Floating Cities

There is a recent upswing in interest in aquatic FloatingCities - ultra-large ships with a permanent population and economy.

Aquatic FloatingCities already exist. Sometimes rivers (in VietNam? for example) are the only transportation route for backwater (literally) communities. Huge Caravans of boats go up and down the river: trading and fishing, forming an aquatic FloatingCity?. (It's true, I saw it on the Food Network.) -- SeanOleary

A floating garden, or three: ;-)

BuckminsterFuller noted that large GeodesicSpheres - a half mile wide - will actually float in the air due to the temperature differential between air inside and outside. This makes sky-floating cities possible, if not necessarily desirable.

Pros:

Make human-habitable the two-thirds of the Earth's surface covered by water.
Convert the planet into a garden and let its habitations never touch the ground.
Provide mid-ocean docking, storage, and cargo transfer facilities.
Inspire awe in primitive earthlings. Also in sophisticated ones.

Cons:

Reduction of solar energy to surface
Read LarryNiven's Ringworld for some images of the bad when FloatingCities fail
What happens if you puncture the dome from below? We'll only have FloatingCities once we figure out how to get rid of guns.
- Is it really likely that a few small holes in a half-mile-wide dome would bring the whole thing crashing down? And the ceiling would be a few hundred feet high, so most guns would not be able to hit it with a lot of force. Guns are not much of a threat to FloatingCities, although other forms of sabotage could be.
- The risk is low. You'd have to make really large holes. One of the radar installations my dad worked with was, as are many radar emplacements, housed in a rubberized "BuckyDome?" and had, because of high wind and accompanying rain, acquired a depression in the top of the dome that accumulated water - and this interfered with the radar. The engineers mulled this over for days before one of the more practical among them showed up with a rifle. He shot a well-placed hole in the top, a drip pan was placed beneath it, and they had no further trouble. The material used in the dome is intentionally tear-resistant, and the hole never got any bigger. Since your FloatingCities would clearly use a similarly tear-resistant material, the occasional hole would be of no consequence.
Migratory cities floating over your neighborhood real soon.
Cities in collision, unless we fix the AirTrafficControl system. (Actually, floating cities would have fixed positions. If they did move, their speeds would be slow enough that accidental collisions would be unlikely.)
Hurricanes. How do you keep these things clear of large weather systems?
- You don't. VeryLargeBalloons? surfing hurricanes are the cheapest way to get a lot of people into orbit. You might need to beef up the tensile strength a little ...

A question - from this discussion, it seems that the city will be a sphere; how will the buildings be part of the lift structure?

OK, we know some of the pros and cons. What about practical application for a sky floating city?

A half mile city is rather small even if you have two vertical plains to work with.
A half mile diameter may be enough to make a dome float, but what about when it's loaded down with the city and its inhabitants?
How big would it have to be before a balance could be found for a full weighted city?
Someone would have develop a stabilization system to keep the city level.
Even if it were on a tether, the slightest breeze and there goes dinner right off the table again.
How big would a sphere have to be to float inside a half mile sphere?

To float, a sphere must be at least half a mile in diameter. Larger spheres would be even easier to make float. Multiple horizontal levels could provide lots of living space. The stabilization problems have been solved, and in any event, anything that big isn't going to wobble around a lot. As far as "practical" applications go, I can't think of any, unless someone needs a city or large facility in an area that is not readily habitable (ocean, desert, jungle, arctic/antarctic), or needs one in an area far away from existing cities.

On what is this half-mile diameter figure based? Temperature? Gravity? Air pressure? Would it need to be larger/smaller at higher/lower elevations, temperatures, etc? In Phoenix, the temperature outside reaches as high as 120 degrees Fahrenheit in the summer. Would the interior have to be hotter than that in order to float?

All this talk about floating things reminds me of Titan, a ScienceFiction novel. I forget what actually floated, but I think they were large whale-like things. FloatingCities would also be a good thing if we ever decided to settle Jupiter (ala the old Marvel Comic Guardians of the Galaxy).

Titan by JohnVarley? was part of the Titan, Wizard, Demon trilogy. Titan concerned Gaea, an intelligent rotating kind of wheel where people and critters lived on the interior of the "innertube". Dunno if this was what you were thinking of though. -- AndyPierce

The thing about colonizing gas giants always struck me as missing the point. In what sense are you actually living on the planet? What benefit do you get from it that you wouldn't get from a station in orbit, geosynch or otherwise? It's not as if you can go outside. I suppose having a horizon is nice aesthetically. I note that it would have to be constructed in space: even if you could somehow build it to withstand liftoff from a planet's surface, you probably couldn't get enough energy in one launch, and if you had a steel plant in microgravity you could avoid that expense altogether. Which is doubly nice, because massive structures are actually easier to build in space (less scaffolding...), but you'll need an awful lot of infrastructure before you can even think about tackling the hard problems, which implies that by the time domes are feasible, space stations will be a technology already well understood, whereas the domes would be something with new dangers and no new benefits. -- DanielKnapp

The benefits are two-fold. First, living in a gravity well, hence not messing up the human metabolism nor needing to accelerate the station. Second, access to atmospheric gases.

See also CriticalPath

Floating cities will never work, for the same reason large scale use of dirigibles is impractical. It has to do with a phenomenon called the weather. Unless you can somehow float above it, but the air gets pretty thin up there!

Proposition :-)

Just connect the floating cities to the Invulnerable SpaceElevator at different elevations, it would give another much more practical reason for its existence than going 25000 miles to visit a space station tied to an asteroid somehow captured and forced into a geosynchronous orbit by the mass of the elevator. Certainly "spaced out" earthlings will feel comfortable in these otherwise rather unnatural surroundings. My concern is that some of the residents might consider it more like a prison than a paradise. It would also provide a place of residence for the maintenance crews for the SpaceElevator.

People with the financial means to support such a scheme would insist that the cities be insured and stable, so if they were ever built, no concern for personal security and safety would be an issue. Certain other money-making enterprises would arise in the opportunity to ship the hundreds and thousands of semi-trucks full of supplies and utilities to the city. The stockholders of the CorporateGovernment which would be introduced by such arrangements would be assured of guaranteed returns, not subject to the ups and downs usually associated with risky investments.

They'd just be subject to much more literal ups and downs.

One step further than this and we have "CitiesInFlight?" as in the JamesBlish? novel.

...My vague memory is that Cities in Flight got less and less interesting as it went along, but still, it's an epic tale. And everyone should know about "spindizzies". :-)

: Spindizzies?

What they used to make the cities fly. Web search says that in fact these 4 books (collected in one) are also called "the spindizzy novels."