Élie Joseph Cartan (French: [kaʁtɑ̃]; 9 April 1869 – 6 May 1951) was an influential French mathematician who did fundamental work in the theory of Lie groups, differential systems (coordinate-free geometric formulation of PDEs), and differential geometry. He also made significant contributions to general relativity and indirectly to quantum mechanics. He is widely regarded as one of the greatest mathematicians of the twentieth century.
His son Henri Cartan was an influential mathematician working in algebraic topology.
Élie Cartan was born 9 April 1869 in the village of Dolomieu, Isère to Joseph Cartan (1837–1917) and Anne Cottaz (1841–1927). Joseph Cartan was the village blacksmith; Élie Cartan recalled that his childhood had passed under "blows of the anvil, which started every morning from dawn", and that "his mother, during those rare minutes when she was free from taking care of the children and the
house, was working with a spinning-wheel". Élie had an elder sister Jeanne-Marie (1867–1931) who became a dressmaker; a younger brother Léon (1872–1956) who became a blacksmith working in his father's smithy; and a younger sister Anna Cartan (1878–1923), who, partly under Élie's influence, entered École Normale Supérieure (as Élie had before) and chose a career as a mathematics teacher at a lycée (secondary school).
Élie Cartan entered an elementary school in Dolomieu and was the best student in the school. One of his teachers, M. Dupuis, recalled "Élie Cartan was a shy student, but an unusual light of great intellect was shining in his eyes, and this was combined with an excellent memory". Antonin Dubost, then the representative of Isère, visited the school and was impressed by Cartan's unusual abilities. He recommended Cartan to participate in a contest for a scholarship in a lycée. Cartan prepared for the contest under the supervision of M. Dupuis and passed at the age of ten. He spent five years (1879–1884) at the college of Vienne and then two years (1884–1886) at the Lycée of Grenoble. In 1886 he moved to the Lycée Janson de Sailly in Paris to study sciences for two years; there he met and befriended his classmate Jean-Baptiste Perrin (1870–1942) who later became a famous physicist in France.
Cartan enrolled in the École Normale Supérieure in 1888, where he attended lectures by Charles Hermite (1822–1901), Jules Tannery (1848–1910), Gaston Darboux (1842–1917), Paul Appell (1855–1930), Émile Picard (1856–1941), Édouard Goursat (1858–1936), and Henri Poincaré (1854–1912) whose lectures were what Cartan thought most highly of.
After graduation from the École Normale Superieure in 1891, Cartan was drafted into the French army, where he served one year and attained the rank of sergeant. For the next two years (1892–1894) Cartan returned to ENS and, following the advice of his classmate Arthur Tresse (1868–1958) who studied under Sophus Lie in the years 1888–1889, worked on the subject of classification of simple Lie groups, which was started by Wilhelm Killing. In 1892 Lie came to Paris, at the invitation of Darboux and Tannery, and met Cartan for the first time.
Cartan defended his dissertation, The structure of finite continuous groups of transformations in 1894 in the Faculty of Sciences in the Sorbonne. Between 1894 and 1896, Cartan was a lecturer at the University of Montpellier; during the years 1896 through 1903, he was a lecturer in the Faculty of Sciences at the University of Lyon.
In 1903, while in Lyon, Cartan married Marie-Louise Bianconi (1880–1950); in the same year, Cartan became a professor in the Faculty of Sciences at the University of Nancy. In 1904, Cartan's first son, Henri Cartan, who later became an influential mathematician, was born; in 1906, another son, Jean Cartan, who became a composer, was born. In 1909 Cartan moved his family to Paris and worked as a lecturer in the Faculty of Sciences in the Sorbonne. In 1912 Cartan became Professor there, based on the reference he received from Poincaré. He remained in Sorbonne until his retirement in 1940 and spent the last years of his life teaching mathematics at the École Normale Supérieure for girls.
As a student of Cartan, the geometer Shiing-Shen Chern wrote:Usually the day after [meeting with Cartan] I would get a letter from him. He would say, “After you left, I thought more about your questions...”—he had some results, and some more questions, and so on. He knew all these papers on simple Lie groups, Lie algebras, all by heart. When you saw him on the street, when a certain issue would come up, he would pull out some old envelope and write something and give you the answer. And sometimes it took me hours or even days to get the same answer... I had to work very hard.In 1921 he became a foreign member of the Polish Academy of Learning and in 1937 a foreign member of the Royal Netherlands Academy of Arts and Sciences. In 1938 he participated in the International Committee composed to organise the International Congresses for the Unity of Science.
He died in 1951 in Paris after a long illness.
In 1976, a lunar crater was named after him. Before, it was designated Apollonius D.
In the Travaux, Cartan breaks down his work into 15 areas. Using modern terminology, they are:
Hypercomplex numbers, division algebras
Systems of PDEs, Cartan–Kähler theorem
Integrable systems, theory of prolongation and systems in involution
Infinite-dimensional groups and pseudogroups
Differential geometry and moving frames