GALILEO GALILEI: BIOGRAPHY, CONTRIBUTIONS AND WORKS - CULTURE VOCABULARY - 2025

Galileo Galilei (1564-1642) was an Italian astronomer, physicist, mathematician, and professor who made pioneering observations that formed the basis for modern astronomy and physics. He also built a telescope, which allowed him to confirm the heliocentric model of Nicolaus Copernicus.

Not only his discoveries were important, but also the methods he used, especially mathematics. He insisted that nature had to be described in the language of mathematics, thereby influencing the shift from a verbal and qualitative description to a quantitative one.

Due to all this and his great role in the development of the Scientific Revolution and the scientific method, he is considered the father of modern science. On the other hand, his formulation of the law of falling bodies, inertia and parabolic trajectories marked the beginning of a new path in the study of motion.

Something not very well known about Galileo is that he was a Catholic. Despite this, he defended the heliocentric Copernican theory and disobeyed some orders that the Catholic Church tried to impose on him. Perhaps this is why he is the greatest exponent of a scientist who faces accepted knowledge in an age challenging authority.

Biography

Galileo Galilei at his trial for the Inquisition in Rome in 1633. Galileo pushes the Bible.

Galileo Galilei was born on February 15, 1564 in the Tuscany region, specifically in the city of Pisa. His family was noble, but not overly wealthy, and they sustained themselves through trade. It was an extensive family picture, since there were six brothers in total.

Galileo was the eldest of all his brothers. His parents were the mathematician and musician Vincenzo Galilei, a native of Florence; and Giulia Ammannati di Pescia, who came from a family of artisans.

Due to the adverse economic situation that the family experienced, Vincenzo had to dedicate himself to business, because what really filled him was music. In fact, he was a composer and studied music theory; the works written by him had a certain prestige in the society of the time.

Training

Galileo's most primary education was in his own home. His parents were in charge of educating him until he was 10 years old.

In 1574 Galileo's parents moved to Florence, leaving him in charge of a family neighbor named Jacobo Borhini, who was characterized as a very religious man.

It was precisely Borhini who did the errands so that Galileo could enter the convent of Santa María Vallombrosa, located in Florence.

The training he received there was focused on the religious sphere, and even at one point in his life Galileo considered himself ordained as a priest. His father did not approve of this interest, since he was an unbeliever man.

At that time Galileo had developed an infection in one eye, and it was precisely this discomfort that his father used as an excuse to withdraw him from the convent, arguing that he had been given poor care.

Once outside the convent, Galileo's father enrolled him at the University of Pisa. This happened in 1581 and even today this house of studies remains one of the most important in Italy. There Galileo studied mathematics, philosophy and medicine.

Interest in mathematics

Vincenzo Galilei's plan was for his son to dedicate himself to medicine. However, the discipline that really caught Galileo's attention was mathematics, and Ostilio Ricci had a lot to do with this.

Ricci was a friend of the Galilei family and a student of the mathematician Niccolò Tartaglia, and he always perceived mathematics as a merely practical tool, through which engineering or mechanical problems could be solved.

Ricci had some sessions with Galileo, parallel to his university studies. It was the practical approach that attracted the most Galileo's attention, since Ricci was characterized by imparting his knowledge through experimental practices, a dynamic that was not very usual at that time.

These experiences with Ricci were central to Galileo's decision at the time: to stop focusing on medicine and dedicate himself to mathematics.

It is worth noting that even in his university days, Galileo made one of the first discoveries related to mechanics, a science about which he theorized extensively. It was the theory of isochronism, which established that the oscillation periods associated with pendulums do not depend on the amplitude.

Influential authors

The texts of the Greek geometer and mathematician Euclid were also very influential for Galileo. By focusing on studying mathematics, he began to read different authors, including Archimedes, Plato, and Pythagoras.

Galileo identified himself with the approaches made by these characters in history and, on the other hand, he was considered adverse to those proposed by Aristotle, a philosophy for which he exhibited no interest.

In 1585 Galileo returned to Florence without having completed his university training and with great interest in learning mathematics. During this stage, he managed to obtain a lot of knowledge, which served as a solid base for his next training process.

First experiments

From 1585 Galileo began to carry out various experiments. One of the elements he focused on was the center of gravity of solids; Within the framework of this interest, he carried out various theorem tests related to this area.

