Experiment!: Planning, Implementing and Interpreting

4.3 Reconstructing the Experiment

Koyré leaves us with a couple of central questions. Could Galileo have conducted the experiment with his limited means? And was the aim really to measure the acceleration of gravity? In response to the criticism, Thomas Settle reconstructed the Galilean experiment in 1961. Then a graduate student in the history of science, he staged the experiment in the common living room he shared with other students [1]. The purpose was to get a better appreciation for some of the problems that Galileo had faced. Both the equipment and the procedures were kept as close as possible to Galileo's description in Two New Sciences. It turned out that he could easily reproduce the results with the precision claimed by Galileo [3].

Settle points out that Koyré had fundamentally misunderstood the purpose of the experiment. It was true that Galileo's apparatus was not capable of establishing the gravitational constant, but he was not trying to do that. He was interested in the ratios given in Equation 4.1. He was thereby not dependent on measuring time in standard units and could be completely arbitrary in his choice of measures. Furthermore, there had been little justice in Koyré's criticism of Galileo failing to account for the rotational inertia of the ball. Not only did this problem not exist in his mind, in this experiment it was even irrelevant. As the factor that accounts for rotational inertia is a constant, it does not affect the proportionalities of the law. ...