Voltaire is said to have described etymology as a science in which vowels count for nothing, and consonants for very little. The line’s provenance is questionable, but the point holds. Over time, vowels shift and so do consonants: words may transform radically. If people are around in a few centuries’ time, we won’t just be using lots of new words: we’ll be using old words that sound different.
I haven’t seen this treated much in science fiction, despite the genre’s reliance on time travel and future scenarios. But I came across an example last weekend in the Ursula K. Le Guin–edited Nebula Award Stories of 1975. Joe Haldeman’s story ‘End Game’ is a futuristic military drama that refers briefly, on a few occasions, to phonetic change and to language change more generally:
(1) Language, for one thing, was no small problem. English had evolved considerably in 450 years; soldiers had to learn twenty-first century English as a sort of lingua franca with which to communicate with their officers, some of whom might be “old” enough to be their nine-times-great-grandfathers. Of course, they only used this language when talking to their officers, or mocking them, so they got out of practice with it.
(2) Most of the other officers played chess, but they could usually beat me – whenever I won it gave me the feeling I was being humoured. And word games were difficult because my language was an archaic dialect that they had trouble manipulating. And I lacked the time and talent to master “modern” English.
(3) He said a word whose vowel had changed over the centuries, but whose meaning was clear.
No dialogue or descriptions provide any details of the form to which English had changed in four and a half centuries, but that may be just as well, as it leaves it to our imagination and avoids suggesting something a linguist might object to. It’s nice to see the subject addressed at all, and so explicitly; the sociolinguistic reference to mockery is an especially good touch.