Six Degrees of Separation: Fact or Fiction?

ByABC News
December 11, 2006, 3:08 PM

Dec. 12, 2006 — -- Most people have heard of the "six degrees of separation" theory -- the idea that everyone in the world is separated from everyone else by six links.

But is the notion just a pop culture myth or a fact of life?

See how "Primetime's" experiment played out on "Basic Instincts: The Human Chain" Wednesday, Dec. 13 at 10 p.m. ET.

"Primetime" resolved to find out by conducting a groundbreaking social experiment. With the help of Columbia University professor Duncan Watts, "Primetime" created a test that pitted real people against each other in a race to see who could connect themselves to a random third individual the fastest, and do it in an unusual way.

For a number of years, Watts has studied Network Theory, the scientific field that examines how networks form and how they work in society. Network Theory covers many subjects, including how people interact socially, how diseases spread, how people find jobs, and even how aspects of the World Wide Web operate.

"You may think that you're sort of locked away in your little part of the world," Watts said. "In fact, you're not. Everyone is connected in some way or another."

As widespread as the notion of six degrees has become since it was hatched in the 1960s and has since become the subject of a play and movie, there has been very little effort to try to prove whether the hypothesis is true. Watts himself has led one of the most significant experiments, Columbia's Small World Project.

The Small World Project is carried out online. In the experiment, each participant, or "searcher," is assigned a random "target," one of 18 people around the world. Their job is to link to this person via e-mail. But there's a catch -- they can't just send an e-mail directly to the target, they must connect by creating a human chain.

First, the participant e-mails someone they know. They ask that person to continue the links by e-mailing someone else they know. The hope is to eventually send an e-mail to someone who knows the target personally, completing the chain.

Some 60,000 people from 170 countries have taken part in the experiment. Of the hundreds of chains that have been completed, Watts says the average number of links has been six, supporting the six degrees of separation theory.