Galileo Galilei
Italian Astronomer, Physicist, and Mathematician 1564–1642
Galileo's many important discoveries put him in direct opposition to the Catholic Church, the ruling body of the time. Only centuries later would Galileo be cleared of heresy.Galileo Galilei is a pivotal figure in intellectual and scientific history. His ideas and activities were integral to the Scientific Revolution, which resulted in world-changing advances in science and technology, and in fundamental changes in the way reality is perceived.
Galileo was born in Pisa, Italy, in 1564. In 1581, he entered the University of Pisa, where his father wanted him to study medicine. But Galileo was interested in mathematics and philosophy, and he left the university without a degree. In 1589, he taught mathematics at the university, but lost his job by challenging Aristotelian teachings held by the university and the Catholic Church. However, he immediately became professor of mathematics at the University of Padua.
Galileo was among the first to perceive that the natural world acts in a regular manner that can be interpreted and understood mathematically. Applying this approach, he developed the concept of acceleration and discovered the law of falling bodies, explaining the movement of projectiles, pendulums, and objects moving on an inclined plane.
Galileo accepted the Sun-centered model of the solar system that had been proposed by Copernicus. This model was in opposition to the Earth-centered model of Ptolemy that was accepted by scholars and the Catholic Church. Soon after the first telescope was invented, Galileo built his own version in 1609 and improved its magnification power. He was the first to use a telescope to study the heavens, obtaining, through these investigations, proof of the Copernican system. He discovered sunspots, valleys and mountains on the Moon, satellites circling Jupiter, and the phases of Venus.
In 1610, Galileo published his observations and interpretations in The Starry Messenger, refuting Aristotle and Ptolemy and supporting Copernicus. Opposition came immediately from scholars and churchmen, who accused him of heresy.
In 1612, Galileo published a book on hydrostatics based on observations, measurements, and mathematical analysis. He was again attacked by churchmen and university scholars for not adhering to the accepted Aristotelian approach. He openly argued that physical evidence and mathematical proofs should not be made dependent on interpretations of scripture but that such interpretations should be subject to change when new evidence becomes available. Not surprisingly, the Catholic Church issued an edict in 1616 banning Copernicanism and censored Galileo's writings.
Undaunted, in 1632 Galileo published Dialogue on the Two Chief World Systems contrasting the planetary models of Ptolemy and Copernicus, with clear preference for Copernicus. He was called to Rome and tried for heresy. Convicted, he was forced to publicly retract his ideas and placed on permanent house arrest. His works were banned, but this order was essentially ignored outside of Italy. His ideas spread rapidly, gaining support throughout Europe.
Galileo continued his work, and his last book, Discourses Concerning Two New Sciences, was published in Leiden in 1638. This classic volume presented a mechanical mathematical physics that eventually led to the development of what would be called Newtonian physics. Galileo died in 1642, the year of Isaac Newton's birth. In 1992, the Catholic Church rescinded its 1633 conviction of Galileo as a heretic—350 years after his death.
Galileo's Belief in Empiricism
Galileo believed that the development of new ideas and understanding was stifled by blind adherence to the authority of the Catholic Church and the writings of the ancient Greeks. Rather than simply accepting the statements of authorities, he believed investigators should rely on their own observations, measurements, and calculations.
Newton, Sir Isaac; Solar System Geometry, History Of.
Bibliography
Gamow, George. The Great Physicists from Galileo to Einstein. New York: Dover Publications, Inc., 1988.
Santillana, Giorgio de. The Crime of Galileo. Chicago: University of Chicago Press, 1955.
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