INTRODUCTION THE WORLD AS WE KNOW IT HAS ENDED. A particularly virulent strain of avian flu finally breached the species barrier and hopped successfully to human hosts, or was deliberately released in an act of bioterrorism. The contagion spread devastatingly quickly in the modern age of high-density cities and intercontinental air travel, and killed a large proportion of the global population before any effective immunization or even quarantine orders could be implemented. Or tensions between India and Pakistan reached the breaking point and a border dispute escalated beyond all rational limits, culminating in the use of nuclear weapons. The warheads' distinctive electromagnetic pulses were detected by defense surveillance in China and triggered a round of preemptive launches against the United States, which in turn spurred retaliatory strikes by America and its allies in Europe and Israel. Major cities worldwide were reduced to jagged plains of radioactive glass. The enormous volumes of dust and ash injected into the atmosphere reduced the amount of sunlight reaching the ground, causing a decades-long nuclear winter, the collapse of agriculture, and global famine. Or the event was entirely beyond human control. A rocky asteroid, only around a mile across, slammed into the Earth and fatally changed atmospheric conditions. People within a few hundred kilometers of ground zero were dispatched in an instant by the blast wave of intense heat and pressure, and from that point on most of the rest of humanity was living on borrowed time. It didn't really matter which nation was struck: the rock and dust hurled up high into the atmosphere--as well as the smoke produced by widespread fires ignited by the heat blast--dispersed on the winds to smother the entire planet. As in a nuclear winter, global temperatures dropped enough to cause worldwide crop failures and massive famine. This is the stuff of so many novels and films featuring post-apocalyptic worlds. The immediate aftermath is often--as in Mad Max or Cormac McCarthy's novel The Road --portrayed as barren and violent. Roving bands of scavengers hoard the remaining food and prey ruthlessly on those less well organized or armed. I suspect that, at least for a period after the initial shock of collapse, this might not be too far from the truth. I'm an optimist, though: I think morality and rationality would ultimately prevail, and settlement and rebuilding begin. The world as we know it has ended. The crucial question is: now what? Once the survivors have come to terms with their predicament--the collapse of the entire infrastructure that previously supported their lives--what can they do to rise from the ashes to ensure they thrive in the long term? What crucial knowledge would they need to recover as rapidly as possible? This is a survivors' guidebook. Not one just concerned with keeping people alive in the weeks after the Fall--plenty of handbooks have been written on survival skills--but one that teaches how to orchestrate the rebuilding of a technologically advanced civilization. If you suddenly found yourself without a working example, could you explain how to build an internal combustion engine, or a clock, or a microscope? Or, even more basic, how to successfully cultivate crops and make clothes? The apocalyptic scenarios I'm presenting here are also the starting point for a thought experiment: they are a vehicle for examining the fundamentals of science and technology, which, as knowledge becomes ever more specialized, feel very remote to most of us. People living in developed nations have become disconnected from the everyday processes of civilization that support them. Individually, we are astoundingly ignorant of even the basics of the production of food, shelter, clothes, medicine, materials, or vital substances. Our survival skills have atrophied to the point that much of humanity would be incapable of sustaining itself if the life-support system of modern civilization failed, if food no longer magically appeared on store shelves, or clothes on hangers. Of course, there was a time when everyone was a survivalist, with a far more intimate connection to the land and methods of production, and to survive in a post-apocalyptic world you'd need to turn back the clock and relearn these core skills.* What's more, each piece of modern technology we take for granted requires an enormous support network of other technologies. There's much more to making an iPhone than knowing the design and materials of each of its components. The device sits as the capstone on the very tip of a vast pyramid of enabling technologies: the mining and refining of the rare element indium for the touch screen, high-precision photolithographic manufacturing of microscopic circuitry in the computing processor chips, and the incredibly miniaturized components in the microphone, not to mention the network of cell phone towers and other infrastructure necessary to maintain telecommunications and the functioning of the phone. The first generation born after the Fall would find the internal mechanisms of a modern phone absolutely inscrutable, the pathways of its microchip circuits invisibly small to the human eye and their purpose utterly mysterious. The sci-fi author Arthur C. Clarke said in 1961 that any sufficiently advanced technology is indistinguishable from magic. In the aftermath of the Fall, the rub is that this miraculous technology would have belonged not to some star-faring alien species, but to people just a generation in our own past. Even quotidian artifacts of our civilization that aren't particularly high-tech still require a diversity of raw materials that must be mined or otherwise gathered, processed in specialized plants, and assembled in a manufacturing facility. And all of this in turn relies on electrical power stations and transport over great distances. This point is made very eloquently in Leonard E. Read's 1958 essay written from the perspective of one of our most basic tools, "I, Pencil." The astounding conclusion is that because the sourcing of raw materials and the methods of production are so dispersed, there is not a single person on the face of the Earth who knows how to make even this simplest of implements. A potent demonstration of the gulf that now separates our individual capabilities and the production of even simple gizmos in our everyday life was offered by Thomas Thwaites when, in 2008, he attempted to make a toaster from scratch while studying for his MA at the Royal College of Art. He reverse-engineered a cheap toaster down to its barest essentials--iron frame, mica-mineral insulating sheets, nickel heating filaments, copper wires and plug, and plastic casing--and then sourced all the raw materials himself, digging them out of the ground in quarries and mines. He also looked up simpler, historical metallurgical techniques, referring to a sixteenth-century text to build a rudimentary iron-smelting furnace using a metal trash can, barbecue coals, and a leaf blower for bellows. The finished model is satisfyingly primitive but also grotesquely beautiful in its own right and neatly underscores the core of our problem. Of course, even in one of the extreme doomsday scenarios, groups of survivors would not need to become self-sufficient immediately. If the great majority of the population succumbed to an aggressive virus, there would still be vast resources left behind. The supermarkets would remain stocked with plentiful food, and you could pick up a fine new set of designer clothes from the deserted department stores or liberate from the showroom