From: jos.bergervoet@xs4all.nl   
      
   After the merger of two black holes there is a "ringdown" in which the   
   new black hole radiates off some energy.   
      
   Presumably this ringdown amplitude decays exponentially, so it never   
   becomes exactly zero. We can also easily imagine (although not easily   
   test experimentally) the reverse: some incoming gravitational radiation   
   which is nicely focussed on an existing balck hole makes it "ring up"   
   instead of ring down..   
      
   But if a black hole can have vibration amplitudes, for lots of spherical   
   harmonics as it seems, doesn't that violate the no-hair theorem?   
      
   --   
   Jos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)