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IsaacNewton'sLife

SpecialthankstotheMicrosoftCorporationfortheircontributiontooursite.ThefollowinginformationcamefromMicrosoftEncarta.

IINTRODUCTION

Newton,SirIsaac(1642-1727),mathematicianandphysicist,oneoftheforemostscientificintellectsofalltime.BornatWoolsthorpe,nearGranthaminLincolnshire,whereheattendedschool,heenteredCambridgeUniversityin1661;hewaselectedaFellowofTrinityCollegein1667,andLucasianProfessorofMathematicsin1669.Heremainedattheuniversity,lecturinginmostyears,until1696.OftheseCambridgeyears,inwhichNewtonwasattheheightofhiscreativepower,hesingledout1665-1666(spentlargelyinLincolnshirebecauseofplagueinCambridge)astheprimeofmyageforinvention.DuringtwotothreeyearsofintensementalefforthepreparedPhilosophiaeNaturalisPrincipiaMathematica(MathematicalPrinciplesofNaturalPhilosophy)commonlyknownasthePrincipia,althoughthiswasnotpublisheduntil1687.

AsafirmopponentoftheattemptbyKingJamesIItomaketheuniversitiesintoCatholicinstitutions,NewtonwaselectedMemberofParliamentfortheUniversityofCambridgetotheConventionParliamentof1689,andsatagainin1701-1702.Meanwhile,in1696hehadmovedtoLondonasWardenoftheRoyalMint.HebecameMasteroftheMintin1699,anofficeheretainedtohisdeath.HewaselectedaFellowoftheRoyalSocietyofLondonin1671,andin1703hebecamePresident,beingannuallyre-electedfortherestofhislife.Hismajorwork,Opticks,appearedthenextyear;hewasknightedinCambridgein1705.

AsNewtoniansciencebecameincreasinglyacceptedontheContinent,andespeciallyafterageneralpeacewasrestoredin1714,followingtheWaroftheSpanishSuccession,NewtonbecamethemosthighlyesteemednaturalphilosopherinEurope.Hislastdecadeswerepassedinrevisinghismajorworks,polishinghisstudiesofancienthistory,anddefendinghimselfagainstcritics,aswellascarryingouthisofficialduties.Newtonwasmodest,diffident,andamanofsimpletastes.Hewasangeredbycriticismoropposition,andharbouredresentment;hewasharshtowardsenemiesbutgeneroustofriends.Ingovernment,andattheRoyalSociety,heprovedanableadministrator.Henevermarriedandlivedmodestly,butwasburiedwithgreatpompinWestminsterAbbey.

Newtonhasbeenregardedforalmost300yearsasthefoundingexamplarofmodernphysicalscience,hisachievementsinexperimentalinvestigationbeingasinnovativeasthoseinmathematicalresearch.Withequal,ifnotgreater,energyandoriginalityhealsoplungedintochemistry,theearlyhistoryofWesterncivilization,andtheology;amonghisspecialstudieswasaninvestigationoftheformanddimensions,asdescribedintheBible,ofSolomon'sTempleinJerusalem.

IIOPTICS

In1664,whilestillastudent,NewtonreadrecentworkonopticsandlightbytheEnglishphysicistsRobertBoyleandRobertHooke;healsostudiedboththemathematicsandthephysicsoftheFrenchphilosopherandscientistRenéDescartes.Heinvestigatedtherefractionoflightbyaglassprism;developingoverafewyearsaseriesofincreasinglyelaborate,refined,andexactexperiments,Newtondiscoveredmeasurable,mathematicalpatternsinthephenomenonofcolour.Hefoundwhitelighttobeamixtureofinfinitelyvariedcolouredrays(manifestintherainbowandthespectrum),eachraydefinablebytheanglethroughwhichitisrefractedonenteringorleavingagiventransparentmedium.Hecorrelatedthisnotionwithhisstudyoftheinterferencecoloursofthinfilms(forexample,ofoilonwater,orsoapbubbles),usingasimpletechniqueofextremeacuitytomeasurethethicknessofsuchfilms.Heheldthatlightconsistedofstreamsofminuteparticles.Fromhisexperimentshecouldinferthemagnitudesofthetransparentcorpusclesformingthesurfacesofbodies,which,accordingtotheirdimensions,sointeractedwithwhitelightastoreflect,selectively,thedifferentobservedcoloursofthosesurfaces.

TherootsoftheseunconventionalideaswerewithNewtonbyabout1668;whenfirstexpressed(terselyandpartially)inpublicin1672and1675,theyprovokedhostilecriticism,mainlybecausecolourswerethoughttobemodifiedformsofhomogeneouswhitelight.Doubts,andNewton'srejoinders,wereprintedinthelearnedjournals.Notably,thescepticismofChristiaanHuygensandthefailureoftheFrenchphysicistEdméMariottetoduplicateNewton'srefractionexperimentsin1681setscientistsontheContinentagainsthimforageneration.ThepublicationofOpticks,largelywrittenby1692,wasdelayedbyNewtonuntilthecriticsweredead.Thebookwasstillimperfect:thecoloursofdiffractiondefeatedNewton.Nevertheless,Opticksestablisheditself,fromabout1715,asamodeloftheinterweavingoftheorywithquantitativeexperimentation.

