Isaac Newton (4 January 1643 – 31 March 1727) was an English
physicist, mathematician, astronomer, alchemist, and natural philosopher,
regarded by many as the greatest figure in the history of science. His
treatise Philosophiae Naturalis Principia Mathematica, published in 1687,
described universal gravitation and the three laws of motion, laying the
groundwork for classical mechanics. By deriving Kepler's laws of planetary
motion from this system, he was the first to show that the motion of objects
on Earth and of celestial bodies are governed by the same set of natural
laws. The unifying and deterministic power of his laws was integral to the
scientific revolution and the advancement of heliocentrism.
In mechanics, Newton also markedly enunciated the principles of conservation
of momentum and angular momentum. In optics, he invented the reflecting
telescope and discovered that the spectrum of colours observed when white
light passes through a prism is inherent in the white light and not added by
the prism (as Roger Bacon had claimed in the thirteenth century). Newton
notably argued that light is composed of particles. He also formulated an
empirical law of cooling, studied the speed of sound, and proposed a theory
of the origin of stars. In mathematics, Newton shares the credit with
Gottfried Leibniz for the development of calculus. He also 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. French mathematician Joseph-Louis Lagrange often said that
Newton was the greatest genius who ever lived, and once added that he was
also "the most fortunate, for we cannot find more than once a system of the
world to establish." English poet Alexander Pope was moved by Newton's
accomplishments to write the famous epitaph:
Nature and nature's laws lay hid in night;
God said "Let Newton be" and all was light.
Isaac Newton's early life and achievements
Newton was born at Woolsthorpe Manor in Woolsthorpe-by-Colsterworth, a
hamlet in the county of Lincolnshire. He was born to a family of farmers who
owned animals and land, thus making them fairly wealthy. The location he was
born at was about seven miles from Grantham, where he later attended school.
By his own later accounts, Newton was born prematurely and no one expected
him to live; his mother Hannah Ayscough said that his body at that time
could have fit inside a quart mug. His father, also named Isaac Newton, had
been a yeoman farmer and had died three months before Newton's birth, at the
time of the English Civil War. When Newton was three, his mother remarried
and went to live with her new husband, leaving her son in the care of his
maternal grandmother, Margery Ayscough.
According to E.T. Bell and H. Eves:
Newton began his schooling in the village schools and was later sent to The
King's School, Grantham, where he became the top boy in the school. At
Kings, he lodged with the local apothecary, William Clarke and eventually
became engaged to the apothecary's stepdaughter, Anne Storey, before he went
off to Cambridge University at the age of 19. As Newton became engrossed in
his studies, the romance cooled and Miss Storey married someone else. It is
said he kept a warm memory of this love, but Newton had no other recorded
"sweethearts" and never married.
However, Bell and Eves' sources for this claim, William Stukeley and Mrs.
Vincent (the former Miss Storey - actually named Katherine, not Anne),
merely say that Newton entertained "a passion" for Storey while he lodged at
the Clarke house. From the age of about twelve until he was seventeen,
Newton was educated at The King's School, Grantham (where his signature can
still be seen upon a library window sill). He was removed from school, and
by October 1659, he was to be found at Woolsthorpe-by-Colsterworth, where
his mother attempted to make a farmer of him. He was, by later reports of
his contemporaries, thoroughly unhappy with the work. It appears to be Henry
Stokes, master at the King's School, who persuaded his mother to send him
back to school so that he might complete his education. This he did at the
age of eighteen, achieving an admirable final report.
In June 1661, he was admitted to Trinity College, Cambridge. At that time,
the college's teachings were based on those of Aristotle, but Newton
preferred to read the more advanced ideas of modern philosophers such as
Descartes and astronomers such as Galileo, Copernicus and Kepler. In 1665,
he discovered the generalised binomial theorem and began to develop a
mathematical theory that would later become calculus. Soon after Newton had
obtained his degree in 1665, the University closed down as a precaution
against the Great Plague. For the next 18 months Newton worked at home on
calculus, optics and the law of gravitation.
Newton and Gottfried Leibniz developed calculus independently, using
their own unique notations (as most great mathematicians do.) Although
Newton had worked out his method years before Leibniz, he published almost
nothing about it until 1693, and did not give a full account until 1704.
Meanwhile, Leibniz began publishing a full account of his methods in 1684.
Moreover, Leibniz's notation and "differential Method" were universally
adopted on the Continent, and after 1820 or so, in the British Empire.
