IStock Photo 11406189 © Rubén Hidalgo

Thanks to an informal game among movie lovers, actor Kevin Bacon’s name became one of the first Internet buzzwords. “Six Degrees of Kevin Bacon” is a game based upon a 1990 play, “Six Degrees of Separation,” which later became a movie. The premise of the play is that only six degrees of separation divides any of us from anyone else—and the game limits the premise to actors who can be connected in six steps or less to fellow actor Kevin Bacon. “Six Degrees of Kevin Bacon” has escalated from verbal sparring to a board game, a book, and a number of websites, the most prominent of which is the 10-year-old Oracle of Bacon.

Aficionados of the game quickly determined that few actors require all six degrees to make the connection; the average Bacon number, as determined by the Oracle of Bacon and the Internet Movie Database, is 2.97, meaning less than three steps are required to complete the link. Anyone who has ever played the game soon discovers the importance of large ensemble dramas like Apollo 13 or Sleepers.

The odds that an actor or actress is three or fewer degrees of separation from Kevin Bacon are 1 in 1.23 (81%). In fact, when it comes to Kevin, “Six degrees” is very misleading. With Kevin Bacon, it’s more fun to reverse the premise. The odds an actor or actress is separated by at least six degrees from Kevin Bacon are long—1 in 1,067. No one ever said Hollywood wasn’t a small town.

It turns out that the Bacon game was itself preceded by an inside joke among mathematicians. The Hungarian academician Paul Erdös, a particularly prolific mathematician, along with one of his colleagues, proposed a function to define the proximity of all other mathematicians to Erdös through article co-authorship. The Erdös numbers tend to be higher than the subsequent Bacon numbers; there are usually far fewer co-authors on a math paper than there are actors in A Few Good Men—or, for that matter, Six Degrees of Separation. For this reason, there are 511 mathematicians with an Erdös number of 1—direct coauthors—but 2,313 actors with a Bacon number of 1—those who have actually been in a film with Kevin Bacon.

At the moment, Bacon does not hold the title to the highest degree of connectedness to other actors. As of April 2009, that distinction passed to Dennis Hopper, although it’s an ephemeral honor as the numbers shift over time. While the average actor or actress is 2.97 degrees from Bacon, he or she is only 2.76 degrees from Hopper.

Naturally, the six degrees of separation concept is now being applied to social networking. A recent startup, Glacir.com, is hoping to attract enough users to be able to map a truly global social web, showing exactly how many degrees separate everyone from everyone else. In 2007, Kevin Bacon himself started SixDegrees.org, to try to connect donors and charities to one another through the Web. He then fell victim to some of that same interconnectedness, when he became one of the many philanthropist victims of billion-dollar swindler Bernard Madoff. Sadly, there are a whole lot of charities that now have a Bacon number of 1.

The moral might be: no matter how you slice it, you’re closer to Bacon than you realize.