this post was submitted on 30 Oct 2023
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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

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[–] Saigonauticon@voltage.vn 74 points 10 months ago* (last edited 10 months ago) (2 children)

Instead of wind mills, you could have gravity mills. Pump water into a higher-altitude reservoir on low-gravity days, and let it flow down -- turning a turbine -- on high gravity days. At least electricity would be cheap.

Or if it varies by region, pump water horizontally (or let it flow slightly downward) from a high gravity region to a low one. Then pump the water upwards there, then horizontally again to the high gravity region. Then let it fall down to turn a turbine that runs all the pumps -- perpetual motion (ish)!

Predicting tides becomes hard. Everything is going to be really windy all the time, as the atmosphere expands in low-gravity regions and contracts in high gravity ones. This makes tall buildings impractical, as they would also have to be built for some maximum gravity rating on top of the constant gravity storms.

The oceans would be weird, and violent. Hurricanes might get far more powerful than what we deal with, if the right gravity conditions occur.

For any sort of civilization to emerge, gravity would have to change/vary really slowly. I don't even want to think of orbits. Kerbal Space Program would be like, really hard in that universe.

[–] flashgnash@lemm.ee 15 points 10 months ago (1 children)

Oh man I didn't even think about atmospheric pressure, could giant windbreakers not potentially be constructed to lessen the effect of this wind?

Or maybe in this fantasy world as it has formed originally with these gravity differences there are lots of natural windbreakers, raised areas and lowered areas, mountains etc due to earth getting compacted to different levels

I would imagine the gravity variance within an area would be fairly mild by comparison to the differences between areas - like how you tend to get warmer temperatures near the equator but can still get variances in temp around that

Oceans may become terrifying but it may be easier to travel by air anyway, instead of trying to travel by ocean you could attempt to plot a course through lower gravity areas and avoid the higher ones Could even spawn some badass hardened sea captains that are required to make certain journeys as they are impossible by air

[–] Saigonauticon@voltage.vn 5 points 10 months ago (1 children)

Well if we are going for science...

Giant constructions will have a lot of wear and tear under varying gravity. On top of that, high winds and frequent storms are likely to weather geographical features a lot, making them more flat. In a fantasy world, you can just magic things away, so that's fine :)

I don't know about you, but I would find constant high winds fairly terrifying for air travel. Perhaps they are high enough to permit wheeled sailboats on land? That would be creative!

[–] flashgnash@lemm.ee 3 points 10 months ago* (last edited 10 months ago) (1 children)

Wheeled sailboats would be very cool, for air travel could have an airbender-like group, a bunch of monks who dedicate their lives to studying the way the wind changes who can instinctively navigate it and use it to their advantage

Aircraft could essentially just be a hang glider with various mechanisms for steering and best catching the wind

I think if I were writing this as a book I'd have to conveniently ignore/find a way to explain away the wind problem though as it would turn the world from a kind of whimsical interesting place to a deadly, unforgiving one.

I also quite like the idea of low gravs having low tech man-powered aircraft instead of land vehicles and wild wind would make that rather impossible

I quite like the idea of wild wind over the ocean for those air nomad people but that might be a case of wanting my cake and eating it too

I guess if I were going the magical route there could be a group of wizards in every town or city maintaining some kind of force field to keep the wind out, taking it in shifts. Could be a major terrorist threat if someone were able to take them down

[–] Saigonauticon@voltage.vn 4 points 10 months ago (2 children)

I suppose wheeled boats are just... cars with sails? Sailcars? Wind chariots?

Hm, one thing I didn't think about was magma, if the variations are not so small. Going to have more volcanic eruptions, as fluids get pressed out of high-gravity regions and into low-gravity ones (creating big mountains that grow and tumble into the high gravity wells like some sort of horizontal convection?). Earthquakes too, as the high gravity regions sink and the low gravity ones rise creating shear force. I bet the planet would be more "lumpy" than your run-of-the-mill oblong spheroid. I wonder what continental drift would be like?

With that much irregular magma flow, I bet the magnetic field would be weird if it could sustain one at all. Maybe as 'cells' where the eruptions occur in low gravity regions, then gets pulled into high gravity regions where it compresses, heats due to radioactive decay, melts and is pushed back out into low-gravity regions. So maybe you'd have 'local north' for the cell? Or a very weak magnetic field overall (yay radiation)? I don't really know on this point.

Oh and exceptionally high-precision clocks won't be useful except locally, because of the effect of gravity on spacetime, but that doesn't seem so bad. Low precision clocks based on pendulums won't be useful at all! Spring escapements should be fine though.

Maybe it would be better to live underwater?

Wow all of that, and home ownership still seems more accessible there than here. I bet real estate prices are a bargain!

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[–] xmunk@sh.itjust.works 5 points 10 months ago (1 children)

If the gravity variation was controlled by a super dense material responding to magnetic fields in a weird way then you might have stable-ish conditions at the magnetic poles.

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[–] Ulvain@sh.itjust.works 39 points 10 months ago (3 children)

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."

Source

[–] flashgnash@lemm.ee 14 points 10 months ago (1 children)

Ooooh and just when I'd kinda given up on a scientific explanation that works rather well

Good idea there

[–] Ulvain@sh.itjust.works 5 points 10 months ago

I'm so glad i could help!!

[–] lolcatnip@reddthat.com 9 points 10 months ago

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.

