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A Physicist Applies Research To Cities

According to theoretical physicist Dr. Geoffrey West, cities of similar size are alike in many ways. He says that population numbers can predict details about a city, from crime rate to economic activity.

Cities are where humans live today, and this is a very new development. As recently as a hundred years ago, in the U.S., the great majority of people lived in rural areas. The rapid growth of cities has been a worldwide reality. And it has caused one scientist, named Geoffrey West, to study them with tremendous intensity. West is a theoretical physicist. He has found that cities, from one country to the next, behave and develop in ways that are remarkably similar. They all hew to many of the same rules, regardless of urban planning. In fact, he's compared cities to living organisms.


Dr. Geoffrey West is a theoretical physicist who studies the behavior and development of cities. He'll speak tonight at the San Diego Museum of Art.

Dr. Geoffrey West will give a lecture at the San Diego Museum of Art tonight at 7:50pm. He'll be there as part of the museum's Summer Salon Series. The theme for the series is "What does a city need?". Artists participating in the Summer Salon series will show their work beginning at 5pm tonight.

Here is Dr. Geoffrey West's TED Talk, from July, 2011.

Dr. Geoffrey West's TED Talk

West's TED Talk recorded in July of this year.

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This is a rush transcript created by a contractor for KPBS to improve accessibility for the deaf and hard-of-hearing. Please refer to the media file as the formal record of this interview. Opinions expressed by guests during interviews reflect the guest’s individual views and do not necessarily represent those of KPBS staff, members or its sponsors.

FUDGE: You're listening to Midday Edition am I'm Tom Fudge. Cities are where humans live today. And this is a very new development. The rapid growth of cities has been a worldwide reality, and it has caused one scientist, named Jeffrey west to study them with tremendous intensity. West is a theoretical physicist. He's found out that cities from one country to the next behave in ones that are remarkably similar. They all heed to the same rules regardless of human planning. In fact, he's compared them to living organisms. Jeffrey west will be in town tonight to speak at the San Diego museum of art. Thank you very much for being our guest on midday.

WEST: Pleasure being here.

FUDGE: The city, now, where did this thing come from and what has happened to the city in the past couple of hundred years?

WEST: Ah, well, cities have been around for maybe as long as 8,000†years, maybe even a little bit longer. And they were formed really as hunter-gatherers turned into agricultural people and so on. And I think in simple terms, really, it was the discovery that working together we can accomplish more from the same amount of energy, from the same amount of resources available, we can do more. And cities really evolved from that very fundamental idea, but also expanding it into innovative, creative ideas that allowed a kind of hierarchical structure to evolve and concepts like reward systems, wages, and so on as an efficient way both for the individual to get more and for the group as a whole to gain more.

FUDGE: Right. And I mentioned the past 200†years because we have seen a tremendous amount of urbanization over that period of time, right?

WEST: Exactly. So cities grew slowly, and in some cases to very large numbers in the last several thousand years. But it was really the coming of the industrial revolution and the discovery of thin sources of energy via coal and oil, and so forth, that allowed this extraordinary expansion in the last 200†years where the cities themselves but also urbanization as a whole has been proceeding at an exponential rate. 200†years ago in the United States, only a few% of us were urbanized. Everybody lived effectively in an agricultural situation. Whereas today you have almost the opposite where well over 80% of us are now urbanized, and only a small minority are really involved in truly rural agricultural kind of situations.

FUDGE: Now, Jeffrey west, you're a theoretical physicist. And the physical world does seem to follow certain rules. But the creation and function and growth of cities doesn't seem like something that can be reduced to a set of rules. And yet, I think that's what you have tried to do.

WEST: Yeah, so indeed, we do all have this impression of whatever city we live in that it seems quite unique. You're in San Diego and it looks quite different than where I am at the moment, namely in Santa Fe New Mexico. I'm high in the high desert, very dry; you're by the ocean. We're a city of maybe 100, 100 and 50,000. Your many million, and so on. So you have this feeling of uniqueness. And yet one of the things that myself and my collaborators have learnt by looking at data is that in fact there are extraordinary regulators and commonalities that transcend the individuality of cities not just across the United States, but in fact across the globe.

FUDGE: And I have a feeling you're going to give us one or two examples of those things.

WEST: I am indeed.

FUDGE: All right.

WEST: So for example, something at the level which is -- sounds almost trivial, but if you ask the question like how many gas stations are there in a city of a given size, you look at the data of the number of gas stations in a city and plot it versus the size of the city as denoted, say, by its population. Whereas my evil you might expect the points representing those data to be scattered all over the place, in fact they follow a very regular pattern so that in principle you tell me the size of a city, I can tell you with kind of a 90% accuracy how many gas stations it will have. And that law, so to speak, that law which tells you how the number of gas stations changes with the size of a city seems to be followed across the globe. What is even more astonishing is that this same law applies to any infrastructural quantity. If you and what is the total length of roads in a city, how long are all the electrical lines, etc., etc., or even what are the averages wages of a person in a city, or how many AIDS cases or how many police, or how big is the taxes of the city collect, etc., etc., all of these kinds of question, anything you can think of that can be measured you find that there is this remarkable systematic behavior as a function of the size of the city.

FUDGE: And my guest is Jeffrey west, he's a theoretically physicist who studies the behavior and development of cities. He's going to be speaking tonight at the San Diego museum of art. Anything you can mention seems to increase, as cities get bigger. What about creativity? What about energy? What about innovation?

