COMPLEXITY: Physics of Life

Luis Bettencourt on The Science of Cities

Episode Notes

If you’re a human in this century, the odds are overwhelming that you are a city-dweller. These hubs of human cultural activity exert a powerful allure – and most people understand that this appeal is due to some deep link between the density, pace, wealth, and opportunity of cities. But what is a city, really? And why have the vast majority of human beings migrated to these intense and often difficult locations? Cities breed not just ideas but also crime, disease, and inequality. We live amidst a shift in what a normal human life looks and feels like, akin to the transition from our lives as nomadic hunter-gatherers to sedentary farmers — only this time, it is happening before our eyes. How can we cultivate the best that cities offer and minimize the predicaments they pose? A powerful new science of the city has emerged in just the last few years, connecting the metropolis through physics to the properties that govern animal metabolisms, ecological diversity, and economics.

This week’s guest is Luis Bettencourt, External Professor at the Santa Fe Institute and Director of the Mansueto Institute for Urban Innovation at the University of Chicago. We spoke while he was visiting Santa Fe to lead SFI’s Global Sustainability Summer School to talk about what makes a city such a fertile zone for innovation of all kinds, and how to help ensure the future of the city is one human beings want to live in.

Visit our website for more information or to support our science and communication efforts.

Join our Facebook discussion group to meet like minds and talk about each episode.

Visit The Mansueto Institute's Website.

Watch a short video on Bettencourt’s work to eliminate slums.

Here are the three papers we discussed in this episode:

"Toward cities without slums: Topology and the spatial evolution of neighborhoods" in Science Advances.

"The Origins of Scaling in Cities" in Science.

Towards a statistical mechanics of cities” in Science Advances.

Learn more about SFI's Global Sustainability Summer School.

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Episode Transcription

Michael: Luis, it's a pleasure to have you on the show, to get to sit down with you and talk with you about an area of inquiry that I think interests pretty much everyone alive on the planet today, which is the city. And I'm inclined to just go to the deepest question here, but before we do that, I'm curious how you came to getting into the science of cities? What motivated you to study this area in the first place?

Luis: Sure, it's my pleasure. It took me a long time and took me a long time to acquire enough confidence and see the possibility of studying that. At a personal level, I think you brings together something I've always been fascinated by as a person.

I grew up in the city of Lisbon in Portugal, which in my lifetime is a city that changed a lot, is a city that received many people from all over the world, that went through a period of rapid growth and strong inequality and a large amount of poverty, to a city that then changed very quickly and again reinvented itself, became a city that much more cultural, with less inequality, with a different identity, and right at the moment it's the city that's quite hip and unique.

But it's kind of a mixture of very old, very dirty, very weird and then very new and kind of strange in its own right — and so those are some of the best qualities about cities. I think my interest also was born out of, growing up, my parents were socially and politically involved, they were both very interested in social justice. And I saw particularly my mom, she works very hard with a lot of non-profits and many different causes, and seeing how difficult it is to create change, how important it is to go to work at it every day. But how then sometimes change happens quickly and sometimes it seems like it will never happen.

And understanding a little bit more about how that might happen, I thought it was maybe what I could do, I was of course a nerdy kid that liked to think about things and I thought, "We need to understand that better, why is it that sometimes things change so quickly, particularly in urban environments? And why is it that most of the time nothing happens?"

Cities are these environments, I like to call them places where a lot is going on, but sometimes he feels like nothing happens, it seems like every day is the same and we're all kind of just running around and hustling around. And other times just feels, oh my gosh, it's a different reality, and in a few years, new technologies, people are wealthier, there're magic solutions to issues that affected humanity forever, like poverty or some issues, public health or social justice.

I wanted to in many ways get to that. But I grew up in a place where I could not imagine coming into the social sciences, which should be the natural path and starting to study and make sense of these issues, so instead I went into physics because I thought, "Damn it, if I don't understand this now as a student." So I did, all the way to PhD. I went to do quantum physics, quantum field theory, beginning of the universe cosmology, so the harder stuff at least on the book that I could imagine, I would never understand it. And I think that was right. It was sort of in some ways the most beautiful, most mathematical in a way, but simplest way of looking at some of the most complicated things you can imagine, like the beginning of the universe or what stuff is made out of.

And I think that was a great education into how the power of ideas, the power of building somewhat simple models that one can keep improving.

