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Sir Isaac Newton was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian who is considered by many scholars and
members of the general public to be one of the most influential people in human
history. His 1687 publication of the Philosophić
Naturalis Principia Mathematica (usually called the Principia) is
considered to be among the most influential books in the history of
science, laying the groundwork for most of classical mechanics. In this work, Newton
described universal gravitation and the three
laws of motion which dominated the scientific view of the physical universe for the next three centuries.
Newton showed that the motions of objects on Earth and of celestial bodies are governed by the same
set of natural laws by demonstrating the consistency between Kepler's laws of planetary
motion and his theory of gravitation, thus removing the last doubts about heliocentrism and advancing
the scientific revolution.
Newton also built the first practical reflecting telescope
and developed a theory of colour based on the observation that a prism decomposes white light into the many colours that form the visible spectrum. He
also formulated an empirical law of cooling and
studied the speed of
sound.
In mathematics, Newton shares the credit with
Gottfried
Leibniz for the development of the differential
and integral calculus. He also demonstrated the generalised binomial theorem, developed Newton's method for
approximating the roots of a function, and contributed to the
study of power series.
Newton remains uniquely influential to scientists, as demonstrated by a 2005
survey of members of Britain's Royal Society asking who had the greater effect
on the history of science and had the greater contribution to humankind, Newton
or Albert Einstein.
Royal Society scientists deemed Newton to have made the greater overall
contribution on both
Newton's mathematical work has been said "to distinctly advance every branch
of mathematics then studied".
Newton's work on the subject usually referred to as fluxions or calculus is
seen, for example, in a manuscript of October 1666, now published among Newton's
mathematical papers. A related subject
of his mathematical work was infinite series. Newton's manuscript "De analysi
per aequationes numero terminorum infinitas" ("On analysis by equations infinite
in number of terms") was sent by Isaac Barrow to John Collins in June 1669: in
August 1669 Barrow identified its author to Collins as "Mr Newton, a fellow of
our College, and very young ... but of an extraordinary genius and proficiency
in these things".
Newton later became involved in a dispute with Leibniz over priority in the development
of infinitesimal calculus. Most modern historians believe that Newton and Leibniz developed infinitesimal
calculus independently, although with very different notations. Occasionally
it has been suggested that Newton published almost nothing about it until 1693,
and did not give a full account until 1704, while Leibniz began publishing a
full account of his methods in 1684. (Leibniz's notation and "differential
Method", nowadays recognised as much more convenient notations, were adopted by
continental European mathematicians, and after 1820 or so, also by British
mathematicians.) Such a suggestion, however, fails to notice the content of
calculus which critics of Newton's time and modern times have pointed out in Book
1 of Newton's Principia itself (published 1687) and in its forerunner
manuscripts, such as De motu corporum in gyrum ("On the
motion of bodies in orbit"), of 1684. The Principia
is not written in the language of calculus either as we know it or as Newton's
(later) 'dot' notation would write it. But Newton's work extensively uses an
infinitesimal calculus in geometric form, based on limiting values of the ratios
of vanishing small quantities: in the Principia itself Newton gave
demonstration of this under the name of 'the method of first and last
ratios' and explained why
he put his expositions in this form, remarking also
that 'hereby the same thing is performed as by the method of indivisibles'.
Because of this content the Principia has been called "a book dense
with the theory and application of the infinitesimal calculus" in modern
times and "lequel est
presque tout de ce calcul" ('nearly all of it is of this calculus') in Newton's
time. Newton's use of
methods involving "one or more orders of the infinitesimally small" is present
in Newton's De Motu Corporum in Gyrum of 1684 and in his papers on motion "during the two decades preceding 1684".
Newton had been reluctant to publish his calculus because he feared
controversy and criticism. Newton had a very
close relationship with Swiss mathematician Nicolas Fatio de Duillier, who from
the beginning was impressed by Newton's gravitational
theory. In 1691, Duillier planned to prepare a new version of Newton's
Principia, but never finished it. However, in 1693 the relationship
between the two men changed. At the time, Duillier had also exchanged several
letters with Leibniz.
Starting in 1699, other members of the Royal Society (of which Newton was a member)
accused Leibniz of plagiarism,
and the dispute broke out in full force in 1711. Newton's Royal Society
proclaimed in a study that it was Newton who was the true discoverer and
labelled Leibniz a fraud. This study was cast into doubt when it was later found
that Newton himself wrote the study's concluding remarks on Leibniz. Thus began
the bitter Newton v. Leibniz calculus
controversy, which marred the lives of both Newton and Leibniz until the
latter's death in 1716.
Newton is generally credited with the generalised
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 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.
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, he observed that colour is the result of objects
interacting with alreadycoloured light rather than objects generating the
colour themselves. This is known as Newton's
theory of colour.
From this work, he concluded that the lens of any refracting
telescope would suffer from the dispersion of light into colours (chromatic
aberration). As a proof of the concept, he constructed a telescope using a
mirror as the objective to bypass that problem.
Building the design, the first known functional reflecting telescope, today
known as a Newtonian telescope,
involved solving the problem of a suitable mirror material and shaping
technique. Newton ground his own mirrors out of a custom composition of highly
reflective speculum
metal, using Newton's rings to judge the quality of the
optics for his telescopes. In late 1668 he was able to produce this first reflecting telescope. 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.
