Black hole

Black hole, according to current astrophysical theory, the final stage of evolution for very massive stars following complete gravitational collapse. In theory, a star with a mass more than 3 times that of the sun could collapse to an indefinitely small size. The gravitational field of such an object would be so powerful that not even electromagnetic radiation (including visible light) could escape. Black holes, if they exist, would have to be detected by their gravitational effects on other bodies and by the emission of X- and gamma rays by objects falling into them. A black hole would therefore bear some resemblance to the initial state of the universe in the big bang theory.

See also: Astronomy; Star; Big bang.