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gr-qc/9309019
Dirac spinor in a nonstationary Godel-type cosmological Universe
In the present article we solve, via separation of variables, the massless Dirac equation in a nonstationary rotating, causal G\"odel-type cosmological universe, having a constant rotational speed in all the points of the space. We compute the frequency spectrum. We show that the spectrum of massless Dirac particles is...
1993-09-16
2015-06-25
[ "gr-qc" ]
Victor M. Villalba
gr-qc/9309018
Exact Dirac Quantization of All 2-D Dilaton Gravity Theories
The most general dilaton gravity theory in 2 spacetime dimensions is considered. A Hamiltonian analysis is performed and the reduced phase space, which is two dimensional, is explicitly constructed in a suitable parametrization of the fields. The theory is then quantized via the Dirac method in a functional Schrodinger...
1993-09-15
2009-10-22
[ "gr-qc", "hep-th" ]
D. Louis- Martinez, J. Gegenberg, G. Kunstatter
gr-qc/9309016
The Collision of Two Black Holes
We study the head-on collision of two equal mass, nonrotating black holes. We consider a range of cases from holes surrounded by a common horizon to holes initially separated by about $20M$, where $M$ is the mass of each hole. We determine the waveforms and energies radiated for both the $\ell = 2$ and $\ell=4$ waves r...
1993-09-14
2016-08-31
[ "gr-qc" ]
Peter Anninos, David Hobill, Edward Seidel, Larry Smarr and Wai-Mo Suen
gr-qc/9309013
Exponential-Potential Scalar Field Universes I: The Bianchi I Models
We obtain a general exact solution of the Einstein field equations for the anisotropic Bianchi type I universes filled with an exponential-potential scalar field and study their dynamics. It is shown, in agreement with previous studies, that for a wide range of initial conditions the late-time behaviour of the models i...
1993-09-14
2010-11-01
[ "gr-qc" ]
J.M. Aguirregabiria, A. Feinstein and J. Ibanez
gr-qc/9309014
Exponential-Potential Scalar Field Universes II: The Inhomogeneous Models
We obtain exact solutions for the Einstein equations with an exponential-potential scalar field (\(V=\Lambda e^{k\phi}\)) which represent simple inhomogeneous generalizations of Bianchi I cosmologies. Studying these equations numerically we find that in most of the cases there is a certain period of inflationary behavi...
1993-09-14
2010-11-01
[ "gr-qc" ]
J.M. Aguirregabiria, A. Feinstein and J. Ibanez
gr-qc/9309015
Formation of Solitonic Stars Through Gravitational Cooling
We studied the formation of compact bosonic objects through a dissipationless cooling mechanism. Implications of the existence of this mechanism are discussed, including the abundance of bosonic stars in the universe, and the possibility of ruling out the axion as a dark matter candidate.
1993-09-14
2008-11-26
[ "gr-qc" ]
Edward Seidel and Wai-Mo Suen
gr-qc/9309017
Quantum Dynamics of Lorentzian Spacetime Foam
A simple spacetime wormhole, which evolves classically from zero throat radius to a maximum value and recontracts, can be regarded as one possible mode of fluctuation in the microscopic ``spacetime foam'' first suggested by Wheeler. The dynamics of a particularly simple version of such a wormhole can be reduced to that...
1993-09-14
2009-10-22
[ "gr-qc" ]
Ian Redmount and Wai-Mo Suen
gr-qc/9309011
Black Holes in Einstein-Lovelock Gravity
Static, spherically symmetric solutions of the field equations for a particular dimensional continuation of general relativity with negative cosmological constant are found. In even dimensions the solution has many similarities with the \Sch\ metric. In odd dimensions, the equations of motion are explicitly anti de-Sit...
1993-09-13
2008-02-03
[ "gr-qc", "hep-th" ]
Maximo Banados
gr-qc/9309009
Blackbody Distribution for Wormholes
By assuming that only (i) bilocal vertex operators which are diagonal with respect to the basis for local field operators, and (ii) the convergent elements with nonzero positive energy of the density matrix representing the quantum state of multiply-connected wormholes, contribute the path integral that describes the e...
1993-09-13
2016-08-14
[ "gr-qc" ]
P.F. Gonz\'alez-D\'iaz
gr-qc/9309012
Unitarity and Causality in Generalized Quantum Mechanics for Non-Chronal Spacetimes
Spacetime must be foliable by spacelike surfaces for the quantum mechanics of matter fields to be formulated in terms of a unitarily evolving state vector defined on spacelike surfaces. When a spacetime cannot be foliated by spacelike surfaces, as in the case of spacetimes with closed timelike curves, a more general fo...
1993-09-13
2009-10-22
[ "gr-qc", "hep-th" ]
James B. Hartle
gr-qc/9309008
Quantum State and Spontaneous Symmetry Breaking in Gravity
A spontaneous symmetry breaking mechanism is used in quantum gravity to obtain a convergent positive definite density-matrix as the most general quantum state of Euclidean wormholes
1993-09-13
2011-04-20
[ "gr-qc" ]
Pedro F. Gonzalez-Diaz
gr-qc/9309010
The Dispersion of Newton's Constant: A Transfer Matrix Formulation of Quantum Gravity
A transfer matrix formalism applicable to certain reparametrization invariant theories, including quantum gravity, is proposed. In this formulation it is found that every stationary state in quantum gravity satisfies a Wheeler-DeWitt equation, but each with a different value of the Planck mass; the value $m_{Planck}^4$...
