Can anyone in the world reach anyone else through a chain of just six friends?
In 1967, sociologist Stanley Milgram created what is known as the "small world phenomenon," the idea that every person in the United States is connected by a chain of six people at most.
Milgram's "six degrees of separation" theory has trickled down through popular culture, inspiring renditions such as the Kevin Bacon game.
But Milgram's theory has gone largely unproven for more than 30 years and hasn't yet been repeated with any success. Now, two separate research projects are using electronic communication to test the small world phenomenon.
Sociologists at Columbia University are testing Milgram's theory on a global scale by tracing e-mails one chain at a time.
Columbia's Small World Research Project is enlisting people from all around the world to send thousands of e-mail messages to reach target individuals using only personal contacts.
While Milgram selected roughly 300 people to reach a single target person, Columbia researchers are aiming for tens of thousands, if not hundreds of thousands, of participants to reach as many as 20 targets.
"This is great stuff for sociology," Peter Sheridan Dodds, a Columbia research scientist, said. "We can now run experiments that will have very strong statistical worth on par with what is the norm in disciplines like physics."
Columbia researchers are collecting 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.
In a separate project, researchers at Ohio State are attempting to create a social map of the Internet. If successful, this map will reveal how different types of people are connected, how information moves through society and just how small social networks really are.
Backed by a grant from the National Science Foundation, The Electronic Small World Project seeks to identify the strongest strings emanating from a large sample of people, and then show how those strings connect together to form the full Web.
"This is the first attempt to map, in a person-to-person sense, the social patterns of e-mail," said Ohio State University sociologist James Moody, who is leading the project.
"(Milgram's theory) was an innovative idea, but it was only a first step," Moody said. "We hope to fill in the holes."
Participants complete an online survey about their demographics, e-mail use and the nature of their e-mail relationships. So far, more than 800 people have completed the survey. The ambitious goal is to gather a half-million responses.
Researchers will contact participants a year after they have completed the survey to find out how their e-mail relationships have changed over time and whether they differ from offline relationships.
"We know that face-to-face relationships tend to be pretty unstable," Moody said. "With e-mail, (relationships) could be much more stable."
The project will also test assumptions about online communication, such as the idea that the Internet transcends barriers of race, sex and economics.
While racial and economic divisions may persist in online relationships, it's likely that e-mail is making the world a smaller place for some people, Moody said.
The notion that millions of people are just a few small steps away from each other seems intuitive in today's digital world, when a computer virus like the Love Bug can shut down half the world's corporations in a single day by infiltrating e-mail address books.
But even if these short connections exist, that doesn't necessarily mean that the people in the network can find them. While the Web has increased the speed with which people can look each other up, actually locating a person through a social network may be just as difficult today as it was 30 years ago.
"It's not necessarily any easier than it was in Milgram's day," said Duncan Watts, an assistant professor of sociology at Columbia University, who is leading the project. "You're still just using your friends. It doesn't change the nature of the problem.
"This is not just a question of there being short paths. The question is, how do people act to figure out who to send it to. It's not just the network that they exist in but how they think about it."
Already, Columbia researchers have found that some short paths exist, such as one successful attempt to reach a target in Siberia from participants as distant as the United States and Australia.
Both research projects could yield substantial benefits, such as helping understand how viruses spread and how knowledge is disseminated through internal networks.
"We all know not to open attachments from people we don't know," Moody said. "By mapping what that network (of people we trust) looks like, we'll get a better sense of the shape of that network."
"If people can find these paths, and depending on how they do it, then that will tell us not only about the networks, but also about how we use ideas of social space to navigate through them with imperfect information," Watts said.
Watts hopes that his research will create models for decentralized networks that will improve upon peer-to-peer networks like Gnutella and to provide alternatives to search engines like Google, which serve centralized directories.
"As the Web gets bigger, we may not always have these services," Watts said. "We need to find other ways to search these big networks."
