21世紀實用英語綜合教程2教學U8-B2公開課一等獎省優(yōu)質(zhì)課大賽獲獎?wù)n件

Unit8Ⅰ.ObjectivesⅡ.SuggestedTeachingPlanⅢ.BackgroundInformationⅣ.ClassPresentationPreviewPreviewThisisthelastunitofBookTwo.IntheListeningandSpeakingsection,youwilllearnhowtoaskforandgivereasons.IntheReadingandWritingsection,youwillreadthreepassagesaboutscienceandtechnology.TextAwaswrittenattheturnofthe21stcenturyandthewriterpredictedthetopfivescientificdevelopmentsofthecomingcentury.TextBconcernsissuesofsafetythatmustbeguaranteedwhenthefrontierofscienceandtechnologyisbeingpushedback.PracticalReadingisaformthatpeopleneedtofilloutuponarrivalintheU.S.prev.Ⅰ.ObjectivesAfterstudyingthisunit,thestudentsareexpectedtobeabletoObj.masterthebasiclanguageandskillsnecessarytoaskforandgivereasons;1.understandthemainideasofTextsAandB,andmastertheusefulsentencestructuresandwordsandexpressionsfoundintheexercisesrelevanttothetexts;2.3.knowhowtouseV-ingphrases,V-edphrasesandToVphrasesasadverbials;4.knowhowtowriteanemail;6.understandparagraphdevelopment(5).5.readaformthatpeopleneedtofilloutuponarrivalintheU.S.Ⅱ.SuggestedTeachingPlanSuggestedTimeandTeachingPlanforUnit8TimeContentsPlan

1)TheLanguageforAskingForandGivingReasonsGiveabrieflead-intalkonthenatureandusesofaskingforandgivingreasons;A.s.t.p.1TheteacherbeginswiththePreviewtomakesurethatthestudentshaveageneralideaofwhatthisunitisallabout.Afterthat,theteacheractivateslisteningandSpeakingexercisesasfollows:2periodsPreviewListeningandSpeakingB.PresentthenecessarylanguagebydoingExercise1;C.Askonestudenttoreadaloudthetalksostudentscanchecktheircompletedanswers;D.OrganizeanactivityforEx.2thatwillreinforcetheusefullanguagestudentspickedupinEx.1.TimeContentsPlan

s.t.p.1.22)ThePracticeofAskingForandGivingReasonsGothroughthenewwordsinthefirstconversationinEx.3;A.B.Havethestudentslistentotheconversationtwiceandfillintheblankswiththemissingwords;C.Askthemtoanswerthequestionsabouttheconversation;D.Tellthemtolookforthelanguageusedtoaskingforandgivingreasons;TimeContentsPlan

s.t.p.2Askthestudentstorole-playtheconversation;Havethemlistentothesecondconversationtwiceandcompletetheshortpassageaccordingly;F.E.Suggesttheydiscusseachoftheircompletedanswersinordertogainabetterunderstandingoftheconversation;G.Now,havethemlistentotheconversationagainandcompletetheformasthespeakerrecountsit;H.Afterwards,havethemchecktheirresponsesbyactingouttheconversation;I.TimeContentsPlan

s.t.p.33)ListeningPracticeBeforeending,theteachertellsthestudentstodoEx.5-10astheirassignmenttoreviewthefunctionalandnotionallanguagepickedupintheListeningandSpeakingsection.TheteacheralsotellsthemthattheyshouldbepreparedtoanswerthequestionsinExercise9andgiveanoralpresentationinclasswhentheynextmeet.OrganizeauniqueclassroomactivityforEx.4thatwillreinforcetheusefullanguagestudentspickedupearlierintheunit.J.3periodsReviewofthelisteningandspeakingskillsthestudentshavelearnedTheteacherbeginswithareviewofthefunctionalandnotionallanguagethestudentspickedupinthepreviousclasses.TheteacherasksseveralstudentstoanswerthequestionsinEx.9oftheListeningandSpeakingsection,andinvitesafewtosharewiththeirclassmatestheiropinionsonthetopic“Itismoreimportanttoraisequestionsthantoanswerthem.”Then,theteacherturnstotheReadingandWritingsection.(Theseactivitiesshouldbecompletedin15minutes.)s.t.p.4TimeContentsPlan

