The Physics of Life explores the roots of the big question by examining the deepest urges and properties of living things, both animate and inanimate: how to live longer, with food, warmth, power, movement and free access to other people and surroundings. Bejan explores controversial and relevant issues such as sustainability, water and food supply, fuel, and economy, to critique the state in which the world understands positions of power and freedom. Breaking down concepts such as desire and power, sports health and culture, the state of economy, water and energy, politics and distribution, Bejan uses the language of physics to explain how each system works in order to clarify the meaning of evolution in its broadest scientific sense, moving the reader towards a better understanding of the world's systems and the natural evolution of cultural and political development.
The Physics of Life argues that the evolution phenomenon is much broader and older than the evolutionary designs that constitute the biosphere, empowering readers with a new view of the globe and the future, revealing that the urge to have better ideas has the same physical effect as the urge to have better laws and better government. This is evolution explained loudly but also elegantly, forging a path that flows sustainability.
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About the Author
Adrian Bejan, chair professor of Mechanical Engineering at Duke University, is one of the world's preeminent energy scientists who developed the Constructal Law of design and evolution in nature. He also currently holds chairs at the University of Evora, University of Pretoria, and Hong Kong Polytechnic University. He has written leading books on applied physics, including Design in Nature, Advanced Engineering Thermodynamics, Convection Heat Transfer, and Convection in Porous Media. He has given two TED lectures.
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The Physics of Life
The Evolution of Everything
By Adrian Bejan
St. Martin's PressCopyright © 2016 Adrian Bejan
All rights reserved.
The Life Question
What is life? is, of course, the big question. In 1944, Erwin Schrödinger, the Nobel Prize–winning Austrian physicist, made a valiant and now classic attempt to answer this in his aptly titled book What Is Life?, which took up the question from a genetics and biology of living cells starting point. It is a perplexing and perennial question that has possessed philosophers and scientists from time immemorial. Just a few months ago we were informed in The New York Times, no less, by the science writer Ferris Jabr, that science has no answer to this basic question. "What is life? Science cannot tell us ... scientists have struggled and failed to produce a precise, universally accepted definition of life." He adds that "nothing is truly alive." Naturally, I disagree with this.
This book is my attempt to explore the roots of the life question by examining the deepest urges and properties of all the things that move and that, while moving, change freely. This is nature and it covers the board, from the inanimate (rivers) to the animate (animals, humans, social organization). These urges were with us long before science emerged: the urge to live longer, to have food, warmth, power, movement and free access to other people and surroundings. I will explore why all these things are "urges," why they happen by themselves, naturally, and why they are in each of us and in everything else that moves and morphs freely.
The urge for life, the life question (and its opposite, the death question, which we tend to avoid), is what this book is about. Unlike Schrödinger, however, I will place this question firmly within the realm of physics — the science of everything.
In my book Design in Nature (2012) I wrote about the phenomenon of organization in nature and its physics principle, for which I coined the term "the constructal law" in 1996. According to constructal law, life is movement that evolves freely, in both animate and inanimate spheres. Alive are all the freely changing flow configurations and rhythms that facilitate flow and offer greater access to movement. When movement stops, life ends. When movement does not have the freedom to change and find greater access, life ends.
In constructal law the life phenomenon is everywhere. Life unites the inanimate realm (rivers, lightning, snowflakes, air turbulence) with the animate realm (animals, vegetation, society and technology). Seen in this broad light, the life phenomenon is older than the biosphere, because the inanimate flow systems of geophysics populated the earth before the animate flow systems of biology.
Life, organization and evolution are physics (natural things, physika, in Greek), and are governed by their own law of physics. I know firsthand the difficulty that the science-educated face when reading that life is a phenomenon of physics, comprising all the flow systems — inanimate, animate and human-made — that morph freely and evolve toward greater access. After all, the word "biology" means the study of life (bios, in Greek). Even a child knows the difference between animal movement and the rest of the moving world (rivers, winds, oceanic currents, volcanos, snow, rain, lightning and earthquakes).
