Sunday, January 15, 2017

Trantor: the Big Town


As Earth awaits the official debut of America's nightmare comedy, this might be a good time to talk about other planets. So here we go! (Again!)

One minor but durable trope in science fiction is the planetwide city. (For which the geek (and Greek) term is ecumenopolis, 'world city'.) For now - until the Star Wars prequels mercifully fade from popular memory - most people will associate this trope with Coruscant. But accept no substitutes: really it means Trantor, capital world of the Galactic Empire in Asimov's Foundation Trilogy.

Just for the record, this discussion obviously lies waaay beyond the Plausible Midfuture. Also a disclaimer that I am not trying to specifically reconstruct Asimov's Trantor, but a more broadly Trantor-esque world.

I bring up this trope because one of my interests, which has gotten oblique mention here before, is urban rapid transit. And while TERTA - the Trantor Ecumenopolitan Rapid Transit Agency - never got any mention in the books, it reasonably ought to be ... impressive.

As useful background for a transit ride, a few words - well, quite a few - about the overall cityscape, starting with its population. The Good Doctor A slipped up badly on this score. His canonical figure for Trantor - 40 billion - is laughably low, only a few times current world population. We want a global city, not a world of ten-acre exurban ranchettes.

Donald Kingsbury does much better in his unofficial Foundation sequel, Psychohistorical Crisis. His version of Trantor, called Splendid Wisdom, is home to a nice, round trillion people. Spread over the whole surface of an earthlike planet, even this comes out to merely suburban average density. But if we leave the oceans wet and only urbanize the land surface, we get roughly the population density of San Francisco.

Now we're talking. San Francisco, outside the Financial District, lacks the glass and steel canyons look, but cityscapes can vary considerably for a given density. Central Paris apparently has about the same population density as Manhattan, but a very different urban look. Likewise a modest urban density could still have an impressive skyline.

The image of Trantor (nominally Coruscant) above - click to embiggen - hints at one way of finessing this. Most of the city seems to be low-rise, or at least of roughly uniform height, but with monumental structures rising above the rest for added zip.

Another consideration is that an ecumenopolis surely cannot be like an ordinary habitable planet, where humans merely skim the cream off a self-sustaining natural ecosystem. It will need something more like a spacecraft life support system, on a suitably giga scale.

The details are far above my biology pay grade, but may well imply vast sublevels of, essentially, plumbing. The subways could thus run through what amount to basements rather than true tunnels. And the oceans may effectively be sewage treatment / oxygen regeneration ponds - nothing you would want to swim in, which at least would keep shorefront promenades from being impossibly crowded.

Parts of the life support system might rise to or above surface level, and some of the megastructures could well be the equivalent of rooftop air conditioning equipment.

Also, the population density need not be uniform all over town. If you really don't like urban living, Trantor is not the planet for you. But many neighborhoods (totalling millions of km2 and a couple of hundred billion people) might well be at suburban density, balanced by high-rise urban districts, thus accommodating people who want a yard as well as those who prefer living near good shopping and restaurants.

Kingsbury mentions one such commercial district on Splendid Wisdom that is suitably Trantorian in scale. I forget its name, but since Splendid Wisdom is a rebuilt Trantor of the Second Empire, I will call it Seldon Street. Though technically a pedestrian mall, functionally it is a suitably giga-scaled version of Market Street or Wilshire Boulevard, extending for some 3000 km.

That being a long, long stroll, expect some serious transit lines to run along the Seldon Street corridor.

But before we ride, a few more thoughts on the cityscape. First, a couple of annoying practicalities. Realism[TM] is not really a key issue in this exercise, but we should give it a superficial nod.

On a world without farmland, how do you feed a trillion people? Asimov's Trantor imports its food from 20 agricultural worlds, but they could only supply this Trantor with delicacies. For basic food supply you need a planetwide array of oscillating hands: something something hydroponics, something something algae.

And, of course, all this stuff should really be on the surface, with the city life below, but we want a planet that looks urban. We will delicately assume that technology originally developed for spacehabs and such will solve food supply along with the rest of the life support challenge.

Energy supply turns out to need less handwaving than food supply. An earthlike planet absorbs on order of 10^17 watts of insolation (instellation?) from its parent star. Current average US energy usage is about 10 kw/capita, scaling to 10^16 watts for a trillion people. So cover the rooftops with solar panels and you more or less get there. Waste heat disposal is not a problem, because you are merely using energy the planet would absorb anyway.

And energy consumption on Trantor can be relatively modest. It is not an industrial world; as the Imperial capital, its chief manufactured product is government. Large cities also tend to be energy efficient - not least because people ride the subway instead of driving.

From these material concerns we can turn to social considerations. An ecumenopolis must have substantial overall social stability to function at all, but Trantor presumably has its good neighborhoods and not so good, perhaps including slums the cops only enter in army-corps strength.

Or - another familiar urban SF trope - class stratification might be literal, with the down and out living among the plumbing sublevels, while the upper classes live on upper floors, the richest in penthouses. This lends itself to a transit subtrope that goes back to 1890: dismal subways for the poor, elegant els for the rich.

Note that the district shown in the image above must be served only by subways; there are no hints of elevated lines.

Given a world of a trillion people none of this needs be an either/or: Within vary broad limits, Trantor's cityscape and social life can be as varied - including the charmingly urbane and the dystopian - as you want them to be.

On yet another note, Isaac Asimov was famously agoraphobic, and his Trantorians rarely went up to the open surface. Depending on how the life support system operates, 'rarely' might be never, at least without a quasi space suit.

But this too is not a given. An ecumenopolis, or neighborhoods thereof, may have rooftop gardens and dining patios under the solar awnings, and even (shock!) open air streets instead of roofed over corridors. When I speak of the Seldon Street corridor I say nothing about its architecture, only that it is an elongated urban district.

Trantor might even have parks, though the only open space on Asimov's version was the Imperial palace grounds. But we have not come all this way to an ecumenopolis to visit a park. You can find those on any garden colony world. So in our next exciting episode we will head for Seldon Street.

And since it is already mostly written, you won't need to wait until the Galactic Era to read it.

Yes, knowing this blog's commenter community - if you have not all given up and deserted me - the discussion will work itself around to space battles.

The cityscape image comes from a blog review of Second Foundation. Alas, I know nothing of the artist who created it.


Elladan said...

Welcome back! Sadly, I found your blog after you stopped writing much. :-(

It seems to me that the whole question of a world-city really hinges on how large you can scale your life support before it becomes dangerous.

