104 points by qnleigh 1 day ago | 30 comments
Panda_ 1 day ago
sroussey 1 day ago
The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.
kurthr 1 day ago
And don't forget the tides, both solar and lunar.

I'm sure a large enough mirror and photocell could get power out of the aurora borealis.

An argument that the magnetic field in a location remains completely constant as the earth rotates seems bizarre, but so does the idea that it's large enough to economically extract power.

kadoban 1 day ago
Are the tides caused by Earth's rotation? My understanding is they're not.

I know they're a bit of an inter-related system, but I thought if anything tides mess with rotation (eventually causing tidal lock), not so much the other way around.

How big are the solar tides? Never really considered that tbh. Looked it up, they're about half the size of the Lunar ones? Wild.

vikingerik 1 day ago
Thermodynamically speaking, the energy in tides does come from Earth's rotation.

The moon raises a bulge in Earth's crust and ocean. Earth's rotation carries that bulge ahead of the Moon's position. The bulge pulls the Moon forward (raising it to a higher orbit), while the Moon pulls the bulge backward (slowing Earth's rotation.)

Once Earth's rotation slows enough, tidal lock is reached. Then the tidal bulge stays in a single place always pointed at the relatively non-moving overhead Moon, and there is no motion to extract energy from.

bmm6o 1 day ago
The short answer is that there would still be tides without rotation, but with a period based on the lunar cycle. We have daily tidal effects, the moon can't do that by itself.
kadoban 1 day ago
Ah I see, that makes sense. Thanks.
thaumasiotes 1 day ago
The mental model I was presented with is that the ocean bulges toward (and, on the other side of the earth, away from) the moon, and the earth spins within the ocean. If you take a perspective that is fixed to a particular point on the earth, you'll see the tides constantly moving past, but that's an illusion just like the rising and setting of the sun. They're both really the rotation of the earth.
bmm6o 1 day ago
Also relevant is that the oceanic bulge is along the elliptic, but the earth's axis of rotation is tilted. So the effect can vary by latitude.
peterashford 1 day ago
Wind power is mostly due to solar energy. Earth's rotation contributes a very small amount and even that smaller effect is more located in the upper atmosphere where we don't collect wind power versus solar caused pressure gradients
rokkamokka 1 day ago
While true, if the earth stopped rotating the sun would also stop being "evenly" distributed around the globe, which would affect wind patterns a lot
aaron695 1 day ago
[dead]
fsckboy 1 day ago
a substantial amount of wind is also caused by (differential) solar heating: that's why wind doesn't only go in one direction

if you've ever spent time at the seashore, the wind comes in off the sea during the day (because of rising thermals on the land side) and blows back offshore at night (because the land cools and the sea is now warmer) that time in between the air is dead-still, and that's when the swarms of gnats can find you.

veqq 1 day ago
But the earth's rotation makes the solar heating _differential_
triceratops 1 day ago
If the earth didn't rotate the differential would be permanent...and permanently in one direction
babyent 1 day ago
Is it possible to speed up the wind?
jcgrillo 1 day ago
Yes that's how airplanes work
_dain_ 1 day ago
Yes, run power to wind turbines to use them as giant fans
righthand 1 day ago
Sure, cause constant heating and cooling and loop it.
timewizard 1 day ago
> It’s why the jet stream only goes one direction

Yet local winds blow in almost every direction. So to access that energy you'd need a structure 5 miles tall.

thayne 1 day ago
Or a balloon or kite five miles up.
IncreasePosts 1 day ago
Isn't that more of the sun+rotation?
cma 1 day ago
Foucault's pendulum also orbits in one way, but is that generating more power than put into it by starting it off?
bhk 1 day ago
None of the power comes from the Earth's rotation. Angular momentum is conserved in a closed system.
thayne 1 day ago
But it isn't a closed system. Tides transfer angular momentum from earth's rotation to the moon's orbit.
bhk 1 day ago
I was responding to a claim about wind. Yes, we can extract energy from tidal forces.
dang 1 day ago
The paper is here: https://arxiv.org/abs/2503.15790

(via https://news.ycombinator.com/item?id=43520716, but we merged that thread hither)

ziofill 2 days ago
Wouldn't this eventually slow down Earth's rotation? The rotational kinetic energy of our planet is 1/5 M * R^2 * w^2 with (approximately) M = 6e34 kg, R = 6.3e6m, w = 7.4e-5 rad/s, which gives approximately 5e36 joules. Yearly we need roughly 3e16 Wh. Yeah ok there's plenty. Woah! (also, I may be off by some orders of magnitude)
MathMonkeyMan 1 day ago
This is addressed in the last paragraph of the article:

> Even if it works, the method will not generate energy from thin air. It would tap Earth’s kinetic energy and, in doing so, cause the planet’s spinning to slow over time — although only slightly. If the technique provided all of Earth’s electricity needs, which was around 11 trillion watts in 2022, this would slow the planet’s spin by 7 milliseconds over the next century, the authors calculate. This is similar to the change in speed caused by natural phenomena such as the Moon’s pull and changing dynamics inside the planet’s core.

aeternum 1 day ago
Isn't friction from the atmosphere already slowing the planet's spin? Many weather effects like hurricanes ultimately derive their energy from a combination of the earth's rotation and thermal/uneven heating effects so I don't see why this is contentions.

Like most things, nature is already doing it and has been for millions of years.

mr_mitm 1 day ago
No, that's not possible due to conservation of angular momentum. Only tidal effects can transfer some of it to the sun.
aeternum 1 day ago
Why would angular momentum be conserved? Rotation within an atmosphere should cause friction would should convert angular momentum into thermal loss.

