8,859 research outputs found
Virtual Black Holes
One would expect spacetime to have a foam-like structure on the Planck scale
with a very high topology. If spacetime is simply connected (which is assumed
in this paper), the non-trivial homology occurs in dimension two, and spacetime
can be regarded as being essentially the topological sum of and
bubbles. Comparison with the instantons for pair creation of black holes
shows that the bubbles can be interpreted as closed loops of
virtual black holes. It is shown that scattering in such topological
fluctuations leads to loss of quantum coherence, or in other words, to a
superscattering matrix that does not factorise into an matrix and its
adjoint. This loss of quantum coherence is very small at low energies for
everything except scalar fields, leading to the prediction that we may never
observe the Higgs particle. Another possible observational consequence may be
that the angle of QCD is zero without having to invoke the
problematical existence of a light axion. The picture of virtual black holes
given here also suggests that macroscopic black holes will evaporate down to
the Planck size and then disappear in the sea of virtual black holes.Comment: 24p, LaTeX, 3 postscript figures included with epsf sent in a
seperate uuencoded fil
No-Go Theorem in Spacetimes with Two Commuting Spacelike Killing Vectors
Four-dimensional Riemannian spacetimes with two commuting spacelike Killing
vectors are studied in Einstein's theory of gravity, and found that no outer
apparent horizons exist, provided that the dominant energy condition holds.Comment: latex, 1 figure, version published in Gen. Relativ. Grav., 37,
1919-1926 (2005
Comment on "The black hole final state"
Horowitz and Maldacena have suggested that the unitarity of the black hole
S-matrix can be reconciled with Hawking's semiclassical arguments if a
final-state boundary condition is imposed at the spacelike singularity inside
the black hole. We point out that, in this scenario, departures from unitarity
can arise due to interactions between the collapsing body and the infalling
Hawking radiation inside the event horizon. The amount of information lost when
a black hole evaporates depends on the extent to which these interactions are
entangling.Comment: 4 pages, REVTe
Entropy in the RST Model
The RST Model is given boundary term and Z-field so that it is well-posed and
local. The Euclidean method is described for general theory and used to
calculate the RST intrinsic entropy. The evolution of this entropy for the
shockwave solutions is found and obeys a second law.Comment: 10 pages, minor revisions, published version in Late
Pair Creation of Black Hole in Anti-de Sitter Space Background
In the absence of a general no-boundary proposal for open creation, the
complex constrained instanton is used as the seed for the open pair creations
of black holes in the Kerr-Newman-anti-de Sitter family. The relative
probability of the chargeless and nonrotating black hole pair is the
exponential of the negative of the entropy, and that of the charged and (or)
rotating black hole pair is the exponential of the negative of one quarter of
the sum of the outer and inner black hole horizon areas
Possible quantum instability of primordial black holes
Evidence for the possible existence of a quantum process opposite to the
famous Hawking radiation (evaporation) of black holes is presented. This new
phenomenon could be very relevant in the case of exotic multiple horizon Nariai
black holes and in the context of common grand unified theories. This is
clearly manifested in the case of the SO(10) GUT, that is here investigated in
detail. The remarkable result is obtained, that anti-evaporation can occur
there only in the SUSY version of the theory. It is thus concluded that the
existence of primordial black holes in the present Universe might be considered
as an evidence for supersymmetry.Comment: LaTeX, 7 pages, version to appear in PRD Rapid Communication
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