Danny Hillis answers frequently asked questions about the 10,000-year clock

There is a huge clock inside a mountain that will tick for 10,000 years. It’s real. As one example of long-term thinking, the face of this clock has been adopted by The Long Now Foundation in its logo. This very real clock deliberately stirs up many questions. Danny Hillis, originator of the 10,000-year clock, and co-founder of The Long Now Foundation, answers some frequently asked questions about this ten millennial clock.

What’s a 10,000-year clock?

A 10,000-year clock is primarily a work of imagination to encourage people to think on a longer time scale. When I first imagined building a clock that would run for 10,000 years I had the naive idea that I would just build it as a personal project. Of course, it was too big a project for that and Stewart Brand pointed out that it really needed some kind of organization to help bring it into existence. That was the origin of The Long Now Foundation.  

The first clock was funded by Jacqui Safra, who loaned it to the London Science Museum, where it is still on display. The second prototype was the Orrery, a prototype of the clock’s annual anniversary display. That project was funded by Nathan Myhrvold. Nathan funded the construction of two identical Orreries and donated one of them back to the Foundation, which is now on display at The Interval. Jeff Bezos funded the third and largest project, which is a full-scale 10,000-year clock built inside a mountain, and he provided the perfect mountain for it in west Texas.

How would you describe this full-scale clock? What is it?

It is built underground in a remote mountain and it is designed to keep accurate time for 10,000 years. It is powered by the temperature change from day to night, synchronized to the correct time by a beam of sunlight that shines deep into the mountain. It is entirely mechanical, with a mechanism hundreds of feet tall. A visit to the clock is intended to be a transformational experience that stretches your sense of time.

When will this clock be completed?

I expect it to be fully operational in the next few years, but I don’t know that it will ever really be “completed.” It was designed to be continually improved upon, so in that sense it may never be finished. As monuments age and times change, and the sensibilities of the caretakers change. People tend to keep modifying them. The Sphinx in Egypt had new things added to it for thousands of years after it was initially “completed.” The clock is designed to expect that kind of continuous upgrade.

Who built this clock?

The clock was built by a diverse talented team from all over the world. Some designed and built unusual mechanisms out of long-lasting materials like titanium and sapphire, while others built the test equipment that ran those through 10,000 years of cycles to make sure they would last. Some adapted traditional methods, like bell casting, to unique designs like the harmonically tuned bells. Others stretched the state of the art in manufacturing precision optics to create the giant quartz prisms and lenses. Tasks like connecting multi-ton mechanisms while hanging in a 500-foot shaft required people with both ingenuity and some pretty specialized skills. Even seemingly mundane things like blasting tunnels and mixing cement take on new dimensions when they need to last 10,000 years. When we finally roll the credits on all the people who built this clock, the list is going to be many hundreds long. Many of them dedicated years or even decades of their lives to the project.

What was Long Now’s role?

Long Now provides the context in which building such improbable, mythical artifacts is possible. The Foundation provided the stewardship of the overall program of clock building that brought this peculiar clock into reality. Projects like this need to earn a certain degree of credibility before anyone will even consider funding them. Without long-term support, ideas, enthusiasm, imagination, and commitment of The Long Now Foundation and its supporters, a monument like this could never become a reality.

So, do my Long Now membership donations go to building and maintaining these clocks?

No, Long Now has never used its own funds to construct the clocks, nor have we taken on the responsibility of owning and maintaining them, except for what we display at the Interval. You might expect we would want to take responsibility for their long-term maintenance and display, but caretaking requires a different kind of organization with significantly different skills. In the case of the Texas clock, it will also require more resources than we can afford. Long Now is funded by membership and donations, which go to supporting the Foundation's staff and operations, including running the Talks series, publishing Ideas, and sharing the work of other long-term thinkers. Contributions also fund exhibits and events at The Interval, development of our Nevada property adjacent to the Great Basin National Park, and other projects that stimulate a long-term imagination, like the Rosetta Project and Long Bets.

Given all of the world’s pressing problems, why build 10,000-year clocks?

Humanity has lots of artifacts that help us extend our imagination to the past. The great pyramids are an example. You see a picture of a pyramid in the desert, and you naturally think about the people who built it. It conjures up a memory of the long human history that shaped our own culture. But we really don't have any such symbols for the future. What do we have that connects us to a thousand years ahead of us? Maybe science fiction, which helps us imagine specific hypothetical futures. The clock is more open-ended. It helps us imagine a future unconstrained by specific predictions. It gives us room to imagine. The 10,000-year time frame reminds us that our future is very big and so it’s worth striving to make it better.

