Henri Poincaré (1854-1912)

Henri Poincaré was one of the last universal mathematicians. He made contributions to the theory of complex functions, to number theory, algebraic and differential geometry, and to many branches of applied mathematics, including celestial mechanics. He invented the notion of an abstract dynamical system in order to attack the question of the stability of the solar system, and, in the course of this study, invented the field of topology. He believed that all physical laws should be "invariant under the Lorentz group." This insight, which expresses the hidden symmetries of Maxwell's equations, leads logically to Einstein's theory of special relativity when applied to Newtonian mechanics.