Fun With: SciFi Militaries

[rhoenix]

Yes, the Fun With... threads are back - for better, or for worse.

Given a setting, technological and developmental level, and a larger civilization in, for the same of argument, the Star Wars universe (in a vacuum, in this case - let's not consider other civilizations' influence just yet), let's design them a military for both defensive and offensive operations.

1. Were you to design a structured military for a civilization large enough to support it, how would you separate the "branches" of the military? This would include planetary occupation, planetary assault, space navy operations (patrol, fleet tactics, etc.)

2. How would you design the different ship classes for the developing space navy? Would you design them according to the purposes for which you'll need a navy and let them evolve from there, or would you go a different way?

I do have additional questions, but they depend entirely on what sorts of answers I get. Thank you in advance for your attention and your thoughts.

[Ender]

how hard scifi are we talking here?

[Ford Prefect]

Given that we're using Star Wars as a 'baseline', I would probably guess 'like jelly'.

[Ender]

Given that we're using Star Wars as a 'baseline', I would probably guess 'like jelly'.

Yeah, but beynd just tech defining your options, there is tech defining the terrains. If high acceleration starships are plentiful to the common man, almost no one will live on planets. This means you need a much smaller force of ground troops, and different equipment for them (hard to use artillery on a space station)

[Darth Raptor]

I think the point of the exercise is to create a credible military out of the technology/resources of an established sci-fi setting. So taking, for example, the United Federation of Planets, you could use their established capabilities to create a Starfleet that would look very different from the canon version; i.e., actual warships crewed by mass-produced Data knockoffs ala Starcrossed, etc.

[Pulp Hero]

Working with Star Wars like tech and sci-fi "hardness" I would have the military split into and Army and Navy.

The Navy would control all the capital ships, logistics, the majority of intel gathering (along with a non-military CIA analogy), and corps of Marines used for orbital drops/boarding actions (however the size would be small to warrant a separate Marine branch.)

The Army would be used for planetary fighting, have control of Orbit-to-Atmospheric fighters and close air support ships, and be in charge of arranging all surface based planetary defenses (to include things like missiles and cannons capable of hitting enemy ships in orbit.)

[rhoenix]

Yeah, but beynd just tech defining your options, there is tech defining the terrains. If high acceleration starships are plentiful to the common man, almost no one will live on planets. This means you need a much smaller force of ground troops, and different equipment for them (hard to use artillery on a space station)

This is a very interesting point. Would only the more affluent people live on planets, or would doing so under these conditions dictate other reasons?

Working with Star Wars like tech and sci-fi "hardness" I would have the military split into and Army and Navy.

The Navy would control all the capital ships, logistics, the majority of intel gathering (along with a non-military CIA analogy), and corps of Marines used for orbital drops/boarding actions (however the size would be small to warrant a separate Marine branch.)

The Army would be used for planetary fighting, have control of Orbit-to-Atmospheric fighters and close air support ships, and be in charge of arranging all surface based planetary defenses (to include things like missiles and cannons capable of hitting enemy ships in orbit.)

This sounds sensible. I posted this on another forum, and the issue of the Marines was raised. In other threads in this forum, I saw that in most navies, the Marines are simply another part of the greater Navy, and not a separate branch - only the US and the UK have separate branch for Marines.

Given this scenario, and given also that the Navy will by nature need a fast-response expeditionary force, would you say that those Marines would be better served by having their own branch, or not?

Additionally, how would the issue of military intelligence be resolved? Should there be a separate branch for Intelligence work, or should each branch have their own section?

[Sea Skimmer]

Given that we're using Star Wars as a 'baseline', I would probably guess 'like jelly'.

