Imagine a terrestrial planet that is Earthlike in all respects, but it simply has more persistent cloud cover, such that seeing an open cloudless sky is miraculously unlikely, as unlikely as humans directly witnessing an asteroid impact.
No ground based astronomy.
No technological discoveries or culture that derives from ground based astronomy.
No celestial navigation on the ground.
Very different / stunted / more difficult cartography.
Technological civilization is capable of emerging, but it would not be able to well understand anything beyond the terra firma, not untill it generated aircraft capable of breaching the cloud cover layer, and then developed airborne observatories.
I wrote and tried publishing a short story about a species like that.
where only occasionally people on top of mountains see stars, and they chuck it as a consequence of low pressure. eventually they invented flight, and assume pilots going high enough to see stars are having cognitive issues due to lack of air.
They asked pilots to draw the stars they see, and they get different drawings (they sent pilots at different times of the year because they couldn’t ever expect stars to shift) and assume its proof that thise stars are a cognitive artifact.
Eventually a pilot swears they are real and can actually use then to navigate, skepticism, he proves it. brand new research field emerges.
Although the story focuses more on deep DEEP time an omniengineering. (A term I just made up because mega engineering is a concept way too small compared to the one in the story).
If you want I don’t mind putting that story in the conversation.
Post it for sure
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
I loved it. Thanks for sharing!
Given who you are, it means a lot.
That was a good read! I liked the pacing, the dawning not quite horror.
I liked it. It seems to fall apart at the end a bit but this is a really cool concept for sure.
if you don’t mind. could you elaborate? it’s ok if you don’t, I am rudely asking for free labor.
Seems like you were going for a bit of a twist ending where the letter is actually a threat. It didn’t really land for me.
The threat could be more concise and pointed which would give it more impact. Instead of speculating about how humans may react and then saying the aliens will counter it, maybe just say something that amounts to “resistance is futile”.
Its also not exactly clear to me what “the problem” is. Its that their race will someday come to an end? There is a lot to be said about this idea and I think you should explore the philosophy of that more. How does prolonging their existence save them? Seems to me like they’re still left with the inevitable.
the problem is the inevitability of the heat death of the universe, and the meaningless of existence if there’s no life at the end.
While the solution is to optimize the entire universe, though massive galactic engineering (using plausible physics) to maximize their research in order to break thermodynamics. I’ll try to make it clearer.
the ending is clear, but wether it’s good or bad is ambiguous and up to the reader, as they basically incarcerated humanity on earth and took away any possibility of humanity ever leaving earth. without any negative effects on the planet or humans.
Shit yeah go for it, I love those kinds of stories!
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
thank u, good read
I’d read it
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
Heck yeah, I’d read that. Feels like it could have been a Hal Clement story idea.
https://docs.google.com/document/d/1PTzQQKXLnBL1ICUK8IYa8YoUSD2ncQk5-jse-FaFPAI/edit?usp=drivesdk
tried putting the text in a comment, but it’s too long, I enabled comments.
Thanks! Will review.
no pressure. and be honest, if some parts are shite tell me. and especially if it is all shite.
“Nightfall”, by Arthur C. Clarke is a short story based on this premise.
Except in the story it’s a complex multiple-star solar system that makes it very rare for all suns to set at once.
Edit: It’s actually Isaac Asimov.
Augh!
You’re telling me there’s an Arthur C Clarke short that I missed?
Damnit I am losing so many nerd points today.
It’s an Isaac Asimov story. An excellent one I cite frequently with regards to human ability to cope with increasing rate of change.
Whoops! That’s my mistake.
points regained, even doubled!
Project Hail Mary has a bit about this, don’t want to say more to keep it spoiler free.
Haven’t seen it yet, I appreciate the nonspoiling =D
Definitely read the book. The book is about the existential elation at discovering a solution to a dire problem, so knowing a poorly-communicated version of every solution will likely ruin the book for anyone serious about the hard Sci-Fi.
Well, as soon as they invent radio and experience interferens radio astronomi will evolve… I guess?
