Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.
> Have you done the calculation how much material is required for such an endeavor?
It's a tiny fraction of what's required for a proper Dyson sphere. And we know civilizations can afford those because we can no longer see their stars.
For anyone who's hung up on saving nickle, we could do a low budget Worldring² or even thriftier Shadow Squares®.
So why make the initial claim "And we know civilizations can afford those because we can no longer see their stars."? Is it humor or irony I'm missing?
It is especially big claim because there have been recent searches for Dyson Spheres and none of have been found. I think the Gaia spacecraft covered most of the visible half of the galaxy.
Dyson Spheres would be really obvious, emitting infrared radiation unlike normal stars.
Oh you are in for a treat. They don't fully finish in that book, for the conclusion you need high-octane Judas Unchained with the best inter- and then planetary chase scene. A great book with lovely twist in the end.
The flaw with your theory is Dyson Spheres don't hide the star. They convert visible light into infrared light. No energy conversion is perfect and always produces waste heat. Dyson Sphere basically looks like a really large star.
The infrared star stands out because it is different than normal stars.
> The flaw with your theory is Dyson Spheres don't hide the star. [follows with sound reasons]
These are really good points. I figured the flaw in my theory is we haven't had precision observation long enough for DS to get constructed. Also that if we noticed the disappearance of a star, that we'd attribute it to a DS and not some natural occluding object.
Closer to the star would only help if the star's size was similar to the death star. And if the death star was made larger then it wouldn't be mistaken for a small moon.
What do you mean it's unstable? You orbit the Lagrange point, right? Sure you might have to spend some fuel maintaining the orbit, but we have a bunch of spacecraft at Earth sun L2 doing that just fine (e.g. the Webb). Is L1 less stable than L2 for some reason?
That'd make for a good story setup: aliens park a shadeship (c) at L1 and wait. They block out most but not all of the sun. After some time (months? years?), conditions on Earth become unbearable, so earthlings have to mount an attack.
Kind of like the movie Sunshine, but with more believable physics.
Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disguise their motives for a while, claiming to be there to help counteract global warming. Warnings from a lone scientist would be ignored. Then, as things start getting too cold, their true purpose would become clear to all.
As an alternative - it could be the oil producing countries, not aliens - seeking shade earth to disrupt solar and wind energy, and return to oil dominance.
It's not solving if they can turn it back on, it's a subscription. The elite want renters, 'you will own nothing and be happy'.
It should give people pause that with all the push for more renewables in California and Germany, they now have among the most expensive electricity on Earth.
Shit, I think the US spent several times that per year, without even a good plan to pay it back. Does that mean the United States is irresponsible, or the amount is just so trivial they can't be bothered? Who cares, it's some other administration's problem.
Solving global warming, turning off the earth iceball machine when it's time? Easily worth $100 trillion. OP just has no supervillain potential.
"I demand the sum of... $1 million dollars!" -- Dr. Evil
And countries which use reliable sources of energy like nuclear would be unaffected. How curious...
Perhaps building unreliable energy infrastructure dependent on favorable climatic conditions is not the greatest idea. Especially if there's going to be major climate change. How's Germany doing again with all its solar lol.
This sounds more like something out of a Mad Max type universe rather than sci-fi. A world living off fossil fuels because daylight has been reduced to 10% of the normal duration or something like that.
> The aliens could disguise their motives for a while, claiming to be there to help counteract global warming.
Seemingly benevolent aliens just here to help us fix our mess, but ultimately just want to sneakily take our stuff, is fun trope. https://www.gateworld.net/sg1/s4/2010/
Another good story setup involving aliens: aliens pop by, tell us we have 25 years to "get our shit together, and the ambiguity here is deliberate, humans" on this planet, or we will be garbage collected.
Then they come back a year later: "I have bad news: the timeline has been accelerated, you now have 10 years".
The most unbelievable part of this would be that earth cooperates enough to organize an attack. Seems more likely countries will use the opportunity to attack each other. In the end, the aliens should win. A few straggling survivors might see the ships land on Earth to survey the conditions.
>The aliens could disguise their motives for a while, claiming to be there to help counteract global warming. Warnings from a lone scientist would be ignored.
Alternative, more physically feasible attack—-aliens take over the moon and begin pushing it closer, messing up tides/weather etc. Humans are forced to fight to take back the moon
Shifting the orbit of the moon is more believable? Than placing a mega structure at L1 (which despite being mega, would be orders of magnitude less mass than the moon)?
* How much mass could be positioned at L1 before changing the gravitational proposition of L1?
* How large an object could be positioned at L1 before it exceeded the practical bounds of L1?
* Presumably the object would reflect rather than absorb solar radiation. How would it deal with other solar ejecta?
Or maybe they showed up 200 years ago and thought: this is a very nice planet, except it's a bit too cold. What can we (compel the natives to) do to make it some 6 degrees warmer on average so that it is perfect for us? And the rest is history.
This is kind of the plot of Pacific Rim. The aliens originally invaded in prehistoric times, but then the Earth cooled and they had to retreat to their dimension. Humans then warmed it back up so they could restart the Kaiju invasion plans.
> Warnings from a lone scientist would be ignored.
A good movie plot, but I imagine in reality it would be obvious from the start that this would be a possibility and no scientists would be caught off-guard when the shade just didn't get removed. I can be almost certain as well that large factions of humans would "know" (believe, based on no facts) that is was happening all along and there would be incredible conflict across Earth as we figured out how to deal with this gentle attack, even before it was certain that is was an attack.
> even before it was certain that is was an attack.
If it was done without consent, then it is an attack, and it doesn't fu*cking matter whether it ends up causing physical harm (or even if the invaders genuinely thought they meant well).
Regardless of whether it ends up taking away somebody's sunlight forever, it's still robbing people of all their agency. That decision was never theirs to make.
This reminds me of the game "SPORE" in the last stage, you flew around in a spaceship conquering planets. The game had a balance problem, but while the space combat was difficult - it was rather easy to fly around a planet really quick "Terraforming". Remove the entire atmosphere, then add the atmosphere back and plant a colony.
