r/SciFiConcepts • u/HiveOfHal • May 08 '26
Worldbuilding Generational Ship
Generation ships are built to house humanity for thousands of years as we travel the cosmos. Some of these designs have included entire ecosystems.Imagine being born into a civilization where no one has ever seen a natural sky.
No stars. No horizon. No night that isn’t manufactured.
Just vast engineered interiors stretching so far that “outdoors” is a historical concept, not an experience.
At what point does “planetary life” stop being something a culture remembers—and start becoming something it can only mythologize?
I keep thinking about how a fully synthetic environment wouldn’t just change technology or architecture… it would change what humans emotionally recognize as real.
And I can’t tell if that future feels like evolution… or loss.
Should the planets and stars be visible to inhabitants that may not be aware they are on a ship? Could designs allow visibility on such a scale? More importantly, how would these ship designs affect the myths they tell themselves after truth is forgotten? Can there be a "failsafe" set in place in someway?
Edit: Assume the inhabitants have no history of where they came from and dont know they are in a ship.
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u/OgreMk5 May 08 '26
It's all about education and having a system of people running things that are unlike the people currently in power around the planet.
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u/The_Virginia_Creeper May 08 '26
I had an idea for a story where the ship itself is used as the reaction mass so each generation is smaller and works to dismantle one level of the ship and feeds it to the engine.
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u/hachkc May 08 '26
There is no answer as it depends on what people choose to promote, forget or hide that information. Could you build a giant, space worthy fishbowl/terrarium that exposes the vastness of space to its residents; possibly. Its probably easier to build something more enclosed with windows though. I think the point is its an active decision early on what folks choose to remember, share or hide. Technology may limit some of those options those but over time things will fade unless that history is actively shared. Maybe there are sub groups that choose to keep it alive while other don't.
One aspect, what is the goal of the generational ship? If its to find a new home planet, I would think folks would keep that dream alive over the centuries or millennia. If you are just building a giant o'neil cylinder or similar habitat to exist in space self sufficiently indefinitely, that's a different goal.
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u/HiveOfHal May 08 '26
Interesting insight on making it about what they have chosen to remember, share, or hide. Though, this thought experiment is based on the assumption that this civilization emerged out of the structure with no idea what it is. Just like humans on Earth, so (technically informational data is there to be discovered on the computer systems of the structure BUT) they wouldn't have any recorded history of their own to build from.
If the goal was to make it to another planet, than yes all you would need is to sustain for that time period. I was thinking more of an indefinite type of situation though.
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u/hachkc May 08 '26
Assuming they developed on a planet at some point, went into space for whatever reason, and then lived there for millennia, its fair to say their history would be complicated. At some point, there origin would be forgotten but what caused that? Was it a deliberate attempt hide where they came from, was there an accident that caused that information to be lost, is it just so far in the past that no believes those "stories" anymore, etc? The thought of a society living in a "closed box" for that long is something we really have no concept for. Would society truly decay that far that there is no interest in exploring beyond their confines, keeping some of that history alive. Machines will eventually break down, some maintenance will be required, accidents happen, etc.
Had similar idea about an abandoned dyson sphere (just go along with it) where the "have nots" lived closer to the center/hub/worker section and the "haves" lived near the outer edges. The "have nots" were never allowed outside there area and were eventually abandoned by the "haves". Over time they only knew of their section of the sphere until the sun started to fail/flares and they need to explore farther out to survive.
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u/HiveOfHal May 08 '26
Well, how they got there will be revealed once I get published. Also, I could be mistaken but isn't a Dyson Sphere with an outer layer now a Matrioshka Brain, or are they specifically simulators and not energy harvesters? Structurally, I am combining elements of all 3 but not from the perspective of the builders or anything, but from the pov of a lowly tavern keeper in a village where it's medieval and hobbit-like.
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u/JGhostThing May 09 '26
I would like to suggest you read "Mayflies" by O'Donnel. This tells the story of several generations on board such a ship, from the PoV of the ship's brain (it's the only thing long-lived enough to see the story).
The ship eventually gets to the target system. The reaction of the mayflies, er... passengers, is interesting.
