Apologies if this doesn’t fit here, not sure where else to post something like this on lemmy
I think having gravity act like weather might be an interesting concept for a fantasy world, where each country has its own gravity patterns, some tend to be heavier some tend to be lighter, some are all over the place
For a few examples, there could be a desert with gravity so high you can get dragged down into the sand
Could be a country with gravity so low everyone uses personal aircraft that work like bicycles instead of land vehicles
Animals in higher gravity areas would have less dense bones, more muscle, etc and lower gravity would have far larger animals because they can support more weight
In a really high gravity area people might need exoskeletons to prevent long term damage
Sorry if someone else pointed to this already, but this could be relevant for your story:
“Unlike a body circling a single star, a planet orbiting a pair of stars would have to contend with two gravitational fields. And because the stars themselves orbit each other, the strength of the gravitational forces would constantly change.”
Ooooh and just when I’d kinda given up on a scientific explanation that works rather well
Good idea there
I’m so glad i could help!!
You wouldn’t notice any difference on the surface of the planet, though. The effects of the moon’s gravity on Earth are extreme in comparison.
Wow that would be bound to have some cool side effects. I wonder what the trees would look like
Sounds pretty heavy.
There’s that word again heavy.
Is there something wrong with the earth’s gravitational field?
Looks like one more reason to read the 3 body problem by Liu Cixin, which is a masterpiece of Chinese sci-fi. I am not gonna tell you anything more, as it’s a spoiler book sci-fi/cycle, and I advise you against reading anything about-it, just read-it
I think having people travel between them could be pretty weird. John Carter on Mars showed how going to a low gravity place would have some benefits (he could jump around like a flea). The people living on Mars though thought there gravity was “normal” because they’d always experienced it, however they did have simpler flying machines.
But if a creature traveled to a higher gravity zone they’d just be crushed like a human on the sea floor. Would all these monsters creep from the high gravity places and destroy low gravity civilizations?
Would the borders be sharp? What’s driving the differences? Dense unground metal deposits? Wizards?
I don’t think it’s horrible but there’s a lot to be worked out.
I like the underground ore deposit idea but it doesn’t account for gravity changing
I would imagine the gravity change would be gradual rather than sharp, so you wouldn’t just step over a border and be instantly crushed, they’d have fair warning to turn back
Though I imagine it would be an issue similar to how drastic temperature changes are an issue (for example if someone from Finland went to live in Texas and couldn’t deal with the heat or vice versa)
The animals from higher gravity areas would likely be dangerous, however their bodies would likely have evolved to be far less dense, bones could be broken more easily, they could be pushed around more easily/flung into the air and wouldn’t be well equipped to deal with that
Also, guns would still exist, creatures still wouldn’t be able to easily cross oceans so I imagine to a modern society they wouldn’t be too much of a threat in the same way that gorillas are pretty scary up close but aren’t really a problem realistically
Definitely are a lot of finer technical points to work out which is kind of the point of this post, just interested to explore the possibilities
If entering lower gravity areas causes bones and muscle to become less dense, then entering higher gravity areas causes bones and muscle to become more dense. Just look at what happens to those on the ISS after long expose to low g forces. The animals from high gravity areas would likely be shorter, but stronger in musclemass and bone density and/or structure. Higher gravity would also mean higher air density. So maybe the air would be more soupy and difficult to travel through. So perhaps the animals would be more aerodynamic. A stiff beeze would ruin your day!
Ooh interesting point, imagine you go on holiday to a higher gravity area and not only does it become difficult to hold yourself up (might need some kind of protective suit or exoskeleton for tourists to take some of the weight and prevent injury) but also get battered by the wind as you try to move
https://gpg.geosci.xyz/content/gravity/gravity_basics.html
If for some reason the whole planet were made of a less dense material except underneath my house was a massive deposit of gold or lead or something, yes, in reality, that variation in gravity can be measured.
https://bigthink.com/strange-maps/indian-ocean-gravity-hole/
Further reading.
Obviously in your fictional world there has to be a reason tiny anomalies are amped up to eleven. But yes, geology drives gravity variations.
I think the way I’d do it if I were writing a story about this world would be to just not mention the technicalities
Either it’s a medieval level fantasy world where they don’t understand how it works and it’s equivalent to how the sun works or weather works
Or it’s modern day and people generally don’t talk about the finer technicalities the same way people don’t go around casually discussing in detail what causes wind to blow or temperatures to rise and fall
Also, it’s fantasy so it could also just be it works that way because all poweful space cthulu decided that’s how it works
I don’t think your readers would just except that gravity is just smudged across the planet. Sure, some fantasy has iffy rules and little explanation, but something like this smacks more of high fantasy or even scifi.
