Introduction
RudolfJuliusEmanuelClausius(RudolfJuliusEmanuelClausius,January2,1822-August24,1888Japan),aGermanphysicistandmathematician,oneofthemainfoundersofthermodynamics.HerestatedNicolasCarnot'slaw(alsoknownastheCarnotcycle),pushingthermaltheorytoamorerealandsoundbasis.Hismostimportantpaperwaspublishedin1850.Thepaperwasaboutthemechanicsofheat,andforthefirsttimeclearlypointedoutthebasicconceptofthesecondlawofthermodynamics.Healsointroducedtheconceptofentropyin1865.
AcademicAchievements
Hismostimportantpaperwaspublishedin1850.Thispaperisaboutthemechanicsofheat,andforthefirsttimeclearlypointedoutthebasicconceptofthesecondlawofthermodynamics.Healsointroducedtheconceptofentropyin1865.
Mainexperience
BornonJanuary2,1822,inafamilyofintellectualsinKirslin,Prussia(nowKoszalin,Poland).EnteredtheUniversityofBerlinin1840.In1847,hestudiedatHalleUniversitywithaPhDdegreeinmathematicsandphysics.Since1850,hehasservedsuccessivelyasprofessorofphysicsattheBerlinArtilleryEngineeringInstitute,ZurichUniversityofTechnology,WürzburgUniversity,andBonnUniversity.HewaselectedasamemberormemberoftheFrenchAcademyofSciences,theRoyalSocietyofEnglandandthePetersburgAcademyofSciences.)Isfamousforhisthesis"OntheDynamicsofHeatandtheLawsonHeatitselfderivedfromit".In1855,heservedasaprofessorattheZurichUniversityofTechnology,in1867asaprofessorattheUniversityofWürzburgintheGermanEmpire,andasaprofessorattheUniversityofBonnin1869.In1865and1868,hewaselectedasamemberoftheFrenchAcademyofSciencesandthepresidentoftheRoyalSociety.
Biography
ClausiuswasborninXling,Pomerania,andbeganhiseducationathisfather’sschool.Afewyearslater,hewenttoSzczecintostudyattheliberalartshighschool.HegraduatedfromtheUniversityofBerlinin1844.Hestudiedmathematicsandphysicsattheuniversity.AmonghisclassmateswereHeinrichMagnusandJohn·PeterDirichletandJacobSteiner(JakobSteiner),alsostudiedhistorywithRanke.In1847,hecompletedopticalresearchontheEarth’satmosphereandobtainedaPh.D.fromHalleUniversity.Afterthat,hebecameaprofessorofphysicsattheRoyalGermanArtilleryInstituteofTechnologyandanunpaidlecturerattheUniversityofBerlin.From1855to1867,heworkedasaprofessorattheETHZurich,thenmovedtoWürzburg,andthenmovedtoBonnin1869twoyearslater.
In1870,ClausiusorganizedarescueteamintheFranco-PrussianWar.Hewaswoundedandpermanentlydisabledduringthewar,sohewasawardedtheIronCross.
Hiswife,AdelheidRimpham(AdelheidRimpham)diedofadystociain1875,leavinghimalonetoraisesixchildren.Buthecontinuedtoteach,butresearchtimehasbeenlesssincethen.ClausiusdiedinBonn.
Research
InhisPhDthesisonlightrefraction,Clausiusproposedthatweseeblueskyduringtheday,andvariousredskyatsunriseandsunset(andsomeotherPhenomenon)arecausedbytherefractionandreflectionoflight.Later,LordRayleighproposedthatthiswasactuallycausedbythescatteringoflight,butinanycase,Clausius’sresearchmethodwasmuchmoremathematicalthanpreviousrelatedstudies.
Hismostfamousessay"Onthemovementofheatandtheheatlawthatmaybederivedfromit"(ÜberdiebewegendeKraftderWärme)waspublishedin1850,whichinvolvedthemechanicsofheat.Inthispaper,heproposedthatCarnot’slawisinconsistentwiththeconceptofconservationofenergy.Clausiusrestatedthetwolawsofthermodynamicstoovercomethiscontradiction(thethirdlawwasdevelopedbyWalterNernstin1906toPublishedin1912).Thispapermadehisscientificcareertakeoff.
ClausiusimprovedAugustKrönig'sverysimplegasmotionmodelin1857,andintroducedthetranslation,rotationandvibrationmotionofmolecules.Onthefieldmadeacontribution.Inthesamestudy,healsointroducedtheconceptofthemeanfreepathofaparticle.
ClausiusdeducedtheClausius-Clapeyronequationfromthermodynamics.Thisrelationshipisawaytodescribethephasetransitionbetweentwostates,suchassolidandliquid.LeCraberonwaspublishedin1834.
