The full scale 10,000 Year Clock is now under construction. While there is no completion date scheduled, we do plan to open it to the public once it is ready. The essay below by Long Now board member Kevin Kelly discusses what we hope the Clock will be once complete. This is one of several projects by Long Now to foster long-term thinking in the context of the next 10,000 years.

Clock in the Mountain by Kevin Kelly

There is a Clock ringing deep inside a mountain. It is a huge Clock, hundreds of feet tall, designed to tick for 10,000 years. Every once in a while the bells of this buried Clock play a melody. Each time the chimes ring, it’s a melody the Clock has never played before. The Clock’s chimes have been programmed to not repeat themselves for 10,000 years. Most times the Clock rings when a visitor has wound it, but the Clock hoards energy from a different source and occasionally it will ring itself when no one is around to hear it. It’s anyone’s guess how many beautiful songs will never be heard over the Clock’s 10 millennial lifespan.

The Clock is real. It is now being built inside a mountain in western Texas. This Clock is the first of many millennial Clocks the designers hope will be built around the world and throughout time. There is a second site for another Clock already purchased at the top of a mountain in eastern Nevada, a site surrounded by a very large grove of 5,000-year-old bristlecone pines. Appropriately, bristlecone pines are among the longest-lived organisms on the planet. The designers of the Clock in Texas expect its chimes will keep ringing twice as long as the oldest 5 millennia-old bristlecone pine. Ten thousand years is about the age of civilization, so a 10K-year Clock would measure out a future of civilization equal to its past. That assumes we are in the middle of whatever journey we are on – an implicit statement of optimism.

The Clock is now being machined and assembled in California and Seattle. Meantime the mountain in Texas is being readied. Why would anyone build a Clock inside a mountain with the hope that it will ring for 10,000 years? Part of the answer: just so people will ask this question, and having asked it, prompt themselves to conjure with notions of generations and millennia. If you have a Clock ticking for 10,000 years what kinds of generational-scale questions and projects will it suggest? If a Clock can keep going for ten millennia, shouldn’t we make sure our civilization does as well? If the Clock keeps going after we are personally long dead, why not attempt other projects that require future generations to finish? The larger question is, as virologist Jonas Salk once asked, “Are we being good ancestors?”

The Clock’s inventor introduced the idea of the Clock (in 01995) with this context:

I cannot imagine the future, but I care about it. I know I am a part of a story that starts long before I can remember and continues long beyond when anyone will remember me. I sense that I am alive at a time of important change, and I feel a responsibility to make sure that the change comes out well. I plant my acorns knowing that I will never live to harvest the oaks. I want to build a clock that ticks once a year. The century hand advances once every 100 years, and the cuckoo comes out on the millennium. I want the cuckoo to come out every millennium for the next 10,000 years.

That’s Danny Hillis, a polymath inventor, computer engineer, and designer, inventor and prime genius of the Clock. He and Stewart Brand, a cultural pioneer and trained biologist, launched a non-profit foundation to build at least the first Clock. Fellow traveler and rock musician Brian Eno named the organization The Long Now Foundation to indicate the expanded sense of time the Clock provokes – not the short now of next quarter, next week, or the next five minutes, but the “long now” of centuries. Eno also composed the never-repeating melody generator that rings the Clock’s chimes inside the mountain. Other people unhappy with our society’s short-attention span are part of this group, including me, one of its charter officers. This Clock in the Mountain is being funded and built on property owned by Jeff Bezos, the founder and CEO of Amazon.com. Bezos is also active in designing the full experience of the Clock.

The first step in this multi-decade project was to construct a working 8-foot-tall prototype. This test version was finished (just in time) on New Year’s Eve 1999. At the stroke of midnight, the prototype 10,000-year Clock bonged twice to usher in the new millennia, the year 2000, in front of a small crowd at its temporary home in the Presidio, San Francisco. The Clock now resides in the London Science Museum. Somewhat worrisome, there have been moments when it was not wound.

In contrast to the human-scale of the prototype, the Clock in the mountain will be monumental, almost architectural in scale. It will be roughly 200 feet tall. Located under a remote limestone mountain near Van Horn, Texas, it will require a day’s hike to reach its interior gears. Just reaching the entrance tunnel situated 1500 feet above the high scrub desert will leave some visitors out of breath, nicked by thorns, and wondering what they got themselves into.

