Humans now consume some 18 trillion watts of energy in a variety of forms—fossil fuels (coal, oil, gas); hydropower; nuclear; renewables (solar, wind, biomass, biofuels, and geothermal); and of course, the food that the 7 billion of us eat. Without this energy constantly running through the arteries of our global civilization, the world as we know it would collapse. Our cities, industries, transportation, agriculture—indeed, every aspect of our contemporary lives—depend on this tremendous flow of energy.
Anyone reading this essay is presumably already one of the energy rich—relative to others throughout human history and others in our contemporary world. You have access to electricity and the Internet. You have potable water pumped into your home and your waste safely disposed. You have an enormous quantity and variety of food at your disposal cultivated and processed in distant places. And you likely have access to travel great distances by bike, car, bus, train, ships, and airplanes. By one estimate, energy flows harnessed by humans increased more than 16-fold during the 20th century.
Much of the world, however, is still energy poor. One billion people lack electricity. Two billion are still burning wood and dung to cook and heat—the indoor air pollution from which kills some 2 million people annually. The most energy poor regions are also the countries with the highest birthrates. Energy poverty is a practical problem and a humanitarian concern. And should the terrawatts ever abruptly stop flowing through our daily lives we too would suddenly know what it means to be energy poor. I shudder to think how long a major city would survive.
In order to meet the demands of a growing population and the desperate needs of the energy poor, the world will need to increase its energy production by about 50 percent in the next two decades. Emerging markets—China, India, Brazil, and others—also aspire to achieve much higher standards of living, comparable to those in the United States and Europe. All of this increased demand occurs on the backdrop of concerns about anthropogenic climate change caused primarily by the burning of fossil fuels. Climate changes have the potential to make an enormous mess of life as we now know it—sooner or later, hotter or colder, wetter or drier.
Big History (Berry and Swimme 1992; Spier 1996; Chaisson 2001, 2006; Christian 2004; Primack and Abrams 2006; Brown 2007) offers an interesting vantage point from which we can think about energy policies and solutions for the 21st century that can lead to a healthier, wealthier, smarter, and more creative global civilization.
The Second Law of Thermodynamics
The search for energy solutions from the perspective of Big History begins with an analysis of the universe and the evolution of life on our planet. We must first understand the Second Law of Thermodynamics, which mathematically describes the tendency over time of all isolated physical systems to move toward states of thermodynamic equilibrium. Differences in temperature, pressure, and chemical potential energy, when not acted upon by external forces, invariably move from concentrated to more diffuse states. The process is called entropy and it is a hard and fast rule of fundamental physics.
The hot cup of coffee left alone reaches room temperature. The heat is conserved, but is now dispersed throughout the room. The inevitable dispersal of matter-energy from a more ordered state (the hot coffee) into a less ordered state (the room) is referred to as increased entropy.
While there is no such thing as decreased entropy, the concept of “negentropy” was introduced by Edwin Schrödinger to account for a related phenomenon (Schrödinger 1944). Negentropy is what you do when you brew the coffee, prepare breakfast, and clean up the dishes afterward, but negentropy also always requires energy flowing through the coffee machine, your body, and through the larger economy. A system that consumes energy to create, maintain, and grow complexity is said to be negentropic. All negentropic systems also increase entropy. And while entropy can be indirectly measured as heat loss, negentropy is more of a hypothetical concept. We can’t measure negentropy, in part because we have no quantifiable definition of complexity.
Life is an example of entropy and negentropy. There has to be continuous energy flow from outside some membrane into the cell and self. Human bodies acquire energy by eating plants and animals. Add water, respiration, some waste disposal, and we have a functioning body. Add science, technology, industry, commerce, communication, and fossil fuels, and we have our 18 terrawatts and 7 billion person global economy.
Most cosmologists assume that the universe as a whole is a closed system and that the universe is running downhill as it expands. Over many billions of years the universe will grow cold and dark. That is the inevitable logic of the Second Law of Thermodynamics, except that we don’t really know if the universe is a closed system.