1993-09-13
2009-10-22
[ "gr-qc", "hep-th" ]
J. Greensite
gr-qc/9309007
The Mixmaster Spacetime, Geroch's Transformation and Constants of Motion
We show that for $U(1)$-symmetric spacetimes on $S^3 \times R$ a constant of motion associated with the well known Geroch transformation, a functional $K[h_{ij},\pi^{ij}]$, quadratic in gravitational momenta, is strictly positive in an open subset of the set of all $U(1)$-symmetric initial data, and therefore not weakl...
1993-09-09
2009-10-22
[ "gr-qc" ]
Boro Grubisic and Vincent Moncrief
gr-qc/9309006
Physical States in d=3,N=2 Supergravity
To clarify some issues raised by D'Eath's recent proposal for the physical states of $N=1$ supergravity in four dimensions, we study pure (topological) $N=2$ supergravity in three dimensions, which is formally very similar, but much easier to solve. The wave functionals solving the quantum constraints can be understood...
1993-09-09
2009-10-22
[ "gr-qc" ]
B.de Wit (Utrecht University), H.J. Matschull and H. Nicolai (Hamburg University)
gr-qc/9309004
A Cosmological Constant Limits the Size of Black Holes
In a space-time with cosmological constant $\Lambda>0$ and matter satisfying the dominant energy condition, the area of a black or white hole cannot exceed $4\pi/\Lambda$. This applies to event horizons where defined, i.e. in an asymptotically deSitter space-time, and to outer trapping horizons (cf. apparent horizons) ...
1993-09-02
2009-10-22
[ "gr-qc" ]
Sean A. Hayward, Tetsuya Shiromizu & Ken-ichi Nakao
gr-qc/9309003
MATTERS OF GRAVITY, a newsletter for the gravity community, number 2
Table of contents: Editorial 1 Correspondents 3 Some recent work in general relativistic Astrophysics 4 Two dimensional black holes 6 Resonant-mass gravitational wave detectors: an update 8 Universality and scaling in gravitational collapse 9 Gravitational Wave memories upgraded 11 Conference report: qu...
1993-09-02
2007-05-23
[ "gr-qc" ]
Jorge Pullin (Editor)
gr-qc/9309001
Dynamical Origin of the Entropy of a Black Hole
Modes of physical fields which are located inside a horizon and which cannot be observed by a distant observer are identified with dynamical degrees of freedom of a black hole. A new invariant statistical mechanical definition of a black-hole's entropy is proposed. It is shown that the main contribution to the entropy ...
1993-09-02
2021-01-05
[ "gr-qc" ]
Valery Frolov and Igor Novikov
gr-qc/9309002
Notes on the (2+1)-Dimensional Wheeler-DeWitt Equation
In contrast to other approaches to (2+1)-dimensional quantum gravity, the Wheeler-DeWitt equation appears to be too complicated to solve explicitly, even for simple spacetime topologies. Nevertheless, it is possible to obtain a good deal of information about solutions and their interpretation. In particular, strong evi...
1993-09-02
2010-04-28
[ "gr-qc" ]
Steven Carlip
gr-qc/9309005
Wigner function and quantum kinetic theory in curved space-time and external fields
A new definition of the Wigner function for quantum fields coupled to curved space--time and an external Yang--Mills field is studied on the example of a scalar and a Dirac fields. The definition uses the formalism of the tangent bundles and is explicitly covariant and gauge invariant. Derivation of collisionless quant...
1993-09-02
2010-11-01
[ "gr-qc" ]
Oleg A. Fonarev
gr-qc/9308032
The Quantum Stress Tensor in the Three Dimensional Black Hole
The quantum stress tensor $<T_{\mu\nu}>$ is calculated in the 2+1 dimensional black hole found by Banados, Teitelboim, and Zanelli. The Greens function, from which $<T_{\mu\nu}> $ is derived, is obtained by the method of images. For the non-rotating black hole, it is shown that $<T_{\mu\nu}>$ is finite on the event hor...
1993-08-27
2016-08-31
[ "gr-qc", "hep-th" ]
Alan R. Steif
gr-qc/9308031
Local Structure of Numerically Generated Worm Hole Spacetime
We investigate the evolution of the apparent horizons in a numerically gererated worm hole spacetime. The behavior of the apparent horizons is affected by the dynamics of the matter field. By using the local mass of the system, we interpret the evolution of the worm hole structure. Figures are available by mail to auth...
1993-08-27
2007-05-23
[ "gr-qc", "astro-ph" ]
Yasusada Nambu and Masaru Siino
gr-qc/9308030
Fate of Inhomogeneity in Schwarzschild-deSitter Space-time
We investigate the global structure of the space time with a spherically symmetric inhomogeneity using a metric junction, and classify all possible types. We found that a motion with a negative gravitational mass is possible although the energy condition of the matter is not violated. Using the result, formation of bla...
1993-08-27
2010-11-19
[ "gr-qc", "astro-ph" ]
Yasusada Nambu
gr-qc/9308028
Selfgravitating Yang-Mills solitons and their Chern-Simons numbers
We present a classification of the possible regular, spherically symmetric solutions of the Einstein-Yang-Mills system which is based on a bundle theoretical analysis for arbitrary gauge groups. It is shown that such solitons must be of magnetic type, at least if the magnetic Yang-Mills charge vanishes. Explicit expres...
1993-08-26
2010-11-01
[ "gr-qc" ]
O. Brodbeck and N. Straumann
gr-qc/9308029
Quantum Fluctuations of Black Hole Geometry
By using the minisuperspace model for the interior metric ofstatic black holes, we solve the Wheeler-DeWitt equation to study quantum mechanics of the horizon geometry. Our basic idea is to introduce the gravitational mass and the expansions of null rays as quantum operators. Then, the exact wave function is found as a...
