高中英语Unit1 Great scientists文章 Hawking, Stephen William人教版必修五VIP专享VIP免费

Hawking,StephenWilliamHawking,StephenWilliam(1942-),Britishtheoreticalphysicistandmathematicianwhosemainfieldofresearchhasbeenthenatureofspaceandtime,includingirregularitiesinspaceandtimeknownassingularities.Hawkinghasalsodevotedmuchofhislifetomakinghistheoriesaccessibletothepublicthroughlectures,books,andfilms.HawkingwasborninOxford,England,andheshowedexceptionaltalentinmathematicsandphysicsfromanearlyage.HeenteredOxfordUniversityin1958andbecameespeciallyinterestedinthermodynamics(thestudyoftheinteractionofmatterandenergy),relativitytheory,andquantummechanics(seeQuantumTheory).In1961heattendedasummercourseattheRoyalObservatorythatencouragedtheseinterests.Hecompletedhisundergraduatecoursesin1962andreceivedabachelor’sdegreeinphysics.HawkingthenenrolledasaresearchstudentingeneralrelativityatthedepartmentofappliedmathematicsandtheoreticalphysicsattheUniversityofCambridge.HawkingearnedhisPh.D.degreefromTrinityCollegeattheUniversityofCambridgein1966.HestayedattheUniversityofCambridge,doingpost-doctoralresearch,untilhebecameaprofessorofphysicsin1977.HebecameoneoftheyoungestfellowsoftheRoyalSocietyin1974.In1979hewasappointedLucasianProfessorofMathematicsatCambridge.Duringhispostgraduateprogram,HawkingwasdiagnosedashavingAmyotrophic用心爱心专心LateralSclerosis(ALS),arareprogressivediseasethathandicapsmovementandspeech.ThisdiseasemakesitnecessaryforHawkingtocarryoutthelongandcomplexmathematicalcalculationsthathisworkrequiresinhishead.Hehasbeenabletocontinuehisstudiesandtoembarkuponadistinguishedandproductivescientificcareerdespitehisillness.Fromitsearlieststages,Hawking’sresearchhasbeenconcernedwiththeconceptofsingularities—breakdownsinspaceandtimewheretheclassiclawsofphysicsnolongerapply.Thecombinationoftimeandthree-dimensionalspaceiscalledspace-time.Themostfamiliarexampleofasingularityisablackhole,thefinalformofacollapsedstar.Muchofwhatscientistsbelieveaboutspace-timecomesfromthetheoryofrelativity,whichwasdevelopedintheearly20thcenturybyGerman-AmericanphysicistAlbertEinstein.Duringthelate1960sHawkingprovedthatifthegeneraltheoryofrelativityiscorrect,thenasingularitymustalsohaveoccurredatthebigbang.Thebigbangistheexplosionthatmarkedthebeginningoftheuniverseandthebirthofspace-timeitself.In1970Hawking’sresearchturnedtotheexaminationofthepropertiesofblackholes.Theboundaryofablackholeiscalledtheeventhorizon.Hawkingrealizedthatthesurfaceareaoftheeventhorizonaroundablackholecouldonlyincreaseorremainconstantwithtime—thisareacouldneverdecrease.Thismeant,forexample,thatiftwoblackholesmerge,thesurfaceareaofthenewblackholewouldbelargerthanthesumofthesurfaceareasofthetwooriginalblackholes.Healsonoticedthattherewerecertainparallelsbetweenthelawsofthermodynamicsandthepropertiesofblackholes.Forinstance,thesecondlawofthermodynamicsstatesthatentropy,ordisorder,must用心爱心专心increasewithtime.Thesurfaceareaoftheeventhorizonofablackholeisthereforesimilartotheentropyofathermodynamicsystem.From1970to1974,HawkingandhisassociatesprovidedmathematicalproofforthehypothesisformulatedbyAmericanphysicistJohnWheelerknownasthe"NoHairTheorem."Thistheoremstatesthattheonlypropertiesthatparticlesofmatterkeeponcetheyenterablackholearemass,angularmomentum(orspin),andelectriccharge.Matterenteringablackholelosesitsshape,itschemicalcomposition,anditsdistinctionasmatterorantimatter.Since1974Hawkinghasstudiedthebe...