As a bonus, the other aliens in the game didn't view destructive terraforming as equivalent to WMDs - you could do this without even declaring war.
That sounds like a great idea for a sci-fi novel, but before I steal and write it I thought I'd ask ChatGPT if it already exists, and it seems it does.
"The Forge of God" by Greg Bear
The Makers deploy a vast, self-replicating robotic spacecraft called the "Doomsday Rock" near Earth's sun. The purpose of this massive construct is to absorb energy from the sun, causing it to dim and ultimately leading to the freezing of Earth, thus rendering it uninhabitable.
Or you could just smack it with a really big rock. That nicely sterlizes the planet too, so you can reseed it with life from your planet after to make it more comfortable.
Honestly it's all kind of silly because distances are so vast. It makes little sense to travel to a distant star - much better to build space habitats in your own star system. And even if you were going to do that for some crazy reason, there's no shortage of uninhabited planets out there. There's no need to commit planetary genocide of an alien race. Also if you have that kind of tech level, space habitats make more sense than planets anyway. Finally if you seed distant star systems with your own species, you risk that species going to war with you later (see how that played out on Earth just across the oceans.)
I was thinking the deep freeze might be useful in preserving some potential food sources, assuming it happens quickly enough. But I agree sterilizing the planet provides some advantage as well.
You are correct, but it's capitalism and the adrenaline kick. We are culturally conditioned folk, and all scripts about alien invasions that end up in movies follow a completely implausible scenario. Most don't even bother any longer to give a reason for invasion. I would blame the writers of those scripts, but movies without violence don't give the adrenaline kick and don't sell well.
Here is an idea for any writers reading this who want to break the violence cycle: whenever you feel you need to have a character kill another in a gratuitously violent way, twist the plot so that they instead end up having steamy sex. The readers will get an intense hormone rush that way too.
Ahh yes famously American media like Squid Games and Alice in Borderland are so filled with gory violence I can barely handle it. And American movies are famous for having so few steamy sex scenes in them that people are not constantly rolling their eyes at the “sex sells” mantra to explain their frequency.
> a really big rock ... nicely sterlizes the planet
Have you seen Earth? We've been hit with a big rock, we've turned out atmosphere into poison, and had several other mass extinctions, none of which sterilized the Earth.
Unless you mean a Theia-level rock to turn the entire surface into lava, but you risk changing the mass, composition, and satellite system of the planet. At that point it's a different planet entirely, so I don't know why you would expend all that energy. Just find another planet to live on.
It came pretty close, remember life slowly bounced back afterward. Something a little larger would almost do the trick. You just clean up what survives.
No I don't think it did. I'm not sure you're understanding the scale of things here. I don't believe it came close at all, if "close" means that a ground team could have sterilized the planet afterward. Even if 99% of life were destroyed, that doesn't mean there's one little tide pool with some barnacles surviving, that means there's extremely hardy single-celled organisms living in the deepest nooks and crannies all over the planet.
We can't even "just clean up what survives" in the cleanest rooms on Earth, using techniques specifically intended to do that. Life is incredibly tenacious, I really don't think you're going to wipe it off a planet's surface without destroying the surface (and atmosphere, probably) of the planet in the process. And if that's acceptable - again, why wouldn't you just pick a barren planet.
> Honestly it's all kind of silly because distances are so vast. It makes little sense to travel to a distant star - much better to build space habitats in your own star system.
Maybe their own star system is not safe for them. Say a political or religious minority that the majority would like to exterminate.
> And even if you were going to do that for some crazy reason, there's no shortage of uninhabited planets out there. There's no need to commit planetary genocide of an alien race.
If they've got cheap and easy FTL, sure. But suppose they don't have FTL. They are going the slow way, using a generation ship. At launch they may only know that their destination has a habitable planet but not know if it has intelligent life already.
Their generation ship environment might not be reliable enough for them to want to risk trying to move on to another star if it turns out the first habitable plant already has intelligent life.
I can’t believe I remember this. You jogged an old memory of Angry Beavers loose. IIRC in one episode they were tasked to save the day Armageddon style but started getting pulled into the sun because they strayed too far into its gravitational field and couldn’t boost out. So the beavers went out and built a dam in space to block it, which saved them but then Mission Control calls them up and says they’ve launched a new ice age.
This is all from memory and frankly I’m finding it fun trying it recall it without confirming it haha
"Just parking" between would not be possible without putting really a lot of energy into maintining the position of the shade. Due to orbital speed differences depending on the distance to the sun[1] and the pressure of the light[2] and solar wind[3] on the shade and Earth's gravitational interference. And the shade must be very much larger in diameter than the planet in order to cover it. How large depends on the distance from the planet.
I wonder how that would look from a feasibility perspective...
Let's see - Earth's radius is 6,378 km.
Area exposed to the sun therefore would be 6,378 * 6,378 * 3.14 = 127,731,695 [1]
If you wanted to block just 1% of the light, that would take a shade of 1 million square kilometers, which would be equivalent to a shade that is 1,130 km on a side.
Seems like it would be tough to do given all the dust and rocks floating around the sun. Also, you're only covering 1%, which is much less than cloud cover.
I'd assume you'd aim to block at the equator since that would have the most direct impact on the intensity of the sun over the course of a year.
[1] - I'm calculating the projection as a flat surface here, so the numbers aren't exact but close enough.
Interesting. That area would be roughly one million Sunjammers[1]. One Sunjammer is 1200 m^2 and wights 32 kg. To lift all this would be 32 million kg or 32000 tons. One Starship launch is designed for 250 metric tons when expendable so it would take 128 launches. Add in some fudge factor for orbital burns and I figure 150 launches would do it. Doesn't seem insurmountable.
Edit: Seems I misread the Starship capacity. This is probably only to LEO. Its hard to estimate but going by the geostationary payload, it would be one third of that, so triple the amount of flights. At a cadence of 2 launches per week it would take 4.5 years to launch all of it. ( 450 launches / 2 launches per week / 50 weeks a year)
If you are clever with cabling through your shade and launch in the right orbit you can use the Earths magnetic field to keep the things oriented properly. Astronomers would hate you though.
