Sophus Lie

Marius Sophus Lie was a Norwegian mathematician, born on 17 December 1842 and died on 18 February 1899. He largely created the theory of continuous symmetry and applied it to the study of geometry and differential equations. He also made substantial contributions to the development of algebra. Continuous symmetry means symmetry given by smooth families of transformations such as rotations, and the groups and algebras that describe it are now called Lie groups and Lie algebras in his honour.