the sports car you've always dreamed about. Find an abandoned mansion, and with a little foraging it wouldn't be too hard to salvage some mobile diesel generators to keep the lighting, heating, and appliances running. Underground lakes of fuel remain beneath gas stations, sufficient to keep your new home and car functioning for a significant period. In fact, small groups of survivors could probably live pretty comfortably in the immediate aftermath of the Fall. For a while, civilization could coast on its own momentum. The survivors would find themselves surrounded by a wealth of resources there for the taking: a bountiful Garden of Eden. But the Garden is rotting. Food, clothes, medicines, machinery, and other technology inexorably decompose, decay, deteriorate, and degrade over time. The survivors are provided with nothing more than a grace period. With the collapse of civilization and the sudden arrest of key processes--gathering raw materials, refining and manufacturing, transportation and distribution--the hourglass is inverted and the sand steadily drains away. The remnants provide nothing more than a safety buffer to ease the transition to the moment when harvesting and manufacturing must begin anew. A REBOOT MANUAL The most profound problem facing survivors is that human knowledge is collective, distributed across the population. No one individual knows enough to keep the vital processes of society going. Even if a skilled technician from a steel foundry survived, he would only know the details of his job, not the subsets of knowledge possessed by other workers at the foundry that are vital for keeping it running--let alone how to mine iron ore or provide electricity to keep the plant operating. The most visible technology we use daily is just the tip of a vast iceberg--not only in the sense that it's based on a great manufacturing and organizational network that supports production, but also because it represents the heritage of a long history of advances and developments. The iceberg extends unseen through both space and time. So where would survivors turn? A great deal of information will certainly remain in the books gathering dust on the shelves of the now-deserted libraries, bookshops, and homes. The problem with this knowledge, however, is that it isn't presented in a way appropriate for helping a fledgling society--or an individual without specialist training. What do you think you'd understand if you just pulled a medical textbook off the shelf and flipped through the pages of terminology and drug names? University medical textbooks presuppose a huge amount of prior knowledge, and are designed to work alongside teaching and practical demonstrations from established experts. Even if there were doctors among the first generation of survivors, they'd be severely limited in what they could accomplish without test results or the cornucopia of modern drugs they were trained to use--drugs that would be degrading on pharmacy shelves or in defunct hospital storage refrigerators. Much of this academic literature would itself be lost, perhaps to fires ripping unchecked through empty cities. Even worse, much of the wealth of new knowledge generated each year, including that which I and other scientists produce and consume in our own research, is not recorded on any durable medium at all. The cutting edge of human understanding exists primarily as ephemeral bits of data: as specialist journals' academic "papers" stored on website servers. And the books aimed at general readers wouldn't be much more help. Can you imagine a group of survivors who had access to only the selection of books stocked in an average store? How far would a civilization get trying to rebuild itself from the wisdom contained in the pages of self-help guides to succeeding in business management, thinking yourself thin, or reading the body language of the opposite sex? The most absurd nightmare would be a post-apocalyptic society discovering a few yellowed and crumbly books and, thinking them the scientific wisdom of the ancients, trying to apply homeopathy to curb a plague or astrology to forecast harvests. Even the books in the science section would offer little help. The latest pop-sci page-turner may be engagingly written, make clever metaphorical use of everyday observations, and leave the reader with a deeper understanding of some new research, but it probably won't yield much pragmatic knowledge. In short, the vast majority of our collective wisdom would not be accessible--at least in a usable form--to the survivors of a cataclysm. So how best to help the survivors? What key information would a guidebook need to deliver, and how might it be structured? I'm not the first person to wrestle with this question. James Lovelock is a scientist with a formidable track record for striking at the heart of an issue long before his peers. He is most famous for his Gaia hypothesis, which posits that the entire planet--a complex assemblage of rocky crust and oceans and swirling atmosphere, along with the thin smear of life that has established itself across the surface--can be understood as a single entity that acts to damp down instabilities and self-regulate its environment over billions of years. Lovelock is deeply concerned that one element of this system, Homo sapiens , now has the capacity to disrupt these natural checks and balances with devastating effect. Lovelock draws on a biological analogy to explain how we might safeguard our heritage: "Organisms that face desiccation often encapsulate their genes in spores so that the information for their renewal is carried through the drought." The human equivalent envisaged by Lovelock is a book for all seasons, "a primer on science, clearly written and unambiguous in its meaning--a primer for anyone interested in the state of the Earth and how to survive and live well on it." What he proposes is a truly massive undertaking: recording the complete assemblage of human knowledge in a huge textbook--a document that you could, at least in principle, read from cover to cover, and then walk away knowing the essentials of everything that is now known. In fact, the idea of a "total book" has a much longer history. In the past, encyclopedia compilers appreciated far more acutely than we do today the fragility of even great civilizations, and the exquisite value of the scientific knowledge and practical skills held in the minds of the population that evaporate once the society collapses. Denis Diderot explicitly regarded his Encyclopédie , published between 1751 and 1772, as a safe repository of human knowledge, preserving it for posterity in case of a cataclysm that snuffs our civilization as the ancient cultures of the Egyptians, Greeks, and Romans had all been lost, leaving behind only random surviving fragments of their writing. In this way, the encyclopedia becomes a time capsule of accumulated knowledge, all of it arranged logically and cross-referenced, protected against the erosion of time in case of a widespread catastrophe. Since the Enlightenment our understanding of the world has increased exponentially, and the task of compiling a complete compendium of human knowledge would be orders of magnitude harder today. The creation of such a "total book" would represent a modern-era pyramid-building project, consuming the full-time exertion of tens of thousands of people over many years. The purpose of this toil would be to ensure not the safe passage of a pharaoh to eternal bliss in the afterworld, but the immortality of our civilization itself. Such an all-consuming undertaking is not inconceivable if the will is there. My parents' generation worked hard to put the first man on the moon: at its peak the Apollo program employed 400,000 people and consumed 4 percent of the total American federal budget. Indeed, you might think that the perfect compendium of current human knowledge has already been created by the phenomenal combined effort of the committed volunteers behind Wikipedia. Clay Shirky, an expert on the sociology and economics of the Internet, has estimated that Wikipedia currently represents around 100 million man-hours of devoted effort in writing and editing. But even if you could print Wikipedia in its entirety, its hyperlinks replaced by cross-referenced page numbers, you'd still be a far cry from a manual enabling a community to rebuild civilization from scratch. It was never intended for anything like this purpose, and lacks practical details and the organization for guiding progression from rudimentary science and technology to more advanced applications. Moreover, a hard copy would be unfeasibly large--and how could you ensure post-apocalyptic survivors would be able to get hold of a copy? In fact, I believe you can help society recover much better by taking a slightly more elegant approach. The solution can be found in a remark made by physicist Richard Feynman. In hypothesizing about the potential destruction of all scientific knowledge and what might be done about it, he allowed himself a single statement, to be transmitted securely to whichever intelligent creatures emerged after the cataclysm: What sentence holds the most information in the fewest words? "I believe," said Feynman, "it is the atomic hypothesis . . . that all things are made of atoms--little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. " The more you consider the implications and testable hypotheses emerging from this simple statement, the more it unfurls to release further revelations about the nature of the world. The attraction of particles explains the surface tension of water, and the mutual repulsion of atoms in close proximity explains why I don't fall straight through the café chair I'm sitting on. The diversity of atoms, and the compounds produced by their combinations, is the key principle of chemistry. This single, carefully crafted sentence encapsulates a huge density of information, which unravels and expands as you investigate it. But what if your word count wasn't quite so restricted? If allowed the luxury of being more expansive while retaining the guiding principle of providing key, condensed knowledge to accelerate rediscovery, rather than attempting to write a complete encyclopedia of modern understanding, is it feasible to write a single volume that would constitute a survivor's quick-start guide to rebooting technological society? I think that Feynman's single sentence can be improved upon in a fundamentally important way. Possessing pure knowledge alone with no means to exploit it is impotent. To help a fledgling society pull itself up by its own bootstraps, you've also got to suggest how to utilize that knowledge, to show its practical applications. For the survivors of a recent apocalypse, the immediate practical applications are essential. Understanding the basic theory of metallurgy is one thing, but using the principles to scavenge and reprocess metals from the dead cities, for instance, is another. The exploitation of knowledge and scientific principles is the essence of technology, and as we'll see in this book, the practices of scientific research and technological development are inextricably intertwined. Inspired by Feynman, I'd argue that the best way to help survivors of the Fall is not to create a comprehensive record of all knowledge, but to provide a guide to the basics, adapted to their likely circumstances, as well as a blueprint of the techniques necessary to rediscover crucial understanding for themselves--the powerful knowledge-generation machinery that is the scientific method. The key to preserving civilization is to provide a condensed seed that will readily unpack to yield the entire expansive tree of knowledge, rather than attempting to document the colossal tree itself. Which fragments, to paraphrase T. S. Eliot, are best shored against our ruins? The value of such a book is potentially enormous. What might have happened in our own history if the classical civilizations had left condensed seeds of their accumulated knowledge? One of the major catalysts for the Renaissance in the fifteenth and sixteenth centuries was the trickle of ancient learning back into Western Europe. Much of this knowledge, lost with the fall of the Roman Empire, was preserved and propagated by Arab scholars carefully translating and copying texts; other manuscripts were rediscovered by European scholars. But what if these treatises on philosophy, geometry, and practical mechanisms had been preserved in a distributed network of time capsules? And similarly, with the right book available, could a post-apocalyptic Dark Ages be averted?* ACCELERATED DEVELOPMENT During a reboot, there's no reason to retrace the original route to scientific and technological sophistication. Our path through history has been long and tortuous, stumbling in a largely haphazard manner, chasing red herrings and overlooking crucial developments for long periods. But with 20/20 hindsight, knowing what we know now, could we give directions straight to crucial advances, taking shortcuts like an experienced navigator? How might we chart an optimal route through the vastly interlinked network of scientific principles and enabling technologies to accelerate progress as much as possible? Key breakthroughs in our history are often serendipitous--they were stumbled upon by chance. Alexander Fleming's discovery of the antibiotic properties of Penicillium mold in 1928 was a chance occurrence. And indeed, the observation that first hinted at the deep coupling between electricity and magnetism--the twitching of compass needles left next to a wire carrying current--was fortuitous, as was the discovery of X-rays. Many of these key discoveries could just as easily have happened earlier, some of them substantially so. Once new natural phenomena have been discovered, progress is driven by systematic and methodical investigation to understand their workings and quantify their effects, but the initial uncovering can be targeted with a few choice hints to the recovering civilization on where to look and which investigations to prioritize. Likewise, many inventions seem obvious in retrospect, but sometimes the time of emergence of a key advance or invention doesn't appear to have followed any particular scientific discovery or enabling technology. For the prospects of a rebooting civilization, these cases are encouraging because they mean the quick-start guide need only briefly describe a few central design features for the survivors to figure out exactly how to re-create some key technologies. The wheelbarrow, for instance, could have occurred centuries before it actually did--if only someone had thought of it. This may seem like a trivial example, combining the operating principles of the wheel and the lever, but it represents an enormous labor saver, and it didn't appear in Europe until millennia after the wheel (the first depiction of a wheelbarrow appears in an English manuscript written about 1250 AD). Other innovations have such wide-ranging effects, aiding a great diversity of other developments, that you would want to beeline directly toward them to support many other elements of the post-apocalyptic recovery. The