61 research outputs found
Field Equations and Conservation Laws in the Nonsymmetric Gravitational Theory
The field equations in the nonsymmetric gravitational theory are derived from
a Lagrangian density using a first-order formalism. Using the general
covariance of the Lagrangian density, conservation laws and tensor identities
are derived. Among these are the generalized Bianchi identities and the law of
energy-momentum conservation. The Lagrangian density is expanded to
second-order, and treated as an ``Einstein plus fields'' theory. From this, it
is deduced that the energy is positive in the radiation zone.Comment: 16 pages, RevTeX. Additional equations supplie
Nonlocal Astroparticles in Einstein's Universe
Gravitational probes should maintain spatial flatness for
Einsten-Infeld-Hoffmann dynamics of relativistic matter-energy. The continuous
elementary source/particle in Einstein's gravitational theory is the r^{-4}
radial energy density rather than the delta-operator density in empty-space
gravitation. The space energy integral of such an infinite (astro)particle is
finite and determines its nonlocal gravitational charge for the
energy-to-energy attraction of other nonlocal (astro)particles. The non-empty
flat space of the undivided material Universe is charged continuously by the
world energy density of the global ensemble of overlapping radial particles.
Nonlocal gravitational/inertial energy-charges incorporate Machian relativism
quantitatively into Einstein's gravitation for self-contained SR-GR dynamics
without references on Newton's mass-to-mass attraction.Comment: 9 pages, typos and arguments adde
Conformal Invariance in Einstein-Cartan-Weyl space
We consider conformally invariant form of the actions in Einstein, Weyl,
Einstein-Cartan and Einstein-Cartan-Weyl space in general dimensions() and
investigate the relations among them. In Weyl space, the observational
consistency condition for the vector field determining non-metricity of the
connection can be obtained from the equation of motion. In Einstein-Cartan
space a similar role is played by the vector part of the torsion tensor. We
consider the case where the trace part of the torsion is the Kalb-Ramond type
of field. In this case, we express conformally invariant action in terms of two
scalar fields of conformal weight -1, which can be cast into some interesting
form. We discuss some applications of the result.Comment: 10 pages, version to appear MPL
The Dynamical Instability of Static, Spherically Symmetric Solutions in Nonsymmetric Gravitational Theories
We consider the dynamical stability of a class of static,
spherically-symmetric solutions of the nonsymmetric gravitational theory. We
numerically reproduce the Wyman solution and generate new solutions for the
case where the theory has a nontrivial fundamental length scale \mu^{-1}. By
considering spherically symmetric perturbations of these solutions we show that
the Wyman solutions are generically unstable.Comment: 13 pages, uses amslatex, graphicx and subfigure package
Geodesic and Path Motion in the Nonsymmetric Gravitational Theory
We study the problem of test-particle motion in the Nonsymmetric
Gravitational Theory (NGT) assuming the four-velocity of the particle is
parallel-transported along the trajectory. The predicted motion is studied on a
static, spherically symmetric background field, with particular attention paid
to radial and circular motions. Interestingly, it is found that the proper time
taken to travel between any two non-zero radial positions is finite. It is also
found that circular orbits can be supported at lower radii than in General
Relativity for certain forms of motion.
We present three interactions which could be used as alternate methods for
coupling a test-particle to the antisymmetric components of the NGT field. One
of these takes the form of a Yukawa force in the weak-field limit of a static,
spherically symmetric field, which could lead to interesting phenomenology.Comment: 17 pages, REVTeX 3.0 with amssymb.st
On the (im)possibility of a supersymmetric extension of NGT
We investigate the possibility of constructing a locally supersymmetric
extension of NGT (Nonsymmetric Gravitation Theory), based on the graded
extension of the Poincare group. In the framework of the simple model that we
propose, we end up with a no-go result, namely the impossibility of cancelling
some linear contribution in the gravitino field. This drawback seems to
seriously undermine the construction of a supergravity based on NGT.Comment: 17 pages, Latex,two references added, minor changes for clarity, v3:
E-mail changed, v4 : Ref(9) correcte
On the nonsymmetric purely affine gravity
We review the vacuum purely affine gravity with the nonsymmetric connection
and metric. We also examine dynamical effects of the second Ricci tensor and
covariant second-rank tensors constructed from the torsion tensor in the
gravitational Lagrangian.Comment: 15 pages; published versio
An assessment of Evans' unified field theory I
Evans developed a classical unified field theory of gravitation and
electromagnetism on the background of a spacetime obeying a Riemann-Cartan
geometry. This geometry can be characterized by an orthonormal coframe theta
and a (metric compatible) Lorentz connection Gamma. These two potentials yield
the field strengths torsion T and curvature R. Evans tried to infuse
electromagnetic properties into this geometrical framework by putting the
coframe theta to be proportional to four extended electromagnetic potentials A;
these are assumed to encompass the conventional Maxwellian potential in a
suitable limit. The viable Einstein-Cartan(-Sciama-Kibble) theory of gravity
was adopted by Evans to describe the gravitational sector of his theory.
Including also the results of an accompanying paper by Obukhov and the author,
we show that Evans' ansatz for electromagnetism is untenable beyond repair both
from a geometrical as well as from a physical point of view. As a consequence,
his unified theory is obsolete.Comment: 39 pages of latex, modified because of referee report, mistakes and
typos removed, partly reformulated, taken care of M.W.Evans' rebutta
The unexpected resurgence of Weyl geometry in late 20-th century physics
Weyl's original scale geometry of 1918 ("purely infinitesimal geometry") was
withdrawn by its author from physical theorizing in the early 1920s. It had a
comeback in the last third of the 20th century in different contexts: scalar
tensor theories of gravity, foundations of gravity, foundations of quantum
mechanics, elementary particle physics, and cosmology. It seems that Weyl
geometry continues to offer an open research potential for the foundations of
physics even after the turn to the new millennium.Comment: Completely rewritten conference paper 'Beyond Einstein', Mainz Sep
2008. Preprint ELHC (Epistemology of the LHC) 2017-02, 92 pages, 1 figur
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