Word: einsteins
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...Even through the most powerful telescope, no one has seen?or ever will see?black holes. Thus, for the time being at least, these inkblots of space are mere mathematical figments. So far, they can be shown to exist only as solutions to the complex equations of general relativity?Einstein's theory of gravity?and very troubling
...Einstein's theory is correct, black holes are the natural consequences of the death of giant stars. In what astronomers call catastrophic gravitational collapse, most of the matter contained in such a dying star begins falling in toward the stellar center. If the conditions are right, the matter crushes together with such enormous force that it literally compresses itself out of existence. The star becomes what mathematicians call a "singularity." Its matter is squeezed into an infinitesimally small volume, and it simultaneously becomes infinitely dense and has an infinitely high gravitational force. At the point of singularity, time and space...
When they are confronted with such a situation, scientists are often inclined to toss out the suspect equations, along with the physical theories underlying them. Yet general relativity has withstood many other tests since it was devised by Einstein more than half a century ago, and more and more scientists believe that the evidence in the skies is rapidly piling up in favor of the reality of black holes...
...shortly after Einstein formulated his theory, a German colleague named Karl Schwarzschild considered one of general relativity's consequences. If a star were to become sufficiently compact and dense, Schwarzschild found, its gravity would so warp space and time around it that the star would literally enclose itself. For a celestial body of the sun's mass, the critical radius turned out to be about 3 km (2 miles). If the star shrunk beyond that, it would vanish. This so-called Schwarzschild radius, or event horizon, is in effect the black hole's boundary. Any matter crossing it simply disappears...
...Using Einstein's equations, astronomers determined that after all of the nuclear fuel is consumed, gravity eventually would cause the star to contract into a white dwarf, a sphere only about as big as the earth but so dense that each cubic centimeter would weigh a ton. Their calculations finally made sense of a dim companion of the star Sirius that was first observed in the 1860s and had puzzled astronomers for decades. Though the star was apparently small, it exerted an inexplicably great gravitational pull on Sirius. The dense little companion?like others that have been observed since?...