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by ChrisNorstrom 445 days ago
My Stupid Question, please don't laugh:

If you did this on a massive enough scale, to generate serious amounts of power, would that accidentally slow the Earth's rotation down over time?

10 comments

It isn't a stupid question, it is a good one. The answer would depend on how the field is generated in the first place.

Given a field generated by asymmetric rotation of the molten core at the center of the Earth, 'shorting it' (apply a load) would presumably affect the core's rotation. In terms of relative energy however, the poor coupling at the surface would suggest that this would be a very challenging way to divert any meaningful amount of power from the core itself. It would however have to deal with points in time where the core reverses its magnetic field. The papers on core reversals are fun to read.

I think more usefully, the presence of the voltage, might be an interesting way to localize one's location and orientation.

I remember brainstorming "off the wall" power generation ideas and one that has yet to be realized would be to inject dust ahead of a wind turbine with a collector in the back. Then using the Van DeGraf effect to generate power instead of lightning as it currently does.

If one needs location, then the magnetic field can be measured directly. It is already considered as a potential alternative for GPS, https://www.electronicdesign.com/markets/automation/article/...

The main problem is that locally measured Earth magnetic field varies on a daily basis and is strongly influenced by solar storms.

A better alternative is to use variations in Earth gravity to improve inertial navigation. That vastly more stable.

They are one step ahead of you. :-)

"We previously showed that even in an extreme scenario where our civilization somehow would obtain all its electrical energy from the effect described here, Earth’s rotation would slow by <1 ms per decade [2]."

fast forward a hundert years and there is a massive culture war between the "rotation slowdown deniers" and people religiously buying "rotation friendly" products.
The term "generate power from Earth's rotation" is basically saying "convert kinetic energy from Earth's angular momentum". If you extract energy, by conservation of energy that energy has to come from somewhere. So yes, we would normally expect Earth's rotation to slow.

But I think if you do the math, it would be absolutely miniscule.

I'm not saying that is why we left Mars.
It's definitely not why we left Mars because Mars still rotates every 24:30. We left Mars because of the hostile Martians, of course.
Yeah, after making an oopsie with a runaway greenhouse effect in Venus. All this has happened before and it will happen again.
Ah yes, the Battlestar Galactica theory of life's origins on earth
I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?
On a local level they absolutely do, in a wind farm one turbine can shadow another and reduce its output significantly. It makes wind farm layout a tricky optimisation problem. On larger scales the impact is pretty minimal though, there’s so much energy spread over such a large area that significantly reducing it a global scale is not a concern.
Fundamentally, yes, right? For some definition of “enough.”

Actually, after some quick googling (so, maybe someone actually knows better) it seems like this is an issue where there’s an active discussion? Maybe somebody actually involved in the field knows more.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2004JD00...

https://esd.copernicus.org/articles/3/79/2012/esd-3-79-2012....

But that came out in 2012. I bet you could find some other article citing it, as rebuttals.

It seems a bit implausible to think we could somehow pull enough energy from the wind to really matter, but then again carbon based climate change also seemed a bit implausible so, I guess, who knows?

If a politician talks in front of a wind turbine, does it make a sound?
Not stupid at all, especially if only one part of physics exists and not quantum physics.
Alternatively, we could speed up the Earth! Let's get rid of those pesky leap seconds!
No because of conservation of angular momentum. Maybe it would cool the Earth's interior faster than otherwise though. It's heat flow from the inside to the outside that drives the fluid flows in the mantle and generates the magnetic field.
Earth's rotation has been slowing down despite principle of conservation of angular momentum, at about 2 mille-sec/century. Dinos had an hour shorter days than we do now.

I'm not an EE, but isn't this related to Tesla's last invention which bankrupted him - I believe he was working on electricity generation from thin air.

It's slowing down mostly because of drag induced by tides, which involve the sun and the moon. The total system including the earth, moon, sun and everything else does conserve angular momentum.

But this paper seems to imply that Earth, isolated from evening else in the solar system, could be made to slow down. This does seem like a violation of conservation of angular momentum...

This is poorly discussed in the article and AFAICS it reaches wrong conclusion.

I think the energy comes from weakening of the magnetic field and the energy stored within it, not from slowing down earth rotation. Earth as the result may rotate faster as the moment stored in the field will be transferred back to Earth as in the example with a sphere from the article.

That would make so much more sense. So then the comments about only slowing down Earth's rotation by a few ms/century. It would deplete Earth's magnetic field, and likely on a much faster timescale.

This would not be good...

I once read a book (Signalz, by F. Paul Wilson), where someone got transmitted power working, and it was part of ushering in eldritch dimension-dwellers. In that book, Tesla was part of some kind of dark wizard cabal.

Don’t remember, exactly. It was a while ago.

> would that accidentally slow the Earth's rotation

No. Incidentally :)