5,367 research outputs found
Tests of the Gravitational Inverse-Square Law
We review recent experimental tests of the gravitational inverse-square law
and the wide variety of theoretical considerations that suggest the law may
break down in experimentally accessible regions.Comment: 81 pages, 10 figures, submitted by permission of the Annual Review of
Nuclear and Particle Science. Final version of this material is scheduled to
appear in the Annual Review of Nuclear and Particle Science Vol. 53, to be
published in December 2003 by Annual Reviews, http://AnnualReviews.or
Was Einstein Right? Testing Relativity at the Centenary
We review the experimental evidence for Einstein's special and general
relativity. A variety of high precision null experiments verify the weak
equivalence principle and local Lorentz invariance, while gravitational
redshift and other clock experiments support local position invariance.
Together these results confirm the Einstein Equivalence Principle which
underlies the concept that gravitation is synonymous with spacetime geometry,
and must be described by a metric theory. Solar system experiments that test
the weak-field, post-Newtonian limit of metric theories strongly favor general
relativity. The Binary Pulsar provides tests of gravitational-wave damping and
of strong-field general relativity. Recently discovered binary pulsar systems
may provide additional tests. Future and ongoing experiments, such as the
Gravity Probe B Gyroscope Experiment, satellite tests of the Equivalence
principle, and tests of gravity at short distance to look for extra spatial
dimensions could constrain extensions of general relativity. Laser
interferometric gravitational-wave observatories on Earth and in space may
provide new tests of gravitational theory via detailed measurements of the
properties of gravitational waves.Comment: 21 pages, 3 figures, to be published in "100 Years of Relativity:
Spacetime Structure - Einstein and Beyond", ed. Abhay Ashtekar (World
Scientific, Singapore
Neutrino Oscillations as a Probe of Dark Energy
We consider a class of theories in which neutrino masses depend significantly
on environment, as a result of interactions with the dark sector. Such theories
of mass varying neutrinos (MaVaNs) were recently introduced to explain the
origin of the cosmological dark energy density and why its magnitude is
apparently coincidental with that of neutrino mass splittings. In this Letter
we argue that in such theories neutrinos can exhibit different masses in matter
and in vacuum, dramatically affecting neutrino oscillations. Both long and
short baseline experiments are essential to test for these interactions. As an
example of modifications to the standard picture, we consider simple models
which may simultaneously account for the LSND anomaly, KamLAND, K2K and studies
of solar and atmospheric neutrinos, while providing motivation to continue to
search for neutrino oscillations in short baseline experiments such as BooNE.Comment: 5 pages, 1 figure, refs added, additional data considered, minor
change in conclusions about LSN
Forgery in Cyberspace: The Spoof Could Be on You!
Spoofing is one of the newest forms of cyber-attack, a technological methodology adapted to mask the identity of spammers who have faced hostile reaction in response to bulk, unsolicited, electronic mail messages.[1] Sending Spam, however, is no longer the only reason for deception, as crackers have taken pleasure in the challenge of manipulating computer systems and, additionally, find recreational enjoyment in doing so. In this legal Note, the author’s intent is to show that criminal, rather than civil liability is the best way to effectively deter and punish the spoofer. The injury that results when a computer system’s technological safety measures fail to adequately safeguard the system affects not only the owner of the hijacked e-mail address, but also the Internet Service Provider, and the Network as a whole. Current Anti-Spam Legislation is arguably ineffective at targeting these particular types of malicious attacks, and a different legal approach is suggested
Numerical analyses for treating diffusion in single-, two- and three-phase binary alloy systems
Numerical solutions were applicable for planar, cylindrical, or spherical geometries with any diffusion-zone size and any continuous variation of the diffusion coefficient with concentration. Special techniques were included in the analyses to account for differences in molal volumes, initiation and growth of an intermediate phase, disappearance of a phase, and the presence of an initial composition profile in the specimen. A major improvement in solution accuracy was achieved in the two phase analysis by employing a mass conservation criterion to establish the location of the interface rather than the conventional interface-flux-balance criterion. In the three phase analysis, computation time was minimized without sacrificing solution accuracy by treating the three phase problem as a two phase problem when the thickness of the intermediate phase was less than a preset small value. Three computer codes were developed to perform these analyses
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