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Climate collapse, Fermi paradox 

How fucked up would it be to find ruins of a highly technological civilization on Venus?

Venus is totally in the habitable zone (although it has very long days) and the only reason it's so hot is because its dense CO2-rich atmosphere. What if once it had sentient life and they started a runaway global warming...?

I wonder if it's possible that an artificial satellite orbiting Venus would have remained invisible to this day. If it has a small enough radar cross-section and stable orbit...

I wish I would know more astronomy.

/cc @anne

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This could make an awesome AND terrifying science-fiction story.

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Climate collapse, Fermi paradox 

@uint8_t I guess it would explain why they've never looked there. It might scare the 1% with the results.

@giantessgnostic Venus was the first planet after Earth where we landed a probe! It failed after a few hours, as expected. Scorching temperatures, darkness, sulfuric acid, high pressure, etc.
So while it's easy to get robots there, it's hard to make them last.

@uint8_t oh gosh we love this idea

one of the old ideas of scifi is that the sun is cooling down over time, and so Mars is the old dead world, Earth is the current one, and Venus is the infant to eventually take Earth's place.

and, welp, turns out that's backwards, the sun is *brightening* over time

but it would definitely be cool to see that trope reversed with nothing to do with the sun at all - now it's life that heats up planets.

Venus was then, Earth is now, Mars is next.

@diodelass What if we build giant spaceships which transfer the excess CO2 from Venus to Mars? We get 2 more habitable planets!

Make rocket fuel from CO2, water, and sunlight in floating cities on Venus. Fill solidified CO2 into reusable tanks, send them into low Venus orbit. Take the frozen CO2 out, send back the tanks, and use laser propulsion to send most of the CO2 ice to Mars.

@uint8_t @diodelass i think orbital rings make more sense than rockets.

Ditto for Saturn/Jupiter, but those are even more.. involved orbital rings. Skyhooks might also be possible..

orionsarm.com/ has a bunch of articles from Paul Birch about it orionsarm.com/fm_store/Paul%20 and of course the Lofstrom loop also has a whole article too.

I like OrionsArm, but tbh it lacks detail sometimes.

@diodelass @uint8_t I'm not sure there's any hope of Mars springing to life (alas) without intelligent intervention - there really isn't enough hydrogen to make oceans. This is a general problem throughout the inner solar system, where small bodies and high temperatures let water escape to space.

With intelligent intervention, well, we might learn to live in current Martian conditions, or we might drop comets on it for a (temporary but long) bunch of extra hydrogen.

@uint8_t I saw an article about a similar hypothesis, but on Earth, several million years ago during one of the mass extinction, as the period was hotter than today, and was following a rapid increase of CO2 in the atmosphere.

@Feufochmar But how much carbon is still in hydrocarbon and coal form on our planet? What if we burn everything? (if the atmosphere gets depleted, we can liberate oxygen from minerals, it's just a matter of energy)

@uint8_t pretty sure I’ve already read one like this but about Mars.

Also modern time JG Ballard has some corker post apocalyptic fiction like:

The Drowned World is a 1962 science fiction novel by British writer J. G. Ballard. The novel depicts a post-apocalyptic future in which global warming has caused the majority of the earth to become uninhabitable.

@uint8_t They have bounced some pretty serious radar off of Venus - like, transmitted with the 300m Arecibo dish. But it's a long way away, and artificial satellites can be small. How long they could last, well, many of our satellites will come down soon but that's because we put them up as low as wee can get away with. The ones that are high up are going to be there a very long time.

@uint8_t Venus is actually a pretty comfortable place, a reasonable temperature, reasonably clear sky, just a bit acidic, at the one-atmosphere altitude. The ground is just a long way below that. But breathable air is a lifting gas on Venus, so there's this idea that you could build floating cities at the 1 atmosphere depth on Venus.

