Scientific Revolution

This article is about the period in history, not the process of scientific progress via revolution, proposed by Thomas Kuhn and discussed at paradigm shift

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The Scientific Revolution is the name given by historians of science to the period that roughly began with the discoveries of Kepler at the dawn of the 17th century, and ended with the publication of the Philosophiae Naturalis Principia Mathematica in 1687 by Isaac Newton. These boundaries are not uncontroversial, with some claiming that the proper start of the Scientific Revolution was the publication of De revolutionibus orbium coelestium by Nicolaus Copernicus in 1543, while others wish to extend it into the 18th century. Nevertheless, the basic themes of the revolution are readily recognised.

The seventeenth century was a period of major scientific change. Not only were there major theoretical and experimental developments, but even more importantly, the way in which scientists worked was radically changed. At the beginning of the century, science was highly Aristotelian; at its end, science was mathematical, mechanical and empirical.

In fact, according to the modern definition of the term science, true science itself did not exist before the 17th century at all.

Table of contents 1 Theoretical developments 2 Experimental developments 3 Methodological developments 3.1 Mechanisation 3.2 Mathematisation 3.3 Empiricism

Theoretical developments

In 1543 Copernicus' work on the Heliocentric model of the solar system was published, in which he tried to prove that the sun was the centre of the universe. For almost two millennia, the Geocentric model had been accepted by all but a few astronomers. The idea that the earth moved around the sun, as advocated by Copernicus, was to most of his contemporaries preposterous. It contradicted not only the virtually unquestioned Aristotelian philosophy, but also common sense. For suppose the earth turns about its own axis. Then, surely, if we were to drop a stone from a high tower, the earth would rotate beneath it while it fell, thus causing the stone to land some space away from the tower's bottom. This effect is not observed.

It is no wonder, then, that although some astronomers used the Copernican system to calculate the movement of the planets, only a handful actually accepted it as true theory. It took the efforts of two men, Johannes Kepler and Galileo Galilei, to give it credibility. Kepler was a brilliant astronomer who, using the very accurate observations of Tycho Brahe, realised that the planets move around the sun not in circular orbits, but in elliptical ones. Together with his other laws of planetary motion, this allowed him to create a model of the solar system that was a huge improvement over Copernicus' original system. Galileo's main contributions to the acceptance of the heliocentric system were his mechanics and the observations he made with his telescope. Using a primitive notion of inertia, Galileo could explain why rocks dropped from a tower fall straight down even if the earth rotates. His observations of the moons of Jupiter, the phases of Venus and the spots on the moon all helped to discredit the Aristotelian philosophy and the Ptolemaic theory of the solar system. Through their combined discoveries, the heliocentric system gained more and more support, and at the end of the 17th century it was generally accepted by astronomers.

Both Kepler's laws of planetary motion and Galileo's mechanics culminated in the work of Isaac Newton. His laws of motion were to be the solid foundation of mechanics; his law of universal gravitation combined terrestrial and celestial mechanics into one great system that seemed to be able to describe the whole world in mathematical formulae.

Not only astronomy and mechanics were greatly changed. Optics, for instance, was revolutionised by people like Robert Hooke, Christiaan Huygens and, once again, Isaac Newton, who developed mathematical theories of light as either waves (Huygens) or particles (Newton). Similar developments could be seen in chemistry, biology and other sciences.

Experimental developments

There were also some very important changes in experimental technology that were to revolutionise the scientific enterprise. The development of telescopes by Galileo and others greatly expanded the accuracy and range of celestial observations. The emerging technology of the microscope brought the world of the very small within reach of the human observer, although it would take an additional two centuries before the instrument was perfected. Another notable invention was the air-pump, extensively used by Robert Boyle and others.

Methodological developments

Yet most important were the changes in the way science was done. Three main developments can be identified: the mechanisation of nature, the mathematisation of nature, and the rise of the experimental philosophy.

Mechanisation

Aristotle recognised four kinds of causes, of which the most important was the 'final cause'. The final cause was the aim or goal of something. Thus, the final cause of rain was to let plants grow. Until the scientific revolution, it was very natural to see such goals in nature. The world was inhabited by angels and demons, spirits and souls, occult powers and mystical principles. Scientists spoke about the 'soul of a magnet' as easily as they spoke about its velocity. The rise of the so-called 'mechanical philosophy' put a stop to this. The mechanists, of whom the most important one was Rene Descartes, rejected all goals, emotion and intelligence in nature. The world consisted of matter moving in accordance with strict laws. Where nature had been like a living entity, the scientific revolution turned her into a machine.

Mathematisation

Aristotelian science had been qualitative, not quantitative. Astronomy had always been quantitative, of course, but it was seen as a lower discipline, subjected to physics. In physics, mathematics wasn't used. And why should it? As Aristotle had pointed out, physics was about changing objects with a reality of their own, whereas mathematics was about unchanging objects without a reality of their own. What could they have to do with each other? During the scientific revolution, the status of mathematics was radically changed, and at the end of the 17th century physics was thoroughly mathematised. As always in history, many factors together caused this development, but both the evident successes of Galileo and other mathematically inclined physicists and the growing tendency to realistically interpret mathematical models like the Copernican system were among the key factors.

Empiricism

Look at the world, but don't experiment!, such was the view of the natural philosophers before the scientific revolution. Nature, it was thought, should be looked at as it worked on its own. If one did an experiment, one was putting nature in 'unnatural' circumstances, and hence the results of an experiment would not agree with the true way nature worked. Under the influence of philosophers like Francis Bacon, an empirical tradition was developed in the 17th century. The Aristotelian belief of natural and artificial circumstances was abandoned, and a research tradition of systematic experimentation was slowly accepted throughout the scientific community.

At the end of the scientific revolution the organic, quantitative world of book-reading philosophers had been changed into a mechanical, mathematical world to be known through experimental research. Though it is certainly not true that Newtonian science was like modern science in all respects, it closely resembled ours in many ways - much more so than the Aristotelian science of a century earlier.