F is for Faster Than Light

falcon_startrailsRemember that moment in Star Wars when the Millennium Falcon went into hyperspace?  When Harrison Ford shouted “go strap yourselves in, I’m going to make the jump to light speed,” and the sky lit up as the stars streaked by?  That was my first introduction to faster-than-light (FTL) travel, and I haven’t looked back since.

FTL is a major recurring trope in space opera, and not just because of how cool it is.  If you’re going to have a galactic empire, you need some way to get around that empire–or at least some way to transmit information without too much difficulty.  The distance between star systems is measured not in miles or kilometers, but light years–that is, the distance that a particle of light can travel in one year.  Considering how the nearest star to Earth, Proxima Centauri, is ~4.24 ly away, you can see the need for some sort of magical technology to bridge the distance.

FTL travel comes in four basic flavors:

  • Warp Drives — The ship breaks the speed of light as easily as our modern fighter jets break the speed of sound.  Impossible to justify, except through hand-waving.  The most prominent example of this is Star Trek.
  • Jump Drives — The ship disappears from its current position and reappears somewhere else.  Also requires hand-waving, but is at least a little easier to justify.  Battlestar Galactica is a good example of this, as is Schlock Mercenary.
  • Hyperspace Drives — The ship enters an alternate dimension which allows it to travel faster through our own.  The alternate dimension is called ____space, usually “hyper” but also “quasi,” “x,” etc.  Star Wars is the classic example, though Star Control II took things a step further by having a hyperspace dimension within hyperspace.
  • Wormgate Network — The ship (or maybe just the passengers) enters a portal which transports it to a portal somewhere else.  A network of these portals allows travel throughout the galaxy.  Stargate and Babylon 5 use this method.

An alternate way to do it is to make FTL travel impossible, but hold the galactic empire together through FTL communication.  This technology, known as the ansible, features prominently in Ursula K. Le Guin’s books and the Ender’s Game universe.  It has some really interesting implications: for example, even though planets can communicate instantaneously with each other, it takes almost 40 or 50 years to go from one to another, but at near-light speeds, it feels as if only a few months have gone by.  Thus, if you’re going to travel to another world, you have to leave everything behind, including your family and loved ones.  By traveling from world to world, you can skip entire generations, spreading your natural lifespan across thousands of years of normal time.

In writing FTL, one thing you have to be really careful about is to keep in mind ways in which the system can be abused.  For example, if jump drive technology makes it possible to instantaneously transport anything anywhere in the universe, then you can bet that someone is going to send a bomb into the White House (or whatever the equivalent is in your fictional universe).  Thus, the invention of unrestricted jump drive technology will lead to a very short and brutal war.

This actually happened in Schlock Mercenary, and the solution was Terraport Area Denial (TAD) zones, or broad areas of space where a force field prevents anyone from either jumping in or out.  Thus, anyone who wants to visit a planet in a TAD zone has to jump to the edge of the field and travel the rest of the way at sublight speeds.

FTL isn’t always appropriate for a science fiction story.  If the story is supposed to lean more toward hard sf, then it’s probably better to stick with our current understanding of the rules of physics, which state that nothing can travel faster than the speed of light.  Still, with things like quantum entanglement and other recent discoveries, if you know the science well enough, even the speed of light might not be an upper limit.  But for the rest of us mortals, FTL is basically just magic–a sufficiently explained magic, perhaps, but magic nonetheless.

Personally, I’m a fan of the jump drive form of FTL.  That’s the one I use the most in my own books.  The cost is that the further distance you try to jump, the harder it is to pinpoint exactly where you’ll end up.  To overcome this, you can use jump beacons to draw out anyone trying to jump into your particular sector and have them exit jumpspace next to the beacon.  This comes in handy in combat, when the enemy tries to jump a nuke onto your ship.

In the later Gaia Nova books, FTL is facilitated by jump stations spread out in a line across space, with reactors powerful enough to jump ships rapidly to the next point along the line.  In the earlier Star Wanderers books, that technology hasn’t been invented yet, so there’s still an Outworld frontier.

