Isaac Newton

English physicist

• Born: December 25, 1642 (new style, January 4, 1643)
• Birthplace: Woolsthorpe Manor, near Colsterworth, Lincolnshire, England
• Died: March 31, 1727
• Place of death: London, England

Newton’s theory of gravitation and laws of mechanics described, for the first time, a natural world governed by immutable physical laws. In addition to creating a conceptual framework that underlay the practice of science until the twentieth century, Newton’s understanding of the world in terms of natural laws profoundly affected the history of ideas and the practice of philosophy in the modern era.

Early Life

Sir Isaac Newton was born on Christmas Day, 1642, to a farmer and his wife, at Woolsthorpe Manor, just south of Grantham in Lincolnshire. His father died shortly before Newton’s birth, and when his mother remarried three years later and moved away to live with her new husband, Newton remained at Woolsthorpe to be reared by his grandparents.

Newton attended the grammar school in Grantham, and he demonstrated scientific aptitude at an early age, when he began to construct mechanical toys and models. Aside from a brief period when his mother tried to persuade him to follow in his father’s footsteps and become a farmer, his education continued (it is said that Newton tended to read books rather than watch sheep, with disastrous results). He was accepted as an undergraduate at Trinity College, Cambridge, in 1661.

Although his mother provided a small allowance, Newton had to wait on tables at college to help finance his studies. Even at that time, his fellow students remarked that he was silent and withdrawn, and indeed, Newton throughout his life was something of a recluse, shunning society. He never married, and some historians believe that Newton had homosexual leanings. Whatever the truth of this speculation, it is certain that he preferred work, study, experimentation, and observation to social activity, sometimes to the detriment of his own health. After retreating to Grantham for a short time while Cambridge was threatened by plague, Newton returned to the university as a don in 1667 with an established reputation for mathematical brilliance.

Life’s Work

It was not long at all before Newton proved his reputation for genius to be well deserved. Shortly after his graduation, Newton developed the differential calculus, a mathematical method for calculating rates of change (such as acceleration) that had long evaded other scholars. As a result, in 1669, he was offered the Lucasian Chair of Mathematics at Cambridge, a position he held until 1701.

Newton’s second major contribution of this period was in the field of optics. His experiments with light had led him to build a reflecting telescope, the first one of its kind that actually worked. After further refinements, he presented the device to the Royal Society, where he was asked to present a paper on his theory of light and colors. Shortly afterward, he was made a fellow of this august body, which contained all the prominent intellectuals of the day.

Newton’s paper offered new insights into the nature of color. While experimenting with prisms, Newton had discovered that white light is a mixture of all the colors of the rainbow and that the prism separates white light into its component parts. Newton’s theory was controversial, provoking strong feelings at the Royal Society and initiating a lengthy dispute with Robert Hooke concerning the nature of light. Hooke criticized Newton with such vehemence that Newton presented no more theories on the nature of light until 1704, after Hooke’s death.

For a scientist such as Newton, the seventeenth century was an interesting period in which to work. Scientific thought was still dominated by the Aristotelian worldview, which had held sway for more than two thousand years, but cracks in that outlook were beginning to appear. Galileo had shown that the planets traveled around the Sun, which was positioned at the center of the universe, while Johannes Kepler had observed that this motion was regular and elliptical in nature. The task confronting scientists, in keeping with the aim of explaining the universe mathematically from first principles, was to find some logical reason for this phenomenon.

Newton, among others, believed that there had to be a set of universal rules governing motion, equally applicable to planetary and earthbound activity. His researches finally led him to a mathematical proof that all motion is regulated by a law of attraction. Specifically, he proved that the force of attraction between two bodies of constant mass varies as the inverse of the square of the distance between those bodies (that is, F_A = k/D², where F_A is the force of attraction between the bodies, D is the distance between them, and k is a constant). From this beginning, he was able to explain why planets travel in ellipses around the Sun, why Earth’s tides move as they do, and why tennis balls, for example, follow the trajectories that they do. The inverse square formula also led Newton toward a notion of gravity that neatly tied his mathematics together. When Newton published this work, it led to another major confrontation with Hooke, who claimed that he had reached the proof of the inverse square law before Newton; the argument between the two was lengthy and acrimonious.

In 1684, Edmond Halley, then a young astronomer, went to Cambridge to visit Newton, who was reputed to be doing work similar to Halley’s. Halley found that Newton claimed that he had proved the inverse square law but had temporarily mislaid it. (Throughout his life, Newton worked on scraps of paper, keeping everything from first drafts to final copies, so this assertion has the ring of truth to it.) Halley was astounded: Here was a man who claimed to have solved the problem that was bothering many leading scientists of the day, and he had not yet made it public. When Halley returned, Newton had found the proof, and Halley persuaded him to publish his nine-page demonstration of the law. Still, Halley was not satisfied. Realizing that Newton had more to offer the world, he prodded him into publishing a book of his theories. The result was the famous Philosophiae Naturalis Principia Mathematica (1687; The Mathematical Principles of Natural Philosophy, 1729, best known as the Principia), which was published at Halley’s expense. A year later, a second and third volume of the work reached the public.

The Principia was a highly technical and mathematical work that many of Newton’s contemporaries had difficulty following, but its effect on the scientific community was profound. In it, Newton outlined his three laws of motion. The first states that every body continues in a state of rest or motion until it is acted on by a force. The second law states that the acceleration of a body is proportional to the force applied to it and inversely proportional to its mass. The third law, perhaps the most widely quoted, states that for every action there is an equal and opposite reaction. From these three fundamental laws, Newton went on to construct his theory of gravity—a force that acts at a distance between two or more bodies, causing an attraction between them that is in inverse proportion to the distance between them.

