Author: Dr. Muhtar Ahat

Galileo Galilei (1564-1642) Galileo was born in Pisa. He was shown his talent not only in science but also in music and art. At the age of 17, he began to study medicine, soon, his interests turned to other branches of science. Later, he was appointed as a professor of mathematics at the University of Pisa. There, he conducted some important experiments to investigate the principle of motion.

His results were against the Greek philosopher Aristotle’s theory which said that heavier objects fall faster than lighter one. Galileo shows that in the ideal frictionless case, all objects have the same acceleration. A legend said that Galileo conducted an experiment on the Leaning Tower of Pisa. There, he climbed on the top of tower; he simultaneously dropped the two objects with different weights. These two objects reached the ground on same time. Now, his conclusions are described as the Newton’s First Law of the Newtonian mechanics.

In 1608, Galileo built a series of telescope with different magnifies by using two spectacle lenses (the telescope can magnify a distant object). He discovered that our moon has mountain ranges, that Jupiter has moons, and that the sun has dark spots. His observations also supported the idea of Copernicus (1473-1543) that the earth is not the center of universe. From his observations he showed that the apparent motions of the sun, stars, and planets could be most simply explained by supposing that earth itself is a planet that rotates daily on its axis and revolves annually about the sun. These results were against the Aristotle’s teaching. This led to a serious problem with the Church authorities because Church adapted the Aristotle’s teaching.

The Church authorities initially forbidden to discuss his ideas, later he was ordered to describe the Copernican ideas as only a hypothesis. However, Galileo’s analysis and presentation of the existing facts were so complete and convincing that earth is moving. At the age of 70, he published that famous book <<Dialogue Concerning the Two Chief Systems of the World - Ptolemaic and Copernican>>. In that book, he described two worlds: one is the new world which is represented by him and others (they have shown the truth that earth was not the center of universe based on the facts), other is the old world which is represented by the Church (based on the Aristotle’s teaching, in fact it was wrong). Since he didn’t change his opinions on this matter, the Church authorities ordered a trial, after the trial he was kept under house arrest for the remaining 12 years of his life.

It was a sad end for so great a man to die condemned of heresy. This argument has been continued to now. On 31 October 1992, 350 years after Galileo's death, Pope John Paul II gave an address on behalf of the Catholic Church in which he admitted that errors had been made by the theological advisors in the case of Galileo. He declared the Galileo case closed, but he did not admit that the Church was wrong to convict Galileo on a charge of heresy because of his belief that the Earth rotates round the sun.