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Peter HeckA well-written and thought-provoking book from Benford; it would be a pleasure to see more non-fiction for a general audience from his hand.
— Asimov's Science Fiction
Human civilization has evolved to the point at which we have begun consciously sending messages into the far future. How should we communicate who we are, what we know, to asyet-unmet intelligent beings elsewhere in both time and space? Will they be able to decipher what we say? And what information will we leave to Earth's occupants a million years hence? How can we address an unknown destiny in which human culture itself may no longer exist?
Combining the logical rigor of a ...
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Human civilization has evolved to the point at which we have begun consciously sending messages into the far future. How should we communicate who we are, what we know, to asyet-unmet intelligent beings elsewhere in both time and space? Will they be able to decipher what we say? And what information will we leave to Earth's occupants a million years hence? How can we address an unknown destiny in which human culture itself may no longer exist?
Combining the logical rigor of a scientist with the lyrical beauty of a novelist, Gregory Benford explores these and other fascinating questions in a provocative analysis of humanity's attempts to make its culture immortal, to cross the immense gulf that such deep-time messages must span in order to be understood. In clear, crisp language, he confronts our growing influence on events hundreds of thousands of years into the future, and explores the possible "messages" we may transmit to our distant descendants in the language of the planet itself -- from nuclear waste to global warming to the extinction of species.
We are already sending messages into nearby space; in the coming ages we will be able to launch probes accurately to other stars. Our indelible legacy to future generations, or to the next occupants of this planet, is already being constructed. As we begin our incredible journey down the path of eternity, Gregory Benford masterfully calls forth some of the intriguing, astounding, undreamed -- of futures which may await us in deep time.
Human civilization has evolved to the point at which we have begun consciously sending messages into the far future. How should we communicate who we are, what we know, to as-yet-unmet intelligent beings elsewhere in both time and space? Will they be able to decipher what we say? And what information will we leave to Earth's occupants a million years hence? How can we address an unknown destiny in which human culture itself may no longer exist?Combining the logical rigor of a scientist with the lyrical beauty of a novelist, Gregory Benford explores these and other fascinating questions in a provocative analysis of humanity's attempts t make its culture immortal, to cross the immense gulf that such deep-time messages must span in order to be understood. In clear, crisp language, he confronts our growing influence on events hundreds of thousands of years into the future, and explores the possible "messages' we may transmit to our distant descendants in the language of the planet itself-from nuclear waste to global warming to the extinction of species.
He would lift up man's heart for his own benefit because in that way he can say No to death.
One of the chores of physics professors everywhere lies in fielding telephone calls that come into one's department. Sometimes they are from obvious cranks, the sort who earnestly implore you to look over their new theory of the cosmos or their device for harnessing the Earth's magnetism as a cure to the world's energy needs. These one must accord a firm diplomacy. Any polite pivot that gets one off the line is quite all right. One of the few governing rules is that one may not deflect the call to another professor.
In 1989, I got a call that at first seemed normal, from a fellow who said he was from Sandia Laboratories in Albuquerque, New Mexico. Then I sniffed a definite, classic odor of ripe crank.
"Did I hear correctly?" I asked. "The House of Representatives has handed down a requirement on the Department of Energy. They want a panel of experts to consider a nuclear waste repository, and then numerically assess, with probabilities, the risks that somebody might accidentally intrude on it for ... "
"That's right, for ten thousand years."
I paused. He sounded solid, without the edgy fervor of the garden variety crank. Still ...
"That's impossible, of course."
"Sure," he said. "I know that. But this is Congress."
We both laughed and I knew he was okay.
So it came to be that a few months later I descended in a wire-cage elevator, clad in hard hat with head lamp, goggles, and carrying on my belt an emergency oxygen pack. I had a numbered brass tag on my wrist, too—"For identification," the safety officer had said.
"Why?" I asked.
She looked uncomfortable. "Uh, in case you, uh ..."
"In case my body can't be identified?"
"Well, we don't expect anything, of course, but—" She blinked rapidly. "—you know, rules."
We rattled downward for long minutes as I pondered the highest risk here: a flash fire that would overwhelm the air conduits, smothering everyone working in the kilometer-long arms of the Waste Isolation Pilot Plant (WIPP), buried deep within the salt flat outside Carlsbad, New Mexico.
We clattered to a stop 2,150 feet down in the salt flat. The door slid aside and our party of congressionally authorized experts on the next ten thousand years filed out into a bright, broad corridor a full thirty-three feet wide and thirteen feet high. It stretched on like a dirty gray demonstration of the laws of perspective, with smaller hallways branching off at regular intervals.
Huge-bladed machines had carved these rectangular certainties, leaving dirty gray walls that felt cool and hard (and tasted salty; I couldn't resist). Floodlights brought everything into sharp detail, like a 1950s science fiction movie—engineers in blue jumpsuits whining past in golf carts, helmeted workers with forklifts and clipboards, a neat, professional air.
We climbed into golf carts with WIPP DOE stenciled on them, for Waste Isolation Pilot Project, Department of Energy. We sped among the long corridors and roomy alcoves. Someone had quietly inquired into possible claustrophobic tendencies among our party, but there seemed little risk. The place resembles a sort of subterranean, Borgesian, infinite parking garage. It had taken fifteen years to plan and dig, at the mere cost of $1.8 billion. Only the government, I mused idly, could afford such parking fees.
