科技英语阅读答案Unit 2Word文档下载推荐.docx
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科技英语阅读答案Unit 2Word文档下载推荐.docx
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Darkmatterisahypothesizedformofmatterparticlethatdoesnotreflectoremitelectromagneticradiation.Theexistenceofdarkmatterisinferredfromgravitationaleffectsonvisiblematter,suchasstarsandgalaxies.
Asmallpercentageofthegravitationaleffectsobservedarefromvisiblematter(someestimatesareaslowas4%oftotalgravitationaleffects).Theremaining96%ispresumedtoresultfromdarkmatterordarkenergy,thoughthesetermsaresomewhatindicativeofourignoranceoftheexactnatureoftheseunknownquantities,astheyhaveneverbeendirectlyobserved.
Onepossiblecandidatefordarkmatteraretheoreticalparticlesknownasweaklyinteractingmassiveparticles(WIMPs),whicharebeingsearchedforbytheCryogenicDarkMatterSearch(CDMS)experiment.
3.Whatisdarkenergy?
Darkenergyisahypotheticalformofenergythatpermeatesspaceandexertsanegativepressure,whichwouldhavegravitationaleffectstoaccountforthedifferencesbetweenthetheoreticalandobservationalresultsofgravitationaleffectsonvisiblematter.Darkenergyisnotdirectlyobserved,butratherinferredfromobservationsofgravitationalinteractionsbetweenastronomicalobjects,alongwithdarkmatter.
Theterm"
darkenergy"
wascoinedbythetheoreticalcosmologistMichaelS.Turner.
4.Haveyoueverheardofthebigbangtheory?
Canyougiveanaccountofit?
TheBigBangisthedominant(andhighlysupported)theoryoftheoriginoftheuniverse.Inessence,thistheorystatesthattheuniversebeganfromaninitialpointorsingularitywhichhasexpandedoverbillionsofyearstoformtheuniverseaswenowknowit.
In1927,RomanCatholicpriestandphysicistGeorgesLemaitreindependentlycalculatedtheFriedmansolutionandagainsuggestedthattheuniversemustbeexpanding.ThistheorywassupportedbyHubblewhen,in1929,hefoundthattherewasacorrelationbetweenthedistanceofthegalaxiesandtheamountofredshiftinthatgalaxy'
slight.Thedistantgalaxiesweremovingawayfaster,whichwasexactlywhatwaspredictedbyLemaitre'
ssolutions.
In1931,Lemaitrewentfurtherwithhispredictions,extrapolatingbackwardsintimefindthatthematteroftheuniversewouldreachaninfinitedensityandtemperatureatafinitetimeinthepast.Thismeanstheuniversemusthavebeguninanincrediblysmall,densepointofmatter-a"
primevalatom."
5.Howdoyouunderstandstringtheory?
Stringtheoryisamathematicaltheorythattriestoexplaincertainphenomenawhichisnotcurrentlyexplainableunderthestandardmodelofquantumphysics.
Stringtheorywasinitiallydevelopedinthe1970sinanattempttoexplainsomeinconsistencieswiththeenergybehaviorofhadronsandotherfundamentalparticlesofphysics.
Aswithmuchofquantumphysics,themathematicsthatappliestostringtheorycannotbeuniquelysolved.Physicistsmustapplyperturbationtheorytoobtainaseriesofapproximatedsolutions.Suchsolutions,ofcourse,includeassumptionswhichmayormaynotbetrue.
Thedrivinghopebehindthisworkisthatitwillresultina"
theoryofeverything,"
includingasolutiontotheproblemofquantumgravity,toreconcilequantumphysicswithgeneralrelativity,thusreconcilingthefundamentalforcesofphysics.
SectionCPost-readingTask
ReadingComprehension
1.Directions:
Workonyourownandfillintheblankswiththemainidea.
Part1(Paras.1-3):
Briefintroductiontodarkenergy
Para.1:
Darkenergyisanunexplainedforcewhichtugsgalaxiesawayfromeachother.
Para.2:
Darkenergyissomewhatlikeanti-gravity.
Para.3:
Darkenergyisscientists’hypotheticformofenergytoexplaintheuniverse’sexpansion.
Part2(Paras.4-9):
Thediscoveryofdarkenergy:
confoundingexpectations
Para.4:
Thediscoveryofdarkenergyisacaseofscienceconfoundingexpectations.
Para.5:
Expertsexpectedthatgravityhadsloweddowntheuniverse’srateofexpansion.
Para.6:
Theuniverse’srateofexpansionwasspeedingup.
Para.7:
Theresultwasbeyondexperts’expectationswhichcausedmuchnervouslaughter.
Para.8:
Themeasurementsofsupernovaeprovidedtheevidencethattheuniverse’srateofballooningwasspeedingup.
Para.9:
Thescientistsobservedmanysupernovaeatdifferentdistancestodeterminehowfasttheyarespeedingawayfromus.
Part3(Paras.10-13):
Therateoftheexpansionoftheuniverse:
shockingresults
Para.10:
Therateoftheuniverse’sexpansionisaccelerating.
