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1、PhysicsandthecommunicationsindustryW.F.BrinkmanandD.V.LangBellLaboratories,LucentTechnologies,MurrayHill,NewJersey07974Thisreviewexplorestherelationshipbetweenphysicsandcommunicationsoverthepast125years.Theauthors®ndthatfourerasofmajorchangeincommunicati
2、onstechnologycanbetracedtothecorrespondingmajordiscoveriesofphysicsthatdirectlyin¯uencedthecommunicationsindustry.Thefourareasofphysicsthatde®netheseperiodsareelectromagnetism,theelectron,quantummechanics,andquantumoptics.[S0034-6861(99)02602-1]I.INTRODU
3、CTIONcanidentifyfourbroaderasofphysicsthathaveim-pactedcommunications:(1)theeraofelectromagnetismToday'scommunicationsindustryisaleadingforcein(startingin1820);(2)theeraoftheelectron(startingintheworld'seconomy.Ourliveswouldbevastlydifferent1897);(3)thee
4、raofquantummechanics(startinginthewithoutthetelephone,fax,cell-phone,andtheInternet.1920s);and(4)theeraofquantumoptics(startinginThecommonplaceandubiquitousnatureofthistechnol-1958).ogy,whichhasbeenevolvingoveraperiodof1251years,tendstoovershadowthedomin
5、antrolethat2physicsandphysicistshaveplayedinitsdevelopment.ThepurposeofthisreviewistoexplorethiscouplingII.THEERAOFELECTROMAGNETISMandtoshowthatthecommunicationsindustryhasnotonlymadeuseoftheresultsofacademicphysicsre-Thiseradatesfrom1820,whenOersteddisc
6、overedsearchbuthasalsocontributedsigni®cantlytoourthatanelectriccurrentgeneratesamagnetic®eld.Thepresentunderstandingoffundamentalphysics.Dueto®rstelectromagnetwasbuiltin1825,andin1831Fara-limitationsofspace,weshallprimarilyuseexamplesdayandHenryindepend
7、entlydiscoveredthatelectriccurrentscanbeinducedinwiresmovinginamagneticfromtheBellSystemandBellLaboratories.®eld.TheconceptoftheelectromagnetwasexploitedinThefoundationsofcommunicationstechnologylayintwoindependentlyinventedtelegraphsystemsinthediscoveri
8、esofthegreatphysicistsoftheearly19th1837ÐananalogsystembyCookeandWheatstoneincentury:Oersted,Ampere,Faraday,andHenry.TheBritainandadigitalsystembySamuelMorseinthetelegraphwasinventedonlyseventeenyearsaftertheU.S.,usingadot