To see the Clock you need to start at dawn, like any pilgrimage. Once you arrive at its hidden entrance in an opening in the rock face, you will find a stainless steel door, and then a second door beyond it. These act as a kind of crude airlock, keeping out dust and wild animals. You rotate its round handles to let yourself in, and then seal the doors behind you. It is totally black. You head into the darkness of a tunnel a few hundred feet long. At the end there’s the mildest hint of light on the floor. You look up. There is a tiny dot of light far away, at the top of top of a 500 foot long vertical tunnel about 12 feet in diameter. There is stuff hanging in the shaft.

The dot of light beckons you. You begin the ascent. You start climbing a continuous spiral staircase, winding up the outer rim of the tunnel, rising toward the very faint light overhead. The stairs are carved out of the rock. The material above each step has been removed from the tunnel leaving astoundingly precise rock stairs. To cut the spiral staircase Stuart Kendall of Seattle Solstice invented a special stone slicing robot to continuously grind out the stairs at the rate of a few stairs per day. His robot incrementally creeps downward while the debris falls into the central shaft out of the way.

Round the tunnel and up the tube toward the light you head. The first part of the Clock you encounter on the ascent up the spiral staircase is the counterweights of the Clock’s drive system. This is a huge stack of stone disks, about the size of a small car, and weighing 10,000 pounds. Depending on when the clock was last wound, you may have to climb 75 feet before you reach the weights.

After you pass the weights, you arrive at the winding station. It is a horizontal windlass, or a capstan like the turnstile on an old sailing vessel that winds up an anchor. It takes two or three visitors to push around the capstan of the clock and to lift its 10,000-pound stones. You rotate around until you can no further. Now the clock is wound.

You keep climbing. For the next 70-80 feet of ascent you pass 20 huge horizontal gears (called Geneva wheels), 8 feet in diameter, each weighing 1,000 pounds. This is the mechanical computer that calculates the over 3.5 million different melodies that the chimes will ring inside the mountain over the centuries. The chimes never repeat so that every visitor’s experience is unique, and the calculated variety creates a sense of progressive time, rather than endless recycling. And “calculate” is the correct word, because cut into the gears is an elaborate system of slots and sliding pins, which, much like a Babbage Difference Engine, will perform digital calculations, generating the next sequence of the ten bells. Only the Clock calculates without electricity, using your stored energy to moving its physical logic gates and bits. This is the world’s slowest computer.

On days when visitors are there to wind it, the calculated melody is transmitted to the chimes, and if you are there at noon, the bells start ringing their unique one-time-only tune. The 10 chimes are optimized for the acoustics of the shaft space, and they are big.

Finally, way out of breath, you arrive at the primary chamber. Here is the face of the Clock. A disk about 8 feet in diameter artfully displays the natural cycles of astronomical time, the pace of the stars and the planets, and the galactic time of the Earth’s procession. If you peer deep into the Clock’s workings you can also see the time of day.

But in order to get the correct time, you need to “ask” the clock. When you first come upon the dials the time it displays is an older time given to the last person to visit. If no one has visited in a while, say, since 8 months and 3 days ago, it will show the time it was then. To save energy, the Clock will not move its dials unless they are turned, that is, powered, by a visitor. The Clock calculates the correct time, but will only display the correct time if you wind up its display wheel. So yet another hand-turned wheel awaits your effort to update the face of time. This one is much easier to wind because the dial motion consumes less power than ringing bells. You start winding and the calendar wheels whirr until BING, it stops and it shows the current date and time.

So how does the Clock keep going if no one visits it for months, or years, or perhaps decades? If it is let to run down between visits, who would keep resetting it? The Clock is designed to run for 10,000 years even if no one ever visits (although it would not display the correct time till someone visited). If there is no attention for long periods of time the Clock uses the energy captured by changes in the temperature between day and night on the mountain top above to power its time-keeping apparatus. In a place like a top of a mountain, this diurnal difference of tens of degrees in temperature is significant and thus powerful. Thermal power has been used for small mantel clocks before, but it has not been done before at this scale. The differential power is transmitted to the interior of the Clock by long metal rods. As long as the sun shines and night comes, the Clock can keep time itself, without human help. But it can’t ring its chimes for long by itself, or show the time it knows, so it needs human visitors.

If the sun shines through the clouds more often than expected, and if the nights are colder than usual, the extra power generated by this difference (beyond what is ordinarily needed to nudge the pendulum) will bleed over into the Clock weights. That means that over time, in ideal conditions, the sun will actually wind up the chimes, and wind them up sufficiently for them to ring when no one is there.

The rotating dials, gears, spinning governor, and internal slips of pins and slots within the Clock will be visible only if you bring your own light. The meager dot of light above is not sufficient to see much otherwise. Lights off, the Clock sits in near total darkness, talking to itself in slow clicks, for perhaps years at a time. In the darkness you can hear things moving, crisp non-random pings, like a crude thought trying to form inside a dim unlit brain.

