Black Hole Formation, Evaporation and the Information Loss Problem – Dejan Stojkovic

Date: Tue. October 17th, 2006, 11:30 am-12:30 pm
Location: Rockefeller 221

We use the full quantum treatment to study formation of a black hole as seen by an asymptotic observer. Using the Wheeler-de Witt equation to describe a collapsing shell of matter (a spherical domain wall), we show that the black hole takes an infinite time to form in the quantum theory, just as in the classical treatment. Asymptotic observers will therefore see a compact object but never see effects associated with an event horizon. To explore what signals such an observer would see we study radiation of quantum fields in this background using two approaches: functional Schroedinger method and an adaptation of Hawking’s original calculation. The radiation is not exactly thermal, the thermal distribution being superposed with some non-thermal features. We discuss the conjecture based on our analysis that a collapsing shell of matter will evaporate completely by non-thermal radiation and never form a black hole. In this case, gravitational collapse preserves unitarity and our findings may resolve the black hole information loss problem. One might separate the Hilbert space into super-selection sectors: in those with no initial black holes, evolution will be unitary.