高中英语新北师大版选择性必修4PPT课件 Unit 10 Section A　TOPIC TALK LESSON 1.pptx

;内容索引;素养导航;;SixDegreesofSeparation

“SixDegreesofSeparation”isthetheorythatanyoneontheplanetcanbeconnectedtoanyotherpersonthroughachainofacquaintances①thathasnomorethanfiveotherpeople.Thetheorywasfirstproposedin1929bytheHungarianwriterFrigyesKarinthyinashortstorycalled“Chains”.?;Inthe1950s,IthieldeSolaPool(MIT)andManfredKochen(IBM)setouttoprovethetheorymathematically.Althoughtheywereabletophrasethequestion(givenasetNofpeople,whatistheprobabilitythateachmemberofNisconnectedtoanothermemberviak1,k2,k3...knlinks?),aftertwentyyearstheywerestillunabletosolvetheproblemtotheirownsatisfaction.In1967,AmericansociologistStanleyMilgramdevised②anewwaytotestthetheory,whichhecalledthe“small-worldproblem”.Herandomly③selectedpeopleinthemid-WesttosendpackagestoastrangerlocatedinMassachusetts.Thesendersknewtherecipient’sname,occupation,andgenerallocation.Theywereinstructedtosendthepackagetoapersontheyknewonafirst-namebasiswhotheythoughtwasmostlikely,outofalltheirfriends,toknowthetargetpersonally.Thatpersonwoulddothesame,andsoon,untilthepackagewaspersonallydeliveredtoitstargetrecipient④.?;Althoughtheparticipantsexpectedthechaintoincludeatleastahundredintermediaries⑤,itonlytook(onaverage)betweenfiveandsevenpeopletogeteachpackagedelivered.Milgram’sfindingswerepublishedinPsychologyTodayandinspiredthephrase“SixDegreesofSeparation”.PlaywrightJohnGuarepopularisedthephrasewhenhechoseitasthetitleforhis1990playofthesamename.AlthoughMilgram’sfindingswerediscountedafteritwasdiscoveredthathebasedhisconclusiononaverysmallnumberofpackages,“SixDegreesofSeparation”becameanacceptednotioninpopcultureafterBrettC.TjadenpublishedacomputergameontheUniversityofVirginia’sWebsitebasedonthe“small-worldproble