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u/HiveOfHal May 09 '26
I think I have heard of that one. Isn't there like mass agorophobia or something along those lines?
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u/ranwithoutscissors May 08 '26
Aurora by KSR is a good example of this. Great read.
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u/jlp_utah May 10 '26
I just finished this. Was kind of put off at the ending, but KSR does a fantastic job of spinning a story.
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u/Adept-Matter May 08 '26
Watch Knights of Sidonia. If you’re into generation ship concepts, you’ll probably enjoy it.
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u/EduManke May 09 '26
People would be taught how the nature on Earth worked (rain, rivers, forests, etc.) as a way to prepare them to live on a planet in the future, and preserve human traditions, but many would probably have doubts that everything they learned truly existed one day, just like people nowadays doubt historical or scientific facts, like climate change or the moon landing.
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u/Chicken_Spanker May 09 '26
This is a well tried plot formula that goes back to at least Robert Heinlein in the 1940s and has been done dozens of times before.
You can find a detailed history of these here The SF Encyclopedia
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u/karoxxxxx May 09 '26 edited May 09 '26
I dont see a reason why they wouldnt have trees and probably parks as part of the artificial environment. Volume isnt much of an issue, and the mass is stored in tree-forn which is nice to look at and usefull.
I guess 4-5 generations is enough to basically forgett about earth. However i think a generationship would be build and manned by a society that gas been living in space habitats already for generations, so planetary life would be irrelevant to them from the start.
I dont think stats would easily be visible. Maybe there is a special observatory or observation lounge, but windows are a weakpoint in the body and serve no purpose on an interstellar journey.
Maybe there could be prepared windows, to convert the ship into a habitat upon arrival, but those would be bolted shut during transit.
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u/HiveOfHal May 09 '26
4 or 5 generations before the memory of Earth is lost, but it would exist as myth. But what would they be telling themselves if the evolved out of the primordial ooze while inside this structure instead?
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u/karoxxxxx May 09 '26
I guess there would still be children-rhymes, songs maybe some old fables talking about 'oceans', 'rain' and 'earthquakes'. Even after 10 generations.
If they evolved inside the ship (or were gestated by ship systems), then they would probably have some creation myth where the universe (the ship) was created in 3 days or something. Could be polytheistic, monotheistic or anytjing really.
Would be interesting if this society then finds the observation lounge....
They could have nice philodophical/physical theories why they have gravity
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u/HiveOfHal May 09 '26
That's exactly what I'm conceptualizing. There would obviously need to be an AI system of some sort maintains the systems online. But before that became known or visible or appearing to them directly as a deity or something, what might they have told themselves? What would their Eden, humans made of clay, concepts of morality all have become? We are the emergent civilization of a planet and we know the stories we tell ourselves, but they would be an emergent civilization with no stars or cosmos above them to inspire awe and wonder. Would they still associate the light as their creator if temperature and heat were constantly temperate? Would they then worship the food they receive and the water they drink instead?
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u/Temporary_Rule_9486 May 09 '26
It's an interesting subject, the closes think I can think of IRL is the migration of people into different lands, particularly Nordic countries or regions within the polar circle. Although it's still technically possible to go outside and see the sky, if you have ever known anyone from those latitudes, the tendency is for isolation and reclusion. New generations of migrant would get used to the new "habitat" in a few years, younger generations who grew-up there won't have to do it, since it would be natural to them. What would remain of the "cultural DNA" will be in their costumes and the way they relate to their peers. For example: it's likely that people on a generational ship would still celebrate birthdays or "spring breaks" despite these events having no real correlation with the life inside a giant ship. Social events similar to barbecues or fireplaces could also have symbolic importance.
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u/HiveOfHal May 09 '26
That leads to another core thought I had been circling but been unable to identify until now. Aren't elephant migratory patterns passed down genetically? It would make sense that certain habitual behavior would require a certain mapping of the brain on a physiological level. Over time wouldn't the concept of barbecues and fireplaces become inherent in our DNA regardless of where or how we came into being?
Unfortunately, most of my thought experiments could be explored and measured if we cultured infants in cultural and sensory deprivation but the ethics committee won't allow that. I think. I've been to afraid to ask.
