3时间旅行

3、TravelinginTimeYoucannotchangethelawsofphysics...butcouldphysicsactuallyenableustotravelthroughtime?Itmightsoundcrazy,butaccordingtoEinsteinstheories,theresnologicalreasonwhytimetravelisntpossible??andtherearenowscientistslookingintoitasaseriousscientificproposal,atleastatatheoretical1level.Manyscience-fictional2ideasfromthepasthavesubsequentlybecamescientificrealities.Takespaceexploration3,forexample.Inthe1950sthiswasjustafantasticalideathatfewpeoplewouldhavedreamtcouldactuallyhappen.Nowitssuchapartofmodernlifethatthelatestblastoff4ofaspacecraft,orthediscoveryofanewplanetoftendoesntevenmakethenationalnews.Timetravelisclearlyatrickier5propositionthanspacetravel,though.AndpriortoEinstein,itwouldhavebeendeemed6utterly7impossible！Thatsbecausetheoldideaabouttimewasthatitwaslikeacosmic8metronome9keepingaregulara