You don’t need to have a geologist character boring your characters, but some level of lore explaining folke reasons for the variation is going to color your world and sell it.
It will absolutely help to have some hint at an explanation
But if the world is not at the the technological level required to figure it out then it wouldn’t make any sense for them to explain it scientifically
They could perhaps explain it as it is this way because the gods made it this way, or because it’s fantasy it actually could be because the gods made it that way (hence my magic space cthulu comment)
We would have different bones/muscles/joints.
What kinds of differences are you thinking? I’d have thought existing joints would be reinforced, limbs shorter, bigger muscles for high grav or the opposite for low
The dwarves live in high gravity, elves live in low gravity. :O
Lmao yeees would explain why the elves live longer too because their bodies are under less strain
Idk, humans couldnt survive gravity changing all the time. Probably have bones filled with material that changes density with gravity fluctuations.
yeah any sort of large change would kill us in our current form, like less oxygen in the atmosphere killing off a number of larger species in Earth’s past. this world would have to have adaptions like you mentioned.
The expanse goes into some interesting generational changes between people who live on earth, Mars, and in the asteroid belt. Belters are tall and scrawny and when they go to earth they can’t stand and the gravity crushes their bones, extremely painful. The only way they can be there comfortably is in water. I’d imagine different areas with different "weather " would have different types of adaptations and travel wouldn’t be as common/easy.
We already experience this on earth to a degree. The moon causes the tides and shore dwelling ocean creatures have to contend with surviving during the high and low tidal periods. Not really weather per se, but it’s something.
Gravity is also inconsistent across the earth, but to a very limited degree.
Good point, and the tidal currents do affect the weather to a degree. But a massive moon (or four) could be used to explain seasonal or even daily changes in gravity.
I think I read your title differently - as in, gravity would ebb and flow like wind or rain or barometric pressure or temperature. In normal days the gravity might be mostly constant, or may fluctuate a few percent as the day goes on, rising and falling over the diurnal cycle. But at times a gravity storm could blow through, causing wild fluctuations from just a few percent (or even reversing!) to a couple hundred percent, causing travelers to lose their un-secured cargo or to be pinned in place until the storm subsides. Locals would know the dangers and have things easily tied down, or beds for riding a gravity storm in relative comfort, but any huge storms people would evacuate, praying that the fluctuations wouldn’t destroy their homes or farms. (And now I’m imagining the end of O Brother Where Art Thou with the cow on the roof)
You read it correctly, that’s what I meant. Both different areas with different gravity patterns but also slight variations day to day like the weather with occasional freak occurances
I think reversal would be rare and restricted to very specific areas
Custom gravity beds would be cool. Personally I’d imagine they’d involve being immersed in some kind of ultra buoyant liquid designed not to cause problems with sustained skin contact
Ergonomic chairs, beds etc would be a must too
In real world terms it doesn’t really make sense, so you’ll need to dial up the “fantastic” when explaining/handwaving it. Ever read Sanderson? Because he does both “reasonably realistic except X” and “this wind is basically a God, whatever, fuck you” and makes both work pretty well.
Oh yeah I do like a good Sanderson book
My thinking was definitely not a realistic/ sci fi world where everything has an explanation, it was just “gravity is like this because it is” and leaving it at that
This actually a real phenomenon.
However, gravity isn’t the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass. NASA uses two spacecraft to measure these variations in Earth’s gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment (GRACE) mission.
But it’s practically unnoticeable on earth in real terms.
So there could be some sort of super dense mineral in some places. Or basically hollow earth in others.
This isn’t realistic really but you said it doesn’t need to be 100%
The problem with that is it doesn’t account for changing gravity patterns. I think as soon as you explain part of it realistically people ask questions about the rest and that becomes a whole scientific discussion
I’m more interested in the effect it’d have on society, evolution, etc rather than the practicalities of how it could happen in the first place personally
Changing gravity could certainly be explained by super dense mineral clusters. Once you get below the mantel the Earth is essentially a liquid… it isn’t so beyond belief to imagine a world where mantel temperatures are higher and everything below the thin outer crust is fluid… if we then imagine pockets of super dense material with weird magnetic properties it’d be possible for large clumps of that to float through the mantel and cause interesting variations in gravity. Gravity follows the inverse square law so a super density fluid traveling through the upper mantel would potentially cause some really odd effects.
You should read The Three Body Problem by Cixin Liu
Really cool concept, this is like an extreme version of our planet; Earth’s gravity is not uniform, there are variations in the gravitational field due to uneven mass distribution.
Was this planet artificially created? I think a hollow, planet sized structure with a small black hole inside that is off-center could give a very noticeable variation in gravity.
