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Laws of Life

One of my favorite literary genres is what I like to refer to as The One Thing That Explains Everything (TOTTEE). Surrounded by strangers on the overcrowded London Underground, I am transported by the awe-inspiring grandeur of Guns, Germs, and Steel expounding on how the east–west geographic orientation of Eurasia led to it outcompeting north–south-oriented America and Africa; or the masterful epoch-spanning epic storytelling of Sapiens explaining how our capacity for imagination turned us into gods. I feel informed and empowered, enraptured and entertained. But when I turn the last page or hear the final end credits about how Audible hopes I've enjoyed this audiobook, I am left unsatisfied.

You and I know – and so too do the authors of these books – that the world is complicated. Arrows of causality showing what causes what split, rejoin, point in multiple directions, and even feed back on each other. No one thing explains everything.

The power of a good TOTTEE book comes from highlighting a fundamental force that shapes our world. But in the real world, especially when we move from explanation to application, there are many forces that must be understood in their relationship to one another.

Geography, for example, is no doubt important, but the thin strip of land splitting Korea into North and South cannot explain the sudden disjuncture between wealthy South Korea, its brightly lit urban infrastructure visible even from space, and poor North Korea, a dark patch on the map separating South Korea from China. To explain that disjuncture, you might need to understand government institutions.

Institutions are important, but they can't explain why different ethnic groups have different outcomes in the same country. For that you might need to understand culture and intergroup competition.

Culture is important, but it can't explain how multilingual, multicultural, multi-religious Singaporeans became the second richest people on the planet after Luxembourg. For that you might need to understand history. But history is complicated and, unlike science, doesn't offer clear causal explanation and application by itself.

This book is TOTTEE adjacent. Rather than offering a single ‘one thing’ to explain everything, it offers a framework that unifies the many forces that shape all of life. These laws of life govern multiple scales, from single-celled bacteria competing for a patch of nutrients to societies of businesses competing over market share. Of course, bacteria and businesses differ in many details, and those details matter for how we should intervene in the world. The applied goal is to identify where, when, and how we should intervene.

Is the lever we need to pull a political matter, a market challenge, a technological gap, a cultural mismatch, a psychological barrier, or some combination? All are shaped by the laws of life. To effectively intervene, we need a periodic table for Homo sapiens and we need to be able to see the big picture and then zoom in and out of different parts. What the laws of life offer is a systems-level, ultimate view.

Systems-level ultimate explanations

Systems-level thinking is essential to the creation of permanent change. One of many cautionary tales about what happens when these interconnections are ignored is the story of cane toads in Australia.

In the early twentieth century the new nation of Australia had a burgeoning sugar-cane industry. The cane crops flourished in the fertile soil, plentiful sunshine, and tropical climate of Queensland, Australia's Sunshine State. The only problem was the native Australian cane beetle, which was so fond of sugar cane, it bore its name. Cane beetle larvae feast on sugar-cane roots, stunting or even killing the plant. Something had to be done. The scientists at the Bureau of Sugar Experiment Stations saw an obvious problem and an obvious solution. Kill the cane beetle.

But how could they do this without hurting the plants?

In 1935, 101 assassins made their way from Hawai‘i to Australia. Not Dalmatians, but cane toads. The toads liked their new home. So much so that their numbers have grown to hundreds of millions if not over a billion. But they have found more than the cane beetle to their liking, and have thereby wrought havoc on the isolated Australian ecosystem. The cane toad is poisonous from egg to tadpole to toadlet to toad, and is thus dangerous to both those they eat and those that eat them. Australian native species, isolated on the island for so long, have no defenses against such a successful predator. Crocodile versus cane toad? Cane toads kill the crocodile even after they're dead.

Today, cane toads are everywhere in Queensland. They are a constant reminder of how a single-minded solution that ignores the broader system can wreak havoc and create new problems requiring even more solutions. Thinking at a systems level is difficult but necessary for successful solutions. One approach is to separate ultimate from proximate explanations.

The ultimate–proximate distinction is an important concept in evolutionary biology. Similar concepts are found in most sciences. In the business world, it's similar to root cause analysis and the five whys. The classic example used to explain the ultimate–proximate distinction in biology is the question of why animals enjoy sex. Here's a proximate explanation: sex is pleasurable and people prefer pleasurable things. This is a kind of explanation but it's tautological. Here's a better explanation: sex releases a chemical cocktail of motivation and loving desire – dopamine, endorphins, oxytocin – all associated with pleasure, love, and trust. Together, they reinforce the behavior. This is a better explanation that invokes neuroscience. But it's still proximate. All we've really done is given more details about the mechanism of ‘sex is pleasurable’. What it doesn't tell us is why people prefer sex to, say, banging their heads against a wall. Understanding the full range of alternatives provides an ultimate explanation.

Here's a systems-level, ultimate explanation for sex: sex is associated with procreation and preferences are transmitted between generations. Imagine a world where some animals associate sex with pleasure and others associate wall-head-banging with pleasure. Animals that associated sex with pleasure had more offspring and so left more descendants who themselves enjoyed sex and had more offspring. And the animals that associated banging their heads against a wall with pleasure and preferred it to sex? Well, they didn't have children and are no longer with us. Nor are their preferences.

Ultimate explanations tell us why almost all of us like chocolate and only some people like chili peppers. When applied to the social world, taking a systems-level view of connected ultimate causes tells us where the ultimate source of a problem lies.

For example, people often blame politicians for inflation and rising energy prices. But if inflation and rising energy prices are occurring around the world then leaders of any specific country are unlikely to be at fault. An underlying ultimate explanation is more likely.

The first law of life is the law of energy.

The ultimate ceiling on the biomass and complexity of all life forms is the availability of energy. Energy is what makes matter come alive. Energy is what matter uses to scurry, fight, and make more of itself. Energy is why you and I can enjoy a life that would be the envy of the richest monarch a few centuries ago. It is thanks to our unprecedented control of energy that you can sit in your climate-controlled home; you can walk, drive, or fly to other places; you can eat a sandwich; you can reproduce; you can read this book. It is the density of stored energy in different sources, the availability and abundance of these sources, the power – energy transferred per second – and the efficiency with which we can find and use these sources that constrain what we are capable of doing. But while energy is in theory abundant – the light falling on Earth, the heat from its core escaping through geothermal vents, the rushing of rivers, or flammable fossil fuels – we need innovations that allow us to use these sources to do work. Indeed, when energy is abundant, as it was after the discovery of fossil fuels, it fades into the background as a law. It becomes like the fish's water. Instead, we begin to focus on innovation alone, particularly innovations in efficiency, to do more with the same amount of energy.

The second law of life is the law of innovation.

Life innovates new ways to efficiently capture and control available energy in competition with other life. These innovations include biological changes such as photosynthesis or the ability to digest meat or milk, technologies such as farming or the engine, and social organizations such as corporations and countries. These innovations, whether biological, technological, or social, increase the amount of energy available by discovering ways to use more of it or use it more efficiently.