Yeah, but beynd just tech defining your options, there is tech defining the terrains. If high acceleration starships are plentiful to the common man, almost no one will live on planets. This means you need a much smaller force of ground troops, and different equipment for them (hard to use artillery on a space station)

I don’t know about that, planets will always have a strong appeal because that way if you get a leak in the window you don’t die of decompression. Sure a planet with say 100 billion people on it might need artificially sustained atmosphere too… but at least it doesn’t leak away. Also giant habitat space stations are likely to run into all sorts of social problems stemming from having so many people in such confine space. If you have full fledged Star Wars technology you don’t really gain much advantage from living on a space station either, because orbit can as you pointed out already be reached so easily.

[Pulp Hero]

[quote="

This sounds sensible. I posted this on another forum, and the issue of the Marines was raised. In other threads in this forum, I saw that in most navies, the Marines are simply another part of the greater Navy, and not a separate branch - only the US and the UK have separate branch for Marines.

Given this scenario, and given also that the Navy will by nature need a fast-response expeditionary force, would you say that those Marines would be better served by having their own branch, or not?

Additionally, how would the issue of military intelligence be resolved? Should there be a separate branch for Intelligence work, or should each branch have their own section?[/quote]

I picture the Marines as dealing with two things:

1) Boarding actions on ships.

2) Assaulting planets to establish the initial beachheads.

In both cases they are directly supporting Naval vessels and only engaging in combat for very short amounts of time. Also their operations will rely a lot on Navy support. Therefore I don't think they warrant or would benefit from being a separate Branch.

***

I don't think the Army would be able to use an Intel branch as well as the Navy, who would have FTL capabilities as well as orbital gadgets.

I think a seperate Intel Agency, either civilian or military that had its own FTL capability and command would be a good idea for in-depth operations, planetary operations, or other "black" stuff.

[Nyrath]

I don’t know about that, planets will always have a strong appeal because that way if you get a leak in the window you don’t die of decompression.

As Destructionator pointed out, this is not much of a problem on space habitats. However, if your technology level suddenly declines due to a civil war or something, planets do have advantages over space habitats.

Joan Vinge pointed out an unexpected consequence of the collapse of technology in her THE OUTCASTS OF HEAVEN'S BELT. If a planetary colony falls into barbarism, everybody reverts to a non-technological agrarian society. If an asteroid civilization falls into barbarism, everybody dies.

It takes lots of technology to run the oxygen system, airlocks, spaceships, hydroponics, nuclear reactors, and other items vital for life in space. No technology, no life. In other words, they are a Hydraulic state.

[Teleros]

1. Were you to design a structured military for a civilization large enough to support it, how would you separate the "branches" of the military? This would include planetary occupation, planetary assault, space navy operations (patrol, fleet tactics, etc.)

1. I'd have a much larger navy than army. Unless planet-based forces have some tremendous advantage over ships (how?), once you've achieved space superiority you'll be able to turn ground forces into large smoking craters at will - thus, the army units on hand only need to be sufficient to mop up what remains of the resistance & keep order.

2. I'd separate the Army, Navy, Marines and intelligence agency (although the "Army" would consist of air, land and sea forces).
2a. The Army would primarily be involved in peacekeeping and wiping out what resistance remains on a planet that the Navy can't / mustn't wipe out from orbit (eg if you mustn't nuke cities or somesuch).
2b. The Navy would do the bulk of the work, as already intimated.
2c. The Marines would do jobs much like Pulp Hero's idea.
2d. The intelligence agency would, by being independent, hopefully not become too focused on any one arm of the armed forces.

3. Fleet / ship tactics depend entirely on how the ships function. If they're like the heavily-protected, inertialess Lensman ships, then acting in concert will be necessary in order to avoid a stalemate. In addition, shields and the like can make smaller ships practically useless against larger ones, forcing small ships to either aid larger ones, team up or get the hell out of the fight.

4. As Ender said, where people live also determines tactics, equipment and such: there will be different responses depending on whether people live on planets, Culture orbitals, Dyson spheres or Babylon 5-esque space stations.

2. How would you design the different ship classes for the developing space navy? Would you design them according to the purposes for which you'll need a navy and let them evolve from there, or would you go a different way?