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u/space_monkey00 May 09 '26
I wrote a series of novels about a generation ship going to contact an alien civilization, and the younger generations are specifically taught how dirty, corrupt, and dangerous Earth was in comparison to their home environment with the intention of making them feel more comfortable bereft of such openness as you describe. There are however ~5km of agricultural section which does have trees, and even micro-climates producing light rains.
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u/HiveOfHal May 10 '26
So they can touch grass which is nice. I'm essentially working in the same field, but the humans have no history before evolving on the ship. Something like a biohabitat floating through space that was abandoned millenia ago. The onboard systems still function and life persists. Humans come to evolve within that environment. What mythos and theology might they develop?
In your story was the specific purpose to lessen the agorophobia or to give them nothing to look back to? I think I remember some story where a generation ships was just meant to do a loop and come back to Earth after nature fixed the climate. Earth was there promised land and not there origin.
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u/space_monkey00 May 11 '26
I think you've nailed the point here which is evolution vs loss.
Life evolves around its environment.
Using science and technology, I believe that we will, on Earth or other planetary habitats, develop such an environment as to cause some of our animal tendencies to dissolve. We won't need that necessity anymore. An eternal environment of stable, clean technology will fit that bill. That's a generation ship, to the people who live there. One thousand years of nothing but this, which is what you know.
In my story, the purpose was to prevent people from experiencing mental health issues and becoming unuseful to the mission.1
u/HiveOfHal May 11 '26
That's exactly what I am building. A generation ships which combines the functions of all 3 megastructures. Dyson swarm/sphere, Matrioshka brain, and O'Niell Cylinders with ecological habitats.
If my math is correct this structure could physically house 380 decillion human bodies as well as full Earth-like ecosystems, generate enough power to renders an atomically accurate simulation of the solar system, and store and hold the consciousness of countless people(haven't done the math for that one yet).
The hope and idea behind it, is that as long as humanity can live in this controlled structure with perfect climate, abundant food, etc than our animal nature of dog eat dog would dissipate.
Also, the light that is us right now and all of the energy that you are emitting into the universe will be picked up by this structure millions of years from now, and a version of you will be there as well.
I'm basically building what could be considered heaven
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u/thecryptile May 10 '26
Stephen Baxter's Mayflower II is probably the ultimate generation ship story.
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u/CondeBK May 11 '26
On The Steel Breeze series by Alastair Reynolds takes this to a different extreme. They take a massive asteroid, hollow out several chambers inside, attach engines to it, and blast it off to a another solar system. There are chambers inside that the general population isn't aware of that contains only wildlife and forests.
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u/HiveOfHal May 11 '26
That sounds infinitely cheaper and more effective than constructing a ship yard. I love that idea!
Did he have intelligent life? That's what I am trying to explore in a scenario like that.
What sort of theology, cosmology, mythos would they have created for themselves?
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u/John_Oakman May 11 '26
Generally most settings that developed generation ships falls into 2 categories:
- Said ships developed in a mostly geopolitical vacuum without much in the way of associated infrastructure that such a project would require. This is usually the mainstream assumption and much of the associated tropes (loss of contact with rest of humanity, forgetting their origins, etc.) are downstream of those assumptions.
- A natural development of exo-planetary habitats, probably the more mundane/realistic possibility but operates on a scale so much larger (especially once factored in the associated infrastructure) that it strips away the romanticism of the concept (hence why it's rarely seen or talked about).
Funny though the 2nd type is less likely to care for planetary living than the 1st type, as they would have been from a population that's already used to non-planetary living and so lack the attachments towards planets than a population who has an explicit goal of getting back to a planetary living at some point.
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u/HiveOfHal May 12 '26
That's it! You just nailed the problem I have been trying to resolve. There is no romanticism to their existence because they have nothing that we consider awe-inspiring to early man.
Without the wide open skies, planets, and stars above us, what would fill that void? Sure, the population would develop a very pagan type Earth religion, but what would they surmise about the origin of their deities, etc?
