How Close We Are to Colonize Galaxy…
January 10, 2010 16 Comments
Whether a planet of 10 million people – the equivalent of a single large urban region — could realistically have a diversified enough economy to maintain and operate a fleet of starships seems a bit iffy, unless they are putting a massive effort into it, so massive that it may stunt their other prospects.
The most likely scenario for a world of 10 million people sending out a colony might be that they’ve decided their current home sux, and they’re going to try their shot at another one.
Looking at the other end, how many people for a viable colony. I’d say 10,000 at the low end, with 100,000 seeming a lot more comfortable. That’s the population of one semirural county. How many machine shops and such does it have, how much can they specialize for efficiency, and oh yeah, you need raw material, a mining sector and all that.
If you can’t make it you have to import it, paying starship freight instead of truck freight, and what have you got for sale? The market for colony-world curios is going to get crowded fast, and if you really do have something to sell, you’ll probably need more than a one-county economy to produce it in commercial quantities.
So I would say that you usually have to put 100,000 people onto a colony planet for it to thrive. Colonies with fewer than that can hang on, but if subsidies are cut off they may die off outright, or be stuck in a marginal existence; only lucky ones will overcome it and do okay.
For a colony to really go as a largely self-sufficient post industrial world it had better have on order of a million people — more or less the equivalent of Bakersfield and environs. I am certain that Australia has a Bakersfield, but I do not know what it is. Maybe our Oz contingent can inform us.
But once again, if they can’t make it or pay starship freight for it they do without it, and the equivalent of Bakersfield has a tough challenge producing nearly all the needs of post industrial civilization. And for exports it is good to have one sizeable airport that can double as the shuttle port and provide steady employment for a lot of the techs.
so hold your pitchforks. This is predicated on the 23rd century, or 28th or whatever, having about the same productive efficiencies of scale that we are used to. If you have got replicators where you shovel dirt in one end and get a washing machine or air car out the other, things are different. But you still need a wide range of human skills, very hard for small communities to provide, maintain, and keep active.
So maybe my figures could all be squeezed down by an order of magnitude, so that a colony of 10,000 is fairly viable, a colony of 100,000 can maintain a full industrial base, and one of a million people can keep its own starships in service. That helps for story settings, but you wouldn’t generally expect worlds like that to be active colonizers.
Finally, and most central to time scale, how fast do colony populations grow, either from immigration or birth rate? I would call a million emigrants from Earth each year a benchmark figure for large scale colonization. That’s several thousand people each day, one huge ship or several merely big ones, and it still takes a century of sustained effort to plant 100 colonies, each of a million people.
|From the colony’s point of view, people are another expensive import, if you have to pay them to come. If they can afford a ticket and house stake they will only go to desirable colonies. If someone is paying to ship people to you, you may want to know why, because colonies could be a good place to dump dissidents, minor troublemakers, and similar riffraff.
On the export side, I’m more dubious of shipping off refugees, because by definition you’re dealing with lots of them, and shipping them all off world is horribly expensive. Much more so than just plucking the town crank and town pickpocket off the streets and getting them to volunteer for emigration.
But by and large you expect that mass colonization involves people who weren’t doing so great on Earth, because the supply of nut enthusiasts like people on this board who would actually like to colonize is limited, and a million people a year is a lot.
The other side of colonial growth is reproductive growth. Doubling the population each generation is about the historical sustained maximum. That corresponds to 10x per century, soDeseret World might go from 100,000 people to 10 million people in 200 years.
But even doubling per century is a pretty robust population growth rate. That’s roughly 1.2x per generation. Unless you’re growing ’em in vats, about half the women are having three or four kids, and one way or another the society encourages and accommodates itself to this.
It’s no given that post industrial societies will generally have this population growth rate, though colony worlds may not follow the current trend in industrialized societies toward ZPG or even less.