1)StarterAfterabriefexplanationoftheinstructions,theteacherA.givesthestudentsafewminutestothinkaboutthequestionsinthestarter;s.t.p.5TimeContentsPlan

B.askssomestudentstoanswerthequestions.2)TextAA.Theteacherletsthestudentsanswerthetext-relatedquestions,helpsthemidentifythemainideaofeachparagraph,andanalyzessomedifficultsentencesandsomelanguageTextA&text-relatedexercises

B.guidesthestudentsthroughtheexercises,focusingoncertainitemsorleavingsomeexercisesasthestudentshomeworkaccordingtothestudentsdifferentlevelsofEnglish(oneperiod).s.t.p.81periodGrammarReview1)GrammarReviewTheteachertalksabouttheuseofV-ingphrases,V-edphrasesandToV-phrasesasadverbials,andatthesametimeasksthestudentstodothegrammarexercisesinclass.TimeContentsPlan

pointswhilediscussingthewholetextwiththestudents(oneandahalfperiods);s.t.p.9PracticalWriting2)PracticalWritingTheteacherexplainstothestudentshowtowriteanemailbydoingEx.12ofPracticalWriting,andthenrequiresthestudentstodoEx.13andEx.14afterclass.TimeContentsPlan

s.t.p.102periodsTextB,&Text-relatedexercises1)TextBWhilediscussingthetextwiththestudents,theteachercallsonthemtopayattentiontothestructureoftheparagraphsofthetext,introducingbrieflytheconceptofthetopicsentence.Ex.16andEx.17canbedoneeitherinorafterclass.2)PracticalReadingThispartshouldeitherbereadbythestudentsthemselvesastheirhomeworkordoneinclass.TimeContentsPlan

PracticalReadings.t.p.11BasicReadingSkills3)BasicReadingSkillsTheteacherexplainstothestudentsparagraphdevelopment(5),andasksthemtodotheexercisesinBasicReadingSkills.TimeContentsPlan

Ⅲ.BackgroundInformationJamesTrefilOriginalTextof“TheTop5ScientificBreakthroughsofthe21stCentury”BIModernScience(20thcentury)ThreeMileIslandTheChernobylAccidentRadiationsicknessSovietUnionandRussiaBI-JTJamesTrefilAsanaward-winningauthorandphysicist,JamesTrefilhaswrittenmorethan25booksonarangeofsciencetopics.He’sacontributortoNationalPublicRadioandSmithsonianMagazine,andaphysicsprofessoratVirginia’sGeorgeMasonUniversity,U.S.A.OriginalTextof“TheTop5ScientificBreakthroughsofthe21stCentury”The20thcenturyproducedscientificandtechnologicalchangeatadizzyingpace-greaterthaninanyothercenturyinhistory.Butthe21stcentury,thedawnofthenewmillennium,maywellseeevenmoredramaticchangedrivenbyadvancesinscienceandtechnology.Onthesepagesaremypredictionsforthetopscientificdevelopmentswe’llseeinthenext100years,intheorderIthinkthey’llhappen.BI-OT1(其中提及了作者進行預測依據(jù))JamesTrefilBI-OT21.We’llknowwherewecamefrom

Whydoestheuniverseexist?Toputitanotherway,whyistheresomethinginsteadofnothing?Sincethe1920s,scientistshaveknowntheuniverseisexpanding,whichmeansitmusthavestartedatadefinitetimeinthepast.Theyevenhavedevelopedtheoriesthatgiveadetailedpictureoftheevolutionoftheuniversefromthetimeitwasafractionofasecondoldtothepresent.Overthenextcoupleofdecades,thesetheorieswillberefinedbydatafromextraordinarilypowerfulnewtelescopesandadvancesinourunderstandingofhowmatterbehavesattheunfathomablyhightemperaturesandpressuresoftheearlyuniverse.BI-OT2MargaretGelleroftheHarvard-SmithsonianCenterforAstrophysics,apioneerinexploringthestructureoftheuniverse,believesthat“by2100,wewillhaveacompletemapofallthegalaxiesinthevisibleuniverse.”ConsideringthatthefirstprimitivemapsofNorthAmerica(producedbyexplorerswhofollowedColumbus)appearedonly500yearsago,amerecenturytomapeverygalaxywithin15billionlight-yearsofEarthseemsabreathtakingaccomplishment.BI-OT32.We’llcrackthegeneticcodeandconquercancer

