[acecharly (OP)]

Any thoughts

Cheers Ace

[evan_au]

There are very few things you can tell about a black hole - one of them is its spin, which influences the shape of the event horizon, and causes frame dragging. http://en.wikipedia.org/wiki/Black_hole#Ergosphere

If you stopped a black hole from spinning, then this ergosphere would disappear.

You could think of casually:

• dropping in another black hole in a way which imparted equal and opposite angular momentum. This would cause some pretty impressive gravity waves.
• feeding in a few stars in the opposite direction to the black hole's current direction of rotation

I think for now, we should be content with just finding black holes with X-Ray telescopes...