Galileo: Scientist, Scholar, Rebel

Seventeenth-century European study was controlled by two powerful forces: the Roman Catholic Church, headed by the Pope, and ancient philosophy dominated by the 2000-year-old ideas of the Greek philosopher, Aristotle. The Church had an overwhelming influence on the lives of most Europeans. During Galileo's time one in twelve people living in Rome was either a cleric or a nun.1 The Church forbid any teaching that deviated from what was taught in the Bible. To enforce this control, the Church set up the Inquisition. Galileo was targeted by the Inquisition for his observations and experiments. 2 Because his teachings differed from the socially accepted ideas of Aristotle, the Inquisition believed he should be persecuted. Even though Galileo's observations were much more factual than Aristotle's and, more important, backed up by experiments and the use of the telescope, he was still sentenced to house arrest for life.

Galileo Galilei was born on February 15, 1564, in Pisa Italy.3 Galileo was born into a family considered nobility, and his father, Vincenzo Galilei, was an accomplished musician.4 Galileo was tutored privately and also educated by his father until the age of eleven, when his family moved to Florence and sent him to a Jesuit monastery to study medicine.5 Three years after his son began school, Vincenzo was surprised to learn Galileo had decided to become a monk. Somewhat angered, his father withdrew him from the monastery, and Galileo continued his high school education in Florence.

At age seventeen Galileo began college at the University of Pisa, where he reluctantly studied medicine. 6 Throughout his first term attending the university, Galileo became more interested in mathematics than medicine. A court mathematician, by the name of Ostillo Ricci, noticed Galileo in his lectures.7 Impressed with Galileo's knowledge, he urged Galileo change his major to mathematics. Against his father's wishes, Galileo changed courses, and by the end of his first term he was a mathematics undergraduate.8

Galileo made his first important discovery while attending the University of Pisa. Galileo noticed a swinging lamp above him during a church sermon. Extremely bored, Galileo conducted an experiment to see if the amount of time in between each swing was the same. Using his pulse to time, he discovered his hypothesis to be true. Although the pendulum was discovered in 1683, it was not actually used to keep time until near the end of Galileo's life.9

In 1685, at age twenty-one, Galileo dropped out of the University of Pisa without a degree.10 Before leaving school, however, he wrote a memo graph about physics called Il biclancetta. Galileo found that after publishing this, a small physics book, he acquired a reputation as an astounding mathematician with profound unconventional views on scientific wisdom.11 In 1589 the college dropout found a job at the University of Pisa thanks to the help of his rich friends.12 Galileo taught his classes by experimentation, and found many of Aristotle's theories to be incorrect. Galileo discovered that Aristotle's predictions on motion were wrong and wrote a pamphlet that criticized Aristotle's view. Although the pamphlet had ideas that are still respected today, it did not win the support of the university, and eventually, when Galileo's contract expired the university did not renew it.

In 1592 Galileo returned home to find work.13 He secured a teaching position at the University of Padua. The following year his family found themselves in financial distress. Galileo's father died, leaving Galileo in need of an alternate sources of income. Galileo focused his spare time on inventing the military compass. The invention of the military compass helped boost his reputation and became a source of much needed income.

Galileo also became interested in astronomy. Determined to prove the ideas of Aristotle and Ptolemy wrong, he read the works of Nicolas Copernicus. Copernicus was a Polish doctor, lawyer, clergyman, and astronomer who lived during the early 1500's.14 Copernicus was convinced that the Earth was not the center of the universe, but rather the Earth, along with other planets, rotated around the sun. Afraid of the consequences of expressing his theory, which contradicted accepted doctrine, Copernicus waited until near the end of his life to publish his ideas. Since Copernicus was unable to prove his ideas, no one championed his beliefs after his death. The Catholic Church ignored his writings, and they nearly faded into obscurity.

In 1609, Galileo heard news of a new optical instrument.15 Using this device, Galileo successfully invented the first telescope in 1610.17 The invention was first used to aid ship merchants, but soon Galileo saw its potential for astronomy. Focusing on the moon, Galileo discovered several dark patches he supposed to be seas. Among the new things revealed by his telescope, Galileo noticed three stars next to the planet Jupiter. After weeks of observation he discovered the stars had disappeared, then reappeared, always staying in line with Jupiter. Galileo published a report that stunned all the academic circles of Europe. His report, called The Sidereal Messenger, conflicted with the prevailing Catholic belief that the only planet with moons was Earth.18 Galileo's discovery of the moons of Jupiter led to perhaps the only occasion where he was actually rewarded for a scientific discovery, he received a job offer to be "philosopher and chief mathematician" of the Grand Duke if Tuscany, a position as superior to any other university chair.19

A very important German Jesuit scientist, Christoph Scheiner, claimed accusations that spots visible on the Sun were actually satellites, which meant that the Sun was a planet that had moons. Angered by this suspicious claim, Galileo wrote several derogating letters, in which he presented reasons why the spots had to be on the Sun, and not be independent satellites. The letters earned Galileo a remarkably dangerous enemy.

The success of Galileo's success began to trigger suspicion and envy. Sermons were preached against "Galileists" in Florence, and there were complaints the he "Defiled the dwelling place of the angels by seeing spots on the Sun and Moon, and lessens the hope of Heaven."20 In his defense, Galileo argued that it had always been permitted to interpret Scripture as allegory. But then he was accused of explaining the Bible in ways which contradicted the teachings of the Roman Catholic Church. These accusations were especially dangerous idea while the Protestant Reformation was then emerging as a major threat a major threat to the Church and authority. Galileo journeyed to Rome to explain he was not a