Black Holes:  Review
Escape velocity from the surface at radius R is
At small enough R  we have VEscape= c  (speed of light)
That R is by definition the Schwarzschild radius
Far from the black hole gravity is the same as for any ordinary mass M
Stars will just orbit around it like any other mass
Gas orbiting it collides, tries to slow down, (just like reentering satellite)
As gas falls inward it ends up speeding up and heating up
Gas will be moving at close to speed of light by the time it reaches RS
Light emitted by hot gas just outside RS can still escape
Provides a way to release about 10% of E=mc2 of energy
Fusion releases only about 1%
Signature of black hole:  Very high energy release, very high velocity