How would a hollow, layered lattice planet work?

Question

I had the idea to make an artificially constructed planet which is terrestrial, but has the diameter of Jupiter. Instead of being a solid sphere, it would be five spherical layers, with land on the outside and inside, connected with pillars and with holes to let sunlight through to deeper spheres.

My current design is to have each sphere resemble a complex polyhedron (I don't know which ones yet.), with the edges being spars of land that curve and the sides being the holes, and connected to the sphere above and below with pillars. Each spar and pillar would have crust, mantle and core layers, with the core made of unobtainium that was enchanted so that its structure would be stable no matter what (which means ignoring hydrostatic equilibrium). It would also alter gravity so that 'down' is in the direction of the nearest land, and project a magnetic field (though I'm not sure if that particular aspect needs to be handwaved like the others).

What I'm curious about is, assuming there's enough magic handwaving to make it possible for humans to live on most of the planet, what other factors would make life different there?

Answer 1

• If the all the spars and columns are close enough to each other, I would expect an increase in flying and sailing creatures. And, if there is a biome made of massive vines or anything like that that could connect one spar to another, there would be an increase in climbing and swinging animals.

• Depending on the amount of open space between struts, the might be species that like to dive in and out, maybe some might race in and out really quickly, diving deep and the sailing out the other side for fun, hunting, etc, and you also might find flocks of slower moving migratory flying animals. People might domesticate some for racing or transportation.

• Depending on the tech level of the inhabitants, and the distance between struts, I could imagine some making structures that connect struts.

• You could have major spars and columns, and then smaller ones, and then smaller ones, on and on, like this:

  

  That could allow for some greater connectivity. You could also have regions where some of the struts are missing or broken, if you wanted an ancient, partially falling apart feeling.

• Obviously, dark loving creatures would be deeper inside the planet, since that will be the darkest area.

• Day and night cycles could be odd, depending on how many struts there are obstructing light from the opposite side of the planet. For example, if you have only a few struts very far apart, then even when the sun is facing the other side of the planet, the far side (night side) might still be getting enough light that it never really gets dark.

• Instead of oceans, you might have some struts composed mostly of water, with only enough unobtainium to mantain their shape. Or, similarly, you could have struts made mostly cloud/gas with a bit of solid structure for shape. Maybe you could have gas mining colonies in those struts, depending on their size.

• You might have some "faces" of the lattices be made/filled of a sheet of translucent or transparent materials, such as cloud, gas or water, or maybe even plasma, lightning, lava or fire. That could give very exotic atmospheres to different areas:

  

• You could also have the 3D volume of some polyhedrons filled with water, gas, fire, lightning, etc., rather than just a 2D face

Answer 2

So, you have a diameter of Jupiter. You'll need to make sure that you don't have anywhere near the mass of Jupiter. So let's assume the layers are sparse enough to avoid a soul-crushing gravity on the outermost surface.

I assume you want atmosphere to breathe? You're going to need airlocks to keep the air from all drifting to the lowest level over time. Or pumps to pump it back out. Either way, there's a big mechanical component (doors or pumps) that someone is going to be responsible for maintaining. Whoever is responsible for maintaining those systems is going to have a lot of power. I'm reminded of Mad Max Thunderdome... the real power is held by the guy who keeps the electricity going, regardless of any military or elections or whatnot. https://www.youtube.com/watch?v=Hgq4w4dqKsU

You will have people who think in terms of three dimensions more than people on Earth typically do. Ask any kid who likes to climb trees just how rarely adults look up... they'll tell you it's very rare. It's something you have to consciously maintain as you get older... we get used to living in a plane. If we truly have cities constantly overhead and under foot, there will be a good deal more consideration of that dimension.

You're probably going to have some prime real estate on the surface with a view of the sun, even if you have a good mirror system or sun lamps down below. The view of the stars cannot be really replicated.

Military tactics of taking and holding the staircases/elevators would be interesting... there are various "conquering the starship" bits of fiction that are relevant here. I don't know enough military sci-fi to really comment, but I suggest you explore it. One thing I will point you toward is the book "Wool" by Hugh Howey. The first book stands by itself, even though it is the first of a trilogy, and it is the first book that is really relevant here. It's all about life in a vertical column "silo". https://en.wikipedia.org/wiki/Silo_(series)

Depending upon how long it takes to get from the inside to the outside -- it might be stairs all the way, with no automation, making it a generational trip to migrate from bottom to top -- you may have folks who disbelieve in the world outside or who are terrified of open space. Likewise, if the mesh of the world has enough metal, radio transmissions through it may not be possible, leading to populaces that are very cut off from the rest of the world except at specific landline terminals... which might be controlled/filtered. We're back to those staircases potentially being very easy control points to keep a populace in check.