In19th-centuryoperas,whentheheroinecoughsinthefirstact,theaudienceknowsshewilldieoftuberculosisinAct3.Butthanksto20thcenturyantibiotics,theonce-dreaded,once-incurablediseasenowcanmeannothingmoreseriousthantakingsomepills.Asscientistslearnmoreaboutthegeneticcodeandthewaycellsworkatthemolecularlevel,manyseriousdiseases—cancer,forone—willbecomelessthreatening.Usingmanufactured“therapeutic”viruses,doctorswillbeabletoreplacecancer-causingdamagedDNAwithhealthygenes,probablyadministeredbyapillorinjection.BI-OT3FrenchAndersonoftheUniversityofSouthernCaliforniaMedicalSchool,whodidthefirstgene-therapytreatmentonahuman,predictsthat“in15or20years,themajorityofdiseaseswillbetreatableinthisway.”Bytheendofthenextcentury,peoplewilllookatourfearofcancerthewaywenowlookattheoperaticfearofTB:asaquaintrelicofanimmaturetechnology.

BI-OT43.We’lllivelonger(120years?)

Ifthenormalagingprocessisbasicallyafurious,invisiblecontestinourcells—acontestbetweendamagetoourDNAandourcells’abilitytorepairthatdamage—then21st-centurystridesingeneticmedicinemayletuscontrolandevenreversetheprocess.Expertsinthisfielddistinguishbetweenincreasinglongevity(extendingtheaveragelifespan—now76.5yearsintheUnitedStates—aswehavebeendoingforcenturies)andincreasingthemaximumpossiblelifespan(whichseemstobeabout120years).Nodoubtwecanachievethefirst,butexpertsarereluctanttospeculateaboutthesecond.SaysRitaEffrosoftheUCLASchoolofBI-OT4Medicine,aleadingresearcheronagingandtheimmunesystem:“Ithink120yearsofgoodhealthisenoughforanyone.”Sobeforewepushscientiststodomore,consider:Dowereallywanttoliveinaworldwherenoonegrowsoldand(presumably)fewchildrenarebornbecausetheplanetcanholdonlysomanypeople?Wherewouldnewideascomefrom?Whatwouldwedowithallthatextratime?Andwouldyoureallywanttobeadeputyassistantmanagerfor500years?BI-OT64.We’ll“manage”Earth

Inthenextmillennium,we’llstoptalkingabouttheweatheranddosomethingaboutit.DavidTilmanoftheUniversityofMinnesota,apioneerindevelopingandtestingecologicaltheories,says,“Theworld’secosystemsareincrediblycomplex,andthejobofunderstandingthemismadeharderbythefactthattheyarebeingchangedbytheinfluenceofhumanbeings.”Aswebuildbiggerandfastercomputers,however,themysteryandunpredictabilitywillstarttofade.BI-OT6We’llgraduallylearnhowtopredicttheeffectsofhumanactivityontheEarth,itsclimateanditsecosystems.Andwiththatknowledgewillcomeanincreasingwillingnesstouseittomanagetheworkingsofourplanet.Earthwillbemanaged,likeafarmoragamepreserve.TheDutchhavebeendoingthissortofthingonasmallerscaleforcenturiesinmanagingtheirsystemofdikes.Iseenoreasonhumanityorganizedinaglobalvillagecan’tdothesame.BI-OT55.We’llhaveabrain“roadmap”

Thisisthereal“finalfrontier”ofthe21stcentury:Thebrainisthemostcomplexsystemweknow.Itcontainsabout100billionneurons(roughlythenumberofstarsintheMilkyWay),eachconnectedtoasmanyas1,000others.Earlyinthenextcentury,wewilluseadvancedformsofmagneticresonanceimagingtoproducedetailedmapsoftheneuronsinoperation.We’llbeabletosaywithcertaintywhichonesareworkingwhenyoureadaword,whenyousayaword,whenyouthinkaboutaword,andsoon.

