Galileo Galilei was an Italian astronomer, physicist and engineer, often described as “the father of modern science.” He was born in Pisa, Italy on February 15, 1564. His parents were Vincenzo Galilei and Guilia Ammannati. His father was a famous composer, musician, and music theorist and his mother was from a wealthy aristocratic background. Galileo had an older sister named Virginia and a younger brother named Michelangelo.
From a young age, Galileo showed great skill in mathematics, leading his father to have him educated under the mathematician Ostilio Ricci in Florence. While in Florence, Galileo was exposed to the lectures of the Tuscan court mathematician Christophorus Clavius. Under the influence of Ricci and Clavius, Galileo developed a fascination with mathematics and physics, choosing to pursue scientific studies over a career in medicine as his father wished.
In 1581, Galileo enrolled at the University of Pisa to study medicine. While at Pisa, however, Galileo became more and more interested in mathematics and physics, causing him to neglect his medical studies. It was at Pisa that Galileo conducted his famous experiments with falling objects from the Leaning Tower of Pisa to test Aristotelian theories of motion. Though the results supported Copernican theories, few were listening at that time to the 22 year old student. Having offended his teachers and openly criticized Aristotelian professors, Galileo left the university without his degree in 1585.
After leaving the University of Pisa without a degree, Galileo began teaching private lessons on mathematics in Florence and Siena. During this time, he published his first scientific work, The Little Balance, describing an accurate balance to measure small quantities. This brought Galileo minor fame among scholars.
In 1589, Galileo was appointed to the Chair of Mathematics at the University of Pisa, allowing him to return as a professor. The appointment was somewhat unusual, partly because Galileo was a Tuscan and the student body was dominated by Florentines and partly because he never completed his degree. During his three years at Pisa, Galileo continued his experiments and began giving public lectures on astronomy. In 1591, he moved to the University of Padua in the Republic of Venice after Florence temporarily fell under control of the Holy Roman Empire.
At Padua, Galileo taught mathematics and was able to pursue his investigations into astronomy. It was here that Galileo made significant discoveries, including “the law of falling bodies” and detailed observations of the Moon that revealed its mountainous terrain. He also worked on the design for a thermometer during this time. His work gained wider notice and his services were requested by many foreign nations. During this period Galileo also studied the works of Copernicus and concluded in favor of heliocentrism, the concept that the Sun was at the center of the universe. This was seen as heretical by the Roman Catholic Church due to Scripture passages implying geocentrism.
In 1604, a supernova appeared in the skies over Europe, making a strong impression on Galileo. Galileo published a paper on the supernova, showing important observations that disproved many common beliefs in Aristotelian astronomy, much to the dislike of proponents of the more traditional viewpoints. The same year, Galileo also developed an improved compass for military and surveying use.
In 1609, Galileo learned of the invention of the telescope in the Netherlands. Using his own technical skills, Galileo began designing and building telescopes after learning the concepts. By August 1609, he had improved upon the Dutch design and built an 8x magnified telescope. He continued to improve his designs, reaching 20x magnification the next year.
With his telescopes, Galileo began a wide ranging study of the heavens including the Moon, stars, and planets. In 1610, Galileo published important astronomical observations showing mountains and craters on the Moon, the proper rotation of sunspots, and the fact that the Milky Way was made up of individual stars. His discoveries caused great debate in European intellectual circles, splitting proponents of the old geocentric model such as Aristotelians and the Roman Catholic hierarchy, and the new model shown by telescopic observations. The publicity over the controversy made Galileo famous across educated Europe.
In the same year as his telescopic observations, 1610, Galileo also published a treatise on buoyancy and the concept of floating objects he had devised. This laid the groundwork from important later studies of dynamics and statics. He also studied the parabolic path of projectiles, paving the way for the study of ballistics.
In 1611 Galileo visited Rome where he was treated with honor and greeted as a celebrated intellectual figure, including receiving a friendly audience with Pope Paul V. He was likewise honored in Florence and Venice with many seeking audiences with the scientist who had made such important and famous observations. However, in 1613 Galileo came into conflict with proponents of Aristotelian cosmology over floating suns in imperfect heavens when he wrote letters stating opinions aligned with the banned works of Copernicus.
In 1613, Galileo was appointed as “First Mathematician and Philosopher of the Grand Duke” of Tuscany. This secured him patronage in Florence and gave financial security. Now fully supported by a stable career and no longer reliant only on students, Galileo aimed his efforts full time into scientific studies.
In 1615 Galileo refined his theories on astronomy and physics into a clean paradoxes that mocked traditional beliefs while technically staying within the realm of hypothetical debate. This work was not approved for printing but circulated informally.
That same year, a letter Galileo wrote regarding biblical interpretations of astronomy was viewed as defiance of the standard church positions and Galileo was warned by a fellow Florentine Cardinal that the Roman Inquisition may get involved if he persisted in public statements on biblical interpretation. Galileo refrained from this debate for the next several years out of caution.
In 1616, church officials in Rome became concerned with some real or rumored statements of Galileo on the topic of heliocentrism vs. geocentrism aligned with biblical interpretation. This came during a time of tension between the Roman church and critics aligned with the Protestant Reformation over interpretation of Scripture. Galileo was requested to come to Rome to account for his views and argue against geocentrism in the presence of Church authorities so they could be assured he was not making statements against Church doctrine.
In 1616 the Inquisition in Rome declared that the ideas of Copernicus were "foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture." Galileo was ordered to abstain from holding, teaching or defending them verbally or in writing. The Inquisition found that the idea of the Earth's movement is against the Bible, which speaks of the motion of the heavens and not the Earth.
Galileo's practice of insisting that the Church should reform its interpretations of biblical passages to match findings based on science and reason, was met with disapproval by theologians who appealed to the Bible's authority as the revelation of God.
Thus Galileo was met with a religious decree stating that it was standard church doctrine that the Earth was stationary at the center of the universe and anyone claiming otherwise was subject to punishment by the Inquisition. The wording allowed that hypothetically Copernicanism could be treated as science used for calculation, but not proposed as actually true.
For a few years after 1616 Galileo temporarily abandoned his researches into astronomy, aware of the dangers now involved. However, after 1619 a man named Mario Guiducci delivered lectures on the topics based on Galileo's work. This allowed Galileo a loophole where he could say others were raising the controversial issues rather than himself.
Then in 1623, a longtime friend of Galileo, Cardinal Barberini, ascended to become Pope Urban VIII. He allowed Galileo greater opportunity to advocate for Copernican theory as science and not necessarily fact. Cardinal Barberini encouraged Galileo to write a work on systems of the world and controver
