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Indo para Dresden dia 20

International Workshop
23 – 27 April 2018

Complex dynamical systems can show sudden transitions to very diverse regimes including dangerous ones such as desertification or epileptic seizures. The workshop will focus on new advances in data-driven approaches for identifying,  characterizing and predicting regime transitions, and promoting cross-fertilization across disciplines.

Topics include

  • ecology
  • biophysics
  • data analysis
  • econophysics
  • brain dynamics
  • social networks
  • extreme events
  • complex systems
  • climate dynamics
  • critical transitions
  • information theory
  • nonlinear dynamics
  • time-series analysis
  • stochastic processes
  • early-warning signals

Invited speakers

Kazuyuki Aihara (JP)
José María Amigó García (ES)
Dante Chialvo (AR)
Jörn Davidsen (CA)
Henk Dijkstra (NL)
Ulrike Feudel (DE)
Petra Friederichs (DE)
Jordi García Ojalvo (ES)
Emilio Hernández-García (ES)
Holger Kantz (DE)
Mark Kramer (US)
Christian Kühn (DE)
Jürgen Kurths (DE)
Inmaculada Leyva (ES)
Milan Palus (CZ)
Ulrich Parlitz (DE)
Martin Rasmussen (GB)
Hui Ren (CN)
Osvaldo A. Rosso (BR)
Maria V. Sanchez-Vives (ES)
Eckehard Schöll (DE)
Michael Small (AU)
Linda Sommerlade (GB)
Aneta Stefanovska (GB)
Piotr Suffczynski (PL)
John Terry (GB)
Raul Toral (ES)
Lev Tsimring (US)
Michal Zochowski (US)


Jaroslav Hlinka
(Academy of Sciences of the Czech Republic, Czech Republic)

Klaus Lehnertz
(University of Bonn, Germany)

Cristina Masoller
(Universitat Politecnica de Catalunya, Spain)


Mandy Lochar
(Max Planck Institute for the Physics of Complex Systems, Dresden, Germany)

Engels e a Complexidade

Nova versão do paper, possivelmente a ser publicado na Revista da Tulha – USP

A precursor of the sciences of complexity in the XIX century

The sciences of complexity present some recurrent themes: the emergence of qualitatively new behaviors in dissipative systems out of equilibrium, the aparent tendency of complex system to lie at the border of phase transitions and bifurcation points, a historical dynamics which present punctuated equilibrium, a tentative of complementing Darwinian evolution with certain ideas of progress (understood as increase of computational power) etc. Such themes, indeed, belong to a long scientific and philosophical tradiction and, curiously, appear already in the work of Frederick Engels at the 70’s of the XIX century. So, the apparent novelity of the sciences of complexity seems to be not situated in its fundamental ideas, but in the use of mathematical and computational models for illustrate, test and develop such ideas. Since politicians as the candidate Al Gore recently declared that the sciences of complexity have influenced strongly their worldview, perhaps it could be interesting to know better the ideas and the ideology related to the notion of complex adaptive systems.

Comments: 29 pages, no figures, in Portuguese
Subjects: Popular Physics (physics.pop-ph); Physics and Society (physics.soc-ph)
Cite as: arXiv:physics/0110041 [physics.pop-ph]
(or arXiv:physics/0110041v2 [physics.pop-ph] for this version)

O crescimento econômico visto por um físico

U.S. total energy 1650-present (logarithmic)Total U.S. Energy consumption in all forms since 1650. The vertical scale is logarithmic, so that an exponential curve resulting from a constant growth rate appears as a straight line. The red line corresponds to an annual growth rate of 2.9%. Source: EIA.

Exponential Economist Meets Finite Physicist

Some while back, I found myself sitting next to an accomplished economics professor at a dinner event. Shortly after pleasantries, I said to him, “economic growth cannot continue indefinitely,” just to see where things would go. It was a lively and informative conversation. I was somewhat alarmed by the disconnect between economic theory and physical constraints—not for the first time, but here it was up-close and personal. Though my memory is not keen enough to recount our conversation verbatim, I thought I would at least try to capture the key points and convey the essence of the tennis match—with some entertainment value thrown in.

Cast of characters: Physicist, played by me; Economist, played by an established economics professor from a prestigious institution. Scene: banquet dinner, played in four acts (courses).

Note: because I have a better retention of my own thoughts than those of my conversational companion, this recreation is lopsided to represent my own points/words. So while it may look like a physicist-dominated conversation, this is more an artifact of my own recall capabilities. I also should say that the other people at our table were not paying attention to our conversation, so I don’t know what makes me think this will be interesting to readers if it wasn’t even interesting enough to others at the table! But here goes…

Act One: Bread and Butter

Physicist: Hi, I’m Tom. I’m a physicist.

Economist: Hi Tom, I’m [ahem..cough]. I’m an economist.

Physicist: Hey, that’s great. I’ve been thinking a bit about growth and want to run an idea by you. I claim that economic growth cannot continue indefinitely.

Economist: [chokes on bread crumb] Did I hear you right? Did you say that growth can not continue forever?

Physicist: That’s right. I think physical limits assert themselves.

Economist: Well sure, nothing truly lasts forever. The sun, for instance, will not burn forever. On the billions-of-years timescale, things come to an end.

Physicist: Granted, but I’m talking about a more immediate timescale, here on Earth. Earth’s physical resources—particularly energy—are limited and may prohibit continued growth within centuries, or possibly much shorter depending on the choices we make. There are thermodynamic issues as well.

Economist: I don’t think energy will ever be a limiting factor to economic growth. Sure, conventional fossil fuels are finite. But we can substitute non-conventional resources like tar sands, oil shale, shale gas, etc. By the time these run out, we’ll likely have built up a renewable infrastructure of wind, solar, and geothermal energy—plus next-generation nuclear fission and potentially nuclear fusion. And there are likely energy technologies we cannot yet fathom in the farther future.

Physicist: Sure, those things could happen, and I hope they do at some non-trivial scale. But let’s look at the physical implications of the energy scale expanding into the future. So what’s a typical rate of annual energy growth over the last few centuries?

Economist: I would guess a few percent. Less than 5%, but at least 2%, I should think.

Physicist: Right, if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. So how long do you think we might be able to continue this trend?

Economist: Well, let’s see. A 3% growth rate means a doubling time of something like 23 years. So each century might see something like a 15–20× increase. I see where you’re going. A few more centuries like that would perhaps be absurd. But don’t forget that population was increasing during centuries past—the period on which you base your growth rate. Population will stop growing before more centuries roll by.

Physicist: True enough. So we would likely agree that energy growth will not continue indefinitely. But two points before we continue: First, I’ll just mention that energy growth has far outstripped population growth, so that per-capita energy use has surged dramatically over time—our energy lives today are far richer than those of our great-great-grandparents a century ago [economist nods]. So even if population stabilizes, we are accustomed to per-capita energy growth: total energy would have to continue growing to maintain such a trend [another nod].

Second, thermodynamic limits impose a cap to energy growth lest we cook ourselves. I’m not talking about global warming, CO2 build-up, etc. I’m talking about radiating the spent energy into space. I assume you’re happy to confine our conversation to Earth, foregoing the spectre of an exodus to space, colonizing planets, living the Star Trek life, etc.

Economist: More than happy to keep our discussion grounded to Earth.

Physicist: [sigh of relief: not a space cadet] Alright, the Earth has only one mechanism for releasing heat to space, and that’s via (infrared) radiation. We understand the phenomenon perfectly well, and can predict the surface temperature of the planet as a function of how much energy the human race produces. The upshot is that at a 2.3% growth rate (conveniently chosen to represent a 10× increase every century), we would reach boiling temperature in about 400 years. [Pained expression from economist.] And this statement is independent of technology. Even if we don’t have a name for the energy source yet, as long as it obeys thermodynamics, we cook ourselves with perpetual energy increase.

Economist: That’s a striking result. Could not technology pipe or beam the heat elsewhere, rather than relying on thermal radiation?

Physicist: Well, we could (and do, somewhat) beam non-thermal radiation into space, like light, lasers, radio waves, etc. But the problem is that these “sources” are forms of high-grade, low-entropy energy. Instead, we’re talking about getting rid of the waste heat from all the processes by which we use energy. This energy is thermal in nature. We might be able to scoop up some of this to do useful “work,” but at very low thermodynamic efficiency. If you want to use high-grade energy in the first place, having high-entropy waste heat is pretty inescapable.

Economist: [furrowed brow] Okay, but I still think our path can easily accommodate at least a steady energy profile. We’ll use it more efficiently and for new pursuits that continue to support growth.

Physicist: Before we tackle that, we’re too close to an astounding point for me to leave it unspoken. At that 2.3% growth rate, we would be using energy at a rate corresponding to the total solar input striking Earth in a little over 400 years. We would consume something comparable to the entire sun in 1400 years from now. By 2500 years, we would use energy at the rate of the entire Milky Way galaxy—100 billion stars! I think you can see the absurdity of continued energy growth. 2500 years is not that long, from a historical perspective. We know what we were doing 2500 years ago. I think I know what we’re not going to be doing 2500 years hence.

Economist: That’s really remarkable—I appreciate the detour. You said about 1400 years to reach parity with solar output?

Physicist: Right. And you can see the thermodynamic point in this scenario as well. If we tried to generate energy at a rate commensurate with that of the Sun in 1400 years, and did this on Earth, physics demands that the surface of the Earth must be hotter than the (much larger) surface of the Sun. Just like 100 W from a light bulb results in a much hotter surface than the same 100 W you and I generate via metabolism, spread out across a much larger surface area.

