CLC2026 OFFICIAL PROGRAM

Monday’s program took place at the Théâtre du Vieux-Colombier, in Saint-Germain-des-Prés. Founded in 1913 by Jacques Copeau and today one of the stages of the Comédie-Française, it gave the opening day an atmosphere no lecture hall could match. Tuesday’s sessions moved to the Callot building, one of the few university buildings in central Paris, and the home ground of Paris-Malaquais.

This year's welcome speeches also brought the society's publishing side to the stage. Telli Faez, Senior Publisher, Mechanical Engineering, Thermal & Fluids, Elsevier, and William Worek, Editor-in-Chief of International Communications in Heat and Mass Transfer, addressed participants at the opening, reminding everyone that the conference and the journal have grown together.

The keynote of the anniversary edition was delivered by Adrian Bejan, under the title “Diversity and Freedom in Nature and Society”, thirty years after the first publication of the law that gives the conference its name.

The Constructal Law Conference Award, first presented in 2024 and now in its third year, went to Stephen Perin, “for originality, independence, and surprising connections between air traffic systems, business, the Pyramids, and computation.” Congratulations, Stephen!

The anniversary year brought one more honor for the constructal society. Adrian Bejan has been awarded the 2026 Prigogine Medal. The University of Siena and the Wessex Institute established the medal in 2004 to honor the memory of Ilya Prigogine, Nobel laureate in chemistry, and it is awarded each year to a leading scientist working in the spirit of his ideas on non-equilibrium thermodynamics and the emergence of order. Thirty years after the Constructal Law was first published, the medal places its author in that line.

Great thanks to Lazaros Mavromatidis, Conference Chair, for steering a conference whose program had to be rebuilt days before it opened; to Christelle Lecoeur, Conference Administrator, who carried that building through in practice; to Jean-Baptiste de Froment, Director of Paris-Malaquais School of Architecture - PSL University, for supporting and hosting the constructal society; and to every speaker and participant who traveled to Paris and adapted to the new schedule.

The road ahead is already set. The 17th Constructal Law Conference (CLC2027) will be held on 22-24 September 2027 at Imperial College London, UK, and the 18th (CLC2028) will be hosted by Yildiz Technical University in Istanbul, Türkiye. We look forward to seeing the constructal society in both cities.

The conference page remains online at constructallaw.com/p/clc2026, and everything about the Constructal Society, past conferences, publications, and upcoming events can be found at constructallaw.com.

CLICK FOR THE CLC2026 PHOTO ALBUM

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His latest book, Diversity through Freedom (Springer, 2026), takes that same physics and points it at a very modern argument. The idea: diversity isn’t something you legislate into existence, it happens naturally when things (rivers, animals, people) are free to change shape in response to how they move. As Bejan turns 78 this year, the principle behind evolution turns 31. He calls it the Constructal Law. Turns out nature figured out flow way before anyone wrote a mission statement about it.

A serial rebel that help demystify the Thermal and Natural Sciences, Prof. Bejan flipped Second Law analysis to hunt down wasted energy instead of just balancing it, popularized scale analysis as a cost-effective method to skip partial differential equations and get straight to the physics, wrote the book on convection in porous media, then formalized the Constructal Law, the idea that rivers, lungs, and lightning branch the same way because that’s how flow evolves. He took it mainstream with Design in Nature, then pushed it into economics and society with Freedom and Evolution. Every time, he took a field comfortable with “that’s just how it’s done” and made it explain why.

Happy birthday, Adrian. Keep making the majority of one shine through the noise.

Introduction

The Constructal Law has a broad purview of applicability, spanning mechanical engineering^[1], physics^[2], thermodynamics^[3], biology^[4], and even geography^[5]. We believe that a school of thought centered on integrating the Constructal Law with economics and finance would serve as a nexus for further research, and as such, we are presenting here an outline for its development.

A recurring theme in the history of macroeconomic thought is that economic systems are flow systems. Capital flows toward return. Risk flows to where it is least priced. Information flows until it is arbitraged away. Notably, Irving Fisher in 1891 and Bill Phillips in 1949 went so far as to build water-based hydraulic computers to use as economic models. However, because the Constructal Law was not identified until 1996 and evolutionary economics has long-been at the fringe of mainstream economics, Constructal Theory is still nascently diffusing into economics and finance. Accordingly, we are aiming to shape a new school of economic thought in Constructal finance. Through this lens, the emergence of new financial institutions, such as exchanges, clearing houses, and central banks, can be thought of as economic evolutionary adaptations that reduce financial frictions and make flow more sustainable.

Much as financial panics have been occurring with a roughly decadal historic regularity, identifying their causes and devising mitigative policies remain contentious subjects in the fields of economic history and macroeconomics, especially when the nature of crashes evolves. For example, while the Panic of 1893 serves as one of many datapoints about the timelessness of financial contagions and cascade effects, that economic systems today could again be destabilized by a run on treasury gold reserves is implausible given that we have long departed from the gold standard. Likewise, because the 2008 financial crisis illuminated the vicious dangers of banks overleveraging while systemically underestimating asset risk, in its wake, the Basel III framework was developed.

In accordance with the Constructal Law, for an economic system to persist in time, it must evolve with freedom in such a way to increase the accessibility of monetary flows to the highest available risk-adjusted rate of return. When monetary flows are congested and the system is too constrained to reconfigure itself, financial crises can arise. Importantly, because financial frictions inhibit monetary flow, they are the underlying drivers of the evolutionary reconfiguration process. The history of monetary inventions can largely be understood through this lens: money itself was invented to circumvent the severe coincidence-of-wants friction of bartering, the replacement of the Bretton Woods system with floating exchange rates and fiat currency reduced frictions on government deficit spending, and more recently, the Covid-19 pandemic served as an inflection point for people to increasingly opt for contactless forms of payment as fumbling with cash became a transactional friction. Modelling financial frictions is key to stress testing economic systems. However, the complex adaptive nature of economies usually makes predicting their failures with any actionable precision a fool’s errand. Nevertheless, using Constructal Theory, we may be able to at least identify monetary flow chokepoints that will become a catalyst for system reconfigurations and characterize such processes.