And really this kind of idea, the thing that you can build, that science is really special and only in science could you actually have a handle on this kind of perspective, which is that sometimes a person can come up with an idea and this idea which can be about — typically the Einstein's always the example,  you're in an elevator and you're comparing how you experience fall, whether it's by gravity or whether it's the force of the elevator — and how simple ideas like this or how far or what happens when you travel in the beam of light. These ideas, we start playing with them can take you all the way to what stuff is made out of in the simplest, smallest sense like Murray Gell-Mann here at the Institute worked on and changed our perspective on or the very beginning of the very end of the universe.

I'm inspired by at least daring to try to ask questions that can take us to ideas that have that kind of scope, right? That you can start locally and end up having an idea that traverses time or place. And I think when you come back to social sciences and to cities, cities are places that have this property, right?

You can imagine the cities in the beginning of civilization, something changed and we never looked back in some ways, but that also have the scope for change and transformation. And so it's a very different set of ideas, physics has very little to do except in practical simple ways of what happens in the city. But at the same time asking what are these processes that cities are facilitating? What is this their scope?

Michael: Yeah, moving from the specific example of Lisbon to the universal example of scaling laws as they manifest in the city — and maybe I'm jumping ahead of ourselves here, but I love that one of the ideas in your work is the city as social reactor.

So I guess, this is where I would ask you, given the amount of time that you've spent on this, given the fact that you're here leading the Global Sustainability Summer School and that you're at the head of the Mansueto Institute for Urban Innovation, you have an idea of what a city is. So, Luis, what is a city?

Luis: Good. So a city at it's most essential is really the concentration of social relationships between people in space. And these two effects, the spatial concentration, the development of course of infrastructure and build spaces and the interactions between people are mutually supportive, that's what a city is.

And that can appear in a number of different forms, those social relationships may be more or less economic, that's you see throughout history that it has changed. And of course the spaces of cities can be quite different from very geometric to very curvy to taller or shorter.

But the point is that by concentrating human interactions in space and time, you create a different logic for their scope and possibility and you'll find all these amplification effects where someone's imagination can be multiplied by all of these relationships.

Another way of saying it is that cities is a social reactors, really they're promoting many different interactions the reactions. And this can have a can create what people call sometimes network effects by which the benefit that you collect from being in these environments is multiplied by the number of relationships that you can have, which increased faster than the number of people involved.

It's a magical thing that the number of relationships goes typically with n^2, where there's only then number of people in the city. These effects show up also in technology and the internet, but in the cities they mediate that through space and time.

Michael: That means that the city, it feels when you're inside a city like New York is I guess a kind of a classic American example that you're inside a living creature, but your work draws some important distinctions between the way that a city functions and the kind of properties that we see at work as a city scales and its population to the kind of scaling at work in organismal systems.

And so how is the city different from other kinds of complex systems that we observe in physics and biology and why?

Luis: Sure. I mean, on the one hand the city feels like it has all this life, because it's our life, right? But by being in a city we behave differently, we have different relationships and possibilities for what we do. And so you see also this kind of interesting acceleration and diversification of what people can do.

 The question is, is there any other system that we know maybe better or in a different context that behaves like that? And in some of my work, I tried to say that no, in many ways there are facets of this problem that you can see now that are complex systems, but it's combination of effects is really special to the city, it's really special to creatures like us.

I think humans, ultimately, are creatures of information. So a lot of what our life is about is combining what we know and can do with different things that other humans can do and can know to create something that no one of us understands. So the city is an environment to do that, but it's not the only environment.

Again, all kinds of technological networks have very much the same character. When we started the work, it was very typical SFI, because it started with a workshop on human and social organizations mostly. We have talks, it was a part of a joint network funded by the European Union and some people in the US. And so we brought together people that looked at cities, that looked at firms, that looked at governments, that looked at other institutions.

So there were a number of very interesting talks about how all these systems worked. And there was a subset of us that got more interested in cities and Geoffery West is one of the organizers of this. But in the back of these talks, my friend Jose Lobo just kept doing the same thing, sort of the hubris of youth, saying that, "Why don't you measure that? Are you sure it works like that?" That kind of question.

And so we went away started of measuring and that's how we started seeing some scaling laws that from the beginning, the first one we saw was looking at wages versus city population. And what you find, I think we all have an intuition for this, is that if you go to a larger city, people typically even on average, make more money per capita in New York city say they're in the smaller city and of course they pay also higher costs.

