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The Physics of Friendship
(Lisa Zyga, Physorg.com)

By modeling people’s interactions based on how particles bounce off each other in an enclosed area, physicists Marta Gonzalez, Pedro Lind and Hans Herrmann found that the characteristics of social networks emerge “in a very natural way.” In a study recently published in Physical Review Letters, the scientists compared their model to empirical data taken from a survey of more than 90,000 U.S. students regarding friendships, and found similarities indicating that this model may serve as a novel approach for understanding social networks.

“The idea behind our model, though simple, is different from the usual paradigmatic approaches,” Gonzalez told PhysOrg.com. “We consider a system of mobile agents (students), which at the beginning have no acquaintances; by moving in a continuous space they collide with each other, forming their friendships.”

After a collision, a particle moves in a different direction with an updated velocity, just as how an individual’s chance of meeting a new person depends on their most recent acquaintances.

At a critical point, the system reaches a quasi-stationary state, for the first time allowing the scientists to reproduce several features of social networks in a single model and in a natural way. Specifically, this technique accurately describes social clustering, the way friendships evolve over time, the shortest path length in a large group, and some features related to group structure.

(via SlashDot)