When you look at other SF tropes -- in particular, space colonies -- the conventional thinking always seems to turn into a question of whether hairless apes can be trusted to perform maintenance (we cannot, the general thinking goes: look at the election!) and whether this naturally leads to a hydraulic empire.

In contrast, planets look like they're potentially safe places to live. After all, you can stop doing maintenance on them for centuries, maybe fight a few wars, lose access to technology and revert to barbarism... and a nice planet will still be there for you, helpfully replenishing your oxygen, cleaning your water, and even providing you with free food ready for picking.

The reality of course is nothing like that. Outside of the Earth, any planet we're likely to live on is going to be an industrial base with more complexity than Antarctica, or if you're lucky the result of millennia of terraforming. Your terraformed world might be stable for a while, but when the machinery breaks down it will slowly revert to a barren, airless waste.

In contrast, the idea of a space colony (or a Mars base) is that it's relatively small. There may be billions or trillions of people living in the system, but they're spread out over thousands or millions of these little polities, where each one carefully manages their life support system and people know exactly what goes in and out.

Trantor doesn't work like that. Functionally, it's a heavily terraformed world, like a giant space colony. And it isn't even self-sufficient at the food level: it's the product of empire, and totally dependent on massive supply chains. At least a Mars base mostly just runs on sunlight and local resources, and a space colony can in principle sit on an asteroid or some other source of water and metals.

When the government of Trantor breaks down, everyone dies. The food stops landing, the air goes bad fairly rapidly, and the ecosystem collapses. A rusting wasteland with toxic oceans is all that's left.

Maybe that idea of millions of glittering lights in the sky, each one a spinning colony, is a better way to gather people around the core of your empire? The whole idea, after all, is to bunch people together so they can do a better job at being bureaucrats: a few light minutes isn't bad, compared to years, right?

p.s. I blogger seems broken, and gives a 400 error when commenting after preview.

D said...

I've always wondered how Asimov came up with that figure. Did he drop a zero or something?
If you have a chance, check out Arcology: The City in the Image of Man by Paolo Soleri. It's from 1973, but it has some of the most amazing images and ideas for future mega-cities I've ever seen. Just a beautiful book.

Theoden said...

New post! I saw maybe two of these before this last Great Silence. I look forward to anything more you may produce.

It seems to me that there may be some inflection point (by which I mean a point where the system becomes maximally effective) between an automated taxi system and a bus/metro/etc transit system. One might consider a mix between an elevator and an escalator. The escalator (bus/metro/etc) runs regularly along fixed routes but not extremely quickly. The elevator (auto-taxis), meanwhile, supplement it with faster connections to fill in the spaces between the escalators.
Or perhaps the bus/metro is the faster option, and the auto-taxis fill in the role of the smaller-scale buses, transferring people between their destinations and the nearest transit hub.

It certainly feels to me like most of the slowness of a transit network is just getting onto the network. If you assume there are no non-automated cars, then the transit system needs to get people onto the system as fast as possible, and can probably do so easier.

It would also probably be true that if there were no manual cars on the internal road network (people can drive their expensive beautiful private nuclear space-yachts in the skies, but no showboating on the ground road!), road networks become much different beasts.

Cererean said...

Does the 10 kW/person figure include the sunlight used by agriculture? Answer - no way, the sunlight used by plants is at least 100 kW, based on 400 m^2 per person. Though as you point out, oscillating hands make light work. I wouldn't be surprised if we could get that down to 10 kW/person to provide food, whether by very efficient agriculture or direct synthesis of food.

A city planet by a star would have to use sunlight to avoid the heat rejection problems, but one built out in interstellar space could run on fusion power. Either way, the limit to population density is whatever area is needed to radiate the power used by one individual. Terra radiates, what, ~325 W per square metre? If we assume a power usage of 20 kW per person, that requires ~60 m^2/person. Which is approximately the population density of Barcelona, though that assumes that the entire planet is covered. At that density, it needn't be sprawl as far as the eye can see - hyperdense (~100 k/km cities surrounded by incredibly efficient farms would be a possible model. At a lower density, say 4 k/km, medium sized towns surrounded by farmland, connected together with rail, and with large areas given over as national parks, would be a possibility. If a planet the size of Mars was settled in such a way (ignoring the oceans that would reform from the heat), it's population would be 588 billion. Terra is larger, but has oceans in the way that would lead to a similar population.

Elladan said...

On the subject of transportation, it occurs to me that outside of the oceans, this sort of world lacks any area where an air disaster wouldn't cause a ground disaster.

Sure, airplanes seldom crash... but when they do, they also seldom land on people. In the world city, they always land on someone. Typically, they crash through a few high-rise apartment complexes before coming to rest in a flaming ruin on the teeming masses below.

There aren't even many flat spaces where an airplane in distress might manage to make an emergency landing: it's all rooftops and towers, to a first approximation.

This is also true, by the way, for space debris: outside of carefully controlled ocean demolition by the orbital garbage crews, anything entering the atmosphere is liable as not to land on someone's head, or at least on their penthouse suite.

The solution, I think, is that there'll be none of the tumultuous air-car traffic we expect in our far-future metropolis. Instead, the local bureaucracy will enforce the sort of tightly controlled, oppressive safety and pollution regulations you'd expect in a large space colony.

Instead, people zoom around in monorails, elevated tube-ways, subways, and all manner of regulated, licensed, and bonded robotic ground cars. Rich people might afford the insurance premiums to go from rooftop to rooftop in a small helicopter, but it will certainly be run by an autopilot that strictly obeys traffic control.

Rick said...

Wow. Given my prolonged absence, I thought comments might trickle in over weeks, as people checked by and found a new post. Five comments in four hours? Not what I expected!

The whole idea of an ecumenopolis is indeed ... problematic. A 'distributed' Imperial administration would surely be more robust, and a trillion people on one planet pushes some theoretical limits, not to mention practical ones.

On the other hand, I wanted to play with a setting for an Awesome urban transit system, and Trantor is the place, if anywhere is. (Well, short of an urbanized Ringworld or, God help us, Dyson sphere. Not. Going. There.)

On the third hand, these comments already hint a framework for thinking about the limits of the plausible. 100 billion, maybe?

Transit specific discussion I'll defer to the next post, 'Rapid Transit on Trantor'. But the short answer to the points made is, basically, Yes.

On a more immediately practical note, I also got a 400 error. Hopefully a transient Blogger glitch. All I can suggest for now is to save a copy, so if Blogger keeps blowing up you at least don't lose your work.

Isn't tech wonderiffic?

Nyrath said...

I disremember if it was Asimov, the Killer B's, or Kingsbury, but at least one of them had Trantor powered by the temperature differential between the sub-sub-sub level and the surface.

