The origin of inflation.
type: CreativeWork
description: The inflationary universe scenario provides an appealing explanation for the riddles of why the observed universe is so flat and isotropic, and it neatly provides a causal mechanism for generating the primordial inhomogeneities which seed the large-scale structure we observe today. However, the 01igin of inflation is still unclear, mainly since we have no compelling evidence for a pe1iod of inflation from M-theory. Moreover, whether inflation actually occurs within a given theory is known to depend strongly on the initial conditions. These conceptual problems of inflation are the driving force behind the research presented in this thesis. We study inflation driven by higher de1ivative quantum effects and show how theories of initial conditions may provide observational discriminants between different inflationary scenarios. First we consider scalar field inflation and develop the techniques to calculate c01Telators of physical observables on a spacelike surface directly from the Euclidean no boundary path integral. We perturbatively evaluate the path integral for metric fluctuations around both regular and singular instanton saddle points. The real-space Euclidean two-point correlator is analytically continued into the Lorentzian universe, where it describes the quantum mechanical vacuum fluctuations of the graviton field in the state described by no boundary initial conditions. Unlike the usual approach to inflationary perturbations, the Euclidean path integral unambiguously specifies the graviton propagators with no additional assumptions. From our results for the two-point c01Telation functions we deduce predictions for the cosmic microwave background (CMB) anisotropies and compare this with what is observed today. It is shown that the long wavelength gravity waves would allow us to probe the initial state, if there were sufficient curvature left in the present-day universe. The lack of compelling theoretical evidence casts doubt on the claim that the potential e…
abstract: The inflationary universe scenario provides an appealing explanation for the riddles of why the observed universe is so flat and isotropic, and it neatly provides a causal mechanism for generating the primordial inhomogeneities which seed the large-scale structure we observe today. However, the 01igin of inflation is still unclear, mainly since we have no compelling evidence for a pe1iod of inflation from M-theory. Moreover, whether inflation actually occurs within a given theory is known to depend strongly on the initial conditions. These conceptual problems of inflation are the driving force behind the research presented in this thesis. We study inflation driven by higher de1ivative quantum effects and show how theories of initial conditions may provide observational discriminants between different inflationary scenarios. First we consider scalar field inflation and develop the techniques to calculate c01Telators of physical observables on a spacelike surface directly from the Euclidean no boundary path integral. We perturbatively evaluate the path integral for metric fluctuations around both regular and singular instanton saddle points. The real-space Euclidean two-point correlator is analytically continued into the Lorentzian universe, where it describes the quantum mechanical vacuum fluctuations of the graviton field in the state described by no boundary initial conditions. Unlike the usual approach to inflationary perturbations, the Euclidean path integral unambiguously specifies the graviton propagators with no additional assumptions. From our results for the two-point c01Telation functions we deduce predictions for the cosmic microwave background (CMB) anisotropies and compare this with what is observed today. It is shown that the long wavelength gravity waves would allow us to probe the initial state, if there were sufficient curvature left in the present-day universe. The lack of compelling theoretical evidence casts doubt on the claim that the potential e…
author: Hertog, Thomas
language: eng
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/c8d76f95-86e5-45c3-a5d7-7584601dd596/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2002-02-12
date modified: 2026-07-24T01:33:11Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.11630