But the point is that there's sort of, you're making more money and spending more money. And if you visit a larger city from a small city, you will see that things are more expensive that's the good expression of that. From the beginning, we knew from biological organisms that for different quantities, like energy use, that the larger the organism, the smaller the energy use per unit of mass, so their analogy seemed already to be sort of upside down.

If money is energy, right, there was more money being created or exchanged per unit, per person, and the organism, there was less energy bigger than that. That continued to get us going and to start to see how that could be.

And so in some sense, to tell a long story somewhat in relatively short terms, what happens, we think, at the level of organisms is that organisms, as they get larger, more massive, you tend to have an economy of scale and a slowdown of metabolism and therefore of all time scales in the life of an organism, so an elephant or a whale is longer, but also does things most slowly through the life course, than a smaller mammal like a mouse or something smaller. And that's was understood by the work of Geoffrey West, Brian Enquist, and Jim Brown and others.

But that effect is interpreted really as a saving, that you wants to be efficient and spend as less energy as you can and doing a similar function. A city doesn't seem to be doing that, in fact the city is not efficient. We having a school of sustainability in part, because cities are not built to save energy.

In fact, they tend to spend a little bit more energy, at least their urban systems do. But there are about all the things you could do with interactions, so they tend actually speed you up and make you go faster. Sometimes they change infrastructure and you can save some energy that way, but if you don't, then you just go faster and spend more energy.

The city in that sense is not like an organism, it's almost opposite of an organism. It's built for speed, not for savings. An ecosystem is a little bit closer, because you can have more interactions and more diverse things and create a more complicated, more efficient, more productive use of energy and resources and this is known in ecosystems that more diverse ecosystems most often also are more productive.

But an ecosystem is very limited by the energy that falls in its own territory, so the energy of the sun in the area of the ecosystem. If you were to compare again a rough thing, if you compare species as specializations and if you compare like types of jobs in cities, cities are incredibly more diverse and having creatively much higher energy density.

If you ask what is the energy by unit time being on an area, cities have incredibly higher energies than ecosystems. And the reason again is that we import a lot of energy to go faster, so cities kind of attract all the stuff concentrated and make us go faster in terms of what we do and how we interact.

And so the only system that has sort of these properties that I know of exist in nature that concentrates things, increases interaction rates and admits products at a rate that's higher, per unit of mass is the sun, is a star and that's a reactor, right?

It's exactly what it's doing, it's creating light and neutrinos and other things by having the power of gravity, drawing things together and creating higher and higher interaction rates with the amount of mass in the star and that creates novelty, creates new elements all the way to carbon, oxygen and iron and other things as the mass of the star increases and those interaction rates increase. The physics of the star is limited and runs out eventually of resources and energy, but has a little bit of the same logic as you see in the city.

Michael: It strikes me sitting at great distance from conversations about loop quantum gravity and stuff like this, that there are people out there trying to come up with an informational definition for gravity and that we may be approaching a more rigorous way of talking about the "gravity of a city,” it's alluring quality.

The ability of a city like San Francisco to accumulate creative and intellectual capital. What does the science of cities say about a city's, I don't know, sex appeal in that way? Because I mean, you'd make an important distinction here that an ecosystem is not advertising itself to other ecosystems and trying to like recruit species into itself exactly. I mean, I don't know, take that anywhere you want to go with it.

But one of the things that's characteristic of your work is that you say that you're not talking about specifically modern cities, you're talking about ancient cities as well. It sounds to me as though cities can really only be understood and as themselves creatures of a network, and that they're in communication with each other, otherwise it just doesn't make sense.

Luis: Yeah, cities are basically the creation, very concentrated network in a place. But then they’re part also of larger networks between cities. It's a little bit of the difference between what can happen in a day and what can happen on a much longer time scale. Right. The stuff that gets exchanged between cities is interesting, but it's slower, right? So you cannot get a hair cut from San Francisco today here, or a meal.

Michael: Not yet.

Luis: Not yet, maybe one day, and we'll kind of refactor things. But the point is there are things, particularly services, exchanges of information, figuring out things a little bit, ambiguous, that proximity and speed and closeness in space and time really facilitate. The things that don't have that character, which of course is also a function of technology of course tends to leave the city, because cities are expensive places.

If you can move things out of cities, you tend to through economic forces, examples on manufacturing and manufacturing often through the history of cities created in many ways modern cities with the industrial revolution, arguably are creating the big cities of China.

