Physics stuff

By way of "right of use", if you use any of my work, please reference me. Preferably, ask me first. Do not copy any of my reports for your own use.

Lectures on relativistic materials

PhD thesis

Generalized perturbations in modified gravity and dark energy
My thesis got published as a hardback book by Springer. You can buy it from amazon. If you ask me nicely, I'll give you an e-copy.


My publications from HEP SPIRES, ADS and Google Scholar.

Simulating the symmetron: domain walls and symmetry-restoring impurities
[arXiv:1409.6570, submitted to PRD]. Also see symmetron page.

Constraining dark sector perturbations I: cosmic shear and CMB lensing
[arXiv:1409.4650, submitted to JCAP]

Material models of dark energy
[arXiv:1403.1213, Annalen Phys.526(2014)7-8,318-339 ]

Computing model independent perturbations in dark energy and modified gravity
[arXiv:1311.6737, JCAP1403(2014)051]

Simple implementation of general dark energy models
[arXiv:1310.6033, JCAP1403(2014)017]

Parameterizing perturbations in the dark sector via equations of state
[arXiv:1306.1175, PhysRevD88(061301)2013]

Massive gravity, the elasticity of space-time and perturbations in the dark sector
[arXiv:1301.5042, PhysRevD88(084004)2013]

Effective field theory for perturbations in dark energy and modified gravity
[arXiv:1205.3611, conference proceedings]

Effective action approach to cosmological perturbations in dark energy and modified gravity
[arXiv:1203.0398, JCAP1207(2012)019]

X-type and Y-type junction stability in domain wall networks
[arXiv:1107.1325, PhysRevD84(125032)2011]

Charge, domain walls and dark energy
[arXiv:1010.3195, conference proceedings]

Charge, junctions and the scaling dynamics of domain wall networks
[arXiv:1010.2328, PhysRevD82(125001)2010]

Formation and evolution of kinky vortons
[arXiv:0908.1865, JCAP09(2009)039]


These are titles of some talks I have given

  • Massive gravity and elasticity of space-time
  • Parameterizing dark sector perturbations here is a recording from the talk I gave at Perimeter Institute
  • Relativistic elasticity theory
  • Domain wall network dynamics
  • Generalized modified gravity
  • Stationary gauged vorton solutions
  • Solitons: how to describe extended objects in physics Notes
  • Inhomogeneous universes
  • Non-technical introduction to modified gravity: YouTube Part 1, part 2, part 2, part 4. Slides Modified gravity

Gravitational theories and cosmology: this is the Introduction chapter to my thesis. It is a relatively self contained introduction to gravitational theories, general relativity, cosmology, perturbation theory in cosmology, the dark sector and modified gravity. Download here.

PhD literature review: field theoretic models of dark energy.

PhD transfer report: dark energy and fundamental cosmology.

Notes on solitons: These are notes from a talk I gave to the University of Manchester's PhysSoc. It's an introduction to solitons, domain walls and charged solitons. The notes are very rough, and not at all polished! Download here.

Faith and science: two sides of the same coin?
I gave this talk at St. Marys, Wythall. Here are my notes and slides. Please be aware that the notes are quite rough in places!

Index notation, tensors and dynamics

These are some notes I constructed a few years ago (pre-2008). There are probably a lot of mistakes in the notes, but the ideas (may) be correct.

  • Index notation: This is a "new" document, that is all my own work. It explains the usage of index notation, in a way which is rarely found in a single book/course. It is a work in progress, so is rather rough and unchecked in places.
  • Tensor Calculus 1: This is the first in a series on tensor calculus. It introduces tensors (covariant & contravariant), geodesics, and begins on general relativity.
  • Tensor Calculus 2: This chapter discusses differentiation of tensors.
  • Appended versions in "Index Notation".... these ones have a lot of mistakes!
  • Notes on Special and General Relativity: Does what it says on the tin. Given by Dr.P.Dale. This is a work in progress, so will be added to.

  • Warning: the above set of notes have been given by Dr.P.Dale; they use un-conventional notation, so should be used with care. However, they do provide an aid to tensor manipulations.
Summer project 2008: cosmic texture

This is the report I produced during a summer project, 2008, at the University of Manchester, supervised by Dr.R.Battye.

We discuss a possible explanation of the observed 5degree cold spot in the CMB as being an unwound topological defect known as texture. We briefly discuss the nature of texture. We then discuss numerical simulations of texture populated skies, and numerically find their power spectrum. We then discuss the covariance matrices of texture only skies, finding that textures are non-Gaussian distributes, with zero bispectrum. We also derive the distribution of textures, extending the approximation of Cruz. We derive analytic expressions for the power spectrum of both a single spot & whole sky, and numerically evaluate them; thus providing previously unused computationally trivial methods for finding such spectra.

MPhys project 2008/9: The dynamics of charged domain walls

This the MPhys report that I produced during my fourth year 2008/9, at the University of Manchester, supervised by Dr.R.Battye.

We investigate the dynamics of a class topological defects known as domain walls. We consider models with interacting fields with junctions and charge, possessing a O(N)xU(1) symmetry with cubic anisotropy terms. We find that a phase separation is possible, between domain and charge, and that if phase separation occurs, domain walls do not scale. This is a more general case of our finding that kinky vortons form from random initial conditions, preventing walls from scaling, in the regime where symmetry currents associate with domain walls.
  • Download here. This is a very low quality version of the report. Contact me if you want better quality images and videos.