Every city is different - New York and Los Angeles are night and day in terms of layout, population dynamics and economy - but are they similar enough that they can be described mathematically? Is there a set of physical equations to which all cities - from small towns to sprawling megalopolises - conform?
That's what physicist Geoffrey West wanted to find out:
“We spend all this time thinking about cities in terms of their local details, their restaurants and museums and weather,” West says. “I had this hunch that there was something more, that every city was also shaped by a set of hidden laws.”
After analyzing a lot of urban data, West and his colleague Luis Bettencourt discovered that cities are actually mathematical objects:
After two years of analysis, West and Bettencourt discovered that all of these urban variables could be described by a few exquisitely simple equations. For example, if they know the population of a metropolitan area in a given country, they can estimate, with approximately 85 percent accuracy, its average income and the dimensions of its sewer system. These are the laws, they say, that automatically emerge whenever people “agglomerate,” cramming themselves into apartment buildings and subway cars. It doesn’t matter if the place is Manhattan or Manhattan, Kan.: the urban patterns remain the same. West isn’t shy about describing the magnitude of this accomplishment. “What we found are the constants that describe every city,” he says. “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.”