A HERITAGE OF WASTE
Ever since 1945, radioactive refuse has been an ever-growing problem. It comes in several kinds—highly radioactive fuel rods from reactors, shavings from nuclear warhead manufacture, and a vast mass of lesser, lightly radioactive debris such as contaminated clothes, plastic liners, pyrex tubes, rags, beakers, drills, pipes, boxes, and casings. Much of this is sitting in steel drums, many already leaking into the ground. We have run out of time.
Fifty years into the Nuclear Age, no country has actually begun disposing of its waste in permanent geologic sites. Many methods have been proposed. The most plausible is placing waste in inert areas, such as salt flats.
Also promising would be dropping waste to the deep sea bed and letting subduction—the sucking in of the earth's mantle material to lower depths—take it down. Subduction zones have a thick silt the consistency of peanut butter, so that a pointed canister packed with radioactives would slowly work its way down. Even canister leaks seem to prefer to ooze downward, not percolate back up. (One imagines a few million years later, when fossil wrist watches and lab gear begin appearing in fresh mountain ranges.)
The highest-tech solution would be launching it into the sun. Given that even the best rockets fail at least one percent of the time, this isn't a popular idea. Also, it would be far less demanding energetically to send waste packages all the way out of our solar system, as dubious interstellar ambassadors.
All these methods have good features and bad. The more active solutions seem politically impossible. Law of the Sea treaties, opposition to launching anything radioactive, and a general, pervasive Not in My Backyardism are potent forces.
The only method to survive political scrutiny is the Pilot Project, sitting in steel buildings amid utter desert waste a forty-five-minute drive from Carlsbad. The Department of Energy regards it as an experimental facility, and has fought endless rounds with environmentalists within and without New Mexico. Should they be allowed to fill this site with 800,000 barrels of low-grade nuclear waste—rags, rubber gloves, wiring, and the like? The refuse is to be packed into ordinary 55-gallon soft-steel drums, which will then be stacked to the ceilings of the wide alcoves that sprout off from the ample halls.
We climbed out of our carts and inspected the chunks of dirty salt carved from the walls by the giant boring machines. Everything looks imposingly solid, especially when one remembers that 2,150 feet of rock hang overhead.
But a central facet of the Pilot Project is that the walls are not firm at all. This Euclidean regularity was designed to flow, ooze, collapse.
We trooped into a circular room with a central shaft of carved salt. Meters placed around the area precisely recorded the temperature as electrical heaters pumped out steady warmth. The air was close, uncomfortable. I blinked, feeling woozy. Were the walls straight? No—they bulged inward. There was nothing wrong with my eyes.
Salt creeps. Warm up rock salt and it steadily fills in any vacancy, free of cracks or seams. This room had begun to close in on the heaters in a mere year. Within fifteen years of heating by radioactive waste left here, the spacious alcoves would wrap a final hard embrace around the steel drums. The steel would pop, disgorging the waste. None would leak out because the dense salt makes perfect seals—as attested by the lack of groundwater penetration anywhere in the immense salt flat, nearly a hundred miles on a side.
"Pilot" is a bureaucrat's way of saying two things at once: "This is but the first," plus "We believe it will work, but ..." Agencies despise uncertainties, but science is based on doing experiments that can fail only in a limited sense.
Often, scientific "failure" teaches you more than success. When Michaelson and Morley searched for signs of the Earth's velocity through the hypothetical ether filling all space, they came up empty-handed. But this result pointed toward Einstein's Special Theory of Relativity, which assumed that such an ether did not exist, and that light had the same velocity no matter how fast one moved, or in what direction.
An experiment that gives you a clear answer is not a failure; it can surprise you, though. Failure comes only when an experiment answers no question—usually because it's been done with ignorance or sloppiness, so the question it asks is muddled. The trick in science is to know what question your experiment is truly asking.
Bureaucrats aren't scientists; they fear failure, by which they mean unpredictability. Here the Department of Energy threaded through a far more vexing territory: advanced technology. The Pilot Project has been held up because equipment did not work quite right, because there are always uncertainties in geological data, and, of course, because environmental impact statements can embrace myriad possibilities.
Our job was by far the furthest-out environmental impact report anyone had ever summoned forth. No high technology project is a child of science alone; politics governs. The pressure on this Pilot Project arose from the fifty years of waste loitering in "temporary" storage on the grounds of nuclear power plants, weapons manufacturers, and assorted medical sites. The simmering wastes rested in "swimming pools" of water that absorbed the heat (but can leak), or in rusting drums stacked in open trenches or in warehouses built in the 1950s.
The long paralysis of all nuclear waste programs is quite probably more dangerous than any other policy, for none of our present methods was ever designed to work for even this long. Already some sites have measured some slight waste diffusion into topsoil; we are running out of time.
Of all the politically feasible sites in the USA, the Carlsbad area looked best. Its salt beds laid down in an evaporating ocean 240 million years ago testify to a stable geology, water free. The politics were favorable, too. Southern New Mexico is poor, envying Los Alamos and Albuquerque their technoprosperity. Dry, scrub desert seems an unlikely place for a future megalopolis to sprout—ignoring Los Angeles, which had a port and ocean nearby.
