How would a Machine at the Heart of the World tidally lock the Earth?

[Cerenkov]

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

In Roger Zelazny's 1971 novel Jack of Shadows the Earth is held tidally locked by the influence of a vast machine at the planet's centre. No, the machine is surrounded by cold, solid rock and not molten rock... but never mind that. Anyway, I was wondering what kind of forces such a machine would have to counteract / compensate for to keep one half of the world in permanent darkness and the other in permanent light?

I can't offer much in the way of additional information, except for these items.

On the Dark side, where magic rules, that half of the world is prevented from freezing into Allwinter by the Compact. This is a loose confederation of sorcerers who unite to keep the Shield positioned directly above the Eastern pole of the world. Though it's never explicitly stated I suspect that the black sphere of the Shield is actually the Moon, which is being held at the anti-solar point by magic.

On the sunlit side, where technology rules, the Daysiders use nuclear-powered force screens to protect themselves from the Sun's incessant glare. Apart from the Sun being stationary in their sky their civilization is in most respects just like our own. They use computers, drive cars, fly planes and so on. But because it never gets dark their technology has never gone beyond the candle when it comes to providing illumination.

There is a Twilight zone between the Dark and Light sides where the influence of technology AND magic fade and are eventually nullified.

So, with the Earth not rotating on its axis and with the Moon held at the anti-solar point by magic, what stresses and forces would the Machine at the world's core have to deal with?

A follow on question from this is as follows.

Towards the end of the tale the Machine is sabotaged and destroyed to allow the Earth to begin rotating. The author describes such catastrophic effects as earthquakes, tsunamis, volcanic eruptions and devastating storms happening as the result of the rotation. Would that be all or would there be other effects as the Earth begins to spin on its axis?

Thank you,

Cerenkov.

 

[256bits]

Would that be all or would there be other effects as the Earth begins to spin on its axis?

I don't know why the planet would start up spinning, being tidally locked, and with the moon perhaps supposedly at Lagrange L2. Tidal locking is the evolution of moons with planets, and planets with their suns, over very long times and doesn't require magic or a machine.

Nevertheless, in the story, the earth begins to spin up for whatever reason.

 

[jedishrfu]

I imagine the machine was like a dad pushing their kid on a swing. You keep injecting a little energy with a push and after awhile let it decay or actively counterpush ie slow the swing by absorbing some of it's energy.

In truth though that wouldn't work but perhaps the spinning skater idea would work. Arms out to slow down and arms in to speed up.

 

[Bandersnatch]

Just reinforcing post #2 here.
If the Moon is out of the picture, by the virtue of it being held in place by magic, then there are no non-negligible forces in play. The Moon-less, tidally locked to the Sun state is the equilibrium the system is currently evolving towards. The only reason it won't get there is that there won't be enough time before the Sun leaves the main sequence.
I.e., the machines don't need to do any work, and nothing would happen if they turned off.

 

[DaveC426913]

I don't know why the planet would start up spinning, being tidally locked, and with the moon perhaps supposedly at Lagrange L2. Tidal locking is the evolution of moons with planets, and planets with their suns, over very long times and doesn't require magic or a machine.

Nevertheless, in the story, the earth begins to spin up for whatever reason.

We have to presume it was indeed tidally-locked to the sun.

That seems pretty obvious, but we don't really know that the premise of the story is that the Earth was stablely locked to the Sun. (do we?)

What if it was artificially locked in an unstable configuration by the machinery, and when the machinery stopped, the Earth started to re-orient to its proper tidal-locked configuration?

 

[Cerenkov]

We have to presume it was indeed tidally-locked to the sun.

That seems pretty obvious, but we don't really know that the premise of the story is that the Earth was stablely locked to the Sun. (do we?)

What if it was artificially locked in an unstable configuration by the machinery, and when the machinery stopped, the Earth started to re-orient to its proper tidal-locked configuration?

Yes, that's right Dave.

In the story the Earth was tidally-locked to the Sun to give Zelazny what he needed, a world half in darkness and half in light. He never explicitly mentioned what the Moon was doing, but he did mention that there was a black sphere in the sky directly over the Earth's anti-solar point. So it's only my supposition that this was the Moon, being held in the umbral cone of shadow cast by the Earth.

