title: Nonlinear parametric quantization of gravity and cosmological models

abstract:
  A generalization of the recently formulated nonlinear quantization of a
parameterized theory is presented in the context of quantum gravity. The
parametric quantization of a Friedmann universe with a massless scalar field is
then considered in terms of analytic solutions of the resulting evolution
equations.


title:
Gauge Problem in the Gravitational Self-Force II. First Post Newtonian
  Force under Regge-Wheeler Gauge

abstract:
  We discuss the gravitational self-force on a particle in a black hole
space-time. For a point particle, the full (bare) self-force diverges. It is
known that the metric perturbation induced by a particle can be divided into
two parts, the direct part (or the S part) and the tail part (or the R part),
in the harmonic gauge, and the regularized self-force is derived from the R
part which is regular and satisfies the source-free perturbed Einstein
equations. In this paper, we consider a gauge transformation from the harmonic
gauge to the Regge-Wheeler gauge in which the full metric perturbation can be
calculated, and present a method to derive the regularized self-force for a
particle in circular orbit around a Schwarzschild black hole in the
Regge-Wheeler gauge. As a first application of this method, we then calculate
the self-force to first post-Newtonian order. We find the correction to the
total mass of the system due to the presence of the particle is correctly
reproduced in the force at the Newtonian order.


title: Passage of Time in a Planck Scale Rooted Local Inertial Structure

abstract:
  It is argued that the `problem of time' in quantum gravity necessitates a
refinement of the local inertial structure of the world, demanding a
replacement of the usual Minkowski line element by a 4+2n dimensional
pseudo-Euclidean line element, with the extra 2n being the number of internal
phase space dimensions of the observed system. In the refined structure, the
inverse of the Planck time takes over the role of observer-independent
conversion factor usually played by the speed of light, which now emerges as an
invariant but derivative quantity. In the relativistic theory based on the
refined structure, energies and momenta turn out to be invariantly bounded from
above, and lengths and durations similarly bounded from below, by their
respective Planck scale values. Along the external timelike world-lines, the
theory naturally captures the `flow of time' as a genuinely structural
attribute of the world. The theory also predicts expected
deviations--suppressed quadratically by the Planck energy--from the dispersion
relations for free fields in the vacuum. The deviations from the special
relativistic Doppler shifts predicted by the theory are also suppressed
quadratically by the Planck energy. Nonetheless, in order to estimate the
precision required to distinguish the theory from special relativity, an
experiment with a binary pulsar emitting TeV range gamma-rays is considered in
the context of the predicted deviations from the second-order shifts.


title: Wave Function of the Universe and Its Meaning

abstract:
  For a FRW-spacetime coupled to an arbitrary real scalar field, we endow the
solution space of the associated Wheeler-DeWitt equation with a Hilbert-space
structure, construct the observables, and introduce the physical wave functions
of the universe that admit a genuine probabilistic interpretation. We also
discuss a proposal for the formulation of the dynamics. The approach to quantum
cosmology outlined in this article is based on the results obtained within the
theory of pseudo-Hermitian operators.


title: Quantum particle on hyperboloid

abstract:
  We present quantization of particle dynamics on one-sheet hyperboloid
embedded in three dimensional Minkowski space. Taking account of all global
symmetries enables unique quantization. Making use of topology of canonical
variables not only simplifies calculations but also gives proper framework for
analysis.


title: Exact General Relativistic Perfect Fluid Disks with Halos

abstract:
  Using the well-known ``displace, cut and reflect'' method used to generate
disks from given solutions of Einstein field equations, we construct static
disks made of perfect fluid based on vacuum Schwarzschild's solution in
isotropic coordinates. The same method is applied to different exactsolutions
to the Einstein'sequations that represent static spheres of perfect fluids. We
construct several models of disks with axially symmetric perfect fluid halos.
  All disks have some common features: surface energy density and pressures
decrease monotonically and rapidly with radius. As the ``cut'' parameter $a$
decreases, the disks become more relativistic, with surface energy density and
pressure more concentrated near the center. Also regions of unstable circular
orbits are more likely to appear for high relativistic disks. Parameters can be
chosen so that the sound velocity in the fluid and the tangential velocity of
test particles in circular motion are less then the velocity of light. This
tangential velocity first increases with radius and reaches a maximum.


title: Gauge-invariant Hamiltonian dynamics of cylindrical gravitational waves

abstract:
  The model of cylindrical gravitational waves is employed to work out and
check a recent proposal in Ref. [11] how a diffeomorphism-invariant Hamiltonian
dynamics is to be constructed. The starting point is the action by Ashtekar and
Pierri because it contains the boundary term that makes it differentiable for
non-trivial variations at infinity. With the help of parametrization at
infinity, the notion of gauge transformation is clearly separated from that of
asymptotic symmetry. The symplectic geometry of asymptotic symmetries and
asymptotic time is described and the role of the asymptotic structures in
defining a zero-motion frame for the Hamiltonian dynamics of Dirac observables
is explained. Complete sets of Dirac observables associated with the asymptotic
fields are found and the action of the asymptotic symmetries on them is
calculated. The construction of the corresponding quantum theory is sketched:
the Fock space, operators of asymptotic fields, the Hamiltonian and the
scattering matrix are determined.


title: Dynamical Horizons and their Properties

abstract:
  A detailed description of how black holes grow in full, non-linear general
relativity is presented. The starting point is the notion of dynamical
horizons. Expressions of fluxes of energy and angular momentum carried by
gravitational waves across these horizons are obtained. Fluxes are local and
the energy flux is positive. Change in the horizon area is related to these
fluxes. A notion of angular momentum and energy is associated with
cross-sections of the horizon and balance equations, analogous to those
obtained by Bondi and Sachs at null infinity, are derived. These in turn lead
to generalizations of the first and second laws of black hole mechanics. The
relation between dynamical horizons and their asymptotic states --the isolated
horizons-- is discussed briefly. The framework has potential applications to
numerical, mathematical, astrophysical and quantum general relativity.


title:
Radiation Reaction in Schwarzschild Spacetime: Retarded Green's Function
  via Hadamard-WKB Expansion

abstract:
  An analytic method is given for deriving the part of the retarded Green's
function v(x,x') that contributes to the tail term in the radiation reaction
force felt by a particle coupled to a massless minimally coupled scalar field.
The method gives an expansion of v(x,x') for small separations of the points x,
x' valid for an arbitrary static spherically symmetric spacetime. It is
obtained by using a WKB approximation for the Euclidean Green's function for
the massless minimally coupled scalar field and is equivalent to the
DeWitt-Schwinger expansion for v(x,x'). The first few terms in this expansion
are displayed here for the case of Schwarzschild spacetime.


title:
Asymptotic behaviour of the Einstein-Vlasov system with a positive
  cosmological constant

abstract:
  We study locally spatially homogeneous solutions of the Einstein-Vlasov
system with a positive cosmological constant. First the global existence of
solutions of this system and the casual geodesic completeness are shown. Then
the asymptotic behaviour of solutions in the future time is investigated in
various aspects.


title:
New proposals for the detection of the Earth's gravitomagnetic field in
  space-based and laboratory-based experiments

abstract:
  In this contribution we present two new proposals for measuring the general
relativistic gravitomagnetic component of the gravitational field of the Earth.
One proposal consists of the measurement of the difference of the rates of the
perigee $\psi$ from the analysis of the laser--ranged data of two identical
Earth'artificial satellites placed in equal orbits with supplementary
inclinations. In this way the impact of the aliasing classical secular
precessions due to the even zonal harmonics of the geopotential would be
canceled out, although the non--gravitational perturbations, to which the
perigees of LAGEOS--type satellites are particularly sensitive, should be a
limiting factor in the obtainable accuracy. With a suitable choice of the
inclinations of the orbital planes it would be possible to reduce the periods
of such insidious perturbations so to use not too long observational time
spans. However, the use of a pair of drag--free satellites would greatly reduce
this problem, provided that the time span of the data analysis does not excess
the lifetime of the drag--free apparatus. In the other proposal the difference
of the rotational periods of two counter-revolving particles placed on a
friction-free plane in a vacuum chamber at the South Pole should be measured in
order to extract the relativistic gravitomagnetic signal. Among other very
challenging practical implications, the Earth's angular velocity
$\omega_{\oplus}$ should be known at a $10^{-15}$ rad s$^{-1}$ level from VLBI
and the friction force of the plane should be less than $2\times 10^{-9}$ dyne.


title:
Role of Initial Data in Higher Dimensional Quasi-Spherical Gravitational
  Collapse

abstract:
  We study the gravitational collapse in ($n+2$)-D quasi-spherical Szekeres
space-time (which possess no killing vectors) with dust as the matter
distribution. Instead of choosing the radial coordinate `$r$' as the initial
value for the scale factor $R$, we consider a power function of $r$ as the
initial scale for the radius $R$. We examine the influence of initial data on
the formation of singularity in gravitational collapse.


title: Differential Invariants of the Kerr Vacuum

abstract:
  The norms associated with the gradients of the two non-differential
invariants of the Kerr vacuum are examined. Whereas both locally single out the
horizons, their global behavior is more interesting. Both reflect the
background angular momentum as the volume of space allowing a timelike gradient
decreases with increasing angular momentum becoming zero in the degenerate and
naked cases. These results extend directly to the Kerr-Newman geometry.


title: Novel approach to the study of quantum effects in the early universe

abstract:
  We develop a theoretical frame for the study of classical and quantum
gravitational waves based on the properties of a nonlinear ordinary
differential equation for a function $\sigma(\eta)$ of the conformal time
$\eta$, called the auxiliary field equation. At the classical level,
$\sigma(\eta)$ can be expressed by means of two independent solutions of the
''master equation'' to which the perturbed Einstein equations for the
gravitational waves can be reduced. At the quantum level, all the significant
physical quantities can be formulated using Bogolubov transformations and the
operator quadratic Hamiltonian corresponding to the classical version of a
damped parametrically excited oscillator where the varying mass is replaced by
the square cosmological scale factor $a^{2}(\eta)$. A quantum approach to the
generation of gravitational waves is proposed on the grounds of the previous
$\eta-$dependent Hamiltonian. An estimate in terms of $\sigma(\eta)$ and
$a(\eta)$ of the destruction of quantum coherence due to the gravitational
evolution and an exact expression for the phase of a gravitational wave
corresponding to any value of $\eta$ are also obtained. We conclude by
discussing a few applications to quasi-de Sitter and standard de Sitter
scenarios.


