I've seen related discussions here before so thought I'd share this idea. It is believed to be the only realistic (doable) method an individual or small group could use to apply such force upon Earth to move it, requiring the force be from an external source.

Studying the Earth-Moon tidal force it occurred that energy from the system (moon) could be used to apply an external force (non-Earth reference frame) to turn the Earth.

By affixing a horizontal lever (eg. 100m long) onto the ocean floor or an island mass, and attaching a large plate, parachute etc. or an array of them to the lever's end, to capture (resist) the ocean tidal movement as the moon passes above each day. Collectively the force applied by the moon dragging the seawater, will slowly apply the force to the rigid lever base (the Earth itself). The ocean tide can provide the enormous energy necessary, free and scalable.

The simple design requirement provides a non-maintained, energy free apparatus which will continue to apply angular momentum at the base of the lever, drawn from the moon-earth gravity. Newton's laws remain intact.

  • $\begingroup$ "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." - Archimedes $\endgroup$ – Xandar The Zenon Mar 6 '16 at 3:34
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    $\begingroup$ Do you want to change the rotation rate of the Earth, or do you actually want to move it, i.e. change its orbit? The former is in principle possible this way (and as ckersch points out, happens natually already) but the latter is not, since interactions between the Earth and Moon cannot affect the centre of mass of the combined Earth-Moon system. $\endgroup$ – Nathaniel Mar 6 '16 at 4:04
  • $\begingroup$ Thanks Nathaniel, PC problems last night so late in replying.Neither. Rotate the poles by converting the linear ocean tide force, to rotational energy through the lever, onto a fixed object such as a large rock formation on the sea floor. The lever would provide a few hours per day, for decades, rotational energy/angular momentum, very slowly turning the poles. The equator would move accordingly north or south. The planet's systems would change. $\endgroup$ – Achbarr Mar 7 '16 at 19:00

This works very slowly, and is already happening!

What you're describing already happens everywhere in the oceans of Earth, thanks to the friction between the ocean and the land beneath it. Since the Earth rotates faster than the moon orbits, this force acts in a direction opposite to the rotation of the Earth, gradually slowing down the rotation of the Earth. The effect of this, in the modern day, is a slow down in the rotation of the Earth by about 2.3ms/century. The general term for this phenomenon is tidal acceleration.

This frictional process on Earth currently generates around 3 TW of energy, so in order to significantly slow the Earth down, you'll need to dissipate substantially more than that through additional frictional forces you create. For reference, humans consume, on average, around 11 TW of energy, so if you can create tidal frictional forces equal to all of human energy consumption, you'd slow the rotation of the earth by around an additional 10ms/century.

Instead of dissipating that energy as friction, of course, you can choose to use it to spin turbines. This will produce usable energy you can use to power countries, or large mad scientist lairs, while slowly but surely accomplishing your nefarious goal of slowing down the rotation of the Earth.

  • $\begingroup$ I've read slowing the Earth 1% will end all life on Earth, however I don't think so as I believe it's slowed around 15% over it's history. Instead, what I'm after is rotating the poles. So as example, London may be situated on the new equator for a time. The amount of energy applied from outside Earth's reference frame (moon-tide) will be much less doing this approach. The (not yet quantified) apparatus may include a 4mile x 2mile undersea sail mounted on a fixed A-frame on the sea floor and a 1/3mile long lever perhaps fixed to a rock formation at its base, converting linear tide cont/... $\endgroup$ – Achbarr Mar 7 '16 at 20:40
  • $\begingroup$ .../cont force to rotational force/angular momentum, pulling the lever at one end, and applying the turning force onto its base to the sea floor, IE. the planet itself. The implementation is practical for a well funded individual or small group with average skills. The apparatus requires no ongoing energy cost or maintenance, is virtually undetectable and will continue to work for decades unmanned. Quantifying this process and further design considerations is my next task. Realism in authorship can be enhanced by inclusion of real and unknown solutions I think. Any further comments appreciated $\endgroup$ – Achbarr Mar 7 '16 at 20:45

Larry Niven proposed one in, I think, "All the myriad Ways" by using a hydrogen fusion rocket floating in the atmosphere of Uranus to move Uranus around, then using that in a series of fly-bys past Earth to drag it into a new orbit.

Remember that planets have essentially zero structural strength compared to their mass. There is a good reason that earth sized planets are smoother than billiard balls (relative to their diameter) Any movement method has to apply to all of the mass at once, or be a small fraction of a standard G (< 1/1000) to keep the planet from falling apart. At that you will be seriously inconvenienced as the oceans slump away from the direction of thrust. Probably slip every fault, and wake up lots of volcanoes too.

  • $\begingroup$ Thanks for the ideas. I was thinking about the after effects of such polar rotation, which may impact the tidal force on the planet itself at a different angle and would likely effect tidal-lock, currents, tectonic plates, all seasons, weather and geopolitical/ social situation initially. As I've mentioned I'm interested in this as I understand this is real/doable whereas many ideas are plausible or unknown such as giant gyro coupled to the planet, but not actually able to be carried out in the real world, and application by an individual, so not of interest to my writing. $\endgroup$ – Achbarr Mar 7 '16 at 21:35

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