Research in Classical and Quantum Gravity

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

This project supports research in gravitational physics at the University of California, Santa Barbara. Many of the deepest problems in theoretical physics revolve around combining Einstein's theory of general relativity with quantum theory. The resulting theory is called "quantum gravity" and is needed to better understand the origin of the universe, the nature of space and time on small scales, and what happens inside black holes. The research supported by this award will use the latest techniques and tools to try to answer some of these fundamental problems. An essential part of this project is the training of graduate students and postdoctoral researchers in the knowledge and techniques that are central to understanding and discovery in gravitational physics. Through a range of forums from public lectures, to informing media reporters, the Principal Investigators will disseminate the directions and results of their research to a broad audience. Society at large will benefit by increasing their understanding of science and the world they live in. James Hartle will continue exploring the interface between quantum mechanics and cosmology. He will work on extending the predictions of the no-boundary quantum state of the universe for observations today to increasingly general and detailed situations. He will further develop the generalizations of quantum mechanics that are necessary for cosmology and investigate cosmologically motivated extensions of quantum mechanics. He proposes to continue to refine our understanding of the origin of the quasiclassical realm of every day experience as an emergent feature of our quantum universe. Gary Horowitz will investigate physics near cosmological singularities in holographic theories of quantum gravity. These are theories in which quantum gravitational degrees of freedom are equivalently described by a lower dimensional nongravitational theory. Horowitz will also explore connections between gravity and condensed matter that can arise using a classical limit of holography. This provides a new tool for the study of superconductivity and other phenomena. In addition, Horowitz will investigate aspects of higher dimensional black holes. Don Marolf will explore a variety of issues in classical and quantum gravity related to black holes, thermodynamics, and entropy. One is to extend arguments that black holes are thermodynamic systems to more general situations. Another is to investigate the possibility that the area of more general surfaces in spacetime might also be associated with entropy, and that spacetime itself may exist only due to thermodynamic phenomena. A final part of his work will continue to study implications of a quantum-mechanical phenomenon (the so-called Hawking effect) that causes black holes to slowly evaporate and which may require significant changes in our understanding of fundamental physics. The methods employed for all this work will be primarily analytic, though it will be supplemented with numerical calculations on desktop computers.