Nyrath said...

I halfheartedly tried to make a rough calculation of the size of Trantor's bureaucracy using Robert Freitas' figures but I didn't get very far.

Nyrath said...

First book FOUNDATION states the galactic empire has 24 million inhabited planets, and almost 1 quintillion people. If I am doing my arithmetic correctly, this means the average population per planet is 40 billion people. Which happens to be the figure specified as the population of Trantor.

Rick said...

It was Asimov who mentioned the using the temperature differential for power. I almost mentioned it, but let it slide, figuring a commenter might mention it. I was not disappointed.

The Freitas link - actually to the interstellar empires page at Atomic Rockets - neatly covers my blunder in failing to provide that link.

From the link, under certain assumptions, 'only one-fifth of the Emperor's plans for the commoners ever reach fruition'. I suspect that any US president from Washington on would have been delighted to hit that percentage. How the next president will deal with that reality may be ... interesting. (We may hope not in the sense of 'interesting times'.)

Both Kingsbury and Asimov (in the later, robot-centric books) touched on how remote the Empire would be from the daily lives of subjects, and even from the regional politics of the provinces.

Elladan said...


"There were nearly twenty-five million inhabited planets in the Galaxy then, and not one but owed allegiance to the Empire whose seat was on Trantor."

"Consider that Trantor has a population of over forty billions [...] the Empire contains nearly a quintillion human beings."

10¹⁸ / 2.5 * 10⁷ -> 18-7 -> Yup!

I first tried to calculate using a quadrillion, and it made a lot more sense...

Brett said...

I'm still here! It's the wonder of RSS feeds - even if you don't post for a long time, as soon as you post again Feedly picks it up and here we go.

The food situation is going to require some hand-waving, although maybe not too much. Trantor could have some truly massive hydroponic skyscraper farming, with the buildings doubling as solar power stations. The Trantorian diet, in turn, would skew towards the types of agricultural products that could be most readily grown in such facilities. They might eat a lot of lettuce, tomatoes, potatoes, and herbs, with stuff that doesn't grow so well either being a delicacy or simulated.

What I really think might be common, though, is Extreme Food Processing. They'd use whatever means necessary - chemical industry, etc - to produce basic stock ingredients and flavoring ingredients. Think "a lipid/fat", "a protein", "a carbohydrate", etc. Then feed them into futuristic food processors and out comes stuff that looks and tastes like regular foods. Such processors might be at home, or they might be done at factories then shipped out to be purchased. Perhaps the poorest Trantorians live off of the Trantorian equivalent of frozen pizza, fake-meat stew, and ready-to-make rolls, supplementing it with basic salads.

The whole idea of an ecumenopolis is indeed ... problematic. A 'distributed' Imperial administration would surely be more robust, and a trillion people on one planet pushes some theoretical limits, not to mention practical ones.

I could even imagine the Emperor deliberately limiting access to the Throne World while making it extremely pleasant to live on (and secure from outside invasion and interior coup de'tat). Getting a post that allows you actually live on the Capitol World might be a sign of great political favor from the Imperial Court.

Matter Beam said...

Welcome back, Rick!

A few thoughts:
-One thing that is more sensitive to light lag than governing is trade. Exchanging currencies and securities a few light second closer to the servers can mean the difference between closing a deal and losing out. This might actually be the real reason why city-world develop: everyone wants to set up shop as close as possible to the trade centers.

-If we assume an Earth-like world, covered 70% by water and with an average depth of 3688m, we'll have an astounding volume of 1.34 billion km3 to grow food in. It vastly outstrips farmable land. Even growing in the first 2 meters depth gives us 726000 km3 of ocean. Growing algae and fish in the sea seems to be the most reasonable prospect. If you want mammalian fat, you can get some whales going.

-Power. Solar power requires that you block sunlight over the majority of the world. Nuclear power is iffy when people are inclined to build servers right up next to the reactor walls. Geothermal power requires an incredibly large initial investment. What we can do is use the temperature gradient between the oceans' surface and the ocean depths, which can be exploited at the cheapest by anchoring thermoelectric generators or more expensively with salt pumps and magnetohydrodynamic generators. It varies between 6 and 26K.
OTEC: potential for 4000x the current world power consumption.

J. Lewis said...

The authors of the Stanford Torus study believed they could feed 10,000 people on a meat-rich North American diet using only ~60 m^2/person--about 1/10 the area needed by present-day outdoor farms. Let's assume this number is overly-optimistic, and that we actually need 120 m^2/person. This means that each km^2 of farm area can support 8,333 people.

If Trantor approximates San Francisco's population density of 7,000 people/km^2, the farm area needed to feed those 7,000 people comes to 0.84 km^2. This is pretty reasonable: we can accommodate it by adding a "farm floor" to the top of every building. Or we can mix-and-match: some buildings get several farm floors while others get none.

Remember: this assumes present-day crops (albeit hydroponically-grown) and a meat-rich diet! Futuristic techniques like algaeculture and zymoculture would be even more productive, and take up even less space.

The main reason indoor farming is (potentially) so much more productive is that, with total control over the indoor climate, we can grow crops continuously. Instead of getting one growing season per year, we can have three or four. Keeping the growing areas sealed off from outside pests, diseases and parasites also helps.

Anyway, I just thought I'd add some BotE numbers to the discussion.

Gregory Johnson said...

Glad to see you're still here!
I must admit, I've seen some impressive engineering solutions to putting lots of people on a planet. When you start talking multi-kilometer high Arcologies, the densities become breathtaking, even if the average density is more reasonable. But how do these people move? How do you get elevators to work efficiently at those scales? Can you have private vehicles or do you HAVE to mandate public transport? Heck, do you require everyone to work from home offices just to prevent a system-wide catastrophe? You've set up a good set of questions... I'm interested to see how you answer them.

Hollister David said...

Good to see you back. Hope you keep it up.

Surface area is a big constraint. In a number of ways.

If you have a large population of energy using citizens, you need surface area to dump waste heat. Else we would cook ourselves.

You need area to grow crops. Doesn't necessarily have to be sunlit area. If you have a power source, LED lights might do it. Or perhaps there are other food sources than plants using chlorophyll.

Which leads me to a rant on planetary chauvinism.

With planets and large moons, real estate is measured in area. This is because only the thin outer shell of a large body is accessible to us. Dig too deep and heat and pressure bar us from going further.

In contrast a small body's entire volume is reachable. This is true of Phobos, Deimos and most of the bodies in the Main Belt. It might even be possible to dig a mohole clear through the center of Vesta and Ceres.

Hollister David said...

