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The Trouble With Time Travel

by | Apr 21, 2021 | World Building, Writing | 0 comments

Have you ever noticed in science fiction stories involving time machines that the machines in question seem to defy all logical explanation? And I don’t just mean the physics of time travel, though that’s an interesting topic by itself. No, what I mean is how the machine seems to ignore physical location when travelling through time.

In any story, a degree of narrative convenience is necessary simply for the sake of having the story happen. But one convenience—or more accurately, contrivance—time travel stories too often suffer from is failing to take into account the fact that Earth is a celestial body travelling at some 67,000 MPH. It wouldn’t be in the same place when travelling through time!

Let’s say you build a time machine in your London home’s basement. You climb in, start the machine up, and decide that as a simple test you’ll go back in time by precisely 24 hours. So where was the Earth 24 hours ago? If it travels 67,000 miles every single hour, then multiplying that by 24 gives us a rough figure of 1,608,000 miles travelled.

Our scientist, who probably isn’t very bright if he’s not thought about this issue, sits in his machine, prods the buttons, sets the Flux Capacitor just so, and hits the big red GO! button. He travels back 24 hours to the exact same spot he’s in right now. Unfortunately, the spot he’s in right now is based on the position of Earth right now as well, not the Earth of 24 hours ago.

As a result, he appears in space and immediate dies from being exposed to hard vacuum. Maybe the assumption is that the time machine somehow compensates for the Earth’s movement and not only travels through time, but space as well? But if that’s the case, this is no longer a time machine, it’s a teleporter with time travel functionality, because it would have to be by sheer necessity.

In a sufficiently advanced future setting, this is less of an issue because you can simply mount the time machine onto a spacecraft and sidestep the issue to some degree (Stargate: Atlantis did this very thing). But even then, you’d have to have faster-than-light—warp, hyperspace, wormholes, whatever—capability for this to be viable, because if you travel back in time and the Earth is now on the other side of the sun, that’s a hell of a long trip back home in normal space at sub-light speeds.

The other way to deal with this would be to simply ensure that you travel back to a time when the Earth is in exactly the same position as it is in the current time. So if it’s May 3rd and you want to travel 100 years back, simply calculate it so that you arrive on May 3rd.

Of course, this presents its own problems. For starters, there’s no guarantees you’ll arrive at precisely the right moment, and could therefore be in mid-air or otherwise about to take some serious damage. But you also have no clue if the world back then had a different building in that spot, or maybe furniture or other clutter that you could phase right into upon arrival. So again, not an ideal solution.

At the end of the day, narrative convenience often trumps logic, but I’d argue that if you’re writing a sci-fi work where complex subjects such as time travel are involved, you should be putting in that extra bit of legwork to ensure it adheres to some of the basic laws of reality, even when your story breaks those bounds in some form.

If you’ve just created a time machine, chances are you’ll have the knowledge and ability to create a teleporter to go with it, so why not? Just throw a bit of technobabble in there to explain why and how this issue was fixed, then you can happily focus on the time travel portion of the story.

You might think I’m picking nits… and yeah, I kind of am, because I enjoy it 🙂 But just because something is a bit nit-picky doesn’t mean it’s not also valid. And I’d really like to see more time travel stories properly tackle the issue of traversing not just time, but space, too.

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