The parabolic model for heat conduction discussed above shows that the Fourier equation (and the more general Fick's law of diffusion) is incompatible with the theory of relativity for at least one reason: it admits infinite speed of propagation of the continuum field (in this case: heat, or temperature gradients). To overcome this contradiction, workers such as Carlo Cattaneo, Vernotte, Chester, and others proposed that Fourier equation should be upgraded from the parabolic to a hyperbolic form, where the n, the temperature field θ θ is governed by: 1 C 2 ∂ ∂ 2 θ θ ∂ ∂ t 2 + 1 α α ∂ ∂ θ θ ∂ ∂ t = ∇ ∇ 2 θ θ .