The physics, the natural tendencies of all these moving things, are one. While in the 1800s the child associated the cart with the animate horse, the child of today associates the cart with the inanimate gasoline, engine and the money paid by the parent at the gas pump. After reading this book, the child of tomorrow will put the money together with the gasoline, the horse and the oats that fuel the horse.
This is how knowledge evolves — from science, technology and the rule of law it becomes, in one word, culture. What was obvious and understood piecemeal becomes one entity, much bigger and simpler. With every new generation, the child grows into a more knowledgeable parent and teacher, while increasingly ignorant of the tentative and disunited past. Knowledge is contagious, and it spreads naturally. I do not see a difference between art and science. They are both about images in motion. The inner pleasure is the same whether making a piece of art that inspires the viewer or coming up with a scientific idea that triggers explosions of images in the mind of the same viewer. Scientists and artists are specimens of the same species.
Freely morphing movement is a macroscopic phenomenon. The entity that moves does so relative to the rest — its environment — which does not move. Movement is contrast, and contrast is visible. We, the observers, call this phenomenon by many names — organization, configuration, design, architecture, change, evolution — names that make sense in our minds because they are as old and as frequent as the images that bombard our senses. Interesting as they may be, the unseen molecules, atoms and subatomic particles are not the macroscopic life phenomenon of evolving organization. Descriptions of their random walk, disorder and Brownian motion are not the same as descriptions of the paths of rivers, pulmonary air and city and air traffic.
In The Physics of Life, I move beyond the parameters of Design in Nature. I construct an edifice of examples to help readers understand the significance of the life principle in their own lives and in our culture today. These examples come from both the geophysical and the animal realms, from the old and the new. They come together not as apples and oranges but as one, because the life phenomenon in nature is one. I will show how the constructal law informs the evolutionary designs that sustain life: power generation and use, transportation, technology and evolution; the spreading of new ideas, devices, knowledge, wealth and better government.
As I was finishing Design in Nature one of the most interesting discoveries for me (and what sparked the idea for The Physics of Life) was that air mass transit on the globe has a sharply hierarchical geography (figure 1.1). Even though air traffic connects the entire populated area of the globe (like the cortex of the brain), most of the air traffic is positioned over the North Atlantic.
Human movement has geography and history. It creates, like all the river basins put together, a constantly changing world map with a few large channels and many small channels. It has hierarchy. Because I cannot forget my MIT education, I thought of this in terms of physics. Seeing as how air traffic happens because it is driven by engines that consume fuel — et voilà! — the burning of fuel must also be hierarchical, with a world map of its own. A few large consumers of fuel collaborate with many more small consumers to spread the flow of movement throughout the entire population, all over the globe. The hierarchy of the whole is good for every moving individual.
Have money, will travel. In a flash, it became obvious to me that the geography of air mass transit and fuel consumption illustrates the geography of global advancement. The two legs of the air bridge over the North Atlantic are planted firmly (and historically) in the most advanced regions of the world, Western Europe and North America. This is how I decided to plot, country by country, the annual rate of fuel consumption versus economic advancement (measured as the annual gross domestic product, GDP).
What came out on paper is shown in figure 1.2. There is an amazingly sharp proportionality between fuel consumption and "wealth." Fuel consumption is physical (tangible, one can weigh fuel and measure the power associated with burning it), while wealth and all the other "obvious" notions used in economics (utility, the idea of money, being better off) are intangible. Economics, it appears, is physics as well; it encompasses the tangible and the intangible.
This led me to further discoveries. The fuel consumed annually in one country drives much more than the airplanes that carry the flying population of that country. The consumed fuel drives everything that moves, kicks, heats and cools. It drives the entire society. It keeps it alive. It sustains it. Why do I say "everything that moves"? Because the measure of wealth (GDP) — so sharply synonymous with the rate of fuel consumption — accounts for everything that lives, moves and changes in society.