@uint8_t It certainly is possible for runaway global warming to occur, and it is thought to have happened to Venus - the oceans would have boiled, and the water vapour would have added to the greenhouse effect until it escaped to interplanetary space. At that point the result is really irreversible. It seems like maybe we can't make it happen here:
royalsocietypublishing.org/doi

@uint8_t TIL: Venus has 100 times more deuterium mixed into its hydrogen than Earth. This is strong evidence for an ocean that boiled away, and it was measured by one of our probes before they died.

@kragen @anne Deuterium is an isotope of hydrogen. Heavy water (D2O) has a slightly higher boiling point, lower vapor pressure, and lower mean speed, so if you got an ocean with a H2O-D2O mixture, the concentration of D2O increases as you boil the water away. Our oceans have a higher D2O concentration than our rivers.

@kragen @anne @uint8_t because it is heavier, it's less distant from oxygen in a water molecule, and has a stronger bond.

Also any molecule it is on, it tends to make it heavier than the identical one with regular hydrogen, so it typically ends up lower in the atmosphere.

@jasper @anne @uint8_t Do we mean 100 times more deuterium in Venus's atmospheric hydrogen than in Earth's hydrogen, most of which is, I think, in its oceans? Is there a big difference between the deuterium fraction in Earth's atmosphere and in its oceans?

@kragen @jasper @uint8_t So the article describing the measurement is: ncbi.nlm.nih.gov/m/pubmed/1778
Terrestrial spectroscopy cast some doubt on the result but Venus Express seems to confirm it:
sci.esa.int/venus-express/5406

The deuterium enrichment is thought to have occurred because hydrogen is lost more easily to space; fortunately the Earth doesn't lose a lot of hydrogen because it's mostly in water and the "cold trap" keeps that too low for photodissociation.

Climate collapse, Fermi paradox 

@uint8_t tricky. Venus itself has a habitable altitude range. It's not likely anything ever lived on the dark, hot, crushing depths of supercritical liquid carbon dioxide and sulfur dioxide on the surface. We can't even get probes down there. If we found ruins it would be ruins that used to float on the clouds. Those would be super rad though.

Climate collapse 

@falkreon The CO2 is definitely not liquid on the surface. The USSR managed to land probes on the solid surface of Venus: en.wikipedia.org/wiki/Observat

Also the core idea of the story is that Venus was not always uninhabitable like it is today. A runaway global heating could have caused the release of so much CO2 into its atmosphere.

Climate collapse 

@uint8_t surface temp of 740K and pressure of about 92 atm on Venus' surface are above the ~300K and 72atm of critical CO2. So if there's CO2 there, it's supercritical fluid.

Climate collapse 

@uint8_t anyway I stand corrected, it's cool that someone managed to get probes down there.

Venus easily has enough nitrogen to make a nitrogen-oxygen atmosphere like we have (let's pretend the oxygen has been lost in a Fermi filter event since), but I worry that without the heavier gases it just wouldn't compact and make the same ionosphere that prevents the loss of atmosphere on that planet.

Climate collapse, Fermi paradox 

@uint8_t have you read theatlantic.com/science/archiv ?

“How do you know we’re the only time there’s been a civilization on our own planet?”

Climate collapse, Fermi paradox 

@meena I have now, thanks!

Climate collapse, Fermi paradox 

@uint8_t @meena *Toolmaker Koan* is a fantastic book with the premise that a maniraptoran civilization in the Cretaceous bombed itself into practical extinction. Highly recommended.

Climate collapse, Fermi paradox 

@gcupc @uint8_t so i was just reminded of the "Quaternary extinction event"
en.wikipedia.org/wiki/Quaterna
and now i wonder, if another similarly intelligent species were to arise, would they too kill (and eat) all the megafauna as they spread further across the planet?

Climate collapse, Fermi paradox 

@uint8_t One of the current hypotheses for Venus is that it had water like Earth did, but because of its slow rotation, those very long days caused it all to evaporate, which accelerated warming. It also would have allowed ground water to allow easier plate tectonics, which would've increased volcanism, releasing carbon dioxide, which at Venus' distance from the Sun would absolutely supercharge warming. This all could've happened in under 100million years.