title: R^2-corrections to Chaotic Inflation

abstract:
  Scalar density cosmological perturbations, spectral indices and reheating in
a chaotic inflationary universe model, in which a higher derivative term is
added, are investigated. This term is supposed to play an important role in the
early evolution of the Universe, specifically at times closer to the Planck
era.


title: A Simulation of the LISA Data Stream from Galactic White Dwarf Binaries

abstract:
  Gravitational radiation from the galactic population of white dwarf binaries
is expected to produce a background signal in the LISA frequency band. At
frequencies below 1 mHz, this signal is expected to be confusion-limited and
has been approximated as gaussian noise. At frequencies above about 5 mHz, the
signal will consist of separable individual sources. We have produced a
simulation of the LISA data stream from a population of 90k galactic binaries
in the frequency range between 1 - 5 mHz. This signal is compared with the
simulated signal from globular cluster populations of binaries. Notable
features of the simulation as well as potential data analysis schemes for
extracting information are presented.


title: On the motion of spinning test particles in plane gravitational waves

abstract:
  The Mathisson-Papapetrou-Dixon equations for a massive spinning test particle
in plane gravitational waves are analysed and explicit solutions constructed in
terms of solutions of certain linear ordinary differential equations. For
harmonic waves this system reduces to a single equation of Mathieu-Hill type.
In this case spinning particles may exhibit parametric excitation by
gravitational fields. For a spinning test particle scattered by a gravitational
wave pulse, the final energy-momentum of the particle may be related to the
width, height, polarisation of the wave and spin orientation of the particle.


title:
Detector Description and Performance for the First Coincidence
  Observations between LIGO and GEO

abstract:
  For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.


title:
Sommerfeld's quantum condition of action and the spectra of
  Schwarzschild black hole

abstract:
  If the situation of quantum gravity nowadays is nearly the same as that of
the quantum mechanics in it's early time of Bohr and Sommerfeld, then a first
step study of the quantum gravity from Sommerfeld's quantum condition of action
might be helpful. In this short paper the spectra of Schwarzschild black
hole(SBH) in quasi-classical approach of quantum mechanics is given. We find
the quantum of area, the quantum of entropy and the Hawking evaporation will
cease as the black hole reaches its ground state.


title:
Stochastic Background Search Correlating ALLEGRO with LIGO Engineering
  Data

abstract:
  We describe the role of correlation measurements between the LIGO
interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in
Baton Rouge, LA, in searches for a stochastic background of gravitational
waves. Such measurements provide a valuable complement to correlations between
interferometers at the two LIGO sites, since they are sensitive in a different,
higher, frequency band. Additionally, the variable orientation of the ALLEGRO
detector provides a means to distinguish gravitational wave correlations from
correlated environmental noise. We describe the analysis underway to set a
limit on the strength of a stochastic background at frequencies near 900 Hz
using ALLEGRO data and data from LIGO's E7 Engineering Run.


title: Brane-cosmology dynamics with induced gravity

abstract:
  The Friedmann equations for a brane with induced gravity are analyzed and
compared with the standard general relativity and Randall-Sundrum cases.
Randall-Sundrum gravity modified the early universe dynamics, whereas induced
gravity changes the late universe evolution. The early and late time limits are
investigated. Induced gravity effects can contribute to late-universe
acceleration. This conditions for this are found. Qualitative analysis is given
for a range of scalar field potentials.


title: Radiation Reaction on Moving Particles in General Relativity

abstract:
  A particle in the vicinity of a Schwarzschild black hole is known to trace a
geodesic of the Schwarzschild background, to a first approximation. If the
interaction of the particle with its own field (scalar, electromagnetic or
gravitational) is taken into account, the path is no longer a background
geodesic and the self-force that the particle experiences needs to be taken
into consideration.
  In this dissertation, a recently proposed method for the calculation of the
self-force is implemented. According to this method the self-force comes from
the interaction of the particle with the Regular-Remainder scalar field,
electromagnetic potential or metric perturbation. That Regular-Remainder is
obtained by subtracting the Singular part (which exerts no force) from the
retarded scalar field, electromagnetic potential of metric perturbation
generated by the moving particle. First, the Singular scalar fields,
electromagnetic potentials and metric perturbations are calculated for
different sources moving in a Schwarzschild background. For that, the
Thorne-Hartle-Zhang coordinates in the vicinity of the moving source are used.
Then a mode-sum regularization method initially proposed for the direct scalar
field is followed, and the regularization parameters for the singular part of
the scalar field and for the first radial derivative of the singular part of
the self-force are calculated. Also, the numerical calculation of the retarded
scalar field for a particle moving on a circular geodesic in a Schwarzschild
spacetime is presented. Finally, the self-force for a scalar particle moving on
a circular Schwarzschild orbit is calculated and some results about the effects
of the self-force on the orbital frequency of the circular orbit are presented.


title:
Introduction to Quantum Fields in Curved Spacetime and the Hawking
  Effect

abstract:
  These notes introduce the subject of quantum field theory in curved spacetime
and some of its applications and the questions they raise. Topics include
particle creation in time-dependent metrics, quantum origin of primordial
perturbations, Hawking effect, the trans-Planckian question, and Hawking
radiation on a lattice.


title:
Large-scale non-locality in "doubly special relativity" with an
  energy-dependent speed of light

abstract:
  There are two major alternatives for violating the (usual) Lorentz invariance
at large (Planckian) energies or momenta - either not all inertial frames (in
the Planck regime) are equivalent (e.g., there is an effectively preferred
frame) or the transformations from one frame to another are (non-linearly)
deformed (``doubly special relativity''). We demonstrate that the natural (and
reasonable) assumption of an energy-dependent speed of light in the latter
method goes along with violations of locality/separability (and even
translational invariance) on macroscopic scales.
  PACS: 03.30.+p, 11.30.Cp, 04.60.-m, 04.50.+h.


title:
Setting upper limits on the strength of periodic gravitational waves
  using the first science data from the GEO600 and LIGO detectors

abstract:
  Data collected by the GEO600 and LIGO interferometric gravitational wave
detectors during their first observational science run were searched for
continuous gravitational waves from the pulsar J1939+2134 at twice its rotation
frequency. Two independent analysis methods were used and are demonstrated in
this paper: a frequency domain method and a time domain method. Both achieve
consistent null results, placing new upper limits on the strength of the
pulsar's gravitational wave emission. A model emission mechanism is used to
interpret the limits as a constraint on the pulsar's equatorial ellipticity.


title:
Gravitational radiation reaction in compact binary systems: Contribution
  of the magnetic dipole-magnetic dipole interaction

abstract:
  We study the gravitational radiation reaction in compact binary systems
composed of neutron stars with spin and huge magnetic dipole moments
(magnetars). The magnetic dipole moments undergo a precessional motion about
the respective spins. At sufficiently high values of the magnetic dipole
moments, their interaction generates second post-Newtonian order contributions
both to the equations of motion and to the gravitational radiation escaping the
system. We parametrize the radial motion and average over a radial period in
order to find the secular contributions to the energy and magnitude of the
orbital angular momentum losses, in the generic case of \textit{eccentric}
orbits. Similarly as for the spin-orbit, spin-spin, quadrupole-monopole
interactions, here too we deduce the secular evolution of the relative
orientations of the orbital angular momentum and spins. These equations,
supplemented by the evolution equations for the angles characterizing the
orientation of the dipole moments form a first order differential system, which
is closed. The circular orbit limit of the energy loss agrees with Ioka and
Taniguchi's earlier result.


title: Exactly soluble model for self-gravitating D-particles with the wormhole

abstract:
  We consider D-particles coupled to the CGHS dilaton gravity and obtain the
exact wormhole geometry and trajectories of D-particles by introducing the
exotic matter. The initial static wormhole background is not stable after
infalling D-particles due to the classical backreaction of the geometry so that
the additional exotic matter source should be introduced for the stability.
Then, the traversable wormhole geometry naturally appears and the D-particles
can travel through it safely. Finally, we discuss the dynamical evolution of
the wormhole throat and the massless limit of D-particles.


title:
On the impossibility of measuring a galvano-gravitomagnetic effect with
  current carrying semiconductors in a space-based experiment

abstract:
  In this paper we investigate the feasibility of a recently proposed
space-based experiment aimed to the detection of the effect of the Earth
gravitomagnetic field in spaceborne semiconductors carrying radial electric
currents and following identical circular equatorial orbits along opposite
directions. It turns out that the deviations from this idealized situation due
to the unavoidable orbital injection errors would make impossible the
measurement of the gravitomagnetic voltage of interest.


title: Dark matter and stable bound states of primordial black holes

abstract:
  We present three reasons for the formation of gravitational bound states of
primordial black holes,called holeums,in the early universe.Using Newtonian
gravity and nonrelativistic quantum mechanics we find a purely quantum
mechanical mass-dependant exclusion property for the nonoverlap of the
constituent black holes in a holeum.This ensures that the holeum occupies space
just like ordinary matter.A holeum emits only gravitational radiation whose
spectrum is an exact analogue of that of a hydrogen atom. A part of this
spectrum lies in the region accessible to the detectors being built.The holeums
would form haloes around the galaxies and would be an important component of
the dark matter in the universe today.They may also be the constituents of the
invisible domain walls in the universe.


title:
On the area of the symmetry orbits in $T^2$ symmetric spacetimes with
  Vlasov matter

abstract:
  This paper treats the global existence question for a collection of general
relativistic collisionless particles, all having the same mass. The spacetimes
considered are globally hyperbolic, with Cauchy surface a 3-torus. Furthermore,
the spacetimes considered are isometrically invariant under a two-dimensional
group action, the orbits of which are spacelike 2-tori. It is known from
previous work that the area of the group orbits serves as a global time
coordinate. In the present work it is shown that the area takes on all positive
values in the maximal Cauchy development.


title: On the embedding of branes in five-dimensional spaces

abstract:
  We investigate the embedding of four-dimensional branes in five-dimensional
spaces. We firstly consider the case when the embedding space is a vacuum bulk
whose energy-momentum tensor consists of a Dirac delta function with support in
the brane. We then consider the embedding in the context of
Randall-Sundrum-type models, taking into account $Z_{2}$ symmetry and a
cosmological constant. We employ the Campbell-Magaard theorem to construct the
embeddings and are led to the conclusion that the content of energy-matter of
the brane does not necessarily determine its curvature. Finally, as an
application to illustrate our results, we construct the embedding of Minkowski
spacetime filled with dust.


title: General Relativistic Static Fluid Solutions with Cosmological Constant

abstract:
  This diploma thesis analyses static, spherically symmetric perfect fluid
solutions to Einstein's field equations with cosmological constant. Constant
density solutions are derived for different values of the cosmological
constant. Eleven types of solutions are found, with an overview given at page
41. Furthermore the existence of a global solution is proved for a cosmological
constant smaller than 4 Pi the boundary density, which is given by the equation
of state.


title: Randall-Sundrum Model in the Presence of a Brane Bulk Viscosity

abstract:
  The presence of a bulk viscosity for the cosmic fluid on a single
Randall-Sundrum brane is considered. The spatial curvature is assumed to be
zero. The five-dimensional Friedmann equation is derived, together with the
energy conservation equation for the viscous fluid. These governing equations
are solved for some special cases: (i) in the low-energy limit when the matter
energy density is small compared with brane tension; (ii) for a
matter-dominated universe, and (iii) for a radiation-dominated universe. Rough
numerical estimates, for the extreme case when the universe is at its Planck
time, indicate that the viscous effect can be significant.


title:
Anisotropic Cosmological Models with Energy Density Dependent Bulk
  Viscosity

abstract:
  An analysis is presented of the Bianchi type I cosmological models with a
bulk viscosity when the universe is filled with the stiff fluid $p = \epsilon$
while the viscosity is a power function of the energy density, such as $\eta =
\alpha |\epsilon|^n$. Although the exact solutions are obtainable only when the
$2n$ is an integer, the characteristics of evolution can be clarified for the
models with arbitrary value of $n$. It is shown that, except for the $n = 0$
model that has solutions with infinite energy density at initial state, the
anisotropic solutions that evolve to positive Hubble functions in the later
stage will begin with Kasner-type curvature singularity and zero energy density
at finite past for the $n> 1$ models, and with finite Hubble functions and
finite negative energy density at infinite past for the $n < 1$ models. In the
course of evolution, matters are created and the anisotropies of the universe
are smoothed out. At the final stage, cosmologies are driven to infinite
expansion state, de Sitter space-time, or Friedman universe asymptotically.
However, the de Sitter space-time is the only attractor state for the $n <1/2 $
models. The solutions that are free of cosmological singularity for any finite
proper time are singled out. The extension to the higher-dimensional models is
also discussed.


title:
Effects of the Shear Viscosity on the Character of Cosmological
  Evolution

abstract:
  Bianchi type I cosmological models are studied that contain a stiff fluid
with a shear viscosity that is a power function of the energy density, such as
$\zeta = \alpha \epsilon^n$. These models are analyzed by describing the
cosmological evolutions as the trajectories in the phase plane of Hubble
functions. The simple and exact equations that determine these flows are
obtained when $n$ is an integer. In particular, it is proved that there is no
Einstein initial singularity in the models of $0\leq n < 1$. Cosmologies are
found to begin with zero energy density and in the course of evolution the
gravitational field will create matter. At the final stage, cosmologies are
driven to the isotropic Fnedmann universe. It is also pointed out that although
the anisotropy will always be smoothed out asymptotically, there are solutions
that simultaneously possess non-positive and non-negative Hubble functions for
all time. This means that the cosmological dimensional reduction can work even
if the matter fluid having shear viscosity. These characteristics can also be
found in any-dimensional models.


title:
Interacting spinor and scalar fields in a Bianchi type-I Universe:
  Oscillatory solutions

abstract:
  Self-consistent system of spinor, scalar and BI gravitational fields is
considered. Exact solutions to the field equations in terms of volume scale of
the BI metric are obtained. Einstein field equations in account of the
cosmological constant $\Lambda$ and perfect fluid are studied. Oscillatory mode
of expansion of the universe is obtained. It is shown that for the interaction
term being a power function of the invariants of bilinear spinor forms and
$\Lambda > 0$ and given other parameters, e.g., coupling constant, spinor mass
etc., there exists a finite range of integration constant which generates
oscillatory mode of evolution.


title:
Optimal generalization of power filters for gravitational wave bursts,
  from single to multiple detectors

abstract:
  Searches for gravitational wave signals which do not have a precise model
describing the shape of their waveforms are often performed using power
detectors based on a quadratic form of the data. A new, optimal method of
generalizing these power detectors so that they operate coherently over a
network of interferometers is presented. Such a mode of operation is useful in
obtaining better detection efficiencies, and better estimates of the position
of the source of the gravitational wave signal. Numerical simulations based on
a realistic, computationally efficient hierarchical implementation of the
method are used to characterize its efficiency, for detection and for position
estimation. The method is shown to be more efficient at detecting signals than
an incoherent approach based on coincidences between lists of events. It is
also shown to be capable of locating the position of the source.


title:
Constraints on the Detectability of Cosmic Topology from Observational
  Uncertainties

abstract:
  Recent observational results suggest that our universe is nearly flat and
well modelled within a $\Lambda$CDM framework. The observed values of
$\Omega_{m}$ and $\Omega_{\Lambda}$ inevitably involve uncertainties. Motivated
by this, we make a systematic study of the necessary and sufficient conditions
for undetectability as well as detectability (in principle) of cosmic topology
(using pattern repetition) in presence of such uncertainties. We do this by
developing two complementary methods to determine detectability for nearly flat
universes. Using the first method we derive analytical conditions for
undetectability for infinite redshift, the accuracy of which is then confirmed
by the second method. Estimates based on WMAP data together with other
measurements of the density parameters are used to illustrate both methods,
which are shown to provide very similar results for high redshifts.


title:
Hawking radiation from spherically symmetrical gravitational collapse to
  an extremal R-N black hole for a charged scalar field

abstract:
  Sijie Gao has recently investigated Hawking radiation from spherically
symmetrical gravitational collapse to an extremal R-N black hole for a real
scalar field. Especially he estimated the upper bound for the expected number
of particles in any wave packet belonging to $\mathcal{H}_{out}$ spontaneously
produced from the state $|0>_{in}$, which confirms the traditional belief that
extremal black holes do not radiate particles. Making some modifications, we
demonstrate that the analysis can go through for a charged scalar field.


title:
Quantum fluctuations of lightcone in 4-dimensional spacetime with
  parallel plane boundaries

abstract:
  Quantum fluctuations of lightcone are examined in a 4-dimensional spacetime
with two parallel planes. Both the Dirichlet and the Neumann boundary
conditions are considered. In all the cases we have studied, quantum lightcone
fluctuations are greater where the Neumann boundary conditions are imposed,
suggesting that quantum lightcone fluctuations depend not only on the geometry
and topology of the spacetime as has been argued elsewhere but also on boundary
conditions. Our results also show that quantum lightcone fluctuations are
larger here than that in the case of a single plane. Therefore, the confinement
of gravitons in a smaller region by the presence of a second plane reinforces
the quantum fluctuations and this can be understood as a consequence of the
uncertainty principle.


title: Ideally embedded space-times

abstract:
  Due to the growing interest in embeddings of space-time in higher-dimensional
spaces we consider a specific type of embedding. After proving an inequality
between intrinsically defined curvature invariants and the squared mean
curvature, we extend the notion of ideal embeddings from Riemannian geometry to
the indefinite case. Ideal embeddings are such that the embedded manifold
receives the least amount of tension from the surrounding space. Then it is
shown that the de Sitter spaces, a Robertson-Walker space-time and some
anisotropic perfect fluid metrics can be ideally embedded in a five-dimensional
pseudo-Euclidean space.


title: Dynamics and stability of the Godel universe

abstract:
  We use covariant techniques to describe the properties of the Godel universe
and then consider its linear response to a variety of perturbations. Against
matter aggregations, we find that the stability of the Godel model depends
primarily upon the presence of gradients in the centrifugal energy, and
secondarily on the equation of state of the fluid. The latter dictates the
behaviour of the model when dealing with homogeneous perturbations. The
vorticity of the perturbed Godel model is found to evolve as in almost-FRW
spacetimes, with some additional directional effects due to shape distortions.
We also consider gravitational-wave perturbations by investigating the
evolution of the magnetic Weyl component. This tensor obeys a simple plane-wave
equation, which argues for the neutral stability of the Godel model against
linear gravity-wave distortions. The implications of the background rotation
for scalar-field Godel cosmologies are also discussed.


title:
A new analytical method for self-force regularization I. scalar charged
  particle in Schwarzschild spacetime

abstract:
  We formulate a new analytical method for regularizing the self-force acting
on a particle of small mass $\mu$ orbiting a black hole of mass $M$, where
$\mu\ll M$. At first order in $\mu$, the geometry is perturbed and the motion
of the particle is affected by its self-force. The self-force, however,
diverges at the location of the particle, and hence should be regularized. It
is known that the properly regularized self-force is given by the tail part (or
the $R$-part) of the self-field, obtained by subtracting the direct part (or
the $S$-part) from the full self-field. The most successful method of
regularization proposed so far relies on the spherical harmonic decomposition
of the self-force, the so-called mode-sum regularization or mode decomposition
regularization. However, except for some special orbits, no systematic
analytical method for computing the regularized self-force has been given. In
this paper, utilizing a new decomposition of the retarded Green function in the
frequency domain, we formulate a systematic method for the computation of the
self-force. Our method relies on the post-Newtonian (PN) expansion but the
order of the expansion can be arbitrarily high. To demonstrate the essence of
our method, in this paper, we focus on a scalar charged particle on the
Schwarzschild background. The generalization to the gravitational case is
straightforward, except for some subtle issues related with the choice of gauge
(which exists irrespective of regularization methods).


title: Analysis of LIGO data for gravitational waves from binary neutron stars

abstract:
  We report on a search for gravitational waves from coalescing compact binary
systems in the Milky Way and the Magellanic Clouds. The analysis uses data
taken by two of the three LIGO interferometers during the first LIGO science
run and illustrates a method of setting upper limits on inspiral event rates
using interferometer data. The analysis pipeline is described with particular
attention to data selection and coincidence between the two interferometers. We
establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$ per
year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the
coalescence rate of binary systems in which each component has a mass in the
range 1--3 $M_\odot$.


