So last week’s topic was Arcologies, the concept of self-sufficient architecture, often envisioned as giant towers that are basically cities unto themselves complete with farms inside them. Today’s topic, Ecumenopolis, extends on this notion as the sort of ultimate Arcology, where an entire world has been transformed into one giant, planet-spanning city.

We’ll look at what this concept means, where it came from, some of the fictional examples of it, and some of myths and misunderstandings about the concept. This is our second article looking at what I’ve dubbed Visions for Earth. On this blog, and in science fiction, we often spend so much time off the planet, out terraforming planets, looking at megastructures, or on interstellar colonization, that we often neglect what happens to Earth itself. In almost any discussion of the future, where Earth isn’t alone but just one of many places people live, it tends to take a backseat. If it gets any attention at all it tends to be either as some lost world humanity fled or as a capital of some interstellar empire where very little of interest goes on. So I thought it might be fun to spend some time looking at Earth.

Now Ecumenopolises hardly have to be on Earth, so our concepts today aren’t Earth-centric, but today we’ll be exploring the notion of how you might go about transforming an entire planet into a city, how you stick the most people on it without turning the planet into some sort of Dystopian Cesspool, and we’ll take some shots at the idea that a planet can’t have lots of nice forests and natural spaces without not only keeping its population to modern levels but actually decreasing it. We’re also going to be looking out how a technologically robust civilization would fundamentally alter their planet in ways we wouldn’t tend to expect, and to do that we’ll be drawing on a lot of concepts we’ve discussed in the past.

If you haven’t seen those in a while and need a refresher, or just haven’t seen them because you’re new to the blog, I will often bring up in-article links such as this one that you can just click on to pause this article and open that one up in a new window, so you can read that and come back to this article when you’re done.

And if you haven’t read Arcologies yet, while it isn’t absolutely required for this article I would encourage you to read that now and come back to this when you’re done.

Ecumenopolis - A World Wide City

Ecumenopolis – A World Wide City

Okay, let’s dig in to today’s topic. The term Ecumenopolis was first coined in 1967, and like Arcologies it came up quite a while after the basic concept was first used. Besides the fact that the fellow who coined it was a Greek city planner, Constantinos Doxiadis, whose name I probably just mispronounced, we have tended to use Greek for a lot of the city related terms. Polis, meaning city, is regularly used in the word Metropolis, literally Mother City, and is the root word of policy, politician, and police for instance. Ecumene, literally “Inhabited”, was routinely used to mean the world and you’d probably best know it from the term Ecumenism, in regard to unifying churches. So there’s a bit of triple-dose on that for the term, since it is using the term in the world spanning context, the original one of inhabited, and the concept of merger and unification of cities into one big whole.

The level below this but above metropolis is usually called a megalopolis, either a very big city of, as mega would imply, more than a million people, or a merger of various cities and suburbs into a bigger whole, such as the region stretching from Boston down to Washington DC, sometimes called the Northeast Megalopolis. There’s a lot of other polis terms, Cosmopolis, Astropolis, Necropolis, Acropolis etc. but for our purposes today we’ll be just looking at it as stepping from Metropolis to Megalopolis to Ecumenopolis at the planetary level. But I’d say a solar-system wide equivalent, basically a Dyson Sphere or Swarm, a Kardashev-2 civilization, could maybe be deemed a Dysonopolis, Solopolis, or maybe Heliopolis if we wanted to stick to Greek, and a Kardashev or K-3 galactic equivalent could be a Galactopolis or maybe the aforementioned Astropolis. Now the basic concept is easy enough, a city sprawling over a whole planet, maybe up to and including the oceans and polar regions. I believe the first example of this in fiction was Isaac Asimov’s Galactic Empire Capital world of Trantor, from his classic Foundation Series but I could be wrong.

Last week I credited the popularization of the term Arcology to the SimCity game franchise but we dug up an earlier reference in William Gibson’s Sprawl Trilogy right in the first book, Neuromancer, in 1984 which definitely predates that article game and as one of the cornerstone science fiction staples of the Cyberpunk Genre along with Blade Runner and Snow Crash is a lot more likely to have been the source that popularized the term. Still I’d say Asimov’s Trantor is the best known fictional example at least until the Star Wars prequel trilogy showed us the city-planet of Coruscant half a century later. Trantor showed up in a number of his works besides the Foundation Trilogy and he later slightly retconned many of them to weld them all together, and one of those, the almost equally famous Robots Series, in its first book the Caves of Steel, spends a lot of time in Megacities, the titular Caves of Steel, exploring a sort of precursor concept of Ecumenpolises and large Arcologies.

