Galileo Galilei

Galileo Galilei . Italian physicist and astronomer , champion of the scientific conception of the world. He criticized the blind admiration of the authority of Aristotle , dogmatic scholasticism . The main results obtained by Galileo in mechanics were the establishment of the law of inertia and the principle of relativity , according to which the uniform and rectilinear movement of a system of bodies is not reflected in the processes that occur in said system. Such discoveries reduced the sterile scholastic physics to nothing and opened the way to the experimental science of modern times. ^[1]

Of capital importance for the fight against religious dogmas were the astronomical discoveries of Galileo, which served as decisive arguments in favor of the heliocentric system of Copernicus . Pressured by the Inquisition , Galileo was forced to recant the “Copernican heresy.” His conception of the world was also progressive. ^[1]

Galileo considered that the world is infinite; matter , eternal, and nature , one. At the basis of nature is a rigorous mechanical causality of absolutely invariable atoms , subject to the laws of mechanics. The starting point of knowledge of nature is observation, experience. Knowledge of the internal necessity of phenomena is, according to Galileo, the highest degree of knowledge. However, Galileo did not free himself from religious prejudices, he admitted the first impulse given by God . His main work is the Dialogue on the two maximum systems of the world: the Ptolemaic and the Copernican ( 1632 ). ^[1]

Summary

[ disguise ]

• 1 Biographical summary
  • 1 Academic youth
  • 2 Death
• 2 The message from the stars
• 3 The battle of Copernicanism
• 4 Contributions
• 5 References
• 6 Sources

Biographical summary

Born in Pisa on February 15 , 1564 . The little that, through some letters, is known about his mother, Giulia

Ammannati di Pescia, does not paint a very flattering figure of her. Her father, Vincenzo Galilei, was Florentine and came from a family that had long been illustrious; A musician by vocation, economic difficulties had forced him to dedicate himself to commerce, a profession that led him to settle in Pisa.

A man of broad humanist culture, he was an accomplished performer and a composer and music theorist, whose works on the subject enjoyed a certain fame at the time. From him Galileo had to inherit not only the taste for music, he played the lute, but also the independent character and the combative spirit, and perhaps even the contempt for blind trust in authority and the taste for combining theory with practice.

Galileo was the first-born of seven siblings, three of whom, Virginia, Michelangelo and Livia, had to contribute, over time, to increasing his economic problems. In 1574 the family moved to Florence and Galileo was sent for a time to the monastery of Santa Maria di Vallombrosa, as a student or perhaps as a novice.

Academic youth

In 1581 Galileo entered the University of Pisa , where he enrolled as a medical student at the will of his father. Four years later, however, he left the university without having obtained any degree, although with a good knowledge of Aristotle. Meanwhile, a determining event had occurred in his life: his initiation into mathematics, outside of his university studies, and the consequent loss of interest in his career as a doctor.

Back in Florence (Italy) in 1585 , Galileo spent a few years dedicated to the study of mathematics, although he was also interested in philosophy and literature in which he showed his preferences for Ariosto over Tasso ; From that time dates his first work on the center of gravity of bodies, which he would later recover, in 1638 , as an appendix to what would become his main scientific work, and the invention of a hydrostatic balance for the determination of specific weights, two contributions. located in the line of Archimedes , whom Galileo would not hesitate to describe as superhuman.

After giving some private mathematics classes in Florence and Siena , he tried to obtain regular employment at the universities of Bologna , Papua and in Florence itself. In 1589 he finally obtained a place at the Study of Pisa, where his discontent with the very poor salary he received could not help but be revealed in a satirical poem against academic dress.

In Pisa Galileo composed a text on movement, which he kept unpublished, in which, still within the framework of medieval mechanics, he criticized the Aristotelian explanations of the fall of bodies and the movement of projectiles; In continuity with this criticism, a certain historiographic tradition has forged the anecdote that is generally considered implausible, of Galileo materially refuting Aristotle through the procedure of throwing different weights from the top of the Campanile, before the disgruntled gaze of the Peripatetics.

In 1591 , the death of his father meant that Galileo had to take responsibility for his family and take care of his sister Virginia’s dowry. Thus began a series of economic difficulties that would only worsen in the following years; In 1601 he had to provide for his sister Livia’s dowry without the collaboration of his brother Michelangelo, who had gone to Poland with money that Galileo had lent him and which he never returned. On the contrary, he later settled in Germany , thanks to again to the help of his brother, and then sent his entire family to live with him.

The need for money at that time was increased by the birth of Galileo’s own three children: Virginia 1600 , Livia 1601 and Vincenzo 1606 , from his union with Marina Gamba, which lasted from 1599 to 1610 and with whom he did not reach a marriage. get marry.

All of this made the small improvement achieved by Galileo in his remuneration when he was elected, in 1592 , to the chair of mathematics at the University of Padua by the Venetian authorities that ran it, insufficient. He had to resort to private classes, advances and even loans. Despite everything, Galileo’s stay in Padua, which lasted until 1610, constituted the most creative, intense and even happy period of his life.

