There’s been a lot of news lately about the Long Now Foundation and Jeff Bezos spending $42 million or so on a giant mechanical clock that is supposed to run for 10,000 years. We aren’t sure we really agree that it is truly a 10,000 year clock because it draws energy — in part — from people visiting it. As far as we can tell, inventor Danny Hills has made the clock to hoard energy from several sources and occasionally chime when it has enough energy, so we aren’t sure how it truly sustains itself. However, it did lead us to an interesting question: how could you design something that really worked for 10,000 years?
The first question might be why would you want to? We aren’t sold on the clock. But there are at least two easy answers for that: storing very bad things safely and generational starships. We are certainly generating nuclear and biological materials that need to be kept locked up for a long time. If we wanted to go to another star system today, we would have to build a ship that would get our descendants to even the nearest star. In both cases, things would have to last and either need no repair or be sustainable.
How Old is Old?
The clock appears to be mostly mechanical and we do have examples of purely mechanical things lasting a very long time, although not always in the best of shape. It doesn’t hurt that the clock ticks once a year.
The megalithic temples of Malta date back about 5,000 years — older than the Egyptian pyramids or Stonehenge. Dating back from around the same time is the Knap of Howar, an old Scottish farmstead and Newgrange, and Irish religious site.
Of course, those aren’t machines and they aren’t 10,000 years old. In Turkey, there are some ancient homes that are nearly 10,000 years old and some large megaliths, although they are hardly well-preserved. There are even parts of the Wall of Jerico that are about the same age.
For long-lived machines, the numbers are much worse. Some church clocks date back to the 1300s. That’s not even a blip on a ten millennia timeline. The oldest steam engine still around is even newer, dating to 1725. So building true machines to last on this scale is a relatively unproven idea. Granted, materials are better today, but then again things are more complex, too.
Problem #1: Power
This would be a big problem. It is easy to wave your hand away and call for nuclear power or batteries, but making those last a long time is an even bigger problem. True, nuclear batteries can last for a century or more, that’s still a far cry from 10,000 years. If you could make a reactor that lasted long enough, you’d still need to refuel it, although the half-life of uranium is in the millions or even billions of years (depending on the isotope), so that’s viable, but you’ll have to carry a lot and have a reliable way to refuel.
If you are Earth-bound, solar or geothermal or even wind might work. None of those would work well for an interstellar spacecraft, though. Molten salt batteries are known to have long shelf lives, but don’t usually last very long once activated.
At the University of Oxford, there are some bells that have been ringing on a single battery for nearly 200 years, but that’s a special and unusual case. So power seems to be a key problem. But it isn’t the only one.
Problem #2: Mechanics and Other Things that Age
Real-world parts wear. Springs get less springy. Magnets demagnetize. Electrolytic capacitors dry out. Metals in ICs electromigrate or grow dendrites. Moisture gets into packages. We don’t often have to deal with much of this because it happens over a long time scale to our normal usage. But those things — and probably more — would become problematic over a few thousand years.
Imagine a generation ship with switches. Mechanical switches. You’d have to carry a lot of spares or a shop for fixing or making new switches, along with the raw materials to do so. Could you do better? A touchscreen is probably too complex. What about an LED and a light sensor with a finger-sized hole? No mechanics, but you probably still won’t get that much life out of an LED, especially if it is on nearly all the time.
The nuclear waste vault is even more problematic because it should continue to function even if no one is around to take care of it. How do you leave a warning for the next wave of humans or cockroaches or whatever inherits what’s left?
Probably Not the Next Contest
At Hackaday, we love to spur innovation through contests. However, we don’t think we want to wait 10,000 years to judge your nuclear waste bunker, although time dilation might help with your spaceship if you can go fast enough.
Seriously, though, what kind of things would you do to ensure a design could run for a century? Or a millennium? Or even 10,000 years? Is there a practical limit to how long an electronic device could last? Let us know in the comments.