Physicist and mathematician. Born
January 4, 1643 (some sources say December 25, 1642) in
Woolsthorpe, a hamlet in southwestern Lincolnshire, England.
When Newton was a child, Lincolnshire was a battleground of the
civil wars, in which religious dissension and political
rebellion was dividing England's population. Also of
significance for his early development were circumstances within
his family. He was born after the death of his father, and in
his third year his mother married the rector of a neighboring
parish and left her son at Woolsthorpe in the care of his
grandmother.
After a rudimentary education in local schools, he was sent at
the age of 12 to the King's School in Grantham, where he lived
in the home of an apothecary named Clark. It was from Clark's
stepdaughter that Newton's biographer William Stukeley learned
many years later of the boy's interest in her father's chemical
library and laboratory and of the windmill run by a live mouse,
the floating lanterns, sundials, and other mechanical
contrivances Newton built to amuse her. Although she married
someone else and he never married, she was the one person for
whom Newton seems to have had a romantic attachment.
At birth Newton was heir to the modest estate which, when he
came of age, he was expected to manage. But during a trial
period midway in his course at King's School, it became apparent
that farming was not his metier. In 1661, at the age of 19, he
entered Trinity College, Cambridge. There the questioning of
long-accepted beliefs was beginning to be apparent in new
attitudes toward man's environment, expressed in the attention
given to mathematics and science After receiving his bachelor's
degree in 1665, apparently without special distinction, Newton
stayed on for his master's; but an epidemic of the plague caused
the university to close. Newton was back at Woolsthorpe for 18
months in 1666 and 1667. During this brief period he performed
the basic experiments and apparently did the fundamental
thinking for all his subsequent work on gravitation and optics
and developed for his own use his system of calculus. The story
that the idea of universal gravitation was suggested to him by
the falling of an apple seems to be authentic: Stukeley reports
that he heard it from Newton himself.
Returning to Cambridge in 1667, Newton quickly completed the
requirements for his master's degree and then entered upon a
period of elaboration of the work begun at Woolsthorpe. His
mathematics professor, Isaac Barrow, was the first to recognize
Newton's unusual ability, and when, in 1669, Barrow resigned to
devote himself to theology, he recommended Newton as his
successor. Newton became Lucasian professor of mathematics at 27
and stayed at Trinity in that capacity for 27 years.
Newton's main interest at the time of his appointment was
optics, and for several years the lectures required of him by
the professorship were devoted to this subject. In a letter of
1672 to the secretary of the Royal Society, he says that in 1666
he had bought a prism "to try therewith the celebrated phenomena
of colours. He continues, "In order thereto having darkened the
room and made a small hole in my window-shuts to let in a
convenient quantity of the Suns light, I placed my prism at its
entrance, that it might be thereby refracted to the opposite
wall." He had been surprised to see the various colors appear on
the wall in an oblong arrangement (the vertical being the
greater dimension), "which according to the received laws of
refraction should have been circular." Proceeding from this
experiment through several stages to the "crucial" one, in which
he had isolated a single ray and found it unchanging in color
and refrangibility, he had drawn the revolutionary conclusion
that "Light itself is a heterogeneous mixture of differently
refrangible rays."
These experiments had grown out of Newton's interest in
improving the effectiveness of telescopes, and his discoveries
about the nature and composition of light had led him to believe
that greater accuracy could not be achieved in instruments based
on the refractive principle. He had turned, consequently, to
suggestions for a reflecting telescope made by earlier
investigators but never tested in an actual instrument. Being
manually dexterous, he built several models in which the image
was viewed in a concave mirror through an eyepiece in the side
of the tube. In 1672 he sent one of these to the Royal Society.
Newton felt honored when the members were favorably impressed by
the efficiency of his small reflecting telescope and when on the
basis of it they elected him to their membership. But when
this warm reception induced him to send the society a paper
describing his experiments on light and his conclusions drawn
from them, the results were almost disastrous for him and for
posterity. The paper was published in the society's
Philosophical Transactions, and the reactions of English and
Continental scientists, led by Robert Hooke and Christiaan
Huygens, ranged from skepticism to bitter opposition to
conclusions which seemed to invalidate the prevalent wave theory
of light.
At first Newton patiently answered objections with further
explanations, but when these produced only more negative
responses, he finally became irritated and vowed he would never
publish again, even threatening to give up scientific
investigation altogether. Several years later, and only through
the tireless efforts of the astronomer Edmund Halley, Newton was
persuaded to put together the results of his work on the laws of
motion, which became the great Principia.
Newton's magnum opus, Philosophiae naturalis principia
mathematica, to give it its full title, was completed in an
astonishing 18 months. It was first published in Latin in 1687,
when Newton was 45. Its appearance established him as the
leading scientist of his time, not only in England but
throughout the Western world. In the Principia Newton
demonstrated for the first time that celestial bodies follow the
laws of dynamics and, formulating the law of universal
gravitation, gave mathematical solutions to most of the problems
concerning motion which had engaged the attention of earlier and
contemporary scientists. Book 1 treats the motion of bodies in
purely mathematical terms. Book 2 deals with motion in resistant
mediums, that is, in physical reality. In Book 3, Newton
describes a cosmos based on the laws he has established. He
demonstrates the use of these laws in determining the density of
the earth, the masses of the sun and of planets having
satellites, and the trajectory of a comet; and he explains the
variations in the moon's motion, the precession of the
equinoxes, the variation in gravitational acceleration with
latitude, and the motion of the tides. What seems to have been
an early version of book 3, published posthumously as The System
of the World, contains Newton's calculation, with illustrative
diagram, of the manner in which, according to the law of
centripetal force, a projectile could be made to go into orbit
around the earth.
