How Do You Think Time-Travel Works?

[killercactus]

WARNING: RANDOM MUSINGS AHEAD!!

I've always been emphatuated with stories that use Time-Travel. It's just so... cool to me. However, most stories have their own take on how it works since it's a concept that hasn't been used in the real world. I like to try and think logically about how Time-Travel should work, and I have an upcoming project in which I want to use Time-Travel, and have to decide on a method I want to follow. So, I thought I'd post here and get some opinions.

Here are the methods I've seen. I'm considering each of them, or some new one that makes sense.

1) You Can't Change Time (Harry Potter and the Prisoner of Azkaban)

This version of time-travel might be the simplest version. It basically says that there is only one timeline, and everything will happen the same way on that timeline regardless of who time-travels. For example, assume I went back to 1963 today and helped assassinate John F. Kennedy. By this theory, I already existed in 1963 and have already helped assassinate him, even before I decided to go back in time. So, my time-travel doesn't change what previously happened. The best I've seen this illustrated is in the third Harry Potter book, where Harry and Hermoine go back in time 2 hours to save a condemned animal and Harry's godfather, only to realize that the animal never actually died in the first place because they were originally there to save it. Stories like the Terminator saga are like this too - people go back in time to change what happens in the future only to find out that their actions help cause the future events they're trying to change.

2) Time is a Pretzel (Kate & Leopold)

This theory, on the surface, seems just like You Can't Change Time. In fact, it might even be the same, except that in those stories above, we don't know what happens when someone that travels into the future. In the Pretzel theory though, when someone travels into the future, they disappear from existence from the time they left until the time they arrive. However, if they then travel back to the past, the timeline can be restored. Lastly, travelers that go back in time were actually always there, except when they were traveling to the future.

Confused yet? Well, in Kate & Leopold, Leopold was an Englishman (I think...) who was responsible for inventing the elevator. He accidentally is thrown into the future by a portal. When he gets there, it can be seen that all elevators stop functioning (because their inventor has been gone from existence), though they don't disappear entirely as you might think they should. Leopold falls in love with Kate, but eventually decides to return to his own time through the same portal. As he is returning, a scientist friend of Kate's looks at a picture Leopold gave him from the past and sees Kate there, signifying that Kate will go back to the past after Leopold, and that in fact, she has already existed in the past. Kate follows into the portal and the scene from the picture comes to pass. So here, the timeline actually does change slightly, as the elevators start working again once Leopold returns. It's like the timeline "bends, but doesn't break", or one could say it twists around like a pretzel.

3) Time is Brittle, and Paradoxes Could Screw You Over (Back to the Future)

This theory says that if you go back in time, you can actually change the timeline and your actions, even if insiginificant, can cause serious ripples through time. Also, the Grandfather Paradox exists, which means if you go back to the past and change history to prevent a future event that caused you to go back in the first place, time can be damaged and/or people can cease to exist. The best example I can think of is the Back to the Future series, where Doc and Marty regularly go back in time and change things, which have major implications on future events. Doc describes the timeline as skewing off onto tangents at each point a time-traveler changes something, creating a new timeline each time. The future is oblivious to the time changes, and time-travelers have to be very careful they don't cause any paradoxes, though we don't actually know what happens if a paradox occurs.

4) Time is Brittle, and Time-Travelers are Immune (Chrono Trigger)

The last theory I've looked at is the same as #3, except the Grandfather Paradox is avoided entirely thanks to something unofficially dubbed Time-Travelers' Immunity. This means that, if I travel to 1940 and kill my grandfather, I will not cease to exist in 1940 even though I'll never be born in 1981. I would just continue to exist in 1940 as a being from another timeline. As soon as I arrive in 1940, the old timeline in which I was born in 1981 is discarded and replaced with a new timeline, in which I'm in 1940 and my grandfather is dead. Also, time-travelers who departed from discarded timelines will appear in new timelines. For example, say I leave today and travel to 2025. After I get there I decide to travel back to 1940 and kill my grandfather. Even though, in the new timeline, I'm never born in 1981 and never travel to the future in 2009, the version of me from the old timeline will appear in the new 2025, thanks to Time-Travelers Immunity. This theory was used in Chrono Trigger (a video game for the SNES) and was used as a major plot device.

5) Multiple Dimensions (??? Chrono Cross?)

This theory is the same as #4, except instead of just discarding the timeline, each different timeline exists simultaneously in a different dimension. Chrono Cross (the sequel to Trigger) seems to use this, but what really happens in the game remains unclear.

So, what do you think?

[Grungebob]

Number 5

[arp12]

Fascinating subject... where's the poll? I'd say probably #1.

[rednax]

Coming from another HP fan, I've got to say #1.*








*Not as big a fan of Runa

[Bonecrusher]

I think #4.

[Toad Rocket]

I would say the first one would be the easiest to understand in term of time travel. However, if that is true and we cannot change time it would suggest that we live on predestined paths of our lives and nothing we can do will change our own destiny. This nullifies the idea of free will/choice because whatever we think we are choosing has been predestined from the beginning of time. So then we would be racing along on our life path, doing actions that were preordained by time itself.

