This lecture, given by Dr. Philip Oldfield, is part of a running series of public lectures held jointly between the University of Nottingham and the Nottinghamshire Branch of the British Science Association. Each lecture is given by an engaging, informative speaker, and is aimed at a non-specialist general audience. All are welcome! To receive an email reminder in advance of our Public Lectures, complete with an abstract of the talk written by the lecturer, please email nottsbsa@gmail.com and ask to be added to our mailing list.