The role of interference and fate in time travel.

One thing that fascinated me about The Time Traveler's Wife was that it was the first time travel story I've read which was working from the theory that everything that happens is set in stone - nothing you do will change anything. That seemed new to me... Most time travel stories work from the opposite concept: Don't wave at President Lincoln, you will change the course of history! Gah!

So how do people feel about the issue? Do you think people traveling through time would change history with the slightest, unintentional act? Or can we trample through time and have no effect because fate has set history in stone? Or something in between the two ideas? What do you enjoy reading/exploring?

My own personal views fall somewhere in the middle. I think we could change things - perhaps on what would seem like a large level to us (effecting several generations) - and yet, I believe the Universe (and human nature) works in rhythms and larger trends would come back round to their original path eventually.

Kage Baker follows the same principle in her novels of the Company: you cannot change recorded history. So all their agents in the past do things that fall outside the areas of observed history.

If time travel were actually possible, some new physical principle would need to turn up to prevent the mere appearance of a time machine from changing history. The universe is governed by quantum mechanics, and chaos theory shows us that even small perturbations become huge over time.

That kind of realism in a time travel story means you can never go home once you go back in time, though, which isn't as much fun...

Can somebody please explain what chaos theory is? I like quantum mechancics/physics from a philosophical standpoint but I am not particularly familiar with this theory.

With that being said I don't think that anything is set in stone, besides what God has said will come to pass in the Bible. The reason being is simple: if everything is set in stone then the autonomy and free will of the individual are undermined by virtue of his existence. This means that every action that I undertake will not be of my fruition by will be the result of fate. Destiny and fate seems to deny the existence of the conciousness, from a randian /objectivist point of view and from an existential point of view. I am not free to decide my own fate? This means that I'm either going to Hell or Heaven no matter how much I repent or no matter what I do.

To me this does not seem plausible, to accept destiny or fate is deny the freedom of human beings. This appears to me to be the best way to shirk our moral responsibility with respect to action and living. Oh, I didn't kill that person, fate made me do it. Yeah right!!!

On Chaos Theory. I will give it a go.

Chaos Theory describes non-linear dynamic systems which are deterministic but highly sensitive to initial conditions (technically it is far more than that but I am simplifying). Some examples are weather, turbulent fluids and stuff like that.

Because they are highly sensitive to initial conditions outcomes seem to be non-deterministic and unpredictable.

Chaos Theory: A Brief Introduction gives a pretty good introduction.

One interesting concept of quantum theory/parallell universes is the idea that we _don't_ make a decision. Or rather at each decision point the universe splits with one universe based on decision A and another based on decision B. Makes for an insane number of universes, but an interesting concept.

morydd - That is hands-down my favorite type of story... Stories exploring how one tiny moment changed everything and what might have happened it the main character had/hadn't...whatever. Not time travel stories where people change the course of things, but stories which backtrack a person's choices/key moments, etc. and explore what *might* have happened if they had been 1 minute late for a train, or had gone to a movie instead of a play, etc. Is that a "parallel universe" story, or is it a class by itself?

I'm not sure I've read any books like this, but I've seen several movies (e.g. Sliding Doors). Recommendations, anyone?

I think that if you went backwards in time and changed something that, yes, the future itself would have changed, but not the future which you already knew - since anything you did in the past would have already formed the future you - the one who travled back in time.

My head hurts ... did that make sense? :D

let us suppose than in 1000 years time somebody builds a time machine and travels back to the year 1970. anything that person does in 1970 happened 36 years ago - it is already a matter of recorded history.

I know I will never travel back in time and visit myself on my 21st birthday because I don't recall seeing myself there.

if there are time travellers among us now, the result of any action they take will already be a part of their own recorded history.

nobody will ever travel back in time and save John Lennon's life - if they did we would know about it now.

if time travel is ever possible it will have no effect on history.

Thank you, freelunch. That's exactly what I meant to say, as the neurons or synapses or whateverses were misfiring in my brain. :D

Unless the "changes" take place in another universe (multiverse). I believe I read a time travel series that involved the time travelers only being able to time travel in a another universe, but not in their own.

You didn't go back and visit yourself, because you don't recall that happening. But do you know what happened to the you in another universe?

