So, somewhat inspired by earlier suggestions of not calculating the surface area of Hive Sibellus, I decided to not only do that, but also to take a look at the population figures. The result is of course that these things don't add up, and that the information given is contradictory.

The facts, as given in the Dark Heresy Core Rulebook:

Populations:
Planet Scintilla: 25 billion (p290)
Hive Sibellus: 2x population of Hive Tarsus (p293)
Gunmetal City: "For now, it is a 4 billion strong foundry station" (298)
Ambulon: "Ambulons equivalent of midhivers are the hundreds of thousands of workers…" (p297)
Wilderness: Unknown

The population of Sibellus then, is 2/3 of what remains of Scintilla’s population when we subtract GMC, Ambulon and the wilderness.
Lets assume the population of Ambulon is 1 million. Mid-hivers make up the largest part of a hives population, and they are numbered in the 100 000's, so 1 million seems reasonable. Lets also assume that the wilderness is not part of the equation. This gives:
2/3 * (25 - 4 - 0.001) = 2/3 * 20,999 = 14 billion (almost).

Dimensions:
“The hives themselves are astonishingly large …. cover continents and stretch for miles into the sky” (p 16)

Sibellus: "8000 kilometre-wide bulk", "skirts touch the coast itself - a 500 kilometre belt"
At most, this makes a circle with diameter 8000 Km. This results in a surface area of 50 240 000 Sq.Km
However, the hive is probably not circular, but shaped more like an oval, oblong shape, where 8000 is the longest diameter.
The silhouette figure of Sibellus in Purge The Unclean (p 32) shows Sibellus to be higher than it is wide (by a factor of about 1,1). Obviously, Sibelus cannot be over 8000 Km tall. The International Space Station is in orbit some 350 Km above earths surface.

So I conclude that the picture either shows Sibellus from “side view”, showing the narrow side of a hive shaped like a long sausage, or is very wrong in its depiction.

If we assume an elliptical shape, 3000 Km thick across the narrow side, this gives a SA of 18 840 000 Sq.Km

By comparison, Europe has a SA of 10 180 000, and North america has 24 490 000 (Wikipedia.com)
So, we have a massive Hive, covering an Area larger than Europe, with a population of more than twice that of our Earth.

So far so good. The problem comes when we look at population densities.
4 Billion people spread across 18,8 million sq.km, gives a population density of 743 people/Sq.km

By comparison, New York City has a density of 10 000 people/sq.km, and Mumbay heads the charts at 22 658. These are packed city centers, but still have parks and open areas. Not even close to Hive-density.

The Hive is described as a crowded place, and I feel it should easily be as crowded as our most crowded cities here on earth today. However, put a density of 20 000 over an area of 18,8 million sq.km and you end up with 376,8 Billion, and thats just on "ground level".

I don't know how many levels Hive Sibellus has "on Average", but I'd Imagine at least 3 (probably a lot more). That gives 1,1 Trillion people.

Which puts Tarsus at 565 Billion, and Scintilla total at 1,7 Trillion people. Almost.
That’s a lot of people And would require massive food imports. It's also a far cry from the stated 25 billion.

If we were to keep the population size, and calculate area based on a density of 20 000, the resulting SA is a mere 700 000 sq.km. A circle less than 1000 km across.

So which is right? The Size, or the population numbers?

Having come over from the 40k games(including Necromunda), I think I can shed a bit of light on this topic for you.

There are vast sections of the hives that are unihabited. The hive was formed from cities. When the old cities got destroyed or were no longer habitable they current society built on top of the old structure. This resulted in a hive like structure with the majority of the population living in the mid to upper sections of the hive.

The old Necromunda rulebooks gave a breakdown of where the populations dwelt. The upper tier or spire was the habitat of the Nobility and weathly living in the hive. The mid sections were occupied by the merchants and and middle class in the hive. The lower level was composed of the lower classes, scum and gangers. Below the lower, habitable levels there are sub levels. Based on the depiction in the book, this is where the vast majority of space in the hive exists. In the sub levels you had vast stretches of unoccupied space. Sometimes due to being toxic or just uninhabitable by humans, or sometimes because the area had been isolated by earthquakes or landslides. These sublevels are considered deadly and off limits to most citizens. Creatures beyond imagining prowl the darkness of this area stalking those foolish enough to go down into the depths of the hive.

So, while you can have enough area to support populations of the size you mention, it's unlikely that every square kilometer of the hive is occupied. Most likely only a minor portion of the hive is really active with human population. The rest is the playground of some very dangerous creatures. As far as overcrowding. That mainly occurs in the habitable areas. Believe me, if the populations could spread out and push down into the lower sublevels, they would. It's just not possible due to the danger those sublevels contain.