Economic and Financial Flows

To rigorously apply the Constructal Law to a flow system, there are at least three key elements that need to be considered: 1) the material or essence of the flow, 2) the boundaries of the system, and 3) the degrees of freedom through which the system can evolve. Perhaps the most obvious type of flow in economics and finance is the flow of money, though information, trade, labor, capital, and risk are also often thought of as economic and financial flows. The boundaries of economic and financial flow systems can be physical, such as a nation’s borders, or nontangible, such as regulations imposed on banks to limit their leverage. Economies are complex adaptive systems, and so they usually contain numerous simultaneous flows and layers of boundaries that generate chaotic noise and feedback. The Constructal Law is most illustrative for evaluating tradeoffs between two or three degrees of freedom; each additional degree of freedom included makes analysis dimensionally more complicated. Good Constructal analysis, thus, requires both engineering and artistic judgment: “The drawing is the permanent record of the fleeting mental viewing. This is why…art and science are one.”^[6]

Evolution’s Sidelined Role in Economics

Economics is rife with different schools of thought. Some are major paradigms, both mainstream and broad in scope (e.g. New Neoclassical synthesis), while others more like specialized lenses polished to look at economic phenomena in a stylized way (e.g. Thermoeconomics). One (and perhaps the only) thing common to all schools of thought is that they were founded to give people new ways of thinking about phenomena.

The quantitative toolkit of economics has its roots predominantly in classical physics and engineering; however, economies function less like predictable, tamable machines and more like adaptive, evolving organisms. Evolutionary economics is a school of thought directed toward formulating economics through this latter analogy. Because biology and evolutionary theory offer a less sophisticated mathematical framework than physics and engineering, evolutionary economics has always been marginal, even if it curries significant sympathy from mainstream economists who are aware of the pitfalls the discipline has currently as a kind of quasi-science.

Reporting a detailed autopsy on evolutionary economics would be too much of a digression from the main subject of our piece here. Suffice it to say, breathing new life into evolutionary economics requires updating its somewhat outmoded palette of evolutionary concepts to include more quantitively operationalizable theories. We see the Constructal Law as one such theory, and so, our school of Constructal Finance may be thought of as a specialized spinoff of evolutionary economics.

Three Threads

Over an initial course of discussions about the Constructal Law and Finance that we had alongside T.J. Heyman, Bob Hansen, and Adrian Bejan, we have identified three threads of research to which our school of thought would be particularly suited. We welcome any collaborates to pursue these or contribute new threads.

1. Crises, Frictions, and Rhythms

Identifying the causes of chronic business cycles and acute financial panics has always been a core endeavor within economics. Some of the discipline’s most prominent studies that gained traction beyond academia have been extensive historical analyses concerning the long-run distortionary effects posed by rising levels of debt^[7], inflation^[8], and inequality^[9]. Considerable work has also been done to identify and model financial frictions that have more fast-acting distortionary effects. We see the Constructal Law as a framework for understanding the effects that such frictions have on the flow of investments and predicting ways in which economic systems could adaptively reconfigure themselves to restore access of capital to the highest risk-adjusted return. Accordingly, Constructal Finance should provide predictive insights about ways in which economies would evolve, though timing the evolution with meaningful precision would still be elusively futile. As a proof-of-concept, we will be presenting an evolutionary Constructal model of one type of banking friction at CLC2026 – more on this at the end.

2. Hierarchy, Access, and Real Assets

The emergence and growth of cities can be understood through three distinct frameworks: spatial economics^[10], power law scaling^[11], and Constructal Theory^[12]. Where the Constructal Law may provide complementarity rather than redundancy is in the study of real estate value as a measure of access of population flows. Through this lens, the boom-bust rhythm of property markets is the same rhythm that governs every other Constructal system operating under a fixed constraint. The decision to invest capital into real assets then weighs upon whether those assets are facilitating or constricting further population flow.

3. A Unifying Principle

Any student of the Constructal Law can attest to its power as a unifying principle for understanding phenomena that are otherwise thoroughly different. And for anyone new to Constructal Theory, a skim through any of the published proceedings of previous CLCs should be compelling. Last year’s conference, for instance, featured several talks that extended the domain of the Constructal Law beyond its established STEM applications, including understanding historical migration flows of the Jewish diaspora^[13] and studying the evolution of universities as systems conducting research flows^[14]. We anticipate that further developing the school of Constructal Finance will generate insights that carry over to other disciplines (indeed, one of us is also a theoretical biologist and currently working on a project concerning ATP and the evolution of bioenergetic currencies). Moreover, economics may also be on the receiving end of such cross-pollination, especially financial economics, which already has a proven crossover with thermodynamics via the Black-Scholes model and Fourier heat equation.

A Constructal Model of Financial Friction

We wanted to share the gist of our first proof-of-concept paper. Our model is inspired by the model of Gertler and Karadi (2011) as presented in Christiano and Ikeda (2013). The original model has a simple chain of monetary flows: depositors « mutual funds « banks « firms. The bankers face a frictional moral hazard of potentially spending subpar effort at finding quality investments, resulting in a lower rate of return to depositors. Because depositors cannot freely observe bankers’ behaviors, the risk of fiduciary shirking gets baked into the contract between the two parties, with the upshot being that bankers lose their residual claimancy to the investments. This, in turn, can induce them to spend less effort searching for good investments, which can trigger a financial downturn. The economic narrative underlying our model preserves much of the framework but shifts the friction source from the effort of the bankers to the supply of good investment opportunities, which are generally outnumbered by the population of bankers. Whereas in the traditional macroeconomic literature, a financial friction is simply a source of market inefficiency, in our Constructal model, it impels the financial system to reconfigure itself in order to maintain investment flow.

