A gravitational singularity ( sometimes called a spacetime singularity ) is a place in a black hole where the gravity is thought to be infinite . While in a non-rotating black hole the singularity occurs at a single point in the model coordinates , called a `` point singularity '' . In a rotating black hole , also known as a Kerr black hole , the singularity occurs on a ring ( a circular line ) , defined as a `` ring singularity '' .