Take the history of lighting as an example. Candles turn less than 0.04% of the chemical energy in wax into light. The rest is lost as heat. Edison's first light bulbs were still less than 1% efficient – more than 99% of the energy was lost to heat. Modern incandescent lights are at most around 10% efficient. Fluorescent lights around 15%. LED lights continue to become more efficient and can in theory approach 100% efficiency. LEDs are brighter, last longer, and consume less energy – so much so that the admonition to ‘turn off the lights’ is now one of the least effective energy-saving behaviors. All these technological innovations allowed us to do more with less. But each innovation, both biological and technological, required organisms to work together.

The third law of life is the law of cooperation.

When there is sufficient energy to exploit and more that is reachable with the help of just a few more helpers, we can make the leap and work together to capture it. Cells can bind together into complex organisms; regions can bind into nation-states; corporations can sign deals, mergers, and acquisitions. Innovations that unlock more energy through new sources or greater efficiency increase the space of the possible.

The more energy unlocked, the larger this space. The larger this space, the larger the possible scale of cooperation. A larger space allows for larger animals and larger states.

Think of it this way. Imagine you are starting a business. If you could run the company all by yourself and keep all the profits to yourself, you should. But by working with others – hiring employees, signing agreements with vendors, bringing investors on board – you can increase your chances of success and size of profits, even if you need to share them with others. The optimal level of cooperation is the level where you have a high probability of winning the spoils and your share of the spoils is larger than the share you could have got in a smaller group or larger group.

We typically don't calculate this consciously. Instead, we get there through trial and error, partial causal models, and selection. Companies with unnecessary employees fail or make less profits. Companies with too few also fail or make less profits. In other words, the level of cooperation is reached through an evolutionary process.

The fourth law of life is the law of evolution.

The exploitation of energy, the way in which we innovate, and the mechanisms of cooperation are typically not intelligently designed solutions but rather the product of millions of attempts, with successes outcompeting failures.

Energy, innovation, cooperation, and evolution are four laws; four interconnected ways to carve up the world and explain how geography, institutions, culture, and history have played out. We will revisit them in more detail at the end of this chapter. For now, let me show you how these laws manifest in each of our lives and then in the history of all life.

Energy, innovation, cooperation, and evolution in the everyday

We all face a trade-off in how much time to allocate to work, to our families, to our friends, and to ourselves. In tackling this trade-off, I personally am obsessed with efficiency. I've spent years figuring out how to maximize my use of the twenty-four hours I have each day, the fifty-two weeks I have each year, and the eighty or so years the average Western male gets for a lifetime. This obsession includes how to efficiently distribute my cognition in a way that prevents my to-do lists and project prioritization tools from getting in the way of focused deep work; how to hack my psychological limitations by doing things like leaving work unfinished at the end of a day to make it easier to restart the next (an application of the Zeigarnik effect); accepting that while it is inevitable that I will procrastinate, it is not inevitable what I will procrastinate on – I can procrastinate by working on low priority things that do actually need to get done – productive procrastination; and even how much time to spend on optimization itself and how much free time I need to ensure there's space for spontaneity.

My obsession even extends to how to efficiently be a better parent to my three children, efficiently be a better partner to my spouse, and how to efficiently relax.

To quickly relax my mind, I find sensory-deprivation tanks a cheat code to meditation. I float with earplugs in a pitch-black tank filled with body temperature Epsom-salted water, like a personal perfectly warm Dead Sea. After a few minutes, my mind wanders and then starts to self-organize. My anxiety and stress dissolve in the water.

To quickly relax my body, I stress it. Apart from lifting weights, one of my favorite ways to stress my body is by profusely sweating in a German Aufguss sauna ceremony. For ten to twelve long minutes, gloriously scented, steamy air heated to at least 85 °C (185 °F) is whirled and beaten around the room and at participants by a skilled Aufguss sauna master. Blood rushes to your brain and body. Stress-free participants stagger out of this communal ritual to a short warm shower followed by an icy cold 4 to 5 °C (40 °F) dip.

But here's the rub. No matter what weird psychology or ceremonies I use, there is a limit to my efficiency. At the end of the day, I still have only twenty-four hours, of which continued efficiency requires eight dedicated to sleep – efficient sleep of course, optimized for letting ideas ruminate. Imagine how much more you or I could do if we had more than twenty-four hours.

There are ways to get more than twenty-four hours. One way is to supplement what we do with machines. We multiply our time by harnessing energy to do work for us.

Polymath Buckminster Fuller had a thought experiment in which he asked us to imagine all the work of the machines that surrounded us being performed by animal or human labor. My car can probably manage around 200 horsepower. Imagine those were actual horses? But those 200 horses wouldn't last long without large amounts of food, water, and rest. A full tank represents the work of around fifty strong men working for a month. Energy-powered transport has shrunk our world. I can travel across town in minutes not hours to meet a friend. I can cross the globe in hours not months for my next collaboration.

Energy is required for everything. Even the food we eat. Long before I cook pasta on a stove or warm up leftovers in a microwave in minutes, the wheat in my pasta was fertilized by ammonia synthesized by combining the nitrogen in the air and hydrogen from natural gas in the Haber-Bosch process, pests were killed with crude-oil-derived pesticides, the ground was plowed by fossil-fueled tractors; and the pasta was delivered to the supermarket by refrigerated trucks, ships, trains, and airplanes.

As Vaclav Smil points out, half the planet – nearly 4 billion people – would not have been alive without synthetic ammonia fertilizer that led to the Green Revolution in agriculture, a second agricultural revolution that rivals the first agricultural revolution 12,000 years ago.

Energy is everywhere.

Our civilization's control of energy is a product of the laws of energy and innovation creating the space of the possible in which we all now live. Efficient, energy-powered technologies have shrunk the globe and effectively extended our time. But there's one more way that I can extend my twenty-four hours. I can also cooperate with other people.

I can build a better company, write better books and papers, and engineer better products by not doing everything myself. When I work with others, the synergies of our different expertise further extend the effective time we all have. I can pass on to my collaborators and employees tasks that they can do faster or better than I can, allowing me to focus on my comparative advantage. Indeed, we also need to cooperate just to harness energy – I can't mine, process, and convert coal to electricity all on my own.

I'm telling you all this because I want you to see that the decisions, trade-offs, and competition we face as individuals are part of a broader system. The challenges we face in our everyday lives and the challenges we face as a society are not new. They are as ancient as life on Earth. They are governed by the same underlying laws.

Energy, innovation, and cooperation are shaped by technologies and ways of working that are themselves shaped by genetic and cultural evolutionary forces. These four factors – energy, innovation, cooperation, and evolution – also affect my everyday life, which is a microcosm of the way in which they affect our society and the evolution of life itself.

These laws weave our personal stories into the larger story of life on Earth. All life forms had to solve energy crises and overcome sudden shocks, just as we do today. To see these laws at play, let's go back to the very beginning. Bear with me, it won't take long, but then you will see how fundamental these laws really are.

A brief history of everything

The universe is about 14 billion years old. Earth is about a third of that, at around 4.5 billion years old. Not long after its formation a planet-sized object, around the size of Mars, smashed into our young planet. This violent collision ejected enough debris to create the Moon. That was a happy accident, because it was the Moon and the Earth that together created life.