title: Entropy of Static Spacetimes and Microscopic Density of States

abstract:
  A general ansatz for gravitational entropy can be provided using the
criterion that, any patch of area which acts as a horizon for a suitably
defined accelerated observer, must have an entropy proportional to its area.
After providing a brief justification for this ansatz, several consequences are
derived: (i) In any static spacetime with a horizon and associated temperature
$\beta^{-1}$, this entropy satisfies the relation $S=(1/2)\beta E$ where $E$ is
the energy source for gravitational acceleration, obtained as an integral of
$(T_{ab}-(1/2)Tg_{ab})u^au^b$. (ii) With this ansatz of $S$, the minimization
of Einstein-Hilbert action is equivalent to minimizing the free energy $F$ with
$\beta F=\beta U-S$ where $U$ is the integral of $T_{ab}u^au^b$. We discuss the
conditions under which these results imply $S\propto E^2$ and/or $S\propto U^2$
thereby generalizing the results known for black holes. This approach links
with several other known results, especially the holographic views of
spacetime.


title: Chern-Simons Modification of General Relativity

abstract:
  General relativity is extended by promoting the three-dimensional
gravitational Chern-Simons term to four dimensions. This entails choosing an
embedding coordinate v_\mu -- an external quantity, which we fix to be a
non-vanishing constant in its time component. The theory is identical to one in
which the embedding coordinate is itself a dynamical variable, rather than a
fixed, external quantity. Consequently diffeomorphism symmetry breaking is
hidden in the modified theory: the Schwarzschild metric is a solution;
gravitational waves possess two polarizations, each traveling at the velocity
of light; a conserved energy-momentum (pseudo-) tensor can be constructed. The
modification is visible in the intensity of gravitational radiation: the two
polarizations of a gravity wave carry intensities that are suppressed/enchanced
by the extension.


title: Generalized Friedmann branes

abstract:
  We prove that for a large class of generalized Randall-Sundrum II type models
the characterization of brane-gravity sector by the effective Einstein
equation, Codazzi equation and the twice-contracted Gauss equation is
equivalent with the bulk Einstein equation. We give the complete set of
equations in the generic case of non-$Z_{2}$-symmetric bulk and arbitrary
energy-momentum tensors both on the brane and in the bulk. Among these, the
effective Einstein equation contains a varying cosmological constant and two
new source terms. The first of these represents the deviation from $Z_{2}$
symmetry, while the second arises from the bulk energy-momentum tensor. We
apply the formalism for the case of perfect fluid on a Friedmann brane embedded
in a generic bulk. The generalized Friedmann and Raychaudhuri equations are
given in a form independent of both the embedding and the bulk matter. They
contain two new functions obeying a first order differential system, both
depending on the bulk matter and the embedding. Then we focus on Friedmann
branes separating two non-identical (inner or outer) regions of
Reissner-Nordstr\"om-Anti de Sitter bulk space-times, generalizing previous
non-$Z_{2}$-symmetric treatments. Finally the analysis is repeated for the
Vaidya-Anti de Sitter bulk space-time, allowing for both ingoing and outgoing
radiation in each region.


title: Time and Energy in Gravity Theory

abstract:
  A new concept of internal time (viewed as a scalar temporal field) is
introduced which allows one to solve the energy problem in General Relativity.
The law of energy conservation means that the total energy density of the full
system of interacting fields (including gravitational field) does not vary with
time, thus being the first integral of the system. It is demonstrated that
direct introduction of the temporal field permits to derive the general
covariant four dimensional Maxwell equations for the electric and magnetic
fields from the equations of electromagnetic fields considering in General
Relativity. It means that the fundamental physical laws are in full
correspondence with the essence of time. Theory of time presented here predicts
the existence of matter outside the time.


title: A Lorentzian Gromov-Hausdoff notion of distance

abstract:
  This paper is the first of three in which I study the moduli space of
isometry classes of (compact) globally hyperbolic spacetimes (with boundary). I
introduce a notion of Gromov-Hausdorff distance which makes this moduli space
into a metric space. Further properties of this metric space are studied in the
next papers. The importance of the work can be situated in fields such as
cosmology, quantum gravity and - for the mathematicians - global Lorentzian
geometry.


title: The limit space of a Cauchy sequence of globally hyperbolic spacetimes

abstract:
  In this second paper, I construct a limit space of a Cauchy sequence of
globally hyperbolic spacetimes. In the second section, I work gradually towards
a construction of the limit space. I prove the limit space is unique up to
isometry. I als show that, in general, the limit space has quite complicated
causal behaviour. This work prepares the final paper in which I shall study in
more detail properties of the limit space and the moduli space of (compact)
globally hyperbolic spacetimes (cobordisms). As a fait divers, I give in this
paper a suitable definition of dimension of a Lorentz space in agreement with
the one given by Gromov in the Riemannian case.


title: Extra force in Kaluza-Klein gravity theory

abstract:
  In induced matter Kaluza-Klein gravity theory the solution of the dynamics
equations for the test particle on null path leads to additional force in
four-dimensional space-time. We find such force from five-dimensional geodesic
line equations and apply this approach to analysis of the asymmetrically warped
space-time.


title:
Numerical analysis of quasinormal modes in nearly extremal
  Schwarzschild-de Sitter spacetimes

abstract:
  We calculate high-order quasinormal modes with large imaginary frequencies
for electromagnetic and gravitational perturbations in nearly extremal
Schwarzschild-de Sitter spacetimes. Our results show that for low-order
quasinormal modes, the analytical approximation formula in the extremal limit
derived by Cardoso and Lemos is a quite good approximation for the quasinormal
frequencies as long as the model parameter $r_1\kappa_1$ is small enough, where
$r_1$ and $\kappa_1$ are the black hole horizon radius and the surface gravity,
respectively. For high-order quasinormal modes, to which corresponds
quasinormal frequencies with large imaginary parts, on the other hand, this
formula becomes inaccurate even for small values of $r_1\kappa_1$. We also find
that the real parts of the quasinormal frequencies have oscillating behaviors
in the limit of highly damped modes, which are similar to those observed in the
case of a Reissner-Nordstr{\" o}m black hole. The amplitude of oscillating
${\rm Re(\omega)}$ as a function of ${\rm Im}(\omega)$ approaches a non-zero
constant value for gravitational perturbations and zero for electromagnetic
perturbations in the limit of highly damped modes, where $\omega$ denotes the
quasinormal frequency. This means that for gravitational perturbations, the
real part of quasinormal modes of the nearly extremal Schwarzschild-de Sitter
spacetime appears not to approach any constant value in the limit of highly
damped modes. On the other hand, for electromagnetic perturbations, the real
part of frequency seems to go to zero in the limit.


title: Schwarzschild solution on a space-time with torsion

abstract:
  We obtain the Schwarzschild solution based on teleparallel gravity (TG)
theory formulated in a space-time with torsion only. The starting point is the
Poincar\UNICODE{0xe9} gauge theory (PGT).The general structure of TG and its
connection with general relativity (GR) are presented and the Schwarzschild
solution is obtained by solving the field equations of TG. Most of calculations
are performed using the GRTensorII package, running on the MapleV platform.


title:
Electromagnetic Response for High-Frequency Gravitational Waves in the
  GHz to THz Band

abstract:
  We consider the electromagnetic (EM) response of a Gaussian beam passing
through a static magnetic field to be the high-frequency gravitational waves
(HFGW) as generated by several devices discussed at this conference. It is
found that under the synchroresonance condition, the first-order perturbative
EM power fluxes will contain a ''left circular wave'' and a ''right circular
wave'' around the symmetrical axis of the Gaussian beam. However, the
perturbative effects produced by the states of + polarization and \times
polarization of the GW have a different physical behavior. For the HFGW of
$\nu_{g}=3GHz$, $h=10^{-30}$ (which corresponds to the power flux density $~
10^{-6} W m^{-2}$) to $\nu_{g}=1.3THz$, $ h=10^{-28}$ (which corresponds to the
power flux density $~10^{3} W m^{-2}$) expected by the HFGW generators
described at this conference, the corresponding perturbative photon fluxes
passing through a surface region of $10^{-2} m^{2}$ would be expected to be
$10^{3} s^{-1} - 10^{4} s^{-1}$. They are the orders of magnitude of the
perturbative photon flux we estimated using typical laboratory parameters that
could lead to the development of sensitive HFGW receivers. Moreover, we will
also discuss the relative background noise problems and the possibility of
displaying the HFGW. A laboratory test bed for juxtaposed HFGW generators and
our detecting scheme is explored and discussed.


title: Particle Creation in Anisotropically Expanding Universe

abstract:
  Using squeezed vacuum state formalism of quantum optics, an approximate
solution to the semiclassical Einstein equation is obtained in Bianchi type-I
universe. The phenomena of nonclassical particle creation is also examined in
the anisotropic background cosmology.


title: Action principle for nonlinear parametric quantization of gravity

abstract:
  The derivation of the recently proposed nonlinear quantum evolution of
gravity from an action principle is considered in this brief note. It is shown
to be possible if a set of consistency conditions are satisfied that are
analogous to the Dirac relations for the super-Hamiltonian and momenta in
classical canonical gravity.


title: Leptons might not generate gravity

abstract:
  A simple thought experiment suggests that, contrary to assertions in an
earlier Letter, constancy across materials of the ratio of active to passive
gravitational mass does not rule out that electrons (and other leptons) could
have active gravitational mass zero, thus might not generate gravity. If they
do not, then widely held assumptions about the gravitational effects of various
forms of energy cannot be sustained.


title: Field-Particle Dynamics in Spacetime Geometries

abstract:
  With the aid of a Fermi-Walker chart associated with an orthonormal frame
attached to a time-like curve in spacetime, a discussion is given of
relativistic balance laws that may be used to construct models of massive
particles with spin, electric charge and a magnetic moment,interacting with
background electromagnetic fields and gravitation described by non-Riemannian
geometries. A natural generalisation to relativistic Cosserat media is
immediate.


