Black Hole Puts Dent In Space-time

http://www.space.com/1976-black-hole-puts-dent-space-time.html

A spinning black hole in the constellation Scorpius has created a stable dent in the fabric of spacetime, scientists say.
The dent is the sort of thing predicted by Albert Einstein's theory of general relativity. It affects the movement of matter falling into the black hole.
The spacetime-dent is invisible, but scientists deduced its existence after detecting two X-ray frequencies from the black hole that were identical to emissions noted nine years ago. The finding will allow scientists to calculate the black hole's spin, a crucial measurement necessary for describing the object's behavior.

   Scientists think that all spinning black holes emit two stable frequencies, and that the frequencies are closely tied to the black hole's mass and spin.