movable-type printing press is one such gateway technology that accelerated development and had incomparable social ramifications in our history. With a little guidance, mass-produced books could reappear early in the rebuilding of a new civilization, as we'll see later. And when developing new technologies, some steps in the progression could be skipped altogether. The quick-start guide could aid a recovering society by showing how to leapfrog straight over intermediate stages from our history to more advanced, yet still achievable, systems. There are a number of encouraging cases of this kind of technological leapfrogging in the developing nations in Africa and Asia today. For example, many remote communities unconnected to power grids are receiving solar-power infrastructure, hopping over centuries of the Western progression dependent on fossil fuels. Villagers living in mud huts in many rural parts of Africa are leapfrogging straight to mobile phone communications, bypassing intermediate technologies such as semaphore towers, telegraphs, or land-line telephones. But perhaps the most impressive feat of leapfrogging in history was achieved by Japan in the nineteenth century. During the Tokugawa shogunate, Japan isolated itself for two centuries from the rest of the world, forbidding its citizens to leave or foreigners to enter, and permitting only minimal trade with a select few nations. Contact was reestablished in the most persuasive manner in 1853 when the US Navy arrived in the Bay of Edo (Tokyo) with powerfully weaponized steam-powered warships, far superior to anything possessed by the technologically stagnant Japanese civilization. The shock of realization of this technological disparity triggered the Meiji Restoration. Japan's previously isolated, technologically backward feudal society was transformed by a series of political, economic, and legal reforms, and foreign experts in science, engineering, and education instructed the nation how to build telegraph and railroad networks, textile mills and factories. Japan industrialized in a matter of decades, and by the time of the Second World War was able to take on the might of the US Navy that had forced this process in the first place. Could a preserved cache of appropriate knowledge allow a post-apocalyptic society to similarly achieve a rapid developmental trajectory? Unfortunately, there are limits to how far ahead you can push a civilization by skipping intermediate stages. Even if the post-apocalyptic scientists fully understand the basis underlying an application and have produced a design that would work in principle, it may still be impossible to build a working prototype. I call this the Da Vinci effect. The great Renaissance inventor generated endless designs for mechanisms and contraptions, such as his fantastic flying machines, but few of them were ever realized. The problem was largely that Da Vinci was too far ahead of his time. Correct scientific understanding and ingenious designs aren't sufficient: you also need a matching level of sophistication in construction materials with the necessary properties and available power sources. So the trick for a quick-start guide must be to provide appropriate technology for the post-apocalyptic world, in the same way that aid agencies today supply suitable intermediate technologies to communities in the developing world. These are solutions that offer a significant improvement on the status quo--an advance from the existing, rudimentary technology--but which are still able to be repaired and maintained by local workmen with the practical skills, tools, and materials available. Thus the aim for an accelerated reboot of civilization is to jump directly to a level that saves centuries of incremental development, but that can still be achieved with rudimentary materials and techniques--the sweet-spot intermediate technology. It is these features of our own history--serendipitous discoveries, inventions that were not waiting for any prerequisite knowledge, gateway technologies that stimulated progress in many areas, and opportunities to leapfrog over intermediate stages--that give us optimism that a well-designed quick-start manual for civilization could give directions toward the most fertile investigations and the crucial principles behind key technologies, guiding an optimal route through the web of science and technology, and so greatly accelerate rebuilding. Imagine science when you're not fumbling around in the dark, but your ancestors have equipped you with a flashlight and a rough map of the landscape. If a rebooting civilization is not required to follow our own idiosyncratic path of progress, it will experience a completely different sequence of advances. Indeed, rebooting along the same trajectory that our current civilization followed may now be very difficult. The Industrial Revolution was powered largely by fossil energy. Most of these easily accessible fossil energy sources--deposits of coal, oil, and natural gas--have now been mined toward depletion. Without access to such readily available energy, how could a civilization following ours haul itself through a second industrial revolution? The solution, as we'll see, will lie in an early adoption of renewable energy sources and careful recycling of assets--sustainable development will likely be forced on the next civilization out of sheer necessity: a green reboot. In the process, unfamiliar combinations of technologies will emerge over time. We will take a look at examples of where a recovering society is likely to take a different trajectory in its development--the path not traveled--as well as utilizing technological solutions that for us have fallen by the wayside. To us, Civilization 2.0 might look like a mishmash of technologies from different eras, not unlike the genre of fiction known as steampunk. Steampunk narratives are set in an alternative history that has followed a different pattern of development and is often characterized by a fusion of Victorian technology with other applications. A post-apocalyptic reboot with very different rates of progress in separate fields of science and technology is likely to lead to such an anachronistic patchwork. A reboot manual would work best on two levels. First, you need a certain amount of practical knowledge handed to you on a plate, so as to recover a base level of capability and a comfortable lifestyle as quickly as possible, and to halt further degeneration. But you also need to nurture the recovery of scientific investigation and provide the most worthwhile kernels of knowledge to begin exploring.