Newton claimed that he had been reluctant to publish his calculus because he
feared being mocked for it. Starting in 1699, other members of the Royal
Society accused Leibniz of plagiarism, and the dispute broke out in full
force in 1711. Thus began the bitter calculus priority dispute with Leibniz,
which marred the lives of both Newton and Leibniz until the latter's death
in 1716. This dispute created a divide between British and Continental
mathematicians that may have retarded the progress of British mathematics by
at least a century.
Newton is generally credited with the generalized binomial theorem, valid
for any exponent. He discovered Newton's identities, Newton's method,
classified cubic plane curves (polynomials of degree three in two
variables), made substantial contributions to the theory of finite
differences, and was the first to use fractional indices and to employ
coordinate geometry to derive solutions to Diophantine equations. He
approximated partial sums of the harmonic series by logarithms (a precursor
to Euler's summation formula), and was the first to use power series with
confidence and to revert power series. He also discovered a new formula for
He was elected Lucasian professor of mathematics in 1669. In that day, any
fellow of Cambridge or Oxford had to be an ordained Anglican priest.
However, the terms of the Lucasian professorship required that the holder
not be active in the church (presumably so as to have more time for
science). Newton argued that this should exempt him from the ordination
requirement, and Charles II, whose permission was needed, accepted this
argument. Thus a conflict between Newton's religious views and Anglican
orthodoxy was averted.
From 1670 to 1672, Newton lectured on optics. During this period he
investigated the refraction of light, demonstrating that a prism could
decompose white light into a spectrum of colours, and that a lens and a
second prism could recompose the multicoloured spectrum into white light.
A replica of Newton's 6-inch reflecting telescope of 1672 for the Royal
Society.He also showed that the coloured light does not change its
properties, by separating out a coloured beam and shining it on various
objects. Newton noted that regardless of whether it was reflected or
scattered or transmitted, it stayed the same colour. Thus the colours we
observe are the result of how objects interact with the incident already-coloured
light, not the result of objects generating the colour. For more details,
see Newton's theory of colour.
From this work he concluded that any refracting telescope would suffer from
the dispersion of light into colours, and invented a reflecting telescope
(today known as a Newtonian telescope) to bypass that problem. By grinding
his own mirrors, using Newton's rings to judge the quality of the optics for
his telescopes, he was able to produce a superior instrument to the
refracting telescope, due primarily to the wider diameter of the mirror. In
1671 the Royal Society asked for a demonstration of his reflecting
telescope. Their interest encouraged him to publish his notes On Colour,
which he later expanded into his Opticks. When Robert Hooke criticised some
of Newton's ideas, Newton was so offended that he withdrew from public
debate. The two men remained enemies until Hooke's death.
Newton argued that light is composed of particles, but he had to associate
them with waves to explain the diffraction of light (Opticks Bk. II, Props.
XII-L). Later physicists instead favoured a purely wavelike explanation of
light to account for diffraction. Today's quantum mechanics restores the
idea of "wave-particle duality", although photons bear very little
resemblance to Newton's corpuscles (e.g., corpuscles refracted by
accelerating toward the denser medium).
In his Hypothesis of Light of 1675, Newton posited the existence of the
ether to transmit forces between particles. The contact with the theosophist
Henry More, revived his interest in alchemy. He replaced the ether with
occult forces based on Hermetic ideas of attraction and repulsion between
particles. John Maynard Keynes, who acquired many of Newton's writings on
alchemy, stated that "Newton was not the first of the age of reason: he was
the last of the magicians." Newton's interest in alchemy cannot be isolated
from his contributions to science. (This was at a time when there was no
clear distinction between alchemy and science.) Had he not relied on the
occult idea of action at a distance, across a vacuum, he might not have
developed his theory of gravity.
In 1704 Newton wrote Opticks, in which he expounded his corpuscular theory
of light. He considered light to be made up of extremely subtle corpuscles,
that ordinary matter was made of grosser corpuscles and speculated that
through a kind of alchemical transmutation "Are not gross Bodies and Light
convertible into one another,...and may not Bodies receive much of their
Activity from the Particles of Light which enter their Composition?" Newton
also constructed a primitive form of a frictional electrostatic generator,
using a glass globe (Optics, 8th Query).
