242 research outputs found
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.Comment: 16pp, RevTex, 6 figures (included), NSF-ITP-93-8
Aspects of electrostatics in a weak gravitational field
Several features of electrostatics of point charged particles in a weak,
homogeneous, gravitational field are discussed using the Rindler metric to
model the gravitational field. Some previously known results are obtained by
simpler and more transparent procedures and are interpreted in an intuitive
manner. Specifically: (i) We show that the electrostatic potential of a charge
at rest in the Rindler frame is expressible as A_0=(q/l) where l is the affine
parameter distance along the null geodesic from the charge to the field point.
(ii) We obtain the sum of the electrostatic forces exerted by one charge on
another in the Rindler frame and discuss its interpretation. (iii) We show how
a purely electrostatic term in the Rindler frame appears as a radiation term in
the inertial frame. (In part, this arises because charges at rest in a weak
gravitational field possess additional weight due to their electrostatic
energy. This weight is proportional to the acceleration and falls inversely
with distance -- which are the usual characteristics of a radiation field.)
(iv) We also interpret the origin of the radiation reaction term by extending
our approach to include a slowly varying acceleration. Many of these results
might have possible extensions for the case of electrostatics in an arbitrary
static geometry. [Abridged Abstract]Comment: 26 pages; accepted for publication in Gen.Rel.Gra
Radiation from a charged particle and radiation reaction -- revisited
We study the electromagnetic fields of an arbitrarily moving charged particle
and the radiation reaction on the charged particle using a novel approach. We
first show that the fields of an arbitrarily moving charged particle in an
inertial frame can be related in a simple manner to the fields of a uniformly
accelerated charged particle in its rest frame. Since the latter field is
static and easily obtainable, it is possible to derive the fields of an
arbitrarily moving charged particle by a coordinate transformation. More
importantly, this formalism allows us to calculate the self-force on a charged
particle in a remarkably simple manner. We show that the original expression
for this force, obtained by Dirac, can be rederived with much less computation
and in an intuitively simple manner using our formalism.Comment: Submitted to Physical Review
Heat transfer and Fourier's law in off-equilibrium systems
We study the most suitable procedure to measure the effective temperature in
off-equilibrium systems. We analyze the stationary current established between
an off-equilibrium system and a thermometer and the necessary conditions for
that current to vanish. We find that the thermometer must have a short
characteristic time-scale compared to the typical decorrelation time of the
glassy system to correctly measure the effective temperature. This general
conclusion is confirmed analyzing an ensemble of harmonic oscillators with
Monte Carlo dynamics as an illustrative example of a solvable model of a glass.
We also find that the current defined allows to extend Fourier's law to the
off-equilibrium regime by consistently defining effective transport
coefficients. Our results for the oscillator model explain why thermal
conductivities between thermalized and frozen degrees of freedom in structural
glasses are extremely small.Comment: 7 pages, REVTeX, 4 eps figure
Quantum-Liouville and Langevin Equations for Gravitational Radiation Damping
From a forward--backward path integral, we derive a master equation for the
emission and absorption of gravitons by a massive quantum object in a heat bath
of gravitons. Such an equation could describe collapse phenomena of dense
stars. We also present a useful approximate Langevin equation for such a
system.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper (including all PS fonts) at
http://www.physik.fu-berlin.de/~kleinert/31
The 4D geometric quantities versus the usual 3D quantities. The resolution of Jackson's paradox
In this paper we present definitions of different four-dimensional (4D)
geometric quantities (Clifford multivectors). New decompositions of the torque
N and the angular momentum M (bivectors) into 1-vectors N_{s}, N_{t} and M_{s},
M_{t} respectively are given. The torques N_{s}, N_{t} (the angular momentums
M_{s}, M_{t}), taken together, contain the same physical information as the
bivector N (the bivector M). The usual approaches that deal with the 3D
quantities , , , ,
, etc. and their transformations are objected from the viewpoint of
the invariant special relativity (ISR). In the ISR it is considered that 4D
geometric quantities are well-defined both theoretically and
\emph{experimentally} in the 4D spacetime. This is not the case with the usual
3D quantities. It is shown that there is no apparent electrodynamic paradox
with the torque, and that the principle of relativity is naturally satisfied,
when the 4D geometric quantities are used instead of the 3D quantities.Comment: 13 pages, revte
Radiation reaction on charged particles in three-dimensional motion in classical and quantum electrodynamics
We extend our previous work (see arXiv:quant-ph/0501026), which compared the
predictions of quantum electrodynamics concerning radiation reaction with those
of the Abraham-Lorentz-Dirac theory for a charged particle in linear motion.
Specifically, we calculate the predictions for the change in position of a
charged scalar particle, moving in three-dimensional space, due to the effect
of radiation reaction in the one-photon-emission process in quantum
electrodynamics. The scalar particle is assumed to be accelerated for a finite
period of time by a three-dimensional electromagnetic potential dependent only
on one of the spacetime coordinates. We perform this calculation in the
limit and show that the change in position agrees with that
obtained in classical electrodynamics with the Lorentz-Dirac force treated as a
perturbation. We also show for a time-dependent but space-independent
electromagnetic potential that the forward-scattering amplitude at order
does not contribute to the position change in the limit after the
mass renormalization is taken into account.Comment: Latex, 20page
The Vacuum in Light-Cone Field Theory
This is an overview of the problem of the vacuum in light-cone field theory,
stressing its close connection to other puzzles regarding light-cone
quantization. I explain the sense in which the light-cone vacuum is
``trivial,'' and describe a way of setting up a quantum field theory on null
planes so that it is equivalent to the usual equal-time formulation. This
construction is quite helpful in resolving the puzzling aspects of the
light-cone formalism. It furthermore allows the extraction of effective
Hamiltonians that incorporate vacuum physics, but that act in a Hilbert space
in which the vacuum state is simple. The discussion is fairly informal, and
focuses mainly on the conceptual issues. [Talk presented at {\sc Orbis
Scientiae 1996}, Miami Beach, FL, January 25--28, 1996. To appear in the
proceedings.]Comment: 20 pages, RevTeX, 4 Postscript figures. Minor typos correcte
Electrodynamic Radiation Reaction and General Relativity
We argue that the well-known problem of the instabilities associated with the
self-forces (radiation reaction forces) in classical electrodynamics are
possibly stabilized by the introduction of gravitational forces via general
relativity
Interaction of Hawking radiation with static sources in deSitter and Schwarzschild-deSitter spacetimes
We study and look for similarities between the response rates and of a static scalar source
with constant proper acceleration interacting with a massless,
conformally coupled Klein-Gordon field in (i) deSitter spacetime, in the
Euclidean vacuum, which describes a thermal flux of radiation emanating from
the deSitter cosmological horizon, and in (ii) Schwarzschild-deSitter
spacetime, in the Gibbons-Hawking vacuum, which describes thermal fluxes of
radiation emanating from both the hole and the cosmological horizons,
respectively, where is the cosmological constant and is the black
hole mass. After performing the field quantization in each of the above
spacetimes, we obtain the response rates at the tree level in terms of an
infinite sum of zero-energy field modes possessing all possible angular
momentum quantum numbers. In the case of deSitter spacetime, this formula is
worked out and a closed, analytical form is obtained. In the case of
Schwarzschild-deSitter spacetime such a closed formula could not be obtained,
and a numerical analysis is performed. We conclude, in particular, that and do not coincide in
general, but tend to each other when or . Our
results are also contrasted and shown to agree (in the proper limits) with
related ones in the literature.Comment: ReVTeX4 file, 9 pages, 5 figure
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