Nader Masmoudi was born in Sfax, Tunisia, in 1974. He is a mathematician whose subject is the mathematics of fluids, how they move, when they hold their shape, and when they stop being predictable. Over the last quarter century he has become one of the small number of analysts who can hold the whole of that question in view: the Euler and Navier Stokes equations, boundary layers in the sense of Prandtl, the long time behaviour of shear flows, the passage from microscopic kinetic descriptions to continuum ones. He is a Professor at the Courant Institute of Mathematical Sciences at New York University, and an affiliated faculty member at NYU Abu Dhabi.
Sfax to Moscow
He came out of the Tunisian school system, and by his last year of it was already known. In July 1992 he travelled to Moscow for the International Mathematical Olympiad and won gold, the first African and the first Arab contestant ever to do so. The official record has him at rank 14 in a field of 351 competitors, with a score of 34 out of 42 and full marks on the first four problems. Tunisia and the result remains unmatched in Tunisia.
He has spoken elsewhere about who he read as a schoolboy: This is who I looked
up to while I was young, these were some of my idols.
The figures he names
are al-Khwārizmī and Omar Khayyām. It is worth pausing on the fact that a
Tunisian teenager preparing for the world’s hardest mathematics contest was
reading algebra from the ninth and eleventh centuries as a living inheritance.
Paris
He moved to France for the classes préparatoires at the Lycée Louis-le-Grand. In 1994 he came first in the joint entrance competition of the École Normale Supérieure and the École Polytechnique, and was awarded the Prize of the Republic of Tunisia for academic achievement. His diploma at ENS Paris followed in 1996. He then went to Paris-Dauphine, where he took his doctorate in 1999 under the direction of Pierre-Louis Lions, with a thesis titled Problèmes asymptotiques en mécanique des fluides. His Habilitation à Diriger des Recherches, on fluid mechanics and gas dynamics, was completed at the same university in 2000. From 1998 through 2000 he held a research position at the CNRS in Paris.
Courant
He moved to the Courant Institute after his doctorate. He has been a Professor of Mathematics there since 2008 and has stayed. His office is in Warren Weaver Hall. The work has kept close to a single organising question: when does a flow described by a nonlinear partial differential equation remain close to a simple reference state, and which conditions cause it to depart. The answer is rarely soft. A small perturbation of a shear flow may damp or form structures beyond the reach of linear theory. A boundary layer may stay thin and orderly or separate. He has spent his career making those distinctions rigorous.
The result that many analysts point to first is his 2013 proof, with his then postdoctoral fellow Jacob Bedrossian, of the nonlinear inviscid damping and asymptotic stability of the two dimensional Couette flow for the Euler equations. The problem had been open in a serious sense since Kelvin's linear stability argument of 1887 and Orr's of 1907. Their proof used ideas from Cédric Villani's work on Landau damping in plasma physics, the two subjects turned out to share a structure. He described it plainly in a talk titled The Two Brothers: Landau damping and inviscid damping, given at the 2014 Fields Medal Symposium held in Cédric Villani's honour at the Fields Institute in Toronto. Related joint work addressed the viscous case, and the formation and stability of Prandtl type boundary layers in the two dimensional Navier Stokes equations.
What he works on
- Nonlinear partial differential equations of hydrodynamics: the Euler and Navier Stokes equations, surface, gravity, capillary and acoustic waves, and the qualitative behaviour of boundary layers.
- Boundary layer theory in the Prandtl regime, including well posedness and separation.
- Hydrodynamic stability, in particular the long time behaviour of Couette flow and other shear flows, and the phenomenon of inviscid damping.
- Landau damping and the nonlinear stability of equilibria in kinetic models of plasmas.
- Hydrodynamic limits of the Boltzmann equation, and the passage from compressible to incompressible regimes.
- Nonlinear Schrödinger equations, Ginzburg Landau equations, and the Keller Segel model of chemotaxis.
His long collaborative record includes Pierre-Louis Lions, Jean-Yves Chemin, Laure Saint-Raymond, Pierre Germain, Jalal Shatah, Emmanuel Grenier and Jacob Bedrossian, among others.
How he talks about the subject
He presents mathematics as a shared discipline with broad connections. In a 2019
interview he described stability as a word that we use in our daily life, not
only in math and physics, it applies to social science, politics, or even
relationships. What’s interesting is the kind of questions we ask in math or
physics, you can ask in social sciences, political sciences, or even relationships.
He said much the same about interdisciplinary work: my office is located right
next to a professor of psychology and we often discuss how our fields connect. I am
always open to interdisciplinary application.
On why more young people in the region need to enter research mathematics, he was
direct: It’s true that Arabs usually think about being engineers or doing
this kind of academic research, so research in general is no longer in the habit,
but if we go back to Muslim mathematicians in the past they were in forefront of
the field.
And on why the pure end of mathematics is worth defending on its own terms:
Math is like a language, whereas even today we try to distinguish between pure
math and applied math. Sometimes pure math is being done without any application
in mind, but it turns out that some pure math done from long ago we have only
begun to understand their application now.
He gave the standard example,
nineteenth century number theory becoming the basis for modern cryptography,
and then this: You never know. Something that has no result other than to be
math today can become tomorrow’s solution.
