Fine-structure constant variability, equivalence principle and cosmology

It has been widely believed that variability of the fine-structure constant alpha would imply detectable violations of the weak equivalence principle. This belief is not justified in general. It is put to rest here in the context of the general framework for alpha variability [J. D. Bekenstein, Phys. Rev. D 25, 1527 (1982)] in which the exponent of a scalar field plays the role of the permittivity and inverse permeability of the vacuum. The coupling of particles to the scalar field is necessarily such that the anomalous force acting on a charged particle by virtue of its mass's dependence on the scalar field is cancelled by terms modifying the usual Coulomb force. As a consequence a particle's acceleration in external fields depends only on its charge to mass ratio, in accordance with the principle. And the center of mass acceleration of a composite object can be proved to be independent of the object's internal constitution, as the weak equivalence principle requires. Likewise the widely employed assumption that the Coulomb energy of matter is the principal source of the scalar field proves wrong; Coulomb energy effectively cancels out in the continuum description of the scalar field's dynamics. This cancellation resolves a cosmological conundrum: with Coulomb energy as source of the scalar field, the framework would predict a decrease of alpha with cosmological expansion, whereas an increase is claimed to be observed. Because of the said cancellation, magnetic energy of cosmological baryonic matter is the main source of the scalar field. Consequently the expansion is accompanied by an increase in alpha; for reasonable values of the framework's sole parameter, this occurs at a rate consistent with the observers' claims.Comment: RevTeX-4, 22 pages, no figures, added a section on caveats as well as several new references with discussion of them in body. To appear in Phys. Rev.

A scalar-tensor cosmological model with dynamical light velocity

The dynamical consequences of a bimetric scalar-tensor theory of gravity with a dynamical light speed are investigated in a cosmological setting. The model consists of a minimally-coupled self-gravitating scalar field coupled to ordinary matter fields in the standard way through the metric: \metric_{\mu\nu}+B\partial_\mu\phi\partial_\nu\phi. We show that in a universe with matter that has a radiation-dominated equation of state, the model allows solutions with a de Sitter phase that provides sufficient inflation to solve the horizon and flatness problems. This behaviour is achieved without the addition of a potential for the scalar field, and is shown to be largely independent of its introduction. We therefore have a model that is fundamentally different than the potential-dominated, slowly-rolling scalar field of the standard models inflationary cosmology. The speed of gravitational wave propagation is predicted to be significantly different from the speed of matter waves and photon propagation in the early universe.Comment: 12 pages, uses amsart and amssymb. Minor corrections, to appear in Phys. Lett.

Comments on "Note on varying speed of light theories"

In a recent note Ellis criticizes varying speed of light theories on the grounds of a number of foundational issues. His reflections provide us with an opportunity to clarify some fundamental matters pertaining to these theories

International Environmental Evaluation for the Helical Screw Expander Generator Unit Projects in Cesano, Italy and Broadlands, New Zealand

The objectives of the Helical Screw Expander (HSE) Generator Program are (1) to accelerate the development of geothermal resources by introducing this advanced conversion technology, (2) to provide operating experience to prospective users of the equipment, and (3) to collect data on the performance and reliability of the equipment under various geothermal resource conditions. The participants hope to achieve these goals by testing a small-scale, transportable HSE generator at existing geothermal test facilities that produce fluids of different salinity, temperature and pressure conditions. This Environmental Evaluation has been prepared, using available information, to analyze the environmental consequences of testing the HSE generator. Its purpose is to support a decision on the need for a complete environmental review of the HSE program under the terms of Executive Order 121 14, ''Environmental Effects Abroad of Major federal Actions''. This Executive Order requires review of projects which involve the release of potentially toxic effluents that are strictly regulated in the United States, or which may have significant environmental effects on the global commons, on natural or ecological resources of international significance, or on the environment of non-participating countries. The final guidelines implementing the provisions of the Executive Order for DOE have been published. This evaluation deals with testing to be conducted at Cesano, Italy by the designated contractor of the Italian government, the Ente Narionale per l'Energia Ellectrica (ENEL), and at Broadlands, New Zealand by the Ministry of Works and Development of New Zealand. Testing at Cerro Prieto, Mexico has already been completed by the Comision Federal de Electricidad and is not evaluated in this report

When Goal Orientations Collide: Effects of Learning and Performance Orientation on Team Adaptability in Response to Workload Imbalance

The authors draw on resource allocation theory (Kanfer & Ackerman, 1989) to develop hypotheses regarding the conditions under which collective learning and performance orientation have interactive effects and the nature of those effects on teams' ability to adapt to a sudden and dramatic change in workload. Consistent with the theory, results of a laboratory study in which teams worked on a computerized, decision-making task over 3 performance trials revealed that learning and performance orientation had independent effects on team adaptability when teams had slack resources available for managing their changed task. Time helped explain the independent effects of performance orientation. Results also revealed that learning and performance orientation had interactive effects when teams did not have slack resources. Finally, the results of this study indicate that teams lacking slack resources were better able to balance high levels of learning and performance orientation over time with practice on the changed task. © 2010 American Psychological Association

