The Physics of Friendship

Another interesting (and successful) paper on modeling of social networks by physicists: A System of Mobile Agents to Model Social Networks (pdf), by Gonzalez, Lind, and Hermann. I recommend the more accessible writeup here.

The gist is that they can model friendship patterns in schools with a system of particle collisions and diffusions, and accurately reproduce the empirical data from a large survey of 84 schools' friendship relations. With a minor variation, the model extends to sexual relations in an HIV study (not at schools).

How depressing to learn we're just particles bumping into each other!