SIGNAL PROPAGATION IN A RELATIVISTIC FLUID WITH VISCOSITY AND HEAT-CONDUCTION

In order to eliminate the paradox due to the faster-than-light propagation of signals in standard relativistic models of fluids with dissipation, it is proposed to replace the dissipative coefficients in the constitutive equations by relaxation kernels, i.e. to use a theory with memory. It is shown that this yields signals with finite velocity, which, however, need not be less than that of light. The condition that the signal propagate at a velocity not exceeding that of light in a vacuum imposes certain a prior restrictions on the dissipative characteristics of a fluid.