The well known "six degrees of separation" idea traces back to a 1967 experiment by Stanley Milgram, who tried to determine how many acquaintances it would take to pass a letter between two randomly selected people.
The result that entered the public imagination was that, in general, it took six steps or fewer to bridge the gap between any two people. But is that result accurate?
Judith Kleinfeld, a professor of psychology at the University of Alaska, researched Milgram's original experiment in the hopes of updating it for the digital world.
"Milgram's startling conclusion turns out to rest on scanty evidence," she says. "The idea of 'six degrees of separation' may, in fact, be plain wrong — the academic equivalent of an urban myth."
Steven Strogatz, a professor of applied mathematics at Cornell University, disputes this claim. He says it's important to remember that Milgram was not being deceptive in his original study, and describes the small world property as a sort of "universal architecture" of connection — both in the outside world and in the biology of the human body.
"We see this sort of architecture — this gorgeous use of the small world property — in the national power grid, in the Internet, in the human brain and in the genome," Strogatz says. "It's a ubiquitous architecture that allows for rapid spreading of information, global coordination of all sorts of activities, and sometimes unwanted effects like computer viruses."
Judith Kleinfeld, director of northern studies and professor of psychology at the University of Alaska, Fairbanks
Steven Strogatz, professor of applied mathematics at Cornell University