata . akibat serius ini perbedaan pendapat sial yang Jesuits mulai untuk melihat Galileo sebagai lawan berbahaya . meskipun dukung mil nya untuk Copernicanism , Galileo dicoba menghindari kontroversi oleh tidak pernyataan publik membuat di isu . bagaimanapun dia menggambar ke dalam terus kontroversi dibentengi meriam siapa ditetapkan untuk kursi matematika di yang diambil di 1613 . dibentengi meriam seperti siswa Galileo's dan dan dia juga pendukung Copernicus . pada bertemu di istana dokter di Florence di desember 1613 dengan adipati besar Cosimo II dan ibu nya pengikut kristus duchess besar Lorraine , dibentengi meriam diminta untuk menjelaskan kontradiksi nyata diantara Copernican teori dan kitab injil suci . dibentengi meriam dipertahankan Copernican penuh semangat kedudukan dan wrote untuk Galileo sesudah itu menceritakan dia bagaimana berhasil dia dalam meletakkan perbedaan pendapat . Galileo , tak sebanyak diyakinkan yang berbenteng meriam menang perbedaan pendapat , surat wrote untuk berbenteng meriam kepada dia membantah yang kitab ditafsirkan di cahaya apa ilmu pengetahuan menunjukkan benar . Galileo beberapa lawan di Florence dan mereka pasti membuat yang mengcopy surat untuk berbenteng meriam mengirim untuk penyelidikan di roma . bagaimanapun , setelah menguji muatan nya mereka sedikit menemukan yang mana mereka dapat benda
catholic Church's paling penting bentuk badan pada ini waktu dalam berhadapan dengan penafsiran kitab injil suci rel Robert Bellarmine . dia nampak pada ini waktu mempunyai sebab sedikit melihat untuk gereja terkait mengenai Copernican teori . di isu apakah Copernicus sederhana depan menaruh mathematical teori yang mana memungkinkan perhitungkan kedudukan amat menyenangkan bodies membuat lebih sederhana atau apakah dia mengusulkan kenyataan pemeriksaan badan . pada ini waktu Bellarmine dipandang teori sebagai molek mathematical satu yang mana lakukan tidak mengancam kepercayaan orang kristen didirikan mengenai struktur dunia . di 1616 Galileo wrote surat untuk duchess besar yang mana penuh semangat diserang para pengikut Aristotle . ini bekerja , yang mana dia menujukan untuk pengikut kristus duchess besar Lorraine , dia betul-betul membantah untuk non-literal penafsiran kitab injil suci ketika penafsiran harfiah akan fakta menyangkal kira-kira dunia pemeriksaan badan dibuktikan oleh mathematical ilmu pengetahuan . ini Galileo dinyatakan sungguh jelas yang untuk dia Copernican teori tidak hanya mathematical alat menghitung , tetapi pemeriksaan badan reality:- saya menjaga yang matahari ditempatkan pada memusat putaran bola amat menyenangkan dan mengerjakan tidak tempat perubahan , dan yang bumi berputar pada dirinya dan bergerak sekitar itu . selain itu .. . saya mengkonfirmasikan ini melihat tidak hanya dengan menyangkal Ptolemy's dan dan perbedaan pendapatnya Aristotle , tetapi juga dengan memproduksi banyak untuk yang lain sisi , beberapa terutama menyinggung ke efek pemeriksaan badan siapa sebabkan barangkali bisa ditentukan apa saja yang lain jalan , dan yang lain astronomi discoveries; ini discoveries jelas menyangkal Ptolemaic sistim , dan mereka dgn mengagumkan setuju dengan ini yang lain kedudukan dan mengkonfirmasikan it.
