He was probably the greatest scientific genius in the history of the world. He was certainly the greatest European scientist who lived between the time of Archimedes and that of Einstein. Before he was 24, Isaac Newton (1642-1727) had invented calculus, discovered the spectrum of light and wrote his Theory of Gravitation. The latter allegedly occurred to him while he was watching an apple fall from a tree. It is a tribute to his genius that he was able to develop such a complex, universal theory from an event so commonplace.
Newton also invented the reflector telescope, which differed from the simpler refractor type in that the light was reflected directly to the eye from a large, concave mirror via a small, flat mirror, without passing through glass.
In 1667, when he was 25, Newton was elected a fellow at Trinity College in Cambridge, England. It was while he was at Cambridge that he developed his Three Laws of Motion, the monumental achievement of a young life that had already experienced several major milestones. The Three Laws were:
Inertia: Every body, if left to itself, free of action of other bodies, will remain at rest if it is at rest, or it will continue to move at constant velocity if it is in motion.
Motion: The rate of change of the momentum of a body measures, in direction and magnitude, the force acting on it.
Reaction: For every action there is an equal and opposite reaction. In 1687, he published his Mathematical Principles of Natural Philosophy. In this work, known universally as the Principia (because it was written and originally published in Latin) Newton demonstrated the structure of the universe, the movement of
Sir Isaac Newton, English mathematician. the planets and calculated the mass of the Sun, the planets and their moons. Where Columbus and Magellan had proven that the Earth was spherical, Newton proved that the Earth is not a perfect sphere but rather an oblate spheroid—slightly flattened at the poles by the centrifugal force of its own rotation.
Like Marco Polo and Columbus expanded our ancestors' view of the geographical parameters of the world, Newton did more than anyone before (or since, until Albert Einstein) to help people understand the physical forces that govern all matter, from the stars in the sky to the apples on a backyard tree. The Principia was so complex that only serious scientists could understand it, but when they did, they agreed with the great English poet Alexander Pope (1688-1744) who wrote:
Nature and Nature's laws lay hid in night: God said, Let Newton be! and all was light.