
Newton, Sir Isaac (16421727), mathematician and
physicist, one of the foremost scientific intellects of all time. Born at
Woolsthorpe, near Grantham in Lincolnshire, where he attended school, he entered
Cambridge University in 1661; he was elected a Fellow of Trinity College in
1667, and Lucasian Professor of Mathematics in 1669. He remained at the
university, lecturing in most years, until 1696. Of these Cambridge years, in
which Newton was at the height of his creative power, he singled out 16651666
(spent largely in Lincolnshire because of plague in Cambridge) as "the prime of
my age for invention". During two to three years of intense mental effort he
prepared Philosophiae Naturalis Principia Mathematica (Mathematical
Principles of Natural Philosophy) commonly known as the Principia,
although this was not published until 1687.
As a firm opponent of the attempt by King James II to make the
universities into Catholic institutions, Newton was elected Member of Parliament
for the University of Cambridge to the Convention Parliament of 1689, and sat
again in 17011702. Meanwhile, in 1696 he had moved to London as Warden of the
Royal Mint. He became Master of the Mint in 1699, an office he retained to his
death. He was elected a Fellow of the Royal Society of London in 1671, and in
1703 he became President, being annually reelected for the rest of his life.
His major work, Opticks, appeared the next year; he was knighted in
Cambridge in 1705.
As Newtonian science became increasingly accepted on the Continent, and especially after a general peace was restored in 1714, following the War of the Spanish Succession, Newton became the most highly esteemed natural philosopher in Europe. His last decades were passed in revising his major works, polishing his studies of ancient history, and defending himself against critics, as well as carrying out his official duties. Newton was modest, diffident, and a man of simple tastes. He was angered by criticism or opposition, and harboured resentment; he was harsh towards enemies but generous to friends. In government, and at the Royal Society, he proved an able administrator. He never married and lived modestly, but was buried with great pomp in Westminster Abbey.
Newton has been regarded for almost 300 years as the founding examplar of modern physical science, his achievements in experimental investigation being as innovative as those in mathematical research. With equal, if not greater, energy and originality he also plunged into chemistry, the early history of Western civilization, and theology; among his special studies was an investigation of the form and dimensions, as described in the Bible, of Solomon's Temple in Jerusalem.
II OPTICS
In 1664, while still a student, Newton read recent work on
optics and light by the English physicists Robert Boyle and Robert Hooke; he
also studied both the mathematics and the physics of the French philosopher and
scientist René Descartes. He investigated the refraction of light by a glass
prism; developing over a few years a series of increasingly elaborate, refined,
and exact experiments, Newton discovered measurable, mathematical patterns in
the phenomenon of colour. He found white light to be a mixture of infinitely
varied coloured rays (manifest in the rainbow and the spectrum), each ray
definable by the angle through which it is refracted on entering or leaving a
given transparent medium. He correlated this notion with his study of the
interference colours of thin films (for example, of oil on water, or soap
bubbles), using a simple technique of extreme acuity to measure the thickness of
such films. He held that light consisted of streams of minute particles. From
his experiments he could infer the magnitudes of the transparent "corpuscles"
forming the surfaces of bodies, which, according to their dimensions, so
interacted with white light as to reflect, selectively, the different observed
colours of those surfaces.
The roots of these unconventional ideas were with Newton by about 1668; when
first expressed (tersely and partially) in public in 1672 and 1675, they
provoked hostile criticism, mainly because colours were thought to be modified
forms of homogeneous white light. Doubts, and Newton's rejoinders, were printed
in the learned journals. Notably, the scepticism of Christiaan Huygens and the
failure of the French physicist Edmé Mariotte to duplicate Newton's refraction
experiments in 1681 set scientists on the Continent against him for a
generation. The publication of Opticks, largely written by 1692, was
delayed by Newton until the critics were dead. The book was still imperfect: the
colours of diffraction defeated Newton. Nevertheless, Opticks established
itself, from about 1715, as a model of the interweaving of theory with
quantitative experimentation.
