Black Holes
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Black holes, sometimes called "collapsars," are a class of astronomical object which has attracted great attention both from astrophysicists and the general public in the past two decades. According to theory, if an astronomical body is large or dense enough, its gravitational escape velocity will exceed the velocity of light: thus no radiation from it can escape to the outside Universe. It disappears within an "event horizon." Such an object, from which not even light can escape, would seem to be undetectable, yet black holes are of great interest to astronomers and physicists. A number of indirect methods of detecting black holes have been proposed, and indeed a number of black hole "candidates" have been identified. However, black holes remain a theoretical construct, since no persuasive indirect observational evidence has been found that would rule out alternative explanations for these "candidate" objects (1: 321-23). In the body of this study, the conditions under which black holes could form will be outlined, possible classes of black holes surveyed, and the current state of observation reviewed. The general concept behind black holes is a surprisingly old one. In 1796, the French mathematician Pierre Simon, better known as the Marquis de Laplace, applied Newton's theory of gravitation to the problem of light, which was already known to have a finite velocity. Laplace argued that if a star were large enough, or dense enough, to have a surface escape velocity g
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right? One possibility was "superstars"--starlike objects thousands of times more massive than the largest ordinary stars. Closer theoretical examination, however, ruled out such superstars as the sources of quasars (1: 299-300). Dense star-clusters, wracked by near-continuous stellar collisions or "chain-reaction" supernovae were also considered, but they also pose severe theoretical difficulties (1: 302-304).
An alternative explanation, now the most popular one, is that quasars are produced by immense black holes, with a mass millions or billions of times greater than that of the sun. The event horizon of such a massive black hole would, indeed, be about the right size to "fit" the observed behavior of quasars. Moreover, extremely massive and compact objects, perhaps "burnedout" quasars, are known to exist in many galaxies, perhaps including our own.
This may seem paradoxical. How could black holes, from which no light whatsoever can escape, be the power source for the brightest objects in the Universe? The answer is that when a black hole is that the event horizon works only in one direction. As with the Roach Motel, nothing can check out of a black hole -but any matter caught in its gravitational field can check in
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Some common words found in the essay are:
Roach Motel, Magellanic Cloud, , Solar System, Bang Universe, Hartland Snyder, Stephen Hawking, Simon Marquis, Hubble Telescope, Karl Schwartzschild, black holes, black hole, event horizon, velocity light, escape velocity, accretion disk, neutron star, black holes remain, magellanic cloud, black hole's, hole's event, black hole's event, black holes proposed, indeed black hole, detecting black holes,
Approximate Word count = 2014
Approximate Pages = 8 (250 words per page)
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