Geekspeak: Why Life + Mathematics = Happiness. Graham Tattersall

      Do you nkow the Queen?

      When I was about seven or eight, I went to play with my elder brother on a railway track. My brother, deliberately winding me up, announced that he was going to derail the next train by placing an old penny on the rail. I believed him, and silently prayed for the imminent disaster to somehow be averted. Penny in place, we hid at the bottom of the embankment. The sound of the steam locomotive grew louder as it approached. There was a terrifying sound of steel on steel, of the snorting smoke box, and the train arrived… and passed by, oblivious to our presence. There were no newspaper headlines. The only evidence of our misdemeanour was the penny, now a flattened piece of copper about two inches by one inch, with a slight curl, lying quietly on the ballast between the rails. To this day I still feel a tingle of relief.

      I tell this story because we, like other children of our generation, were pretty free of adult supervision. There were paedophiles, transformer yards and rail tracks waiting to catch the unwary child, but the sense of anxiety about strangers and the world’s danger barely registered.

      One cause of our present-day unease is maybe down to not knowing who is who in our community. In a village of three hundred people a hundred years ago, you would probably know which men had a predatory eye for children. What’s more, you would know their name, and their parents and their brothers and sisters. Nowadays, you might not even know who lives two doors away in your street.

      If we look at the number of children born to each couple and do some simple arithmetic, we can see why this has happened, and consequently why we are now faced with the prospect of identity cards, biometric devices and databases with information about our DNA.

      The story goes like this.

      How often has someone you know done some name-dropping by telling you about a friend of a friend who has met someone famous, or an eighth cousin twice removed who’s starred alongside Tom Cruise? Maybe you know someone whose friend has a relative who works at Buckingham Palace and has spoken to the Queen.

      I come from a middle-class family, but went to a secondary modern school. I have no obvious links to the aristocracy. But now I come to think of it, I do know a woman who was married to a man whose father was General Montgomery’s adjutant during the Second World War, and who as a result was invited to tea with the Queen. That’s just four links between me and the throne.

      Try to forge those links for yourself, and you’ll almost certainly succeed in finding a connection. In fact there’s a good chance of making a chain of personal connections between you and anyone else on Earth using no more than six links in the chain. That means that a friend of a friend of a friend of a friend of a friend knows anyone you care to name – George Bush, Naomi Campbell, Osama bin Laden…