2,178,506 research outputs found
How does the entropy/information bound work ?
According to the universal entropy bound, the entropy (and hence information
capacity) of a complete weakly self-gravitating physical system can be bounded
exclusively in terms of its circumscribing radius and total gravitating energy.
The bound's correctness is supported by explicit statistical calculations of
entropy, gedanken experiments involving the generalized second law, and
Bousso's covariant holographic bound. On the other hand, it is not always
obvious in a particular example how the system avoids having too many states
for given energy, and hence violating the bound. We analyze in detail several
purported counterexamples of this type (involving systems made of massive
particles, systems at low temperature, systems with high degeneracy of the
lowest excited states, systems with degenerate ground states, or involving a
particle spectrum with proliferation of nearly massless species), and exhibit
in each case the mechanism behind the bound's efficacy.Comment: LaTeX, 10 pages. Contribution to the special issue of Foundation of
Physics in honor of Asher Peres; C. Fuchs and A. van der Merwe, ed
Building Atomic Nuclei with the Dirac Equation
The relevance of the Dirac equation for computations of nuclear structure is
motivated and discussed. Quantitatively successful results for medium- and
heavy-mass nuclei are described, and modern ideas of effective field theory and
density functional theory are used to justify them.Comment: 9 pages, REVTeX 4.0 with 12pt.rtx, aps.rtx, amssymb.tex, bm.sty,
ntgdefs.tex. Contribution to the Dirac Centennial Symposium (FSU, 12/6-7/02
Are there hyperentropic objects ?
By treating the Hawking radiation as a system in thermal equilibrium, Marolf
and R. Sorkin have argued that hyperentropic objects (those violating the
entropy bounds) would be emitted profusely with the radiation, thus opening a
loophole in black hole based arguments for such entropy bounds. We demonstrate,
on kinetic grounds, that hyperentropic objects could only be formed extremely
slowly, and so would be rare in the Hawking radiance, thus contributing
negligibly to its entropy. The arguments based on the generalized second law of
thermodynamics then rule out weakly self-gravitating hyperentropic objects and
a class of strongly self-gravitating ones.Comment: LaTeX, 4 page
Electric field measuring and display system
An apparatus is described for monitoring the electric fields of cloud formations within a particular area. It utilizes capacitor plates that are alternately shielded from the clouds for generating an alternating signal corresponding to the intensity of the electric field of the clouds. A synchronizing signal is produced for controlling sampling of the alternating signal. Such samplings are fed through a filter and converted by an analogue to digital converter into digital form and subsequently fed to a transmitter for transmission to the control station for recording
Bell's inequality and the coincidence-time loophole
This paper analyzes effects of time-dependence in the Bell inequality. A
generalized inequality is derived for the case when coincidence and
non-coincidence [and hence whether or not a pair contributes to the actual
data] is controlled by timing that depends on the detector settings. Needless
to say, this inequality is violated by quantum mechanics and could be violated
by experimental data provided that the loss of measurement pairs through
failure of coincidence is small enough, but the quantitative bound is more
restrictive in this case than in the previously analyzed "efficiency loophole."Comment: revtex4, 3 figures, v2: epl document class, reformatted w slight
change
Gas dispersion measurements using a mobile Raman lidar system
The exploitation of natural gas resources to supply energy demands has resulted in the need to engineer pipelines and plants capable of handling extremely high pressures and throughputs. Consequently, more attention has been directed to evaluating the consequences of releases of material whether accidental or deliberate in nature. An important aspect of assessing the consequences of a release is an understanding of how gas disperses in the atmosphere over a wide range of release and atmospheric conditions. The most cost effective way of providing such information is through the development and use of reliable theoretical prediction methods. The need for some form of remote sensing device was identified. The various possibilities studied led to the conclusion that LIDAR (Light Detection And Ranging) offered the most suitable method. The system designed and built is described, and its recent use in monitoring operational ventings from a high pressure transmission system is discussed
CINDA - Chrysler Improved Numerical Differencing Analyzer computer program
Dimensionless multioption systems compiler computer program constructs and analyzes a mathematical model of any arbitrary one, two, or three dimensional lumped parameter representation of a physical system. It automatically optimizes the utilization of computer core space and is more general and versatile than BETA
- …