What made Earth a giant snowball 700M years ago? Scientists have an answer
sydney.edu.au
sydney.edu.au
https://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)
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.
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.
"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®.
²Nivenlarry ®Larry NivenThat'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:
* 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?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
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)
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.
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...
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….
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
(am also annoying about Thinkpads, FreeTaxUSA)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.
P.S. As a small start, Brave+DDG is infinitely better than Chrome+Google.
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.
https://www.youtube.com/watch?v=LXzDfQyUlLg
Beautiful scenery and an excellent discussion of geological strata.
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: