I have a setting that involves floating islands that coast slowly across a planet. There are multiple tiers separated by cloud layers, however the surface is inaccessible to my floating islanders.
In order to suspend my floating islands I have decided to use a few different magic/handwavium particles. These particles when compressed against each other create a lifting force that pulls objects up. My islands are floated when these particles compress on the planet's surface into a giant crystal-like structure with a very specific internal shape. Pushing the land within a certain radius of said crystal up into the sky.
Based on crystal factors such as crystalline structure, mass, size etc. different islands are floated at different altitudes and coast with different speeds. These altitudes are by and large fixed with allowance for some bobbing up and down. Nothing more than 100 meters at the most.
The inhabitants of my world mine these crystals for airship-like flight. When mined these crystals no longer hold their solid structure, rather they break down into a sludge-like liquid which is placed into a rigid cylindrical container with a few other magic/handwavium particles. When compressed inside said container, the particles excite and effectively lift the container up. Height is controlled by changing how much pressure the pistons inside the container generate.
The end result is essentially a rigid airship, only that it can lift/repel much heavier cargo and cabins off the ground and into the sky. Effectively steampunkesque airship design. If the sludgy liquid is allowed to decay into a gaseous state using another process, the lifting potential is much higher and more efficient. Pistons still control height.
That said, orbital height, or even getting past the highest of islands, is impossible. A solid crystal structure is needed to get very high, something that my people haven't figured out how to recreate, nor will they ever. Refueling also needs to take place as the sludgy liquid or gaseous mix eventually dissipates. Note that solid crystals that islands use to float do NOT have this problem.
The main issue I have, however, is that the people of my world can construct artificial islands using these particles and processes. Something like a floating city or an artificially created floating island would be possible if they arrayed multiple containers. I explicitly want all my people living on naturally floating islands. People flying about on airships or flying carriers are fine. But something like floating Manhattan isn't.
How do I stop people from creating artificial islands using the magic/handwavium particles that suspend my floating islands in the first place?
- The particles only lift things to a certain height; they don't impart lateral direction. Airships need things like propellers or engines to change direction. Islands using crystals coast around the world of their own accord and aren't subjected to this limitation.
- Refueling needs to occur for such particles. They don't last forever.
- There is powered flight already, the jet engine has existed for a while. These don't use the above particles. They're normal aircraft by all accounts.
- The first airships were very steampunk in design. Rigid airship frame with a boat like frame slung underneath it. Thus, any changes to things like atmosphere, winds, etc., must allow humans to still breathe and live.
- The largest ships are flying aircraft carriers of sorts that can launch fighter jets (think the sizes along the F14 or A5). They are used for expeditionary mining or warfare operations in conjunction with an airship fleet. There are jet cargo aircraft as well.
- Naturally floating islands will never hit each other.
Edit: The primary end goal in all of this is to stop my floating islanders from expanding past their home island with the physics and technology available to them. Expanding in this sense means living perpetually. Things like airship carriers are not part of the scope in this regard.