While I was drawing figure 1.2, unusual answers to old puzzles started to voice themselves in my mind. For example, why are all the countries racing upward, along the same line? Why is the United States leading the peloton? Americans are not smarter than the people of other countries; in fact, most Americans are descendants of those people. Why is the urge to have "wealth" in every individual and group?
The answers boil down to the single fact that the urge for more and easier movement is in everybody and in everything that moves and changes, with freedom to change. In figure 1.2, this means that the dots must speed-walk to the right, toward more fuel consumption, not less. No one will cut back on fuel consumption, because no one prefers poverty over wealth, or death over life.
This is how the story of The Physics of Life got started. This voice in my mind, the relationship between GDP and fuel consumption, led me to question views that scientists, pundits, politicians and the public consider obvious. It allowed me to bring all the answers under a single scientific umbrella.
There is a hidden truth in science, and it is unveiled in this book. Science is interesting when it is about us, and when it is useful to us. This is why the ideas in this book are about our needs and how to achieve them, and how to construct a better future for humanity.
The story of The Physics of Life is rooted in the obvious: every animal and human wants power. We see this very clearly in the urge to eat — to consume — and in the march upward to the right in figure 1.2 — food for animals, and fuel for our vehicles and machines. Food for the human & machine species (see chapter 4) is power, which in physics is called useful energy (or "exergy") consumed, per unit of time. From power comes movement: body movement, internal flow (pumping blood and air), external flow (locomotion, migration, transportation). And from power we get the means to ensure our safety and comfort — warmth, drinkable water, health and the construction of highways and steel beams that do not break when we walk or drive on them.
My use of the word "machine" in the name of the human & machine species needs some explaining. It is not about automobiles, power plants, refrigerators and manufacturing. Machine is used in accord with its oldest meaning, which is contrivance (mihaní in old Greek), a sophisticated tool that allows for more effective use of human effort. Every artifact that we attach to ourselves is a contrivance, the shirt, the harvested food and the power drawn from an animal or an electric outlet. It's true that through the centuries new contrivances have made us much more powerful, bigger and longer living. Yet, a machine should not be confused with or limited to the biggest contrivances that empower us today.
The machine was in us from the beginning. It was also there from the beginning of science as mechanics and mechanisms, which are as old as geometry. The word itself belongs in the realm of physics because it is physical, the palpable and measureable version of our last name, sapiens (wise, or knowing). Words have meaning, especially in science.
The growth and spread of civilization on the globe is the flow of more power to more individuals, for greater movement of the whole. This is better known as the evolution of power generation and consumption (from domesticated animals, to slaves, serfs, windmills, waterwheels, steam engines) and the contagiousness of life (individual liberty, health, emancipation, affluence and empowerment). We cannot have enough of any of these design changes. They are good, and they stick because they are useful for our movement. This is evolution and life, as physics.
Everyone wants more power, not less, and everybody collaborates with others in order to get more. Collaboration itself is movement, because the root term "labor" means work, and work entails movement (work = force · travel). Collaboration is another word for organization, a flow configuration with purpose and the freedom to change, which together mean life. When the flowing entities are free to change, they turn to the right, and then to the left, and to the right again, to find better ways of flowing. Flow itself enables better flow over time. This is sustainability, as physics.
Life, as a concept in thermodynamics, is unambiguous and easy to grasp. It is the antonym of death. The thermodynamic definition of the dead state is well-established. It is the condition — the being — of a system (an amount of material, or a region in space) that is in complete equilibrium with its environment. For example, in the dead state the pressure and temperature of the system are identical to the pressure and temperature of its surroundings. Dead state means "nothing moves," not the system, and not its innards.
