Black Hole

Just to add to what others have already defined as a black hole.... They say that the black holes could be the way out of this universe! (Ref. General Theory of Relativity)

A black hole is an object predicted by general relativity, with a gravitational field so powerful that even electromagnetic radiation (including light itself) cannot escape its pull. A black hole is defined to be a region of space-time where escape to the outside universe is impossible. The outer boundary of this region is called the event horizon. Nothing can move from inside the event horizon to the outside, even briefly, due to the extreme gravitational field existing within the region. For the same reason, observers outside the event horizon cannot see any events which may be happening within the event horizon; thus any energy being radiated or events happening within the region are forever unable to be seen or detected from outside. Within the black hole is a singularity, an anomalous point in space-time where all matter is infinitely dense and is infinitely compressed into nothingness. Theoretically, a black hole can be any size. Astrophysicists expect to find black holes with masses ranging between roughly the mass of the sun ("stellar-mass" black holes) to many millions of times the mass of the sun (supermassive black holes). The existence of black holes in the universe is well supported by astronomical observation, particularly from studying X-ray emission from X-ray binaries and active galactic nuclei. It has also been hypothesized that black holes radiate energy due to quantum mechanical effects known as Hawking radiation. SOURCE: WIKIPEDIA

Black Hole is a stage of star in which the star collapse under its own gravitational force until such a point that the escape velocity on the surface of the star becomes greater than the velocity of light.Here the singularity is achieved.Space & time cease to exist.