The Complex Itinerary of Leibniz’s Planetary Theory: Physical Convictions, Metaphysical Principles and Keplerian Inspiration PDF
Preview The Complex Itinerary of Leibniz’s Planetary Theory: Physical Convictions, Metaphysical Principles and Keplerian Inspiration
Science Networks Historical Studies 52 Paolo Bussotti The Complex Itinerary of Leibniz’s Planetary Theory Physical Convictions, Metaphysical Principles and Keplerian Inspiration Science Networks. Historical Studies Science Networks. Historical Studies Founded by Erwin Hiebert and Hans Wußing Volume 52 Edited by Eberhard Knobloch, Helge Kragh and Volker Remmert Editorial Board: K. Andersen, Amsterdam S. Hildebrandt, Bonn H.J.M. Bos, Amsterdam D. Kormos Buchwald, Pasadena U. Bottazzini, Roma Ch. Meinel, Regensburg J.Z. Buchwald, Pasadena J. Peiffer, Paris K. Chemla, Paris W. Purkert, Bonn S.S. Demidov, Moskva D. Rowe, Mainz M. Folkerts, Mu¨nchen Ch. Sasaki, Tokyo P. Galison, Cambridge, Mass. R.H. Stuewer, Minneapolis J. Gray, Milton Keynes V.P. Vizgin, Moskva R. Halleux, Lie´ge More information about this series at: http://www.springer.com/series/4883 Paolo Bussotti The Complex Itinerary of ’ Leibniz s Planetary Theory Physical Convictions, Metaphysical Principles and Keplerian Inspiration PaoloBussotti UniversityofUdine Udine Italy ISSN1421-6329 ISSN2296-6080 (electronic) ScienceNetworks.HistoricalStudies ISBN978-3-319-21235-7 ISBN978-3-319-21236-4 (eBook) DOI10.1007/978-3-319-21236-4 LibraryofCongressControlNumber:2015951719 SpringerChamHeidelbergNewYorkDordrechtLondon ©SpringerInternationalPublishingSwitzerland2015 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilarmethodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. Thepublisher,theauthorsandtheeditorsaresafetoassumethattheadviceandinformationinthis book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained hereinorforanyerrorsoromissionsthatmayhavebeenmade. Coverillustration:FromWallerMsde-00215,AugustBeer:U¨berdieCorrectiondesCosinusgesetzesbei derAnwendungdesNicol’schenPrismasinderPhotometrie,after1850.Withfriendlypermissionby TheWallerManuscriptCollection(partoftheUppsalaUniversityLibraryCollections). Printedonacid-freepaper Springer International Publishing AG Switzerland is part of Springer Science+Business Media (www.birkhauser-science.com) Foreword Authors like the late Eric Aiton, Domenico Bertoloni Meli, Franc¸ois Duchesneau, Alexandre Koyre´ and many others have diligently studied, explained or criticized Leibniz’splanetarytheory.Leibniz,itistrue,changedhisrelativeopinionsinmany respectsinthecourseoftime.Buthealwaysadheredtosomefundamentalconvic- tions, among them being the strong assertion that all hypotheses must be based on mechanicalmodels.Thisisespeciallytrueofhisdifferentexplanationsofgravitythat are closely connected with his cosmological considerations. He thus inevitably refused Newton’s celestical mechanics because it was based on the unexplained notionofgravity. PaoloBussottimakesanew,comprehensiveefforttointerpretLeibniz’sdiffer- enttrialstodevelopaconsistentplanetarytheorywellknowingthat“itisdifficultto offeracoherentpictureofLeibniz’stheoryofmotion”.Yet,herightlyemphasizes that Leibniz aimed at a physical-structural theory, not only at a kinematical or dynamicaltheoryinordertounderstandtheworldsystem. Bussotti presents a subtle analysis of Leibniz’s thinking and argumentation. Leibniz’s natural inertia is not Newton’s inertia. Leibniz had no inertia concept thatwascomparabletothatofNewton.Hetriedtoreplaceitbymeansofhisforces. Leibniz’smainphysicalquantitywasspeed,notacceleration.Whenheelaborated histheoryofaharmoniccirculationandaparacentricmotionasbasicingredientsof hisplanetarytheory,hediditwithregardtoNewton’sPrincipiamathematica.He wantedtoofferaphysicalalternativetoNewton’sphysics. What is more, Bussotti’s aim is to explain