Posted 30 January 2003 - 04:31 AM
Umm, I'd like to ask Cardie or Rhys to move this thread to the Science & Tech forum. It's just the kind of discussion for that forum, and I get so little activity there. :pout:
Okay, let's bring physics into this, because Robert, Zack & Ash have stayed more consistent with actual time-travel physics than any other SFTV/film writers ever.
No, I take that back, it's not so much physics as simple logic. I say this over and over again: An event that has happened cannot "un-happen." Period. You can't erase a moment of time, because erasure is change. Change requires a "before" and an "after" -- the version of the thing that existed before the change and the version that exists after the change. A single moment in time cannot exist before itself! So the concept of "erasing the past" or "changing the past" is simply meaningless. By definition, if there are two versions of a single moment, they both exist at the same time. Neither one "replaces" the other; they exist side-by-side in parallel timelines.
Most time-travel stories assume that the time-traveller's perspective is reality -- that the "new" history created by the traveller "replaces" the "old" one. But to the objective observer the two histories run simultaneously. The perspective that one history comes "first" and the other "second" is only the time-traveller's personal, subjective point of view, arising from the order in which s/he visits the timelines. It makes no sense to assume the time-traveller's perspective overrides the rest of reality. Maybe it's more interesting from a dramatic viewpoint, but it's logically nonsensical.
It's also mathematically impossible (which is kind of the same thing). To put it in physics terms, an equation must have a unique solution. It can't add up to two different values at once. So there are only two options, the two which Rommie and Sara spelled out in ADDB & BotL: either an event only happens one way, or it happens a different way in each of two separate timelines which subsequently do not affect each other's development.
GRA's writers managed to use both theories. The rules are: under normal circumstances, there is only one timeline. But Harper's device created a unique set of initial conditions which allowed the equations to have two separate solutions, thus allowing two separate histories to branch off. (Does this mean the laws of physics changed? No, merely the conditions under which they operated. Plug different variables into the equations and you get different results. It's just that certain combinations of variables almost never occur.) In quantum terms, it allowed the wavefunction of the universe (see BotL -- a real concept from Stephen Hawking's theories) to enter a stable superposition (two sets of properties at once, like a radioactive atom that's both decayed and undecayed).
The physics is quite clear here from what we've been told onscreen. There is no single history being "rewritten," and no separate-from-the-start parallel histories that cross over. There is one timeline which forks into two (or probably a few more) at a particular node in history, one triggered by the effects of the Alice string-tesseract device (effects which reach back and forward through time around the date of its construction). The Rhade who survived in one timeline ultimately travelled back to the "fork" and took the action which enabled the other timeline to exist.
Okay, that's enough of that for 4 AM... let's move on to the question of free will. Does predestination in time travel mean that free will doesn't exist in the universe? Of course not. Or rather, it proves that we have more free will in some circumstances than we do in others. Our actions are always constrained by what the circumstances make possible. You have free will to move in any direction you choose -- until you step off a cliff. Then your movement options become very, very constrained.
We have free will to act within the laws of physics and logic. Making an event "un-happen" is physically and logically meaningless, so the will to do it is irrelevant -- it just can't be done. Making it happen in two different, simultaneous ways is (by GRA-universe physics) possible in a unique set of initial conditions.
So on to the philosophical question: why should Rhade care about making things better in another timeline if it won't undo what happened in his own? This is something that I guess each individual has to decide. You can do it out of simple altruism, the desire to make things go better in someone's reality if not yours. Or you can convince yourself that the alternate you is still you in some way, and that the alternate versions of the people you care about are still them and deserve your protection just as much. Or you can say, "if it doesn't make things any better for my versions of my loved ones, what's the point?" -- in which case you probably won't make the time journey anyway. Does it matter? Does it matter that you save one version of JFK when another one still dies? That's up to the individual to decide.
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"The first man to raise a fist is the man who's run out of ideas." -- "H. G. Wells," Time After Time
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