Around this time Galileo invented the heart rate monitor, a tool with which it was possible to measure the pulse and frame it on a time scale. Likewise, he continued to develop research related to pendulums, falling bodies and the hydrostatic balance proposed by Archimedes.

Teaching experience

Three years after arriving in Florence, in 1588, the Florentine Platonic Academy invited him to give a couple of lessons. From then on Galileo began to look for a position as a university professor, and in the middle of the search process he met renowned academics such as Guidobaldo del Monte, an Italian astronomer, philosopher and mathematician.

The latter introduced Galileo to Ferdinand I de Medici, who was serving as Grand Duke of Tuscany. Ferdinand I offered Galileo a position as professor of mathematics at the University of Pisa. On November 12, 1589, he began his work as a teacher.

In 1590 and 1591, while working as a university professor, Galileo found the concept of the cycloid, which corresponds to a curve that is drawn by a point on a circumference while moving along a line. This conception allowed him to be able to draw arches of bridges.

Padua trip

Some sources indicate that Galileo had certain disagreements with one of the sons of Fernando I, a reason that could have motivated him to leave Pisa and seek other horizons.

Then, in 1592 Galileo traveled to the city of Padua and was professor of astronomy, mechanics and geometry at the University of Padua, which is counted among the oldest houses of study in the world. He was a teacher there for 18 years, until 1610.

Specifically, Galileo taught lessons on military architecture, mathematics, applied mechanics, and astronomy.

At that time the Inquisition was in force in the European context, but the city of Padua remained somewhat away from the conflicts, due to the fact that it was part of the Republic of Venice, an independent state that was located towards the north of Italy and that was extremely powerful at that time.

Because of this fact, Galileo felt free to carry out his experiments in complete tranquility, without being threatened by this oppressive institution.

Death of the father

In 1591, Vincenzo Galilei, Galileo's father, died. At that time the family was in a serious economic situation.

From then on, Galileo found himself obliged to contribute to the family economy, and to produce more income he began to offer private classes in his own home, aimed at children from wealthy families.

Galileo intended to help his family, but apparently he wasn't managing money in the most efficient way, so his input didn't really make a difference.

Among the obligations to which Galileo had to respond, the gifts of his sisters Virginia and Livia stood out. Only through help from friends and some loans requested by Galileo himself did he manage to stabilize his family's economy.

Life as a couple

In 1599, the year in which Galileo was part of the founding committee of the Accademia dei Ricovrati, he met a young woman named Marina Gamba, who later became the mother of his children. They lived together even though they never got married.

Their three children were born practically one after the other: Virginia was born in 1600, Livia in 1601, and Vincenzo in 1606.

The couple remained together until 1610, at which point they separated and Galileo took care of their son. As for the daughters, Vincenzo Galilei determined that they were not going to be able to marry due to their illegitimate status, for which they were registered in a convent. Unlike Virginia and Livia, Galileo's son was eventually made official as a legitimate son.

Discoveries

The years between 1604 and 1609 were very positive for Galileo, who made several discoveries.

Among the most important are the conception of the law of uniformly accelerated motion, the verification of the operation of the water pump and the observations on a new star observed in the sky.

In 1606 Galileo created the thermoscope, an innovative tool that was capable of objectively measuring how much heat and cold there was in a space. At the same time he also dedicated himself to studying the conformation of magnets.

Telescope

In 1609, one of Galileo's most iconic inventions took place: the telescope. This scientist learned that Hans Lippershey, a Dutch-born lens manufacturer, had built a tool through which it was possible to distinguish stars invisible to the human eye.

Soon after, Galileo began to build his own telescope. He got it to have a magnification range of about six times, three times more than the telescope that Lippershey presented. Also, the image was not distorted and looked straight, thanks to the use of a diverging lens.

Galileo continued to refine his invention and built another telescope, which was able to enlarge the image about nine times. Once this copy was finished, he presented it to the Senate of Venice, where he carried out a demonstration and surprised everyone present.

The rights to the telescope were ceded by Galileo to the Republic of Venice. In return, he kept his position at the University of Padua and received higher monthly income.

1610 was also fruitful for Galileo, as he engaged in astronomical observations with his ever-improving telescopes. These observations allowed him to verify that celestial bodies do not revolve around the Earth, and that not all planets revolve around the Sun.

Return to Florence

In 1610 Galileo returned to Florence, where he was appointed first mathematician of the University of Pisa. Likewise, the Duke of Tuscany named him the first philosopher and first mathematician.

