Bernhard Herbordt's Profile

The basic design principles and requirements for the clock are:

1. Longevity: The clock should be accurate even after 10,000 years, and must not contain valuable parts (such as jewels, expensive metals, or special alloys) that might be looted.
2. Maintainability: Future generations should be able to keep the clock working, if necessary, with nothing more advanced than Bronze Age tools and materials.
3. Transparency: The clock should be understandable without stopping or disassembling it; no functionality should be opaque.
4. Evolvability: It should be possible to improve the clock over time.
5. Scalability: To ensure that the final large clock will work properly, smaller prototypes must be built and tested.

Self-contained clocks

Most of these methods are inaccurate (the clock will slowly become less correct) but reliable (the clock will not suddenly stop working). Others are accurate but opaque.

• pendulum (inaccurate over the long term, and requires lots of ticks, which creates wear)
• torsion pendulum (less frequent ticks, but even less accurate)
• balance wheel (more inaccurate than pendulum)
• water flow (inaccurate and wet)
• solid material flow (inaccurate)
• wear and corrosion (very inaccurate)
• rolling balls (very inaccurate)
• diffusion (inaccurate)
• tuning fork (inaccurate)
• pressure chamber cycle (inaccurate)
• inertial governor (inaccurate)
• atomic oscillator (opaque, difficult to maintain)
• piezoelectric crystal oscillator (opaque, difficult to maintain)
• atomic decay (opaque, difficult to measure precisely)

External events that the clock could track or be adjusted by

Many of these methods are accurate (some external cycles are very uniform over huge stretches of time) but unreliable (the clock could stop working completely if it failed to track the external event properly). Others have separate difficulties.

• daily temperature cycle (unreliable)
• seasonal temperature cycle (imprecise)
• tidal forces (difficult to measure)
• Earth's rotating inertial frame (difficult to measure accurately)
• stellar alignment (unreliable because of weather)
• solar alignment (unreliable because of weather)
• tectonic motion (difficult to predict and measure)
• orbital dynamics (difficult to scale)
• human ritual (too dependent on humans).