Infinite derivative gravity:a ghost and singularity-free theory

Conroy, Aindriú (2017) Infinite derivative gravity:a ghost and singularity-free theory. PhD thesis, UNSPECIFIED.

PDF (2017conroyphd)
2016conroyphd.pdf - Published Version
Available under License Creative Commons Attribution-NonCommercial-NoDerivs.

Download (6MB)


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.

Item Type:
Thesis (PhD)
ID Code:
Deposited By:
Deposited On:
25 Apr 2017 09:04
Last Modified:
02 May 2022 04:43