Conclusion

In a traditional interpretation of financial economics, crises are market failures that arise from frictions, which ideally get greased with patchwork policy to prevent their recurrence. In an evolutionary Constructal interpretation, such frictions serve as impetuses for market adaptations. Although they may be mitigated in the medium-run through policy, long-run evolvability is generally maximized by allowing markets more evolutionary degrees of freedom, which may get inadvertently curtailed by policy. Thus, in the Constructal interpretation, policy should be directed more at smoothing reconfiguration processes than at reducing the frictions themselves. As we continue to build this Constructal school of economic thought, a key idea to consider is whether the Constructal Law is not merely analogous to finance but constitutive of it. Capital conservation in structured finance echoes the First Law of Thermodynamics. Risk management and regulatory oversight echo the Second Law’s imposition of order on a system tending toward disorder. The evolution of financial institutions echoes the hierarchical, Constructal architecture that mature flow networks tend toward. Taken individually, each parallel is suggestive. Taken together, they invite the claim that financial structure is not merely describable in the language of flow physics but generated by it.

In Closing

We look forward to uncovering the unifying principles of Constructal Law and Finance — continuing to explore the connections that deepen our understanding and help us harness knowledge to advance economics and finance. Let the journey begin…

About the Authors

Michael Stockman

Michael Stockman is a Managing Partner at WMD Capital Partners, LLC, a real estate private equity partnership, and has been with the firm since 2015. Michael brings over 30 years of experience from senior roles in mortgage trading, global fixed income, capital markets, and risk management at leading institutions, primarily Goldman Sachs and UBS Investment Bank. Mr. Stockman has also been actively engaged in academia and service through leadership and advisory board roles at the Tuck School of Business at Dartmouth College and the University of Colorado. He holds an MBA from Dartmouth’s Tuck School of Business, a Master’s Degree in Mechanical Engineering from the University of Colorado, Boulder, and a Bachelor’s Degree in Mechanical Engineering from Union College, Schenectady, NY.

Albert Magnell

Albert Magnell is an evolutionary theorist working at the intersection of the life sciences and economics. He holds an M.Biochem. from the University of Oxford, an S.M. in biology from the Massachusetts Institute of Technology, an M.A. in economics from Duke University, and an M.Phil. in economics from the University of Oxford.

^[1] Bejan, Adrian, and Sylvie Lorente. Design with constructal theory. Hoboken, NJ, USA: John Wiley & Sons, 2008.

^[2] Ibid.

^[3] Ibid.

^[4] Bejan, Adrian, and J. Peder Zane. Design in nature: How the Constructal Law governs evolution in biology, physics, technology, and social organizations. Anchor, 2013.

^[5] Baciu, Dan C., Lily Wolf, Marcelo R. Errera, Vinicius Braz de Oliveira, and Umit Gunes. “Constructal thinking: Geospatial and temporal focal points of activity.” BioSystems (2026): 105784.

^[6] Bejan, Adrian. Time and beauty: Why time flies and beauty never dies. World Scientific, 2022.

^[7] Reinhart, Carmen M., and Kenneth S. Rogoff. This time is different: Eight centuries of financial folly. Princeton University Press, 2009.

^[8] Friedman, Milton, and Anna Jacobson Schwartz. A monetary history of the United States, 1867-1960. Princeton University Press, 2008.

^[9] Piketty, Thomas. Capital in the twenty-first century. Harvard University Press, 2014.

^[10] Fujita, Masahisa, Paul Krugman, and Anthony J. Venables. The spatial economy: Cities, regions, and international trade. The MIT press, 1999.

^[11] West, Geoffrey. Scale: The universal laws of life, growth, and death in organisms, cities, and companies. Penguin, 2018.

^[12] Bejan, Adrian. The physics of life: the evolution of everything. Macmillan, 2016.

^[13] Savitt, Samuel A., and Susan S. Savitt. “Constructal evolution of the Jewish diaspora” in Proceedings of the 15^th Constructal Law Conference (2025).

^[14] Gunes, Umit. “Analyzing research output: A data-driven approach” in Proceedings of the 15^th Constructal Law Conference (2025).

We are delighted to unveil the official program of the 16th Constructal Law Conference (CLC2026), to be held on 12–15 October 2026 in Paris, France, hosted by École nationale supérieure d’architecture Paris-Malaquais – PSL, across the historic spaces of the Beaux-Arts de Paris and Université Paris Sciences et Lettres.

CLC2026 OFFICIAL PROGRAM

Under the theme Design in Nature — The Evolution of Designs, the program brings together four days of lectures, scientific sessions, awards, posters, workshops, and research encounters, gathering scientists, engineers, architects, and scholars from across the natural and social sciences.

CLC2026 will explore how living and non-living flow systems acquire and evolve their configurations through time—from organisms, rivers, and energy systems to buildings, cities, technologies, information, and societies. At the heart of the program lies a fundamental question: how does the world acquire form through flow?

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Ultimately, batteries are thermodynamic devices. Materials science determines what reactions are possible, and electrochemistry describes how charge is transported and stored, but neither explains how much useful work is destroyed in the process, nor how much additional work should be spent to preserve it. Every watt dissipated, every temperature gradient, every pressure drop and every side reaction contributes to the degradation of exergy—the capacity of the battery to perform useful work. For this reason, battery management is fundamentally a thermodynamic problem: one of distributing limited cooling resources in a way that minimizes irreversibility over the lifetime of the system.