In Padua Galileo had the opportunity to deal with technical issues such as military architecture, castrametation, topography and other related topics that he dealt with in his private classes. Various inventions also date from then, such as a machine for raising water, a thermoscope and a mechanical calculation procedure that he presented in his first printed work: Le operazioni del compasso geometrico e militare, 1606 .

Initially designed to solve a practical artillery problem, the instrument was soon perfected by Galileo, who expanded its use to solve many other problems. The usefulness of the device, at a time when logarithms had not yet been introduced, allowed him to earn some income through its manufacture and marketing.

In 1602 Galileo resumed his studies on movement, dealing with the isochronism of the pendulum and the movement along an inclined plane, with the aim of establishing the law of fall of the bass. It was then, and until 1609 , when he developed the ideas that thirty years later would constitute the core of his Discorsi.

Death

Galileo remained until his death, on January 8 , 1642 , in his villa in Arcetri, near Florence , under house arrest. At first he couldn’t receive visitors. There he managed to complete the last and most important of his works: the Discorsi e dimostrazioni matematiche intorno à due nine scienze, published in Leyden by Luis Elzevir in 1638 .

In it, starting from the discussion on the structure and resistance of materials, Galileo laid the physical and mathematical bases for an analysis of movement, which allowed him to demonstrate the laws of fall of bass in a vacuum and develop a complete theory of projectile firing.

The work was destined to become the cornerstone of the science of mechanics built by scientists of the next generation, with Newton at the helm. His last years were very bitter because he was also completely blind.

The message of the stars

In July 1609 , visiting Venice to request a salary increase, Galileo learned of a new optical instrument that

a Dutchman had introduced Prince Maurice of Nassau ; It was the telescope, whose practical importance Galileo immediately grasped, dedicating his efforts to improving it until it became a true telescope.

Although he declared that he had managed to perfect the device thanks to theoretical considerations about the optical principles that were its foundation, it is most likely that he did so through successive practical attempts that, at most, were based on some very summary reasoning.
Be that as it may, his undeniable merit lay in the fact that he was the first to succeed in extracting decisive scientific benefit from the device.

Indeed, between December 1609 and January 1610 Galileo made the first observations of the Moon with his telescope , interpreting what he saw as proof of the existence on the satellite of mountains and craters that demonstrated its community of nature with the Earth; The traditional Aristotelian theses about the perfection of the celestial world, which required the complete sphericity of the stars, were called into question.

The discovery of four satellites of Jupiter contradicted, for its part, the principle that the Earth had to be the center of all movements that occurred in the sky. As for the fact that Venus presented phases similar to the lunar ones, which Galileo observed at the end of 1610 , it seemed to him that it provided empirical confirmation of Copernicus ‘s heliocentric system , since this, and not Ptolemy ‘s , was in a position to provide an explanation for the phenomenon.

Eager to make his discoveries known, Galileo hurriedly wrote a short text that was published in March 1610 and that soon made him famous throughout Europe : the Sidereus Nuncius, the sidereal messenger or messenger of the stars, although the title It also allows the translation of the message, which is the meaning that Galileo, years later, said he had in mind when he was criticized for the arrogance of claiming the status of celestial ambassador.

The book was dedicated to the Grand Duke of Tuscany Cosimo II de’ Medici and, in his honour, the satellites of Jupiter were called Medicean planets there. With this, Galileo secured his appointment as mathematician and philosopher of the Tuscan court and the possibility of returning to Florence, for which he had been fighting for several years.

The job included an honorary professorship in Pisa, without teaching obligations, which fulfilled a long-held hope and made him prefer an absolute monarch to a republic like the Venetian one, since, as he himself wrote, it is impossible to obtain any payment of a republic, however splendid and generous it may be, that does not entail any obligation; since, to get something from the public, you have to satisfy the public.

The battle of Copernicanism

In 1611 a German Jesuit, Christof Scheiner , had observed sunspots and published a book about them under a pseudonym.

Galileo before the court of the Holy Inquisition

the same. Around the same time Galileo, who had already observed them before, had them seen by various people during his stay in Rome , on the occasion of a trip that was described as triumphant and that served, among other things, for Federico Cesi to make him member of the Accademia dei Lincei which he had founded in 1603 and which was the first scientific society of lasting importance.

Under its auspices, the Istoria e dimostrazione interna alle macchie solari was published in 1613 , where Galileo challenged Scheiner’s interpretation, who claimed that the spots were a phenomenon extrapolating stars close to the Sun , which were interposed between it and the Earth. The text unleashed a controversy about the priority in the discovery, which lasted for years and made the Jesuit one of Galileo’s most bitter enemies, which did not fail to have consequences on the process that the Inquisition was to follow.