Interestingly, it looks like the upper atmosphere generally rotates faster than the planet, so it could be that the opposite effect actually dominates. IE the uneven heating causes a atmospheric bulge that actually pushes the atmosphere around slightly faster than the planet rotates, thereby slightly contributing to planetary angular momentum.

mr_mitm 1 day ago
Because the system exhibits rotational symmetry. It follows from Noether's theorem that angular momentum is conserved. Only when you include the interactions with other stellar bodies you lose the symmetry and you have an opportunity to shed angular momentum.
ziofill 1 day ago
Energy conservation and momentum conservation are different
Jensson 1 day ago
Tidal effects mostly transfers it to the moon, the sun has almost no tidal effects.
MathMonkeyMan 1 day ago
Tidal effects from the sun are about 46% as strong as those from the moon.

<https://oceanservice.noaa.gov/education/tutorial_tides/tides...>

mmooss 1 day ago
How much velocity loss would be needed for an impact on the environment, or on some humans someplace?
api 1 day ago
> which was around 11 trillion watts in 2022, this would slow the planet’s spin by 7 milliseconds over the next century, the authors calculate.

Really puts how small we are on a cosmic scale into perspective.

If we did it for a million years at current energy use scale it would shorten our day by about 1.1 seconds.

OccamsMirror 1 day ago
Wouldn't it extend our day?
api 1 day ago
Yes. Had it backwards.
thayne 1 day ago
Where does the angular momentum go?
1 day ago
ForHackernews 1 day ago
It's kind of insane how much energy is involved in big masses of rock flying around in space.
DriverDaily 1 day ago
Can we put energy in to speed it up?

That way a day can be 24 hours exactly instead of 23 hours, 56 minutes, 4 seconds, etc...

1 day ago
incognito124 1 day ago
I mean, solar day is 24h, it's the sidereal day that's 23.9344696h
Detrytus 1 day ago
Don’t follow your logic: if the day is currently shorter than 24 hours we need to slow the Earth rotation down, not speed it up.
frozencooler 1 day ago
Doesn’t driving west to east on a highway slow down the Earth’s rotation, via the power transferred into the ground?
rocqua 1 day ago
It's actually driving north south that changes the rotation speed. Because your 'real' speed gets higher as you get closer to the equator, you 'steal' momentum from the earth as you get closer to the equator.

Its effectively the same principle as a figure skater pulling in their arms when spinning, to spin faster.

logifail 1 day ago
Reminds me of a glorious question from undergraduate physics:

Calculate the change in the length of the Earth's day if the UK were to switch to vehicles driving on the right-hand side of the road rather than the left..

antod 1 day ago
Is that due to all the roundabouts switching direction relative to the Coriolis effect? Hence the relevance of the UK?

Presumably without roundabouts it's all random directions and balanced?

Or am I barking up the wrong tree?

logifail 50 minutes ago
It was indeed all about the roundabouts. I forget the details but I do know it took us quite a while to get there(!)

Those tutorials filled me with dread at the time, but with hindsight they were - how can I put this - a fairly formative experience.

Watching your tutor use paper and pencil - and estimation - to calculate something like that was actually quite inspiring. That was, once it stopped being terrifying.

amarant 1 day ago
Yes, but that energy is returned when you break
danillonunes 1 day ago
Things get interesting when you reverse.
thayne 1 day ago
Then when you stop the angular momentum of your car is transferred back to the earth.
BurningFrog 1 day ago
Only while you're driving.
Retric 2 days ago
0.44 picowatts = 4.4e-13 watts so not in a detectable fashion before the sun consumes the earth billions of years from now.
ziofill 2 days ago
Well, the watts that come out of the rotational energy must match the ones we need, for energy conservation.
Retric 2 days ago
Sure, but there’s no “eventually” it happens instantly.

The only way you’ll care about what happens eventually is if you’re concerned about some detectable result. Meanwhile individual rocket launches to Mars extract like 10^18+ times as much energy as this will over it’s lifespan and those still aren’t detectable.

golol 1 day ago
Where does the angular momentum go?
fsckboy 1 day ago
it's the angular momentum that gets transferred to the earth's spin, and all the other numbers, energy, power, are simply how the books are balanced. GP should have asked the question in terms of momentum in the first place.

with energy, you need to consider friction, losses, thermodynamics 3rd law, but with momentum it's pure.

teamonkey 1 day ago
Torque is applied, the paper mentions a magnetic braking effect.
foota 1 day ago
The IERS will never stand for this!
themaninthedark 1 day ago
watersb 1 day ago
Ideally enjoyed these. Can't find them as ebooks.

The first one was where I first encountered the idea of the "One Electron Universe":

https://en.m.wikipedia.org/wiki/One-electron_universe

A major plot point of these books is an alien technology that enables teleportation by somehow tapping into the Earth's angular momentum.

jaggederest 1 day ago
Eric Nylund's books are uniformly excellent, even (perhaps surprisingly) the Halo tie-ins
genewitch 1 day ago
Never heard of him
genewitch 1 day ago
> The novel follows Jack Potter, a computer cryptographer tenured at the fictional Academe of Pure and Applied Sciences in Santa Sierra, California (a city assembled from the ruins of San Francisco.) The story details Jack's first encounter with an alien calling himself Wheeler who apparently wishes to trade information with humanity.

> Accompanied (for a while) by "gene witch" Zero al Qaseem and data paleontologist Isabel Mirabeau, Jack establishes a corporation based around one of the technologies he was traded by Wheeler, but soon finds that there may be more to his dealings with the alien than he bargained for. Traitorous alliances, deceitful propaganda, and shady business practices are frequent elements of the novel.

