“Back to the Future” celebrated its 30th birthday earlier this month – or so they claim. Time is always a little elastic when it comes to this movie. Thirty years is the amount of time Marty McFly travels in the first film, from 1985 to 1955, inadvertently messing things up for his parents and putting his own existence in jeopardy. And it’s the amount of time that Biff Tannen travels in the second film, from 2015 – yes, 2015! – to 1985, in order to take over Hill Valley. The idea that “Back to the Future” was not released in 1985 at all, but put there by time-travelling movie executives eager to plant the idea of a four-quadrant summer hit—a movie, that is, which appeals to Marty McFly, his sister and both parents—in our collective movie-going subconscious cannot easily be discounted.
The plot of Robert Zemeckis’s film – the result of a three-year writing spell with his writing partner Bob Gale – remains a model of what the Pixar people call “simplexity”: a mixture of complexity and simplicity, intricacy and ergonomic craft. It’s a Fabergé egg of clockwork plotting. But time travel remains an elusive grail for Hollywood, with “X-Men: Days of Future Past”, “Looper”, “In Time”, “Edge of Tomorrow” and “Terminator Genisys” just the most recent attempts to stretch time, space and credulity in search of answers to the big questions. If someone cuts off one of your past self’s fingers do you suddenly become an amputee? Is it true that you can only travel through time naked? What happens if you touch your past or future self? And if you impregnate your mother, become your own father and then divorce, do you have to pay for childcare?
There are two schools of thought on these matters. The first we’ll call the Sarah Connor Theory, after the heroine of the “Terminator” movies. At the end of James Cameron’s original “Terminator” (1984) she declares that, “There’s no fate but what we make,” after defending herself from an assassin sent back from the future to kill her and her unborn son. According to this theory, history’s timeline is relative and mutable. You can go back and change the past, and the future (relative to wherever you happen to be) is as yet unwritten. This is the basic working model of much classic sci-fi, including H.G. Wells’s “The Time Machine” and Ray Bradbury’s short story “A Sound of Thunder”, in which a time traveller steps on a butterfly in the Jurassic era, and returns to find humans spelling words differently, having elected a different leader. (In the movie version, humans have devolved into flying monkeys.)
It is also the theory beloved of Hollywood screenwriters. At the end of “It’s a Wonderful Life” (1946), for example, James Stewart is shown alternate visions of his past and future, and, realising his importance, hunkers down for Christmas with his family. To be self-determining, a master of one’s own fate, is the rock on which America’s manifest destiny is founded. In “Back to the Future” Marty not only reunites his parents in high school, thus ensuring his own birth, but gives his father a little pep talk which turns him into a bestselling author with the money to buy his son a brand new Toyota. “If you put your mind to it, you can accomplish anything,” Marty tells him, not only echoing Sarah Connor’s credo but suggesting the way in which time travel, especially in movies from the go-getting 1980s, seems to exist as an adjunct to the self-improvement industry.
There is a logical objection to this theory, though, and it is this: if Marty McFly ceases to exist, there will be no-one in the future to come back and mess things up for his parents in the first place. Ergo, he will turn out to exist after all. As Marty once put it, “Talk about déjà vu!” The response of many storytellers to this objection is to appeal to the “many worlds” interpretation of quantum mechanics: Marty’s interference would result not in the obliteration of his future self, but in alternate universes. In one, he is indeed rubbed out; but in another he is left alive and well. This was the theory, certainly, put forward by Doc Brown in “Back to the Future Part II”, which juggled alternate versions of 1955, 1985 and 2015, creating, as Doc Brown put it, “a new temporal event sequence resulting in this alternate reality!” The result was what is known in the scientific community as a God-awful mess.
The second school of thought on time travel has things differently. By this theory, the timeline of history is singular, absolute and immutable. Any attempt to go back and change the past must and will fail, possibly bringing about the event you were trying to stop. We’ll call it the Bruce Willis Time Loop, after the doomed character he plays in “12 Monkeys”, an adaptation of Chris Marker’s 1962 film “La Jetée”. The protagonist, haunted by visions of a dying man, goes back in time, only to realise that the death he has been foreseeing is his own. “He realised there was no escape out of time,” says the narrator, “and that that moment he'd been granted to see as a child, and that had obsessed him forever after...was the moment of his own death.”
The important element here is that the time-traveller essentially changes nothing. Rather, any changes he thinks he has made are already woven into the fate he has been unable to see. This is the type of ending much beloved by writers of the European arthouse and Greek tragedy. Sophocles’ “Oedipus Rex” features a similar self-fulfilling prophecy. This theory, though, also has a logical objection. As Thomas Aquinas put it in “Summa Theologia”, “there is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible.”
Since both theories contain their own inherent design flaws, it is not unheard of for writers to put both on a simmer, and hop back and forth between them as and when they threaten to boil over. “12 Monkeys” makes you think it is a make-your-own-fate time-travel plot, only to reveal itself as a no-escape-from-immutable-time plot at the last minute. The 2006 Denzel Washington thriller “Déjà Vu” does the opposite, arguing that time is immutable before allowing that change is possible. “No time-travel movie makes sense, if you look at it hard,” Looper’s director, Rian Johnson, once admitted. Maybe that’s what makes them such a beguiling grail.