Definition:Lie Group/Historical Note

Historical Note on Lie Group
When the concept of a Lie group was originally researched, it did not appear to have any immediate practical application.

In more recently times, they have been used:
 * to describe pseudo-Riemannian locally homogeneous symmetric spaces, to be used in geometric theory of gravitation
 * to model phenomena in quantum mechanics, from $1925$ to $1926$, via Hermitian matrix representations of observations