318 research outputs found
On Special Re-quantization of a Black Hole
Quantized expressions for the gravitational energy and momentum are derived
from a linearized theory of teleparallel gravity. The derivation relies on a
second-quantization procedure that constructs annihilation and creation
operators for the graviton. The resulting gravitational field is a collection
of gravitons, each of which has precise energy and momentum. On the basis of
the weak-field approximation of Schwarzschild's solution, a new form for the
quantization of the mass of a black hole is derived.Comment: 4 page
Zoneamento de riscos climáticos para a cultura de milho no estado do Rio Grande do Sul: períodos favoráveis de semeadura por município, safra 2004-2005.
bitstream/CNPT-2010/40294/1/p-bp21.pd
Space-time defects and teleparallelism
We consider the class of space-time defects investigated by Puntigam and
Soleng. These defects describe space-time dislocations and disclinations
(cosmic strings), and are in close correspondence to the actual defects that
arise in crystals and metals. It is known that in such materials dislocations
and disclinations require a small and large amount of energy, respectively, to
be created. The present analysis is carried out in the context of the
teleparallel equivalent of general relativity (TEGR). We evaluate the
gravitational energy of these space-time defects in the framework of the TEGR
and find that there is an analogy between defects in space-time and in
continuum material systems: the total gravitational energy of space-time
dislocations and disclinations (considered as idealized defects) is zero and
infinit, respectively.Comment: 22 pages, no figures, to appear in the Class. Quantum Gravit
Zoneamento de riscos climáticos para a cultura de feijão no estado do Rio Grande do Sul: períodos favoráveis de semeadura por município, safra 2003-2004.
bitstream/CNPT-2010/40289/1/p-bp16.pd
Zoneamento de riscos climáticos para a cultura de milho no estado do Rio Grande do Sul: períodos favoráveis de semeadura por município, safra 2003-2004.
bitstream/CNPT-2010/40287/1/p-bp14.pd
Energy of general 4-dimensional stationary axisymmetric spacetime in the teleparallel geometry
The field equation with the cosmological constant term is derived and the
energy of the general 4-dimensional stationary axisymmetric spacetime is
studied in the context of the hamiltonian formulation of the teleparallel
equivalent of general relativity (TEGR). We find that, by means of the integral
form of the constraints equations of the formalism naturally without any
restriction on the metric parameters, the energy for the asymptotically flat/de
Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate
can be expressed as . It is surprised to learn that the
energy expression is relevant to the metric components ,
and only. As examples, by using this formula
we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter
(KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes.Comment: 12 page
Charged Dilaton, Energy, Momentum and Angular-Momentum in Teleparallel Theory Equivalent to General Relativity
We apply the energy-momentum tensor to calculate energy, momentum and
angular-momentum of two different tetrad fields. This tensor is coordinate
independent of the gravitational field established in the Hamiltonian structure
of the teleparallel equivalent of general relativity (TEGR). The spacetime of
these tetrad fields is the charged dilaton. Our results show that the energy
associated with one of these tetrad fields is consistent, while the other one
does not show this consistency. Therefore, we use the regularized expression of
the gravitational energy-momentum tensor of the TEGR. We investigate the energy
within the external event horizon using the definition of the gravitational
energy-momentum.Comment: 22 Pages Late
Macrozoneamento climático para o arroz irrigado no Rio Grande do Sul.
bitstream/item/33533/1/documento-137.pd
Yang's gravitational theory
Yang's pure space equations (C.N. Yang, Phys. Rev. Lett. v.33, p.445 (1974))
generalize Einstein's gravitational equations, while coming from gauge theory.
We study these equations from a number of vantage points: summarizing the work
done previously, comparing them with the Einstein equations and investigating
their properties. In particular, the initial value problem is discussed and a
number of results are presented for these equations with common energy-momentum
tensors.Comment: 28 pages, to appear in Gen. Rel. Gra
Riemannian and Teleparallel Descriptions of the Scalar Field Gravitational Interaction
A comparative study between the metric and the teleparallel descriptions of
gravitation is made for the case of a scalar field. In contrast to the current
belief that only spin matter could detect the teleparallel geometry, scalar
matter being able to feel the metric geometry only, we show that a scalar field
is able not only to feel anyone of these geometries, but also to produce
torsion. Furthermore, both descriptions are found to be completely equivalent,
which means that in fact, besides coupling to curvature, a scalar field couples
also to torsion.Comment: Minor corrections made, and a paragraph added to the last section.
Version to appear in Gen. Rel. Gra
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