Sir Isaac Newton was an English mathematician and natural philosopher, who is considered by many to be the greatest scientist that ever lived. Newton summarized his discoveries in terrestrial and celestial mechanics in his Philosophiae Naturalis Principia Mathematica [Mathematical Principles of Natural Philosophy] (1687), one of the greatest works in the history of science. In Book I of Principia, Newton defined the three laws of motion now known as Newton's laws (laws of inertia, action and reaction, and acceleration proportional to force). Book II presented Newton's new scientific philosophy that would replace Cartesianism. Book III presented the applications of his dynamics, including an explanation for tides and a theory of lunar motion. Newton also correctly formulated and solved the first ever problem in the calculus of variations. However, he did not publish his work on calculus until afterward Leibniz had published his. This produced a long-running feud between English and continental mathematicians that lasted for decades. Newton’s work surpassed all scientists that came before him, concisely stating simple yet elegant scientific principles and methods that applied to all branches of science. The Latin inscription on Newton's tomb reads,” Mortals! Rejoice at so great an ornament to the human race!"

Newton showed that the motions of objects on Earth and of celestial bodies are governed by the same set of natural laws by demonstrating the consistency between Kepler's laws of planetary motion and his theory of gravitation, thus removing the last doubts about heliocentrism and advancing the scientific revolution.

In mechanics, Newton enunciated the principles of conservation of both momentum and angular momentum. In optics, he built the first practical reflecting telescope and developed a theory of color based on the observation that a prism decomposes white light into the many color which form the visible spectrum. He also formulated an empirical law of cooling and studied the speed of sound. In mathematics, demonstrated the generalized binomial theorem, developed the so-called "Newton's method" for approximating the zeroes of a function, and contributed to the study of power series.

Sources

• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2008. "Newton, Isaac." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth September 20, 2006; Last revised December 1, 2008; Retrieved September 2, 2009]. 
• Wikipedia Contributors, Isaac Newton, Wikipedia The Free Encyclopedia, Accessed 2 September 2009.