Isaac Newton

Isaac Newton was an English polymath whose work spanned mathematics, physics, astronomy, alchemy, theology, writing, and invention. He played a central role in the Scientific Revolution and the Enlightenment. His 1687 work *Philosophiæ Naturalis Principia Mathematica* unified physics for the first time and laid the groundwork for classical mechanics.

In the *Principia*, Newton set out the laws of motion and universal gravitation. These principles dominated scientific thought for centuries, until relativity overtook them, but they remain accurate for everyday speeds and weak gravity. Using his mathematics, he explained Kepler’s planetary laws, tides, comet paths, the precession of the equinoxes, and confirmed that the Solar System is heliocentric. He solved the two-body problem and introduced the three-body problem, showing that the same rules govern objects on Earth and in the heavens. His prediction that Earth is an oblate spheroid was later verified by Maupertuis, Clairaut, La Condamine, and others, convincing most European scientists that Newtonian mechanics was superior to earlier systems. He also made the first experimental calculation of Earth’s age, described a forerunner of the modern wind tunnel, and produced the first quantitative estimate of the Sun’s mass.

Newton built the first reflecting telescope and developed a detailed theory of color, based on how a prism splits white light into the visible spectrum. He published these findings in *Opticks* in 1704. He pioneered the use of prisms as beam expanders and multiple-prism arrays, later key to tunable lasers. He also formulated an empirical law of cooling—the first heat transfer law, which underlies convective heat transfer—made the first theoretical calculation of the speed of sound, and introduced the concepts of a Newtonian fluid and a black body. He was the first to explain the Magnus effect and to analyze Couette flow. Beyond inventing calculus, Newton generalized the binomial theorem to any real number, introduced Puiseux series, first stated Bézout’s theorem, classified most cubic plane curves, contributed to Cremona transformations, developed a method for approximating function roots, originated the Newton–Cotes formulas for numerical integration, and gave the earliest explicit statement of the general Taylor series. He also started the field of calculus of variations, solved the first geometric probability problem, devised an early form of linear regression, and pioneered vector analysis.

Newton was a fellow of Trinity College and became the second Lucasian Professor of Mathematics at Cambridge at age 26. He was a devout but unorthodox Christian who privately rejected the Trinity doctrine and refused to take holy orders, unlike most Cambridge faculty. Besides his scientific work, he spent much time on alchemy and biblical chronology, though most of that remained unpublished until after his death. Politically aligned with the Whigs, he served two short terms as Member of Parliament for Cambridge University (1689–1690 and 1701–1702). Queen Anne knighted him in 1705. He spent his last three decades in London, as Warden (1696–1699) and then Master (1699–1727) of the Royal Mint, where he improved the accuracy and security of British coinage. He was also president of the Royal Society from 1703 until his death. He died at 84 and was the first scientist buried at Westminster Abbey.

Newton was born on Christmas Day 1642 (Julian calendar; 4 January 1643 New Style) at Woolsthorpe Manor in Lincolnshire. His father, also named Isaac, had died three months earlier. Born prematurely, he was tiny—his mother Hannah Ayscough said he could fit inside a quart mug. When he was three, his mother remarried the Reverend Barnabas Smith and moved away, leaving Newton with his maternal grandmother. He resented his stepfather and his mother for the marriage, as shown by a teenage confession: “Threatening my father and mother Smith to burn them and the house over them.” His mother had three more children from her second marriage.

From about age twelve to seventeen, Newton attended The King’s School in Grantham, where he learned Latin and Ancient Greek and likely gained a solid mathematical foundation. His mother pulled him out of school in October 1659 and sent him back to Woolsthorpe.