NEW YORK UNIVERSITY ARCHIVES A decades atNewYork University (NYU),a joined hisfriend Sarah Courant atthenearby University in Montreal in1945, Nirenberg degree andphysics inmathematics atMcGill tutor. After completing his undergraduate for mathematical puzzles from his Hebrew Montreal, Canada,Nirenberg acquired ataste relativity to biology. lysed large bodiesof research, from general and methodsstrikingly lucid.Hisworks cata- Fellow mathematiciansfoundhisperspectives govern theproperties of unknown functions. renowned formanipulatinginequalitiesthat always compatible withasmoothflow. movement of water from a given initial state are cant askswhethertheequationsgoverning the which Nirenberg’s insightshave beensignifi One famousandstill-unresolved question in to debatesics aboutthenature of numbers. from telecommunications andnuclearphys a vast range of theoretical andappliedsubjects, ematical physics, PDEbecameacentrepiece of Emerging from math eighteenth-century different dimensionsrelate to eachother. tions from studying how theirvariations along what canbeknown aboutmathematicalfunc- differential equations (PDE), which explores and appliedmathematics. above emerging distinctions between pure joyfully nurtured peopleandideas,skating glements andtheirscholarly rewards. He realization of the discipline’s post-war entan- 26 January, aged 94. just abookend to afêted career. Hediedon famous by Mind)was the2001 ABeautiful film 2015 AbelPrize (shared withJohnNash,made systems, from cells to markets. Winningthe maticians understand and study dynamical into hiseighties,andreshaped how mathe continued to make waves until he was well also amongthemost collaborative. Hiswork productive mathematicians,Nirenberg was consummate problem-solver Louis Nirenberg. empires of theoriesandpeople,includingthe patrons,try whounderwrote far-reaching Mathematician whotransformed thestudy of partialdifferential equations. (1925–2020) Louis Nirenberg Obituary Raised inaYiddish-speaking familyin of approximation,A virtuoso Nirenberg was Nirenberg of transformed partial thefield Nirenberg spentanillustrious seven One of theworld’s most cited and their worth to military and indus their worth to military interests. Mathematicianshadshown flourished owing to aconvergence of mathe fter theSecond World War, matics in thematics United States - - - - twentieth-century mathematics, including mathematics, twentieth-century colleagues from around theworld. Hisfirst found inspiration invisitingandhosting mathematicians to be“one bigfamily”, and research on elliptic equations (with appli of Naval Research supported Nirenberg’s budgets from sources includingtheOffice the groundwork for hisinstitute. Expansive duringtheSecond Worldsupport War to lay professor. Cathleen Morawetz, heclimbedtheranks to Americas. Withfellow students Peter Lax and from across Europe, theSoviet Unionandthe tor Kurt Friedrichs aswell asvisitingscholars JamesStokerhis PhDsupervisor andhismen Sciences from 1970 to 1972. heading theCourant Institute of Mathematical He remained there for the rest of his career, a master’s at the university. in mathematics leading mathematician at NYU, Nirenberg did of Sarah’s father-in-law, Richard Courant, a research onatomic weapons. Ontheadvice National Research Council, contributing to 1963, he took inalandmark symposium part on lectures from stars of Courant’s generation. In wrote upresults from histhesisandattended took himto Zurich, Switzerland, where he extended overseas research trip, in 1951–52, . on PureandApplied Mathematics the institute’s own journal,Communications tions, including four his first in 1953, were in modern physics). of One-quarter his publica- for anenormousvariety of approaches in pseudo-differential operators (afoundation cations from fluid and to finance) dynamics © Courant hadcourted federal contracts and Nirenberg trained withawho’s who of Nirenberg considered theworld’s
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A l l r i g h t s r e s e r v e d . - - Nirenberg co-authored papers to anextent strated itsversatile potential to researchers in establishing inequalitiesinPDE.Hedemon referring to a fundamental technique for living off themaximum principle,” hequipped, their most fruitfulgenerality. “Ihave madea oped alifelong forItaly. affinity paper duringhis graduate studies, hedevel a PhDthesisinItalianasthesubject foraterm the Cultural Revolution. After beingassigned cant triptook himto Chinatoward theendof a voyage atsea. Alater geopolitically signifi friendships inanenvironment hecompared to and theUnited States. There, heforged close the relationship between theSoviet Union PDE inNovosibirsk, whichhelpedto redefine [email protected] e-mails: [email protected]; Nirenberg for their research. modern mathematics. Both had interviewed and culture the global history studies of University of Edinburgh, UK, where he is lecturer of science at the in the history she knew Nirenberg. whereInstitute of Mathematical Sciences, programme administrator at the Courant Pennsylvania in Philadelphia and a part-time and Applied Science at the University of senior lecturer in the School of Engineering of twentieth-century mathematics; she is Brit Shields works on the cultural history new ideasincompany. while walking to arestaurant, ashedigested extended dialoguesinfront of ablackboard or 46 doctoral —involved students he supervised Other collaborations —includingwiththe Lax, conducted whileNirenberg was inJapan. work he published with his lifelong colleague took place entirely by post, including theonly collaborationsunusual Some in mathematics. firmament. ognized PDE work from separate parts of the Although he knew Nash, their Abel Prize rec International MathematicalUnionin2010. Prize in 1982 Chern Medal of and the first the andbeyond.in mathematics problems that stretched the limits of research his exceptional insightandtaste asaposer of lems. Yet Nirenberg gained areputation for about hisabilityto formulate originalprob many As a young fields. man, he had worried Nature |Vol 578 | 20 February 2020 |359 Nirenberg was known forusingmethodsin A famouslycongenial collaborator, His career awards Crafoord includedthefirst Michael J. Barany - - - - -