1,212 research outputs found
Quantum generation of Schwarzschild-de Sitter (Nariai) black holes in effective dilaton-Maxwell gravity
Dilaton coupled electromagnetic field is essential element of low-energy
string effective action or it may be considered as result of spherical
compactification of Maxwell theory in higher dimensions. The large and
large curvature effective action for dilaton coupled vectors is calculated.
Adding such quantum correction to classical dilaton gravity action we show that
effective dilaton-Maxwell gravity under consideration may generate
Schwarzschild-de Sitter black holes (SdS BHs) with constant dilaton as
solutions of the theory. That suggests a mechanism (alternative to BHs
production) for quantum generation of SdS BHs in early universe (actually, for
quantum creation of inflationary Universe) due to back-reaction of dilaton
coupled matter. The possibility of proliferation of anti-de Sitter space is
briefly discussed.Comment: LaTeX file, 11 page
Flat space physics from holography
We point out that aspects of quantum mechanics can be derived from the
holographic principle, using only a perturbative limit of classical general
relativity. In flat space, the covariant entropy bound reduces to the
Bekenstein bound. The latter does not contain Newton's constant and cannot
operate via gravitational backreaction. Instead, it is protected by - and in
this sense, predicts - the Heisenberg uncertainty principle.Comment: 11 pages, 3 figures; v2: minor correction
Can Quantum-Corrected BTZ Black Hole Anti-Evaporate?
Kaluza-Klein reduction of 3D gravity with minimal scalars leads to 2D
dilaton-Maxwell gravity with dilaton coupled scalars. Evaluating the one-loop
effective action for dilaton coupled scalars in large and s-wave
approximation we apply it to study quantum evolution of BTZ black hole. It is
shown that quantum-corrected BTZ BH may evaporate or else anti-evaporate
similarly to 4D Nariai BH as is observed by Bousso and Hawking. Instable higher
modes in the spectrum indicate also the possibility of proliferation of BTZ BH.Comment: LaTeX file and ps file of figure
Holographic Domains of Anti-de Sitter Space
An AdS_4 brane embedded in AdS_5 exhibits the novel feature that a
four-dimensional graviton is localized near the brane, but the majority of the
infinite bulk away from the brane where the warp factor diverges does not see
four-dimensional gravity. A naive application of the holographic principle from
the point of view of the four-dimensional observer would lead to a paradox; a
global holographic mapping would require infinite entropy density. In this
paper, we show that this paradox is resolved by the proper covariant
formulation of the holographic principle. This is the first explicit example of
a time-independent metric for which the spacelike formulation of the
holographic principle is manifestly inadequate. Further confirmation of the
correctness of this approach is that light-rays leaving the brane intersect at
the location where we expect four-dimensional gravity to no longer dominate. We
also present a simple method of locating CFT excitations dual to a particle in
the bulk. We find that the holographic image on the brane moves off to infinity
precisely when the particle exits the brane's holographic domain. Our analysis
yields an improved understanding of the physics of the AdS_4/AdS_5 model.Comment: 29 pages, 6 figure
Quantum Global Structure of de Sitter Space
I study the global structure of de Sitter space in the semi-classical and
one-loop approximations to quantum gravity. The creation and evaporation of
neutral black holes causes the fragmentation of de Sitter space into
disconnected daughter universes. If the black holes are stabilized by a charge,
I find that the decay leads to a necklace of de Sitter universes (`beads')
joined by near-extremal black hole throats. For sufficient charge, more and
more beads keep forming on the necklace, so that an unbounded number of
universes will be produced. In any case, future infinity will not be connected.
This may have implications for a holographic description of quantum gravity in
de Sitter space.Comment: 37 pages, LaTeX2e, 10 figures. v2: references adde
A covariant entropy conjecture on cosmological dynamical horizon
We here propose a covariant entropy conjecture on cosmological dynamical
horizon. After the formulation of our conjecture, we test its validity in
adiabatically expanding universes with open, flat and closed spatial geometry,
where our conjecture can also be viewed as a cosmological version of the
generalized second law of thermodynamics in some sense.Comment: JHEP style, 9 pages, 1 figure, typos corrected, accepted for
publication in JHE
Proliferation of de Sitter Space
I show that de Sitter space disintegrates into an infinite number of copies
of itself. This occurs iteratively through a quantum process involving two
types of topology change. First a handle is created semiclassically, on which
multiple black hole horizons form. Then the black holes evaporate and
disappear, splitting the spatial hypersurfaces into large parts. Applied to
cosmology, this process leads to the production of a large or infinite number
of universes in most models of inflation and yields a new picture of global
structure.Comment: 19 pages, LaTeX2e, 4 figure
Holographic entropy bound from gravitational Fock space truncation
A simplified derivation of Yurtsever's result, which states that the entropy
of a truncated bosonic Fock space is given by a holographic bound when the
energy of the Fock states is constrained gravitationally, is given for
asymptotically flat spacetimes with arbitrary dimension d greater or equal to
four. For this purpose, a scalar field confined to a spherical volume in
d-dimensional spacetime is considered. Imposing an upper bound on the total
energy of the corresponding Fock states which ensures that the system is in a
stable configuration against gravitational collapse and imposing a cutoff on
the maximum energy of the field modes of the order of the Planck energy leads
to an entropy bound of holographic type. A simple derivation of the entropy
bound is also given for the fermionic case.Comment: 5 pages, Latex (incl. style file), minor typos correcte
The CMB and the measure of the multiverse
In the context of eternal inflation, cosmological predictions depend on the
choice of measure to regulate the diverging spacetime volume. The spectrum of
inflationary perturbations is no exception, as we demonstrate by comparing the
predictions of the fat geodesic and causal patch measures. To highlight the
effect of the measure---as opposed to any effects related to a possible
landscape of vacua---we take the cosmological model, including the model of
inflation, to be fixed. We also condition on the average CMB temperature
accompanying the measurement. Both measures predict a 1-point expectation value
for the gauge-invariant Newtonian potential, which takes the form of a
(scale-dependent) monopole, in addition to a related contribution to the
3-point correlation function, with the detailed form of these quantities
differing between the measures. However, for both measures both effects are
well within cosmic variance. Our results make clear the theoretical relevance
of the measure, and at the same time validate the standard inflationary
predictions in the context of eternal inflation.Comment: 28 pages; v2: reference added, some clarification
Thermodynamics of Schwarzschild-(Anti-)de Sitter Black Holes with account of quantum corrections
We discuss the quantum corrections to thermodynamics (and geometry) of S(A)dS
BHs using large one-loop anomaly induced effective action for dilaton
coupled matter (scalars and spinors). It is found the temperature, mass and
entropy with account of quantum effects for multiply horizon SdS BH and SAdS BH
what also gives the corresponding expressions for their limits: Schwarzschild
and de Sitter spaces. In the last case one can talk about quantum correction to
entropy of expanding Universe.
The anomaly induced action under discussion corresponds to 4d formulation
(s-wave approximation, 4d quantum matter is minimal one) as well as 2d
formulation (complete effective action, 2d quantum matter is dilaton coupled
one). Hence, most of results are given for the same gravitational background
with interpretation as 4d quantum corrected BH or 2d quantum corrected
dilatonic BH. Quantum aspects of thermodynamics of 4d 't Hooft BH model are
also considered.Comment: LaTeX file, 28 pages, some misprints are correcte
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