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What really happens inside astronomically realistic black
holes? In this talk I will review the physics of the interior structure
of classical black holes, and illustrate with real time general
relativistic visualizations. It is well known that, except for the
single case of the Schwarzschild solution, the vacuum solutions for the
interiors of black holes are inconsistent as endpoints of gravitational
collapse, because the cores of vacuum black holes are gravitationally
repulsive. Instead, black holes must contain matter. As first pointed
out by Poisson and Israel (1990), the key physical effect that changes
the interior structure of a black hole from the vacuum solution is "mass
inflation" near the inner horizon. Mass inflation seriously modifies the
geometry of a black hole inside the region where the inner horizon would
be in a vacuum black hole. Mass inflation is driven by a feedback effect
in which counter-streaming between ingoing and outgoing fluids generates
a large pressure, which generates a large gravitational force, which
accelerates the ingoing and outgoing fluids ever faster through each
other.? I argue that a generic result of the mass inflation instability
is to produce a relativistic plasma inward of the erstwhile inner horizon.
If you fall into a supermassive black hole, where the tidal forces are
relatively weak, chances are you will die by being vaporized by the
relativistic plasma before you are torn apart by tides.
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