Stars so massive that gravity attracts and holds everything in the vicinity, including light; if no light can escape, they appear black. Their possible existence is suggested by relativity theory applied to cosmology. The argument runs: If a massive star, with its high gravity, continues to mop up surrounding matter, it will eventually become so large that its gravity will prevent anything from escaping. Relativity predicts that light is also affected by gravity. There has been experimental confirmation of this: Light from a star passing close to a planet is deflected slightly by gravitational attraction. Light too will be unable to escape from so large a star; we would be unable to see it either by emitted or reflected light. It would be a perfect absorber, a perfect “black body,” totally invisible and only detectable if at all by its tendency to absorb any matter approaching. Such an object is known as a black hole. It is a theoretical construct, a hypothesis; there is no direct evidence of one’s existence.
Such ideas that violate common sense, particularly when accepted by the scientific community, inevitably attract even stranger associations. For example, the theoretical physicist John Taylor in his book on the subject Black Holes (1973), after explaining the theory in some detail, goes on into flights of the imagination. He imagines black-hole energy driving spaceships. He sees beings, sucked into black holes, exiting into an alternative universe. Perhaps souls could travel via black holes into another existence a sort of reincarnation. Several other writers have joined in these speculations and added more: white holes as the complement of black holes; the two joined by a wormhole matter going in the black, through the wormhole, and out of the white (as antimatter) and so on.