In addition to these recognitions, in March 1611 he attended the Pontifical College of Rome and the Academy of the Lynx, invited by Cardinal Maffeo Barberini.

The reason for this invitation was to offer a space for Galileo to present his findings there. In this context, the Lynx Academy welcomed him as its sixth member.

Attacks

Galileo's conception was very popular and, at the same time, very damaging for a large sector that identified with the geocentric theory of the universe. This generated contrary reactions and, little by little, more violent towards Galileo.

The first confrontation was through tracts and pamphlets published by Galileo and his followers, as well as his detractors.

Very soon the attacks on Galileo changed their focus and the supposed intention of the scientist to interpret the Bible in a way favorable to his theories was raised. As a result of these arguments, in 1611 Cardinal Roberto Belarmino ordered the Inquisition to investigate Galileo.

Religious focus

After Galileo built his telescope in 1604, he began to gather information that supported the Copernican theory that the Earth and the planets revolve around the Sun. However, this theory questioned Aristotle's doctrine and the order established by the Catholic Church.

In 1612 the Dominican priest Niccolo Lorini gave a speech in which he criticized Galileo from the point of view of religion; this is considered the starting point for attacks with religious overtones.

In 1613, Galileo wrote a letter to a student in which he explained that the corpenic theory did not contradict biblical passages. The letter was made public and the Church Inquisition declared the heretical Copernican theory.

In the years that followed there were discussions in which Galileo always presented his findings. To defend himself from calumnies, in 1615 he went to Rome and continued to defend the heliocentric theory of Copernicus from there.

In February 1616 he was summoned by the Holy Office with the intention of evaluating the censorship of this Copernican theory; in effect, this theory was censored. Galileo was ordered not "to uphold, teach, or defend the Copernican theory in any way."

This was devastating for Galileo, who became seriously ill. From then until 1632 he continued to defend his notions from various platforms and continued to develop studies, at the same time that he published several of his most relevant works.

Sentence

During the early 1630s Galileo published a work in which he again showed his support for the Copernican theory. The censorship of 1616 forced him to speak of this theory as a hypothesis and not as something proven, and Galileo ignored it.

In 1623, a friend of Galileo, Cardinal Maffeo Barberini, was elected Pope, under the name Urban VIII. He allowed Galileo to continue his work in astronomy and even encouraged him to publish it, on the condition that it was objective and did not advocate the Copernican theory. This led Galileo to publish Dialogues on the World's Two Greatest Systems in 1632, which advocated the theory.

The reaction of the Church was swift and Galileo was called to go to Rome. The investigation by the Inquisition lasted from September 1632 to July 1633. For most of this time, Galileo was treated with respect and was never imprisoned.

Home arrest

On April 9, 1633, the process began and Galileo was forced to confess his faults to the decree of 1616, with the threat of torture if he did not do so. Galileo agreed and was taken to court. On June 21, he was sentenced to life imprisonment and forced to deny his ideas.

After doing so, the sentence was changed to house arrest. There he was imprisoned from 1633 to 1638 and at that time he was able to publish some more works, since he was able to receive visits from some colleagues.

Death

In January 1638 Galileo became blind and was allowed to move to his house in San Giorgio, located very close to the sea. While there he continued working with several of his disciples, such as Evangelista Torricelli and Vincenzo Viviani.

On January 8, 1642, Galileo Galilei died at the age of 77. On January 9 his body was buried in Florence and several years later, in 1733, a mausoleum dedicated to him was built in the Church of the Holy Cross in Florence.

Main contributions

First law of motion

Galileo was the forerunner of Newton's law of motion. He concluded that all bodies accelerate at the same rate regardless of their size or mass.

He developed the concept of motion in terms of speed (speed and direction) through the use of inclined planes.

In addition, he developed the idea of ​​force as a cause for motion, and determined that the natural state of an object is rest or uniform motion. For example, objects always have a velocity and sometimes that velocity has a magnitude of cer, or equal to rest.

He further postulated that objects resist changes in motion, which is called inertia.

Telescope upgrade

Galileo did not invent the telescope, however the improvements made by the scientist to the Dutch version of the instrument allowed the development of his empirical discoveries.

Previous telescopes magnified objects three times the original size, but Galilei learned to focus the lenses and created a telescope with a magnification of 30x.