The Environmental Protection Agency, which developed the current safety standards, predicted that the Pilot Project would probably not cause more than one thousand deaths over the entire ten-thousand-year span. This is an upper limit; the most likely number is much smaller, about a hundred.
Yet we had already spent well over a billion dollars to prevent those roughly thousand deaths, or a million dollars per death! This, in a country where two million die annually, and the Department of Transportation spends about $100,000 to avert a traffic death on the highways. Such matters troubled many of us, but we had accepted the job, and it was interesting.
So we members of the Expert Judgment Panel split into four groups to separately reach an estimate of the probability that someone might accidentally intrude into the sprawling, embedded facility.
We had intense discussions about big subjects, reflecting the general rule that issues arouse intense emotion in inverse proportion to how much is known about them. Should we be doing more to protect our descendants, perhaps many thousands of years in the future, from today's hazardous materials? How do we even know what future to prepare for?
We usually foresee the future by reviewing the past, seeking long-term trends. Yet this can tell us little about the deep future beyond a thousand years.
A bit over two centuries ago, what is now the eastern United States was in the late English colonial period. At least in the European world, there were some resemblances to the current world—in fact, some countries have survived this long. For this period, extrapolation is useful in predicting at least the range and direction of what might happen.
Going back a thousand years takes us to the middle of the Middle Ages in Europe. Virtually no political institutions from this era survive, although the continuity of the Catholic Church suggests that religious institutions may enjoy longer lifetimes. Most history beyond a thousand years is hazy, especially on a regional scale. Prior to the Norman invasion in 1066, English history is sketchy. Beyond three thousand years lie vast unknowns; nine thousand years exceeds the span of present human history.
The probability of radical shifts in worldview and politics means that we cannot anticipate and warn future generations based on an understanding of the past, even when we anticipate the use of modern information storage capabilities.
There are three types of future hazards. The best are those we can identify and reduce or eliminate, such as DDT and other chemicals. More ominous are those we know little or nothing about, such as some additive or emission—for example, radioactivity wasn't thought to be harmful a century ago. Finally, there are hazards we know pose deep-future hazards but which we do not wish to ban—long-lived nuclear waste and toxic chemicals essential to industry.
Instead, we decide to continue producing these, and then shove them away in some dark corner, with warnings for the unwary and unaware. Ancient civilizations did this without a thought; Rome did not label its vast trash heaps, ripe with lead and disease.
Working on the panel was intriguing but frustrating. We used scenarios to help fix specific possibilities firmly in the mind, allowing us to pick assumptions and work out their implications using common sense in a direct, storytelling way. Like extrapolating from the past, scenarios reduce infinite permutations to a manageable, if broad, group of possibilities.
A few of us referred to classic science fiction works to draw out talking points. Walter Miller, Jr.'s A Canticle for Leibowitz, for example, artfully showed how knowledge, passing through time's strainer, can get muddled. Watching the social scientists particularly grapple with the wealth of possibility open to them, I came to realize how rare are the instincts and training of science fiction readers.
After much wrangling, we decided to make our musings concrete by writing scenarios detailed enough to consider the physical as well as the social environment. They would also be bounded within some range of assumptions, or else the game becomes like tennis with the net down; not doing this negates the usefulness of scenarios in the first place. What bounds seemed reasonable?
Our initial assumptions were:
* The repository will be closed after the proposed period of operation (twenty-five years).
* Only inadvertent intrusions were allowed; war, sabotage, terrorism, and similar activities are not addressed.
* Active control of the site will be maintained during the "loading" and for a century after closure.
* After active control, only passive measures will remain to warn potential intruders—no guards.
* The radioactive materials will decay at currently projected
rates, so the threat will be small in ten thousand years.
* No fantastic (although possible within ten thousand years) events will occur, such as extraterrestrial visits, big asteroid impacts, or antigravity.
Modern geology can yield firm predictions because ten millennia is little on the time scale of major changes in arid regions like New Mexico. By contrast, myriad societal changes could affect hazards, as readers of science fiction know well.
Our four-man subpanel—no women accepted the Sandia Lab invitations—worked out three basic story lines for life around the Pilot Project, based on the role of technology. There could be a steady rise in technology (Mole-Miner scenario), a rise and fall (Seesaw scenario), or altered political control of technology (the Free State of Chihuahua scenario). Envisioning these, arguing them through, was remarkably like writing a story.
The Mole Miner Scenario
If technology continues to advance, many problems disappear. As Arthur C. Clarke has remarked, "Any sufficiently advanced technology is indistinguishable from magic." A magically advanced technology is no worry, for holders of such lore scarcely need fear deep future hazards from present-day activities. Indeed, they may regard it as a valuable unnatural resource. The great pyramids, the grandest markers humanity has erected, were scavenged for their marble skins.
The societies that must concern us are advanced enough to intrude, yet not so far beyond us that the radioactive threat is trivial. Even though we assume technology improves, its progress may be slow and geographically uneven—remember that while Europe slept through its "dark ages," China discovered gunpowder and paper. It is quite possible that advanced techniques could blunder in, yet not be able to patch the leaks.
