arXiv:physics/0602043v1[physics.hist-ph]7Feb20061IndianContributionstoHighEnergyPhysicsinthe20thCenturyG.RajasekaranInstituteofMathematicalSciences,Madras600113.e-mail:graj@imsc.ernet.inAbstract:TheinwardboundpathofdiscoveryunravellingthemysteriesofmatterandtheforcesthatholdittogetherhasculminatedattheendofthetwentiethcenturyinatheoryoftheFundamentalForcesofNaturebasedonNonabelianGaugeFields,calledtheStandardModelofHighEnergyPhysics.Inthisarticlewetracethehistoricaldevelopmentoftheideasandtheexperimentaldiscoveriesonwhichthistheoryisbased.WealsomarksignificantIndiancontributionswhereverpossible.Finallywehaveaglimpseatfuturedevelopments.AnAppendixonmoreIndiancontributionsisaddedattheend.Adisclaimer:Thisisreallyajobforahistorianofscience.Theselectionofthistopicwasnotdonebyme.Thetopicandthetitleweregiventome.Ihavereinterpretedthetitle.Iamnotinterpretingitinanarrowsense.Thatwouldbesuicidalandasureprescriptionforturningeverybodyintomyenemy.Ihavechosenabroadcanvasandabroadbrush.So,yourportraitmaybetoosmalltoshowhere.Inanycase,thisisnotaselectioncommitteeandIamnotassessinganybodyforrecruitmentorpromotion.AllthatIwilltrytodoistogivemyviewofthedevelopmentofFundamentalPhysicsinthe20thcenturyand,ontheway,refertoIndia’scontributions(ifany).Planofthetalk1.Scope2.HEPbeforeandaftertheStandardModel3.FutureofHEP4.PresentStatusinIndiaandSuggestionsforFuture5.AlistofmoreIndiancontributions(ThiswasaninvitedtalkattheXIVDAESymposiumonHighEnergyPhysics,Univer-sityofHyderabad,Dec2000,publishedintheProceedings(Eds:AKKapoor,PKPanigrahiandBinduABambah)p1.)2IndianContributionsToHEPInThe20thCentury0.1ScopeTheearlierpartofthe20thCenturywasmarkedbytworevolutionsthatrockedtheFoun-dationsofPhysics.1.QuantumMechanics&2.RelativityQuantumMechanicsbecamethebasisforunderstandingAtoms,andthen,coupledwithSpe-cialRelativity,QuantumMechanicsprovidedtheframeworkforunderstandingtheAtomicNucleusandwhatliesinside.INWARDBOUNDAtoms−→Nuclei−→Nucleons−→Quarks−→?10−8cm10−12cm10−13cm10−16cmThisinwardboundpathofdiscoveryunravelingthemysteriesofmatterandtheforcesholdingittogether–atdeeperandeverdeeperlevels–hasculminated,attheendofthe20thcentury,inthetheoryofFundamentalForcesbasedonNonabelianGaugeFields,forwhichwehavegivenaratherprosaicname:THESTANDARDMODELOFHIGHENERGYPHYSICSBut,thisisnottheendoftheroad.Moreonthat,later.Thus,HEPisjustthecontinuationoftheeraofdiscoveriesthatsawthediscoveryoftheelectron,thediscoveryofradioactivityandXrays,thediscoveryofthenucleusandtheneutronandthediscoveryofcosmicraysandthepositron.ThesediscoverieswenthandinhandwiththedevelopmentofQuantumMechanics,Rel-ativityandQuantumFieldTheory.For,withouttheconceptualadvancesmadeinthesetheoreticaldevelopments,theaboveexperimentaldiscoveriescouldnothavebeenassimi-latedintotheframeworkofPhysics.So,thepresent-dayHEPmustberegardedasthesuccessortoNuclearPhysics,whichinturnwasthesuccessortoAtomicPhysics:AtomicPhysics−→NuclearPhysics−→HighEnergyPhysics0.1.SCOPE3HEPisthefrontendorcuttingedgeofthehumanintellectadvancingintotheunknownterritoryinitsinwardboundjourney.This100-year-longhistorymustbeviewedtogether,togetatruepictureofHEP.ItiswithinthisbroadframeworkthatwemustplaceanyparticularcontributionorthetotalityofIndiancontributions,foraproperperspective.Viewedinthislight,itisperfectlynaturaltoincludethegreatIndiancontributionsmadeintheearlierpartofthe20thcentury.IfBose,Raman&Sahawerealiveandyoungtoday,theywouldbedoingHEP.So,Istartwiththeircontributions...1.MNSaha’s(1923)theoryofthermalionizationplayedacrucialroleintheelucida-tionofstellarspectraandthuswasoffundamentalimportancefortheprogressofAstrophysics.(Saha’s(1936)reinterpretationofDirac’squantizationconditionformonopoles,intermsofang.mom.quantization,wasveryoriginalanditsimportanceisnowrecognized.)2.SNBose(1924)discoveredQuantumStatisticsevenbeforethediscoveryofQuantumMechanicsbyHeisenberg&Schr¨odingeroneyearlater.Logicallypursued,Bose’sdis-coverybyitselfwouldhaveledtoQuantumMechanics.But,Historywentdifferently.QMwasdiscoveredsoon(infact,toosoon)andthefloodgateswereopen.ThiswasunfortunateforIndia.ThismaybecalledMISSEDOPPORTUNITYI.3.CVRaman(1928)discoveredtheinelasticscatteringofphotononboundelectronsandthustooktheconceptofphotononestephigher.Ramaneffectisafundamentalexperimentaldiscoverythathasnotbeensurpassedorevenequalledinitsimportanceandimpactevenafter70yearsbyanyotherexperimentdoneinthiscountry.4.S.Chandrasekhar(1932)appliedrelativisticquantummechanicstotheinteriorofstars.Hecalculatedthedegeneracypressure(orPaulipressure)ofarelativisticelectrongasandthusinitiatedourunderstandingofthegravitationalcollapseofstars.5.H.J.Bhabha’s(1935)calculationofe+e−scatteringwasoneoftheearliestnontrivialapplicationsofDiracequationtoaprocessinwhichDirac’sholetheoryplayedacrucialrole.Thiswasdoneevenbeforeafull-fledgedQuantumFieldTheoryexisted.4IndianContributionsToHEPInThe20thCentury0.2HEPbeforeandaftertheStandardModel0.2.1QEDL=−14(∂μAν−∂νAμ)2−¯ψγμ(i∂μ−eAμ)ψ−m¯ψψPlanck(1900):QuantizationofradiationenergyEinstein(1905):PhotonBose(1924):PhotonsasidenticalparticlesBo
本文标题:Indian Contributions to High Energy Physics in the
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