Xi Chen
Professor Shanyu Ji
Math 4388
15th Oct. 2017
Galileo Galilei
Generally considered the brightest Italian polymath of scientific Renaissance era, Galileo Galilei was one of the very first pioneers in the scientific revolution in the 16th century. He is best known for his improved vision of the telescope, his discovery of the four massive moons of Jupiter, and his advocacy of the Copernican system & heliocentrism that led to his trial against the Catholic Church. Galilei’s contribution in physics, engineering, astronomy, and mathematics deservingly earned him the nickname “father of modern science”. However, his path to success was never easy.
In early 1600’s, Galileo focused his telescope into the sky, and finally found the astronomical evidence to support Copernicus’s mathematical argument. Such devise was inspired by a spyglass – an optical instrument that was widely popular in Europe at the time. Spyglass was made by advanced opticians with very low power telescopes, it can magnify distant objections on Earth. After learning about Spyglass, Galileo improved the magnifying power and built the first fracting telescope. He grinded and polished the lenses, and used math to calculate the distance between the two lenses. He discovered that with greater distance between two lenses, he could see close objects with clarity, while a shorter distance between two lenses, he could see distant objects more clearly. Galileo’s optical telescope enabled him to observe celestial objects in detail. For example, Galileo perceiveD the roughness of the Moon’s surface and observed that four moons circling around Jupiter, and he eventually demised the theory of geocentric Ptolemaic model of the Universe.
Figure 1 The earliest known sketch of a telescope, Aug.1609 (Australia Telescope National Facility)
Figure 2 Galileo’s drawing of the optical path of his telescope (Australia Telescope National Facility)
Figure 3 Distance between two lenses
(Mathematical understanding of functions of Galilean’s telescope: Y’ – is the distant object, y’’ is the real image from objective, y’’ is the magnified virtual image from eyepiece, D is the entrance pupil diameter, d is the virtual exit pupil diameter, L1 is the objective lens, L2 is the eyepiece lens, e is the virtual exit pupil.) (Tamasflex)
With the systematic use and refinement of telescope, Galileo made significant scientific discoveries of the solar system. On January 7th, 1610, Galileo observed two tiny “stars” to the east of Jupiter, and one to the west, all arranged in a tight straight line along the ecliptic path with Jupiter itself. However, in next evening, all three tiny “stars” were on the west side of Jupiter. Galileo realized these tiny “stars” were not fixed at all, they moved around Jupiter just like Moon moves around Earth. He proposed his theory by concluding that moon orbits Earth, and supported The Copernican system of ethnocentrism. Galileo published “Sidereal Messenger” (Sidereus Nuncius) with his newly observation and thoughts about how Universe works. The document also contained various observations of new stars in the Milky way. By calling Jupiter’s moons the “Medician Stars”, he quickly earned favor with the grand duke Cosimo II de Medici of Tuscany. More importantly, Galileo described the roughness of the Moon’s surface going against the idea of heavenly perfection, and the orbits of stars violated the geocentric idea that “heavens” revolved around Earth. His observation contradicted the Aristotelian view of the universe.
Figure 4 Geocentrism of Ptolemaic system (Velho)
His publication became one of the most controversial topics at that time, because it challenged and contested The Ptolemaic Model, which acknowledged that Earth is the center of the Universe, and Geocentrism was publicly supported by the powerful Catholic Church. In 1616, the Catholic Church publicly banned “De Revolutionibus Orbium Coelestium” (On the Revolutions of the Heavenly Spheres), published by Nicolaus Copernicus in 1543, which explained that the earth rotated on its axis once daily and travelled around the sun once yearly. Galileo Galilei was personally called to Rome by Pope Paul V and told that he was no longer allowed to support Copernican system.
Figure 5 Heliocentrism of Copernicus system
In a failed attempt to please the Church while proving his point, Galileo Galilei published “Dialogue concerning the Two Chief World Systems” in 1632 with formal authorization from the inquisition and papal permission. Pope Urban VII had asked Galileo not to advocate heliocentrism. The document was supposedly presented arguments for both side of heliocentrism debate. However, it was unclear to everyone that Galileo’s intention was to balance the scale. Especially it did not help that his advocate for Geocentrism was named “Simplicius”. (“Simpleton”). As a result, Galileo inadvertently alienated himself from his most powerful supporter – the Pope and subsequently summoned to Rome to defend his book in 1633. At first, in front of the Roman inquisitor Vincenzo Maculani, Galileo maintained that he had not advocated heliocentrism and kept his promise not to support Copernicus’ idea publicly. In July 1633, after being threatened with torture, Galileo admitted that he had only done so unintentionally. Galileo was convicted of “vehement suspicion of heresy” having held the belief that the Sun is the center of the universe and the Earth moves around contrary to the Holy Scripture. “Dialogue concerning the Two Chief World Systems” was put on the List of Prohibited Books by the Catholic Church. Initially, Galileo was sentenced to imprisonment. Though, this was reduced to house arrest. He carried out this sentence until the day he died.
It wasn’t until the 20th century that Popes Pius XII and John Paul II made official statements of regret how the Church had treated Galileo. The Dialogue marked a great triumph for Galileo, his argument was finally published in print and approved by the Church in 1744. The Dialogue was initially written in Italian language but has now been translated to different languages and print around the world. It is not only one of the most important written scientific references but also a work of supreme clarity and accessibility. Galileo’s theory of ethnocentrism was also supported by many famous scientists such as Newton and Kepler.
Galileo didn’t narrow his topic to only astronomical topics, but also over much of contemporary science. His discoveries played an important role in William Gilbert’s work on Magnetism. His discoveries & meticulous documentation proved invaluable and created the foundation for modern science. Even the likes of Newton & Einstein gave him the nickname “father of modern science”. His knowledge indeed live on in each and every one of us.
Work Cited
Australia Telescope National Facility, “The earliest known sketch of a telescope”, CSIRO
Australia Telescope National Facility, “Galileo’s drawing of the optical path of his telescope”, CSIRO
Tamasflex, “Optical diagram of Galilean telescope”, WIKIPEDIA, 15 March 2010
Velho, Bartolomeu. “Figure of the heavenly bodies.” WIKIPEDIA, 1568
“Heliocentricus of Copernicus system.” Minmaxsunt.wordpress, 1 Nov. 2012.