I'd try to design them to do a specific job, then change as needed. Depending on how the universe functions though, you can probably divide up all the ship classes into one of six (very) broad categories:

1. Scouts
2. Security ships (anti-piracy, convoys, patrols etc)
3. Dedicated warships (either for one-on-one or fleet engagements, includes carriers if it makes sense to have them)
4. Siege ships
5. Command ships
6. Transport & logistics ships

How these work in practice depends a lot on what the universe is like. Starfleet seems to combine all categories quite a lot, whilst the Lensmen combine 2 & 3, and fleet engagements are usually decided by super-dreadnought class vessels rather than cruisers or heavier ships.

Yeah, but beynd just tech defining your options, there is tech defining the terrains. If high acceleration starships are plentiful to the common man, almost no one will live on planets. This means you need a much smaller force of ground troops, and different equipment for them (hard to use artillery on a space station)

1. Planets may be cheaper however, and especially for a race or civilisation starting to expand into space via FTL, it will be much easier to establish colonies on planets than in space (especially if their starships aren't designed for extended operations). This would certainly apply to the Federation and probably the early Star Wars universe, but I'd have expected more space habitats by the time of TPM.

2. If you're allowing for shields and the like, then planets can also mount considerably larger ones than most stations could, simply because there's a lot more space to build them and the accompanying infrastructure. In space you'll have station-keeping thrusters, mass, power requirements, moving parts (eg B5's central living section) and all that to consider.

3. For the same reasons, planets can mount more and heavier weaponry - and unless your space stations have equivalent spare manufacturing capabilities, a planet can probably put up more orbital weapon platforms and the like too.

4. Finally, even if a colony ship can survive as an orbital habitat, the people on it may simply prefer to live on a planet.

Nor does this happen in space habitats. Punching a hole is much easier said than done, and even if one does occur, if it is a square meter hole, it will take several months for enough air to escape before it starts to give people trouble. Plenty of time to patch it up.

It would however be easier done on a space station than on a planet, which is all you need for people to have safety concerns and choose to live on a planet. I mean, what if the kids open the airlock? Whoever said we were dealing with knowledgeable, rational people in this?

Is this really that much different than real life?

Yes, although I think that we need a new phrase instead of "hydraulic state" (perhaps an "extreme form" of one or something?). The point is, on Earth people would survive and could eventually rebuild. On an orbital colony (and assuming no outside help), they'd all die.

[Illuminatus Primus]

I don’t know about that, planets will always have a strong appeal because that way if you get a leak in the window you don’t die of decompression.

As Destructionator pointed out, this is not much of a problem on space habitats. However, if your technology level suddenly declines due to a civil war or something, planets do have advantages over space habitats.

Joan Vinge pointed out an unexpected consequence of the collapse of technology in her THE OUTCASTS OF HEAVEN'S BELT. If a planetary colony falls into barbarism, everybody reverts to a non-technological agrarian society. If an asteroid civilization falls into barbarism, everybody dies.

It takes lots of technology to run the oxygen system, airlocks, spaceships, hydroponics, nuclear reactors, and other items vital for life in space. No technology, no life. In other words, they are a Hydraulic state.

So, like in The Humanist Inheritance, all permanent space colonies should be autocracies due to the fact they are hydraulic states?

[Timotheus]

I don’t know about that, planets will always have a strong appeal because that way if you get a leak in the window you don’t die of decompression.

Nor does this happen in space habitats. Punching a hole is much easier said than done, and even if one does occur, if it is a square meter hole, it will take several months for enough air to escape before it starts to give people trouble. Plenty of time to patch it up.

Really? Spend much time on space habitats?

[Junghalli]

So, like in The Humanist Inheritance, all permanent space colonies should be autocracies due to the fact they are hydraulic states?

Personally I wouldn't think so, at least not all of them. As has already been pointed out, modern First World nations are very much hydraulic states. If the infrastructure fails most people would be very, very borked. Just imagine what would happen to places like New York or Las Vegas if essential services were cut off. But there are a lot of non-autocratic First World countries.

