Yvonne Choquet-Bruhat

Yvonne Choquet-Bruhat (; 29 December 1923 – 11 February 2025) was a French mathematical physicist now best remembered for her investigation of the mathematics of general relativity. She also studied non-Abelian gauge theory, relativistic hydrodynamics, and supergravity. and was a Grand Officer of the Legion of Honour.

Early life and education Yvonne Bruhat was born in Lille on 29 December 1923 in an intellectual family. Her brother François Bruhat also became a mathematician. Uncertain whether to study medicine, physics, or mathematics, she decided on the last. While it was known that the equations of motion derived from Newton's laws of motion and gravitation yielded unique solutions with initial conditions, whether this was true for Einstein's gravitational field equations remained unproven until her landmark thesis. She expressed the Einstein field equations in vacuum using harmonic coordinates, previously introduced by Théophile De Donder and Cornelius Lanczos, in which case they become non-linear hyperbolic partial differential equations, While Georges Darmois had already tackled the problem for analytic solutions, Bruhat's proof applied to non-analytic cases as well. Bruhat's faith in her mathematical work was vindicated by multi-messenger astronomy. She attended the Conference on the Role of Gravitation in Physics in Chapel Hill, North Carolina, in 1957. The International Society on General Relativity and Gravitation (ISGRG) was formed 14 years later. From 1958 to 1959 she taught at the University of Reims. In 1960 relocated to the Sorbonne in Paris. important in the study of global aspects of the Cauchy problem in general relativity and the theorems on gravitational singularities of Roger Penrose and Stephen Hawking. With Cécile DeWitt-Morette and Margaret Dillard-Bleick, she published monograph titled Analysis, Manifolds and Physics, detailing the relevance of global analysis for physics. Her work in 1981 with Demetrios Christodoulou demonstrated the existence of global solutions of the Yang–Mills, Higgs, and spinor field equations in 3+1 dimensions. In 1984 she examined results in supergravity that can be extended to 11 dimensions.

In 1978 Yvonne Choquet-Bruhat was elected a correspondent to the Academy of Sciences and on 14 May 1979 became the first woman to be elected a full member.

It is now common to study such developments. For instance, the well-known theorem of Demetrios Christodoulou and Sergiu Klainerman on stability of Minkowski space asserts that if is a vacuum initial data set with and sufficiently close to zero (in a certain precise form), then its maximal globally hyperbolic vacuum development is geodesically complete and geometrically close to Minkowski space.

Choquet-Bruhat's proof makes use of a clever choice of coordinates, the wave coordinates (which are the Lorentzian equivalent to the harmonic coordinates), in which the Einstein equations become a system of hyperbolic partial differential equations, for which well-posedness results can be applied.

Personal life and death

In 1947, she married fellow mathematician Léonce Fourès.

Choquet-Bruhat died on 11 February 2025 in Merignac, France (33700), at the age of 101. . Second edition. North-Holland Publishing Co., Amsterdam-New York, 1982. xx+630 pp. Choquet-Bruhat, Yvonne; DeWitt-Morette, Cécile. Analysis, manifolds and physics. Part II. North-Holland Publishing Co., Amsterdam, 1989. xii+449 pp. Choquet-Bruhat, Y. Distributions. (French) Théorie et problèmes. Masson et Cie, Éditeurs, Paris, 1973. x+232 pp. Choquet-Bruhat, Yvonne. General relativity and the Einstein equations. Oxford Mathematical Monographs . Oxford University Press, Oxford, 2009. xxvi+785 pp. Choquet-Bruhat, Y. Géométrie différentielle et systèmes extérieurs. Préface de A. Lichnerowicz. Monographies Universitaires de Mathématiques, No. 28 Dunod, Paris 1968 xvii+328 pp. Choquet-Bruhat, Yvonne. Graded bundles and supermanifolds. Monographs and Textbooks in Physical Science. Lecture Notes, 12. Bibliopolis, Naples, 1989. xii+94 pp. Choquet-Bruhat, Yvonne. Introduction to general relativity, black holes, and cosmology. With a foreword by Thibault Damour. Oxford University Press, Oxford, 2015. xx+279 pp. Choquet-Bruhat, Y. Problems and solutions in mathematical physics. Translated from the French by C. Peltzer. Translation editor, J.J. Brandstatter Holden-Day, Inc., San Francisco, Calif.-London-Amsterdam 1967 x+315 pp.

Popular book Choquet-Bruhat, Yvonne. A lady mathematician in this strange universe: memoirs. Translated from the 2016 French original. World Scientific Publishing Co. Pte. Ltd., Hackensack, NJ, 2018. x+351 pp. Celebratio Mathematica records 250 publications by Choquet-Bruhat

Honours and awards Médaille d'Argent du Centre National de la Recherche Scientifique, 1958 Prix Henri de Parville of the Académie des Sciences, 1963 Member (since 1965), (President 1980–1983) Member, Académie des Sciences, Paris (elected 1979) Elected to the American Academy of Arts and Sciences 1985 Association for Women in Mathematics Noether Lecturer, 1986 Commandeur de la Légion d'honneur, 1997 Dannie Heineman Prize for Mathematical Physics, 2003 She was elevated to the 'Grand Officier' and 'Grand Croix' dignities in the Légion d'Honneur in 2008.

In 2026, Choquet-Bruhat was announced as one of 72 historical women in STEM whose names are proposed to be added to the 72 men already celebrated on the Eiffel Tower. Anne Hidalgo, the Mayor of Paris, announced this on the recommendation of a committee led by Isabelle Vauglin of Femmes et Sciences and Jean-François Martins, which represents the operating company that manages the Eiffel Tower.