Probably pretty dead since you couldn’t have planets with stable orbits.
Variable gravity means its not our universe, So anything is possible.
Maybe the world is on the back of a turtle etc.
I was thinking exactly the same thing, discworld absolutely came to mind thinking about how space might work in this world
Excuse me? Starfield tells me that gravity drives are just around the corner…
If we don’t know what gravity does in this other universe, than talking about variable gravity would pointless.
It is called fiction. They are making it up, the only rules are the ones they decide work for the story.
It can be whatever they want.
See Star wars fighters flying in space like ww2 fighter planes flying in atmosphere.
It can be whatever they want
In fantasy sure. Doesn’t work that well for science-fiction, at least if you want it to be good.
Ah, A Critic!
And one who can judge without actually reading the story.
Impressive skill…
that well for science-fiction
Is Star Wars SF or Fantasy in your world?
I did literally state it was fantasy in the post
Mechanically, I’d modify the weather table in the DMG:
d20 Gravity
1-14 normal for the season/location
15-17 1d4 × 10 percent lighter than normal
18-20 1d4 × 10 percent heavier than normal
Example: a location that is 200% of normal (all weights doubled) could vary from 160% of normal to 240% of normal.
Low gravity + strong winds sounds like it would wreck everything and everyone. Hurricanes would turn into a disaster situation rather than a mild annoyance. Imagine cars flying around and ramming buildings.
Ooof yeah natural disasters could be way worse.
There could be entirely gravity based natural disasters too, imagine a gravity quake where gravity rapidly changes between high and low and the havoc that could wreak on structures and people’s bodies
Imagine a rare event like asteroid impact rare where a gravity inversion happens over water. A massive volume of water could rise up, arc over, drop onto a densely populated area. Imagine a small ocean falling from the sky onto a city.
In areas where that could happen they may need to build waterproof bunkers/homes
Completely scraping off any astronomical/space problems with this and just rolling along with the idea, which I like, I think your world inhabitants could be either:
- as you said, adapted locally
Or
- with a series of physical adaptations that would allow them to move between areas of different gravity. I think this would make things interesting because you said gravity as weather, and so you could play with the idea of gravitational seasons and gravitational storms or draughts.
Space is kind of a bust, I was thinking this is some fantastical universe where either it’s something like discworld or just magically the effects of the gravity variance are localised to inside the atmosphere
Would be interesting to think about what kind of variants of humans would adapt to their respective areas
I think the people who evolved in the highest gravity regions would become like supermen and end up ruling the whole world due to their superior strength. If not, it would at least give them a significant advantage while technology is still primitive. How would they defend themselves from attack?
See I kinda thought the opposite. I had thought all the wealthy elite would snap up homes in the nice cushy lower gravity areas and have financial power to control the working class living in the harsher, higher gravity areas
To begin with without technology absolutely the higher gravity people would be at the advantage. I imagine the lower gravity areas’ technology would be able to advance much more quickly though, less energy required from their society, so more going spare for research
Also, oceans still exist and as someone else has pointed out would be chaotic and dangerous to cross, so primitive societies would likely have a hard time
There’s also an advantage for low gravity people there in that it’s far easier for them to construct flying machines, so they would likely be far more mobile, and quite possibly first to make contact
Are you assuming there’s the one species who live all over the globe, like humans do? I was coming from the viewpoint that there may be related but divergent species who evolved to different gravity “climates”. I think that might affect the how things turn out to some extent.
Travel around the low gravity areas would be easier, but they would also only be limited to those areas due to piggyback weakness, whereas the people who evolved/grew up in high gravity would be able to travel the earth, so they would be the explorers, merchants and conquerors. Of course as technology advances this will all mean less and less
I can see the low gravity areas becoming prime real estate though, like you said. Talking geologically for a second, my first guess is that these would be higher elevation as the crust isn’t pulled down so much by gravity, and erode slower. Also precious metal deposits might(?) be closer to the surface too. If this is the case then this will give the low G folks to also advance in tech faster with greater access to useful metals. So if they’re quick enough maybe they can defeat the 'heavy’s with ingenuity.
I didn’t really come to a conclusion there did I? I just got more confused the more I thought about geopolitics…
Nothing wrong with not coming to a conclusion the goal is exploration
I am not assuming everyone would be the same physiology, however I imagine when travel becomes viable technologically people will start to mix and so will be varying amounts of high grav and low grav genetics, also I imagine a low grav individual who is born and grows up in a high grav area would end up suited for high grav through just building more muscle
That’s more or less my thinking with high/low grav dominance, much the same as in real life it’ll start out survival of the fittest and as society and technology progresses end up as smarter and/or more wealthy individuals in the lower grav areas taking over