IIIMATHEMATICS

Inmathematicstoo,earlybrillianceappearedinNewton'sstudentnotes.Hemayhavelearntgeometryatschool,thoughhealwaysspokeofhimselfasself-taught;certainlyheadvancedthroughstudyingthewritingsofhiscompatriotsWilliamOughtredandJohnWallis,andofDescartesandtheDutchschool.Newtonmadecontributionstoallbranchesofmathematicsthenstudied,butisespeciallyfamousforhissolutionstothecontemporaryproblemsinanalyticalgeometryofdrawingtangentstocurves(differentiation)anddefiningareasboundedbycurves(integration).NotonlydidNewtondiscoverthattheseproblemswereinversetoeachother,buthediscoveredgeneralmethodsofresolvingproblemsofcurvature,embracedinhismethodoffluxionsandinversemethodoffluxions,respectivelyequivalenttoLeibniz'slaterdifferentialandintegralcalculus.Newtonusedthetermfluxion(fromLatinmeaningflow)becauseheimaginedaquantityflowingfromonemagnitudetoanother.Fluxionswereexpressedalgebraically,asLeibniz'sdifferentialswere,butNewtonmadeextensiveusealso(especiallyinthePrincipia)ofanalogousgeometricalarguments.Lateinlife,Newtonexpressedregretforthealgebraicstyleofrecentmathematicalprogress,preferringthegeometricalmethodoftheClassicalGreeks,whichheregardedasclearerandmorerigorous.

Newton'sworkonpuremathematicswasvirtuallyhiddenfromallbuthiscorrespondentsuntil1704,whenhepublished,withOpticks,atractonthequadratureofcurves(integration)andanotherontheclassificationofthecubiccurves.HisCambridgelectures,deliveredfromabout1673to1683,werepublishedin1707.

TheCalculusPriorityDispute

Newtonhadtheessenceofthemethodsoffluxionsby1666.Thefirsttobecomeknown,privately,toothermathematicians,in1668,washismethodofintegrationbyinfiniteseries.InParisin1675GottfriedWilhelmLeibnizindependentlyevolvedthefirstideasofhisdifferentialcalculus,outlinedtoNewtonin1677.NewtonhadalreadydescribedsomeofhismathematicaldiscoveriestoLeibniz,notincludinghismethodoffluxions.In1684Leibnizpublishedhisfirstpaperoncalculus;asmallgroupofmathematicianstookuphisideas.

Inthe1690sNewton'sfriendsproclaimedthepriorityofNewton'smethodsoffluxions.SupportersofLeibnizassertedthathehadcommunicatedthedifferentialmethodtoNewton,althoughLeibnizhadclaimednosuchthing.Newtoniansthenasserted,rightly,thatLeibnizhadseenpapersofNewton'sduringaLondonvisitin1676;inreality,Leibnizhadtakennonoticeofmaterialonfluxions.Aviolentdisputesprangup,partpublic,partprivate,extendedbyLeibniztoattacksonNewton'stheoryofgravitationandhisideasaboutGodandcreation;itwasnotendedevenbyLeibniz'sdeathin1716.ThedisputedelayedthereceptionofNewtonianscienceontheContinent,anddissuadedBritishmathematiciansfromsharingtheresearchesofContinentalcolleaguesforacentury.

IVMECHANICSANDGRAVITATION

Accordingtothewell-knownstory,itwasonseeinganapplefallinhisorchardatsometimeduring1665or1666thatNewtonconceivedthatthesameforcegovernedthemotionoftheMoonandtheapple.HecalculatedtheforceneededtoholdtheMooninitsorbit,ascomparedwiththeforcepullinganobjecttotheground.Healsocalculatedthecentripetalforceneededtoholdastoneinasling,andtherelationbetweenthelengthofapendulumandthetimeofitsswing.TheseearlyexplorationswerenotsoonexploitedbyNewton,thoughhestudiedastronomyandtheproblemsofplanetarymotion.

CorrespondencewithHooke(1679-1680)redirectedNewtontotheproblemofthepathofabodysubjectedtoacentrallydirectedforcethatvariesastheinversesquareofthedistance;hedeterminedittobeanellipse,soinformingEdmondHalleyinAugust1684.Halley'sinterestledNewtontodemonstratetherelationshipafresh,tocomposeabrieftractonmechanics,andfinallytowritethePrincipia.