Dynamical System Approach to Cosmological Models with a Varying Speed of Light

Methods of dynamical systems have been used to study homogeneous and isotropic cosmological models with a varying speed of light (VSL). We propose two methods of reduction of dynamics to the form of planar Hamiltonian dynamical systems for models with a time dependent equation of state. The solutions are analyzed on two-dimensional phase space in the variables $(x, \dot{x})$ where $x$ is a function of a scale factor $a$. Then we show how the horizon problem may be solved on some evolutional paths. It is shown that the models with negative curvature overcome the horizon and flatness problems. The presented method of reduction can be adopted to the analysis of dynamics of the universe with the general form of the equation of state $p=\gamma(a)\epsilon$. This is demonstrated using as an example the dynamics of VSL models filled with a non-interacting fluid. We demonstrate a new type of evolution near the initial singularity caused by a varying speed of light. The singularity-free oscillating universes are also admitted for positive cosmological constant. We consider a quantum VSL FRW closed model with radiation and show that the highest tunnelling rate occurs for a constant velocity of light if $c(a) \propto a^n$ and $-1 < n \le 0$. It is also proved that the considered class of models is structurally unstable for the case of $n < 0$.Comment: 18 pages, 5 figures, RevTeX4; final version to appear in PR

Black holes in the varying speed of light theory

We consider the effect of the \emph{Varying Speed of Light} theory on non-rotating black holes. We show that in any varying-$c$ theory, the Schwarzschild solution is neither static nor stationary. For a no-charged black hole, the singularity in the Schwarzschild horizon cannot be removed by coordinate transformation. Hence, no matter can enter the horizon, and the interior part of the black hole is separated from the rest of the Universe. If $\dot{c}<0$, then the size of the Schwarzschild radius increases with time. The higher value of the speed of light in the very early Universe may have caused a large reduction in the probability of the creation of the primordial black holes and their population.The same analogy is also considered for the charged black holes.Comment: 5 page

A time-space varying speed of light and the Hubble Law in static Universe

We consider a hypothetical possibility of the variability of light velocity with time and position in space which is derived from two natural postulates. For the consistent consideration of such variability we generalize translational transformations of the Theory of Relativity. The formulae of transformations between two rest observers within one inertial system are obtained. It is shown that equality of velocities of two particles is as relative a statement as simultaneity of two events is. We obtain the expression for the redshift of radiation of a rest source which formally reproduces the Hubble Law. Possible experimental implications of the theory are discussed.Comment: 7 page

Planning an integrated agriculture and health program and designing its evaluation: Experience from Western Kenya.

AbstractMulti-sectoral programs that involve stakeholders in agriculture, nutrition and health care are essential for responding to nutrition problems such as vitamin A deficiency among pregnant and lactating women and their infants in many poor areas of lower income countries. Yet planning such multi-sectoral programs and designing appropriate evaluations, to respond to different disciplinary cultures of evidence, remain a challenge. We describe the context, program development process, and evaluation design of the Mama SASHA project (Sweetpotato Action for Security and Health in Africa) which promoted production and consumption of a bio-fortified, orange-fleshed sweetpotato (OFSP). In planning the program we drew upon information from needs assessments, stakeholder consultations, and a first round of the implementation evaluation of a pilot project. The multi-disciplinary team worked with partner organizations to develop a program theory of change and an impact pathway which identified aspects of the program that would be monitored and established evaluation methods. Responding to the growing demand for greater rigour in impact evaluations, we carried out quasi-experimental allocation by health facility catchment area, repeat village surveys for assessment of change in intervention and control areas, and longitudinal tracking of individual mother-child pairs. Mid-course corrections in program implementation were informed by program monitoring, regular feedback from implementers and partners’ meetings. To assess economic efficiency and provide evidence for scaling we collected data on resources used and project expenses. Managing the multi-sectoral program and the mixed methods evaluation involved bargaining and trade-offs that were deemed essential to respond to the array of stakeholders, program funders and disciplines involved

2d Stringy Black Holes and Varying Constants

Motivated by the recent interest on models with varying constants and whether black hole physics can constrain such theories, two-dimensional charged stringy black holes are considered. We exploit the role of two-dimensional stringy black holes as toy models for exploring paradoxes which may lead to constrains on a theory. A two-dimensional charged stringy black hole is investigated in two different settings. Firstly, the two-dimensional black hole is treated as an isolated object and secondly, it is contained in a thermal environment. In both cases, it is shown that the temperature and the entropy of the two-dimensional charged stringy black hole are decreased when its electric charge is increased in time. By piecing together our results and previous ones, we conclude that in the context of black hole thermodynamics one cannot derive any model independent constraints for the varying constants. Therefore, it seems that there aren't any varying constant theories that are out of favor with black hole thermodynamics.Comment: 12 pages, LaTeX, to appear in JHE