* We'll start with the basics and see how you can provide the fundamental elements of a comfortable life for yourself after the Fall: sufficient food and clean water, clothes and building materials, energy and essential medicines. There will be a number of immediate concerns for the survivors: cultivable crops must be gathered from farmland and seed caches before they die and are lost; diesel can be rendered from biofuel crops to keep engines running until the machinery fails, and parts can be scavenged to reestablish a local power grid. We'll look at how best to cannibalize components and scavenge materials from the detritus of the dead civilization: the post-apocalyptic world will demand ingenuity in repurposing, tinkering, and jury-rigging. Once the essentials are in place, I'll explain how to reinstate agriculture and safely preserve a stockpile of food, and how plant and animal fibers can be turned into clothes. Materials such as paper, ceramic pottery, brick, glass, and wrought iron are today so commonplace that they are considered prosaic and boring--but how could you actually make them if you needed to? Trees yield an enormous amount of remarkably useful stuff: from timber material for construction to charcoal for purifying drinking water, as well as providing a fiercely burning solid fuel. A whole range of crucial compounds can be baked out of wood, and even ashes contain a substance (called potash) needed for making essential items such as soap and glass, as well as producing one of the ingredients of gunpowder. With basic know-how you can extract a great deal of other critically useful substances from your natural surroundings--soda, lime, ammonia, acids, and alcohol--and start a post-apocalyptic chemical industry. And as your capabilities recover, the quick-start guide will help the development of explosives suitable for mining and for demolishing the carcasses of ancient buildings, as well as the production of artificial fertilizer, and of the light-sensitive silver compounds used in photography. In later chapters we'll see how to relearn medicine, harness mechanical power, master the generation and storage of electricity, and assemble a simple radio set. And since The Knowledge contains information on how to make paper, ink, and a printing press, the book itself contains the genetic instructions for its own reproduction. How much can one book invigorate our understanding of the world? I obviously can't begin to pretend this single volume represents a complete documentation of the sum total of human knowledge of science and technology. But I think it provides enough of a grounding in the fundamentals to help survivors in the early years after a Fall, and broad directions for tracing an optimal route through the web of science and technology for a greatly accelerated recovery. And, following the principle of providing condensed kernels of knowledge that unravel under investigation, a single volume can encapsulate a vast treasure trove of information. By the time you put down this manual, you'll understand how to rebuild the infrastructure for a civilized lifestyle. You'll also, I hope, have a firmer grip on some of the beautiful fundamentals of science itself. Science is not a collection of facts and figures: it is the method you need to apply to confidently work out how the world works. The purpose of a quick-start guide is to ensure that the fire of curiosity, of inquiry and exploration, continues to burn fiercely. The hope is that even in the maw of a cataclysmic shock the thread of civilization is not broken and the surviving community does not regress too far or stagnate; that the core of our society can be preserved; and that these crucial kernels of knowledge, nurtured in the post-apocalyptic world, will flourish once again. This is the blueprint for a rebooting civilization--but also a primer on the fundamentals of our own. CHAPTER 1 THE END OF THE WORLD AS WE KNOW IT The most glorious moment for a work of this sort would be that which might come immediately in the wake of some catastrophe so great as to suspend the progress of science, interrupt the labors of craftsmen, and plunge a portion of our hemisphere into darkness once again. DENIS DIDEROT, Encyclopédie (1751-1772) THE SEEMINGLY OBLIGATORY SCENE in any disaster movie is a panning shot across a broad highway gridlocked with tightly packed vehicles attempting to flee the city. Instances of extreme road rage flare as drivers grow increasingly desperate, before abandoning their cars among the others already littering the shoulders and lanes and joining the droves of people pushing onward on foot. Even without an immediate hazard, any event that disrupts distribution networks or the electrical grid will starve the cities' voracious appetite for a constant influx of resources and force their inhabitants out in a hungry exodus: mass migrations of urbanite refugees swarming into the surrounding countryside to scavenge for food. TEARING UP THE SOCIAL CONTRACT I don't want to get stuck in the philosophical quagmire of debating whether mankind is intrinsically evil or not, and whether a controlling authority is a necessary construct to impose a set of laws and maintain order through the threat of punishment. But it is clear that with the evaporation of centralized governance and a civil police force, those with ill intentions will seize the opportunity to subjugate or exploit those more peaceful or vulnerable. And once the situation seems sufficiently dire, even previously law-abiding citizens will resort to whatever action is necessary to provide for and protect their own families. To ensure your own survival you may have to forage and scavenge for what you need: a polite euphemism for looting. Part of the glue that binds societies together is the expectation that the pursuit of short-term gains through deception or violence is far outweighed by the long-term consequences. You'll be caught and socially stigmatized as an untrustworthy partner or punished by the state: cheats don't prosper. This tacit agreement between the individuals in a society to cooperate and behave for the collective good, sacrificing a certain amount of their own personal freedom in exchange for benefits such as the mutual protection offered by the state, is known as the social contract. It is the very foundation of all collective endeavor, production, and economic activity of a civilization, but the structure begins to strain and social cohesion loosens once individuals perceive greater personal gains in cheating, or suspect that others will cheat them. During a severe crisis the social contract can snap altogether, precipitating a complete disintegration of law and order. We need look no further than the most technologically advanced nation on the planet to see the effects of a localized fracture in the social contract. New Orleans was physically devastated by the rampage of Hurricane Katrina, but it was the desperate realization by the city's inhabitants that local governance had evaporated and no help would be arriving anytime soon that precipitated the rapid degeneration of normal social order and the outbreak of anarchy. So after a cataclysmic event, we might expect organized gangs to emerge to fill the power vacuum left behind after the evaporation of governance and law enforcement, laying claim to their own personal fiefdoms. Those who seize control of the remaining resources (food, fuel, and so on) will administer the only items that have any inherent value in the new world order. Cash and credit cards will be meaningless. Those appropriating the caches of preserved food as their own "property" will become very wealthy and powerful--the new kings--controlling the allocation of food to buy loyalty and services in the same way that ancient Mesopotamian emperors did. In this environment, people with special skills, such as doctors and nurses, might do well to keep this to themselves, as they may be forced to serve the gangs as highly specialized slaves. Lethal force may be applied swiftly to deter looters and raids from rival gangs, and as resources become depleted the competition will get only fiercer. A common mantra of people who actively prepare for the apocalypse (called Preppers) is: "It is better to have a gun and not need it than to need a gun and not have it." One pattern likely to recur over the weeks and months after the Fall is that small communities of people will gather together in a defensible location for mutual support and protection of their own stash of consumables, looking for safety in numbers. These small