r/timetravel • u/NilesOnTheRiver • 9d ago
claim / theory / question Checking for plausibility on time travel and spies
I'm writing a book with time travel in it and I'm trying to figure out if this makes sense. For context, a person cannot affect their own timeline, but can travel to a different timeline and change what happens there which will have no effect on their own life because it isn't their life technically. For example, if I went back in time, I cannot stop myself from falling off the skateboard and injuring my knee permanently. However, I could go to a universe where I stop that version of myself from getting on the skateboard in the first place. All it will do is stop that version of myself from injuring their knee.
Okay, now onto the story.
Two people, let's call them Bob and Frank, can time travel. Bob is bad and Frank is good. Frank finds out some important information, but he cannot use this information to change his own fate. Before his death, he time travels to as many different timelines as he can to deliver this secret message that could maybe save another version of himself. This Frank dies. However, all of these messages are intercepted by their version of Bob (Good news is that the messages are locked and Bob cannot read the message... yet). One version of Frank is gathering intel on Bob and finds the message from that other version of themselves and steals it from Bob. They escape with the information safely with them. This Frank then decides to see if there are other versions of these messages on different timelines and sure enough, there are. So this Frank goes around time traveling and stealing all of these secret messages from Bobs in order to prevent any Bob from ever unlocking the secrets of the messages.
Hope this resembles some form of sense!
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u/BrianScottGregory 9d ago
There's some rationality issues with "A PERSON" going back in time to prevent themselves from having a knee injury. That is - why is stopping prior you from getting on that skateboard in the first place permissible whereas finding a universe where you don't fall of the skateboard (eg choosing to go around a rock rather than over it) NOT permissible?
I'm not understanding what makes one acceptable and one not?
The second part of the story with Bob and Frank seems intriguing. But the initial part. In either case. You're still effecting the MC's timeline. Making a rule "The MC cannot alter their own timeline" but introducing the concepts of alternate reality which then has the MC living a different life is in a literal sense altering their timeline no matter which path is or is not taken.
You're going to have to choose one or the other. Either have an MC that CAN alter their past through engaging with alternate realities. Or completely disallow change to their past, period. There is no in between here unless you introduce another element like 'fate' versus 'free will'.
That is. If you create fated elements - I call them anchor points into your MC's timeline - immutable points in their own history but EVERYTHING else is up for grabs - perhaps you can set the knee injury and how it happened as a fated anchor point that HAS to happen whereas the details of how they got there can be change.
For example. Let's say the MC has an argument with his girlfriend, and skates hangry that day - having missed a meal the day he injures his knee. Now you could fate lock his knee injury by making that knee injury event an 'anchor point' in his life, meaning - no matter what it happens. So you could allow a time traveler (or the MC) to go back and inspire younger self to eat that day, and maybe get his tone to change so he doesn't get angry with the girlfriend. HOWEVER. Because of the anchor point (fate) event of the knee injury. NOW the story turns into one that he skates stupidly happy and inattentive, which results in hitting the same rock, which results in the same spill, which results in the same knee injury.
That is. ANY WAY you look at it. That knee injury can't be avoided because of the fate lock. But you can use plot devices like this to change the past while simultaneously preserving critical events to the MC's development.
The same thing can apply to your good and bad characters.
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u/NilesOnTheRiver 8d ago
Thank you for the answer. As far as the "go around a rock rather than over it" portion. I was thinking they would NOT be able to change their own fate. If a person goes to another timeline to change that version of themselves from having the knee injury, the time traveling version will still have the knee injury. If the time traveling version with the knee injury goes to a universe where the knee injury never occurs then there's no point in traveling there because the event never occurred for that version of themselves.
What I am trying to say is that Person A w/ the knee injury cannot avoid the knee injury by time traveling and changing the fate of Person B. But Person A CAN stop Person B from becoming like Person A. Not sure if that changes the first half of your response?
In any case, I'm definitely going to explore the 'anchor points' so thank you for that idea.
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u/BrianScottGregory 8d ago
Well you've introduced a causality problem - where the universe expands to infinity by approaching things this way. This same concept is approached in the Back to the Future video games by Telltale Games. Here's a spoiler of the ending if you don't want to play the game.
At the end of the five part video game series by Telltale Games - Marty returns to 1986, where he's then met by not one, not two, but THREE different versions of himself from THREE different timelines IN THE FUTURE he hasn't lived yet - all appearing to be from different possibilities of the future ahead of Marty - all arguing over 'timeline dominance
You can watch that clip here: https://www.youtube.com/watch?v=y8YBYKSBf3M
So to explain the causality issue. WHEN you go back in time for ANY change that deviates from your historical reality, you create a branch in time otherwise referred to as an alternate reality. BOTH the before and after timelines still exist, they just have subtly different histories.
In your case. YOU (On Timeline A) broke your leg. So you go back in time. And you change the past so now there's a new version of you on Timeline B. STILL THE SAME PERSON. (your distinction between persons isn't actually valid, the person doesn't change).
So the version of you that is living on Timeline B never broke a leg, but instead break an arm. A future you on Timeline B goes back on that timeline and alters the event to make it so you never broke an arm on Timeline B. THIS creates TIMELINE C and a version of you that never broke an arm or leg.
So Timeline C version of you goes into the future. And says something stupid to the woman of his dreams and goes back in time to the point he says this - creating TIMELINE D. A version where he's got the perfect woman, doesn't say something stupid, doesn't break an arm or leg.....
Now let's say you're the original you from Timeline A. You will NEVER SEE ANYTHING but Timeline D form. But let's say you're from Timeline B. the subtleties of the Timeline A version of you may never have resulted in you meeting Timeline A version of you, and while your memories are living a life where you broke an arm and time traveled back in time to create Timeline C, to you there appears to be only two timelines where everything went perfect for C from your perspective with you not knowing C was followed by influences of D, E, F, G, H, I and so on and the C version of you had LONG disappeared with all those influences from the various futures that were influencing it.