In the early universe, gravity operated on quantum fluctuations in the early hot, dense plasma to gradually pull expanding clouds of gases together. Eventually, hydrogen and helium were gathered together to ignite stars and sculpt the fantastic web of galaxies we observe today. Pockets of negentropy now exist in the stars and galaxies. These localized energy gradients have the capacity to run uphill for a long, long time, even as the system as a whole must at some point come tumbling down. Our sun will be a reliable partner in sustaining negentropy on Earth for billions of years to come. Without the energy from the sun, coming from outside the physical system of our Earth, the concentrated energy flows of life on Earth would quickly become a very cold cup of coffee in a big, mostly dark universe.
Nothing violates the letter of the Second Law of Thermodynamics—but Big History seems to violate the spirit of the Second Law. The actual history of the universe, the evolution of life, and the human drama is one of increasing complexity, what we are calling negentropy. It is like a super hot, super dense cup of coffee in the morning at an empty construction site that explodes over the course of the day into a completely furnished home with you reading this sentence on your computer. An unfathomable amount of energy was loss to entropy. Yet what should bewilder us is the finished product—the universe and you—on the other end of that explosion.
The Second Law says nothing about the particulars of the universe we live in and observe. There is nothing in the Second Law that specifies how complexity is to emerge and expand, even as there is nothing in the universe that violates the Second Law. We may not be able to measure negentropy, but we see it all around us.
The Second Law is where we need to begin our exploration of how Big History can lead us to solutions for meeting our energy needs. The first insight is to faithfully follow the Second Law, because we have no choice. By paying attention to energy flows, however, we are best positioned to innovate and try to violate the spirit of the Second Law.
Energy Density Flow
All complexity in the universe arises in and from concentrated pockets of matter-energy—in the first instance, galaxies and stars, which then give rise to the periodic table of elements, complex chemistry, second and third generation planetary systems, and the vast quantities of solar energy to empower much smaller islands of intense complexity, like our planet. Greater complexity in the universe requires exponentially greater energy flow.
Harvard astronomer Eric Chaisson has estimated the comparative energy density flow of different entities in the universe, measured as the amount of free energy flowing through a system with respect to its mass over time, in this case measured as erg per seconds per grams (erg s-1 g -1). The Earth’s climasphere, which consists of the atmosphere and oceans, has roughly 100 times the energy density flow of a typical star or galaxy. Through photosynthesis, plants achieve an energy density flow roughly 1,000 times more than that of a star. The human body is sustained by a daily food intake resulting in an energy density flow about 20,000 times more than that of a typical star. And the human brain, which consumes about 20 percent of our body’s energy while constituting about 2 percent of our body weight, has an energy density flow 150,000 times that of a typical star. If we take the 18 terrawatt global civilization of 7 billion human bodies, then our average energy density flow today is 500,000 times that of a typical star. If our calculations focus only on the energy rich humans today, then many of us achieve energy density flows millions of times larger than the star. (Chaisson 2001; Chaisson 2006; Chaisson 2011; Chaisson 2011).
Though it seems counterintuitive, humans have generated the largest energy density flows in the known universe. We are the only entity that we know of that constructs complexity driven by external energy sources. Chaisson calculates the energy density flow on an early steam engine as 10,000 times that of a typical star. The Daimler engine of 1899 was 40,000 times greater. The Wright Brothers 1903 engine was 1 million times the energy density flow of a star and a modern fighter aircraft is 82 million times greater.(Chaisson 2012)
The same pattern also exists with computers. The ENIAC computer from the 1940s weighed 8.5 tons and used 50 kW of electricity. Today, a MacBook laptop today weighs 2.2 kg and uses 60 W. Energy density flow in computers has increased from 64,000 times that of Chaisson’s average stellar unit to 280,000 times.(Chaisson 2012)
Chaison writes of these insights:
Better metrics than energy rate density may well describe each of the individual systems within the realm of physical, biological, and cultural evolution that combine to create the greater whole of cosmic evolution, but no other single metric seems capable of uniformly describing them all. The significance of plotting ‘on the same page’ a single quantity for such a wide range of systems observed in Nature should not be overlooked. I am unaware of any other sole quantity that can characterize so extensively a principal system dynamic over >20 orders of magnitude in spatial dimensions and nearly as many in time (Chaisson 2012).
His rough estimates show an exponential growth curve in energy density flow throughout the history of the universe. If we take evolution as our guide, then our future energy policy must strive to obtain further exponential energy density growth. Over the deep time of evolution, life tends toward greater and greater complexity, and each new threshold of complexity seems to require greater concentrations of energy flowing through the system in ever, smaller sizes.
