The novel depicts a world where genetic selection for increased health, longevity and intelligence has become so widespread that the unmodified 'control normals' are a coddled, almost endangered minority. The control normals are preserved to maintain a backup of human stock in case the gene selection takes a wrong choice somewhere. The world has become an economic utopia; the "economic dividend" is so high that work has become optional -- a sort of welfare state for the upper middle class. The chief economic problem is in finding a way to use up the economic surplus: much goes into scientific research, but this has the side-effect of further increasing productivity a decade or three later, so long-term projects with no possible economic return are favoured (e.g. galactic astronomy).
But there's trouble: dissatisfied elements are fomenting revolution, and it's up to gun-totin' Hamilton Felix to stop them. Guns and duels are permitted (An armed society is a polite society.), except for the control normals, whose reflexes are so poor compared to current human stock that they'd be slaughtered in combat.
The region between the stationary limit and the event horizon is known as the ergosphere.
It touches the event horizon at the poles, and stretches out to a distance equal to the radius of the event horizon of a Schwarzchild hole of equal mass (5).
Once the object's angular momentum increased beyond it's mass, the event horizon of the hole would be moving in excess of the speed of light.