title:
The vacuum energy density in the teleparallel equivalent of general
  relativity

abstract:
  Considering the vacuum as characterized by the presence of only the
gravitational field, we show that the vacuum energy density of the de Sitter
space, in the realm of the teleparallel equivalent of general relativity, can
acquire arbitrarily high values. This feature is expected to hold in the
consideration of realistic cosmological models, and may possibly provide a
simple explanation to the cosmological constant problem.


title: Noise characterization for LISA

abstract:
  We consider the general problem of estimating the inflight LISA noise power
spectra and cross-spectra, which are needed for detecting and estimating the
gravitational wave signals present in the LISA data. For the LISA baseline
design and in the long wavelength limit, we bound the error on all spectrum
estimators that rely on the use of the fully symmetric Sagnac combination
($\zeta$). This procedure avoids biases in the estimation that would otherwise
be introduced by the presence of a strong galactic background in the LISA data.
We specialize our discussion to the detection and study of the galactic white
dwarf-white dwarf binary stochastic signal.


title: Particle Creation in Kaluza-Klein Cosmology

abstract:
  We exactly calculate the particle number $N$ of scalar fields which are
created from an initial vacuum in certain higher-dimensional cosmological
models. The spacetimes in these models are the four-dimensional Chitre-Hartle
or radiation-dominated universe with extra spaces which are static or power-law
contracting. Except for some models in which no particles could be produced,
the distribution of created particles shows a thermal behavior, at least in the
limit of high three-dimensional "momentum" $k$. In some models, $N$ does not
depend on the magnitude of the extra-dimensional "momentum" $k_c$ if $k_c$ is
nonvanishing. A cutoff momentum $k_c$ may emerge in some models, and particles
with $k\le k_c$ could not be produced. We also discuss these results.


title:
Galaxies as Rotating Buckets - a Hypothesis on the Gravitational
  Constant Based on Mach's Principle

abstract:
  According to Mach's principle inertia has its reason in the presence of all
masses in the universe. Despite there is a lot of sympathy for this plausible
idea, only a few quantitative frameworks have been proposed to test it. In this
paper a tentative theory is given which is based on Mach's critisism on
Newton's rotating bucket. Taking this criticism seriously, one is led to the
hypothesis that the rotation of our galaxy is the reason for gravitation.
Concretely, a functional dependence of the gravitational constant on the size,
mass and angular momentum of the milky way is proposed that leads to a spatial,
but not to a temporal variation of G. Since Newton's inverse-square law is
modified, flat rotation curves of galaxies can be explained that usually need
the postulate of dark matter. While the consequences for stellar evolution are
discussed briefly, a couple of further observational coincidences are noted and
possible experimental tests are proposed.


title: Nonlinear spinor field in cosmology

abstract:
  Within the scope of Bianchi type VI (BVI) model the self-consistent system of
nonlinear spinor and gravitational fields is considered. Exact self-consistent
solutions to the spinor and gravitational field equations are obtained for some
special choice of spatial inhomogeneity and nonlinear spinor term. The role of
inhomogeneity in the evolution of spinor and gravitational field is studied.
Oscillatory mode of expansion of the BVI universe is obtained for some special
choice of spinor field nonlinearity.


title: Scale Free Small World Networks and the Structure of Quantum Space-Time

abstract:
  We report on parallel observations in two seemingly unrelated areas of
dynamical network research. The one is the so-called small world phenomenon
and/or the observation of scale freeness in certain types of large (empirical)
networks and their theoretical analysis. The other is a discrete cellular
network approach to quantum space-time physics on the Planck scale we developed
in the recent past. In this context we formulated a kind of geometric
renormalisation group or coarse graining process in order to construct some
fixed point which can be associated to our macroscopic space-time (physics).
Such a fixed point can however only emerge if the network on the Planck scale
has very peculiar critical geometric properties which strongly resemble the
phenomena observed in the above mentioned networks. A particularly noteworthy
phenomenon is the appearance of translocal bridges or short cuts connecting
widely separated regions of ordinary space-time and which we expect to become
relevant in various of the notorious quantum riddles.


title:
Second generation instruments for the Laser Interferometer Gravitational
  Wave Observatory (LIGO)

abstract:
  The interferometers being planned for second generation LIGO promise and
order of magnitude increase in broadband strain sensitivity--with the
corresponding cubic increase in detection volume--and an extension of the
observation band to lower frequencies. In addition, one of the interferometers
may be designed for narrowband performance, giving further improved sensitivity
over roughly an octave band above a few hundred Hertz. This article discusses
the physics and technology of these new interferometer designs, and presents
their projected sensitivity spectra.


title: General study and basic properties of causal symmetries

abstract:
  We fully develop the concept of causal symmetry introduced in Class. Quant.
Grav. 20 (2003) L139. A causal symmetry is a transformation of a Lorentzian
manifold (V,g) which maps every future-directed vector onto a future-directed
vector. We prove that the set of all causal symmetries is not a group under the
usual composition operation but a submonoid of the diffeomorphism group of V.
Therefore, the infinitesimal generating vector fields of causal symmetries
--causal motions-- are associated to local one-parameter groups of
transformations which are causal symmetries only for positive values of the
parameter --one-parameter submonoids of causal symmetries--. The pull-back of
the metric under each causal symmetry results in a new rank-2 future tensor,
and we prove that there is always a set of null directions canonical to the
causal symmetry. As a result of this it makes sense to classify causal
symmetries according to the number of independent canonical null directions.
This classification is maintained at the infinitesimal level where we find the
necessary and sufficient conditions for a vector field to be a causal motion.
They involve the Lie derivatives of the metric tensor and of the canonical null
directions. In addition, we prove a stability property of these equations under
the repeated application of the Lie operator. Monotonicity properties,
constants of motion and conserved currents can be defined or built using casual
motions. Some illustrative examples are presented.


title:
Manifold structures for sets of solutions of the general relativistic
  constraint equations

abstract:
  We construct manifold structures on various sets of solutions of the general
relativistic initial data sets.


title:
Topological Charged Black Holes in High Dimensional Spacetimes and Their
  Formation from Gravitational Collapse of a Type II Fluid

abstract:
  Topological charged black holes coupled with a cosmological constant in
$R^{2}\times X^{D-2}$ spacetimes are studied, where $X^{D-2}$ is an Einstein
space of the form ${}^{(D-2)}R_{AB} = k(D-3) h_{AB}$. The global structure for
the four-dimensional spacetimes with $k = 0$ is investigated systematically.
The most general solutions that represent a Type $II$ fluid in such a high
dimensional spacetime are found, and showed that topological charged black
holes can be formed from the gravitational collapse of such a fluid. When the
spacetime is (asymptotically) self-similar, the collapse always forms black
holes for $k = 0, -1$, in contrast to the case $k = 1$, where it can form
either balck holes or naked singularities.


title:
Comment on "Absence of trapped surfaces and singularities in cylindrical
  collapse"

abstract:
  Recently, the gravitational collapse of an infinite cylindrical thin shell of
matter in an otherwise empty spacetime with two hypersurface orthogonal Killing
vectors was studied by Gon\c{c}alves [Phys. Rev. {\bf D65}, 084045 (2002).]. By
using three "alternative" criteria for trapped surfaces, the author claimed to
have shown that {\em they can never form either outside or on the shell,
regardingless of the matter content for the shell, except at asymptotical
future null infinite}.
  Following Penrose's original idea, we first define trapped surfaces in
cylindrical spacetimes in terms of the expansions of null directions orthogonal
to the surfaces, and then show that the first criterion used by Gon\c{c}alves
is incorrect. We also show that his analysis of non-existence of trapped
surfaces in vacuum is incomplete. To confirm our claim, we present an example
that is a solution to the vacuum Einstein field equations and satisfies all the
regular conditions imposed by Gon\c{c}alves. After extending the solution to
the whole spacetime, we show explicitly that trapped surfaces exist in the
extended region.


title: An Inertial Reaction to Cosmological Accelerations

abstract:
  Mach's "fixed stars" are actually not fixed at all. The distant clusters of
galaxies are not only receding from each observer but they are also
accelerating since the rate of cosmological expansion is not constant. If the
distant cosmic masses in someway constitute the frame of inertial reference
then an additional force should be generated among local bodies in reaction to
the apparent cosmological accelerations of the distant galaxies.


title: No-Go Theorem in Spacetimes with Two Commuting Spacelike Killing Vectors

abstract:
  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.


title: Universes encircling 5-dimensional black holes

abstract:
  We clarify the status of two known solutions to the 5-dimensional vacuum
Einstein field equations derived by Liu, Mashhoon & Wesson (LMW) and Fukui,
Seahra & Wesson (FSW), respectively. Both 5-metrics explicitly embed
4-dimensional Friedman-Lemaitre-Robertson-Walker cosmologies with a wide range
of characteristics. We show that both metrics are also equivalent to
5-dimensional topological black hole (TBH) solutions, which is demonstrated by
finding explicit coordinate transformations from the TBH to LMW and FSW line
elements. We argue that the equivalence is a direct consequence of Birkhoff's
theorem generalized to 5 dimensions. Finally, for a special choice of
parameters we plot constant coordinate surfaces of the LMW patch in a
Penrose-Carter diagram. This shows that the LMW coordinates are regular across
the black and/or white hole horizons.


title:
Black Hole Spectroscopy: Testing General Relativity through
  Gravitational Wave Observations

abstract:
  Assuming that general relativity is the correct theory of gravity in the
strong field limit, can gravitational wave observations distinguish between
black hole and other compact object sources? Alternatively, can gravitational
wave observations provide a test of one of the fundamental predictions of
general relativity? Here we describe a definitive test of the hypothesis that
observations of damped, sinusoidal gravitational waves originated from a black
hole or, alternatively, that nature respects the general relativistic no-hair
theorem. For astrophysical black holes, which have a negligible charge-to-mass
ratio, the black hole quasi-normal mode spectrum is characterized entirely by
the black hole mass and angular momentum and is unique to black holes. In a
different theory of gravity, or if the observed radiation arises from a
different source (e.g., a neutron star, strange matter or boson star), the
spectrum will be inconsistent with that predicted for general relativistic
black holes. We give a statistical characterization of the consistency between
the noisy observation and the theoretical predictions of general relativity,
together with a numerical example.


