Paul J. Thomas

Comets and the origins and evolution of life

Papers are presented on comets and the formation of biochemical compounds on the primitive earth; the cometary origin of carbon, nitrogen, and water on the earth; comets as a possible source of prebiotic molecules; comet impacts and chemical evolution on the bombarded earth; and cometary supply of terrestrial organics (lessons from the K/T and the present epoch). Other papers are on a computational study of radiation chemical processing in comet nuclei, the origin of the polycyclic aromatic hydrocarbons in meteorites, the fate of organic matter during planetary accretion (preliminary studies of the organic chemistry of experimentally shocked Murchison meteorite), recent observations of interstellar molecules (detection of CCO and a limit on H2C3O), terrestrial and extraterrestrial sources of molecular monochirality, and dark matter in the solar system (hydrogen cyanide polymers).

Energy conservation and Poynting's theorem in the homopolar generator

Most familiar applications of Poyntings theorem concern stationary circuits or circuit elements. Here, we apply Poyntings theorem to the homopolar generator, a conductor moving in a background magnetic field. We show that the electrical power produced by the homopolar generator equals the power lost from the deceleration of the rotating Faraday disk due to magnetic braking and review the way that magnetic braking arises within Poyntings theorem.

Introduction: Comets and the Origin of Life

Extraterrestrial objects such as comets and asteroids (and their associated dust) played a significant dual role in the early history of the Earth’s biosphere: they were both deliverers of organic material and volatiles, and also destroyers of organic material, by the heat and shock of violent impact. The study of the origins of life on Earth attempts to uncover the physical processes operating during this earliest, very turbulent era in the history of our planet. There is still much to learn, despite recent progress in our knowledge of such fundamental issues as the nature of organic chemical processes in space, the chemistry of comets and asteroids and the nature of the early terrestrial environment.