for National Geographic News
How well do you know Madonna? Do you consider Tiger Woods a buddy? What about former South African President Nelson Mandela?
According to the "small world" theory, you should be just six handshakes away from each of them. But can anyone in the world really reach anyone else through a chain of just six friends?
Yes, say researchers from Columbia University in New York, who have published the first results of their "Small World Research Project."
They identified 18 target people in 13 different countries, then asked participants to get a message through to the target by sending e-mails to friends and acquaintances.
On average, researchers say, people can reach their targets in five to seven steps.
The study also collected demographic data to find out what barriers make it difficult for messages to get through and to deduce what strategy participants use to reach their intended target.
More than 60,000 people participated, creating about 24,000 message chains. Yet less than 400 messages actually reached their targets.
But that failure rate is deceptive. Researchers believe that most people who failed to pass on messages had people they could contact, but simply forgot or didn't want to participate.
"The world is connected, but people don't always believe they are connected," said Duncan Watts, the Columbia University sociology professor who led the project. "It's the perception of connectivity that is most important."
Six Degrees of Separation
In 1967, the social psychologist Stanley Milgram conducted an experiment to test the theory that members of a large social networkin his case, the population of the United Stateswould be connected through a short chain of intermediate acquaintances.
Milgram sent packets to 400 randomly selected people in Kansas and Nebraska, with the aim of sending the packets to a target person in Massachusetts. He instructed the participants to send the packets to someone they knew on a first-name basis, who they thought was more likely to know the target than they were themselves.
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