Newton, Sir Isaac 1642-1727. English mathematician and scientist. He invented a form of calculus and formulated principles of physics that remained basically unchallenged until the work of Albert Einstein, including the law of universal gravitation, a theory of the nature of light, and three laws of motion. His treatise on gravitation, presented in Principia Mathematica (1687), was in his own account inspired by the sight of a falling apple.
Our Living Language: The British mathematician and physicist Sir Isaac Newton stands as one of the greatest scientists of all time. Newton spent most of his working life at Cambridge University. In 1665, the year he received his bachelor's degree, an outbreak of the bubonic plague caused Cambridge to close for two years. Newton returned to his family home in Lincolnshire and, working alone, did some of his most important scientific work. Perhaps his greatest achievement was to demonstrate that scientific principles have universal applications. His universal law of gravitation states that there is an attractive force acting between all bodies in the universe. According to the famous—and possibly true—story, he observed an apple falling from a tree and, remarkably, connected the force drawing the apple to the ground with that keeping the Moon in its orbit. Along with his law of gravitation, Newton's three laws of motion, which laid the basis for the science of mechanics, bridged the gap between scientific thinking about terrestrial and celestial dynamics. The laws are: (1) A body at rest or moving in a straight line will continue to do so unless acted upon by an external force; (2) The acceleration of a moving object is proportional to and in the same direction as the force acting on it and inversely proportional to the object's mass; and (3) For every action there is an equal and opposite reaction. For nearly 400 years these laws have remained unchallenged; even Einstein's Theory of Relativity is consistent with them. Newton stated his laws of motion in his 1687 masterpiece, the Principia Mathematica, in which he also introduced his formulation of the calculus (what we now call simply "calculus," a different version of which was simultaneously developed by Leibnitz). In optics, Newton demonstrated that white light contains all the colors of the spectrum and provided strong evidence that light was composed of particles.