Gravity and motion
Newton's own copy of his Principia, with hand written corrections for the
second edition.Further information: The writing of Principia Mathematica
In 1679, Newton returned to his work on mechanics, i.e., gravitation and its
effect on the orbits of planets, with reference to Kepler's laws of motion,
and consulting with Hooke and Flamsteed on the subject. He published his
results in De Motu Corporum (1684). This contained the beginnings of the
laws of motion that would inform the Principia.
The Philosophiae Naturalis Principia Mathematica (now known as the
Principia) was published on 5 July 1687 with encouragement and financial
help from Edmond Halley. In this work Newton stated the three universal laws
of motion that were not to be improved upon for more than two hundred years.
He used the Latin word gravitas (weight) for the force that would become
known as gravity, and defined the law of universal gravitation. In the same
work he presented the first analytical determination, based on Boyle's law,
of the speed of sound in air.
With the Principia, Newton became internationally recognised. He acquired a
circle of admirers, including the Swiss-born mathematician Nicolas Fatio de
Duillier, with whom he formed an intense relationship that lasted until
1693. The end of this friendship led Newton to a nervous breakdown.
For more details on this topic, see Isaac Newton's later life.
In the 1690s Newton wrote a number of religious tracts dealing with the
literal interpretation of the Bible. Henry More's belief in the universe and
rejection of Cartesian dualism may have influenced Newton's religious ideas.
A manuscript he sent to John Locke in which he disputed the existence of the
Trinity was never published. Later works — The Chronology of Ancient
Kingdoms Amended (1728) and Observations Upon the Prophecies of Daniel and
the Apocalypse of St. John (1733) — were published after his death. He also
devoted a great deal of time to alchemy.
Newton was also a member of the Parliament of England from 1689 to 1690 and
in 1701, but his only recorded comments were to complain about a cold draft
in the chamber and request that the window be closed.
Newton moved to London to take up the post of warden of the Royal Mint in
1696, a position that he had obtained through the patronage of Charles
Montagu, 1st Earl of Halifax, then Chancellor of the Exchequer. He took
charge of England's great recoining, somewhat treading on the toes of Master
Lucas (and finagling Edmond Halley into the job of deputy comptroller of the
temporary Chester branch). Newton became perhaps the best-known Master of
the Mint upon Lucas' death in 1699, a position Newton held until his death.
These appointments were intended as sinecures, but Newton took them
seriously, retiring from his Cambridge duties in 1701, and exercising his
power to reform the currency and punish clippers and counterfeiters. As
Master of the Mint in 1717 Newton unofficially moved the Pound Sterling from
the silver standard to the gold standard by creating a relationship between
gold coins and the silver penny in the "Law of Queen Anne"; these were all
great reforms at the time, adding considerably to the wealth and stability
of England. It was his work at the Mint, rather than his earlier
contributions to science, that earned him a knighthood from Queen Anne in
Newton's grave in Westminster AbbeyNewton was made President of the Royal
Society in 1703 and an associate of the French Académie des Sciences. In his
position at the Royal Society, Newton made an enemy of John Flamsteed, the
Astronomer Royal, by prematurely publishing Flamsteed's star catalogue,
which Newton had used in his studies.
Newton died in London on March 20th, 1727, and was buried in Westminster
Abbey. His half-niece, Catherine Barton Conduitt, served as his hostess in
social affairs at his house on Jermyn Street in London; he was her "very
loving Uncle", according to his letter to her when she was recovering from
smallpox. Although Newton, who had no children, had divested much of his
estate onto relatives in his last years he actually died intestate. His
considerable liquid estate was divided equally between his eight half-nieces
and half-nephews (three Pilkingtons, three Smiths and two Bartons (including
Catherine Barton Conduitt). Woolsthorpe Manor passed to his heir-in-law, a
John Newton ("God knows a poor representative of so great a man"), who,
after six years of "cock[fight]ing, horse racing, drinking and folly" was
forced to mortgage and then sell the manor before dying in a drunken
After his death, Newton's body was discovered to have had massive amounts of
mercury in it, probably resulting from his alchemical pursuits. Mercury
poisoning could explain Newton's eccentricity in late life.
Although the laws of motion and universal gravitation became Newton's
best-known discoveries, he warned against using them to view the universe as
a mere machine, as if akin to a great clock. He said, "Gravity explains the
motions of the planets, but it cannot explain who set the planets in motion.
God governs all things and knows all that is or can be done."
