| Themes > Science > Physics > About Physics, Generalities > A Brief History and Philosophy of Physics > The Renaissance (1300-1700) |
The rebirth ("Renaissance") of knowledge and learning in Europe, which followed the rediscovery of Greek and Arab learning, affected all of society. Awakened to the fact that there was so much "new" knowledge to be explored, people became free to invent their own. The arts flourished, with Durer inventing perspective drawing in Germany, Michelangelo studying anatomy to give life to his sculpture in Italy, and orchestral music being born. It saw the beginning of the Protestant Reformation in 1517, with Martin Luther nailing his 95 theses to the door of Wittenburg Cathedral. This was the period of the great European voyages of discovery, with Columbus arriving in America in 1492 and Magellan sailing around the tip of South America. Unfortunately, this period also saw the destruction of much of the learning of the peoples "discovered" by the Europeans, who still believed that non-Christian/European culture was valueless. This Eurocentrism is still active today, as witnessed by the almost complete omission of the great Central American civilizations from today's school curriculum in Canada. However, during the Renaissance Aquinas' integration of Greek, and particularly Aristotelian, philosophy with Catholic theology eventually led to as many problems for the church as it had solved. Copernicus' suggestion (about 1530) that the Earth and the other planets moved around the sun, rather than the reverse, was seen as heresy by the Church. Not only did it contradict Aristotle's teaching and several Biblical assertions that the Earth was stationary, it also challenged the authority of the Church by questioning the hierarchical structure on which its entire existence was based. If the Earth was not stationary at the centre of the universe, perhaps Heaven was not outside the sphere of the stars, and where did this leave God, not to mention all of His ecclesiastical delegates? The idea of a moving Earth was so revolutionary that Copernicus did not agree to have it published until he was on his death bed (1543). It is no surprise that the two people most responsible for the publishing of Copernicus' book were followers of Martin Luther, who had dared to question the authority of the Catholic church on scriptural matters. The Renaissance also saw the beginnings of modern science under Galileo Galilei (1564-1642). One of Galileo's greatest contributions was to recognize that the role of the scientist was not to explain "why" things happened as they do in nature, but only to describe them. In one of his "Dialogues" he asks a colleague why objects fall when released. When the colleague replies that everyone knows that gravity makes them fall, Galileo replies that he has not explained anything, just given it a name. This new role greatly simplified the work of the scientist, who no longer had to wonder why God would have caused a particular phenomenon to occur. It sufficed to recognize that it did occur, and allowed one to get on with the job of deciding how best to describe it. This leads us to Galileo's second major contribution, the description of natural phenomena using mathematics and the appeal to nature through experimentation to see if the description is correct. This was a major deviation from the qualitative science of Aristotle in which, for the most part, all that was required of an explanation was that it agreed qualitatively with reality: solid objects fell because they were composed of earthy material whose natural place was at the centre of the universe. In Galileo's science, on the other hand, one had to describe mathematically how far an object fell in a given time, and then verify experimentally that this description was correct. Moreover, he recognized that the experimenter had to devise the experiment so as to isolate the phenomenon being studied; for example, to minimize the effect of friction in the study of falling bodies. Galileo's most important applications of these ideas was in the mechanics of falling bodies, building on the early ideas of the impetus theorists. He showed that all compact bodies fell at the same rate, such that the distance covered was proportional to the square of the elapsed time of fall. Because objects in free fall drop too fast for easy measurement, Galileo did his measurements by rolling balls down an inclined plane. Even so, there were no clocks at the time accurate enough to make the measurements Galileo has recorded. (Galileo is, in fact, credited with the suggestion of using a pendulum as clock.) Stillman Drake, a Canadian who was one of the world's foremost scholar of Galileo, has noted that a person can keep time while singing with a precision of about 0.01 seconds. Drake shows that Galileo could have made his measurements by noting where the rolling ball was at each beat in a song [Drake, 1975]. Galileo is probably best known for his conflict with the Catholic church over his support for Copernicus' description of the solar system. When Galileo heard of the invention of the telescope, he designed and built one for himself. This, the first telescope usable for astronomical observations, quickly led Galileo to realize that Copernicus' theory was more than just an alternative to the Ptolemaic approach for calculating the positions of the planets. He saw that Jupiter had moons, and so was a miniature model of the solar system in itself; that Venus showed phases similar to those of the moon, as it must under the Copernican system; and that the moon had mountains and so was similar to the Earth. No wonder the church saw him as a threat! Galileo, aged sixty-eight, was tried by the Inquisition and sentenced to house arrest for the remainder of his life for daring to support Copernicus' theory, even though he recanted when faced with the death penalty. Ironically, he used this time to develop mechanics to the point at which it could explain why the planets would not fall into the sun if they were not held up by their "natural place". |
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