Economist: I see. That does make sense.

Act Two: Salad

Economist: So I’m as convinced as I need to be that growth in raw energy use is a limited proposition—that we must one day at the very least stabilize to a roughly constant yearly expenditure. At least I’m willing to accept that as a starting point for discussing the long term prospects for economic growth. But coming back to your first statement, I don’t see that this threatens the indefinite continuance of economic growth.

For one thing, we can keep energy use fixed and still do more with it in each passing year via efficiency improvements. Innovations bring new ideas to the market, spurring investment, market demand, etc. These are things that will not run dry. We have plenty of examples of fundamentally important resources in decline, only to be substituted or rendered obsolete by innovations in another direction.

Physicist: Yes, all these things happen, and will continue at some level. But I am not convinced that they represent limitless resources.

Economist: Do you think ingenuity has a limit—that the human mind itself is only so capable? That could be true, but we can’t credibly predict how close we might be to such a limit.

Physicist: That’s not really what I have in mind. Let’s take efficiency first. It is true that, over time, cars get better mileage, refrigerators use less energy, buildings are built more smartly to conserve energy, etc. The best examples tend to see factor-of-two improvements on a 35 year timeframe, translating to 2% per year. But many things are already as efficient as we can expect them to be. Electric motors are a good example, at 90% efficiency. It will always take 4184 Joules to heat a liter of water one degree Celsius. In the middle range, we have giant consumers of energy—like power plants—improving much more slowly, at 1% per year or less. And these middling things tend to be something like 30% efficient. How many more “doublings” are possible? If many of our devices were 0.01% efficient, I would be more enthusiastic about centuries of efficiency-based growth ahead of us. But we may only have one more doubling in us, taking less than a century to realize.

Economist: Okay, point taken. But there is more to efficiency than incremental improvement. There are also game-changers. Tele-conferencing instead of air travel. Laptop replaces desktop; iPhone replaces laptop, etc.—each far more energy frugal than the last. The internet is an example of an enabling innovation that changes the way we use energy.

Physicist: These are important examples, and I do expect some continuation along this line, but we still need to eat, and no activity can get away from energy use entirely. [semi-reluctant nod/bobble] Sure, there are lower-intensity activities, but nothing of economic value is completely free of energy.

Economist: Some things can get awfully close. Consider virtualization. Imagine that in the future, we could all own virtual mansions and have our every need satisfied: all by stimulative neurological trickery. We would stil need nutrition, but the energy required to experience a high-energy lifestyle would be relatively minor. This is an example of enabling technology that obviates the need to engage in energy-intensive activities. Want to spend the weekend in Paris? You can do it without getting out of your chair. [More like an IV-drip-equipped toilet than a chair, the physicist thinks.]

Physicist: I see. But this is still a finite expenditure of energy per person. Not only does it take energy to feed the person (today at a rate of 10 kilocalories of energy input per kilocalorie eaten, no less), but the virtual environment probably also requires a supercomputer—by today’s standards—for every virtual voyager. The supercomputer at UCSD consumes something like 5 MW of power. Granted, we can expect improvement on this end, but today’s supercomputer eats 50,000 times as much as a person does, so there is a big gulf to cross. I’ll take some convincing. Plus, not everyone will want to live this virtual existence.

Economist: Really? Who could refuse it? All your needs met and an extravagant lifestyle—what’s not to like? I hope I can live like that myself someday.

Physicist: Not me. I suspect many would prefer the smell of real flowers—complete with aphids and sneezing; the feel of real wind messing up their hair; even real rain, real bee-stings, and all the rest. You might be able to simulate all these things, but not everyone will want to live an artificial life. And as long as there are any holdouts, the plan of squeezing energy requirements to some arbitrarily low level fails. Not to mention meeting fixed bio-energy needs.

Act Three: Main Course

Physicist: But let’s leave the Matrix, and cut to the chase. Let’s imagine a world of steady population and steady energy use. I think we’ve both agreed on these physically-imposed parameters. If the flow of energy is fixed, but we posit continued economic growth, then GDP continues to grow while energy remains at a fixed scale. This means that energy—a physically-constrained resource, mind—must become arbitrarily cheap as GDP continues to grow and leave energy in the dust.

Economist: Yes, I think energy plays a diminishing role in the economy and becomes too cheap to worry about.

Physicist: Wow. Do you really believe that? A physically limited resource (read scarcity) that is fundamental to every economic activity becomes arbitrarily cheap? [turns attention to food on the plate, somewhat stunned]

Economist: [after pause to consider] Yes, I do believe that.

Physicist: Okay, so let’s be clear that we’re talking about the same thing. Energy today is roughly 10% of GDP. Let’s say we cap the physical amount available each year at some level, but allow GDP to keep growing. We need to ignore inflation as a nuisance in this case: if my 10 units of energy this year costs $10,000 out of my $100,000 income; then next year that same amount of energy costs $11,000 and I make $110,000—I want to ignore such an effect as “meaningless” inflation: the GDP “growth” in this sense is not real growth, but just a re-scaling of the value of money.

