The idea of black holes was first developed in the late eighteenth century by English geologist John Michell and French astronomer Pierre Simon Laplace. In 1783, Michell calculated the speed at which an object would have to travel in order to escape the gravity of the Sun. In 1796, Laplace conducted a similar study. The two scientists agreed that if a star was big enough and dense enough, it would exhibit so much gravitational attraction that nothing could escape from its clutches. Scientists once called black holes "gravitationally collapsed objects." Russian scientists suggested the name "collapsar." Then in 1969, physicist John A. Wheeler of Princeton University coined the term "black hole," which became instantly popular. The discovery of quasars lent support to the theory of black holes. Quasars are small and extremely distant objects that emit tremendous quantities of radiation, including visible light and X-rays. Mathematician Roy Kerr concluded, in the mid-1960s, that black holes could be the source of the quasars. The radiation emission could be the result of huge quantities of matter crossing the event horizon and disappearing into a black hole. Stephen Hawking, professor of mathematics at Cambridge University, has added much in recent years to our understanding of black holes.