But in US for example, in Europe and increasingly in Japan and other higher income economies, manufacturing, of most things anyway, is no longer such a value added that it can be sustained economically in cities and at the same time is understood enough, that can be moved to smaller places they don't have necessarily the same skills and knowledge, but can run the recipe in a way that makes sense economically.

There's always sort of a cycle of things that are attracted to cities and then move out of cities. A more personal example is if you ask, okay, again, some people like cities, some people don't love cities in particular. If you ask, "Who comes to large cities?" Right? And there's a very clear signature that you can say this for American cities for it should have very good data, for other cities we think it's similar, but it's mostly young people that are more educated. They are coming to assemble their own network.

In some sense they are coming to react, to acquire education experience from their first professional networks, elaborate on those. And often later in life, they may then move out of a larger city, either to get more space, maybe they just go to the suburbs, but often they move to other cities and then can carry the value of what they acquired, their network now gets stretched and get exported to the city.

And so there's always things coming in and out, but the place where you assemble and have access to that rare is potentially but not always in reality, but potentially more valuable, more interesting things tends to be at the hottest places of these social reactors, so it's often worth it to come through and do that.

Cities are very dynamical, but they're places where you are doing most of this exploration of social spaces and creating of your own space. Their attraction is not like gravity that attracts everything, but it's actually a little singular, because they attract people that want to interact, that may benefit from these interactions, that may be able to find a cost-benefit in an expensive place that makes sense for them. And therefore that becomes much more interesting to study, and a lot of studies of migration and economic development innovation are exactly about that: what sectors but also what people make sense in each place given their composition. It's much more complicated than a star, but it has a little bit some of the same at least that first pass properties.

And it's interesting, because when people started studying migration, the metaphor they actually, they put into math is exactly that, that cities have a certain gravity. There’s something called the gravity law, which isn’t a law but an empirical regularity, but it says how many people come to a city and go between two cities.

And that the simplest version of that is that it's proportional to the number of people there in each city. Basically, in each city you have a certain probability of going to another city and the probability of going to a specific city is proportional to the number of people there, so the number basically interactions they could in principle realize there.

That actually kind of holds and has a certain explanation and allows also the whole system of cities to stay together, but it is not gravity per se, it just has a certain mathematical form that kind of looks like gravity, but it's wrong because it's more like gravity in three-dimensions not two-dimensions, so that's just a technical level thing.

Michael: Well, I don't know, there's something in there — not to stretch the metaphor, where you've clearly already bounded it — in the evaporation of a black hole or something, that you reach a size and then you've grown as much as you can and then you're just slowly off-gassing people into the exurbs, or whatever.

I wonder because in your 2013 paper on the origins of scaling in cities is one of the things that you talk about is that you're making an assumption about the boundedness of human effort, that a city in theory can get more and more dense and more and more accelerated in its facilitation of social interaction.

But at some point like there are only so many seconds in an hour and if you look at Doug Rushkoff talking about the way that Manhattan is architecturally being really designed to look like a macro-scale computer chip in order to facilitate these high frequency financial trading processes, it's making it sort of less and less habitable to human beings.

It kind of begs the question, is there an effective limit to the size of a city? Or perhaps, is there an effective limit to the size of a human habitable city? And then a new category that we haven't really seen on this planet yet, but is it possible that this thermodynamic reaction is going to lead to something like Robin Hanson the economist imagines, where we have cities that are entirely digital that people don't even live within.

What do you think about all of all of this? Where does this take us? Because clearly we're not going to get, like in Star Wars there's the capital of the Galactic Republic is Coruscant, and the planet is entirely covered in metropolis.

Luis: It's an entire planetary city.

Michael: Right. Now, what you're saying is that, it sounds to me like that can't happen, because the city and the rural and suburban areas around it form sort of like different types of tissue and that they depend on each other. And what do you think is the end game of this massive demographic shift that we're seeing here and what kind of balance do you think we're going to strike?

Luis: People love limits, right? And there are so many papers written about the city cannot keep going, getting bigger and so forth. Even back to the Greeks and they're saying this and they're thinking that 30,000 or some things to limit.

Okay, so just keep that in mind — or Malthusian arguments about the size of population, where in some cities are in whole societies. In complex systems usually it's not a single thing that's going on. It's not just how much energy or somebody who can concentrate, but they're a bunch of trade offs, so some things are changing that making, bigger sizes or more interactions possible.