A continuation of my earlier post part II

Inner Visions of Ceres

One of my favorite daydreams is Ceres 3,000 years from now. In this fantasy there are twelve major entrances on Ceres' surface. These correspond to the vertices of an Icosahedron. Transportation corridors beneath Ceres surface link these entrances. Corridors to next door neighbor hubs form the edges of an icosahedron. Corridors to hubs two doors down form the edges a stellated dodecahedron. And then there'd be corridors from a hub going through the center of Ceres to the entrance hub at the antipode.

Off these major arterials would branch smaller arterials. These would in turn branch into smaller corridors forming a fractal structure that permeates every cubic meter of Ceres' volume. In this fashion the Ceres' mass has a truly enormous surface area.

Using Ceres' gravity, it would be possible to travel from one hub entrance to any other hub entrance with almost zero energy. I talk about this at

Hollister David said...

Earlier post continuation Part III

Outer Visions of Ceres

And the potential for building Ceres inward is just half of it. With Ceres shallow gravity well, it is possible to build tall towers. With Ceres' high angular velocity and shallow gravity well, Clarke style space elevators could be easily erected from Ceres' equator. These space elevators could be built with existing materials like Zylon. Ceres synchronous orbit lies about 700 kilometers above Ceres' equator. Extending an elevator to an altitude of 2000 km provides enough centrifugal force to keep the elevator aloft.

So what's the point of a Ceres space elevator? With Ceres' low gravity, it's easy to get off Ceres' surface. Well, not always. It depends on what sort of space craft you're using. High ISP ion propelled craft would be great for moving about the Main Belt and outer solar system. But with their tiny thrust, they don't have the thrust to weight ratio needed for a soft Ceres landing. A ion craft could dock with an elevator, though. Also traveling to the top of a 2000 km Ceres space elevator would lend a ship half a kilometer per second velocity. This would be helpful for injection to transfer orbits to other parts of the solar system.

Given materials like long carbon nanotubes, much higher Ceres space elevators could be built. If reaching to altitudes of 10,000 km, an elevator could provide most of the injection velocity to many destinations in the solar system.

At first there would be a few elevators. Then more spokes in a wheel. Eventually Ceres wold become a disk with a cross section something like this:
A disk 20,000 km in diameter could give Ceres a huge radiator surface to dump waste heat. Ceres could accommodate many energy using citizens.

Hollister David said...

Post Continuation Part 4

And not just Ceres

Ceres has many neighbors. If each Main Belt asteroid used mirrors to harvest sunlight, you'd have the beginnings of a Dyson swarm.

I haven't done the math but I suspect the Main Belt could support a population of trillions. This would make Trantor look like Dogpatch.

Eth said...

Great to see you back!

If solar power is insufficient, for example because it is wished to not cover the surface with solar panels and block the sky, Trantor can also use powersats, from the geostationary version to a Dyson sphereling.
It will have to radiate all this extra heat back, though. For example with giant red glowing radiators at the poles. IIRC, in Prelude to Foundation, the waste heat system is at the South pole, and it is evoked that if it stopped, Trantor would be screwed.
Another solution is to have a web of equatorial space elevators, connected to a radiator ring. The view, both from space and from the ground, would be quite spectacular.

Such a planet requires lots of moving parts to keep working, similarly to a space colony on a vaster scale. This is a problem for the long-term well-being of its denizens, but a slowly failing city-world is chock-full of story potential.

Cererean said...

Talking again about temperature, not all the energy that arrives at Terra is absorbed - some is reflected by high altitude clouds, and thus doesn't heat up the surface. According to NASA ( the average amount of energy absorbed by the surface, averaged over the entire planet, is 240 W.

So that gives you a figure for how much energy you can use per square metre, if you don't use giant heat pumps (and how much energy is that going to take, and how much is going to be reabsorbed by the atmosphere and thus reduce the efficiency?). You might be able to get it higher than that, since the equatorial regions absorb a lot more than the polar regions, but it's a good lower bound based on what we know, and I don't think the upper bound would be more than twice that.

Which then brings on the question of how much power people would need. At the absolute minimum, 100 W, which is the power used by the average person at rest to simply survive. At our lower bound of 240 W/m^2, each person will need ~0.42 m^2. People's own body heat rules out a planet entirely covered by mile high skyscrapers, unless everyone gets a very large apartment with tall ceilings. Adding in the power required for food and day to day life... even if you could get it down to 1 kW with direct food synthesis and very efficient transit (no need for heating, at least), that's still 4.2 m^2 per person, which means the city planet would be mainly mid-rise construction.

Of course, if you have some Second Law violating heat pumps or other means of disposing of the heat, then you can go arbitrarily high. You can also get stealth in space, so your troop transports can sneak up on the planet without being intercepted by your enemies fighters...

Elladan said...

So, back to Trantor for a bit... I was wondering about the logistics of shipping in food from space. I mean, really, this seems like a lot of work. But how much work?

I decided to start by assuming that to take some food in Low Earth Orbit and move it onto someone's plate, the first step is to slow it down from 8 km/s. I'll assume that everyone eats about 1 kg of food per day: maybe the yeast vats make up the rest.

I'll also assume that the space ships the food comes in don't mass anything. So... how much kinetic energy are we going to be dumping into the atmosphere?

I got 1.28*10¹⁸ J, or 14.8 TW.

Current world energy consumption is about 12 TW, so yay! Um... we win?

How about with a trillion people? Well, 0.37 PW. Still peanuts compared to the sun, at 130 PW.

We just need 400 thousand SpaceX ITS rockets (or 10 million for a trillion people) per day and we're set!

Rick said...

Regarding habitation on - or inside! - Ceres, the huge unanswered question is the same as for every other Solar System body with a solid surface. (Except for Venus, which has its own challenges!) We know that microgravity is bad for human health, while 1 g is fine. What we don't know is the intermediate cases, and how much gravity is needed to avoid health issues.

You *could* build spin habs on/in an object, like big carousels, but at that point it may be easier to just mine stuff and build 'traditional' space habs.

But tunnels in Ceres, or anywhere, raise an indirect transit related issue. Tunneling is horribly expensive - which has killed many a subway project - and over time the cost has tended to go up rather than down. Tunneling under Ceres is not like tunneling under NYC, but a tech revolution may be needed for Awesome tunnel projects to be viable.

Not necessarily an issue for Trantor, since as noted the subways may run mainly through basement levels rather than actual tunnels.

Rick said...

The discussion of energy and food production seems to converge on Trantor being near the limits of the possible, but not grossly beyond them.

The idea of the Throne World as a sort of Forbidden City (Forbidden Planet?!!) probably is, like a super constellation of habs, more sensible than an ecumenopolis of a trillion people.