dominions will need to patrol and protect their own borders in the way that whole nations do today. Ironically, the safest place for a group to barricade themselves in and hunker down during the turbulence would be one of the fortresses dotted across the country, but now turned inside out in its purpose. Prisons are largely self-contained compounds with high walls, sturdy gates, barbed wire, and watchtowers, originally intended to prevent the inhabitants from escaping, but equally effective as a defensive refuge for keeping others out. The outbreak of widespread crime and violence is probably an inevitable effect of any catastrophic event. However, this hellish descent into a Lord of the Flies world is not something I will discuss any further here. This book is about how to fast-track the recovery of technological civilization once people are able to settle down again. THE BEST WAY FOR THE WORLD TO END Before we get to the "best" let's start with the worst. From the point of view of rebuilding civilization, the worst kind of doomsday event would be all-out nuclear war. Even if you escape vaporization in the targeted cities, much of the material of the modern world will have been obliterated, and the dust-darkened skies and ground poisoned by fallout would hamper the recovery of agriculture. Just as bad, even though it is not directly lethal, would be an enormous coronal mass ejection from the Sun. A particularly violent solar burp would slam into the magnetic field around our planet, set it ringing like a bell, and induce enormous currents in the electricity distribution wires, destroying transformers and knocking out electrical grids across the planet. The global power blackout would disrupt the pumping of water and gas supplies and the refining of fuel, as well as the production of replacement transformers. With such devastation of the core infrastructure of modern civilization without any immediate loss of life, the collapse of social order would soon follow, and the roving crowds would rapidly consume the remnant supplies and so precipitate a subsequent mass depopulation. At the end, survivors would still encounter a world without people, but one that has now also been stripped bare of any resources that would have offered them a grace period for recovery. While the dramatic scenario favored by many post-apocalyptic movies and novels may be the collapse of industrial civilization and social order, forcing survivors to engage in an increasingly frantic struggle for dwindling resources, the scenario that I want to focus on is the inverse: a sudden and extreme depopulation that leaves the material infrastructure of our technological civilization untouched. The majority of humanity has been erased, but all of the stuff is still around. This scenario presents the most interesting starting point for the thought experiment on how to accelerate the rebuilding of civilization from scratch. It grants the survivors a grace period to find their feet, preventing a degenerative slide too far, before they need to relearn all the essential functions of a self-supporting society. In this sense, the "best" way for the world to end would be at the hands of a fast-spreading pandemic. The perfect viral storm is a contagion that combines aggressive virulence, a long incubation period, and near 100 percent mortality. This way, the agent of the apocalypse is extremely infectious between individuals, takes a little while for its sickness to kick in (so that it maximizes the pool of subsequent hosts that are infected), but results in certain death in the end. We have become a truly urban species--since 2008 more than half of the global population lives in cities rather than rural areas--and this crammed density of people, along with fervent intercontinental travel, provides the perfect conditions for the rapid transmission of contagions. If a plague like the Black Death, which wiped out a third of the European population (and probably a similar proportion across Asia) from 1347 to 1351, were to strike today, our technological civilization would be much less resilient.* -- WHAT, THEN, is the minimum number of survivors of a global catastrophe that is sufficient for humanity to have a feasible chance of not just repopulating the world but being able to accelerate the rebuilding of civilization? To put it another way: What is the critical mass to enable a rapid reboot? There are two extremes on the spectrum of surviving populations, which I will call the "Mad Max" and "I Am Legend" scenarios. If there is an implosion of the technological life support system of modern society but no immediate depopulation (such as would be triggered by a coronal mass ejection), most of the population survives to rapidly consume any remaining resources in fierce competition. This wastes the grace period, and society promptly descends into Mad Max -style barbarism and a subsequent mass depopulation, with little hope of rapidly bouncing back. If, on the other hand, you are the sole survivor in the world, or at least one of a small number of survivors so dispersed that they are unlikely to stumble across one another during their lives, then the notion of rebuilding civilization, or even recovering the human population, is nil. Humanity hangs on by a single thread and is inevitably doomed when this Omega man or woman dies--the situation in Richard Matheson's novel I Am Legend . Two survivors--a male and a female--is the mathematical minimum for continuation of the species, but the genetic diversity and long-term viability of a population growing from just two individuals would be seriously compromised. So what is the theoretical minimum needed for repopulation? Analysis of the mitochondrial DNA sequences in the Maori people living in New Zealand today has been used to estimate the number of founding pioneers who first arrived on rafts from Eastern Polynesia. The genetic diversity revealed that the effective size of this ancestral population was no more than about seventy breeding females, and so a total population a little over twice that. A similar genetic analysis deduced a comparable founding population of the great majority of Native Americans, who are descended from ancestors who crossed the Bering land bridge from Eastern Asia 15,000 years ago when sea levels were lower. Thus a post-apocalyptic group of a few hundred men and women, all in the same place, ought to encapsulate sufficient genetic variability to repopulate the world. The problem is that even with a growth rate of 2 percent per annum, the fastest the world's population has ever grown when sustained by industrialized agriculture and modern medicine, it would still take eight centuries for this ancestral group to recover to the population of the time of the Industrial Revolution. (We'll explore in later chapters the reasons why advanced scientific and technological developments probably require a certain population size and socioeconomic structure.) And such a diminished initial population would probably be far too small to be able to actually maintain reliable cultivation, let alone more advanced production methods, and so would regress all the way back to a hunter-gatherer lifestyle, preoccupied with the struggle for subsistence. Ninety-nine percent of human existence has been spent in this lifestyle, which cannot support dense populations and represents a trap that is very hard to progress out of again. How do you avoid regressing that far? The surviving population would need plenty of hands to work the fields to ensure agricultural productivity, yet leave enough individuals available