) should be in order to form a black hole (Shipman 65). His equation became known the Schwarzschild radius, which shows to what critical radius a given mass should be compressed to become a black hole (Gribbin and White 77). In 1939, the United States physicists J. Robert Oppenheimer, Hartland S. Snyder and Volkoff showed that it is possible for massive stars to collapse and form black holes (Bunn and Shipman 65). In 1970s, the British scientist Steven Hawking developed a theory that black holes are not completely black (Bunn). Hawking noticed that black holes comply with the second law of thermodynamics. The second law of thermodynamic says that the entropy of an isolated system always increases, and that when two systems are joined together, the entropy of the combined system is greater than the sum of the entropies of the individual systems (Ferris 229). It means that the area of event horizon increases whenever matter fell into a black hole. This was researched by student at Princeton named Jacob Bekenstein. Such a proposal was logical, but it had a flaw in complying with the second law of thermodynamics. If a body has entropy it also must have a temperature, which means that black holes should emit radiation. But how can black holes emit anything when by the definition nothing can escape from their gravitational pull? When Hawking was visiting Moscow in 1973 he had a chance to discuss black holes with two leading Soviet scientists Yakov Zeldovich and Alexander Starobinsky. They convinced Hawking that according to the quantum mechanical uncertainty principle, rotating black holes should create and emit particles (Ferris 230). Hawking decided to calculate how much radiation is emitted from rotating black holes. He found out from his calculations that even non - rotating black holes should emit radiation. However this radiation does not directly comes out of black hole itself. The answer lies in quantum mechanics theory, which tells t...