> "gene witch"

genewitch 1 day ago
"Decent"
pavel_lishin 1 day ago
I thoroughly enjoyed them! I think I have both in paperback, though as a teenager, I managed to read them out of order.
yhager 1 day ago
By quoting the word "Decent" you mean it is actually excellent, or is it actually poor?
genewitch 1 day ago
my handle, gene witch, is literally from the book(s) being discussed. They're real good books.
vessenes 2 days ago
This is really cool. Question for EEs / Material Scientists reading the paper - they mention you could shrink the cylinders and get the same voltage provided a "suitable material" could be found. Any back of the envelope or explanation of materials needed to make these cylinders say 1/1000th their current size? That'd be an extremely useful amount of energy when put into say a 1000x parallel array.

It seems hard to imagine that this kind of shrink-down could go on forever, but on the other hand, the earth is just sort of hurtling us around with great energy while it rotates.

LegionMammal978 1 day ago
It would be interesting if this works. Last time people were hyping up a tiny effect with big ramifications that can only exist due to a subtle 'loophole', it was the EmDrive stuff that turned out to be driven by measurement errors. But I'm no expert in electrostatics.
api 1 day ago
I was about 99.99999% sure that one was bogus because it was violating bedrock conservation laws. I'm not sure that this does. AFAIK there is no conservation law that says a spinning mass can't extract power from that.

Still... it would have been hilarious of the EmDrive had worked.

"Well, they've progressed! Last time we checked in on the third planet in this star system its inhabitants were still using warp drives to heat food. They appear to have realized this."

Certhas 1 day ago
For the EmDrive it also was that the claimed theoretical mechanism was mathematically impossible, because it was based on equations that (like all known equations and everything ever observed) satisfy the conservation laws.

That's a good question actually. Supposedly this is extracting energy from the rotational kinetic energy of the earth. I haven't looked at the paper but you'd need to worry about conservation of angular momentum here.

Given that the cited physicists didn't dismiss this out of hand I assume this is accounted for somewhere...

1 day ago
qnleigh 1 day ago
Well conservation of energy says you can't extract energy out of nowhere. In the paper they claim that the extracted energy comes at the price of slowing down Earth's rotation. But then this seems to violate conservation of angular momentum... Maybe it depletes Earth's magnetic field instead?
sitharus 1 day ago
Conservation of angular momentum doesn’t prohibit reducing angular momentum by extracting energy, in this case the angular momentum is converted to electricity.
codethief 1 day ago
You can't just trade (angular) momentum for energy or vice versa, those are independent conservation laws.
1970-01-01 1 day ago
A bad question, as it has been doing that literally (rotationally) since before life started. This power is busy generating the magnetosphere. We would not be enjoying our nice oxygen atmosphere and would be as dead as Mars if Earth's rotation wasn't also powering a dynamo.
mr_mitm 1 day ago
It doesn't take any energy to maintain a static magnetic field though.
1 day ago
pfdietz 1 day ago
The currents that produce the magnetic field are flowing in liquid metal with nonzero resistivity.
jagger27 1 day ago
Earth's magnetic field isn't static, though.
mr_mitm 1 day ago
Negligibly so. The Sun delivers more energy to Earth in about 5 seconds than the magnetic field loses in 1,000 years.
timewizard 1 day ago
The magnetic field is coherent. The energy from the Sun is not.
fallingknife 1 day ago
Earth's rotation is also generating the power that is moving the Moon's orbit slowly away from Earth. There will be no more total solar eclipses in 600 million years because of this.
ChrisNorstrom 2 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?

ChuckMcM 2 days ago
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.

fpoling 2 days ago
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.

whatshisface 2 days ago
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]."

ngruhn 2 days ago
fast forward a hundert years and there is a massive culture war between the "rotation slowdown deniers" and people religiously buying "rotation friendly" products.
marshray 2 days ago
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.

6510 2 days ago
I'm not saying that is why we left Mars.
aeve890 2 days ago
Yeah, after making an oopsie with a runaway greenhouse effect in Venus. All this has happened before and it will happen again.
amarant 1 day ago
Ah yes, the Battlestar Galactica theory of life's origins on earth
fallingknife 1 day ago
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.
nopelynopington 2 days ago
I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?
padjo 2 days ago
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.
bee_rider 1 day ago
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?

nprateem 2 days ago
If a politician talks in front of a wind turbine, does it make a sound?
modeless 2 days ago
Alternatively, we could speed up the Earth! Let's get rid of those pesky leap seconds!
chrisjj 1 day ago
> would that accidentally slow the Earth's rotation

No. Incidentally :)

foxglacier 2 days ago
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.
FilosofumRex 2 days ago
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.

qnleigh 2 days ago
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...

fpoling 2 days ago
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.

qnleigh 1 day ago
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...

2 days ago
ChrisMarshallNY 2 days ago
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.

j45 1 day ago
Not stupid at all, especially if only one part of physics exists and not quantum physics.
threeseed 2 days ago
Current = 25.4 ± 1.5 nA, Voltage = 17.3 ± 1.5 µV.

Making total power for the 30cm shell = 0.44 picowatts.

MichaelRo 2 days ago
[flagged]
serm56 2 days ago
I don't see a problem with the LLM answer. The field near an FM station can reach 100mV or more. The maximum safe exposure levels for general public at 100MHz is 30V/m according to standards.
rcxdude 1 day ago
It's easy to lose a sense of scale in a field which usually works in logarithmic scales. Signals can easily vary by more than 40dB, and it's easy to forget that's a factor of 100 already, and another 40-60dB is not crazy in edge cases. (OTOH ~100uV is a much better estimate of what you'll be seeing from a 'good' FM radio signal)
userbinator 2 days ago
The part about FM sounds like BS, but much more than 1V at the antenna is definitely possible if you're close to an AM station, enough to cause unintentional receivers to emit sounds.
MichaelRo 2 days ago
Well, I'm expecting an average case, not "playing AM radio with grass", because in the vast majority of the cases, antennas won't be situated within a few meters of the radio tower:

