7,623 research outputs found
The Hausdorff moments in statistical mechanics
A new method for solving the Hausdorff moment problem is presented which makes use of Pollaczek polynomials. This problem is severely ill posed; a regularized solution is obtained without any use of prior knowledge. When the problem is treated in the L 2 space and the moments are finite in number and affected by noise or round‐off errors, the approximation converges asymptotically in the L 2 norm. The method is applied to various questions of statistical mechanics and in particular to the determination of the density of states. Concerning this latter problem the method is extended to include distribution valued densities. Computing the Laplace transform of the expansion a new series representation of the partition function Z(β) (β=1/k BT ) is obtained which coincides with a Watson resummation of the high‐temperature series for Z(β)
Reciprocal relativity of noninertial frames and the quaplectic group
Newtonian mechanics has the concept of an absolute inertial rest frame.
Special relativity eliminates the absolute rest frame but continues to require
the absolute inertial frame. General relativity solves this for gravity by
requiring particles to have locally inertial frames on a curved position-time
manifold. The problem of the absolute inertial frame for other forces remains.
We look again at the transformations of frames on an extended phase space with
position, time, energy and momentum degrees of freedom. Under nonrelativistic
assumptions, there is an invariant symplectic metric and a line element dt^2.
Under special relativistic assumptions the symplectic metric continues to be
invariant but the line elements are now -dt^2+dq^2/c^2 and dp^2-de^2/c^2. Max
Born conjectured that the line element should be generalized to the pseudo-
orthogonal metric -dt^2+dq^2/c^2+ (1/b^2)(dp^2-de^2/c^2). The group leaving
these two metrics invariant is the pseudo-unitary group of transformations
between noninertial frames. We show that these transformations eliminate the
need for an absolute inertial frame by making forces relative and bounded by b
and so embodies a relativity that is 'reciprocal' in the sense of Born. The
inhomogeneous version of this group is naturally the semidirect product of the
pseudo-unitary group with the nonabelian Heisenberg group. This is the
quaplectic group. The Heisenberg group itself is the semidirect product of two
translation groups. This provides the noncommutative properties of position and
momentum and also time and energy that are required for the quantum mechanics
that results from considering the unitary representations of the quaplectic
group.Comment: Substantial revision, Publicon LaTe
Self-Interacting Electromagnetic Fields and a Classical Discussion on the Stability of the Electric Charge
The present work proposes a discussion on the self-energy of charged
particles in the framework of nonlinear electrodynamics. We seek magnet- ically
stable solutions generated by purely electric charges whose electric and
magnetic fields are computed as solutions to the Born-Infeld equa- tions. The
approach yields rich internal structures that can be described in terms of the
physical fields with explicit analytic solutions. This suggests that the
anomalous field probably originates from a magnetic excitation in the vacuum
due to the presence of the very intense electric field. In addition, the
magnetic contribution has been found to exert a negative pressure on the
charge. This, in turn, balances the electric repulsion, in such a way that the
self-interaction of the field appears as a simple and natural classical
mechanism that is able to account for the stability of the electron charge.Comment: 8 pages, 1 figur
The Application of Feedback in Measurement
Instrument errors, error reduction, and elements of measurements for measurement systems with feedback instrumentatio
Anharmonic stabilization of the high-pressure simple cubic phase of calcium
The phonon spectrum of the high-pressure simple cubic phase of calcium, in
the harmonic approx- imation, shows imaginary branches that make it
mechanically unstable. In this letter, the phonon spectrum is recalculated
using density-functional theory (DFT) ab initio methods fully including
anharmonic effects up to fourth order at 50 GPa. Considering that perturbation
theory cannot be employed with imaginary harmonic frequencies, a variational
procedure based on the Gibbs- Bogoliubov inequality is used to estimate the
renormalized phonon frequencies. The results show that strong quantum
anharmonic effects make the imaginary phonons become positive even at zero
temperature so that the simple cubic phase becomes mechanically stable, as
experiments suggest. Moreover, our calculations find a superconducting Tc in
agreement with experiments and predict an anomalous behavior of the specific
heat.Comment: 5 pages, 3 figure
Born-Regulated Gravity in Four Dimensions
Previous work involving Born-regulated gravity theories in two dimensions is
extended to four dimensions. The action we consider has two dimensionful
parameters. Black hole solutions are studied for typical values of these
parameters. For masses above a critical value determined in terms of these
parameters, the event horizon persists. For masses below this critical value,
the event horizon disappears, leaving a ``bare mass'', though of course no
singularity.Comment: LaTeX, 15 pages, 2 figure
Nonperturbative calculation of Born-Infeld effects on the Schroedinger spectrum of the hydrogen atom
We present the first nonperturbative numerical calculations of the
nonrelativistic hydrogen spectrum as predicted by first-quantized
electrodynamics with nonlinear Maxwell-Born-Infeld field equations. We also
show rigorous upper and lower bounds on the ground state.
When judged against empirical data our results significantly restrict the
range of viable values of the new electromagnetic constant which is introduced
by the Born-Infeld theory.
We assess Born's own proposal for the value of his constant.Comment: 4p., 2 figs, 1 table; submitted for publicatio
Spontaneous Generation of Photons in Transmission of Quantum Fields in PT Symmetric Optical Systems
We develop a rigorous mathematically consistent description of PT symmetric
optical systems by using second quantization. We demonstrate the possibility of
significant spontaneous generation of photons in PT symmetric systems. Further
we show the emergence of Hanbury-Brown Twiss (HBT) correlations in spontaneous
generation. We show that the spontaneous generation determines decisively the
nonclassical nature of fields in PT symmetric systems. Our work can be applied
to other systems like plasmonic structure where losses are compensated by gain
mechanisms.Comment: 4 pages, 5 figure
Indeterminacy of Holographic Quantum Geometry
An effective theory based on wave optics is used to describe indeterminacy of
position in holographic spacetime with a UV cutoff at the Planck scale.
Wavefunctions describing spacetime positions are modeled as complex
disturbances of quasi-monochromatic radiation. It is shown that the product of
standard deviations of two position wavefunctions in the plane of a holographic
light sheet is equal to the product of their normal separation and the Planck
length. For macroscopically separated positions the transverse uncertainty is
much larger than the Planck length, and is predicted to be observable as a
"holographic noise" in relative position with a distinctive shear spatial
character, and an absolutely normalized frequency spectrum with no parameters
once the fundamental wavelength is fixed from the theory of gravitational
thermodynamics. The spectrum of holographic noise is estimated for the GEO600
interferometric gravitational-wave detector, and is shown to approximately
account for currently unexplained noise between about 300 and 1400Hz. In a
holographic world, this result directly and precisely measures the fundamental
minimum interval of time.Comment: 4 pages, LaTeX. Considerably shortened from earlier version.
Conclusions are unchanged. Submitted to PR
Black holes in extended gravity theories in Palatini formalism
We consider several physical scenarios where black holes within classical
gravity theories including and Ricci-squared corrections and formulated
\`a la Palatini can be analytically studied.Comment: 4 pages, contribution to the "Spanish Relativity Meeting in Portugal
2012 (Progress in Mathematical Relativity, Gravitation and Cosmology)",
Springer Proceedings in Mathematics (to appear
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