On the inertia of heat

Abstract

Does heat have inertia? This question is at the core of a long-standing controversy on Eckart's dissipative relativistic hydrodynamics. Here I show that the troublesome inertial term in Eckart's heat flux arises only if one insists on defining thermal diffusivity as a spacetime constant. I argue that this is the most natural definition, and that all confusion disappears if one considers instead the space-dependent comoving diffusivity, in line with the fact that, in the presence of gravity, space is an inhomogeneous medium.

3 pages

References in corpus (2)

• Relativistic transport theory for simple fluids at first order in the gradients: a stable picture
• On the nature of the so-called generic instabilities in dissipative relativistic hydrodynamics

Cited by in corpus (1)

• A hyperbolic theory of relativistic conformal dissipative fluids