In fiction, both written and on-screen, there are certain “uninvented inventions” whose properties transcend any one story. We know how these things work, how they operate, and when they appear in a new story we understand their import just as well as we understand anything familiar from the real world.
Faster-than-light travel, for example. Virtually all fiction that deals with interstellar distances employs some method of getting around the problem of relativity for both travel and communication. Usually, either the method involves shifting to some alternate form of reality where the rules are different (subspace in Star Trek, hyperspace in Star Wars), or using a wormhole or some equivalent artificial shortcut to render distances moot (2001: A Space Odyssey and its sequels, Ursula K. LeGuin’s Hainish Cycle). In reality, it’s far from clear whether any such thing is even remotely possible, but in fiction we’re used to it. We buy it, emotionally speaking.
I once attended a talk by a philosophy student who referred to these things as “unfilled categories,” or perhaps a similar phrase I now forget…she included not only technology but also biological and spiritual phenomena that exist in the popular mind, but not otherwise, pointing out that some of these categories have since been filled (space ships and robots, for example). She argued that the category “undead” has now been filled by…wait for it…frozen sperm. Human sperm can’t live more than 48 hours, and dead sperm can’t impregnate a woman. Since frozen sperm can be thawed and used years after collection, it violates both the “live” and “dead” categories and is therefore undead. The talk was very entertaining, but logically, quite sound.
Uninvented inventions, or unfilled categories, can be used to explore possibilities. As I’ve discussed before, over a century of fiction dealing with the possibility of artificial life has prepared us to ask some very important questions about the genetic engineering technology we now have. Writers can also use uninvented inventions to avoid having to deal with certain inconvenient truths, such as the speed-of-light barrier. Finally, there are simple flights of fancy—like time travel.
We all know how time travel in fiction works.
Young Marty McFly, for example, goes back in time and meets his parents as teenagers. Unfortunately, his mother-to-be ends up more interested in him than in his father-to-be, so he must play matchmaker for his parents or disappear, never having been born. He is successful, and returns to his own time, pleased to discover that his intervention gave his father the necessary confidence to become a much cooler dad. Everyone lives happily ever after (after the sequels). Right?
Right, but if Marty McFly had failed in his matchmaking, and ceased to exist, then how could he have interrupted his parents’ courtship? He wouldn’t exist! Logically, it should be impossible to go back in time and change history in such a way as to prevent the time travel in the first place. For the same reason, all plots that involve someone going back in time to solve a problem shouldn’t work, because once the problem is solved, the motivation for time travel disappears. There are other severe rational inconsistencies. And yet we are all so familiar with the conventions of fictional time travel that these plots work emotionally.
Look, I’m not trying to say that everybody is doing time travel wrong. Fictional conventions have their own integrity, and many of these stories are a lot of fun. Why do children returning from Narnia revert to their old physical age but retain their memories of their years in the otherworld? Because magic, that’s why. As long as fiction is sufficiently believable to permit willing suspension of disbelief, that’s good enough.
And yet if you really want a story about what time travel is like, the current body of stories won’t provide.
The central problem with typical time travel stories is revealed when you imagine what the story looks like from the perspective of an objective observer in a normal time sequence, not the time-traveling protagonist. Take Marty McFly, again. He and the DeLorean appear suddenly in a farm field out of nowhere, thus violating the First Law of Thermodynamics, which states that matter and energy can neither be created nor destroyed. Where did they come from? The future? But that’s not a “where.” How and why does traveling in time mean showing up in a place where your existence cannot be accounted for by the laws of physics?
When time traveling, shouldn’t you show up in a place where you actually were at the time you are going to? Shouldn’t going back in time look like rewinding to an earlier part of the movie? An earlier page of the book? Shouldn’t time travel simply be a form of perfect memory?
The reason I bring all this up is that, as delightful as the typical time travel narratives are, it would be nice to see what a good writer could do with a clean slate and a rigorously logical approach. What stories might be possible with time travel framed as a shift in perspective, not quasi-physical movement?
This is the central difference between science fiction as it is typically practiced, in which the story comes first and realistic speculation may be compromised as needed for the good of the story, and science-based fiction, which is what I write. In the latter, an adherence to realism itself generates the story.
The result is not necessarily without wonder and whimsy. Remember that as flexible and powerful as imagination is, fantasy is always limited by the imaginer. Reality is where we can go to be surprised.
Realistic time travel has been done in fiction, by the way. Read Slaughterhouse Five, by Kurt Vonnegut, Jr.