Amusingly, for an author who normally was very good with his math and science in his writing, those megacities, where every human on Earth lived, housed an unbelievably enormous 8 billion people, just a bit over our current total population, and Trantor, a city-planet described as having paved over everything including the oceans, and building many stories high, even miles high in the sky and underground, holds a whopping 40 billion people and had twenty planets in its neighborhood that did nothing but grow food for them. Bringing in food on enormous fleets of ships and bringing fertilizer back to those agriculture worlds. Needless to say, that’s all wrong, especially since access to nuclear fusion is explicitly mentioned in both book series, and we’ve talked a lot about how fusion is a game changer in terms of agricultural production. We also talked a lot about how robots are for both agriculture and construction and they obviously have those in the Robot Series, though how much they despise robots and don’t like using them is a pretty big theme in that.

In that book, Caves of Steel, the protagonist does have an internal monologue about potentially transforming Earth into one single giant city. Now 40 billion is just ridiculously low, you can pull that off even without a super-power supply like fusion by just green housing over all your farmland, though doing so would mean a very large increase in overall maintenance cost and manpower unless you had robots. And incidentally when I refer to robots I’m not talking Asimov style androids I mean slightly more sophisticated versions of the entirely non-human type ones we employ in factories and these days even to mow lawns, vacuum floors, and clean pools. If you did pave over an entire planet like that, ocean and ice and all, even just one level high, you’d have 200 million square miles of area, or 5.5 quadrillion square feet or 500 trillion square meters. If we used our 10,000 square foot, or 1000 square meter, figure from last time for all the space one person needed for housing, food, recreation, work space, warehouses, and shared public areas, which we said at the time was meant to be very rounded up and generous, that one level high paved over planet would support half a trillion people.

And in the case of Asimov’s Trantor, it is described as miles high and deep, or thousands of levels since you get about five hundred from one mile, and they imported their food too. So the 40 billion figure is just way off, other fictional Ecumenpolises like Coruscantfrom Star Wars and Terra from the Warhammer 40k fictional setting usually went for a trillion, or low trillions. But we just found you could rather generously portion every one 10,000 square feet, something like ten times bigger than a reasonably comfortable family apartment, and get half a trillion in one level. You do four miles up and down, about 2000 levels total, and you get a quadrillion people. And you could kick that up an order of magnitude or more just by building higher and not giving people quite so much personal space, and fictional examples usually do paint them as very cramped. Now we’ll see in a moment why space, even for growing food, isn’t the issue at all and why a quadrillion people just isn’t doable, because of heat, but let me tangent off onto scale in science fiction for a moment.

It’s a standing joke and Trope that a lot of science fiction writers have no sense of scale, usually in terms of size or power or similar notions but population is always the one that bugs me personally. When looking at a setting I always try to assess it under what the fictional setting is giving us for technology, that’s a major aspect of the blog, we often explore seemingly crazy ideas and how they aren’t when grounded in reality under the specified assumptions. Science fiction, in particular the Space Opera genre, always seems to think a galaxy has a few thousand inhabited worlds sporting maybe a billion people each on average and tends to try to awe us with empires of trillions of people and armies of billions and fleets of thousands of ships. Star Trek tended to be the worst for this, a federation of hundreds of worlds and power sources that made fusion look weak and advantages like matter replicators and transporters yet for some reason they tended to have maybe one ship per planet with a crew of a few hundred or a thousand for maybe a whopping million personnel, on par or smaller than what most major nations here on Earth field, with only about a hundredth of our planet to supply that, not hundreds of planets.

Interstellar empires ought to be able to throw millions if not billions of mile long ships into the field without even noticing the expense and their home worlds could be pristine natural forests while those solar systems would not regard a trillion people as their population, but more akin to how many plumbers or painters or writers they had. That said, the quadrillion plus population on a planet isn’t viable, not because they don’t have enough space, but because if they don’t have some novel way to get rid of heat, even if the only heat being emitted was by people’s bodies because everything else was done off world or was super-efficient, people are basically 100 Watt space heaters.