Compared to the moons of other planets, our moon is relatively large, over a quarter of the size of Earth. Indeed, some scientists have suggested that the Earth and Moon should be considered a binary planet – two planets orbiting each other. One definition of a binary planet is that the center of mass of the two bodies – the point they both orbit – lies beyond both. Currently, this is not true of the Earth–Moon orbit. The center of mass is around 1,000 miles under the surface of Earth. But the Moon is slowly drifting away. The drift isn't fast enough for the Earth–Luna system to reach this binary planet defin-ition in any reasonable time. But if you run the tape backwards, it means that the Moon used to be a lot closer to Earth. Tides are created by the Moon's gravity pulling on the oceans and so the early Earth had massive tides, stirring the primordial chemical soup, moving warmth and sloshing the oceans back and forth over the land. This created tidal pools that brought ocean life to land and tidal-pool life to the oceans. It was thanks to this gravitational energy that life could begin.

Laws of life govern all

The ultimate constraint on this entire system – the ceiling on the space of the possible – was once the sun and the ability of plants to convert solar energy into something we can use. For most of history the energy ceiling was low for all life, regardless of genetic or technological innovations. There was no point in cooperating at large scales as we do today – what we could gain had to be taken from the other poor folks around us. No amount of innovation or cooperation could pierce the ceiling of the law of energy.

If you look at graphs over the last several millennia of wealth, energy capture, total population size, size of countries and polities, child survival rates, or just about any other indication of progress then you'll notice something odd. There are wiggles and bumps, but everything is pretty flat from the beginning of history to the mid 1700s. And then everything just explodes.

Human progress. Based on graph and data compiled by Luke Muehlhauser, https://lukemuehlhauser.com/industrial-revolution/

All those major world events – the fall of the Roman Empire, the violent conquests of Genghis Khan, the devastation of the Black Death, the innovations of the Renaissance, the discoveries of the Scientific Revolution – and much more of what you covered in high-school history are mere blips. They are completely dwarfed by the enormous progress that has taken place since the Industrial Revolution. The laws of life tell us why.

Till the 1700s the energy ceiling remained low. The amount of work our ancestors could do was a function of their own manual labor and the labor of their work animals, such as oxen and horses, made more efficient by a few sparse mechanical innovations such as levers, pulleys, and windmills. Once the technologically supplemented human and animal labor paid for its own energy costs in terms of the energy needed to produce the food and build and maintain the technologies, there wasn't a lot of excess energy. With so little excess energy, no matter what we did, no matter how clever we were, no matter how hard we worked, there was a limit to what we could achieve. Then we discovered a large store of densely packed solar energy that changed everything. It was the sacrifice of past life.

Plant matter, algae, and other ancient organisms had stored solar energy in chemical form. Time and pressure had compressed all that chemical energy into dense coal, oil, and natural gas. We found fossil fuels and learned to use them. Those chemical batteries took millions of years to charge. We have been draining them in a matter of centuries, using that awesome power to raise the energy ceiling to unimaginable levels and allow our civilizations to soar to the heights we've reached. Underneath that almost vertical line you previously saw is a fossil-fueled fire.

Fossil fuels led to new innovations in the efficient use of the energy they contained. Industrial societies wielding this new power source were able to use it to colonize and dominate pre-industrial societies. The unlocked energy and all that we could do with it incentivized working together, leading to larger, more complex, relatively internally peaceful new civilizations, which would eventually be made up of people from all over the world. These large groups could then begin flirting with alternative sources of energy, from nuclear to solar.

Each energy source allowed us to access the next higher energy density source with greater efficiency. But energy became so abundant, the ceiling so high, that over generations we forgot that there was any limit at all. Our engineers and economists largely stared at the floor, focusing on technological innovations in efficiency. For those familiar with economic growth models, the focus was on the A technology term that multiplies our labor (L) and capital (K). Thus far, doomsayers from Thomas Malthus to M. King Hubbert seem to have been proven wrong time and again by technological advancements. Technology seems to have saved us from the Malthusian trap and delayed Hubbert's peak oil decline. But those technological advancements have been in the efficiency floor, not the energy ceiling. And in the end, it doesn't matter how fancy or efficient your gadgets are, if you can't charge them, you can't use them. Technology that unlocks more energy is fundamentally different to technologies that make life more efficient or enjoyable. We assumed that we could ignore energy because we would always have enough, but as financial advisors warn: past performance is no guarantee of future results.

The energy ceiling is falling.

Fossil fuels are becoming costlier to mine, process, and use. Once cheap and abundant, they are now expensive and scarce. Innovations in efficiency have also meant that these resources can be captured and controlled by fewer people. Continued progress, peace, and the civilization they create require us to get to the next energy level.

It is through the lens of the laws of life that all the pieces suddenly come together to make sense of who we are and how we got here.

Let's start with the ceiling constraint – the law of energy.

The law of energy

Let's say you're mining. You could dig up coal or you could dig up uranium. Uranium is much more energy dense than coal. That's really an understatement – uranium has at least 16,000 times as much energy per kilogram, 2 million times as much if enriched. That's great! But what also matters is how much energy it takes to access and use that energy source. Let's think about some of those costs.

The first step is digging some ore. You could dig the ore from the ground with your bare hands. That would take a long time and lead to dirty, bloody fingers. One innovation in efficiency would be a shovel and pickaxe. That technology would be slightly more efficient. But you are still doing all the digging. You are still limited by the energy provided by the food you consume. That in turn is limited by your agricultural technology, the energy you use to power it, and genetic limitations as an under-muscled, underpowered human ape. We are much weaker than the other great apes and many other animals.

So, a further improvement would be to use another animal with a better food-to-muscle ratio, such as an ox. An ox not only has a better energy return on energy invested in food but can also generate more power – energy released per second – than you can. You can use that power to drive a bigger plow more forcefully to prepare more unyielding rocky ground. But to have an ox, you need enough excess food to feed and domesticate the animal. Again, this is a function of your agricultural technology: can you grow enough food to feed you, your family, your community, and the oxen? Will the food grown with the help of the oxen be enough to feed your community of humans and animals?

If you already have access to industrial energy sources such as fossil fuels, you could use an engine with a more straightforward return based on the quality of the ore and the ease of finding, processing, storing, and transporting it, and the technology of your engine. You might also require the help of other people. But again, the question is the same: is the return from those fossil fuels enough to justify feeding all the people and animals and fueling all the machines involved in getting that energy?

This concept is what Charles Hall calls energy return on investment (EROI), sometimes also referred to as energy return on energy invested (EROEI). EROI is normally calculated as a ratio by dividing the output energy by the input energy:

It's a ratio of how much energy you expend in getting some energy back; a sense of how much excess energy you have. How many calories do you burn relative to the size of the animal you catch, cook, and consume? A hunter who expends more calories hunting than the calories they get from their kill is going to starve.

The EROI of different energy sources varies dramatically and also changes over time as an energy source becomes more difficult to access. For example, coal that's close to the ground has a higher EROI than coal that has to be laboriously dug up from deep inside a mountain. As economic historian Tony Wrigley convincingly argues in Energy and the English Industrial Revolution, easily accessible and abundant coal goes a long way to explaining why England was able to reach industrialization first.

EROI values also vary depending on what researchers choose to include in the energy input. If you invade a country and ‘liberate’ some of its oil alongside its people then should you include the energy used by all those missiles, drones, and soldiers? These challenges notwithstanding, we can compare EROI calculated using similar approaches to get a sense for the challenge in using various energy sources.