BI-OT7StevenPinkeroftheMassachusettsInstituteofTechnology,notedpsychologistandauthorofthebookHowtheMindWorks,predictsthatinthenextcentury“we’lllearnalotaboutthingswedon’tunderstandtoday:humanemotions,socialrelationships,reasoninganddecision-making.”We’llseenewtreatmentsforspecificmentalconditions(astoday’sProzactreatsdepression).We’lldevelopmedicinesthatenhancementalfunctions—likethesteroidsathletesusetopromotemusclegrowth,butwithouttheharmfulsideeffects.Sowiththisfifthpredictionwecomefullcircle,andrealizethatthemostdifficultthingtounderstandintheuniversemaybethe3-poundorganwecarryaroundinourskulls—theorganthatallowsustounderstandtheuniverseinthefirstplace.BI-MS1ModernScience(20thcentury)Inthe20thcentury,scientistsachievedspectacularadvancesinthefieldsofgenetics,medicine,socialsciences,technology,andphysics.1.GeneticsAtthebeginningofthe20thcentury,thelifesciencesenteredaperiodofrapidprogress.Mendel’sworkingeneticswasrediscoveredin1900,andby1910biologistshadbecomeconvincedthatgenesarelocatedinchromosomes,thethreadlikestructuresthatcontainproteinsanddeoxyribo-nucleicacid(DNA).Duringthe1940sAmericanbiochemistsdiscoveredthatDNAtakenfromonekindofbacteriumcouldinfluencethecharacteristicsofanother.Fromtheseexperiments,itbecameclearthatDNAisthechemicalthatmakesupgenesandthusthekeytoheredity.BI-MS2AfterAmericanbiochemistJamesWatsonandBritishbiophysicistFrancisCrickestablishedthestructureofDNAin1953,geneticistsbecameabletounderstandheredityinchemicalterms.Sincethen,progressinthisfieldhasbeenastounding.Scientistshaveidentifiedthecompletegenome,orgeneticcatalog,ofthehumanbody(seeHumanGenomeProject).Inmanycases,scientistsnowknowhowindividualgenesbecomeactivatedandwhateffectstheyhaveinthehumanbody.Genescannowbetransferredfromonespeciestoanother,side-steppingthenormalprocessesofheredityandcreatinghybridorganismsthatareunknowninthenaturalworld(seeTransgenicOrganism).BI-MS32.MedicineAttheturnofthe20thcentury,DutchphysicianChristiaanEijkmanshowedthatdiseasecanbecausednotonlybymicroorganismsbutbyadietarydeficiencyofcertainsubstancesnowcalledvitamins.In1909GermanbacteriologistPaulEhrlichintroducedtheworld’sfirstbactericide,achemicaldesignedtokillspecifickindsofbacteriawithoutkillingthepatient’scellsaswell.Followingthediscoveryofpenicillinin1928byBritishbacteriologistSirAlexanderFleming,antibioticsjoinedmedicine’schemicalarmory,makingthefightagainstbacterialinfectionalmostaroutinematter.Antibioticscannotactagainstviruses,butvaccineshavebeenusedtogreateffecttopreventsomeofthedeadliestviraldiseases.Smallpox,onceaworldwidekiller,wascompletelyeradicatedbythelate1970s,andintheUnitedStatesthenumberofpoliocasesdroppedfrom38,000inthe1950stolessthan10ayearbythe21stcentury.BI-MS4