I'd guess it would be far more efficient to launch more of these into regular orbit than trying to assemble them out in L1 and keep them from drifting off, even though you would need to launch at least twice as many for the same amount of coverage.
1 million square kilometers is 1 trillion square meters, or 833 million Sunjammers. It would take 3748 years to launch them at 2 Starship launches per week.
Does it have to be a sheet of material? If all we want to do is shade the earth, we could launch a few million KGs of glitter into low earth orbit or to the Sun-Earth L1.
Any sentient species that can generate, store, and then convert the amount of energy to either move a sunshade or move the infrastructure needed to construct and then deploy a sunshade at the distances needed to reach inhabitable worlds no longer cares about planets.
They can use that same technology to create, on a whim, inhabitable structures of arbitrary size and composition around any star- converting gas giants (or gas clouds or the solar winds) into perfectly positioned and constructed habitats in ideal locations.
Competition over planets would probably be as foreign and incomprehensible to them as what occurred in the universe prior to the Planck epoch is currently to us.
Seems like climate is more sensitive than we think.
Man made impact or not, the whole system seems on a knifes edge of tipping towards the extremes. That we are living right now is rare in-between point.
Sediment cores show extreme temperature oscillations over far shorter time frames. This [1] is 5 million years of temperature reconstructions based on the Vostok ice cores. Keep in mind the scale, the difference between the peaks and valleys is 10 degrees celsius!
But the really interesting thing is that that derived from this [2], which is Earth's temperature over the past 65 million years. Those previous extremes just blur, because now you're talking about a temperature difference of 20 degrees celcius, no ice on the planet, and giant beasts roaming in lush greenery. Greenery which was basically everywhere, even Antarctica! [3]
It could be the stability of Earth's systems is just an illusion created by observer selection. If it had not been within limits, we wouldn't be here. This places no constraint on how stable it will be in the future.
Another part of the system that could be like that is the oxygen content of the atmosphere. The time constant for variation in O2 level is just a few million years (due to consumption of O2 by release of reducing gases and weathering of rocks to expose reduced materials like ferrous iron.) If it had ever dropped too much during the Phanerozoic higher life would have been wiped out. I don't believe any plausible feedback control mechanism has been discovered. In particular, fire involving plants (which couldn't have occurred before the evolution of large land plants) can be a positive feedback, as charcoal is very resistant to further oxidation and, when buried, represents a net increase in atmospheric oxygen.
Maybe, if mankind explores the galaxy, we'll find all these formerly life bearing planets where stability failed.
Stability is an illusion. It’s becoming increasingly evident that even small shifts in climate have triggered devastating events for humans, like the Bronze Age Collapse, plagues, and so on. Plus, there’s the whole end of the last glaciation that likely created the various flood myths and wiped out most of the megafauna.
Arguably Venus and Mars were more habitable than Earth in the earlier solar system. Both fell off the stability wagon and now are dead worlds (with possible survival of deep underground life on Mars.)
Keep in mind that becoming an ice ball likely led to significantly increased biodiversity, via Wikipedia:
> Since 2009, some researchers have argued that during the Cryogenian Period, potentially the oldest known fossils of sponges, and therefore animals, were formed. However, it is unclear whether these fossils actually belong to sponges, though the authors do not rule out the possibility of such fossils to represent proto-sponges or complex microbial precursors to sponge-grade organisms. The issue of whether or not biology was impacted by this event has not been settled, for example Porter (2000) suggests that new groups of life evolved during this period, including the red algae and green algae, stramenopiles, ciliates, dinoflagellates, and testate amoeba.
> The end of the period also saw the origin of heterotrophic plankton, which would feed on unicellular algae and prokaryotes, ending the bacterial dominance of the oceans.
Even during catastrophic events, life persists in certain niches: deep sea life usually flourishes during massive extinctions because the marine snow becomes a blizzard; ducks survived the dinosaur extinction because rivers obtain bioavailable energy from gravity and erosion, not photosynthesis. So I suspect something like an "Mars vs Venus" cycle is necessary for the evolution of complex life. A highly predictable habitable planet might have cyanobacteria but not algae, since there wouldn't be any selective crises for mutated bacteria to adapt to. It would be awfully hard for a spectrometer to tell the difference between a planet full of bacteria and a pre-civilization planet full pf complex life.
There is a fantastic BBC Horizons documentary from the 90s called Snowball Earth that was easy to find on YouTube the last time I looked, but just now I see a hot mess of search results and if it's still in there somewhere I can't find it.
Google is dead and frozen, a lifeless snowball planet of searchy permafrost.
From Page Rank primacy to worthless enshittified commercial crap, all in a Silicon Valley heartbeat. As one tech commentator put it, very politely, to a GOOG exec in a podcast:
I used to find Google fantastic for answering my questions,
but now it is only good for finding things to buy,
not for finding out what I don't know.
Someone please put us out of our misery, and put Google down.
P.S. As a small start, Brave+DDG is infinitely better than Chrome+Google.
They had a series on planets and some of their history too.
Growing up I honestly thought that planets evolved into a sort of natural stable state that I guess I assumed would last until the sun or other external force decided otherwise. But it’s interesting how throughout time the earth has dramatically changed due to “minor” changes like volcanic activity changes, the introduction of, water, oxygen, or bacteria or other chemicals.
I had thought the sun and distance from it really was the determining factor as far as the temperature generally goes.
Rumsfeld was referring to a way of categorizing uncertainties in a mutually exclusive and collectively exhaustive way. There are many scenarios that are genuinely unknowable - it has nothing to do with competence. He probably saw the matrix on a McKinsey consultants slide earlier that day while they were using their 6 months of strategy consulting experience out of college to help him run the war.
No, it is much closer to the Cynefin framework's understanding that complex systems are affected by the influence of variables which are too small for us to measure or even know they exist until after they act.
Rumsfeld's embarrassment over that line was well earned. He was trying to sell a war based on Iraq having weapons of mass destruction. He was asked why we should go along when there was no evidence for that. He tried to sound smart saying, "Sometimes you don't know what you don't know", basically admitting that there was no evidence to justify his predetermined course of action.
