Sometimes I still marvel about how in most time-travel stories nobody thinks of this.
The alternate way of computing this is to not actually discard the future, but to split it off to a separate timeline so that you now have two simulations: one that proceeds normally aside for the time-traveler having disappeared from the world, and one that’s been restarted from an earlier date with the addition of the time traveler. Of course, this has its own moral dilemmas as well—such as the fact that you’re as good as dead for your loved ones in the timeline that you just left—but generally smaller than erasing a universe entirely.
Of course, this has its own moral dilemmas as well—such as the fact that you’re as good as dead for your loved ones in the timeline that you just left—but generally smaller than erasing a universe entirely.
You could get around this by forking the time traveler with the universe: in the source universe it would simply appear that the attempted time travel didn’t work.
That would create a new problem, though: you’d never see anyone leave a timeline but every attempt would result in the creation of a new one with a copy of the traveler added at the destination time. A persistent traveler could generate any number of timelines differing only by the number of failed time travel attempts made before the succesful one.
Sometimes I still marvel about how in most time-travel stories nobody thinks of this.
The alternate way of computing this is to not actually discard the future, but to split it off to a separate timeline
Or maybe also another one, somewhat related to the main post—let the universe compute, in it’s own meta-time, a fixed point [0] of reality (that is, the whole of time between the start and the destination of time travel gets recomputed into a form that allowed it to be internally consistent) and continue from there. You could imagine the universe computer simulating casually the same period of time again and again until a fixed point is reached, just like the iterative algorithms used to find it for functions.
That would imply that any changes you made in the past never had any effect on the time you had come from. Which is certainly logically consistent, but not the way most time travel stories work.
The alternate way of computing this is to not actually discard the future, but to split it off to a separate timeline so that you now have two simulations: one that proceeds normally aside for the time-traveler having disappeared from the world, and one that’s been restarted from an earlier date with the addition of the time traveler. Of course, this has its own moral dilemmas as well—such as the fact that you’re as good as dead for your loved ones in the timeline that you just left—but generally smaller than erasing a universe entirely.
You could get around this by forking the time traveler with the universe: in the source universe it would simply appear that the attempted time travel didn’t work.
That would create a new problem, though: you’d never see anyone leave a timeline but every attempt would result in the creation of a new one with a copy of the traveler added at the destination time. A persistent traveler could generate any number of timelines differing only by the number of failed time travel attempts made before the succesful one.
Short jumps (like the 1-hour one in the example) look more like erasing a bit of everyone’s memories, anyway. At least if you buy Egan’s model.
Or maybe also another one, somewhat related to the main post—let the universe compute, in it’s own meta-time, a fixed point [0] of reality (that is, the whole of time between the start and the destination of time travel gets recomputed into a form that allowed it to be internally consistent) and continue from there. You could imagine the universe computer simulating casually the same period of time again and again until a fixed point is reached, just like the iterative algorithms used to find it for functions.
[0] - http://en.wikipedia.org/wiki/Fixed_point_(mathematics)
As good as dead, until you jump back, right? As long as you jump back to a point after you originally jumped from.
That would imply that any changes you made in the past never had any effect on the time you had come from. Which is certainly logically consistent, but not the way most time travel stories work.