13 research outputs found
Nonlocal observables and lightcone-averaging in relativistic thermodynamics
The unification of relativity and thermodynamics has been a subject of
considerable debate over the last 100 years. The reasons for this are twofold:
(i) Thermodynamic variables are nonlocal quantities and, thus, single out a
preferred class of hyperplanes in spacetime. (ii) There exist different,
seemingly equally plausible ways of defining heat and work in relativistic
systems. These ambiguities led, for example, to various proposals for the
Lorentz transformation law of temperature. Traditional 'isochronous'
formulations of relativistic thermodynamics are neither theoretically
satisfactory nor experimentally feasible. Here, we demonstrate how these
deficiencies can be resolved by defining thermodynamic quantities with respect
to the backward-lightcone of an observation event. This approach yields novel,
testable predictions and allows for a straightforward-extension of
thermodynamics to General Relativity. Our theoretical considerations are
illustrated through three-dimensional relativistic many-body simulations.Comment: typos in Eqs. (12) and (14) corrected, minor additions in the tex
On the Foundation of the Relativistic Dynamics with the Tachyon
The theoretical foundation of the object moving faster than light in vacuum
({\it tachyon}) is still missing or incomplete. Here we present the classical
foundation of the relativistic dynamics including the tachyon. An anomalous
sign-factor extracted from the transformation of
under the Lorentz transformation, which has been always missed in the usual
formulation of the tachyon, has a crucial role in the dynamics of the tachyon.
Due to this factor the mass of the tachyon transforms in the unusual way
although the energy and momentum, which are defined as the conserved quantities
in all uniformly moving systems, transform in the usual way as in the case of
the object moving slower than light ({\it bradyon}). We show that this result
can be also obtained from the least action approach. On the other hand, we show
that the ambiguities for the description of the dynamics for the object moving
with the velocity of light ({\it luxon}) can be consistently removed only by
introducing a new dynamical variable. Furthermore, by using the fundamental
definition of the momentum and energy we show that the zero-point energy for
any kind of the objects, {\it i.e.}, the tachyon, bradyon, and luxon, which has
been known as the undetermined constant, should satisfy some constraints for
consistency, and we note that this is essentially another novel relativistic
effect. Finally, we remark about the several unsolved problems.Comment: 39 pages, latex, 15 figures avaliable upon reques
Theory of quantum radiation observed as sonoluminescence
Sonoluminescence is explained in terms of quantum radiation by moving
interfaces between media of different polarizability. In a stationary
dielectric the zero-point fluctuations of the electromagnetic field excite
virtual two-photon states which become real under perturbation due to motion of
the dielectric. The sonoluminescent bubble is modelled as an optically empty
cavity in a homogeneous dielectric. The problem of the photon emission by a
cavity of time-dependent radius is handled in a Hamiltonian formalism which is
dealt with perturbatively up to first order in the velocity of the bubble
surface over the speed of light. A parameter-dependence of the zero-order
Hamiltonian in addition to the first-order perturbation calls for a new
perturbative method combining standard perturbation theory with an adiabatic
approximation. In this way the transition amplitude from the vacuum into a
two-photon state is obtained, and expressions for the single-photon spectrum
and the total energy radiated during one flash are given both in full and in
the short-wavelengths approximation when the bubble is larger than the
wavelengths of the emitted light. It is shown analytically that the spectral
density has the same frequency-dependence as black-body radiation; this is
purely an effect of correlated quantum fluctuations at zero temperature. The
present theory clarifies a number of hitherto unsolved problems and suggests
explanations for several more. Possible experiments that discriminate this from
other theories of sonoluminescence are proposed.Comment: Latex file, 28 pages, postscript file with 3 figs. attache