  It is often argued that superluminal velocities and nontrivial spacetime
topologies, allowed by the theory of relativity, may lead to causal paradoxes.
By emphasizing that the notion of causality assumes the existence of a time
arrow (TA) that points from the past to the future, the apparent paradoxes
appear to be an artefact of the wrong tacit assumption that the relativistic
coordinate TA coincides with the physical TA. The latter should be identified
with the thermodynamic TA, which, by being absolute and irrotational, does not
lead to paradoxes.