Economist: Agreed.

Physicist: Then in order to have real GDP growth on top of flat energy, the fractional cost of energy goes down relative to the GDP as a whole.

Economist: Correct.

Physicist: How far do you imagine this can go? Will energy get to 1% of GDP? 0.1%? Is there a limit?

Economist: There does not need to be. Energy may become of secondary importance in the economy of the future—like in the virtual world I illustrated.

Physicist: But if energy became arbitrarily cheap, someone could buy all of it, and suddenly the activities that comprise the economy would grind to a halt. Food would stop arriving at the plate without energy for purchase, so people would pay attention to this. Someone would be willing to pay more for it. Everyone would. There will be a floor to how low energy prices can go as a fraction of GDP.

Economist: That floor may be very low: much lower than the 5–10% we pay today.

Physicist: But is there a floor? How low are you willing to take it? 5%? 2%? 1%?

Economist: Let’s say 1%.

Physicist: So once our fixed annual energy costs 1% of GDP, the 99% remaining will find itself stuck. If it tries to grow, energy prices must grow in proportion and we have monetary inflation, but no real growth.

Economist: Well, I wouldn’t go that far. You can still have growth without increasing GDP.

Physicist: But it seems that you are now sold on the notion that the cost of energy would not naturally sink to arbitrarily low levels.

Economist: Yes, I have to retract that statement. If energy is indeed capped at a steady annual amount, then it is important enough to other economic activities that it would not be allowed to slip into economic obscurity.

Physicist: Even early economists like Adam Smith foresaw economic growth as a temporary phase lasting maybe a few hundred years, ultimately limited by land (which is where energy was obtained in that day). If humans are successful in the long term, it is clear that a steady-state economic theory will far outlive the transient growth-based economic frameworks of today. Forget Smith, Keynes, Friedman, and that lot. The economists who devise a functioning steady-state economic system stand to be remembered for a longer eternity than the growth dudes. [Economist stares into the distance as he contemplates this alluring thought.]

Act Four: Dessert

Economist: But I have to object to the statement that growth must stop once energy amount/price saturates. There will always be innovations that people are willing to purchase that do not require additional energy.

Physicist: Things will certainly change. By “steady-state,” I don’t mean static. Fads and fashions will always be part of what we do—we’re not about to stop being human. But I’m thinking more of a zero-sum game here. Fads come and go. Some fraction of GDP will always go toward the fad/innovation/gizmo of the day, but while one fad grows, another fades and withers. Innovation therefore will maintain a certain flow in the economy, but not necessarily growth.

Economist: Ah, but the key question is whether life 400 years from now is undeniably of higher quality than life today. Even if energy is fixed, and GDP is fixed once the cost of energy saturates at the lower bound, will quality of life continue to improve in objectively agreed-upon ways?

Physicist: I don’t know how objective such an assessment can be. Many today yearn for days past. Maybe this is borne of ignorance or romanticism over the past (1950′s often comes up). It may be really exciting to imagine living in Renaissance Europe, until a bucket of nightsoil hurled from a window splatters off the cobblestone and onto your breeches. In any case, what kind of universal, objective improvements might you imagine?

Economist: Well, for instance, look at this dessert, with its decorative syrup swirls on the plate. It is marvelous to behold.

Physicist: And tasty.

Economist: We value such desserts more than plain, unadorned varieties. In fact, we can imagine an equivalent dessert with equivalent ingredients, but the decorative syrup unceremoniously pooled off to one side. We value the decorated version more. And the chefs will continue to innovate. Imagine a preparation/presentation 400 years from now that would blow your mind—you never thought dessert could be made to look so amazing and taste so delectably good. People would line the streets to get hold of such a creation. No more energy, no more ingredients, yet of increased value to society. That’s a form of quality of life improvement, requiring no additional resources, and perhaps costing the same fraction of GDP, or income.

Physicist: I’m smiling because this reminds me of a related story. I was observing at Palomar Observatory with an amazing instrumentation guru named Keith who taught me much. Keith’s night lunch—prepared in the evening by the observatory kitchen and placed in a brown bag—was a tuna-fish sandwich in two parts: bread slices in a plastic baggie, and the tuna salad in a small plastic container (so the tuna would not make the bread soggy after hours in the bag). Keith plopped the tuna onto the bread in an inverted container-shaped lump, then put the other piece of bread on top without first spreading the tuna. It looked like a snake had just eaten a rat. Perplexed, I asked if he intended to spread the tuna before eating it. He looked at me quizzically (like Morpheus in the Matrix: “You think that’s air you’re breathing? Hmm.”), and said—memorably, “It all goes in the same place.”