I like number five also, but then your not really time travelling. You are travellling to different dimensions and what you do in that dimension will have no bearing what so ever on your orginal dimension.

The problem with Time Travels immunity is that it creates a paradoxal loop of impossiblity. Using your example, being born in 1981 you travel back intime to 1940 and off your grandfather (at least you didnt pull a futurama and become your own grandfather,icky).
The paradox is that if you killed your grandfather then you can not be born in 1981 and then grow up to kill your grandfather, so then you really didnt kill him? If you did kill him and continue to exist them you would slip into an alternate dimension (#5) and that is whole nother ball of wax. Time Traveller doesnt really makes sense. What if, after killing your grandfather you travel back to 2009, would you cease to excise because your in the timeline were the death of you grandfather would affect you. But if we are talking timelines are you then jumping from line to line on different strands of time? So would that not be differnt dimensions?

[ProtoFury]

Heh well I love time travel things... In fct, I even wachedan hour of Star Trek (whatever the ones from like the 90's were) after watching one of my shows, just because i had a whole time-travel theme. In it, the captain (Bacard or something?) had his consciousness flipping back and forth in btween three times--present, past, and future versions of himself. They were all in one timeline, however, and he had been told by some "Q" guy that he was going to bring about the end of mankind. In the present, he and his crew found some huge like explosion-looking anomaly, and so he went to that place in the future and past too to analyze it in the other times. It was twice the size in the past, and wasn't there at all in the future. One of the crew gus in the future decided to use some kind of beam (sorry, I know nothing about Star Trek past the new movie), and so when Bacard flipped back into theother two times, he had them scan the same point in space with the same kid of beam.

Then this Q guy shows up again and tkes Bacard to the past, wher life originally formed on earth. That huge anomaly took up our "whole quadrant of the galaxy", and becuse of it, life didn't form. Turned out that because he scanned with that beam at the same spot in three points in time at the same point in space, he caused an "anti-time" explosion, that expanded slowly, backwards in time. He ended up flitting between all three times and geting them al to fix it, but it was all still in their same timeline. As nerdy as it was, I couldn't resist the draw of the time travel aspect.

I would have to agree with the theory proposed in this episode--or something similar. I would say that I would think of one different than your listed theories. One where there is one timeline, but it can be altered. That when people go back, thy may shape evnts that caused them to do so in the first place, but they can also change the course of time.

[Xn F M]

Originally Posted by Toad Rocket

I would say the first one would be the easiest to understand in term of time travel. However, if that is true and we cannot change time it would suggest that we live on predestined paths of our lives and nothing we can do will change our own destiny. This nullifies the idea of free will/choice because whatever we think we are choosing has been predestined from the beginning of time. So then we would be racing along on our life path, doing actions that were preordained by time itself.

Some of us don't have a problem with that. I'd argue that free will is an illusion anyway. #1 All the way.

[Quintaton16]

Originally Posted by Toad Rocket

I would say the first one would be the easiest to understand in term of time travel. However, if that is true and we cannot change time it would suggest that we live on predestined paths of our lives and nothing we can do will change our own destiny. This nullifies the idea of free will/choice because whatever we think we are choosing has been predestined from the beginning of time. So then we would be racing along on our life path, doing actions that were preordained by time itself.

I like number 1, and I disagree with you here. It does not mean that we don't get a choice at all, it just means that it's a one-shot deal. You can't screw something up and the go into the past to make it better. Rather if you screw something up, it is a result of the further bad choice to go back into the past and try to change it. So our future choices can affect our past choices, just not nullify them.

What I think your argument stems from is the idea that if, say, Hermione and Harry had decided not to go into the past and save Buckbeak, then he would have been all right anyway because he would have been saved by people who ended up never coming to save him. Since you think that can't happen, you conclude that they were forced to go into the past by their own actions. This is where I disagree. If they had not traveled through time, Buckbeak would have died in the past, but Harry and Hermione at the time of his death would have been no different. The past cannot be changed, because it is already affected by the choices we make in the future.

This perception is a little weird, so I actually think 1 is the hardest to wrap one's mind around. It sort of concludes that time is linear and only one timeline exists, but at the same time, future events can influence past events.

[H4XGD]

#5 makes for more...involved stories, and #3 is the one I'd take out of any of them.

[ABOMINATION]

Time travel is impossible, as time does not flow like a river. You can't paddle back. Therefore, the point is moot and there is no further talking about it.


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D'oh, what the heck. I'd go with #3 simply because I love the Back to the Future series. Never can get tired of them; they're too darned funny.

[ProtoFury]

Originally Posted by ABOMINATION

Time travel is impossible, as time does not flow like a river. You can't paddle back. Therefore, the point is moot and there is no further talking about it.

I don't think we'll be ever able to manipulate time, but you make be interested in this. Wait till you get to the fourth dimensions and suff, the stuff about time. The whole video itself will blow your mind.