Chapter One
Clock of Ages
December 1999. As the world spirals on toward 01-01-00, survivalists are hoarding cash, canned goods, and shotgun shells. It's not the Rapture or the Revolution they await, but a technological apocalypse. Y2K! The lights are going out, they warn.Banks will fail. Airplanes may crash. Your VCR will go on the blink. Who could have foreseen such turmoil? Decades back, one might have predicted anxiety and unrest at the end of the millennium, but no one could have guessed that the cause would be an obscure shortcut written into computer software by unknown programmers of the 1960s and '70s. To save a few bytes of computer memory, they left room for only the final two digits of the year.
We now know that civilization did not collapse on January 1, 2000. Y2K was a nonevent. Nevertheless, in hindsight those programmers do seem to have been pretty short on foresight. How could they have failed to look beyond year 99? But I give themthe benefit of the doubt. All the evidence suggests they were neither stupid nor malicious. What led to the Y2K bug was not arrogant indifference to the future. ("I'll be retired by then. Let the next shift fix it.") On the contrary, it was an excess of modesty. ("There's no way my code will still be running thirty years from now.") The programmers could not envision that their hurried hacks and kludges would become the next generation's "legacy systems."
Against this background of throwaway products that somebody forgot to throw away, it may be instructive to reflect on a computational device built in a much different spirit. This is a machine carefully crafted for Y2K compliance, even though it was manufactured at a time when the millennium was still a couple of lifetimes away. As a matter of fact, the computer is equipped to run through the year 9999, and perhaps even beyond with a simple Y10K patch. This achievement might serve as an object lesson to the software engineers of the present era. But I am not quite sure just what the lesson is.
A Glory of Gears
The machine I speak of is the astronomical clock of Strasbourg Cathedral, built and rebuilt several times over the past sixhundred years. The present version is a nineteenth-century construction, still ticking along smartly at age 160-something.
The Strasbourg Cathedral clock is not a tower clock, like Big Ben in London, meant to broadcast the hours to the city. Although it does have a face on the exterior of the building—a rather undistinguished one that would look more at home ona train station—the main body of the clock is inside the cathedral. And yet it is certainly not a clock you would puton the mantel or hang on the wall. It has a case of carved stone and wood that stands fifty feet high and twenty-four feet wide, with three ornamented spires and a gigantic instrument panel of dials and globes, plus paintings, statuary, and a large cast of performing automata. Inside the clock is a glory of gears.
"Clock" is hardly an adequate description. More than a timepiece, it is an astronomical and calendrical computer. A celestial globe in front of the main cabinet tracks the positions of five thousand stars, while a device much like an orrery models the motions of the six inner planets. The current phase of the moon is indicated by a rotating globe, half-gilt and half-black.
If you want to know what time it is, the clock offers a choice of answers. A dial mounted on the celestial globe shows sidereal time, as measured by the earth's rotation with respect to the fixed stars. A larger dial on the front of the clock indicates local solar time, which is essentially what a sundial provides; the prick of noon by this measure always comes when the sun is highest overhead. The pointer for local lunar time is similarly synchronized to the height of the moon. (When the solar and lunar pointers coincide, an eclipse is predicted.) Still another dial, with familiar-looking hour and minute hands, shows mean solar time, which averages out the seasonal variations in the earth's orbit to make all days equal in length, exactly twenty-four hours. A second pair of hands on the same dial shows civil time, which in Strasbourg runs thirty minutes ahead of mean solar time. (The city is half a time zone west of the reference meridian for Central European time.)
To count the years there is an inconspicuous four-digit register that anyone from our age of automobiles will instantly recognize as an odometer. Each December 31 at midnight (that's midnight mean solar time, and thus half an hour late by French official time), the counter rolls over to a new year. The transition from 1999 to 2000 went without a hitch.
There's more. A golden wheel nine feet in diameter, marked off into 365 divisions, turns once a year, while Apollo stands at one side to point out today's date. What about leap years? Presto: an extra day magically appears on the wheel when needed. Each daily slot on the calendar wheel is marked with the name of a saint or with some church occasion to be observed that day. Of particular importance, the occasions include Easter and the other "movable feasts" of the ecclesiastical calendar. Calculating the dates of those holidays, and displaying them correctly on the wheel of days, require impressive feats of mechanical trickery.