And I think this is completely intuitive, you can study this through data and analytically, but the point is that you see that when you live in the largest city, so part of the point of the argument, in fact I tried to call it a principle in the paper, is that people change their behavior as they live in places with more or fewer interactions and this is well known to social psychologists and they've studied this a lot.

But when you live, for example, in a larger city, you expect things to go faster, for example, it's very hard when I come back to Santa Fe, how long a cup of coffee takes. I want my cup of coffee to be fast. And that goes with almost everything that's more or less standard you will observe and I hope that people listening to this will do their own personal experiments, go to different places and see how certain services are faster or slower in different-sized cities and also in different societies to some extent.

But we use a lot of technology also to mediate how we navigate space, the last 20 years have been amazing, right? It's very hard not to navigate a large city without a map or somebody telling you, what's the best route or what you can find around you.

And also to coordinate your social encounters and your social life via cell phone they have all the time. Right? I don't really, if anyone still remembers, but you'd meet at a cafe and never know which one was the right one, there was a lot of waiting. There's a lot less of that happening.

We’re kind of always cutting at the space in between, that's why people walk faster in larger cities, they're kind of trying to compress that time and at the same time finding opening up space, that's interaction space for difficult things, like the things that actually have value. like presumably at work, or your family, things you dedicate a lot of time to.

We're always sort of compressing time, making uses that are essential, more efficient, this is why urban services is so important. You don't want to have to think about your water or your electricity or reliability or transportation, you just want it to be there. But of course if you go to places out that are poorer or back in history, these things took a lot of time.

This compression of time is also something that's mediated through technology that then allows you to reallocate that released time to more interactions or to better quality interactions, so that's the game: as long as that keeps going on, you can keep on refactoring this and the city is sort of an intensification of the social networks, at least over some periods of time, can keep going.

If you understand that that limit can break at some point for some fundamental reason, which I don't think you can for a simple fundamental reason, like the speed of light is something, then yes, you will have a ironclad argument. But in fact what you observe is that there's always been sort of a struggle to make things more intense and to work better and to substitute things that sort of more mundane into our technology and our services, So to that extent, cities can keep going.

Michael: I remember visiting New York, 2005 and managing to get around without a cell phone and then 2013 praising a smartphone and Google maps. It sounds like you're kind of putting hope in the fact that in 2045, we'll have Neural Lace not to get around. That our cities will get so insanely dense that they make no sense to someone today, but we'll find new ways because the reactor of the city itself provides these innovations.

Luis: Yeah and in some sense we're changing our behavior, our cognitive capacities on analytical powers, our perceptions of space and time through this process. In many ways cities are bending space and time, they're making it more intense, more full, faster in terms of the number of events and that complexity that happen in space and our ability to manage them.

This is part of their magic, is that they allow things that we never thought were possible, possible, but they come through this intensification, they need to manage these very intense environments full of challenges and full of you know what sometimes psychologists called urban cognitive overload.

We are always at the level of overload and always trying to cope and improve on that. And then that trickles through the whole system, not just the large city and allows people everywhere to do new things, so that's kind of very special. Of course, it will have ultimate limits, but in many ways the actual limits keep on being pushed.

Michael: You brought up just a moment ago the access that people have to basic urban resources, to sanitation and basic services. You wrote a paper recently on eliminating slums and applying a network model to looking at the complexity of urban blocks and finding a really clever strategy for interventions to open up new spaces, and I'd love to hear you talk to people about that.

Luis: Sure. Well, so there's a general problem, which is that in many ways as cities form, because as we described cities as a form of connectivity, right, it's a connectivity that's both physical in terms of having road accesses and street access and transportation, but having the pipes and water and electricity, all of these are kind of very physical.

But then of course the social economic connectivity and opportunities that all that helps mediate and that may also has independent elements that need to be added, so as a city forms that network is forming. And when you look at slums or people that sort of at the edge of the season, sometimes socially, sometimes in physical terms, that network is not there yet. It's an incipient part of the city, if you will, in many cities of course that have become higher income and to a large extent eliminate extreme poverty, you've seen their process. A lot of places that were sort of informal, built by hands, not formally connected, were connected eventually in good ways and bad ways, but effectively address the issue.

But as we look at some of the explosion of art in the growth of the last decades, we now have maybe up to about a billion people living in conditions that are just incipient in this sense and they're very exposed to climate change and other emergencies and live in poverty.

