825 research outputs found
The nonlinear evolution of de Sitter space instabilities
We investigate the quantum evolution of large black holes that nucleate
spontaneously in de Sitter space. By numerical computation in the s-wave and
one-loop approximations, we verify claims that such black holes can initially
"anti-evaporate" instead of shrink. We show, however, that this is a transitory
effect. It is followed by an evaporating phase, which we are able to trace
until the black holes are small enough to be treated as Schwarzschild. Under
generic perturbations, the nucleated geometry is shown to decay into a ring of
de Sitter regions connected by evaporating black holes. This confirms that de
Sitter space is globally unstable and fragments into disconnected daughter
universes.Comment: 10 pages, 8 figures, to appear in PR
(Anti-)Evaporation of Schwarzschild-de Sitter Black Holes
We study the quantum evolution of black holes immersed in a de Sitter
background space. For black holes whose size is comparable to that of the
cosmological horizon, this process differs significantly from the evaporation
of asymptotically flat black holes. Our model includes the one-loop effective
action in the s-wave and large N approximation. Black holes of the maximal mass
are in equilibrium. Unexpectedly, we find that nearly maximal quantum
Schwarzschild-de Sitter black holes anti-evaporate. However, there is a
different perturbative mode that leads to evaporation. We show that this mode
will always be excited when a pair of cosmological holes nucleates.Comment: 16 pages, LaTeX2e; submitted to Phys. Rev.
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
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
PeV-Scale Supersymmetry
Although supersymmetry has not been seen directly by experiment, there are
powerful physics reasons to suspect that it should be an ingredient of nature
and that superpartner masses should be somewhat near the weak scale. I present
an argument that if we dismiss our ordinary intuition of finetuning, and focus
entirely on more concrete physics issues, the PeV scale might be the best place
for supersymmetry. PeV-scale supersymmetry admits gauge coupling unification,
predicts a Higgs mass between 125 GeV and 155 GeV, and generally disallows
flavor changing neutral currents and CP violating effects in conflict with
current experiment. The PeV scale is motivated independently by dark matter and
neutrino mass considerations.Comment: 5 RevTex page
Inflation as a response to protect the Holographic Principle
A model where the inflationary phase emerges as a response to protect the
Fischler-Susskind holographic bound is described. A two fluid model in a closed
universe inflation picture is assumed, and a discussion on conditions under
which is possible to obtain an additional exponential expansion phase as those
currently observed is given.Comment: 6 pages, 2 figures. Accepted for publication in MPL
Correlation Classes on the Landscape: To What Extent is String Theory Predictive?
In light of recent discussions of the string landscape, it is essential to
understand the degree to which string theory is predictive. We argue that it is
unlikely that the landscape as a whole will exhibit unique correlations amongst
low-energy observables, but rather that different regions of the landscape will
exhibit different overlapping sets of correlations. We then provide a
statistical method for quantifying this degree of predictivity, and for
extracting statistical information concerning the relative sizes and overlaps
of the regions corresponding to these different correlation classes. Our method
is robust and requires no prior knowledge of landscape properties, and can be
applied to the landscape as a whole as well as to any relevant subset.Comment: 14 pages, LaTeX, 5 figure
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
Open inflation from non-singular instantons: Wrapping the universe with a membrane
The four-form field recently considered by Hawking and Turok couples
naturally to a charged membrane, across which the effective cosmological
constant has a discontinuity. We present instantons for the creation of an open
inflationary universe surrounded by a membrane. They can also be used to
describe the nucleation of a membrane on a pre-existing inflationary
background. This process typically decreases the value of the effective
cosmological constant and may lead to a novel scenario of eternal inflation.
Moreover, by coupling the inflaton field to the membrane, the troublesome
singularities which arise in the Hawking-Turok model can be eliminated.Comment: 23 pages, LaTeX2e, 4 figure
Three Dimensional de Sitter Gravity and the Correspondence
Certain aspects of three dimensional asymptotically de Sitter spaces are
studied, with emphasis on the mapping between gravity observables and the
representation of the conformal symmetry of the boundary. In particular, we
show that non-real conformal weights for the boundary theory correspond to
space-times that have non-zero angular momentum. Some miscellaneous results on
the role of the holonomies and isometry groups are also presented.Comment: 10 pages, 1 figure, uses epsf. Added references and a discussion on
the (dis)similarities with previous work
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