That's all that comes to mind right now. I may add more if comments yield interesting inspirations.

Answer 3

Most of the differences between this world and Earth stem from unequal daylight hours across the world.

Areas will consistently receive less light throughout the year as sunlight headed toward them is blocked by other segments of the planet. You will see cold patches, altered seasons, and a host of other changes because of these.

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Here's a list of what I can think of:

Complex scenes in the sky at all times

Depending on how spread out your layers are, you may see the other parts of the planet, in detail, in broad daylight. This is the most obvious change, and it may affect developing cultures. (You could come up with a hundred possible local myths, such as spiders in the sky that spin webs of terrain, or how the sky "cracks" every day and is saved when a god (the moon) appears)

Daily eclipses

Segments will constantly separate the landscape from the sun, most likely in a predictable way, and native life will get used to it. As a result, timekeeping systems may develop from this (instead of 24 hours per day, 15 eclipses per day - etc).

"Poles" at the joints

Terrain where multiple segments connect will be in shadow for most of the day. Therefore, it may be similar to Earth's poles - colder due to less direct sunlight. This would be be extremely interesting, as it yields a plethora of effects:

• Exploration difficulty. Intelligent species seeking to move outward from the segments they inhabit will find that it gets increasingly colder the closer to the joints they move. Harsh temperatures, combined with mountainous terrain due to high gravity and "segment fusion", could even separate populations of people until they developed space faring technology.

• Strange winds. Warm(er) air from the centers of the segments will rise, moving toward the joints; cool(er) air from the segments/poles will move toward the centers of the segments. This may be an additional obstacle for travelers, and keep them at home. To add to this, gravity will pull the planet's atmosphere(s) inward, but centrifugal force will pull them outward, potentially causing more strange winds at the segments connecting spheres.

• Biodiversity. Intelligent species aren't the only ones affected by segment isolation! Most species will not be able to cross the segment divides, meaning evolution may look completely different all across the planet. Biodiversity is also fueled by surface volume - there's so much space to cover that you're bound to end up with variety.

Coldest at the "true" poles and on the inside

Sunlight will be least direct at the "poles" of the whole structure - the top and bottom - so they will be the coldest regions. Additionally, the inside, while receiving more direct light than the poles, may see much of it obstructed by the surrounding shells - also making it slightly cooler. The converse of this is true - the outer shells will be warmest, and the equator(s) will be warm as well.

Screwy satellites and unsafe orbits

If the majority of would-be impacts just pass through the lattice, and every segment is as thick as the Earth, some objects may orbit specific segments. You may see regions with their own local moons, whose orbits don't stray into other regions. Additionally, comets, asteroids, and other bodies may fling themselves in and out of the planet, or in a complex orbit inside the spheres. Imagine how culture could change as a result of so many objects to see! Consider also that some of these may be their own (spherical planets) within the main one.

A true core

This planet's center of gravity will likely be close to the center of all of the concentric spheres. Some bodies passing in and out of the planet may even lose momentum and settle in this region! Consider a planet or two, or at the very least a gas cloud, to put in this area.

Rich culture overall

This setup has produced regionally divided groups of people, huge biodiversity, potentially large temperature gradients with such a large sphere, and a ton of astronomical phenomena to influence mythology, timekeeping, and more.

Answer 4

Moving Parts

These are very "outside of the box" ideas, not what you mentioned in your description, but if you are interested in exploring variations on lattice worlds, they might give you some ideas you like:

Rotating/Flexing Columns and Spars

This idea was inspired by some mathematical artwork an old friend of mine, Paul Nylander, made. He was very interested in exploring polyhedral structures, and many of them flexed and rotated:

Here is a higher resolution version, so you can see all the details.

Rotating Layers

The different spherical layers could rotate, perhaps in synch with each other or not. You could remove the columns, or have them be loosely attached to each sphere, perhaps utilizing a non-solid, yet connecting joint, such as a repelling magnetic connection. Or, perhaps the columns could be on solid tracks.