Discovery of the satellites of Saturn

Galileo Galilei. Oil painting for an Italian pain. 8th century ¿?

With the new telescope, Galileo Galilei was the first to observe the four largest Jupiter satellites, the craters on the surface of the Moon, as well as the sunspots and phases of Venus.

The telescope also revealed that the universe contained many more stars that were not visible to the human eye. Galileo Galilei, through sunspot monitoring, inferred that the Earth could rotate on its own axis.

The discovery of the phases of Venus was the first evidence to support the Copernican theory, which claimed that the planets orbit the Sun.

Defense of heliocentrism

Galileo's observations confirmed the Copernicus heliocentric model. The presence of moons orbiting Jupiter suggested that the Earth was not the absolute center of motion in the cosmos, as Aristotle had proposed.

Furthermore, the discovery of the Moon's surface disproved the Aristotelian point of view, which expounded an immutable and perfect universe. Galileo Galilei also postulated the theory of solar rotation.

Divorce between science and the Church

After contradicting Aristotle's theory, which was the one approved by the Catholic Church at the time, Galileo Galilei was found guilty of heresy and sentenced to arrest at his home.

This caused a separation between ecclesiastical dogmas and scientific research, which generated a Scientific Revolution, as well as a change in society that marked future research.

Scientific methodology

Galileo Galilei introduced a new way of research, through the scientific method. He used this method in his most important discoveries and today it is considered indispensable for any scientific experiment.

Law of Fall

Before the time of Galileo, scientists thought that force caused speed as Aristotle said. Galileo showed that force causes acceleration.

Galilei concluded that bodies fall on the Earth's surface at a constant acceleration, and that the force of gravity is a constant force.

Your mathematical ideas

Speeches and demonstrations around two new sciences related to mechanics was one of the greatest works of Galileo Galilei. Its original name is Discorsi e dimostrazioni matematiche intorno a due nuove scienze attineti la mechanica.

Galileo exposes in this work one of his most famous and enduring mathematical ideas, such as the movement of objects on an inclined plane, the acceleration of bodies in free fall, and the movement of pendulums.

It was published in Leyden, Holland, in 1634, after presenting problems in its presentation with the Catholic Church in Italy.

The thermoscope

One of Galileo Galilei's most notable inventions was the thermoscope, a version that would later become today's thermometer.

In 1593, Galileo built the thermoscope using a small glass filled with water and attached it to an elongated pipe with an empty crystal ball at the end. This thermoscope relied on temperature and pressure to give a result.

The military compass

Galileo improved a geometric and military multifunctional compass between 1595 and 1598.

The military used it to measure the elevation of the barrel bar, while merchants used it to calculate the exchange rate for currencies.

Plays

Galileo published several works throughout his life, including:

-The operations of the geometric and military compass (1604), which revealed Galileo's abilities with experiments and practical applications of technology.

-The Sidereal Messenger (1610), a small booklet that reveals Galileo's discoveries that the Moon was not flat and smooth, but a sphere with mountains and craters.

-Discourse about things that float on water (1612), which refuted the Aristotelian explanation of why objects float in water, saying that it is due to its flat shape, but because of the weight of the object in relation to the water that displaces.

- Letter to Mrs. Cristina de Lorena, Grand Duchess of Tuscany (1615), in which she deals with the problem of religion and science.

-The Assayer (1623), written with the purpose of ridiculing Orazio Grassi.

-Dialogues on the two greatest systems in the world (1632), a discussion between three people: one who supports Copernicus's heliocentric theory of the universe, one who opposes it and one who is impartial.

-Two New Sciences (1638), a summary of Galileo's life work on the science of motion and the force of materials.

References

1. Galilei G. Dialogue concerning the two chief world systems. London: Modern Library Science, 2001.
2. The Columbia Electronic Encyclopedia, 6th ed, 2012.
3. Sharrat, Michael. Galileo: Decisive Innovator. Oxford and Cambridge, MA: Blackwell, 1994.
4. SparkNotes: The Scientific Revolution (1550 - 1700) - The Re-Formation of the Heavens.
5. Galileo and Scientific Method, W Fisher Jr… Rasch Measurement Transactions, 1993, 6: 4 p. 256-7.
6. Galileo's Law of Fall. Excerpted from Encyclopedia Muse. muse.tau.ac.il.
7. Drake, Stillman. Galileo: A Very Short Introduction. New York: Oxford University Press, 1980.