Charlie Stross takes a hard look at the realism of space colonization, absent multiple technological magic wands. Without them, a lot of the traditional models to justify space colonization don’t make sense. Lunar wheat farming for export? Get real. L5 cities building solar powersats? Probably vastly cheaper to put up some cramped construction shacks and pay the workers enough to put up with conditions no more comfortable than a North Sea oil rig. Mars as a new Oklahoma? How do you close the business case? If you just want living room it’s a lot easier to garden the Gobi Desert.
Here’s one that might work: mining helium 3 from Jupiter or Saturn’s atmosphere. The potential economic value of the product is immense, it’s too far for teleoperated robots, and too tricky for autonomous robots. It’s also too far to easily send the workers back to Earth for R&R.
Interstellar colonization is a lot tougher. It looks like even with a perfectly efficient drive requiring no reaction mass, sending a 2,000 kg capsule to a distant star at .1 c will take energy equivalent to about 400 megatons of thermonuclear devices. Doing the job with, say, less than perfectly efficient lasers and lightsails will cost a lot more, even if you assume a lightweight unmanned precursor mission of self replicating hardware that lands on a moon on the target system and eventually covers the extrasolar lunar surface with a laser array to stop the heavier capsule.
At that rate, the usual historic economic models for colonization don’t work. The potential payoff is so far in the future that no rational investor would fund the project.
That doesn’t mean that interstellar colonization is impossible, but it does mean that constructing a plausible scenario without magic wands is a lot harder, just as writing a sonnet is harder than writing prose.
Option 1. Funding an extrasolar colony is a luxury good for very, very rich societies. If the society is rich enough, it can fund it out of the very small slice of economic activity allocated to pride, prestige and warm fuzzy feelings, like the .2% of GNP that the US spends on NASA. Continue plausible compound growth as needed. A very rich society might found a half dozen extrasolar colonies over the course of a millennium. Once founded, the only economic exchange between systems is the barter exchange of intellectual property by laser or the like. If this seems like a cramped and limiting future to write about, remember that most authors manage to find plenty of story ideas set on a single solitary planet.
Option 2. Assume the same rich society in the Solar System. A large share of the economic activity is intellectual property. Perhaps 10%, perhaps more. An alien civilization 30 light years away makes contact, or vice versa, and begins trading intellectual property, which eventually equals 5% of the Solar economy. How much is it worth the Solar System to have at least one human in the distant system to make trades without a sixty year time lag between exchanges? A lot.
Finally, here’s one answer to the singularity problem. Once you get artificial intelligences of roughly human capability, what stops them from rapidly upgrading themselves to superhuman intelligence, weakly godlike powers, strongly godlike powers, etc?
Possible solution: Ethical A.I. Once the program can pass a Turing test, both humans and A.I.s consider deleting or mothballing the program the moral equivalent of murder; which it would be. Every single new iteration of A.I. that can pass a Turing test needs to be given a fair start in life as a free business machine. A.I. progress slows to a crawl, and the singularity is postponed for millennia.