It's a small world! (Stories from a connected world)

I'm sure you have experienced meeting a stranger at a party, and finding that she is a friend of a schoolmate of yours, or an acquaintance of a relative, or a football teammate of a co-worker. This experience is not so weird as it seems.

In 1967, psychologist Stanley Milgram showed that the expression "it's a small world" is not just a cliché. Milgram sent tens of letters to random US citizens, and asked them to forward the letters to a person in Boston, The address was not given. Participants in the experiments were asked to send the letter to some acquaintance that could be somehow "close" to the recipient. It seemed a hopeless task, but after a few days the recipient in Boston started to get the first letters. By the end of the experiment, more than half of the letters had arrived, through only six intermediaries, on average.

The number six is not that important, as different numbers appear by repeating the experiment. What is surprising is that these numbers are always very small. Playwright John Gwear wrote: "Everybody on this planet is separated by only six other people. The president of the United States. A gondolier in Venice. A native in a rain forest. A Tierra del Fuegan. An Eskimo. I am bound to everyone on this planet by a trail of six people."

Want to know more? Read "Networks. A Very Short Introduction" http://bit.ly/QDxC1M

(Adapted from "Einstein a la platja". Thanks to Barcelona Televisió)

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