You might already know how I am fascinated with the idea of time travels. The most special thing about it is how it may change our perception of time. In deeper consideration we could come to conclusion, that the most widely spread concept of time travels in fiction contradicts with itself if we assume that there is only one world, with no alternatives and time is linear.
It in fact has nothing to do with any technical possibility of travelling in time, but the motives driving a potencial time traveller to his or her journey. What would be the reason to ‘mend’ the past if it will be already ‘mended’?
Let us consider a hypothetical situation: something happens, few years after, somebody (let’s call him Jack) discovers its consequences and wants to ‘undo’ that situation. To do this, Jack travels back in time to prevent this something from taking place. He succeeds and… what now?
If the change was made in the past, now it is already changed. There is no longer any reason to go back in time… Although without doing it, the change wouldn’t take place. Jack eliminates the problem together with the motives which have driven him to do that. Then… how to make it happen anyway?
We may think, that this traveller could leave a message for himself. Okay. Then in the reality when the problem doesn’t exist, the message would be the reason to go back in time and follow the instructions. It would work like a some kind of infinite recursion, an event invoking itself, but… here we have another paradox.
This recursion would ‘delete’ its first invocation at the beginning. Jack went back in time, made the change and left the message, but still… The reason for doing it disappears, nobody goes back and there’s no message left… and the change still isn’t made. What happens then?
If it is impossible, then Jack would probably be unable to make this journey happen or… it will be happening again and again, trapping the traveller in one moment in time. Starting the journey, succeeding, going back to moment right before it, starting the journey… infinitely. If there is no alternative world, then it would be impossible for Jack to make other decision or perceive what is happening and stop it.
But… what if every person and every thing has its own, personal timeline? If mixing one’s chronology of events doesn’t affect the other? Time is relative and there is no absolute time. So maybe it wouldn’t be paradox if we would think of time as a space?
The fundamental question in this case will be the fact, that Jack wouldn’t be affected by the changes in his own ‘linear’ past. It wouldn’t change his memories, Jack’s timeline wouldn’t be linear anymore and maybe it shouldn’t be perceived that way even outside this context.
For Jack (our time traveller), element of the past will be the future (right before the journey) and there, in the past, his own past will be future (the time when the journey started). The next question is… how would it affect everybody else and their timelines? We will try to consider this next… um… time?
PS: You might also share your thoughts about this issue here.