broken arrow of time: the three flavors of time travel (part 1 of 2)

Recently, watching Looper, I knew something was wrong. I just didn’t quite know what.

Looper is better than your average time-travel movie, or even thriller. Joseph Gordon-Levitt, creatively named ‘Joe,’ is the titular looper, a kind of hit man in the future who specializes in killing people sent back from the even-more distant future.

The ridiculousness actually peaks early in the movie. Joe’s friend Seth, also a looper, chokes when the person sent back in time to be killed is a future version of himself. Future Seth gets loose and goes on the run, causing both him and present-day Seth great difficulties; apparently, letting your victim get away is a real no-no in the syndicate that Seth and Joe work for.

Here’s where the time travel gets goofy. To arrange a meeting with future Seth, the syndicate carves an address into current Seth’s arm — which appears in the arm of future Seth right before his eyes. Watching this scene, I knew immediately and instinctively that this kind of thing was bogus, but I had never sat down before to work out how exactly. This is what I figured out.

the big question

To figure out what kind of time travel movie you’re watching, ideally you only need to deduce how the filmmakers have chosen to answer a single famous question: If you go back in time, what’s to stop you from killing your grandfather before he impregnates your grandmother with your father or mother?

If it’s not abundantly clear, the reason the question is so important is that by killing your grandfather at that point, you would make it impossible for you to exist. Which would not be such a big deal in the scheme of things, except that you would not then be able to go back and kill your grandfather.

photo by Kaptain Kobold

(I suspect the reason that the canonical example of the paradox here involves killing your grandfather and not your father is that your grandfather is a little more distant both genetically and probably emotionally, whereas just thinking about killing your father draws up all kinds of icky oedipal stuff no one wants to think about. Similarly, killing your grandmother somehow seems relatively more barbaric than killing your grandfather, and of course, no one wants to kill their mother. So grandpa drew the short straw on this one.)

I hesitate to retread the issue of time travel — the grandfather paradox has been around for decades — but I have a particular love of simple rubrics that clarify a problem, and mainstream movies are still perpetrating nonsense. So herewith are my three flavors of time travel: closed loop, open loop, and continuous-ridiculous.

closed loop

I thought I made this term up, but no, I was scooped again by the rest of humanity. If time travel occurs in a closed loop (or if the filmmaker has constructed the universe of the film that way), and if you return to the past with the intention of offing your ancestors, you will inevitably fail. It may be for whatever reason: You slip on a banana peel, you chicken out, whatever. It can’t happen, though, because, well, it didn’t happen. If it had, you wouldn’t be around to even attempt it, so it didn’t happen.

Closed loop time travel has implications that are not terribly intuitive but, like other great paradoxes, logical. For instance, it may turn out that not only did you not kill your grandfather, but that you were integral in saving him from some deadly event that would have precluded your own existence. Let’s say you go back in time to meet your young grandfather and compare muscle tone with him. For this to work, we should just assume this is some point prior to him making your own existence possible, like probably before he made the baby that became your parent.

photo by kevin dooley

Anyway, as he’s preening for you, he has a heart attack that almost kills him. He might have been alone, but you were there to rush him to the hospital. You save his life, and it’s clear he would not have survived had it not been for you. You might even recall that the gramps you knew growing up had mentioned that a mysterious, very good-looking stranger had saved him when he had that heart attack.

So by traveling back in time, you’ve just saved your grandfather, and by extension, perhaps yourself. But, um, huh?

This is what’s great about a paradox: It seems like something fishy is going on, but the logic holds. The most unlikely part of the paradox is that, at the moment you arrived in the past, your time travel pod suddenly appeared out of nowhere. ‘But it came from the future!’ you might object. Nope. Remember, at this point in the past time travel hasn’t been invented yet, so there’s nowhere for this pod to have come from. So whatever the consequences of that time machine appearing will have already been factored into the future in which it’s possible to send a time machine back.

The big implication here is that there’s no free will in this kind of time travel, since everything has already happened that would have happened in any past you travel to. In other words: You will travel to the past because you already have.

I’ll continue this post on Friday by explaining “open loop” and “continuous-ridiculous” time travel, and I’ll also give some suggestions to potential time travelers.

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