While I'd like to write SFF or rewrite Hot Earth Dreams , this year I'm stuck spending most of my energy fighting developers who decided not to let a good housing crisis go to waste and are busy clogging California with million dollar fire traps. Right now, worldbuilding is my way to blow off steam, and I figured I'd pass some of it along for your amusement. If you're a writer, feel free to appropriate anything here. My ask for comments is to contribute to the effort: help me unpack the science in this essay, ask questions, and contribute cool worldbuilding science of your own. If this goes over well, there are other topics we can cover.

Unsustainable Interstellar Civilization

Yes, I'm an environmentalist, so if you think I believe truly this, you'll also believe that Charlie's an ardent royalist. Nonetheless, there's this meme floating around the SFF universe that the only way we'll make it to the stars is if we solve all the sustainability problems that plague global civilization today. This is correct, if we're stuck with STL (slower than light) interstellar transportation, because you can't live bottled up in a starship for centuries without mad sustainability skillz. However, if FTL (faster than light) transportation is possible, sustainability no longer matters.

Yes, I know FTL isn't physically possible. Whatever. As a plausible explanation for how it came about, consider the following scenario: Following WWIII, the global internet was destroyed, simply to prevent cyberattacks from continuing to wreck civilization all over the world. The internet backbone was physically severed, and Kessler syndrome destroyed satellite communications. No WMDs were deployed in WWIII, but it turned out the price of democracy (and autocracy) was isolation. That left a number of large data centers sitting idle, so some bright bulbs decided to repurpose these behemoths for deep learning and evolutionary engineering, to solve society's problems. One of the problems they threw at the data centers was The Theory of Everything; they fed in vast libraries of particle accelerator and cosmological data, and out popped the Theory. It didn't make any sense, but when they plugged numbers into the equations, the resulting predictions were accurate. One of the weird things about how the Theory of Everyhing handled spacetime was that C wasn't the limit we think it is now. When this theory was plugged into an evolutionary engineering system with an absurdly optimistic set of output specs, after some huge number of iterations, the system spit out a working FTL drive. Again, the design made no sense, but it could be built and flown, and it worked. Why it works is a mystery, because the systems weren't designed for helping humans decipher their outputs.

When you have FTL, you don't need long-term sustainability, so long as the rate at which successful colonies are founded is greater than the rate at which established colonies fail, with successful colonies being those that can build their own starships and found their own colonies. There are actually a number of Earthly species that live this way, and there's a whole little scientific field, metapopulation dynamics, that studies them. If humans can learn to pull off this trick with our extraterrestrial colonies, in theory we can expand indefinitely, especially if we expand slowly enough to return to this section of the galaxy in, say 50-100 million years, after which the planets we formerly colonized have fallowed long enough for us to colonize them again (basically by recycling the top kilometer or two of crust).

The way it works is that, once the first settlers on a new planet demonstrate that they won't die horribly from allergies, pathogens, or getting buried under the excrement of herds of titanosaurs, they then spread out to build mining settlements all over the planet, high-grade all the most accessible mineral deposits, drill for oil, and grow the infrastructure needed to build starships. With starhips built and trade links established, they grow into a mature colony over the course of a few centuries, all the while founding as many daughter colonies on new planets as possible. Eventually, they run into serious pollution problems, loss of usable mineral deposits, changing climate (both natural through the equivalent of Milankovich cycles, and anthropogenic), and a biosphere that coevolves to exploit the colony, because that's just what life does (think pesticide resistant bugs, coyotes, superweeds...). At that point, the colony starts to fall apart. Interstellar trade shifts away from it (after all, whatever's causing them to collapse them might be contagious). Ultimately the survivors hang on to become a truly resilient indigenous population in a backwater world--or all die horribly as their critical infrastructure fails. Their fate doesn't matter to our interstellar civilization, because it has literally already moved on to new frontiers, boldly going where no man has gone before. So long as they can find new worlds to conquer, they can go on forever.

Oh yes: planets, you ask. Why planets and not, say, asteroids? Or ice moons? The short answer is gravity, radiation shielding, atmosphere, and biosphere. We still haven't figured out how to complete a human life cycle in space, and it's not clear it's possible. We require gravity, and unless someone invents a usable gravity generator, we need planets to warp space for us. Even if someone does invent a gravity generator, on a planet you get gravity as part of the price of entry. If that planet has an active core, you also get a magnetosphere, which helps a lot with radiation shielding, plus things like plate tectonics. We don't have decent, light radiation shields either, so until people start building force fields that keep out radiation, a magnetosphere is essential. A nice, oxygen-rich atmosphere also does a lot to moderate the radiation experienced on the surface, and again, with a planet with a biosphere, you get this for free. And you can (to a first approximation) breathe the air. And yes, an alien biosphere can be counted on to cause problems. However, life does a lot of useful things, one of which is concentrating elements into ore bodies (something bacteria do with some elements). A combination of plate tectonics and an active biosphere means that you've got possibilities for a lot of concentrated ore bodies, petrochemicals like oil, and useful biochemicals--all the stuff you need to build a starship. While asteroids have these elements, they don't have them so much in concentrated ore bodies, so you've got to spend a lot of energy refining asteroids into useful feedstocks and dealing with the slag. The bottom line is that alien biospheres are dangerous, but so is living on an asteroid, and I suspect the former is the less dangerous option, at least for humans.