This is a Doctor Who Christmas Episode
I have written a post about exactly this phenomenon, arguing that that’s how most animals/insects see the world (assuming their sense of vision isn’t good enough or they just don’t care to look up). Apparently i was wrong, even insects can see the stars and navigate due to their light (milky way navigation).
I would instantly buy your book!
Hah, I haven’t written one, but maybe check out Arthur’s short story elsewhere in the comments!
He’s got uh… watermelon emojis in his name.
That just sounds like a hollow world…
Jokes on us: Because of the gravity issue, alien life on such planets jumps right to stargate technology.
“They spent almost a thousand years fooling around with rockets!”
Uhh, one stargate doesn’t go anywhere.
You can accelerate it into space at g forces which would liquify living beings, perhaps?
Using what?
(Remember the premise of this subthread is that they’re doing this instead of rockets.)
Bah, Stargates are just propaganda from the rocket first civs.
There is no need to send a gate in advance, just use your favorite teleportation mechanic.
I’d say they stand a whelks chance in a supernova of that succeeding.
Actually I’m a marine astrobiologist and that chance is really really high
Just frisbee those things in random directions until one works.
that’s why you communicate via radio waves to other life in the area and build a network
Waddayamean a « ro-ket »? You guys don’t use the three seashells system for liftoff?
Haha he doesn’t know how to use the three sea shells.
If the planet is massive enough, getting to orbit becomes a real challenge because fuel consumption scales roughly exponentially with the mass of a planet (delta-v formula, rocket equation).
This leads to an almost sharp cut-off for the maximum mass that a planet can have so that a rocket which utilizes chemical fuel (e.g. methane+oxygen) can still reach orbit successfully. This maximum mass is roughly 10^26 kg.
For reference: Earth’s mass is around 6*10^24 kg.
While other propulsion types exist, such as nuclear + ion drive, these propulsion types are significantly more complicated.
Interestingly, if a planet is too small, it cannot hold an atmosphere. There is a surprisingly sharp cut-off minimum mass for this as well, at roughly 10^21 kg.
We really are in the Goldilocks Zone, aren’t we?
Well, yes. In the middle of the goldilocks zone that is based on the environment we are adapted to is where you would expect to find us :p
Haha fair point.
Only if there are not sentient life forms on that planet capable of getting off it
If anything, it’d be a bias towards spaceplane designs over straight up rockets. As long as the atmospheric density relative to the gravity supports it, offloading some of the acceleration to high atmospheric flight using ram/scramjets can massively reduce the launch vehicle mass (don’t need to carry oxidisers for the flight stage).
That being said, it also would be a bias against high orbits and space exploration in general; safe re-entry is tricky enough on earth.
I suspect that atmosphere composition makes different options more or less viable.
The difficulty/cost getting to orbit probably also would influence where a space elevator lands in terms of developmental priority.
I did not know that. It’s because it interferes with gravity? I’m dumb sorry
Not enough gravity, the atmosphere will drift away from the planet with the help of solar winds etc. Too much gravity, and the ammount of fuel you need to leave the plannet weighs more than the rocket the fuel is being used to lift can carry.
Even in our current ships, most of the fuel used to leave orbit is really used to carry the other fuel you need later.
That’s interesting! Thank you!!
The tallest people on that planet

Imagine all the room for activities! (Trench warfare)
We make a mistake by assuming that life forms would likely be at the same scale as us. Larger planets would likely develop life forms appropriate for those planets instead of appropriate for ours.
Uh… being smaller or larger does not really change the laws of physics… if the gravity is too high, no fuel has enough energy density to escape the gravity of the celestial body.
If you need 150kg of fuel to get 100kg worth of matter to escape velocity it does not matter how much fuel you have. It will not ever be enough to leave.
I love how Earthlings assume that all of the variables on other planets would be exactly the same as they are on Earth, leading them to believe they have any idea about what other species might be dealing with on other planets.
It’s cute.
You do know that they couldn’t even estimate the functionality of the heat shield of the spacecraft that just splashed down on our own planet? That they had to literally increase the angle of entry because they couldn’t accurately predict the behavior of a craft on a planet that they’ve been studying for all of recorded time?
