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So clearly our
laws of physics are breaking down. I already said this happens at the center
of a black hole, so why is this more of a problem? As long as the "tear
in the fabric of spacetime" was hidden below the event horizon of a
black hole, it did not ruin the predictability of things that went on
outside. However, now we have a breakdown of predictibility, a loss of
information, that essentially affects the rest of the universe. Moreover, the
problem is not occurring at absurdly high temperatures and pressures that
exist at the center of the black hole. Its source is just outside the
horizon, and has to do with the interplay between macroscopic physics, and
the microscopic processes that cause the evaporation. Thus the laws of
physics are breaking down a lot sooner than we had any right to expect. To
resolve this problem we have to understand this evaporation process, and
ultimately, we need to understand how gravity and quantum mechanics are to be
unified into a single theory. The strange behaviour of black holes is
providing us with value clues that will ultimately lead us to the Holy Grail
of theoretical physics: a correct and consistent unification of gravity with
the other interactions. The currently popular candidates for such a theory
are string theory and loop quantum gravity. Both theories are based on
similar fundamental geometrical objects, namely one dimensional loops or
strings, but the technical details are quite different.
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