Major Figures of the Scientific Revolution (page 2)
Major Figures of the Scientific Revolution
The Scientific Revolution was an international phenomenon; scholars from all over Europe took part in it. This chapter describes the most important figures of the era.
Nicolaus Copernicus was born in 1473 in Torun, Poland. He learned astronomy from the books he read as a student in Italy. Books of the time agreed that the Earth was at the center of the universe and that the other heavenly bodies, including the sun, traveled around it. In ancient times, both Ptolemy and Aristotle had arrived at this view by observing the heavens. Despite Aristotle’s status as a pagan from the Classical era, the Church fathers had always accepted his view of astronomy because it allowed them to teach that humankind, God’s supreme creation, had its proper place in the center of the universe.
Copernicus, however, came to believe that Aristotle and Ptolemy were wrong. He suggested that the sun, not the Earth, was at the center of the universe, with the planets orbiting it. It seemed to Copernicus that since the Earth and its moon were spherical, the orbits of the planets should be circular; how- ever, he realized that from the point of view of the Earth, the orbits could not be perfect circles. In 1543, Copernicus published his thoughts and discoveries in a book called De Revolutionibus, known in English as On the Revolutions of the Heavenly Spheres. He died the same year.
The next great European astronomer was Tycho Brahe. Born in 1546 to a noble family in what was then Danish territory, Brahe was fortunate in having as his patron a king who provided him with a fully fitted observatory. This enabled him to conduct direct experiments in astronomy—the first in Europe for many centuries. While Copernicus’ theories had been more or less guesses, Brahe’s observations told him that while the sun and moon traveled around the Earth, the other planets orbited the sun. Like Copernicus, he could not understand why the planets’ apparently circular orbits were not regular.
Brahe’s assistant, the brilliant Johannes Kepler, took discoveries of the heavens one step further. Born in 1571 in the free city of Weil der Stadt, Kepler used mathematics and direct observation to show that the orbits of the planets were ellipses, not circles. As soon as he replaced the idea of circles with that of ellipses, the orbital paths became regular. Kepler also proved that the planets orbited the sun at different speeds. His greatest work was On the Motion of Mars, published in 1609; it soon appeared on the Holy Office’s Index of Forbidden Books.
Astronomy took a giant leap forward with the discovery of the telescope, first patented in the Netherlands in 1608–1609. Scientists had realized during the 1300s that a glass lens could magnify an object seen through it; they had been using this knowledge ever since to manufacture eyeglasses and magnifying glasses. However, these were only intended to improve people’s vision for everyday purposes such as reading. No one had thought to apply the same idea to achieving a close-up view of such faraway objects as the stars.
Mathematics and engineering professor Galileo Galilei of Pisa was the first to make extensive use of the telescope to study the planets. With this new invention—at that time no more than a plain narrow tube a little over a yard long, with concave and convex lenses inside—he was able to see things in the heavens that had simply not been visible to his predecessors.
Looking through his telescope in 1610, Galileo realized immediately that Jupiter had its own moons in orbit around it, just as the Earth had a moon. This discovery alone proved that Earth was not the center of the universe around which all other objects orbited. When Galileo published his new knowledge of the heavens, Kepler and most of Europe’s intellectuals, including the Jesuit astronomers, eagerly accepted them.
Through his telescope, Galileo saw the rings around Saturn, although he did not understand what they were. He observed that, contrary to Aristotle’s assertion that all heavenly bodies were perfect, smooth spheres, the surface of the Earth’s moon was craggy and irregular. Since the Church had accepted Aristotle’s theory of the universe, this meant that Galileo was well on his way to making an enemy of one of Europe’s most powerful institutions.
In 1632, Galileo published Dialogue on the Two Great Systems of the World. Written in the form of an imaginary dialogue between Copernicus and Ptolemy, this work discussed theories about planetary orbits and tides. A lifelong and devout Catholic, Galileo dedicated the Dialogue to Pope Urban VIII. It was clear that he anticipated no trouble from the Church because of his writing; he had carefully refrained from discussing certain forbidden topics, such as the work of Kepler.
To Galileo’s surprise, Urban VIII summoned him to Rome to appear before the Inquisition on the charge of defying the Holy Office’s policy against writing about Copernican theory. Galileo produced documentary proof of his assertion that he was permitted to write speculatively about Copernican astronomy. Despite this evidence, the Inquisition refused to face the public mockery that would have resulted from making a mistake over a figure so internationally famous as Galileo. The Holy Office therefore sentenced Galileo to deny the validity of his own discoveries, then placed him under custody of the liberal archbishop of Siena, who encouraged him to continue working and writing. In effect, Galileo remained under house arrest until his death in 1642. He was free to study, experiment, and write, although it proved difficult (though not impossible) to find publishers in the face of a Holy Office ban on anything he might produce.
Within the next few years Galileo’s works spread throughout Europe in various translations and editions. His last book, The Two New Sciences, discussed the structure of matter, the strength of materials, and the laws governing natural motion. He discovered the laws of falling bodies and the mathematical formula we use to describe acceleration.
Defending his own writings in his later personal correspondence, Galileo argued that God had given human beings the ability to observe and reason. What people could see and understand with their five senses must be the truth; for instance, that planets moved around the sun. He argued that if this appeared to conflict with the scriptures, then human understanding of the scriptures must be at fault.