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[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole (upper left) and a main sequence star (lower right).  The black hole is drawing matter from the star via an ''accretion disk'' (blue) around it, and some of this matter forms a gas jet (also blue).]]

[[Image:Iu8969hu.jpg|right|thumb|300px|Artist's conception of a binary system consisting of a black hole (upper left) and a main sequence star (lower right).  The black hole is drawing matter from the star via an ''accretion disk'' (blue) around it, and some of this matter forms a gas jet (also blue).]]

A '''black hole''' is a theoretical formation in space with near-[[infinity|infinite]] density and sufficient gravitational force that escape velocity exceeds the speed of light. Thus, "black" refers to the impossibility of any light ([[photon]]s) escaping, thereby making them completely dark.<ref>They are assumed to come into existence from extremely large stars that collapse into a state of high density when they run out of fusion fuel.  An object becomes a black hole when it lies entirely inside the Schwarzschild radius (see below) determined by its mass.  For most objects, the Schwarzschild radius is very tiny compared with its size (for Earth it is about 1 centimeter), so the object could not lie inside that radius.</ref>

A '''black hole''' is an object that lies entirely inside the Schwarzschild radius arising from its own gravity.  This requires enormous density&mdash;far higher than occurs in ordinary matter.  The idea of a black hole arose in 1916, almost immediately after the formulation of [[general relativity]], though the term only came into existence much later.  No one, Einstein or anyone else, believed such a thing could actually exist.  It wasn't until the latter half of the 20^th century that knowledge of fundamental physics had reached the point that black holes were considered possible.  They have since been "observed" many times.

 

A black hole has near-[[infinity|infinite]] density, and sufficient gravitational force, that escape velocity exceeds the speed of light. Thus, "black" refers to the impossibility of any light ([[photon]]s) escaping, thereby making them completely dark.<ref>They are assumed to come into existence from extremely large stars that collapse into a state of high density when they run out of fusion fuel.  An object becomes a black hole when it lies entirely inside the Schwarzschild radius (see below) determined by its mass.  For most objects, the Schwarzschild radius is very tiny compared with its size (for Earth it is about 1 centimeter), so the object could not lie inside that radius.</ref>

Black holes are increasingly promoted by [[liberal]] publications, such as the science page of the ''[[New York Times]]'', glossy magazines, and movies including ''Event Horizon'' (1997), ''The Black Hole'' (TV, 2006), and ''Interstellar'' (2014). Black holes fail the [[falsifiability]] requirement of science, because it is impossible to prove that they do not exist anywhere in the universe.

Black holes are increasingly promoted by [[liberal]] publications, such as the science page of the ''[[New York Times]]'', glossy magazines, and movies including ''Event Horizon'' (1997), ''The Black Hole'' (TV, 2006), and ''Interstellar'' (2014). Black holes fail the [[falsifiability]] requirement of science, because it is impossible to prove that they do not exist anywhere in the universe.

==Are Black Holes Falsifiable?==

==Are Black Holes Falsifiable?==

''Things'' cannot be judged [[falsifiable]] or non-falsifiable.  The concept of being falsifiable only applies to theories or hypotheses.  One can't say the unicorns are falsifiable, but the hypothesis "there are no unicorns" is.  The imagined experiment would consist of finding a unicorn.  If one were found, the hypothesis would be refuted.  None has ever been found, but that's not germane to the question of falsifiability.  Similarly, the hypothesis "there are no black holes" is falsifiable.  The test would be to find one.  (Many have been found, perhaps the most notable being the ones involved in the discovery of [[gravitational waves]].)

''Things'' cannot be judged [[falsifiable]] or non-falsifiable.  The concept of being falsifiable only applies to theories or hypotheses.  One can't say that unicorns are falsifiable, but the hypothesis "there are no unicorns" is.  The imagined experiment would consist of finding a unicorn.  If one were found, the hypothesis would be refuted.  None has ever been found, but that's not germane to the question of falsifiability.  Similarly, the hypothesis "there are no black holes" is falsifiable.  The test would be to find one.  (Many have been found, perhaps the most notable being the ones involved in the discovery of [[gravitational waves]].)

==See also==

==See also==