I know this is a controversial idea these days, but I believe that over the long view of history people really are getting better. I know that it's hard to see that with all the big problems we still have to solve, and those we have created along the way. Yet, I believe it is clearly true. On a millennial timescale, we humans have been repeatedly expanding our circle of empathy. I believe that is what Martin Luther King was talking about when he said, “the arc of the moral universe is long, but it bends toward justice.” The longer your point of view, the easier it is to see that bend. When you imagine a 10,000-year future, it is also easier to see how you can help that bend toward justice. You have more leverage with a longer view.

How much did this clock cost?

A lot more than I originally guessed! And the construction of the underground space in the mountain that houses the clock was even more expensive than the clock itself. For instance, we had to invent a robot to cut a spiral staircase into the solid rock --- definitely not in the original budget.  Since the project is not complete and we don’t yet have a model for how it will be visited, we don’t know the final cost yet.

Wasn’t the clock supposed to have been built on a mountain top in Nevada?

Originally, the idea was to build a practice clock in Texas, which would serve as a prototype for a 10,000-year clock in Nevada. As we got into the project, we came to appreciate the complexities of underground construction in a remote mountain, and understood the quality of materials that would be needed to make even a practice clock. So in getting this prototype working as a long-lasting clock, it became a real 10,000-year clock. I still expect the Long Now Foundation will eventually put something at the Nevada site, but it will be something else.

When can people visit the Clock?

We have an understanding that the Clock will have ways of being visited in the future, especially for visitors associated with Long Now, but we do not have the details of how that will work yet. The clock is located in some of the roughest desert wilderness in North America, inhabited by rattlesnakes and mountain lions. Even the needle-sharp plants seem out to get you. I have seen weather shift from a baking heat to a dust storm, to lightning, to freezing sleet in a matter of hours. The clock is deep underground inside of a mountain that is far from roads, and it’s a tough climb to reach it. So, visits won’t be easy. Finding the right way to make sure people understand how difficult the hike is and how to facilitate all of the logistics will be a real challenge that has not yet been figured out.

What would a visit to this clock be like?

Well, let’s assume you have made arrangements for a visit and made your way to West Texas. You would want to reach the clock with enough time to wind it up to hear the chimes ring at noon, so you'd have to wake up super early in the morning. Presumably you would need some kind of a guide or docent that would lead you there, because it is a pretty tough and confusing climb. At the start of the trail, you can see the site of the clock with a pair of binoculars from a far distance, but as you get closer the route is designed so that it disappears from view. You would wonder constantly if you are lost and about to come to a dead end. You will need to squeeze through a narrow slot with sheer walls and then you have to climb up a cliff, using hanging chain ladders. When you finally arrive at the base of the mountain, you are confronted with this unclimbable 500-foot cliff. There is a tiny entrance at the bottom of it that looks like an old mine entrance. Just inside there is a crank you can turn to give you a little bit of light. It illuminates a ladder that goes down into a natural cave. By now, you’re probably wondering if you're in the right place. You wander through the natural cave formations until you find a tiny hole in the back of the cave that you can slip through. It takes you into a carved tunnel that leads you to the first thing that really feels like you're getting to the clock: a big metal door that hinges upward. The door opens an airlock to the clock. Once you go inside, there's another door behind it and you'll discover that you can't open the next door until you drop and let it close. So, there's a moment of truth. You have to close the first door to open the second. That marks the transition. You are having to leave behind the ordinary world and enter into a different one. One that will stretch your sense of time.

Why make it so hard to visit?

I always wanted this clock to be far away in the middle of nowhere because remoteness makes it more likely to survive. Things mostly survive for a long time on the margins. It is not intended to be a high-traffic tourist attraction; rather it is more like a pilgrimage for the very determined seeker. It is in the nature of a pilgrimage that not everybody who dreams about it actually does it, and not everyone who starts a pilgrimage completes it. The experience of visiting the clock is designed to unfold from the long journey to reach the entrance, through the final exit from darkness into the sunlight.

Are there going to be ways to visit this clock virtually?

Maybe. Lots of people have suggested ideas for that, but we've not committed to doing anything specific. That will evolve over time.

Is visiting this clock in person all that important?

My hope is that a 10,000-year clock will serve as a symbol of the future, in the same way the picture of the whole Earth floating in space serves as a symbol of our shared home. The clock symbol represents our connection to unborn generations that will inherit whatever we leave to them. Much of what a millennial clock accomplishes can be gained by just hearing its story. In fact, a lot of people who hear about the clocks think it is just a story. They are surprised to find out there are actual clocks. The reality of an actual giant clock ticking away inside a mountain for 10,000 years adds weight and power to that story.