Are the laws of physics actually a thing? Clearly. But here’s the thing: The kinds of organisms that might exist on such an object could be absolutely massive compared to us. And for us to assume that we would have an understanding of the laws of physics that would be anywhere near as great as animals that might have brains exponentially larger than ours? And hell, the energy that might be available in such environments? We don’t know what’s in space around these objects, or whether there are any kinds of characteristics which would make unconventional (to us) means feasible to get off of the planet.
For all we know, they could be scientifically a billion years ahead of us and might be able to manipulate time or matter in ways we couldn’t conceive. It hasn’t even been 100 years since humanity learned to harness nuclear power.
No, there are too many variables. Life on such planets could evolve in countless different ways, and the different characteristics of the environment, and the resources on and around the planet provide too many options for us to be wrong.
And before you respond that I am arguing against science, no, it’s actually your opinion that is arguing against science. History is filled with organisms finding unusual solutions for problems that were long deemed impossible to solve. And when people said “Well, I don’t think we have enough knowledge to make such a firm claim,” history is also full of people like you who insisted that there was no way. And history is full of people who walked into the room, picked up the rules as they wrre known to that point, and basically flipped over the game board.
You are literally the person arguing that a scientific process is impossible given environmental variables because they don’t match the laws of physics.
But you don’t understand that you are arguing not for the infallibility of those laws, but for the infallibility of our understanding:
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of the laws as we understand them
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of the chemical makeup and geography and resources of the planet
And all of that is not even to mention that the estimates of whether the planet itself was capable of supporting life have literally changed relatively recently because humanity developed a better understanding of science.
If I had a nickel for every time someone proudly claimed something to be impossible because it hadn’t scientifically been done yet I would be richer than Elon Musk.
Unlikely? Well, look. I’m not willing to make statements about humans’ accuracy when studying objects that far away. I will acknowledge that it’s not something that would be easy for us to accomplish given our current knowledge, but my humility can acknowledge that that seems to say more about US on this planet than it says about any kind of organism that may have developed on such a planet.
You’re treating scientific uncertainty as if it means “anything is possible.” It doesn’t.
We don’t assume variables on other planets match Earth. Astrobiology, planetary science, and exoplanet studies are built on the opposite assumption: that most planets don’t resemble Earth. When scientists estimate what life or civilizations could be like elsewhere, they work from measurable constraints (gravity, density, stellar flux, atmospheric composition), not wishful thinking. For example, we know that: A planet with 3× Earth’s gravity constrains organism size, structural strength, locomotion, and escape velocity. A planet with a dense hydrogen atmosphere changes chemistry and energy availability. A star’s light spectrum dictates photosynthetic possibilities. These aren’t guesses. They follow from basic physics and chemistry, which apply everywhere.
“They misestimated a heat shield” ≠ “we don’t understand planetary physics.” Engineering uncertainty in a single atmospheric re-entry doesn’t invalidate the underlying physics. Weather variation, material tolerance margins, and modeling limits don’t erase Newtonian mechanics or thermodynamics. If your argument were valid, airplanes would disprove gravity because turbulence is hard to predict. Scientific uncertainty does not mean lawlessness.
An organism the size of a mountain on a 10g world can’t simply evolve because “maybe their brains are bigger.” Biology cannot override: stress limits of matter metabolic scaling laws biomechanics gravity energy density limits An advanced species might innovate, but it doesn’t get to ignore basic constraints. A billion-year-old civilization would know more than we do, but they still can’t accelerate to escape velocity without energy, or support infinite mass with finite-strength materials. Knowledge does not nullify physics.
For all we know, they could be scientifically a billion years ahead of us and might be able to manipulate time or matter in ways we couldn’t conceive
This is pretty much just “We can’t rule out magic, therefore you’re wrong. Science can only operate on what’s known to be possible or what follows from tested theories. Speculating about physics-breaking abilities isn’t meaningful without evidence; it’s equivalent to saying “you can’t disprove dragons.”
When scientists say “a civilization on a super-Earth would struggle to reach orbit,” they base it on: the planet’s mass and radius → calculates escape velocity atmospheric density gravitational load on structures realistic energy sources We don’t need to know the exact geology to know that a planet of a given mass requires a minimum amount of energy to launch mass into space. That’s just conservation of energy.
