After coming back in (more or less) one piece, September's been reasonably productive. I've managed to finalise the plot for the second volume in my trilogy, Descent: Diaspora, so I'm able now to stick it in a shelf while I get stuck into volume one, Descent: Death, with a view to finalising it for printing. I'm giving it a final brush up before The Gatekeeper comes back with the inevitable changes - hopefully they'll be minor and it will be a smooth process from here on in.
While plotting Descent: Diaspora I started thinking about time travel. No, not actually doing any time travel (although we all do without knowing it; yes, it's all in one direction and yes, it's all around 1 second per second, but it's still time travel if you want to be pedantic) but how it's used in science fiction. It made a bit of a cameo in my first novel, Sha'Kert, and I think it will push itself up a little more in volume three of my trilogy, Descent: Destiny (that's no sure thing yet), but I have used it a few times in my short and flash science fiction writing, at times as the core element, other times as a prop for the main plot. So what was the outcome of all my rumination? Should I write about time travel?
Well, time travel's a bit of a cop out, I think. Get into a seriously knotty plot problem? Easy, have your main character go back in time and sort out the issue. Have a tangled, warped plot that makes no sense with no possible outcome? Time travel's the culprit and the cure, just write it in. Having trouble coming up with a story line at all? No dramas, do a time travel piece, easy territory, familiar ground. It's probably harsh of me, there's some excellent fiction out there built around the idea, but there's an obvious (if not too entertaining) drawback - and it's all Einstein's fault.
Relativity. No, not about speed of light flight, event horizons and all the rest, but the idea that to fully understand something it is critical to look at it from all positions, as they would see it. And there's your problem (as a certain TV show would say).
If you have a time traveler who shuttles back and forth, changing this and that until they are happy with the result, there's an interesting dilemma that arises. From their perspective, unless they have some sort of 'time stasis field' (my apologies) there was never anything to change anyway; the end result is, to them, the way it always was. Several better-known authors get around this by placing the main protagonists in a separate universe / dimension / plane of existence where the changes made do not impact them or their memories, but there's yet another dilemma that rears its ugly head.
Everything in the universe or time-line (urk, sorry, its an unlovely phrase now, but you know what I mean) that's impacted has no history other than the final state once all the changes are wrought, so there's nothing to actually change at any point, and no observer can actually see anything to change. As a corollary, at no point in its history is there ever any condition or state that does not correlate to the final, finished state post changes; to all observers at all times and perspectives, all that exists is the finished state. It's a cousin to the grandfather paradox, but a little further removed.
A classic way to get around this is the 'multiple universe' or 'multiple time-line' trope; each change made spawns a new universe, exactly like the old one except for the change and it's consequences. Star Trek is an absolute junkie when it comes to this, both in their series and movies, and the end result is a convoluted and loosely written body of work. Ok, I'm not picking on Roddenberry or his heirs specifically, they're just an example, but they're a clear example and easy target.
But in the world of science fiction, who gives a fig? Every author should. Although our readers do suspend belief while they read our work, there's still an element of 'yes, well, it could be possible' or 'ok, at least it's consistent' that we do have to honour. Time travel, if used as a plot device, should not be used as a way to dig ourselves out of impossible plot holes, or as license to throw away 90% of the story for a 10% crash-boom ending. And time travel as the central feature of a science fiction novel? Heck, that went out in the 1980s.
Treat your readers with respect; not only for their knowledge of the genre, but also for what they may know that you don't. You never know if one of your readers is a theoretical physicist; or a time traveler.