If colony populations do tend to grow, I suspect the driving force is not the Heinleinian trope of ranchers with half a dozen marriageable — and “husband-high” — daughters, but the pervasive shortage of skilled specialists of all sorts. How this is transmitted to social attitudes I’m not sure, and no doubt can vary widely.
A colony with population doubling each century will go from 100,000 people to 10 million people in about 700 years, pushing us into the second half of the millennium.
Looking at it broadly, say that the age of colonization is around 2250-2350. That is a fairly common time frame for interstellar SF with a geocentric setting; (Star) Trek is vaguely in this era, AD2300 of course, and it’s implied by some of Heinlein’s interstellar stories.
After a century or so colonization from Earth sputters out, because all the low-hanging fruit has been plucked, and it is increasingly costly to reach virgin planets.
Emigration from Earth to the existing colonies can continue after that, but at some point the rate will likely fall. Successful colonies will no longer want people dumped on them, unsuccessful colonies can’t absorb them, so emigration falls to the level of people who can pay to go and want to go, or who the colonies are willing to pay for.
So. At some point around 2400, colonization has tapered off and emigration is tapering off. We can guess that there are at least a dozen or so full colony planets – if you can reach any you can probably reach about that many (and you need a good handful for a decent scenario).
The upward limit is about 100 or so true colony worlds, set – regardless of how many worlds are in reach of your FTL – by the postulated size of the colonization wave. A hundred million people, a hundred worlds – an average of about a million immigrants per colony, though the distribution may well be oligarchic by a power law, a handful of colonies getting a large share of total immigrants, growing to populations of up to a few tens of millions, while most have less than a million and kind of struggle along.
Beyond and between the colonies there may be planets never made into self-sustaining colonies, but remaining as outposts, and likely with some permanent populations. If someone pulls the plug on these, though, don’t miss the last bus out. Same with space stations and such.
As with the chronology, I think this is a fairly classical scale for a mid-interstellar setting — when there are already established colony worlds, that you can get to by starliner, not just outpost transport or even colonization ship.
There are enough worlds for a diverse interstellar setting, but few enough that people who deal with space, at least, will have some notion of them all as distinct places. (The way “Spain” conveys something to you, or “New Delhi,” but “Florianópolis” probably does not.
A few of these colonies already in 2400 have upwards of 10 million people and some potential to colonize themselves, but these were the immigration magnets, so they probably still feel short-handed if anything, not inclined to send lots of people off.
It will take 200 or 300 years for smaller colonies with rapid population growth rates to start pushing up into the 10 million population range, and might have the impulse and capability to colonize. But it might take closer to 500 years for a substantial number of the original colonies to have much motivation to colonize.
The early goers, though, will have filled in the next layer of easy pickings. Here is where your FTL really matters – whether you can light off freely into the vastness to hunt for a suitable planet, or are constrained by a colonization sphere that is starting to grow again.
But broadly speaking, it seems that secondary colonization couldn’t be expected in any serious way until sometime well after 2500, and perhaps not in a big way till sometime around 2700-3000.
An interstellar domain can have no definite borders; stars are scattered too thinly, their types too intermingled. And there are too many of them. In very crude approximation, the Terrestrial Empire was a sphere of some 400 light-years diameter, centered on Sol, and contained an estimated four million stars. But of these less than half had even been visited. A bare 100,000 were directly concerned with the Imperium, a few multiples of that number might have some shadowy contact and owe a theoretical allegiance.
Consider a single planet; realize that it is a world, as big and varied and strange as this Terra ever was, with as many conflicting elements of race and language and culture among its natives; estimate how much government even one planet requires, and see how quickly a reign over many becomes impossibly huge.
Then consider, too, how small a percentage of stars are of any use to a given species (too hot, too cold, too turbulent, too many companions) and, of those, how few will have even one planet where that species is reasonably safe. The Empire becomes tenuous indeed.
And its inconceivable extent is still the merest speck in one outlying part of one spiral arm of one galaxy; among a hundred billion or more great suns, those known to any single world are the barest, tiniest handful.