4,546 research outputs found
The Quantum Newton's Law
Using the quantum Hamilton-Jacobi equation within the framework of the
equivalence postulate, we construct a Lagrangian of a quantum system in one
dimension and derive a third order equation of motion representing a first
integral of the quantum Newton's law. We then integrate this equation in the
free particle case and compare our results to those of Floydian trajectories.
Finally, we propose a quantum version of Jacobi's theorem.Comment: 10 pages, LateX, no figures, minor change
Is the Universe More Transparent to Gamma Rays Than Previously Thought?
The MAGIC collaboration has recently reported the detection of the strong
gamma-ray blazar 3C279 during a 1-2 day flare. They have used their spectral
observations to draw conclusions regarding upper limits on the opacity of the
Universe to high energy gamma-rays and, by implication, upper limits on the
extragalactic mid-infrared background radiation. In this paper we examine the
effect of gamma-ray absorption by the extragalactic infrared radiation on
intrinsic spectra for this blazar and compare our results with the
observational data on 3C279. We find agreement with our previous results,
contrary to the recent assertion of the MAGIC group that the Universe is more
transparent to \gray s than our calculations indicate. Our analysis indicates
that in the energy range between ~80 and ~500 GeV, 3C279 has a best-fit
intrinsic spectrum with a spectral index ~1.78 using our fast evolution model
and ~2.19 using our baseline model. However, we also find that spectral indices
in the range of 0.0 to 3.0 are almost as equally acceptable as the best fit
spectral indices. Assuming the same intrinsic spectral index for this flare as
for the 1991 flare from 3C279 observed by EGRET, viz., 2.02, which lies between
our best fit indices, we estimate that the MAGIC flare was ~3 times brighter
than the EGRET flare observed 15 years earlier.Comment: version accepted for publication in ApJ Letter
The high energy limit of the trajectory representation of quantum mechanics
The trajectory representation in the high energy limit (Bohr correspondence
principle) manifests a residual indeterminacy. This indeterminacy is compared
to the indeterminacy found in the classical limit (Planck's constant to 0)
[Int. J. Mod. Phys. A 15, 1363 (2000)] for particles in the classically allowed
region, the classically forbiden region, and near the WKB turning point. The
differences between Bohr's and Planck's principles for the trajectory
representation are compared with the differences between these correspondence
principles for the wave representation. The trajectory representation in the
high energy limit is shown to go to neither classical nor statistical
mechanics. The residual indeterminacy is contrasted to Heisenberg uncertainty.
The relationship between indeterminacy and 't Hooft's information loss and
equivalence classes is investigated.Comment: 12 pages of LaTeX. No figures. Incorporated into the "Proceedings of
the Seventh International Wigner Symposium" (ed. M. E. Noz), 24-29 August
2001, U. of Maryland. Proceedings available at
http://www.physics.umd.edu/robo
A Determination of the Intergalactic Redshift Dependent UV-Optical-NIR Photon Density Using Deep Galaxy Survey Data and the Gamma-ray Opacity of the Universe
We calculate the intensity and photon spectrum of the intergalactic
background light (IBL) as a function of redshift using an approach based on
observational data obtained in many different wavelength bands from local to
deep galaxy surveys. This allows us to obtain an empirical determination of the
IBL and to quantify its observationally based uncertainties. Using our results
on the IBL, we then place 68% confidence upper and lower limits on the opacity
of the universe to gamma-rays, free of the theoretical assumptions that were
needed for past calculations. We compare our results with measurements of the
extragalactic background light and upper limits obtained from observations made
by the Fermi Gamma-ray Space Telescope.Comment: 32 pages, 6 figures, Accepted for publication in the Astrophysical
Journa
An Empirical Determination of the Intergalactic Background Light Using NIR Deep Galaxy Survey Data out to 5 microns and the Gamma-ray Opacity of the Universe
We extend our previous model-independent determination of the intergalactic
background light (IBL), based purely on galaxy survey data, out to a wavelength
of 5 microns. Our approach enables us to constrain the range of photon
densities, based on the uncertainties from observationally determined
luminosity densities and colors. We further determine a 68% confidence upper
and lower limit on the opacity of the universe to gamma-rays up to energies of
1.6/(1+z) TeV. A comparison of our lower limit redshift-dependent opacity
curves to the opacity limits derived from the results of both ground-based air
Cherenkov telescope and Fermi-LAT observations of PKS 1424+240 allows us to
place a new upper limit on the redshift of this source, independent of IBL
modeling.Comment: version accepted for publication in the Astrophysical Journal, 23
pages, 4 figure
An Empirical Determination of the Intergalactic Background Light from UV to FIR Wavelengths Using FIR Deep Galaxy Surveys and the Gamma-ray Opacity of the Universe
We have previously calculated the intergalactic background light (IBL) as a
function of redshift in the far ultraviolet to near infrared range, based
purely on data from deep galaxy surveys. Here we utilize similar methods to
determine the mid- and far infrared IBL out to a wavelength of 850 microns. Our
approach enables us to constrain the range of photon densities, based on the
uncertainties from observationally determined luminosity densities and colors.
By also including the effect of the 2.7 K cosmic background photons, we
determine 68% confidence upper and lower limits on the opacity of the universe
to gamma-rays up to PeV energies. Our direct results on the IBL are consistent
with those from complimentary gamma-ray analyses using observations from the
Fermi -ray space telescope and the H.E.S.S. air Cherenkov telescope.
Thus, we find no evidence of previously suggested processes for the
modification of gamma-ray spectra other than that of absorption by pair
production alone.Comment: 33 pages, 11 figures, replacement matches article published in ApJ
827:6 (2016
Sorobon (Abacus) to Silicon Chip
This report covers the objectives with which the writer was guided in the planning and implementation of his faculty development leave in Japan for the academic year 1983-84. today, (2) Japanese Initial objectives were to study language, (3) women in (1) Japanese culture leadership roles, (4) characteristics of high-achieving Japanese students in the areas of mathematics and science, and (5) the reasons why Japanese students surpass their American counterparts in these areas
- …