  In classical mechanics, Galilean covariance and the principle of relativity
are completely equivalent and hold for all possible dynamical processes. In
contrast, in relativistic physics the situation is much more complex. It will
be shown that Lorentz covariance and the principle of relativity are not
completely equivalent. The reason is that the principle of relativity actually
only holds for the equilibrium quantities that characterize the equilibrium
state of dissipative systems. In the light of this fact it will be argued that
Lorentz covariance should not be regarded as a fundamental symmetry of the laws
of physics.
