WFU Physics Colloquium

TITLE: Quantum Effects of the Massless Spin One-Half Field in Static Spherically Symmetric Black Hole and Wormhole Spacetimes

SPEAKER: William H. Hirsch ,

TIME: Monday June 29, 2009 at 3:00 PM

PLACE: Room 101 in Olin Physical Laboratory

My research has been in the area of quantum fields in curved spacetime. The goal of this work is to attain a description of quantum effects occurring in systems containing strong gravity. The specific geometries studied are the extreme Reissner-Nordstrom black hole and three static spherically symmetric wormholes. Calculations in this area involve treating the field quantum mechanically on a classical curved background spacetime governed by general relativity. Quantum effects are assessed through the computation of the renormalized quantum stress-energy tensor for the massless spin one-half field. The quantum stress-energy tensor contains information regarding the energy density and pressures created in the vicinity of gravitational sources. These results are compared to utilizing only an analytic approximation for the quantum stress-energy tensor. We find that the approximation is very poor in most cases, even getting the sign wrong for many components. For the extreme Reissner-Nordstrom black hole, divergences predicted by the analytic approximation are shown to be nonexistent. Lastly, the results for the quantum stress-energy tensor for wormholes are analyzed in terms of an arbitrary renormalization parameter to see if the "exotic" energy conditions needed to keep such an object from collapsing are met. No wormhole geometry studied is found to be stable to quantum fluctuations of the spin one-half field when the renormalized calculation is performed. This is in contrast to the results found with the analytic approximation which predicts one of the wormholes is stable.