The EROI of coal ranges from around 10 to 80. Think of it like this: 1 lump of coal can get you another 10 to 80 lumps. The EROI of oil and natural gas are much more variable because of the variety of sources, but the EROI has been falling for a century. Consider oil discovery:

In 1919 1 barrel of oil found you at least another 1,000.

In 1950 1 barrel of oil found you another 100.

By 2010 1 barrel of oil found you another 5.

And the number has continued to fall as we move from abundantly available sweet crude to hard-to-refine sources such as tar sands and fracking. This is part of the reason energy prices (and consequently inflation) have risen; but it is not the only reason.

The effective EROI has also been artificially constrained by cooperation between oil-exporting nations such as Saudi Arabia and Kuwait. The Organization of the Petroleum Exporting Countries, more commonly referred to as OPEC, has artificially constrained supply to keep prices high. Their actual EROI and oil availability remain state secrets. We'll discuss this in more detail in Chapter 9.

With the availability and EROI of fossil fuels falling, one suggested path out is to transition to renewable sources of energy, but there's a problem. Indeed many.

The EROI of renewables is much lower than that of fossil fuels. Photovoltaic solar panels are currently in the single digits, typically no higher than 2 to 4, and the higher values are really only when you add a battery. So it costs you 1 watt of electricity to get 2 to 4 watts back. This value may be higher when panels exceed their planned lifespan, but it still requires a large upfront cost.

We are at the early technological stage in solar panels and so prices are falling rapidly, which is reducing that upfront cost. There are, however, fundamental limits on solar efficiency and cost sensitivity to the resources required to build them. Solar panel prices will stabilize and perhaps increase at some point based on the availability and cost of materials such as copper. And we are a long way from building enough panels to replace even our current electricity needs.

To meet the United States’ current electricity consumption would require more solar panels than all the space used by roads in America. That's just the panels and doesn't include batteries, wiring, and other infrastructure. And that's just electricity usage at the moment.

The transition away from directly using fossil fuels such as gasoline in cars or natural gas in homes toward a fully electrified grid, such as by transitioning to electric cars and electric heating, represents a more flexible and efficient energy future. But some estimates suggest that to power this future with solar panels would require solar panels that take up more space than the entire state of California.

Wind too has similar issues. The sun doesn't shine at night, but the wind blows. Yet wind is far more erratic than sunshine and so the EROI of wind is highly variable, from around 4 to 16. Wind, and particularly solar, can play a part in our immediate energy future, and almost certainly must in the distant energy future, but alone, both lack the EROI to transition us to the next level of energy abundance.

In contrast, hydroelectric power, generated by large, fast-flowing rivers spinning a turbine, has an EROI of typically 50 to over 250 depending on the size and gradient of the river. There's very little downside to using hydropower, but it is limited to those countries lucky enough to have large, fast-flowing rivers, such as Canada, where electricity is commonly, and confusingly to non-Canadians, called ‘hydro’. Canada generates 60% of its electricity through its rivers. But EROI isn't the only factor that matters. Other important factors include availability, density of energy, power, and start-up cost. The challenges of transitioning to renewables is made stark when they're contrasted with fossil fuels.

Fossil fuels are nature's batteries of densely stored solar energy. Coal is millions of years of densely stored sunlight in the form of plant material (peat) turned to black rock, about twice as energy dense as wood, which is merely a tree's energy surplus over its lifetime. Oil and natural gas are millions of years’ worth of densely stored sunlight in the form of algae and zooplankton pressure-cooked into both oil and natural gas. Heat and pressure have made them dense, transportable batteries.

One active area of research is how to store solar and wind energy in some kind of artificial battery or fuel. There are many potential solutions, from a chemical battery of some kind, similar to what powers your electronic devices and electric car, to pumping water uphill and storing the energy as gravitational potential energy, ready to be drained by letting the water flow back downhill. One promising idea is the use of solar energy to generate hydrogen by splitting water – H₂O. This approach requires sunlight and water but has geopolitical advantages over chemical batteries. Any country – even those without the rare metals needed to make chemical batteries – can produce hydrogen in this manner.

We are currently like early life with little ability to store and distribute the power of the giant fusion reactor in the sky – the Sun. We are waiting for the modern ATP battery revolution. Remember, early life took millions of years to charge those dense fossil-fuel batteries. We have been burning through those batteries in a matter of centuries. The low density of artificial batteries is a major challenge for renewables.

We require more energy-dense batteries to be able to transport large amounts of energy and release them with sufficient power (energy per second) needed for many tasks. Electric cars are more viable than electric planes because cars can carry heavier, less energy-dense batteries than planes, which need to lift those batteries off the ground. No amount of horses could power a plane nor could current batteries power anything more than a light aircraft or drone. Even though the energy transfer from batteries is more efficient than burning gasoline, jet fuel is much more energy dense and able to release sufficient power for an A380 to carry almost 1,000 people across the Atlantic.

Energy return on investment for various electricity-generating power plants. Based on data and graph from: D. Weißbach, G. Ruprecht, A. Huke, K. Czerski, S. Gottlieb, and A. Hussein, (2013), ‘Energy Intensities, EROIs (Energy Returned on Invested), and Energy Payback Times of Electricity Generating Power Plants’, *Energy*, 52, 210–21.

The final major challenge with transitioning from fossil fuels to renewables is the start-up cost. A lot of energy and rare resources are required to build those wind turbines and in particular those solar panels. The availability and already low EROI of renewables mean that that initial investment in energy takes a long time to pay off. It's the same trade-off we face in using solar panels in our homes.

My mother, Shanthi, who lives in Queensland, Australia, is very fond of the solar panels on her roof, which now generate enough electricity for her needs and sometimes generate power back to the grid, turning her a small profit. But even in sunny Queensland, with 300 days of bright sunshine every year, it took years before her subsidized initial investment was paid off. Some households can afford to do this, but at a national level an initial investment in subsidies or solar power for a whole population requires a massive upfront investment. That effectively means less energy for other productive parts of the economy, which can lead to inflation and a rise in prices and cost of living at first.

Quality of life and actual wealth in terms of what we can do beyond survival is a function of excess energy, which is in turn a function of EROI and energy source availability. And so an upfront payment for renewables from our quickly falling excess energy budget will require tightening our collective belts in the meantime. In other words, it means a reduction in current productivity in other sectors – less energy for farms, hospitals, and heating homes, not to mention holidays and other leisure activities. Ultimately that means your energy bills go up while we make the transition. This debt reduces overall national wealth and drives up inflation. In the second half of this book we'll discuss in more detail the relationship between energy, money, and upfront subsidies, and how reductions in overall wealth lead to dissatisfaction and lower cooperation, both of which make people harder to govern.

These are not unsolvable problems, but they do need to be solved. We cannot ignore either the fundamental physics of energy sources or the fundamental social challenge of governance and continued cooperation. These are fundamental laws of life that have applied long before the arrival of Sapiens.

The total energy available to humans is the availability of different energy sources multiplied by their EROI. For low EROI sources such as solar, this means large tracts of land dedicated to harnessing the energy of our sun, which comes with both a material cost to build those solar panels and at an ecological cost to the land used. Renewables won't substantially increase our energy budgets. Apart from an initial energy and resource cost, renewables are also going to require a lot of innovation. But innovation too is a function of available energy.

