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Escape velocity from the surface at radius R is
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At small enough R
we have VEscape= c (speed of light)
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That R is by definition the Schwarzschild radius
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Far from the black hole gravity is the same as for
any ordinary mass M
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Stars will just orbit around it like any other mass
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Gas orbiting it collides, tries
to slow down, (just like reentering satellite)
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As gas falls inward it ends up speeding up and
heating up
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Gas will be moving at close to speed of light by the
time it reaches RS
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Light emitted by hot gas just outside RS
can still escape
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Provides a way to release about 10% of E=mc2 of energy
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Fusion releases only about 1%
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Signature of black hole:
Very high energy release, very high velocity
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