The Necromunda Rulebook really gives those interested a flavor of what to expect in the depths of a hive.

I hope this sheds some light on why your numbers might not be adding up to what is listed in the book.

Thanks for your reply and information!

I had indeed checked the Necromunda book to llok for input, but it still leads to some interesting figures.

If the population of Sibellus were condensed to one area, living about as tightly packed as people in Shanghai do today, they would cover an area just over 1 million square kilometers. Thats less than 6% of Sibellus total surface area. As we have no definite info on the height of Sibellus, I cannot speculate on volume distribution, but obviously as people stack on top of each other, they will use even less surface area.

So I'm all for large crush zones, toxic wastes, haunted sub-sectors, recycling vats, manufactoria, etc, but 95%+ of the total hive seems to be pushing it. That certainly is not the picture painted by the text, as a teeming hive with constan activity all over.

In reality, I don't think they put much effort into figuring out population size. They probably just said...25 billion sounds about right to me....don't you think?

Hrm, looks to be a case of authors turning out some numbers that look and feel massive and over the top only to, once the calculations are done, prove to be way under the ceiling.

Beyond the large swaths of hive that's just completely uninhabitable, another thing that could contribute to the discrepancy in numbers is the 25 billion might be the official population of Scintilla as recorded by the Administratum. If that's the case, then only those with a cognomen are counted which means that there is the vast underhive class which goes completely uncounted or miss counted at best. Heck, if you want to get all grimdark you could assume that half of Scintilla's actual population is underhive dregs and ciphers giving Scintilla an actual population (discounting wilderness areas) of something closer to 50 billion... though not being good at math, I don't know if that would come any where close to filling up the hive enough to knock that 95% empty ratio...

I think there was some misunderstanding between one author and another regarding the shape of Hive Sibellus.

The description in the rulebook clearly points to a Blade Runner-esque megacity, with many levels on top of each other. In Apocrypha: vehicles, grav-carriages are mentioned as a way of transport between the spires, suggesting that they are scattered across the whole city and that there is open air between them.

On the other hand, the silhouette in PtU is a direct port of Necromundan Hive, with its conical shape.

I guess it's up to you to decide which to use, because these two visions are in conflict.

Oh, and I recall the population of Necromunda to be somwhere along 300 billion, for all that it helps. It sounds better, but is still far from your 1,7 trillion.

Well, Nobles want space, so I guess it's like wealth; the top 10% control 90% of it or something. *G*

I would lean more towards your population density numbers than the total population of 25 billion.

25 Billion sounds like a lot of people, especially when we consider Earth now has just over 6. But there is a LOT of open space on our planet. 25 billion people is nothing.

Adjust the population densities for large areas of unused or broken down areas of the Hive, but also consider that there are many many spires and the like as well. More than three levels worth at any rate. I would estimate, personally, that the total population of Sibellus to be in the neighborhood of 1.25 Trillion.

This makes things a little more clear as to why there are entire worlds devoted solely to agriculture, why a lot of people eat very poorly, and just how small a part of the race a single person is.

Another thing to take into consideration is the huge volume of a hive that has to be given over to infrastructure. They will all have massive dock yards to accommodate hundreds, if not thousands of ships landing every day just to bring in supplies needed for the hive to function. Then you have the superhighway systems needed to move the goods through out the hive. There will be millions, if not billions, of tractor trailers hauling cargo everywhere, the facilities to store and maintain all those vehicles, and the distribution hubs to redirect the cargo. You get the idea.

A real world example is Wal-Mart. They have at least 84 distribution centers scattered around the U.S. that range from 400,000 square feet to well over 1,000,000. That’s just what one company needs to distribute goods to the 306 million people and around 3,000 stores in the U.S. Translate that to how many hundreds of big box stores there are in operation and then start scaling up for the hundreds of billions in population for the hives.

My view also takes into account the bigness of the 40K tech. I would scale everything up to 5-10 times its normal size. So an air conditioner for a small house for us might be 1 square meter. In 40k that same unit might very well be 5-10 square meters. Now by taking the bigness of 40k into account you can start eating up space pretty quickly.

In Necropolis , Gaunt’s Ghosts #3, they had a full armored division, memory is fuzzy on totals, within Vervunhive. The tanks never left the hive and had a full battlefield of open space to maneuver around and engage the chaos forces.

Another thought is to how much of the hive is uninhabitable due to the fact nobody knows how to fix some environmental system or even where that system may be located in a large section of the hive. If an air purifier went down and nobody could fix it a whole section of the hive might have to be abandoned because the air becomes toxic or too hot for humans to live there, forcing hundreds of thousands to relocate to an already crowded section of the city. Over the centuries habitable sections of the city get smaller and smaller and the merchants and nobility certainly won't let anybody come up to their levels causing ever increasing congestion of people.

