精密测量，扭秤特性，周期拟合
measurementofgravitationalcotantgandresearch
ontorsionpendulumproperties
anaccurateknowledgegisnotonlyimportantfromthepointofviewoftheoreticalphysics,butalsosignificantforpracticalpurposes,particularlywhenfindingthedeityanddeitydistributiooftheinteriorsoftheearth,moon,planetsandstars.furthermore,apreciseknowledgeofgisofcoiderablemetrologicalinterest,anditprovidesauniqueaswellasavaluablemeasurementchallengethatsharpeandpreparesexperimentalskilltobetterdealwithavarietyofpreciseandnullexperiments.forthosereaso,greateffortshavebeenmadeovertwocenturiestoobtainareliablevalue.sincecavendishreportedthefirstexperimentvalueofg,nearly300differentmeasurementsofghavebeenmadeovertheye
ars,includingseveralinwhichtheobjectivewastosearchforsometypeofvariationing.initeofthesemanystrenuousefforts,gistheleastpreciselydeterminedofallthefundamentalcotantsofnature.thedifficultiesindetermininggarewellknown:thegravitationalforceisextremelyweakandisubiquitouthegravitationalforcecaotbeshieldedintheexperiment;theaolutemeasurementsincreasethedifficulties,gisdefinedbythreefundamentalquantities—time,lengthandma.basedontherecentmeasurements,in1999,thecommitteeondataforscienceandtechnology(codata)gaveanewrecommendedvalueforg,i.e.codata-98.itisnotedthatthenewrecommendedcodata-98valueforgiseentiallythesameasthecodata-86valuebuttherelativeuncertaintyplacedonthisvaluehasbeenexpandedto1500m.thissituation,withadisagreementfarinexceoftheestimate,suggeststhepresenceofunknownsystemat
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