My point is that the stunning presentation of desserts will not have universal value to society. It all goes in the same place, after all. [I’ll share a little-known secret. It’s hard to beat a Hostess Ding Dong for dessert. At 5% the cost of fancy desserts, it’s not clear how much value the fancy things add.]

After-Dinner Contemplations

The evening’s after-dinner keynote speech began, so we had to shelve the conversation. Reflecting on it, I kept thinking, “This should not have happened. A prominent economist should not have to walk back statements about the fundamental nature of growth when talking to a scientist with no formal economics training.” But as the evening progressed, the original space in which the economist roamed got painted smaller and smaller.

First, he had to acknowledge that energy may see physical limits. I don’t think that was part of his initial virtual mansion.

Next, the efficiency argument had to shift away from straight-up improvements to transformational technologies. Virtual reality played a prominent role in this line of argument.

Finally, even having accepted the limits to energy growth, he initially believed this would prove to be of little consequence to the greater economy. But he had to ultimately admit to a floor on energy price and therefore an end to traditional growth in GDP—against a backdrop fixed energy.

I got the sense that this economist’s view on growth met some serious challenges during the course of the meal. Maybe he was not putting forth the most coherent arguments that he could have made. But he was very sharp and by all measures seemed to be at the top of his game. I choose to interpret the episode as illuminating a blind spot in traditional economic thinking. There is too little acknowledgement of physical limits, and even the non-compliant nature of humans, who may make choices we might think to be irrational—just to remain independent and unencumbered.

I recently was motivated to read a real economics textbook: one written by people who understand and respect physical limitations. The book, called Ecological Economics, by Herman Daly and Joshua Farley, states in its Note to Instructors:

…we do not share the view of many of our economics colleagues that growth will solve the economic problem, that narrow self-interest is the only dependable human motive, that technology will always find a substitute for any depleted resource, that the market can efficiently allocate all types of goods, that free markets always lead to an equilibrium balancing supply and demand, or that the laws of thermodynamics are irrelevant to economics.

This is a book for me!


The conversation recreated here did challenge my own understanding as well. I spent the rest of the evening pondering the question: “Under a model in which GDP is fixed—under conditions of stable energy, stable population, steady-state economy: if we accumulate knowledge, improve the quality of life, and thus create an unambiguously more desirable world within which to live, doesn’t this constitute a form of economic growth?”

I had to concede that yes—it does. This often falls under the title of “development” rather than “growth.” I ran into the economist the next day and we continued the conversation, wrapping up loose ends that were cut short by the keynote speech. I related to him my still-forming position that yes, we can continue tweaking quality of life under a steady regime. I don’t think I ever would have explicitly thought otherwise, but I did not consider this to be a form of economic growth. One way to frame it is by asking if future people living in a steady-state economy—yet separated by 400 years—would always make the same, obvious trades? Would the future life be objectively better, even for the same energy, same GDP, same income, etc.? If the answer is yes, then the far-future person gets more for their money: more for their energy outlay. Can this continue indefinitely (thousands of years)? Perhaps. Will it be at the 2% per year level (factor of ten better every 100 years)? I doubt that.

So I can twist my head into thinking of quality of life development in an otherwise steady-state as being a form of indefinite growth. But it’s not your father’s growth. It’s not growing GDP, growing energy use, interest on bank accounts, loans, fractional reserve money, investment. It’s a whole different ballgame, folks. Of that, I am convinced. Big changes await us. An unrecognizable economy. The main lesson for me is that growth is not a “good quantum number,” as physicists will say: it’s not an invariant of our world. Cling to it at your own peril.

Note: This conversation is my contribution to a series at www.growthbusters.org honoring the 40th anniversary of the Limits to Growth study. You can explore the series here. Also see my previous reflection on the Limits to Growth work. You may also be interested in checking out and signing the Pledge to Think Small and consider organizing an Earth Day weekend house party screening of the GrowthBusters movie.

Read more [+]

Cliodinâmica e Psicohistória

Trilogia da Fundação – Isaac Asimov


Human cycles: History as science

Advocates of ‘cliodynamics’ say that they can use scientific methods to illuminate the past. But historians are not so sure.


Sometimes, history really does seem to repeat itself. After the US Civil War, for example, a wave of urban violence fuelled by ethnic and class resentment swept across the country, peaking in about 1870. Internal strife spiked again in around 1920, when race riots, workers’ strikes and a surge of anti-Communist feeling led many people to think that revolution was imminent. And in around 1970, unrest crested once more, with violent student demonstrations, political assassinations, riots and terrorism (see ‘Cycles of violence’).