If human civilization is to advance we must use more energy normalized for mass. The energy that is most important to our lifestyle today is not the energy that flows through our bodies, but the energy that flows through our economies and cultures. If that energy were flowing through our bodies instead, we would all be burnt toast, but we are able to harness this energy outside of our bodies to remarkable effects.
Hunter-gatherers harvested solar energy from plants and animals as food to empower their mammalian bodies. With the controlled use of fire, our ancestors could turn burning wood into heat in the cold, light in the darkness, and a way of cooking and thereby pre-digesting our food. With the rise of agriculture, we gradually increased and concentrated bio-energy available to humans, including the use of muscle power from draft animals, thus supporting a growing population, permanent settlements, and division of labor. The Industrial Revolution, barely 200 years old, was empowered by the mining and burning of fossil fuels. To this mix of energy sources, we can add wind power, hydropower, and nuclear power (Smil 2007; Smil 2011). In all of these cases, we are directly and indirectly harnessing energy from the sun to empower a growing population living ever more complex lives. The energy rich in the world today consume something on the order of 2,000,000 times the energy density flow of Chaisson’s average stellar unit (Chaisson 2012).
Thus, the slogan “reduce, reuse, recycle” is only partly right because what drives the evolution of increasing complexity on our planet and in the universe is actually “consume more energy in order to be more complex.” This is what Bertrand Russell calls “chemical imperialism,” in which the chemicals harvested are stored matter-energy (Russell 1993).
This seems to be the second lesson from Big History. Exponential increases in energy consumption at ever smaller scales are consistent with the trajectory of evolution. Increasing human energy consumption may be essential to the future complexification of our species, with an important caveat.
Focusing solely on energy density flow misses important qualia and difference between emergent natural kinds and processes. A songbird, for instance, has roughly the same energy density flow as a human body. Does this mean that the bird is as complex as a human? Our kidneys consume as much oxygen as our esteemed brains. Does this mean that our kidneys are as complex as our brains?
Energy density flow is indicative of complexity, but by itself, does not tell us enough about the nature of complexity within any particular domain of the universe. Complexity cannot be rigorously defined and measured across scientific disciplines and natural domains, though we induce that complexity involves not just energy density flow, but also has something to do with information density flow within concentrated interactive networks.
Too much energy flow through a system is also just crash and burn. Too little can be just as bad. Too much or too little energy causes natural kinds to disintegrate and dissolve. Creative thermodynamic gradients appear many times in Big History, but they seem to always occur within narrow bandwidths of possibilities, what Chaisson calls “optimum energy flow.” If temperatures on Earth were continuously below minus 10 degrees Celsius or above 40 degrees Celsius, life as we know it could not exist. Such bandwidths also exist for stars, planets, rocks, and polymers. These boundary conditions for emergent complexity appear to be fine-tuned and exist throughout the universe, in evolution, and in human life. The Dutch anthropologist Fred Spier refers to this as the Goldilocks Principle in reference to the familiar fairy tale (Spier 2011).
Spier analyzes Big History from the vantage point of energy flows. He frames the rise of agriculture, for instance, as human efforts “at concentrating useful bio-solar collectors (plants) and bio-energy converters (animals) within certain areas to improve the conversion of solar energy into forms of bio-energy that were helpful for maintaining or improving human complexity.” (Spier 2011). Historians William McNeill and his son J.R. McNeill have similarly analyzed human history under the rubric of thermodynamics, though they focus primarily on networks of interaction between cultures and civilizations as the driving force in human evolution. The result of these expanding networks of information exchange is that humans were able to exponentially expand our control of energy flows through coordinated actions facilitated by symbolic language and collective learning. Language and learning requires very little energy but have had enormous impact on energy flows on the planet and in human life (McNeill and McNeill 2003).
Along side creativity, destruction is an essential feature of our cosmic story—this being the necessity of the Second Law. During their explosive death, supernovae can radiate as much energy as our Sun does over its entire lifespan. Out of this destruction, the elements of the periodic table arise. Our solar system and our planet are themselves the remnants of a supernova. Life would not be possible without the complex chemistry created in supernovae.
