Long-term research: Slow science
nature.com
nature.com
Milgram's 1967 small world experiment that introduced the "6 degrees of separation" term consisted of 300 people trying to send physical letters to 1 target, this stock broker in Boston. 80% of the letters never reached the target, and of the ones that reached, the average number of hops was 6.
Fast forward to 2008. A summer intern at Microsoft Research attempts to re-do this experiment. He constructs a graph with 180 million nodes and 1.3 billion undirected edges using MSN Messenger data, and finds the average path length between users to be 6.6. http://research.microsoft.com/en-us/um/people/horvitz/leskov...