The contributions of the founder of experimental physics to science have propelled human progress, but they came at a personal cost of repression. The ruling church perceived the scientist’s stance as a threat to the established order and a challenge to its spiritual monopoly. This was a clash between authority and a bearer of knowledge who dared to oppose the powers that be with an independent mind.
Personal Development
Ironically, the active proponent of the heliocentric system, which led him into conflict with the Catholic Church, had initially intended to become a priest. A man who believed that “one should measure the measurable and make measurable what is not,” received his early education at the Vallombrosa monastery. From a young age, the novice of the monastic order showed a strong inclination towards knowledge and was one of the best students in his class. The future Italian physicist, mechanic, astronomer, mathematician, and philosopher had tied his life plans to the church, and it was only his father’s objections that made the scion of a family of priors (members of the ruling council of the Florentine Republic) reconsider.
The eldest of six children (two girls and two boys survived), Vincenzo Galilei was born on February 15, 1564, in the ancient city of Pisa. Galileo Galilei belonged to a family of impoverished Italian aristocrats, among whom was even a popularly elected head of the republic in 1445—his famous great-great-grandfather was also named Galileo Galilei and was a physician by profession.
The father of the future “revolutionary in physical science” was mentioned in documents as a lutenist and music theorist. Galileo’s younger brother, Michelangelo, also became a lutenist. The family’s move to the capital of the Duchy of Tuscany in 1572 helped the talented children develop in secular pursuits: Florence was then ruled by the Medici dynasty, known for its patronage of science and the arts.
From childhood, Galileo was passionate about music and drawing, mastering both talents with great skill. In matters of perspective and composition, even renowned Florentine artists like Bronzino and Cigoli consulted him (the latter credited Galileo for his own fame). At the same time, Galileo’s written works revealed a remarkable literary talent. His creative abilities contributed to the breadth of his scientific inquiries, aiding in the complex analysis of phenomena, the formation of independent judgments, and the acquisition of persuasive skills.
Introduction to Mathematics
At his father’s insistence, in 1581, the 17-year-old Galileo began studying medicine at the University of Pisa, but unexpectedly found a more intriguing discipline—geometry. He was introduced to this subject in lectures by Ostilio Ricci and discovered the previously unfamiliar science of mathematics. While simultaneously studying ancient philosophy, the student learned to manipulate measurements and assumptions, earning a reputation as an insatiable debater for whom truth was more important than authority. It is believed that even then, Galileo may have become fascinated by Copernican theory, as astronomy was actively discussed against the backdrop of calendar reform.
The Old Building of the University of Pisa
Unfortunately, the opportunity for education directly depended on his father’s financial capability. The family funds were only sufficient for three years, and Galileo had to return home without a degree: the university administration refused to waive tuition for the gifted student. However, on the side of the constructor of hydrostatic balances and several other useful inventions stood the educated patron, Marquis Guidobaldo del Monte, about whom Galileo wrote that the world had not known such a genius since Archimedes. Thanks to the patronage of this new acquaintance, the promising scientist made a significant contribution to science, securing a paid position as a researcher through the personal intervention of the Tuscan Duke Ferdinand I de’ Medici.
In 1589, Galileo returned to the University of Pisa as a professor of mathematics, and in his first year of independent mathematical and mechanical experiments, he published the scientific treatise “On Motion.” After his father’s death, the responsibility for the well-being of his brother and sisters fell on the eldest son, which strengthened Galileo’s sense of responsibility and determination to achieve his goals. The next step in his career came in 1592 when he was appointed a lecturer in astronomy, mechanics, and mathematics in the Venetian Republic: Galileo began working at the prestigious University of Padua. A recommendation from the Venetian Doge attested to the high scientific authority of the young scholar even at that time.
Challenging Traditions
His professorship in Padua became the most fruitful period of scientific achievements for Galileo. He earned the respect of students and the government, which regularly entrusted him with new technical developments. The author of the treatise “Mechanics” corresponded with prominent scientists of the time, including a follower of Kepler. In 1604, however, the professor received his first denunciation to the Inquisition, accused of reading forbidden literature and studying astrology. Only the personal sympathy of the Padua inquisitor, Cesare Lippi, saved Galileo from early persecution.
