Our collaborators developed a powerful theoretical approach to describing and predicting crowd behavior that is easiest to understand when you picture a human crowd. For example, imagine you go to a stadium to see your favorite band. The show is about to start, so you look for the best spot to watch. You walk up to the stage and politely pass by the people at the edge of the crowd. Those people have forgone the best view in order to have a little more personal space. As you near the front though, it gets more and more crowded.