Friday, December 26, 2008

After watching "Planet of the Apes" I was thinking a lot about...

Time Travel
Something specific about time travel though. but, First from Wikipedia...
An ontological paradox is a paradox of time travel that questions the existence and creation of information and objects that travel in time. It is very closely related to the predestination paradox and usually occurs at the same time. Because of the possibility of influencing the past while time traveling, one way of explaining why history does not change is by saying that whatever has happened was meant to happen. A time traveler attempting to alter the past in this model, intentionally or not, would only be fulfilling his role in creating history, not changing it. The Novikov self-consistency principle proposes that contradictory causal loops cannot form, but that consistent ones can.

The following is what I was really interested in though.
However, a scenario can occur where items or information are passed from the future to the past, which then become the same items or information that are subsequently passed back. This not only creates a loop, but a situation where these items have no discernible origin. Physical items are even more problematic than pieces of information, since they should ordinarily age and increase in entropy according to the Second law of thermodynamics. But if they age by any nonzero amount at each cycle, they cannot be the same item to be sent back in time, creating a contradiction unless it is a reproduced item such as a seed, spore, etc. The paradox raises the ontological questions of where, when and by whom the items were created or the information derived. Time loop logic operates on similar principles, sending the solutions to computation problems back in time to be checked for correctness without ever being computed "originally."

I heard a good example that went something like this:
On your 13th birthday, a familiar looking man of middle age gives you a beautifully crafted pocketwatch; what appears to be a priceless antique in pristine condition. He tells you that he is a friend of your father's and he'd want you to have it. So you accept the watch, thank the man and he goes on his way. You never see him again, but you keep the watch in a cigar box and it goes untouched until 35 years later when you finally complete work on your time machine. With the watch you go back in time to meet your former teenage self and give yourself the watch.

So I kind of botched the storytelling, but anyway, where did the watch come from originally? Nowhere?

"Back to the Future" is a good example too. Marty goes back in time and proves to Doc that he's from the future by telling him how he originally got the idea for the flux capacitor when he hit his head. Therefore, Doc must have at that point realized that time travel IS possible and that his plans for the FC would eventually work. What would have been weirder is if Marty went back in time before Doc had even started thinking of making a time machine and gave him the idea and plans to build one. So the plans came from the Doc of the future, who "originally" got the plans when he was visited by Marty in the past. so....

I didn't really have a point to this discussion. I was just thinking about all that stuff and how it could be possible to have objects or ideas (or a person maybe?) without any discernible origin.


Robert said...


see the film PRIMER

Ryan said...

i put it on my cue. thanks for the recommendation, tho.

Hi Bob!

Pete said...

Time travel is one of the most poignant, personal, and hallucinatory vehicles Science Fiction has. (Slaughterhouse Five, La Jetee/Twelve Monkeys, et al.)

Schoedinger's Cat is another great paradox. Perhaps everything that can exist, does.