His scientific fame notwithstanding, Newton's study of the Bible and of the
early Church Fathers were among his greatest passions. He devoted more time
to the study of the Scriptures, the Fathers, and to Alchemy than to science,
and said, "I have a fundamental belief in the Bible as the Word of God,
written by those who were inspired. I study the Bible daily." Newton
himself wrote works on textual criticism, most notably An Historical Account
of Two Notable Corruptions of Scripture. Newton also placed the crucifixion
of Jesus Christ at 3 April, AD 33, which is now the accepted traditional
date. He also attempted, unsuccessfully, to find hidden messages within the
Bible (See Bible code). Despite his focus on theology and alchemy, Newton
tested and investigated these ideas with the scientific method, observing,
hypothesising, and testing his theories. To Newton, his scientific and
religious experiments were one and the same, observing and understanding how
the world functioned.
Newton may have rejected the church's doctrine of the Trinity. In a minority
view, T.C. Pfizenmaier argues that he more likely held the Eastern Orthodox
view of the Trinity rather than the Western one held by Roman Catholics,
Anglicans, and most Protestants. In his own day, he was also accused of
being a Rosicrucian (as were many in the Royal Society and in the court of
In his own lifetime, Newton wrote more on religion than he did on natural
science. He believed in a rationally immanent world, but he rejected the
hylozoism implicit in Leibniz and Baruch Spinoza. Thus, the ordered and
dynamically informed universe could be understood, and must be understood,
by an active reason, but this universe, to be perfect and ordained, had to
Newton's effect on religious thought.
Newton and Robert Boyle’s mechanical philosophy was promoted by rationalist
pamphleteers as a viable alternative to the pantheists and enthusiasts, and
was accepted hesitantly by orthodox preachers as well as dissident preachers
like the latitudinarians. Thus, the clarity and simplicity of science
was seen as a way to combat the emotional and metaphysical superlatives of
both superstitious enthusiasm and the threat of atheism, and, at the
same time, the second wave of English deists used Newton's discoveries to
demonstrate the possibility of a "Natural Religion."
The attacks made against pre-Enlightenment "magical thinking," and the
mystical elements of Christianity, were given their foundation with Boyle’s
mechanical conception of the universe. Newton gave Boyle’s ideas their
completion through mathematical proofs and, perhaps more important, was very
successful in popularising them. Newton refashioned the world governed
by an interventionist God into a world crafted by a God that designs along
rational and universal principles. These principles were available for
all people to discover, allowed man to pursue his own aims fruitfully in
this life, not the next, and to perfect himself with his own rational
Newton saw God as the master creator whose existence could not be denied in
the face of the grandeur of all creation. But the unforeseen
theological consequence of his conception of God, as Leibniz pointed out,
was that God was now entirely removed from the world’s affairs, since the
need for intervention would only evidence some imperfection in God’s
creation, something impossible for a perfect and omnipotent creator.
Leibniz's theodicy cleared God from the responsibility for "l'origine du
mal" by making God removed from participation in his creation. The
understanding of the world was now brought down to the level of simple human
reason, and humans, as Odo Marquard argued, became responsible for the
correction and elimination of evil.
On the other hand, latitudinarian and Newtonian ideas taken too far resulted
in the millenarians, a religious faction dedicated to the concept of a
mechanical universe, but finding in it the same enthusiasm and mysticism
that the Enlightenment had fought so hard to extinguish
As warden of the royal mint, Newton estimated that 20% of the coins taken in
during The Great Recoinage were counterfeit. Counterfeiting was treason,
punishable by death by drawing and quartering. Despite this, convictions of
the most flagrant criminals could be extremely difficult to achieve;
however, Newton proved to be equal to the task.
He gathered much of that evidence himself, disguised, while he hung out at
bars and taverns. For all the barriers placed to prosecution, and separating
the branches of government, English law still had ancient and formidable
customs of authority. Newton was made a justice of the peace and between
June 1698 and Christmas 1699 conducted some 200 cross-examinations of
witnesses, informers and suspects. Newton won his convictions and in
February 1699, he had ten prisoners waiting to be executed. He later ordered
all records of his interrogations to be destroyed.
Newton's greatest triumph as the king's attorney was against William
Chaloner. One of Chaloner's schemes was to set up phony conspiracies of
Catholics and then turn in the hapless conspirators whom he entrapped.