On the terrestrial scale with which we are more familiar, we also witness incredible destructive events in the form of continental drift, earthquakes, tsunamis, super-volcanoes, impact events, and changing climates. These geological events have dramatically reshaped our planet in the past and will again in the future. Life as we know it, including the still brief florescence of human civilization, could only have occurred on just such a restless planet. All creativity requires entropy.
To natural destruction, we now add human caused destruction. Aborigines around the world torched huge swaths of land and hunted large mammals to extinction. Early agriculture and irrigation in Mesopotamia turned once fertile fields into salinated soils and deserts. Ancient civilizations around the Mediterranean deforested the region, transforming the local climates and ecosystems. Human unintentionally harm each other through diseases spread and blunders made.
And of course, humans also have a long and dark history of intentionally harming each other through warfare, murder, rape, slavery, theft, and other forms of exploitation and oppression, as extensively detailed in Steven Pinker’s recent book The Better Angels of Our Nature (Pinker 2011). Unlike natural destruction, human violence has a moral character that we would not ascribe to natural events, in part because human evil is avoidable. We would not, for instance, want to impute “creativity” to horrific human-caused events like the Holocaust because naturalizing evil runs counter to our moral intuitions and instincts. And yet, at every stage of human history, we see creative destruction as an integral part of the story.
What are the boundary conditions for human life and other species on our planet? What are the limits to humanity’s chemical imperialism? When will human growth and activities set off a destructive cascade of failures and collapses? Our species has been on an amazing exponential growth spurt, but at some point it must end.
Available energy per se may not be the limiting factor, but the resulting entropy in the form of pollution and destruction likely will be. In addition to vast quantities of fossil fuels, there is an enormous amount of renewal energy available on Earth, and our current global consumption of 18 terawatts is rather small in comparison. The total solar energy available is estimated at 444,000 terawatts. The total wind power is estimated at 139,000 terawatts. The total geothermal energy is estimated at 139,000 terawatts. The total hydropower is estimated at 14,000 terawatts (Worldwatch-Institute. 2009). Technologies may soon allow us to concentrate this energy in usable forms. And should commercially viable fusion energy ever be available then humanity would have a virtually unlimited source of energy.
The challenge is not energy per se, but the kind of entropy this energy consumption would unleash on the planet in the form of industrial production, waste generated, mountains moved, and ecosystems altered. And while anthropogenic climate change from the burning of fossil fuels is a real danger, we should also anticipate naturally caused climate change as a future inevitability. Our species is well positioned to survive dramatic climate changes, more so than other large mammals, but the short-term results would mean a dramatic devolution in quantity and quality of life. We don’t really no what the Goldilocks boundary conditions are for the planet and our species in the Anthropocene.
Maximize Creativity, Minimize Entropy
Humanity must pay more attention to the entropic results of our energy generation and consumption through a new whole system’s approach. There are two ways to increase energy density flow. The first is to increase the amount of energy flowing through the system. The second is to make the system smaller. As the late Richard Feynman pointed out—there is a lot of room at the bottom (Feynman, Leighton et al.  2005). From the human scale, the universe is as many orders of magnitude smaller than us as it is also larger.
Our analysis of Big History and the thermodynamics of complex systems suggests that greater energy consumption at ever-smaller scales is a pattern in the universe that we should intentionally emulate in our energy policies. The existence of finely tuned Goldilocks Gradients also suggests prudence and pragmatism are needed in the transitions ahead.
It may be that greater energy efficiency has survival value at different stages of our cosmic story and that we should start measuring those efficiencies in terms of energy density flows. Few of us think about energy flows in our daily lives. We drive to the supermarket to buy our groceries which we store in a refrigerator and cook on the stove. Calculating the flow of energy in our morning breakfast, including multiple conversions of energy from one form to another along the entire journey from field to body, requires a new kind of scientific and economic literacy (Smil 2007). Elegance in evolution is achieved when we do more for less with the emphasis being on more and smaller.
Big History provides both a humbling and ennobling view of the human experiment within the context of the evolutionary epic. Humans have the possibility of maximizing creativity while minimizing entropy. In so doing, we may enhance and continue an evolutionary epic that seems to desire greater complexity along with exponential growth in energy density flows. “Maximize creativity, minimize entropy” is the new ethical, aesthetic, and pragmatic axiom for our future success.
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