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後科學時代的宇宙和生命新思維李政道吳健雄SegreSerberWickWilhelmConradRoentgen(1845-1923)DiscovereroftheX-rayThehandofMrs.WilhelmRoentgen:thefirstX-rayimage,1895MurrayGell-Mann1969NobelPrizewinner,hecoinedthenameofquark”後科學時代的宇宙和生命新思維科學分殊的危機認知的局限物質科學粒子物理MoreUnifiedTheories•Foryears,physicistshavesoughtforandfoundunifiedtheories.•1861-1865•JamesMaxwell,inaseriesofpages,describedtheinterrelationofelectricandmagneticfieldstherebyunifyingthemintoelectromagnetism.Thisledtothenow-famousMaxwell'sEquations.•1881-1884•Hertzdemonstratedradiowavesandestablishedthatradiowavesandlightareelectromagneticwavesofdifferentfrequencies,aspredictedbyMaxwell.HeinrichRudolfHertzJamesClerkMaxwell1967-1970Glashow,Salam,andWeinbergproposedatheorythatunifieselectromagneticandweakinteractions.TheypredictedthemassoftheWbosonwhichmediatesweakprocessessuchasbetadecayandpredictedanewtypeofweakinteractionanditsmediatingparticletheZboson.HiggsBoson.1979TheNobelPrizewasawardedtoGlashow,Salam,andWeinbergfortheirroleinthedevelopmentoftheelectroweaktheory,fouryearsbeforethediscoveryoftheWandZbosons!1983TheWandZbosonswerefinallydiscoveredin1983bytheUA-1andUA-2experimentsatCERN.基本粒子物理電磁理論(JamesMaxwell)+弱作用理論電弱理論+強作用理論標準模型(StandardModel)+重力作用統一場論GrandUnifiedTheoryOneofthebiggestgoalsinphysicstodayistounifythestrong,weak,electromagnetic,andgravitationalforcesintooneunifiedforce,orwhatphysicistscalltheGrandUnifiedTheory.Ithasalreadybeendiscoveredthatathighenoughenergies,electromagnetismandtheweakforcearethesameforce,knownastheelectroweakforce.Itistheorizedthatifenergiesareincreasedevenfurther,alltheknownforceswillboildownintothesameforce.Ifthestandardmodelcanbesimplifiedinthisway,itmayleadintoareasoffurtherstudyinordertogetabettergraspoftheworldaroundus.粒子物理電磁理論(JamesMaxwell)+弱作用理論電弱理論+強作用理論標準模型(StandardModel)+重力作用統一場論誰是EdwardWitten?ManyphysicistsconsiderEdWittentobeEinstein'struesuccessor.什麼是弦理論?Whatisstringtheory?Witten:Stringtheoryisanattemptatadeeperdescriptionofnaturebythinkingofanelementaryparticlenotasalittlepointbutasalittleloopofvibratingstring.Oneofthebasicthingsaboutastringisthatitcanvibrateinmanydifferentshapesorforms,whichgivesmusicitsbeauty.Ifwelistentoatuningfork,itsoundsharshtothehumanear.Andthat'sbecauseyouhearapuretoneratherthanthehigherovertonesthatyougetfromapianoorviolinthatgivemusicitsrichnessandbeauty.•Sointhecaseofoneofthesestringsitcanoscillateinmanydifferentforms--analogouslytotheovertonesofapianostring.Andthosedifferentformsofvibrationareinterpretedasdifferentelementaryparticles:quarks,electrons,photons.Allaredifferentformsofvibrationofthesamebasicstring.Unityofthedifferentforcesandparticlesisachievedbecausetheyallcomefromdifferentkindsofvibrationsofthesamebasicstring.Inthecaseofstringtheory,withourpresentunderstanding,therewouldbenothingmorebasicthanthestring.EssayNature438,1085(22December2005)|ConceptUnravellingstringtheoryEdwardWitten1•（Lasttwoparagraphs)•Butwhatisstringtheory?Itmaywellbetheonlywaytoreconcilegravityandquantummechanics,butwhatisthecoreideabehindit?Einsteinunderstoodthecentralconceptsofgeneralrelativityyearsbeforehedevelopedthedetailedequations.Bycontrast,stringtheoryhasbeendiscoveredinbitsandpieces—overaperiodthathasstretchedfornearlyfourdecades—withoutanyonereallyunderstandingwhatisbehindit.Asaresult,everybitthatisunearthedcomesasasurprise.Westilldon'tknowwherealltheseideasarecomingfrom—orheadingto.•Onedaywemayunderstandwhatstringtheoryreallyis.Butevenifwedo,andthetheoryisontherighttrack,willwebeabletolearnhowitworksinnature?Icertainlyhopeso.Realistically,italldependsonmanyunknowns,includingthenatureoftheanswer,howcleverwewillbe,andtheclueswecangetfromexperiment.SuperstringTheoryWorldNature440,1132-1136(27April2006)|doi:10.1038/nature04804IsourUniversenatural?SeanM.Carroll11.EnricoFermiInstitute,DepartmentofPhysicsandKavliInstituteforCosmologicalPhysics,UniversityofChicago,5640SouthEllisAvenue,Chicago,Illinois60637,USA.Email:carroll@theory.uchicago.eduAbstractItgoeswithoutsayingthatwearestuckwiththeUniversewehave.Nevertheless,wewouldliketogobeyondsimplydescribingourobservedUniverse,andtrytounderstandwhyitisthatwayratherthansomeotherway.WhenconsideringboththestateinwhichwefindourcurrentUniverse,andthelawsofphysicsitobeys,wediscoverfeaturesthatseemremarkablyunnaturaltous.PhysicistsandcosmologistshavebeenexploringincreasinglyambitiousideasinanattempttoexplainhowsurprisingaspectsofourUniversecanarisefromsimpledynamicalprinciples.AnaturalstateforaUniversewithapositivevacuumenergyisemptydeSitterspace;thisisthebackgrounduniverseinthefigure,withtimerunningvertically.Inthepresenceofanappropriatescalarfield,quantumfluctuationsinsuchabackgroundcanleadtothenucleationofbabyuniverses.Eachbabyuniverseiscreatedinaproto-inflationarystate,whichthenexpandsandreheatsintoauniverselikethatweobserve.Theseuniversesareportrayedasevolving'sideways',toemphasizethatthelocaldirectionoftimemaynotberelatedtothatofthebackgroundspace-time.ChenNingYangAlbertEinsteinProfessorEmeritusNobelLaureateinPhysicsYang-MillsTheoryMyPhysicsStringTheoryTheirMathematicsMu