... If the mass of the collapsing star is more than three solar masses, however, no force can prevent it from collapsing completely to become a black hole. What is a black hole? Mini black holes . ... For Further Reading About Black Holes A black hole is a region of space in which the pull of gravity is so strong that nothing can escape. ... A black hole with a mass less than three solar masses would not form on its own; its gravity is too weak to cause it to completely collapse in on itself. ...