Bythemiddleofthe20thcenturyscientistsbelievedtheywerewellonthewaytotreating,preventing,oreradicatingmanyofthemostdeadlyinfectiousdiseasesthathadplaguedhumankindforcenturies.Butbythe1980sthemedicalcommunity’sconfidenceinitsabilitytocontrolinfectiousdiseaseshadbeenshakenbytheemergenceofnewtypesofdisease-causingmicroorganisms.Newcasesoftuberculosisdeveloped,causedbybacteriastrainsthatwereresistanttoantibiotics.New,deadlyinfectionsforwhichtherewasnoknowncurealsoappeared,includingthevirusesthatcausehemorrhagicfeverandthehumanimmunodeficiencyvirus(HIV),thecauseofacquiredimmunodeficiencysyndrome.Inotherfieldsofmedicine,thediagnosisofdiseasehasbeenrevolutionizedbytheuseofnewimagingtechniques,BI-MS5includingmagneticresonanceimagingandcomputedtomography.Scientistswerealsoonthevergeofsuccessincuringsomediseasesusinggenetherapy,inwhichtheinsertionofnormalorgeneticallyalteredgenesintoapatient’scellsreplacesnonfunctionalormissinggenes.Improveddrugsandnewtoolshavemadesurgicaloperationsthatwereonceconsideredimpossiblenowroutine.Forinstance,drugsthatsuppresstheimmunesystemenablethetransplantoforgansortissueswithareducedriskofrejection(seeMedicalTransplantation).Endoscopypermitsthediagnosisandsurgicaltreatmentofawidevarietyofailmentsusingminimallyinvasivesurgery.Advancesinhigh-speedfiber-opticconnectionspermitsurgeryonapatientusingroboticinstrumentscontrolledbysurgeonsatanotherlocation.Knownastelemedicine,thisformofmedicinemakesitpossibleforskilledphysicianstotreatpatientsinremotelocationsorplacesthatlackmedicalhelp.BI-MS63.SocialSciencesInthe20thcenturythesocialsciencesemergedfromrelativeobscuritytobecomeprominentfieldsofresearch.AustrianphysicianSigmundFreudfoundedthepracticeofpsychoanalysis,creatingarevolutioninpsychologythatledhimtobecalledthe“Copernicusofthemind.”In1948theAmericanbiologistAlfredKinseypublishedSexualBehaviorintheHumanMale,whichprovedtobeoneofthebest-sellingscientificworksofalltime.Althoughcriticizedforhismethodologyandconclusions,Kinseysucceededinmakinghumansexualityanacceptablesubjectforscientificresearch.BI-MS6The20thcenturyalsobroughtdramaticdiscoveriesinthefieldofanthropology,withnewfossilfindshelpingtopiecetogetherthestoryofhumanevolution.AcompletelynewandsurprisingsourceofanthropologicalinformationbecameavailablefromstudiesoftheDNAinmitochondria,cellstructuresthatprovideenergytofuelthecell’sactivities.MitochondrialDNAhasbeenusedtotrackcertaingeneticdiseasesandtotracetheancestryofavarietyoforganisms,includinghumans.BI-MS74.TechnologyInthefieldofcommunications,ItalianelectricalengineerGuglielmoMarconisenthisfirstradiosignalacrosstheAtlanticOceanin1901.AmericaninventorLeeDeForestinventedthetriode,orvacuumtube,in1906.Thetriodeeventuallybecameakeycomponentinnearlyallearlyradio,radar,television,andcomputersystems.In1920ScottishengineerJohnLogieBairddevelopedtheBairdTelevisor,aprimitivetelevisionthatprovidedthefirsttransmissionofarecognizablemovingimage.Inthe1920sand1930sAmericanelectronicengineerVladimirKosmaZworykinsignificantlyimprovedthetelevision’spictureandreception.In1935BritishphysicistSirRobertWatson-Wattusedreflectedradiowavestolocateaircraftinflight.RadarsignalshavesincebeenreflectedfromtheMoon,planets,andstarstolearntheirdistancefromEarthandtotracktheirmovements(seeRadarAstronomy).BI-MS8In1947AmericanphysicistsJohnBardeen,WalterBrattain,andWilliamShockleyinventedthetransistor,anelectronicdeviceusedtocontroloramplifyanelectricalcurrent.Transistorsaremuchsmaller,farlessexpensive,requirelesspowertooperate,andareconsiderablymorereliablethantriodes.Sincetheirfirstcommercialuseinhearingaidsin1952,transistorshavereplacedtriodesinvirtuallyallapplications.Duringthe1950sandearly1960sminicomputersweredevelopedusingtransistorsratherthantriodes.Earliercomputers,suchastheelectronicnumericalintegratorandcomputer(ENIAC),firstintroducedin1946byAmericanphysicistJohnW.MauchlyandAmericanelectricalengineerJohnPresperEckert,Jr.,usedasmanyas18,000triodesBI-MS8andfilledalargeroom.Butthetransistorinitiatedatrendtowardmicrominiaturization,inwhichindividualelectroniccircuitscanbereducedtomicroscopicsize.Thisdrasticallyreducedthecomputer’ssize,cost,andpowerrequirementsandeventuallyenabledthedevelopmentofelectroniccircuitswithprocessingspeedsmeasuredinbillionthsofasecond.