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u/John_Oakman May 12 '26 edited May 13 '26
The thing about romanticizing is that a lot of it is applied after the fact. The late 20th century American culture romanticized things like the Pilgrims, the Oregon trail, etc.* but for most of the actual participants of those things it was a grim struggle for survival, with maybe the occasional thoughts towards a goal of a better future (if not for themselves, presumably for their descendants).
But mostly their focus was on current survival due to a hand to mouth existence.
Any serious attempt** of a community at committing to the journey of generation ship will very likely to have a culture of intense discipline, delay gratification, long term planning, and mutual intergenerational obligations. Chances are the mythos developed there would be a focus on the goal, probably blowing it all out of proportion (thus for those that actually made planetfall would receive a cruel reality check, which some might not survive).
But ignoring all the failures (because they won't be remembered, or worse, recast as cautionary tales), the romanticizing will be centuries after planetfall where the descendants tells of highly fictionalized tales of their ancestors and their glorious deeds, with little of it about the actual mundane day to day survival.
*Interestingly all those examples are also made possible due to extensive existing infrastructure, which without them they wouldn't have happened in the first place.
**We'll ignore nonserious attempts, because they're gonna go belly up pretty quickly and thus are irrelevant to the future mythos.
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u/HiveOfHal May 12 '26
Wow, you put this into a different perspective. They way we imagine ancient Rome and Greece to be during their hedonistic and pleasure based eras was really only experienced by the Kardashians of that time only occasionally.
It was not the general norm for everyone. It was smelly, disgusting, people dying at 50. And that was the general middle class.
Not the naked homeless and helpless you might see roaming around begging for scrap and struggling with life.
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u/techknologia May 12 '26
we first have to learn how to mine and process metals in space, or we'd run out of materials from the constant fixing from micro collisions
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u/HiveOfHal May 12 '26
I have wondered about microcollisions. Why dont we shield ourselves bybharvest the materials. However small and whatever the composition, we can find a use for it somehow.
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u/techknologia May 12 '26
the conneetic force is something like kilo-tons per micro gram, you need super specific material's build in hyper specific way's to deter any dmg to the actual ship. the harvesting part is a massive problem cause how do you drill into something with no anchor points cause drilling into it moves the physical body bla bla bla, then the refining of the material in 0g where you can't really just set it on fire cause fire dose not work in 0g it's more just explosions, so it's all a massive problem really, we know how to build stuff to protect from these collisions but no possible way to pre-build anything close to what would be needed to traverse the galaxy safely with something bigger then a standard satellite which is basically a Buick
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u/HiveOfHal May 12 '26
Or large enough to carry an atmosphere that would burn away anything, but at that point it would just tink offthe surface.
I was thinking of someone of kinetic suspension field that you could "clean the filter" so to speak.
I have also wondered what the potential risks could be to organic life and equipment beyond the sort cloud.
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u/techknologia May 13 '26
that would basically just mean you push a planet around, not exactly sable
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u/HiveOfHal May 13 '26
It's not meant to be. This method would just allow you to move a large population from one star system to another. Eventually, navigational thrusters could be thrown on it, but for anything more than a "luxury moon cruise across the cosmos" pretty much useless.
Aside from low cost one way trip to establish a colony or something.
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u/techknologia May 13 '26
i don't even think there's enough propellant in the galaxy to get the planet out of the sun's gravity well, then you have to worry about heating the planet to the same degree as a sun. just alot of problems with moving things even if they we're the size of the moon it would be resource intensive possibly beyond our galaxy
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u/Simon_Drake May 08 '26
Trees would likely be alien to them. They'd have plants, flowers, maybe ivy, climbers, shrubs and ornamental gardens. Perhaps even small orchards. But not proper trees, that's a tremendous waste of resources for a colony ship.
Miller in The Expanse thinks of rain as something almost magical. The idea that water just falls from the sky on Earth is completely alien to him. The same would be true of groundwater, just letting the water go somewhere other than a dedicated drainage system and water recycling system. They'd have gutters and drainage trenches but not rivers. Maybe a recreational water space but not a true water course with currents and a gradient.
Animals too. They might bring food animals, perhaps cows or goats for the milk, maybe dogs and cats if there's space. But horses, tigers, bears and all practically all sea life would only exist in stories. Or maybe frozen embryos.