4 December 2025

9:00 AM – 9:45 AM

Amphi Petit Kursaal

Jean-Philippe Uzan

Jean-Philippe Uzan is a research director in theoretical physics at the CNRS. A specialist in gravitation and cosmology, he works at the Paris Astrophysics Institute. He was deputy director of the Institut Henri Poincaré from 2013 to 2017. He has published more than 160 research articles on many aspects of cosmology, from the most theoretical to the interpretation of the most recent observations. He received the Paul Langevin Prize (2010), the prestigious Georges Lemaître Prize (2015), and the Jules Janssen Prize (2025). He taught for several years at the École Normale Supérieure in Paris and the École des Mines de Paris, as well as at international thematic schools. He has been collaborating for fifteen years with the University of Cape Town in South Africa and has been an affiliate professor at Kyoto University since 2023. His latest works include L’harmonie secrète de l’univers (The Secret Harmony of the Universe) (2017), Big-bang en (2018), L’importance des constantes (The Importance of Constants) (2020), L’appel de l’univers (The Call of the Universe) (2024), and Une histoire populaire de l’univers (A Popular History of the Universe) (2025). He also explores the porosity between arts and science with composer Fabien Waksman and director Etienne Pommeret.

Has the cosmological model reached its limits?

After a century of development, the standard model of cosmology allows us to account for all astronomical observations and describe the structure of the universe. However, it shows several signs of its limitations, first of all explanatory limitations (in particular with its initial singularity popularly known as the Big Bang), then questions of consistency with the microscopic description of nature (in particular the dark sector that still eludes us) and finally a growing number of observational tensions (Hubble tension, JWST observations, etc.). Can we sketch out the evolutions, or revolutions, that this portends?