III MATHEMATICS
In mathematics too, early brilliance appeared in Newton's
student notes. He may have learnt geometry at school, though he always spoke of
himself as selftaught; certainly he advanced through studying the writings of
his compatriots William Oughtred and John Wallis, and of Descartes and the Dutch
school. Newton made contributions to all branches of mathematics then studied,
but is especially famous for his solutions to the contemporary problems in
analytical geometry of drawing tangents to curves (differentiation) and defining
areas bounded by curves (integration). Not only did Newton discover that these
problems were inverse to each other, but he discovered general methods of
resolving problems of curvature, embraced in his "method of fluxions" and
"inverse method of fluxions", respectively equivalent to Leibniz's later
differential and integral calculus. Newton used the term "fluxion" (from Latin
meaning "flow") because he imagined a quantity "flowing" from one magnitude to
another. Fluxions were expressed algebraically, as Leibniz's differentials were,
but Newton made extensive use also (especially in the Principia) of
analogous geometrical arguments. Late in life, Newton expressed regret for the
algebraic style of recent mathematical progress, preferring the geometrical
method of the Classical Greeks, which he regarded as clearer and more rigorous.
Newton's work on pure mathematics was virtually hidden from all but his correspondents until 1704, when he published, with Opticks, a tract on the quadrature of curves (integration) and another on the classification of the cubic curves. His Cambridge lectures, delivered from about 1673 to 1683, were published in 1707.
A The Calculus Priority Dispute Newton had the essence of the methods of fluxions by 1666. The first to become known, privately, to other mathematicians, in 1668, was his method of integration by infinite series. In Paris in 1675 Gottfried Wilhelm Leibniz independently evolved the first ideas of his differential calculus, outlined to Newton in 1677. Newton had already described some of his mathematical discoveries to Leibniz, not including his method of fluxions. In 1684 Leibniz published his first paper on calculus; a small group of mathematicians took up his ideas.
In the 1690s Newton's friends proclaimed the priority of Newton's methods of fluxions. Supporters of Leibniz asserted that he had communicated the differential method to Newton, although Leibniz had claimed no such thing. Newtonians then asserted, rightly, that Leibniz had seen papers of Newton's during a London visit in 1676; in reality, Leibniz had taken no notice of material on fluxions. A violent dispute sprang up, part public, part private, extended by Leibniz to attacks on Newton's theory of gravitation and his ideas about God and creation; it was not ended even by Leibniz's death in 1716. The dispute delayed the reception of Newtonian science on the Continent, and dissuaded British mathematicians from sharing the researches of Continental colleagues for a century.
IV MECHANICS AND GRAVITATION
According to the wellknown story, it was on seeing an apple
fall in his orchard at some time during 1665 or 1666 that Newton conceived that
the same force governed the motion of the Moon and the apple. He calculated the
force needed to hold the Moon in its orbit, as compared with the force pulling
an object to the ground. He also calculated the centripetal force needed to hold
a stone in a sling, and the relation between the length of a pendulum and the
time of its swing. These early explorations were not soon exploited by Newton,
though he studied astronomy and the problems of planetary motion.
Correspondence with Hooke (16791680) redirected Newton to the problem of the path of a body subjected to a centrally directed force that varies as the inverse square of the distance; he determined it to be an ellipse, so informing Edmond Halley in August 1684. Halley's interest led Newton to demonstrate the relationship afresh, to compose a brief tract on mechanics, and finally to write the Principia.
Book I of the Principia states the foundations of the science of mechanics, developing upon them the mathematics of orbital motion round centres of force. Newton identified gravitation as the fundamental force controlling the motions of the celestial bodies. He never found its cause. To contemporaries who found the idea of attractions across empty space unintelligible, he conceded that they might prove to be caused by the impacts of unseen particles.
