How does a person with fixed political opinions influence the voting intentions of other people in an election? According to Mauro Mobilia, a theoretical physicist at the EPFL in Lausanne and Boston University, there are striking similarities between the influence of a zealot in the electorate and a fixed magnetic spin in an array of random spins. Mobilia believes this zealot model could give insights into a wide range of 'many-body' physical systems (M Mobilia 2003 Phys. Rev. Lett. 91 028701). In an election most people weigh up the pros and cons of the candidates before they choose who to...