#like the only thing they'd have in common is orbiting a planet the way a planet orbits a star

[dectech]

We all know about the fuss around Pluto, how many decry its "demotion" to a dwarf planet, and how it's still an honorary planet in the hearts of many, and I totally get it, but I don't think any of you out there are taking it far enough.

What about the rest of the so-called "dwarf" planets, huh? where's their justice? what about Ceres? Haumea? Makemake? Eris? fucking Quaoar?! why have just eight planets when you can have 18?! Why only invite Pluto to the party if you're already gonna expand the guest's list?!

you know what should be "demoted"? fucking Phobos and Deimos, the two "moons" of Mars. these two motherfuckers are proof that the barrier-to-entry for moons is too low. they're barely visible, they don't effect mars in any meaningful way, they aren't even round since they aren't big enough to round themselves under their own gravity, and one of them isn't even in a stable orbit of Mars! Phobos is gonna get ripped apart by mars' gravity in just a few dozen million years!

the concept of a "Dwarf Moon" is too good for them. they should be called, like, sateloids or something. Lunoids at most. fuck em

[ifuckinglovedinosaurssomuchjesus]

Pretending End Cretaceous mass extinction event never took place, do you have any thoughts on speculative evolution and how dinosaurs and their contemporaries may have evolved through the years?

Like the explosion of mammal biodiversity probably wouldn’t have taken place, but what else? Assuming other global processes like plate tectonics, and the accompanying changes in currents, oxygen cycles etc, if you only take away the asteroid and it’s direct consequences, how do the dominoes fall?

Well, AFAIK the asteroid wouldn't have had any long term affects on the planet's tectonic activity or the climate. It was an apocalyptic event for sure, but depending on what scientist you believe, the immediate effects of the impact were over anywhere from a couple thousand years to only a few months.

So the plates would still move the way they have in the Cenozoic and the climate would still cool down and dry up due to the Earth's orbit and Milankovitch cycles. There would still be an Ice Age and animals would have to adapt to it.

The main difference would be life of course, and I cannot stress this enough, everything would be different. There would be no placental mammals, plant life would be mostly angiosperms but not in their total domination we see today, teleost fish wouldn't fill almost every aquatic niche like they do today, and of course there'd still be a shit ton of dinosaurs.

The thing about the asteroid was that it basically wiped the earth clean of entire clades, and those vast expanses of open niches is what kickstarted the biosphere we know today. There would be literally nothing in common with our "timeline" if it hadn't hit, except for some extreme cases of living fossils like Triops or Lepisosteus. No Mackerel, no Poison Dart Frogs, no Rose Bushes, no Great White Sharks, no Leopard Slugs, no Bears, no Giraffes, no Komodo Dragons, no Coconut Trees, no Crows or Ravens, etc.

In that sense though, 66 million years isn't that long in the perspective of the Mesozoic, so there wouldn't be anything crazy different from the Cretaceous. I doubt we'd see any dinosauroids for example. There would still be big sauropods and big theropods to hunt them, there would still be pterosaurs and marine reptiles of all kinds, there'd still be Ammonites and plenty of lobe finned fish, etc.

I think it's safe to say the arms race between armored Ornithischians and Tyrannosaurs would fizzle out, and much like the Stegosaurs and Carnosaurs of the Jurassic, they'd go extinct to make way for other animals to take their place. Maybe gigantic dromaeosaurs and quadrupedal ornithomimids or extremely armored sauropods and pterosaurs with bone crushing beaks, the possibilities are endless and I'm sure there's a million speculative evolution projects out there trying to answer that question.

Basically, we wouldn't be here making these posts.

[hasufin]

Ad astra, non planetarum

With current talk of the pipe dream of colonizing Mars, I'd like to put forth a more realistic notion:

We are never going to colonize other planets at all.

Now, I'm not saying we will give up on space and stick on this little ball of rock. I mean, yes, it's a pretty nice ball of rock and it's well-suited to us, but there are Damned Good Reasons to not limit ourselves.

However, it's a really nice ball of rock, in terms of human life. Uniquely so. To the extent that it's kind of silly to think of Humans as independent organisms. We are part of this ecosystem. I think it's fair to say Earth's ecosystems would largely continue without us - we are not a keystone species in most cases - that ecosystem is crucial to our survival.

We are uniquely suited to, and reliant on, Earth conditions in ways which are both obvious and subtle.

It's not hard to replicate straightforward things like temperature, pressure, and atmosphere. We're at the point where we can - with risks, to be sure - create shirtsleeve conditions both on the ocean floor and in space. Gone are the days of Oxygen-only environments for space, and exotic gas mixes aren't obligatory for deep sea exploration.

That's enough for brief little excursions. For longer time periods, though, that's not enough. Earth's Van Allen belts and ozone layer protect us from the worst of cosmic radiation (fun fact! Apollo astronauts reported seeing bright flashes. This was due to high energy particles passing through their eyes! This is horrifying!).

