Did anyone see the movie? What do you think of the plausibility of the time-travel and the sort of technology presented there? I know there were many loopholes in the way the store unfolded and soem of it went quite mad after a while (they pretty much skipped over all the paradoxed this sort of time-travel would entail). Still though, how close could we get to this sort of technology?
DejaVu
- Thread starter alexsok
- Start date
Well, a non-interactive "temporal viewer" is logically consistent in that it introduces no traditional time travel paradoxes. That is, being able to view any information from an arbitrary prior date doesn't cause logical paradoxes (although it may conflict with thermodynamics and information theory somehow). However, actually traveling back in a way where one can interact with the past causes of course all of the illogic of time travel plot devices. David Deutsch in "The Fabric of Reality" actually explore the reality of building a real time machine by using the thought experiment of trying to build a virtual reality simulator/holodeck that simulates exactly the time traveling experience. If you allow past interaction and future recursion (e.g. you can change the past, which can change your own future timeline), you end up with a Halting Theorem violation, and a violation of the Church-Turing hypothesis, which may or may not rule out time travel devices, but at the very least, provides a conditional theory of time travel, conditional on the truth/falsity of the Church-Turing hypothesis.
Deutsch provides a "way out" explanation which will be somewhat unsatisfying for some fans of time travel. Time doesn't exist. Each instant of time is just another configuration of the multiverse. Time travel to the past, if possible, is actually travel to a parallel universe. Any changes you may there have no effect on the original "time line" that you came from. Therefore, there is no grandfather paradox. There's also probably no way to "get back" to the future/timeline you originally came from.
I prefer the illogical, but more twisted, single-universe paradox laden time travel plot devices. However, I like it when they use predestination paradoxes instead, so that the timeline can't be changed no matter how hard you try, and in reality, all your timetraveling was a closed loop that always was going to happen.
And of course, I love Hiro's character from Heroes.
He of course, recently discovered that he couldn't change the past (yet) as his travel became part of a predestination paradox (he ended up being the one giving MegaMemory Waitress her Japanese phrasebook birthday present, which means in the future, she had already met him, but perhaps can't remember much from six months ago due to her brain damage ala Memento. She can remember facts and figures, but can't remember personal experience from that time. Or perhaps she did recognize Hiro in the future, but pretended not to, knowing he would go back in time if she didn't say anything)
Deutsch provides a "way out" explanation which will be somewhat unsatisfying for some fans of time travel. Time doesn't exist. Each instant of time is just another configuration of the multiverse. Time travel to the past, if possible, is actually travel to a parallel universe. Any changes you may there have no effect on the original "time line" that you came from. Therefore, there is no grandfather paradox. There's also probably no way to "get back" to the future/timeline you originally came from.
I prefer the illogical, but more twisted, single-universe paradox laden time travel plot devices. However, I like it when they use predestination paradoxes instead, so that the timeline can't be changed no matter how hard you try, and in reality, all your timetraveling was a closed loop that always was going to happen.
And of course, I love Hiro's character from Heroes.
He of course, recently discovered that he couldn't change the past (yet) as his travel became part of a predestination paradox (he ended up being the one giving MegaMemory Waitress her Japanese phrasebook birthday present, which means in the future, she had already met him, but perhaps can't remember much from six months ago due to her brain damage ala Memento. She can remember facts and figures, but can't remember personal experience from that time. Or perhaps she did recognize Hiro in the future, but pretended not to, knowing he would go back in time if she didn't say anything)
I liked the movie Deja Vu, although there were plot holes and inconsistencies you could drive a truck thru.
Even with all the problems, it was still smarter than most Hollywood time travel movies.
Even with all the problems, it was still smarter than most Hollywood time travel movies.
DudeMiester
Regular
I've been coming to think of the universe as a reconfiguring state that maintains a history of its past. That is, time is a side effect of it's internal interactions. We only perceive time because of the causal chain of events, not that time exists on its own.
