The theory being that once these stars exhaust their supply of fuel, they begin to collapse inward with such tremendous force that even the powerful internuclear forces within the atoms of the star aren’t sufficient to prevent it from continuing to fall in on itself until the entire mass of the star is concentrated at a point called a singularity. Within the singularity, matter is infinitely compressed into a region of infinite density. At the singularity, gravity is infinite. Space-time has become infinitely curved (3). At the present time, science has no tools to describe conditions within the singularity. All laws of physics lose meaning in such a region. Schwarzschild’s work, however, does shed some light on conditions in the immediate vicinity of this cosmic forbidden zone.
As the star begins to contract, it’s mass becomes increasingly concentrated into an ever smaller region of space. The effects of gravity become increasingly pronounced. Soon, the gravity becomes so intense that a beam of light directed out into space will fall back to the ground, following the same parabolic path as an earthly projectile. At a point very near the end of the body’s existence as a star, light must be directed perpendicular to the ground in order for it to escape. When the collapsing star passes its Schwartzschild radius, it vanishes from view because its escape velocity has exceeded the speed of light. Since, according to Einstein’s work, nothing can travel faster than the speed of light, nothing, not even light itself, can escape from the star. It has become a black hole. The outer edge of the hole is called the event horizon, because no knowledge of events beyond it can ever be passed to the outside world.