Re: Time Travel, Can it ever be?

Posted by Pasti on Feb 08, 2004 at 22:08

Re: Time Travel, Can it ever be? (Uncle Al)

Al, it is not obvious to me that what you say will happen, neessarily.I.e. that any universe with time travel in the past will screw itself up until time travel will not be discovered anymore.

As much as I enjoyed the sci-fi novel you are paraphrasing,it is not the only possibility.And remember, when the guy in the novel returned to its original time coordinates, everything was diffterent because he stepped on that butterfly in the past, but time travel was still available because the guy returned there...

Before making any argument of the type you made,you have first to decide if you have a unique timeline, or parallel universes.

If you have a unique timeline, than you are in trouble, because causality (assuming it holds) does not allow the past to be influenced by the future, so going back into the past won't affect the future, at least at this theoretical level.

If you assume multiple universes, at the level where at every instant in time the universe evolution branches out in an infinite number of possible futures, and we are now in only one of these possibilities, going into the past means that the traveler might end in another parallel universe,where time travel hasn' been discovered yet, and with some luck will never be discovered.But then he knows about time travel,and that particular universe will therefore know about time travel,and given enough time and ergodicity, or even quasi-ergodicity, in the end all universes will know about time travel.

The beauty about discussing time travel of any type is that sooner or later the argments become cyclic, and we don't know yet how toproperly deal with this cyclicity.

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