kekurangan paus V perintah Bellarmine rel suci index menentukan di Copernican teori . rel jumpa penyelidikan pada 24 pebruari 1616 dan fakta-fakta mengambil dari ahli mengenai agama . mereka mengutuk mengajar Copernicus , dan Bellarmine disampaikan keputusan mereka untuk Galileo siapa tidak pribadi dilibatkan di pemeriksaan pengadilan . Galileo melarang ke menjaga Copernican melihat tetapi peristiwa kemudian membuat dia tak sebanyak terkait tentang ini keputusan penyelidikan . paling sangat Maffeo Barberini , siapa pengagum Galileo , dipilih sebagai dengan kota paus VIII . ini terjadi hanya sebagai bukunya Galileo Il saggiatore ( kir ) tentang diterbitkan oleh Accademia melumerkam Lincei di 1623 dan Galileo cepat untuk mempersembahkan ini bekerja untuk paus baru . bekerja uraikan metode ilmiah barunya Galileo dan berisi kutipan terkenal mengenai mathematics:- filosofi menulis ini buku besar , dunia , yang mana terus menerus perhentian membuka untuk pandangan kita . tetapi bisa buku kecuali jika memahami satu pertama belajar untuk memahami bahasa dan membaca karakter yang mana itu menulis . itu menulis di bahasa matematika , dan karakter nya segitiga , lingkaran , dan yang lain tanpa skate indah geometris yang mana itu mustahil kemanusiaan untuk memahami kata single it; tanpa ini satu mengembara di labirin kegelapan
dengan kota paus VIII diundang Galileo ke pendengar dengan paus saat di enam dan memimpin Galileo untuk percaya yang gereja catholic akan tidak membuat isu Copernican teori . Galileo , karena itu , diputuskan ke menerbitkan melihat nya percaya yang dia dapat melakukan sangat konsekwensi-kon serius tanpa dari gereja . bagaimanapun dengan ini panggung hidup nya kesehatannya Galileo miskin dengan pertandingan sering sakitnya keras dan sangat bahkan meskipun demikian dia mulai untuk tulis dialog terkenal nya di 1624 itu mengambil dia tahun enam ke lengkap bekerja . Galileo dicoba untuk izin mendapat dari roma ke menerbitkan dialog di 1630 tetapi ini lakukan tidak gampang membuktikan . secepatnya dia izin menerima dari Florence , dan tidak roma . pebruari 1632 Galileo dialog diterbitkan mengenai dua sistem kepala dunia - Ptolemaic dan Copernican . itu mengambil bentuk dialog diantara Salviati , yang memperdebatkan untuk Copernican sistim , dan kesederhanaan siapa Aristotelian filsuf . klimaks buku perbedaan pendapat oleh Salviati yang bumi bergerak yang mana berdasarkan teorinya pada Galileo pasang . teorinya Galileo pasang meskipun palsu seluruhnya menjadi didalilkan setelah Kepler depan menaruh keterangan benar . itu sial , memberi kebenaran luar biasa dialog didukung , yang perbedaan pendapat yang mana Galileo pikiran untuk memberi bukti kuat teorinya Copernicus harus tidak benar
segera setelah penerbitan dialog mengenai dua sistem kepala dunia - Ptolemaic dan Copernican penyelidikan dilarang penjualan nya dan memerintah Galileo untuk nampak di roma sebelum mereka . sakitnya dicegah dia dari bepergian ke sampai roma 1633 . tuduhannya Galileo pada pemeriksaan pengadilan yang mana mengikuti yang dia melanggar turun meletakkan kondisi-kondisi oleh penyelidikan di 1616 . bagaimanapun versi beda ini keputusan diproduksi pada pemeriksaan pengadilan agak dari satu Galileo memberi pada waktu . kebenaran Copernican teori tidak karena itu isu itu mengambil sebagai fakta pada pemeriksaan pengadilan yang ini teori palsu . ini logis , jalan , sejak seperti penghakiman 1616 mengumumkan itu palsu total . bersalah menemukan , Galileo dikutuk ke hukuman penjara