Furthermore, it was there that, for the first and only time, Galileo gave to the printing press unequivocal proof of his adherence to Copernican astronomy, which he had already communicated in a letter to Kepler in 1597 . Faced with the attacks of his academic adversaries and the first signs that his opinions could have conflicting consequences with ecclesiastical authority, the position adopted by Galileo was to defend in a letter addressed in mid-1615 to Christina of Lorraine that, while admitting that There could be no contradiction between the Holy Scriptures and science, it was necessary to establish the absolute independence between the Catholic faith and scientific facts.

Now, as Cardinal Bellarmino noted, it could not be said that there was conclusive scientific proof in favor of the movement of the Earth, which, on the other hand, was in contradiction with biblical teachings; Consequently, the Copernican system could only be understood as hypothetical. In this sense, the Holy Office condemned the Copernican system on February 23 , 1616 as false and opposed to the Holy Scriptures, and Galileo received the admonition not to publicly teach Copernicus’ theories.

Galileo, aware that he did not have the proof that Bellarmino claimed, even though his astronomical discoveries left him no doubt about the truth of Copernicanism, took refuge for a few years in Florence in the calculation of some tables of the movements of the satellites. of Jupiter, with the aim of establishing a new method for calculating longitudes on the high seas, a method that he tried in vain to sell to the Spanish and Dutch governments.

In 1618 he was involved in a new controversy with another Jesuit, Orazio Grassi , regarding the nature of comets, which resulted in a text, Il Saggiatore 1623 , rich in reflections on the nature of science and the scientific method. , which contains his famous idea that “the Book of Nature is written in mathematical language.” The work, published by the Accademia dei Lincei, was dedicated by it to the new Pope Urban VIII , that is, Cardinal Maffeo Barberini, whose election as pontiff filled the cultured world in general with joy and, in particular, Galileo, whom the cardinal had already shown his affection.

The new situation encouraged Galileo to write the great exposition work of Copernican cosmology that he had already announced in 1610: the Dialogo sopra i due massimi sistemi del mondo, tolemaico e copernicano; In it, the Aristotelian points of view defended by Simplicio were confronted with those of the new astronomy advocated by Salviati, in the form of a dialogue moderated by Sagredo’s bona mens.

Although the work failed in its attempt to live up to the demands expressed by Bellarmino, since it provided, as proof of the movement of the Earth, a false explanation of the tides, Simplicio’s inferiority to Salviati was so manifest that the Saint Oficio did not hesitate to open a process against Galileo, even though he had obtained an imprimatur to publish the book in 1632 . Begun on April 12 , 1633 , the process ended with a sentence of life imprisonment, despite Galileo’s refusal to defend himself and his formal recantation. The sentence was softened by allowing him to serve it in his country house in Arcetri.

Contributions

The contributions made by Galileo have served many other scientists as a basis for their research, among them we can mention:
Physics
He made notable scientific contributions in the field of physics, which called into question theories considered true for centuries. Thus, for example, he demonstrated the falsity of the Aristotelian postulate that the acceleration of the fall of bodies in free fall was proportional to their weight, and he conjectured that, in a vacuum, all bodies would fall with equal speed. To do this, he made spheres slide down the smooth surface of inclined planes with different angles of inclination, and it was not by launching bodies of different weights from the leaning tower of Pisa, as had been believed for a long time. <

Among other notable discoveries are the laws of pendulum motion, about which he began to think, according to the well-known anecdote, while observing a lamp that oscillated in the cathedral of Pisa, and the laws of accelerated motion.

Astronomy
His contributions in the field of astronomy and the study of the universe were no less important. At the beginning of the 17th century, he perfected the spyglass, a newly invented optical instrument, to obtain a sixty-fold telescope.
With the help of this device, Galileo explored the sky and reached conclusions that profoundly revolutionized the way we understand the order of the universe.

Contrary to general belief, he demonstrated that the surface of the Moon was not crystalline, but was covered with craters and mountains, thereby refuting the Aristotelian idea of ​​the absolute perfection of the stars. In the same way, he discovered sunspots, with which he was able to determine the period of the Sun’s rotation and the direction of its axis. Galileo also discovered the four largest satellites of Jupiter and demonstrated that not all the stars revolved around the Earth. This confirmation of Copernican theories, contrary to Ptolemy’s cosmology in force until then, earned him condemnation from the ecclesiastical authorities, but it played a fundamental role in building the modern vision of the universe.

Scientific methodology
Galileo can be considered the founder of modern astronomy, and more generally, as the introducer of the experimental method in scientific research. In addition to his extraordinary results as a physicist and astronomer, Galileo’s importance lies precisely in having created a new scientific mentality, the foundations of which are still current.

For these reasons, Galileo can be considered the founder of modern science, based on the observation of facts, the performance of experiments and the formulation of explanatory theories. In the history of culture, Galileo has become the symbol of the fight against authority and freedom in research.