The law of innovation

In the brief history of everything earlier in this chapter, we saw that the first major energy revolution was the photosynthetic innovation. As abundant sunlight fell on Earth, photosynthesis offered a way to store the sun's energy in chemical form for later use. Remember that energy is what makes matter move as life, and so if you can store energy then you can do bigger things. It's like saving money to buy something more expensive. Storage also requires a surplus of energy. That surplus can then be focused to harness a more energy-dense and abundant source with a higher EROI.

For humans, the earliest unlocking of energy was fire. Fire allowed us to burn one organism (dead trees) to unlock the energy of another (the chemical energy in the calories of food). Trees are dense, stored solar energy that can be unlocked through oxidation in fire. The dense trees of the past also had more energy than current less-dense, fast-growing varieties. Humans used this wood energy to stay warm, ward off predators, and cook.

Cooking is a process of pre-digestion whereby external energy is used to break down the molecules in meat and vegetables, predigesting them to save the mechanical movement of our teeth, the synthesizing of stomach acids, and the hosting of microbiome bacteria that would otherwise take more energy and more time to do the hard work, lowering our EROI from food. Our species needed the extra energy that cooking unlocked because it had one very energy-expensive organ: our brain.

Our brains are incredibly energy expensive. At rest, the brain uses as much energy as all your muscles do. Indeed, 1 gram of brain tissue uses twenty times more energy than 1 gram of muscle tissue.

Cooking saved us from sitting there like gorillas chewing plants all day or needing four stomachs like a cow munching on grass. We reduced the size of our gut and lost a lot of muscle, saving us a lot of energy. We used that extra energy to fuel a larger brain. What did we do with that larger brain? We learned more useful stuff, including figuring out how to hunt larger, higher EROI animals. Rather than just hunting hare or scrounging for grubs, we could focus on large animals like stag, bison, or mammoth.

Meat is the original superfood, offering a denser energy source than plants. When eaten from nose to tail, organs and all, not just the muscle meat typically eaten in the West, it also provides a dense source of all the nutrients you need, literally stealing all the things an animal needs by taking it from another animal's whole body. We figured out better techniques for making hunting and gathering more efficient, offering us more time to continue innovating. And eventually, we figured out a better way to get food: farming.

Agriculture was the next major unlocking of energy after fire. We switched from hunting and gathering to harvesting and grinding. Hunting, gathering, and cooking food with fire had a better EROI than eating raw food and digesting it inside our bodies, but we still had to expend energy wandering the plains trying to find plants that wouldn't poison us and hunting animals that didn't want to be eaten. As anyone who hunts or fishes knows, returns are uncertain. Agriculture, in contrast, meant efficiently turning areas of earth into food production. It was a solar technology, efficiently exploiting the energy of the sun to multiply our growing efforts. It was still laborious, but it was also a more reliable and higher EROI source of calories. We continued innovating and made the process so efficient that we created a bit more excess energy.

What did we do with that excess energy? We funneled it into creating more people and domesticating a higher EROI food source: other animals. Instead of just farming plants, we farmed animals. Those animals could not only be eaten but, with enough excess plant energy, could be put to work to help plow and create more food for us. Horses, in particular, also allowed us to travel faster and further, shrinking the world and helping us share ideas to further innovation. Agriculture and domestication co-evolved.

Just as the cultural innovation of fire unlocked more energy, the cultural innovations of agriculture and domestication gave us a reliable, if less diverse, food supply. Relative to hunter-gatherers, agriculturalists were – individually speaking – unhealthier and shorter in both stature and lifespan. Living in higher-density settlements alongside animals and eating nothing but grains isn't great for you. But agriculturalists’ larger, more reliable food supply allowed them to expand their populations at an unprecedented rate.

Just as photosynthetic prokaryotes were exploited by other prokaryotes who were exploited by eukaryotes who were exploited by complex eukaryotes who were exploited by cooperative groups of eukaryotes, hunter-gatherers were outcompeted by the agriculturalists around them, pushing them to ecological niches less suitable for agriculture – deserts or thick forests – where even today the few remaining hunter-gatherers still live. Soon agriculture became the dominant form of subsistence. But as these agricultural groups grew in number and size relative to their agricultural output, abundance turned to scarcity. As the number of people rose, the amount of food per person decreased.

This was doubly challenging because innovations meant that fewer people were needed for farming as animals and implements made farming more efficient. So agriculturalists began to compete among their own groups and with other agriculturalists, stealing land, crops, animals, and even people. People taken from other groups could be made slaves, paid the minimum in lifestyle and food, leading to higher EROI for the enslavers (though not for the population as a whole). This continued till the next energy revolution, which would finally break us out of this Malthusian world of scarcity, violence, and conflict: the Industrial Revolution.

The Industrial Revolution of the eighteenth century made us even more efficient. Instead of burning wood like agriculturalists, we began to burn up millions of years of fossil fuels in factories that produced at a pace that would have required thousands or millions of people without them. From Henry Ford to the Toyota Way to Tesla's robots, we continued to make those factories more efficient. We also used fossil fuels to innovate efficiencies in food production.

In the mid twentieth century we launched a second agricultural revolution on the back of fossil fuels: the Green Revolution. We not only mechanized farming through fossil-fueled farming machinery but also learned how to turn that ancient fossil life into new life by turning it into fertilizers and pesticides, making farms far more productive. This led to an abundance of food, reduction in poverty and famine, increased income, higher child survival rates, and a doubling of the human population. Half the human population owe their lives and all of us owe our current standard of living to this second agricultural revolution. In 1970 the father of the Green Revolution, Norman Borlaug, won the Nobel Peace Prize.

Each of these revolutions led to new social organizations. Some hunter-gatherer groups blessed with abundant resources developed property rights and hierarchical societies, but it was really with the abundance of agriculture that these features of society became commonplace.

Excess resources meant storage. Storage meant having something that needed ownership. Owning something meant protecting it from people who would like to take it from you. Remember the prokaryotes and eukaryotes? It's not uniquely human greed, it's inevitable. Ownership and property rights increased productivity as people competed with one another to own more. And differences in ownership meant increased inequality and higher rates of violence over these stored resources. This in turn led to hierarchies and governments and greater divisions of information and labor. And in turn to innovations through intellectual arbitrage, the cultural equivalent of genetic recombination. Just as we combined genes to create new people, we started combining ideas to create new innovations. As Matt Ridley puts it, ‘ideas had sex’.

Cultural evolution explored different norms, institutions, and political systems; new ways of cooperating but also new ways of competing and exploiting each other. But nothing in life is done alone.

Our greatest achievements and our worst atrocities are all cooperative acts. As energy becomes efficiently accessed, captured, and controlled, new niches are opened for larger units of organisms and organizations to come together to exploit energy. To do that, we needed to work together. We needed to cooperate.

The law of cooperation

Cooperation increases as organisms and societies discover new energy sources and learn to efficiently access and use them, which requires working together. More abundant, high-density, high-powered energy sources with higher EROI lead to a corresponding increase in the complexity and scale of cooperation. This increasing scale happens because the potential pay-offs are higher and it may be worth working together with others to access that reward. The reward is large enough that even if it's shared, it's still worth working with others. With energy up for grabs, smaller units enmesh as larger wholes with aligned incentives.

