Schrodinger-What-is-Life

WHATISLIFE?ERWINSCHRODINGERFirstpublished1944Whatislife?ThePhysicalAspectoftheLivingCell.BasedonlecturesdeliveredundertheauspicesoftheDublinInstituteforAdvancedStudiesatTrinityCollege,Dublin,inFebruary1943.TothememoryofMyParentsPrefaceAscientistissupposedtohaveacompleteandthoroughIofknowledge,atfirsthand,ofsomesubjectsand,therefore,isusuallyexpectednottowriteonanytopicofwhichheisnotalife,master.Thisisregardedasamatterofnoblesseoblige.ForthepresentpurposeIbegtorenouncethenoblesse,ifany,andtobethefreedoftheensuingobligation.Myexcuseisasfollows:Wehaveinheritedfromourforefathersthekeenlongingforunified,all-embracingknowledge.Theverynamegiventothehighestinstitutionsoflearningremindsus,thatfromantiquitytoandthroughoutmanycenturiestheuniversalaspecthasbeentheonlyonetobegivenfullcredit.Butthespread,bothinandwidthanddepth,ofthemultifariousbranchesofknowledgebyduringthelasthundredoddyearshasconfronteduswithaqueerdilemma.Wefeelclearlythatweareonlynowbeginningtoacquirereliablematerialforweldingtogetherthesumtotalofallthatisknownintoawhole;but,ontheotherhand,ithasbecomenexttoimpossibleforasinglemindfullytocommandmorethanasmallspecializedportionofit.Icanseenootherescapefromthisdilemma(lestourtruewhoaimbelostforever)thanthatsomeofusshouldventuretoembarkonasynthesisoffactsandtheories,albeitwithsecond-handandincompleteknowledgeofsomeofthem-andattheriskofmakingfoolsofourselves.Somuchformyapology.Thedifficultiesoflanguagearenotnegligible.One'snativespeechisacloselyfittinggarment,andoneneverfeelsquiteateasewhenitisnotimmediatelyavailableandhastobereplacedbyanother.MythanksareduetoDrInkster(TrinityCollege,Dublin),toDrPadraigBrowne(StPatrick'sCollege,Maynooth)and,lastbutnotleast,toMrS.C.Roberts.Theywereputtogreattroubletofitthenewgarmentonmeandtoevengreatertroublebymyoccasionalreluctancetogiveupsome'original'fashionofmyown.Shouldsomeofithavesurvivedthemitigatingtendencyofmyfriends,itistobeputatmydoor,notattheirs.Thehead-linesofthenumeroussectionswereoriginallyintendedtobemarginalsummaries,andthetextofeverychaptershouldbereadincontinuo.E.S.DublinSeptember1944Homolibernulladereminusquamdemortecogitat;etejussapientianonmortissedvitaemeditatioest.SPINOZA'SEthics,PtIV,Prop.67(Thereisnothingoverwhichafreemanponderslessthandeath;hiswisdomis,tomeditatenotondeathbutonlife.)CHAPTER1TheClassicalPhysicist'sApproachtotheSubjectThislittlebookarosefromacourseofpubliclectures,deliveredbyatheoreticalphysicisttoanaudienceofaboutfourhundredwhichdidnotsubstantiallydwindle,thoughwarnedattheoutsetthatthesubject-matterwasadifficultoneandthatthelecturescouldnotbetermedpopular,eventhoughthephysicist’smostdreadedweapon,mathematicaldeduction,wouldhardlybeutilized.Thereasonforthiswasnotthatthesubjectwassimpleenoughtobeexplainedwithoutmathematics,butratherthatitwasmuchtooinvolvedtobefullyaccessibletomathematics.Anotherfeaturewhichatleastinducedasemblanceofpopularitywasthelecturer'sintentiontomakeclearthefundamentalidea,whichhoversbetweenbiologyandphysics,toboththephysicistandthebiologist.Foractually,inspiteofthevarietyoftopicsinvolved,thewholeenterpriseisintendedtoconveyoneideaonly-onesmallcommentonalargeandimportantquestion.Inordernottoloseourway,itmaybeusefultooutlinetheplanverybrieflyinadvance.Thelargeandimportantandverymuchdiscussedquestionis:Howcantheeventsinspaceandtimewhichtakeplacewithinthespatialboundaryofalivingorganismbeaccountedforbyphysicsandchemistry?Thepreliminaryanswerwhichthislittlebookwillendeavortoexpoundandestablishcanbesummarizedasfollows:Theobviousinabilityofpresent-dayphysicsandchemistrytoaccountforsucheventsisnoreasonatallfordoubtingthattheycanbeaccountedforbythosesciences.STATISTICALPHYSICS.THEFUNDAMENTALWDIFFERENCEINSTRUCTUREThatwouldbeaverytrivialremarkifitweremeantonlytostimulatethehopeofachievinginthefuturewhathasnotbeenachievedinthepast.Butthemeaningisverymuchmorepositive,viz.thattheinability,uptothepresentmoment,isamplyaccountedfor.Today,thankstotheingeniousworkofbiologists,mainlyofgeneticists,duringthelastthirtyorfortyyears,enoughisknownabouttheactualmaterialstructureoforganismsandabouttheirfunctioningtostatethat,andtotellpreciselywhypresent-dayphysicsandchemistrycouldnotpossiblyaccountforwhathappensinspaceandtimewithinalivingorganism.Thearrangementsoftheatomsinthemostvitalpartsofanorganismandtheinterplayofthesearrangementsdifferinafundamentalwayfromallthosearrangementsofatomswhichphysicistsandchemistshavehithertomadetheobjectoftheirexperimentalandtheoreticalresearch.YetthedifferencewhichIhavejusttermedfundamentalisofsuchakindthatitmighteasilyappearslighttoanyoneexceptaphysicistwhoisthoroughlyimbuedwiththeknowledgethatthelawsofphysicsandchemistryarestatisticalthroughout.Foritisinrelationtothestatisticalpointofviewthatthestructureofthevitalpartsoflivingorganismsdifferssoentirelyfromthatofanypieceofmatterthatwephysicistsandchemistshaveeverhandledphysicallyinourlaboratoriesormentallyatourwritingdesks.Itiswell-nighunthinkablethatthelawsandregularitiesthusdiscoveredshouldhappentoapplyimmediatelytothebehaviourofsystemswhichdonotexh