Published on April 23, 2023

The *Medal of the Erwin Schrödinger Institute for Mathematics and Physics* for the year 2023 is awarded to **Isabelle Gallagher**, Professor at the Department of Mathematics and its Applications of the École Normale Supérieure in Paris.

Professor Gallagher is honored for her numerous innovative and highly significant contributions to the mathematical theory of fluid dynamics. With rigorous mathematical analysis she has greatly advanced our understanding of the relationships between microscopic and macroscopic models of fluid. In particular, her work explains how the Boltzmann equation, which gives a statistical description of a gas, emerges from an atomic-level model of the gas as a vast collection of interacting particles moving and colliding according to Newton's laws.

In more recent work, she has shown how smooth solutions of the Boltzmann equation converge to solutions of the Navier-Stokes equations, which give a continuum model of the flow of a fluid. In her work on the Navier-Stokes equations, Professor Gallagher discovered unknown and unexpected examples of global solutions with arbitrarily large initial data. She is also a leading expert on strongly rotating fluids, which are of central importance in the atmospheric and oceanic sciences. Professor Gallagher’s groundbreaking work in mathematics has important implications for physics and advances our understanding of these fundamental equations governing fluid dynamics.

The Award Ceremony will take place on November 9, 2023 at the Erwin Schrödinger Institute for Mathematics and Physics in Vienna.

**Isabelle Gallagher**

Born in 1973 in Cagnes-sur-Mer, Isabelle Gallagher studied at the École Polytechnique from 1992 to 1995 before joining the Université Pierre-et-Marie-Curie, where she obtained a diplôme d'études approfondies (DEA) in 1996 and a doctorate in 1998, working under the supervision of Jean-Yves Chemin on the dynamics of fluids. After that she was Chargée de Recherches of the CNRS at the University of Paris-Sud and the École Polytechnique and habilitated in 2002 at the Université Paris-Sud. From 2004, she was a professor at the Université Paris-Diderot and from 2003 to 2009, she also taught at the École Polytechnique. Since 2017 she is a Professor in Mathematics at the École Normale Supérieure, Paris, where she directed the Department of Mathematics and Applications from 2018 to 2019. Since 2019, she is the director of the Foundation Sciences Mathématiques in Paris.

Isabelle Gallagher has received numerous awards, including the Prix Paul Doistau–Émile Blutet and the Prix Sophie Germain of the French Academy of Sciences and the Silver Medal of the CNRS. In 2014 she was an invited speaker at the International Congress of Mathematicians. From 2012 to 2016 she was a member of the International Scientific Advisory Board of the ESI.

Webpage of Prof. Gallagher: __https://www.math.ens.psl.eu/~gallagher/indexenglish.php__

**The ESI Medal **

The *Medal of the Erwin Schrödinger International Institute for Mathematics and Physics*, or ESI-Medal, awarded in 2020 for the first time, has been created to recognize outstanding achievements in any area of mathematics or physics, including contributions at the interface of the two fields. The previous recipients of the ESI-Medal are Anton Alekseev (2020), Elliott Lieb (2021) and Martin Hairer (2022).

The ESI-Medal is awarded annually and emphasis is generally given to recent achievements not older than ten years. There is no age limitation for the recipient and ordinarily the ESI-Medal is awarded to one person.

The recipient of the ESI-Medal receives a medal, a certificate and a monetary award of 4,000 Euro.

Nominations for the ESI Medal can be made by organizers of current and previous ESI Thematic Programmes, current and former ESI Senior Research Fellows, former members of the Scientific Advisory Board of the ESI, former recipients of the ESI Medal, former Directors of the ESI and the President of the ESI Association. The recipient is selected by the Scientific Advisory Board of the ESI.