Sign of the times I guess , maybe the only comment .
  All too wrapped up in our tiny worlds , the USA is good at that too:-) . 
Yes AE was ahead of his time , in hindsight all seems so obvious . 
  2 Galaxies collide , 2 black holes go into a toxic embrace , makes a super nova look like a small cracker . 
  So there is fallout :-) 
And unless the particles hit something , they just carry on I guess ? Or pass through planets etc . ?
And now we have found a few .
Why only from a black hole colliding from another ? 
  How do we know they are from a black hole , how to tell the difference ?