Black hole. Photograph illustrating the concept of a black hole. Any object with mass distorts spacetime in its locality, a phenomenon we know as gravity. All gravitational fields have an escape velocity (the velocity at which a body must move in order to escape from the gravitational field). A black hole is any region of spacetime which is so greatly curved (so much gravity) that the escape velocity is greater than the speed of light. As nothing travels faster than light, nothing may escape from the black hole. It is generally accepted that some black holes may be formed from the collapse of super-massive stars.