There's also the microbial world. Now, a controlled environment has some advantages - people don't get the common cold at the South Pole, because everyone who goes there undergoes quarantine and screening so they don't bring in unwanted bugs - but you need your gut bacteria, your skin mites, your yeasts. There's even the old friends hypothesis that you need some exposure to allergans so your immune system doesn't freak out. So a fully-controlled long-term environment has some potential issues there.

But we haven't even touched the big one: gravity. Humans evolved on a nice 1g planet, and living a long time in lower G is... not great. Technically the ISS and other orbital habitats are not in zero G, they're in freefall, but the effect is (probably) the same. It has significant effects on bone density, lymphatic drainage, and cardiovascular health, just to name a few things.

Some of these issues can be ameliorated. I recall discussing with a friend how to handle the radiation issue - I was coming up with a design for a hypothetical P5 containment facility out at a LaGrange point - and he suggested sintered lunar dust as shielding. Because in the absence of a planetary dynamo generating a magnetic shield, you need a lot of mass to block that sort of stuff.

And sure, we'll probably work out the microbial stuff. The gravity, though... we do kinda need it. And so far there's exactly one way to generate gravity: a centrifuge. Which could be adapted to operate on a planet, but would be an engineering challenge. It would be necessary, though, as the only planets with surface gravity even close to Earth's are Venus and (with caveats vis a vis their lack of a "surface") the three outermost gas giants. And I cannot even go into how difficult it would be to build a habitat on Venus. So you couldn't have people permanently living on one of the other planets - they'd have to rotate out every few months, and even then have permanent health issues.

Not to mention that those other planets all have their own issues. For example, moon dust turns out to be terribly abrasive and gets everywhere, which is bad for equipment. Martian soil is full of toxic perchlorates. Venus is... well, Venus. Mercury is at times inside the solar corona. Not only is Mars a bad place to raise your kids, so are the other planets.

What I'm getting at is, in order to have a habitat on any other planetary body, we'd necessarily need to have a fully-realized supporting space station. A habitat in space which provides not just heat and atmosphere, but has a functional facsimile of a Terran ecosystem, is largely a closed or at least self-sustaining system in terms of food and water, provides gravity, has appropriate radiation shielding, and addresses whatever other unknown unknowns we have with extraterrestrial habitation. Some of the solutions can be put on a planetary body, but only a few are easier to implement on a planet, and some may not be possible on a planetary body at all. Moreover, before we could do them on a planet we'd inevitably have to build them all in a space station at the same place anyway.

Which means that you decide you want to go to Mars. Or Epsilon Eridani. Whatever. You build a pretty comfortable space station, you park it in orbit. Then you decide to build an inferior habitat on the planet below. At which point you need to address the exorbitant cost of going in and out of a gravity well. And for what? Bragging rights?

I'm reluctant to cast this strictly in economic terms, but from where we are right now, it looks like it will never make sense (assuming humans remain as biological entities) to colonize other planets: we will always have to build something better first, and a planetary habitat will be both more expensive and inferior to a space habitat.

[fenmere]

It's actually pretty well known at this point that when a planet starts to undergo an industrial revolution, what they end up like by the time your envoy arrives is pretty random.

That's sort of the point. You never know what kind of wacky technology they'll have developed by the time you get there. It can be a pretty big gamble, but it's worth it if you're flexible enough.

Evolution is creative, and life even more creative. We've gained so much knowledge and technology by acquiring it from others.

But you've got to be on your toes.

The envoy you send out to make first contact won't look the same by the time they reach their destination as the when they first set out, if you're doing things right.

They'll be monitoring transmissions from the target planet and cracking the languages, keeping abreast of their social developments, keeping track of their militaristic technology and strategies, trying to get a handle on their politics, etc.

Some like to manipulate their targets, send out transmissions as soon as the linguistic barrier is broken. Or sooner, to help break it. Sometimes that helps things along and paves the way for a smooth assimilation, if that's what you're after. But it's still a gamble.

A good, surprise nuclear war is an excellent way for a planet to wipe its slate clean just before you arrive. And while you can lower the chances of that happening if you try to coddle them and guide them before you show up, you can also screw up and trigger it.

And then you have civilizations like the Ktletaccete who don't even bother, roaming around in their generational ships at 0.99 C, avoiding everyone. Just cruising past technological singularity after technological singularity as if they're unnecessary snacks.

We prefer to sneak up on our targets.

Which is what we did with Gaia, of course, or Terra, or Earth, or Dìqiú, or Krakawoa, or what we called it, #367.

Even back then we were old hands at this.

We watched our envoys from afar, knowing that when we got the updates from them, it would have all been over. It doesn't matter. We learn what we learn when we learn it and can use it. Timing only matters for the arrival of our envoy fleet, not for our home. We're stable.

But here's what happened with that damn planet.

By the time we got there, the technologically advanced species had killed themselves off with climate change and disease. Unfortunately, pretty common for those that manage to narrowly avoid nuclear war. Fortunately, it meant that their archives and artifacts were in relatively good condition when we arrived, and our envoys were so ready for that.

By the time we got there, it was a fecund planet covered in jungles with a layer of treasure underneath all of it. We were excited.

But then, shortly after our envoy landed they went silent. All of them. Even the ones left in orbit.