the internal change of Leibniz’s concept of gravity. Leibniz finally came to the conclusion that gravity originates fromthecirculationoftheether.Yet,theoriginofgravitywasnotcertainforhim. Hecontinuedtowriteonituptotheendofhislife.HeattributedtoKeplertheidea that gravity is due tothe centrifugalforce ofthe fluid.It is worth mentioning that suchafluidisareminiscenceofPtolemy’scosmology. ThereforeBussottijustlyconcludesthatafullunderstandingofLeibniz’splan- etary theory is not possible without an understanding of its connection with Leibniz’sgeneral,physical,andmetaphysicalprinciples. v vi Foreword InmyeyesBussotti’slastchapterisespeciallyimportantandoriginal.Itanalyses Kepler’s influence on Leibniz’s scientific thinking and planetary theory. Influence doesnotnecessarilymeanagreement,thoughLeibnizhimselfconsideredhimselfas somebody who continued Kepler’s work. For example Leibniz did not accept Kepler’splanetarysoulsormagneticinfluences.Forhimeventheorbitoftheplanets mightbenotanellipse. BussottidemonstratesthatLeibnizfalselyascribedtheinsighttoKeplerthatina curvilinearmotionabodytendstoescapealongthetangent.ButLeibnizobviously tooktheideaoftheparacentricmotion,aswellasthatofadecompositionofplanetary motions,intotwocomponentsfromKepler.Ontheotherhand,hewasnotinfluenced by his countryman when he conceived of the circulatio harmonica. Both scientists sharedtheconvictionthatharmonydeterminesthestructureoftheuniverse. In spite of many differences between the two thinkers, Bussotti emphasizes the similarity between their ways of thinking, of approaching the problems, and of conceiving of the universe and of its relation with God. Bussotti teaches the reader to see Leibniz’s metaphysics under a new perspective, to see Leibniz as a modern Keplerian.KeplerandLeibnizsharedindeedacommonvisionoftheuniversethatwas basedonharmony,finalcauses,andonaconceptionoftheworldasatruekosmos. Berlin,Germany EberhardKnobloch June2015 Preface ThegenesisofthisbookbeginswithanAlexandervonHumboldtfellowshipthatIhad achievedintheperiod2003–2005atLudwigMaximiliansUniversity,Munichthough inthoseyearsIdidnotfocusonLeibniz.SomeyearslaterIextendedtheprivilegeof thisFellowshipduringathreemonthperiodfromDecember2013toFebruary2014at theBerlin-BrandenburgAcademyofScience,Berlin.Thehostofmyfellowshipwas ProfessorDr.EberhardKnobloch.Intheprevioussixmonths,Ihadfrequente-mail contactswithProfessorKnoblochandwesharedtheideathat,duringthistimeperiod inBerlin,IwouldfocusmystudiesontheinfluenceexertedbyKepleronLeibniz’s planetarytheory.Therefore,Ibeganmyresearchwiththisclearintention.However, myreading ofLeibniz’s works and the existing literatureonthe subject,aswell as discussions with ProfessorKnobloch, convinced me to extend my research beyond thisnarrowintention.Thus,myaimwaswidenedtoframeLeibniz’splanetarytheory insidehisphysicsandmetaphysics.Inparticular,Iwonderedifplanetarytheorywas, forLeibniz,somethinglikeanacademicexerciseor,inanycase,asecondarypartof hisgeneralorderofideas,scarcelyconnectedwiththewholeofhisproductionorif,in contrast,itplayedanimportantroleinthedevelopmentofhisentirewayofthinking. Myattemptstoanswersuchquestionsarethecoreofthisbook,insidewhich,without enteringintodetails,whichthereaderwillcontrolintherunningtext,itispossibleto recognizethreemainconceptualcentres: 1) Description and specification of the details (in particular mathematical and physical details) of Leibniz’s planetary theory, also considering its historical evolution.TheChaps.2and4arededicatedtothisproblem; 2) Connection between Leibniz’s gravity theory—perhaps better to speak of Leibniz’sideasongravityratherthanatheoryinapropersense—andplanetary theory.ThisisthesubjectofChap.5; 3) Kepler’s influence on Leibniz. This was my original project. It is developed in Chap. 6, where I show the influence exerted by Kepler on Leibniz’s planetary