Habemus the first woman member of the French Academy of Sciences or dum vita est, spes est! Yvonne Choquet-Bruhat is an internationally recognized French mathematician and physicist. She is known for her research at the border of mathematics and physics, ranging from the first mathematical proof of the existence of solutions to Einstein’s theory of general relativity to the conversion of electromagnetic waves into gravitational waves (or vice versa) near a black hole. Yvonne Choquet-Bruhat developed new mathematical methods that provided a solid foundation for analyzing several physical theories, including the theory of general relativity, the non-Abelian gauge theory of the standard model, relativistic hydrodynamics, and the theory of supergravity. Yvonne Choquet-Bruhat performed pioneering research on the initial value problem of general relativity. Her exceptional work in this field was highlighted as one of the “milestones of general relativity”.

Yvonne Choquet-Bruhat, a universal scientist, gained her fame through patience, sacrifice, hard work, and only by merit of her own strengths. She is defined by high standards of honor. Yvonne Choquet-Bruhat is a model for women scientists and accomplished women, in general.

Ad honorem, the celebration of the 350th anniversary (1666–2016) of the French Academy of Science provides us with the opportunity to remember Yvonne Choquet-Bruhat. She is a trailblazer for women in science!

1 Yvonne Choquet-Bruhat's education: a hymn to life

O life as one ode to joy! In 1923, the great soprano Maria Callas was born, and the great musician George Enescu became the conductor of the Philadelphia Orchestra. W. Rontgen, J. D. van der Waals, J. Dewar and G. Eiffel died in 1923, and several notable scientists were born in the same year, including P. W. Anderson (Nobel Laureate in Physics, 1977), D. C. Gajdusek (Nobel Laureate in Physiology or Medicine, 1976), A. Carlsson (Nobel Laureate in Physiology or Medicine, 2000), W. Kohn (Nobel Laureate in Chemistry, 1998), R. Marcus (Nobel Laureate in Chemistry, 1992), V. L. Fitch (Nobel Laureate in Physics, 1980), J. Kilby (Nobel Laureate in Physics, 2000), the French physicist C. Bloch, and the great mathematicians H. Cabannes, R. Thom (Fields Medal, 1958), G. Kreisel, R. Bott, H. Chandra, and F. Dyson.

Yvonne Suzanne Marie Louise Choquet-Bruhat was born on 29 December 1923, in Lille. She was born into a family of French intellectuals; she was the daughter of Berthe Hubert Bruhat, a philosophy professor, and Georges Bruhat, a prominent physics professor at the Faculty of Science in Paris. Choquet-Bruhat’s brother was the mathematician François Bruhat (born in 1929). Her father George was awarded his doctorate in physics in 1914. He was appointed to the University of Lille in 1919 and then promoted to professor of physics in 1921. Her mother, Berthe Hubert Bruhat, was ranked first in the ‘concours de l’agrégation’ in arts in 1917. In 1927, her father was appointed to the Faculty of Science in Paris, and the girl moved to Paris with her family. Georges Bruhat was appointed to deputy director of the ‘École normale supérieure’ in 1935 and then to the physics chair at the school in 1941.

