So we write about time travel to the past, but not all of us do it the same way. You see, time travel creates logic problems called time paradoxes. We all know the famous ones, which are related to the idea of killing someone necessary for our own existence. Kill your virginal grandparent, and you can’t exist, but if you don’t exist, who killed the grandparent? And what about all the other people whose lives change because gramps is no longer around? Your one action prevents a growing chain of events, each of which spreads out into a web of others.
So then what?
In fiction, a time travel plot comes from the way a past action can change the future. In some stories, it does. In others, the characters try to prevent it. In yet others, they try to redirect events to produce a more desirable history. All these stories are potentially interesting if they are done properly. Let’s get into some examples.
Classic time travel stories can be found in Star Trek: The Original Series. These are aimed at using the characters’ ingenuity to preserve the timeline. “Tomorrow is Yesterday” follows the classic pattern. The Enterprise crew is thrown back in time to 1969 and accidentally captures a pilot who has a crucial role to play in earth history. Once they are returning back to their original time, they use the transporter to put him back in place in a way that prevents his ever having come aboard. This isn’t fully logical (sorry, Spock!) because if the pilot never came aboard Enterprise, then no one should remember, but our heroes do. This is a fun story and a great episode, however. In “Assignment: Earth,” a kind of sequel, the ship returns on purpose to 1968 to conduct historical research, only to get sucked into the activities of characters from a failed attempt to launch another show and wind up having to do the best they can to avoid disrupting a timeline even though they don’t fully understand it. This is, again, logically silly, but entertaining, and worth watching also for an early-career appearance of actress Teri Garr, who in my opinion is totally dreamy.
The best, by popular consensus, of the ST:TOS time travel stories is “City on the Edge of Forever,” credited to Harlan Ellison although his idea was almost completely dismantled by four other writers. The story won numerous awards, deservingly so on the whole. An alien technology throws Kirk, Spock, and McCoy into 20th century New York, where Kirk must sacrifice his love affair with a social worker, Edith Keeler. Kirk allows Edith, played by soap opera star Joan Collins, to die so that history can work out properly. This story of nobility and tragedy is generally considered the best episode of the original series. (You can see Edith, recast, interacting with Kirk years later in the Star Trek Continues episode “Divided We Stand.”) Although it is a must-seek if you like Star Trek, even “City” is logically flawed, because, like many other stories of its type, it assumes that only great people matter to the course of events. But really, anything can matter.
This is called the butterfly effect, name courtesy of scientist Edward Lorenz. Lorenz wrote:
“One meteorologist remarked that if the theory were correct, one flap of a sea gull’s wings would be enough to alter the course of the weather forever. The controversy has not yet been settled, but the most recent evidence seems to favor the sea gulls.” In other words, any tiny change in the known course of the past can change anything.
Stories based on the butterfly effect can be very entertaining, but they are usually full of logic holes. The most entertaining examples are to be found in the first two Back to the Future movies, in which every action in the romantic and sporting lives of the characters changes the timeline, over and over. Marty McFly and Doc Brown focus not on restoring the proper timeline, though (which would cause Doc Brown to be dead) but on creating one more favorable to them, with the right love affairs in place and the villains in the down position. They have no sense of the integrity of the timeline, or the effect of their changes upon people other than themselves, but are focused on self-preservation and their own betterment.
Another such story of seeking a favorable future is found in the first two Terminator movies. In The Terminator, the villainous killer robot tries to prevent a present outcome by killing someone in the past. In the sequel, Terminator 2: Judgment Day, this effort is repeated, but the second time around, the heroes use a pre-emptive strategy and try to prevent the creation of the killer robots in the first place. Illogically, they seemingly succeed, but the heroic killer robot is still around at the conclusion, when it should have been erased. While T2 is one of my favorite movies of all time, that is so only because I ignore the time paradox to focus on the character relationships and the action. The Terminator franchise gets dumb in the third movie in many ways (although somewhat redeemed by the chance to watch Kristanna Lokken in action) but its time travel aspect makes more sense than one might think. The good terminator explains, "Judgment Day is inevitable." This makes sense, because it, albeit only just barely, denies the possibility of a time paradox. Sorry, guys: you CAN'T change the future. Que sera, sera. Time can't be effed with. (As for the other two movies in the franchise, there is no time travel in the fourth, and the fifth, despite the compelling presence of Emilia Clarke, makes no goddamn sense at all, time-travel-wise.)