But a lot of people, when you come to these places, live in hope that that process is happening quickly in their lives and that they hope that it will happen such that they can become full urbanites, but in a sense fully part of a network of entrepreneurship and creativity, et cetera, that cities can mediate.

What we do is to ask sort of the fundamental question about how cities are organized in this case spatially. And so the obstacle to that thinking is that for a long time and this is, also a very beautiful, very appealing thing to do is to go around and see that different cities have different shapes. Some are very regular like Chicago, where I live now and New York, some are very curvy and some have lots of cul-de-sacs, some don't.

All kinds of different cities have different sizes of blocks. And at the end of the day that matters a little bit for how people need to travel, and therefore energy use and transportation. But from the point of view of the socioeconomic products of the city, they don't matter that much.

A city like Silicon Valley, which is very extended, is very rich. City like New York that's very concentrated, is very rich too. They do different things, but in some sense the interactions that they promote, have extreme value anyway and so the consequences of that spatial forum is not fundamental, even though they are instrumental.

The point is, so what's the essential element of the street network? And how has this organized spatially? Essentially, it is that people have to live somewhere, in a building, if you're not homeless for most people are not homeless, they need to often work somewhere else and they need to, in a city, everyone is interdependent. You cannot grow your own food and so forth, so you need to go around space and find food, find services, work, et cetera.

And so that process requires that you have access to your bigger place where you live and work is serviced, so it has water and sanitation and it’s a decent place to live and work, but also that you able to move around.

And so that property is not a geometry, it's a topology. It's just the relationship that you start from where you wake up, you step onto the street, you go along the street or the subway, end up in a different place, different building and you repeat.

And that just means that places, so essentially houses and offices, are connected by streets. That's it. And these streets have a certain property. But the point is you can jiggle that geometry around and find ways to create accesses to places as they exist now.

And when you go to a slum you have places where people live, sometimes shacks and places that are under built, but they're not connected, they don't have street front, because of that they don't have sanitation, they don't have water, they don't have other connections, they don't have an address.

And you can find by applying these principles of topology, access points that allow you to connect to these places without infrastructure to an extension of the existing network in a way that's minimal and that does the minimal disturbance and that creates curvy streets typically in cul-de-sacs.

But these are the qualities of a lot of cities that we like, as they were able to develop and create services, say in old cities in Europe, old cities in Asia, and that planners thought were impossible to service with street networks, because they're too complicated and too costly.

And so what we do is a mathematical demonstration that servicing these places with street networks and allowing them for it to develop and be connected to the city is possible and provide a method that allows us at least to have a first guess at the minimal rate in which that can happen and that allows a starting point for communities and their cities to decide how to continue to develop that infrastructure.

Michael: Yeah, one of the things reading that paper, I was thinking about you mentioned elsewhere talking about, “What is an optimally productive city?” And in that paper you said, "Cities may be suboptimal either because they do not realize their full social potential or because they do so in a manner that renders transportation costs too high."

And I was thinking well, there are two to solve this problem. One is to carve new streets, one is to change the incentive landscape that changes the cost-benefit equation for how we're able to provide services to those areas.

I'm thinking of how the Metacurrency Project did a pilot project in a favela outside of Rio de Janeiro, where they gave people living in the favela bus tokens and exchanges for bags of trash. And so they had the children of the families were collecting trash and then collecting the bus tokens, and then they were able to send their parents into the city and work, but without having to actually create any additional infrastructure.

And so I'm curious in light of that, and in the space between those two examples, what other genius hacks are you seeing deployed around the world that address this kind of an issue?

Luis: Yeah, I think the issue is that if you start by thinking that a good city needs to realize this potential by which people can be socially, economically, civically connected, that's the basis of it.

And having choice in those connections such that they can be creative, they can be entrepreneurial, that's what at the end of the day creates good cities where people feel they have agency, and through the agency and hustle end up creating new things that have new value.

At the same time, there are a lot of barriers to that, both economic, social associated with stigma and then physical, right? They have to do with the fact that often in poor places people are the infrastructure, they pay with time, so basically that disabled from being socioeconomic creative agents. That's one aspect of it that we're trying to address with that work on expanding access networks.

But at the same time you can also work, even if people are provided that there are good public services and that is no longer an issue, imagine that you start with a neighborhood that's socially and economically disconnected and also physically disconnected. You may create access to services and infrastructure so that this neighborhood at least doesn't have that sort of problem.