Organelles comprise cells, cells comprise organisms, organisms comprise colonies, colonies comprise complex societies. People come together in tribes and raiding parties. Regions come together in countries. Countries come together in unions. But for incentives to align there must be a reward for all parties.

We work together at a level that allows us to reliably access energy rewards that when divided up by the number of workers (or cells) are greater than what could be accessed by working alone, in a smaller group, or in a larger group. When a new energy source is unlocked it leads to new innovations and new abundance. But as populations grow thanks to these resources, abundance turns to scarcity.

Energy access often requires a certain size and complexity: a certain number of people to mine the ore, to build the pipelines, to work the oilfields, to ship the oil, to protect and to provide infrastructure around the entire ecosystem-like enterprise. But a positive EROI means excess energy beyond these energy costs, increasing what biologists call a carrying capacity – the maximum number of people that can be sustained. The human carrying capacity vastly increased with the Green Revolution, and our population began to catch up.

When I was born, in the late 1980s, there were only 5 billion people on the planet. We have since added another 3 billion people. More people can mean more innovation and progress, but only if those people have opportunities to express their full potential; only if they can join and participate in our collective brains and proportionally expand the space of the possible. If they do not and the space stays the same, then energy per person decreases. And when this happens a new scarcity and new conflict are inevitable: poverty, violence, and war.

The law of innovation leads to greater efficiency in energy use, which means fewer people are needed for the same energy return. Innovations can make people redundant for the energy economy. Today, with mechanized, fossil-fueled farming, fewer farmers are needed than in the past, but this was also true with past innovations and will be true of future innovations. This means that even with fewer people we can return the same or more energy per person. For this reason, the energy available per person can go up after a war or plague.

In the fourteenth century the Black Death killed a third of Europe. Rather than devastating the continent, resources per person went up for the survivors. In turn, feudalism was weakened, wages increased, and a new middle class and new social order emerged. After the Black Death the land still needed to be worked and the fewer workers alive had more bargaining power, but with innovations in efficiency fewer people were required to work the land. This in turn led to higher wages, higher life expectancy, greater equality, and a weakened aristocracy. In turn, this may have directly led to the Renaissance. Indeed, it may have contributed to Europe's Scientific Revolution, Enlightenment, and eventually the Industrial Revolution.

Similar patterns have occurred throughout history. The dearth of men during the two world wars of the twentieth century may have led to greater gender equality as women entered the workforce. Right now, efficiencies in artificial intelligence and automation are once again increasing efficiency and creating inequality as far fewer people are needed for the same productivity. AI workers are entering the economy. Those workers require vast amounts of energy for the computer servers needed to train them, but, once trained, they can be replicated and work for less energy – and money – than a human performing the same task. These AI workers are owned by a smaller group of people, which means that the fruits of production at the same or even a higher level can be controlled by a smaller number of people. These few individuals increase their energy rewards because other people are now redundant in the energy economy. But falling energy availability and EROI shrinks the space of the possible.

Clearly there's a limit to this redundancy. We still need a minimum number of people to extract energy and resources and to create the economy that surrounds and enables its efficient functioning. Take power plants for example. By one estimate, there is an almost perfect correlation (r = 0.98) between the worker years (how many workers and the time it takes) needed for construction of a plant and power-plant capacity (how much electricity is generated when the plant is running on a full load). But that's just the minimum for the energy portion of the economy. It is the excess energy that leads to true human wealth and a high quality of life.

In an ideal world, only a tiny fraction of our economy is dedicated to energy, because the energy returns mean that there is enough excess energy to support everything else in life. It's counterintuitive, but a growing energy sector is an indication of falling EROI, falling excess energy availability, and falling quality of life.

The laws of energy, innovation, and cooperation create an inexorable cyclical pattern. First, a new energy source increases the carrying capacity of our population. The energy ceiling is raised. This in turn creates positive-sum conditions that incentivize people to cooperate at a high enough scale to access that new source of energy. The higher cooperation leads to greater innovative capacity, which in turn leads to new efficiencies to do more with less energy. Those innovations in efficiency can lead to fewer people being required for the energy sector. The rest can simply enjoy the excess energy returns and use it to make life better.

But since these efficiencies mean that fewer people are required to access the same amount of energy, smaller scales of cooperation – feudalism, aristocracies, oligarchies, or corrupt cabals – emerge trying to control that wealth. This in turn leads to fewer opportunities for many people, reducing human potential, reducing quality of life, and reducing innovative and cooperative capacity.

As populations grow but the space of the possible does not proportionally grow or even shrinks because of lower innovation or no transition to the next energy level, so abundance turns to scarcity. What we call zero-sum conditions dominate.

Zero-sum conditions, in contrast to positive-sum conditions, are those where another's success predicts your loss – win-lose rather than win-win – for example, when jobs, contracts, or university places are limited. When conditions are zero-sum, you are incentivized to harm others, because their failure is your success. If someone else doesn't get the job, you might, so why would you want them to get it?

Positive-sum conditions are those where another's success predicts your success, such as during economic booms. You can get what they're getting by doing the same thing. If the coffee business is booming, you can also start a Starbucks.

Zero-sum and positive-sum conditions incentivize very different psychologies. Zero-sum conditions incentivize destructive competition as people or groups undermine one another. Positive-sum conditions incentivize productive competition as people compete and innovate to capture the abundant resources.

Excess energy, which can be measured as cheap energy, leads to economic booms. Less energy, which can be measured as a spike in energy prices, leads to recessions. These affect our psychology, behavior, and tendency to cooperate.

It's easier to be nice when there's more to go around.

Consider this analogy. Imagine yourself waiting for a bus. Let's treat the rate of buses and availability of seats as the total energy available. Let's assume buses arrive every five minutes and there's plenty of space available for everyone. As people find the service convenient, more people begin to turn up. If there are plenty of seats available, you might graciously let someone ahead of you in the queue. Even if you miss out, there will be another bus in five minutes. There may be mumblings and grumblings about the 1% with special passes that always get to the front of the line or about people favoring their friends or ingroups and letting them into the queue ahead of you. But it's only mumbling and grumbling as long as there are seats available. Eventually, the number of people begins to meet the number of seats available and it becomes harder to get a seat than it once was. Imagine now that the frequency of buses slows down – one an hour, one a day. Bus seats per person, which in our analogy represents energy per person, is decreasing, but the number of people matches the old carrying capacity. What was once mumbling and grumbling erupts into something more hostile.

In a society, such zero-sum conditions manifest as good publicly funded schools become harder to get into or less well funded, as waiting times at hospitals increase or quality of health care decreases, as well-paid jobs become more difficult to find or require more work. Local populations can become understandably resentful of these new pressures, and more resentful still when their existing resources are deployed to help newcomers.

It's not so much about inequality as equality of opportunity. Research reveals that people don't necessarily expect equality, but they do want fairness. Many people don't mind the special bus passes as long as they can get one at some point, perhaps as they get older or if they work harder. People don't mind others ahead of them in the line as long as they can get a seat if they choose to wake up earlier to get to the bus stop. But if a better life seems improbable no matter what you do; if people wake up to the idea that not being a millionaire is not a temporary embarrassment but a ceiling on their progress due to the happenstance of their birth; when who you are and not what you can do limits what you achieve – then cooperation is threatened. When this happens, the ties that bind us start to unravel.