A quadrillions of us, 10 to the 15th, would emit 10 to 17th watts of power and that’s basically what the planet absorbs from the sun, and you need to scale that up by about a factor of 100 at least if you want to feed them food you grew there on the planet, because even the super-efficient kind of hydroponics we’ve discussed in the past is still only about 1% efficient at turning electricity and light into food calories. If you’ve got to get rid of 100 times the normal heat our planet receives, using the blackbody thermal radiation we’ve discussed in the past a lot too, mostly recently in the Matrioshka Brain article, your planet’s temperature increases three-fold, and that’s in absolute temperature, Kelvin, and would be hotter than Venus or Mercury. Just doubling a planet’s heat output would raise the temperature almost 20%, which would be about 150 degrees Fahrenheit or 66 Celsius.

So even if we blocked off the sun, or at least the infrared radiation from it, which does us no good except to heat the planet, and even if we used all sorts of tricks like giant radiating fins and antennas, which will talk about in a bit, unless you’ve got some special trick for getting rid of heat you’re going to roast everyone alive long before you’ve got to worry about living space or food. And before you think we could just deliver food grown elsewhere without building up heat, you know import everything down space elevators, that doesn’t really work either. Objects gain kinetic energy as they come down to the planet, same as you have to give them a lot to get off the planet. A pound of bacon imported from the lunar hog farms and rich in fatty goodness has 2500 calories, which in terms of joules is a million. You want to move a pound of mass down from low earth orbit it’s going to gain over a million joules of energy which all has to end up a heat at some point. So while you can have more people if you’re importing everything you still have more heat being built up, and you still get problem even if you’re importing everything frozen or trying to bring down big blocks of ice from space.

Now if you did have some super-science trick for heat, the sky’s the limit, quite literally, since you can just build until you’ve encompassed the whole atmosphere and keep going. At that point there’s no real point in thinking of it as floor area anymore, just volume, and 10,000 square feet a person easily becomes 100,000 cubic feet. Which would give you something like 4 times 10 to the 18 or 4000 quadrillion or 4 quintillion people. And if you’ve got stuff like wormholes or teleportation to get rid of your heat and artificial gravity or anti-gravity to keep things form collapsing, which they do in Star Trek and most sci-fi settings, you could do stuff like that. We’ll assume we don’t, and just keep it to realm where nuclear fusion is available and we’ve got robots that aren’t human level intelligence but can do a lot of groundwork like constructing buildings under supervision or water gardens and harvesting crops with minimal oversight. We might never get those but they tend to both be considered by a lot of futurists and scientists to be things we probably ought to have before the end of the century and maybe before another generation has passed.

On the grand planetary scale though, if we have significant off world industry, fusion isn’t strictly necessary and there are some disadvantages to it, since while power plants down on Earth could churn out the power for optimized LED lighting of plants those reactors are still going to be generating tons of waste heat while making that power. If your goal is to minimize heat on a planet by, for instance, using glass out at our LaGrange point to intercept infrared light but let visible light through, you might be better off using huge arrays of tinted lenses and mirrors to beam that same photosynthesis optimized light down to Earth where the useless frequencies were just not sent on.

Similarly, if you’ve got decently cheap and sturdy superconductors you might want all your power production done off world where you can get rid of that heat a lot easier, either as fusion reactor or solar panels. Superconductors let you move power over basically any distance without the loss of power to heat that normal conductors give us, and there is a concept called a thermal superconductor that lets you move heat by conduction that would also be invaluable for cooling, we won’t go into it now other than to mention that the availability and specific properties of such materials would probably have a huge impact on Ecumenopolis design and maximums. So fusion, while incredibly helpful, isn’t absolutely necessary for this sort of setup we’re discussing and indeed there would be some pros and cons in contrast to alternatives.

I sometimes get accused of being overly focused on fusion, which I regard like someone in the 19th century telling someone they were overly focused on internal combustion engines, but the point is cheap power in massive quantities and fusion is the best candidate for giving us that on the horizon. Get yourself the ability to convert matter straight into energy, or to make wormholes so you can just dump one end right into a star, or grey goo Nano-robots who can transmute an entire asteroid into a planet sized solar panel overnight, and those are better power sources. And since in this context I actually mean human power sources mostly, being food, those same Nano-robots might be able to just transmute rock right into bacon-double-cheeseburger with way less power than growing one would take, or people might be all cyborg or post-biological and not even need much or any normal food.