Wait! There's even more! The clock is inhabited by enough animated figures to open a small theme park. The day of the week is marked by a slow procession of seven Greco-Roman gods in chariots. At noon each day the twelve apostles appear, salutinga figure of Christ, who blesses each in turn and at the end offers benediction to all present. Every half hour a putto overturns a sandglass, and on the quarter hours another strikes a chime. Still more chimes are sounded by figures representing the four ages of mankind, followed by a skeletal Death, who rings the hours. And a mechanical cock crows on cue, flapping its metal wings.
All of this apparatus is housed in a structure of unembarrassed eclecticism, both stylistic and intellectual. The central tower of the clock is topped with a froth of German-baroque frosting, whereas a smaller turret on the left (which houses theweights that drive the clockwork) has been given a more Frenchified treatment. A third tower, on the right, includes a stone spiral staircase that might have been salvaged from an Italian Renaissance belvedere. In the base of the cabinet, two glass panels allowing a view of brass gear trains are a distinctively nineteenth-century element; they look like the windows of an apothecary shop. The paintings and statues are mainly on religious themes—death and resurrection, fall and salvation— but they also include portraits of Urania (Muse of astronomy) and Copernicus. Another painting portrays Jean BaptisteSosimé Schwilgué, whose part in this story I shall return to presently.
Programming with Brass
It's all done with gears. Also pinions, worms, snails, arbors; pawls and ratchets; cams and cam followers; cables, levers, bell cranks, and pivots.
The actual timekeeping mechanism—a pendulum and escapement much like those found in other clocks—drives the gear train for mean solar time. All the other astronomical and calendrical functions are derived from this basic, steady motion. For example, local solar time is calculated by applying two corrections to mean solar time. The first correction compensates for seasonal changes in day length, the second for variations in the earth's orbital velocity as it follows its slightly elliptical path around the sun. The corrections are computed by a pair of "profile wheels" whose rims are machined to trace out a graph of the appropriate mathematical function. A roller, following the profile as the wheel turns, adjusts the speedof the local-solar-time pointer accordingly. The computation of lunar motion requires five correction terms and five profile wheels. They all have names: anomaly, evection, variation, annual equation, reduction.
The overall accuracy of the clock can be no better than the adjustment of the pendulum, which requires continual intervention, but for the subsidiary timekeeping functions there is another kind of error to be considered as well. Even if the mean time is exact, will all the solar and lunar and planetary indicators keep pace correctly? The answer depends on how well celestial motions can be approximated by the arithmetic of rational numbers, as embodied in gear ratios. The Strasbourg clockcomes impressively close. For example, the true sidereal day is 23 hours, 56 minutes, 4.0905324 seconds, whereas the mean solar day is exactly 24 hours (by definition). The ratio of these intervals is 78,892,313 to 79,108,313, but grinding gears with nearly 80 million teeth is out of the question. The clock approximates the ratio as 1 + (450/611 ×1/269), which works out to a sidereal day of 23 hours, 56 minutes, 4.0905533 seconds. The error is less than a second percentury.
The most intricate calculations are those for leap years and the movable feasts of the church. The rule for leap years states that a year N has an extra day if N is divisible by 4, unless N is also divisible by 100, in which case the year is a common year, with only the usual 365 days; but if N is also divisible by 400, the year becomes a leap year again. Thus 1700, 1800, and 1900 were all common years (at least in those parts of the world that had adopted the Gregorian calendar), but 2000 had a February 29. How can you encode such a nest of if-then-else rules in a gear train? The clock has a wheel with twenty-four teeth and space for an omitted twenty-fifth. This wheel is driven at a rate of one turn per century, so that every four years a tooth comes into position to actuate the leap-year mechanism. The gap where the twenty-fifth tooth would be takes care of the divisible-by-100 exception. For the divisible-by-400 exception to the divisible-by-100 exception, a furtheradjustment is needed. The key is a second wheel that turns once every 400 years. It carries the missing twenty-fifth tooth and slides it into place on every fourth revolution of the century wheel, just in time to trigger the quadricentennial leapyear.