Furtherminiaturizationledin1971tothefirstmicro-processor—acomputeronachip.Whencombinedwithotherspecializedchips,themicroprocessorbecomesthecentralarithmeticandlogicunitofacomputersmallerinsizethanaportabletypewriter.WiththeirsmallsizeandaBI-MS9pricelessthanthatofausedcar,today’spersonalcomputersaremanytimesmorepowerfulthanthephysicallyhuge,multimillion-dollarcomputersofthe1950s.Onceusedonlybylargebusinesses,computersarenowusedbyprofessionals,smallretailers,andstudentstoperformawidevarietyofeverydaytasks,suchaskeepingdataonclients,trackingbudgets,andwritingschoolreports.Peoplealsousecomputerstointerfacewithworldwidecommunicationsnetworks,suchastheInternetandtheWorldWideWeb,tosendandreceivee-mail,toshop,ortofindinformationonjustaboutanysubject.BI-MS10Duringtheearly1950spublicinterestinspaceexplorationdeveloped.ThefocaleventthatopenedthespaceagewastheInternationalGeophysicalYearfromJuly1957toDecember1958,duringwhichhundredsofscientistsaroundtheworldcoordinatedtheireffortstomeasuretheEarth’snear-spaceenvironment.Aspartofthisstudy,boththeUnitedStatesandtheSovietUnionannouncedthattheywouldlaunchartificialsatellitesintoorbitfornonmilitaryspaceactivities.WhentheSovietUnionlaunchedthefirstSputniksatellitein1957,thefeatspurredtheUnitedStatestointensifyitsownspaceexplorationefforts.In1958theBI-MS10NationalAeronauticsandSpaceAdministration(NASA)wasfoundedforthepurposeofdevelopinghumanspaceflight.Throughoutthe1960sNASAexperienceditsgreatestgrowth.Amongitsachievements,NASAdesigned,manufactured,tested,andeventuallyusedtheSaturnrocketandtheApollospacecraftforthefirstmannedlandingontheMoonin1969(seeApolloProgram).Inthe1960sand1970s,NASAalsodevelopedthefirstroboticspaceprobestoexploretheplanetsMercury,Venus,andMars(seeMariner).ThesuccessoftheMarinerprobespavedthewayfortheunmannedexplorationoftheouterplanetsinEarth’ssolarsystem.Inthe1970sthrough1990s,NASAfocuseditsspaceexplorationeffortsonareusablespaceshuttle,whichwasBI-MS11firstdeployedin1981.In1998thespaceshuttle,alongwithitsRussiancounterpartknownasSoyuz,becametheworkhorsesthatenabledtheconstructionoftheInternationalSpaceStation.

