http://www.physorg.com/news11202.html
Hitching a Ride Out of a Gluttonous Black Hole
Physics : February 25, 2006
“Ever since Stephen Hawking showed that black holes evaporate,” says
Seth Lloyd, an MIT physicist, “people have wondered about the stuff that
comes out of them. Is it just garbage, or is it something else?” With
his piece published in Physical Review Letters on February 14, Lloyd
attempts to show that quantum information does escape black holes, and
that this information is useful and can have lasting impacts on how we
understand our universe.
Lloyd’s assertion is that information escapes as black holes evaporate
in what is known as a final state projection model. Final projection is
nonlinear, but it is also considered self-consistent. “It’s funky,”
Lloyd explains to Physorg.com, “but it is self-consistent. Anything that
happens in a final state projection can ‘legally’ happen in a more
conventional quantum mechanical manner.”
Final state projection is far from commonly accepted, however. One of
the main problems some physicists have with these models is that in
order the information has to travel at faster-than-light speeds to
escape. While a final state projection model of black hole evaporation
preserves unitarity and can even explain entropy as microstates of black
hole horizon, getting past the idea of quantum information escaping at
such high speeds is difficult. The idea of final state projection and
escaping quantum information was put forth in the 1960s, but had been
pretty much shunted aside by the 1980s. Despite attempts by a few
physicists to substantiate the idea of faster-than-light quantum
information escape from black holes, many remain skeptical.
Even Lloyd concedes that quantum bits moving faster than light hard to
accept. “I admit that it’s strong medicine, things traveling faster than
the speed of light.” But he insists his calculations show that it is
possible. In a process similar to teleportation, quantum information
inside the black hole entangles itself with Hawking radiation. As the
black hole evaporates, the information is mostly preserved in the
radiation. In Lloyd’s letter, his calculations show that the escaping
quantum information has fidelity ? (8/3 ?)2 . This means that if Lloyd
is right, an average of half a bit of information is lost, no matter how
many bits escape the black hole.
Lloyd’s calculations show that it is possible, in a final state
projection scenario, for useful quantum information to escape a black
hole. This of itself is a remarkable discovery, considering that it is
commonly thought that nothing can escape a black hole, and that fairly
useless Hawking radiation is the only product of black hole evaporation.
Lloyd’s letter suggests that even the Hawking radiation has a use, as it
will carry the entangled bits of quantum information.
But it is the implications regarding a theory of quantum gravity that
Lloyd feels is especially significant. “We can understand quantum
gravity by looking at how things process quantum information, and one of
these things can be an evaporating black hole. This [letter] shows an
example of applying methods of quantum information about quantum gravity
and then getting something back.”
Not only does Lloyd believe that black holes can help physicists form a
theory of quantum gravity, but he also thinks that final state
projection shows how black holes can function as quantum computers. “It
becomes a matter of putting information into a hole. The hole processes
the information and spits it out through Hawking radiation.” Lloyd
pauses, then continues: “We don’t know how to program a black hole, but
maybe when we learn more about quantum gravity, we will be able to.”
Citation: Seth Lloyd. Almost Certain Escape from Black Holes in Final
State Projection Models, Phys. Rev. Lett. 96, 061302 (2006)
By Miranda Marquit, Copyright 2006 PhysOrg.com
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shove a wooden cross up their arses and rotate
at a high rate of speed. I trust you'll
be 'blessed' with a cornucopia of splinters.
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