kekal , tetapi gram dibawa luar penuh simpati banyak dan itu amounted ke penangkapan rumah agak dari gram penjara . dia dapat ke pertama yang hidup dengan uskup besar Siena , kemudian kemudian ke kembalinya untuk rumah nya di Arcetri , dekat Florence , tetapi untuk membelanjakan beristirahat dari hidup nya lebih diamati oleh petugas dari penyelidikan . di 1634 dia menderita pukulan keras ketika keperawanan anak perempuan nya , surgawi mariuwana saudara perempuan , meninggal . dia dukung besar kepada dia terus bapak penyakit nya dan Galileo dihancurkan dan dapat tidak bekerja untuk banyak bulan . ketika dia lakukan mengatur untuk merestart bekerja , dia mulai untuk pidato tulis dan mathematical demonstrasi mengenai dua ilmu pengetahuan baru . setelah Galileo menyelesaikan bekerja di pidato itu diselundupkan luar itali , dan mengambil ke leyden di negeri belanda di mana itu diterbitkan . itu nya keras mathematical bekerja yang mana masalah perlakukan di daya pendorong , sesaat , dan memusat berat . banyak ini kembali pergi bekerja untuk gagasan tak diterbitkan di De debu dari sekitar 1590 dan perbaikan yang mana dia bekerja luar selama 1602-1604 . di pidato dia mengembangkan gagasan nya pesawat terbang ditundukkan writing:-
saya mengasumsikan yang yang diperoleh kecepatan oleh kecenderungan beda lebih benda dapat digerakkan sama pesawat terbang sama sewaktu-waktu kemuliaan itu pesawat terbang sama . dia kemudian uraikan percobaan menggunakan bandul ke memverifikasi properti nya pesawat terbang menundukkan dan menggunakan ini gagasan untuk memberi dalil di percepatan bodies bebas fall:- waktu yang mana jarak pasti dilintasi oleh benda percepatan pakaian seragam bawah bergerak dari beristirahat sama untuk waktu yang mana jarak sama akan dilintasi oleh benda dapat digerakkan sama bergerak pada kecepatan pakaian seragam dari satu separuh maksimum dan kecepatan akhir gerakan percepatan berpakaian seragam sebelum . setelah hasil lebih lanjut memberi ini tipe dia memberi hasil terkenal nya yang jarak yang badan bergerak dari percepatan pakaian seragam bawah beristirahat sebanding untuk segi empat mengambil waktu . satu akan mengharapkan yang Galileo's pemahaman bandul , yang mana dia sejak dia lelaki anak , akan telah dipimpin dia ke desain jam bandul . di fakta dia hanya nampak mempunyai pikiran ini dekat kemungkinan akhir dari hidup nya dan sekitar 1640 dia desain lakukan jam bandul pertama. Galileo meninggal awal 1642 tetapi arti dari desain jam nya pasti disadari dengan anak lelaki nya Vincenzo yang mencoba untuk membuat jam untuk Galileo's merencanakan, tetapi gagalkan. itu akhir sedih untuk sangat besar lelaki ke mati dikutuk bidaah. tandai nya yang dia ingin dikuburkan disamping bapak nya di kuburan keluarga di basilika sinterklas mengait tetapi keluarga nya ditakutkan, sungguh pada tempatnya , yang ini akan perlawanan menimbulkan dari gereja . badan nya sembunyi dan hanya ditempatkan di kuburan denda di gereja di 1737 oleh sipil authorities melawan mengharap banyak di gereja . pada 31 bulan oktober 1992 , 350 tahun setelah kematiannya Galileo , paus johnny kekurangan II memberi alamat di kepentingan gereja catholic yang mana dia telah diakui itu kesalahan membuat oleh penasehat mengenai agama di kasus Galileo . dia mengumumkan Galileo kasus ditutup , tetapi dia lakukan tidak mengakui yang gereja kesalahan ke narapidana Galileo pada ongkos bidaah sebab dari kepercayaan nya yang bumi ronde berputar matahari.

artikel oleh : J J O'Connor dan E F Robertson