From Mark O'Neill
Given that the proposed gravastars have a solid crust as opposed to the event
horizon of a black hole, material falling onto one would hit the crust rather
than disappearing beyond the event horizon.
Surely this would mean that a gravastar would vibrate under the shock of
impact, unlike a black hole. I suspect the vibration would be slight, given the
density of the crust, but it might be detectable and would give a mechanism for
differentiating such superdense bodies.
London