to work on developing other crafts and recovering technologies. For the best possible restart, you'd also want the survivors to number enough that a broad swath of skill sets is represented and sufficient collective knowledge is retained to prevent sliding backward too far. Thus an initial surviving population of around 10,000 in any one area (which for a large state such as Texas represents a survival fraction of only 0.04 percent), who are able to gather into a new community and work peacefully together, represents the ideal starting point for this thought experiment. So let's turn our attention to the sort of world that the survivors will find themselves in, and how it will change around them as they rebuild. RECOLONIZATION BY NATURE Immediately after the termination of routine maintenance, nature will seize its opportunity to reclaim our urban spaces. Trash and detritus will collect on the streets and pavements, blocking drains and causing the pooling of water and accumulation of debris rotting into mulch. Pioneering weeds will first begin proliferating in pockets like this. Even in the complete absence of pounding car tires, cracks in the asphalt will steadily expand into crevices. With every frost, water pooled in these depressions will freeze and expand, crumbling the hard artificial ground from within with the same punishing freeze-thaw cycle that steadily wears down entire mountain ranges. This weathering creates more and more niches for small opportunistic weeds, and then shrubs, to become established and further break up the surface. Other plants are more aggressive, their penetrating roots pushing right through the bricks and mortar to find purchase and tap into sources of moisture. Vines will snake their way up traffic lights and street signs, treating them like metallic tree trunks, and lush coatings of creepers will grow up the cliff-like faces of buildings and spread down from the rooftops. Over a number of years, accumulating leaf litter and other vegetative matter from this pioneering burst of growth will decay to an organic humus and will mix with the windblown dust and grit of deteriorating concrete and bricks to create a genuine urban soil. Papers and other detritus billowing out of broken office windows will collect in the streets below and add to this composting layer. A thickening carpet of dirt will smother the roads, sidewalks, parking lots, and open plazas of towns and cities, allowing a succession of larger trees to take root. Away from the asphalt streets and paved squares, the cities' grassy parks and the surrounding countryside will rapidly return to woodland. Within just a decade or two, elder thickets and birch trees will have become firmly established, maturing to dense woods of spruce, larch, and beech trees by the end of the first century after the apocalypse. BUILDINGS CRUMBLE AND NATURE RECLAIMS OUR URBAN SPACES, INCLUDING OUR STORES OF KNOWLEDGE LIKE THIS NEW JERSEY LIBRARY. And while nature is busy reclaiming the environment, our buildings will crumble and decay among the growing forests. As vegetation returns and fills the streets with wood and drifts of windblown leaves, mingling with the trash strewn out of broken windows, piles of perfect kindling will collect in the streets, and the chances of raging urban forest fires increase. Tinder accumulated against the side of a building and ignited by a summer lightning storm, or perhaps by sunlight focused through broken glass, is all that's needed to unleash devastating wildfires that would spread along the streets and burn up the insides of high-rises. A modern city wouldn't be razed to the ground like London in 1666 or Chicago in 1871, the fire ripping rapidly from one wooden building to the next and leaping across the narrow streets; but blazes spreading unopposed by firefighters would still be devastating. Gas lingering in underground pipes and throughout buildings would explode, any fuel left in the tanks of vehicles abandoned in the streets only adding to the intensity of the inferno. Dotted throughout populated areas are bombs waiting to go off when a blaze sweeps through: gas stations, chemical depots, and the vats of highly volatile and flammable solvents in dry-cleaning stores. Perhaps one of the most poignant sights for post-apocalyptic survivors would be watching the burning of the old cities, sprouting thick columns of choking black smoke towering above the landscape and flushing the sky bloodred at night. After a passing blaze, the brick, concrete, and steel matrix of contemporary buildings would be all that is left behind--charred skeletons after their combustible internal viscera have been gutted. Fire will wreak devastation across great areas of the deserted cities, but it is water that will eventually bring certain destruction for all our carefully constructed buildings. The first winter after the Fall will see a spate of burst frozen water pipes, which will disgorge inside buildings during the following thaw. Rain will blow in through missing or broken windows, trickle down among dislodged roofing tiles, and overflow from blocked gutters and drains. Peeled paint from window and door frames will allow moisture to soak in, rotting wood and corroding metal until the whole insert falls out of the wall. The wooden structures--floorboards, joists, and roof supports--will also soak up moisture and rot, while the bolts, screws, and nails holding the components together rust. Concrete, bricks, and the mortar smeared between them are subject to temperature swings, soaked with water trickling down from blocked gutters, and pulverized by the relentless pulsing of freeze-thaw at high latitudes. In warmer climates, insects such as termites and woodworms will join forces with fungi to eat away at the wooden components of buildings. Before too long, wooden beams will decay and yield, causing floors to fall through and roofs to collapse, and eventually the walls themselves will bow outward, then topple. The majority of our houses or apartment blocks will last, at most, a hundred years. Our metal bridges will corrode and weaken as the paint peels off, allowing water to seep in. The death knell for many bridges, though, is likely to be windblown detritus collecting in the expansion gaps, breathing spaces designed to allow the materials to swell in the summer heat. Once clogged, the bridge will strain against itself, shearing off corroding bolts until the whole structure gives way. Within a century or two, many bridges will have collapsed into the water below, the lines of rubble and debris at the feet of the still-standing pillars forming a series of weirs in the river. The steel-reinforced concrete of many modern buildings is a marvelous building material, but although more resistant than wood, it is by no means impervious to decay. The ultimate cause of its deterioration is ironically the source of its great mechanical strength. The steel rebars are cocooned from the elements by the concrete surrounding them, but as mildly acidic rainwater soaks through, and humic acids released by rotting vegetation seep into the concrete foundations, the embedded steel begins to rust inside the structures. The final blow for this modern construction technique is the fact that steel expands as it rusts, rupturing the concrete from the inside, leaving even more surface exposed to moisture and so accelerating the endgame. These rebars are the weak point of modern construction--and unreinforced concrete will prove more durable in the long run: the dome of the Pantheon in Rome is still going strong after two thousand years. The greatest