Friday, June 12, 2009 Special Physics Colloquium, 2:00 PM, 102 Thaw Hall, PITT

Prof. Roger Penrose

Oxford University, Mathematics Institute

"Eons Before the Big Bang?"

Abstract:

The cosmic microwave background (CMB) provides much of the impressive evidence for an enormously hot and dense early stage of the universe -- the Big Bang -- but was this singular event actually the absolute beginning? Observations of the CMB are now very detailed, but this very detail presents new puzzles, one of the most blatant being an apparent paradox in relation to the Second Law of thermodynamics. The hypothesis of inflationary cosmology has long been argued to explain away some of these puzzles, but it does not resolve some key issues, including that raised by the Second Law. In this talk, I describe a quite different proposal, which posits a succession of expanding universe aeons prior to our own. The expansion never reverses in this scheme, but the space-time geometry and the physics is nevertheless made consistent through a fundamental but surprising role for conformal geometry. Black-hole evaporation turns out to be central to the Second Law. A preliminary analysis of CMB data, obtained from the WMAP satellite data, provides a tantalizing input to these issues.