Galileo the Scientist

Introduction

The life and achievements of Galileo form a subject of enduring interest. He is certainly one of the greatest scientists of all time and indeed has been called the founder of modern science. He showed that natural phenomena obey mathematical laws and thus, Galileo laid the foundations of quantitative dynamics and used it to give the first accurate account of the motions of falling bodies and projectiles. He improved the telescope and used it to discover the moons of Jupiter, the mountains on the moon, the phases of Venus, and the spots on the sun. All this combined to throw doubt on Aristotelian cosmology and to support the heliocentric theory of Copernicus. More than any scientist, Galileo was responsible for initiating the transition from the Aristotelian science of the Middle Ages to the mathematical science of the following centuries.

Galileo lived at a critical moment in the development of science. According to the popular account, the ancient Greeks made the first steps toward a scientific understanding of the world. The Greek writings were inherited by the Muslim civilization and then transmitted to the new universities in the Middle Ages through translations done mainly in Spain. Thereafter, an authoritarian Church controlled the intellectual development of Western Europe and prevented any independent thought or scientific development. It was only during the Renaissance that the authority of the Church was challenged by men like Galileo who insisted on the greater value for science of experimentation and observation than reliance on ancient texts. This is dramatized by the story that Galileo dropped two balls of different masses from the Leaning Tower of Pisa and showed that, contrary to Aristotle's theory, they reached the ground simultaneously. Thereafter, science developed as a free and independent search for truth.

The reality is, of course, different and highly instructive. The familiar story, still heard today, that there was no science worth speaking about in the long period from the time of the ancient Greeks to the flowering of genius in the Renaissance has long been disproved by modern scholarship. Galileo himself was not only a highly original scientist but remained a devout Catholic throughout his life. ¹ He had a sound grasp of theology and saw clearly that the new knowledge of the world gained by the scientific method was in no way inconsistent with the teaching of the Church, since both come from God. He also saw that some of the new knowledge raised important problems of scriptural interpretation that could be resolved within the context of traditional Catholic theology. It is now recognized that Galileo's views on the interpretation of Scripture are basically correct, and he was particularly anxious to prevent the tragedy that actually happened—the condemnation by the Church of a genuine scientific breakthrough. He was, however, overconfident concerning his scientific arguments, which were still at that time inconclusive, at least to nonscientists. In view of the delicate theological questions raised by the heliocentric theory, it was not unreasonable for Church authorities to ask Galileo to moderate his claims until a definite proof was forthcoming. The main protagonists were all motivated to defend the truth, but they were strongly influenced by their intellectual backgrounds and possessed personal character traits that exacerbated their misunderstandings.

Before considering the achievements of Galileo, it is useful to sketch the understanding of the physical world that existed before his time.

The youthful Galileo was attracted to mathematics and avidly studied the works of Archimedes. His interest in hydrostatics was stimulated by Archimedes' solution of the problem of King Hiero's crown, which led to Galileo's first publication, The Little Balance (1586). Nature, he realized, is written in the language of mathematics. Galileo was further stimulated by his experiments on the relation between musical tones and the length, weight, and tension of strings. His work on the centers of gravity of solids led to his appointment as the chair...