Justin Sullivan/Getty Images

It has been proposed that everyone on the planet is only six degrees of separation away from anyone else on the planet — in other words, you are six or fewer "friend of a friends" away from "the president of the United States [or] a gondolier in Venice." Only now, with the invention of the internet, that number has shrunk enormously; Facebook's research has found that "each person in the world (at least among the 1.59 billion people active on Facebook) is connected to every other person by an average of three and a half other people."

The "degrees of separation" between people are rapidly shrinking, too. In 2011, researchers at Cornell, the Università degli Studi di Milano, and Facebook calculated the average degrees of separation was more like 3.74. Facebook users have doubled since the last calculation, however, so naturally as more people use the site, we grow more interconnected.

Read more about degrees of separation and the math involved in calculating that number over at Facebook.