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 video looking at what I’ve
dubbed Visions for Earth. On this channel, 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 channel, I will
often bring up in-video links such as this one that you can just click on to pause this
video and open that one up in a new window, so you can watch that and come back to this
video when you’re done. And if you haven’t seen Arcologies yet,
while it isn’t absolutely required for this video I would encourage you to watch that
now and come back to this when you’re done. If you do happen to be new to this channel,
I suggest you turn on the close captions too. Some folks find me hard to understand and
the topics we discuss on this channel tend to be complicated enough on their own that
we don’t need an additional hurdle of my speech impediment interfering in that. Also, this week we will be having a poll again
for future topics, I’ll talk about that a bit more near the end but while the poll
is active you should see a little marker in the upper right corner you can click on to
bring up that poll and vote. Okay, intro complete, announcements complete,
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 video 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 gamechanger 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 greenhousing 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 Coruscant from 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 channel, 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 homeworlds 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 quadrillion 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 video, 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 scifi 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 grunt work 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 miles 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 video
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 ecumenopolises 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. Ya 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 videos, tend to be
enough to power entire planetary economies all on their own. 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 channel, 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 skyhooks, 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 dyson swarm without even denting the material available
on Earth or the Moon. I usually call this the Terran 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 geosynch 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 Ecumenopolises much like conversations of human immortality tend
to make a lot of folks flinch away from them, and while for the latter, people will handwave
at the notion that very long lives would be boring and undesirable, for Ecumenopolises
the Handwaves 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 where it 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 Ecumneopolis, 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 Ecumenpolis 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
Episode 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 drank it before. 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 thousand 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 scifi 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 Ecumenpolis,
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 Ecumenopolises 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 supermajority 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 video,
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 video or might need to
be broken up like we did with Arcologies and Ecumenpolises. I don’t know if it should be one video,
maybe two, or a short series, if that last Black Hole Farming would be episode 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 videos 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. You can click on the poll to vote if you haven’t
already. No channel update this time, various previously
mentioned things are still ticking along and I want them in place before I launch any other
channel additions. Though as always suggestions remain welcome. Ideas for the channel, topics for videos,
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. If you enjoyed the video, hit the like button
and subscribe to the channel for alerts when new videos come out. You can also share the video with others and
help support the channel on Patreon. Sometime in the next month or so we’ll hold
our first raffle for the channel patrons to let the winner pick a subject for a video
too. In the meantime feel free to watch any of
these other video series on the channel, and since I seem to get asked a lot what this
or that song was in the background, let me just note that I do always include the music
in chronological order during the credits. Again next week is Black Hole Farming and
until then, have a great day and we’ll see you next time!
Interesting channel.
Isaac Arthur should write a book, in my opinion. Maybe, without the commentary on the failures of science fiction authors, and more about the actual possibilities.