193 research outputs found
Black holes in the quantum universe
A succinct summary is given of the problem of reconciling observation of
black hole-like objects with quantum mechanics. If quantum black holes behave
like subsystems, and also decay, their information must be transferred to their
environments. Interactions that accomplish this with `minimal' departure from a
standard description are parameterized. Possible sensitivity of gravitational
wave or very long baseline interferometric observations to these interactions
is briefly outlined.Comment: 11 pages + ref
Modulated Hawking radiation and a nonviolent channel for information release
Unitarization of black hole evaporation requires that quantum information
escapes a black hole; an important question is to identify the mechanism or
channel by which it does so. Accurate counting of black hole states via the
Bekenstein-Hawking entropy would indicate this information should be encoded in
radiation with average energy flux matching Hawking's. Information can be
encoded with no change in net flux via fine-grained modulation of the Hawking
radiation. In an approximate effective field theory description, couplings to
the stress tensor of the black hole atmosphere that depend on the internal
state of the black hole are a promising alternative for inducing such
modulation. These can be picturesquely thought of as due to state-dependent
metric fluctuations in the vicinity of the horizon. Such couplings offer the
prospect of emitting information without extra energy flux, and can be shown to
do so at linear order in the couplings, with motivation given for possible
extension of this result to higher orders. The potential advantages of such
couplings to the stress tensor thus extend beyond their universality, which is
helpful in addressing constraints from black hole mining.Comment: 10 pages of text + refs. v2: cleaner figure. v3: minor updates to
match published versio
Hawking radiation, the Stefan-Boltzmann law, and unitarization
Where does Hawking radiation originate? A common picture is that it arises
from excitations very near or at the horizon, and this viewpoint has supported
the "firewall" argument and arguments for a key role for the UV-dependent
entanglement entropy in describing the quantum mechanics of black holes.
However, closer investigation of both the total emission rate and the stress
tensor of Hawking radiation supports the statement that its source is a
near-horizon quantum region, or "atmosphere," whose radial extent is set by the
horizon radius scale. This is potentially important, since Hawking radiation
needs to be modified to restore unitarity, and a natural assumption is that the
scales relevant to such modifications are comparable to those governing the
Hawking radiation. Moreover, related discussion suggests a resolution to
questions regarding extra energy flux in "nonviolent" scenarios, that does not
spoil black hole thermodynamics as governed by the Bekenstein-Hawking entropy.Comment: 7 pages + references. v2: references added, v3: minor typos
corrected. To appear in Physics Letter
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