Attractive and Repulsive Gravity

We discuss the circumstances under which gravity might be repulsive rather than attractive. In particular we show why our standard solar system distance scale gravitational intuition need not be a reliable guide to the behavior of gravitational phenomena on altogether larger distance scales such as cosmological, and argue that in fact gravity actually gets to act repulsively on such distance scales. With such repulsion a variety of current cosmological problems (the flatness, horizon, dark matter, universe age, cosmic acceleration and cosmological constant problems) are then all naturally resolved.Comment: RevTeX, 31 pages. Prepared for Foundations of Physics Festschrift in honor of Kurt Halle

Torsion, Magnetic Monopoles and Faraday's Law via a Variational Principle

Even though Faraday's Law is a dynamical law that describes how changing $\bf{E}$ and $\bf {B}$ fields influence each other, by introducing a vector potential $A_{\mu}$ according to $F_{\mu\nu}=\partial_{\mu}A_{\nu}-\partial_{\nu}A_{\mu}$ Faraday's Law is satisfied kinematically, with the relation $(-g)^{-1/2}\epsilon^{\mu\nu\sigma\tau}\nabla_{\nu}F_{\sigma\tau}=0$ holding on every path in a variational procedure or path integral. In a space with torsion $Q_{\alpha\beta\gamma}$ the axial vector $S^{\mu}=(-g)^{1/2}\epsilon^{\mu\alpha\beta\gamma}Q_{\alpha\beta\gamma}$ serves as a chiral analog of $A_{\mu}$, and via variation with respect to $S_{\mu}$ one can derive Faraday's Law dynamically as a stationarity condition. With $S_{\mu}$ serving as an axial potential one is able to introduce magnetic monopoles without $S_{\mu}$ needing to be singular or have a non-trivial topology. Our analysis permits torsion and magnetic monopoles to be intrinsically Grassmann, which could explain why they have never been detected. Our procedure permits us to both construct a Weyl geometry in which $A_{\mu}$ is metricated and then convert it into a standard Riemannian geometry.Comment: 4 pages, revtex4. In this version the Weyl geometry connection is taken to be associated with an anti-Hermitian field $iA_{\mu}$ rather than with a Hermitian $A_{\mu}$. It is the anti-Hermitian connection that yields an electromagnetic $A_{\mu}$ that couples to a Dirac fermion in the standard minimally coupled $i\partial_{\mu}-A_{\mu}$ Hermitian wa

Is Cosmic Acceleration Really Recent?

In the standard cosmological paradigm cosmic acceleration is to only be a very recent (viz. $z \leq 1$) phenomenon, with the universe being required to be decelerating at all higher redshifts. We suggest that this particular expectation of the standard model is to be viewed as a quite definitive test not only of the model itself but also of the fine-tuning assumption on which the expectation is based, with the expectation itself actually being readily amenable to testing once the Hubble plot can be extended out to only $z=2$ or so. Moreover, such a modest extension of the Hubble plot will also provide for definitive testing of the non fine-tuned alternate conformal gravity theory, a theory in which the universe is to accelerate both above and below $z=1$.Comment: revtex, 11 pages, 2 figures. To appear in proceedings of "Cosmology and Elementary Particle Physics", Coral Gables Conference, December 2001, B. N. Kursunoglu (Ed.), American Institute of Physics, NY (2002