Para.11:
Moreresearchesdonebyotherexpertsalsoshowthesameresults.
Para.12:
Einstein’scosmologicalconstanthasbeenrevivedtoexplainthepuzzlingfindings.
Para.13:
Thecosmologicalconstantisoneoftheleadingtheoriestoexplaintheexpansionoftheuniverse.
Part4(Paras.14-17):
Thedifferencebetweendarkenergyanddarkmatter
Para.14:
Theconfusionofdarkenergyanddarkmatter.
Para.15:
Darkmatterisaninvisiblehypothesizedformofmatter.
Para.16:
Darkmatteranddarkenergyseemtomakeupmostofthemassoftheuniverse.
Para.17:
Thediscoveryofdarkenergystirredupalotofotherissues,suchasmakingsomepeoplebelievethatthereareseveraluniverses.
2.Directions:
1)What’sdarkenergybeforeandafteryoustudiedthetext?
Before,Iknownothingaboutdarkenergy.Now,Iknowthatdarkenergyisahypotheticalformofenergythatpermeatesspaceandexertsanegativepressure,whichwouldhavegravitationaleffectstoaccountforthedifferencesbetweenthetheoreticalandobservationalresultsofgravitationaleffectsonvisiblematter.Darkenergyisnotdirectlyobserved,butratherinferredfromobservationsofgravitationalinteractionsbetweenastronomicalobjects,alongwithdarkmatter.
2)Inyoureyes,what’sgravityandanti-gravity?
Referto:
3)Didgravityslowdowntherateoftheexpansionoftheuniverse?
Whyorwhynot?
No.Gravitywasspeedinguptherateoftheexpansionoftheuniverse.Theevidencewasbasedonmeasurementsofsupernovaethatastronomerswereusingaslamppoststotrackdistance.
4)CanyouexplainDopplerEffectindetail?
TheDopplereffect(orDopplershift),namedafterAustrianphysicistChristianDopplerwhoproposeditin1842inPrague,isthechangeinfrequencyofawaveforanobservermovingrelativetothesourceofthewave.Itiscommonlyheardwhenavehiclesoundingasirenorhornapproaches,passes,andrecedesfromanobserver.Thereceivedfrequencyishigher(comparedtotheemittedfrequency)duringtheapproach,itisidenticalattheinstantofpassingby,anditislowerduringtherecession.
http:
//en.wikipedia.org/wiki/Doppler_effect
5)DoyouknowanystoryofEinstein’scosmologicalconstant?
Inphysicalcosmology,thecosmologicalconstant(usuallydenotedbytheGreekcapitalletterlambda:
Λ)wasproposedbyAlbertEinsteinasamodificationofhisoriginaltheoryofgeneralrelativitytoachieveastationaryuniverse.EinsteinabandonedtheconceptaftertheobservationoftheHubbleredshiftindicatedthattheuniversemightnotbestationary,ashehadbasedhistheoryontheideathattheuniverseisunchanging.However,thediscoveryofcosmicaccelerationinthe1990shasrenewedinterestinacosmologicalconstant.
//en.wikipedia.org/wiki/Cosmological_constant
6)Whatisdarkmatter?
What’sthedifferencebetweendarkenergyanddarkmatter?
Darkmatterismatterthatisundetectablebyitsemittedradiation,butwhosepresencecanbeinferredfromgravitationaleffects.Darkmatterisinvisible.
//en.wikipedia.org/wiki/Dark_Matter_(disambiguation)
7)Isittrueorfalsethattheuniverseisformedmainlyofdarkenergyanddarkmatter?
Canyougivesomeevidence?
Yes.Itistrue.Somestudiesshowthatdarkenergyisthoughttoaccountfor74percentoftheuniverse,whiledarkmatteraddsabout22percent.
8)Areyouoneofthebelieversinmultipleuniverses?
Why?
(Open)
3.Directions:
Readthefollowingpassagecarefullyandfillintheblankswiththewordsyou’velearnedinthetext.
Darkenergy—themysteriousstuffthatisstretchingspaceandspeedingtheexpansionoftheuniverse—issaidtohavebeenaroundatleast9billionyears.Itisahypotheticalformofenergy,whichissomewhatlikeanti-gravitythatdrawsgalaxiesawayfromeachother.Inthemid-1990s,whenastronomerswentaboutmeasuringtherateoftheexpansionoftheuniverse,theysurprisinglyfoundthattheuniverse’sballooningwasspeedingup,whichwasbeyondmanyastrophysicists’expectations.Someotherresearchersalsofoundthattheuniverseisblowingupfastertodaythanatanytimeinthepast.AllthesepuzzlesopenupanopportunityforsomescientiststoreviveEinstein’sdiscardedidea—cosmologicalconstant.Thoughdarkenergyanddarkmatter(invisible)areseparateentities,peoplearealwaysconfusedaboutthem.Itseemsthatdarkenergyaccountsfor74percentoftheuniverse,whiledarkmatteraddsabout22percent.Thedisco
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