S1, E3: Todd Sampson takes a leap of faith by bungee jumping with two interwoven phone books, and nothing but the friction between the pages to arrest his fall. With the help of astrophysicist Dr Alan Duffy, Todd explores the law of friction and reveals the latest science behind how this daring experiment actually works. According to Alan's calculations, the phone books will have to sustain at least four times Todd's body weight.