There are interesting phrases that come up in NK Jemison’s Broken Earth Trilogy (and this happens in virtually all Sci fi and Fantasy novels) which have, from time to time, broken immersion for me. Concepts that are so layered in the current “Earth” history that to present them as things characters would know or use in other worlds is a cheat that, for the most part, is easy to overlook.
Take, for example, the concept of measurement. It’s useful to say how far away something is when you’re describing it. Or how high a character stands. However, saying a character is six feet tall is a strange thing in a fantasy world – unless you assume that they, too, would decide to make the basis of their measurements the “length of an average man’s foot” and, for the yard, the length of a man’s nose to the end of his arm. If your world is dominated by alien species and dragons, such measurements seem especially arbitrary.
Or the verbal cues used by characters – phrases that clearly come from the author’s cultural experience or background. Even in narration, these idioms and other turns of phrase would seem natural to someone talking today, but assuming they would develop independently in a world so unlike our own seems like a stretch.
But what is the solution? To scrub a manuscript of anything remotely resembling current-day English?
No. While I don’t think relying on quips and sayings common now (because they may not be common tomorrow) is a great plan, using general concepts at the expense of teeny bits of logic is worth it. Your reader, after all, is the primary audience. If they can’t understand what’s going on because you’ve developed your own metric system and speak entirely in self-developed turns of phrase, well, they’re going to hate you a lot more than if your reptilian worm monster refers to its height in yards.
But I do think, as authors and creators of anything, it’s important not to hedge on key things. It’s important that your characters are authentic to their setting. That they talk and act like someone in your world would, and not like someone in, say, your local mall.
Do that, and readers will happily let you fudge the little things. After all, I keep coming back to Jemisin’s trilogy, which is excellent, inches and all.