Black holes :: essays research papers

black hole,in astronomy, airy object of such passing intense gravity that it attracts everything near it and in some instances prevents everything, including hang, from escaping. The term was prime(prenominal) used in reference to a hero in the uttermost(a) phases of gravitational fail (the final stage in the life tale of certain stars see stellar evolution), by the American physicist John A. Wheeler. gravitational collapse begins when a star has depleted its steady sources of nuclear zilch and can no longer produce the expansive force, a progeny of normal gas pressure, that supports the star against the compressive force of its own gravitation. As the star shrinks in surface (and increases in density), it may assume one of some(prenominal) manikins depending upon its mass. A less massive star may release a white dwarf, while a to a greater extent massive one would become a supernova. If the mass is less than three times that of the sun, it will form a neutron star. Ho wever, if the final mass of the remaining stellar core is more than three solar masses, as shown by the American physicists J. Robert Oppenheimer and Hartland S. Snyder in 1939, null remains to prevent the star from collapsing without limit to an indefinitely small size and infinitely large density, a point called the " trace.At the point of singularity the effects of Einsteins general theory of relativity become paramount. According to this theory, home becomes curved in the vicinity of matter the greater the concentration of matter, the greater the curvature. When the star (or supernova remnant) shrinks below a certain size determined by its mass, the extreme curvature of space seals off contact with the outside world. The appear beyond which no radiation can escape is called the event horizon, and its gas constant is called the Schwarzschild radius after the German astronomer Karl Schwarzschild, who in 1916 postulated the existence of collapsed celestial objects that emit no radiation. For a star with a mass liken to that of the sun, this limit is a radius of only 0.9 mi (1.5 km). Even light cannot escape the black hole but is turned back by the enormous pull of gravitation.It is now believed that the origin of some black holes is nonstellar. whatever astrophysicists suggest that immense volumes of interstellar matter can collect and collapse into supermassive black holes, such as are found at the mall of some galaxies.