He would expand these laws by arguing that orbits (such as those
of comets) were not only elliptic; but could also be hyperbolic
and parabolic. He is also notable for his arguments that light was
composed of particles; see: wave-particle duality. He was the first
to realise that the spectrum of colours observed when white light
was passed through a prism was inherent in the white light, and
not added by the prism as Roger Bacon had claimed 400 years earlier.
Newton also developed Newton's law of cooling, describing the rate
of cooling of objects when exposed to air; the binomial theorem
in its entirety; and the principles of conservation of momentum
and angular momentum. Finally, he studied the speed of sound in
air, and voiced a theory of the origin of stars.
Early
life
Newton was born in Woolsthorpe-by-Colsterworth, a hamlet in the
county of Lincolnshire. His father had died three months before
Newton's birth, and two years later his mother went to live with
her new husband, leaving her son in the care of his grandmother.
Newton was a child prodigy.
According to E.T. Bell (1937, Simon and Schuster) and H. Eves:
Newton began his schooling in the village schools and later was
sent to Grantham Grammar School where he became the top boy in the
school. At Grantham he lodged with the local apothecary and eventually
became engaged to the apothecary's stepdaughter, Miss Storey, before
he went off to Cambridge University at the age of 19. But 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.
Newton was educated at Grantham Grammar School. In 1661 he joined
Trinity College, Cambridge, where his uncle William Ayscough had
studied. 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, Galileo, Copernicus and
Kepler. In 1665 he discovered the binomial theorem and began to
develop a mathematical theory that would later become calculus.
Soon after Newton had collected his degree in 1665, the University
closed down as a precaution against the Great Plague. For the next
two years Newton worked at home on calculus, optics and gravitation.
Tradition has it that Newton was sitting under an apple tree when
an apple fell on his head, and this made him understand that earthly
and celestial gravitation are the same. This is an exaggeration
of Newton's own tale about sitting by the window of his home (Woolsthorpe
Manor) and watching an apple fall from a tree. However it is now
generally considered that even this story was invented by him in
his later life, to try to show how clever he was at drawing inspiration
from everyday events. A contemporary writer, William Stukeley, recorded
in his Memoirs of Sir Isaac Newton's Life a conversation with Newton
in Kensington on April 15, 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."
Newton became a fellow of Trinity College in 1667. In the same year
he circulated his findings in De Analysi per Aequationes Numeri
Terminorum Infinitas (On Analysis by Infinite Series), and later
in De methodis serierum et fluxionum (On the Methods of Series and
Fluxions), whose title gave the name to his "method of fluxions".
Newton and Leibniz developed the theory of calculus independently
and used different notations. Although Newton had worked out his
own method before Leibniz, the latter's notation and "Differential
Method" were superior, and were generally adopted throughout
the English-speaking world. (Curiously, in Germany the Newtonian
notation is more popular.) Though Newton belongs among the brightest
scientists of his era, the last twenty-five years of his life were
marred by a bitter dispute with Leibniz, whom he accused of plagiarism.
He was elected Lucasian professor of mathematics in 1669. Any fellow
of Cambridge or Oxford had to be ordained at the time. 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 normal
ordination requirement, and Charles II, whose permission was needed,
accepted this argument. This prevented the conflict that would have
occurred between his nontrinitarian views and the orthodoxy of the
church.
Newton and optics
From 1670 to 1672 he 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.
From his work he concluded that any refracting telescope would suffer
from the dispersion of light into colours, and invented the reflecting
telescope to bypass that problem. (Later, when glasses with a variety
of refractive properties became available, achromatic lenses became
possible.) 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. Due to Newton's paranoia, the
two men remained enemies until Hooke's death.
In one experiment, to prove that colour was caused by pressure on
the eye, Newton slid a darning needle around the side of his eye
until he could poke at its rear side, dispassionately noting "white,
darke & coloured circles" so long as he kept stirring with
"ye bodkin."
He once said, in a letter to Hooke dated 5 February 1676:
If I have seen a little further it is by standing on the shoulders
of Giants.
In changing this quotation of Didacus Stella (Lucan (vol. II, 10)
) from "Pigmies placed on the shoulders of giants see more
than the giants themselves", Newton was perhaps making a more
personal point than the mere expression of modesty - as Hooke was
a man of short stature.
Newton argued that light is composed of particles. Later physicists
instead favored a wave explanation of light because of certain experimental
findings. Today's quantum mechanics recognizes a "wave-particle
duality" however photons bear very little semblance to Newton's
corpuscles (e.g., corpuscles refracted by accelerating toward the
denser medium).
In his Hypothesis of Light of 1675, Newton relied on the existence
of the ether to transmit forces between particles. Newton was in
contact with Henry More, the Cambridge Platonist who was born in
Grantham, on alchemy, and now his interest in the subject revived.
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 believed in the occult
idea of action at a distance, across a vacuum, he may not have developed
his theory of gravity.
Physics
In
1679, Newton returned to his work on 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.
Philosophiae Naturalis Principia Mathematica (now known as the Principia)
was published in 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 the next three 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.
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 infinity of 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 Parliament 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 deputy comptroller of the temporary Chester branch). Newton
became master of the Mint upon Lucas' death in 1699. These appointments
were intended as sinecures, but Newton took them seriously, exercising
his power to reform the currency and punish clippers and counterfeiters.
He retired from his Cambridge duties in 1701.
In 1701 Newton anonymously published a law of thermodynamics now
known as "Newton's law of cooling" in the Philosophical
Transactions of the Royal Society.
In 1703 Newton became President of the Royal Society 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 attempting to steal his catalogue of observations.
Newton was knighted by Queen Anne in 1705.
Newton never married, nor had any recorded children. He died in
London and was buried in Westminster Abbey.
Religious
views
The
law of gravity became Sir Isaac Newton's best-known discovery. Newton
warned against using it to view the universe as a mere machine,
like 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."
Despite his fame as one of the greatest scientists ever to have
lived, the Bible was Sir Isaac Newton's greatest passion. He devoted
more time to study of Scripture 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 was secretly a unitarian; he did not believe in the church's
doctrine of divine trinity. Had this become known while he lived,
the law would have required his removal from his position as a professor
in Cambridge University. His writings on this topic were published
only posthumously.
Newton's
legacy
Newton's
laws of motion and gravity provided a basis for predicting a wide
variety of different scientific or engineering situations, especially
the motion of celestial bodies. His calculus proved vital to the
development of further scientific theory. Finally, he unified many
of the isolated physics facts that had been discovered earlier into
a satisfying system of laws. For this reason, he is generally considered
one of history's greatest scientists, ranking alongside such figures
as Einstein and Gauss.
Quotations
about Newton
"The Principia is preeminent above any other production of
human genius." - Pierre-Simon Laplace
"Taking mathematics from the beginning of the world to the
time when Newton lived, what he has done is much the better part."
- Gottfried Leibniz
"All that has been accomplished in mathematics since his day
has been a deductive, formal, and mathematical development of mechanics
on the basis of Newton's laws." - Ernst Mach
"Nature and Nature's laws lay hid in night: God said, Let Newton
be! and all was light." - poem, Alexander Pope
Writings
by Newton
Method
of Fluxions (1671)
De Motu Corporum (1684)
Philosophiae Naturalis Principia Mathematica (1687)
Opticks (1704)
Reports as Master of the Mint (1701-1725)
Arithmetica Universalis (1707)
An Historical Account of Two Notable Corruptions of Scripture(1754)
Short Chronicle, The System of the World, Optical Lectures, Universal
Arithmetic, The Chronology of Ancient Kingdoms, Amended and De mundi
systemate were published posthumously in 1728.
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