To Peter Turchin, who studies population dynamics at the University of Connecticut in Storrs, the appearance of three peaks of political instability at roughly 50-year intervals is not a coincidence. For the past 15 years, Turchin has been taking the mathematical techniques that once allowed him to track predator–prey cycles in forest ecosystems, and applying them to human history. He has analysed historical records on economic activity, demographic trends and outbursts of violence in the United States, and has come to the conclusion that a new wave of internal strife is already on its way1. The peak should occur in about 2020, he says, and will probably be at least as high as the one in around 1970. “I hope it won’t be as bad as 1870,” he adds. Read more [+]

Estado minimo e eficiência econômica e Blade Runner

Eu aposto que se fizessem modelos de econofísica com Estado Minimo (neoliberalismo) competindo com Estados Médio (capitalismo de estado) e Estado Maximo (comunismo estatal), e botasse os caras para competir, venceria o Estado Médio.

Por que, afinal de contas, o Caminho do Meio (chinês?) está vencendo…

Falta apenas democratizar a China. A menos, é claro, que a Democracia Politica não seja economicamente eficiente. Se o critério maior for a eficiência econômica para se determinar a estrutura econômico-social (uma tese do Marxismo Vulgar), em vez do bem estar e liberdade humana ou da Biosfera, então a Democracia será superada pelo Estado Chinês (que, pelo que entendo, funciona bem no longo prazo…).

A Primavera Árabe, o Verão Londrino e o 2012 Mundial?

the physics arXiv blog

The Cause Of Riots And The Price of Food

Posted: 14 Aug 2011 09:10 PM PDT

If we don’t reverse the current trend in food prices, we’ve got until August 2013 before social unrest sweeps the planet, say complexity theorists

What causes riots? That’s not a question you would expect to have a simple answer.

But today, Marco Lagi and buddies at the New England Complex Systems Institute in Cambridge, say they’ve found a single factor that seems to trigger riots around the world.

This single factor is the price of food. Lagi and co say that when it rises above a certain threshold, social unrest sweeps the planet.

The evidence comes from two sources. The first is data gathered by the United Nations that plots the price of food against time, the so-called food price index of the Food and Agriculture Organisation of the UN. The second is the date of riots around the world, whatever their cause. Both these sources are plotted on the same graph above.

This clearly seems to show that when the food price index rises above a certain threshold, the result is trouble around the world.

This isn’t rocket science. It stands to reason that people become desperate when food is unobtainable. It’s often said that any society is three square meals from anarchy.

But what’s interesting about this analysis is that Lagi and co say that high food prices don’t necessarily trigger riots themselves, they simply create the conditions in which social unrest can flourish. “These observations are consistent with a hypothesis that high global food prices are a precipitating condition for social unrest,” say Lagi and co.

In other words, high food prices lead to a kind of tipping point when almost anything can trigger a riot, like a lighted match in a dry forest.

On 13 December last year, the group wrote to the US government pointing out that global food prices were about to cross the threshold they had identified. Four days later, Mohamed Bouazizi set himself on fire in Tunisia in protest at government policies, an event that triggered a wave of social unrest that continues to spread throughout the middle east today.

That leads to an obvious thought. If high food prices condition the world for social unrest, then reducing the prices should stabilise the planet.

But what can be done to reverse the increases. Lagi and co say that two main factors have driven the increase in the food price index. The first is traders speculating on the price of food, a problem that has been exacerbated in recent years by the deregulation of the commodities markets and the removal of trading limits for buyers and sellers.

The second is the conversion of corn into ethanol, a practice directly encouraged by subsidies.

Those are both factors that the western world and the US in particular could change.

Today, the food price index remains above the threshold but the long term trend is still below. But it is rising. Lagi and co say that if the trend continues, the index is likely to cross the threshold in August 2013.

If their model has the predictive power they suggest, when that happens, the world will become a tinderbox waiting for a match.

Ref: arxiv.org/abs/1108.2455: The Food Crises and Political Instability in North Africa and the Middle East

Copula Information, Guerras Meméticas, Polarização Social e Difusão de Inovação

Alguns artigos dos meu amigos Renato Vicente, Nestor Caticha e colaboradores. Imagino que colocaram o último, sobre culture wars, depois que o Serra apelou para táticas terroristas religiosas na internet. Será? 

The cultural war in America is between two sides that go by different names. The most common are Conservative vs. Liberal, Right vs. Left, and Republicans vs. Democrats.


Professor James Davison Hunter has written several books on the cultural war.  He uses the terms “orthodox” and “progressive” to decribe the two sides in his book, Culture Wars: The Struggle to Define America. He has chosen his words carefully to depict each side. “Orthodox” gives a feeling of respect for past, time-honored traditions. “Progressives” captures how liberals see themselves — optimistic, creative and making progress away from old-fashioned virtues and toward a brave new world with constantly changing rules and values.

The inside cover of his book says “Abortion, funding for the arts, women’s rights — the list of controversies that divide our nation runs long and each one cuts deep.  This book shows that these issues are not isolated from one another but are, in fact, part of a fabric of conflict which constitutes nothing short of a struggle over the meaning of America.”

