  The null geodesic congruence for the Lorentzian version of Hawking's wormhole
is studied, in spherical Rindler coordinates. One finds that the wormhole
throat expands exponentially and the "flare - out" condition is satisfied. A
time reversal is equivalent with an inversion applied to the radial coordinate.
The stress energy is mostly located near wormhole's throat and the anisotropic
fluid is comoving with the spherical distribution of accelerating observers.
Far from the throat (the light cone in Cartesian coordinates) the negative
energy density acquires an expression similar with the Casimir energy density
between two perfectly reflecting plates. We conjecture that the light
propagation follows the throat of a preexisting expanding wormhole (a "light
dragging" phenomenon).