As an example, consider the evolution of mining exploration. Vertical or slant drilling is only a few centuries old. Its high present cost comes from equipment expenses and labor. An attractive alternative may arise with the development of artificial intelligences. A "smart mole" could be delivered to a desired depth through a conventional bored hole. The mole would have carefully designed expert systems for guidance and analysis, enough intelligence to assess results on its own, and motivation to labor ceaselessly in the cause of its masters—resource discovery.
The mole moves laterally through rock, perhaps fed by an external energy source (trailing cables), or an internal power plant. Speed is unnecessary here, so its tunneling rate can be quite low—perhaps a meter per day. It samples strata and moves along a self-correcting path to optimize its chances of finding the desired resource. Instead of a drill bit, it may use electron beams to chip away at the rock ahead of it. It will be able to "see" at least a short distance into solid rock with acoustic pulses, which then reflect from nearby masses and tell the mole what lies in its neighborhood. CAT-scan-like unraveling of the echoes could yield a detailed picture. Communication with its surface masters can be through seismological sensors to send messages—bursts of acoustic pulses of precise design which will tell surface listeners what the mole has found.
The details of the mole are unimportant. It represents the possibility of intrusion not from above, but from the sides or even below the Pilot Project. No surface markers will warn it off. Once intrusion occurs, isotopes could then escape along its already evacuated tunnel, out to the original bore hole and into groundwater.
This is the sort of technological trick science fiction so often explores, as a way of getting us to think about new approaches. I contributed most of this story, while the social scientists considered less optimistic ones.
The Seesaw Scenario
Many events could bring about a devastating and long-lasting world recession: famine, disease, population explosion, nuclear war, hoarding of remaining fossil fuels, global warming, ozone depletion. Then the rigors of institutional memory and maintenance would diminish, fade, and evaporate. Warning markers—and what they signify—could crumble into unintelligible rubble.
Later, perhaps centuries later, society could rebuild in areas especially suitable to agriculture and sedentary life. A tilt in the weather has brought moisture to what used to be southeastern New Mexico. Farming improves, prosperity returns.
Explorers would again probe the earth's crust for things they need. The political instabilities in the region during the dimly remembered Late Oil Age had kept some of the oil from being pumped out. A quest for better power sources for the irrigation systems of this reborn civilization then leads to the rediscovery of petroleum as an energy source.
A search of old texts shows that much oil drilling had been done in the Texas territory. Since all the oil was known to have been removed from that region, explorers turn westward to New Mexico. In the spring of A.D. 5623 an oil exploration team comes upon the remains of an imposing artifact in southeastern New Mexico.
"Perhaps they left it here to tell us that there's oil down below."
"Maybe there is danger. We should consult the scholars to see if they know anything about this."
"Ah, you know these old artifacts—all rusted junk. Forget them! Let's drill and see if there's oil...."
This strongly recalls A Canticle for Leibowitz—our "Expert Judgment" recreating classic science fiction in clunkier prose.
The Free State of Chihuahua
The year is 2583, just after a century of political upheaval in the former American Southwest. After endless wrangling caused by regional interests and perceived inequities in political representation, the United States has fragmented into a cluster of smaller nation states. Similar processes have affected the stability of Mexico, traditionally plagued by tensions between the relatively affluent North and the centralized political control of the South. Its northern provinces have formed the Free State of Chihuahua.
Political uncertainty in the Free State leads to a large-scale exodus of Anglo-Saxons, as well as many long-established Hispanic families, from the former U.S. territories. They are escorted by forces loyal to one or the other of the new countries, who practice a scorched earth policy, destroying most of the technological infrastructure, especially installations of potential military value, on the northern side of the former U.S.-Mexico border.
The Free State lacks foreign exchange and has a poor credit rating. Because it is limited in available natural resources, its people evolve into a scavenger society, recovering, repairing, and reusing all available technical artifacts from earlier times.
While excavating at the former site of Sandia Laboratory, Free State "resource archeologists" (fancily-named scavengers) discover references to the ancient Pilot Project site, including photographs of waste barrels filled with abandoned tools, cables, and clothing. They find fragmentary maps locating the site, but no references to radioactivity. In any case, social knowledge of radiation is limited, due to the development of nonnuclear energy sources during the twenty-first century—the Age of Ecology now long past.
Arriving at the site, Free State resource archeologists find the remains of markers that locate the site but do not transmit unambiguously the message that there is danger. They decide to enter. Later, the site is intentionally mined by people unaware of the potential hazard. They breach the site. Groundwater gushes up the drill, driven by the long-sealed heat of radioactive decay. Nobody can stop the gusher. A radioactive creek winds down to the riverbed, miles away.
This scenario reminds us that no nation has survived for more than a few centuries. Large states tend to fragment into smaller, more culturally coherent ones. For example, the Austro-Hungarian Empire is today divided amongst at least nine smaller countries, and something similar seems to be under way in the former Soviet Union only seven decades after its inception. Union with northern Mexico is not critical to the scenario—one can visualize a variety of ways for political control to change. As control alters, chances for inadvertent intrusion rise.
Cultural shifts can have the same effect. Suppose that in 2100 a feminist mining company comes upon our warning markers and finds them to be "another example of inadequate, inferior, and muddled masculine thinking"—and ignores them.
