Galileo Galilei: Architect of Modern Scientific Thought
Galileo Galilei: A Pioneer of Modern Science
Galileo Galilei (1564-1642) is considered one who took the final step towards modern science. Born in Pisa, he studied at the University of that city, where he became a teacher of mathematics. In 1592, he became a professor of the same subject in Padua, already famous for his scientific discoveries. In 1597, he wrote a letter to Kepler expressing support for Copernicus. In 1609, he developed his theory of uniformly accelerated motion and built a telescope. He then began his significant astronomical discoveries. In 1610, he moved to Florence, and in 1615, he was denounced to the Holy Office. In 1632, he published his seminal work:
Dialogue Concerning the Two Chief World Systems, in which he compared the Aristotelian-Ptolemaic system with the Copernican, presented as a conversation between three symbolic characters: Salviati, representing the new science and acting as a spokesman for Galileo; Sagredo, a free and open spirit, unprejudiced by traditional schools, able to understand and receive Salviati’s teaching; and Simplicio, a defender of the university tradition dominated by the authority of Aristotle. This publication precipitated his trial, which began that year, leading to his conviction the following year. Galileo did not recant; however, he was exiled to Arcetri, south of Florence. Galileo’s last work, Discourses and Mathematical Demonstrations Relating to Two New Sciences, published in Leiden in 1638, revised and refined his earlier studies on motion and the principles of mechanics in general. This book paved the way for Newton to formulate the law of universal gravitation, which harmonized Kepler’s laws on planetary motion with Galileo’s mathematics and physics. Before the publication of this work, Galileo became blind and died in 1642 while in exile.
Key Contributions to Modern Science
We emphasize three major contributions to modern science: to astronomy, to physics, and to scientific methodology. While often associated with astronomy, his most profound contributions were to physics. Galileo, who was primarily a physicist (and would have been so even before Copernicus, and even if he had never looked through a telescope), realized that the task facing science at the time was to align physics with the reality of a moving Earth. The old anti-Copernican arguments had been turned inside out: if the Earth truly rotated around its axis, why were there not extremely strong winds constantly blowing? Why did vertically dropping bodies not fall obliquely? In short, why did the moving Earth behave as if at rest? Finding the answers to these questions demanded that Galileo undertake important work on the motion of non-celestial bodies, paving the way for Newton.
Contributions to Astronomy
Galileo, building upon earlier astronomers’ work, took enormous advantage of the telescope—certainly primitive compared with current models—but which allowed him to see what nobody had ever seen before. (Arguably, he was not its sole inventor, but rather the one who best utilized it). The results were published in 1610 in his Sidereus Nuncius (Starry Messenger): he discovered the four largest satellites of Jupiter and the phases of Venus. Both findings, according to him, supported Copernicus’s heliocentric model. He also observed the surface of the Moon and sunspots on solar planets, demonstrating that these celestial bodies were not perfect, ethereal compounds with smooth and unchanging surfaces. This challenged the idea of two worlds of different matter, suggesting a homogeneous universe.