[Nyrath]

Punching a hole is much easier said than done, and even if one does occur, if it is a square meter hole, it will take several months for enough air to escape before it starts to give people trouble. Plenty of time to patch it up.

Really? Spend much time on space habitats?

dm/dt = A * sqrt( 2 * P * rho )
where
dm/dt = the rate (mass per unit time) at which air leaks into vacuum
A = Area of the hole it is leaking through
P = Pressure inside the habitat far from the hole
rho = density inside the habitat far from the hole

I may have made a silly mistake, but the back of my envelope says that if you have a standard cylindrical O'Neil "Island 3" colony with a radius of 3 kilometers and a height of 20 kilometers, with Earth normal pressure, and a hole opened up that was about nine square meters in area (approximately the size of a barn door), it would take about 7.7 years for the atmospheric pressure to drop to one-half Earth normal pressure.

Again, somebody should check my math, but I'm sure I'm in the general ballpark.

[Commander 598]

Most of the holes that got poked in UC Gundam's colonies appeared roughly that big most of the time...and they supposedly had a diameter of 10km and a length of 30 to 50 or so km...I think.

[Sea Skimmer]

Nor does this happen in space habitats. Punching a hole is much easier said than done, and even if one does occur, if it is a square meter hole, it will take several months for enough air to escape before it starts to give people trouble. Plenty of time to patch it up.

A plane can decompress in about 1 second flat and its not even being exposed to hard vacuum, a huge number of people would easily die from even a very small leak. Its going to decompress everything inside of the surrounding and hopefully air tight bulkheads before anyone can react. Anyone in that space is dead unless the leak is sealed and the area is depressurized in less then 2 minutes. Never mind the threat of things like solar flares or major a

Space is huge and materials are plentiful.

So what, the earth is huge with plentiful materials too, that doesn’t mean building stuff is free. Building stuff in space cannot help but be more expensive then building on a planetary surface. You need way more complex systems to provide life support and safety backups and its just going to be inherently harder to do work.

It isn't hard to build more real estate and connect it to your existing stuff if what you have already starts to run out, so there is no good reason why they would be confined.

Right so that’s why everyone on earth already lives on a 6000 square foot apartment right? And huge apartment block projects in US inner cities worked out so damn well? Because all we need is space and materials? Give me a break, the idea that the future of mankind is everyone living in giant space habitats is no more realistic then the 1930s projections that the future of life on earth would be nothing but mega cities and massive skyscrapers in which it would be an honor to live. The reality is the same as what really happened since, then, some of these big habitats will be built just like we kept building some skyscrapers, but for the average joe housing is going to remain much the same as it always did.

[Firethorn]

This sounds sensible. I posted this on another forum, and the issue of the Marines was raised. In other threads in this forum, I saw that in most navies, the Marines are simply another part of the greater Navy, and not a separate branch - only the US and the UK have separate branch for Marines.

And even for the US, the Marines are technically a part of the Navy, they just have their own recruiting section. It's part of the mythos of being a Marine.

This way, If you join the Navy you don't really have to worry about being part of a beach assault.

A plane can decompress in about 1 second flat and its not even being exposed to hard vacuum, a huge number of people would easily die from even a very small leak.

Here's a better statement. Cases where a plane depressurizes quickly involve things like doors coming off, holes larger than a window being torn from the plane, etc... Basically, a hole much larger than the 1 meter square given in the example.

No matter what the movies show, bullet holes aren't going to be able to overwhelm the plane's pressurization system, well, at least not until the plane starts looking like swiss cheese.

Now scale it up a 1000x or more. We're talking about a Scifi habitation station. Odds are it's a lot bigger than a plane or a bus.

Its going to decompress everything inside of the surrounding and hopefully air tight bulkheads before anyone can react.

Nope. If the station is built with safety equipment, there should be emergency breathers and patches, and as the pressure gets down to 'high mountain' levels the loss will slow dramatically, reducing any wind. They patch the hole, then the area can be repressurized.

