Six Degrees (broadcast Friday, January 25th, 2008)

Chances are you've heard of the 'small world' idea of six degrees of separation. But is it correct?

The idea traces back to an experiment begun in 1967 by Stanley Milgram, in which he tried to trace how many acquaintances it would take to pass a letter between two randomly selected people. The result that entered the public consciousness was that in general it took six steps or fewer to bridge the gap between any two people. But is that result accurate? One researcher, Judith Kleinfeld, a professor of psychology at the University of Alaska Fairbanks, looked at 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."

Other researches take issue with her assertions, however. In this segment, guest host Joe Palca talks with Kleinfeld and 'small worlds' researcher Steven Strogatz, a professor of applied mathematics at Cornell University, about the 'six degrees' idea. Do we really live in a 'small world' -- and, if so, what can we do with that information?