https://www.youtube.com/watch?v=b9UO9tn4MpI

1 day ago
cedws 2 days ago
Still more net energy than fusion reactors have ever produced.
Retric 2 days ago
No, it took far more electricity to make than it produces over any conceivable lifetime.
number6 2 days ago
That's untrue
Kerbonut 2 days ago
I had an idea somewhat related to this where we use the solar winds as a sort of road and the earth's magnetic field as a sort of rotor to convert kinetic energy from the sun into electricity.
BurningFrog 1 day ago
This kinda sorta how auroras/northern lights work.
evan_ 1 day ago
Sounds like solar power with extra steps
2 days ago
deadbabe 1 day ago
Suggest a hard sci-fi story where humans abuse this so much the Earth basically stops rotating.
Rygian 1 day ago
I've already read one where some weird alien ants hollow out the earth to make it spin faster, and take advantage of the increase in speed to generate power somehow (maybe by building a geostationary conductive belt around the planet, that acts as the "stator"?)
MaxikCZ 9 hours ago
Wouldnt hollowing the earth not change its rotation speed? And if the hollowed material would be deposited on surface, wouldnt the speed actually decrease?
Hyperboreanal 1 day ago
Saying what book you're talking about is kind of a spoiler now for anyone that happens to be reading its series. Are there spoiler tags on HN? <SPOILER> The Long Utopia, book 4/5 of the Long Earth series by Pratchett and Baxter. </SPOILER> The series has very meh characters/dialogue, excellent ideas and sense of nearly possibility-unlimited discovery that's executed very well, highly recommend if that's your cup of tea. Ended up skipping all the flashback chapters near the end of the series though, that felt like a load of filler
pavel_lishin 1 day ago
I was wildly disappointed in that series. A great premise that fizzled out about 3/4ths of the way through the first book. I powered through, and started the second, and gave up maybe five chapters in.

If the concept of world-hopping intrigues you, Charles Stross's "Merchant Princes" series does it better.

whutsurnaym 23 hours ago
I'm really glad to see this wasn't just my experience.

I absolutely loved the premise of the first book. Every time I think about it I get the same kind of excitement I feel when I come up with the perfect idea for a D&D campaign.

But the second book gathers dust on my shelf, and no matter how many times I think "I should get back into these!" I just can't. The first book ended in a fizzle and the second completely failed to keep my attention.

I'll take a look at Merchant Princes and see if that's more to my liking!

bigmadshoe 1 day ago
Reminiscent of 'The Gods Themselves' by Isaac Asimov
hammock 1 day ago
Eric Nylund’s Jack Potter series. See an earlier comment
owenpalmer 1 day ago
Imagine trying to speed up the Earth's rotation!
throwaway48476 2 days ago
Would this reduce the magnetic field stength allowing more cosmic rays to reach the surface.
xattt 2 days ago
I, for one, look forward to ground-level auroras.
asdefghyk 1 day ago
I ask, ..... Would Extracting power would have the side effect of slowing down the earths rotation ?
npodbielski 1 day ago
I wonder how many wats of power we would be able to generate before earth slows down for i.e. 1 second longer day.
af78 1 day ago
I'm taking figures from https://en.wikipedia.org/wiki/Rotational_energy

Moment of inertia of the Earth: I=8.04e37

Angular velocity, with sidereal rotation period of 23.93 hours: ω0=2π/(23.93 × 3600)

Angular velocity, with sidereal rotation period of 23.93 hours plus one second: ω1=2π/(23.93 × 3600 + 1)

Rotational energy difference: .5 × I × ω0 ** 2 - .5 × I × ω1 ** 2 ≈ 4.96e+24 J

For comparison, according to https://ourworldindata.org/energy-production-consumption the total amount of energy consumed on Earth in 2023 was 180E3 TWh i.e. 6.48e+20 J

Slowing down the Earth by one second would be equivalent to 7661 times this amount.

adalacelove 1 day ago
According to Wikipedia [1] we consume 9717 Mtoe or equivalently 408 TJ (per year, although it is not explictely stated, which I find annoying).

The earth moment of inertia is about I=8e37 kg m2 [2]

The energy extracted by a slowdown of angular speed from wa to wb would be 1/2 I(wa2-wb2).

Approx wa=2pi/86400 and wb=2pi/86401. Energy extracted: 4.9e24J=4.9e12TJ.

We would have energy for about 12 billion years.

If I double check with Kagi's assistant with Claude 3.7 (I'm in my phone and I could easily have made an error) it starts with my exact reasoning and figures but messes up final numbers (so close!!!) to give a total of 40 billion years, which nevertheless is the correct order of magnitude.

[1] https://en.m.wikipedia.org/wiki/World_energy_supply_and_cons...

[2] https://scienceworld.wolfram.com/physics/MomentofInertiaEart...

IshKebab 1 day ago
That's easy to work out but I can tell you not it's going to be more than we will ever use.
Beijinger 1 day ago
You have no idea, what amount of energy we will be able to use the long run.
ada1981 1 day ago
220, 221, whatever it takes.
tiagod 1 day ago
We have potentially millions or billions of years of history in front of us. If we find a way and a motive to have self-sustaining communities outside this planet, and considering our own history, it looks at least plausible that we will continue spreading, after dominating an entire planet against the brutal odds of natural selection, which we basically hacked with our consciousness to reach this state.

Keep in mind that energy is not electricity. When a rocket is burning huge amounts of fuel to reach orbit, that's energy we're using, a lot of it.

janpot 1 day ago
"640K ought to be enough for anybody"
barbazoo 1 day ago
Typical human response
mmooss 1 day ago
bmacho 1 day ago
Imagine a massive planet spinning in empty vacuum. Can the inhabitants slow down their planet, and generate electricity?