The display of leap years calls for as much ingenuity as their calculation. On the large calendar ring, an open space between December 31 and January 1 bears the legend "Commencement de l'année commune" ("Start of common year"). Shortly before midnight on each December 31 when a leap year is about to begin, a sliding flange that carries the firstsixty days of the year ratchets backward by the space of one day, covering up the word "commune" at one end of the flange and at the same time exposing February 29 at the other end. The flange remains in this position throughout the year,then shifts forward again to cover up the 29 and reveal "commune" just as the following year begins.
The rules for finding the date of Easter are even more intricate than the leap-year rule. Donald Knuth, in his Art of Computer Programming, remarks: "There are many indications that the sole important application of arithmetic in Europe during the Middle Ages was the calculation of Easter date." Knuth's version of a sixteenth-century algorithm for thiscalculation has eight major steps, some of which are fairly complex. Here's step five:
Set E(11G + 20 + Z – X) mod 30. If E = 25 and the golden number G is greater than 11, or if E = 24, then increase E by 1. (E is the so-called "epact," which specifies when a full moon occurs.)
Programming a modern computer to perform the Easter calculation requires some care; programming a box of brass gears to do the arithmetic is truly a tour de force. I have stared at diagrams of the gears and linkages and tried to trace out their action, but I still don't fully understand how it all fits together.
In the abstract, it's not too hard to see how a mechanical linkage could carry out the basic steps of the epact calculation given above. A wheel with 30 teeth or cogs would ratchet 11G notches clockwise, then it would add 20 steps more in the same direction, then another Z steps; finally it would turn X steps counterclockwise. The "mod 30" part of the program—reducing the sum modulo 30 (so that 30 becomes 0, 31 becomes 1, and so forth)—would be taken care of automatically by doing the arithmetic on a circle with 30 divisions. So far so good. The 30-tooth wheel does exist in the Strasbourg clock, and it is even helpfully labeled "Epacte." Where I get lost is in trying to understand the various lever arms and rack-and-pinion assemblies that drive the epact wheel, and the cam followers that communicate its state to the rest of the system. There appear to be a number of optimizations in the gear works, which doubtless save a little brass but make the operation more obscure. Perhaps if I had a model I could take apart and put together again . . .
But never mind my failures of spatiotemporal reasoning. The mechanism does work. Each New Year's Eve a metal tag that marks the date of Easter slides along the circumference of the calendar ring and takes up a position over the correct Sunday for the coming year. (The date of Easter can range from March 22 to April 25.) All the other movable feasts of the church are a fixed number of days before or after Easter, so the indicators of their dates are rigidly linked to the Easter tag and move along with it.
Making It Go
The present Strasbourg clock is the third in a series. The first was built in the middle of the fourteenth century, just as the cathedral itself was being completed with the addition of a spire that made it the tallest structure in Europe. That original clock had animated figures of the three Magi who bowed down before the Virgin and Child every hour on the hour. Little else is known of it, and all that survives is a mechanical rooster, ancestor of the current cock of the clock.
By the middle of the sixteenth century, the Clock of the Three Kings was no longer running and no longer at the leading edge of horological technology. To supervise an upgrade, the Strasbourgeois hired Conrad Dasypodius, the professor of mathematics at Strasbourg, as well as the clockmaker Isaac Habrecht and the artist Tobias Stimmer. These three laid out the basic plan of the instrument still seen today, including the three-turreted case and most of the paintings and sculptures. A curiosity surviving from this era is the portrait of Copernicus— a curiosity because the planetary display on the Dasypodius clock portrayed not the sun-centered Copernican system but the earth-centered Ptolemaic one. The second clock lasted another two hundred years, give or take.