The first paper (Ignuta-Ciuncanu, Marinescu & Martinez-Botas), published in the International Journal of Heat and Mass Transfer, introduces a hierarchical generative design framework for battery packs using phase change materials. Cooling architectures are allowed to morph freely across scales: from high-conductivity inserts surrounding individual cells, to functionally graded module assemblies, and finally to battery pack layouts treated as evolving porous media. The resulting designs reduce hotspot temperatures by up to 60% while requiring only a fraction of the pumping power demanded by uniform configurations.

In my second paper (Ignuta-Ciuncanu), recently published in International Communications in Heat and Mass Transfer, I answer a different question: how much cooling should a battery receive? Using entropy generation minimization, I show that neither fixed cooling rates nor fixed battery temperatures are thermodynamically optimal. Instead, the cooling effort should evolve together with the battery itself. As cells age, they require progressively greater access to the cooling stream, in agreement with the Constructal Law.

Together, these studies suggest a new direction for battery thermal management. The first addresses the evolution of form—how cooling structures should be configured in space. The second addresses the evolution of rhythm—how cooling intensity should evolve in time.

One changes geometry. The other changes control.

Both point toward the same conclusion: that freedom to morph is freedom to cool (wisely) and persist in time.

Perhaps this is how the next generation of battery thermal management systems will be designed: not as fixed objects, but as architectures free to change, guided by physics and informed by computation. In one word: construcally.

The first channel is the hardest. The current that crosses over a new threshold into untouched ground bears the full weight of the resistance—no one has loosened the earth ahead of it.

Adrian Bejan began carving that first channel nearly thirty years ago, and has been deepening it since: bolstering the law across disciplines, across skepticism great and small, across the quiet weight of being the one who saw it first. He tells his students, “Your mother only made one of you.”

Adrian expounds on this in his latest book Diversity Through Freedom: “You are an individual, irrepressible, and irreplaceable. Nobody is like you. You are an important person, the one-of-a-kind. Seek freedom, it’s all right.”

What happens when one lone creative does seek freedom and trusts that his ideas are important? When one pioneer chooses to cut the channel and forge the pathway?

The Constructal Law tells us that the pathway will branch — a river reaches the sea not as one line, but as a diverse configuration of flows working as one.

The diverse research and strengths of the Constructal Community bring the movement to life. From Mary Bejan and Terry Bristol for their presence and grounding, to Umit Güneş and Elsie Gothman for their dedication to organizing and circulating the research — together, this community has been a true expression of an evolving living system, working with its natural diversity to spread new ideas across the globe. (And we can thank Dan Baciu for the maps and research to visualize it!)

I am one who now enjoys the fruit of that path-paving.

I’m Christine Bizzell, a strengths practitioner, independent researcher, and founder of Canon Collaborative in Tulsa, Oklahoma. For six years I’ve been researching how the Constructal Law maps onto human experience. It was 2020 when I sent a cold email to Bejan, whose work with Marcelo Errera on wealth inequality had sparked a serious pull toward research for the first time in my life. (I’m telling more of that story over at my blog, Patterns in the Wild.)

With Adrian’s encouragement, I presented at my first Constructal Law Conference in Torino in 2023. With a real hypothesis and a real fear of public speaking, I presented early before the courage could sink into the comfy red cushions.

12th Constructal Conference 2023, Energy Center of Torino

Hosted by Umberto Lucia and Giulia Grisolia of Politecnico di Torino, Italy

What I remember most are the smiles, the warm applause, and thoughtful questions from Mircea Scurtu, Adrian Pet’rescu’, and Miguel Panão. And Adrian, who warmly congratulated me on my debut presentation while assuring me this was only the beginning (this guy really can predict the future, it seems). My idea felt seen by a room of world-class scientists.

In Bucharest the next year, I understood that this was no longer a group I was visiting but a community I belonged to—a room full of colleagues laying new pathways themselves. I am in the greatest company.

14th Constructal Conference Dinner 2024, Bucharest, Romania

Standing from left to right: George Stanescu, Adrian Bejan, Marcelo Errera, and Dan Baciu.

As Bejan shares, we have an opportunity to speed the process of creating design to better serve society—as individuals, and as a whole. As this community comes together for the 30th anniversary of the Constructal Law and 16th conference in Paris, we celebrate the countless pioneers among us—made possible by our first pathway paver, Adrian Bejan, whose own words hold the invitation: “The holistic view is the key to understanding design in nature and predicting the future.”

At the 15th Conference in Miami, I initiated the Constructal Strength Ecosystem—an invitation for this community to map its diverse strengths together, and to explore what becomes possible when an empowered community unites its strength toward this shared purpose.

The Constructal Strength Ecosystem is now live: canoncollaborative.com/constructal-strength

15th Constructal Law Conference, Florida International University, Miami — with Adrian Bejan: Constructal Pioneer and Chief Jokester

In this lecture, Adrian Bejan returns to the model he built earlier for movers, where a vehicle is treated as the same thing as an animal, the motor stands for muscle mass and the fuel stands for the food carried in the body. He first recalls the two organ model, in which the mass of the mover is dominated by the fuel load and the motor, and shows how the balance between them is settled by the constructal law. He then makes the model heavier by adding the dead weight of the chassis, the seats, the roof and the occupants, and finds that the conclusion survives unchanged. Finally he divides life travel by speed to arrive at lifetime, and explains why the bigger animals and vehicles live longer.

• A vehicle is an animal: Bejan asks the audience to treat vehicles and animals as the same kind of mover, where the motor means muscle mass and the fuel means the food in the stomach, or the grains a bird gathers in the sack under its beak. This is why the same reasoning covers runners, birds and fish as well as land vehicles, air vehicles and ships.