We work inside the context of the technology’s we think plausible, for today that’s fusion and reasonably smart but not human-smart robots helping regular old humans grow their food and construct their buildings. Okay, so in that context, assuming we could get away with maybe adding 50% to the heat we need to purge off our planet, either because we’ve done some tricks to help us radiate away heat or blocked some of the useless infrared from the sun, and that we only need maybe 10,000 watts of power per person for all our food and industrial and recreational needs, that would give us a budget of 10 to the 17 watts divided by 10,000 watts per person or 10 to the 13, which is 10 trillion. That’s way closer to the trillion or so seen in more modern fictional portrayals of Ecumenpolises, and is a good round figure. So let’s just say 10 trillion is the upper cap for people on Earth. A bit over a thousand times our current population. Last time we threw together an example Arcology big enough to grow all the food for 5000 people and leave them lots of personal space, and it was only a hundred stories high and 400 feet in radius. As I said then you could build taller or wider and we were pretty generous giving everyone 10,000 square feet, though that figure included all their hydroponics, shared public spaces, parks, warehouses, stores, and so on. If we just used those, to fit 10 trillion people, we need 2 billion of them. Could we even fit that on Earth or do we need to go taller? Well let’s run the numbers. Earth’s surface area is just under 200 million square miles, land, sea, everything, and conveniently we’ve got 2 billion of these Arcologies, almost like I originally cherry-picked 5000 people to make the math easy, so ten per square mile. These things happened to have half a million square feet of area per floor, their footprint on the ground, so we’d need 10 times that, five million square feet given over to them on each square mile, and a square mile has 28 million square feet, so only 17% of area is actually taken up by them. If we only wanted a trillion people, you’d conveniently only need one Arcology per square mile taking up only 1.7% of that square mile.4 or 5 times as dense if you want to leave the ocean unused and the coldest parts of the polar regions. Of course we could easily double their height, ours were 100 stories high but we already have a couple dozen buildings nowadays about that tall or taller.

We can definitely go taller, we can also go lower, as in underground, since most of the space in the Arcologies is not actual residential living space where people would get touchy without windows. Heck if you want to go for mile high towers that gives you 500 floors, not 100, and since the air is still quite dense enough to breath a mile high you could still have balconies if you wanted and even some sort of pyramid or tiered cone set up that was much wider on the bottom and still have tons of space left over.

If you wanted to go with Arcologies that were skinny needles jutting all the way up to the top of the atmosphere maybe with space elevators extending from them or connecting up to an orbital ring like discussed in that same article way back at the beginning of the megastructures series, you could do that too and very conveniently hook yourself up to space. And we’ll talk about space more, outer space, in a moment. Talking about space, as in space per person, what we’re seeing is there is plenty, once we go vertical. If I dropped 10 trillion people down on this planet, and only in the places where they wouldn’t drown or freeze to death, everybody would only have about a 10-foot square to themselves. And that is very like the super-cramped megalopolises or Ecumenpolises fictions usually shows us, but they always show those with a very vertical component and there is none in this 10 foot by 10-foot box we just drew, the size of a decent bedroom. I think that’s why I beat on this dead horse a lot, about population density, because we’ve known how big the planet was since long before we had science fiction and we haven’t done any complex math here. Just straight arithmetic.

You know we see the same cramped, submarine like quarters on spaceships a lot in science fiction where you’ve got ships miles long with crews of maybe a thousand, but when you run the numbers on a lot of these ships, even if you assume they only give over 1% of the ship to crew accommodations, your junior personnel shouldn’t be sleeping 4 to a room, they ought to have closets that size. And the power outputs needed for ships like that just to wander around solar systems, forgetting all the Faster than Light stuff, as we saw in the interstellar colonization and black hole starships articles, tend to be enough to power entire planetary economies all on their own.

Is Ecumenopolis possible?

Is Ecumenopolis possible?

Science Fiction can still be good even when the science and scale is all messed up but whole plots or concepts like crews being low on food or freezing or asphyxiating in ten minutes when the power goes off or not having enough water for showers are just kind a ludicrous when they’ve got huge ships like that with massive power supplies outright described as fusion or matter-anti-matter reactors. It’s like an entire story revolving around how poor and cash strapped the protagonist is while they’re walking around covered in solid gold chains carrying a briefcase crammed full of hundred dollar bills while sorting their loose change to buy a cup of coffee. Portrayals of Ecumenpolises tend to be about the same way for me, because they get described as so huge in terms of sheer space then someone goes and puts a population figure on it and you realize that if that was the case, 40 billion people on a planet hundreds of levels deep from land to pole to ocean, if they were evenly distributed everybody would feel like they were blundering around an empty skyscraper all by themselves, and if someone flicked the lights on in every room on the planet they’d all catch fire and melt soon thereafter.

