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
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