But (setting aside the meta issue that the objective here is to play with trains!), Trantor is a product of history, not preplanning. It is a giga London or Paris, not a giga Brazilia or even Washington DC. A initially run of the mill planet becomes Galactic capital, and by the time the implications become clear, merely sensible options are no longer politically available.

Continued ...

Rick said...

a slowly failing city-world is chock-full of story potential

Darker and Edgier strikes again! In other words, yes.

Note that since Trantor is ecologically more like a space hab than a normal habitable world, Ken Burnside's 3Gen issue has to be solvable - or at least put off for a good long time - for it to fully develop at all. Trantor is not built in a day, or even a few generations!

That said, for sure it can gradually fail. If not averted, at some critical point panic will take hold and you get a trillion people rushing for the exits. Few will make it.

(Curiously enough, the fall of Trantor in the Foundation books seems due to outside attack - albeit part of the overall fall of the Empire - not internal breakdown on Trantor itself.)

All that said, parts of Trantor can surely be 'slowly failing' at any given time, and even local breakdown can be on a pretty grand and story-worthy scale. Especially since City Hall knows that things could get out of hand and lead to catastrophe.

Elladan said...

Regarding the gravity issue, it seems like in the sort of far future where megaprojects like space elevators and transit tunnels on Ceres are plausible, you can just as well imagine that humans have the medicine or genetic engineering to be tolerant of low gravity. Certainly many of the problems astronauts experience today are the sorts of things we'd like to fix anyway: osteoporosis? Maintaining your physique without heavy exercise?

This leads to the question of why bother with gravity at all?

One thing I've wondered about is whether a very low but noticeable amount of gravity might be preferable even in the near future. Imagine a Mars clipper designed for a 3 month journey, which rotates for modest 0.01 g. What's the advantage over free fall, assuming it's not enough to counteract muscle loss and so on?

How about plumbing and convection? It seems to me like people would much prefer the possibility of a bath (or a toilet) that doesn't completely fly all over the place, over the fixtures on the ISS. But more to the point: we need to run fans constantly on the ISS so people don't pass out in their own little CO₂ bubbles. Even a very small amount of gravity may counteract that, leading to a nice pleasant living space.

There are also potentially benefits for the ship's mechanicals, since pumping liquids around in free fall isn't necessarily easy (you need to provide some sort of small acceleration just to get the liquid to settle down).

So rather than living on the ISS in deep space, or on a large and rapidly spinning shit habitat in full Earth gravity, how about a modest Ceres-like gravity as the standard for vessels?

Rick said...

rapidly spinning shit habitat

Is that a typo? Micrograv toilets are indeed a pain in the (ahem!) ass, but I'm puzzling over the specific point here!

On the overall point, even modest gravity would indeed be highly convenient, especially including the toilet thing.

I'm always vaguely uncomfortable with human genetic engineering, but that is arguably mere prejudice. Anyway, if we go to the stars and All That, human subspeciation and even full speciation is likely inevitable, planned or not, and certainly whether I like it or not.

Brett said...


Good points on Trantor being a product of history, not planning. That said, I figure that sooner or later they'd have to apply a massive amount of planning and construction to it as a planet overall if they want it to be a livable ecumenopolis. It would probably happen around the time that some of the mega-cities converge to cover an entire continental coastline, or something like that (or maybe when the cities have gotten so big that they're changing the planet's global weather patterns just by their daily operation).

Thinking about it some more, a city-planet Capital World might make more sense for an authoritarian Galactic Empire than for a different government model. After-all, the Emperor is going to want to keep his enemies and allies close, and control of the reigns of government close as well. Delegating too much power to outlying worlds might lead them to become focal points for the rise of usurpers, in the way that Roman Emperors before the 4th century AD had to worry that delegating too much material power to a general might lead said general to turn around and lay claim to the throne.

It's not so much of a problem for a Galactic Republic, and I suspect that the citizens of a Galactic Republic would have much more power to prevent a world-city from forming in the first place.

Elladan said...

Is that a typo?

Lol! Yes. Though oddly appropriate.

Theoden said...

It's an interesting thought-experiment to amalgamate two ideas that have been bouncing around in here into one: "Trantor Prime" is a forbidden-planet sort of idea, home to [insert grandiose description here]. Quite possibly you have an excessively planned city (or multi-city?), spreading people around but still keeping them somewhat concentrated. Much of the planet is devoted to agriculture - keeping the planet fed with the absolute choicest food. And so on.

"Trantor Plethora", meanwhile, is a relative maze of habitats, depots, "palaces", and assorted other dwelling places, formed out of the asteroid belt of the Trantor system. Most of these outposts are trade-groups establishing rights to close-communication with the entire Trantor system.

In this sort of situation, all space within Trantor Plethora can be well-guarded without limiting the trade activity much. Further, Trantor Prime could have a very tightly-maintained population base, while those who are not quite that important can still be close to the heart of the empire.

This would allow more leisurely use of the planetary space, and I could easily believe that such an asteroid-belt-spanning station-cluster might form over time as Trantor Prime gets built and solidified as the core of the galaxy. One could further create a system with Trantor/Sun L3 and L4 as secondary important places, to serve as an interface between Trantor-Prime and Trantor-Plethora, and perhaps lighten the load further from Trantor-Prime - though this would seem mostly unnecessary in this case.

There are definitely some good options for narratives in all this.

... The one thing I don't like is giving the gravitational advantage to anyone who might wish harm to Trantor. Asteroids are pretty great doomsday weapons. Removing this option poses a host of other problems, though.

Elladan said...

I'm always vaguely uncomfortable with human genetic engineering, but that is arguably mere prejudice.

You're not the only one... but at some point, I'm not sure there's a huge amount of difference between medicine and engineering.

Imagine a retrovirus (gene therapy) which cures a certain cause of pancreatitis (or blindness, or immunodeficiency...) It doesn't modify the germ line, but... is it genetic engineering or not?

The point is, we're at the point where this is turning into a today, right now question, not even a near future question. By the time we're into near or mid futures where we have a space faring civilization, it's no longer really credible that it won't be a part of the landscape.

Elladan said...

@ Theoden: ... The one thing I don't like is giving the gravitational advantage to anyone who might wish harm to Trantor. Asteroids are pretty great doomsday weapons.

There are so many doomsday weapons... and so few ways in reality for a galaxy-spanning empire to exist (i.e. none).

I think you just have to assume that any pesky would-be doomsday attack will be foiled by some combination of the all-powerful imperial navy, handwavium, and peoples' natural goodness (blow up Trantor?! But so many people live there!).

