The Virial Theorem in Self-Gravitating Systems

The Virial Theorem of Clausius, which relates the average kinetic and potential energies of a dynamical system, is a powerful tool in astrophysics with a wide range of applications. I will show how the scalar form of the virial equilibrium equation is derived from first principles and demonstrate its utility in explaining the heating of contracting bodies, weighing supermassive black holes, and measuring the distances to far-flung galaxies.