The Small World of Kevin Bacon
https://oracleofbacon.org/index.php
One Networks lecture featured a discussion of the “small world phenomenon,” a consequence of the global friendship network. The idea—backed up by work from Milgram and Watts—is that most people in the world are connected by relatively few connections. The number of people in a given individual’s sphere increases exponentially with each additional connection.
Think about it: say I know 700 people. If each of those people also knows 700 people who aren’t part of my sphere, then the maximum number of people in this two-connection network is (700)(700-1)= 489,300. Now, this number is likely to be inaccurate because I probably have a bunch of mutual friends with each of my connections—our immediate connection networks are extremely unlikely to be disjointed. As such, the number of new people that each of my connections brings to the table will be lower. Still, the principle holds that with each connection, there is a substantial marginal increase in the number of people in the network.
The ‘Oracle of Bacon’ website works on this principle. It uses the IMDB (Internet Movie Database) to make a massive graph of all the actors and movies in the film industry. Actors can be considered nodes, and movies can be considered edges. The website allows users to input any given actor, and see how many edges separate that actor from Kevin Bacon. If a given actor has been in a movie with Kevin Bacon, then his number is 1. If that same given actor has been in a movie with someone else, and that extra person has starred in a film with Kevin Bacon, then the first actor’s number is 2. And so on. It seems intuitive that some actors might have pretty high Bacon Numbers, but this is rarely the case. Numbers are astonishingly low.
I tried testing the site by inputting esoteric or lesser-known actors. It didn’t matter. Most had Bacon numbers of 2 or 3. In fact, I never got a number higher than 3. I like this example because it illustrates the “small world phenomenon” in an interactive, entertaining way. So try it out!
https://oracleofbacon.org/index.php