Details

Autor(en) / Beteiligte

• Grant, James D. E

Titel

Spacetime distortion and quantum gravity

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1994

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• In this thesis, we are concerned with some problems in quantum gravity and quantum field theory in curved spacetime. In Chapter 1, we study a specific model of a spacetime that admits closed time-like curves and has non-compactly generated chronology horizon. We then quantise a conformally coupled scalar field on this background. We find that the vacuum expectation value of the energy momentum tensor of the field diverges at both the chronology horizon and the polarised hypersurfaces. Although the divergence at the horizon is too weak to be measureable, the divergence at the hypersurface is sufficiently strong that it would radically alter the structure of the spacetime before we expect quantum gravitational effects to come into effect. This suggests that the Chronology Protection Conjecture may also hold on spacetimes with non-compactly generated chronology horizon. Chapter 2 deals with the problem of complex metrics with self-dual Riemann tensor. Starting from the formulation of the problem in terms of Ashtekar variables, we manage to reduce the problem to the study of anon-linear evolution equation, similar to Pleba'nski's First Heavenly Equation. We then construct, formally, the general solution to this equation. We also study the group structure of the equation and find an infinite number of conserved quantities. These quantities have non-vanishing Poisson brackets, i.e. are not in involution. Finally, we show how our formalism is equivalent to the Pleba'nski formulation of this problem. In Chapter 3, we present some work on quantum field theory in curved spacetime carried out in collaboration with H.A. Chamblin and C.J. Fewster. It is an attempt to find a physical interpretation of topological obstructions to Pin structures.