Saying “we don’t know everything” is true. Saying “therefore any extreme scenario is viable” is not.
You’re treating scientific uncertainty as if it means “anything is possible.” It doesn’t.
Except I’m not.
I am treating things as if we are a species who barely has enough knowledge to send a small group of individuals off of the planet, and I am stating that while humanity seems to have a fairly okay ability to do that(and barely get to the next rock over), we probably shouldn’t be speaking with the confidence as if we wrote our masters thesis on interstellar travel. The moment humans stop having tons of massive scientific discoveries about space travel every year, that’s the point that we might have a good argument that it’s impossible for someone to escape a particular planet.
At this point, we can’t even confidently say that we know what that planet is like. Hell, up until recently, they believed that planet couldn’t even support life.
I am not questioning the laws of physics.
I am questioning that humans’ understanding of them is complete.
But you go on with your bad self, with your complete assurance that nothing will ever get off of that planet. The good news is that both of us will be dead before anyone even gets to know that it’s been tried.
You can question whether we know everything, that’s always fair. but saying “maybe something will escape a high-gravity planet because we don’t know everything” is like saying “Maybe we’ll find out 2+2 isn’t always 4 because math isn’t complete.” Possible? In a philosophical sense, yes. Useful? Not really.
Most “revolutionary” discoveries refine our understanding, not overturn the foundation. Relativity didn’t make Newtonian mechanics wrong. It expanded the domain. Quantum mechanics didn’t nullify classical physics. It explained small scales. Dark matter didn’t erase gravity. It suggests additional components.
When you argue, “We’re still making discoveries, therefore our predictions about what is possible are worthless,” you’re ignoring that the discoveries rarely contradict established, experimentally validated constraints.
You aren’t offering any reason to believe our current models are wrong, only that they could be wrong because science is incomplete. By that logic, any claim can be doubted indefinitely, and no amount of evidence ever matters.
But i truly like your child like enthusiasm for space. You throw intresting ideas around, but so far they have been only wishfull thinking. Difference between science, fantasy and religion is, that when something new is proven in science, people accept it, but it needs proof first.
In fantasy people throw crazy ideas and have fun, knowing they are not real.
Religion is when you have “faith” that something is true.
You are living in somewhere between fantasy and religion with your ideas. There is nothing wrong with it, but it makes discussions meaninless, because while i try to argue based on science you dont have any limitations and can just say. “We dont know, maybe they can manipulate time”. Its really convinient isint it.
Sure thing, Lord Kelvin.
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Damn. As if the atmosphere wasn’t enough of a hurdle already, they gots dumpys too
To everyone saying launching to orbit is impossible, I have two words: Orion Drive
No rockets maybe, but what about a space elevator?
Those would be harder too though. Right now we humans don’t have a material strong enough and the higher the gravity the stronger the material you would need.
space elevators aren’t feasible, but a space pyramid is. just build a really tall pyramid, some kilometres high, it would work. though expensive.
I mean, that’s probably what’s keeping US down. The aliens out there are probably from worlds with low enough gravity to make a proper space elevator. And they never come to visit us because our world is just too damn big, you’d need some kind of controlled explosion to get back up from a gravity well that deep.
You would need to get into orbit first to start the process of making it. It could make it easier to get into orbit once you have it but it doesn’t eliminate the burden of needing to get into orbit at least once before it’s set up. Likely more than once since failed attempts will require you to start over.
That’s what the martians said about Earth
A while back I read an article that stated earth was about as high G as you could get and still be able to get to orbit with chemical rockets (barring huge leaps in tech). I could be remembering that badly though, so take it with a grain of salt
You underestimate the motivation of sentient species that just want to get away from other members of its species.
reminded me of Ad Astra and its soul crushing revelation that the scientists haven’t found alien life despite all the fancy tech.
Or it’s likely a mini-Neptune type planet with more atmosphere than ground and therefore likely won’t have complex life at all. Or complex life able to try and do that.
mogged
still, they could be detectable, radio signals and stuff like that, afaik we have sent radio signals (not just inadvertently) from the ground
