All of the above was achieved artificially and did not naturally evolve this way. The black sphere is called the Shield by the darksiders and they hold it in place with mighty magics. The Great Machine at the centre of the world "somehow" holds the Earth locked and unturning using technology. Nothing else is known or mentioned or even hinted at.

Now its my naïve understanding that a planet would have to be within the orbit of Mercury to become tidally locked by natural forces. Which is not the case for Zelazny's non-rotating Earth. That outcome was achieved by a combination of magic and technology.

Since its impossible for us to even speculate upon the magic I was wondering what would be required in technological terms to achieve this unusual and highly artificial arrangement of Sun, Earth and Moon. That is, to stop the Earth's rotation and to keep the planet permanently fixed with one specific point on its surface always directly under the Sun.

On a side note and perhaps someone can correct me here, isn't it the case that the moon Charon is tidally locked to the dwarf planet Pluto in a similar way? So that if you stood at the correct location on either body the other would always be directly overhead and never appear to move?

Thanks,

Cerenkov.

 

[Hornbein]

A tidally locked planet rotates once year. To slow the rotation of a planet one could fire off mass into space counter to the planet's rotation. If it has to be a machine in the center of the planet then it would be very massive and rotate in the same sense as the planet but much faster. The back reaction would slow down the planet's rotation. The amounts of energy involved would be enormous.

 

[Algr]

This can only be a fantasy book though. The premise really doesn't make any sense. Slowing a planet to tidally locked would take obscene amounts of energy, and what would that accomplish? It would be cheaper and faster to build a counter rotating shell enclosing the entire Earth and held up by wheels like a rotating restaurant. Then they would build a fake world on that while the real Earth kept rotating five feet underneath the fake one.

In fact, that is a way the Earth could start rotating again. If the shell breaks, the real Earth would drag it along.

 

[Hornbein]

On a side note and perhaps someone can correct me here, isn't it the case that the moon Charon is tidally locked to the dwarf planet Pluto in a similar way? So that if you stood at the correct location on either body the other would always be directly overhead and never appear to move?

So Wikipedia says.

Neptune has a counter-orbiting moon. This will cause it to eventually crash into the planet.

 

[DaveC426913]

On a side note and perhaps someone can correct me here, isn't it the case that the moon Charon is tidally locked to the dwarf planet Pluto in a similar way? So that if you stood at the correct location on either body the other would always be directly overhead and never appear to move?

Correct.

In fact, it is surmised that they even share their atmosphere.

 

[Cerenkov]

To Hornbein and Algr...

Yes, this is indeed a fantasy story. Zelazny was noted for his ability to seamlessly blend fantasy with science fiction.

As regards the Great Machine, here's how it is described in the book.


It had so many gears that it would have been an interminable task to number them, some turning slowly, some rapidly, big unto small: and there were cams, drive shafts, and pulleys and pendulums - some of the pendulums twenty times his own height and slow, ponderous - and pistons and things that corkscrewed in and out of black metal sockets; and there were condensers, transformers and rectifiers; there were great blue-metal banks containing dials, switches, buttons and little lights of many colours, which constantly blinked on and off; there was a steady noise, a hum, of still further buried generators - or perhaps they were something else, possibly drawing power from the planet itself, its heat, its gravitational field, certain hidden stresses - which buzzed in his ears like a swarm of insects; there was the blue smell of ozone, reaching everywhere.

There was a brilliant light coming from all the walls of the enormous cavern which housed the equipment; there was a battery of buckets which moved on guidelines above the entire complex, occasionally pausing in their courses to dump lubricants at various points; there were power cables, like snakes, that wound from one point to another, indicating nothing that he could understand; there were tiny, glass-enclosed boxes, connected with the whole by means of thin wires, which connected components so minute that he could not discern their forms from where he lay.

There were no fewer than a hundred elevator-type mechanisms, which constantly plunged into the depths or vanished overhead, and which paused at various level to extrude mechanical appurtenances into portions of the mechanism; there were wide red bands of light on the farthest wall, and flicked on and off; and his mind could not encompass all that he saw, felt, smelled and heard...


Fantasy, of course.

But my interest was piqued by that mention of hidden stresses. What would they be in the real world? Just curious.


Cerenkov.