title: The Cotton tensor in Riemannian spacetimes

abstract:
  Recently, the study of three-dimensional spaces is becoming of great
interest. In these dimensions the Cotton tensor is prominent as the substitute
for the Weyl tensor. It is conformally invariant and its vanishing is
equivalent to conformal flatness. However, the Cotton tensor arises in the
context of the Bianchi identities and is present in any dimension. We present a
systematic derivation of the Cotton tensor. We perform its irreducible
decomposition and determine its number of independent components for the first
time. Subsequently, we exhibit its characteristic properties and perform a
classification of the Cotton tensor in three dimensions. We investigate some
solutions of Einstein's field equations in three dimensions and of the
topologically massive gravity model of Deser, Jackiw, and Templeton. For each
class examples are given. Finally we investigate the relation between the
Cotton tensor and the energy-momentum in Einstein's theory and derive a
conformally flat perfect fluid solution of Einstein's field equations in three
dimensions.


title: Causal Sets: Discrete Gravity (Notes for the Valdivia Summer School)

abstract:
  These are lecture notes on causal set theory prepared in Jan. 2002 for a
Summer School in Valdivia, Chile. In some places, they are more complete, in
others much less so, regrettably. An extensive set of references and a glossary
of terms can be found at the end of the notes.


title:
Correspondence between the first and the second order formalism in the
  generalized gravity of f(R)-type

abstract:
  We clarify the correspondence between the first order formalism and the
second order formalism in the generalized gravity where the Lagrangian density
is given by a function of the scalar curvature f(R).


title: ASTROD, ASTROD I and their gravitational-wave sensitivities

abstract:
  ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) is a
mission concept with three spacecraft -- one near L1/L2 point, one with an
inner solar orbit and one with an outer solar orbit, ranging coherently with
one another using lasers to test relativistic gravity, to measure the solar
system and to detect gravitational waves. ASTROD I with one spacecraft ranging
optically with ground stations is the first step toward the ASTROD mission. In
this paper, we present the ASTROD I payload and accelerometer requirements,
discuss the gravitational-wave sensitivities for ASTROD and ASTROD I, and
compare them with LISA and radio-wave PDoppler-tracking of spacecraft.


title:
Frequency domain interferometer simulation with higher-order spatial
  modes

abstract:
  FINESSE is a software simulation that allows to compute the optical
properties of laser interferometers as they are used by the interferometric
gravitational-wave detectors today. It provides a fast and versatile tool which
has proven to be very useful during the design and the commissioning of
gravitational-wave detectors. The basic algorithm of FINESSE numerically
computes the light amplitudes inside an interferometer using Hermite-Gauss
modes in the frequency domain. In addition, FINESSE provides a number of
commands to easily generate and plot the most common signals like, for example,
power enhancement, error or control signals, transfer functions and
shot-noise-limited sensitivities.
  Among the various simulation tools available to the gravitational wave
community today, FINESSE is the most advanced general optical simulation that
uses the frequency domain. It has been designed to allow general analysis of
user defined optical setups while being easy to install and easy to use.


title:
Comment on gr-qc/0309003: ``Comment on `Absence of trapped surfaces and
  singularities in cylindrical collapse' ''

abstract:
  Very recently, a ``Comment'' by Wang [gr-qc/0309003] on a paper by
Gon\c{c}alves [Phys. Rev. D {\bf 65}, 084045 (2002)] appeared, claiming that
Gon\c{c}alves' analysis of trapped surfaces in certain kinds of cylindrical
spacetimes was incomplete. Specifically, Wang claims to have found a coordinate
extension of the spacetime used by Gon\c{c}alves (the Einstein-Rosen spacetime)
which contains trapped surfaces; in addition, Wang also claims that some such
trapped surfaces are apparent horizons. Here, I comment on Wang's ``Comment'',
and argue that, while Wang's spacetime extension appears to exist and contain
trapped surfaces, it does not render Gon\c{c}alves' results incomplete in the
sense Wang claims. I also show that, contrary to Wang's claim, his spacetime
extension does {\em not} contain apparent horizons, i.e., it does not contain
outer marginally trapped surfaces which are the outer boundary of a trapped
region. Further peripheral comments by Wang are also commented on.


title:
Explanation of the anomalous acceleration of a free moving body in the
  frame of extended space model

abstract:
  We consider (1+4) generalization of classical electrodynamics including
gravitation field. With this approach it is assumed a presence of an extra
component of extended field stress tensor, whose physical interpretation is
based on necessity to obtain Newton gravity law as particular case. In model
analyzed in present work mass of having in 4D a rest mass particle moves in
five-dimensional space-time along fifth coordinate with light velocity and its
electric charge is a stationary value in additional dimension. Generalized
gravity law that is obtained from extended Maxwell equations confirmed by
existence of variable component of Pioneer 10 additional acceleration, whose
analyze is made in frame of this model.


title: Higher order gravity theories and scalar tensor theories

abstract:
  We generalize the known equivalence between higher order gravity theories and
scalar tensor theories to a new class of theories. Specifically, in the context
of a first order or Palatini variational principle where the metric and
connection are treated as independent variables, we consider theories for which
the Lagrangian density is a function f of (i) the Ricci scalar computed from
the metric, and (ii) a second Ricci scalar computed from the connection. We
show that such theories can be written as tensor-multi-scalar theories with two
scalar fields with the following features: (i) the two dimensional sigma-model
metric that defines the kinetic energy terms for the scalar fields has
constant, negative curvature; (ii) the coupling function determining the
coupling to matter of the scalar fields is universal, independent of the choice
of function f; and (iii) if both mass eigenstates are long ranged, then the
Eddington post-Newtonian parameter has value 1/2. Therefore in order to be
compatible with solar system experiments at least one of the mass eigenstates
must be short ranged.


title: Does asymptotic simplicity allow for radiation near spatial infinity?

abstract:
  A representation of spatial infinity based in the properties of conformal
geodesics is used to obtain asymptotic expansions of the gravitational field
near the region where null infinity touches spatial infinity. These expansions
show that generic time symmetric initial data with an analytic conformal metric
at spatial infinity will give rise to developments with a certain type of
logarithmic singularities at the points where null infinity and spatial
infinity meet. These logarithmic singularities produce a non-smooth null
infinity. The sources of the logarithmic singularities are traced back down to
the initial data. It is shown that is the parts of the initial data responsible
for the non-regular behaviour of the solutions are not present, then the
initial data is static to a certain order. On the basis of these results it is
conjectured that the only time symmetric data sets with developments having a
smooth null infinity are those which are static in a neighbourhood of infinity.
This conjecture generalises a previous conjecture regarding time symmetric,
conformally flat data. The relation of these conjectures to Penrose's proposal
for the description of the asymptotic gravitational field of isolated bodies is
discussed.


title: The Post-Newtonian Maclaurin Spheroids to Arbitrary Order

abstract:
  In this paper, we develop an iterative scheme to enable the explicit
calculation of an arbitrary post-Newtonian order for a relativistic body that
reduces to the Maclaurin spheroid in the appropriate limit. This scheme allows
for an analysis of the structure of the solution in the vicinity of bifurcation
points along the Maclaurin sequence. The post-Newtonian expansion is solved
explicitly to the fourth order and its accuracy and convergence are studied by
comparing it to highly accurate numerical results.


title: Quasinormal modes prefer supersymmetry ?

abstract:
  One ambiguity in loop quantum gravity is the appearance of a free parameter
which is called Immirzi parameter. Recently Dreyer has argued that this
parameter may be fixed by considering the quasinormal mode spectrum of black
holes, while at the price of changing the gauge group to SO(3) rather than the
original one SU(2). Physically such a replacement is not quite natural or
desirable. In this paper we study the relationship between the black hole
entropy and the quasi normal mode spectrum in the loop quantization of N=1
supergravity. We find that a single value of the Immirzi parameter agrees with
the semiclassical expectations as well. But in this case the lowest
supersymmetric representation dominates, fitting well with the result based on
statistical consideration. This suggests that, so long as fermions are included
in the theory, supersymemtry may be favored for the consistency of the low
energy limit of loop quantum gravity.


title: The force exerting on cosmic bodies in a quaternionc field

abstract:
  The expression of a time-dependent cosmological constant $\lambda \propto
1/t^2$ is interpreted as the energy density of a special type of the
quaternionic field. The Lorenz-like force acting on the moving body in the
presence of this quaternionic field is determined. The astronomical and
terrestrial effects of this field are presented, and the ways how it can be
observably detected is discussed. Finally, a new mechanism of the particle
creation and an alternative cosmological scenario in the presence of the cosmic
quatertionic field is suggested.


title: The Relative Space: Space Measurements on a Rotating Platform

abstract:
  We introduce here the concept of relative space, an extended 3-space which is
recognized as the only space having an operational meaning in the study of the
space geometry of a rotating disk. Accordingly, we illustrate how space
measurements are performed in the relative space, and we show that an old-aged
puzzling problem, that is the Ehrenfest's paradox, is explained in this purely
relativistic context. Furthermore, we illustrate the kinematical origin of the
tangential dilation which is responsible for the solution of the Ehrenfest's
paradox.


title: S-matrices for spinor particles on Reissner-Nordstr\"{o}m black holes

abstract:
  The scattering problems arising when considering the contribution of the
topologically inequivalent configurations of the spinors on
Reissner-Nordstr\"{o}m black holes to the Hawking radiation are correctly
stated. The corresponding $S$-matrices are described and presented in the form
convenient to numerical computations.


title: Zero temperature black holes and the failure of semi-classical analysis

abstract:
  The extreme Reissner-Nordstr\"om black holes have zero surface gravity.
However, a semi-classical analysis seems to be ill-definite for these objects
and apparently no notion of temperature exists for them. It is argued here that
these properties are shared for all kind of black holes whose surface gravity
is zero. Two examples are worked out explicitely: the scalar-tensor cold black
holes and extreme black holes resulting from a gravity system coupled to a
generalized Maxwell field in higher dimensions. The reasons for this anomolous
behaviour are discussed as well as its thermodynamics implications.


