7,508 research outputs found
Dynamics and symmetries of a field partitioned by an accelerated frame
The canonical evolution and symmetry generators are exhibited for a
Klein-Gordon (K-G) system which has been partitioned by an accelerated
coordinate frame into a pair of subsystems. This partitioning of the K-G system
is conveyed to the canonical generators by the eigenfunction property of the
Minkowski Bessel (M-B) modes. In terms of the M-B degrees of freedom, which are
unitarily related to those of the Minkowski plane waves, a near complete
diagonalization of these generators can be realized.Comment: 14 pages, PlainTex. Related papers on accelerated frames available at
http://www.math.ohio-state.edu/~gerlac
Paired Accelerated Frames
The geometrical and quantum mechanical basis for Davies' and Unruh's
acceleration temperature is traced to a type of quantum mechanical
(``achronal'') spin. Its existence and definition are based on pairs of
causally disjoint accelerated frames. For bosons the expected spin vector of
monochromatic particles is given by the ``Planckian power'' and the ``r.m.s.
thermal fluctuation'' spectra. Under spacetime translation the spin direction
precesses around that ``Planckian'' vector. By exhibiting the conserved
achronal spin four-current, we extend the identification of achronal spin from
single quanta to multiparticle systems. Total achronal spin conservation is
also shown to hold, even in the presence of quadratic interactions.Comment: 22 pages, Plain Tex, one figure. Also published in Proc. of the 7th
Marcel Grossmann Meeting edited by R.T. Jantzen and G.M. Keiser (World
Scientific, Singapore, 1996), 957-976. Related papers on accelerated frames
are available at http://www.math.ohio-state.edu/~gerlac
Radiation from Bodies with Extreme Acceleration II: Kinematics
When applied to a dipole source subjected to acceleration which is violent
and long lasting (``extreme acceleration''), Maxwell's equations predict
radiative power which augments Larmor's classical radiation formula by a
nontrivial amount. The physical assumptions behind this result are made
possible by the kinematics of a system of geometrical clocks whose tickings are
controlled by cavities which are expanding inertially. For the purpose of
measuring the radiation from such a source we take advantage of the physical
validity of a spacetime coordinate framework (``inertially expanding frame'')
based on such clocks. They are compatible and commensurable with the
accelerated clocks of the accelerated source. By contrast, a common Lorentz
frame with its mutually static clocks won't do: it lacks that commensurability.
Inertially expanding clocks give a physicist a window into the frame of a
source with extreme acceleration. He thus can locate that source and measure
radiation from it without being subjected to such acceleration himself. The
conclusion is that inertially expanding reference frames reveal qualitatively
distinct aspects of nature which would not be accessible if static inertial
frames were the only admissible frames.Comment: This 21-page 13-figure RevTeX4 article is a follow-up to Part I:
"Radiation from violently accelerated bodies", gr-qc/011004
First-order directional ordering transition in the three-dimensional compass model
We study the low-temperature properties of the classical three-dimensional
compass or orbital model on simple-cubic lattices by means of
comprehensive large-scale Monte Carlo simulations. Our numerical results give
evidence for a directionally ordered phase that is reached via a first-order
transition at the temperature . To obtain
our results we employ local and cluster update algorithms, parallel tempering
and multiple histogram reweighting as well as model-specific screw-periodic
boundary conditions, which help counteract severe finite-size effects.Comment: 8.5 pages, 7 figures, 2 table
Coulomb field of an accelerated charge: physical and mathematical aspects
The Maxwell field equations relative to a uniformly accelerated frame, and
the variational principle from which they are obtained, are formulated in terms
of the technique of geometrical gauge invariant potentials. They refer to the
transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge
invariant "2+2" decomposition is used to see how the Coulomb field of a charge,
static in an accelerated frame, has properties that suggest features of
electromagnetism which are different from those in an inertial frame. In
particular, (1) an illustrative calculation shows that the Larmor radiation
reaction equals the electrostatic attraction between the accelerated charge and
the charge induced on the surface whose history is the event horizon, and (2) a
spectral decomposition of the Coulomb potential in the accelerated frame
suggests the possibility that the distortive effects of this charge on the
Rindler vacuum are akin to those of a charge on a crystal lattice.Comment: 27 pages, PlainTex. Related papers available at
http://www.math.ohio-state.edu/~gerlac
Report drawn up on behalf of the Committee on Budgets on the report of the ECSC Auditor for the financial year 1975 and the discharge to be given to the Commission of the European Communities in respect of the financial and budgetary activities in that financial year (Doc. 231/76). EP Working Documents, document 567/76, 28 February 1977
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