Follow the Money

In a beautiful video, researchers explained how they were able to track dollar bills and used that information to calculate borders of social networks. Some of the borders seem to follow state lines, others follow geographic landscapes (e.g. the Mississippi). What was especially nice about this video are the animations which make it easy to understand what calculations are being done.

The equation for a city

I found this article in the New York Times very fascinating about two physicists who decided that they wanted to create an urban science which rethinks the way that we look at urban planning. They found that there are simple relations between certain parameters of a city. With a few equations they can make predictions about all cities that are remarkably accurate. I'll let the article speak for itself, but the following quote seems to summarize the

“I can take these laws and make precise predictions about the number of violent crimes and the surface area of roads in a city in Japan with 200,000 people. I don’t know anything about this city or even where it is or its history, but I can tell you all about it. And the reason I can do that is because every city is really the same.” After a pause, as if reflecting on his hyperbole, West adds: “Look, we all know that every city is unique. That’s all we talk about when we talk about cities, those things that make New York different from L.A., or Tokyo different from Albuquerque. But focusing on those differences misses the point. Sure, there are differences, but different from what? We’ve found the what.”