He studied for a PhD in theoretical physics at Imperial College London, supervised by Andy Albrecht.
He occupied postdoctoral positions at Berkeley and CERN, before returning to the UK to join the faculty in the astrophysics department at the University of Oxford as a research fellow and lecturer.
[6] With Michael Joyce, in 1997 he was one of the first to propose quintessence scalar field models as a possible explanation of dark energy.
He is currently involved in several proposals to test general relativity using the Euclid spacecraft and Square Kilometre Array radio telescope.
He regularly appears on TV and radio to discuss astrophysics and cosmology news stories, and has contributed to several science and mathematics documentaries for the BBC, Discovery Channel, and others.