  Coule's primary objection to the Alcubierre "warpdrive" is that the material
producing the warp field needs to be superluminal. This difficulty is solved by
placing the drive material inside its own warp field (making the drive system
part of the payload), but we then have to deal with Low's related objection,
that there is then a restricted rate at which this "naked" warp-field can
propagate through the background metric. We argue that the propagation of this
sort of gravitational wave is not a trivial problem, and that the possibility
of ultrafast warpfield propagation should not be dismissed without further
research.