Good point, Itsuncertainwho.

Infrastructure takes up a lot of space. Most storage areas are probably off limits to the local populace as well so that space really wouldn't count as habitable space even though it's being used by the population at large.

I still think overall that the 25 billion number was pulled out of the air.

25 billion is definitely on the low side.

Incoming political thought:

We tend to think of the earth as being overrun with human beings who are crowding out every last possible open space and destroy habitats left and right, but the reality is that our 6 billion bodies barely touch a fraction of the available spaces on this planet. And that with 80% or more being completely uninhabitable by human beings.

Can you imagine the population of 40K terra when the seas have all boiled away and it is the center of an Imperium spanning millions of worlds?

Only 38k years to go to see if we get to that point.

I CAN'T WAIT!!!

Step 1: Dark age of Technology

Step 2: Age of Strife

Step 3: ?????? (Emperor?)

Step 4: Profit.

Idaan said:

I just assumed we were looking at only one spire in Ptu, not all of the hive.

And the big factor everyone has to remember about hives. The population is not only 'spread out' but it's going higher then any skyscaper today full of just people working. So say 25 billion...that could be in the realm of possibility. Maybe five billion less or so?

On Terra everything there is mostly Hive cities, some that would count as countries in thier own right today as mentioned. (Especially on a world without oceans) The Guard fields armies in the countless billions almost every year, and that's just a fraction of the population in a sector at any given time. Given casualties births, and the facts that some planets don't even use space for things like agriculture (Agri worlds are for that), and people live work in the same habs...yeah think bigger in populations then our Earth today for even 1/8 the space of land we use today.

There are no laws protecting a planet from exploitation in the Imperium. Some worlds are good, others are corrosive wastelands, others in the middle...But the main thing to remember is that authors take heaps of liberties in explaining backgrounds. (I remember typing about this before though lol) So best you all incorpate what you reckon is reasonable for the Imperium. Who knows, in your game you could even have the said Hive wiped out by some event, making it all null. *evil grin*

GW seems to have a morbid fear of the 'T' word (trillion). At most they talk about billions of poeple. Although 1.7 trillion is probably too high, as the population increases so too does the infrastructure required to keep them alive, more poeple require exponentionally more infrastructure.

LeBlanc13 said:

You mean only 13907896 more sleeps to go! Jay!

aethel said:

Well, if you look at the base, it seems to include the Lucid Palace and the rock walls at ground level. I picture the different spires of Sibellus to rise to various heights out of a rolling hivescape of lower (but still quite high) levels of constructions. The picture clearly is not of such a hive, and only with very generous amounts of goodwill could I see it as "just part of the bigger picture"

After doing some reading about real-world crowded places, I found out about Gunkanjima, the forbidden island just off the coast from Japan. (It was linked to from this thread about a "real world Hive City").

Anyway, this little island had a density of 835 people per hectare for the whole island (1,391 per hectare for the residential district) - one of the highest population densities ever recorded worldwide. A hectare is 0,01 square kilometres, so multiply these figures by 100 to make them comparable to those in my earlier posts.

So that is 10 times the density of Shanghai. Now we're talking Hive level densities in my opinion.

So, pack Sibellus 14 billion people into an area, using this density, and you only use 0,6% of the Hive surface area.

I just do not see 99,4% of the Hive being uninhabited, no matter how many and weighty arguments put forth

Agmar_Strick said:

Exponentially more infrastructure is stretching it. If one person eats 3 pounds of food per day, 2 people would eat six pounds, not nine. They don't eat more just because more people are there.

To feed something like 1.7 Trillion people in a hive, or a hive world, you would need entire planets devoted to food production. In fact, you could call them agricultural worlds...or agriworlds.

If only GW had thought of something like that....

In fact, you could also argue that you wouldn't need nearly as much food production per capita as we enjoy today, as most people east less well in 40K. More than that, they seem to have some ability to manufacture water and basic food out of chemicals, or at the very least recycle these things to a very efficient degree. You'd probably have to talk to the mechanicus about all this, but I don't think you'd be likely to find canned goods and wholesome food on the tables of most hiver habs. You're probably looking at anything from protein blocks with nutrient broth, to corpse starch rations, to the kind of stuff they ate in the Matrix.

The kinds of numbers we're talking about here are easily manageable with the way the infrastructure for the system is set up...I think. Assuming large amounts of mechanical help.

You're right, 25 billion is much much too low. Trillions are much more likely.

The impression I get about the population density arguments is that the hives are pretty much the only populated areas on the entire planet of Scintilla. The rest is incredibly polluted wasteland. Let's assume that there are about a dozen hives on the planet in addition to the major ones mentioned in DH: say 1 billion each. This leaves about 13 billion to be divided up between the three big hives. To me that doesn't seem like TOO low a population, subject to the scale of the hives themselves.