The story of the third clock starts with an anecdote so charming that I can't bear to look too closely into its authenticity. Early in the nineteenth century, the story goes, a beadle was giving a tour of the cathedral, and mentioned that the clock had been stopped for twenty years and no one knew how to fix it. A small voice piped up: "I will make it go!" The boy who made this declaration was Jean Baptiste-Sosimé Schwilgué, who made good on his promise forty years later.
There was mild conflict over the terms of Schwilgué's commission. He wanted to build a wholly new clock; the cathedraladministration wanted to repair the old one. They compromised: he gutted the works, but kept the case, and built his new indicators and automata to fit the old design. The new mechanism was first started up on October 2, 1842.
Schwilgué was clearly thinking long-term when he undertook the project. As I have already noted, the leap-year mechanism includes components that engage only once every four hundred years—parts that were tested for the first time in 2000 andwill lie dormant again until 2400. Such very rare events might have been left for manual correction. It would have been only a small imposition on the clock's maintainers to ask that the hands be reset every four centuries. But Schwilguéevidently took pride and pleasure in getting the details right. He couldn't know if the clock would still be running in 2000 or2400, but he could build it in such a way that if it did survive, it would not perpetrate error.
The contrast with recent practice in computer hardware and software could hardly be more stark. Many computer systems—even those that survived the Y2K scare—are explicitly limited to dates between 1901 and 2099. The reason for choosing thisparticular span is that it makes the leap-year rule extremely simple: it's just a test of divisibility by four. Under the circumstances, this design choice seems pretty wimpy. If Schwilguécould take the trouble to fabricate wheels that make one revolution every one hundred and four hundred years, surely a programmer could write the extra line of code needed to check for the century exceptions. The line might never be needed, but there's the satisfaction of knowing it's there.
Other parts of Schwilgué's clock look even further into the future. There is a gear deep in the works of the ecclesiastical computer that turns once every 2,500 years. And the celestial sphere out in front of the clock has a still-slower motion. In addition to the sphere's daily rotation, it pirouettes slowly on another axis to reflect the precession of the equinoxes of the earth's orbit through the constellations of the zodiac. In the real solar system, this stately motion is what has lately brought us to the dawning of the age of Aquarius. In the clock, the once-per-sidereal-day spinning of the globe is geared down at a ratio of 9,451,512 to 1, so that the equinoxes will complete one full precessional cycle after the passage of 25,806 years. (The actual period is now thought to be 25,784 years.) At that point we'll be back to the cusp of Aquarius again, and no doubt paisley bell-bottoms will be back in fashion.
Easter in 11842 Falls on April 3
The odometer of years on the face of the Strasbourg clock, as mentioned above, runs up to 9999. According to some accounts,Schwilgué suggested that if the clock is still going when the counter rolls over to 0000, a numeral 1 could be paintedon the case to the left of the thousands digit. The simplicity of this solution suggests that the Y10K crisis may turn out to be even less disruptive than the Y2K one was. After all, appending a digit to the tally is easier than changing one.
Is there any chance the Strasbourg clock will actually run for ten thousand years? No products of human artifice have yet lasted so long, with the exception of cave paintings and some sharpened flints. Stonehenge and the pyramids of Egypt are half that age. The two earlier Strasbourg clocks, built with technology similar to that of the current instrument, both failedafter roughly two centuries. Complex machines with moving parts seldom seem to last more than a few hundred years, even with conscientious maintenance. Of course such machines were great rareties until a few hundred years ago, so the age distribution is highly skewed. One might equally well argue that electronic computers cannot work for more than fifty or sixty years, since all the functioning ones are younger than that. Still, the actuarial life expectancy of either the clock or the computer can surely be expressed in three digits or less.
In principle, a machine can last forever if you keep replacing parts as fast as they wear out. For this strategy to succeed, however, not only artifacts but also institutions must survive. Someone must be there to wind the clock and lube it and dust it, day after day. The perils to long-term continuity should be abundantly clear in a border town like Strasbourg, which has been batted back and forth between France and Germany like the child of a contested divorce. Bishops and burghers once fought for control of the city; the cathedral has passed through the hands of Catholics, Protestants, and revolutionary atheists. And yet the stones still stand, and so do the institutions. A single organization, the Oeuvre Notre-Dame, has maintained the cathedral since the thirteenth century.