I suspect that they can generate electricity with angular momentum with it, that can be only used to do work with the equivalent angular momentum.

drewolbrich 1 day ago
The Moon's tidal forces are already slowing down the rotation period of the Earth, which was apparently only 5 hours long about 4.5 billion years ago.
qnleigh 1 day ago
Yes, but when you consider the combined system of the earth and everything that affects its orbit, angular momentum is conserved.
randomNumber7 1 day ago
Maybe if we use the moon (and ideally get 2 more) we can build a giant generator.
mentalgear 1 day ago
how practical is this, eg how big would a device have to be to produce any meaningful energy?
miller_joe 1 day ago
Strong flashbacks of Southland Tales (2006). Underrated movie with this as a core premise
exabrial 1 day ago
They made a really terrible movie about this.

Spoiler: they nuked a bunch of stuff.

1 day ago
K0balt 1 day ago
I mean… yes, the earth’s rotation can easily generate power. All you need is a gyroscope spinning in a vacuum on frictionless supports to make that work. Of course it’s only 1 revolution per day, but still, if it’s big enough…

It’s hard to beat solar though.there are very few technologies that stack up better financially than “just buy more panels” in most of the populated world. Batteries are really the key.

signa11 1 day ago
but _why_ does the earth rotate ?
dabbz 1 day ago
Futurama already did this episode though? It caused the Earth to stop spinning.
shadowgovt 1 day ago
I have no idea on the claims here, but there is one method for extracting work from the magnetic field that I very much enjoy.

A magnetorquer is an attitude control system on a satellite that runs on electricity. Run the electricity through an electromagnet. The magnet couples to Earth's magnetic field and turns the satellite, like a compass needle.

aurizon 1 day ago
We could use this, by adding power, to fine tune the day to eliminate leap years...;)
ada1981 1 day ago
Interesting. Yes could we put power into a similar system and accelerate the rotation?
aurizon 1 day ago
turn fast enough = we can all fly... while we wear armor like a turtle...
nyc111 1 day ago
Why does the earth have a magnetic field?
qnleigh 1 day ago
This is a great question, and it's not as simple many comments here make it seem to be. This Veritasium video has a great explanation (and an enormous ball of molten sodium).
frozencooler 1 day ago
The earths rotation creates it. Or was this rhetorical.
nyc111 1 day ago
No, it was a serious question. Does anything that rotates create a magnetic field even if it is not an electrical material?
cyphax 1 day ago
In case of Earth, Wikipedia describes [1] it as being "[..] generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core". This makes Earth a geodynamo [2]. (The aforementioned Wikipedia page is actually really long and detailed, a lot more than I would have thought)

[1] https://en.wikipedia.org/wiki/Earth%27s_magnetic_field [2] https://en.wikipedia.org/wiki/Dynamo_theory

pmontra 1 day ago
The iron core but there are many open questions https://news.mit.edu/2020/origins-earth-magnetic-field-myste...
beeforpork 1 day ago
Basically: moving electric charge = magnetic field. It's equivalent, that's why it's called electromagnetism: it's one and the same force.

The Earth rotates, liquid iron (inside Earth) flows => a current flows in the iron => there is a magnetic field.

fallingknife 1 day ago
No, otherwise Mars would have a magnetic field just like Earth.
j45 1 day ago
The topic is very interesting. The spin of science, is not.

Side story: What's to argue over?

There's no shortage of scientists with breakthroughs who are pretty much abused by their profession and colleagues, sometimes for decades, simply for exploring possibilities and capabilities that are more than safe and conservative and incremental.

Either it's true, or it's not, and it can be explored, or not.

Division breeds who is right and wrong, not what is right or wrong.

Maybe it can be proven, maybe not. Maybe it's true and we don't understand it yet. The naysayers might just not be wanting someone else to succeed.

vessenes 1 day ago
I didn't downvote, but since you asked for feedback, I'd venture a guess that most who did think your post doesn't add anything to the discussion. It's vague, not topical to the paper and isn't falsifiable.

A related topic, the emDrive, which had plenty of controversy, is something readers of this thread want to talk about; the specifics are a better fit for this crowd than the meta questions, esp. when vaguely introduced.

j45 1 day ago
Happy to be downvoted over silent disagreement.

Even happier to get input and maybe learn.

ninetyninenine 2 days ago
Wouldn't this slowly slow the earths rotation down? Let's say everyone tried to build power plants using this.
mmooss 1 day ago
ziofill 2 days ago
Ah didn't see this comment and I asked the same. Yes, right? The energy has to come from somewhere...
EncomLab 1 day ago
It's incredible the lengths humanity is willing to go to avoid adopting nuclear energy - despite the US navy driving mobile reactors millions of miles over the last 70 years.
deepfriedchokes 1 day ago
The Navy isn’t constrained by economics. Nuclear doesn’t make sense economically compared to things like solar and batteries.
SecretDreams 1 day ago
> things like solar and batteries.

Magnets too - let's just go magnets everywhere.

Reality is solar isn't viable everywhere. And it's not optimal to put it in places where you use the sun to grow food.

We should follow a holistic approach.

* Wind where it's windy.

* Solar where it's sunny - ideally on buildings/away from farms.

* Hydro where possible.

* Nuclear where it makes sense, i.e. stable geography, low occurence of natural disasters, lots of land.

* Some natty gas plants for overflow - not saying commission new ones or prioritize natty, but it's sensible to utilize existing peaked plants.

I'm not a big fan of large scale battery storage solutions, but they can work sometimes. I think they're more sensible for residential/commercial use and, when paired with solar, can really help add robustness to the grid. But, for mega energy storage, I think hydro based solutions are more sensible.

Certhas 1 day ago
What do you base all these claims on? Plenty of papers show Solar + wind + storage is viable practically everywhere.