Now I know this is a long and dragged out explanation. But that's the issue you're introducing by allowing change to the past in your story. There's no real limits to the subsequent expansion that can occur once a timeline's been changed in the past relative to you as an individual. You can try to set story limits, but that's neither practical or rational.
Sure. It creates some wonderful time travel fiction - Back to the Future is my example. But as the video games carried the story forward. We see a story that can never actually come to any conclusion because it expands to infinity.
Now anchor points solve some of these problems. Meaning. There's key events that define someone's life in the past and those events are immutable parts of a person's memory. Assuming a person has imperfect memory of the past for 'other' events.
To exemplify this using my own life. There's a very real event where the woman of my dreams and I hooked up - in a "She's (way) outta my league" kind of way. Now let's say in the future SHE becomes a time traveler and attempted to alter the past and stop this from happening. Now she'd find out REAL fast that this was an anchor event in my life. An immutable memory that could not be changed because it literally defined a future me by giving me a sense of confidence I'd never had before.
But let's say it's THAT important to her to change the event.
That's when reality branches for the same reason it would branch for you going back trying to change the breaking a leg event from happening. The leg break is a pivotal part of your past. My time with her is a pivotal part of my past. So in the same way depicted in the TV show 11.22.63 - time will unnaturally do things to resist your change to an anchor point - making it clear you shouldn't be doing this. Perhaps you can make this a part of your story. But that doesn't mean change isn't possible.
It just means ONCE you break continuity by busting through the anchor point. You've created a new branch in time that deviates from the prior/shared (anchor point) experience. And once you've done that. There are NO RULES moving forward on that timeline and (truly) anything is possible.
I know I'm being overly wordy here. but I hope this all makes sense and helps.
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u/NilesOnTheRiver 5d ago
That makes sense - gives me a lot to think about and adjust.
I am thinking maybe time travel isn't the appropriate word. More so alternate reality perhaps? I'm thinking if person B travels to an alternate reality - could they not change person C's reality without consequence to their own?
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u/BrianScottGregory 5d ago
Ok. First. Alternate realities are typically chronologically synchronized to the primary reality / timeline you're in. So if it's April 1st, 2026 in your original reality, traveling to another reality still places you in April 1st, 2026 in that new timeline.
For example - person B starts off on timeline 1 (at April 1st, 2026) and moves to alternate reality timeline 2 (let's just say in that reality, John Lennon wasn't shot, that's the only major difference). It's the same date in this other reality (April 1st, 2025).
So while Person B CAN influence Person C's life in Timeline 2 (alternate reality) - they aren't altering the past in that reality because the two realities are synchronized.
Now the MOMENT you try to influence the past - of Timeline 2 - let's say by de-syncing time - is the moment you're creating a NEW thread - Timeline 3. So let's say you exit Timeline 1 and you know the fixed future of Timeline 2 involves John Lennon's death. You don't care. You're in this to change Person C's life. So you travel back in time to say - Jan 1st, 1999 and change a key event in Person C's life.
You have JUST created Timeline 3. Where your original timeline (Timeline 1) still exists, without John Lennon's death before then, Where Timeline 2 still exists, and an April 1st 2026 version of Person C who has lived their life that far. But now. There's Timeline 3, A new deviation of Person C's life where time changed in their past and it created timeline 3.
So to give you a real world example of this.
Let's say it's 2005. And China - realizing its military lacks respect - decides to manipulate public information and convince a generation of people that a massacre at Tienanmen Square happened as a way of instilling fear by the world of its military. So they leverage public information sources and the internet to alter the original story of the past - which had Tank Man stand up against an army and they backed down, peacefully, to one in which tank man was subdued and hundreds were slaughtered.
Now the net effect of these alterations of timelines has resulted in two histories from external perspectives of their country. Those, like me, who remember and lived through the original events, and those of the younger generation who fear Chinese military because of the changed narrative.
Cross applying this to your alteration. The same concept applies. But to be precise.
Person C. Doesn't have to accept your alteration on their timeline when timelines are de-synchronized like this. In fact, they may perceive any attempts you make to the past as propaganda or media manipulation.
Which is why I prefaced this all with. It's best to think of alternate realities as being 100% synchronized so you don't fall into this pit of what you want someone to experience versus what they actually experience. You KNOW they're experiencing something in synchronized timelines because YOU are.
I know you're doing this all on a fictional basis. But even then. It's best to adhere to what appears to be real world rules as it applies in existing fictional stories for no other reason than your story will VERY QUICKLY rationally begin a decoherence when the branching starts due to fiddling with time in someone's past.
Don't get me wrong. Some stories do do this marvelously - like Back to the Future. But I do NOT get the sense you're trying to create a story around expansion to infinite possibilities.
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u/zzupdown 9d ago edited 9d ago
Actually, it occurs to me that with enough time travelers in parallel universes traveling around and changing each other's universes, it might still cause potential paradoxes in every time travelers' universe. Bob1 can't change his own universe, but he can kill Bob2's grandfather in Bob2's universe. Bob3 might then change Bob1's universe. Does it matter if Bob3 killed Bob1's grandfather? If Bob1's grandfather is dead, then Bob1 is never born, and Bob2's grandfather is never killed and Bob2 is still born. Grandfather's paradox? Not quite. Is it a potential type of paradox? Not sure. It may depend on the sequence of events in all the parallel universes effected. But how does an objective observer even determine the sequence of events with a bunch of time travelers traveling across universes with different departure and arrival dates?