I love this idea, but the speed of separation is just a couple of cm per year. Unless the cable had absolutely no temperature expansion, weather changes would probably have a far greater effect on cable length than the imperceptible drift of the endpoints (which suggests another crazy idea interesting in its own right).

One might build this deep underground to minimize temperature changes and provide the hard rock anchor points necessary for the forces involved.

> weather changes would probably have a far greater effect on cable length than the imperceptible drift of the endpoints (which suggests another crazy idea interesting in its own right)

There is a clock running for over a century based on a similar idea: https://en.wikipedia.org/wiki/Beverly_Clock

...and the commercial version, which is still in production:

https://en.wikipedia.org/wiki/Atmos_clock

Not cheap (few k$), but not as expensive as some other high-end timepieces either.

Go deep enough and you might as well just build a geothermal power plant.

Kenya is way ahead of you:

https://www.nytimes.com/2018/02/23/business/geothermal-energ...

Kenya generates 47% of power from geothermal and 35% from hydro. For a third world country, it’s quite greener than most developed nations. https://mobile.nytimes.com/2018/02/23/business/geothermal-en...

I do hope Kenya gets a electric car boom, because all of it’s fuel is imported. Solar + other methods could power the whole economy with relative ease. Being on equator means plenty of sun throughout the year.

Which would have the side effect of actually generating power!

> Unless the cable had absolutely no temperature expansion...

One might be able to get a composite with very close to zero thermal expansion coefficient by linking stages made of materials with positive and negative [1] coefficients.

[1] https://en.wikipedia.org/wiki/Negative_thermal_expansion

You don't even need to use exotic materials with negative thermal expansion: instead, you can use a combination of materials with different coefficients of thermal expansion pointed in opposite directions. This was one of the innovations that John Harrison made that allowed him to make precision timepieces.

https://en.wikipedia.org/wiki/Gridiron_pendulum

You could use a couple of anchors so that when it only moves 1mm the end attached to the gear would move several meters. Where the gear is really huge which makes the small gear spin faster. But it might still be too slow.

Seems like someone already had that idea, atleast for the continental shelf: https://patents.google.com/patent/US8258638

Something with that much gear ratio would essentially be locked. It would most likely just tear the mechanism apart before it did any actual work.

Then a thousands of them over the split with a thousands less ratio :P

You'd stand a better chance to get that to work by using hydraulic pistons that are used to compress a working fluid using an appropriately placed lever.

There’s lots of other ‘free’ and ‘infinite’ energy around that is much easier to collect. You could go to the moon and make strawberry jam and then market it as ‘Space Jam’ but it’s simpler and cheaper to skip the whole moon part.

Considering the drift is occurring at a rate of a couple millimetres a year...no.

With high enough gearing that is plenty. The issue is we are not capable of building strong enough gears.

Please read https://news.ycombinator.com/newsguidelines.html, which ask you not to snark or to post shallow dismissals.

A good version of this comment would explain what's wrong with the original idea, so that readers who don't know could learn something.

Physics taught me that all pulleys are frictionless.

Mechanical Engineering may find some issues with it though...

Or you both can consider stepping down from your high horses. It is a fun tongue-in-cheek idea, and the author explicitly mentioned the need for a gearbox. I am teaching physics and I will probably use this example in a lesson soon, because it is actually interesting to discuss why this idea would not work in practice (in principle all you need is indeed just a perfect gearbox).