BookIofthePrincipiastatesthefoundationsofthescienceofmechanics,developinguponthemthemathematicsoforbitalmotionroundcentresofforce.Newtonidentifiedgravitationasthefundamentalforcecontrollingthemotionsofthecelestialbodies.Heneverfounditscause.Tocontemporarieswhofoundtheideaofattractionsacrossemptyspaceunintelligible,heconcededthattheymightprovetobecausedbytheimpactsofunseenparticles.

BookIIinauguratesthetheoryoffluids:Newtonsolvesproblemsoffluidsinmovementandofmotionthroughfluids.Fromthedensityofairhecalculatedthespeedofsoundwaves.

BookIIIshowsthelawofgravitationatworkintheuniverse:Newtondemonstratesitfromtherevolutionsofthesixknownplanets,includingtheEarth,andtheirsatellites.However,hecouldneverquiteperfectthedifficulttheoryoftheMoon'smotion.Cometswereshowntoobeythesamelaw;inlatereditions,Newtonaddedconjecturesonthepossibilityoftheirreturn.Hecalculatedtherelativemassesofheavenlybodiesfromtheirgravitationalforces,andtheoblatenessofEarthandJupiter,alreadyobserved.HeexplainedtidalebbandflowandtheprecessionoftheequinoxesfromtheforcesexertedbytheSunandMoon.Allthiswasdonebyexactcomputation.

Newton'sworkinmechanicswasacceptedatonceinBritain,anduniversallyafterhalfacentury.Sincethenithasbeenrankedamonghumanity'sgreatestachievementsinabstractthought.Itwasextendedandperfectedbyothers,notablyPierreSimondeLaplace,withoutchangingitsbasisanditsurvivedintothelate19thcenturybeforeitbegantoshowsignsoffailing.SeeQuantumTheory;Relativity.

VALCHEMYANDCHEMISTRY

Newtonleftamassofmanuscriptsonthesubjectsofalchemyandchemistry,thencloselyrelatedtopics.Mostofthesewereextractsfrombooks,bibliographies,dictionaries,andsoon,butafewareoriginal.Hebeganintensiveexperimentationin1669,continuingtillheleftCambridge,seekingtounravelthemeaningthathehopedwashiddeninalchemicalobscurityandmysticism.Hesoughtunderstandingofthenatureandstructureofallmatter,formedfromthesolid,massy,hard,impenetrable,movableparticlesthathebelievedGodhadcreated.MostimportantlyintheQueriesappendedtoOpticksandintheessayOntheNatureofAcids(1710),Newtonpublishedanincompletetheoryofchemicalforce,concealinghisexplorationofthealchemists,whichbecameknownacenturyafterhisdeath.

VIHISTORICALANDCHRONOLOGICALSTUDIES

Newtonownedmorebooksonhumanisticlearningthanonmathematicsandscience;allhislifehestudiedthemdeeply.Hisunpublishedclassicalscholia—explanatorynotesintendedforuseinafutureeditionofthePrincipia—revealhisknowledgeofpre-Socraticphilosophy;hereadtheFathersoftheChurchevenmoredeeply.NewtonsoughttoreconcileGreekmythologyandrecordwiththeBible,consideredtheprimeauthorityontheearlyhistoryofmankind.InhisworkonchronologyheundertooktomakeJewishandpagandatescompatible,andtofixthemabsolutelyfromanastronomicalargumentabouttheearliestconstellationfiguresdevisedbytheGreeks.HeputthefallofTroyat904BC,about500yearslaterthanotherscholars;thiswasnotwellreceived.

VIIRELIGIOUSCONVICTIONSANDPERSONALITY

NewtonalsowroteonJudaeo-Christianprophecy,whosedeciphermentwasessential,hethought,totheunderstandingofGod.Hisbookonthesubject,whichwasreprintedwellintotheVictorianAge,representedlifelongstudy.ItsmessagewasthatChristianitywentastrayinthe4thcenturyAD,whenthefirstCouncilofNicaeapropoundederroneousdoctrinesofthenatureofChrist.ThefullextentofNewton'sunorthodoxywasrecognizedonlyinthepresentcentury:butalthoughacriticofacceptedTrinitariandogmasandtheCouncilofNicaea,hepossessedadeepreligioussense,veneratedtheBibleandaccepteditsaccountofcreation.InlateeditionsofhisscientificworksheexpressedastrongsenseofGod'sprovidentialroleinnature.

VIIIPUBLICATIONS

NewtonpublishedaneditionofGeographiageneralisbytheGermangeographerVareniusin1672.Hisownlettersonopticsappearedinprintfrom1672to1676.ThenhepublishednothinguntilthePrincipia(publishedinLatinin1687;revisedin1713and1726;andtranslatedintoEnglishin1729).ThiswasfollowedbyOpticksin1704;arevisededitioninLatinappearedin1706.PosthumouslypublishedwritingsincludeTheChronologyofAncientKingdomsAmended(1728),TheSystemoftheWorld(1728),thefirstdraftofBookIIIofthePrincipia,andObservationsuponthePropheciesofDanielandtheApocalypseofStJohn