Recently I was re-reading What if the Earth Had No Moon? by Neil Comins. Reading nonfiction speculation about what conditions might be like if you vary various parameters when building a solar system makes me think about the real universe and the Fermi Paradox, about life and complex life and intelligent life and technologically advanced life and all like that. And you know, I kind of wonder if it’s that last step, to advanced technology, which might be the kicker.
I think that’s the way it’s going to be in my science fiction universes, at least. Space opera is more fun if you allow lots of habitable words.
In the real world, I think it’s fairly unlikely that life as such is all that rare. If there are something like 500 billion galaxies, and about 200 billion stars in a typical galaxy, and about a fifth of all stars have Earth-sized planets . . . uh, where does that put us? Well, according to Kepler data, in 2013, astronomers calculated there could be as many as 11 billion Earth-sized planets orbiting in the habitable zones of Sol-type stars in just our galaxy. That’s a bunch, and you can multiply that by 500 billion or so for all the rest of the galaxies. Cut that number by nine-tenths to leave just the ones that are actually fairly comfortable for life-as-we-know-it and that is still a whale of a lot of planets.
Supposing it’s not that hard to get organic molecules followed by simple replicating ribozymes or whatever, followed by cellular life and then multicellular life. That particular step, to multicellularity, doesn’t appear to be all that tricky, since multicellular organisms appear to have independently evolved about fifty times on Earth. So supposing all that, what could stop complicated life from appearing everywhere, waving clubs one day and uploading their brains to super-advanced computers the next?
Here are the sorts of things I think might have prevented massive explosions technologically advanced species in my science fiction universes, even if intelligent life is common. Everything on this list presupposes that life is everywhere and intelligent life is not rare either.
1. Watery worlds. You need lots of liquid water to get the kind of ecosystems that look homelike to humans, but if your various intelligent species happen to be aquatic, they are completely screwed as far as technology goes. Orcas and narwhals and for that matter octopuses could be sentient for all we know; how would we ever be able to tell? An aquatic species is not going to smelt metals, much less build Dyson spheres, so a world that offers just a scattering of islands and plenty of ocean surface could be quite nice to live on for humans, but would probably not have a recognizably intelligent native species. Certainly not a technologically advanced species.
2. The world lacks metals. Clubs and stone knives, sure. High tech, well, good luck with that.
3. Recent meteor impacts. Anything like what knocked out the dinosaurs would re-set the evolutionary clock. Sorry, troödontids! Nice campfire you had there, congrats on the clubs and reed baskets, but now we have to start over with those tiny little mammals.
4. The Earth’s climate has been amazingly stable over the past billion years. Ever since the last terrifying “Snowball Earth” episode, during which all the water on land froze, sublimed, blew out to sea, and left the land bone-dry; and the oceans froze over so solidly that the liquid water below the ice decoupled chemically from the atmosphere and both became toxic . . . as I say, since then, the climate has not varied enough to seriously discommode living organisms. Glaciations have merely been mildly inconvenient. But maybe that’s not usually the case! Maybe most words within a star’s habitable zone actually experience a Snowball Earth type of event at just about the moment people start tapping flint into spearpoints. Or sailing around the world on tall ships. A civilization would have to be quite advanced to have a chance during *real* climate change.
5. Gamma ray bursts or supernovas or other such astronomical events pretty much sterilize your planet at some inconvenient moment, such as just about when you are ready to start sending space probes to investigate nearby planets. Life on your planet has to start over with extremophile bacteria. Sorry. Sucks to be you.
6. There’s an intelligent species and it’s getting up there with technology, but it never thinks about leaving its planet because (a) it’s blind and has no idea the stars even exist; nothing even suggests these people should look up to find out if anything’s up there because why would that ever occur to them? (b) it’s not blind, but planetary conditions restrict its view of stars; (c) its physiology forces its attention to go in other directions. Think of “Love is the Plan the Plan is Death” by James Tiptree Jr.
7. There’s a perfectly nice habitable world, but it’s the moon of a giant planet and even though the people look up and think wistfully about the stars, escaping from that massive gravity well is no joke.
8. One or more of the species to achieve advanced technology is crazy-mean and exterminates other intelligent species wherever it finds them. All their neighbors are out of luck, especially if they build robot exterminators and send them out in all directions. I know variants on this theme are pretty common in SF.
9. When stepping from early industry to nanotech, someone makes a tiny error and turns the entire surface of your world into gray goo. Of course apocalyptic visions by foaming-at-the-mouth fanatics will serve as well as error. Either way, if your species wasn’t already established in space, you all die. Sorry. Not quite as common in SF, but it certainly seems plausible.
10. What’s one I haven’t thought of? Got a favorite? Remember, your explanation should involve stopping intelligent species from becoming technologically advanced. This particular list is predicated on the idea that there is no bottleneck for intelligence as such.