4 ms·

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 p

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.

NegativeLatency 9y ago
Go deep enough and you might as well just build a geothermal power plant.
- deadmetheny 9y ago
  Which would have the side effect of actually generating power!
- theandrewbailey 9y ago
  Kenya is way ahead of you: https://www.nytimes.com/2018/02/23/business/geothermal-energy-grows-in-kenya.html https://www.nytimes.com/2018/02/23/business/geothermal-energ...
  - nojvek 9y ago
    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-energy-grows-in-kenya.html 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.
sannee 9y ago
> 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 https://en.wikipedia.org/wiki/Beverly_Clock
- userbinator 9y ago
  ...and the commercial version, which is still in production: https://en.wikipedia.org/wiki/Atmos_clock https://en.wikipedia.org/wiki/Atmos_clock Not cheap (few k$), but not as expensive as some other high-end timepieces either.
- aaron695 9y ago
  > running for over a century Continuing to work after a century.
avz 9y ago
> 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 https://en.wikipedia.org/wiki/Negative_thermal_expansion
- jmharvey 9y ago
  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 https://en.wikipedia.org/wiki/Gridiron_pendulum
z3t4 9y ago
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.

NegativeLatency 9y ago

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

deadmetheny 9y ago
Which would have the side effect of actually generating power!
theandrewbailey 9y ago
Kenya is way ahead of you: https://www.nytimes.com/2018/02/23/business/geothermal-energy-grows-in-kenya.html https://www.nytimes.com/2018/02/23/business/geothermal-energ...
- nojvek 9y ago
  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-energy-grows-in-kenya.html 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.

sannee 9y ago

> 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 https://en.wikipedia.org/wiki/Beverly_Clock

userbinator 9y ago
...and the commercial version, which is still in production: https://en.wikipedia.org/wiki/Atmos_clock https://en.wikipedia.org/wiki/Atmos_clock Not cheap (few k$), but not as expensive as some other high-end timepieces either.
aaron695 9y ago
> running for over a century Continuing to work after a century.

avz 9y ago

> 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 https://en.wikipedia.org/wiki/Negative_thermal_expansion

jmharvey 9y ago
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 https://en.wikipedia.org/wiki/Gridiron_pendulum

z3t4 9y ago

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.