Galileo’s Last Work on the Foundations of Mechanics
The scientist continued to pursue what interested him: a series of astronomy lectures was spurred by the discovery of the so-called Kepler’s Supernova in 1604. Learning that a telescope had been invented in Holland, Galileo constructed his own telescope for studying celestial bodies based on the same principle. With this new instrument, he distinguished the stars of the Milky Way, observed sunspots, recognized the lunar landscape, identified Jupiter’s moons, and was the first to suspect the existence of external rings around Saturn.
Galileo’s telescopic images were so astonishing that even a century later, many refused to believe in the reality of his discoveries, considering what the scientist saw to be an illusion. After describing his findings in the 1610 publication “Starry Messenger,” Galileo received orders for his “wonder of technology” from European royalty and gifted telescopes to Venetian senators, who rewarded him with a lifetime professorship, assigning him a generous salary of 1,000 florins. Galileo became a European sensation: panegyrists compared the scientist to Columbus. Only astrologers and physicians expressed dissent, deeming the new discoveries “damaging” to the integrity of their methods.
Galileo’s Telescopes “cannocchiali” in the Galileo Museum in Florence
“Escalation of Heresy”
For the debunker of Aristotelian metaphysics, the fateful step was moving in 1610 from tranquil Venice, where the Inquisition was not rampant, to Florence. This decision was preceded by changes in Galileo’s personal life. The successful experimenter united his fate with the Venetian Marina Gamba and became, in this civil marriage without a wedding, the father of three children, whom he named after his father and sisters—Vincenzo (the son was legitimized in 1619), Virginia, and Livia (the daughters later lived in a convent). In need of funds to support his family, Galileo agreed to take the lucrative position promised by Duke Cosimo II de’ Medici as an advisor at the Tuscan court. The son of Ferdinand I kept his promise, allowing Galileo to settle his debts that had accumulated after marrying off his sisters: he provided each with a respectable dowry. Meanwhile, the scientist’s court duties were not burdensome: he simply taught the nobleman’s sons, formally remaining a professor at the University of Pisa without the need to lecture students.
Continuing his research, the founder of experimental physics and the father of classical mechanics discovered the phases of Venus and the rotation of the Sun around its axis. His bold and polemical manner of presenting his achievements and priorities earned Galileo numerous adversaries in the academic community and among the Jesuits. His defense of officially condemned Copernicanism particularly outraged his enemies. An influential figure in science, he fearlessly promoted the heliocentric system of the universe, defending the theory of Earth’s rotation, which contradicted the Psalms.
Galileo Shows the Telescope to the Venetian Doge (Fresco by Giuseppe Bertini, 1858)
Armed with evidence for this conclusion, at the height of his scientific fame, Galileo traveled to the capital in 1611 to convince the Pope that Copernicanism was not contrary to Catholicism. His small victory at the meeting with Paul V was the verdict of a commission of cardinals regarding the use of the telescope: at that time, the question was seriously discussed whether it was sinful to look at the sky through a telescope. Encouraged by such support, Galileo declared two years later that Scripture pertains only to matters of saving souls and cannot be an authority in scientific questions: “No postulate of Scripture has such compelling force as natural phenomena.” In 1613, Galileo published his book “Letters on Sunspots,” where he openly expressed support for Copernicanism.
Debating the Inquisition
In February 1615, the Roman Inquisition could no longer turn a blind eye to the “heretical views” of the Italian scientist: the first case against Galileo was initiated. This was prompted by the “brazen” call of the professor to the Roman authorities to clarify their final stance on Copernicanism. This mistake pushed the Catholic Church to accuse Galileo of heresy. This occurred against the backdrop of the successes of the Reformation, which alarmed the Catholic elite, who saw a threat to their spiritual monopoly. Theologians explained that accepting Copernicanism as an acceptable mathematical model would undermine the Church’s authority by acknowledging the fallibility of the traditional interpretation of biblical narratives: “Agreement with the Earth’s rotation around the Sun would harm the holy faith by recognizing the positions of Holy Scripture as false.”