If you pave over and multi-layer a planet like that it’s just because you want a lot of space, and you like your space more than efficiency so maybe you’re making each floor a couple hundred feet high so you can replicate forests or tundras or lake or deserts and you carefully light them with a heat-efficient blend of artificial sunlight. You can squeeze out mother nature so it’s nothing but people, our pets, our parasites, and our provisions, but again you can outright double and then some your available sunlit land by just removing the infrared light from the sun from our solar budget. So you just build one layer above the other, artificially light the one and use it for people. And that’s without doing any other spectrum tricks like only using photosynthetic frequencies of light in most places and trimming back the lighting level to the minimum to maintain that ecosystem. Of course everybody could live only inside a few towers linked up to space stations or in space stations, we’ve spent a lot of time talking about that on this blog, rotating habitats, and that helps a lot with the heat issue to.

Though it might be better in many cases to be putting your nature preserve in those space stations since you can make them quite larger and seal them of very easily from reckless humans or invasive species. But I’d argue all those space stations near a planet, all those orbital rings or space elevators or sky hooks, basically still remain part of that planet and part of that Ecumenopolis. I mean if you’ve got an orbital ring hanging a hundred miles over the planet that’s a lot easier to get too then the other side of the planet by flying. As I mentioned back then if you had one of those, or several, while they’re very wonderful for launching or receiving space ships they’d probably get used even more for rapid transport around the planet because without air drag and friction it takes virtually no energy to get up to very high speeds.

You can also potentially dump heat that way too, not infinite amounts of it but it’s a lot easier to radiate heat when you’re using non-flat surface up in space than when you’re trying to purge it of the surface of a basically smooth sphere with a thick layer of infrared absorptive atmosphere over it. You get the equivalent of a thermal superconductor, and you can lift a lot of your heat away for easier dispersal up in space. And once you have stuff like space elevators or orbital rings in place, it is just about as easy and cheap to build an Arcology in low orbit, or high orbit, as on the ground, and you don’t have to worry about its heat very much. And you could build a whole swarm of these things around your planet like a mini dysons warm without even denting the material available on Earth or the Moon. I usually call this the Terrain Cloud, or when I’m generalizing and avoiding the accursed letter R, a planet cloud. Sort of a big brother of the Ecumenopolis and probably a more realistic scenario too.

You could run something like this entire on sunlight, so it’s an option if you never get fusion. In that sort of setup your effective land area for people and critters is basically whatever the surface area of a sphere the same size as it would be, and you hardly have to stop such a cloud at geosynchronous orbital distance, or even way out at the moon, but for comparison a swarm that occupied the space out to geo synch could have as much as fifty time’s the Earth energy and heat budget and one out to the moon could have about 4000 times that. And then you really can cram quadrillions of people, or tens of quadrillions, into your super-city or Planet Cloud while still leaving a good dozen Earth’s worth of living area and habitat over to the equivalent of total nature preserves. So if you wanted to blow something like an entire continent over to just being protected habitats of various extinct ice age critters you’d grabbed the DNA for and cloned, you could do that for a chunk of your budget comparable to what a city spends on a zoo, and you can obviously tailor that climate perfectly and keep out problems that might disrupt it.

I don’t particularly think our descendants would be trying to devote giant portions of their space and economy to preserving Earth’s native Flora and Fauna, or that would be their big focus in constructing these sorts of things, but I like to point out options like this because when you start talking high-tech civilizations, especially high population ones, lots of people tend to picture endless tree stumps or concrete parking lots and thinking every species will go extinct. Extinction is bad, and we should do what we can to prevent that, but it is worth mentioning that we already have the technology to read a critters DNA into digital format and print DNA, even if we didn’t have frozen sperm and embryos, let alone surviving members of that species.

