John D. Barrow FRS is Professor of Mathematical Sciences at the University of Cambridge and Director of the Millennium Mathematics Project to improve the appreciation of mathematics amongst the general public, teachers, and school students. The recipient of many distinguished prizes, his research interests are in cosmology, gravitation, and the interface between particle physics and astronomy. He is also a prolific author, the most recent of his twenty-two books being 100 Essential Things You Didn't Know You Didn't Know about Maths and the Arts (2014) and The Book of Universes (2011).