Researchresults
Thermodynamicsresearch
Clausiusismainlyengagedinmolecularphysics,thermodynamics,steamenginetheory,theoreticalmechanics,mathematics,etc.,especiallyHehasmadeoutstandingachievementsinthetheoryofthermodynamicsandthekinetictheoryofgases.Hewasthefirstscientistinhistorytoaccuratelyexpressthelawsofthermodynamics.In1850andRankine(WilliamJohnMa-ZquornRankine,1820～1872)eachindependentlyexpressedtheuniversalrelationshipbetweenheatandmechanicalwork-thefirstlawofthermodynamics,andproposedtheidealthermodynamiccycleofthesteamengine(Rankine-ClauHughesCycle).In1850,Clausiuspublishedapaperentitled"OntheDynamicsofHeatandtheLawsofHeatitself".Heconductedanewresearchontheworkingprocessofheatenginesfromtheviewpointthatheatismovement.ThethesisfirststartsfromthethermalworkequivalentestablishedbyJoule,andsummarizesthelawofconservationofenergyobservedbythermodynamicsasthefirstlawofthermodynamics.Itpointsoutthatpartoftheheatisconsumedintheprocessofheatenginework,andtheotherpartoftheheatistransferredfromthehotbodytothecoldbody..Thereisarelationshipbetweenthesetwopartsofheatandtheworkproduced:.WheredQistheheattransferredtotheobject,dWistheworkdone,andUisanewfunctionintroducedbyClausiusforthefirsttimeinthermodynamics,whichisafunctionofvolumeandtemperature.LaterKelvincalledUtheenergyoftheobject,thatis,theinternalenergyofthethermodynamicsystem.Inthesecondpartofthethesis,onthebasisofCarnot'stheorem,theproblemofenergyconversionandtransferdirectionisstudied,andthemostfamousformofthesecondlawofthermodynamics(Clausius'sformulation)isproposed:heatcannotspontaneouslychangefromcolderTheobjectistransferredtothehotterobject.ThereforeClausiusisoneofthetwomainfoundersofthesecondlawofthermodynamics(theotherisKelvin).
Basedonthediscoveryofthesecondlawofthermodynamics,peopleexpecttofindaphysicalquantitytoestablishauniversalcriteriontojudgethedirectionofthespontaneousprocess.Clausiusfirstfoundsuchaphysicalquantity.In1854,hepublishedthepaper"AnotherFormoftheSecondLawofThermalTheoryofMechanics",whichgavethemathematicalrepresentationofthesecondlawofthermodynamicsintheprocessofreversiblecycles:andintroducedanewonelaternamedentropyStateparameters.In1865,hepublishedapaperentitled"TheApplicableFormsoftheMainEquationsoftheThermalTheoryofMechanics",andofficiallynamedthisnewstateparameterentropy.Theaboveintegralisextendedtoamoregeneralcyclicprocess,andthemathematicalrepresentationofthesecondlawofthermodynamicsisobtained:≤0equalsigncorrespondstoareversibleprocess,andinequalitysigncorrespondstoanirreversibleprocess.ThisisthefamousClausiusinequality.Usingthenewfunctionofentropy,Clausiusprovedthatinanyisolatedsystem,thesumoftheentropyofthesystemwillneverdecrease,orthespontaneousprocessinnatureisgoinginthedirectionofincreasingentropy.Thisisthe"entropyincreaseprinciple",whichisthesecondlawofthermodynamicsexpressedbytheconceptofentropy.Later,Clausiusinappropriatelyextendedthesecondlawofthermodynamicstotheentireuniverse,andproposedtheso-called"heatdeaththeory."
ResearchontheKineticTheoryofGas
Clausiushasmadeoutstandingcontributionstothekinetictheoryofgases.Clausius,Maxwell,andBoltzmannareknownasthethreemainfoundersofthekinetictheoryofgases.Becauseoftheirseriesofwork,thekinetictheoryofgasesfinallybecameaquantitativesystemtheory.In1857,Clausiuspublishedhisthesis"OntheFormsofThermalMotion",whichdevelopedthebasicideasofthekinetictheoryofgasesinaveryclearway.Heassumedthatthemoleculesinthegasmovedrandomlyinalldirectionsatthesamespeed,andthecollisionofthegasmoleculeswiththevesselwallproducedthepressureofthegas.Forthefirsttime,hededucedthewell-knownidealgaspressureformula,andthusprovedtheBoYiEar-Marriott'slawandGuyLussac'slawinitiallyshowedtheachievementsofthekinetictheoryofgases.Andforthefirsttime,thestatisticalconceptinphysicswasclearlyputforward.Thisnewconceptplayedapioneeringroleinthedevelopmentofstatisticalmechanics.
