A clock that runs for 10,000 years - the clock of the long present by Jef Besos

The first prototype, exhibited at the Science Museum in London, 2005

The Long Now Clock, also known as the 10,000-Year Clock, is a mechanical clock under construction that will keep time for 10,000 years. It is being built by the Long Now Foundation.

A two-meter-tall prototype is on display at the Science Museum in London. Since June 2018, two more prototypes have been on display at the Long Now Museum & Store at the Fort Mason Center in San Francisco.

The project was conceived by Danny Hillis in 1989. The first prototype of the clock began operation on December 31, 1999, just in time to mark the transition to the year 2000. At midnight on New Year's Eve, the date display changed from 01999 to 02000, and the chimes struck twice.

The production and construction of the first scale watch prototype is funded by Jeff Bezos' investment firm Bezos Expeditions with $42 million and will take place on land owned by Bezos in the Sierra Diablo mountains of Texas.

Stewart Brand, a founding member of the foundation, put it this way: "Such a clock, if sufficiently impressive and well constructed, would embody profound time for people. It should provide a fascinating visit, an interesting insight into time, and be so widely known that it becomes an icon in public discourse. Ideally, it would do for thinking about time what Earth photographs from space have done for thinking about the environment. Such icons change the way people think."[3]

design
I want to build a clock that ticks once a year. The century hand advances every hundred years, and the cuckoo chimes at the turn of the millennium. I want the cuckoo to chime every millennium for the next 10,000 years. If I hurry, I should finish the clock in time to see the cuckoo chime for the first time.

— Danny Hillis, “The Millennium Clock,” Wired Scenarios, 1995[4]
The basic design principles and requirements for the watch are:[5]

Durability: The clock should still be accurate even after 10,000 years and must not contain any valuable parts (such as jewels, expensive metals, or special alloys) that could be plundered.

Maintainability: Future generations should be able to keep the clock running if necessary using Bronze Age tools and materials.

Transparency: The watch should be understandable without stopping or disassembling it; no function should be opaque.

Evolvability: The watch should be able to be improved over time.

Scalability: To ensure that the final large clock functions properly, smaller prototypes must be built and tested.

Whether the clock has actually been continuously maintained and serviced over such a long period is questionable. Hillis chose the 10,000-year target as just about plausible. There are technological artifacts, such as fragments of pots and baskets, that are 10,000 years old.

So there are some precedents for human artifacts surviving this long, although very few human artifacts have been continuously maintained for more than a few centuries.