Newton and Hooke had brief exchanges in 167980, when Hooke, appointed to manage
the Royal Society's correspondence, opened up a correspondence intended to
elicit contributions from Newton to Royal Society transactions, which had the effect of stimulating Newton to work out a proof that the
elliptical form of planetary orbits would result from a centripetal force
inversely proportional to the square of the radius vector (see Newton's law of
universal gravitation  History and De motu corporum in gyrum). But
the two men remained generally on poor terms until Hooke's death.
Newton argued that light is composed of particles or corpuscles, which were
refracted by accelerating into a denser medium. He verged on soundlike waves to
explain the repeated pattern of reflection and transmission by thin films
(Opticks Bk.II, Props. 12), but still retained his theory of ‘fits’ that
disposed corpuscles to be reflected or transmitted (Props.13). Later physicists
instead favoured a purely wavelike explanation of light to account for the interference patterns, and the
general phenomenon of diffraction. Today's quantum mechanics, photons and the idea of wave–particle duality bear only a
minor resemblance to Newton's understanding of light.
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; however, he did
apparently abandon his alchemical researches (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. (See also Isaac Newton's occult
studies.)
In 1704, Newton published 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).
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 planetary motion. This
followed stimulation by a brief exchange of letters in 167980 with Hooke, who
had been appointed to manage the Royal Society's correspondence, and who opened
a correspondence intended to elicit contributions from Newton to Royal Society
transactions. Newton's reawakening interest in astronomical matters received further stimulus
by the appearance of a comet in the winter of 16801681, on which he
corresponded with John
Flamsteed. After the
exchanges with Hooke, Newton worked out a proof that the elliptical form of
planetary orbits would result from a centripetal force inversely proportional to
the square of the radius vector (see Newton's law of
universal gravitation  History and De motu corporum in gyrum). Newton
communicated his results to Edmond Halley and to the Royal Society in De motu
corporum in gyrum, a tract written on about 9 sheets which was copied
into the Royal Society's Register Book in December 1684.
This tract contained the nucleus that Newton developed and expanded to form the
Principia.
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 200 years. He used the Latin word
gravitas (weight) for the effect that would become known as gravity, and defined
the law of universal
gravitation.
In the same work, Newton presented a calculuslike method of geometrical
analysis by 'first and last ratios', gave the first analytical determination
(based on Boyle's law) of
the speed of sound in air, inferred the oblateness of the spheroidal figure of
the Earth, accounted for the precession of the equinoxes as a result of the
Moon's gravitational attraction on the Earth's oblateness, initiated the
gravitational study of the irregularities in the motion of the moon,
provided a theory for the determination of the orbits of comets, and much
more.
Newton made clear his heliocentric view of the solar system – developed in a
somewhat modern way, because already in the mid1680s he recognised the
"deviation of the Sun" from the centre of gravity of the solar system.
For Newton, it was
not precisely the centre of the Sun or any other body that could be considered
at rest, but rather "the common centre of gravity of the Earth, the Sun and all
the Planets is to be esteem'd the Centre of the World", and this centre of
gravity "either is at rest or moves uniformly forward in a right line" (Newton
adopted the "at rest" alternative in view of common consent that the centre,
wherever it was, was at rest).
Newton's postulate of an invisible force able to act over vast
distances led to him being criticised for introducing "occult agencies" into science.
Later, in the second edition of the Principia (1713), Newton firmly
rejected such criticisms in a concluding General Scholium, writing that it was
enough that the phenomena implied a gravitational attraction, as they did; but
they did not so far indicate its cause, and it was both unnecessary and improper
to frame hypotheses of things that were not implied by the phenomena. (Here
Newton used what became his famous expression Hypotheses non fingo).
With the Principia, Newton became internationally recognised.
He acquired a
circle of admirers, including the Swissborn mathematician Nicolas
Fatio de Duillier, with whom he formed an intense relationship that lasted
until 1693, when it abruptly ended, at the same time that Newton suffered a nervous breakdown.
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 (see above).
Newton was also a member of the Parliament of England from 1689 to 1690
and in 1701, but according to some accounts his only comments were to complain
about a cold draught 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 securing the job of deputy comptroller of the temporary Chester branch for
Edmond Halley). Newton became perhaps the bestknown 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 in the "Law of Queen
Anne" Newton moved the Pound Sterling from the silver standard to the
gold standard by setting
the bimetallic relationship between gold coins and the silver penny in favour of
gold. This caused silver sterling coin to be melted and shipped out of Britain.
Newton 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 Historia Coelestis Britannica, which Newton had used in his
studies.
In April 1705, Queen Anne knighted Newton during a royal visit to Trinity
College, Cambridge. The knighthood is likely to have been motivated by political
considerations connected with the Parliamentary election in May 1705, rather
than any recognition of Newton's scientific work or services as Master of the
Mint Newton was the
first scientist ever to be knighted.
Towards the end of his life, Newton took up residence at Cranbury Park, near Winchester with his niece and her
husband, until his death in 1727. Newton died
in his sleep in London on 31 March 1727 [OS: 20 March 1726], and was
buried in Westminster Abbey. His halfniece, 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. Newton, a bachelor, had divested much of his
estate to relatives during his last years, and died intestate.
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.
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