Distinctions
- 1992, Gold Medal, International Mathematical Olympiad, Moscow. First African and first Arab gold medallist.
- 1994, Ranked first in the joint entrance competition of the École Normale Supérieure and the École Polytechnique; Prize of the Republic of Tunisia.
- 2011, Best scientific article, Annales Henri Poincaré.
- 2012, National Science Foundation Fellowship.
- 2017, Fermat Prize, Institut de Mathématiques de Toulouse. Cited by the
jury for
his very deep and creative work
on nonlinear partial differential equations. - 2018, Invited speaker, International Congress of Mathematicians, Rio de Janeiro (Partial Differential Equations).
- 2021, Elected Fellow of the American Academy of Arts and Sciences.
- 2022, King Faisal Prize in Science (Mathematics), awarded jointly with Martin Hairer, for work on Euler and boundary layer equations that reset earlier assumptions about the range of validity of the classical models.
At NYU Abu Dhabi
At NYU Abu Dhabi he founded and leads the Center for Stability, Instability and Turbulence, a research centre within the NYUAD Research Institute where he serves as Principal Investigator. He chairs the Math Olympiad Trainer Academy, which sits inside that centre. That’s the shortest true summary; the longer version of the Academy’s founding logic lives on the About page.
External profiles
Sources
- NYU Abu Dhabi, official announcement, Nader Masmoudi Wins King Faisal Prize in Science (Provost's Office, 2022): confirms the King Faisal Prize (2022), his Courant Institute professorship, his NYUAD affiliated faculty status, and his role as founding Principal Investigator of the SITE research centre within the NYUAD Research Institute. https://nyuad.nyu.edu/en/about/leadership-and-people/office-of-the-provost/communications/nader-masmoudi-wins-king-faisal-prize-in-science.html
- King Faisal Prize, official 2022 laureate biography and press release (Science, Mathematics): confirms shared award with Martin Hairer, the citation on Euler and boundary layer equations, and the biographical details of his education (Lycée Louis-le-Grand entry, ENS/Polytechnique first place, ENS Paris 1996 diploma, Paris-Dauphine PhD 1999 and Habilitation 2000, CNRS 1998 to 2000). https://kingfaisalprize.org/category/science/ and Globe Newswire release, 29 March 2022.
- International Mathematical Olympiad, official individual results database, 1992 (Moscow): confirms his gold medal, rank 14, score 34/42, and full marks on Problems 1 to 4. https://www.imo-official.org/results/individual/year/1992/. Tunisia country page confirms this remains Tunisia's only IMO gold medal. https://www.imo-official.org/countries/TUN/.
- NYU Courant Institute, faculty profile: title (Professor of Mathematics), research interests (nonlinear partial differential equations), and office listing. https://cims.nyu.edu/people/profiles/MASMOUDI_Nader.html.
- NYU Abu Dhabi, faculty profile: NYU New York affiliation, PhD from ENS Paris (Paris-Dauphine 1999), affiliated faculty status at NYUAD, link to SITE. https://nyuad.nyu.edu/en/academics/divisions/science/faculty/nader-masmoudi.html.
- SITE research team page, confirms Courant professorship since 2008, PhD under Pierre-Louis Lions, list of honours including the 1992 IMO gold, the 2011 Annales Henri Poincaré best article prize, the 2012 NSF Fellowship, the 2017 Fermat Prize, and the 2022 King Faisal Prize. https://wp.nyu.edu/stability/team/.
- International Mathematical Union, ICM Plenary & Invited Speakers database: confirms Masmoudi as an Invited Speaker at ICM 2018, Rio de Janeiro, in the Partial Differential Equations section. https://www.mathunion.org/icm-plenary-and-invited-speakers.
- Fields Institute for Research in Mathematical Sciences, official programme for the 2014 Fields Medal Symposium: Cédric Villani: confirms Masmoudi as a speaker at the symposium honouring Villani (Fields Medal 2010), supporting the dating of the Two Brothers talk. http://www.fields.utoronto.ca/activities/workshops/2014-fields-medal-symposium-0.
- Bedrossian, J. and Masmoudi, N., Inviscid damping and the asymptotic stability of planar shear flows in the 2D Euler equations, arXiv:1306.5028 (April 2014): the paper itself, which states in the abstract that “our work appears to be the first rigorous confirmation of this behavior on the nonlinear level,” referencing Kelvin (1887) and Orr (1907). https://arxiv.org/abs/1306.5028.
- NYU Abu Dhabi, research impact profile, Finding a Deeper Meaning in Numbers (2019): source for the direct quotations on stability, interdisciplinary work, mathematical idols (al-Khwārizmī and Khayyām), Arab research habits, and the long view of pure mathematics; also the source for the 1994 Presidential Award of Tunisia phrasing and for the Fermat Prize jury citation. https://nyuad.nyu.edu/en/research/impact/our-research/2019/finding-deeper-meaning-in-numbers.html
- Wikipedia (English), secondary biographical summary: birth year 1974, birthplace Sfax, thesis title, list of principal research areas, collaborators (Bedrossian, Villani, Lions, Chemin, Saint-Raymond, Germain, Shatah, Grenier), and the reference back to Kelvin (1887) and Orr (1907) on linear stability of Couette flow. Verified across sources against the primary sources above. https://en.wikipedia.org/wiki/Nader_Masmoudi.