I agree though that the scale of the hives sounds a bit confused in the material produced so far. I also agree with an earlier poster that the spire image of Hive Sibellus in Purge the Unlean seemed a bit out of proportion with the scale of the hive as described in the DH rulebook.

There does seem to be a little bit of confusion about the architectural style of Hive Sibellus too. I read Hive Sibellus in the DH book as being a very different type of Imperial city to the "classic" hive city shown in Necromunda: all this stuff about its very broad scale, how it tumbles over cliffs etc etc. Compelling stuff, and very different to the needle spire shown in Purge the Unclean.

The Impression I got of Sibellus is that it was meant to be a bit like Mexico City: a huge sprawling mess covering thousands of square kilometres. But the GW art style crept in, and suddenly it has a spire.

It's a shame, because logically all cities are going to be different and have a different look. Stalinvast in the Inquisitor novels is meant to look a bit like a vast coral reef, Malfi is supposed to be "gloomy" and "subtropical" - I imagined it being a bit like Mumbai...

Anyway, I'm wandering off topic here, sorry!

Oh arig-worlds! never thought of that! /sarcasm.

seriously though, the increase in infrastrcuture required might not quite be exponential, but it would probably be close. Even though a lot of food production is moved off world, you still need to transport, store and process all that food. Which is huge. not to mention other resources like power, water, clothing, tools, tables and chairs, kitchen applicances, cleaning supplies, etc. Your average hive worlder is not going to use as many resoruces as your average westerner, but they still need to drink water, clean their clothing and have something to sit on and eat their food with.

Where the massive increase in infrastruce comes in is not that people eat more food, but that the logisitcs of moving such vast quanitities of material becomes increasingly complex.

Take two logical extremes as an example.

If you have 10 apples and want to distribute them to your 10 friends whoare standing right next you, you just hand them each an apple. Maybe you need a bag to hold the 10 apples.

If you have 300 million apples and want to distribute them to them to every person in the USA, and you're in singapore. You need a place to store them in singapore dock space in singapore to load them onto ships sufficent shipping to get them to the US before they rot, docks at the US to receive the ships, information on where in the US the ships should go (provided by population distribution information, which also needs to be gathered) warehousing at each of the docks to store the apples while a sufficent number of trucks pick up enough apples to deliver to each city (and they need to know know many apples to take to each location). Once in the city, you need more wharehousing, another set of distribution capable of delivering to each home. Which also need to know how many apples to deliver to each house. whew!

now try that with delivering 2550 teragrams of food (per day, assuming 1.5 kilos of food) from half an dozen planet each a dozen light years away to 1.7 trillion people. The logisitcs of it would be mindblowing. lets not even consider waste management...

edit:

doing some calculations shows that, if you imported that much food every day, and didn't export any waste (yay! garbage world!), after 5,000 years you would add the weight of earth's atmosphere to Sibellus.

Glad you laughed at the agri-world thing. Didn't realize till a while ago that it might come off as a jerk thing to say.

Anyway:

--now try that with delivering 2550 teragrams of food (per day, assuming 1.5 kilos of food) from half an dozen planet each a dozen light years away to 1.7 trillion people. The logisitcs of it would be mindblowing. lets not even consider waste management...--

Kind of gives you a new-found respect for the administratum...or munitorum...or whomever handles that kind of thing.

Your last comment is interesting, and would present a problem. I think, though, you could reason it away by supposing that the hive has a very efficient recycling/waste management system. And that the underhive is VERY dirty. Depending on the efficiency of any recycling facilities on the planet it may even alleviate some of the strain on importation of biomass or at the very least, water.

The mind-boggling scale of the Imperiums activities is why I feel Marines need to be mind-bogglingly uber - how else can they deserve their reputation in a civilisation as vast as the Imperium?

I'm with you Dezmond, Marines need to be crazy hard for a thousand troops to have any impact on a planet with a pop of 25 billion, let alone the more likley 1.7 trillion.

I figure most hive worlds are knee deep in crap, just dump it 'in the wilderness'. You would probably have entire mountain ranges of garbage and quite likley unique eco-systems and indeed civilisations living in the garbage dumps of hive worlds. Then you could have mining operations in the garbage, strange materials formed from 2,000 year old hamburgers and tin cans

Also for very old worlds, the amount of material being piled up is getting to the area where it could start affecting their orbit, which is crazy. Malfi is supposed to be more heavily populated and Sibellus, and is described as being almost like old Segmentum Solar worlds with trans-continental hives and such. Logically then, if Sibellus is not particuarly heavily populated for a hive world, how many people must there be on those old segmentum solar worlds?