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Because of [[quantum mechanics|quantum-mechanical]] phenomena involving Hawking Radiation, discussed later in the article, black holes must emit radiation and thus are a logical contradiction at the microscopic level.

Because of [[quantum mechanics|quantum-mechanical]] phenomena involving Hawking Radiation, discussed later in the article, black holes must emit radiation and thus are a logical contradiction at the microscopic level.

Black holes have never been directly observed, and there is no direct evidence for their existence.  Even believers in black holes should admit that there are far fewer than predicted by theory, and they lose credibility when they fail to address that undisputed truth.  They will cite evidence of observations of radiation from accretion disks, motion of stars near the center of the galaxy, and "gravitational lensing", having all the properties that relativity predicts, around places where there are no visible objects.  Like positrons, their existence was predicted (in both cases based on relativity) before there was any actual evidence of their existence.

Black holes have never been directly observed, and there is no direct evidence for their existence.  Even believers in black holes should admit that there are far fewer than predicted by theory, and they lose credibility when they fail to address that undisputed truth.  They will cite evidence of observations of radiation from accretion disks, motion of stars near the center of the galaxy, and "gravitational lensing", around places where there are no visible objects.  But at most the evidence for the existence of black holes is circumstantial, with heavy reliance on speculation.

Black holes 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 does not lie inside that radius.

Black holes 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 does not lie inside that radius.