theory, but where I try to extend the argumentation, as I attempt to prove that vii viii Preface Kepler was also influential on Leibniz’s metaphysics, in particular as far as the conceptofpre-establishedharmonyisconcerned. Chapter1isahistoricalandconceptualintroductiontothescenariodescribedin the book, while Chap. 3 has to be interpreted as a brief parenthesis concerning the conceptofinertiainLeibniz,especiallyfocusingontheaspectsconnectedtoplane- tarytheory.Tobeclear,myintentionhasnotbeentodealwiththecomplexgeneral problemsofLeibniz’sphysics,onwhichahugeandprofoundliteratureexists. As to the quotations, in the running text I have always offered the English translation from original works or letters, which are almost exclusively written in twolanguages:Latin(inmostcases)andFrench(inseveralcases).Ifnotexplicitly specifiedotherwise,thetranslationismine. IwishtoexpressmyparticulargratitudetoProfessorDr.EberhardKnobloch.He followed my research in Germany and he read the whole of my work, giving me preciousadvice.Finally,hecontacted thepublishing houseBirkha¨usertopropose the publication of this book. Without his collaboration and precious help, this researchwouldhavebeenneitherwrittennorpublished. IamalsogratefultoProfessorDaniloCapecchiforhisqualified,numerousand profoundtips,astothecontentandformofmywork. I am indebted with Dr. Raffaele Pisano, with whom I have published several worksandwhoalsogavemevaluablehelp. I wish to thank Professor Niccolo` Guicciardini for an important observation concerningChap.4andDr.StefanoGatteiforsomeadviceregardingChap.2. Itisobviousthatpossiblemistakesorimperfectionsrestentirelyupontheauthor. I wish to express my gratitude to the Alexander von Humboldt Foundation for havingfinancedmyresearch-periodinBerlin. IamgratefultotheBirkha¨userPublishingHouseforhavingacceptedmybook forpublication. Udine,Italy PaoloBussotti Contents 1 AnIntroduction:TheHistorical-ConceptualReferenceFrame. . . . 1 2 DescriptionoftheMostImportantElementsofLeibniz’s PlanetaryTheory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 PhysicalPresuppositions,theCirculatioharmonica andtheMotusparacentricus. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1 Leibniz’sAssertions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.2 Commentaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2 TheMotusParacentricusandItsProperties. . . . . . . . . . . . . . . . . 13 2.2.1 Leibniz’sAssertions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.2 Commentaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3 EllipticalMotionandInverseSquareLaw. . . . . . . . . . . . . . . . . . 22 2.3.1 Leibniz’sAssertions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.3.2 Commentaries:TwoDifferentModelsforPlanetary Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2.4 TheFinalDescriptionoftheSolarSystemintheTentamen. . . . . 29 2.4.1 Leibniz’sAssertions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.4.2 Commentaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3 AnInterlude:Leibniz’sConceptofInertia. . . . . . . . . . . . . . . . . . . . 31 3.1 LeibnizandNaturalInertia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2 Leibniz:NewtonianInertiaandConatetoRecedeAlong theTangent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 4 TheFinalVersionofLeibniz’sPlanetaryTheory. . . . . . . . . . . . . . . 45 4.1 ANewModelfortheconatusexcussorius. . . . . . . . . . . . . . . . . . 46 4.1.1 CircularPathandFallingBodies:Leibniz’sAssertions. . . 46 4.1.2 CircularPathandFallingBodies:Commentaries. . . . . . . . 49 4.1.3 TheNewModelfortheconatusexcussorius:Leibniz’s Assertions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.1.4 TheNewModelfortheconatusexcussorius: Commentaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 ix
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