That was spooky.

We wondered if maybe someone else got there just after us, and wiped our people out. Or maybe they'd been lying in ambush. It's been known to happen.

In hopes of learning something eventually, we sent a message asking what happened, knowing it would take a couple hundred years to return, and that the people who received it might not know our language. And then we moved on. Focused elsewhere, except for one radio array we kept focused on that planet.

Just as we were signing off on the project and leaving our technicians to monitor the monitoring equipment, a transmission came from the planet. It was in a whole new language, but came with a translation guide tailored specifically for us.

The guide took up far more bandwidth and storage than the message itself did. Volumes of information to assist us in understanding anything the new civilization might say to us, all for the purpose of saying one tiny sentence:

"Thanks for the shinies."

There was also an image included. A portrait of one of them. Or part of them.

They leaned so close to the camera that we could only see their big black eye, surrounded by fine black feathers, and what appeared to be a nostril at the base of what our biologists think is a beak.

Between the nature of their language, these visual clues, and their predecessor's descriptions of their fauna that we'd scavenged on the way there, we're pretty sure that these beings were living on that planet the whole time.

They call themselves the Krakawoans.

Honestly, they overpowered our envoys and appropriated our communications technology so fast, we're afraid of them.

We haven't bothered to continue communications with them, and we caution anyone eying that planet. They're going to be one of us, soon.

Aliens first observed our planet long before the Industrial Revolution, a perfectly habitable world ripe for conquest. However, it takes hundreds of years for the invasion fleet to arrive and they are in for one hell of a suprise.

[morningcattime]

My current preferred answer to the Fermi paradox relies on these assumptions:

1) Galactically speaking, we're extremely early to reach advanced intelligence. The earth may be ideally placed to reach advanced biological stages quickly.

a) The earth has a weirdly stable climate because of its huge moon helping to maintain a liquid water system, tidal forces preserving tectonic activity that maintained the biosphere and a powerful magnetosphere, and the Sol system's possibly abnormal lack of inner gas/ice giants causing orbital perturbations. (Though that could apparent abnormality could very well be observational bias, since with our current technology it's far harder to find planets that aren't massive and close to their stars. This hypothesis could be disproven within a decade.)

Most planets that evolve advanced life might lack a moon like ours and might only be able to evolve life thanks to thick atmosphere to block radiation (implying high surface temperature), an ice sheet, or a radiation-blocking crust riddled with lava tubes. More on those scenarios later.

b) The sun is unusually stable for a yellow dwarf, and certainly much more stable relative to giants or early stage red dwarfs. This allowed multicellular life to evolve faster than "normal", where it would normally. Most life in the galaxy might end up evolving around red dwarfs, which have much much longer periods of stability but extremely narrow liquid water ranges.

c) We have had unusually quiet galactic trajectory. The sun's path through the galaxy has apparently not brought us close to many supernovae or though any other stars' Oort clouds or anything. Passing through the Local Bubble for the past few million years may have been conducive to the development of advanced technological life by making supernovae and stellar encounters even less common.

2) Space travel is way harder for many or most technological civilizations. The earth's lowish gravity and liquid water might make it much more conducive to creating a spacefaring civilization sooner. Ice planets might have dozens of technological civilizations over hundreds of millions of years before any of them discover space at all. A civilization that evolves underground that has to launch expeditions onto a barren, radiation scorched surface late in its technological development might not be much better off. And for the higher gravity civilizations, the rocket equation becomes a real bitch. Imagine a civilization having to discover fusion and cooperate on a global basis just to launch their Sputnik equivalent, just because they'd need a rocket 100 times the power of the SLS to launch it.

3) Interstellar travel is HARD and not especially rewarding. The idea that we should be able to see Kardashev class II+ civilizations assumes that there are viable ways to reach those levels and that spacefaring civilizations will inevitably reach them. If most civilizations evolve in small islands or archipelagos with no real benefit to exploring further--which doesn't seem unlikely, since fewer neighbors means fewer nearby supernovae--we won't see those signs.

Relatedly, it might just be that class II is a much comfier place to sit for millennia than we're giving it credit for. There may be no meaningful bottlenecks that would cause a civilization to even want to leave their sun. This is especially important if life inevitably tends towards cyborg integration. If you are part of a superorganism with every other person within light speed communication range, why do you want to increase that latency from milliseconds to years or decades?! Imagine atavistically reducing your existence to just being a single mind trapped in a cranium, where you sometimes might not know things or even be almost completely alone for hours at a time, where your community is reduced to a few hundred other individuals of your species. Practically torture.

4) A civilization's radio bubble shrinks dramatically after they get good at using radio waves. Once every being on your planet has terabit wireless connections to every other being, there's no tolerance for extremely powerful signals that can be intercepted hundreds of light years away.

5) The great filter is nuclear technology. Expansionist civilizations that want to move outside their system have a bias towards war and massively weaken themselves multiple times times or even wipe themselves out before they can reach class II+. Non-expansionist civilizations sit at that comfy class II essentially forever, producing no signs of their existence outside of their tiny radio bubbles other than the infrared signature of their Dyson swarm.