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Q:
The temperature of a black hole is only a fraction of a degree above
absolute zero. How is this possible when the black hole ingests
everything
within its grasp ? What happens to the matter and energy captured by the
black hole ?
A:
The temperature of an object in thermal equilibrium is related to the
rate at
which object radiates energy divided by its area. As shown by Stephen
Hawking and others, this relation can be applied to black holes if the
area is
taken to be the surface area described by the event horizon. The energy
radiated by a black hole is for all practical purposes zero, so the
temperature is very close to zero. An extremely small amount of energy is
radiated by the Hawking process, but this is negligible for a stellar mass
black hole or larger.
The matter and energy captured by a black hole is trapped there forever, and
the mass of the black hole increases.
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