In1858,hepublishedthepaper"OntheMeanFreePathofGasMolecules",whichstartedwiththeanalysisofthecollisionsbetweengasmolecules,andintroducedimportantconceptsofthenumberofcollisionsperunittimeandthemeanfreepathofgasmolecules.Itsolvesthecontradictionbetweenthehighspeedofgasmoleculesandtheslowpropagationspeedofgasdiffusionbasedontheoreticalcalculations,andopensthewayforstudyingthetransportprocessofgas.
Theoryofthermodynamics
Thefounderofthetheoryofthermodynamics,Clausius,hasstudiedextensivelythroughouthislife,buthismostfamousachievementisthatheputforwardthesecondlawofthermodynamicsandbecameoneofthefoundersofthetheoryofthermodynamics..Thedevelopmentofhumanscienceinthe19thcentury,theapplicationofsteamengineshasbeenveryextensive,andhowtofurtherimprovetheefficiencyofheatengineshasattractedmoreandmoreattentionandhasbecomeakeysubjectoftheoreticalphysicsresearch.In1824,CarnotprovedthelaterfamousCarnottheoremonthebasisofthermalmasstheoryandtheimpossibilityofperpetualmotionmachines.Thisnotonlydeducedtheupperlimitofheatengineefficiency,butalsocontainedseveralcontentsofthesecondlawofthermodynamics.Sincethen,afterlong-termresearchbymanyscientists,bythemid-19thcentury,thelawofenergyconversionandconservationwasestablished.Thisextremelyimportantuniversallawinphysicssoonbecameasolidfoundationforstudyingthemutualtransformationofheatandotherformsofmotion..
Clausiushasdecidedtoconducttheoreticalresearchonheatsincehisyouth.Hebelievesthatoncethereisatheoreticalbreakthrough,theproblemofimprovingtheefficiencyofheatenginescanbesolved.Withacleargoal,Clausiusisextremelydiligentinstudying.Heknowsthatonlybylayingasolidfoundationinmathematicsandphysicsatthestudentstagecanhemakeachievementsinthefutureresearchroad.Therefore,Clausiusspentnearly10yearsstudyinghardinschool.Ifthereisawill,itwillcometrue.In1850,Clausiuspublishedthefirstthesisonthetheoryofheat-"OntheDynamicsofHeatandtheLawsConcerningHeatitself."Inthethesis,hefirstbasedonthethermalpowerequivalentestablishedbyJoule'sexperimentalmethodatthattime,andforthefirsttimeclearlyproposedthefirstlawofthermodynamics:inallcaseswhereworkisproducedbyheat,theremustbeasumoftheresultingworksuccess.Proportionalcaloriesareconsumed;conversely,consumingthesameamountofworkwillproducethesameamountofheat.Accordingtothisbasiclaw,Clausiustooktheidealgasasanexampletofurtherdiscuss,denyingthebasicpremiseofthethermalmasstheory,thatis,theconservationofheatintheuniverse,andtheheatinsidematterisacontributiontothemotiontheoryofgasmolecules
Asthefounderofthetheoryofthermodynamics,Clausius’achievementsinhislifearemuchmorethanthat.Hehasmaderemarkableresearchresultsinmanyaspects,especiallyinthetheoryofgasmolecules.PeoplearealsousedtoSexuallycalledhim,MaxwellandBoltzmann,thefounderofthetheoryofmolecularkinetics.
Gasmoleculetheory
Asearlyasthe18thcentury,scientistsdiscoveredthatgasiscomposedofalargenumberofviolentlymovingparticles,andthepressureofthegascomesfromthecollisionoftheparticlesagainstthewall.Inthe1850s,Clausiusandothersestablishedthetheoryofthermodynamicsandusedthetheoryofthermalmotionasthebasisformolecularmotionresearch,whichgreatlypromotedthedevelopmentofthetheoryofmolecularmotion.In1857,Clausiuspublishedagroundbreakingpaper"OntheKindofMovementWeCallHeat".Thepaperwasrichincontentandexpoundedonanumberofissuesrelatedtomolecularmotion.Fromtheviewpointthatgasisacollectionofmovingmolecules,Clausiusbelievesthatitisimpossibleandmeaninglesstoexaminethemovementofasinglemolecule.Themacroscopicpropertiesofthesystemdonotdependonthemovementofoneorsomemolecules,butonalargenumberofmolecules.Theaveragevalueofthemovement.Therefore,heproposedtheconceptofstatisticalaverage,whichisthepremiseofestablishingthetheoryofmolecularkinetics.Basedonthispremise,Clausiusestablishedamodelofthemotionofidealgasmoleculesandemphasizedthatthekineticenergyofmoleculesisnotonlytheirlinearmotion,butalsotherotationandoscillationofatomsinthemolecule,thuscorrectlydeterminingtheactualgasandidealgas.thedifference.Onthisbasis,Clausiuscalculatedthenumberofmoleculesinthewallofthecolliderandthecorrespondingchangesinthemomentumofthemolecules,andthroughaseriesofcomplexcalculationsanddemonstrations,finallyobtainedtheformulaforthepressureappliedtothewallduetothecollisionofmolecules.,Thusrevealingthemicroscopicnatureofthegaslaw.Notonlythat,Clausiusalsosethissightsonthesolidandliquidgas.Heconcludedthatthemoleculesinthethreeaggregatestatesareallmoving,butthewaytheymoveisdifferent.