Even if the clock keeps ticking, however, will anyone in 11842 want to know the date of Easter? For that matter, will people then still be counting the years of the Common Era? No system of timekeeping has endured anywhere near ten millennia. TheRoman calendar was abandoned after fifteen hundred years; the Mayan one may have lasted as long as two thousand years, the Egyptian possibly three thousand. According to the Hebrew calendar, the tally of years is now well past fifty-seven hundred, but that's not to say that anyone has been faithfully marking the days and months since 1 Tishri 1. Meanwhile, other calendars have come and gone. If Schwilgué had rebuilt the Strasbourg clock just a few decades earlier, it would have listed dates in Brumaire, Thermidor, Fructidor, and the other months decreed by the French Revolution, and the year would now be in the low 200s.
The Long Now
I want to address another question. Even if a clock can be kept in working order, and even if the calendar it keeps retainssome meaning, is the building of such multimillennial machines a good idea? I have my doubts, and they have been redoubled by a recent proposal to build another ten-thousand-year clock.
The new plan comes from Danny Hillis, the architect of the Connection Machine, an innovative and widely admired supercomputer of the 1980s. Another of Hillis's projects was a computer made entirely of Tinkertoys, which has a distant familial connection with Schwilgué's ecclesiastical computer. Together with several friends and colleagues, Hillis has proposed building a clock described as "the world's slowest computer," whose function is just to keep going as long as possible. The project is outlined in The Clock of the Long Now, a book by Stewart Brand, the instigator of The Whole Earth Catalog.
Technical details of the Long Now clock remain to be worked out, but the provisional design that Brand describes has a torsion pendulum (one that twists rather than swings) and a digital counter of pendulum oscillations instead of an analog gear train. Although the counter is digital, it is emphatically not electronic; Hillis's design uses mechanical wheels and pegs to count in binary notation from zero up to some predefined constant, such as the number of seconds in a year.
The plan is to build several clocks, of increasing grandeur. A prototype will be eight feet high. A twenty-foot model will be placed in a large city for ease of access, and then a sixty-footer will be installed somewhere out in the desert for safekeeping. Here is one of Hillis's visions of how the full-size clock might be experienced:
Imagine the clock is a series of rooms. In the first chamber is a large, slow pendulum. This is your heart beating, but slower. In the next chamber is a simple twenty-four-hour clock that goes around once a day. In the next chamber, just a Moon globe, showing the phase of the lunar month. In the next chamber is an armillary sphere tracking the equinoxes, the solstices, and the inclination of the Sun . . . The next chamber is the Lifetime room—a single blank, featureless disk of soft stone that rotates once a lifetime, onto which you can carve your own mark.
The final chamber is much larger than the rest. This is the calendar room. It contains a ring that rotates once a century and the 10,000-year segment of a much larger ring that rotates once every precession of the equinoxes. These two rings intersect to show the current calendrical date.
The motive for building this monument to slow motion is not timekeeping per se; Hillis is not worried about losing count ofthe centuries. The aim is psychological. The clock is meant to encourage long-term thinking, to remind people of the needs and claims of future generations. The preamble to the project summary begins: "Civilization is revving itself into a pathologically short attention span. The trend might be coming from the acceleration of technology, the short-horizon perspective of market-driven economics, the next-election perspective of democracies, or the distractions of personal multitasking." The big slow clock would offer a counterpoise to these frenetic tendencies; it would "embody deep time."
The wisdom of planning ahead, husbanding resources, saving something for those who will come after, leaving the world a better place—it's hard to quibble with all that. Concern for the welfare of one's children and grandchildren is surely avirtue—or at least a Darwinian imperative—and more-general benevolence toward future inhabitants of the planet is also widely esteemed. But if looking ahead two or three generations is good, does that mean looking ahead twenty or thirty generations is better? What about two hundred or three hundred generations? Perhaps the answer depends on how far ahead you can actually see.
