The origins of modern science(2)

                       Samir Okasha, Philosophy of Science, Oxford, 2002, 4~5

Taken together, Kepler¡¯s laws provided a far superior planetary theory than had ever been advanced before, solving problems that had confounded astronomers for centuries. Galileo was a life-long supporter of Copernicanism, and one of the early pioneers of the telescope. When he pointed his telescope at the heavens, he made a wealth of amazing discoveries, including mountains on the moon, a vast array of stars, sun-spots, and Jupiter¡¯s moons. All of these conflicted thoroughly with Aristotelian cosmology, and played a pivotal role in converting the scientific community to Copernicanism.

Galileo¡¯s most enduring contribution, however, lay not in astronomy but in mechanics, where he refuted the Aristotelian theory that heavier bodies fall faster than lighter ones. In place of this theory, Galileo made the counter-intuitive suggestion that all freely falling bodies will fall towards the earth at the same rate, irrespective of their weight (Figure 2). (Of course in practice, if you p a feather and a cannon-ball from the same height the cannon-ball will land first, but Galileo argued that this is simply due to air resistance - in a vacuum, they would land together.) Furthermore, he argued that freely falling bodies accelerate uniformly, i.e. gain equal increments of speed in equal times; this is known as Galileo¡¯s . of free-fall. Galileo provided persuasive though not totally Delusive evidence for this law, which formed the centrepiece of his theory of mechanics.

Figure 2 Sketch of Galileo¡¯s mythical experiment on the velocity of objects dropped from the Learning Tower of Pisa

Galileo is generally regarded as the first truly modern physicist. He the first to show that the language of mathematics could be used to describe the behaviour of actual objects in the material 'orld, such as falling bodies, projectiles, etc. To us this seems obvious - today¡¯s scientific theories are routinely formulated in mathematical language, not only in the physical sciences but also in biology and economics. But in Galileo¡¯s day it was not obvious: mathematics was widely regarded as dealing with purely abstract entities, and hence inapplicable to physical reality. Another innovative aspect of Galileo¡¯s work was his emphasis on the importance of testing hypotheses experimentally. To the modern scientist, this may again seem obvious. But at the time that Galileo was working, experimentation was not generally regarded as a reliable means of gaining knowledge. Galileo¡¯s emphasis on experimental testing marks the beginning of an empirical approach to studying nature that continues to this day.