title:
On a modified-Lorentz-transformation based gravity model confirming
  basic GRT experiments

abstract:
  Implementing Poincar\'e's `geometric conventionalism' a scalar
Lorentz-covariant gravity model is obtained based on gravitationally modified
Lorentz transformations (or GMLT). The modification essentially consists of an
appropriate space-time and momentum-energy scaling ("normalization") relative
to a nondynamical flat background geometry according to an isotropic,
nonsingular gravitational `affecting' function Phi(r). Elimination of the
gravitationally `unaffected' S_0 perspective by local composition of space-time
GMLT recovers the local Minkowskian metric and thus preserves the invariance of
the locally observed velocity of light. The associated energy-momentum GMLT
provides a covariant Hamiltonian description for test particles and photons
which, in a static gravitational field configuration, endorses the four `basic'
experiments for testing General Relativity Theory: gravitational i) deflection
of light, ii) precession of perihelia, iii) delay of radar echo, iv) shift of
spectral lines. The model recovers the Lagrangian of the Lorentz-Poincar\'e
gravity model by Torgny Sj\"odin and integrates elements of the precursor
gravitational theories, with spatially Variable Speed of Light (VSL) by
Einstein and Abraham, and gravitationally variable mass by Nordstr\"om.


title:
Geometric equations of state in Friedmann-Lema\^{i}tre universes
  admitting matter and Ricci Collineations

abstract:
  As a rule in General Relativity the spacetime metric fixes the Einstein
tensor and through the Field Equations (FE) the energy-momentum tensor. However
one cannot write the FE explicitly until a class of observers has been
considered. Every class of observers defines a decomposition of the
energy-momentum tensor in terms of the dynamical variables energy density
($\mu$), the isotropic pressure ($p$), the heat flux $q^a$ and the traceless
anisotropic pressure tensor $\pi_{ab}$. The solution of the FE requires
additional assumptions among the dynamical variables known with the generic
name equations of state. These imply that the properties of the matter for a
given class of observers depends not only on the energy-momentum tensor but on
extra a priori assumptions which are relevant to that particular class of
observers. This makes difficult the comparison of the Physics observed by
different classes of observers for the {\it same} spacetime metric. One way to
overcome this unsatisfactory situation is to define the extra condition
required among the dynamical variables by a geometric condition, which will be
based on the metric and not to the observers. Among the possible and multiple
conditions one could use the consideration of collineations. We examine this
possibility for the Friedmann-Lema\^{i}tre-Robertson-Walker models admitting
matter and Ricci collineations and determine the equations of state for the
comoving observers. We find linear and non-linear equations of state, which
lead to solutions satisfying the energy conditions, therefore describing
physically viable cosmological models.


title: Higher Dimensional Cosmological Models: the View from Above

abstract:
  A broader perspective is suggested for the study of higher dimensional
cosmological models. [1986: Considerations involving the Einstein constraints
and the Ricci form of the evolution equations for spatially homogeneous
spacetimes in 4 or more dimensions in the Taub time gauge (constant densitized
lapse) are used to show how many of the special exact solutions found at random
fit together into a larger picture in which the Taub spacetime solution plays
an instructive role. Concludes with some remarks on chaos.]


title: Universal canonical black hole entropy

abstract:
  Non-rotating black holes in three and four dimensions are shown to possess a
canonical entropy obeying the Bekenstein-Hawking area law together with a
leading correction (for large horizon areas) given by the logarithm of the area
with a {\it universal} finite negative coefficient, provided one assumes that
the quantum black hole mass spectrum has a power law relation with the quantum
area spectrum found in Non-perturbative Canonical Quantum General Relativity.
The thermal instability associated with asymptotically flat black holes appears
in the appropriate domain for the index characterising this power law relation,
where the canonical entropy (free energy) is seen to turn complex.


title: Exact Cosmological Solutions of Gravitational Theories

abstract:
  A global picture is drawn tying together most exact cosmological solutions of
gravitational theories in four or more spacetime dimensions.


title: Boucles et Mousses de Spin en Gravite Quantique

abstract:
  I review the formalism of loop quantum gravity, in both its real and complex
formulations, and spin foam theory which is its path integral counterpart. Spin
networks for non-compact groups are introduced (following hep-th/0205268) to
deal with gauge invariant structures based on the Lorentz group. The whole
formalism is studied in details in three dimensions in both its canonical
formulation (loop gravity) and its spin foam formulation. The main output
(following gr-qc/0212077) is the discreteness of timelike intervals and the
continuous character of spacelike distances even at the quantum level. Then it
is explained how to extend these considerations to the 4-dimensional case. I
review the Barrett-Crane model, its geometrical interpretation, its link with
general relativity and the role of causality. It is shown to be the history
formulation of a covariant canonical formulation of loop gravity (following
gr-qc/0209105), whose link with standard loop quantum gravity is discussed.
Similarly to the 3d case, spacelike areas turn out continuous. Finally, ways of
extracting informations from the non-perturbative spin foam structures are
discussed.


title:
Global symmetries: matter from geometry, hoop conjecture, and cosmic
  censorship

abstract:
  We show that four-dimensional Lorentzian metrics admitting a global spacelike
Lie group of isometries, $G_{1}={\mathbb R}$, which obey the Einstein equations
for vacuum and certain types of matter, cannot contain apparent horizons. The
assumed global isometry allows for the dimensional reduction of the (3+1)
system to a (2+1) picture, wherein the four-dimensional metric fields act
formally as matter fields. A theorem by Ida allows one to check for the absence
of apparent horizons in the dimensionally reduced spacetime, with the
four-dimensional results following from the topological product nature of the
corresponding manifold. We argue that the absence of apparent horizons in
spacetimes with translational symmetry constitutes strong evidence for the
validity of the hoop conjecture, and also hints at possible (albeit arguably
unlikely) generic violations of strong cosmic censorship.


title: Godel brane

abstract:
  We consider the brane-world generalisation of the Godel universe and analyse
its dynamical interaction with the bulk. The exact homogeneity of the standard
Godel spacetime no longer holds, unless the bulk is also static. We show how
the anisotropy of the Godel-type brane is dictated by that of the bulk and find
that the converse is also true. This determines the precise evolution of the
nonlocal anisotropic stresses, without any phenomenological assumptions, and
leads to a self-consistent closed set of equations for the evolution of the
Godel brane. We also examine the causality of the Godel brane and show that the
presence of the bulk cannot prevent the appearance of closed timelike curves.


title: Time dependence of c and its concomitants

abstract:
  As we showed in a preceding arXiv:gr-qc Einstein equations, conveniently
written, provide the more orthodox and simple description of cosmological
models with a time dependent speed of light $c$. We derive here the concomitant
dependence of the electric permittivity $\epsilon$, the magnetic permeability
$\mu$, the unit of charge $e$, Plank's constant $h$, under the assumption of
the constancy of the fine structure constant $\alpha$, and the masses of
elementary particles $m$. As a consequence of these concomitant dependences on
time they remain constant their ratios $e/m$ as well as their Compton wave
length $\lambda_c$ and their classical radius $r_0$.


title:
Gravitational Energy Loss and Binary Pulsars in the Scalar Ether-Theory
  of Gravitation

abstract:
  Motivation is given for trying a theory of gravity with a preferred reference
frame (``ether'' for short). One such theory is summarized, that is a scalar
bimetric theory. Dynamics is governed by an extension of Newton's second law.
In the static case, geodesic motion is recovered together with Newton's
attraction field. In the static spherical case, Schwarzschild's metric is got.
An asymptotic scheme of post-Minkowskian (PM) approximation is built by
associating a conceptual family of systems with the given weakly-gravitating
system. It is more general than the post-Newtonian scheme in that the velocity
may be comparable with $c$. This allows to justify why the 0PM approximation of
the energy rate may be equated to the rate of the Newtonian energy, as is
usually done. At the 0PM approximation of this theory, an isolated system loses
energy by quadrupole radiation, without any monopole or dipole term. It seems
plausible that the observations on binary pulsars (the pulse data) could be
nicely fitted with a timing model based on this theory.


title:
On the Stability of Circular Orbits of Particles Moving around Black
  Holes Surrounded by Axially Symmetric Structures

abstract:
  The Rayleigh criterion is used to study the stability of circular orbits of
particles moving around static black holes surrounded by different axially
symmetric structures with reflection symmetry, like disks, rings and halos. We
consider three models of disks one of infinite extension and two finite, and
one model of rings. The halos are represented by external quadrupole moments
(either oblate or prolate). Internal quadrupole perturbation (oblate and
prolate) are also considered. For this class of disks the counter-rotation
hypothesis implies that the stability of the disks is equivalent to the
stability of test particles. The stability of Newtonian systems is also
considered and compared with the equivalent relativistic situation. We find
that the general relativistic dynamics favors the formation of rings.


title:
Ricci and matter collineations of locally rotationally symmetric
  space-times

abstract:
  A new method is presented for the determination of Ricci Collineations (RC)
and Matter Collineations (MC) of a given spacetime, in the cases where the
Ricci tensor and the energy momentum tensor are non-degenerate and have a
similar form with the metric. This method reduces the problem of finding the
RCs and the MCs to that of determining the KVs whereas at the same time uses
already known results on the motions of the metric. We employ this method to
determine all hypersurface homogeneous locally rotationally symmetric
spacetimes, which admit proper RCs and MCs. We also give the corresponding
collineation vectors.


title:
Isotropic Loop Quantum Cosmology with Matter II: The Lorentzian
  Constraint

abstract:
  The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum
cosmology coupled to a massless scalar field. As in the Euclidean case, the
discreteness of quantum geometry removes the classical singularity from the
quantum Friedmann models. In spite of the absence of the classical singularity,
a modified DeWitt initial condition is incompatible with a late-time smooth
behavior. Further, the smooth behavior is recovered only for positive or
negatives times but not both. An important feature, which is shared with the
Euclidean case, is a minimal initial energy of the order of the Planck energy
required for the system to evolve dynamically. By forming wave packets of the
matter field an explicit evolution in terms of an internal time is obtained.


title:
On the problem of cosmological singularity within gauge theories of
  gravitation

abstract:
  In this note I discuss the problem of cosmological singularities within gauge
theories of gravitation. Solutions of cosmological equations with the scalar
field are considered.


title: Correct Quantization Modes of Free Fields in Schwarzschild Spacetime

abstract:
  This paper has been withdrawn, because the result turned out to be well
known.


title:
Solutions of all one-dimensional wave equations with time independent
  potential and separable variables

abstract:
  Exact solutions, in terms of special functions, of all wave equations $%
u_{xx} - u_{tt} = V(x) u(t,x)$, characterised by eight inequivalent time
independent potentials and by variable separation, have been found. The real
valueness of the solutions from computer algebra programs is not always
manifest and in this work we provide ready to use solutions. We discussed
especially the potential $\cosh^{-2}x (m_1 + m_2 \sinh x)$. Such potential
approximates the Schwarzschild black hole potential for even parity.