Labor is the source of virtue. – Herder

Yvonne Choquet-Bruhat attended secondary school in Paris and obtained her bachelor’s degree in 1941. She won the second prize in physics in open competition and used her prize to attend the ‘École normale supérieure’ in Sèvres (for girls only), just outside Paris. This women’s university was the partner institution of the ‘École normale supérieure de Paris’. She graduated from the ‘École normale supérieure de jeunes filles’ in 1946 and performed research with André Lichnerowicz (who later became her doctoral thesis supervisor). She studied with great teachers, including Georges Darmois and Jean Leray, and began to teach at the ‘École normale supérieure’ in 1946, after she achieved first place on the mathematics aggregation examination. From 1946 to 1949, Yvonne Choquet-Bruhat was an assistant at the ‘École normale supérieure’. From 1949 to 1951, she was a research assistant and then a research associate at the ‘Centre national de la recherche scientifique ‘(CNRS). She was awarded her doctorate in 1951 for her thesis Théorème d’existence pour certains systèmes d’équations aux dérivées partielles non linéaires. Yvonne Choquet-Bruhat then completed a postdoctoral fellowship at the Institute for Advanced Study at Princeton between 1951 and 1952. In 1953, she became a lecturer at the Faculty of Science in Marseilles. Yvonne Choquet-Bruhat soon returned to the Institute for Advanced Study at Princeton during the 1955–1956 academic year. Between 1958 and 1959, she served as a professor at the ‘École des sciences de Reims’. In 1960, she was appointed to the analytical mechanics and celestial mechanics chair of the Faculty of Science in Paris. In 1971, the Faculty of Science was dismantled, and Yvonne Choquet-Bruhat moved to the Pierre-and-Marie-Curie University, where she remained until her retirement in 1992. She has been professor emeritus since then.

2 Research accomplishments

It is the theory that decides what we can observe. – Einstein

Yvonne Choquet-Bruhat’s research interests in the field of mathematical physics include partial differential equations on manifolds and their application to fundamental physics problems in the areas of general relativity, relativistic fluids, magneto fluids and plasmas, supergravity, and gauge theories. Yvonne Choquet-Bruhat essentially invented the field of mathematical general relativity. The study of gravity has fascinated the scientist and the philosophers such as Liiceanu, who wrote about gravitational freedom. Although several explicit solutions of the Einstein gravitational field equations were found before Yvonne Choquet-Bruhat’s work, it was only after her proof that Einstein’s equations were well-posed in 1952 that general relativity became a topic of serious mathematical interest. In mathematical general relativity, Yvonne Choquet-Bruhat made groundbreaking advances in solving the Einstein constraint equations and analyzing the evolution of initial data into space-time solutions of the Einstein field equations. Key aspects of her work include developing new mathematical tools and novel approaches for applying them to problems of interest. In addition, she introduced new formulations of Einstein’s theory of gravitation that recently spurred great progress in numerical relativity, including the calculation of the gravitational waves emitted when two black holes collapse and merge together. These results are of great importance for giant interferometric gravitational wave detectors, such as Virgo or LIGO.

The man who moves a mountain begins by carrying away small stones. – Confucius

In a seminal work published as her ‘thèse d’État’ when she was 28 years old, Yvonne Choquet-Bruhat showed that if the initial state of a gravitational field is represented by certain geometric fields that satisfy the constraint equations, then a space-time solution of the complete system of Einstein’s equations exists. This solution is compatible with the initial state data set and describes the past and future of the gravitational field. Yvonne Choquet-Bruhat used fundamental mathematical results to provide a solid foundation for solving classical physics equations, most importantly those pertaining to general relativity and other theories of gravity, supergravity, and non-Abelian gauge theories of the standard model.

Yvonne Choquet-Bruhat is widely acclaimed both in France and worldwide as an author of scientific papers. In concreto, she has published well over 200 research papers and three major research books. She has presented at several conferences and invited lectures at both national and international congresses.

Her career has consisted of many remarkable achievements. She is an inspiring teacher and a remarkable woman of science with an extraordinary gift for logical reflection. All who worked with Yvonne Choquet-Bruhat have been attracted by his genial and kind personality, and none failed to be impressed by her intellect and by the high, almost exacting, standards he set for scientific work.

In his chosen field of research, Yvonne Choquet-Bruhat is preeminent and has established a tradition that will not be easily upheld. Through her work, she is assured of a worthy place in the history of the science to which he was devoted. Yvonne Choquet-Bruhat has proven that all boundaries can be broken by the desire to succeed.

I love those who yearn for the impossible. – Goethe

Yvonne Choquet-Bruhat, the first woman elected to the French Academy of Sciences, is the symbol of women in science.