Newton’s theories were a major challenge to the dominant worldview, constructing the world, as they did, purely from mechanics. His theories seemed revolutionary and initiated a great debate, which continued for the better part of a century after the Principia was published. When they were eventually accepted as a useful description of nature, Newtonian science formed the basis of modern thinking until the twentieth century, when Albert Einstein’s theories turned the world upside down again.

Writing the Principia dominated Newton’s life to such an extent that he became completely obsessed with the project, often forgetting to eat or even to sleep while he continued working. Despite his reclusive tendencies, however, in 1687 Newton entered the public arena. Cambridge University and King James II, a Catholic, were in the midst of a battle over religion. The university had refused to grant a degree to a Benedictine monk, and the officials of the university, including Newton, were summoned to appear before the infamous Judge George Jeffreys to argue their case. Shortly afterward, Newton was elected the member of Parliament for Cambridge. Newton’s entrance into politics was less than world-shattering, though; it is said that he spoke only once during his term of office, and that was to ask an usher to open a window.

In 1693, Newton suffered a mental breakdown about which little is known, and he withdrew into his previous solitary state. Two years later, he returned to public office when he was asked to take over the wardenship of the mint. There was to be a major reissue of coinage because of the increasingly pressing problem of clipped gold and silver coins. New coins needed to be minted with milled edges, and several prominent scientists were pressed into service to aid in the process. Newton discovered a hitherto unrecognized penchant for administration and proved himself a highly able bureaucrat, being promoted to master of the Mint in 1699. In 1701, he was reelected to Parliament and continued in the public eye for the remainder of his life.

Until his death in 1727, honors were heaped upon Newton, as befitted the most prominent scientist of his generation. In 1703, he was elected president of the Royal Society and was annually reelected to that post for the next twenty-five years. He moved to London and became more sociable but nevertheless earned a reputation for being cantankerous and ill-tempered. In 1704, Newton published Opticks, a tract about the theories of light that he had earlier expounded to the Royal Society. It was more accessible than the Principia and gained a wider audience. A year later, he was knighted by Queen Anne. Meanwhile, the Principia was proving to be a best-seller, as everyone wanted to read the theories that were pushing back the frontiers of contemporary science, and it went through second and third editions during Newton’s lifetime.

Newton’s work in the last years of his life was mainly religious, apart from another acrimonious dispute with the German philosopher Gottfried Wilhelm Leibniz over who had first invented the differential calculus. Newton spent hours attempting to understand the messages hidden in the Book of Revelation, seeing this task as simply another aspect of the search for truth as revealed in God’s works, both written and created. Thus, in the end, Newton proved himself to be a medieval thinker, despite his work laying the foundations of modern scientific thought.

Significance

Newton made an outstanding contribution to the modernization of the Western scientific worldview. He followed in the footsteps of Nicolaus Copernicus, Galileo, Kepler, and others in asserting that the heavens and earth were a part of one solar system (not separated as they are in Aristotelian philosophy), with the Sun at the center. Newton further developed and refined the method of observation and experiment that had already established itself in the seventeenth century, by carefully checking and rechecking his work and by creating experimental verifications of his various theories. Most important, he demonstrated that a comprehensive mechanical description of the world that explained matter and motion in terms of mathematics was actually possible. With the Principia, Newton effectively sounded the death knell of the old description of the universe and laid the basis for a modern approach. His was perhaps the greatest individual contribution to a rich and innovative period of scientific development.

Newton’s Major Works

1687

• Philosophiae Naturalis Principia Mathematica (The Mathematical Principles of Natural Philosophy, 1729)

1704

• Opticks

1707

• Arithmetica Universalis (Universal Arithmetick, 1720)

1711

• Analysis per Quantitatum Series, Fluxiones, ad Differentias: Cum Enumeratione Linearum Tertii Ordinis (includes De Analysi per Aquationes Infinitas; Fragmenta Epistolarum; De Quadratura Curvarum; Enumeratio Linearum Tertii Ordinis; and Methodus Differentialis)

1728

• The Chronology of Ancient Kingdoms Amended

1733

• Observations upon the Prophecies of Daniel and the Apocalypse of St. John

1736

• The Method of Fluxions and Infinite Series

Bibliography

Aughton, Peter. Newton’s Apple: Isaac Newton and the English Scientific Revolution. London: Weidenfeld, 2003. Print.

Brewster, Sir David. Memoirs of the Life, Writings, and Discoveries of Sir Isaac Newton. Edinburgh: Constable, 1855. Reprint. New York: Johnson Reprint, 1965. Print.

Christianson, Gale E. In the Presence of the Creator: Isaac Newton and His Times. New York: Free, 1984. Print.

Cohen, I. Bernard, and George E. Smith, eds. The Cambridge Companion to Newton. New York: Cambridge UP, 2002. Print.

Fara, Patricia. Newton: The Making of a Genius. New York: Columbia UP, 2002. Print.

Gleick, James. Isaac Newton. New York: Pantheon, 2003. Print.

Koyré, Alexandre. From the Closed World to the Infinite Universe. Baltimore: Johns Hopkins UP, 1957. Print.

Koyré, Alexandre. Newtonian Studies. Cambridge: Harvard UP, 1965. Print.

Manuel, Frank E. A Portrait of Isaac Newton. Cambridge: Harvard UP, 1968. Reprint. New York: Da Capo, 1990. Print.

Newton, Sir Isaac. Mathematical Principles of Natural Philosophy and His System of the World: Principia. 2 vols. Berkeley: U of California P, 1934. Reprint. 1962. Print.

Newton, Sir Isaac. Opticks. New York: Dover, 1952. Print.

Westfall, Richard S. Never at Rest: A Biography of Isaac Newton. New York: Cambridge UP, 1980. Print.