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A gravitational singularity occurs when an Astrophysical model, typically based on General Relativity , predicts some type of Pathological Behavior of Space-time , such as a point of Infinite space-time Curvature . In this point, everything will be infinitely deflected by an infinite gravitational well. A singularity has a finite mass but an infinitely small volume and infinitely large density. There is special distance, called the Schwarzschild Radius to a singularity at which nothing, not even light can escape. Within this radius, the gravitational escape velocity is greater than the speed of light, and nothing can travel faster than light. Therefore, at the Schwarzschild Radius, the escape velocity is exactly c, the speed of light. This radius varies depending on the mass of the singularity. The sphere defined by the Schwarzschild Radius is called the Event Horizon , because events which occur within the event horizon cannot be described by modern physics. The conditions for something to escape the gravitational pull of a singularity at exactly the Schwarzschild Radius are as follows:
The term is closely related to the . DISCUSSION The notion of singularities as points where space-time curvature reaches infinity is the one that is most intuitive. However, singularities can exist even if the curvature of space-time is finite everywhere. Not all geometries whose Metric Tensor blows up at some point must be actual geometric singularities; some of them are merely coordinate singularities and may be removed by a redefinition of coordinates. More generally, a space-time is considered singular if:
If these two conditions are met, it is said that singularities are located at the "points" where "incomplete" observers start and/or end their existence. The Big Bang Cosmological model of the Universe contains a gravitational singularity at the start of Time (''t''=0). At the "Big Bang Singularity," the model predicts that the density of the universe and the curvature of space-time are Paradoxically infinite. However, the basic Big Bang model does not include Quantum effects, so its predictions are valid only shortly after the projected singularity. A singularity also exists within a Black Hole , where general relativity predicts a region of infinite curvature. In a non-rotating black hole, the singularity occurs at a single point in the model coordinates, and is called a "point singularity". In a rotating black hole, the singularity occurs on a ring, and is called a " Ring Singularity ". Rotating black holes are sometimes referred to as Kerr Black Hole s. A singularity in a black hole is the theoretical representation of Matter becoming so compressed that it can have unlimited Density with no physical Volume . This type of singularity only occurs when a Neutron Star is so Massive that it is completely bent inwards upon itself due to its own gravitational forces. Until the early 1990s , it was widely believed that general relativity hides every singularity behind an Event Horizon , making Naked Singularities impossible. This is referred to as the Cosmic Censorship Hypothesis . However, in 1991 Shapiro and Teukolsky performed computer simulations of a rotating plane of dust which indicated that general relativity allows for naked singularities. What these objects would actually look like is unknown. Nor is it known if singularities would still arise if the simplifying assumptions used to make the simulation tractable were removed. The singularity is an object that challenges so many ideas in Physics (such as the idea of mass without volume) that it is described as unphysical (i.e. it cannot really exist under present assumptions about physical science). This does not mean that it does not exist, but it does mean that it would take a new view and a few new theories about Physics to change the current state belief. It is generally assumed that a theory of Quantum Gravity - a theory that unifies General Relativity with Quantum Mechanics - will provide a better description of what actually occurs where General Relativity predicts a singularity. However, As Of 2006 , no theory of Quantum Gravity has been experimentally confirmed, but there exists a handful of theories of Quantum Gravity (namely String Theory or M-theory ) that proposes the so-called " Theory Of Everything ". REFERENCES
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