1993-08-26
2017-02-01
[ "gr-qc", "hep-th" ]
K.Nakamura, S.Konno, Y.Shiro, A.Tomimatsu
gr-qc/9308026
Nicolai Maps for Quantum Cosmology
We construct Nicolai maps for $N=2$ supersymmetric extensions of minisuperspace models. It is shown that Nicolai maps exist for only a very restricted set of states. In the models considered these are the two states corresponding to the empty and the filled fermion sectors. The form of the Nicolai maps in these sectors...
1993-08-24
2009-10-22
[ "gr-qc" ]
R. Graham and H. Luckock
gr-qc/9308027
New Types of Thermodynamics from $(1+1)$-Dimensional Black Holes
For normal thermodynamic systems superadditivity $\S$, homogeneity $\H$ and concavity $\C$ of the entropy hold, whereas for $(3+1)$-dimensional black holes the latter two properties are violated. We show that $(1+1)$-dimensional black holes exhibit qualitatively new types of thermodynamic behaviour, discussed here for ...
1993-08-24
2010-04-06
[ "gr-qc" ]
P.T. Landsberg and R.B. Mann
gr-qc/9308025
Quantum cosmology and the emergence of a classical world
This paper gives an elementary introduction to some of the conceptual problems of quantum cosmology. Contents: 1. Why quantum cosmology? 2. Time in quantum gravity 3.Decoherence and the recovery of the Schrodinger equation 4. The direction of time
1993-08-23
2009-09-25
[ "gr-qc" ]
C. Kiefer
gr-qc/9308024
Quantum Gravity and Non-unitarity in Black Hole Evaporation
We discuss the relevance of quantum gravitational corrections to the functional Schr\"odinger equation for the information loss paradox in black hole evaporation. These corrections are found from the Wheeler-DeWitt equation through a semiclassical expansion scheme. The dominant contribution in the final evaporation sta...
1993-08-23
2010-11-01
[ "gr-qc", "hep-th" ]
Claus Kiefer, Rainer Mueller, and Tejinder P. Singh
gr-qc/9308023
Energy Radiation of Charged Particles in Conformally Flat Spacetimes
Original abstract: Consider the worldline of a charged particle in a static spacetime. Contraction of the time-translation Killing field with the retarded electromagnetic energy-momentum tensor gives a conserved electromagnetic energy vector which can be used to define the radiated electromagnetic energy. This note poi...
1993-08-22
2008-02-03
[ "gr-qc" ]
Stephen Parrott
gr-qc/9308022
Multiplicative Noise: Applications in Cosmology and Field Theory
Physical situations involving multiplicative noise arise generically in cosmology and field theory. In this paper, the focus is first on exact nonlinear Langevin equations, appropriate in a cosmologica setting, for a system with one degree of freedom. The Langevin equations are derived using an appropriate time-depende...
1993-08-21
2009-10-22
[ "gr-qc", "hep-th" ]
Salman Habib
gr-qc/9308020
Quantum mechanical composition laws in reparameterization invariant systems
This paper gives a brief description of the derivation of a composition law for the propagator of a relativistic particle, in a sum over histories quantization. The extension of this derivation to the problem of finding a composition law for quantum cosmology is also discussed. (For the proceedings of Journees Relativi...
1993-08-20
2011-04-15
[ "gr-qc", "hep-th" ]
J.J.Halliwell and M.E.Ortiz
gr-qc/9308021
Integrals of Motion in the Two Killing Vector Reduction of General Relativity
We apply the inverse scattering method to the midi-superspace models that are characterized by a two-parameter Abelian group of motions with two spacelike Killing vectors. We present a formulation that simplifies the construction of the soliton solutions of Belinski\v i and Zakharov. Furthermore, it enables us to obtai...
1993-08-20
2010-11-01
[ "gr-qc" ]
Nenad Manojlovi\'c and Bill Spence
gr-qc/9308019
Particle Creation in a universe filled by radiation and dust-like matter
In this article the particle creation process of scalar and spin 1/2 particles in a spatially open cosmological model associated with a universe filled by radiation and dustlike matter. The Klein-Gordon and Dirac equations are solved via separation of variables. After comparing the{\it \ in }and% {\it \ out} vacua, we ...
1993-08-19
2017-02-01
[ "gr-qc" ]
Victor M. Villalba
gr-qc/9308017
On the mechanism of trapped surface formation
By a combination of analytical and numerical methods, the density profile of a momentarily at rest spherical star is varied, and the corresponding response in the area of the spherical shells is monitored. It is shown that the inner apparent horizon (if it exists) must lie within or at most on the star's surface, while...
1993-08-19
2009-10-22
[ "gr-qc", "astro-ph" ]
David Valls-Gabaud and Thomas Zannias
gr-qc/9308018
Solution space of 2+1 gravity on ${\bf R} \times T^2$ in Witten's connection formulation
We investigate the space ${\cal M}$ of classical solutions to Witten's formulation of 2+1 gravity on the manifold ${\bf R} \times T^2$. ${\cal M}$ is connected, unlike the spaces of classical solutions in the cases where $T^2$ is replaced by a higher genus surface. Although ${\cal M}$ is neither Hausdorff nor a manifol...
1993-08-19
2010-04-06
[ "gr-qc", "hep-th" ]
Jorma Louko and Donald M. Marolf
gr-qc/9308016
How to determine approximate Mixmaster parameters from numerical evolution of Einstein's equations
To assess the validity of the Belinskii, Khalatnikov, and Lifshitz (BKL) approximation to Mixmaster dynamics, it would be useful to evaluate the BKL discrete parameters as a byproduct of the numerical solution of Einstein's equations. An algorithm to do this and results for a typical trajectory are presented.
1993-08-17
2009-10-22
[ "gr-qc" ]
Beverly K. Berger
gr-qc/9308015
The use of exp(iS[x]) in the sum over histories
The use of $\sum \exp(iS[x])$ as the generic form for a sum over histories in configuration space is discussed critically and placed in its proper context. The standard derivation of the sum over paths by discretizing the paths is reviewed, and it is shown that the form $\sum \exp(iS[x])$ is justified only for Schrodin...
1993-08-17
2009-10-22
[ "gr-qc", "hep-th" ]
Arlen Anderson
gr-qc/9308014
No New Symmetries of the Vacuum Einstein Equations
In this note we examine some recently proposed solutions of the linearized vacuum Einstein equations. We show that such solutions are {\it not} symmetries of the Einstein equations, because of a crucial integrability condition.
1993-08-16
2009-10-22
[ "gr-qc" ]
Riccardo Capovilla
gr-qc/9308013
Did the Pseudo-Sphere Universe have a Beginning?
A calculation of the no-boundary wave-function of the universe is put forward for a spacetime with negative curvature. A semi-classical Robertson-Walker approximation is attempted and two solutions to the field equations, one Lorentzian and the other a tunneling one are found. The regularity of those solutions are anal...
1993-08-12
2007-05-23
[ "gr-qc" ]
G. Oliveira-Neto
gr-qc/9308012
Why is Spacetime Lorentzian?
We expand on the idea that spacetime signature should be treated as a dynamical degree of freedom in quantum field theory. It has been argued that the probability distribution for signature, induced by massless free fields, is peaked at the Lorentzian value uniquely in D=4 dimensions. This argument is reviewed, and cer...
1993-08-12
2009-10-22
[ "gr-qc", "hep-th" ]
A. Carlini and J. Greensite
gr-qc/9308010
Exact Superstring Motivated Cosmological Models
We present a number of new, exact scalar field cosmologies where the potential consists of two or more exponential terms. Such potentials are motivated by supergravity or superstring models formulated in higher dimensional spacetimes that have been compactified to (3+1)-dimensions. We have found solutions in both curve...
1993-08-11
2010-04-06
[ "gr-qc", "astro-ph" ]
Richard Easther
gr-qc/9308011
Squeezed States and Uncertainty Relation at Finite Temperature
We use the quantum Brownian model to derive the uncertainty relation for a quantum open system in an arbitrarily-squeezed initial state interacting with an environment at finite temperature. We examine the relative importance of the quantum and thermal fluctuations in the evolution of the system towards equilibrium wit...
1993-08-11
2019-06-05
[ "gr-qc", "hep-th" ]
B. L. Hu and Yuhong Zhang (Univ. of Maryland)
gr-qc/9308009
The Quantum Propagator for a Nonrelativistic Particle in the Vicinity of a Time Machine
We study the propagator of a non-relativistic, non-interacting particle in any non-relativistic ``time-machine'' spacetime of the type shown in Fig.~1: an external, flat spacetime in which two spatial regions, $V_-$ at time $t_-$ and $V_+$ at time $t_+$, are connected by two temporal wormholes, one leading from the pas...
1993-08-10
2009-10-22
[ "gr-qc", "astro-ph", "hep-th" ]
Dalia S. Goldwirth, Malcolm J. Perry, Tsvi Piran and Kip S. Thorne
gr-qc/9308008
Properties of 3-manifolds for relativists
In canonical quantum gravity certain topological properties of 3-manifolds are of interest. This article gives an account of those properties which have so far received sufficient attention, especially those concerning the diffeomorphism groups of 3-manifolds. We give a summary of these properties and list some old and...
1993-08-09
2015-06-25
[ "gr-qc" ]
Domenico Giulini
gr-qc/9308006
Quantum Logic and the Histories Approach to Quantum Theory
An extended analysis is made of the Gell-Mann and Hartle axioms for a generalised `histories' approach to quantum theory. Emphasis is placed on finding equivalents of the lattice structure that is employed in standard quantum logic. Particular attention is given to `quasi-temporal' theories in which the notion of time-...
1993-08-09
2009-10-22
[ "gr-qc", "hep-th" ]
C.J.Isham (Imperial College)
gr-qc/9308007
Quantum Measurement, Gravitation, and Locality
This essay argues that when measurement processes involve energies of the order of the Planck scale, the fundamental assumption of locality may no longer be a good approximation. Idealized position measurements of two distinguishable spin-$0$ particles are considered. The measurements alter the space-time metric in a f...
1993-08-09
2008-11-26
[ "gr-qc", "hep-th" ]
D. V. Ahluwalia
gr-qc/9308005
Aspects of the Decoherent Histories Approach to Quantum Mechanics
I give an informal overview of the decoherent histories approach to quantum mechanics, due to Griffiths, to Omn\`es, and to Gell-Mann and Hartle is given. Results on the connections between decoherence, records, correlation and entropy are described. The emphasis of the presentation is on understanding the broader mean...
1993-08-06
2007-05-23
[ "gr-qc" ]
J. J. Halliwell
gr-qc/9308003
Recollapse of the closed Tolman spacetimes
The closed-universe recollapse conjecture is studied for the spherically symmetric spacetimes. It is proven that there exists an upper bound to the lengths of timelike curves in any Tolman spacetime that possesses $S^3$ Cauchy surfaces and whose energy density is positive. Furthermore, an explicit bound is constructed ...
1993-08-05
2009-10-22
[ "gr-qc" ]
Gregory A. Burnett
gr-qc/9308004
The Stability of the Minisuperspace
The stability of the minisuperspace model of the early universe is studied by solving the Wheeler-DeWitt equation numerically. We consider a system of Einstein gravity with a scalar field. When we solve the Wheeler-DeWitt equation, we pick up some inhomogeneous wave modes from the infinite number of modes adequately: d...