But then you have the classical problem, say of the American city or some European cities, we have very poor neighborhoods that have physical access, but they're still socioeconomically disconnected and that one thing doesn't necessarily follow from the other. It is possible that by creating services, people now have time, they are able to access knowledge and relationships and therefore also have access to socioeconomic improvements in their lives.

But one thing does not follow immediately from the other, right? There’s an articulating argument, but one when is not instantly provided by the physical infrastructure as often people think in planning.

You could start at the other end and just start creating socioeconomic relationships as in your example in the hope that also creates physical and health conditions in neighborhoods and then you'll have a similar problem: does that actually follow or are there impediments to that?

It's very hard usually for poor communities to build streets and sanitation and reduce violence by themselves and that usually takes institutional interventions and public services. But to some extent it may work, but again, maybe you can start with one kind of connectivity and develop the other or maybe you have to develop them in tandem.

But again, this perspective, the city has a complex system where many types of relationships are self-reinforcing and allow people to be more creative socioeconomic agents, that then allows you to start thinking about that in a different way and what nucleates what is, you will have different paths to create solutions because these hacks, as long as they are self reinforcing a great virtuous cycles of change, then you're on the right track.

But that I think opens up a lot of space to think about interesting urban interventions that are more systematic and that can take a life of their own, that are good for people, not just stay in one realm like physical infrastructure and not do anything for socioeconomic issues.

Michael: I'm not going to hold you accountable for this answer, but what do you see as currently the most interesting problem for you in this space? Like right now, here at the Global Sustainability Summer School, I'm sure you're being bathed in interesting ideas.

Luis: Well, there're several, I think interconnected issues. I think, from the point of view of sustainability, we're facing obviously a transition that's not just about cities, but because most people, most money, most technology are now in cities and because a lot of political will is in large cities have to do with how citizens inform themselves.

Sustainability means many different things, it used to mean almost exclusively that we think about the environment and climate. And specifically we take away a lot of the carbon emissions and other greenhouse emissions that our energy systems create and some of the other pollution like plastics or evolution associated with that.

But increasingly what cities are doing is to very intentionally coupling that situations of equity, so issues that have to do with inequality in particularly sectors of the population that may be disconnected and lack opportunity. And then issues actually of economic growth, where we want this transformation to not just be a substitution, right? You can imagine taking every gasoline car and replace it by electric car, we end up with the same city, right?

Or replace a coal-fired power station by a solar farm you end up at the same city. Okay, that does something. But the idea is that this transformation should actually be good also to promote innovation and new invention, new business models that will be a big part of the economy of employment going forward.

We just had talks, for example, the City of LA that has an initiative on clean tech, the City of Chicago that tries to couple a lot of what it does with also economic innovations. But this is all stuff that's just bubbling up. We don't know how to couple these things in a very effective way, so there are many experiments throughout the world in many cities and that's really interesting to see and that's what we're doing with the Global Sustainability Summer School.

I think too, then, to become a little bit more abstract about those issues, is that cities always in transformation and the main issues have to do with firstly structural issues, how do we create cities that more enabling of more people. And I think we've been a bit in autopilot thinking often from a policy perspective that cities are zero sum games, that by making somebody's life a little bit better, somebody else needs to pay for it. And the character of cities is exactly that they're not like that, that there are channels by which people can work together, create a firm or create an idea, create a new service by which they can create value and generate growth.

But you need to be intentional about helping create those channels and helping bridge, different sectors of population on this socioeconomic or racial whatnot, subset that diversity tells and he's able to create value and a better life, so cities have exactly that property because of their network effects.

But often they're addressed in policy as a zero sum game. And that means that if I am going to transfer some money effectively from a rich neighborhood to a poor neighborhood, that people do this because they’re charitable and not because this can actually create better lives for everyone and create a positive sum relationship.

That's very important to have that conscious, that's what cities are for, that's what cities are good at. And finally, building on all that is really a better understanding of processes of change. For example, the process of economic growth we know has a lot to do with information, same thing in biology.

Evolution has to do with new ways in which life can use the energy of the physical environment and resources to do new things. Same thing with human societies. You have to say how the processes are different, but there's a similar logic that in many ways cities again are places that very starved for energy and resources that are always scarce, but they're all about information, what we use those resources to do.