Climate collapse, Fermi paradox 

@uint8_t the factors in a Drake-equation-esque calculation you multiply a sequence of probabilities with the number of stars and get the probability of a civilization.

Given the number of stars, the probability that a star creates a civilization has to be really low. It seems to me that the probability that a planet does not have significant is fossil fuels is what, 50%. Think if the dinosaurs had a civilization, they won't have as much fossil fuels..

Climate collapse, Fermi paradox 

@uint8_t I mean it doesn't help the fermi paradox.

@jasper and the big question is if we're before or after the Great Filter

we need more data

@uint8_t @jasper it seems to me that talking about a Great Filter presumes that technological civilizations can reach a stable, long-lasting state if they manage to pass through one. Perhaps all technological civilizations implode after a few centuries; that would certainly help with the Drake Equation.

@anne @jasper so technology itself might be the Great Filter ⚙

@uint8_t @anne it's all speculation at this point.

Like nuclear weapons? I am not sure if that has similar issues as fossil fuels. I.e. having too little nuclear material. "It just being a great disaster" instead of killing civilizations..

Is there some idea that is destructive?

Or maybe it's just lots of different things that bring the probabilty down sufficiently. Maybe it doesn't kill them at all, but slows them down and natural selection is adverse for civilizational development.

@uint8_t @anne
There is the en.wikipedia.org/wiki/Aestivat that civilizations realize that black hole farming can contain far more computation power than the entire stellar era.(because of lower temperatures)

But it's not clear to me that black hole farming can actually be built, and the article didn't talk about enforcement.

Imagine a populated universe might cause conflicts that interfere with building of black hole farms.

Not sure why they would not tell us, though.

Climate collapse, Fermi paradox 

@jasper @uint8_t Most coal was laid down in the Carboniferous. The dinosaurs would have had plenty of fossil fuels.

One of the usual factors in the Drake equation is the fraction of life-bearing planets that develop industrial civilizations. Or rather, it's the expected number of industrial civilizations, if a planet might develop more than one independently.

Climate collapse, Fermi paradox 

@anne @uint8_t right.. didn't realize that.. Remember reading about lignin decomposition occuring late. It might be that it is dependent on specific evolutionary history aswel.

Of course there is a chance fossil fuels might be needed to progress civilizations.

Anyway, the odds of killing the civilization is also a concern. Other civilizations might be on planets that are on the cold side, and just suffer disasters from it.

Climate collapse, Fermi paradox 

@anne @uint8_t Like a 1% survival rate makes just like a small part of the story how the probability of civilizations surviving is so small we see none, because there have to be more factors out there.

Climate collapse, Fermi paradox 

@uint8_t Earth will one day end up like that, we're just accelerating that process.

As the sun ages the habitable zone expands outwards, life on Earth would adapt to keep more CO2 out of the atmosphere eventually bringing it too low to sustain photosynthesis which will start the trend towards CO2 entering back into the atmosphere due to various chemical reactions in the rock.

Multicellular life has ~1billion year window to evolve, develop technology that could save them before the habitability for life more complex than archaea and bacteria disapears, Prokarya were here for ~3G years before the dawn of multicellular life, and they'll be the last here too assuming humanity doesn't finds their way through many great filters.

Climate collapse, Fermi paradox 

@uint8_t this is loosely similar to the backstory of Echoes of an Alien Sky.

I feel like I've read another book that was actually about Venus being an extinct runaway greenhouse planet, but I may just be remembering the theory as a general concept.

Climate collapse, Fermi paradox 

@uint8_t Turns out that Venus's atmospheric runaway was likely fairly recent. Possibly w/in past billion years, if not 100s of millions. According to theories.

Climate collapse, Fermi paradox 

@dredmorbius so maybe the comet killing the dinosaurs was a Venereal terraforming project!?

Climate collapse, Fermi paradox 

@uint8_t Poetic, but unlikely.

Climate collapse, Fermi paradox 

I've wondered this before.

@uint8_t

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