1993-08-05
2009-10-22
[ "gr-qc" ]
Atushi Ishikawa and Toshiki Isse
gr-qc/9308002
The physical hamiltonian in nonperturbative quantum gravity
A quantum hamiltonian which evolves the gravitational field according to time as measured by constant surfaces of a scalar field is defined through a regularization procedure based on the loop representation, and is shown to be finite and diffeomorphism invariant. The problem of constructing this hamiltonian is reduced...
1993-08-05
2011-09-30
[ "gr-qc" ]
Carlo Rovelli and Lee Smolin
gr-qc/9308001
Bianchi Cosmologies: New Variables and a Hidden Supersymmetry
We find a supersymmetrization of the Bianchi IX cosmology in terms of Ashtekar's new variables. This provides a framework for connecting the recent results of Graham and those of Ryan and Moncrief for quantum states of this model. These states are also related with the states obtained particularizing supergravity for a...
1993-08-04
2009-10-22
[ "gr-qc" ]
Octavio Obregon, Jorge Pullin and Michael P. Ryan
gr-qc/9307038
Black Hole Entropy is Noether Charge
We consider a general, classical theory of gravity in $n$ dimensions, arising from a diffeomorphism invariant Lagrangian. In any such theory, to each vector field, $\xi^a$, on spacetime one can associate a local symmetry and, hence, a Noether current $(n-1)$-form, ${\bf j}$, and (for solutions to the field equations) a...
1993-07-29
2008-11-26
[ "gr-qc" ]
Robert M. Wald
gr-qc/9307037
Effective Potential of a Black Hole in Thermal Equilibrium with Quantum Fields
Expectation values of one-loop renormalized thermal equilibrium stress-energy tensors of free conformal scalars, spin-${1 \over 2}$ fermions and U(1) gauge fields on a Schwarzschild black hole background are used as sources in the semi-classical Einstein equation. The back-reaction and new equilibrium metric are solved...
1993-07-28
2012-08-27
[ "gr-qc" ]
David Hochberg, Thomas W. Kephart and James W. York, Jr
gr-qc/9307036
Can the Gravitational Wave Background from Inflation be Detected Locally?
The Cosmic Background Explorer (COBE) detection of microwave background anisotropies may contain a component due to gravitational waves generated by inflation. It is shown that the gravitational waves from inflation might be seen using `beam-in-space' detectors, but not the Laser Interferometer Gravity Wave Observatory...
1993-07-26
2014-11-17
[ "gr-qc", "astro-ph" ]
Andrew R Liddle
gr-qc/9307035
Entropy Bounds and Black Hole Remnants
We rederive the universal bound on entropy with the help of black holes while allowing for Unruh--Wald buoyancy. We consider a box full of entropy lowered towards and then dropped into a Reissner--Nordstr\"om black hole in equilibrium with thermal radiation. We avoid the approximation that the buoyant pressure varies s...
1993-07-25
2009-10-22
[ "gr-qc", "hep-th" ]
Jacob D. Bekenstein (University of California at Santa Barbara and Hebrew University)
gr-qc/9307033
Dimensionally Continued Black Holes
Static, spherically symmetric solutions of the field equations for a particular dimensional continuation of general relativity with negative cosmological constant are studied. The action is, in odd dimensions, the Chern-Simons form for the anti-de Sitter group and, in even dimensions, the Euler density constructed with...
1993-07-23
2009-10-22
[ "gr-qc" ]
Maximo Banados, Claudio Teitelboim and Jorge Zanelli
gr-qc/9307034
Extended Gravity Theories and the Einstein-Hilbert Action
I discuss the relation between arbitrarily high-order theories of gravity and scalar-tensor gravity at the level of the field equations and the action. I show that $(2n+4)$-order gravity is dynamically equivalent to Brans-Dicke gravity with an interaction potential for the Brans-Dicke field and $n$ further scalar field...
1993-07-23
2010-04-06
[ "gr-qc" ]
David Wands
gr-qc/9307032
Numerical Investigation of Cosmological Singularities
Although cosmological solutions to Einstein's equations are known to be generically singular, little is known about the nature of singularities in typical spacetimes. It is shown here how the operator splitting used in a particular symplectic numerical integration scheme fits naturally into the Einstein equations for a...
1993-07-22
2009-10-22
[ "gr-qc" ]
B.K. Berger, V. Moncrief
gr-qc/9307030
A Noncommutative Extension of Gravity
The commutative algebra of functions on a manifold is extended to a noncommutative algebra by considering its tensor product with the algebra of nxn complex matrices. Noncommutative geometry is used to formulate an extension of the Einstein-Hilbert action. The result is shown to be equivalent to the usual Kaluza-Klein ...
1993-07-22
2011-04-20
[ "gr-qc" ]
J.Madore and J. Mourad
gr-qc/9307031
Loop Variables in Topological Gravity
We examine the relationship between covariant and canonical (Ashtekar/Rovelli/Smolin) loop variables in the context of BF type topological field theories in 2+1 and 3+1 dimensions, with respective gauge groups SO(2,1) and SO(3,1). The latter model can be considered as the simplest topological gravity theory in 3+1 dime...
1993-07-22
2010-04-06
[ "gr-qc" ]
Y. Bi and J. Gegenberg
gr-qc/9307028
Classical Models of Subatomic Particles
We look at the program of modelling a subatomic particle---one having mass, charge, and angular momentum---as an interior solution joined to a classical general-relativistic Kerr-Newman exterior spacetime. We find that the assumption of stationarity upon which the validity of the Kerr-Newman exterior solution depends i...