threat to high-rises, though, is waterlogged foundations from unmaintained drainage, blocked sewers, or recurring floods, particularly among cities built along the banks of a river. The supports will corrode and degrade, or subside into the ground to create listing skyscrapers far more ominous than the leaning tower of Pisa, before inevitably collapsing. The raining debris will further damage surrounding edifices, or the buildings will perhaps even topple over into neighboring monoliths like giant dominoes, until only a few remain spiking above a skyline of trees. Few of our great high-rise buildings would be expected to still be standing after a few centuries. So within just a generation or two after the Fall, the urban geography will have become unrecognizable. Opportunistic seedlings have become saplings have become full-blown trees. City streets and boulevards have been replaced by dense corridors of forest crammed into the man-made canyons between high-rise buildings, themselves now grossly dilapidated and trailing vegetation from gaping windows like vertical ecosystems. Nature has utterly reclaimed the urban jungle. Over time, the jagged piles of rubble from collapsed buildings will themselves become softened by the accumulation of decomposing plant matter forming soil--hillocks of dirt sprouting trees, until even the tumbled remains of once-soaring skyscrapers are buried and hidden by verdant growth. Away from the cities, fleets of ghost ships will be adrift across the oceans, occasionally carried by the vagaries of wind and currents to ground themselves on a coastline, slicing open their bellies to bleed noxious slicks of fuel oil or releasing their load of containers onto the ocean currents like dandelion seeds in the wind. But perhaps the most spectacular shipwreck, if anyone happens to be in the right place at the right time to watch it, will be the return of one of humanity's most ambitious constructions. The International Space Station is a giant 100-meter-wide edifice built over fourteen years in low Earth orbit: an impressive assemblage of pressurized modules, spindly struts, and dragonfly wings of solar panels. Although it soars 400 kilometers over our heads, the space station is not quite beyond the wispy upper reaches of the atmosphere, which exert an imperceptibly slight but unrelenting drag on the sprawling structure. This saps the space station's orbital energy so that it spirals steadily toward the ground, and it needs to be repeatedly boosted back up with rocket thrusters. With the demise of the astronauts, or lack of fuel, the space station will relentlessly drop about 2 kilometers every month. Before too long, it would be hauled down into a fiery plunge through the air, ending in a streak of light and fireball like an artificial shooting star. THE POST-APOCALYPTIC CLIMATE The gradual decay of our cities and towns is not the only transforming process that the survivors of the apocalypse will witness. Since the Industrial Revolution and exploitation of first coal and then natural gas and oil, humanity has been fervently burrowing underground to dig up the buried chemical energy accumulated from times past. These fossil fuels, readily combustible dollops of carbon, are the decayed remains of ancient forests and marine organisms: chemical energy derived from the trapping of sunlight that shone on the Earth eons ago. This carbon originally came from the atmosphere, but the problem is that we are burning these stores so quickly that a few hundred million years' worth of fixed carbon have been released back into the atmosphere in just over a hundred years, pumped out of our smokestacks and car exhaust pipes. This is far, far faster than the planetary system can reabsorb the liberated carbon dioxide, and there is about 40 percent more of the gas in the air today than at the beginning of the eighteenth century. One effect of this elevated carbon dioxide level is that more of the Sun's warmth is trapped by the Earth's atmosphere through the greenhouse effect, leading to global warming. This in turn will lead to a rise in sea levels and the disruption of weather patterns worldwide, creating more frequent, heavier monsoon floods in some areas and droughts in others, with severe repercussions for agriculture. With the collapse of technological civilization, emissions from industry, intensive agriculture, and transport would cease overnight, and pollution from the small surviving population would drop to practically zero in the immediate aftermath. But even if emissions were to completely stop tomorrow, the world will continue to respond for the next few centuries to the vast amount of carbon dioxide our civilization has already belched out. We are currently in a lag phase, as the planet reacts to the sudden hard shove we have given to its equilibrium. The post-apocalyptic world is therefore likely to experience a rise in sea level of several meters over the following centuries from momentum already built up in the system. The effects could be much worse if the warming triggers other secondary effects, such as the thawing of methane-laden permafrost or widespread melting of glaciers. While carbon dioxide levels will decline after the apocalypse, they will plateau at a substantially elevated value and not return to their preindustrial state for many tens of thousands of years. So over the timescale of our, or any following, civilization, this forced cranking-up of the planet's thermostat is essentially permanent, and our current carefree lifestyle will leave a long, dark legacy for those inhabiting the world we leave behind. The consequences for survivors already struggling to support themselves is that as climate and weather patterns continue to change over the generations, once-fertile cropland may be ruined by drought, low-lying regions become flooded, and tropical diseases become more prevalent. Shifts in local climate have caused abrupt collapses of civilizations in human history, and the ongoing global changes may well frustrate the recovery of a fragile post-apocalyptic society. CHAPTER 2 THE GRACE PERIOD Thus we never see the true state of our condition till it is illustrated to us by its contraries, nor know how to value what we enjoy, but by the want of it. DANIEL DEFOE, Robinson Crusoe (1719) AFTER A PLANE CRASH IN A REMOTE AREA, your main priorities for survival would be shelter, water, and food. The same requirements are paramount after the crash of civilization. While it's possible to survive several weeks without food, and a few days without drinking water, if you're caught outside in an inclement climate, you can die of exposure within a matter of hours. As the British Special Air Service (SAS) survival expert John "Lofty" Wiseman told me, "If you're still on your feet after the big bang, you are a survivor. But how long you continue to survive is down to your knowledge and what you do." For our purposes we'll assume that, like more than 99 percent of people, including myself, you're not a Prepper and have not stockpiled food and water, fortified your home, or made any other prior arrangements for the end of the world. So during the crucial buffer period before you're forced to start producing things anew, what remnants could you scavenge to ensure your survival in the post-apocalyptic world? What would you want to look out for when beachcombing the detritus left behind by the receding technological tide? SHELTER Excerpted from The Knowledge: What Survivors of an Apocalypse Need to Rebuild Civilization by Lewis Dartnell All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
