Dr Paul Parsons was formerly a theoretical cosmologist at the University of Sussex, developing models to explain how the microphysics of the Big Bang determined the largescale structure of the universe today. Now a science journalist and author, he has contributed articles to the Guardian, the Daily Telegraph and New Scientist, and has also served both as editor of the award-winning BBC science magazine Focus and as managing editor of BBC Sky at Night magazine. His previous books include The Periodic Table, How to Destroy the Universe and The Science of Doctor Who.