We are better off, in our time travel stories, if we assume that paradoxes are impossible. It just WILL work out. As an author, you can achieve this in two ways:
The most interesting is the classic Marvel Universe method. It says that time is linked to an infinitely expanding multiverse (complex of universes), and that when anyone time travels to the future, that time travel creates a new timeline. So if Captain America goes back in time and slays Adolf Hitler on a WWI battlefield, and then returns to his own time, he finds that where he comes from, nothing has changed. The Hitler he slew was a different Hitler, so though he may have prevented the Nazi regime in some universe, his own is the same as he remembers it being before he left.
Marvel sometimes tried to get around its own rules -- for example, stupidly using Mephisto, a Satan analogue, to erase Spider-Man's past -- but has also gotten great stories out of those rules. One Marvel movie does not follow the rules, which is X-Men: Days of Future Past. This is the superhero equivalent of Back to the Future II, letting the characters time-travel to create a more desirable future for themselves, with only a precious few who were involved recalling what happened before. Their efforts changed the world for the better.
The multiverse rule set makes for good stories involving parallel versions of characters, controlling authorities who can influence all the timelines, invasion from a parallel-universe stories, and more. It worked well for the original, printed Days of Future Past story as well as for the cross-time epic Avengers Forever.
If you aren't using the concept of a multiverse, then you have to go in a different direction to prevent paradoxes. I prefer this one for my own writing, and I think my best-selling colleague, Georgina Young-Ellis, does as well, although she is less explicit than I. According to this version, things just naturally work out so that whatever the time-traveler does, history doesn't change. The time-traveler's actions turn out to be part of the pattern of the universe all along. The prototype of this, for me, is a Robert Heinlein story called "By His Bootstraps," summarized at http://www.heinleinsociety.org/rah/works/shortstories/byhisbootstraps.html, in which a character repeatedly meets versions of himself.
In my first novel to involve time-travel, 2010's The Ghost in the Crystal, which is now in its revised second edition eBook, the story relies upon a stable chronology for the universe. My young hero has named himself Simon Magus, after the Biblical magician and villain. As a result, a ghost from that time period confuses him with the "real" Simon Magus. He then travels in time to occupy the role. In this way, events in 2001, when the book mainly take place, cause events nearly 2000 years before. Is our Simon the "real" Simon Magus? Probably not, but there may not be a real one, or there may be many. It all works out: Simon interacts with historical figures, but history doesn't change; rather, he was part of that story all along.
Georgina is a lot more subtle about these things. Her time-travelers do their utmost to avoid culturally contaminating their ancestors, or they are supposed to, at least. When they return, they find their actions reflected in the historical record, but there is no butterfly effect. Their timeline is entirely unchanged.
The same idea of time-travel can be found in one of the most well-known books of all time, J.K. Rowling's Harry Potter and the Prisoner of Azkaban. Hermione and the boys use the time-turner to revisit a scene of their failure and replay it, but when they do, their actions only create events that they remember the first time. Most notably, Harry's patronus charm, done on the second visit to the lake, is seen as a mysterious spell during his first visit. Nothing changed: the second visit explains, not changes, but the initial events. If you try to create a time paradox in this schema, it just doesn't work. You CANNOT kill your virginal grandparent, or a young Hitler. Something will prevent your actions. History will not change; no butterfly effect exists; you were always there; or, alternately, when you are about to do it, there is a snap and you are back in your original chronology.
I hope you enjoyed this quick survey of how time travel stories are constructed. If you did, please visit Amazon today and take a look at The Ghost in the Crystal, now in its second edition as I said earlier, with a new cover and several new sequences. It's magic in the real world, with a great cast of characters. I believe you will enjoy it even more than my essay.
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