Other scenarios developed by the teams were quite imaginative. Suppose a Houston-to-Los Angeles tunnel breached the site? Or that a religious cult hostile to science disbelieved the warnings. Treasure hunters might have the same skepticism. Illiterates also could fail to fathom the redundant markers. A huge spaceship in the year 11,911 could crash into the deep site.
These sketched out the vast possibilities, though the panel members assigned most of them very low probability.
Gabriel Garcia Marquez's One Hundred Years of Solitude alerted many of us to the subtle cultural differences between North and South America. Trying to store waste for ten thousand years of solitude reminds us, in turn, that cultural and geographical boundaries make no difference over such eras.
For example, an unspoken constraint on the U.S. program is that the waste must be stored within the country. Why not find better spots elsewhere? Mexico has many salt flats larger than the Carlsbad site. Some might well prove better, too.
The temporary constraints of politics prevented us from thinking along those lines. Under what other blinders, even unconscious ones, did we labor?
RISKS AND RELATIVES
One of the ethical philosophers on the sixteen-man Expert Judgment Panel found the prospect of international traffic in waste abhorrent. "Risk," he pronounced, "is not morally transferable."
But of course it is; we do it every day. Anyone who works in a coal mine or commutes on a heavily traveled highway incurs extra risk for some gain. Those who burn the coal or use the goods moved on the road benefit from others' activity, yet do not share the risk.
How much risk to accept is a personal decision. The ethical pivot, we felt, was that people should know the dangers they undertake.
But the Pilot Project points to a deeper problem. Over ten thousand years, no continuity of kinship or culture respects borders. Mexicans are the same as, say, New Yorkers—populations shift, societies alter. Risks resolutely kept in New Mexico are the same as risks piled up in Mexico City, for the people diffuse over these passing perimeters within a few centuries. The idea of nationality fades. Only two centuries ago Spain ruled both sites. We really are all in this together, in the long run.
This ethical relativity further questions the basic motivation in the congressional orders. Spending $1.8 billion on the Pilot Project to avert far future deaths calls into question whether we could do something more effective with the money. As panel physicist, Bernard Cohen, discussed, this brings in economic discounting of such investments. A single dollar in a trust fund set up now at three percent interest would yield in a thousand years $6 trillion!
Spending all but a single buck of the Pilot Project's price on present safety measures could save millions of lives over a millennium, or an average of thousands per year. With the extra dollar, we could send down the timeline bales of money to help our distant descendants. Similar investment in biomedical research now would have equally spectacular results.
Indeed, the World Health Organization estimates that fifty dollars could prevent a measles death right now in Gambia and Cameroon, or $210 per life for immunizations in Indonesia. "Since we are not spending this money to save present lives, it does not seem reasonable to spend more money to save far future lives," Cohen remarked. After all, the neighbors of the Pilot Project a millennium from now probably will be as distant from us by many measures—cultural, genetic—as the Gambians are now.
The general objection to this way of thinking is that future beneficiaries from a trust fund are not those who may be sickened by radioactive leakage. Quite so; and further, we have no way to untangle these populations.
Such arguments strongly suggest that our gut feelings do not match with classical economic discounting methods. Economists assume that an investment can carry forward undisturbed, gaining an immense multiplier effect. But never has this happened over a thousand years; banks go bankrupt, commodities crash, empires evaporate. People intuitively trust their sense of human connection more than interest rates. This is why they ignore discounting in the perspective of deep time.
This raises the question of whether there is an ethical horizon. Is there some future time, past which fretting is pointless? Physicist Hal Lewis has remarked, "No law of nature asserts that the future is less relevant than the present, but people have behaved for many centuries as if it were." Survival, he notes, is the single most important duty we have to our descendants, for without it, they won't exist. "It is pretentious to suppose that they will share our sense of values, or that we can predict their needs."
Lewis is just one of many physicists who scoffed at our congressional mandate of insuring for ten thousand years. Congress was simply adopting the Environmental Protection Agency's original 1985 regulations, but this missed significant facts.
Within a few centuries most of the Pilot Project's waste will have decayed to a few percent of its present level, though some isotopes will persist much longer. At ten thousand years it will have returned to the level of radioactivity the original ore had before it was mined for uranium; apparently, this is how Congress picked the number 10,000. Lewis points out that a single penny invested now would yield a trust fund to cover medical expenses of $10 billion in just 700 years. Indeed, the only way to set aside less than $10 billion would be to put off investing the penny until more than nine thousand years had passed. Lewis remarks, "Imagine, ten thousand years, for a country that is barely two hundred years old."
I am sympathetic to such views. Anxiety over risks from waste does not justify ignoring the simple numbers that show that we are wasting money as well.
Still, Congress wanted its estimate. We forged ahead.
Of course, our scenarios did not exhaust all possibilities; they only sketched out the conceptual ground. Our panel also considered a "USA Forever" yarn that assumed government could indeed keep continuous control. It yielded a smaller risk, but we thought it had much smaller probability of coming true.
Such stories are fine, but how could we use them to predict quantitative probabilities? Congress wanted a number, not a short-story anthology.
We believed two elements of these scenarios most directly affect the likelihood of inadvertent intrusion: political control of the site region, and the pattern of future technological development. How could we use this intuition?
