The physics of the Big Bang. By studying the very early Universe we can test fundamental theories of physics. I am currently working on the gravitational waves from the very early universe, dynamics and observational signatures of strings in cosmology, and particle physics theories of inflation and the Big Bang.

Much of my research uses large numerical simulations of processes in the early universe. Here's one from the Cosmic Defects YouTube channel, showing a visualisation of the Higgs field turning on at around 10 picoseconds after the beginning of the Universe. The coloured rings are slices through spherical compression waves surrounding the expanding bubbles of Higgs field. The video was made by my collaborator David Weir (University of Helsinki).

Here's an interview with me talking about gravitational waves, with interviewer Jonathan Hare of the Creative Science Centre: Gravitational waves and the early universe