The day that Leonard Susskind decided he was not going to follow his father into the family plumbing business, his parents were appalled. “My father was a tough guy,” says Prof Susskind with a chuckle. “He said: ‘What do you want to be: a ballet dancer?’ I said: ‘No, I don’t want to be a ballet dancer, I want to be a physicist.’ He said: ‘You aint going to work in no drugstore.’ I said: ‘No, not a pharmacist, a physicist.’ He said: ‘What’s a physicist?’ I said: ‘Like Einstein.’ That shook him and from that moment he got it. My mother was crying and saying, ‘We’re going to be broke,’ and he just looked at her and said: ‘Shut up – he’s going to be Einstein.’” Susskind may not quite be Einstein but he is a very eminent physicist. One of the founders of string theory – the complex branch of mathematics that attempts to unite the weirdness of quantum mechanics and Einstein’s Theory of Relativity – he has been a physics professor at Stanford University for the past 35 years.