Chaloner made himself rich enough to posture as a gentleman. Petitioning
Parliament, Chaloner accused the Mint of providing tools to counterfeiters
(a charge also made by others). He proposed that he be allowed to inspect
the Mint's processes in order to improve them. He petitioned Parliament to
adopt his plans for a coinage that could not be counterfeited, while at the
same time striking false coins. Newton was outraged, and went about the work
to uncover anything about Chaloner. During his studies, he found that
Chaloner was engaged in counterfeiting. He immediately put Chaloner on
trial, but Mr Chaloner had friends in high places, and to Newton's horror,
Chaloner walked free. Newton put him on trial a second time with conclusive
evidence. Chaloner was convicted of high treason and hanged, drawn and
quartered on March 23, 1699 at Tyburn gallows.
Enlightenment philosophers chose a short history of scientific
predecessors—Galileo, Boyle, and Newton principally—as the guides and
guarantors of their applications of the singular concept of Nature and
Natural Law to every physical and social field of the day. In this respect,
the lessons of history and the social structures built upon it could be
It was Newton’s conception of the universe based upon Natural and rationally
understandable laws that became the seed for Enlightenment ideology. Locke
and Voltaire applied concepts of Natural Law to political systems advocating
intrinsic rights; the physiocrats and Adam Smith applied Natural conceptions
of psychology and self-interest to economic systems and the sociologists
criticised the current social order for trying to fit history into Natural
models of progress. Monboddo and Samuel Clarke resisted elements of Newton's
work, but eventually rationalised it to conform with their strong religious
views of nature.
Newton's laws of motion
The famous three laws of motion:
- Newton's First Law (also known as the Law
of Inertia) states that an object at rest tends to stay
at rest and that an object in uniform motion tends to
stay in uniform motion unless acted upon by a net
- Newton's Second Law states that an applied
force, F, on an
object equals the time rate of change of its momentum,
this is written as
Assuming the mass to be constant, the first term
vanishes. Defining the acceleration to be
results in the famous equation
which states that the acceleration of an object is
directly proportional to the magnitude of the net force
acting on the object and inversely proportional to its
mass. In the MKS system of measurement, mass is given in
kilograms, acceleration in metres per second squared,
and force in newtons (named in his honour).
- Newton's Third Law states that for every
action there is an equal and opposite reaction.
A popular story claims that Newton was inspired to formulate his theory of
universal gravitation by the fall of an apple from a tree. Cartoons have
gone further to suggest the apple actually hit Newton's head, and that its
impact somehow made him aware of the force of gravity. John Conduitt,
Newton's assistant at the royal mint and husband of Newton's niece,
described the event when he wrote about Newton's life:
In the year 1666 he retired again from Cambridge to his mother in
Lincolnshire. Whilst he was musing in a garden it came into his thought that
the power of gravity (which brought an apple from a tree to the ground) was
not limited to a certain distance from earth, but that this power must
extend much further than was usually thought. Why not as high as the Moon
said he to himself & if so, that must influence her motion & perhaps retain
her in her orbit, whereupon he fell a calculating what would be the effect
of that supposition.
The question was not whether gravity existed, but whether it extended so far
from Earth that it could also be the force holding the moon to its orbit.
Newton showed that if the force decreased as the inverse square of the
distance, one could indeed calculate the Moon's orbital period, and get good
agreement. He guessed the same force was responsible for other orbital
motions, and hence named it "universal gravitation".
A contemporary writer, William Stukeley, recorded in his Memoirs of Sir
Isaac Newton's Life a conversation with Newton in Kensington on 15 April
1726, in which Newton recalled "when formerly, the notion of gravitation
came into his mind. It was occasioned by the fall of an apple, as he sat in
contemplative mood. Why should that apple always descend perpendicularly to
the ground, thought he to himself. Why should it not go sideways or upwards,
but constantly to the earth's centre." In similar terms, Voltaire wrote in
his Essay on Epic Poetry (1727), "Sir Isaac Newton walking in his gardens,
had the first thought of his system of gravitation, upon seeing an apple
falling from a tree." These accounts are probably exaggerations of Newton's
own tale about sitting by a window in his home (Woolsthorpe Manor) and
watching an apple fall from a tree.
Various trees are claimed to be "the" apple tree which Newton describes. The
King's School, Grantham, claims that the tree was purchased by the school,
uprooted and transported to the headmaster's garden some years later, the
staff of the [now] National Trust-owned Woolsthrope Manor dispute this, and
claim that a tree present in their gardens is the one described by Newton. A
descendant of the original tree can be seen growing outside the main gate of
Trinity College, Cambridge, below the room Newton lived in when he studied