Here we used a "probability tree," which links chains of events numerically. We began by assigning simple estimates of the likelihood of single, important events. Then we multiplied these to get the total probability that a sequence of events will happen. After much wrangling, we settled on a ballpark estimate of less than ten percent chance the site would suffer intrusion.
The major risk came from the seesaw scenario of technological decline and rebuilding. Information lost because of disrupted cultural continuity meant that people could again and again make the same, simple mistakes. They might drill or mine with modest technology, unable to sense the radioactivity before they reached it, then leaving an open shaft for it to leak through.
A quick estimate can give the probability of such drilling intrusion. Research showed that the neighborhood suffered roughly one drilling per year over the last century. Assuming random drilling around the approximately four hundred square miles, the buried waste's area of about half a square mile should then have a probability of 0.001 per year of drilled intrusion. If over ten thousand years such eras occur a hundredth of the time—that is, a century in all—then there is a one percent total probability. Adding in other scenarios gives a final sum of a few percent.
Did we believe this? Of course not, in its details. There was no reason at all to prefer our guess that wildcatters would return one percent of the time. But it seemed a plausible estimate, given admittedly limited experience in the modern age.
We wrote up our result and found that the other three teams of four each had gotten the same few percent result. This added a heartening note of certainty to our otherwise rather surrealistic task. I reassured the head of the program that we could even guarantee the answer. "If there's an intrusion, I'll pay back ten times my consulting fee ... ten thousand years from now."
Then I learned that since we finished our report first, the other teams knew our answer before they finished theirs—bad technique. A convergence of opinion is common in all prognosticating, and "experts" like us were not immune to it.
I had further worries. Physics has dominated our century, but biology may well rule the next. The implications of the Human Genome Project and rapid progress in biotechnology remind us of a more general truth: the most difficult realization about the future is that it can be qualitatively different than the present and past. This implies that an irreducible unknown in all our estimates arises from our very worldview itself, which is inevitably ethnocentric and timebound.
Are we being too arrogant when we assume we can accurately anticipate far future hazards or protection mechanisms? Probably—but we have no choice. Waste of all sorts stacks up and we must do our best to offset its long-term effects.
The Department of Energy was happy with our estimate. They and Congress could tolerate risks up to about ten percent. At present, the Pilot Project staff is finishing a trial run to further study the salt creep, how it seals, and other final technical details.
Personally, I believe the Pilot Project caverns will be filled, and that's only the beginning. Storing all our accumulated nuclear waste, not just the low-radioactivity debris the Pilot Project is designed for, would take about ten more such vaults.
What would be the point, politically or practically, in dispersing the sites? The only other site for disposal, Yucca Mountain in Nevada, is under heavy technical and political pressure. All our waste for a century could go into that single salt flat near Carlsbad.
Confining the area both lowers costs, reduces total risk, and localizes damage if it occurs. It's also politically astute. The locals want the work, and the opponents in northern New Mexico have nearly run out of legal delays. They seemed to operate out of a Not in My Backyard psychology, with no alternatives.
Part of the problem with waste of all sorts is that fears have been blown so high, few really perceive the rather minute level of risk. That was why congressional fretting over ten thousand years from now seemed so bizarre to the panel, which actually knew something about real risks. An ironic joke circulated: How many nuclear engineers does Congress think it takes to change a lightbulb? Seven: One to install the bulb and six to figure out what to do with the old bulb for the next ten thousand years.
During our deliberations, television stations sent their cameras and environmentalists demonstrated. I asked one of the placard-carrying men where he was from. "Santa Fe," he answered. I was surprised; he lives many hundreds of miles from the site. "They might bring some of that waste through my town, though," he said.
He was right. Spills during transport are a real, if remote, possibility. I wanted to talk to him further about sentiment in Santa Fe, which leads opposition to the site, but I couldn't tolerate his company any longer. He was puffing steadily on a Marlboro.
He could well claim that smoking was his choice, his risk—and unless he spoke out, he had no control whatever over nuclear waste. True enough—but then, there is always secondhand smoke. And the waste was generated by the federal government, an obligation settled upon all of us.
Neither Congress nor the Department of Energy has pondered the long-term issue of disposal in one site yet, but I believe it is obviously coming. The waste must go somewhere.
If we halted all nuclear power and weapons production tomorrow, we would still have a vast pile of medical contamination to care for. Nobody, I believe, wants to do away with cancer diagnostics and treatments, which produce great volumes of mildly radioactive waste.
Despite opposition, I believe eventually even local politics and bureaucratic lethargy will be unable to stop interment of wastes in the salt flats of southern New Mexico, probably before the year 2000. A government which has already invested $1.8 billion does not relish walking away from it.
Whether one regards this as a good idea or not, the political fact is that we have largely run out of time to decide how to store wastes. Holding even low grade radioactive wastes in "swimming pools," as we do now, runs real risks and can't be simply continued for, say, another century. The stuff leaks into groundwater. Increasingly, the public wants all sorts of wastes, nuclear or chemical or biological, interred far, far away from them.
Most likely, the problem will persist indefinitely. Will people give up X rays and cancer treatments? We are stuck with our largely unrecognized reach into deep time. Seemingly minor acts today can amplify through millennia, leaving legacies we do not consciously intend. Deep time has become ever-present in our age.
