The radius of the event horizon of a black hole. At the Schwarzschild radius the escape velocity becomes equal to the speed of light. The more massive the black hole, the larger the Schwarzschild radius. For a body of mass M the Schwarzschild radius is 2GM/c2, where G is the gravitational constant and c is the speed of light. It was first calculated in 1916 by K. Schwarzschild.
Subjects: Astronomy and Astrophysics — Physics.