Sir Isaac NewtonPRS MP (/ˈnjuːtən/;[8]25 December 1642 – 20 March 1727[1]) was an English physicist and mathematicianwho is widely regarded as one of the most influential scientists of all timeand as a key figure in the scientific revolution. His book PhilosophiæNaturalis Principia Mathematica ("Mathematical Principles of NaturalPhilosophy"), first published in 1687, laid the foundations for most ofclassical mechanics.Newtonalso made seminal contributions to optics and shares credit with GottfriedLeibniz for the invention of the infinitesimal calculus.

Newton's Principia formulated the laws of motionand universal gravitation that dominated scientists' view of the physicaluniverse for the next three centuries. It also demonstrated that the motion ofobjects on the Earth and that of celestial bodies could be described by thesame principles. By deriving Kepler's laws of planetary motion from hismathematical description of gravity,Newtonremoved the last doubts about the validity of the heliocentric model of thecosmos.

Newton built the first practical reflectingtelescope and developed a theory of colour based on the observation that aprism decomposes white light into the many colours of the visible spectrum. Healso formulated an empirical law of cooling and studied the speed of sound. Inaddition to his work on the calculus, as a mathematicianNewtoncontributed to the study of power series, generalised the binomial theorem tonon-integer exponents, and developedNewton'smethod for approximating the roots of a function.

Newton was afellow ofTrinityCollegeand the second Lucasian Professor ofMathematics at theUniversityofCambridge. He was adevout but unorthodox Christian and, unusual for a member of theCambridgefaculty, herefused to take holy orders in the Church of England, perhaps because heprivately rejected the doctrine of the Trinity. In addition to his work on themathematical sciences,Newtonalso dedicated much of his time to the study of alchemy and biblicalchronology, but most of his work in those areas remained unpublished until longafter his death. In his later life,Newtonbecame president of the Royal Society. He also served the British government asWarden and Master of the Royal Mint.

Early lifeMainarticle: Early life of Isaac Newton

Isaac Newton wasborn (according to the Julian calendar in use inEnglandat the time) on Christmas Day, 25 December 1642 (NS 4 January 1643[1]), atWoolsthorpe Manor in Woolsthorpe-by-Colsterworth, a hamlet in thecountyofLincolnshire. He was born three monthsafter the death of his father, a prosperous farmer also named Isaac Newton.Born prematurely, he was a small child; his mother Hannah Ayscough reportedlysaid that he could have fit inside a quart mug (≈ 1.1 litres). WhenNewtonwas three, hismother remarried and went to live with her new husband, the Reverend BarnabusSmith, leaving her son in the care of his maternal grandmother, MargeryAyscough. The young Isaac disliked his stepfather and maintained some enmitytowards his mother for marrying him, as revealed by this entry in a list ofsins committed up to the age of 19: "Threatening my father and motherSmith to burn them and the house over them."Newton'smother had three children from her second marriage.[9] Although it was claimedthat he was once engaged,[10]Newtonnever married.

Newton in a 1702 portrait by Godfrey Kneller

Isaac Newton (Bolton, Sarah K. Famous Men of Science. NY: Thomas Y.Crowell & Co., 1889)From the age of about twelve until he was seventeen,Newton was educated at The King's School, Grantham which taught him Latin butno mathematics. He was removed from school, and by October 1659, he was to befound at Woolsthorpe-by-Colsterworth, where his mother, widowed by now for asecond time, attempted to make a farmer of him. He hated farming.[11] HenryStokes, master at the King's School, persuaded his mother to send him back toschool so that he might complete his education. Motivated partly by a desirefor revenge against a schoolyard bully, he became the top-ranked student,[12]distinguishing himself mainly by building sundials and models of windmills.[13]

In June 1661, hewas admitted toTrinityCollege,Cambridge,on the recommendation of his uncle Rev William Ayscough. He started as asubsizar—paying his way by performing valet's duties—until he was awarded ascholarship in 1664, which guaranteed him four more years until he would gethis M.A.[14] At that time, the college's teachings were based on those ofAristotle, whom Newton supplemented with modern philosophers, such asDescartes, and astronomers such as Galileo and Thomas Street, through whom helearned of Kepler's work. He set down in his notebook a series of 'Quaestiones'about mechanical philosophy as he found it. In 1665, he discovered thegeneralised binomial theorem and began to develop a mathematical theory thatlater became infinitesimal calculus. Soon afterNewtonhad obtained his B.A. degree in August1665, the university temporarily closed as a precaution against the GreatPlague. Although he had been undistinguished as a Cambridge student,[15]Newton's private studies at his home in Woolsthorpe over the subsequent twoyears saw the development of his theories on calculus,[16] optics and the lawof gravitation. In April 1667, he returned toCambridgeand in October was elected as afellow of Trinity.[17][18] Fellows were required to become ordained priests,although this was not enforced in the restoration years and an assertion ofconformity to the Church of England was sufficient. However, by 1675 the issuecould not be avoided and by then his unconventional views stood in the way.[19]Nevertheless,Newtonmanaged to avoid it by means of a special permission from Charles II (see"Middle years" section below).