1993-07-21
2009-10-22
[ "gr-qc" ]
R.B. Mann and M.S. Morris
gr-qc/9307029
Solution to 2+1 Gravity in DreiBein formalism
The reduction of the dreibein formalism of 2+1 General Relativity to the holonomies is explicitly performed. We also show explicitly how to relate these holonomies to a geometry classically, and how to generate these holonomies from any initial data for 2+1 gravity obeying the constraints.
1993-07-21
2010-11-01
[ "gr-qc" ]
W. G. Unruh and Peter Newbury
gr-qc/9307027
Semiclassical Equations for Weakly Inhomogeneous Cosmologies
The in-in effective action formalism is used to derive the semiclassical correction to Einstein's equations due to a massless scalar quantum field conformally coupled to small gravitational perturbations in spatially flat cosmological models. The vacuum expectation value of the stress tensor of the quantum field is dir...
1993-07-21
2009-07-10
[ "gr-qc" ]
Antonio Campos and Enric Verdaguer
gr-qc/9307026
Canonical variables and quasilocal energy in general relativity
Recently Brown and York have devised a new method for defining quasilocal energy in general relativity. Their method yields expressions for the quasilocal energy and momentum surface densities associated with the two-boundary of a spacelike slice of a spatially bounded spacetime. These expressions are essentially Arnow...
1993-07-21
2010-04-06
[ "gr-qc" ]
Stephen Lau
gr-qc/9307024
Quantum Squeezing and Cosmological Entropy Production
The entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter, and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic black-body radiati...
1993-07-20
2010-04-06
[ "gr-qc", "astro-ph", "hep-th" ]
M.Gasperini and M.Giovannini
gr-qc/9307025
The Geometry and Topology of 3-Manifolds and Gravity
It is well known that one can parameterize 2-D Riemannian structures by conformal transformations and diffeomorphisms of fiducial constant curvature geometries; and that this construction has a natural setting in general relativity theory in 2-D. I will show that a similar parameterization exists for 3-D Riemannian str...
1993-07-20
2007-05-23
[ "gr-qc", "hep-th" ]
J. Gegenberg and G. Kunstatter
gr-qc/9307023
How to Estimate Energy Lost to Gravitational Waves (revised)
The energy--momentum radiated in gravitational waves by an isolated source is given by a formula of Bondi. This formula is highly non--local: the energy--momentum is not given as the integral of a well--defined local density. It has therefore been unclear whether the Bondi formula can be used to get information from gr...
1993-07-19
2009-10-22
[ "gr-qc" ]
Adam D. Helfer
gr-qc/9307022
Energy, Temperature, and Entropy of Black Holes Dressed with Quantum Fields
A deeper understanding of the thermal properties of black holes than we presently have depends to a large degree on obtaining a firmer grasp of the properties of the entropy. For such an understanding we must at least know the basic relations among entropy, energy, and temperature of a black hole in thermal equilibrium...
1993-07-19
2012-08-27
[ "gr-qc" ]
James. W. York, Jr
gr-qc/9307021
On Singularity Free Cosmological Models
In 1990 Senovilla$^1$ obtained an interestisng cosmological solution of Einstein's equations that was free of the big-bang singularity. It represented an inhomogeneous and anisotropic cylindrical model filled with disordered radiation, ${\bf \rho = 3p}$. The model was valid for ${\bf t \rightarrow - \infty }$ to ${\bf ...
1993-07-15
2007-05-23
[ "gr-qc" ]
N. Dadhich, R. Tikekar and L.K. Patel
gr-qc/9307016
The origin of spacetime topology and generalizations of quantum field theory
The research effort reported in this paper is directed, in a broad sense, towards understanding the small-scale structure of spacetime. The fundamental question that guides our discussion is ``what is the physical content of spacetime topology?" In classical physics, if spacetime, $(X, \tau )$, has sufficiently regular...
1993-07-14
2010-04-06
[ "gr-qc" ]
Ulvi Yurtsever
gr-qc/9307020
Collapse of a Circular Loop of Cosmic String
We study the collapse of a circular loop of cosmic string. The gravitational field of the string is treated using the weak field approximation. The gravitational radiation from the loop is evaluated numerically. The memtric of the loop near the point of collapse is found analytically.
1993-07-14
2009-10-22
[ "gr-qc" ]
David Garfinkle and G. Comer Duncan
gr-qc/9307018
Superspace Dynamics and Perturbations Around "Emptiness"
Superspace parametrized by gauge potentials instead of metric three-geometries is discussed in the context of the Ashtekar variables. Among other things, an "internal clock" for the full theory can be identified. Gauge-fixing conditions which lead to the natural geometrical separation of physical from gauge modes are d...
1993-07-14
2010-11-01
[ "gr-qc", "hep-th" ]
Chopin Soo and Lay Nam Chang
gr-qc/9307017
Algebraic approach to quantum field theory on non-globally-hyperbolic spacetimes
The mathematical formalism for linear quantum field theory on curved spacetime depends in an essential way on the assumption of global hyperbolicity. Physically, what lie at the foundation of any formalism for quantization in curved spacetime are the canonical commutation relations, imposed on the field operators evalu...
1993-07-14
2010-04-06
[ "gr-qc" ]
Ulvi Yurtsever
gr-qc/9307019
Generalized Sums over Histories for Quantum Gravity II. Simplicial Conifolds
This paper examines the issues involved with concretely implementing a sum over conifolds in the formulation of Euclidean sums over histories for gravity. The first step in precisely formulating any sum over topological spaces is that one must have an algorithmically implementable method of generating a list of all spa...
1993-07-14
2009-10-22
[ "gr-qc", "hep-th" ]
Kristin Schleich and Donald M. Witt
gr-qc/9307015
Generalized Sums over Histories for Quantum Gravity I. Smooth Conifolds
This paper proposes to generalize the histories included in Euclidean functional integrals from manifolds to a more general set of compact topological spaces. This new set of spaces, called conifolds, includes nonmanifold stationary points that arise naturally in a semiclasssical evaluation of such integrals; additiona...
