Hi Lin!

The small-world phenomenon formalizes the anecdotal notion that "you are only ever six 'degrees of separation' away from anybody else on the planet." Almost everyone is familiar with the sensation of running into a complete stranger at a party or in some public arena and, after a short conversation, discovering that they know somebody unexpected in common. "Well, it's a small-world!" they exclaim. The small-world phenomenon is a generalized version of this experience, the claim being that even when two people do not have a friend in common, only a short chain of intermediaries separates them.

The Kevin Bacon Game: Kevin Bacon is an actor best known for not being the star of many films. But a few years ago, Brett Tjaden—a computer scientist at the University of Virginia—catapulted Bacon to true international recognition with the claim that he was somehow at the center of the movie universe. This is how the game goes:

Think of an actor or actress.
If they have ever been in a film with Kevin Bacon, then they have a "Bacon Number" of one.
If they have never been in a film with Kevin Bacon but have been in a film with somebody else who has, then they have a Bacon Number of two, and so on.

The claim is that no one who has been in an American film, ever has a Bacon Number of greater than four. Elvis Presley, for example, has a Bacon Number of two. For real enthusiasts, Tjaden created a web site that provides the Bacon Number and shortest path to the great man for the most obscure of choices. In fact, Tjaden later fireproofed his claim by conducting an exhaustive survey of the Internet Movie Database, and determined that the highest finite Bacon Number (for any nationality) is eight. This may seem nothing more than a quirky fact about an already bizarre industry, but in fact it is a particularly clear example of a phenomenon that increasingly pervades our day-to-day existence: something known as the "small-world phenomenon."

Spaw