Inapaperin1857,Clausiuscalculatedforthefirsttimethevelocitiesofoxygen,nitrogen,andhydrogenmoleculesatfreezingpoint.However,thisconclusionthatgasmoleculesmoveataspeedofhundredsofmeterspersecondisfarbeyondpeople’sexpectations,becauseinreallife,theprocessofgasdiffusion(suchasthediffusionofsmoke)isquiteslow,sopeopleareconcernedaboutClausiusSi'sresearchresultsexpressedgreatsuspicion.Howcanweexplainthecontradictionbetweenthespeedofmolecularmotioncalculatedbasedonthetheoryandthespeedshownbythegasdiffusionphenomenon?Clausiusfellintoanewconfusion.Herealizedthathispreviousmodelofthinkingofmoleculesasmathematicalgeometricpointswasnotaccurateenoughandmustberevised.Hestartedbyanalyzingthecollisionsbetweengasmolecules,takingtherangeofactionofmoleculesashismainconcept,andintroducingtwoconcepts:thenumberofcollisionsperunittimeandthefreepathofmolecularmotion,andcameupwiththefirstTheformulaforthefreepathofeachindividual.Throughthesebrand-newresearchmethods,Clausiusbelievesthatalthoughthespeedofindividualmoleculesisveryfast,thetrajectoryofmolecularmotionisverytortuousduetothemutualcollisionsbetweenmolecules.Asfarastheentiremolecularassemblyisconcerned,thewayforwardisItisevenlonger,farlessthantheresultofthespeedofmolecularmotion,whichisthereasonfortheslowgasdiffusion.Clausiusgroundbreakinglysolvedthecontradictionbetweenthegasdiffusionspeedbeinglessthanthemolecularmotionspeed,andfinallydispelledpeople'sdoubts,makingthemfullofconfidenceinthetheoryofmolecularmotion,andopenedthewaytostudythephenomenonofgasmotion.
EntropyTheory
Inthepaper"AbhandlungenüberdiemechanischeWärmetheorie,ZweiteAbteilung"publishedin1867,Clausiusprovidedamathematicalversionoftheconceptofentropyforthefirsttime,andprovideditwithFornaming,heusedthenowdeprecatedentropyunit"Clausius"(symbolisCl).
1Cl=1cal/°C=4.1868J/K
Othercontributions
Clausiusalsocontributedalotinotherareas.HetheoreticallydemonstratedtheJoule-Lenzlaw.In1851,theClapeyronequationwasdemonstratedfromthetheoryofthermodynamics,sothisequationisalsocalledtheClapeyron-Clausiusequation.In1853hedevelopedthethermodynamictheoryofthermoelectricphenomena.In1857heproposedtheelectrolysistheory.In1870,hefoundedoneoftheimportanttheoremsinstatisticalphysics-thetheoremofvigor.In1879,heproposedthetheoryofdielectricpolarization,fromwhichheandO.Mosottiindependentlyderivedtherelationshipbetweenthedielectricconstantofthedielectricanditspolarizability-theClausius-Mosottiformula.
Themainworksinclude"ThermalTheoryofMechanics","PotentialFunctionandPotential",
Honors
AcademicHonors
1868HewaselectedasamemberoftheRoyalSocietyin1879andwontheCopleyMedalin1879.In1870,hewontheHuygensPrize.In1883,hewonthePenselleAward.In1882,hewasawardedanhonorarydoctoratebytheUniversityofWürzburg.TheClausiuscrateronthemoonisnamedafterhim.
Inscribedhonor
PeopleinthenaturalsciencesandphilosophywillalwaysrememberthetwofamouswordsusedbyClausiusin1865:
"Theenergyoftheuniverseisconstant".
"Theentropyoftheuniversetendstoamaximum".
Thesubjectextensionofentropy
Theoryofheatdeath
Boltzmannentropy
Negativeentropy
Informationentropy