Anyone in that space is dead unless the leak is sealed and the area is depressurized in less then 2 minutes.

This is something that's pretty much impossible to estimate unless you know: The size of the hole, the pressure and volume of the interior before the breech. For unconsciousness, the oxygen level of the atmosphere would be nice to know as well.

[Saxtonite]

Because all we need is space and materials? Give me a break, the idea that the future of mankind is everyone living in giant space habitats is no more realistic then the 1930s projections that the future of life on earth would be nothing but mega cities and massive skyscrapers in which it would be an honor to live.

Isn't that coming true arguably to a certain extent (the increasing amount of people moving to urban areas throuought the world and increasing oil prices giving more incentive for people to move closer to the city core, etc?)

[Sea Skimmer]

Isn't that coming true arguably to a certain extent (the increasing amount of people moving to urban areas throuought the world and increasing oil prices giving more incentive for people to move closer to the city core, etc?)

Its true more people are living in urban areas, but they usually aren’t hyper dense like skyscrapers or even just 10 story tall ‘projects’ apartment buildings would be. Many of those urban areas also happen to be some of the worst places to live on earth with horribly inadequate services. We wont be running out of land on earth for devolopments anytime soon either, rule of thumb is we can fit 6 billion people into Texas alone at mere New York City level density.

[Ford Prefect]

Give me a break, the idea that the future of mankind is everyone living in giant space habitats is no more realistic then the 1930s projections that the future of life on earth would be nothing but mega cities and massive skyscrapers in which it would be an honor to live.

If human beings start living off the surface of the Earth, exactly where do you think people are going to live? No celestial body in this soalr system is particularly more suitable to live on compared to a habitat like an O'neill Cylinder, which is essentially able to replicate everything the earth has, albeit it on a much smaller scale. The point becomes moot if you can just zip over to Deneb V, as the OP would suggest, and stumble across a planet which supports your species (on a galactic scale, the prevalence of a world more or less like earth is going to be fairly significant).

However, if you really are stuck in one system, and you do start living off the surface of your home world, you have the choice of inhospitable rocks or you can build a habitat which has the same atmospheric mix and the illusion of the same surface gravity as your home planet.

[Sikon]

Give me a break, the idea that the future of mankind is everyone living in giant space habitats is no more realistic then the 1930s projections that the future of life on earth would be nothing but mega cities and massive skyscrapers in which it would be an honor to live.

The primary basic part of a space habitat is a large metal shell. Once that's created, filled with air, and rotating for artificial gravity, the construction environment for interior furnishing inside is relatively similar to that on earth.

What stands in the way of an advanced space civilization making large metal shells affordably? Materials? Energy? Labor? Consider them one by one.

It's not particularly materials, as spacestations could be made right by a convenient source, using the metal of a nickel-iron asteriod which is almost like a giant block of premade stainless steel ready to be melted or vapor deposited.

Energy? On earth, the multiple order-of-magnitude cost difference between a $100000 house of 1000-ft^2 area and a ~ $1000 giant tent of 1000 ft^2 area is in part due to the difference in sturdiness. Although current solar cells cost on the order of $500 per square meter, a flimsy sheet of aluminum foil can reflect sunlight for nominally as little as under $1 per square meter. Such flimsy reflectors aren't a workable method on earth, but, in the practically perfectly undisturbed environment of space, cheap and flimsy giant sail-like solar reflectors can survive.

Quite literally, on the order of 200 terawatts of concentrated solar power could be obtained with the first million tons of such reflectors alone. For perspective, today's world electricity generation is 2 terawatts.

Labor? Aside from possibilities such as thermal spraying, one manufacturing technique is to use vapor deposition. Such is impractical for large-scale usage on earth where only small expensive chambers of sufficiently high quality vacuum can be built, but the ambient vacuum and zero-g of space is where it shines.