Also there is a ton of research on planning energy systems and what technology mixes make sense. This stuff has to be economical. Energy costs are measured in percentage of GDP. Simply liking nuclear doesn't make it viable. Especially in a world with PV meaning you can't sell energy during the day.

There really is only one macro fact that will shape the energy system of the future: The price of PV modules is now effectively zero in rich countries. Everything else has to be judged by how well it complements/makes use of free energy during daylight hours. The geopolitical implications of this haven't even begun to be explored.

SecretDreams 1 day ago
Energy independence and a mix of technologies isn't just about cost. It's about redundancy and how you're positioning yourself to handle various unexpected events.

You don't want a state primarily on solar if you get a super cell darkening the sky for a week.

You want a mix of renewables, but you don't strictly want to rely on the food graces of mother nature at all times.

Boiling things down to just price is a very simplistic view.

Certhas 1 day ago
You seem to think this contradicts my statement somehow?

Obviously you want a tech mix, and obviously anyone working in the field is taking the dunkelflaute or other extreme events very seriously. That's where storage comes in, and that's where the biggest unknowns and needs for future development are (e.g. is seasonal H2 storage really feasible). But to pretend like nuclear can magically become cheaper through technical breakthroughs, while storage is an unsolvable problem is disingenuous.

It's also disingenuous to suggest that random fluctuations in weather are somehow a unique problem. Sudden unscheduled maintenance can take down nuclear plants as well. As can the weather: Nuclear power plants require cooling and can be shut down due to weather and climatic conditions, too [1].

[1] https://www.nature.com/articles/s41560-021-00849-y

> I analyse climate-linked outages in nuclear power plants over the past three decades. My assessment shows that the average frequency of climate-induced disruptions has dramatically increased from 0.2 outage per reactor-year in the 1990s to 1.5 in the past decade. Based on the projections for adopted climate scenarios, the average annual energy loss of the global nuclear fleet is estimated to range between 0.8% and 1.4% in the mid-term (2046–2065) and 1.4% and 2.4% in the long term (2081–2100).

SecretDreams 1 day ago
> But to pretend like nuclear can magically become cheaper through technical breakthroughs, while storage is an unsolvable problem is disingenuous.

I didn't say storage was not solvable and I even gave a better storage solution than your silly "batteries" example.

> Based on the projections for adopted climate scenarios, the average annual energy loss of the global nuclear fleet is estimated to range between 0.8% and 1.4% in the mid-term (2046–2065) and 1.4% and 2.4% in the long term (2081–2100).

From your own linked article - do you think this energy loss is even close to comparable to solar for similar conditions? You've linked an article but don't seem to understand the point they're looking to make.

Anywho, I don't think you're looking to argue in good faith and seem to have an anti-nuclear agenda, despite talking about an "energy mix". Save your policies for whatever echo chamber they were derived from, thanks.

Certhas 12 hours ago
What silly batteries example?

If seasonal storage is solvable, solar + wind is not unreliable.

And no, I don't have an anti nuclear agenda. But I know the energy system models and the results, and just how difficult integrating nuclear into the mix is.

https://nworbmot.org/blog/burden-of-proof.html

Finally, I know exactly what the paper says but maybe you don't: the problem with Dunkelflaute events is correlation. If it's cloudy somewhere and the sun is shining elsewhere, then no problem. These problematic conditions for nuclear are the same: large scale spatial correlated.

SecretDreams 5 hours ago
> Finally, I know exactly what the paper says but maybe you don't: the problem with Dunkelflaute events is correlation. If it's cloudy somewhere and the sun is shining elsewhere, then no problem. These problematic conditions for nuclear are the same: large scale spatial correlated.

Great. We'll just pipe over the energy from Arizona to Michigan, should be fine.

Large scale weather events drop nuclear by 1% long term. What percentage do they do for solar?

I'm not even a solar hater - I love solar... On residential and commercial rooftops. Or in sunny and void of life areas.

I love a mix. And nuclear integrates just fine into the mix. Look at a province like Ontario where 60% of the energy is derived from hydro and nuclear. An incredible and robust baseline power with low downtime and, correspondingly, cheap power for all of the residents of that province.

Even more energy from solar and wind too, with some natty gas as top off. Seems to work just fine for them - and with long winters and plenty of cloudy days, solar as a big component of their energy mix seems pretty silly to push for. You can see the mix live below.

https://live.gridwatch.ca/home-page.html

It was 53% nuclear and 28% hydro at the time of me posting this. 16% natty, 4% wind, and 0.1% solar. The solar was good for 21 MW and the nuclear was good for 9600 MW for perspective. Their nuclear has been safe as hell and has run flawlessly for I think 30+ years.

mike_hearn 1 day ago
The (subsidized, market dumped) price of cells may be low at the moment, but the price of storage, land and artificial inertia isn't.

You can absolutely sell non-PV power during the day. Big power consumers sign contracts for predictable and reliable supply.

Certhas 1 day ago
PV is not heavily subsidized compared to other energy carriers, and the learning rate has been extremely consistent for a long time.

LCOE takes some of the system costs into account, but it's of course true.

And your second sentence is not how energy markets actually work. Of course I make a contract for reliable supply, but I don't contract with an individual power plant. I contract with an energy company and that buys from the cheapest supplier mix (aka merit order).

The long term contracts for base load run for years, but those, too will eventually have to adpat to the reality of abundant cheap daylight energy.