title:
Perturbation method in the assessment of radiation reaction in the
  capture of stars by black holes

abstract:
  This work deals with the motion of a radially falling star in Schwarzschild
geometry and correctly identifies radiation reaction terms by the perturbative
method. The results are: i) identification of all terms up to first order in
perturbations, second in trajectory deviation, and mixed terms including lowest
order radiation reaction terms; ii) renormalisation of all divergent terms by
the $\zeta$ Riemann and Hurwitz functions. The work implements a method
previously identified by one of the authors and corrects some current
misconceptions and results.


title: Quantization of Gravitational System and its Cosmological Consequences

abstract:
  We have found that the hierarchial problems appearing in cosmology is a
manifestation of the quantum nature of the universe. The universe is still
described by the same formulae that once hold at Planck's time. The universe is
found to be governed by the Machian equation, $G M=Rc^2$, where $M$ and $R$ are
mass and radius of the universe. A Planck's constant for different cosmic
scales is provided. The status of the universe at different stages is shown to
be described in terms of the fundamental constants (eg. \textcolor{blue}{$c,
\hbar, G, \Lambda, H$}) only. The concept of maximal (minimal) acceleration,
power, temperature, etc., is introduced and justified. The electromagnetic
interactions are shown to be active at a cosmic level. Their contribution would
exclude the inclusion of dark energy in cosmology.


title: Renormalizable Quantum Gauge General Relativity

abstract:
  The quantum gauge general relativity is proposed in the framework of quantum
gauge theory of gravity. It is formulated based on gauge principle which states
that the correct symmetry for gravitational interactions should be
gravitational gauge symmetry. The gravitational gauge group is studied in the
paper. Then gravitational gauge interactions of pure gravitational gauge field
is studied. It is found that the field equation of gravitational gauge field is
just the Einstein's field equation. After that, the gravitational interactions
of scalar field, Dirac field and vector fields are studied, and unifications of
fundamental interactions are discussed. Path integral quantization of the
theory is studied in the paper. The quantum gauge general relativity discussed
in this paper is a perturbatively renormalizable quantum gravity, which is one
of the most important advantage of the quantum gauge general relativity
proposed in this paper. A strict proof on the renormalizability of the theory
is also given in this paper. Another important advantage of the quantum gauge
general relativity is that it can explain both classical tests of gravity and
quantum effects of gravitational interactions, such as gravitational phase
effects found in COW experiments and gravitational shielding effects found in
Podkletnov experiments. For all classical effects of gravitational
interactions, such as classical tests of gravity and cosmological model,
quantum gauge general relativity gives out the same theoretical predictions as
that of the Einstein's general relaitvity.


title: Quantum Perfect-Fluid Kaluza-Klein Cosmology

abstract:
  The perfect fluid cosmology in the 1+d+D dimensional Kaluza-Klein spacetimes
for an arbitrary barotropic equation of state $p= n \rho$ is quantized by using
the Schutz's variational formalism. We make efforts in the mathematics to solve
the problems in two cases. For the first case of the stiff fluid $n=1$ we
exactly solve the Wheeler-DeWitt equation when the $d$ space is flat. After the
superposition of the solutions we analyze the Bohmian trajectories of the
final-stage wave-packet functions and show that the flat $d$ spaces and the
compact $D$ spaces will eventually evolve into finite scale functions. For the
second case of $n \approx 1$, we use the approximated wavefunction in the
Wheeler-DeWitt equation to find the analytic forms of the final-stage
wave-packet functions. After analyzing the Bohmian trajectories we show that
the flat $d$ spaces will be expanding forever while the scale function of the
contracting $D$ spaces would not become zero within finite time. Our
investigations indicate that the quantum effect in the quantum perfect-fluid
cosmology could prevent the extra compact $D$ spaces in the Kaluza-Klein theory
from collapsing into a singularity or that the "crack-of-doom" singularity of
the extra compact dimensions is made to occur at $t=\infty$.


title: Tachyonic potential in Bianchi type-I universe

abstract:
  Motivated from recent string theoretic results, a tachyonic potential is
constructed for a spatially homogeneous and anisotropic background cosmology.


title: Holeum,enigmas of cosmology and gravitational waves

abstract:
  The principle of nuclear democracy is invoked to prove the formation of
stable quantized gravitational bound states of primordial black holes called
Holeums. The latter come in four varieties: ordinary Holeums H, Black Holeums
BH, Hyper Holeums HH and the massless Lux Holeums LH.These Holeums are
invisible because the gravitational radiation emitted by their quantum
transitions is undetectable now. The copiously produced Holeums form an
important component of the dark matter and the Lux Holeums an important
component of the dark energy in the universe. A segregation property puts the
Holeums mainly in the galactic haloes (GH) and the domain walls (DW) explaining
the latters' invisibility now. Cosmic rays (CR) are produced by two exploding
black holes created in a pressure-ionization of a stable Holeum. Our prediction
that more CRs will be emitted by the haloes than by the discs of galaxies
already has a strong empirical support. The concentration of the Hs and the HHs
in the GHs and the DWs lead to the formation of Holeum-stars emitting the CRs
and the gravitational waves(GW).Innumerable explosions of BHs at the time of
decoupling of gravity from the other interactions lead to inflation and baryon
asymmetry. A substantial cosmic back ground of matter and GWs and an
infra-quantum gravity (infra-QG) band and an ultra-QG band of GWs and their
emission frequencies are predicted. A unique quantum system containing
matter-energy oscillations is found.


title:
Various features of quasiequilibrium sequences of binary neutron stars
  in general relativity

abstract:
  Quasiequilibrium sequences of binary neutron stars are numerically calculated
in the framework of the Isenberg-Wilson-Mathews (IWM) approximation of general
relativity. The results are presented for both rotation states of synchronized
spins and irrotational motion, the latter being considered as the realistic one
for binary neutron stars just prior to the merger. We assume a polytropic
equation of state and compute several evolutionary sequences of binary systems
composed of different-mass stars as well as identical-mass stars with adiabatic
indices gamma=2.5, 2.25, 2, and 1.8. From our results, we propose as a
conjecture that if the turning point of binding energy (and total angular
momentum) locating the innermost stable circular orbit (ISCO) is found in
Newtonian gravity for some value of the adiabatic index gamma_0, that of the
ADM mass (and total angular momentum) should exist in the IWM approximation of
general relativity for the same value of the adiabatic index.


title: Dimensional Structure of Space-Time

abstract:
  The dimensional structure of space-time is investigated according to physical
and mathematical methods. We show that ther are various empirical and
theoretical restrictions on the number of independent dimensions of space-time,
consequently there is no physical and mathematical evidence for a space-time
with four independent dimensions.


title:
Response of the Brazilian gravitational wave detector to signals from a
  black hole ringdown

abstract:
  It is assumed that a black hole can be disturbed in such a way that a
ringdown gravitational wave would be generated. This ringdown waveform is well
understood and is modelled as an exponentially damped sinusoid. In this work we
use this kind of waveform to study the performance of the SCHENBERG
gravitational wave detector. This first realistic simulation will help us to
develop strategies for the signal analysis of this Brazilian detector. We
calculated the signal-to-noise ratio as a function of frequency for the
simulated signals and obtained results that show that SCHENBERG is expected to
be sensitive enough to detect this kind of signal up to a distance of $\sim
20\mathrm{kpc}$.


title: Global Hyperbolicity of Sliced Spaces

abstract:
  We show that for generic sliced spacetimes global hyperbolicity is equivalent
to space completeness under the assumption that the lapse, shift and spatial
metric are uniformly bounded. This leads us to the conclusion that simple
sliced spaces are timelike and null geodesically complete if and only if space
is a complete Riemannian manifold.


title:
Parametric phenomena of the particle dynamics in a periodic
  gravitational wave field

abstract:
  We establish exactly solvable models for the motion of neutral particles,
electrically charged point and spin particles (U(1) symmetry), isospin
particles (SU(2) symmetry), and particles with color charges (SU(3) symmetry)
in a gravitational wave background. Special attention is devoted to parametric
effects induced by the gravitational field. In particular, we discuss
parametric instabilities of the particle motion and parametric oscillations of
the vectors of spin, isospin, and color charge.


title:
Propagation of signals in spaces with affine connections and metrics as
  models of space-time

abstract:
  The propagation of signals in space-time is considered on the basis of the
notion of null (isotropic) vector field in spaces with affine connections and
metrics as models of space or of space-time. The Doppler effect is generalized
for these types of spaces. The notions of aberration, standard (longitudinal)
Doppler effect, and transversal Doppler effect are considered. On their
grounds, the Hubble effect appears as Doppler effect with explicit forms of the
centrifugal (centripetal) and Coriolis velocities and accelerations. Doppler
effect, Hubble effect, and aberration could be used in mechanics of continuous
media and in other classical field theories in the same way as the standard
Doppler effect is used in classical and relativistic mechanics.


title:
Centrifugal (centripetal) and Coriolis velocities and accelerations in
  spaces with affine connections and metrics as models of space-time

abstract:
  The notions of centrifugal (centripetal) and Coriolis velocities and
accelerations are introduced and considered in spaces with affine connections
and metrics used as models of space or of space-time. It is shown that these
types of velocities and accelerations are generated by the relative motions
between mass elements in a continuous media or of particles. The velocities and
accelerations are closely related to the kinematic characteristics of the
relative velocity and of the relative acceleration. The relation between the
centrifugal (centripetal) velocity and the Hubble law is found. The centrifugal
(centripetal) acceleration could be interpreted as gravitational acceleration
as it has been done in the Einstein theory of gravitation. This fact could be
used as a basis for working out of new gravitational theories in spaces with
affine connections and metrics.


title: Evolution of relativistic polytropes in the post--quasi--static regime

abstract:
  A recently presented method for the study of evolving self-gravitating
relativistic spheres is applied to the description of the evolution of
relativistic polytropes. Two different definitions of relativistic polytrope,
yielding the same Newtonian limit, are considered. Some examples are explicitly
worked out, describing collapsing polytropes and bringing out the differences
between both types of polytropes.