They weren't "unknown unknowns". We knew. He knew too, but he was trying to muddy the waters. He got his way at the expense of one million dead Iraqi civilians, thousands of dead US soldiers, and 3 trillion dollars of US money.
I wonder if we’ll get to a computational space where we can completely simulate every atom in a small closed system. Are we there yet? Can you simulate at the atomic scale and get a perfect representation of reality or do we have to try and simulate something smaller?
If you think about it, a computer's not going to be able to perfectly simulate it's own physical operation, so the limit of a system's ability to simulate things is it's own complexity.
This isn’t obvious to me. It doesn’t have to simulate itself in real time. It may not be able to simulate itself simulating itself. There may be proof of this using a diagonalization proof.
Consider programs that are quines, programs are able to output the exact source code of the program. See [1].
And there are abstract computers that can produce any computable output. These are called Universal Turing Machines, see [2]. UTMs can be specified with a remarkably small number of internal states, see [3].
I’m not saying you are wrong, but computability is full of unintuitive results, and the answer may be more subtle than what is revealed by “just thinking about it”.
We can get up to 100 or so lightweight atoms (the real limiter is the number of electrons, not the number of atoms. Larger atoms cost more). Maybe a thousand or so on supercomputers.
No, for multiple reasons. To your first question, there's still simplifying assumptions. These things usually treat the nucleus as fixed and static, for example, and often other approximating assumptions are used. Outside of the interior of a star, radioactive elements, or when relativistic energies are involved, these are good approximations though.
More fundamentally, quantum systems are inherently random. You literally can't know the exact future of hundreds of atoms in perpetuity--that's not how quantum physics works.
But you can get an idea of minimum energy states, the energy barriers holding those states in place, and therefore what the stable outcomes might be.
The other reason the answer to this is "no" is that we don't even really understand how an atom even works its entirety yet. We don't know fundamentally know what makes the potential energy of an atomic nuclear be structured in the way it is.
EDIT: I thought I'd double check that since it's been a while since I studied physics formally; apparently it is possible to model light nuclei[1] (up to four nucleons) from the ground up now!
You are confusing exact solutions with the ability to solve. We know how atoms work and can solve for any property we might want to measure. Ab initio systems aren't very practical for large systems because of computational costs, but they would work if given infinite compute (or a quantum computer). We just solve them numerically instead of closed-form.
It's like polynomials: there's a quadratic formula, and a cubic and even quartic formula for exact solutions (although the quartic is ridiculous and no one would ever use it). Higher order polynomials have NO exact, closed-form solutions using standard arithmetic operations. But we can still solve any polynomial no matter the degree using numerical methods. To say that we don't even know how how degree 5 polynomials work would be flat out wrong.
Yeah, I’m aware. I was assuming some sort of aligned starting state with atoms whose configurations were perfectly known but I guess that’s not really possible.
If you're thinking "yeah but what if we really knew the starting configuration" then you're not really understanding the uncertainty principle. There is no hidden state that we just don't have access to.
you have no idea what the purpose of the simulation is.
turns out the purpose was for them to study how the borg collective spreads across galaxies, and when we wipe out the borg we've ruined their experiment and they just pull the plug, because none of it was about us. oops.
Things are weirder than that. It's also indistinguishable from the "brain in a vat" theory, which everyone has heard of and which nobody finds interesting. It escapes me why anyone finds "simulation theory" more interesting than that.
> In the year 2079, a human attempt to mine a nearby asteroid instead results in the asteroid being directed towards Earth. As catastrophic natural disasters envelop the world, Mac Walters and Jill McCulloch find themselves in Reno, Nevada. Entering a nearby bar, they encounter a demon named Asmodeus Mogart, who tells them that Earth is but one of thousands of universes set up by the mysterious Department of Probabilities, and that he can save the world if he can gather six magic jewels.
The hack is to find emergent behavior so that you don’t need to simulate every atom. That’s what we did with classic thermodynamics. Extremely simple rules that accurately describe crazy complex systems.
> To better understand the coronavirus’s journey from one person to another, a team of 50 scientists has for the first time created an atomic simulation of the coronavirus nestled in a tiny airborne drop of water.
> To create the model, the researchers needed one of the world’s biggest supercomputers to assemble 1.3 billion atoms and track all their movements down to less than a millionth of a second. This computational tour de force is offering an unprecedented glimpse at how the virus survives in the open air as it spreads to a new host.
> ...
> Once the virus was loaded into an aerosol, the scientists faced the biggest challenge of the project: bringing the drop to life. Dr. Amaro and her colleagues calculated the forces at work across the entire aerosol, taking into account the collisions between atoms as well as the electric field created by their charges. They determined where each atom would be four millionths of a billionth of a second later.
> To carry out this vast set of calculations, the researchers had to take over the Summit Supercomputer at the Oak Ridge National Laboratory in Tennessee, the second most powerful supercomputer in the world. Because the machine was in high demand, they could run their simulation only a few times. “We only have so many shots to actually see if we can get this thing to actually fly,” Dr. Amaro said.
> The first run was a disaster. Tiny flaws in their model caused the virtual atoms to crash into one another, and the aerosol instantly blew apart. “It basically explodes,” Dr. Amaro said.
> After half a dozen rounds of adjustments, the aerosol became stable. The researchers ran the calculations all over again to see what happened inside the aerosol an instant later. All told, they created millions of frames of a movie that captured the aerosol’s activity for ten billionths of a second.
Well, it's a really good start. Total insolation is a great, ah, trend marker. Higher insolation planets tend to be warmer.
Of course, insolation itself stops looking less like a number and more like a function. After all, you're getting photons of different wavelengths (pretend the sun in question is a blackbody) and so that feeds into absorption, reflection, and transmission of each frequency component versus the local atmosphere.
Local atmosphere is a function of surface gravity, orbital velocity (you have to scoop up those gases after all), geologic activity, possible tidal lock, and temperature. Whoops! Back to where we started.