My main point with PV isn't about the system we have right now. It's that we are in the first days of a new system structured around the new technological reality that only recently emerged. Until very recently nobody, even the optimists, expected PV to get that cheap that fast. It will take decades for the repercussions of this phase transition to shake out. The issue is, due to climate change we don't have decades.

djmips 1 day ago
Why doesn't Geothermal make your list?
SecretDreams 1 day ago
Great question! Mostly, because I forgot. Second, it's pretty expensive for the gains you get - I'd rather favour it for use in heat pumps; but it makes sense for some regions.
DonHopkins 1 day ago
Back when all my precious data was on floppy disk and hard drives, I HATED magnets. Now I am more ambivalent.
Nifty3929 1 day ago
I haven't seen any data that backs that up based on general principals. Most of the cost is in artificially-imposed operational requirements - however well founded.

Also, remember that nuclear, unlike solar, has a lot of room for improvement still, both in how it's done, and how it's regulated. Solar has already been tremendously optimized, while nuclear has not.

The cost argument seems to be advances by the same people who impose or support the additional operational requirements, and who also just have a philosophical aversion to nuclear power.

There are hundreds of nuclear power plants already in operation, many decades old. There have been only a very small number of minor accidents (3 come to mind: Chernobyl, Three mile island and Fukushima), in which only a few dozen people were killed. Nuclear, even using old technology, has proven to be far safer and better for the environment than any scalable alternative, including solar. New designs are even safer.

peer2pay 1 day ago
Calling Chernobyl a minor accident is insane. We are lucky it wasn’t worse but even then most of Europes forests are still polluted from the fallout. People directly killed during the incident is not a great indicator of incident severity when we're talking about environmental pollutants.

Nobody died from installing asbestos insulation yet here we are.

rsynnott 1 day ago
> Most of the cost is in artificially-imposed operational requirements

Indeed. Once there was a wonderfully efficient, economical nuclear reactor design, better thermal efficiency than PWRs, could be refueled during operation, considerably cheaper to build… However, nobody is THAT keen to build more Chernobyls.

(The RBMK design really was quite impressive, provided you weren’t too concerned about, well, safety.)

The economics of nuclear energy are difficult, today. So much of the cost is upfront that getting the investment is problematic; unless you have a guaranteed price per kWh, it really is a huge gamble.

Certhas 1 day ago
All I see is people with an aversion to solar and wind, that champion nuclear for purely ideological reasons. The aversion seems to be mostly driven by the fact that solar and wind were first championed by eco hippies, and some people seem to find it hard to bear that the eco hippies were right in this case.

Nuclear has had tremendously more cumulative R+D spend than solar and wind. The notion that it's less optimized is absurd. And this is where your bias shows: we have empirically proven persistent scaling laws for solar and batteries. We also have seen nuclear become ever more expensive over time. Yet you claim that these trends will come to an end, and in the case of Nuclear will suddenly completely reverse themselves without any evidence.

To also bemoan the burdensome operational requirements while championing it's safety record is internally inconsistent.

And in the end no one has so far actually built a place where you could store the nuclear waste long term, and the costs of long term storage are not even fully factored into the costs of today's nuclear power plants.

Nifty3929 1 day ago
"All I see is people with..." - Maybe some do, but not me. I think solar is great, and wind too. I have solar panels on my roof that cover most of my family's usage. Geo would be awesome, and hydro can be great.

I'm all for doing more, and improving our lot incrementally over time. Let's focus on doing more wherever we can.

Why is nuclear getting more expensive over time? Are we forgetting how to produce it or something? Actually we've been finding more efficient and safer ways to produce nuclear for decades, but we impose - as I said - artificial burdens that make it more expensive, or simply don't allow it at all. At least in the US.

The operational requirements DON'T make it more safe though, they just add cost. Storing nuclear waste is also safe, easy and cheap - if we allow it to be so.

Certhas 11 hours ago
Seriously, that's good to hear. I really often encounter arguments that seem heavily ideology driven.

Do you have some sources for operational requirements not making things safer? And as far as I know there are plenty of fusion concepts in the lab, but very few that have actually been explored at the full reactor scale. If you have any pointers on recent developments in that direction I would also be curious to take a look.

But then I also have to ask why nuclear? Why not methanation (or hydrogen if storage becomes feasible) and gas power plants or some more sophisticated version of that? That has much better complementarity to solar. And it typically is preferred to nuclear by energy system models wherever seasonality is strong.

Also I haven't really seen any proposals discussing long term waste storage. Again do you have any sources that discuss this?

AtlasBarfed 1 day ago
Nuclear has had a century almost to hone its craft.

I'm a lftr fanboy, but nuclear had its time to optimize.

I can't believe you're calling Chernobyl "minor". Go take a vacation there if you disagree.

Anyway, nuclear is not cost competitive in the real world, imo it never will be with solid fuel, nor will it be safe. Certainly not with standards like yours.

timewizard 1 day ago
> The Navy isn’t constrained by economics.

In what way is it not? It has a budget and a mission. Economics are a huge part of their existence. Far more is spent on health care every year over the Navy.

mmooss 1 day ago
The US Navy has other, very high priorities to balance against cost - national security, global security, freedom, peace, trade, the lives of billions, the lives of its own personnel. The US military may the largest budget of any organization in the world.

At the same time, they invest in those mobile nuclear reactors only for specific needs: attack submarines, ballistic missile submarines, and aircraft supercarriers. They calculate that the benefit of effectively unlimited fuel supply is worth the cost for those ships. The submarines can stay submerged for months at a time and have extensive range, and the carriers can move through the ocean, displacing 100,000 tons of water, to anywhere on the globe without worrying about the logisitcs of the enormous amount of fossil fuel it would require.

qnleigh 1 day ago
I think it's more that the Navy isn't constrained by Nimby's and anti-nuclear lobbyists.
kjkjadksj 1 day ago
Why do we have to be constrained by economics unlike the navy? The state within the state has access to nuclear powered ships so it is just a question of widening that capability to the members of the state living outside the walls of the keep. Not a matter of establishing precedent or anything. That part is done and long proven. The federal government even has experience managing water and power for entire geographical regions today.
Rury 1 day ago
> The Navy isn’t constrained by economics

And solar less so than nuclear. Nuclear receives only ~1-3% of energy subsidies in the US [1].