I really don’t like to say anything that might encourage folks to be reckless with our environment but I also don’t like to obscure plausible possibilities and solutions, and I would seriously doubt anything that’s gone extinct in recent years will stay that way, even if our civilization ends up in one of those concrete dystopian hellholes we just got done showing weren’t very realistic. It’s just not that hard to keep huge banks of frozen sperm and eggs or tissue or outright digital copies of DNA lying around. It took us a decade and a few billion dollars to sequence the human genome, now it takes a few days and a few thousand bucks. We usually put the total number of species in the low millions, at a few thousand bucks a piece, a number likely to drop further, that’s low billions and pretty affordable. Keeping them on ice too isn’t terribly expensive in space or energy either.

DNA doesn’t take up much space, the Smithsonian’s bio-repository isn’t much bigger than a house and has room for 4 million vials all on its own, and that’s one of things that gets a lot cheaper when you build it bigger. Nor would minor damage or data loss be the end of things, besides keeping redundant copies DNA is a blueprint, you can guess what a damaged or missing bit was supposed to say and being wrong usually won’t matter too much, those sorts of minor errors happen routinely when your DNA replicates or you have kids. I hate to bring that option up because it’s very off subject and it should never be necessary, we can be better stewards of our planet than that, but I find that Ecumenpolises much like conversations of human immortality tend to make a lot of folks flinch away from them, and while for the latter, people will hand wave at the notion that very long lives would be boring and undesirable, for Ecumenpolises the Hand waves to dismiss the idea are quality of life, what we’d do with all those people, and what havoc it would do to mother nature.

I can understand the first and third one there, quality of life and fears for the environment, that’s why I spend so much time on this subject and Arcologies talking about how luxurious and spacious and ecologically sound such things could be. That middle one, what we’d do with all those people, much like when folks suggest we have too many people, is one of those responses that I never really understand how to reply to. I can certainly understand why someone might think having more of us could be a bad thing if it meant we needed to plow every forest under for farms and couldn’t have any luxuries, but all things being equal more people is good and I would tend to regard that as a self-evident truth. Which is to say, one that does not require proof or discussion. I’ve made that point before in conversations about the Fermi Paradox, that life, especially intelligent life, is probably considered more valuable to most intelligent species than inanimate asteroids and dead planets so that I’d have a hard time imagining why they wouldn’t try to turn those things into habitats for life, but for some folks that doesn’t seem to click and I’m never sure why. Maybe they’re right, but I’ve never had a conversation with a chunk of rock whereat laid out its reasoning for its inherent value, I suppose if it did I might change my mind but until then I’ll keep to my stance on the matter. If anyone’s had a nice chat with a rock saying otherwise maybe you can explain it to me, though I’d probably want to check your blood alcohol level or do a drug test on you first, no offense. Back to the space angle of things.

Outer space not living space. We often see these world cities with many ships in orbit or landing or leaving or figure folks and freight go up and down in space elevators. Which is as it should be but, keeping in mind the elevator conundrum we mentioned last time, how much traffic is that? I mean a Ecumenopolis, we think of that as this big planet of planets, the capital, a place with probably a lot of tourism and trade. You look at the tourism figures for a lot of our great cities, just the tourism, and usually it is in excess of the total population. So I don’t think we’d be excessive, and honestly rather conservative, to imagine that a Ecumenopolis might process ten trillion visitors a year, and to assume a like amount of trade goods and personal baggage made the trip. But call it ten trillion people or a trillions tons. There’s about half a million minutes in a year, or 20 million people every minute,40 since they have to come and go.40 million people checking through your spaceports, coming or going, every minute, nearly a million a second. You’d be processing the entire current human population going each direction every work shift, and who knows how much baggage or trade goods. When we think about building space elevators, when we talk about them in science fiction and how a planet has one, we usually don’t think of those embarking a passenger every second.

So you are going to need a lot of them, whether we are talking the classic space elevator or just a hundred-mile-long one up to an orbital ring. You might even need one for every Arcology, especially since as I mentioned a lot of folks would use such a thing for travel around the planet. As I mentioned way back in Megastructures Article one, you don’t need those tether to only be at the equator or run straight up vertically, so long as you’ve got multiple ones connecting from different directions to cancel out any lateral forces, nor do orbital rings need to be around the equator. It would depend more on just how much throughput you needed, which we can’t really predict. One school of thought says humans, assuming we haven’t gone all cyborg or post-biological in the future, which would seriously increase the total population a planet could handle too, would pack pretty light because mass is always an issue in travel and if you’ve got really excellent automation and 3D printing they could get almost everything they needed when they arrived and leave it to be recycled when they left. Ditto the good people of Earth might not put much value on where an item was made or grown because we can make identical versions anywhere so the Lunar Hog Farms might not have any market off world to sell their bacon.

