Hasil untuk "gr-qc"

S. Gharanfoli, A. Abbassi

P. Zizzi

J. Guven, N. Murchadha

We continue our examination of the constraints in spherically symmetric general relativity begun in I (gr-qc/9411009) and II (gr-qc/9411010). We extend to general configurations with $J\ne 0$ the analysis of II which treated a moment of time symmetry. We exploit the one parameter family of foliations introduced in I which are linear and homogeneous in the extrinsic curvature to characterize apparent horizons and spatial singularities in the initial data. In particular, we demonstrate that these characterizations do not depend sensitively on the foliation.

M. Salti, O. Aydoğdu

This paper has excessive overlap with the following paper also written by the authors or their collaborators: gr-qc/0511095.

S. Deser

The above hep-th posting purports -- erroneously -- to be a comment on a Note by me in gr-qc.

D. Brill

This is the reply given at the conference ``Mach's Principle" at T\"ubingen in July 1993 to the paper by Isenberg (1993a). Unfortunately the Isenberg paper itself was not submitted to gr-qc.

F. Binbay, I. Acikgoz, M. Salti

This paper has been removed by arXiv administrators because it plagiarizes gr-qc/9803014, "A White Hole Model of the Big Bang," by Philip Gibbs.

D. Brill

This is a reply, given at the conference ``Mach's Principle" in T\"ubingen in July 1993, to the paper by Pfister (1993). Unfortunately the Pfister paper itself was not sent to gr-qc.

F. Henry-Couannier

The previous version of this article gave erroneous predictions. The correct uptodate predictions can be found in the section devoted to gravitomagnetism in the living review of the Dark Gravity theory: gr-qc/0610079 The most natural prediction is zero frame dragging and the same geodetic effect as predicted by GR. However, a straightforward extension of the theory could lead to the same frame-dragging as in GR.

Toshifumi Sakaguchi

The paper entitled ``Against Many-Worlds Interpretations'' by A. Kent, which has recently been submitted to the e-Print archive (gr-qc/9703089) contained some misconceptions. The claims on Everett's many-worlds interpretation are quoted and answered.

S. Rouhani, M. V. Takook

Miguel Sánchez Caja

This paper has been withdrawn because the part concerning the definition of global hyperbolicity has already been included in an expanded and clearer way in gr-qc/0611138. The remainder will be also extended and posted.

L. Pachon, J. Rueda

We dispose of some objections raised by Manko et al. (gr-qc/0604091) on a recently published paper on the role of Poynting vector in the ocurrence of vorticity in electrovaccum spacetimes (2006, Class. Quantum Grav. 23, 2395)

L. Susskind

In a recent paper on wormholes (gr-qc/0503097), the author of that paper demonstrated that he didn't know what he was talking about. In this paper I correct the author's naive erroneous misconceptions.

G. Clément, D. Gal’tsov, P. Letelier

We show that the Letelier-Gal'tsov (LG) metric describing multiple crossed strings in relative motion does solve the Einstein equations, in spite of the discontinuity uncovered recently by Krasnikov [gr-qc/0502090] provided the strings are straight and moving with constant velocities.

F. Aquino

In a previous work it was shown that the gravitational and inertial masses are correlated by an adimensional factor, which depends on the incident radiation upon the particle. It was also shown that there is a direct correlation between the radiation absorbed by the particle and its gravitational mass, independently of the inertial mass. This finding has fundamental consequences to Unified Field Theory and Quantum Cosmology. Only in the absence of electromagnetic radiation the mentioned factor becomes equal to one. On the other hand, in specific electromagnetic conditions, it can be reduced, nullified or made negative. This means that there is the possibility of the gravitational masses can be reduced, nullified and made negative by means of electromagnetic radiation. This unexpected theoretical result was recently confirmed by an experiment (gr-qc/0005107). A fundamental consequence of the mentioned correlation is that , in specific ultra-high energy conditions, the gravitational and electromagnetic fields can be described by the same Hamiltonian , i.e., in these circumstances, they are unified. Such conditions can have occurred inclusive in the Initial Universe , before the first spontaneous breaking of symmetry. Taking as base this discovery, and starting from the gravitational mass of superparticles from the Initial Universe we show here that it is possible to deduce the reciprocal fine structure constant and the uncertainty principle directly from the Gravitation Theory(Unified Theory).

E. Abdalla, R. Mohayaee, M. B. Ribeiro

L. Iorio

B. Dimitrov

Motivated by the necessity to find exact solutions with the elliptic Weierstrass function of the Einstein's equations (see gr-qc/0105022),the present paper develops further the proposed approach in hep-th/0107231, concerning the s.c. cubic algebraic equation for effective parametrization. Obtaining an ''embedded'' sequence of cubic equations, it is shown that it is possible to parametrize also a multi-variable cubic curve, which is not the standardly known case from algebraic geometry. Algebraic solutions for the contravariant metric tensor components are derived and the parametrization is extended in respect to the covariant components as well. It has been speculated that corrections to the extradimensional volume in theories with extra dimensions should be taken into account, due to the non-euclidean nature of the Lobachevsky space. It was shown that the mechanism of exponential "damping" of the physical mass in the higher-dimensional brane theory may be more complicated due to the variety of contravariant metric components for a spacetime with a given constant curvature. The invariance of the low-energy type I string theory effective action is considered in respect not only to the known procedure of compactification to a four-dimensional spacetime, but also in respect to rescaling the contravariant metric components. As a result, instead of the simple algebraic relations between the parameters in the string action, quasilinear differential equations in partial derivatives are obtained, which have been solved for the most simple case. In the Appendix, a new block structure method is presented for solving the well known system of operator equations in gravity theory in the N-dimensional case.

B. Dimitrov