We cooperate to compete, compete by cooperating; cooperation and conflict are two sides of the same coin. Cooperation and conflict lead to innovations and occasionally to breakthroughs in our total energy budget. These possibilities and configurations are not deliberate human designs or decisions; they are explorations in the constrained space of the possible. Explorations through the law of evolution.

The law of evolution

Charles Darwin, the father of evolution, was a pigeon breeder. And as a pigeon breeder he was well aware of how artificial selection could change the traits of an animal or plant. Through artificial selection humans turned a wolf into a poodle, grasses into wheat and other cereals, and one mustard plant into broccoli, Brussels sprouts, cabbage, kale, cauliflower, kohlrabi, and gai lan. In all these cases, human intelligence is doing the selecting on preferred traits – artificially.

In life's quest for energy and efficiency through innovation and cooperation, three simple ingredients decide the scale of cooperation and the winners of conflicts: diversity, transmission, and selection. With these three ingredients, systems will inevitably converge on adaptive solutions – the law of evolution.

The genius in Darwin's theory of natural selection wasn't in the selection. It was in the natural. The realization that nature could do the selection if, in the competition for resources and energy, some survived better than others. That an organism's survival depended on its particular transmissible physiology, cognition, and behavior. But what are these traits trying to do?

Part of Darwin's great insight came from reading Thomas Malthus. Malthus argued that because animals reproduced faster than plants could grow, at some point the animal population would outstrip their food supply. We can now see that the plant population has an energy availability and EROI that imposes a carrying capacity on the herbivore population, which in turn has an EROI that imposes a carrying capacity on the size of the carnivore population. Each energy source leads to abundance and then scarcity.

Darwin's insight is that scarcity increases the strength of selection; that those who survive and thrive are those with the physiology, cognition, and behavior that leads to the highest energy returns. This might be by accessing a new food source more efficiently or by reducing energy requirements. Indeed, it is likely to be how some human populations evolved the genetic ability to drink milk and digest lactose beyond childhood – something that most humans and no other mammal can do. Famines may have provided the necessary selection pressure. Those with a mutation that led to lactose tolerance were able to access more calories from milk during these hard times.

By this same logic we can also now see how fossil fuels allowed us to escape the Malthusian trap – at least until scarcity catches up with us as our populations grow and nature's batteries deplete. We either fall back into the Malthusian trap of continual conflict once more or we move on to the next greater energy source toward abundance.

The EROI of fossil fuels is falling and availability is decreasing. The ceiling is coming down and the walls are closing in. We're all starting to feel the squeeze. Although we can't always articulate it, we can feel that there's less space and opportunity than there once was. Innovation is needed. But not just in efficiency. Our current energy is running out. The space of the possible has shrunk. To return to a win-win positive-sum world of excess energy, abundance, and high energy rewards per person, we need innovations in the energy technologies themselves. Without these innovations, our future looks bleak.

A hint of what's to come

When we first discovered oil, we only used the kerosene and wasted the rest. We literally burned off the natural gas, gasoline, and other non-kerosene products as useless waste. It's horrifying in hindsight. But over time competition led to greater efficiency. Just as our light bulbs became more energy efficient so too did everything else.

When a new energy source is discovered, initially we're not good at using it. Then organisms and organizations such as cells and societies learn to access and use the energy more efficiently, increasing the EROI of a given energy source – as is currently happening with solar panels. After an efficiency limit is reached the EROI either remains roughly the same – as in the case of hydropower (as long as the river keeps flowing), geothermal (as long as there is geothermal activity), and nuclear fusion (because the fuel is effectively unlimited). In other cases, if the energy source becomes more difficult to access then efficiency once again decreases.

Early innovations have larger efficiency gains, but then efficiency gains slow down and continued growth and progress require new, larger sources of energy or breakthroughs in efficiency. As we shall see, this arrival at carrying capacity and slowdown in innovation is where we are in the human story: the Great Stagnation as described by economist Tyler Cowen.

Entrepreneurship, engineering, and economics mostly exist to service the law of innovation. Entrepreneurs disrupt inefficiencies and, in doing so, create more efficient systems. Engineers develop technologies that allow you to do more, better, and/or more efficiently. And economists look at how to efficiently allocate scarce resources.

Innovations in efficiency are why Jeff Bezos is so rich. You can't beat two-day, one-day, or even same-day shipping, a massive marketplace, and easy customer returns. Amazon had several efficient innovations that allowed it to, first, outcompete bookshops, then strip shopping malls and high streets, and then web servers. Amazon Web Services (AWS) is now the largest web service and cloud computing platform and has become the most profitable part of Amazon's business. These innovations emerged from an evolutionary marketplace that once contained many now extinct competitors and competing products.

But all these innovations in efficiency are fundamentally different from innovations in energy. While they also expand the space of the possible by doing more with less, they are the equivalent of finding a bargain or being more frugal, which is fundamentally different from increasing your salary. Increasing your income always beats reducing your expenses.

As the sun sets on the era of fossil fuels, we need to prepare for tomorrow.

Many people push for a future based on renewable energy sources. Innovations in battery technologies and a sufficient energy surplus to pay the large start-up costs may lead to renewable sources meeting the current demands of our energy-hungry civilization. Perhaps even our immediate future demands. In the more distant future, the astonishing amount of energy released by the sun means that solar technologies in particular have the ability to far exceed our needs.

Physicist Freeman Dyson once proposed the idea of a Dyson sphere – a megastructure encircling the sun and capturing a large percentage of its energy to meet the energy needs of our spacefaring descendants. A Dyson sphere or the more modest but still distant Dyson swarm or Dyson ring would allow us to reach fantastic levels of energy abundance. We're a long way from a Dyson anything, but the low EROI of solar means a lot of material is needed to build all the solar panels we need. That requires a massive start-up cost in energy and resources we simply don't have in Earth's discretionary budget. A fully solar future is not within reach of our current energy budget. Even if we were willing to pay the start-up cost in our lifestyles, the shrinking space of the possible means that in the not-so-distant future our quality of life would continue to get worse. Proposals that require coercive population control not only require violence but will continue stagnation in innovation and further shrink the space of the possible. In effect, from where we are today, solar, wind, or any other renewable sources are insufficient to reach a new level of energy abundance.

The power of the sun

If you survey every energy source within our current or close technological capabilities, one stands out as having the necessary numbers to radically lift the human energy ceiling and enter the next level of abundance: nuclear.

Current nuclear fission technologies have abundant fuel and an EROI of 75. Nuclear fission exploits the enormous amounts of compressed energy created by massive supernovas and neutron-star mergers as they fused smaller elements into heavier elements such as uranium and plutonium. When these elements split, they release vast amounts of energy. As Einstein's equation E = mc² tells us, the loss of mass gets multiplied by the enormous number that is the speed of light (299,792,458 m/s), which is even larger when multiplied by itself in the squared term (9.0 x 10∧16). That's the amount of energy you get back. Nuclear fission is more plentiful, better for the environment, and has a higher EROI than any fossil fuel.

