Galileo Galilei

Galileo Galilei (1564 – 1642) was an Italian scientist who was a major figure in the Scientific Revolution. He was a pioneer in the modern combination of mathematical theory with systematic experiment in science.

His work in physics included experimentation to establish the behavior of falling bodies, as well as the first modern theoretical work on inertia (for which he was given credit by Newton) and relativity of motion (for which he was credited by Einstein).

He was one of the first astronomers to use a telescope, and the discoverer or co-discoverer of several phenomena that contradicted the accepted ideas of the heavens. His support of the Copernican idea that the Earth rotates around the Sun led to a trial before the Inquisition on a suspicion of heresy.

Experimental science

Among the figures of the scientific revolution Galileo occupies a high position because of his pioneering use of quantitative experiments with results analyzed mathematically. There was no tradition of such methods in European thought at that time; the great experimentalist who immediately preceded Galileo, William Gilbert, did not use a quantitative approach. (However, Galileo's father, the musician Vincenzo Galilei, had performed experiments in which he discovered what may be the oldest known non-linear relation in physics, between the tension and the pitch of a stretched string.)

In the 20th century the reality of Galileo's experiments was challenged by some authorities, in particular the distinguished French historian of science Alexandre Koyré. The experiments reported in Two New Sciences to determine the law of acceleration of falling bodies, for instance, required accurate measurements of time, which appeared to have been impossible with the technology of 1600. According to Koyré, the law was arrived at deductively, and Galiileo's experiments, reported in some detail as if actually performed, were merely illustrative thought experiments.

Later research, however, has validated the experiments. The measurements on falling bodies (actually rolling balls) were replicated using the methods described by Galileo (Settle, 1961), and the precision of the results was consistent with Galileo's report. Later research into Galileo's unpublished working papers from as early as 1604 clearly showed the reality of the experiments and even indicated the particular results that led to the time-squared law (Drake, 1973).

References

• Drake, Stillman (1973). "Galileo's Discovery of the Law of Free Fall". Scientific American v. 228, #5, pp. 84-92.
• Settle, Thomas B. (1961). "An Experiment in the History of Science". Science, 133:19-23.