Book II inaugurates the theory of fluids: Newton solves problems of fluids in movement and of motion through fluids. From the density of air he calculated the speed of sound waves.
Book III shows the law of gravitation at work in the universe: Newton demonstrates it from the revolutions of the six known planets, including the Earth, and their satellites. However, he could never quite perfect the difficult theory of the Moon's motion. Comets were shown to obey the same law; in later editions, Newton added conjectures on the possibility of their return. He calculated the relative masses of heavenly bodies from their gravitational forces, and the oblateness of Earth and Jupiter, already observed. He explained tidal ebb and flow and the precession of the equinoxes from the forces exerted by the Sun and Moon. All this was done by exact computation.
Newton's work in mechanics was accepted at once in Britain, and universally after half a century. Since then it has been ranked among humanity's greatest achievements in abstract thought. It was extended and perfected by others, notably Pierre Simon de Laplace, without changing its basis and it survived into the late 19th century before it began to show signs of failing. See Quantum Theory; Relativity.
V ALCHEMY AND CHEMISTRY
Newton left a mass of manuscripts on the subjects of alchemy and
chemistry, then closely related topics. Most of these were extracts from books,
bibliographies, dictionaries, and so on, but a few are original. He began
intensive experimentation in 1669, continuing till he left Cambridge, seeking to
unravel the meaning that he hoped was hidden in alchemical obscurity and
mysticism. He sought understanding of the nature and structure of all matter,
formed from the "solid, massy, hard, impenetrable, movable particles" that he
believed God had created. Most importantly in the "Queries" appended to "Opticks"
and in the essay "On the Nature of Acids" (1710), Newton published an incomplete
theory of chemical force, concealing his exploration of the alchemists, which
became known a century after his death.
VI HISTORICAL AND CHRONOLOGICAL
STUDIES
Newton owned more books on humanistic learning than on
mathematics and science; all his life he studied them deeply. His unpublished
"classical scholia"—explanatory notes intended for use in a future edition of
the Principia—reveal his knowledge of preSocratic philosophy; he read
the Fathers of the Church even more deeply. Newton sought to reconcile Greek
mythology and record with the Bible, considered the prime authority on the early
history of mankind. In his work on chronology he undertook to make Jewish and
pagan dates compatible, and to fix them absolutely from an astronomical argument
about the earliest constellation figures devised by the Greeks. He put the fall
of Troy at 904 BC, about 500 years later than other scholars; this was not well
received.
VII RELIGIOUS CONVICTIONS AND PERSONALITY Newton also wrote on JudaeoChristian prophecy, whose decipherment was essential, he thought, to the understanding of God. His book on the subject, which was reprinted well into the Victorian Age, represented lifelong study. Its message was that Christianity went astray in the 4th century AD, when the first Council of Nicaea propounded erroneous doctrines of the nature of Christ. The full extent of Newton's unorthodoxy was recognized only in the present century: but although a critic of accepted Trinitarian dogmas and the Council of Nicaea, he possessed a deep religious sense, venerated the Bible and accepted its account of creation. In late editions of his scientific works he expressed a strong sense of God's providential role in nature.
VIII PUBLICATIONS
Newton published an edition of Geographia generalis by
the German geographer Varenius in 1672. His own letters on optics appeared in
print from 1672 to 1676. Then he published nothing until the Principia
(published in Latin in 1687; revised in 1713 and 1726; and translated into
English in 1729). This was followed by Opticks in 1704; a revised edition
in Latin appeared in 1706. Posthumously published writings include The
Chronology of Ancient Kingdoms Amended (1728), The System of the World
(1728), the first draft of Book III of the Principia, and Observations
upon the Prophecies of Daniel and the Apocalypse of St John (1733).
Contributed By:
Alfred Rupert Hall
"Sir Isaac Newton" Microsoft® Encarta®. Copyright © 1998 Microsoft Corporation.
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