WEST: Yeah, so of course they're very hard to measure. What is the proxy for the creativity of a city, the innovation of a city? One of the metrics that is commonly used and we use it is for example the number of patents that are produced in a city. And we discovered that indeed that scales with the size of a city in a very systematic way, so given the size of a city, we can estimate how many patents the city is producing. And roughly speaking, the generic law that is at work can be stated as follows: If you double the size of the city from 100,000 to 200,000 or from a million to two million or from 10 million to 20 million, doesn't matter where you start, but if you just double it, systematically you increase by approximately 15% the average wages, the number of AIDS cases, the number of patents produced, the number of fancy restaurants, the number of super creative people all go along in the same way. They all increase by roughly this 15%.

FUDGE: I'm sorry, go ahead.

WEST: No, and at the same time, when you double the size of a city only need to increase by about 85%, rather than 100%, the total infrastructure, the number of the length of roads, the length of electrical cables, the number of gas stations, and so on. So there's this extraordinary savings on the one hand systematically, and at the same time, these extraordinary gains in many of the good things, but also many of the bad things that we don't like about cities and the social life.

FUDGE: So cities have economies of scale, it sounds like.

WEST: They have economies of scale. Bigger cities are more efficient on the average by this 15% factor. But -- and they're also more creative, innovative, wealth producing. But they are also to the same degree places with greater numbers of AIDS cases and pollution and so forth.

FUDGE: This belief that you have that cities tend to act in the same way, I'm sure there are a lot of people out there who would disagree with that or at least be suspicious of that theory because they look at cities and they say, for one thing, different cities have different population densities. Not every city is Manhattan. Some cities are like San Diego or Phoenix. Now, does that make a difference or is it all about the number of people you get in roughly the same area?

WEST: Well, yeah. Two things. First of all, all those statements I made to you are simply data. We just analyzed enormous amounts of data. These are actually facts about cities. And the same phenomenon that we see when we look at the United States is reflected quantitatively in Japan, Columbia, Chile, Portugal, France, you name it. You see the same phenomenon everywhere in cities that have no relationship whatsoever with one another in terms of their geography, history, and culture. So there are these kind of systematic behaviors. Now, the question of density is a very tricky and interesting one. And partly that's because of the question of what is the area of the city. When you think about density, what do you mean by that? You mean the number of people occupying a certain unit area?

FUDGE: That's what I think of.

WEST: Yes. And that creates all kinds of questions about what is the area of the city, because to include the park pace, do you include the fact that -- what do you average over? Do you average over the whole city or as you mentioned earlier, Manhattan clearly has a different density than the suburbs of New York. So there's a whole bunch of very important, and some of them more technical, but critical questions for the dynamics and growth of the city that are involved in the questions density and the questions implicit in that, the question of what is the area of the city. And we and others have struggled with that. But independent of that, the thing that we have discovered is that it is the absolute number of people that seems to play the driving role for the average behavior that we see of a city that -- when we average over its entire size. By a city, incidentally, we don't just mean the political city.

FUDGE: Sure.

WEST: What we mean, of course, is the metropolitan area that is connoted by the connectivity of people that live within that area so that they're all in some way, one could argue, interrelated and connected and form a kind of coherent system.

FUDGE: Doctor Jeffrey west is a theoretical physicist who studies the behavior and development of cities. One thing that I know you talk about in your city studies is the increasing level of consumption of goods in cities, which you say is unsustainable. And why do cities make us want to have more stuff?

WEST: Yes, well, this is an extremely oxygen ing and important question. One of the extraordinary differences between cities an organism, say -- so one of the questions I asked myself during this work is San Diego just a great big whale? Is it a biological organism? Because we use very often biological metaphors. We talk about metabolism of a city or the DNA of a company or the ecology of the marketplace, and so on. So we use these phrases. And the question is, are these kind of characterizations just metaphors, or is there something serious in it? And one of the critical differences between organisms and cities is that almost all organisms, when they are created, they growth quickly, and then they stop growing. They reach a mature size, and then they spend most of their life at that mature size or close to it. Cities by and large seem to be continuously growing. They are -- they seem to know continuously expanding, there is almost -- there is very, very small mortality amongst cities. Very few cities die. We know, of course, classic examples, and we know of the phenomenon of ghost towns and so on. But of the hundreds of thousands, millions of cities that have grown on the surface of the planet, almost all of them are still with us.

FUDGE: They just keep getting bigger.

WEST: And they simply get bigger. And that's a, in marked contrast to organisms. We all die. And in particular, it's a marked craft to companies, which all day. One of the great things about cities, one of the things that makes them most attractive is that they have -- we talked about economies of scale earlier, but the scaling of socioeconomic quantities like wages and cultural phenomena and patents and so on, all of these are what we term super lineal which means the bigger the city, the more you get per capita, the bigger you are. So they're very attractive in that way, so to vehicle speak, for the same buck. And that's what makes them so attractive to the individual, and also very, very efficient ways of dealing with large numbers of people in communities. And one of the reasons for that is that underlying all this are the social networks by which we also interact, the cluttering of human beings in communities, whether it be families or jobs and so on. And the social network that connects us all is really the underlying mechanisms that lead to this kind of universality of scaling, because social networks have a kind of universality to them. Human beings and their interactions are pretty much the same everywhere across the United States, but they're also pretty much the same across the globe.

FUDGE: Okay, well, I'm afraid we are out of time. I'm just going to have to remind people that Jeffrey west will give a lecture at the San Diego museum of art tonight at 7:50 PM. That's ten minutes of eight. Don't be late. And Jeffrey west is a theoretical physicist who studies the behavior and development of cities. And if you want to hear more, San Diego museum of art tonight. And doctor west, thank you very much.

WEST: Oh, it was a pleasure talking to you, appreciate it very much.

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