The Long Now group urges us to act in the best interests of posterity, but beyond a century or two I have no idea what those interests might be. To assume that the values of our own age embody eternal verities and virtues is foolish and arrogant.For all I know, some future generation will thank us for burning up all that noxious petroleum and curse us for exterminating the smallpox virus.
From a reading of Brand's book, I don't sense that the Long Now organizers can see any further ahead than the rest of us; as a matter of fact, they seem to be living in quite a short Now. All those afflictions listed in their preamble—the focus on quarterly earnings and quadrennial elections and so forth—are bugaboos of recent years and decades. They would have been incomprehensible a few centuries ago, and there's not much reason to suppose they will make anybody's list of pressing concerns a few centuries hence, much less in ten thousand years.
The emphasis on the superiority of binary digital computing is something else that puts a late-twentieth-century date stamp on the project. A time may come when Hillis's binary counters will look just as quaint as Schwilgué's brass gears.
Long-term thinking is really hard. Of course that's the point of the Long Now project, but it's also a point of weakness. It's hard to keep in mind that what seems most steadfast over the human life span may be evanescent on a geological or astronomical timescale. Consider the plan to put one clock in a city (New York, say) and another in a desert (Nevada). This makes sense now, but will New York remain urban and Nevada unpopulated over the next ten thousand years? Many a desolate spot in the desert was once a city, and vice versa. (On the other hand, maybe Nevada isn't such a bad choice. They could build the clock in Yucca Mountain, the proposed repository of one product of civilization we can count on lasting ten thousand years: the radioactive wastes from nuclear power generation.)
Needless to say, the difficulty of predicting the future is no warrant to ignore it. The Y2K scare offered clear evidence that a time horizon of two digits is too short. But four digits is plenty. If we take up the habit of building machines meant to last past 10000, or if we write our computer programs with room for five-digit years, we are not doing the future a favor. We're merely nourishing our own delusions.
Chronocolonialism
In the sixteenth century, Dasypodius and his colleagues could have chosen to restore the two-hundred-year-old Clock of the Three Kings in Strasbourg Cathedral, but instead they ripped out all traces of it and built a new and better clock. A bit more than two hundred years later, Schwilgué was asked to repair the Dasypodius clock, but instead he eviscerated it and installed his own mechanism in the hollowed-out carcass. He built a new and better clock, good for ten thousand years. Today, after another two centuries, the Long Now group is not threatening to destroy the Schwilgué clock, but neither are they working to ensure its longevity. They ignore it. They want to build a newer, better, different clock, good for ten thousand years.
I begin to detect a pattern. The fact is, winding and dusting and fixing somebody else's old clock is boring. Building a brand-new clock of your own is much more fun, especially if you can pretend that it's going to inspire awe and wonder for ages to come. So why not have the fun now and let the next three hundred generations do the boring bit?
If I thought that Hillis and his associates might possibly succeed in this act of chronocolonialismmdash;enslaving future generations to maintain our legacy systems—I would consider it my own duty to posterity to oppose the project, even to sabotage it. But in fact I don't worry. I have faith in the future. Sometime in the 2200s a small child touring the ruins of the Clock of the Long Now will proclaim, "I will make it go!" And that child will surely scrap the whole mess and build a new and better clock, good for ten thousand years.
AFTERTHOUGHTS
Of all the essays collected in this volume, this meditation on the theme of things-built-to-last turned out to be the most perishable. It was written for a particular occasion—the end of the second millennium of the Common Era—and was published in the November–December 1999 issue of The Sciences. When I began to prepare the essay for re-publication here, I found that much of the discussion was closely tied to the preoccupations of that single moment, especially the impending "Y2K crisis." Obviously, I wasn't thinking long-term when I wrote the piece.
I have done some light editing to liberate the essay from its captivity in 1999, without trying to rewrite it entirely fromthe perspective of 2007. (This moment, too, shall pass, after all.) I have also taken the opportunity to restore a few passages that had to be omitted from the original magazine version for lack of space. Finally, I have corrected an embarrassingerror.
