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Shards, fragments, and ruins are all that remain from the earliest human civilizations ten thousand years ago. Nothing continues to function as it once did; the Earth has ruthlessly erased all that other humans did not destroy. But ten thousand years from now, in a cave in what is now Nevada, a single functional sign of human technological prowess may continue to tick, whether there are humans there to observe it or not. And no, it isn’t Yucca mountain.

The Clock, as its designer Danny Hillis calls it, will stand over 60 feet tall and keep track of every second, minute, day, century, and millennium for at least 10,000 years. Over that time, it will function with near perfect accuracy by occasionally resetting itself automatically using the warming heat of the desert sun. Its pendulum will be powered by the Earth itself – by temperature and pressure changes during the desert night. But its many faces will require winding. Thus if forgotten it will enter a long silence but continue to mark the years as they pass.

For all our technology, we as a society have little experience designing machines to operate for 400 generations. Since Hillis only has one chance to get things right, the Clock will not be the first that is created in its image. Over three years in construction, Prototype 1 was finished just in time to ring in the millennium on December 31st, 1999. Resting in the halls of London’s Science Museum, Prototype 1 ticks once every 30 seconds. Its polished and brushed metal surfaces gleam in the sunlight and track the hours, years, centuries, and phases of the moon and zodiac. Already, Prototype 2, displaying the orbits of the 6 naked-eye visible planets, has been built and is ready to begin its 10,000 year lifespan. More will follow until Hillis is satisfied that the Clock is ready.

Over so long a period, metal parts fatigue and wear, so the Clock can not be made with traditional works. Inside both Prototypes is a digital computer capable of counting to 28 bits of accuracy. But this computer, called a serial bit adder, is a completely mechanical device invented and patented by Hillis. The serial bit adder is designed so that even with severe wear, its parts will continue to count correctly. Even silicon microchips with no moving parts will cease to function long before this because of the very slow process of solid atom diffusion.

Yet even if the Clock can keep ticking, will there be anyone to hear it ring in the year 12,000? Hillis believes that the very presence of a machine intended to operate for 10 millennia will help humanity to achieve a longer perspective on our future. This musing is what led him, along with Stewart Brand, to found the Long Now Foundation. In addition to funding the building of the clock, the Long Now Foundation encourages people to stretch their horizons and see their actions as part of a much larger web of human existence. Among other activities, the Foundation invites famous thinkers and futurists to monthly seminars in order to help us plan now so that our descendants may someday witness the Clock’s final tick.