His studies hadimpressed the Lucasian professor, Isaac Barrow, who was more anxious to develophis own religious and administrative potential (he became master of Trinity twoyears later), and in 1669,Newtonsucceeded him, only one year after he received his M.A.

MiddleyearsMathematicsNewton's work has been said "to distinctly advance everybranch of mathematics then studied".[20] His work on the subject usuallyreferred to as fluxions or calculus, seen in a manuscript of October 1666, isnow published among Newton's mathematical papers.[21] The author of themanuscript De analysi per aequationes numero terminorum infinitas, sent byIsaac Barrow to John Collins in June 1669, was identified by Barrow in a lettersent to Collins in August of that year as:[22]

Mr Newton, afellow of our College, and very young ... but of an extraordinary genius andproficiency in these things.

Newton later became involved in a dispute withLeibniz over priority in the development of infinitesimal calculus (theLeibniz–Newton calculus controversy). Most modern historians believe thatNewtonand Leibnizdeveloped infinitesimal calculus independently, although with very differentnotations. Occasionally it has been suggested thatNewtonpublished almost nothing about ituntil 1693, and did not give a full account until 1704, while Leibniz beganpublishing a full account of his methods in 1684. (Leibniz's notation and"differential Method", nowadays recognised as much more convenientnotations, were adopted by continental European mathematicians, and after 1820 orso, also by British mathematicians.) Such a suggestion, however, fails tonotice the content of calculus which critics of Newton's time and modern timeshave pointed out in Book 1 of Newton's Principia itself (published 1687) and inits forerunner manuscripts, such as De motu corporum in gyrum ("On themotion of bodies in orbit"), of 1684. The Principia is not written in thelanguage of calculus either as we know it or asNewton's (later) 'dot' notation would writeit. But his work extensively uses an infinitesimal calculus in geometric form,based on limiting values of the ratios of vanishing small quantities: in thePrincipia itself Newton gave demonstration of this under the name of 'themethod of first and last ratios'[23] and explained why he put his expositionsin this form,[24] remarking also that 'hereby the same thing is performed as bythe method of indivisibles'.

Because of this,the Principia has been called "a book dense with the theory andapplication of the infinitesimal calculus" in modern times[25] and"lequel est presque tout de ce calcul" ('nearly all of it is of thiscalculus') in Newton's time.[26] His use of methods involving "one or moreorders of the infinitesimally small" is present in his De motu corporum ingyrum of 1684[27] and in his papers on motion "during the two decadespreceding 1684".[28]

Newton had been reluctant to publish hiscalculus because he feared controversy and criticism.[29] He was close to theSwiss mathematician Nicolas Fatio de Duillier. In 1691, Duillier started to writea new version ofNewton's Principia, andcorresponded with Leibniz.[30] In 1693 the relationship between Duillier andNewtondeteriorated, andthe book was never completed.

Starting in 1699,other members of the Royal Society (of whichNewtonwas a member) accused Leibniz ofplagiarism, and the dispute broke out in full force in 1711. The Royal Societyproclaimed in a study that it wasNewtonwho was the true discoverer and labelled Leibniz a fraud. This study was castinto doubt when it was later found thatNewtonhimself wrote the study's concluding remarks on Leibniz. Thus began the bittercontroversy which marred the lives of bothNewtonand Leibniz until the latter's deathin 1716.[31]

Newton is generally credited with thegeneralised binomial theorem, valid for any exponent. He discoveredNewton's identities,Newton'smethod, classified cubic plane curves (polynomials of degree three in twovariables), made substantial contributions to the theory of finite differences,and was the first to use fractional indices and to employ coordinate geometryto derive solutions to Diophantine equations. He approximated partial sums ofthe harmonic series by logarithms (a precursor to Euler's summation formula),and was the first to use power series with confidence and to revert powerseries.Newton'swork on infinite series was inspired by Simon Stevin's decimals.[32]