In the years after Newton's election to the Royal Society, the
thinking of his colleagues and of scholars generally had been
developing along lines similar to those which his had taken, and
they were more receptive to his explanations of the behavior of
bodies moving according to the laws of motion than they had been
to his theories about the nature of light. Yet the Principia
presented a stumbling block: its extremely condensed
mathematical form made it difficult for even the most acute
minds to follow. Those who did understand it saw that it needed
simplification and interpretation. As a result, in the 40 years
from 1687 to Newton's death the Principia was the basis of
numerous books and articles. These included a few peevish
attacks, but by far the greater number were explanations and
elaborations of what had subtly evolved in the minds of his
contemporaries from "Mr. Newton's theories" to the "Newtonian
philosophy."
The publication of the Principia was the climax of Newton's
professional life. It was followed by a period of depression and
lack of interest in scientific matters. He became interested in
university politics and was elected a representative of the
university in Parliament. Later he asked friends in London to
help him obtain a government appointment. The result was that in
1696, at the age of 54, he left Cambridge to become warden and
then master of the Mint. The position was intended to be
something of a sinecure, but he took it just as seriously as he
had his scientific pursuits and made changes in the English
monetary system that were effective for 150 years.
Newton's London life lasted as long as his Lucasian
professorship. During that time he received many honors,
including the first knighthood conferred for scientific
achievement and election to life presidency of the Royal
Society. In 1704, when Huygens and Hooke were no longer living,
he published the Opticks, mainly a compilation of earlier
research, and subsequently revised it three times; he supervised
the two revisions of the Principia; he engaged in the
regrettable controversy with G. W. von Leibniz over the
invention of the calculus; he carried on a correspondence with
scientists all over Great Britain and Europe; he continued his
study and investigation in various fields; and, until his very
last years, he conscientiously performed his duties at the Mint
In the interval between publication of the Principia in 1687 and
the appearance of the Opticks in 1704, the trend was away from
the use of Latin for all scholarly writing. The Opticks was
written and originally published in English (a Latin translation
appeared 2 years later) and was consequently accessible to a
wide range of readers in England. The reputation which the
Principia had established for its author of course prepared the
way for acceptance of his second published work. Furthermore,
its content and manner of presentation made the Opticks more
approachable.
Newton's mathematical genius had been stimulated in his early
years at Cambridge by his work under Barrow, which included a
thorough grounding in Greek mathematics as well as in the recent
work of Rene Descartes and of John Wallis. During his
undergraduate years Newton had discovered what is known as the
binomial theorem; invention of the calculus had followed;
mathematical questions had been treated at length in
correspondence with scientists in England and abroad; and his
contributions to optics and celestial mechanics could be said to
be his mathematical formulation of their principles. But it was
not until the controversy over the discovery of the calculus
that Newton published mathematical work as such. The
controversy, begun in 1699, when Fatio de Duillier made the
first accusation of plagiarism against Leibniz, continued
sporadically for nearly 20 years, not completely subsiding even
with Leibniz's death in 1716.
Two other areas to which Newton devoted much attention were
chronology and theology.
A shortened form of his Chronology
of Ancient Kingdoms appeared without his consent in 1725,
inducing him to prepare the longer work for publication; it did
not actually appear until after his death. In it Newton
attempted to correlate Egyptian, Greek, and Hebrew history and
mythology and for the first time made use of astronomical
references in ancient texts to establish dates of historical
events. In his Observations upon the Prophecies of Daniel and
the Apocalypse of St. John, also posthumously published, his aim
was to show that the prophecies of the Old and New Testaments
had so far been fulfilled.
The mass of Newton's papers, manuscripts, and correspondence
that survive reveal tremendous powers of concentration, ability
to stand long periods of intense mental exertion, and
objectivity uncomplicated by frivolous interests. The many
portraits of Newton (he was painted by nearly all the leading
artists of his time) range from the fashionable, somewhat
idealized, treatment to a more convincing realism. When Newton
came to maturity, circumstances were auspiciously combined to
make possible a major change in men's ways of thought and
endeavor. The uniqueness of Newton's achievement could be said
to lie in his exploitation of these unusual circumstances. He
alone among his gifted contemporaries fully recognized the
implications of recent scientific discoveries. With these as a
point of departure, he developed a unified mathematical
interpretation of the cosmos, in the expounding of which he
demonstrated method and direction for future elaboration. In
shifting the emphasis from quality to quantity, from pursuit of
answers to the question "Why?" to focus upon "What?" and "How?"
he effectively prepared the way for the age of technology. He
died on March 20, 1727.
