Short biography of Jean-Marie Souriau

Short biography of Jean-Marie Souriau Frédéric Barbaresco The name Souriau means “mouse” in “the Perche ”. In the “Vendomois ”, the Souriau from 1490 to 1819 were all “ Master Plowmen” or “ Master Millers”. Jean-Marie Souriau was born June 3, 1922 in Paris in the 6 th arrondissement. Jean-Marie Souriau comes from a family of Philosopher all graduated from ENS Paris. His father, Michel Souriau joined the ENS Paris in 1910 and obtained the aggregation in philosophy in 1914 and wrote in 1938 an article on “Introduction to mathematical symbolism” before being mobilized as a battalion commander. His uncle, Etienne Souriau, is a French philosopher, specialized in aesthetics, entered the ENS Paris in 1912, received first in the aggregation in philosophy in 1920. In 1958, Etienne Souriau was elected member of the Academy of moral sciences and policies by a committee in which Charles de Gaulle appears, and will be the director of the thesis of the filmmaker Éric Rohmer. Etienne Souriau published a book on “Structure of the Work of Art (Structure de l’Oeuvre d’Art) ”. His grandfather, Paul Souriau, is a French philosopher known for his work on the theory of invention and aesthetics, who entered the ENS Paris in 1873 and aggregated in philosophy in 1876. It can be noted that his grand-father, Paul Souriau, composed a thesis titled “Theory of Invention” (théorie de l’invention), published in 1881, and also a Latin thesis titled “De motus perceptione”, which aimed to determine the importance of vision for the perception of movements (the initial thesis title was “De visione motus” and was a precursor to his future work on the perception of movement). We can assume that Jean-Marie Souriau read his grandfather's thesis and was influenced by it for his own work. In 1889, Paul Souriau published a book on “The Aesthetics of Movement (L’Esthétiquee du movement)” which describes two levels of aesthetics for movement: mechanical beauty (the adaptation of movement to fulfill its purpose) and meaning of movement (the meaning that the movement communicates to an outside observer). In doing so, Paul Souriau distinguished movement from perception of movement, concepts that would later become the subject of motor cognition and psychophysics. It is interesting to note that Etienne Souriau studied the structures of aestheticism, Paul Souriau developed the aestheticism of the movement and Jean-Marie Souriau founded the structures of the movement. This triptych will remain an important element of French philosophy at the hinge of this 1900 Spirit (Esprit 1900). Jean-Marie Souriau from 1932 to 1942 did his secondary studies in Nancy, Nîmes, Grenoble and Versailles. Jean-Marie Souriau married Christianne Hoebrechts, who died prematurely in 1985 and with whom he had five children Isabelle, Catherine, Yann, Jérôme and Magali. He entered the ENS Paris in 1942, passing twice in the unoccupied zone in Lyon and a second time in Paris. Also received at the Ecole Polytechnique, he resigned to join the ENS Paris. During his studies at the ENS, he took courses at the Sorbonne from the physicist Yves Rocard and the mathematician Elie Cartan. He volunteered for “La France Libre” in 1944. On his return in 1946, he passed the mathematics aggregation, and the same year joined a laboratory working on the scanning electron microscope and then entered as a researcher in a " theoretical physics” session at the CNRS. Fig. 1. Jean-Marie Souriau, a student at the Ecole Normale Supérieure in Paris in 1942, with Jacques Dixmier and René Deheuvels among others He finally opted for a career as an aeronautical engineer at ONERA by becoming head of research groups and defending his thesis in June 1952 on the theme of "aircraft stability " which was supervised by André Lichnerowicz (professor at the College of France) and Joseph Pérès (collaborator of Vito Volterra), which was useful for the design of the “Caravelle” and “Concorde” aircrafts (ONERA obtains royalties from Souriau patents). In this thesis, he refers to the book by Yves Rocard on “ General dynamics of vibrations ”. On his thesis, he wrote [1] “ I studied the problems of vibrations and stability which arise in aeronautics and in some other techniques; this work allowed me to develop stability criteria which are presented in the form of algorithms which can be easily calculated from theoretical data or from tests; they have since