He was appointedLucasian Professor of Mathematics in 1669 on Barrow's recommendation. In thatday, any fellow ofCambridgeorOxfordwas required to become an ordainedAnglican priest. However, the terms of the Lucasian professorship required thatthe holder not be active in the church (presumably so as to have more time forscience).Newtonargued that this should exempt him from the ordination requirement, and CharlesII, whose permission was needed, accepted this argument. Thus a conflictbetweenNewton'sreligious views and Anglican orthodoxy was averted.[33]

Later life

Isaac Newton inold age in 1712, portrait by Sir James ThornhillMain article: Later life ofIsaac Newton

In the 1690s,Newtonwrote a number ofreligious tracts dealing with the literal and symbolic interpretation of theBible. A manuscript Newton sent to John Locke in which he disputed the fidelityof 1 John 5:7 and its fidelity to the original manuscripts of the NewTestament, remained unpublished until 1785.[59][60]

Even though anumber of authors have claimed that the work might have been an indication thatNewtondisputed the belief in Trinity, othersassure thatNewtondid question the passage but never denied Trinity as such. His biographer,scientist Sir David Brewster, who compiled his manuscripts for over 20 years,wrote about the controversy in well-known bookMemoirs of the Life, Writings,and Discoveries of Sir Isaac Newton, where he explains thatNewtonquestioned the veracity of thosepassages, but he never denied the doctrine of Trinity as such. Brewster statesthat Newton was never known as an Arian during his lifetime, it was firstWilliam Whiston (an Arian) who argued that "Sir Isaac Newton was so heartyfor the Baptists, as well as for the Eusebians or Arians, that he sometimessuspected these two were the two witnesses in the Revelations," whileother like Hopton Haynes (a Mint employee and Humanitarian), "mentioned toRichard Baron, that Newton held the same doctrine as himself".[61]

Later works – TheChronology of Ancient Kingdoms Amended (1728) and Observations Upon theProphecies of Daniel and the Apocalypse of St. John (1733) – were publishedafter his death. He also devoted a great deal of time to alchemy (see above).

Newton was also amember of the Parliament of England for Cambridge University in 1689–90 and1701–2, but according to some accounts his only comments were to complain abouta cold draught in the chamber and request that the window beclosed.[62][63][64]

Newton movedtoLondontotake up the post of warden of the Royal Mint in 1696, a position that he hadobtained through the patronage of Charles Montagu, 1st Earl of Halifax, thenChancellor of the Exchequer. He took charge ofEngland'sgreat recoining, somewhat treading on the toes of Lord Lucas, Governor of theTower (and securing the job of deputy comptroller of the temporaryChesterbranch for EdmondHalley). Newton became perhaps the best-known Master of the Mint upon the deathof Thomas Neale in 1699, a position Newton held for the last 30 years of hislife.[65][66] These appointments were intended as sinecures, but Newton tookthem seriously, retiring from his Cambridge duties in 1701, and exercising hispower to reform the currency and punish clippers and counterfeiters. As Masterof the Mint in 1717 in the "Law of Queen Anne"Newtonmoved the Pound Sterling de facto fromthe silver standard to the gold standard by setting the bimetallic relationshipbetween gold coins and the silver penny in favour of gold. This caused silversterling coin to be melted and shipped out ofBritain.Newtonwas made President of the RoyalSociety in 1703 and an associate of the French Académie des Sciences. In hisposition at the Royal Society,Newtonmade anenemy of John Flamsteed, the Astronomer Royal, by prematurely publishingFlamsteed's Historia Coelestis Britannica, whichNewtonhad used in his studies.[67]

Personal coat ofarms of Sir Isaac Newton[68]In April 1705, Queen Anne knightedNewtonduring a royal visit toTrinityCollege,Cambridge.The knighthood is likely to have been motivated by political considerationsconnected with the Parliamentary election in May 1705, rather than anyrecognition ofNewton's scientific work orservices as Master of the Mint.[69]Newtonwas the second scientist to be knighted, after Sir Francis Bacon.

Towards the endof his life, Newton took up residence at Cranbury Park, near Winchester withhis niece and her husband, until his death in 1727.[70] His half-niece,Catherine Barton Conduitt,[71] served as his hostess in social affairs at hishouse on Jermyn Street in London; he was her "very loving Uncle,"[72]according to his letter to her when she was recovering from smallpox.

Newton diedin his sleep inLondonon 20 March 1727 (OS 20 March 1726; NS 31 March 1727)[1] and was buried inWestminster Abbey. Voltaire was present at his funeral and praised the Britishfor honoring a scientist of heretical religious beliefs with burial there. Abachelor, he had divested much of his estate to relatives during his lastyears, and died intestate. After his death,Newton's hair was examined and found tocontain mercury, probably resulting from his alchemical pursuits. Mercurypoisoning could explainNewton'seccentricity in late life.[73]