英语说明文阅读理解例题讲解
文章体裁：说明文字数统计：347主题：主要介绍了原子钟和正在研发中的核钟（nuclearclock）的技术特点、工作原理以及潜在的应用前景。
①Fortheprecisetimekeeper,onlyanatomicclockwilldo.Whilethebestquartz(石英)timepieceswillloseamillisecondeverysixweeks,anatomicclockmightnotloseathousandthofoneinadecade.SuchdevicesareaccurateenoughtodriveeverythingfromGPSandtheinternettostock-markettrading.However,researchersarenowworkingonasuccessor:thenuclearclock.EkkehardPeik,apioneerinthefield,sayssuchaclockcouldbe1,000timesmoreaccuratethantoday’satomicclocks.②Atomicclocksworkbyexcitingtheelectronsaroundanatom’snucleus(原子核)withincomingradiationofaspecificfrequency,witheachwavecyclecorrespondingtoa“tick.”Nuclearclockswouldfunctionsimilarlybutwouldusethetransitionsofneutronsandprotons(中子和质子)insidethenucleus.
③Themostpromisingcandidatenucleusisthorium-229,whichuniquely,hasanucleartransitionthatlasers(激光)shouldbeabletoactivate.Theexactfrequencyatwhichthisoccurs,however,haslongbeenunknown.ResearchersChuankunZhangandJunYe,fromtheUniversityofColoradoinBoulder,bypassedthischallengebydevelopingacustom-builtlasercapableofgeneratingarangeoffrequenciesaroundtheexpectedtransitionpoint.Whentheyfireditatthetarget,oneparticularlightstreammatchedthenucleartransitionfrequency.Althoughthesystemneedsoptimization,Zhangsays,“It’sthefirstdemonstrationthatallthecomponentsofanuclearclockarehere.”
④Becauseatomicclocksarealreadymorethanaccurateenoughformostpracticaluses,scientistsarenotaimingtoreplacethem.Instead,theyaremoreinterestedintheadvantagesofhavingtwoindependentmethodsformeasuringtime,asbeyondprecisetimekeeping,nuclearclockscouldhavebroaderapplicationsinfundamentalphysics.OnepotentialuseisintestingEinstein’stheoryofrelativity,whichsuggests,amongotherthings,that
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