Cities are a new kind of complex system: Part social reactor, part network
New research by Santa Fe Institute Professor Luis Bettencourt suggests a city is something new in nature -- a sort of social reactor that is part star and part network, he says.
"It's an entirely new kind of complex system that we humans have created," he says. "We have intuitively invented the best way to create vast social networks embedded in space and time, and keep them growing and evolving without having to stop. When that is possible, a social species can sustain ways of being incredibly inventive and productive."
In a paper published this week in Science, Bettencourt derives a series of mathematical formulas that describe how cities' properties vary in relation to their population size, and then posits a novel unified, quantitative framework for understanding how cities function and grow.
His resulting theoretical framework predicts very closely dozens of statistical relationships observed in thousands of real cities around the world for which reliable data are available.
"As more people lead urban lives and the number and size of cities expand everywhere, understanding more quantitatively how cities function is increasingly important," Bettencourt says. "Only with a much better understanding of what cities are will we be able to seize the opportunities that cities create and try to avoid some of the immense problems they present. This framework is a step toward a better grasp of the functioning of cities everywhere."
What has made this new view of cities possible is the growing opportunities in recent years to collect and share data on many aspects of urban life. With so much new data, says Bettencourt, it's easier than ever to study the basic properties of cities in terms of general statistical patterns of such variables as land use, urban infrastructure, and rates of socioeconomic activity.
For more than a decade, Bettencourt and members of SFI's Cities & Urbanization research team have used this data to painstakingly lay the foundation for a quantitative theory of cities. Its bricks and mortar are the statistical "scaling" relationships that seem to predict, based on a city's size, the average numerical characteristics of a city, from the number of patents it produces to the total length of its roads or the number of social interactions its inhabitants enjoy.
Those relationships and the related equations, models, network analyses, and methods provide the basis for Bettencourt's theoretical framework.
So what is a city? Bettencourt thinks the only metaphor that comes close to capturing a city's function is from stellar physics: "A city is first and foremost a social reactor," Bettencourt explains. "It works like a star, attracting people and accelerating social interaction and social outputs in a way that is analogous to how stars compress matter and burn brighter and faster the bigger they are."
This, too, is an analogy though, because the math of cities is very different from that of stars, he says.
Cities are also massive social networks, made not so much of people but more precisely of their contacts and interactions. These social interactions happen, in turn, inside other networks -- social, spatial, and infrastructural -- which together allow people, things, and information to meet across urban space.
Ultimately, cities achieve something very special as they grow. They balance the creation of larger and denser social webs that encourage people to learn, specialize, and depend on each other in new and deeper ways, with an increase in the extent and quality of infrastructure. Remarkably they do this in such a way that the level of effort each person must make to interact within these growing networks does not need to grow.
How these networks fit together, and the tensions and tradeoffs among them, often determines how productive or prosperous a city is, or whether it fissions into smaller 'burbs, or if people want to live in them or don't, Bettencourt says.
His framework has practical implications for planners and policy makers, he says. To keep these social reactors working optimally, planners need to think in terms of urban policies that create positive social interactions at low costs in terms of mobility and energy use, for example. The paper shows how obstacles to socialization, such as crime or segregation, and enablers that promote the ability of people to connect, such as transportation and electricity, all become part of the same equation.
It even names a couple of U.S. cities that appear to suboptimal in terms of their social interactivity. Brownsville, Texas, and Riverside, Calif., for example, might benefit from policies to improve citywide connectivity. Bridgeport, Conn., which includes Connecticut's "Gold Coast," could be a victim of its own socioeconomic success, as high mobility costs suggest more compact urban living or more efficient transportation might be in order.
The framework is a first theoretical step, Bettencourt says, and much more needs to be done. In the coming years, more and better data from cities in developing nations will become available, which will provide new opportunities to test the theory in places where understanding urbanization is most critical.
"Rapid urbanization is the fastest, most intense social phenomenon that ever happened to humankind, perhaps to biology on Earth," says Bettencourt. "I think we can now start to understand in new and better ways why this is happening everywhere and ultimately what it means for our species and for our planet."
Welcome to SUV System Ltd!
SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.
We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.
SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com
Electronic Components distributor:http://www.suvsystem.com
Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html
IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html
LED Distributor:http://www.suvsystem.com/l/LED-1.html
Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html
Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html
Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html
Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html
SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc
we are focus on the following fields,and hope we can help you.
BZY91C33 BZY91C30V BZY91C30R BZY91C30N BZY91C30 BZY91C27V BZY91C27R BZY91C27 BZY91C24V BZY91C24R BZY91C24 BZY91C22V BZY91C22R BZY91C22N BZY91C22 BZY91C20V BZY91C20R BZY91C20 BZY91C18V BZY91C18R BZY91C18 BZY91C16V BZY91C16R BZY91C16 BZY91C15V BZY91C15R BZY91C15 BZY91C14V BZY91C14R BZY91C14 BZY91C13V BZY91C13R BZY91C13 BZY91C12V BZY91C12R BZY91C12 BZY91C11V BZY91C11R BZY91C11 BZY91C10V
http://www.suvsystem.com/a/3092.aspx
