In 1967, the social psychologists Jeffrey Travers and Stanley Milgram sent letters to groups of people in Wichita, Kansas, and Omaha, Nebraska. They also chose a single target individual in Massachusetts. Each letter recipient was instructed to forward their letter to an acquaintance who was most likely to know the target individual. Many of the letters reached the target, and the researchers were able to find out how many steps it took. The medium number of hops was six, hence, the common phrase six degrees of separation.
The small world problem
Ring networks
Typically, most of an individual's acquaintances are others who live in the same area. If every individual was only acquainted with others who lived near them,...