“Culture Wars presents a riveting account of how Christian fundamentalists, Orthodox Jews, and conservative Catholics have joined forces in a fierce battle against their progressive counterparts — secularists, reform Jews, liberal Catholics and Protestants — as each struggles to gain control over such fields of conflict as the family, art, education, law and politics. Not since the Civil War has there been such fundamental disagreement over basic assumptions about truth, freedom, and our national identity.” The public debates “are topics of dispute at the corporate cocktail party and the factory cafeteria alike, in the high school civics classroom, in the church lounge after the weekly sermon, and at the kitchen table over the evening meal.  Few of us leave these discussions without ardently voicing our own opinions on the matter at hand.  Such passion is completely understandable.  These are, after all, discussions about what is fundamentally right and wrong about the world we live in — about what is ultimately good what is finally intolerable in our communities.”

Signatures of the neurocognitive basis of culture wars found in moral psychology data

segunda-feira, 31 de maio de 2010, 15:31:34 | Nestor CatichaIr para artigo inteiro
Moral Foundation Theory (MFT) states that groups of different observers may rely on partially dissimilar sets of moral foundations, thereby reaching different moral valuations on a subset of issues. With the introduction of functional imaging techniques, a wealth of new data on neurocognitive processes has rapidly mounted and it has become increasingly more evident that this type of data should provide an adequate basis for modeling social systems. In particular, it has been shown that there is a spectrum of cognitive styles with respect to the differential handling of novel or corroborating information. Furthermore this spectrum is correlated to political affiliation. Here we use methods of statistical mechanics to characterize the collective behavior of an agent-based model society whose inter individual interactions due to information exchange in the form of opinions, are in qualitative agreement with neurocognitive and psychological data. The main conclusion derived from the model is that the existence of diversity in the cognitive strategies yields different statistics for the sets of moral foundations and that these arise from the cognitive interactions of the agents. Thus a simple interacting agent model, whose interactions are in accord with empirical data about moral dynamics, presents statistical signatures consistent with those that characterize opinions of conservatives and liberals. The higher the difference in the treatment of novel and corroborating information the more agents correlate to liberals.

An information theoretic approach to statistical dependence: copula information

sábado, 21 de novembro de 2009, 19:41:35 | Rafael S. CalsaveriniIr para artigo inteiro
We discuss the connection between information and copula theories Read more [+]

Econofísica do bolsa-família

Dado que o Serra promete um 13o para o bolsa-família, e todo PSDBista enfatiza que o bolsa-familia é uma agregação das políticas socio-assistencialistas de FHC, imagino que nenhum Serrista deveria ser contra o bolsa-família, concordam?

Do ponto de vista científico, uma série de trabalhos de econofísica mostram que um programa de renda mínimia é o melhor meio de mudar o expoente da lei de Pareto de distribuição de renda. Ver este trabalho e as referências que ele cita:

arXiv:1007.0461 (July 2010)

How simple regulations can greatly reduce inequality

J. R. Iglesias

Programa de Pós-Graduaccão em Economia and Instituto de F’isica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil

Received. 03 July 2010 Last updated. 13 July 2010

Abstract. Many models of market dynamics make use of the idea of wealth exchanges among economic agents. A simple analogy compares the wealth in a society with the energy in a physical system, and the trade between agents to the energy exchange between molecules during collisions. However, while in physical systems the equipartition of energy is valid, in most exchange models for economic markets the system converges to a very unequal “condensed” state, where one or a few agents concentrate all the wealth of the society and the wide majority of agents shares zero or a very tiny fraction of the wealth. Here we present an exchange model where the goal is not only to avoid condensation but also to reduce the inequality; to carry out this objective the choice of interacting agents is not at random, but follows an extremal dynamics regulated by the wealth of the agent. The wealth of the agent with the minimum capital is changed at random and the difference between the ancient and the new wealth of this poorest agent is taken from other agents, so establishing a regulatory tool for wealth redistribution. We compare different redistribution processes and conclude that a drastic reduction of the inequality can be obtained with very simple regulations.

Categories. physics.soc-ph nlin.AO q-fin.TR

Subject. Physics and Society; Adaptation and Self-Organizing Systems; Trading and Market Microstructure

Comment. 7 pages, 7 figures

Dois pesos…

02 de outubro de 2010 | 0h 00

Leia a notícia

Comentários 395

Maria Rita Kehl – O Estado de S.Paulo

Este jornal teve uma atitude que considero digna: explicitou aos leitores que apoia o candidato Serra na presente eleição. Fica assim mais honesta a discussão que se faz em suas páginas. O debate eleitoral que nos conduzirá às urnas amanhã está acirrado. Eleitores se declaram exaustos e desiludidos com o vale-tudo que marcou a disputa pela Presidência da República. As campanhas, transformadas em espetáculo televisivo, não convencem mais ninguém. Apesar disso, alguma coisa importante está em jogo este ano. Parece até que temos luta de classes no Brasil: esta que muitos acreditam ter sido soterrada pelos últimos tijolos do Muro de Berlim. Na TV a briga é maquiada, mas na internet o jogo é duro.