It gets kind of complicated, but it’s lots and lots of fun to world build.  For example, how does a particular change in the FTL tech alter the galactic balance of power?  When settlers try to colonize a new system, what do they establish first–starlanes, jump beacons, Lagrange outposts, or what? As with any magic, changing one thing affects everything else, which also affects everything else, which … yeah, you get the picture.

By Joe Vasicek

Joe Vasicek is the author of more than twenty science fiction books, including the Star Wanderers and Sons of the Starfarers series. As a young man, he studied Arabic and traveled across the Middle East and the Caucasus. He claims Utah as his home.

4 comments

  1. I always found it interesting that you could have fast communication, but not travel, since we can already break the speed of sound. How would you get sound to travel quickly over large distances? Surely that would involve some sort of jump too?

    In my world, I have handwaving FTL, but no communications. Meaning no one can come and rescue you in an emergency, and my tiny village is stranded on a planet with no way to let anyone know they are still alive.

    FTL, and communicaions, can lead to some interesting situations.

    Rinelle Grey

  2. Well, most of our real-world communications systems transfer information electronically, through waves or signals that propagate at the speed of light. For practical purposes, that means that we can communicate almost instantaneously between any two points on Earth (provided we have the right kind of network set up for it). But once you start moving out to the rest of the solar system, things get kind of fishy.

    It takes light about one second to travel from here to the moon, which made for some hilarious moments in the anime Planetes when Hachimaki got into an argument with some friends of his while at the lunar medical center. Mars is several light minutes away, depending on its orbit and where it stands in relation to us. And the furthest man-made objects, the Voyager space probes, are currently almost a hundred light hours from Earth (and STILL just barely on the edge of the solar system).

    With our current technology, communication between stars would be difficult if not impossible. Any sort of signal would be bound by the speed of light, which means that it would take over four years to send a message to Proxima Centauri (and we’d either have to send it in Morse code or use a really, really, really powerful signal generator). If you have FTL travel, presumably you could have the starships convey messages from other places, but that would be kind of like sending letters between islands in the Pacific (unless you had some sort of intergalactic pony express … hmmm).

    Either way, the constraints certainly lead to some interesting story possibilities.

    1. Actually, Voyager 1 is only about 16 light hours away! (From the calculators I can find).

      I think communication on the planet only appears to be instantaneous, because the distances, on a universal scale, are quite small. The reality though, is that anyone who’s spent any time on multiplayer game servers knows that you get lag, differences in signal response, quite quickly. Not noticable on the telephone line, but get much more accurate, and it is.

      Bit hard to run a fiberoptic cable between planets. 🙂 Not sure what other options there are for long distance communications. My brain just won’t even come up with something that works in any way other than light or waves. I’m really surprised sci-fi hasn’t played around with this more.

  3. Ah, that’s right. Voyager 1 is currently a little over 123 astronomical units (AU) from Earth, which is probably where I got that number in my head.

    There are a few sf authors who have done some interesting things with FTL communication. One of the best examples of this is the Hainish cycle by Ursula K. Le Guin. In The Dispossessed, the main character is the guy who invents the ansible device, and the implications of how that tech could alter the galactic balance of power (something that completely goes over his head because of his anarchic upbringing) makes for some fascinating storytelling.

    Orson Scott Card also features a galactic ansible network, which figures quite prominently in the whole Ender’s Game series. In Xenocide, he goes into all the metaphysical explanations for how it works, which are actually quite fascinating, as well as directly relevant to the storytelling. Just as the philotic web involves quantum entanglement of particles, so on a macroscopic scale (in his universe, at least) humans are also interconnected. The end result of it all is Jane, probably my favorite AI character of all time.

    In real life, we’ll probably keep using electromagnetic waves until we figure out a way to apply quantum entanglement to an interplanetary communication system. I’ve got an idea for a book in my Gaia Nova series that revolves around that: basically, transceiver pairs that can communicate instantaneously with each other, and nodes that act as communication hubs between multiple pairs. Of course, the entanglement process is so expensive, and the bandwidth so limited, that usage is limited to Imperial officials, major interstellar corporations, and high ranking socio-political elites. Since the Hameji have basically smashed the empire by the time this book begins, the ansible network is completely destroyed … except for one critically important node. 🙂

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