Modern technology projects our grasp
across great distances. Our Voyager space craft glide serenely beyond the solar
system, headed out forever. Less obvious is our technology's reach through
We peer backward through tree ring
dating (good to about 5,000 years), Arctic ice bores (which measures layers of
ice, good to about 200,000 years), and nuclear dating methods (good for the
Earth's age, about 4.6 billion years). Through the astronomical time machine
given by light's finite speed—the so-called "look-back"
time—we can look out to several more
billion years, culminating in the recent scrutiny of the early universe
radiation, we have seen structure as it was about fifteen billion years ago,
only perhaps a few million years after the universe began.
We are much less aware of our reach in
the other direction, the future. The Voyager probes carry plaques rhapsodizing
over our culture, gestures which might be read billions of years from now.
Cosmic time capsules. But on Earth, until this century, the Pharaohs were the
champions at knowingly reaching down to their posterity—less
than 6,000 years.
Nuclear physics changed all that. Now
we leave a legacy—on the earth's surface, not gliding
serenely though space—through the long half-lives of the
radioactive byproducts of nuclear power, weaponry and medicine. These will be
around for tens of thousands of years. Chemical wastes may also be as
In my last column I described my
adventures when asked by the Department of Energy, acting for Congress, to
estimate the risks of inadvertent disturbance of a projected nuclear waste
repository (the Waste Interment Pilot Project) for the next ten thousand years.
We estimated the probability at a few percent.
I believe eventually even Not In My
Back Yard politics will be unable to stop interment of wastes in the salt flats
of southern New Mexico. 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, gets into ground water. Increasingly,
the public wants all sorts of wastes, nuclear or chemical or biological,
interred far, far away from them.
Given this, how will we protect future
generations from such deep-future hazards? How to warn them off the site? A
second panel discussed the marker problem in detail, with necessarily
science-fictional logic. I found all this to be just about the most fun
possible while working for the government.
One illuminating moment came after a
day of intense discussion among the so-called Expert Judgment Panel. I was the
only science fiction writer there, but the group spanned most sciences,
including people like Theodore Taylor, the inventor of the Project Orion idea—spaceships
driven by nuclear warhead explosions—in the 1950s. We decided to 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 which 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
It failed. 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 copper plaque running green
from oxidation. In big letters, PROJECT GNOME, 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
If we hadn't known our quarry, we
would not have found it easily out on the dry plain. Drab, small, it did not
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?
Our team, 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
envisioned "miner moles" which would slowly tunnel through deep
strata, searching for neglected lodes of valuable minerals. This implied a
"spherical strategy"—deploying markers 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" which could see magnetic or acoustic or 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. Magnetic markers could produce a clearly artificial pattern,
the simplest being a strong, single dipole located at the Pilot Project center.
These could be magnetized iron deposits, flagrantly artificial. Specially made
high-field permanent magnets could produce a clearly artificial pattern at the
hazard's center. (This I stole from 2001: A Space Odyssey; thanks,
Radioactive markers could be left at
least some 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.
Ultra-sensitive particle detectors might detect the waste itself, or small tags
with samples of the waste buried a safe distance below ground. (These would be
small amounts, of no health risk to the curious—weaker
than a radium watch, yet slowly decaying.)
there's a more basic decision: whether to mark hazardous sites at all. Perhaps
the best warning is no warning. The only major inviolate 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.
a hidden or forgotten hazard protect itself from harming future generations
best of all? A "soft" surface marker which erodes in a few centuries
would cover the short-term possibilities, I argued, and then avoid curiosity
seekers in the far future. High technologies would still be able to sense the
buried markers, after all.
course, 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 re-emergent future would have no warning.
I proposed this, mostly for fun. 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
much liked the idea, as I'd guessed. 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 poor taxpayer) foots the bill.
vast stretches of time tends to bring on lofty sentiments. But the present is
mostly ruled by money, so as an example, the panel worked out the costs of
erecting a Cheops pyramid, which has lasted 4,600 years. Using square blocks of
granite, 9x9x9 feet, one could engrave all six sides with warning messages.
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 in out of simple
curiosity (archaeologists), or those suspecting that there's a treasure in
there somewhere, or else why go to all the trouble?
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
which open cracks.
is, that's 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.
is no accident. Considering many different markers taught a tough lesson:
longevity trades off against cost. There is no simple, good, cheap marker.
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.
opens a larger question: the greatest 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.
cubic blocks especially might be carted away. The Cheops pyramid 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. (Indeed, it is worth remembering that
the Washington Monument was vandalized immediately after it opened in 1886, and
the interior stairwell had to be permanently closed. Vandals don't respect
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.
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.
the ancients understood this principle quite well, since Stonehenge (1500 BC)
used blocks of up to 54 tons and English tombs (2000 to 3000 BC) used stones of
up to 100 tons. They thought the trouble was worth long-term insurance.
experience with concrete goes back 2,000 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
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.
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
led both panels of experts toward marker systems—different-sized
components, relating to each other so that the whole exceeds the sum of the
parts. Vandalism doesn't usually take everything, so the message gets through
in a holographic sense. (About a third of the Stonehenge stones are missing,
yet we can infer the entire design without much dispute. People differ over
whether there is evidence of Mycenaean Greek influence in the architectural
niceties, or just what the building was truly for, but its layout is clear.)
best way to insure survival of truly enormous structures against both weather
and pilfering is to make them out of dirt. Prehistoric mounds last well. The
Romans build a long wall to keep out the Teutonic tribes, stretching from the
Danube to the Rhine. Even in that wet climate, while the wood is completely
gone, the earth berms survive. Hadrian's Wall in England is a similar case. The
record is held by a chambered passage grave which is today a simple mounded
earthwork in Ireland, older than 5,000 years.