Here's the story of the error. I had believed that Schwilgué's simple ploy of painting a 1 next to the year counter would not fully adapt the clock to the post-10000 era, because the Easter calculation would be incorrect. The algorithm for calculating the date of Easter takes the year number as its input and produces a month and a date as its output. I had written a little computer program based on this algorithm, which seemed to indicate that the clock's calculation would go awry after 9999. For example, the date of Easter in 11999 (if anyone is paying attention then) will be April 11; if the ecclesiastical computer inside the clock were to see only the final four digits of this number, it would calculate the date of Easter for 1999, which was April 4. Thus the clock would forever repeat a ten-thousand-year cycle of Easter dates.
The flaw in my reasoning was to assume that the gear train inside the clock worked the same way as my program. In actuality, the ecclesiastical computer is oblivious to the numerical value of the year; it performs its calculation progressively, year by year, in effect simulating all the motions of the sun and the moon that ultimately determine the Easter date. The year number never enters into the calculation; the church calendar would continue to be updated correctly even if the counter of years were to stop.
What's embarrassing about this error is that my faulty understanding was pointed out even before publication, by Peter Brown, who was then the editor of The Sciences; but I was sure I was right. It was a letter to the editor from Bob Conley of Anchorage, Alaska, that finally convinced me.
There is another small error; I have allowed it to stand in the text, but I should acknowledge it here. When I wrote that cave paintings and stone tools are the only man-made artifacts to have survived ten thousand years or more, I was forgettingabout pottery. The jomon pottery of Japan is thought to go back at least eleven thousand years and perhaps substantially longer.
What has become of the Clock of the Long Now? A first prototype was completed just in time to bong twice at midnight on December 31, 2000. That clock is now on display at the Science Museum in London. A second prototype is under construction in California, and the Long Now Foundation has purchased a site in eastern Nevada—not too far from Yucca Mountain!—for the big stone clock. For more information and progress reports, see www.longnow.org.
The debate over global warming, which has heated up considerably since this essay first appeared, prompts a further commenton the need for long-term thinking, and on the difficulty of seeing into the distant future. The idea that actions we take now—or fail to take—might alter the earth's climate for thousands of years to come argues that we cannot shirk responsibility for the fate of the planet. Whether or not we bother to give any thought to the future, we will determine its shape.
But the prospect of a major shift in climate is also a reminder that the future is a different world—different from the one we inhabit now, and also probably different from any that we can imagine. The current fear is that Florida will become a shallow sea, and the Corn Belt will be growing nothing but cactus. It could happen. But so could the opposite: the glaciers might descend again and scrape the continent clean as far south as St. Louis. For optimists, there's also the possibility that by the year 12000 people may have acquired the means and the wisdom to control the planet's wilder divagations.
When I was younger, the peril to human survival that seemed most worrisome was a nuclear shoot-out that could leave the earth uninhabitable. That threat has not disappeared, although it has retreated from public consciousness. There have also been periods when overpopulation, pollution, and the exhaustion of resources appeared to be the principal agents of doom. Now the focus is on climate. In reciting this history of shifting hazards, I don't mean to belittle any of them; they are all to be taken seriously. I simply want to point out that when we make an earnest effort to think about "the long run,"our vision of the distant future always seems to reflect mainly the concerns of the present moment.
Trying to make life a little better for the great-great-. . . great-grandkids is a worthy goal; conversely, policies that cater solely to our own comfort and convenience, ignoring the welfare of future generations, are reprehensible. If building the Clock of the Long Now will help to remind people that life goes on—or that we hope it goes on—then there's surely no harm in it. But keep in mind that it's an exercise for the benefit of those who build it, not for those to whom we supposedly bequeath it.
Excerpted from Group Theory in the Bedroom and Other Mathematical Diversions by Brian Hayes.
Copyright © 2008 by Brian Hayes.
Published in 2008 by Hill and Wang a division of Farrar, Straus and Giroux, LLC.
All rights reserved. This work is protected under copyright laws and reproduction is strictly prohibited. Permission to reproduce the material in any manner or medium must be secured from the Publisher.