• Two organs and one degree of freedom: In the earlier model the mass of the mover was assumed to be dominated by two organs, the fuel load and the motor, with the total mass held fixed, so the only freedom left is the relative size of these two parts. The burned fuel delivers its heating value as a heat input, the motor turns part of it into work, and that efficiency is greater when the motor is bigger, which is the predicted phenomenon of economies of scale.

• Movement is what the design maximizes: Bejan calls the product of the body mass and the travel movement, and according to the constructal law an object that has the freedom to change will change in the direction that makes this quantity greater. Working out that balance gives the motor and the fuel as fixed fractions of the total mass, so the more muscular birds are the ones flying from Alaska to New Zealand on larger stores of fat, and the bigger movers travel farther.

• Adding the dead weight does not change the answer: The new step in this lecture is a three part model, where the chassis, the seats, the roof, the occupants and the suitcases are counted as dead weight and taken as a fixed fraction of the total size, the way a shipyard states the size of a cargo ship in tons of dead weight, the shell alone. The longer algebra ends at exactly the same conclusion, which is what Bejan means when he calls a result robust.

• Lifetime is life travel divided by speed: Since the bigger movers travel farther and also move faster, whether they are runners, birds, fish or land, air and maritime vehicles, the two effects combine into a lifetime that grows with body size. The exponent that falls out of this back of the envelope sketch is comparable with one half or two thirds.

• The data were waiting in the zoology books: Only after the sketch is finished does Bejan open the books of zoology, which are full of plots of lifetime versus body size, and the dots line up along a power law with this kind of exponent. Those books report the exponent without explaining it, and his point is that the exponent is the real question, because everybody knows that the bigger live longer but very few question what everybody knows.

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In this video, Adrian Bejan takes on turbulence, a phenomenon he says people treat as a statement of admitting defeat, and explains it through the life of a single eddy, a rolling blob of water rolling in water, the fluid equivalent of the rolling stone. Starting from a jet discharged into a swimming pool, he shows how eddies are born where moving water meets still water, how friction with the surroundings slows each eddy until it fades away, and why the bigger eddies live longer, travel farther, and complete more turns before disappearing. He closes by arguing that turbulence is no longer an enigma, and that it is time to close the book and move on.

• Where eddies come from. A jet discharged into a pool spreads predictably as a cone, but a closer look reveals a meandering flow that thickens and travels forward like a wave. Eddies have to form because the moving water interacts with the surrounding water that is not moving.

• Every eddy lives and dies. Friction between the rolling blob and its slower surroundings retards its turning, making it slower and slower as it travels downstream. Eventually the eddy becomes indistinguishable from its surroundings, which means it dies.

• A story about rolling stones. As a junior at MIT, Bejan took a psychology course whose professor, opposed to students experimenting with LSD, ran a controlled experiment asking a sober student and a student who was high the same question: what happens to a rolling stone? The high student answered, do not throw rolling stones into a glass house because they gather no moss, two sayings interbred into nonsense, and the lesson is simple, do not play with your brain.

• Bigger live longer and travel farther. By comparing an eddy’s inventory of kinetic energy with the rate at which friction dissipates it, Bejan predicts that bigger eddies should live longer and travel farther. In a population of many sizes, this predicts a diversity of lifetimes, a few long-lived movers among many short-lived ones, and those words apply to every diverse group of movers.

• The number of rolls is set at birth. Every roll of an eddy is like the tick of a clock, and the number of rolls until death is dictated from the eddy’s birth. Bigger and faster-rolling eddies make more turns before they disappear.

• The birth of turbulence has a threshold. Each eddy’s size and rotational speed define its own identity, what Bejan calls the local Reynolds number, like the brand name of a particular eddy. When this number reaches roughly one hundred, eddies are born and the flow shifts from laminar to turbulent, and below that threshold no eddy appears.

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We are delighted to announce the 17th Constructal Law Conference (CLC2027), to be held on 22-24 September 2027 at Imperial College London, UK. Under the theme Power, Structure and Mobility, CLC2027 will bring together scientists, engineers, architects, and scholars from across the natural and social sciences to explore how flow systems, living and non-living, evolve their configurations to gain access, generate power, and move more easily, with Freedom. Building on the momentum of recent conferences in Turin (CLC2023), Bucharest (CLC2024), Miami (CLC2025), and Paris (CLC2026), we look forward to welcoming you to London.

In this video, Adrian Bejan asks why bigger things live longer, a pattern long noticed in animals but never predicted from physics. He argues that life and travel are really the same idea, so a rule that works for animals should work for anything that moves, from vehicles and rivers to winds and rolling stones. Using a single rolling stone that slowly comes to a stop, he shows how its kinetic energy, worn away by friction, sets both how far it travels and how long it lasts. He then asks how many rolls a stone makes before stopping, and uses the constructal law to explain why moving bodies, from eroding rocks to the human-made wheel, evolve toward easier rolling.

• Why the bigger live longer. Bejan starts from a trend in zoology, sometimes called animal design, that bigger animals live longer, the same way big dogs outlive tiny ones. His aim is not just to describe this pattern but to predict it, since describing something is not the same as explaining why it must happen.

• Life and travel are the same thing. A large river carries water far and lasts a long time, while milk spilled on the kitchen floor goes nowhere and is gone in moments. Because moving and living are tied together, the same rule should hold for animals, vehicles, rivers, winds, and rolling stones alike.

• A rolling stone tells the story. A stone hurtling downhill carries kinetic energy that friction slowly wears away until it stops, having covered a certain distance over a certain lifetime. From this single balance, Bejan predicts that more initial speed buys both a longer journey and a longer life.

• Lifespan grows with the square root of travel. A surprising result is that lifetime rises only with the square root of the distance covered. As Bejan puts it, moving farther when you are old does not make you live longer.

