  Using traversable wormholes as theoretical background, we revisit a deep
question of general relativity: Does a uniformly accelerated charged particle
radiate? We particularize to the recently proposed gravitational \v{C}erenkov
radiation, that happens when the spatial part of the Ricci tensor is negative.
If $^{^{(3+1)}}R^i_{\phantom{i}i}< 0$, the matter threading the gravitational
field violates the weak energy condition. In this case, the effective
refractive index for light is bigger than 1, i.e. particles propagates, in that
medium, faster than photons. This leads to a violation of the equivalence
principle.