Shining your light around the rest of the chamber you’ll see the pendulum and escapement encased in a shield of quartz glass – to keep out dust, air movements, and critters. The pendulum, which governs the timing of the Clock, is a 6-feet-long titanium assembly terminating with football-sized titanium weights. It swings at a satisfyingly slow 10-second period. The slight clicks of its escapement echo loudly in the silence of the mountain.

Building something to last 10,000 years requires both a large dose of optimism and a lot of knowledge. There’s a huge geek-out factor in the Clock because the engineering challenges are formidable. What do you build with that won’t corrode in 100 centuries? How do you keep it accurate when no one is around? The Clock’s technical solutions are often ingenious.

Almost any kind of artifact can last 10 millennia if stored and cared for properly. We have examples of 5,000-year-old wood staffs, papyrus, or leather sandals. On the other hand, even metal can corrode in a few years of rain. For longevity a 10K year environment is more important than the artifact’s material. The mountain top in Texas (and Nevada) is a high dry desert, and below, in the interior tunnel, the temperature is very even over seasons and by the day (55 degrees F) – another huge plus for longevity since freeze-thaw cycles are as corrosive as water. Dry, dark and stable temperatures are what archivists love. It’s an ideal world for a ceaseless Clock.

Still, the Clock is a machine with moving parts, and parts wear down and lubricants evaporate or corrode. Most of the Clock will be made in a marine grade 316 stainless steel. Because the engineering tolerances of the huge Clock are in fractions of an inch, rather than thousandths, the microscopic expansion by a film of rust won’t hurt the time keeping. The main worry of the Clockmakers is that elements of a 10K-year Clock — by definition — will move slowly. The millennial dial creeps so slowly it can be said to not move at all during your lifetime. Metals in contact with each other over those time scales can fuse – defeating the whole purpose of an ongoing timepiece. Dissimilar metals in contact can eat each other in galvanic corrosion. To counteract these tendencies some of the key moving parts of the Clock are non-metal — they are stone and hi-tech ceramics.

Ceramics will outlast most metals. We have found shards of clay pots 17,000 years old. And modern ceramics can be as hard as diamonds. All the bearings in the Clock will be engineered ceramic. Because these bearings are so hard, and rotate at very low speed, they require no lubrication – which normally attracts grit and eventually cause wear.

There is more than just technology in the mountain. The ticks of time are a very human invention. Astronomical calendars are among the first pieces of culture, and often the mark of civilizations. The cave holds culture. The Clock in the mountain not only plays the music of an ever-changing slow melody, but it will collect cultural expressions of time, ticks to mark the passage of decades and centuries. Off to the side of the main cavern of the Clock are a series of small grottos to explore and collect these notices of time. Their contents will be a surprise.

Behind the main chamber’s dials the stairs continue up to the outside summit of the mountain. The shaft above Clock continues to the surface, where its opening to the daylight is capped with a cupola of sapphire glass. This is the only part of the clock visible from outside, on the mountain peak. In this outdoor cupola sits the thermal-difference device to power the timekeeping, and also a solar synchronizer. Every sunny noon, a prism directs sunlight down the shaft and slightly heats up this ingenious mechanical device. That synchronizing signal is transmitted by rods further down to the Clock’s innards, where the imperceptible variations in the length of the day as the earth wobbles on its axis will be compensated so that the Clock can keep its noon on true solar noon. In that way the Clock is self-adjusting, and keeps good time over the centuries.

The journey to the Clock in the mountain ends on the summit in light. It is the sun that powers its ringing below. Like a heart beating while we sleep, the Clock in the mountain keeps time even when we pretend the past did not happen and the future will not come.

The biggest problem for the beating Clock will be the effects of its human visitors. Over the span of centuries, valuable stuff of any type tends to be stolen, kids climb everywhere, and hackers naturally try to see how things work or break. But it is humans that keep the Clock’s bells wound up, and humans who ask it the time. The Clock needs us. It will be an out of the way, long journey to get inside the Clock ringing inside a mountain. But as long as the Clock ticks, it keeps asking us, in whispers of buried bells, “Are we being good ancestors?”

How do you become one of those time-conscious beings who visit and wind the Clock? Long Now Members will have priority to visit the Clock when it is completed and should check the Visit the Clock box in the Notifications tab in your Member Settings when you are signed in as a member on the Long Now website.

Jeff Bezos’ team at Amazon have also created a new website at 10000YearClock.net with information for the public about the project as well as a public sign up page for learning about the eventual visiting opportunities there.