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The 10,000 Year Clock

These are the principles that Danny Hillis used in the initial stages of designing a 10,000 Year Clock. We have found these are generally good principles for designing anything to last a long time.

Longevity

With occasional maintenance, the clock should reasonably be expected to display the correct time for the next 10,000 years.

Maintainability

The clock should be maintainable with bronze-age technology.

Transparency

It should be possible to determine operational principles of the clock by close inspection.

Evolvability

It should be possible to improve the clock with time.

Scalability

It should be possible to build working models of the clock from table-top to monumental size using the same design.

Longevity:
Go slow
Avoid sliding friction (gears)
Avoid ticking
Stay clean
Stay dry
Expect bad weather
Expect earthquakes
Expect non-malicious human interaction
Dont tempt thieves
Maintainability and transparency:
Use familiar materials
Allow inspection
Rehearse motions
Make it easy to build spare parts
Expect restarts
Include the manual
Scalability and Evolvabilty:
Make all parts similar size
Separate functions
Provide simple interfaces

Examples:

Clepsydra (water clock) Atomic Clock
Power potential energy supplied by human electricity
Time flow rate of water oscillation of cesium atom
Convert lever with e.o.t. adjustment electronic frequency divider
Display pointer, gong numeric display, radio

Options considered for powering the Clock:

Atomic Poor maintainability&transparency
Chemical Poor scalability
Solar Electric Poor maintainability
Pre-stored potential energy Poor scalability
Water flow Exposure to water
Wind Exposure to weather
Geothermal Poor scalability
Tidal gravitational changes Poor scalability
Temperature change ...
Pressure change Need for bellows or seal
Seismic and plate tectonic Poor scalability
Human winding Fosters responsibility

Conclusion: My current favorite is human winding because it fits with goals of clock. Temperature change is also a viable alternative.

Options considered as sources of timing for clock:

pendulum innacurate
spring and mass innacurate
water flow innacurate and wet
solid material flow innacurate
daily temperature cycle unreliable
seasonal temperature cycle imprecise
tidal forces difficult to measure
earths rotating inertial frame difficult to measure accurately
stellar alignment unreliable (clouds)
solar alignment unreliable (clouds)
atomic oscillator too high tech, difficult to maintain
piezoelectric oscillator too high tech, difficult to maintain
atomic decay difficult to measure precisely
wear and corrosion very inaccurate
marble roll very inaccurate
diffusion inaccurate
tectonic motion difficult to predict and measure
orbital dynamics difficult to scale
audio oscillator inaccurate and difficult to measure
pressure chamber cycle inaccurate
inertial governor inaccurate
human ritual too much dependence on humans

Conclusion: Since no single source does the job, use an unreliable timer to adjust an inaccurate timer, creating a phase locked loop. My current favorite combination is to use solar alignment to adjust a slow mechanical oscillator.

Options considered for the part of the Clock that
converts time source to display units:

Electronics Poor maintainability&transparency
Gears Need for rational approximation
Pre computed display Lots of calendar pages
Levers Require very slow timing source
Hydraulics High power
Mechanical Digital Logic ...

Conclusion: Mechanical digital logic.

Options for how to display time:

chimes Poor maintainability&transparency
flutes or whistles cannot sound too often
sweeping hand fragile, confusing for many hands
concentric rotating rings ...
balls in holes creates collectibles
shadows, beams of light ...
animation high power

Conclusion: This is the one I have thought about the least. Note that there can be multiple displays, and that some display can have independent power sources.

Some options for what to display:

Display Days per cycle
Time of Day 1
Phase of moon 29.5305882
Lunar eclipses -6793.504897308
Season 365.242
Positions of
visible planets
mercury 87.969
venus 224.701
earth 365.256
mars 686.980
jupiter 4331.772
saturn 10759.22
Procession of zodiac 9417404.8533435
Christian Calendar approximates solar years
Moslem Calendar approximates lunar years
Jewish calendar ...
Chinese calendar ...
Mayan calendar 360
day count 1
moon count 29.5305882
year count (centuries, millennia) 365.242
historical events (past and future) ...

Other information to display: (library functions)

future time scales ...
astronomical ephemeris ...
maintenance manual ...
visits to the clock ...
weather records ...
earthquake records ...
calendar systems ...
general useful knowledge ...

The design principles for the clock were primarily the work of Daniel Hillis with additional thoughts brought about by discussion with the other founding board members.