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Jorge Pullin

Publications and source records attributed to Jorge Pullin.

189 records · Page 11Linked to original sources
arXiv1994

Colliding Black Holes: The Close Limit

The problem of the mutual attraction and joining of two black holes is of importance as both a source of gravitational waves and as a testbed of numerical relativity. If the holes start out close enough that they are initially surrounded by a common horizon, the problem can be viewed as a perturbation of a single black hole. We take initial data due to Misner for close black holes, apply perturbation theory and evolve the data with the Zerilli equation. The computed gravitational radiation agrees with and extends the results of full numerical computations.

gr-qc↗
arXiv1994

MATTERS OF GRAVITY, a newsletter for the gravity community, Number 3

Table of contents Editorial Correspondents Gravity News: Open Letter to gravitational physicists, Beverly Berger A Missouri relativist in King Gustav's Court, Clifford Will Gary Horowitz wins the Xanthopoulos award, Abhay Ashtekar Research briefs: Gamma-ray bursts and their possible cosmological implications, Peter Meszaros Current activity and results in laboratory gravity, Riley Newman Update on representations of quantum gravity, Donald Marolf Ligo project report: December 1993, Rochus E. Vogt Dark matter or new gravity?, Richard Hammond Conference reports: Gravitational waves from coalescing compact binaries, Curt Cutler Mach's principle: from Newton's bucket to quantum gravity, Dieter Brill Cornelius Lanczos international centenary conference, David Brown Third Midwest relativity conference, David Garfinkle

gr-qc↗
arXiv1993

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: quantum aspects of black holes 13 Conference report: knots and quantum gravity 14 Conference report: deterministic chaos in GR 17

gr-qc↗
arXiv1993

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 minisuperspace. Implications for the general theory are also briefly discussed.

gr-qc↗
arXiv1992

The Escape of Gravitational Radiation from the Field of Massive Bodies

We consider a compact source of gravitational waves of frequency $ω$, in or near a massive spherically symmetric distribution of matter or a black hole. Recent calculations have led to apparently contradictory results for the influence of the massive body on the propagation of the waves. We show here that the results are in fact consistent and in agreement with the ``standard'' viewpoint in which the high frequency compact source produces the radiation as if in a flat background, and the background curvature affects the propagation of these waves.

astro-ph↗
arXiv1992

How the Jones Polynomial Gives Rise to Physical States of Quantum General Relativity

Solutions to both the diffeomorphism and the hamiltonian constraint of quantum gravity have been found in the loop representation, which is based on Ashtekar's new variables. While the diffeomorphism constraint is easily solved by considering loop functionals which are knot invariants, there remains the puzzle why several of the known knot invariants are also solutions to the hamiltonian constraint. We show how the Jones polynomial gives rise to an infinite set of solutions to all the constraints of quantum gravity thereby illuminating the structure of the space of solutions and suggesting the existance of a deep connection between quantum gravity and knot theory at a dynamical level.

hep-th↗
arXiv1992

The Emergence of Radiation from Gravitational Potential Wells: The Absence of $ωM$ Effects

We consider a source of gravitational waves of frequency $ω$, located near the center of a massive galaxy of mass $M$ and radius $R$, with $ω\gg R^{-1}$. In the case of a perfect fluid galaxy, and of odd-parity waves, there is no direct matter-wave interaction and the propagation of the waves is affected by the galaxy only through the curvature of the spacetime background through which the waves propagate. We find that, in addition to the expected redshift of the radiation emerging from the galaxy, there is a small amount of backscatter, of order $M/ω^2R^3$. We show that there is no suppression of radiative power by the factor $1+ω^2M^2/4$ as has been recently predicted by Kundu. The origin of Kundu's suppression lies in the interpretation of a term in the expansion of the exterior field of the galaxy in inverse powers of radius. It is shown why that term is not related to the source strength or to the strength of the emerging radiation.

hep-th↗
arXiv1992

Jones Polynomials for Intersecting Knots as Physical States of Quantum Gravity

We find a consistent formulation of the constraints of Quantum Gravity with a cosmological constant in terms of the Ashtekar new variables in the connection representation, including the existence of a state that is a solution to all the constraints. This state is related to the Chern-Simons form constructed from the Ashtekar connection and has an associated metric in spacetime that is everywhere nondegenerate. We then transform this state to the loop representation and find solutions to all the constraint equations for intersecting loops. These states are given by suitable generalizations of the Jones knot polynomial for the case of intersecting knots. These are the first physical states of Quantum Gravity for which an explicit form is known both in the connection and loop representations. Implications of this result are also discussed.

hep-th↗