  In a glassy system different degrees of freedom have well-separated
characteristic times, and are described by different temperatures. The
stationary state is essentially non-equilibrium. A generalized statistical
thermodynamics is constructed and a universal variational principle is
proposed. Entropy production and energy dissipation occur at a constant rate;
there exists a universal relation between them, valid to leading order in the
small ratio of the characteristic times. Energy dissipation (unlike entropy
production) is closely connected to the fluctuations of the slow degree.
Corrections due to a finite ratio of the times are obtained. Onsager relations
in the context of heat transfer are also considered. They are always broken in
glassy states, except close to equilibrium.