On a different note, one of the really nice things about having an atmosphere -- even a pitiful atmosphere like that of Mars -- is that it protects you from all manner of rocks, space junk, ionizing radiation, and the like. For free. Whipple shields and all manner of radar and lasers and such are nice, but at some point the only real way you can protect your space house from a rock the size of a car moving at 40 km/s is to be able to dodge.

To put this another way, I don't think the "gravitational advantage" is really a thing. Whatever doomsday weapon you have for a planet, something much, much, much simpler works on a space colony.

Nyrath said...

@ Hollister David said:
In contrast a small body's entire volume is reachable.

Which is ironic since Isaac Asimov himself rubbed our nose in this fact in his short story "Strikebreaker".

Blei's polite fixed smile expanded a hair. He said, "We are not a small world, Dr. Lamorak; you judge us by two-dimensional standards. The sur­face area of Elsevere is only three quarters that of the State of New York, but that's irrelevant. Remember, we can occupy, if we wish, the entire interior of Elsevere. A sphere of 50 miles radius has a volume of well over half a million cubic miles. If all of Elsevere were occupied by levels 50 feet apart, the total surface area within the planetoid would be 56,000,000 square miles, and that is equal to the total land area of Earth. And none of these square miles, Doctor, would be unproductive."

Stevo Darkly said...

1) Yahoo! You're back!

2) If you are unable to identity the image used to illustrate this post, it is of the very Trantor-like Coruscant, from the Star War series. (I couldn't tell you the specific artist(s) responsible, at least not without a little digging.)

This is all I have to say at this point in time.

fro1797 said...

Wow. That was a long break...oh, well. where to start? Trantor Rapid Transit Authority: Major hubs are connected together, each with a cluster of minor hubs that in turn feed reginal hubs, that feed local hubs, that feed sub-hubs, where you can get an auto taxi. Don't go swimming, there's not much but fish, alge, and thermocouples in the oceans. Skyscrapers are either radiator towers or communications centers. Alge, yeast, and fish form the basic rations for everyone, the starships only bring in luxury foods. I think that much of Trantor would have to be automated; robots, AIs, and massive computer networks running most of the traffic and maintenance functions. The world city would be in a constant state of rebuilding, a constant and purpetual urban renewal.

Matter Beam said...

I wonder if Trantorians will live on an 'energy budget' that measures how much they spend in kWh in transport, food and so on.

Stevo Darkly said...

Oops! ACK! I was so overjoyed to see a new Rocketpunk Manifesto post that I commented before I actually read it. I just saw the heading and the closing, hence my "helpful" identification of Coruscant. I completely missed the subtle sarcasm.

Now I look kind of dumb.

Ack. I have brought shame upon my entire filial Oort habitat network ... my complete genetic lineage ... and every instantiation of my digital pseudopresence. A bath in the Agony Pools of Kerlath would be too good for me. There is only one way by which I can atone: self-exile in the ergosphere of the supermassive black hole in the center of the Galaxy for ONE ... MILLION ... YEARS! Perhaps by the end of that time, the memory of my shame may have faded.

Farewell! Farewell!


OK, I'm back. (Closed timelike path; it got complicated.)

Sorry about that.

Damien Sullivan said...

Earth land: 150e6 km2. At a sub-Parisian density of 20,000/km2, 1/3 of that land can house 1 trillion people. The same land, mostly covered in solar panels at 100 Watts/m2, would generate 5e15 Watts, or 5 kW per person -- perfectly reasonable for a high density city, ignoring food and water.

Humans are basically 100 Watt lightbulbs, so we need at least another 1e14 Watts of food production to feed them. Another 1/3 of the land can be devoted to that at 2% power->food efficiency, and this isn't even trying to make use of the oceans.

We also need water, and rainfall sure won't cut it, but reverse osmosis can use under 10 kJ/kg, people need maybe 1000 m3 = 1e6 kg/year each, that's 1e10 J/year, that's another 300 Watts needed. I feel like we can wave that into the budget.

The remaining 1/3 of the land can be left as wilderness...

Damien Sullivan said...

As for commenting quickly, yeah, RSS feeds are great. I've been checking mine less thoroughly recently, else I'd have commented sooner.

Sustainable geothermal power isn't that much, actually; total heat flux from Earth's core is about 2x what humanity currently uses as electricity and heat, so forget about it for Trantor. There is a lot of heat in molten rock, if you want to 'mine' stored heat, but that *won't* be sustainable over the very long term. Might be over Trantorian timescales, I don't feel like doing the math right now.

Transport probably is an interesting question; what works for Paris or Manhattan now may not scale as well to a continent-wide Paris, as you have to move people between regions as well as within them. Then again, it also depends on the movement patterns. Putting a subway or el every half-mile really does carry a lot of people, and people only want to go so far (or rather, travel so long) on a daily basis. You'll want some high speed rail lines too, though that increases people's commuting radius -- 250 mph and stops every 50 miles means you can easily live 50 or 100 miles out from your office.

The thing about the high volume to surface area of hollowed out asteroids is that that also applies to your ability to collect solar power or radiate waste heat. At some point "we could have X people live in Y volume!" becomes "yes but they'd cook themselves just from existing."

Rick said...

The tricky thing about multi-part blog posts is that comments are already anticipating what I will be saying in the next exciting episode.

This of course is a feature, not a bug!

Also my standard Official Grump about the ever popular tactic of whacking a planet with an asteroid. Yes, Rule of Cool rules, but it is sort of the Rube Goldberg approach. And while taking 20 years to steer the asteroid into its target may be decisive, it is not swift and decisive.

If you really want to slag a planet, and your conscience is good with that, saturating it with high yield nukes would do the job.

OTOH, in a case like this, perhaps it is good to provide ample time for second thoughts ...

Rick said...

A repeated hearty welcome to commenters new and returning. But I gotta say a special hello to Ferrell, who has been a regular here since the earliest days of RM.

And if you have read down this far, a word about the long hiatus. Happily for me it was not due to health or any other personal 'issues'. (The US election did play a part, alas.)

But mostly it was due to the psychological equivalent of thread drift: I started playing with stuff, from 1930s flying boats to rapid transit, that likely would be of interest to many readers, but was not obviously and specifically germane to RM as such.

Finally I decided to hell with it; if I was gonna play with trains, I might as well blog about it. So here we all are on Trantor, waiting for the subway!

fro1797 said...

