World building question: technology (yes, another one)

[Jimmy Magnusson]

I didn't want to post in the other thread as it could have meant some derailment. I'm having trouble justifying my world to myself. The concept I've developed for my SF story is that the main planet (or a cloned Earth or something; basically, it doesn't have to be Earth but it's an analogue to it) has been completely covered by a megapolis. Not only that, but there's been another layer added to that, so that we now have a surface city and undercity. The problem is twofold:

a) It would take a shedload of people for that to happen. Any guesses on how many billion it would take is greatly appreciated. But it's the lesser problem.

b) I don't want a particularly advanced technology level. There are some inconsistencies here, as I have ships (jet-propelled flying ones which can hover in the air like a helicopter) and cybernetics (brain implants, mechanical body parts), but at the same time a pretty low-tec and gritty world. Overall not any more advanced than what we have today, give or take a decade or two. The question is, is this believable? How do I justify a planet-wide city when we're not even close to it today?

 

[Pyan]

How do I justify a planet-wide city when we're not even close to it today?

You don't have to justify it, Jimmy - it's not that unbelievable that it might not happen to Earth yet.

And off the top of my head I can think of at least two worlds in SF that have this world-as-city premise: Trantor in Asimov's Foundation series, with a population of 45 billion inhabitants, and Coruscant in the Star Wars universe, given as having 100 billion residents.

 

[dustinzgirl]

b) I don't want a particularly advanced technology level. There are some inconsistencies here, as I have ships (jet-propelled flying ones which can hover in the air like a helicopter) and cybernetics (brain implants, mechanical body parts), but at the same time a pretty low-tec and gritty world. Overall not any more advanced than what we have today, give or take a decade or two. The question is, is this believable? How do I justify a planet-wide city when we're not even close to it today?

This is done quite frequently in sff. Johnny Mnuemonic, Fifth Element, for starters.

To help you a bit, think about our world. Take NYC or London or Hong Kong, they are beautiful cities full of wonder and high tech and cha-ching, but you walk down a bit from the upper levels and you get rats and muggers and some foul stench. If the technology is accepted as being a part of the world in that era, then there will be people who can afford it and people who cant, unless you are going for the whole star trek no money thing which could be good for society, or bad for society.

 

[HareBrain]

Don't forget what all these people are going to eat. Maybe there's easy space travel from planets that have an abundance of food, but if your tech level is only slightly ahead of ours, maybe not. Our own planet is already facing the pressures of population with only a small fraction of its surface urbanised.

 

[iansales]

The most densely populated city on Earth is Dhaka (capital of Bangladesh), 43,752 people per sq km. New York is 10,452 ppl/sq km, London is 4,697. Which would give you approximate global populations for the same population densities of...

(Dhaka) - 22,300 trillion
(NYC) - 5,330 trillion
(London) - 2,400 trillion

(for a total Earth surface area of 510,072,000 sq km - land and sea)

 

[chrispenycate]

Um- minor question- when you say "entire surface" are you being literal, or is this really "the entire landmass"? If the latter, the problem is trivial; I just raise ocean levels until there's just enough space left to fit the maximum population that can be fed.
If the former, I don't think there's enough energy coming in from the sun to feed that number of people. Even if every scrap of rooftop were crops, even if we served up the dead as food, a low-tech society couldn't support that mass of insects, let alone mammals like us. Trantor (anything but low tech) needed thousands of spaceships a day carrying in food (and presumably carrying out sewage to prevent it collapsing into a brown hole)
Mind you, high tech can get pretty gritty, too; read some of Cherryh's stations. Get enough humans together, and we can make anything a slum. If you've got a good alternative source of energy, you can float your habitations out over the oceans, build more on the ocean beds, and have algae tanks with artificial lights and yeast cultures in the undercity and get tens of trillions of inhabitants. Your limit might be the total mass of phosphorus available on Earth.

Big problem I see; even with fifty trillion inhabitants, I don't see packing densities getting that high, unless the rich have huge estates. Look at the Earth from the air; even the crowded areas, like Great Britain or the Netherlands, dwellings don't cover a thousanth of the available surface area; when you look at South America, or even the States, the factor is enormously more in favour of land, cultivated or not. A city feels big when we're in it, but seen from space it's a point in a wilderness. If Calcutta were to be spread out over the available space around it, rather than an inhabitant per square metre (or whatever the ridiculous population density is) you'd have fifty metres between each one (and the energy required to transport food would rise over that required to grow it.)

 

[Daniel Hetberg]

Barring space faring technology or really advanced microbiology to supplement a planet-wide megapolis, especially if you want to stick to traditional food, I think it wouldn't work in reality - but don't let that stop you. If it's borderline believable, it should work in fiction.

Take Mieville's New Crobuzon, even though it's surrounded by huge amounts of wilderness, it's literally wilderness. The issue where the food comes from is never so much as raised if I remember correctly, and I never thought of it myself. The paradigm of urban life is not concerned with trivialities like "where does the food come from"? Of course it comes from the supermarket!

Actually, you can either skirt around the issue completely, or make it an issue briefly, but don't give an explanation. Readers will come up with their own grisly theories where the food comes from.

I just saw "The Matrix" again the other day, and there it was a bit blunt that basically the whole story rests on the shoulders of a perpetuum mobile... the machines breed humans because they generate energy. Ummm.... riiiight. Avoid that. ^^

 

[Cheehwawa]

How is the environment on your world? With a surface covered two-fold by cities built from modern technology, I would assume a very un attractive and unhealthy environment - could feed into your gritty environment that you want to capture.

As for the populations, I would personally give the under city roughly twice as much inhabitants as the Earth has today (making it roughly 14 billion) and the city on top could have three times as much as today's world (what with all of the sky scrapers and possibly floating cities) making it roughly 21 billion... for a grand total of 35 billion. Damn.

 

[Cheehwawa]

One more thing -- if you are having trouble with food, maybe you could have floating farms on the ocean surface? Grow lots of crops and stuff. You could also have animal farms out there, and the meat would most certainly have to be cloned and not grown "regularly" as it is today. Maybe naturally grown foods could be coveted by the rich.