In this system, time travel to the future or the past is perfectly possible, but it's more of a delusion really. When you go to the future, you just step out of the interactions for a while. To go to the past, you tap into the history mechanism to run a simulation. Once the simulation is established, one can create paradox like situations, but really nothing unusual is occurring. You're just making a strange simulated environment. Moreover, there is no worry of being unable to come back to where you started, because when you step into the simulation, you could step out of your normal interactions, do the "time travel", and step back in without missing a beat. It would seem to your friends that you were only gone for an instant. Of course, this would almost certainly require ridiculous amounts of energy and information.
In this system, time travel to the future or the past is perfectly possible, but it's more of a delusion really. When you go to the future, you just step out of the interactions for a while. To go to the past, you tap into the history mechanism to run a simulation. Once the simulation is established, one can create paradox like situations, but really nothing unusual is occurring. You're just making a strange simulated environment. Moreover, there is no worry of being unable to come back to where you started, because when you step into the simulation, you could step out of your normal interactions, do the "time travel", and step back in without missing a beat. It would seem to your friends that you were only gone for an instant. Of course, this would almost certainly require ridiculous amounts of energy and information.
... Haven't we already had this thread?
Now, that's clever.I like the movie overall though there were several holes. Information theory would proabably blow the whole premise apart but i can think of logical ways to get around some parts of it.
For example moving paper or a body from the present into the past isn't that much of a problem. The movie solves the problem by substituting the "future" denzel washington before reintroducing the "old" denzel washington to the woman which was a very neat information theory solution.
So bodies and objects can be dealt with allow for a consistent balance to the universe's information level. Until the old denzel appears to the viewers, he doesn't exist so to speak. The problem lay in the transfer of energy like when he used teh lazer pointer and the woman saw it.. that could NOT happen. That energy was current energy that was expended in the future and could not go backwards in time to before it was expended. anyway more later...
For example moving paper or a body from the present into the past isn't that much of a problem. The movie solves the problem by substituting the "future" denzel washington before reintroducing the "old" denzel washington to the woman which was a very neat information theory solution.
So bodies and objects can be dealt with allow for a consistent balance to the universe's information level. Until the old denzel appears to the viewers, he doesn't exist so to speak. The problem lay in the transfer of energy like when he used teh lazer pointer and the woman saw it.. that could NOT happen. That energy was current energy that was expended in the future and could not go backwards in time to before it was expended. anyway more later...
I was not speaking of information theory issues with respect to past time travel and duplicates, but from past temporal viewing (you don't travel to past, but you can view any event that happened). And it's not just information theory problems about information storage and erasure, but also quantum mechanics. Leaving aside interaction-free measurement/observation, one might be able to conduct a quantum eraser experiment, and then use a temporal viewer to recover the information which was erased, which would pose serious questions for QM.
One can imagine a temporal viewer physically realized by using an uber-powerful omega-point quantum computer to simulate physics. Then, run time-reversible physics backwards to recover past state and then forward to recover the event. The problem is, storage, since if you use reversible computation, you need enormous storage to avoid "erasing" information which consumes energy, and if you use non-reversible computation, you consume ginormous amounts of energy .
I think somewhere along the line, there's a information paradox to temporal viewing just as there is to time travel itself, just like we encountered seemingly paradoxical situations when we assumed blackholes with singularities can erase information.
One can imagine a temporal viewer physically realized by using an uber-powerful omega-point quantum computer to simulate physics. Then, run time-reversible physics backwards to recover past state and then forward to recover the event. The problem is, storage, since if you use reversible computation, you need enormous storage to avoid "erasing" information which consumes energy, and if you use non-reversible computation, you consume ginormous amounts of energy .
I think somewhere along the line, there's a information paradox to temporal viewing just as there is to time travel itself, just like we encountered seemingly paradoxical situations when we assumed blackholes with singularities can erase information.
