Experiment!: Planning, Implementing and Interpreting

4.1 Galileo's Important Experiment

Galileo was born in Pisa in 1564, where he grew up in a musical family. His father, Vincenzio, was an esteemed lutist who also made controversial experiments with intonations, intervals, and tuning that challenged ancient authorities [1]. His brother became a professional musician and Galileo played the lute, just as his father. He entered the University of Pisa to study medicine, but soon switched to mathematics. Vincenzio's zest for experimentation seems to have rubbed off on Galileo, because when he got a position at the university in 1589, he began to study the motion of falling bodies.

According to Aristotle, bodies fell at a constant speed that was proportional to their weight. Since free fall typically occurs very fast it is difficult to form an idea of it from direct observation. To be able to study it at all, Aristotle had evidently slowed objects down by letting them fall in water [1]. He had concluded that, in the absence of a resisting medium such as water or air, the speed of fall would be infinite. In Aristotle's view of the world, things fell because they sought their natural place at the center of the universe. He thereby made a difference between the “natural”, downward motion of falling objects and “violent”, upward motion that he considered contrary to nature.

Galileo showed by thought experiment that Aristotle was wrong in thinking that the speed of fall was proportional to the weight of the falling object. If we suppose that ...