Aus einem aktuellen Beitrag der New York Times:
Facebook, Pfadlängen, 6 degrees of separation.
"[The] researchers used a set of algorithms developed at the University of Milan to calculate the average distance between any two people by computing a vast number of sample paths among Facebook users. They found that the average number of links from one arbitrarily selected person to another was 4.74. In the United States, where more than half of people over 13 are on Facebook, it was just 4.37."