1993-07-13
2010-11-01
[ "gr-qc", "hep-th" ]
Kristin Schleich and Donald M. Witt
gr-qc/9307013
Quantum-Mechanical Histories and the Uncertainty Principle. II. Fluctuations About Classical Predictability
This paper is concerned with two questions in the decoherent histories approach to quantum mechanics: the emergence of approximate classical predictability, and the fluctuations about it necessitated by the uncertainty principle. We consider histories characterized by position samplings at $n$ moments of time. We use t...
1993-07-12
2009-10-22
[ "gr-qc", "cond-mat", "hep-th" ]
J.J.Halliwell
gr-qc/9307014
Testing Cosmic Censorship with Black Hole Collisions
There exists an upper limit on the mass of black holes when the cosmological constant $\Lambda$ is positive. We study the collision of two black holes whose total mass exceeds this limit. Our investigation is based on a recently discovered exact solution describing the collision of $Q=M$ black holes with $\Lambda > 0$....
1993-07-12
2009-10-22
[ "gr-qc", "hep-th" ]
Dieter Brill, Gary Horowitz, David Kastor, and Jennie Traschen
gr-qc/9307012
Singularity Free Spacetimes -- I :Metric and Fluid Models
We show that the metric for the singularity free family of fluid models [3] can be obtained by a simple and natural inhomogenisation and anisotropisation procedure from Friedman--Robertson--Walker metric with negative curvature. The metric is unique for cylindrically symmetric spacetime with metric potentials being sep...
1993-07-12
2007-05-23
[ "gr-qc" ]
Naresh Dadhich, L. K. Patel and R. Tikekar
gr-qc/9307011
On Singularity Free Spacetimes--II : mid Geodesic Completeness
We study the geodesics of the singularity free metric considered in the preceding Paper I and show that they are complete. This once again demonstrates the absence of singularity. The geodesic completeness is established in general without reference to any particular matter distribution. The metric is globally hyperbol...
1993-07-12
2007-05-23
[ "gr-qc" ]
Naresh Dadhich and L. K. Patel
gr-qc/9307009
Late-Time Behavior of Stellar Collapse and Explosions: I. Linearized Perturbations
Problem with the figures should be corrected. Apparently a broken uuencoder was the cause.
1993-07-10
2009-10-22
[ "gr-qc", "astro-ph" ]
Carsten Gundlach, Richard Price and Jorge Pullin
gr-qc/9307010
Late-Time Behavior of Stellar Collapse and Explosions: II. Nonlinear Evolution
Problem with the figures should be corrected. Apparently a broken uuencoder was the cause.
1993-07-10
2009-10-22
[ "gr-qc", "astro-ph" ]
Carsten Gundlach, Richard Price adn Jorge Pullin
gr-qc/9307007
2D dilaton-gravity from 5D Einstein equations
A semiclassical two-dimensional dilaton-gravity model is obtained by dimensional reduction of the spherically symmetric five-dimensional Einstein equations and used to investigate black hole evaporation. It is shown that this model prevents the formation of naked singularity and allows spacetime wormholes to contribute...
1993-07-09
2016-08-14
[ "gr-qc" ]
P.F. Gonz\'alez-D\'iaz
gr-qc/9307008
Gravitational Effects on Domain Walls with Curvature Correction
We derive the effective action for a domain wall with small thickness in curved spacetime and show that, apart from the Nambu term, it includes a contribution proportional to the induced curvature. We then use this action to study the dynamics of a spherical thick bubble of false vacuum (de Sitter) surrounded by an inf...
1993-07-09
2009-10-22
[ "gr-qc" ]
C.Barrabes, B.Boisseau and M.Sakellariadou
gr-qc/9307006
The Phase Space of 2+1 Dimensional Gravity in the Ashtekar Formulation
The Ashtekar formulation of 2+1 gravity differs from the geometrodynamical and Witten descriptions when the 2-metric is degenerate. We study the phase space of 2+1 gravity in the Ashtekar formulation to understand these degenerate solutions to the field equations. In the process we find two new systems of first class c...
1993-07-08
2017-03-24
[ "gr-qc" ]
J. Fernando Barbero and Madhavan Varadarajan
gr-qc/9307004
A Phase Space for Gravitational Radiation
We give a new definition, based on considerations of well-posedness for a certain asymptotic initial value problem, of the phase space for the radiative degrees of freedom of the gravitational field in exact General Relativity. This space fibres over the space of final states, with the fibres being the purely radiative...
1993-07-07
2010-11-01
[ "gr-qc" ]
Adam D. Helfer
gr-qc/9307005
Twistors and the BMS Group
We compute the motions of null infinity to which the components of the angular momentum of the gravitational field, as defined by Penrose, are conjugate. We find that the boosts are supplemented by anomalous translations. If $c_{ab}$ is the skew bivector determining the component of the angular momentum in question, th...
1993-07-07
2010-04-06
[ "gr-qc" ]
Adam D. Helfer
gr-qc/9307003
Models of Particle Detection in Regions of Spacetime
We investigate two models of measuring devices designed to detect a non-relativistic free particle in a given region of spacetime. These models predict different probabilities for a free quantum particle to enter a spacetime region $R$ so that this notion is device dependent. The first model is of a von Neumann couplin...
1993-07-06
2009-10-22
[ "gr-qc", "hep-th" ]
Donald Marolf
gr-qc/9307002
Conformal Invariance of Black Hole Temperature
It is shown that the surface gravity and temperature of a stationary black hole are invariant under conformal transformations of the metric that are the identity at infinity. More precisely, we find a conformal invariant definition of the surface gravity of a conformal Killing horizon that agrees with the usual definit...
