Galileo, Yesterday and Today

Looking at souvenirs from Galileo, physicists often wonder, “Who was the real Galileo?” What was his place in science? in philosophy? in history? in public affairs? A brief review is made here of the nature of historical evidence and its applicability to two famous Galileo incidents: the swinging lamp of Pisa and the leaning tower of Pisa. Some attention is given also to the question of historical myth, particularly in the case of Galileo. The author emphasizes Galileo's contributions to modern physics rather than his indebtedness to ancient philosophy. Galileo is first considered as a public figure; on the one hand, as a prominent person and, on the other hand, as a propagandist for the Copernican theory and for a phenomenological outlook. Galileo is regarded as a person, with particular concern for the “inevitability” of the celebrated Galileo case. The author, however, deals with Galileo as a physicist. His scientific approach is examined in terms of his experiential viewpoint, of his own behavior as an observer and a measurer, and of his role as a mathematical physicist, with particular interest in his use of models. Finally, Galileo's contributions to dynamics are reviewed: namely, his growing understanding of the first law of motion and his inklings as to the second law, with respect to acceleration but even more important with reference to role of the medium, as well as the relation of the projectile and tidal phenomena to Newton's first two corollaries. The author concludes that Galileo, the physicist, can rightly be regarded as the founder of dynamics.