Guest Post: “Working Out The Rules of Interstellar Travel” by Gareth L. Powell

Today the BiblioSanctum is pleased to welcome author Gareth L. Powell, author of Embers of War, the first in a three part science fiction series described to be perfect for fans of Ann Leckie, Alastair Reynolds and Adrian Tchaikovsky! The central character of the novel is a sentient starship, called the Trouble Dog. Following a brutal war and disgusted at herself for the role she played in the atrocities, she decides to atone by joining an organization dedicated to helping out ships in distress. Together with her new crew led by Sal Konstanz, a captain who actually once fought against Trouble Dog, they set out to investigate reports of a lost ship in a disputed system, hoping to save as many as they can. Published by Titan Books, Embers of War is now available wherever books are sold, so be sure to check it out! In the meantime, please enjoy this guest post by Mr. Powell on a most fascinating space opera topic – starships and space travel!

by Gareth L. Powell

Space travel is one of the staples of science fiction. Characters move from one planet to another. They set out into the starry unknown in search of adventure, glory, or vengeance—but as a writer, knowing how their starships work has a profound effect on the type of story we’re trying to write.

For instance, our first decision—whether our spaceships can fly faster-than-light or not—dictates the timescale of our story. If we decide to stick with the currently accepted laws of physics, it’s likely our heroes will have to enter some form of cryogenic sleep in order to prevent them dying of old age before they reach their destination. And if their journey takes more than a couple of decades, the world they left will be profoundly changed by the time they return, and some of their friends will have died in the interim.

Good examples of this temporal displacement can be found in Revelation Space by Alastair Reynolds, The Forever War by Joe Haldeman, and A Deepness In The Sky by Vernor Vinge.

However, if you’d like to move your characters from one place to another on a scale of days or weeks rather than centuries, you’re going to have to invent some sort of faster-than-light drive.

But, just as fantasy writers have to invent rules and limitations for the way magic works in their worlds, so SF authors have to work out a set a guidelines for how their spaceships behave. After all, if a ship can just go anywhere in the galaxy in the blink of an eye, there would be no way to defend planets or bases from attack. Hostile armadas could pop into orbit, unload a thousand warheads, and be a hundred light years away before the first one had exploded. Space battles would be impossible if ships could just leap away at any second. And how would economies function if you could import fresh produce from Betelgeuse as cheaply as buying it from the farm up the road?

Now, before you panic, I’m not asking you to describe exactly how your starship’s jump drives actually work. If you knew that, you wouldn’t have to write a book, as NASA would currently be showering you with money and asking you to build one! Instead, I’m suggesting you come up with some limitations. After all, you don’t have to be able to describe the inner workings of an internal combustion engine in order to know that your average car can’t travel at 8,000 mph or operate under water.

Classic ways of limiting FTL include putting upper limits on the distance a ship can jump at any one time, and forbidding jump engines from working inside a planet’s gravity well. In Larry Niven and Jerry Pournelle’s classic first contact doorstop, Mote In God’s Eye, resonances between stars mean jump engines only work if activated at a particular point within a system. In the TV series Babylon 5, most ships have to use a network of star gates, and only the largest ships have the power to open their own ‘gates’ into hyperspace. In both cases, it becomes possible to blockade a star system by occupying the jump point or star gate—and it can also lead to thrilling chases and battles, as ships try to slog across the system to reach the next gate or jump point. This kind of travel forms the basis of Jack Campbell’s Lost Fleet series, in which the remnants of a defeated navy have to travel the long way back through occupied territory, jumping from one system to the next while trying to avoid dead ends and ambushes.

In my new novel, Embers of War, I allow ship to take shortcuts through the ‘higher dimensions’—a place where the usual laws of physics are mutable and the speed of light can be exceeded. I liken the process to a dolphin leaping out of the water into the air. For a moment it finds itself moving through a different medium, where it moves faster because the water no longer drags on it.

However, in order to give my characters time to interact and get to know each other, I’ve had to impose a speed limit on higher dimensional travel. It isn’t instantaneous. In order to make the jump, a ship has to build up speed, kind of like the Delorean in Back To The Future. Then, once it’s in the hypervoid, its engines power it forward at roughly five light years per day. This means journeys can take days or weeks, and regular fuel stops need to be made to keep the engines powering the ships forward.

Whatever you decide, the way your starships move will shape your story, for good or ill. But learning to live with the limitations you impose will help make your story more interesting and authentic, and give your characters more obstacles to overcome.


Gareth L. Powell is an award-winning author from the UK. His alternate history thriller, Ack-Ack Macaque won the 2013 BSFA Award for Best Novel, spawned two sequels, and was shortlisted in the Best Translated Novel category for the 2016 Seiun Awards in Japan. His short fiction has appeared in a host of magazines and anthologies, including Interzone, Solaris Rising 3, and The Year’s Best Science Fiction, and his story ‘Ride The Blue Horse’ made the shortlist for the 2015 BSFA Award.

Embers of War by Gareth L. Powell is published by Titan Books. You can find Gareth on Twitter @garethlpowell

14 Comments on “Guest Post: “Working Out The Rules of Interstellar Travel” by Gareth L. Powell”

  1. Thanks Mogsy, that was a cool read; informative and thought-provoking. I’ve heard good things about this book, too. Must dig out ‘Ack-Ack Macaque’ from my tbr pile.


  2. Thank you so much for sharing this! 🙂
    And yes, limitations to what a ship can do are the way to give a story depth and pathos. This particular story looks very, very intriguing – I love sentient ships! – and I will certainly add it to my “wanted” list.


  3. Pingback: Mogsy’s Bookshelf Roundup: Stacking the Shelves & Recent Reads | The BiblioSanctum

  4. He mentions how fantasy writers have to lay a set of ground rules for how magic works and compares it to how science fiction writers have to set rules for how spaceships function. Yet, while both do require rules, I find writing rules for science fiction to be much harder and more stringent than rules for fantasy. Though good fantasy has rules, there is still plenty of room for leeway. When it comes to writing good science fiction, particularly hard science fiction, the rules have to come across as more realistic and believable.


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