e to become neutron stars (dense stars made up almost entirely of neutrons). Scientists aresure that neutron stars form by collapse. They suspect that a black hole will form in the same way if a stars burned out core contains at least three times the mass of the sun.The idea of a black hole is based on physicist Albert Einsteins theory of gravitation, known as general relativity. Einsteins theory predicts that a black hole formed by the collapse of a star about 100,000 times smaller than the sun and almost featureless. Therefore, it would make it extremely difficult to pinpoint a black hole.(World Book)*** Astronomers believed that black holes could only be an intermediate step towardthe completion of spherical gravitational collapse or a disappearance in what theastronomers call a singularity. The singularity is a region of space-time where infinitelyintense gravitational forces deform matter and photons beyond recognition and, as the radius of a sphere shrinks to a point of zero dimension and the volume goes to zero, matter and energy are squeezed out of existence. The singularity, to some scientists, is natures way of saying that the present physical laws we are using are notadequate to cope with the situation-perhaps we have missed the proper application of some existing laws or, in the extreme, because new laws are needed. Other scientistsare just as certain that once we have a black hole, the singularity is ruled out; theyindicate that as it takes an infinite time to reach the gravitational radius and as the universe spans a finite time, the black hole simply does not have enough time to go to a singularity. Perhaps an example will serve to illustrate what happens in space-time that could give rise to a singularity. Picture a thin sheet of rubber stretched over a largeframe, and let us assume that this rubber represents a corner of the universe. If wetake a ball and place it in the middle of the sheet, the ball will...
