I’m back, and I’m as anal-retentive about science fiction as ever!
the final frontier a popular setting for SF, with good reason. Now that James Cameron has been to the bottom of the ocean, space is the only setting where we could run in to alien artifacts or extinct civilizations or giant crystalline computers housing sentient AIs but then the twist at the end is that they’re naturally occurring I guess? (That’s my idea. You’re not allowed to use it.)
So space is awesome. It’s also way outside our ability to easily visualize, which is why astrophysicists are paid so lavishly* to visualize it for us.
Even still, there are a few fundamental aspects of space travel that almost every SF writer overlooks. Even a quick Google search would reveal to them the true depths of their folly, and yet they make the same mistakes over and over again.
With that in mind, your space travel might be terrible if…
…you forget about Newton’s First Law.
This is easily the most common mistake SF writers make when they write about spaceships. Newton’s First Law states that:
The velocity of a body remains constant unless the body is acted upon by an external force. (Wikipedia)
We’re used to traveling around on Earth, where the general rule is ‘stuff only moves if you keep applying force to it’. If you stop your car’s engine, the car is only going to keep coasting along for a few seconds before it comes to a halt. If you’re riding a bike and you don’t pedal for long enough, you will eventually come to a complete stop. That’s ‘just how things work’, the same way a priceless vase will ‘just fall’ if you happen to knock against it as part of a comically over-the-top slapstick routine.
no one can hear you scream those rules don’t apply. Or rather, they do, but the factors that make them work the way they work on Earth are largely absent. There is very little ‘external force’ to act upon a space-body in motion.The most obvious consequence of this is that a spaceship (or anything else) in motion will stay in motion unless something stops it. Remember, the ship doesn’t have wheels trundling over tarmac, nor is it fighting resistance from air (more on that in a bit). If you use up three-quarters of your fuel getting to top speed, you now have no way of stopping, because slowing down completely is going to take just as much fuel as accelerating. You’d end up drifting through space forever. (Well, unless you hit something. But that’s spectacularly unlikely.)
Of course, this also means that there’s no reason whatsoever to run your engines constantly. You need them to accelerate, but not to keep going; again, you’re not talking about flying a jetliner here. Unless your characters are in an unstable orbit around a planet and need to readjust their trajectory immediately or else risk crashing, their engines ‘failing’ shouldn’t trigger a desperate scramble to repair them, because they don’t technically need to fix them until they have to either stop or change the direction they’re going.
This mistake is closely related to the following one.
…you forget that space is frictionless.
On Earth, aircraft are designed to take advantage of the fact that our atmosphere is composed of some sort of gaseous, air-ish stuff. Scientists call it ‘air’. Anything designed to go really fast through the atmosphere is going to need to take into account the fact that air suddenly becomes a lot more difficult to move through when you’re traveling upwards of 1,000km (or more) per hour. That’s why jet fighters are shaped the way they are: they need to be aerodynamic.
Space vehicles have absolutely no business looking or behaving anything like a jet fighter unless they routinely take off through an atmosphere. If they stay in space all the time (as any really large spaceship would), their design should be constrained by factors other than air resistance.
For example, look at the International Space Station:
That thing would snap like a twig if you tried to fly it through the atmosphere, but there’s no particular reason why you couldn’t strap some rockets onto it and send it blasting through deep space.
This also means that spaceships shouldn’t maneuver the way planes do. If a spaceship wants to turn around, the easiest way to do it would be to turn around on the spot, so that it would be flying ‘backwards’. (Remember, it’s going to keep moving in the direction of its last acceleration, not in the direction it’s now facing). Any dogfight in space would quickly end up with two ships moving in the same direction while facing each other and then promptly blowing each other up. This is also a good reason for ships to not have thrusters only at the back, by the way, because that would limit their ability to reorient themselves relative to whatever they’re interacting with. In space, that would be far more useful than being able to swoop around like a jet fighter.
Incidentally, this also means that Asteroids is a more realistic depiction of how a spaceship should behave than any other video game ever.
…you have no sense of scale.
Space is big, that Douglas Adams quote, you know the drill. Except maybe you don’t.
While most people understand on some level that the distances involved in space travel are orders of magnitude larger than anything involved in traveling around Earth, they sometimes ignore the consequences of those distances…like the fact that being able to move at a significant fraction of the speed of light still wouldn’t be good enough if you want zooming around the galaxy to be as easy as going for a cruise. (Keep in mind that even traveling at the speed of light, it would take over four years to reach Proxima Centauri.)
Space-distances (the official term for them) also have some pretty serious consequences for long-distance communication. Recall the scene in 2001: A Space Odyssey where the BBC airs an interview with the main characters. It’s mentioned at the beginning that there’s a significant time delay between a question being asked and the TV station receiving the astronauts’ responses because of how far they are from Earth. The delay is at least several minutes (I’ve forgotten how long exactly), making real-time communication impossible, even though the people trying to communicate with each other are within the same solar system.
Now imagine what it would be like to communicate between systems. If a distant colony sent out a distress signal, it would be year before any other system received it. By the time the would-be rescuers could react and launch a rescue mission, the problem would either have fixed itself or else the colonists would all be dead, even if the rescuers had ships capable of light-speed travel. If the Proxima Centaurians needed our help tomorrow, the absolute minimum possible time between them sending a message and us arriving would be a bit under 8.5 years (from their perspective.)
The easiest way around this problem is an ansible, which is one of those SF tropes that are so common you almost don’t need to explain it. Also keep in mind that having faster-than-light travel doesn’t necessarily fix the communication problem if you don’t pair it with some sort of ansible; in an FTL/no ansible scenario, it would actually be faster to send a letter on board a ship than it would be to communicate the same message via radio waves or some other broadcast signal.
(Also keep in mind time dilation, which kicks in at noticeable levels when you’re going really fast and might be of use if you’re okay with your space travelers outliving all of their loved ones/their entire civilization while they’re on their way to the Adventure System.)
But all is not lost! Your space travel might not be terrible even if…
…you have gravity on your ships.
Look, some SF novels are so hard that they were originally bound in diamond. If you’re writing something like that, you will probably not get away with having your characters walk comfortably around their spaceship with no mention of how they’re generating artificial gravity. (Although do keep in mind that being weightless because you’re in an orbit is not the same thing as being unaffected by gravity.)
For everyone else, hand-waving the gravity problem is perfectly acceptable. In fact, don’t even bother hand-waving it. Just don’t mention it. Nobody cares, and any explanation you give will only remind people that you’re technically breaking the rules.
…you have FTL with no real explanation.
This is going to be a contentious one, but I see nothing wrong with saying ‘Hurray, we invented FTL travel at some point, ‘it’s adventure time,‘ even for serious SF. Throw in some advanced alien technology if it makes you feel more comfortable with it, but just remember that most readers are willing to look the other way when an author casually violates the laws of physics.
…nobody dies of radiation sickness.
Do I even have to elaborate on this one? Yes, space is awash with dangerous radiation. No, that doesn’t mean most people want to read about it.
And now you’re all set to go and write some space-travel SF! Did I miss any important points? Let me know in the comments.