6 Degrees of Separation
Watched this last night with the wife.
The beautiful math behind six degrees of separation
Really interesting stuff on networks, which is right down my alley.
More information here
Six degrees of separation is the idea that all people are six or fewer social connections away from each other. As a result, a chain of "friend of a friend" statements can be made to connect any two people in a maximum of six steps. It is also known as the six handshakes rule.[1] Mathematically it means that a person shaking hands with 30 people, and then those 30 shaking hands with 30 other people, would after repeating this six times allow every person in a population as large as the United States to have shaken hands (seven times for the whole world).
Six degrees of separation - Wikipedia
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Well documented, and lots of material freely available if you're interested.
#enoughsaid