On the causality requirement for diffusive-hyperbolic systems in non-equilibrium thermodynamics

The consequences of the Causality Principle for the constitutive equations of non-equilibrium thermodynamics are investigated. It is proved that such a principle, once interpreted in the light of the experimental results, is compatible with both the hyperbolic and parabolic thermodynamic theories. As an example, a diffusive-hyperbolic model of heat conduction is presented.