Home > Research > Publications & Outputs > Infinite derivative gravity

Electronic data

  • 2017conroyphd

    Final published version, 6.38 MB, PDF document

    Available under license: CC BY-NC-ND: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License

Text available via DOI:

View graph of relations

Infinite derivative gravity: a ghost and singularity-free theory

Research output: ThesisDoctoral Thesis

Published
Publication date04/2017
Number of pages145
QualificationPhD
Awarding Institution
Supervisors/Advisors
Award date21/04/2017
Publisher
  • Lancaster University
Original languageEnglish

Abstract

The objective of this thesis is to present a viable extension of general relativity free from cosmological singularities. A viable cosmology, in this sense, is one that is free from ghosts, tachyons or exotic matter, while staying true to the theoretical foundations of General Relativity such as general covariance, as well as observed phenomenon such as the accelerated expansion of the universe and inflationary behaviour at later times. To this end, an infinite derivative extension of relativity is introduced, with the gravitational action derived and the non-linear field equations calculated, before being linearised around both Minkowski space and de Sitter space. The theory is then constrained so as to avoid ghosts and tachyons by appealing to the modified propagator, which is also derived. Finally, the Raychaudhuri Equation is employed in order to describe the ghost-free, defocusing behaviour around both Minkowski and de Sitter spacetimes, in the linearised regime.