5.PhysicsIn1900theGermanphysicistMaxPlanckproposedthethensensationalideathatenergyisnotinfinitelydivisiblebutisalwaysgivenoffinsetamounts,orquanta.Fiveyearslater,German-bornAmericanphysicistAlbertEinsteinsuccessfullyusedquantatoexplainthephotoelectriceffect,whichisthereleaseofelectronswhenmetalsarebombardedbylight.This,togetherwithEinstein’sspecialandgeneraltheoriesofrelativity,challengedsomeofthemostfundamentalassumptionsoftheNewtonianera.BI-MS12

Unlikethelawsofclassicalphysics,quantumtheorydealswitheventsthatoccuronthesmallestofscales.Quantumtheoryexplainshowsubatomicparticlesformatoms,andhowatomsinteractwhentheycombinetoformchemicalcompounds.Quantumtheorydealswithaworldwheretheattributesofanysingleparticlecanneverbecompletelyknown-anideaknownastheuncertaintyprinciple,putforwardbytheGermanphysicistWernerHeisenbergin1927.Butwhilethereisuncertaintyonthesubatomiclevel,quantumphysicssuccessfullypredictstheoveralloutcomeofsubatomicevents,afactthatfirmlyrelatesittothemacroscopicworld-thatis,theoneinwhichwelive.BI-MS12In1934Italian-bornAmericanphysicistEnricoFermibeganaseriesofexperimentsinwhichheusedneutrons(subatomicparticleswithoutanelectriccharge)tobombardatomsofvariouselements,includinguranium.Theneutronscombinedwiththenucleioftheuraniumatomstoproducewhathethoughtwereelementsheavierthanuranium,knownastransuraniumelements.In1939otherscientistsdemonstratedthatintheseexperimentsFermihadnotformedheavierelements,butinsteadhadachievedthesplitting,orfission,oftheuraniumatom’snucleus.Theseearlyexperimentsledtothedevelopmentoffissionasbothanenergysource(seeNuclearEnergy)andaweapon(seeAtomicBomb).BI-MS13

Thesefissionstudies,coupledwiththedevelopmentofparticleacceleratorsinthe1950s,initiatedalongandremarkablejourneyintothenatureofsubatomicparticlesthatcontinuestoday.Farfrombeingindivisible,scientistsnowknowthatatomsaremadeupof12fundamentalparticlesknownasquarksandleptons,whichcombineindifferentwaystomakeallthekindsofmattercurrentlyknown.

Advancesinparticlephysicshavebeencloselylinkedtoprogressincosmology.Fromthe1920sonward,whentheAmericanastronomerEdwinHubbleshowedthattheuniverseisexpanding,cosmologistshavesoughttorewindtheclockandestablishhowtheuniversebegan.Today,mostscientistsBI-MS14believethattheuniversestartedwithacosmicexplosionsometimebetween10and20billionyearsago(seeBigBangTheory).However,theexactsequenceofeventssurroundingitsbirth,anditsultimatefate,arestillmattersofongoingdebate.(ByDavidBurnie.FromtheMicrosoftEncartaReferenceLibrary)

BI-TMThreeMileIslandisanislandintheSusquehannaRiverinDauphinCounty,Pennsylvania,nearHarrisburg,ofarea3.29km2(814acres).ThenameismostcommonlyassociatedwithanaccidentattheThreeMileIslandNuclearGeneratingStationonMarch28,1979,whenreactorTMI-2sufferedapartialcoremeltdown.ThreeMileIslandNoidentifiableinjuriesduetoradiationoccurred(althoughagovernmentreportbyL.Battistet.al.statedthat“theprojectednumberofexcessfatalcancersduetotheaccident…isapproximatelyone.”)Itwas,however,aseriouseconomicandpublicrelationsdisaster.Italsofurtheredaseriousdeclineinthepublicpopularityofnuclearpower.(FromtheWikipedia)BI-TCA1TheChernobylAccident

Therehavebeendifferentreportsabouttheconsequencesoftheaccident.Twodifferentversionshavebeenpresentedbelow.BI-TCA1TheChernobylaccidentin1986wastheresultofaflawedreactordesignthatwasoperatedwithinadequatelytrainedpersonnelandwithoutproperregardforsafety.Theresultingsteamexplosionandfirereleasedatleastfivepercentoftheradioactivereactorcoreintotheatmosphereanddownwind.Some31peoplewerekilled,andtherehavesincebeenaroundtendeathsfromthyroidcancerduetotheaccident.AnauthoritativeUNreportinconcludedtha