One of the world's most famous scientists, Jules Henri Poincaré (1854-1912) was born in the eastern French city of Nancy into an influential family. His father Léon Poincaré (1828-1892) was a professor of medicine at the University of Nancy. His younger sister Aline married the néo-Kantian philosopher Emile Boutroux. Another noted member of his family was his cousin Raymond Poincaré, President of France from 1913 to 1920.
Poincaré is one of France's most reknowned mathematicians, and contributed important works in physics, astronomy and philosophy of science. He is often described as a polymath, and in mathematics as "The Last Universalist".
Poincaré contributed to mathematics, mathematical physics and celestial mechanics. He formulated the Poincaré conjecture, one of the most famous problems in mathematics, for which Grigori Perelman offered a solution four years ago. In his research on the three-body problem, Poincaré became the first person to describe a chaotic trajectory and is considered to be the founder of the field of algebraic topology.
Like Albert Einstein, Poincaré elevated the principle of relativity to a postulate in 1905; unlike Einstein, he retained the notion of a luminiferous ether (thus obviating the need for Einstein's light postulate). In addition, he characterized the Lie-algebra of the Lorentz group, and derived the first two Lorentz-covariant laws of gravitation. Along the way, Poincaré provided the four-vectors for Hermann Minkowski's four-dimensional spacetime theory (1908), but deplored the latter's Einsteinian view of space and time coordinates, advocating in its place an interpretative convention equivalent to the postulation of Galilean spacetime.
Poincaré often intervened in philosophical discussions and controversies concerning the foundations of science. His articles dedicated to the philosophy of science are gathered in 4 volumes: Science and Hypothesis (1902), The Value of Science (1905), Science and Method (1908) and Last Thoughts (1913). Considered to be the "father of conventionalism", Poincaré emphasized the creative role of scientists in coming to grips with reality.
Poincaré received many awards and honours throughout his professional career. He became a member of the "Académie Française" in 1908, and the Poincaré group used in physics and mathematics was named after him.
In tribute to this great mathematician, the Henri Poincaré Archives in Nancy has compiled a comprehensive collection of the "Poincaré correspondance", and Nancy's prestigious science and technology University also bears his name.
Although Nancy's scientific history and reputation are most often associated with, and even dominated by, Poincaré, other names deserve to be mentioned.
In the field of mathematics, a prime example among numerous others would be Charles Hermite (1822-1901), who directed Poincaré's PhD. He was famous at the time for his work on elliptic functions and number theory, as well as for his influential position as an inspiring teacher at the Ecole Polytechnique, the Ecole Normale Supérieure and the Faculty of Sciences of Paris.
Nancy also provided France with two of its greatest mathematicians, Elie and Henri Cartan. Elie Cartan (1869-1951) was professor at the Faculty of Sciences of Nancy at the turn of the 20th Century and made important contributions in group theory and differential geometry. The Institute of Mathematics of Nancy is now named Institut Elie Cartan in his honour.
His son, Henri Cartan, was born in Nancy in 1904. He worked on algebraic topology but is also well-known as a founding member of the Bourbaki group, of which he was an active participant from the beginning in 1935. From a methodological point of view, he represents a totally non-Poincarean, anti-intuitionistic and pro-hilbertian way of doing and exposing mathematics. He died very recently, in 2008, at the age of 104.
Though few famous theoricians in physics, apart from Poincaré, come from Lorraine, Nancy was home to several great experimentalists, such as René-Prosper Blondlot (1849-1930), who did major work on experimental consequences of Maxwell's theories. Unfortunately, he is now especially famous for his false discovery of the N rays, and the controversy it lead to during the period from 1903 to 1904.
Nancy was also one of the pioneering towns in France concerning the application of physics and chemistry to industry. The "Institut de Chimie de Nancy" (at the origin of the Ecole Nationale Supérieure des Industries Chimiques de Nancy) was founded in 1892 under the impulsion of Albin Haller (1849-1925), who became its director, and won the Davy medal in 1917.
Nancy is also well-known for his school of psychology, in the field of suggestibility. Hyppolite Bernheim (1840-1919) is one the most famous representants of this school. Professor at the Faculty of Medicine of Nancy, he was a pioneer in using suggestion and hypnotism for therapeutic treatments, and was considered during the 1880's as an important searcher. His influential work made Nancy an attractive place for psychology and psychiatry. Sigmund Freud visited him in 1889 and was deeply interested by what he learnt on this occasion.
On the philosophical side, Nancy's most interesting teacher and searcher was Raymond Ruyer (1902-1984). Against the majoritory fashions of French philosophy during the 60's, Ruyer showed strong interest towards science, especially biology and cybernetics and their consequences concerning consciousness. He made interesting and unfortunately too often ignored contributions in favor of a finalist position.
The Stanislas Academy was founded by King Stanislas Leszczynski in 1750. Since then, the Academy has kept alive the spirit of its foundator, and has promoted science, literature, culture and enlightenment in Nancy and Lorraine. Prestigious names such as Montesquieu, Fontenelle, Buffon or Poincaré were members of the Academy.