" Indeed, on Facebook, 99.91 percent of the two billion people on it belong to the “giant component,” meaning that almost everyone is everyone else’s friend of a friend of a friend.67 There are only about 4.7 “degrees of separation” (the number of “nodes” you have to cross) between any two people in the giant component. This implies that in principle we could easily be exposed to pretty much everyone’s views as they travel through the social network. "

― Abhijit V. Banerjee , Good Economics for Hard Times: Better Answers to Our Biggest Problems