24 black holes hanging on the wall. And if one black hole should
accidentally fall--
< The holes exist in clusters, with the two most powerful in the
center of the galaxy orbiting at very high speed and affecting
each other like a double star, the Yomiuri Shimbun quoted
Oya as saying. >
Interestingly, this double black hole (on a rather more extravagant scale)
is a key speculation in Donald Moffitt's rather good and usually overlooked
sf novel SECOND GENESIS.
Damien Broderick