When the World Wide Web happened, it was only natural to expect that someone would repeat Milgram's original snail mail experiment with electronic networking tools across the globe.

Milgram's original experiment involved sending about 300 letters to a random list of people in the town of Omaha in Nebraska. Each was instructed to forward the letter to a 'target' person in Boston using personal contacts alone. There was some information provided about the target, on the basis of which each sender would try and establish contact either directly or via someone they thought would be most likely to know the target.

A chain of letters began, with each sender trying to reach the target through a friend, colleague or family member. From the 60 chains that eventually reached the target, Milgram deduced that the average number of steps in each chain was about six people.

Over three decades later, Dr Duncan J Watts, assistant professor of sociology at Columbia University, had an argument with a friend who claimed the six degrees theory was nonsense. "He said he wouldn't be convinced until he saw some actual numbers," says Dr Watts, "so I determined to go out and get some."

Dr Watts got in touch with colleague, postdoctoral research scientist Peter Sheridan Dodds and a graduate student called Roby Muhamad. The three decided to see what could be done with an email analogue to Milgram's original experiment in order to test it globally.

And that's how the Small World Research Project was born.

The Internet makes the team's task easier but only just. "We can add more targets, deal with the data easily and, most importantly, run very large experiments," says Dr Dodds. "What Milgram's experiment lacked was enough participants to make it statistically sound. We hope that with enough time and interest, we'll be able to get enough chains through to enough targets to be able to say something concrete."

Here's how it works. The team has already selected a number of global targets of different ages, races, professions and socio-economic classes. They are now inviting people to volunteer as senders to initiate a message chain. Over 1,500 have signed up so far and many chains are under way. Three have already made it through to the current target, a PhD student in Novosibirsk, Siberia.

Over the next couple of months, thousands of emails will be sent to around 20 targets in the hope that the team will end up with hundreds of completed chains per target.

Are they are aware of the volume of work involved? "Analysing the data will be fairly simple," says Dr Dodds. "The biggest problem is getting people involved and with some press we seem to be getting over that hurdle."

Dr Watts agrees. "One of the nice things about the Internet is that once the site has been set up and the procedures explained there is very little additional effort required to include large numbers of people."

For those wondering why anyone would go through all the trouble, it is important to realise that this isn't simply about proving a thirty-year-old theory. Watts and his team hope to learn how social networks are structured. They will investigate whether parallels can be drawn between human social webs and engineered systems like distributed computer networks. "One important application that we think this project is quite relevant to is developing search strategies for peer-to-peer networks," adds Dr Watts. "In the aftermath of Napster, P2P networks have become more highly distributed, thereby reducing their vulnerability to attack. But the flip side of this trend is that information stored in the networks has become much harder to find. Because searching for a particular data file in a P2P network is a lot like searching for a particular person in a large social network, we think that if we can understand how people actually succeed at the latter activity, we might be able to design better algorithms for the former."

With this data, computer systems can be remodelled to avoid common problems like the congestion experienced by most networks. "We're not thinking about economic benefits from the results," says Dr Dodds, when questioned about the possibilities. "Though people are pretty ingenious when it comes to working out how to make money. We just want to know something about social structure."

By when will they see a clear pattern emerging? Dodds thinks it could be within six months to a year, while Watts says it will depend on how many people participate. "Some people are suspicious of the idea, suspecting some kind of sinister plot. If we can't overcome their reluctance to participate, it could take us much longer to gather reliable data, and it may not be feasible at all. Participation is very important -- we can't stress that enough."

What if you found out you were related to Osama bin Laden, I ask both researchers, finally. Wouldn't that dramatically change the way you saw the world? "If we can show that people can connect to others who seem to be enormous distances away in not just distance but also social status and religious belief then I think we have something," replies Dr Dodds. "Social space is not so much like real space and because of technology we have the phone, mail system, Internet, air travel and we mix people through the world more and more. Geography becomes less of a constraint."

Dr Watts has a different reply. "I am quite sure I can be connected to bin Laden, as can just about everybody else. We are not making any claims for the significance of being connected, even through some quite short chain. What we are examining is our ability to navigate through these networks; an ability which has a different kind of significance."

Wherever he may be, I really can picture Stanley Milgram nodding his approval.