Two Degrees of Separation
Last week, I wrote about the Oak Creek shooting, and posited that perhaps it was not random violence. Since my weekly email contains a teaser for my blog post, she got that teaser, as well as the link.
A day later, I got an email from the Milwaukee woman, saying that the Oak Creek temple was her temple! She said she knew 3 of those who’d died, and several women who’d been hiding in the kitchen with the kids. That makes me only 2 degrees of separation from the people who died — and you only 3 degrees of separation. It’s a really small world. How is this possible?
It’s possible because of small world networks.
Consider the game, Six Degrees of Kevin Bacon, where players try to tie a given actor to Kevin Bacon in as few steps as possible, based on the movies they’ve acted in together. So if an actor has worked in a movie with Mr. Bacon, he has a Bacon number of 1, if an actor has worked with an actor who has worked with Mr. Bacon, she has a Bacon number of 2, and so on. As you can see in the table below, using data from the internet movie data base, www.imdb.com, which has over 500,000 actors, the vast majority of actors are within 3 degrees of separation from Bacon, and virtually all are within 4 degrees:
Degrees of Separation Cumulative Bacon Percentage
The book, “Six Degrees”, by Duncan Watts, from which the above data is abstracted, is all about “small world” networks, looking at networks as different as movie actors and the power grid from a mulitdisciplinary approach. After considering several models and research from the 1930’s onward, he concludes that “As long as individuals are more likely to know other people like them, and — crucially — as long as they measure similarity along more than one social dimension, then not only will short paths exist between almost anyone almost anywhere, but also individuals… will be able to find them.” And other research suggests that the two most powerful dimensions to explore are geographical connections and professional ones.