[–] SubArcticTundra@lemmy.ml 4 points 10 months ago

Wow that would be bound to have some cool side effects. I wonder what the trees would look like

[–] TransplantedSconie@lemm.ee 21 points 10 months ago (1 children)
[–] rindo25@lemmy.world 15 points 10 months ago (1 children)

There's that word again heavy.

[–] Pons_Aelius@kbin.social 6 points 10 months ago

Is there something wrong with the earth's gravitational field?

[–] Overzeetop@beehaw.org 19 points 10 months ago (1 children)

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)

[–] flashgnash@lemm.ee 5 points 10 months ago

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

[–] neptune@dmv.social 17 points 10 months ago (2 children)

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.

[–] flashgnash@lemm.ee 7 points 10 months ago (3 children)

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

[–] neptune@dmv.social 3 points 10 months ago (3 children)

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.

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[–] Ziggurat@sh.itjust.works 16 points 10 months ago

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

[–] foggy@lemmy.world 15 points 10 months ago (1 children)

We would have different bones/muscles/joints.

[–] flashgnash@lemm.ee 5 points 10 months ago (3 children)

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

[–] Gardienne@lemmy.world 10 points 10 months ago (1 children)

The dwarves live in high gravity, elves live in low gravity. :O

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[–] foggy@lemmy.world 6 points 10 months ago (1 children)

Idk, humans couldnt survive gravity changing all the time. Probably have bones filled with material that changes density with gravity fluctuations.

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[–] Guy_Fieris_Hair@lemmy.world 3 points 10 months ago

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.

[–] CosmicSploogeDrizzle@lemmy.world 15 points 10 months ago (2 children)

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.

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[–] MrFunnyMoustache@lemmy.ml 14 points 10 months ago

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.

[–] amio@kbin.social 9 points 10 months ago (1 children)

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.

[–] flashgnash@lemm.ee 6 points 10 months ago (1 children)

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

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[–] lmaydev@lemmy.world 9 points 10 months ago* (last edited 10 months ago) (1 children)

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.

[–] flashgnash@lemm.ee 3 points 10 months ago (2 children)

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

[–] xmunk@sh.itjust.works 6 points 10 months ago

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.

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[–] CanadaPlus@lemmy.sdf.org 7 points 10 months ago* (last edited 10 months ago) (2 children)

Lumpy.

Of course, if this is a fantasy world you're under no obligation to go with a world held together by self-gravitation, and you can even ignore the weight of air. Believable water is going to want to follow gravity as usual, though, so you need to figure out some sort of crazy hydraulic system to move it around. It could be a backstory for some cool canyons and things depending on what you decide.

More interesting questions might be related to how the residents adapt. I imagine lower gravity areas would be favoured, with groups living in the high gravity areas being specialised. Maybe unpredictable gravity could serve as an energy source for whatever civilisations are in your setting - you balance a very large weight somehow (against a non-gravitational force or a weight somewhere else), and have it work machinery as it adjusts to a new equilibrium. If it changes rapidly enough it might even be useful at small scales, like on vehicles.

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[–] theKalash@feddit.ch 7 points 10 months ago (1 children)

Probably pretty dead since you couldn't have planets with stable orbits.

[–] Pons_Aelius@kbin.social 20 points 10 months ago (7 children)

Variable gravity means its not our universe, So anything is possible.

Maybe the world is on the back of a turtle etc.

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[–] Moobythegoldensock@lemm.ee 6 points 10 months ago* (last edited 10 months ago)

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.

[–] Mothra@mander.xyz 6 points 10 months ago (1 children)

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.
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[–] simple@lemm.ee 6 points 10 months ago (1 children)

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.

[–] flashgnash@lemm.ee 4 points 10 months ago (1 children)

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

[–] TotalFat@lemmy.world 3 points 10 months ago (1 children)

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.

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[–] intensely_human@lemm.ee 5 points 10 months ago (1 children)

You’d need the planet’s core to contain some kind of non-dense material that will not mix with the dense material … like molten rock but also molten something else that’s much lighter than rock. Basically you need “oil and water” droplets that don’t mix, and are of different densities. Then you need some mechanism for them to churn in a turbulent way. The turbulence makes their movements chaotic and unpredictable.

Only thing I can think of to account for the churning is electromagnetic forces being generated by naturally-occurring nuclear reactions.

So to summarize:

  • Mantle composed of two substances. One much heavier than the other, and they don’t mix
  • Electromagnetic forces occurring at random places and times causes these substances to churn in a turbulent way
  • Turbulent churning of these two materials affects the total amount of mass under characters’ feet at different times, causing unpredictable “gravity weather”
  • Those electromagnetic forces somehow result from nuclear reactions happening naturally underground (otherwise where do you get the electromagnetism from?)
[–] flashgnash@lemm.ee 3 points 10 months ago (2 children)

I think this is my favourite idea so far as to explaining the gravity changes, very cool explanation

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[–] joel@lemmy.dbzer0.com 5 points 10 months ago (3 children)

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?

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[–] rbos@lemmy.ca 4 points 10 months ago

You'd have some wild weather.

[–] davefischer@beehaw.org 3 points 10 months ago

Roadside Picnic has gravitational anomalies, but they're very small, don't move, and are caused by abandoned alien artifacts.

!worldbuilding@lemmy.world

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