six segrees of separation

An explosion of interest in Stanley Milgram's "Small World Problem" is occurring outside the field of psychology. The stimulus is a 1998 paper in Nature which offers an intriguing mathematical explanation of how the "small world" phenomenon can be explained based on the presence of random connectors in a network (Watts & Strogatz, 1998). This fascinating mathematical demonstration, based on graph theory, is supported in the Nature article by only one empirical example from the social world: Calling two actors "connected" if they had ever been in a film together, Watts and Strogatz found that 225,000 film actors listed in the Internet Movie Database as of April, 1997 were separated from each other by only four steps. The example is intriguing and may well be a good analogy for certain other occupational networks, such as scientists or corporate businesspeople. Film actors, who shift social worlds with each film they make, however, are not a good analogy for the classic formulation of the small world problem: To what extent are people anywhere in the world connected? This problem includes illiterate farmers in rural India as well as corporate executives or teenage technophiles.