Imagine making a large metal shell not by manual labor of many thousands of laborers welding together little pieces but by starting with a thin form (analogous to a giant balloon in cheapness although not technically such). Onto the interior area, a tiny thickness of metal would deposit per minute but with that adding up as such ran for hundreds of thousands of minutes in a year.

Such a manufacturing method can require few personnel, as part of the NASA 1975 giant spacestation study described:

In physical vapor deposition of metals, most alloy systems show a fall density, fine grained microstructure at a substrate temperature 0.3 times the melting point of the metal (ref. 32). As substrate temperature is increased, the grains become coarser, the yield strength decreases, and ductility increases. Because these properties correspond to those of rolled and annealed sheet, vapor deposited metals have been termed "a true engineering material (ref. 33). [...]

The equipment used in vacuum vapor fabrication can be very lightweight. It handles sunlight, thermal radiation, rarefied vapor, and an aluminum feed rod; forces on it are virtually nonexistent. The greatest mass in the system appears to be the solar furnace mirror area, which is directly proportional to energy consumption. This consumption is, in turn, driven by the efficiency of energy use (thermal radiation to heat of vaporization), efficiency of vapor use (aluminum vaporized to aluminum reaching substrate), and by the total quantity of aluminum deposited.

Ignoring efficiency factors, for a heat of vaporization of l.l X 10^4 J/g, a colony mass of 300 kt, a solar constant of 1.4 kW/m^2, and a fabrication time of I yr, the ideal mirror area is 7.4 X 10^4 m^2. An average flux deviation from perpendicular of 20 degrees probably represents adequate collimation; with proper evaporator design the inefficiency of vapor use should be less than 2.5 (unused vapor is condensed and recycled); even a poor energy efficiency should keep the total inefficiency below a factor of 10. Allowing a full factor of 10, the mirror area is 7.4 X 10^5 m^2 . At 100 g/m^2, this is 0.74 kt.

The remainder of the system includes refractory metal foil boxes for the actual solar furnace evaporation units, plastic film hoods to intercept scattered metal atoms, and a carefully made balloon in the shape of the desired structure. Including these masses, the total system is very likely less than 1.5 kt; if the fabrication time were extended over several years this mass would be less.

Because colony structures have rotational symmetry, the solar furnace evaporation units can cover different areas as the colony rotates beneath their beams. With proper arrangernent, complex shapes and structures can be created, and the direct human labor required for fabrication is very small. [...]

From here

The reality is the same as what really happened since, then, some of these big habitats will be built just like we kept building some skyscrapers, but for the average joe housing is going to remain much the same as it always did.

The natural tendency of most people is to sometimes overestimate change in the near-term but underestimate it in the long-term. The Roman shipbuilders of a couple thousand years ago would surely not have guessed that the world would go from having a few thousand tons of ships (like hundreds or so of ~ 75-ton Quinqueremes, etc.) to having more than 800 million tons total world merchant marine today, an increase of literally at least tens of thousands of times.

With the length of time that structures can last in space compared to earth, a situation where eventually more people lived in space than terrestrially could occur even if the number of space habitats was built up gradually by each century adding some more while still using the giant metal shells of the past century's habitats. Analogously, some 150-year-old cast iron pipes are still used today in places where corrosion has not been bad.

With that said, growth might not be that gradual anyway. For example, that NASA study also estimated that:

12 percent of the maximum population of one such sphere, working for 3 yr could duplicate the habitat. Automation is much better suited to the large scale, repetitious production operations needed for the habitat shell than to the details of interior architecture and landscape design. It seems quite likely, therefore, that the construction of new habitats will become an activity for specialists who supply closed shells, ready for interior finishing, to groups of prospective colonists.

Really, there's vastly more likelihood of the preceding than there is in getting to imagined habitable planets through FTL. Space habitats would be necessary for a number of goals regardless of cost. Besides, nothing fundamentally prevents an advanced space civilization from potentially producing such for less labor per occupant than a $200000 subdivision house today that may cost its owner the equivalent of a half-dozen years of wages.

