arXiv subjects

Alan A Coley

Publications and source records attributed to Alan A Coley.

3 recordsLinked to original sources

arXiv2024

The sounds of science a symphony for many instruments and voices part II

Despite its amazing quantitative successes and contributions to revolutionary technologies, physics currently faces many unsolved mysteries ranging from the meaning of quantum mechanics to the nature of the dark energy that will determine the future of the Universe. It is clearly prohibitive for the general reader, and even the best informed physicists, to follow the vast number of technical papers published in the thousands of specialized journals. For this reason, we have asked the leading experts across many of the most important areas of physics to summarise their global assessment of some of the most important issues. In lieu of an extremely long abstract summarising the contents, we invite the reader to look at the section headings and their authors, and then to indulge in a feast of stimulating topics spanning the current frontiers of fundamental physics from The Future of Physics by William D Phillips and What characterises topological effects in physics? by Gerard t Hooft through the contributions of the widest imaginable range of world leaders in their respective areas. This paper is presented as a preface to exciting developments by senior and young scientists in the years that lie ahead, and a complement to the less authoritative popular accounts by journalists.

physics.soc-ph↗

arXiv1999

Qualitative Analysis of Early Universe Cosmologies

A qualitative analysis is presented for a class of homogeneous cosmologies derived from the string effective action when a cosmological constant is present in the matter sector of the theory. Such a term has significant effects on the qualitative dynamics. For example, models exist which undergo a series of oscillations between expanding and contracting phases due to the existence of a heteroclinic cycle in the phase space. Particular analytical solutions corresponding to the equilibrium points are also found.

gr-qc↗

arXiv1998

On the Asymptotic Behaviour of Cosmological Models in Scalar-Tensor Theories of Gravity

We study the qualitative properties of cosmological models in scalar-tensor theories of gravity by exploiting the formal equivalence of these theories with general relativity minimally coupled to a scalar field under a conformal transformation and field redefinition. In particular, we investigate the asymptotic behaviour of spatially homogeneous cosmological models in a class of scalar-tensor theories which are conformally equivalent to general relativistic Bianchi cosmologies with a scalar field and an exponential potential whose qualitative features have been studied previously. Particular attention is focussed on those scalar-tensor theory cosmological models, which are shown to be self-similar, that correspond to general relativistic models that play an important rôle in describing the asymptotic behaviour of more general models (e.g., those cosmological models that act as early-time and late-time attractors).

gr-qc↗