• Why stones become round. Counting how many times a stone rolls before stopping gives a simple answer, few rolls for rough shapes and many more for smooth ones, just as a ball bearing rolls far more freely than a jagged rock. The constructal law predicts that a moving stone keeps changing toward less friction, becoming rounder rather than breaking apart.

• The same pull toward easier rolling. This drive toward smoother movement runs from eroding rocks to rivers cutting their channels, and even to the human biped, which Bejan pictures as a wheel with only two spokes. About 10,000 years ago the human-made wheel appeared and evolved from solid disks toward spoked forms, following the very same direction.

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In this video, Adrian Bejan turns the S-curve into a lesson about innovation. He explains that anything useful spreads in the same S shape, growing slowly, then quickly, then slowly again, until it reaches a plateau where the maker runs into trouble. The way out, he argues, is to replace the old with something new before the curve flattens, thereby launching a fresh S-curve and keeping the company alive. He illustrates this with Apple’s run of iPhone models, the rise of maritime technology in Western Europe, and the link between wealth, movement, and freedom.

• Why things spread. Anything that spreads, from a news item to the latest iPhone model, does so because it is useful and becomes attached to or adopted by a person. Bejan notes that none of us is a “naked animal” anymore, since that picture disappeared when we adopted fire.

• The maker’s problem. The same S-curve that rewards everyone who adopts a new technology leaves the manufacturer in trouble once growth reaches the plateau. The question then becomes how to make the curve steeper and keep the product spreading.

• Innovation is replacement. Bejan’s answer is to replace something old with something new, which is what innovation means. Drawing on the constructal law, he says you need the freedom to redraw the picture, sending the invasion in new directions rather than waiting for slow consolidation.

• The rhythm of new models. With the iPhone, marketing teams learn to detect the inflection point of each curve and launch a new model before the old one flattens. Each launch starts a fresh S-curve of income, and that rhythm has carried Apple through some sixteen models.

• Innovation is not spread evenly. Maritime technology, including the compass, the telescope, and maps, developed in Western Europe and spread across the oceans from there. Even the name “Americas” comes from a Florentine map maker, Amerigo, a reminder that it pays to be on the map.

• Wealth, movement, and freedom. Two graphs in the lecture show that wealth measured as GDP rises with movement, and that movement rises with economic freedom. Quoting Cicero, Bejan defines freedom as the power to live as one wishes, which to him means the power to make the changes that are good for you.

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In this video, Adrian Bejan explains the logistics S-curve, the universal shape that describes how almost anything spreads or is collected over time. He traces the word “logistics” back to military engineering rather than philosophy, argues that the “exponential growth” people invoke for viral phenomena is actually the wrong word, and then shows how a simple two-dimensional conduction model reproduces the S-curve through two stages he calls invasion and consolidation. He ties the whole idea to the German blitzkrieg through France and even to rainwater spreading across the ground.

• Where “logistics” comes from. Bejan opens with Napoleon, who understood that an army “marches on its belly” and needs food and lodging to keep moving. That need for lodging from stop to stop is the origin of the word logistics, meaning military engineering, not logic or philosophy.

• The S-curve is universal. Anything that spreads or is collected grows slowly, then fast, then slowly again, tracing the same S shape that you cannot defeat. Bejan’s recent contribution was not just to observe this curve but to predict it.

• “Exponential” is a misnomer. People call the steep early part of viral growth exponential, but a true exponential curve starts at minus infinity and keeps climbing forever. Since nothing in nature starts before the Big Bang, Bejan says that calling real growth exponential forgets your high school mathematics.

• Invasion then consolidation. In his model, a hot blade first cuts long and fast into a cooler square, then grows across it like a finger, producing the convex early rise. Once it reaches the far wall, the heat spreads sideways more slowly to fill the rest, the concave tail, which are the two phases he calls invasion and consolidation.

• A wartime newsreel made it click. The idea came from a Hollywood newsreel of Germany’s blitzkrieg into France, which bypassed France’s fortified eastern frontier by marching through Belgium. Tanks raced down the highway to Paris while trucks behind them spread sideways to protect the channel, an invasion followed by consolidation, exactly as in his model.

• The same pattern is everywhere. Rainwater falling on the ground first runs as a rivulet, then diffuses laterally and turns the patch into mud or swamp. The S-curve, Bejan argues, governs everything that fills a territory in time.

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At the heart of the book’s scientific framework is the counterintuitive revelation that “perfection is the enemy of evolution” (p. 23). Bejan explains how nature does not strive for a singular, frozen state of flawless design but instead keeps what works, allowing life and movement to flourish in a “broadband of slightly imperfect designs” (p. 3). Through clear, mathematics-free illustrations of convex performance curves, Bejan shows that a vast multitude of diverse shapes and rhythms can achieve nearly the same performance as a theoretically perfect design. This fundamental principle dictates how an immense diversity of solutions emerges from the freedom to be slightly imperfect, ensuring resilience and progress in everything from the layout of airport concourses to the architecture of city streets.

Bejan masterfully applies this physics lens to human and animal movement, illustrating how elite performance naturally gives rise to diverse physical forms. He explores the divergent evolution of athletic body types, demonstrating through physics why the fastest sprinters tend to have a higher center of mass, while the fastest swimmers have a lower one. These insights not only unify the study of animal locomotion and human sports but also highlight that natural hierarchies of merit are born from freedom and competition. Furthermore, Bejan challenges the narrow focus on convergent evolution by showing how divergent evolution operates simultaneously, as in the distinct cross-sectional shapes of fish compared to those of aquatic mammals, thereby proving that nature actively generates endless variety to optimize flow and heat retention.