The above probably doesn't make sense, but then since I seem to recall certain historical facts which seem to have now not occurred, or occurred differently . . . .. I don't recall anyone mentioning that I was in an insane asylum. I better ask someone.

Can someone please explain to me how the time-traveling worked at the end of The Time Traveler's Wife? I thought I understood how Henry could move forward and backward through time, but how it ends for him completely confuses me. I don't want to spoil the ending for anyone who hasn't read it, so if I should be asking this somewhere else, please let me know...

There's a theory in quantum physics that everything that CAN happen DOES happen. And that, in fact, it MUST happen. Just not along our timeline. Everytime a decision is made, either by us ourselves or by the universe, there's a branch off that timeline that includes every single optional choice (so each and every second may have an infinite amount of branches, and each and every single one of those may have an infinite amount of branches as well). So, basically, we got an infinite amount of "Yes" universes and an infinite amount of "No" universes, in the case of Binary kinda mindset. And each of those infinite alternate timelines can have an infinite amount of offshoots with all their own yes/no, true/false, living/dead, etc optional offshoots.

So...we "know" that we didn't go visit ourselves at 4 years old to tell us all the mistakes we made in life to try to live a better life, because we know we never met ourselves at age 4 (but, at age 4, would you recognize yourself when you were 30, or 60, or 80?).
But...what if time travel was real? What if we do go back in time to tell our 4 year old self what not tod o? Or to do?

The most logical, IMO, explanation of this is that we do not travel back across time along the single timeline we exist(ed) upon. We actually jump across the timelines and change the reality we percieve, and become part of the new timeline where it happens. I don't go back to talk to myself when -I- was 4. I go to an alternate reality where there's a me that is now 4, and I talk to that alternate me.
Then when I go back to 'my present' I don't return to my original timeline. I travel to another branching timeline, one of the infinite possible timelines of infinite options, and become a part of that timeline. I go to a timeline where I'm rich and famous and supremely healthy because in -that- timeline I was -supposed- to have talked to my 4 year old self and thus I now "truely" exist on that timeline.

Or, in otherwords, we live on Timeline-1. I time travel, I go to Timeline-4, where I was me when I was 4. When I go back to the 'modern era', I don't go back to Timeline-1 or the future of Timeline-4, I go to Timeline-4A, or Timeline-5, whatever you wanna call it, where I now exist and live my life out as if my 4 year old self knew everything I told it.

Confused or enlightened from that? ;)

I see what you are saying but until there is some evidence for multiple time lines and infinite branching universes, I will keep it filed under "miscellaneous theories"

I always liked the idea that the invention of the first time machine can be brought about by using a time travel paradox.

Here is how to do it. The world's scientists agree that they will commit money, time and resources to design and build a time machine. They also agree that the first to achieve the goal, no matter how long it takes, will travel back in time to (let's say) 10 minutes after the agreement is signed. The scientists wait for 10 minutes and if nobody shows up, time travel is impossible. If someone appears, they ask the time traveller how it works and build a machine.

(smile) i like that.

#! - I really love the determinist stories, where if you travel to the past, then you have historically travelled to the past and thus cannot change the future.

I think there is room for both views in fiction, and I love stories like A Sound of Thunder where one mistep (heee heeee) makes the entire future wonky. Still, I prefer the idea that if I visited 1846 to hang with Edgar Allan Poe in Fordham, then I always travelled to the past to hang with Poe and DID NOT change the future.

#13 - Lord Darrow, I've heard your brilliant theory before in another forum, and still think it's the bee's knees! It's so wonderfully simple!!!

Has anyone read Rebecca Ore's Time's Child? There is a scene in that where the voices from the future are all haranguing the characters to do something (often contradicting each other - because at this point there are many possible futures) and as they choose to do something significant many of the voices start to disappear as that particular future becomes impossible.

I've found that the fixed history theory of time travel is better in short stories because they are about the traveller being confused about the travel. The changeable theory makes for more dramatism. But off the top of my head Heinleins "All you Zombies" and "By his Bootstraps" are both of the fixed variety as is time enough for love if i remeber correctly. Also I watched the recent Sandra Bullock film called Premonition which seems to be a fixed one as well.