Nuclear fission is a good bet for the immediate to medium future; it ticks all the boxes in terms of availability, density, EROI, power, and start-up cost relative to return. It does, however, suffer from at least two challenges. But they're not what many people assume, the problems of nuclear waste and safety having been largely solved in modern reactors.

Nuclear waste is small because nuclear fuel is incredibly dense. The incredible devastation caused by the bomb dropped on Hiroshima was the result of just 64 kilograms of uranium. The bomb dropped on Nagasaki contained just 6 kilograms of plutonium. One ton of coal has about the same energy as 120 gallons of oil, both of which have the same amount of energy as a 1-inch enriched uranium pellet. The waste from nuclear reactors can be reused in other reactors that run on spent fuel, or can be placed in dry storage containers. These containers are lined with just twenty inches of concrete encased in half an inch of steel, which is more than enough of a barrier to stand next to a container without the need for special protective equipment. Indeed, in the Netherlands, you can sign up for a tour of the COVRA nuclear waste facility to see and stand next to the spent fuel containers yourself – such openness helps increase public trust and dispel fears. Depleted uranium, which is about one and a half times as dense as lead, is about as harmful as lead – don't eat it! Its radioactivity is lower than even unenriched uranium ore and doesn't penetrate human tissue. It's used in armor-piercing projectiles and in hospital radiation shielding. If Superman can't see through lead, he definitely can't see through depleted uranium.

Safety has also vastly improved, in a variety of ways. The three major nuclear power plant incidents – Chernobyl, Three Mile Island, and Fukushima – all used early technology in the form of pressurized, boiling-water reactors, which, as a friend in the nuclear industry aptly described, are giant, pressurized kettles where the water used to generate the power and the water circulating the heat from the reactors mingle in a sealed unit inherently less safe than even the next generation of nuclear plants that followed. In contrast, now even old reactors developed in the late twentieth century, such as Canada's CANDU reactors, are much safer, with features such as separation of the water heated by the nuclear reaction from the water used to turn the turbines that generate the electricity. By using heavy water, it is also possible to use unenriched uranium, recycle spent fuel, or use other fuels such as weakly radioactive thorium.

Even more modern reactor designs are smaller, safer, and more flexible. There are many small modular reactor designs (SMRs), which can be about the size of a football field or two, and even smaller micro-reactors of the kind currently used in nuclear submarines and aircraft carriers. Micro-reactors range in size, from a car to a shipping container. In addition to generating power on Earth, they will play an essential role in space travel and mining other planets and asteroids. To judge the safety of present and future nuclear power plant designs based on our earliest designs from the 1950s would be similar to judging cars or airplanes as unsafe based on early models from that period.

In the United States in the 1950s there were around 60 to 70 deaths per billion miles travelled in cars. Today that number is 11 deaths per billion miles. In the 1950s, for every 10 million flights, over 400 resulted in fatalities. Today, that number is just 1 fatality for every 10 million flights.

Newer cars have become increasingly safe with the adoption of seat belts, airbags, crumple zones, ABS brakes, stability and traction control, and lane-keeping, and various accident-avoidance systems. So too in airplanes. And so too in nuclear technology.

There are, however, other real challenges to be overcome.

The first major challenge is nuclear proliferation. Given low levels of good governance and high probabilities of conflict in many countries, are Yemen or Zimbabwe ready for nuclear reactors? We will return to this thorny problem later.

The second major challenge to nuclear fission is the high cost of new nuclear reactors. Unlike many technologies, nuclear power plants have become more expensive and take a long time to build. This is in part due to regulations and in part due to insufficient innovation driven by fears of an earlier generation. We would be much better off today in terms of wealth and quality of life if we had pursued a nuclear future in the twentieth century.

Regulation is part of what ensures modern nuclear safety, but, as with the automobile industry, regulation is an area that is eminently open to innovation in the quest for reduced costs while still ensuring safety. The flexible SMR and micro-reactor designs also reduce this cost, increasing flexibility and scalability compared to current large monolithic nuclear reactor designs.

Despite these challenges, a mix of solar and nuclear fission in the future is both necessary and achievable. At a fundamental level, nuclear has the necessary physical properties to meet our energy needs this century. Greater investment and innovation in nuclear technologies alongside innovation in solar are the next step for humanity. But nuclear fission is not the next level of energy abundance. It will not substantially change our energy budgets in a way that will allow us to scalably explore the stars or mine asteroids for all those rare metals we need in the coming century.

To reach the next level of abundance we need nuclear fusion, the process that stars like our sun use to unlock energy. Fusion is the source of energy that has allowed for all life on this planet, that solar panels are harnessing, and that was turned into chemical energy through photosynthesis and stored in fossil fuels. It is the power of the sun.

In nuclear fusion, rather than splitting atoms, we combine them – two hydrogen atoms are fused into helium, releasing far more energy than when large elements are split in nuclear fission. Nuclear fusion has the potential to move us into effectively unlimited energy and permanent abundance. Fusion is clean and safe with no radioactive waste. It also uses the most abundant fuel in the universe – hydrogen. Although much innovation is required to increase the EROI of fusion, a nuclear-fusion-fueled future has effectively no ceiling. Were we to achieve fusion, we would have energy to desalinate our oceans to provide clean water, create new rivers and seas, mine asteroids for rare resources, and perhaps build that solar-paneled Dyson structure for our descendants. So when do we get fusion?

The arrival of fusion is perpetually somewhere between next Monday and the next thirty years. But we have little reason to believe it's anything other than a matter of when, not if. Nonetheless, there are many problems, some of which may prove more challenging than we expected. For example, nuclear fusion reactions require the rarer hydrogen isotope tritium, which has two neutrons unstably bound to the single proton. Tritium is rare. But for all these challenges, theoretical solutions exist. For example, our current conventional fission nuclear reactors, in addition to being major producers of the medical isotopes needed to diagnose and treat cancer, also produce tritium as a by-product. On a visit to a nuclear reactor, tritium was one of the particles I was constantly monitored for. Nuclear fusion reactors can also continually breed tritium during the fusion reaction through contact with a lithium ‘breeding blanket’.

New advances and record outputs in the last decade have led, for the first time, to a burgeoning start-up industry in nuclear fusion firms, both private and state sponsored. Each company is pursuing different promising technologies with billions in funding. Nonetheless, energy scientist Vaclav Smil – much admired by Bill Gates – estimates that nuclear fusion is unlikely to replace current energy production any time before mid-century – 2050.

Nuclear fusion is going to require a lot of investment, innovation, and technological advancement, but, as we will see, many of the barriers to breaching then forever surpassing the next energy level are not physical or technological but rather social, economic, and psychological. Overcoming these challenges will be the largest return on investment in the history of our species.

Once we reach the next fusion-fueled energy level, we will enter a new era of peace and prosperity. It will make our current era, with all its conflicts, seem to our descendants as primitive and barbaric as we see the Middle Ages with its superstitions, witch burning, and horrifyingly brutal wars of conquest.

To solve the problem, we must first see it. To see it, we must under-stand our periodic table, our theory of everyone. We must understand how the laws of life created the human animal, our intelligence, innovation, ability to work together, and every aspect of our lives. Only then will it be obvious what needs to be done to reach the next levels of innovation, cooperation, and abundance.