In an environmental sense, the black holes are actually preventing galactic sprawl from taking over the neighborhood.

We already knew that powerful quasars are very efficient at making light. Now we know that black holes in elliptical galaxies are efficient as well. This suggests that being green is a trait that all black holes may have in common.

There are no black holes in the sense of regimes from which light can't escape to infinity.

A black hole is simply the end of space as we know it!

Black holes can bang against space-time as mallets on a drum and have a very characteristic song.

We don't want this to be used for sprawl.