After the Council of Trent prohibited interpreting Scripture contrary to the collective opinion of the Church Fathers, the Church solidified the doctrine of the Sun’s rotation around the “most distant from heaven” Earth, which “is immovable at the center of the world.” Conversely, the assertion that “the Sun stands immovably at the center of the world” was considered by the Inquisition experts to be “a nonsensical thought, false from a philosophical standpoint and sinful from a religious perspective.” The official verdict of February 24, 1616, declared heliocentrism “a dangerous heresy” subject to persecution. After the Pope’s approval, the decision gained legal force, and Copernican teachings were deemed forbidden “until corrected.”
Galileo Before the Roman Inquisition, Cristiano Banti, 1857
The new decree was unacceptable for the staunch supporter of heliocentrism, and the scientist continued to advocate for knowledge despite the Church’s prohibition. To defend the truth, Galileo dared to publish a book with a neutral discussion of various viewpoints. He spent 16 years on this work, gathering compelling arguments and waiting for the right moment. Taking advantage of the election in 1623 of a new Pope—an old acquaintance and friend of Galileo, Matteo Barberini, known as Urban VIII—the scientist traveled to Rome to seek the repeal of the 1616 edict. Although after a personal meeting in 1624 Urban VIII prohibited the Jesuits from debating with Galileo, the conflict between the scientist and the Catholic Church remained unresolved. In the 1632 book of the theorist “Dialogue,” the Pope saw himself in the guise of an ignorant simpleton, thus harboring a personal grudge against the author.
The Path to Truth
During the investigation into Galileo’s case, he was interrogated under the threat of torture, and even after his renunciation of forbidden beliefs on his knees, he was kept under house arrest for the rest of his life, despite his advanced age and poor health. Meanwhile, the Inquisition did not engage in scientific debates with the esteemed prisoner; they were only interested in two questions: whether the scientist knowingly violated the 1616 edict and whether he repented of his actions. Galileo was given a choice: renounce the “dangerous errors” or share the fate of Giordano Bruno as an unrepentant heretic.
Galileo in Prison, Jean Antoine Laurent
Galileo’s “compliance” helped him avoid the Inquisition’s pyre, but deep down, he did not renounce his progressive views. Remaining under the watch of the Inquisition, Galileo continued his scientific work, even becoming completely blind in his old age. He settled near a convent in Arcetri, where his daughters lived, and outlived both of them (his favorite Virginia, in the convent as Maria Celeste, died young at 33 due to illness), leaving him alone with his sorrow. Galileo was forced to adhere to a regime that prohibited communication with friends and trips to cities. All his printed works were subject to censorship, and even the 77-year-old Galileo died on January 8, 1642, in the presence of two guards.
However, the lifelong surveillance of the prisoner did not hinder the popularization of his scientific works. The author of the theory of the homogeneity of matter laid the groundwork for Newton’s future discoveries, and his banned “Dialogue” continued to be published in Latin translation in Protestant Holland. The scientist continued to illuminate the path for humanity, planning to anonymously publish a new treatise in defense of his position.
While teaching the fundamentals of kinematics and material resistance, Galileo wrote that “even in darkness” he could not cease to ponder various phenomena of nature, for he “could not stop his restless mind, even if he wished to.” Regarding his last book “Discourse and Mathematical Proofs of Two New Sciences,” Galileo stated that it was “the defeat of Aristotelian dynamics,” for which he proposed new principles of motion, experimentally verified. The new book, featuring old heroes from the banned “Dialogues,” in the author’s view, once again placed him “among the ranks of fighters.”
Half-blind Galileo on a walk with his daughter. Engraving from Gaston Tissandier’s book “Martyrs of Science”
The authorities allowed the disgraced scientist to be buried without honors or a monument: he was laid to rest separately from the family basilica, and only later were Galileo Galilei’s remains reunited with those of his son. The last representative of the Galilei family, the scientist’s only grandson, became a monk and burned his grandfather’s invaluable manuscripts as “blasphemous.” However, the seed of knowledge sown did not perish in the future: the truth found its way to the minds of followers, albeit not as quickly as life would have demanded. After a nine-year effort by a commission from 1981 to 1992, the first to dare to proclaim Galileo’s rehabilitation was its initiator, Pope John Paul II. The Inquisition’s error from 350 years ago was recognized by the Pope only at the end of the 20th century.