Even though the primary value of this clock is in the story, I wanted to provide something special to anyone who does make the journey to visit it. It is purposely difficult to photograph. You can’t put it onto a postcard like the Taj Mahal. You will need to complete the long pilgrimage into the desert to get the full experience. You will need to pass through the dark tunnels and ascend a spiral staircase toward the light where you will wind the clock and hear the chimes. When you arrive at the clock chamber you see the date and time left by the last visitor, and when you wind the clock, you advance it to the current time so the next visitor will know when you were there. I am hoping that will help pilgrims feel the continuity, that great continuity, with our deep past and our long future. You can take a rubbing of the display showing the date you visited, and your visit will become part of the story. And your visit will benefit the clock.

Does it need visitors?

This clock doesn’t strictly need visitors, but it welcomes them and responds to them. The timekeeping is powered from the temperature change at the top of the mountain between day and night. Even if a big asteroid hits the earth or a volcano’s eruption interferes with the temperature change for a few decades, the clock stores enough energy to wait it out. Even if nobody visits, it will still have enough energy to keep itself wound.

The sustained energy that keeps the clock ticking is not enough to actually display the time. It takes a lot more energy to advance the calendar and move the big display to show the time, and even more energy to ring the chimes. Those displays are all for the human visitors, and the clock depends on those humans to supply the energy for that.

When a pilgrim visits the clock, what they see is the time that the last visitor was there, and they must wind up the clock to update the display of the correct time. They will get to see the position of the sun and moon and sky advance from the date of the last visit until it catches up to the present.

A pilgrim can also give the clock more energy by winding up the chimes. The bells ring in different order each time they are played, so this melody has never been heard before and will never be heard again. When the chimes have been fully wound, they will ring at noon. For the most part, the chimes inside the mountain will only ring if they have been wound and updated by visitors but, if no one visits the clock for a long time, the daily trickle of night-to-day energy can accumulate enough surplus sufficient to trigger the chimes. When that happens, the clock burns off the extra energy by ringing the chimes just for the fun of it. Sadly, no one will be around to hear that melody, and it will never repeat again.

How does this clock keep accurate time when nobody's there?

The clock calibrates itself from the sun. Around the summer solstice, the sun’s light shines down the shaft into the chamber. The sunbeam heats up a trigger that synchronizes the clock to the actual solar time.

Will there be a ceremony for the moment it starts running?

Maybe. To a 10,000-year clock, a moment is several years. There will be several years of fine tuning.

What kind of maintenance will be required to keep it working for 10,000 years, after its creators are long gone?

We spent a lot of effort designing it to not require much maintenance. For example, you don't have to worry about lubricating it incorrectly, because it doesn't have any lubrication. Some parts may eventually break or need cleaning, but there is no scheduled maintenance. Of course, there will be problems we have not anticipated, but the clock is designed to be self-documenting and functionally transparent, so that you can look at something, see how it works and fix it. There are architectural parts that people interact with when they visit, like the lighting system, that will require some maintenance. Those are parts that wear out with human use, so we can depend on people being around to maintain them. And they really don’t even have to work. The lighting system is minimal because once you get into the main shaft of the clock, it's naturally lit. The natural light coming from the top is almost like moonlight. The main chore for the caretaker will be to protect the clock from being deliberately vandalized..

This clock is almost ready to start running and stories about it have been told for a decade. What difference to the people of the present has the clock made so far?

I often run into people who start out by saying, “You know, I never really considered 10,000 years as a serious timeframe to even think about before. It just seemed too remote. But the clock has made me think seriously about 10,000 years of human future.” People think,“If this clock will still be ticking then, what else might also happen over that time?” It gives them permission to take the long term seriously. It already gets people thinking about next generations differently because it tickles their imagination. Mentions of it have already started to appear in children’s books. And we’ve seen that bigger story can cause people to think about their responsibility to that future. So, in that sense, it’s already starting to work. People are also starting to design their own variations of 10,000-year clocks, clocks that reflect their own ideas of what a long-term clock should be. I would like to live in a world with lots of 10,000-year clocks.

What’s next?

From the beginning of The Long Now Foundation we have talked about clocks, plural. There are probably going to be more clocks in the future. For instance, the world needs a 10,000-year clock that is more easily accessible than this one. We've started conversations with different potential hosts about building a clock in their city. Institutions like the Smithsonian have expressed interest in a clock of their own. And we still have the Nevada site where we originally wanted to build a clock. That site has a very clear mountaintop where you can see the stars in some of the darkest skies in the United States, and the site is surrounded by Bristlecone pines, the oldest living trees on the planet. All that lends itself to a very different kind of design. For instance, a clock for that mountain probably doesn’t want to be underground but outside, looking up. There are many ways to design a symbol for the future.

— Danny Hillis, February 02024

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