But it is still a great trend. Very low-mass planets are in some ways easier to model. If they are far from a star, any gases that wouldn't escape would freeze and just fall down as another layer of the planet. If they are close to a star, you're just not going to have much atmosphere for long.
Once you are big enough to retain an atmosphere, stuff can get wonky.
Not mentioned but still important, the Sun’s output very slowly rises over time and so was significantly lower 600 million years. We are in a ~2 billion year wide sweet spot where multicellular life can thrive in a high oxygen low CO2 atmosphere.
> Co-author Professor Dietmar Müller from the University of Sydney said: Geology ruled climate at this time. We think the Sturtian ice age kicked in due to a double whammy: a plate tectonic reorganisation brought volcanic degassing to a minimum, while simultaneously a continental volcanic province in Canada started eroding away, consuming atmospheric CO2.
Research:
> Duration of Sturtian “Snowball Earth” glaciation linked to exceptionally low mid-ocean ridge outgassing’, Dutkiewicz, A. et al (Geology, 2024). DOI: 10.1130/G51669.1
It's the carbonate-silicate cycle. Erosion of silicate rocks (which form most of the Earth's crust) by chemical weathering consumes CO2 from the atmosphere and turns it into thermodynamically stable carbonates. Those carbonates can eventually be subducted and their CO2 released again by heat from the Earth's interior.
The carbonate-silicate cycle, which plays a key role in stabilizing Earth's climate over long time scales, is shown in Fig. 2. The cycle begins when atmospheric CO2 dissolves in rainwater, forming carbonic acid, H2CO3. Through a process termed "weathering", this weak acid dissolves silicate rocks on the continents, releasing Ca++, Mg++, HCO3- (bicarbonate), and SiO2 (dissolved silica) into solution. The products of weathering make their way down to the oceans in streams and rivers. There, organisms such as the planktonic foraminifera that live in the surface ocean use them to make shells out of calcium carbonate (CaCO3). When the organisms die, they fall down into the deep ocean, where most of the shells redissolve. Some of the calcium carbonate survives, however, and is buried in sediments on the seafloor. The seafloor spreads from the midocean ridges and, at some plate margins, is carried down subduction zones. The carbonate minerals recombine with SiO2, which by this time is the mineral quartz, to reform calcium and magnesium silicates and release gaseous CO2. This CO2 is vented into the atmosphere through volcanoes, thereby completing the cycle.
Calcium carbonate can also spontaneously precipitate out of solution, but it takes greater extremes of temperature, concentration, or other chemical changes. Shellfish increase the rate at which dissolved calcium carbonate converts to solid calcium carbonate. That action increases the rate at which trapped carbon can be returned to the atmosphere via subduction and volcanic emissions, which means a higher equilibrium concentration of atmospheric CO2 and a warmer planet than we would have if the oceans were lifeless.
From the article: "The team's work raises intriguing questions about Earth's long-term future. A recent theory proposed that over the next 250 million years, Earth would evolve towards Pangea Ultima, a supercontinent so hot that mammals might become extinct."
I'll keep this handy as a smart quip next time someone tries to convince me that human-led climate warming is a thing.
Too little would be bad, yes, but too much is also bad. We can reduce CO2 by a huge amount and still have more than the amount needed for a temperate world.
We are so far over the desired greenhouse gas levels that it's a crisis and reducing it is necessary if we're to continue being able to live in relative comfort. We're not even near the ballpark of having so little greenhouse gas that this would be a worry.
I remember it was one of the remarkable take-away points of nonlinear system dynamics, aka chaos theory: the weather/climate system doesn't even have an "average regime" that it converges on. You can average over longer periods of time, and the resulting sequence doesn't necessarily converge to a single limit. Pretty mind boggling when you think about it. Long term enough, "this place's climate" doesn't even exist.
This is clear even without that knowledge if you take a long enough view. The sun will eventually boil our oceans, and then later the solar system will spend the vast majority of its existence in total darkness.
Coincidentally, I was just watching Myron Cook's video on the Great Unconformity (https://en.wikipedia.org/wiki/Great_Unconformity, although that page only briefly discusses the "Snowball Earth" connection).
The more that we learn about the evolution of Earth as a planet, the more I think that the development of complex life is an exceedingly low probability event. So many things had to go “just right” for conditions on Earth to allow the formation of life.
It’s mind blowing to me that one of those things is the collision of a proto Earth that created the Moon which was just the right size to stabilize the Earth’s rotation.
On top of that, life on Earth required, vulcanism, plate tectonics, carbon cycle, magnetic field, collection of water, location and size of Jupiter and clearing of asteroids, near extinction events that were survivable by some life, etc….
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[ 3.5 ms ] story [ 225 ms ] threadhttps://news.ycombinator.com/item?id=39315378 (An extreme ice-age climate 700M years ago)
What Turned Earth Into A Giant Snowball 700 Million Years Ago? (astrobiology.com)
4 days ago (81+ points / 89+ comments)
"The plans for demolition have been available on Alpha Centauri which is only 4 light years away you know."
It's a tiny fraction of what's required for a proper Dyson sphere. And we know civilizations can afford those because we can no longer see their stars.
For anyone who's hung up on saving nickle, we could do a low budget Worldring² or even thriftier Shadow Squares®.
That's a giant claim you just made like it's fact.
You are correct. That is absolutely a thing I did.
Also correct. Even past that, we haven't been mass-cataloging stars long enough for a Dyson sphere to be constructed and remove a star from our view.
One man's poison is the same man's alcohol and mankind revolves around that.
Dyson Spheres would be really obvious, emitting infrared radiation unlike normal stars.
It looks promising; I'll check it out. Appreciate the recommendation.
The infrared star stands out because it is different than normal stars.
These are really good points. I figured the flaw in my theory is we haven't had precision observation long enough for DS to get constructed. Also that if we noticed the disappearance of a star, that we'd attribute it to a DS and not some natural occluding object.
https://en.wikipedia.org/wiki/Stratospheric_aerosol_injectio...
edit: SOHO is at L1
Kind of like the movie Sunshine, but with more believable physics.
Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disguise their motives for a while, claiming to be there to help counteract global warming. Warnings from a lone scientist would be ignored. Then, as things start getting too cold, their true purpose would become clear to all.