The book moves seamlessly from the natural world to human institutions, offering a rigorous defense of the merit system and the solitary thinker. Examining the world university system, Bejan reveals that institutional prestige and rankings are not the result of artificially imposed diversity or sheer size, but rather the natural byproduct of groundbreaking ideas generated by brilliant individuals. He vigorously dismantles the contemporary push for the “collectivization of research” (p. 136), warning that monumental ideas originate in the mind of the solitary investigator, not within the confines of groupthink tanks or bureaucratic task forces. By defending the “majority of one” (p. 15), Bejan inspires readers to value the creator who, like a beautiful flower, attracts a diverse crowd of followers.

Perhaps the most gripping and deeply personal aspect of Diversity Through Freedom is Bejan’s critique of what he terms “unnatural diversity.” (p. 137) Drawing on his harrowing childhood experiences under communism in Romania, he draws striking parallels between modern diversity, equity, and inclusion (DEI) policies and the oppressive class-struggle tactics of the Soviet-era Red Terror. Bejan uses the poignant metaphor of a man walking a dog on a leash to illustrate the built-in inefficiency and suffering caused by collectivism: When forced to move at a dictated, uniform speed, both the man and dog are deprived of their natural, most economical rhythms. He argues that policies aimed at artificially engineering equality of outcome restrict human potential and are inherently destined to fade away because they run counter to the natural laws of evolution.

Diversity through Freedom is an empowering, holistic manifesto for liberty, common sense, and the unconquerable human spirit. Bejan successfully connects disparate phenomena, from the meandering of rivers and the rhythm of breathing to the cyclical nature of economic growth and the hierarchy of universities, under one elegant unifying principle. He challenges readers to reject ideological jargon, to ask difficult questions, and to recognize that society is at its healthiest when individuals are free to associate, compete, and evolve on their own terms. For anyone seeking a scientifically grounded and profoundly liberating understanding of how the world truly works, Bejan’s ultimate advice resonates clearly: “If you want diversity, give the population freedom, not the leash.” (p. 155).

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16th Constructal Law Conference (CLC2026)

🗓️ 12-15 October 2026, Paris-Malaquais School of Architecture-PSL (Paris Sciences et Lettres) University, Paris, France

Deadlines

• Extended Abstract Submission: June 3, 2026

• Extended Abstract Acceptance: June 20, 2026

• Registration Deadline: June 30, 2026

Accepted extended abstracts will be presented as oral presentations or posters.

Submit Your Extended Abstract

Registration Fee

• Full: €400

• Student: €150

The registration fee covers admission to all conference sessions and coffee breaks. However, lunches and dinners are not included in this fee.

Contact: info@constructallaw.com

More Information about CLC2026

In this video, Adrian Bejan describes design and evolution in time as rhythm or frequency, and adds two examples, defrosting a refrigerator and the logistics S-curve of spreading and collecting. He explains that defrosting is a rhythmic life of the appliance, with on operation and off operation, and that heat transfer and timing matter in the kitchen. He sketches the refrigerator as a flow system with room temperature, insulation, the beer place, and the evaporator at T minimum, where a layer of frost grows in time with thickness delta. He connects the heat leak Q, power W, and the refrigeration load to the cycle with durations T1 and T2, and asks how long the machine should run before the buildup becomes a thermal resistance. He also links this to Carnot efficiency, second-law efficiency, a short history of refrigeration, George Claude, and John Gori.

• Bejan frames the examples as designs that manifest as rhythm, with diversity in the optimized rhythm and frequency. He treats defrosting as a repeating cycle that you can recognize from spending time in the kitchen.

• He draws temperature levels from room temperature through the insulation to the beer place, then down to the evaporator at Tmin. He says the frost layer forms on the coldest surface because air containing water vapor is mixed with it.

• Bejan describes a heat leak, Q, that steadily penetrates when the motor is working and stops during defrosting. He defines the rhythm with T1 for the operation and T2 for defrosting, and focuses on the degree of freedom called T1.

• He explains that the delta increases over time and acts as a thermal resistance, so Q decreases as the ice layer accumulates. He notes diffusion processes are effective early, not late, and that a resistance generates heat to melt the water on the evaporator surface during T2.

• Bejan connects the analysis to Carnot efficiency and second-law efficiency, and says that refrigeration means repeated cooling because heat leaks keep leaking. He adds history about George Claude and an Otch power plant, and says the first refrigeration machine was built by an American dentist, John Gorrie, in Apalachicola, Florida.

16th Constructal Law Conference (CLC2026)

🗓️ 12-15 October 2026, Paris-Malaquais School of Architecture-PSL (Paris Sciences et Lettres) University, Paris, France

Deadlines

• Extended Abstract Submission: May 15, 2026

• Extended Abstract Acceptance: May 31, 2026

• Registration Deadline: June 30, 2026

Accepted abstracts will be presented as oral presentations or posters.

Submit Your Extended Abstract

Registration Fee

• Full: €400

• Student: €150

The registration fee covers admission to all conference sessions and coffee breaks. However, lunches and dinners are not included in this fee.

Contact: info@constructallaw.com

More Information about CLC2026

In this video, Adrian Bejan discusses a celebration at Duke and uses 7 slides to give a brief overview of his work. He begins with acknowledgments to Mary and their children, and he explains how two photographs make one point about footprints, the leopard, the giraffe, and the stability of quadripeds on the ground. He describes a career spanning more than four decades and says he enjoyed the freedom of a university professor, surrounded by inquisitive, bright students who appreciated learning. He recalls his start at MIT in thermodynamics and cryogenics, the difficult time getting a position, rejections, and how a book was published, which led to entropy generation minimization and textbooks in thermodynamics and heat transfer. He says what really matters is configuration, and he connects this to convection, freedom of the flow architecture, and a line of design science books. He ends with a punchline about a school of thought associated with Duke, the primordial presence of the idea before observation, and conferences from Duke to Paris and London.

