Lizhen Ji Athanase Papadopoulos Sumio Yamada Editors From Riemann to Differential Geometry and Relativity From Riemann to Differential Geometry and Relativity Lizhen Ji Athanase Papadopoulos (cid:129) Sumio Yamada Editors From Riemann to Differential Geometry and Relativity 123 Editors Lizhen Ji Sumio Yamada Department ofMathematics Department ofMathematics University of Michigan Gakushuin University AnnArbor, MI Tokyo USA Japan Athanase Papadopoulos University of Strasbourg, CNRS Institut deRecherche Mathématique Avancée StrasbourgCedex France ISBN978-3-319-60038-3 ISBN978-3-319-60039-0 (eBook) DOI 10.1007/978-3-319-60039-0 LibraryofCongressControlNumber:2017942965 ©SpringerInternationalPublishingAG2017 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of 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 orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerInternationalPublishingAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Preface Bernhard Riemann is one of those few mathematicians whose work made a pro- found transformation of mathematics and physics. Not only his results are far-reaching, but his vision and approach to mathematics were directly felt and appreciated by all the later generations of mathematicians. To say something original on Riemann’s work is not easy, not because every- thing about him is known—far from it, but because it requires a profound reading and understanding of his mathematical writings, which are difficult, involving hidden geometric arguments, sometimes originating in physics and most of all relying on his broad intuitive vision. Besides a familiarity with the mathematical concepts involved, a reader of Riemann’s works must be capable offollowing his verytersestyle.Anyonewhohasreadhishabilitationlecture,ÜberdieHypothesen, welchederGeometriezuGrundeliegen,hasfeltitsunusualtone.Themathematical ideas are expressed there in a broad and unusual language, and the results are generallystatedwithoutsupportingproofsorcalculations.Furthermore,theseideas are intertwined with philosophical and historical considerations, which may be incomprehensibletoa reader who isnotsensible tohistory and philosophy. André WeilmentionsthismemoirinaletterhewrotetohissisteronMarch26,1940,and published in his Collected Papers (Springer Verlag, New York, Vol. 1, p. 244– 255).Hewritesthefollowing,talkingaboutalgebraicfunctionsofonevariable:“It is generally believed that there is nothing left to do on algebraic functions of one variable,becauseRiemann,whodiscoveredalmosteverythingweknowaboutthese functions (I am excepting the works of Poincaré and Klein on uniformization, and thoseofHurwitzandSeverioncorrespondences)didnotleaveforusanystatement of a big problem that concerns them. I am without doubt one of the most knowl- edgeablepersonsonthissubject;certainlybecauseIhadthegoodfortune(in1923) tolearnitdirectlyfromRiemann’swritings,whosememoirisofcourseoneofthe greatest things that a mathematician has ever written; there is not a single word there that is not of consequence.” Today, 150 years after Riemann’s death, some of his highly original ideas are still poorly known to the mathematical community, in spite of the fact that a large numberof books and articles were published on his work. The reason isthat these v vi Preface books often concentrate on the results that are considered to lead to important developments, leaving in the dark some of Riemann’s beautiful ideas that deserve to be contemplated and further exploited. Actualizing these ideas and including them in the context of current mathematics is a permanent necessity. Several essays included in the present volume are the result of reading Riemann’swritings,andtheothersaremotivatedbyhisideasastheyappearinthe scientific literature. The decision of editing this book was taken after two conferences held in Strasbourg, the first one on June 12–14, 2014, whose subject was “Riemann, topology and physics,” and the second one on September 18–20, 2014, whose subject was “Riemann, Einstein and geometry,” where Riemann’s influence on relativitytheorywasemphasized.Consequently,thisbookcontainsseveralchapters on the latter theory. Despite the variety of topics contained in this volume, there is one simple and common purpose, to highlight—hopefully in a new way—some of Riemann’s original ideas and their subsequent development. We would like to take this opportunity to thank Elena Griniari from Springer Verlagforherinterest,supportandefficienthelpinthisedition,andManfredKarbe for his invaluable advice. Editing such a book required hard work. We consider it an expression of our gratitude for all that Riemann gave to human knowledge. His ghostly voice still inspires us all. Ann Arbor, USA Lizhen Ji Strasbourg, France and Providence, USA Athanase Papadopoulos Tokyo, Japan Sumio Yamada April 2017 BernardRiemann(CourtesyofthelibraryoftheUniversityofGötttingen) Riemann'swifeanddaughter(CourtesyofthelibraryoftheUniversityofGötttingen) Contents Preamble . .... .... .... .... ..... .... .... .... .... .... ..... .... 