1993-07-06
2010-04-06
[ "gr-qc", "hep-th" ]
Ted Jacobson and Gungwon Kang
gr-qc/9307001
Recovery of information from black hole radiation by considering stimulated emission
We deal with the black hole information loss paradox by showing that the stimulated emission component of the black hole radiation contains information about the initial state of the system. The nonlocal behaviour that allows the recovery of information about the matter that falls behind the horizon appears in a natura...
1993-07-01
2009-10-22
[ "gr-qc", "hep-th" ]
R. Mueller and Carlos O. Lousto
gr-qc/9306035
From the Big Bang Theory to the Theory of a Stationary Universe
We consider chaotic inflation in the theories with the effective potentials phi^n and e^{\alpha\phi}. In such theories inflationary domains containing sufficiently large and homogeneous scalar field \phi permanently produce new inflationary domains of a similar type. We show that under certain conditions this process o...
1993-06-29
2009-09-29
[ "gr-qc", "astro-ph", "hep-lat" ]
Andrei Linde, Dmitri Linde and Arthur Mezhlumian
gr-qc/9306034
On the Constraint Algebra of Degenerate Relativity
As shown by Ashtekar in the mid 80's, general relativity can be extended to incorporate degenerate metrics. This extension is not unique, however, as one can change the form of the hamiltonian constraints and obtain an {\it alternative} degenerate extension of general relativity that disagrees with Ashtekar's original ...
1993-06-28
2009-10-22
[ "gr-qc" ]
Joseph D. Romano
gr-qc/9306033
Gravitational Waves from an Axi-symmetric Source in the Nonsymmetric Gravitational Theory
We examine gravitational waves in an isolated axi--symmetric reflexion symmetric NGT system. The structure of the vacuum field equations is analyzed and the exact solutions for the field variables in the metric tensor are found in the form of expansions in powers of a radial coordinate. We find that in the NGT axially ...
1993-06-25
2015-06-25
[ "gr-qc" ]
N. J. Cornish, J. W. Moffat and D. C. Tatarski
gr-qc/9306032
Black Hole with Non-Commutative Hair
The specific nonlinear vector $\sigma$-model coupled to Einstein gravity is investigated. The model arises in the studies of the gravitating matter in non-commutative geometry. The static spherically symmetric spacetimes are identified by direct solving of the field equations. The asymptotically flat black hole with th...
1993-06-25
2007-05-23
[ "gr-qc", "hep-th" ]
C. Klimcik, P. Kolnik, and A. Pompos
gr-qc/9306031
Elliptic and circular wormholes
Two new exact analytical solutions of the euclidean Einstein equations for a minimal massless scalar field and negative cosmological constant have been obtained. These solutions are given in terms of Jacobian elliptic or circular functions, rather than hyperbolic functions, connect large asymptotic regions of maximally...
1993-06-25
2016-08-14
[ "gr-qc" ]
P.F. Gonz\'alez-D\'iaz
gr-qc/9306029
On time and the quantum-to-classical transition in Jordan-Brans-Dicke quantum gravity
Any quantum theory of gravity which treats the gravitational constant as a dynamical variable has to address the issue of superpositions of states corresponding to different eigenvalues. We show how the unobservability of such superpositions can be explained through the interaction with other gravitational degrees of f...
1993-06-24
2010-04-06
[ "gr-qc", "astro-ph", "hep-th" ]
Claus Kiefer and Erik A. Martinez
gr-qc/9306030
Gravitational Observables and Local Symmetries
Using a recent classification of local symmetries of the vacuum Einstein equations, it is shown that there can be no observables for the vacuum gravitational field (in a closed universe) built as spatial integrals of local functions of Cauchy data and their derivatives.
1993-06-24
2010-01-06
[ "gr-qc", "hep-th" ]
C. G. Torre
gr-qc/9306028
Geometric Phase in Vacuum Instability:APPLICATIONS in Quantum Cosmology
Three different methods viz. i) a perturbative analysis of the Schr\"odinger equation ii) abstract differential geometric method and iii) a semiclassical reduction of the Wheeler-Dewitt equation, relating Pancharatnam phase to vacuum instability are discussed. An improved semiclassical reduction is also shown to yield ...
1993-06-24
2010-11-01
[ "gr-qc" ]
D.P. Datta
gr-qc/9306027
Blow-Up of Test Fields Near Cauchy Horizons
The behaviour of test fields near a compact Cauchy horizon is investigated. It is shown that solutions of nonlinear wave equations on Taub spacetime with generic initial data cannot be continued smoothly to both extensions of the spacetime through the Cauchy horizon. This is proved using an energy method. Similar resul...
1993-06-23
2009-10-22
[ "gr-qc" ]
J. Rauch and A. D. Rendall
gr-qc/9306026
Gauge fields on Riemann-Cartan space-times
Gauge fields are described on an Riemann-Cartan space-time by means of tensor-valued differential forms and exterior calculus. It is shown that minimal coupling procedure leads to a gauge invariant theory where gauge fields interact with torsion, and that consistency conditions for the gauge fields impose restrictions ...
1993-06-22
2009-10-22
[ "gr-qc" ]
Alberto Saa
gr-qc/9306025
Open Questions in Classical Gravity
We discuss some outstanding open questions regarding the validity and uniqueness of the standard second order Newton-Einstein classical gravitational theory. On the observational side we discuss the degree to which the realm of validity of Newton's Law of Gravity can actually be extended to distances much larger than t...
1993-06-21
2009-10-22
[ "gr-qc", "astro-ph" ]
Philip D. Mannheim (University of Connecticut)