• Bejan shows footprints of a leopard and says the rear foot touches the spot left by the front paw on the same side of the body. He says the giraffe photograph shows the same thing, and he connects it to extreme stability per unit weight of design.

• He says the recipe for an individual's happy and creative life is freedom and humility, surrounded by inquisitive, bright students appreciative of learning. He points to the Duke student who comes voluntarily to be shaped in life.

• Bejan describes the book cover as an accident from Africa, with an Egyptian goose on a branch, which he recognized as Adrian. He calls this an individual investigator standing on dead wood with infinite freedom to the blue sky of ideas.

• He recalls training at MIT and work in cryogenics, then a postdoc in Berkeley, and being hired at the University of Colorado. He says a book led to entropy generation minimization, and he connects thermodynamics and heat transfer to configuration and convection.

• Bejan says this kind of thinking represents a school of thought associated with Duke and calls it thermodynamics of 2026, tied to design in nature or constructal law. He says the idea is the fastest and cheapest investigation method, and he mentions the 16th Constructal Law Conference in Paris and the next year at Imperial College in London.

In this video, Adrian Bejan describes the design of the ice maker in a domestic refrigerator, where water freezes on a refrigerated surface called an evaporator, forming a layer of ice whose thickness increases over time, eventually reaching a point where it stops growing rapidly. He explains that the ice maker must then remove the manufactured ice to clean the surface, so the process repeats as a cycle with two time scales: a freezing time and a surface renewal time. He treats the surface renewal time as a known constant given by engineers and focuses on selecting the freezing time as the degree of freedom. The purpose is to maximize the time-averaged rate of ice production, which depends on how much ice is produced before removal and on the full cycle time. He connects this trade-off to familiar designs from domestic life to animal design and industry, where surfaces must be cleaned rhythmically to maintain high performance.

• The heart of ice making is a cold, refrigerated surface where water at the freezing point accumulates a layer of ice. Over time, the process runs out of zip because the layer no longer grows quickly, so the surface must be cleaned.

• Ice removal is a second time interval that renews the surface, and designs like ice trays with little cubicle alvoli help remove a whole bunch at once. This surface renewal time is treated as a constant, assumed to be known.

• The object of the game is to determine the freezing time as the degree of freedom selected rationally. The purpose is to maximize the time-averaged rate of ice production over the cycle, including freezing and surface renewal.

• The trade-off has two extremes: short freezing time on one side and long freezing time on the other. High values occur when the freezing time is determined by the time required to remove or clean the surface, which is good news for mechanical methods of scraping ice off.

• The same idea appears in the windshield wiper that cleans the window and in the eyelids that lubricate and clean the eyeball rhythmically. He also points to heat exchangers whose ducts get clogged by debris or gunk called scale, like plaque on teeth, and to the cost of shutting down a power plant to clean the tubes internally.

• Bejan starts from the idea of predicting the evolution of design and shifts from design in space to design in time. He connects this to rhythmic functioning in the body and the daily cycle.

• He frames respiration as a problem of posing the right questions, especially why inhaling time t1 equals exhaling time t2. He also links the same type of solution to heartbeating.

• Bejan models inhaling as atmospheric air entering the trachea and increasing the thorax volume by capital V, driven by a partial vacuum and limited by a global resistance R. He uses a pressure difference proportional to R and a velocity to an exponent n, and writes conservation of mass for the inflow and the accumulated air.

• He models exhaling as the thorax volume shrinking, indicated by a capital V, with an excess pressure delta p2, flowing out through the same resistance and cross-section, with an average velocity u2. He then computes work as the integral of p dv over the two parts and expresses average power in terms of V, af, and the time intervals.

• Bejan introduces alveoli and diffusion, where oxygen transfer scales with the square root of time and becomes inefficient, leading to intermittency and surface renewal through finite inhaling followed by exhaling. With a fixed oxygen requirement per unit time K, he minimizes average power and obtains the result that t1 and t2 are nearly equal, and higher K corresponds to shorter times and frequent breathing during running.

In this video, Adrian Bejan explains how the Atlanta airport story and a question at the 2009 ASHRAE congress led him from the golden ratio, or divine proportion, as a popular observation to a brief explanation of why it happens. He connects what people like in paintings, facades, the laptop screen, and other rectangles to how the two eyes scan an image with saccades, taking snapshots at 5 per second across the flat field of vision. He describes scanning horizontally and up and down, and considers the best shape to be the one that lets the eyes scan the whole area as quickly as possible, because fast scanning helps you grasp the meaning of a message and move on. He then uses the binoculars drawing, with two discs and their intersection, to argue that vertical and horizontal scanning differ because the eyes move upward in parallel but horizontally in series. He ends by tying well-proportioned and complex rectangles stacked on rectangles, and by saying eyes and ears sit on the horizontal because the world is flat, and because fast scanning and fast understanding are useful.

• Adrian Bejan says the Atlanta airport story first appeared in his 2000 book and was presented at the 2009 ASHRAE Congress. A participant said the drawing looked like the golden ratio, and Adrian Bejan said he figured out how to predict it and why it happens.

• Bejan describes two eyes that jiggle with saccades, taking snapshots at 5 per second as they scan the field of vision. He says the shape matters because scanning fast helps you understand fast, and that is useful.

• He treats the image as H and L, with scanning times along the horizontal and vertical axes, and he seeks the minimum total time. He says the fastest shape depends on the scanning speeds.

• Bejan uses binoculars and the intersection of two discs to compare how the eyes sweep vertically and horizontally. He gets an order-of-magnitude ratio and links it back to the rectangles people like.

• He connects the Renaissance and Uklid to the 618 dot dot dot ratio and the label divine proportion, then says science explains the attractiveness. He extends this to paragraphs, faces, and complexity as smaller rectangles stacked on bigger rectangles.