been regularly used in various fields (subsonic and supersonic airplanes, navigation instruments, etc. ) ” . I obtained a copy of this thesis through colleagues at ONERA, whose cover I am reproducing below. Fig. 2. Cover page of the thesis of Jean-Marie Souriau “ On the stability of planes ” defended on June 20, 1952, as well as the bibliographic page which refers to the work of Yves Rocard. During this period, he also invented in 1948 an algorithm named Leverrier -Souriau algorithm which allows to compute the characteristic polynomial of a matrix and which was used on the first IBM computers in the United States. From 1948 to 1952, he also provided continuing education at the Special School of Aeronautical Works (ESTA, Paris) under the general title “New Methods of Mathematical Physics”. From 1951 to 1952, he created and ran the Mechanics course in the third year of the École Normale Supérieure de l'Enseignement Technique (ÉNSET, Paris). From 1952, he also had a university education in the following disciplines: Mathematics, Mechanics, Relativity, Mathematical Methods of Physics and Computer Science. After his thesis in 1954, he joined the “Institut des Hautes Etudes ”, rue de Rome in Tunis, and moved with his wife to Carthage. It is during this period that he rereads and deepens the work of Lagrange in Analytical Mechanics and discovers the symplectic structures that he will formalize in his book “Structure of dynamic systems ”. It is by thinking of his discussions with ONERA engineers that he invents his masterpiece, the “moment map” (application moment). We can read in the interview by Patrick Iglesias [ 2 ] “ It was with the memory of discussions with engineers who asked themselves the following question: what is essential in mechanics. I remember very well an engineer who asked me: is mechanics simply the principle of conservation of energy? This is fine for a oneparameter system, but once there are two, it is not enough. I had learned of course the Lagrange equations and all the analytical principles of mechanics, but it was all a cookbook; we did not see any real principles”. He remained in Tunis from 1952 to 1958, as Lecturer, then as Full Professor at the Institut des Hautes Études. In 1953, he participated in Strasbourg in the conference on Differential Geometry. Fig. 3. Jean-Marie Souriau at the Conference on “Differential Geometry” in Strasbourg in 1953. In the same picture, Jean-Louis Koszul , André Weil, Shiing-Shen Chern , Georges de Rham , Charles Ehresmann , Lucien Godeaux , Heinz Hopf , André Lichnerowicz (the director of the thesis of Jean-Marie Souriau), Bernard Malgrange , John Milnor, Georges Reeb , Laurent Schwartz, René Thom, Paulette Libermann. In 1958, he became Professor at the University of Aix-Marseille. He remained in Marseille throughout his career, and from 1978 to 1985 became Director of the Center for Theoretical Physics of Marseille (CNRS laboratory) in charge of the teams in Theoretical Mechanics, Geometry and Quantification, Astronomy and Cosmology. He was also professor of Mathematics at the University of Provence (Aix-Marseille I) and ended up as an exceptional Professor with second echelon. He was also a member of the “Société Mathématique de France” and of the French Society of Specialists in Astronomy. For five years, he also taught the course of the third interuniversity cycle of Pure Mathematics in Marseille and the third interuniversity cycle of Theoretical Physics in Marseille-Nice. He was a member of the Editorial Board of the Journal of Geometry and Physics in Florence. He organized two International Colloquiums of the CNRS in 1968 and 1981 and Days of the “Société Mathématique de France”. Honored by the Academic Palms and of the National Order of Merit, he obtained the Prize on the subject "Vibrations " put up for competition by the Association for Aeronautical Research in 1952, the Prize on the subject “Cosmology” put out for competition by the Foundation Louis Jacot in 1978, the Grand Prix Jaffe of the French Academy of Sciences in 1981 and the Great Scientist prize of the City of Paris in 1986. Jean-Marie Souriau died in 2012 in its 90th year. [1] Souriau J-M., On Geometric Dynamics, Discrete and Continuous Dynamical Systems, Volume 19, Number 3, pp. 595–607, November 2007 [2] Iglesias P., Itinéraire d’un mathématicien : Un entretien avec Jean-Marie Souriau, Le journal de Maths des élèves, ENS Lyon, October 1, 1995