As an alternative - it could be the oil producing countries, not aliens - seeking shade earth to disrupt solar and wind energy, and return to oil dominance.
Step One: build a machine that can cool the Earth, solving global warming Once and For All.
Step Two: demand the governments of the Earth pay you $1 trillion to turn it off at the appropriate time.
It should give people pause that with all the push for more renewables in California and Germany, they now have among the most expensive electricity on Earth.
Solving global warming, turning off the earth iceball machine when it's time? Easily worth $100 trillion. OP just has no supervillain potential.
"I demand the sum of... $1 million dollars!" -- Dr. Evil
Perhaps building unreliable energy infrastructure dependent on favorable climatic conditions is not the greatest idea. Especially if there's going to be major climate change. How's Germany doing again with all its solar lol.
Seemingly benevolent aliens just here to help us fix our mess, but ultimately just want to sneakily take our stuff, is fun trope. https://www.gateworld.net/sg1/s4/2010/
Then they come back a year later: "I have bad news: the timeline has been accelerated, you now have 10 years".
What to do? To whom shall we turn for a plan?
It's a cookbook!
Interesting to think about:
A good movie plot, but I imagine in reality it would be obvious from the start that this would be a possibility and no scientists would be caught off-guard when the shade just didn't get removed. I can be almost certain as well that large factions of humans would "know" (believe, based on no facts) that is was happening all along and there would be incredible conflict across Earth as we figured out how to deal with this gentle attack, even before it was certain that is was an attack.
If it was done without consent, then it is an attack, and it doesn't fu*cking matter whether it ends up causing physical harm (or even if the invaders genuinely thought they meant well).
Regardless of whether it ends up taking away somebody's sunlight forever, it's still robbing people of all their agency. That decision was never theirs to make.
As a bonus, the other aliens in the game didn't view destructive terraforming as equivalent to WMDs - you could do this without even declaring war.
"The Forge of God" by Greg Bear The Makers deploy a vast, self-replicating robotic spacecraft called the "Doomsday Rock" near Earth's sun. The purpose of this massive construct is to absorb energy from the sun, causing it to dim and ultimately leading to the freezing of Earth, thus rendering it uninhabitable.
Spoiler alert: in The Forge of God the Earth gets literally blown to pieces.
Honestly it's all kind of silly because distances are so vast. It makes little sense to travel to a distant star - much better to build space habitats in your own star system. And even if you were going to do that for some crazy reason, there's no shortage of uninhabited planets out there. There's no need to commit planetary genocide of an alien race. Also if you have that kind of tech level, space habitats make more sense than planets anyway. Finally if you seed distant star systems with your own species, you risk that species going to war with you later (see how that played out on Earth just across the oceans.)
Here is an idea for any writers reading this who want to break the violence cycle: whenever you feel you need to have a character kill another in a gratuitously violent way, twist the plot so that they instead end up having steamy sex. The readers will get an intense hormone rush that way too.
Have you seen Earth? We've been hit with a big rock, we've turned out atmosphere into poison, and had several other mass extinctions, none of which sterilized the Earth.
Unless you mean a Theia-level rock to turn the entire surface into lava, but you risk changing the mass, composition, and satellite system of the planet. At that point it's a different planet entirely, so I don't know why you would expend all that energy. Just find another planet to live on.
We can't even "just clean up what survives" in the cleanest rooms on Earth, using techniques specifically intended to do that. Life is incredibly tenacious, I really don't think you're going to wipe it off a planet's surface without destroying the surface (and atmosphere, probably) of the planet in the process. And if that's acceptable - again, why wouldn't you just pick a barren planet.
Maybe their own star system is not safe for them. Say a political or religious minority that the majority would like to exterminate.
> And even if you were going to do that for some crazy reason, there's no shortage of uninhabited planets out there. There's no need to commit planetary genocide of an alien race.
If they've got cheap and easy FTL, sure. But suppose they don't have FTL. They are going the slow way, using a generation ship. At launch they may only know that their destination has a habitable planet but not know if it has intelligent life already.
Their generation ship environment might not be reliable enough for them to want to risk trying to move on to another star if it turns out the first habitable plant already has intelligent life.
This is all from memory and frankly I’m finding it fun trying it recall it without confirming it haha
[1] See https://en.wikipedia.org/wiki/Orbital_speed#Planets
[2] See https://en.wikipedia.org/wiki/Radiation_pressure
[3] See https://en.wikipedia.org/wiki/Solar_wind
https://news.ycombinator.com/item?id=39361279
Let's see - Earth's radius is 6,378 km.
Area exposed to the sun therefore would be 6,378 * 6,378 * 3.14 = 127,731,695 [1]
If you wanted to block just 1% of the light, that would take a shade of 1 million square kilometers, which would be equivalent to a shade that is 1,130 km on a side.
Seems like it would be tough to do given all the dust and rocks floating around the sun. Also, you're only covering 1%, which is much less than cloud cover.
I'd assume you'd aim to block at the equator since that would have the most direct impact on the intensity of the sun over the course of a year.
[1] - I'm calculating the projection as a flat surface here, so the numbers aren't exact but close enough.
Edit: Seems I misread the Starship capacity. This is probably only to LEO. Its hard to estimate but going by the geostationary payload, it would be one third of that, so triple the amount of flights. At a cadence of 2 launches per week it would take 4.5 years to launch all of it. ( 450 launches / 2 launches per week / 50 weeks a year)
1. https://en.wikipedia.org/wiki/Sunjammer_(spacecraft)
I'd guess it would be far more efficient to launch more of these into regular orbit than trying to assemble them out in L1 and keep them from drifting off, even though you would need to launch at least twice as many for the same amount of coverage.
I wonder if there's a solution that uses the dust and rocks. Maybe you nudge some near-Earth asteroid near L1 and then blow it up or something.
Technically you need a bit more than that, for its umbra to block out the entire photosphere over the entire Earth:
https://en.wikipedia.org/wiki/Tangent_lines_to_circles#Outer...
