5,029 research outputs found
Doubly Special Relativity with a minimum speed and the Uncertainty Principle
The present work aims to search for an implementation of a new symmetry in
the space-time by introducing the idea of an invariant minimum speed scale
(). Such a lowest limit , being unattainable by the particles, represents
a fundamental and preferred reference frame connected to a universal background
field (a vacuum energy) that breaks Lorentz symmetry. So there emerges a new
principle of symmetry in the space-time at the subatomic level for very low
energies close to the background frame (), providing a fundamental
understanding for the uncertainty principle, i.e., the uncertainty relations
should emerge from the space-time with an invariant minimum speed.Comment: 10 pages, 8 figures, Correlated paper in:
http://www.worldscientific.com/worldscinet/ijmpd?journalTabs=read. arXiv
admin note: substantial text overlap with arXiv:physics/0702095,
arXiv:0705.4315, arXiv:0709.1727, arXiv:0805.120
The Maxwell Lagrangian in purely affine gravity
The purely affine Lagrangian for linear electrodynamics, that has the form of
the Maxwell Lagrangian in which the metric tensor is replaced by the
symmetrized Ricci tensor and the electromagnetic field tensor by the tensor of
homothetic curvature, is dynamically equivalent to the Einstein-Maxwell
equations in the metric-affine and metric formulation. We show that this
equivalence is related to the invariance of the Maxwell Lagrangian under
conformal transformations of the metric tensor. We also apply to a purely
affine Lagrangian the Legendre transformation with respect to the tensor of
homothetic curvature to show that the corresponding Legendre term and the new
Hamiltonian density are related to the Maxwell-Palatini Lagrangian for the
electromagnetic field. Therefore the purely affine picture, in addition to
generating the gravitational Lagrangian that is linear in the curvature,
justifies why the electromagnetic Lagrangian is quadratic in the
electromagnetic field.Comment: 9 pages; published versio
Mesoscopic supersolid of dipoles in a trap
A mesoscopic system of indirect dipolar bosons trapped by a harmonic
potential is considered. The system has a number of physical realizations
including dipole excitons, atoms with large dipolar moment, polar molecules,
Rydberg atoms in inhomogenious electric field. We carry out a diffusion Monte
Carlo simulation to define the quantum properties of a two-dimensional system
of trapped dipoles at zero temperature. In dimensionless units the system is
described by two control parameters, namely the number of particles and the
strength of the interparticle interaction. We have shown that when the
interparticle interaction is strong enough a mesoscopic crystal is formed. As
the strength of interactions is decreased a multi-stage melting takes place.
Off-diagonal order in the system is tested using natural orbitals analysis. We
have found that the system might be Bose-condensed even in the case of strong
interparticle interactions. There is a set of parameters for which a spatially
ordered structure is formed while simultaneously the fraction of Bose condensed
particles is non zero. This might be considered as a realization of a
mesoscopic supersolid.Comment: 5 figure
Dynamics of Einstein - de Haas Effect: Application to Magnetic Cantilever
Local time-dependent theory of Einstein - de Haas effect is developed. We
begin with microscopicinteractions and derive dynamical equations that couple
elastic deformations with internal twists due to spins. The theory is applied
to the description of the motion of a magnetic cantilever caused by the
oscillation of the domain wall. Theoretical results are compared with a recent
experiment on Einstein - de Haas effect in a microcantilever.Comment: 7 PR pages, 5 figures, submitted to PR
Vacuum energy and Universe in special relativity
The problem of cosmological constant and vacuum energy is usually thought of
as the subject of general relativity. However, the vacuum energy is important
for the Universe even in the absence of gravity, i.e. in the case when the
Newton constant G is exactly zero, G=0. We discuss the response of the vacuum
energy to the perturbations of the quantum vacuum in special relativity, and
find that as in general relativity the vacuum energy density is on the order of
the energy density of matter. In general relativity, the dependence of the
vacuum energy on the equation of state of matter does not contain G, and thus
is valid in the limit when G tends to zero. However, the result obtained for
the vacuum energy in the world without gravity, i.e. when G=0 exactly, is
different.Comment: LaTeX file, 7 pages, no figures, to appear in JETP Letters, reference
is adde
Reply to "Can gravitational dynamics be obtained by diffeomorphism invariance of action?"
In a previous work we showed that, in a suitable setting, one can use
diffeomorphism invariance in order to derive gravitational field equations from
boundary terms of the gravitational action. Standing by our results we reply
here to a recent comment questioning their validity.Comment: Accepted for publication in PR
Entropy-Enthalpy Compensation May Be a Useful Interpretation Tool for Complex Systems Like Protein-DNA Complexes: An Appeal to Experimentalists
In various chemical systems enthalpy-entropy compensation (EEC) is a
well-known rule of behavior, although the physical roots of it are still not
completely understood. It has been frequently questioned whether EEC is a truly
physical phenomenon or a coincidence due to trivial mathematical connections
between statistical-mechanical parameters - or even simpler: A phantom effect
resulting from the misinterpretation of experimental data. Here, we review EEC
from a new standpoint using the notion of correlation which is essential for
the method of factor analysis, but is not conventional in physics and
chemistry. We conclude that the EEC may be rationalized in terms of hidden (not
directly measurable with the help of the current experimental set-up) but
physically real factors, implying a Carnot-cycle model in which a micro-phase
transition (MPT) plays a crucial role. Examples of such MPTs underlying
physically valid EEC should be typically cooperative processes in
supramolecular aggregates, like changes of structured water at hydrophobic
surfaces, conformational transitions upon ligand-biopolymer binding, and so on,
so forth. The MPT notion could help rationalize the occurrence of EEC in
connection with hydration and folding of proteins,enzymatic reactions,
functioning of molecular motors, DNA de- and rehybridization, as well as
similar phenomena.Comment: 8 pages, 2 Figures, Submitted for publicatio
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
The Electrostatics of Einstein's Unified Field Theory
When sources are added at their right-hand sides, and g_{(ik)} is a priori
assumed to be the metric, the equations of Einstein's Hermitian theory of
relativity were shown to allow for an exact solution that describes the general
electrostatic field of n point charges. Moreover, the injunction of spherical
symmetry of g_{(ik)} in the infinitesimal neighbourhood of each of the charges
was proved to yield the equilibrium conditions of the n charges in keeping with
ordinary electrostatics. The tensor g_{(ik)}, however, cannot be the metric of
the theory, since it enters neither the eikonal equation nor the equation of
motion of uncharged test particles. A physically correct metric that rules both
the behaviour of wave fronts and of uncharged matter is the one indicated by
H\'ely. In the present paper it is shown how the electrostatic solution
predicts the structure of the n charged particles and their mutual positions of
electrostatic equilibrium when H\'ely's physically correct metric is adopted.Comment: 15 pages. Misprints corrected. To appear in General Relativity and
Gravitatio
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