Alternatively, in a post-scarcity kind of society people might be even more prone to liking foreign goods seemingly because they’re foreign and a lot of folks don’t like the vat grown bacon of their home Arcology, because it’s so mundane and was never a part of genuine pig and the Lunar Hog Farms are in business and so are the huge greenhouse habitats floating around the Lagrange Points shipping in wheat grown under the genuine honest to goodness real sun. And discerning people only drink bottled water straight from icy rings of Saturn, where no living creature has ever drunk it before.

Ecumenopolis

Trying to predict people’s tastes in stuff, especially luxury items, is virtually impossible even a year or two in advance so I won’t bother trying for centuries ahead in time. But even if we assumed it was just those tourists, that’s a lot of ship docking and leaving every day too. You think of that classic spaceship with hundreds or maybe a thousand or so people on board and you’ve got several thousands of them arriving and leaving every second too, and since they’d probably be spending at least an hour or so docked or accelerating or decelerating to arrive or leave, you’d be talking about several million ships hanging around the general area at any given time. Way, way more if we’re talking about that Planet Cloud mini-dyson enveloping the general area. I was making grumpy statements early about how a lot of sci-fi setting seemed to have relatively tiny fleets and this is why.

It takes a lot of tonnage to service a planet like this even if they don’t do much importing and exporting and even the kinds of giant armadas that used to be limited to books only but that CGI lets us do on TV and in film nowadays would get swallowed up in that sort of traffic like they were insignificant specks. It always comes back to scale, and it all does seem pretty ridiculous and overwhelming but as I mentioned earlier, we keep ourselves grounded in reality under the specified assumptions. All we did today was look at those options, assign them numbers, and do the arithmetic. Things change a lot when you actually plug in the numbers and they can come out unbelievably huge, but they’re unbelievable because we’re having difficulty absorbing their sheer scope and immensity, not because our reasoning and logic was bad. So we’ve got this notion then of the Ecumenopolis, the world-spanning city, and we see now that it doesn’t quite pass muster when inspected in the traditional form.

It’s not that we can’t pack trillions of people on a planet, if we’ve got fusion or can beam power down from solar satellites, it’s that unless we can deal with the heat produced in using all that power we can never actually have that many people all tightly packed as those representations tend to imply. In the end our Ecumenpolises had way more people than they are usually said to have when people put numbers on it, yet at the same time had way more space to themselves. And we also see the planet doesn’t end at the surface, you can dig your Arcologies down deep, or do whole layers separated by hundreds of feet, or float them on oceans or stick them down in oceanic trenches. Or you can keep building them up and directly attach them to space stations and how those space stations in many ways could be an integral part of that planet or even where the super majority of the human population, or even the critters, make their homes. This is of course just one possible vision for how things on Earth could develop, and if there’s interest we may come back and look at some more in the future.

But we’ve a lot of other subjects to cover first and some I’ve been putting off for too long. Next week is our black hole farming article, which will either be our first look at civilizations at the end of time or our entire look, depending on how much I can cut the script down. Big long topic. So it might be one article or might need to be broken up like we did with Arcologies and Ecumenpolises. I don’t know if it should be one article, maybe two, or a short series, if that last Black Hole Farming would be article 1 of the series on the civilizations at the end of time. Every time I think I’m running low on material discuss I seem to end up with some new topic that when I’m done with it feels like it should have been three or four articles instead of the one I ended up making. We have a poll this week to decide what comes after that, and it is past time we got back to the Faster Than Light series and Habitable Planets series for our look at Wormholes and Ocean Planets.

I have a suspicion both series will go on long hiatus after that, we’ve so much other material to cover and those haven’t generated as much interest as other topics so I’d rather continue on with those topics or new one. I’ve also been getting asked regularly to discuss KIC 8462852, also known as Tabby’s Star, for around a year now and got asked three separate times just today as I was redrafting this script so I’m giving in and putting it up as an option.

As always suggestions remain welcome. Ideas for the blog, topics for articles, questions about today’s subject, and general comments are always welcome and I encourage everyone to flick through the comments where people often do ask a lot of novel questions and I try to reply to as many as I can and encourage folks to try to answer any questions they can too.

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