Tuesday, 27 January, 1998 at 3pm

Douglas Scott - Univ of British Columbia

"How the Universe Became Neutral"

ABSTRACT:"The canonical Big Bang model is now considered a very robust basis for all investigations of the evolution of the universe. Although the first tiny fraction of cosmological history requires an understanding of things like quantum gravity, that are not currently well understood, the evolution after a second or so relies only on straightforward, everyday physics. The relevant energies and densities are so low, that you might be forgiven for assuming that everything was already understood in detail. One aspect of the evolution of the universe, which has attracted surprisingly little attention, is the details of how its material contents went from plasma state to being neutral hydrogen and helium gas, when the universe was about 300,000 years old. This talk will concentrate on that epoch, what the physical picture is for what happened back then, and what the implications are for understanding what sort of universe we live in."