1 Looking Backward: From Euler to Riemann . .... .... ..... .... 1 Athanase Papadopoulos 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 2 2 Functions . .... .... ..... .... .... .... .... .... ..... .... 10 3 Elliptic Integrals.... ..... .... .... .... .... .... ..... .... 20 4 Abelian Functions... ..... .... .... .... .... .... ..... .... 30 5 Hypergeometric Series .... .... .... .... .... .... ..... .... 32 6 The Zeta Function .. ..... .... .... .... .... .... ..... .... 33 7 On Space . .... .... ..... .... .... .... .... .... ..... .... 40 8 Topology . .... .... ..... .... .... .... .... .... ..... .... 46 9 Differential Geometry..... .... .... .... .... .... ..... .... 60 10 Trigonometric Series. ..... .... .... .... .... .... ..... .... 66 11 Integration .... .... ..... .... .... .... .... .... ..... .... 76 12 Conclusion .... .... ..... .... .... .... .... .... ..... .... 78 References. .... .... .... ..... .... .... .... .... .... ..... .... 81 Part I Mathematics and Physics 2 Riemann on Geometry, Physics, and Philosophy—Some Remarks.. .... .... .... ..... .... .... .... .... .... ..... .... 97 Jeremy Gray 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 97 2 The Hypotheses .... ..... .... .... .... .... .... ..... .... 98 3 Influences. .... .... ..... .... .... .... .... .... ..... .... 101 4 Heat Diffusion and the Commentatio . .... .... .... ..... .... 106 References. .... .... .... ..... .... .... .... .... .... ..... .... 108 ix x Contents 3 Some Remarks on “A Contribution to Electrodynamics” by Bernhard Riemann . .... ..... .... .... .... .... .... ..... .... 111 Hubert Goenner 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 111 2 Riemann’s New Result of 1858: The Retarded Potential ... .... 112 3 Gauss, Weber, and Riemann on Electrodynamic Interaction. .... 114 4 Riemann’s Paper.... ..... .... .... .... .... .... ..... .... 117 5 Concluding Remarks ..... .... .... .... .... .... ..... .... 119 References. .... .... .... ..... .... .... .... .... .... ..... .... 122 4 Riemann’s Memoir Über das Verschwinden der #-Functionen........ 125 Christian Houzel 1 Jacobi’s Inversion Problem. .... .... .... .... .... ..... .... 125 2 A Crucial Observation on Theta Functions. .... .... ..... .... 128 3 The First Step of Riemann’s Proof... .... .... .... ..... .... 129 4 The Second Step of Riemann’s Proof. .... .... .... ..... .... 130 5 The Conclusion of the Proof.... .... .... .... .... ..... .... 130 6 Later Developments . ..... .... .... .... .... .... ..... .... 133 References. .... .... .... ..... .... .... .... .... .... ..... .... 133 5 Riemann’s Work on Minimal Surfaces .. .... .... .... ..... .... 135 Sumio Yamada 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 135 2 On the Surface of Least Area with a Given Boundary..... .... 136 3 Representation Formulas by Riemann and Weierstrass-Enneper..... 147 4 Closing Remarks ... ..... .... .... .... .... .... ..... .... 149 References. .... .... .... ..... .... .... .... .... .... ..... .... 150 6 Physics in Riemann’s Mathematical Papers .. .... .... ..... .... 151 Athanase Papadopoulos 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 151 2 Function Theory and Riemann Surfaces... .... .... ..... .... 162 3 Riemann’s Memoir on Trigonometric Series.... .... ..... .... 173 4 Riemann’s Habilitationsvortrag 1854—Space and Matter... .... 181 5 The Commentatio and the Gleichgewicht der Electricität... .... 193 6 Riemann’s Other Papers... .... .... .... .... .... ..... .... 195 7 Conclusion .... .... ..... .... .... .... .... .... ..... .... 199 References. .... .... .... ..... .... .... .... .... .... ..... .... 199 7 Cauchy and Puiseux: Two Precursors of Riemann. .... ..... .... 209 Athanase Papadopoulos 1 Introduction ... .... ..... .... .... .... .... .... ..... .... 209 2 Algebraic Functions and Uniformization... .... .... ..... .... 210 3 Puiseux and Uniformization .... .... .... .... .... ..... .... 212