Good ideas are often thwarted by selfish little minds with the crassest of motivations.
A couple of anecdotes:
Hiking along the beach in the Moskito Coast region of Honduras I saw a number of strange devices. Imagine a concrete slab about eight feet square with a bollard in the center. It looked like something that a ships lines may be fastened to but no-one was going to be trying to moor a small ship on a sandy beach. From time to time a boat would come to grief on the beach and it only took a day or so for a small storm and wave action to destroy the boat. A mooring device was not the purpose.
I finally found out the purpose of the devices. A do-good feel-good group had decided that the villagers living along the beach needed latrines. The devices were the lid of a septic tank and a cast in place, concrete toilet. There was originally an enclosure but when the builders left there was a rush to steal all the building material that could easily be moved.
On a trip through the beach villages in the same area, I noticed a pipe issuing about three feet from the ground every few miles.
Another Do-good feel-good group had decided that wells would be a good idea and had installed well points and hand pumps in the villages. No-one owned these improvements and no-one had responsibility for them. I was told that a local drug user had removed the pumps and sold them to purchase drugs until all the pumps were gone.
I suggest that by far the most challenging problem will not be building a 10,000 year clock or 10,000 year any-thing.
The problem will be ensuring the security of the device.
I visualize a group seeking shelter during a downturn in civilization sometime in the future. It won't take much intellectual capacity to figure out where to drop a rock so that the darn thing stops and the ticking doesn't keep every one awake all night.
Some equally mundane fate will do this clock in long before the 10.000 years pass.
Bill
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"Why not the best?"
Jimmy Carter