Given this, how will we protect future generations from such deep-future hazards, warning them about the dangerous package we've sent down the timeline? How does one send a deep time warning across ten millennia? A whole new panel pondered that question, opening up still more vexing issues.
THE EVANESCENCE OF MARKERS
The Department of Energy created two separate second panels to discuss the marker problem in detail, using necessarily science-fictional logic. I did not serve on them; the panel memberships were separate, so that the Marker panels could get some independent perspective on our recommendations. Since I knew several Marker Panel members—Frank Drake, Jon Lomberg, Louis Narens—I followed the arguments from the sidelines. Like us, they found the job to be just about the most fun possible to have while working for the government.
An illuminating moment had already come after a day of intense discussion among our so-called Expert Judgment Panel, as we considered what advice to give the Marker panels. The group spanned most sciences and was unafraid of speculative thinking. This included people like Theodore Taylor, an authority on nuclear devices, and the inventor of the 1960's Project Orion idea—spaceships driven by nuclear warhead explosions. He suggested that we detour near the Pilot Project site to find the site of Project Gnome, a nuclear test.
In 1961, Project Plowshare exploded a small warhead a thousand feet down in the same salt flat that the Pilot Project wanted to use for nuclear waste storage. The idea was to heat up rock salt and use the molten mass's residual heat to drive steam through electrical generators. It failed because the blasted-out cavity soon caved in, burying the molten salt. One would think this might have occurred to an engineer before they tried it. But that was in the golden years of nuclear development, when ideas got tried for size right away, rather than spending a decade or so mounting up piles of paper studies.
We all got out of our government-gray cars and the drivers waved vaguely at the flat scrub desert, dust devils stirring among the sage. We spread out, shooing away grazing cattle. A hoot of discovery. A granite slab, tombstone-sized, bearing a rectangular copper plaque running green from oxidation. In big letters:
followed by GLEN SEABORG, then director of the Atomic Energy Commission, and in smaller type the generals and bureaucrats who had overseen this failed effort.
I walked around the slab and saw another plaque, its raised lettering rusted and nearly unreadable. We could barely make out some technical detail: kilotons, warhead type, purpose, amount of residual radioactivity. At the very bottom:
THIS SITE WILL REMAIN DANGEROUS FOR 24,000 YEARS.
If we hadn't known our quarry, we would not have found it easily out on the dry plain. Drab, small, it did not announce itself. We could tell, though, that it had been moved. Apparently, cattle needing a rubbing post had in thirty years nudged the slab several meters. How far away would it be in 24,000 years?
Ever the mathematical physicist, I reasoned that this resembled the famous "drunkard's walk," diffusionlike process. Standing in the dry desert breeze, I imagined cows bumping the worn marker in a random way. Then by standard theory, the distance wandered went up as the square root of time. If it moved, say, a meter in thirty years, then it would be about thirty meters away in 24,000 years.
Not too far to be still useful; the plaque was safe from cattle. But suppose something nonrandom decided to move it—such as a human needing chunks for a riprap wall?
This experience brought to my mind a worry: Could warning markers be self-defeating? There lurked behind our assumptions a more basic decision: whether to mark hazardous sites at all. Could the most effective warning be no warning?
Egypt's only major unviolated burial site, King Tut's tomb, provided us with much of the Egyptian legacy. Unmarked and forgotten because its entrance was soon buried under the tailings of a grander tomb, it escaped the grave robbers, who may well have included the priests of the time.
Could a hidden or forgotten hazard protect itself from harming future generations best of all? A "soft" surface marker that erodes in a few centuries would cover the short-term possibilities, I argued, and then avoid curiosity seekers in the far future. Without any clear sign that something important lay so far below, grave robbers of whatever stripe would have to be awfully ambitious to dig down over two thousand feet, on pure speculation. As well, high technologies would still be able to sense the buried markers, after all.
But this imposes ignorance on our descendants, who may wish to avoid the place but not know quite where it is. Also, low-tech wildcatters drilling for scarce resources in some reemergent future would have no warning, and they might be the most probable trespassers.
Still, I proposed this notion, mostly for fun. Many of our most valued finds from antiquity were hidden, by accident or otherwise, from prying descendants. I suggested that standard-issue government concrete would be useful here: it disintegrates in about a century or so, providing everyone with a big, noticeable object for a reassuring lifetime, then erasing it.
Nobody much liked the idea, as I'd guessed. The later Marker panels rejected it, citing moral concerns, by analogy with printing warnings on cigarette packages. In the end this is a choice between two ends—knowledge against safety—mingling with the later issue of how markers might attract interest.
There was another issue, never expressed explicitly. I'm sure we had all imagined standing on a hill a few decades later, dwarfed by a grand monument, knowing that we had some small hand in putting it there. One of the major psychic payoffs in considering markers at all is the Pharaoh effect: the impulse to build a big monument to ... well, yourself. Or at least your era. They won't forget us right away! Even better if somebody else (the Pharaoh's subjects, say, or the poor taxpayer) foots the bill.
Our panel, charged with estimating the chances of inadvertent intrusion into the Pilot Project salt flat buried 2,150 feet down, also suggested possible strategies for placing warning markers.
We had envisioned "miner moles" that would slowly tunnel through deep strata, searching for neglected lodes of valuable minerals. This implied a "spherical strategy"—deploying markers that were magnetically apparent from above, beside, and even below the deep repository.
