Six degrees of separation is a hypothesis that every human being knows every other human being through six people. In other words for any two people A and B, either A knows B (1 degree of separation), or A knows someone who knows B (two degrees of separation) and so on.
There have been experiments to verify if this is true in practice. In one experiment, called the Small world experiment and conducted by Columbia University – each volunteer was given the name of a person with some details (like the place he lived in) and was asked to contact the person either directly (if he knew him) or to forward the request to someone who he thought was “closer” the person. I also participated in the experiment, and was asked to contact someone in Russia – I sent it to the only person who I knew in Russia! Someone should also have contacted me, but no one did – I guess I broke the chain 🙂
The experiment found that “social searches can reach their targets in a median of five to seven steps”.
Today, this can be easily verified through data contained in social networking sites like Facebook and Orkut. Indeed, there is a Facebook application that estimates average separation to be 5.73 and maximum 12. Interesting, isnt it?