Time travel with causality violation, "changing the past," introduces further meanings of "now," "then" and "when." A time traveler who has prevented Hitler's birth might think, "Now, history will be different." This "Now..." refers to the timeline in which Hitler is not born and contrasts with the timeline in which Hitler is/was (a new tense is needed) born. Does the latter timeline exist only in the time traveler's memory? If so, then the time traveler never did set out on a mission to change the past. He merely remembers himself doing so.
It would follow that a time traveler who considers setting out on a mission to change the past, e.g., by preventing Hitler's birth, should reason thus:
If my mission succeeds, then my present self will not exist;
but I do exist;
therefore, my mission, if attempted, will fail, possibly fatally;
therefore, I should not attempt it.
Should he instead think, "Now, the timeline that includes Hitler's birth exists materially but then, when I have completed my mission, it will exist only in my memory"? That when does not refer to any moment in the time traveler's current timeline. I think that it implies a second temporal dimension, which would also give meaning to the Now and the then.
1 comment:
Kaor, Paul!
Another question to consider is this: IS it worth trying to prevent Hitler's birth in timeline B when he still would be born in timeline A? One might argue that at least the people in time line B would be spared the horrors arising from his beliefs and actions. But since Hitler would still be born in some timelines, that makes me doubt the utility of trying to prevent his birth at all.
Btw, perhaps that well known picture of Adolf as an infant might be an appropriate blog illustration. Hard to imagine what such an innocuous looking child to have CAUSED.
Sean
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