panels thought along truly gargantuan lines. A simple berm of, say, thirty-five
meters wide and fifteen meters high, completely ringing the Pilot Project area,
would demand moving about 12 million cubic meters of earth. The Panama Canal
moved 72.6 million cubic meters, and the Great Pyramid occupies 2.4 million
cubic meters. So this will be one of the grandest public works in history.
initially to greet the tourist, who might mistake even a huge berm for a
natural hill, ten thousand years from now. To get their attention, the panels
wanted a ring of monoliths, probably of granite, bearing a variety of symbolic,
pictographic and linguistic inscriptions.
and other sites have taught us that to keep monoliths upright, more must be
buried than is exposed, or else it should be firmly stuck in a rock layer
below. They will probably have to be erect, too, because slanted monoliths have
a poor track record. They develop tensile stresses at the surface, and in
brittle material like granite, once a crack develops, it reaches a critical
length—and then the whole monolith splits.
are good reasons to make none of these from composite materials—thermal
stresses, as in the pyramid. This means the monoliths will be imposing,
homogeneous rock, arranged in patterns that convey our message of threat.
prudence suggests that we should also scatter small markers around the site,
perhaps slightly buried, which attract attention even if the monoliths somehow
fail. The panels considered electrically active markers, reasoning that
thermo-electric power (which would use the temperature difference between the
surface and 100 feet below) or solar power is available.
trouble is that even the most reliable electronic components, such as those
used in undersea cables, only last a few centuries. More reliably, we could
embed contrasting dielectric materials in the site surface, which reflect radar
differently. These would give a good, artificial signal to airplanes or even
could also bury time capsules, just a bit below the usual souvenir-hunter's
digging zone, made of tough stuff—baked clay, tektite-like glass. These
might be tablets, far better than the mud tablets the Babylonians left
everyone agreed that there should be some sort of central chamber, where
detailed messages are left. It would have a lot of plane surfaces for messages
and could be completely buried. It can also include buried magnets, which would
be detectable with a good pocket compass even if all surface signs of the site
vanish. Their fields could point at the buried waste.
we elect to put this central room above ground, there are several ways to go.
We could use messages chiseled into granite, such as the biography of a Persian
king, Darius I, which has lasted over 2,000 years in open, dry weather. It had
to contend with blown sand and carbonic acid in rain, but not with the sulfuric
acid belched out by coal-fired plants, as now exist within a few hundred miles
of the Pilot site.
2,000 years, consider a faint carving of a square-hilted dagger on the inner
surface of a sarsen stone, which survived in an open field at Stonehenge for
perhaps 4,000 years. So expecting detailed messages to last 10,000 years is
a buried vault is our best bet—just what the Pharaohs chose. It would
be the most interesting and complex marker in the whole site, well hidden,
purposely designed to be the world's longest-lasting human artifact. If the
above-ground monoliths were strikingly beautiful, maybe the locals will
preserve the site because it is pleasing, rather than for its message—thus
letting the message travel longer through time, perhaps to a more distant era
which needs it more. Saving the striking, obvious structure would leave the
vault below undisturbed.
visitor would meet first the encircling earthworks, then a ring of monoliths—say,
as wide as the length of a soccer field—and finally some central marker that
would tell (or suggest) the buried chamber. The idea is to draw them in, make
them feel psychologically enclosed in the monolith circle, become
"involved" with the stone monuments at the center, induced to read
the pictographs and messages inscribed.
it would be smart to convey the general emotional message in some direct
way, independent of language. Suppose we erect some aerodynamically streamlined
monoliths with gaps between them. These resonate in the wind, sending forth a
hollow, mournful note. Most likely, such wailing rocks could establish a legend
about the site that transcends language.
the rub—getting through to cultures and
languages we cannot anticipate. The future may see our scientific age as a
passing phenomenon, an idiosyncratic momentary deflection from some One True
Path we would not even recognize. So how can we expect them to share our (often
unspoken) assumptions, and thus read our warnings?
we can't. But there are ways of shaping a message so that it has some plausible
chance of sailing intact across the great ocean of Deep Time. I'll take up
those methods in my next column.
may not be able to predict the future, but we can reach it nevertheless. One
could characterize nuclear waste containers at WIPP as hazardous time capsules
sent into the future, not knowing where they will land or what effect they will
have, hoping (perhaps even assuming) that technology will solve the problems
they currently represent.
a sense the Pilot's task runs against powerful human archetypes. We aren't
saying, as burial ceremonies do, "Take this child—his
name is Klug." or "This mummy of our king we place here, for he needs
resurrection." Instead, we're trying to say: We buried this and it's bad.
only other alternative to this millennia-spanning waste problem is to forswear
hazardous technologies in the first place; but we already have plenty of waste,
with more accumulating from medical uses alone, so there really is no going
back. Besides, how do you get people to 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 Deep Time, leaving legacies we do not
intend and in fact may not even know.
closing, consider Trinity Site, the spot where the first A-bomb was tested in
1945. At Ground Zero in White Sands, New Mexico, the blast left a glassy crater
of fused aluminum silicates a quarter mile across and twenty-five feet deep.
there is nothing. Dry winds had filled the crater, tough desert plants had
cracked it. Radiation levels are very slightly higher than the background of
ordinary scrub desert. Life had reclaimed its territory in a single human
generation. The "message" of Trinity is gone.
easy problem of Deep Time is time's rub. Greater still is the abyss of culture
we must cross.
barren Trinity site recalls Shelley's "Ozymandias":
And on the pedestal these words appear:
"My name is Ozymandias. King of Kings:
Look on my works, ye Mighty, and despair!"
Nothing besides remains. Round the decay
Of that colossal wreck, boundless and bare
The lone and level sands stretch far away.
Time is as much the province of the poet as of the scientist.