Se o povão das chamadas classes D e E – os que vivem nos grotões perdidos do interior do Brasil – tivesse acesso à internet, talvez se revoltasse contra as inúmeras correntes de mensagens que desqualificam seus votos. O argumento já é familiar ao leitor: os votos dos pobres a favor da continuidade das políticas sociais implantadas durante oito anos de governo Lula não valem tanto quanto os nossos. Não são expressão consciente de vontade política. Teriam sido comprados ao preço do que parte da oposição chama de bolsa-esmola.

Uma dessas correntes chegou à minha caixa postal vinda de diversos destinatários. Reproduzia a denúncia feita por “uma prima” do autor, residente em Fortaleza. A denunciante, indignada com a indolência dos trabalhadores não qualificados de sua cidade, queixava-se de que ninguém mais queria ocupar a vaga de porteiro do prédio onde mora. Os candidatos naturais ao emprego preferiam viver na moleza, com o dinheiro da Bolsa-Família. Ora, essa. A que ponto chegamos. Não se fazem mais pés de chinelo como antigamente. Onde foram parar os verdadeiros humildes de quem o patronato cordial tanto gostava, capazes de trabalhar bem mais que as oito horas regulamentares por uma miséria? Sim, porque é curioso que ninguém tenha questionado o valor do salário oferecido pelo condomínio da capital cearense. A troca do emprego pela Bolsa-Família só seria vantajosa para os supostos espertalhões, preguiçosos e aproveitadores se o salário oferecido fosse inconstitucional: mais baixo do que metade do mínimo. R$ 200 é o valor máximo a que chega a soma de todos os benefícios do governo para quem tem mais de três filhos, com a condição de mantê-los na escola.

Outra denúncia indignada que corre pela internet é a de que na cidade do interior do Piauí onde vivem os parentes da empregada de algum paulistano, todos os moradores vivem do dinheiro dos programas do governo. Se for verdade, é estarrecedor imaginar do que viviam antes disso. Passava-se fome, na certa, como no assustador Garapa, filme de José Padilha. Passava-se fome todos os dias. Continuam pobres as famílias abaixo da classe C que hoje recebem a bolsa, somada ao dinheirinho de alguma aposentadoria. Só que agora comem. Alguns já conseguem até produzir e vender para outros que também começaram a comprar o que comer. O economista Paul Singer informa que, nas cidades pequenas, essa pouca entrada de dinheiro tem um efeito surpreendente sobre a economia local. A Bolsa-Família, acreditem se quiserem, proporciona as condições de consumo capazes de gerar empregos. O voto da turma da “esmolinha” é político e revela consciência de classe recém-adquirida.

O Brasil mudou nesse ponto. Mas ao contrário do que pensam os indignados da internet, mudou para melhor. Se até pouco tempo alguns empregadores costumavam contratar, por menos de um salário mínimo, pessoas sem alternativa de trabalho e sem consciência de seus direitos, hoje não é tão fácil encontrar quem aceite trabalhar nessas condições. Vale mais tentar a vida a partir da Bolsa-Família, que apesar de modesta, reduziu de 12% para 4,8% a faixa de população em estado de pobreza extrema. Será que o leitor paulistano tem ideia de quanto é preciso ser pobre, para sair dessa faixa por uma diferença de R$ 200? Quando o Estado começa a garantir alguns direitos mínimos à população, esta se politiza e passa a exigir que eles sejam cumpridos. Um amigo chamou esse efeito de “acumulação primitiva de democracia”.

Mas parece que o voto dessa gente ainda desperta o argumento de que os brasileiros, como na inesquecível observação de Pelé, não estão preparados para votar. Nem todos, é claro. Depois do segundo turno de 2006, o sociólogo Hélio Jaguaribe escreveu que os 60% de brasileiros que votaram em Lula teriam levado em conta apenas seus próprios interesses, enquanto os outros 40% de supostos eleitores instruídos pensavam nos interesses do País. Jaguaribe só não explicou como foi possível que o Brasil, dirigido pela elite instruída que se preocupava com os interesses de todos, tenha chegado ao terceiro milênio contando com 60% de sua população tão inculta a ponto de seu voto ser desqualificado como pouco republicano.

Agora que os mais pobres conseguiram levantar a cabeça acima da linha da mendicância e da dependência das relações de favor que sempre caracterizaram as políticas locais pelo interior do País, dizem que votar em causa própria não vale. Quando, pela primeira vez, os sem-cidadania conquistaram direitos mínimos que desejam preservar pela via democrática, parte dos cidadãos que se consideram classe A vem a público desqualificar a seriedade de seus votos.