New horizons in thermodynamics

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" New horizons in thermodynamics "
G. G. Hayward W. Israel

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112511
Doc. No	:	TLpq230801831
Main Entry	:	G. G. Hayward
	:	W. Israel
Title & Author	:	New horizons in thermodynamics\ G. G. HaywardW. Israel
College	:	University of Alberta (Canada)
Date	:	1991
student score	:	1991
Degree	:	Ph.D.
Page No	:	209
Abstract	:	This thesis collects five papers which treat the theory of horizon thermodynamics and its applications to cosmology. In the first paper I consider general, spherically symmetric spacetimes with cosmological and black hole horizons. I find that a state of thermal equilibrium may exist in classical manifolds with two horizons so long as a matter distribution is present. I calculate the Euclidean action for non-classical manifolds with and without boundary and relate it to the grand canonical weighting factor. I find that the mean thermal energy of the cosmological horizon is negative. In the second paper I derive the first law of thermodynamics for bounded, static, spherically symmetric spacetimes which include a matter distribution and either a black hole or cosmological horizon. I calculate heat capacities associated with matter/horizon systems and find that they may be positive or negative depending on the matter configuration. I discuss the case in which the cosmological constant is allowed to vary and conclude that the Hawking/Coleman mechanisms for explaining the low value of the cosmological constant are not well formulated. In the third paper, co-authored by Jorma Louko, we analyze variational principles for non-smooth metrics. These principles give insight to the problem of constructing minisuperspace path integrals in horizon statistical mechanics and quantum cosmology. We demonstrate that smoothness conditions can be derived from the variational principle as equations of motion. We suggest a new prescription for minisuperspace path integrals on the manifold usd\bar D \times S\sp2usd. In the fourth paper, I examine the contribution of the horizon energy density to black hole temperature. I show the existence of positive heat capacity solutions in the small mass regime. In the fifth paper, co-authored by Diego Pavon we investigate the role of primordial black holes in the very early universe under SU(3) usd\timesusd usdSUusd(2) usd\timesusd usdUusd(1), SU(5), and their supersymmetric counterparts. Three of the four theories predict a phase in which black holes and radiation are of comparable energy density. The fourth theory, SU(5), predicts a radiation dominated model from the Planck era onward. In the concluding general discussion I show how generalized laws of thermodynamics can be related to variations of the classical gravitational action. These laws apply even for non-static, non-spherically symmetric spacetimes.
Subject	:	Astronomy
	:	Astronomy
	:	Astrophysics
	:	cosmology
	:	horizon thermodynamics
	:	Pure sciences