Krzysztof Gawędzki, Director of Research Emeritus at the CNRS, assigned to the Physics Laboratory of ENS de Lyon, passed away this Friday, January 21, 2022. This is a huge loss for our entire community. Having lived in Lyon since 2001, Krzysztof played a major role in the development and recognition of Theoretical Physics at ENS de Lyon. His contributions were extremely varied, collaborating with both experimental physicists and mathematicians, on topics ranging from out-of-equilibrium systems and turbulence to quantum field theory and conformal theories. The breadth of his spectrum of activity combined with his insatiable curiosity, benevolence and kindness meant that he played a central role in the activities of Lyon's scientific life in Theoretical Physics and the development of his interactions with Mathematics. His notoriety has contributed to the recognition of ENS de Lyon at both national and international levels in these fields.

Born on July 2, 1947, in Żarki, Poland, Krzysztof Gawędzki obtained his doctorate in 1971 under the supervision of Krzysztof Maurin at the University of Warsaw, which he then joined as a researcher in the Department of Mathematical Methods. During this period, he spent long periods at the University of Göttingen (1975-76), the University of Gdansk (1978-79) and Harvard University (1979-80). Martial law in Poland in 1981 forced him to emigrate. He  then joined the Institut des Hautes Études Scientifiques in France, of which he was a member until 2001. He joined the CNRS in 1982 and became Research Director in 1988. Since 2001, he had been a member of the Physics Laboratory of the École normale supérieure de Lyon, CNRS Research Director emeritus since 2014.  

Early in his career, his research focused primarily on quantum field theory. With Antti Kupiainen, he developed rigorous renormalization group methods for quantum field theory and statistical physics. He also made a major contribution to conformal field theory, more specifically to the Wess-Zumino-Witten-Novikov models. During the 1990s, he became interested in the problem of turbulence. Also with Antti Kupiainen, he described the abnormal scale behavior of the advection of a passive scalar field. In recent years, Krzysztof Gawędzki made outstanding contributions to a wide variety of fields, from Experimental Physics to Mathematics, on topics ranging from entropy production and out-of-equilibrium fluctuation theorems to topological states induced by periodic forcing.

His international influence can be illustrated by the numerous invitations to prestigious institutions that he received, including the Swiss Federal Institute of Technology in Zurich, the Max Planck Institute for Mathematics in the Sciences in Leipzig, Rutgers University, Harvard University and the University for Advanced Study in Princeton.

He was a guest speaker at the International Congress of Mathematics in Berkeley in 1986 and a plenary speaker at the International Congress of Mathematical Physics in Lisbon in 2003. He was the recipient of the 2022 Dannie Heineman Award from the American Physical Society for Mathematical Physics.

Our thoughts are with his family and his colleagues and friends around the world.