Revolution in Astronomy, Physics and Mathematics
Between about 1550 and 1700, knowledge and understanding of the sciences underwent colossal upheavals as ideas sanctioned by the Christian Church were challenged.
This challenge became inevitable once astronomers, mathematicians and physicists began to realize that the facts of science and Nature which they could observe did not fit concepts that were considered to be true in their time.
The Renaissance and Fundamental Change
This fundamental change occurred during the Renaissance, the revival of ancient arts and learning that began in around 1450 and reintroduced the ideas prevalent in the ancient world..Despite the fact that the ancient practitioners had been pagans, the Church promoted their teachings.
One ancient philosospher whose theories received Church support was Aristotle, who lived in Greece in the 4th century BC. Aristotle taught that the Earth was flat and never moved in the Heavens. Furthermore, Aristotle claimed, the Sun and planets orbited the Earth and the starry heavens, which never changed, were composed of crystalline spheres.
These ideas were turned upside down by the work of astronomers such as the Polish priest Niklaus Copernicus, the Danish Tycho Brahe and the German Johannes Kepler.
Copernicus, Brahe and Kepler versus Aristotle
Copernicus put forward the theory that the Earth was round, not flat; it certainly moved, in orbit round the Sun, while the Sun, not the Earth, was the centre of the Universe. After the invention of the telescope in 1608, the Italian Galileo Galilei was able to make observations of the sky which proved Copernicus’ heliocentric theory.
As for Aristotle’s crystalline spheres, in 1577, Tycho Brahe observed a comet which was moving freely in the regions around the planets. That would have been impossible had the spheres really existed. Tycho also saw the apparently immutable heavens change before his eyes, when he observed a star going nova, exploding at an immense distance from Earth.
Johannes Kepler used Tycho’s work as the basis for his three planetary laws, which he formulated in 1609-1610. These laws set down ideas about the motion, speed and orbits of the planets and suggested that they belonged to one system; this later became known as the Solar System.
New Scientific Instruments and Methods
All this totally contradicted the theories of Aristotle and with that, the teachings of the Church. However, despite Church disapproval of the new science, the new scientists continued to investigate, experiment and observe. A whole new range of instruments and aids helped them. These instruments included the compound microscope of 1590, the thermometer of around 1611, and the barometer of 1643.
Keeping scientific records became much simpler after the language of mathematics was created in the 16th century. Calculations could now be expressed with plus, minus, multiplication, division and equals signs. Logarithms enabled astronomers to handle an increasing load of complex calculations.
Calculus, a new method of reckoning, was the most important new tool of mathematicians in the 17th century, It was of particular value in the science of ballistics and in helping astronomers investigate continuous change in the heavens. Calculus was devised independently by Gottfried Leibniz, the German philosopher and mathematician and by the English philosopher Sir Isaac Newton.
Principia, Book of the New Science
In 1687, Newton published his Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) in which he set down the chief elements of the new scientific thought.
They included Galileo’s ideas about dynamics, Christian Huygens’ theory of centrifugal force, Kepler’s theory of the Moon’s gravitational pull, and the theory of the French mathematician René Descartes that all particles in motion move in a straight line.
Principia also outlined Newton’s own System of the World, in which all things obeyed three laws of motion and all exerted and were affected by gravity.