[Ender]

So, like in The Humanist Inheritance, all permanent space colonies should be autocracies due to the fact they are hydraulic states?

That's quite a leap in logic you made there. He just said that space colonies were hydraulic states, which is true. How you went from that to accusing him of advocating autocracy is beyond me.

One can reasonably assume that a space colony, while it may or may not be autocratic (just as any country may or may not be autocratic) will invoke many trends of the panticopia or the nanny state. How much these policies will intrude on the life of the citizens will depend on their implementation. Really we can't say much at all about what system of government will be used. I do think a safe assumption is that as a culture, space stations will host a population that has precious little tolerance for those who think it is better to hang separately then to hang together.

Really? Spend much time on space habitats?

Do you take pride in being ignorant or something?

A plane can decompress in about 1 second flat and its not even being exposed to hard vacuum, a huge number of people would easily die from even a very small leak. Its going to decompress everything inside of the surrounding and hopefully air tight bulkheads before anyone can react. Anyone in that space is dead unless the leak is sealed and the area is depressurized in less then 2 minutes.

So despite the fact the equations were helpfully provided 9 hours ago, you decide to run with a no math fallacy rather than consider that things might go differently then you insist they will.

Never mind the threat of things like solar flares or major a

Yeah, we have this stuff called water that you need plenty of to support life. Makes pretty good shielding. Never mind using metals or rock.

So what, the earth is huge with plentiful materials too, that doesn’t mean building stuff is free. Building stuff in space cannot help but be more expensive then building on a planetary surface. You need way more complex systems to provide life support and safety backups and its just going to be inherently harder to do work.

Are you seriously contending that it will be harder to work in free fall, given the proper equipment, than it is to build a skyscraper (where you still need dedicated equipment)?

Right so that’s why everyone on earth already lives on a 6000 square foot apartment right? And huge apartment block projects in US inner cities worked out so damn well? Because all we need is space and materials? Give me a break, the idea that the future of mankind is everyone living in giant space habitats is no more realistic then the 1930s projections that the future of life on earth would be nothing but mega cities and massive skyscrapers in which it would be an honor to live. The reality is the same as what really happened since, then, some of these big habitats will be built just like we kept building some skyscrapers, but for the average joe housing is going to remain much the same as it always did.

Our population is currently expanding at a rate of 0.3% a year. Estimates I've seen peg the earth at being able to support 10^10 of us with its resources. Where are all the people going to live if the Earth can't provide for them? And if you are going to seriously contend that it is more realistic that people will voluntarily restrict the population growth rather then implement technology we've had since the 70's to expand towards space, let me start laughing in your face now.

Speaking of threats of living somewhere, let me quote part of a message I just got in the yahoo sfconsim-l mailing list:

How do I join this group?

[Commander 598]

I think you should keep in mind that birth/death rates aren't exactly the same across the globe and that if population growth is stabilized it won't make the general effects of overpopulation on the Earth any lighter. Resources are still going to be gobbled up at an unhealthy rate and we're already having issues with deforestation and pollution.

[Junghalli]

It's worth noting that global carrying capacity is very much a function of technology. Pre-modern technology could probably never have supported our current population. Likewise new technology may permit more people to be supported more sustainably in the future. A relatively cheap and clean energy source which isn't likely to run out anytime soon (like mature fusion) would go a long way to making human civilization more sustainable. Advancing technology could permit resources to be exploited that weren't economical to exploit before, and allow more people to be fed with less land. These are exactly the trends that led to the relative prosperity of modern First World civilization, and I doubt we've reached the end of the road with them yet.

My own feeling is that by the time we have the technology to send millions of people out into space we'll probably also have the technology to sustainably support a population of ten billion. Indeed, it's worth noting that the same technologies and techniques that allow you to support huge populations in space could probably be applied to supporting large numbers of people on Earth. Keeping lots of people alive in a space habitat is a matter of making highly efficient use of a relatively limited amount of land and biomass, after all.