Hotspot Colonies

So you've found a fine, middle-aged planet, and you want to settle it (there's a little aside here about the evolution of planetary crusts that I won't go into here--ask in comments). Where do you site the first colony? My suggestion is to locate it on a mid-ocean, hotspot volcano, like Hawai'i, Iceland, or Tenerife. The advantages are that you're dealing with an isolated, fairly simple ecosystem, and if island species are sufficient to overwhelm your immune system and rot your brain (or cover you in piles of dung), you wouldn't have survived the mainland either. As the Polynesians and Guanche demonstrated, it's possible to terraform an island using neolithic technology, so you can probably establish an island colony with the contents of one or a few starships, even with 21st Century tech. Moreover, islands are quite fertile, both from the elements coughed up by the volcano and also from the excrement left behind by sea life hauling out on the island or using it as a rookery. Yes, what I'm recommending will result in the extinction of many no-doubt fascinating, even cuddly, island species, but if you're planning to do that on a massive scale anyway (it's called terraforming for a reason) and you have to start small, then it makes sense to start on mid-ocean volcanoes and see if you can establish a beachhead there. If living on an idyllic, isolated volcanic island causes your children to die horribly, then it's likely that you're not going to be able to successfully colonize this world anyway.

To successfully colonize a planet, though, you can't stop at one island chain. Islands may be good for agriculture, but they're missing things like the rare earths lithium that you'll need for electronics and batteries. Mainland settlements are necessary for the long-term success of a colony. At a minimum, there have to be mines and oil wells, extractive operations to feed back to the main colonies on the islands. At a maximum, the entire planet can be colonized and terraformed. But for a first colony, I'd suggest targeting a hotspot volcano in the middle of a big ocean. We know how to settle those on Earth.

Yes, I know there's a lot of planetology I'm ignoring here, like the story of planetary crust evolution. If people are interested, we can discuss it in the comments.

Dwarf culture



Red dwarf exoplanets, I mean. Can life even exist on a planet orbiting a red dwarf star? I have no clue, although reading the dueling model papers is fun. Here I'm assuming it's possible, but whether this is plausible is something to hash out in the comments. Anyway, assuming oxygenic biospheres can form on planets orbiting red dwarf stars, and assuming humans can live there...well, life gets interesting. The problem with red dwarf stars is they have the bad habit of emitting large blasts of x-rays and coronal mass ejections, so for humans, the best place for a long-term colony is either underground or behind a mountain. Being in the shade of a volcano isn't a bad idea.

Shade? That's the second issue. Red dwarfs are cool little stars, and that means that the habitable zone where water is liquid is far closer than Mercury is to our sun. A year for a habitable dwarf exoplanet is on order of days to weeks. As a result, the planet almost certainly has no moon(s) and it is tidally locked to the star. Tidal lock means that the planet rotates one day in one year, so that one side of the planet always faces the red dwarf, while the other is in perpetual darkness. The planet stays habitable because all the water on the planet flows to either the front side (so there's a huge ocean under the sun, due to a massive day/year long tidal bump) or the backside (where it freezes, except that heat from the ground below melts water at the base of the glacier, and this flows somewhere). Anyway, the star evaporates water and heats air, which together drive formation of huge storms under the sun, but which also move a lot of water and hot air around the rest of the planet, driving a planet-wide atmospheric circulation cell, so that hot air travels towards the back of the planet, while cold air moves to fill in the gap, and the whole thing reaches some sort of windy stable system.

There's probably no volcanic islands directly under the red dwarf (the sea's too deep there), and you wouldn't want to live there anyway, with perpetual hurricanes. The better place to live is closer to the terminator between day and night, where the sea is shallower and there are perpetual shadows behind the volcanoes. Or you can dig in. Earthly crops, unless they're massively genetically engineered to have photosystems that don't need ultraviolet light, will have to be grown in greenhouses, but with the sun in the same place in the sky, even setting up massive solar farms is pretty trivial, assuming you don't simply posit a fusion planet to power it all.

As for human culture on a red dwarf planet, that's where it gets weird. To start with, it's underground or in the shade. Sunbathing is a risky sport at best, and you'd better be wearing a dosimeter when you're casting a shadow. Timekeeping is even weirder. Humans have circadian rhythms as does most terrestrial life, so keep track of days, weeks, and so forth is useful in a red dwarf culture. However, there's no reason for everyone to stay on the same day-night cycle, because the sun never changes position. Why not organize the colony around shifts, say, three eight-hour shifts in a 24 hour notional day. It doesn't correspond to what's going on with the local sun, but it helps the colony be more productive and keeps everyone on time.

This is where dwarf culture comes into being. Since I like corny slang, I suspect that, in an FTL culture, "dwarf" will shift from meaning vertically challenged and refer to anyone who grew up on a red dwarf planet. After all, an underground culture where daylight is unending but which shift you work is culturally important is pretty alien to someone who grew up on Earth, with its days and nights, seasons, going outside, and not worrying about solar flares. In terms of interstellar politics, dwarves from different colonies may find that they have more in common with each other than they do with people who grew up on swiftly spinning planets like Earth. Since there are a lot of red dwarf stars out there, factional splits between dwarf and "normal" colonies could have huge political implications for how interstellar civilization works. Working out the details is where the fun begins for the writer.

That's my three tidbits. Feel free to add your favorite exoplanetology lessons for writers in the comments below.