The Pharaohs used one big, obvious marker for their tombs—the pyramid; we suggested as well small, dispersed tags, visible to "eyes" that could see magnetic or acoustic or weakly radioactive signs. Acoustically obvious markers could be made—solid rock unlikely to shatter and lose shape in the salt beds.
Large granite disks or spheres might be easily perceived by acoustic probes. They could be arrayed in two straight lines in the repository hallways, intersecting perpendicularly at the center: X marks the spot. These could be magnetized iron deposits, flagrantly artificial. Specially made high-field permanent magnets could produce a clearly artificial pattern, the simplest being a strong, single dipole located at the hazard's center. (This I took from 2001: A Space Odyssey by Arthur C. Clarke.)
Radioactive markers could be left at least meters outside the bulk of the waste rooms and drifts—say, small samples of common waste isotopes. Like similar weak but telltale markers left on or near the surface, these have the advantage of showing the potential intruder exactly what he is about to get into. No language problem.
All these markers should be detectable from differing distances from the waste itself. Acoustic prospecting in the neighborhood could pick up the granite arrays. Magnetic detectors, perhaps even a pocket compass, could sense the deep iron markers from the surface. Ultrasensitive particle detectors might detect the waste itself, or small tags with samples of the waste buried a safe distance belowground. These would be small amounts, of no health risk to the curious—weaker than a radium watch, yet slowly decaying.
Considering vast stretches of time tends to bring on lofty sentiments. But the present is mostly ruled by money, so as an example, the Marker panels worked out the costs of erecting a Cheops pyramid, which has lasted 4,600 years. Using square blocks of granite, nine feet on each side, one could engrave all six sides with warning messages.
That way, if the exterior faces wear away, lifting one block would uncover a fresh inscription. The pyramid core could hold, not a Pharaoh, but a set of more detailed messages, for those in the future who will dig out of simple curiosity (archeologists), or those suspecting that there's a treasure in here somewhere—else why go to all the trouble?
Making all the blocks of the same material eliminates problems arising from different thermal expansion rates, which can cause cracks. Tapering the pyramid less steeply than the natural slope of a sand pile would avoid much damage from earthquakes. Like the Cheops pyramid, the load-bearing stress would be wholly compressive, using only gravity to hold it all together, with no tensile forces that open cracks.
This is expensive. If a single inscribed block costs $5,000, they would cost $62 million, about six percent of the to-date cost of the Pilot Project (though less than one percent of the projected cost over the site's entire active use).
This is no accident. Considering many different markers taught a tough lesson: longevity trades off against cost. There is no simple, good, cheap marker.
Thinking like a cost-conscious Pharaoh, suppose we make the blocks smaller, to ease assembly costs. That makes them easily climbed, increasing vandalism. It also means ordinary sized people can reach all the inscriptions without a ladder.
That opens a larger question: the biggest threat to the Pharaoh's pyramids and to a nuclear marker pyramid is pesky, grasping humans. In historic sites, metals quickly vanished and buildings were quarried. Useful, cubic blocks especially might be carted away. The Cheops lost all its cladding marble skin quite quickly; ancient Greek travelers remarked on how they could be seen as bright white beacons far across the desert, but no modern observer has found any of that left. (The Washington Monument was vandalized immediately after it opened in 1888, and the interior stairwell had to be permanently closed. Vandals don't respect greatness.)
One could offset such problems. For example, using interlocking but irregularly shaped blocks would stop their use elsewhere. Making the materials outright obnoxious might help, too—but stones that exude a bad smell steadily evaporate away, destroying the structure.
A better path might be to make the marker hard to take apart. Here the clear winner is reinforced concrete. The Cheops would take much less work to tear down than it was to build up, but the reverse is true, for example, of the Maginot and Siegfried lines of the world wars. Despite intense political pressure from local communities, the bunkers have proved to be too costly to take away. Contrast the colosseum in Rome, which has suffered greatly, with most of its building stones "recycled" into houses.
Probably the ancients understood this principle quite well, since Stonehenge (1500 B.C.) used blocks of up to fifty-four tons, and English tombs (2000 to 3000 B.C.) used stones of up to a hundred tons. They thought the trouble was worth long-term insurance. Our experience with concrete goes back two thousand years; six of the eight Roman bridges built across the Tiber are still in service! We must be a bit cautious here, though, because it is quite possible that Roman concrete was better than ours.
This is because strong concrete demands a low ratio of cement to water, a very stiff mix that is tough and pricey to work with. The Romans used slave labor to ram firm concrete into place, and today's contractors pump a sloppy, muddy mix through pipes. This can make the concrete twenty times less durable than the dry, high-grade sort.
But even such precautions run into a sad lesson of history. Pyramids and other grand structures often mark honored events or people. This might be the primary message a pyramid sends: here's something or somebody important. Why not come see? And surely such a big monument won't miss this little chunk I can pry off ...
|Introduction: From Here to Eternity||1|
|Pt. 1||Ten Thousand Years of Solitude||31|
|Pt. 2||Vaults in Vacuum||87|
|Pt. 3||The Library of Life||135|
|Pt. 4||Stewards of the Earth: The World as Message||169|