Galileo

It is with regard to the muddle of contemporary thought, that of " gravity " and " levity," that Galileo is most clearly revealed as the first of an illustrious line, the line of mathematical physicists ; of men able to analyse their experiments by means of their mathematics.

His experiments had begun in 1583. They reached a climax about 1588-91. Criticism now denies his demonstrations from the Leaning Tower of Pisa, in which he was thought to have shown that bodies of different weights fall (apart from an obvious correction for air resistance) at the same rates. Whatever experiments he did perform seem to have been convincing enough to rouse the " Aristotelian " orthodoxy. This latter was committed to the view that bodies move faster in proportion to their weights.

Galileo's mathematics came to the fore in a practical as well as theoretical sense in his use of the inclined plane and the pendulum to give greater precision to his proofs ; since freely falling bodies move too fast to be directly observable. He rediscovered the fact that a reasonably wide pendulum swing takes no longer than a very narrow one. He then showed mathematically how this implies that " gravity " is increasing the speed of the bob by equal amounts in equal times. This, also, was contrary to the orthodoxy of the time.

Galileo has also left us with experimental evidence that the acceleration produced by gravity is independent of the mass or weight of the body concerned.