The opposite of the dead state, which I now define, is the live state. The live-state system is not in equilibrium with its environment. Differences of temperature and pressure (and other properties) are everywhere, inside the system and outside, between the system and its surroundings. As a consequence, the system is being pushed and pulled, heated and cooled, it is inhabited by flows (currents) and, above all, by organization. It moves as a whole and it morphs freely as it moves and flows.
The live system has flow, organization, freedom to change and evolution. Once present, these features distinguish the alive from the dead.
Life is movement, and in order for both to happen, movement requires work spent, work requires food and food comes from work — a job for the human, fighting and hunting for the carnivorous animal and constant walking and grazing for the herbivore. All these words come together to say that life is work. This is the naked physics of life, but why is it important? It is important in education, which is my profession, where many of my contemporaries teach the young that there is a lot more to life than work. It may already feel this way to the child of ready money in an affluent society, where food is much easier to find than in other parts of the globe. The big picture, however, is that of a global movement of humanity that, in order to keep moving, must consume food and other streams (heating, cooling, freshwater) that flow from nowhere except work (power) spent.
To each of us, life is a private movie, a strictly personal show in which the individual is screenwriter, director, producer, actor, spectator and reviewer. The individual improves the plot as the tape rolls forward. The direction of the movie plot and the rolling of the tape are the same in all such movies, which is toward a longer movie.
This movie has a beginning and an end. There was nothing to watch before the beginning, and there will be nothing to watch after the end. For some of us, the movie script includes one or more intermissions, which cover the brief periods of unconsciousness that accompany modern surgery. These intermissions resemble what was before the movie started, and what will be after the movie ends. In view of all this, there are only two things to do: improve the script, and enjoy the show.
We are wedded to an incorrect, dichotomous understanding of life: natural vs artificial, animate vs inanimate, bio vs non-bio and nature vs nurture. Yet most of us are unaware that we are flowing together with so many like us. We are like the raindrops falling on the plain. The water must return to the air, and it manages to do so by flowing through many designs such as tree-shaped river basins, grazing and migrating animals, grasses, trees and forests, waves on the ocean, sand dunes, oceanic and atmospheric currents and disruptions caused by fallen trees and broken branches, all causing eddies, whirls and turbulence, all flowing and dying downstream. All this is life.
Symbiosis, the urge to live together when such association is of mutual advantage, is a manifestation of the life law of physics everywhere, bio and non-bio. We see it in two rivulets that come together into one stream. We see it in the fungi on the roots of plants, the mycorrhizal networks and the flow and life of the soil. We see it in every instance of social organization, where the urge to join is of selfish origin.
It is not that getting together and making one big thing out of a huge number of small things is the best arrangement. There is a balance to be reached between the large and the small, between the few and the many. Big is not the answer. The answer is that it is easier to move stuff on the landscape (animate, inanimate, social) with the support of a special tapestry of a few large and many small carriers. This balance, or hierarchy, is predictable in every domain we have looked at. This is how the flow most easily covers the available area or volume.
Organization (design) happens naturally. The word "organization" speaks of the fact that the design — the organ — is alive, with flows inside and around it, all belonging to a greater whole, and all morphing, evolving, growing, shrinking and moving in the world. Collaboration is a design that comes from the selfish urge of each individual to move more easily. We collaborate in order to flow together in ways that serve us better individually. These collaborations are channels through which things flow, channels that hug the flow and morph with the flow. They are not "links," and "networks," not strings tied between two or more nails.
Excerpted from The Physics of Life by Adrian Bejan. Copyright © 2016 Adrian Bejan. Excerpted by permission of St. Martin's Press.
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Table of Contents
1 The Life Question 1
2 What All the World Desires 23
3 Wealth as Movement with Purpose 49
4 Technology Evolution 67
5 Sports Evolution 93
6 City Evolution 115
7 Growth 133
8 Politics, Science and Design Change 153
9 The Arrow of Time 181
10 The Death Question 205
11 Life and Evolution as Physics 223
Appendix to Chapter 5 244
About the Author 248