They can use that same technology to create, on a whim, inhabitable structures of arbitrary size and composition around any star- converting gas giants (or gas clouds or the solar winds) into perfectly positioned and constructed habitats in ideal locations.
Competition over planets would probably be as foreign and incomprehensible to them as what occurred in the universe prior to the Planck epoch is currently to us.
Seems like climate is more sensitive than we think.
Man made impact or not, the whole system seems on a knifes edge of tipping towards the extremes. That we are living right now is rare in-between point.
But the really interesting thing is that that derived from this [2], which is Earth's temperature over the past 65 million years. Those previous extremes just blur, because now you're talking about a temperature difference of 20 degrees celcius, no ice on the planet, and giant beasts roaming in lush greenery. Greenery which was basically everywhere, even Antarctica! [3]
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[1] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
[2] - https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
[3] - https://en.wikipedia.org/wiki/Eocene#/media/File:Ypresian_Ea...
Climate and Biosphere is delicate with lots of tipping points and cascades to uninhabitable.
A few billion years ago, the inner planets of the Sol system were capable of supporting abundant surface life - now only Terra.
Another part of the system that could be like that is the oxygen content of the atmosphere. The time constant for variation in O2 level is just a few million years (due to consumption of O2 by release of reducing gases and weathering of rocks to expose reduced materials like ferrous iron.) If it had ever dropped too much during the Phanerozoic higher life would have been wiped out. I don't believe any plausible feedback control mechanism has been discovered. In particular, fire involving plants (which couldn't have occurred before the evolution of large land plants) can be a positive feedback, as charcoal is very resistant to further oxidation and, when buried, represents a net increase in atmospheric oxygen.
Maybe, if mankind explores the galaxy, we'll find all these formerly life bearing planets where stability failed.
> Since 2009, some researchers have argued that during the Cryogenian Period, potentially the oldest known fossils of sponges, and therefore animals, were formed. However, it is unclear whether these fossils actually belong to sponges, though the authors do not rule out the possibility of such fossils to represent proto-sponges or complex microbial precursors to sponge-grade organisms. The issue of whether or not biology was impacted by this event has not been settled, for example Porter (2000) suggests that new groups of life evolved during this period, including the red algae and green algae, stramenopiles, ciliates, dinoflagellates, and testate amoeba.
> The end of the period also saw the origin of heterotrophic plankton, which would feed on unicellular algae and prokaryotes, ending the bacterial dominance of the oceans.
Even during catastrophic events, life persists in certain niches: deep sea life usually flourishes during massive extinctions because the marine snow becomes a blizzard; ducks survived the dinosaur extinction because rivers obtain bioavailable energy from gravity and erosion, not photosynthesis. So I suspect something like an "Mars vs Venus" cycle is necessary for the evolution of complex life. A highly predictable habitable planet might have cyanobacteria but not algae, since there wouldn't be any selective crises for mutated bacteria to adapt to. It would be awfully hard for a spectrometer to tell the difference between a planet full of bacteria and a pre-civilization planet full pf complex life.
[1] https://en.wikipedia.org/wiki/Cryogenian
EDIT: found it on dailymotion and its a great story of how the radical theory was rejected then accepted. https://www.dailymotion.com/video/x7o0b66
From Page Rank primacy to worthless enshittified commercial crap, all in a Silicon Valley heartbeat. As one tech commentator put it, very politely, to a GOOG exec in a podcast:
Someone please put us out of our misery, and put Google down.P.S. As a small start, Brave+DDG is infinitely better than Chrome+Google.
https://www.pbs.org/wgbh/nova/article/the-history-of-earth-i...
They had a series on planets and some of their history too.
Growing up I honestly thought that planets evolved into a sort of natural stable state that I guess I assumed would last until the sun or other external force decided otherwise. But it’s interesting how throughout time the earth has dramatically changed due to “minor” changes like volcanic activity changes, the introduction of, water, oxygen, or bacteria or other chemicals.
I had thought the sun and distance from it really was the determining factor as far as the temperature generally goes.
This seems to be another expression of the truth that "people tend to mistake the limits of their view for the limits of the world."
1. You don't know what you don't know.
2. You know what you don't know.
3. You know what you know.
4. You don't know what you know.
https://en.wikipedia.org/wiki/Four_stages_of_competence
They weren't "unknown unknowns". We knew. He knew too, but he was trying to muddy the waters. He got his way at the expense of one million dead Iraqi civilians, thousands of dead US soldiers, and 3 trillion dollars of US money.
I'd first encountered it in print in a 1982 book, Forced Options, by Roger Lincoln Shinn, two decades before Rumsfeld's famous 2002 usage:
<https://archive.org/details/forcedoptionssoc0000shin_c8x7/pa...>
- George Bernard Shaw, "Ceasar and Cleopatra"
https://www.quantamagazine.org/inside-the-proton-the-most-co...
Consider programs that are quines, programs are able to output the exact source code of the program. See [1].
And there are abstract computers that can produce any computable output. These are called Universal Turing Machines, see [2]. UTMs can be specified with a remarkably small number of internal states, see [3].
I’m not saying you are wrong, but computability is full of unintuitive results, and the answer may be more subtle than what is revealed by “just thinking about it”.
[1] https://en.m.wikipedia.org/wiki/Quine_(computing)
[2] https://en.m.wikipedia.org/wiki/Universal_Turing_machine
[3] https://en.m.wikipedia.org/wiki/Wolfram%27s_2-state_3-symbol...
Quantum computing will change this though.
More fundamentally, quantum systems are inherently random. You literally can't know the exact future of hundreds of atoms in perpetuity--that's not how quantum physics works.
But you can get an idea of minimum energy states, the energy barriers holding those states in place, and therefore what the stable outcomes might be.
EDIT: I thought I'd double check that since it's been a while since I studied physics formally; apparently it is possible to model light nuclei[1] (up to four nucleons) from the ground up now!
[1] https://en.m.wikipedia.org/wiki/Ab_initio_methods_(nuclear_p...
