Sometimes erroneously described as global village phenomenon the notion of a small world goes back to an experiment by Stanley Milgram (who became famous with the “obedience to authority” experiment – I did not know until last weeks that the punishing experiments had been repeated here in Munich where 85 percent of the subjects continued until to the end!).
The small world theory says that everyone in the world can be reached through a short chain of social acquaintances. The concept gave rise to the famous phrase of phrase six degrees of separation – I believe that a scientist may even reach another scientist in 4-5 steps.
My first PubNet example here is to reach F. Sanger by joint co-authors. This doesn’t work – my estimate would be 3 intermediary steps.
My second PubNet example is to reach N. Morton (the foreword of his anniversary book says that a qualification of a genetic epidemiologist can be counted as “Newton”-points – the number of joint publications with Professor Morton).
Arxive.org has the largest study so far: 6,6 steps in 30 billion messenger conversations among 240 million people.