Yeah, sometimes things just get away from you! Kind of funny to think that a world-city like Trantor would have all kinds of trains; high tech/high speed monorails, hyperloop subways, maybe an old stream engine or two (maybe the Emperor likes playing with trains), more recognizable electric tramways and trollys, and of course, the iconic sliding sidewalks. I think that air travel would be restricted to official only, no civilians especially private aircraft. I think that you would need a huge department, with at least one AI/massive computer network, just to run the trains on time on Trantor. It might be one of the few things the Emperor would be interested in keeping tabs on in person, and not just a daily briefing of a couple of hundred synopsis' dealing with broad issues and status' of provences (groups of star systems). Hell, space elevators are a kind of train (or bus, if you prefer), so there's that. Maybe that's what the Imperial kids do; whoever masters the running of the Trantor Rapid Transit Authority gets to be the next Emperor...cuz ruling the galaxy is a piece of cake after that...

Rick said...

I think that you would need a huge department, with at least one AI/massive computer network, just to run the trains on time on Trantor.

Great minds, and all that. I once wrote a story in which 'real' self conscious AI emerged in the computer network running the LA transit system, because it had to understand people in order to anticipate things like attendance at a Dodgers game.

For the same reason, and with or without 'real' AI, the transit system effectively runs Trantor. Other services are just as vital (water/sewage, etc), but transit is more directly connected to people. Civil disorder? Professionals study logistics - shut down the buses and subways, and no one gets in or out of the affected area unless they walk. (Or get a ride in a police paddy wagon.)

But as for the Emperor (and indeed the Empire), no one much cares except the equivalent of the tabloid press. All those agricultural outer worlds can supply their own bread, but they rely entirely on Trantor for decent circuses. In the legends of remote antiquity, Gotham provided a similar service on the Origin World.

Cererean said...

Rick, your comment about the tabloid press makes me think that an interstellar civilisation, even one with FTL travel, will be based around cultural hegemony and soft power, rather than hard power projection and warships. The Emperor won't be able to wield any hard power beyond the throne system, but maybe it will be better that way - keep the Emperor as an impotent figurehead who serves as a unifying symbol, far away where he can't mess anything up.

That's not to say his words won't have any influence, though. Even without ansibles, the words of the Pope back in the Solar System will still influence Catholics at Tau Ceti, though given the time delay I imagine nearly all matters will be handled by the System Cardinal.

For the rest of human civilisation, Sol will be the physical and social centre of humanity for a very long time to come. Being centrally located, it will have the most up to date information about all settled worlds out of all systems, and will be able to propagate it's cultural produce across known space the fastest. Being settled the first, it will have by far the largest population, and so will produce the most new stuff for export across the interstellar net. If ansibles are available, the physical location advantage disappears, but the speed of transmission makes the size advantage much bigger.

So I don't think you need FTL *travel* to have an interstellar cultural hegemonic empire, but an ansible would be very helpful. In this case the throneworld will be less New York or Washington DC (finance or governance respectively) and more Los Angeles or Silicon Valley (media or technology). Fewer bureaucrats, more actors - or perhaps more likely CGI animators (though maybe people would watch retro-style films).

Brett said...

I was thinking about city-worlds today, albeit more about Coruscant than Trantor. They might actually make more sense if they started out as barren, lifeless planets that were chosen as neutral "capital world" sites by the founding worlds of an interstellar government (like a larger, more extreme version of Washington DC being founded on swampland). The global city-sprawl would be more understandable if the planet's habitability depended on mechanical systems from the get-go, and if there's no biosphere being displaced by the expanding city over time.

The galaxy would be chock full of potentially terraformable worlds of varying sizes to serve as potential sites for such worlds. There's imperial precedent as well, such as the founding of Constantinople at a strategic location by Constantine.

Cererean said...

Say, for example, Luna. Close to the homeworld, but without as troublesome a gravity well (a space elevator would be feasible), no oceans to worry about, and no biosphere for people to get upset about losing.

Rick said...

an interstellar civilisation, even one with FTL travel, will be based around cultural hegemony and soft power, rather than hard power projection and warships

This seems entirely likely. The disadvantages, for us, are that soft power is harder to sim, and it falls badly short on blowing stuff up. But since blowing stuff up is popular with the audience, there's the somewhat ghastly possibility of actual warfare as a component of 'soft' power. :-O

Since an ecumenopolis needs hab style life support anyway, there is indeed no reason why it needs to originate on a conventionally habitable planet. Or you could imagine a specialized kind of terraforming, aimed at providing urban amenities rather than a traditional ecosystem.

Cererean said...

You can still have warfare, even if you're just transporting in mercs or special operatives rather than large battlefleets (an idea I first read on Atomic Rockets, quoting another source).

In fact, the empire can possibly still exercise some hard power in an ansible-but-no-FTL setting, as long as it can maintain a secure link to loyalist forces. It might not be able to send fleets quickly, but it *can* provide the best tactical and scientific minds in the known galaxy to assist the loyalists. Plus, of course, the possibility of drone warfare using remotely piloted weapons platforms through the ansible link.

If you can send in assassins, all the better. If the FTL in question is based on wormholes, then the rebellious governor might be able to close the link without having to deal with a rebellion of their own if a fleet tries going through it, but if there nothing seemingly happening and he disrupts trade and cuts families in half based on his fears?

fro1797 said...

The Imperial Ministry of Life Support...That and the Global Transit Authority might need an Imperial eye watching over them. Ansibles or whatever FTL communication system is used do provide for a "cultural empire", but the question is, how difficult is it to build one? To be able to use the network, do you have to buy the box from the Imperial Communications Corporation? Will the nightly news lead with "...And now for your Imperial, Sector, Planitary, and Local news, sports, and weather" ? If it's the only source of off-world news, isn't that a type of soft power? Especially interstellar economic news. Or, if only a few military ships can go FTL without a stargate, you'll need the pass codes to use them and the Empire won't sell them cheap. They'd probably change them with frequent regularity, as well. You know, instead of spending years sending a few divisions of ground troops to quell an uppity planetary governor, just cut off the local's favorite sitcom and let them take care of the problem themselves.


Rick said...

instead of spending years sending a few divisions of ground troops to quell an uppity planetary governor, just cut off the local's favorite sitcom and let them take care of the problem themselves

Which applies even if it doesn't take years to send the troops. Hence the general advantage of soft power, if you can cultivate it.

Rick said...

A new post is up, Rapid Transit on Trantor.

Luke said...

Rick said "Finally I decided to hell with it; if I was gonna play with trains, I might as well blog about it. So here we all are on Trantor, waiting for the subway! "

Well then, you're going to love the setting I'm working on. Not only do people use trains to get between cities, they use them to travel to other worlds! None of those boring spaceships, just head town to the station, buy a ticket, and jump on a passenger car going to an alien planet.

Rick said...

