Thermal Dynamics in General Relativity

Understand

We discuss a relativistic model for heat conduction, building on a convective variational approach to multi-fluid systems where the entropy is treated as a distinct dynamical entity.

• We demonstrate how this approach leads to a relativistic version of the Cattaneo equation, encoding the finite thermal relaxation time that is required to satisfy causality.
• We also show that the model naturally includes the non-equilibrium Gibbs relation that is a key ingredient in most approaches to extended thermodynamics.
• Focussing on the pure heat conduction problem, we compare the variational results to the second-order model developed by Israel and Stewart.