The Terminator (1984)
The “happy” ending of this sequel-friendly movie is apparently a foregone conclusion. You know that Sarah Connor (Linda Hamilton) survives to give birth to future rebel leader John Connor, because he sends Reese (Michael Biehn) back in time to shield her from the high-tech birth-control device played by Arnold Schwarzenegger. So why does Reese come back at all?
The key to The Terminator is remembering that the timeline portrayed in the movie is not the original (A-B) sequence of events, but an altered (C-D) one. Instead of protecting Sarah so an undisclosed third party can impregnate her with the future rebel leader, Reese actually gets it on with Sarah and sires John Conner himself. Which muddies things a bit, since Reese would never have been sent back from the future if Sarah hadn’t gotten pregnant. But the fact that she does get pregnant would seem to preclude the necessity of sending him back—unless something happened in the original timeline to necessitate his risky voyage. In time-travel parlance, this temporal anomaly is called an N-jump. Does your brain hurt yet?
Back to the Future (1985)
The divergence of altered timelines spawned by time travel is clearly illustrated in this fun flick. Michael J. Fox stars as Marty McFly, a poor guitar-slinger who travels back to 1955 (points A and C) in a souped-up DeLorean to prevent its inventor from being shot. In doing so, he very nearly preempts his own existence by getting caught in a romantic triangle with his future father and mother. Happily, in spite of all his temporal tampering, he manages to get his future parents together (though not precisely as it happened in the A-B timeline), and when he returns to the moment in the future from which he originally left for the past (points B and D), he finds that everything is a little nicer, and Doc has survived the terrorist attack. Here’s the brain-bending part: If Marty (or someone else) hadn’t managed to get his parents together after disrupting their meeting, he never would have been born and so would not have been able to return to 1955 in Doc’s time machine to interfere with his parents meeting. Therefore he would have been born, so he can return from the future to mess things up. Time-travel theorists call this kind of anomaly an “infinity loop,” with both timelines repeating in an endless cycle.
Minority Report (2002)
According to one time-travel author, this Tom Cruise sci-fi thriller is one big rat’s nest of time-trapping “infinity loops.” The premise of the film is that future police are able to prevent violent crimes—particularly murders—from happening, thanks to a trio of psychics floating in a tank of amniotic liquid. The psychics receive fragmented visions of future crimes, which the police piece together with an advanced interface system and act on to arrest suspects before the foreseen events unfold. The “infinity loop” problem is this: If a murder does not take place, the images shouldn’t exist. So if the police prevent the murder, that should also prevent the psychics from seeing the images; if the psychics cannot see the images, the police have no warning and the murder cannot be prevented. Time cannot progress. See what happens when you start monkeying around with the future? When handled improperly, information can cause just as much damage as the cyborg assassins in the Terminator movies.
Kate and Leopold (2001)
Seriously, you could fill a book with time-travel conundra solely as depicted in the movies. But, as you’ve probably noticed, most movies involving time travel are more concerned with its humorous or dramatic consequences than with plausible physics. I mean, really—a DeLorean?
Still, the basic structure of some time-travel movies is supported by certain theories—but not by others. And at present, it’s all purely theoretical, and will remain so until someone actually figures out a workable way to stuff an experimental craft through a wormhole or squash a chunk of matter with 10 times the mass of the sun into an infinitely long piece of space-vermicelli that’s made to rotate several billion times per second.
But it’s fun to think about in the meantime, and Hollywood will continue to mine time-travel for the motherlode of appealing paradox that it is. With a little imagination, time travel can be co-opted and customized for almost any movie genre—including the romantic comedy.
Kate and Leopold stars Hugh Jackman as a 19th-century duke who falls through a fissure in the temporal fabric that occasionally opens under the Brooklyn Bridge, and Meg Ryan as the woman who chucks her advertising career to follow him back to the 1800s. The consequences of Meg Ryan loose in a time machine are too terrible to contemplate, but think about the scene with the Sta-Puft Marshmallow Man (“Choose the form of the Destructor”) from Ghostbusters as I leave you with this quote from Millenium author John Varley:
“Time travel is so dangerous it makes H-bombs seem like perfectly safe gifts for children and imbeciles. I mean, what’s the worst that can happen with a nuclear weapon? A few million people die: trivial. With time travel we can destroy the whole Universe, or so the theory goes.”
To which God replies: “If you’re going to play games like that, I’ll take my marbles and go home.”