And that creation of new information of new forms of value creation is essential. And while we've been discussing them at the macro level, at the level of what is the 3% growth GDP for a nation or even sometimes even for a city, we do not know how to unpack that process and now ask for example, if it's Santa Fe today, was there economic growth? What were the sources? What was it for that person or that neighborhood?

We don't have a way to have access to the true, macroscopic personal level processes that creating that change. And because we don't have access to those, we don't have a really good way of incentivizing them or creating essentially a process by which we can select what we do and how institutions work that are actually creating positive transformations, both economic and otherwise.

And so we’re missing a fundamental understanding of how cities as these environments that create change work in a short term dis-aggregated way. And in the lack of that, we often have policies that promote growth that create a lot of inequality, because most of the resources are with rich people, so we want to give them better conditions to invest, for example. That creates actually additional value in a financial sense, but it doesn't create a better city that's better prepared for the future as a place of innovation.

Michael: You think that that's something that can be routed around? Because one of the things that comes up again and again and the conversation around scaling population growth is the bigger the city, the more socioeconomic inequality. And so in a way it seems that we're constantly falling off of that treadmill by virtue of the physics of it.

Luis: Yeah, it's true that as cities that create transformations, those transformations tend to be expressed unequally, but that's not just the fault of cities, it is also a fault of cities. But goes a lot through of course, structures of production, what firms do, what kind of wages and wage inequality they promote, which is basically the redistribution of a collective production, right, very Marxist perspective.

But still and we know how much does the CEO make versus the medium worker or something. So there's a very interesting problem partially tackled in technology and economics. But I think coming to the for also in urban environments, which has to do with the fact that if what we produce is always collective, scientists know this well because they need to, in papers we always have many names: who should get which fraction of the value, right?

Do we redistribute equally? Well, that's not what firms do for sure. Right? The CEO makes a lot more money, if we don't distribute equally, how much should each part make? And if somebody whose work is really very synergistic with their own farm or their own city, rather than just being every janitor is the same, every CEO is the same, then you have to recognize that and actually compensate people in certain ways.

But we've been lacking essentially the formulas, the understanding the mathematics to think about this straight and I think I'm most excited and this is something I'm working a lot on, with this nexus between resources and information and how it's pulled together to create sophisticated things that have a lot of value on the one hand, which is what cities are so good at doing, and at the same time, how that creates a virtuous cycle where the products of this collective production continue to create better lives, better cities, and continue to create hopefully societies that are creative, that feel good, that have good quality of life for everybody, and that are in a better relationship with the planet that can be constructive and not destructive.

Michael: That actually leads really neatly into the last question I had for you, which is you've lived all over the place. You've lived in London, you were a postdoc at MIT, Lisbon, Heidelberg, Los Alamos. You've seen many different kinds of city, you study this stuff. Were you to decide that you were going to relocate based on — not a job you're done in Chicago — what are you looking for? If you're just choosing on like the character of that city alone, what do you consider the most desirable aspects? Or what would you suggest to someone who is going to spin the globe and take a crap shot at this?

Luis: Well, that's a very difficult question, because sometimes I say cities are like children: we love them all, right, for somewhat different reasons, but the city's also very polyphonic, right, so there are all these characters, those are bad things and good things in each place. And so I think that and as we talked about, if you go to a large city, it can be more exciting, there're more social and economic possibilities, but you pay a high cost, the thing is more expensive, you live in less space.

It depends on what you want at what stage in life. When I was a student I was happy in London then, I still have very many good friends of that time in London and I see their lives, which is in some sense, exciting in some dimensions, but limited in others. Right? I think the best thing actually is to evade your question.

I don't want to give you a political answer, but continue to sample what's good about different places, you can do that through travel, but you can also as opportunities come up in your life and go to a place that excites you as you're trying to discover things in your life that you may want to do and be exposed to.

If you know what you want and you want some space to go to a smaller city that gives you space, Santa Fe is wonderful for that, come to Santa Fe. But if you want to scale up what you do, we may have to go to Chicago or a bigger city again to do that.

Different places have certain advantages and disadvantages and it's an urban world where a lot of these places, you can bring the experience of one place to another and that's a very enriching quality, So enjoy that. Enjoy that possibility of being in many different places through your life course, through your experience.

And the trick goal is, is to be an active agent, make the most of each place and search for what's good and what you've been missing in that place in others.

Michael: That's awesome, Luis. Thank you so much for taking the time.

Luis: My pleasure.