[1] - https://en.wikipedia.org/wiki/Energy_subsidies_in_the_United...

grepfru_it 1 day ago
Solve the waste problem and you solve nuclear. Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!)

I used to have a neighbor who worked for the DOE, all of the viable solutions are blocked by people who don’t want it in their backyard. Can’t really move forward until that is solved..

cyberax 1 day ago
> Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!)

The correct solution: put it into dry casks and do nothing right now. Store it simple underground storage facilities or on the grounds of active nuclear power plants.

The casks are fine for the next 300 years, and during that time we can either:

1. Perfect the nuclear fusion, it will provide plenty of neutrons to transmute the waste.

2. Perfect fast fission reactors. See above.

3. Use some of the excess of too-cheap-to-meter green energy for accelerator-driven subcritical fission reactors.

4. Yep, use rockets to slowly launch the waste into space. We can already design a storage capsule that can survive re-entry.

In any case, we have literally hundreds of years to come up with a solution and there are many viable paths.

qnleigh 1 day ago
> use rockets to slowly launch the waste into space. We can already design a storage capsule that can survive re-entry.

Do you have a source in mind for this claim? Even if a capsule could survive reentry, surely it wouldn't survive impact.

cyberax 1 day ago
Yes. We're _already_ launching nuclear waste into space, in the form of RTGs with Pu-238. So there's been a lot of work towards making them passively safe, although the weight constraints for deep-space craft necessarily limit the amount of achievable safety.

> Even if a capsule could survive reentry, surely it wouldn't survive impact.

It'll be moving at a terminal velocity, and can be engineered to not fragment on impact.

For example, I remember reading about a proposal to alloy the nuclear waste elements with a carrier metal like iron or nickel, and then cover them in an ablative graphite shell.

maxerickson 1 day ago
The Pu-238 in Rtgs is produced for the purpose, it isn't isolated from waste.

Of course it is more or less equivalent when it comes to handling.

walleeee 1 day ago
Some MSRs can consume spent nuclear fuel, that's a 7th grade solution at least
AtlasBarfed 1 day ago
Lftr! Breeds burns almost all the fuel.i think the waste products it does make are shorter term.
Ylpertnodi 1 day ago
>Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!)

Could the waste be 'sent' into space? Bonus points for sending a certain human with it. Serious question, though.

rsynnott 1 day ago
This was one of the Soviet Union’s proposed use for Energia (a super-heavy launcher which flew precisely twice before the Soviet Union collapsed). In practice, there would be, ah, challenges; no launcher ever built is reliable enough that anyone would be particularly comfortable with _launching large amounts of high-level nuclear waste_ with it.
mschuster91 1 day ago
> Could the waste be 'sent' into space? Bonus points for sending a certain human with it. Serious question, though.

Would you want a RUD of nuclear waste in the atmosphere? That's the key thing with sending stuff to space, we are nowhere near close enough in terms of reliability and cost to what would be needed to send the stuff away.

bell-cot 1 day ago
By "space" do you mean low earth orbit - where the stuff will reenter the atmosphere within (say) a century? Or geosync orbit - where it'll stay up there forever-ish...but ain't actually gone? Or actually gone, like (say) Mars?

IIR, the current rock-bottom (Falcon 9) launch prices are something like $1,000/lbs. to low earth orbit, $2,500/lbs. to geosync, and $6,500/lbs. to Venus.

A quick Google says the US has about 88,000 tons of radioactive waste. So - 88,000 tons = 176,000,000 lbs. = $176,000,000,000 just to put it in low earth orbit. And something like 4,600 Falcon 9 launches. (Some fraction of which would doubtless go badly wrong, spreading radioactive stuff all over the landscape.)

In short - it's a cool-sounding idea. But neither the numbers nor the politics are remotely near viable.

fallingknife 1 day ago
Burying the waste is an excellent solution. We are currently dealing with the much more dangerous problem of hydrocarbon combustion waste by releasing it into the atmosphere.
kjkjadksj 1 day ago
What problem with the waste? Reactors are working and generating power today for many thousands of americans. Whatever is being done with waste today seems to work well enough to continue reactor operations without any major headlines. Just seems to be a bit of cognitive dissonance here between what is claimed online and what we see today out in the field generating power.
pmontra 1 day ago
Many countries would have to buy nuclear fuel from other countries much like they do for gas and oil. On the other side very few countries can build their own solar panels so it seems the same sort of problem. However if you accept to depend from potential hostile countries at least solar panels don't do much harm when they fail and it takes very little effort to install the equivalent amount of power of a nuclear power plant. If we only could all get along and have a global power grid with always 12 hours of sunshine on it.
abdullahkhalids 1 day ago
Most country that can invest a few hundred million can build their own solar panels that will be significantly cheaper than existing and future fossil fuel prices. It's just those panels will be 2x+ the price of those produced in China. So can't compete in the free market.
bmacho 1 day ago
You can do solar energy with mirrors (the ancient Greeks were able to produce that) and steam turbine/stirling generator.
devmor 1 day ago
Until we solve the storage problem, the manufacture of batteries required to store solar power at night and during other low generation times is actively doing harm even without failing.

I don’t think this invalidates your point but I do think it is incredibly important to recognize that environmental harm done slowly over time is no less impactful than that done by a disaster.

fallingknife 1 day ago
Unfortunately the arrangement of the continents would require undersea transmission lines for this. Would be an interesting future where the Bering Strait is the most valuable real estate on Earth for the American-Euraisian grid connection. But more likely we would build fusion reactors or get over our nuclear phobia before building something like that.