I touched on just that possibility in the post linked by this one:

So far as I can tell, to whatever slight degree the physicists have left the door ajar for FTL, nothing says it needs to involve space travel in the usual sense.

But what do passengers see out the windows between stations? Do hypertrains have dome cars?

Damien Sullivan said...

Replying to a comment on the next post, but more thematic here:

"On Brett's point, for most Trantorians the experience of daily life would be living in an 'endless' urban fabric.

That said, I don't think it would be especially bewildering or easy to get lost."

Addresses are potentially interesting. Probably can't just scale an urban grid up to a world, the numbers get too big. Or maybe the postal service does internally, but people will probably want more layers of chunking.

"Endless urban fabric" can still be variable, even if fairly urban. Small plot houses, townhouses, high-rises, small neighborhood parks, Central or Golden Gate Parks, zoos and botanical gardens...

Michael said...

To strike a balance between "soft power" and "blowing stuff up", one could imagine the Throne World and Emperor occupying the position of a male lion in a pride. 95% of the time, they're basically a dangerous parasite (using soft powder to get their way), but theoretically, if a big threat comes along, they're the ones on the front line.

Rick said...

Addresses ... maybe people live on the 117,000 block of Suchandsuch Street. But in practice, no doubt there would be 'chunking' into boroughs, townships, districts, or whatever terminology developed. And indeed an 'endless urban fabric' could and probably would be highly variable.

I love the analogy to the role of male lions in a pride. Staying on good social terms with half a dozen lionesses must be challenging, even for a lion.

Byron said...

He's back!
I do have serious questions about a government setting up shop on a planet which is so vulnerable to siege. Also, good questions about life support. It wouldn't be possible to have an ecosystem which didn't produce enough food, if I understand ecology correctly (not guaranteed).

WRT ecumenopolises, I expect that you'd have quite a bit of land you couldn't build on. It's easier to go around mountains than to go over them. And people are going to want open areas. I recently (well, 18 months ago) moved to LA, and there are times when I desperately need to get out, because I rarely in the normal course of business get to places where the population density is below mid-suburban.
I do get to a battleship regularly, though. I think that thread still holds the all-time record here, and I'm a tour guide there now. It's great. I get to talk about battleships and people thank me.

Rick said...

Presumably Trantor's growth into an ecumenopolis came after it became the seat of empire, and in consequence thereof. By the time the government recognized the scope of the problem, there might not be any practical way to reverse it. The growth of an imperial capital is probably related to the vitality of the empire - compare Constantinople under the Paleologi and under the Ottomans.

Rick said...

Cool that you're giving tours on a battleship, by the way! Iowa, right?

Byron said...

Cool that you're giving tours on a battleship, by the way! Iowa, right?
It is indeed Iowa. It's a lot of fun. I get to talk about battleships for hours, and people thank me instead of running away. You should have my email. If you get down here, let me know, and I'll see if I can show you around.

Rick said...

Absolutely I will keep that in mind!

Jon Brase said...

Regarding Coruscant, I think the geeks of my generation will always retain it as the prototypical city-planet. Star Wars was the first contact many of us had with Sci-Fi, and the Foundation universe is based on an old enough set of tropes and assumptions that it just feels weird to many of us. And the memory of Coruscant will live long after the prequels pass into oblivion: it was an element of the Expanded Universe (for those who aren't familiar with Star Wars fandom, the licensed books, video games, etc. set in the Star Wars universe) well before the prequels came out. We may still see mention of it in the new movies.

I think the chances are very good, however, that Timothy Zahn had read the Foundation trilogy and had Trantor in mind when he first wrote about Coruscant.

Rick said...

Both speculations seem entirely likely = that the generation that grew up with the Star Wars universe will mainly associate city planets with Coruscant, and that Coruscant - like the idea of a Galactic Empire - was itself inspired by Trantor.

Probably there is an entire discussion out there about the source materials that fed into the Star Wars 'verse, from Lucas' first conception through streams from Expanded Universe authors, etc.

Sabersonic said...

It has been a while since I last commented on this particular blog and it's nice to see you back Rick. Anywho I figured that I might as well comment on the entry detailing the ecumenopolis. As I was reading the comments (yes, ALL of them) to see if anyone touched upon the subject I am about to bring up was J.Lewis with his indoor agriculture comment and Hollister David mentioning plants being lit beneath LED lighting for photoshythesis, and that issue being Urban Agriculture.

Specifically Aeroponics as seen in this particular segment of that Ecopolis show (does anyone even remember that show?) which is suppose to (key word being "suppose") feed a substantial number of people with little environmental impact within an equally limited amount of space. I don't know the specifics (I only skimmed through the videos and I'm doing this comment at like 5AM in the morning, I'm surprised that I can be legible this late, or early), but I'm sure a few dozen "Vertical Agriculture Districts" across any Trantor-esque worlds that came to be "naturally", artificially, or otherwise. Granted, such Urban Agriculture doesn't exactly address the non-Vegan protein side of farming, but then again that's where in vitro meat come into play. Heck, if future medicine is able to print out organs, why not print out meats? Especially a range of selection from the familiar chicken and beef, to more exotic flesh of endangered or even extinct animals. Though it'll probably be best to make sure that Human or any other sapient DNA or genetic information equivalent doesn't find itself in the food supply for, well, obvious reasons....

Now that I think of it, if Urban Agriculture does fly off well enough on an ecumenopolis-like settlement, one could potentially see a reversal of trends of urban zones supplying such produce to the suburban equivalents.

I also recall something from that Ecopolis show where a Green/Living Roof is able to regulate the temperature of a city by not having black roofs absorbed all that sunlight. It also be used as a kind of carbon sink and rainwater collector wouldn't hurt as well, pending architecture that can carry something that heavy enough to be considered a park, and considering how big Trantor's buildings are in terms of kilometers, said roof just might be the equivalent to Central Park or even Golden Gate Park.

But, like earlier comments, if the machinery breaks down for whatever reason, and especially those that regulate global temperatures and rainfall. Well, expect a lot of rioting and chaos followed by a lot of people dying on both sides of the riot shield wall.

Though I do like the idea that Brett mentioned in his comment about a brand new Galactic Empire (or interstellar equivalent) choosing a lifeless planet as the capital of said government. It's almost symbolic in a way of how they're creating a new galactic order or something to that effect.

But I gotta be honest, I've been more of an O'Neil Cylinder Space Colony guy over an ecumenopolis due to the logistical and infrastructure issues of the latter. As for colonizing Ceres portion that was mentioned earlier, well even though shows like The Expanse have the dwarf planet rotate, I'm more fond of the Jordan Carousel concept myself.