[1]
It's like polynomials: there's a quadratic formula, and a cubic and even quartic formula for exact solutions (although the quartic is ridiculous and no one would ever use it). Higher order polynomials have NO exact, closed-form solutions using standard arithmetic operations. But we can still solve any polynomial no matter the degree using numerical methods. To say that we don't even know how how degree 5 polynomials work would be flat out wrong.
However, it actually doesn't matter in any way whatsoever.
turns out the purpose was for them to study how the borg collective spreads across galaxies, and when we wipe out the borg we've ruined their experiment and they just pull the plug, because none of it was about us. oops.
People who believe in the simulation also tend to try and influence it (Scott Adams does), using a method indistinguishable from prayer.
https://en.wikipedia.org/wiki/And_the_Devil_Will_Drag_You_Un...
> In the year 2079, a human attempt to mine a nearby asteroid instead results in the asteroid being directed towards Earth. As catastrophic natural disasters envelop the world, Mac Walters and Jill McCulloch find themselves in Reno, Nevada. Entering a nearby bar, they encounter a demon named Asmodeus Mogart, who tells them that Earth is but one of thousands of universes set up by the mysterious Department of Probabilities, and that he can save the world if he can gather six magic jewels.
> To better understand the coronavirus’s journey from one person to another, a team of 50 scientists has for the first time created an atomic simulation of the coronavirus nestled in a tiny airborne drop of water.
> To create the model, the researchers needed one of the world’s biggest supercomputers to assemble 1.3 billion atoms and track all their movements down to less than a millionth of a second. This computational tour de force is offering an unprecedented glimpse at how the virus survives in the open air as it spreads to a new host.
> ...
> Once the virus was loaded into an aerosol, the scientists faced the biggest challenge of the project: bringing the drop to life. Dr. Amaro and her colleagues calculated the forces at work across the entire aerosol, taking into account the collisions between atoms as well as the electric field created by their charges. They determined where each atom would be four millionths of a billionth of a second later.
> To carry out this vast set of calculations, the researchers had to take over the Summit Supercomputer at the Oak Ridge National Laboratory in Tennessee, the second most powerful supercomputer in the world. Because the machine was in high demand, they could run their simulation only a few times. “We only have so many shots to actually see if we can get this thing to actually fly,” Dr. Amaro said.
> The first run was a disaster. Tiny flaws in their model caused the virtual atoms to crash into one another, and the aerosol instantly blew apart. “It basically explodes,” Dr. Amaro said.
> After half a dozen rounds of adjustments, the aerosol became stable. The researchers ran the calculations all over again to see what happened inside the aerosol an instant later. All told, they created millions of frames of a movie that captured the aerosol’s activity for ten billionths of a second.
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Aside: the "four millionths of a billionth of a second" is 4fs or 4x10^-15 seconds - https://www.wolframalpha.com/input?i=four+millionths+of+a+bi...
> 0.4 x time for a typical water molecule vibration
The corresponding press release: https://www.olcf.ornl.gov/2021/11/16/we-know-covidisairborne...
The abstract presented - https://sc21.supercomputing.org/proceedings/tech_paper/tech_...
Preprint of paper that matches the abstract mentioned in the ornl press release - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8609898/
Of course, insolation itself stops looking less like a number and more like a function. After all, you're getting photons of different wavelengths (pretend the sun in question is a blackbody) and so that feeds into absorption, reflection, and transmission of each frequency component versus the local atmosphere.
Local atmosphere is a function of surface gravity, orbital velocity (you have to scoop up those gases after all), geologic activity, possible tidal lock, and temperature. Whoops! Back to where we started.
But it is still a great trend. Very low-mass planets are in some ways easier to model. If they are far from a star, any gases that wouldn't escape would freeze and just fall down as another layer of the planet. If they are close to a star, you're just not going to have much atmosphere for long.
Once you are big enough to retain an atmosphere, stuff can get wonky.
Research:
> Duration of Sturtian “Snowball Earth” glaciation linked to exceptionally low mid-ocean ridge outgassing’, Dutkiewicz, A. et al (Geology, 2024). DOI: 10.1130/G51669.1
https://personal.ems.psu.edu/~jfk4/PersonalPage/ResInt2.htm
The carbonate-silicate cycle, which plays a key role in stabilizing Earth's climate over long time scales, is shown in Fig. 2. The cycle begins when atmospheric CO2 dissolves in rainwater, forming carbonic acid, H2CO3. Through a process termed "weathering", this weak acid dissolves silicate rocks on the continents, releasing Ca++, Mg++, HCO3- (bicarbonate), and SiO2 (dissolved silica) into solution. The products of weathering make their way down to the oceans in streams and rivers. There, organisms such as the planktonic foraminifera that live in the surface ocean use them to make shells out of calcium carbonate (CaCO3). When the organisms die, they fall down into the deep ocean, where most of the shells redissolve. Some of the calcium carbonate survives, however, and is buried in sediments on the seafloor. The seafloor spreads from the midocean ridges and, at some plate margins, is carried down subduction zones. The carbonate minerals recombine with SiO2, which by this time is the mineral quartz, to reform calcium and magnesium silicates and release gaseous CO2. This CO2 is vented into the atmosphere through volcanoes, thereby completing the cycle.
2 CO2 + H2O + CaSiO3 -> Ca^2+ + 2HCO3- + SiO2
and
Ca^2+ + 2HCO3- -> CaCO3 + CO2 + H2O
https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc...
I'll keep this handy as a smart quip next time someone tries to convince me that human-led climate warming is a thing.
We are so far over the desired greenhouse gas levels that it's a crisis and reducing it is necessary if we're to continue being able to live in relative comfort. We're not even near the ballpark of having so little greenhouse gas that this would be a worry.
Illustrated answer:
https://xkcd.com/1732/
https://www.youtube.com/watch?v=LXzDfQyUlLg
Beautiful scenery and an excellent discussion of geological strata.
It’s mind blowing to me that one of those things is the collision of a proto Earth that created the Moon which was just the right size to stabilize the Earth’s rotation.
On top of that, life on Earth required, vulcanism, plate tectonics, carbon cycle, magnetic field, collection of water, location and size of Jupiter and clearing of asteroids, near extinction events that were survivable by some life, etc….