L'int?r?t que portait Henri Poincar? (1854-1912) ? des questions d'ordre physique a ?t? durable et profond; elle couvre presque toute sa carri?re, et marque l'histoire de la physique tout au long du 20^?me si?cle. Sa correspondance avec cinquante-et-un physiciens, quatre chimistes, et cinq ing?nieurs commence d?s 1879, lorsqu'il s'engage activement dans la recherche scientifique. Elle est rythm?e par des grandes d?couvertes d'ordre exp?rimental, instrumental, et th?orique.

Henri Poincar?, while well-known as the most brilliant mathematician at the close of the 19th century, is also a founder of 20th-century physics, in virtue of his fundamental contributions to Maxwell's theory, systems dynamics, electron theory, relativity and quantum theory. These subjects and others are discussed in this critical edition of his correspondence with sixty physicists, chemists, and engineers.