Time Travel as a narrative device
Some thoughts on the nature of narrative time travel, that is the characters are able to travel to different points in the timeline, not the narrative focus.
As I see it, there are 4 or 5 different situations with time travel:
1. Time travel is not possible, or only possible in one direction - forward. This is either a normal real-time movie or may involve some form of stasis, but you can't go back. Ever.
2. Time travel only works through dimensional shifting (e.g. Sliders, Crighton's Timeline) - you transfer from one universe to another universe that happens to be X time units ahead or behind you. An odd version, to be sure, but this means that causality isn't inherently at play - you can do X without concern of unmaking yourself because you can always go home. Now, doing X may be a repetition of X happening in the original timeline long ago, but that's parity, not causality.
3. Time travel works within your own timestream but nothing changes. You always traveled to the past and you always will travel to the past, you will always do/have done exactly the same things and thus will never achieve a paradox. If you attempt to kill your grandfather, you will not succeed. (Wrong person, killed too late, somehow prevented from succeeding). You can't kill Hitler because you didn't kill Hitler before. This is good for a twist, I suppose, lots of drama about possibly changing the future and then... boom, doesn't happen.
4. Time travel is possible within your own timeline and paradoxes are possible. Two subtypes:
A. Single timeline, unmaking yourself is a real danger. (e.g. BTTF, Quantum Leap). This forces you into a Type 2 as a consequence or at least into a state with minimal changes.
B. Spoke timeline, where your arrival into the past didn't happen previously and now you're in a new continuity. Either it overwrites the original timeline or just works in parallel, but either way you cannot return to your original timeline unless you fix any deviations. (BTTF II)
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One idea I've heard is that "if time travel ever is invented, it will eventually cancel out its own existence", which leads me to the idea that a 4A can lead to a type 3, where the time travel causes a disruption in the timeline and the resulting paradoxes, and then finds a new equilibrium for balance. We actually saw something like that in BTTF - the initial timejump is unprecedented, but we later see that despite all the changes, the timejump still occurs in the altered timeline. Things may be different (the 2nd Marty may not realize there ever was a "Two Pines Mall" instead of a "Lone Pine Mall", because from his perspective, that's how things always were.
So, say you go back and invoke the grandfather paradox in a 4A, which unmakes you, which cancels the grandfather paradox, but then it loops. Instead of it being identical, small changes are introduced each cycle, perhaps the traveler emerges in a different spot, until a stable cycle is achieved.
Also, narratively, there's the concept of consecutive timelines. (e.g. Terminator, Primer), sort of like a 4A but without the grandfather paradox. Timeline A inspires Timeline B, which still has time travel but different starting parameters so it inspires Timeline C, and so on. Primer has about 7 or 8 timelines all working on top of each other and that's one explanation for how the Terminator franchise has more movies - each movie changes the past which causes the Man/Machine war to proceed differently. The first time they send a single Terminator, then when that didn't work, they send two. Then they send three. Then they change the target dates. Then a Type 2 occurs with a dimensional traveler (Matt Smith) and things go to hell.
The main problem with that, I suppose, is that it would be difficult to write from scratch, as you'd have to plan out X number of timelines and their interactions leading to your target story, or just let the story evolve over time.
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Qualities
- One driving nature of Time Travel movies deals with how usable the jump mechanism is.
- Is it 1-way? - once in the past (or future) you can't jump back (Terminator, 7 Days)
- Is it easy? - can one travel at any time to any time? Issues are more about how to effect changes or rescue people without disrupting the timestream (Doctor Who, BTTF II, Bill and Ted's Excellent Adventure)
- Is the time machine portable? - The BTTF delorean, for example, is mobile while the TimeCop mechanism is a giant facility. Course, this would only apply if you need the original time machine for an exit jump.
- Is it the same spot? - are you restricted to just one location? (H.G. Wells Time Machine wasn't, but the BTTF Delorean and Dr. Who's Tardis is. Not sure how to classify 7 Day's sphere, but at least it mentions the concept of orbital drift)
- Is the time connection fixed? - Point A at B time only connects to Point C at D time, you can't change it. One example of that is the Time Scouts novels.
- Is it reliant on another time? - does a chrononaut rely on a device at another point in time to travel? Like TimeCop - the travel device is in the future and the chrononaut is remotely recovered, but that requires maintaining the original departure equipment, change the wrong thing and you cannot go home.
Past Influence characteristics:
- Does the future version replace the past version? (e.g. Seven Days), which handily avoids any paradox issues such as being in two places at once and keeps things simple. Definitely type 4B.
- Does interacting with your past self disrupt causality? Variations can include either a major temporal paradox or, in the form of TimeCop, mutual annihilation, which leads to its own causality impact.
- Are there multiple layers at work? See above
Future alterations
- Are the future alterations avoidable - either they are delayed or one can be specifically isolated from any alterations. So, for example, you could unmake your nemesis and then go and enjoy the timeline without their interference. Also allows for temporal police to detect and respond to alterations. The Journeyman Project and BTTF II have the idea of jumping over an inbound alteration, you're not affected by the change (at least not right away) as it never touched you.
- Are the future alterations delayed or instantaneous - if you make a change, do things IMMEDIATELY shift. Examples include Frequency and multiple episodes of Quantum Leap. (a chrononaut has a future advisor, until he changes the past and the advisor changes to a completely different person)
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Time travel motivations.
Drama comes from complications. BTTF is about correcting mistakes because of causality and just pure unpleasantness, along with issues of being stranded. 7 Days avoids issues of causality but replaces it with time-jump constraints - only 7 days so how much intelligence can you gather before you nullify your ability to make a change?
1. Accidental. You didn't know you'd be traveling, you are unprepared and may not even realize what sort of rules you're dealing with.
2. Experimental. You know you'll be traveling, but encounter a variable you didn't anticipate or things just plain go awry.
3. Policing. You're only there to maintain the timeline, not bend it to your will. This would require detecting and then responding to changes, not pre-emptive moves, as sentry agents could alter the very timeline they seek to maintain
4. Historical. You're there to solve mysteries of the past, maybe gain historical lore. Incredibly dangerous, this should only be attempted if you are sure you either can't or won't alter things. (so if you want to research Pompeii, the day before the volcano erupts may be the best time as few things would survive the blast). Can also overlap with tourism.
5. Crime/Vigilantism. The Lets Kill Hitler example, you go to the past to make a change, either to invoke specific consequences (like giving a past self a sports almanac) or change a specific event, consequences be damned (Kill Hitler to stop the Holocaust.)
Long post I know, but any thoughts?
Jake Meridius Conhale, at your service!
"Old Man" of the BSG (RDM) boards.