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1、21世纪，科学上的未解之谜TheunsolvedmysteriesofScienceinthetwenty-firstCenturyThemysteryoftheoriginoflifeonearthTheageoftheearthisabout4billion500millionyears,andtheinitialappearanceoftheearth'slifeformdatesbackto3billionyearsago.Theoriginoflifeonearthhasalwaysbee
2、nacontroversialissue・Beforethebirthofmodernscience,therewasaconceptof''biologicaloccurrence"・Today,scientistsaremuchmoreawareoftheoriginsoflifethantheywerein17thCenturyand18thCentury.Theyhaveputforwardcluestotheoriginoflifeonearthinmanyways・Buttheanswe
3、rremainsbewildering・Clue1:theprimordialEarthatmosphereisthebirthplaceoforganicmolecules,andthengenerateslife・Oneofthefirstquestionstoaskis:Whydidorganicmoleculesachievesuchbrilliantvictories?Thisismainlybecausetheorganicmoleculeshaverelativelystrongato
4、miccombinations,buttheseatomsarehardtocombine・Itismuchmoredifficulttoproduceacarboncontaining,closelypackedandorderedmulticomponentstructurethantoproducesomethingsuchasthesiliconoxygenstructure・However,oncethiscarbonbasedstructurehasbeencreated,itsuniq
5、uecomplexitywillremainindefinitely,eventuallyleadingtothebirthofalifesystem・Cluetwo:Volcanobreedslife・Primitivevolcanicactivityisfrequent.IntheArchea.ndeep-seavolcanoanditsgeologicalconditionssimilartothemoderndeepoceanridgesoccurlifechemicalsynthesiso
6、faseriesofreactionsinthere,wheretheformationoforganicmolecules,wasbornlastprimitivelifethere.Cluethree:thetheoryoftheoriginofthesky.In1990,NASA'sKevinGillinspproposedthatorganicdustinthestrataneartheCretaceous一thirdboundarywasformedbytheaminoacidsleftb
7、yoneormorecometsskimmingtheearth・Intheearlydaysoftheearth,cometscouldshedorganicmatterinthisway,likealightrain,beneaththeearth,whichisthesourceoflifeonearth・Inaddition,meteoroidsfallingonthegroundprovidevaluablecluesforstudyingtheoriginandevolutionofth
8、esolarsystemandtheoriginoflife・Cluefour:claymineralcrystals・Clay,themostcommonsubstanceonearth,isthefirstlivingsubstance・Claymineralsaretinycrystalsinwhichclaymineralshavesomeofthekeycharacteristicsofthelifesystem・Forexample,somemineral
