Probably the wrong word to use but it sounded cool so I thought it would work. OK originally David is sent back to his planet 8 years later but without aging. At the end he travels back in time 8 years into the past where he started from. Here's my question, what happens in 8 years from that point? Does the "other" David from the first time appear? Would there be 2 Davids or did I miss it completely?
shareNo I don't think that would happen because he didn't just travel in time, he changed time. By going back in time to his original "time zone", he therefore erases the fact that he was abducted for 8 years and therefore isn't missing and doesn't turn up 8 years later (because in David's timeline, that's already happened (the movie), but in everyone else's timeline, he was never missing in the first place).
I used to feel really sorry for the family that he leaves behind in the "future", but I now realise that by going back and joining his family in his original time line, the "future" family without David ceases to exist and instead becomes whatever it becomes with David having been around all along.
I'm aware that's not a flawless explanation, but since this is a kids film that's how I choose to look at it.
This doesn't really make sense. If you can change time then it would create a parallel universe, where David was abducted.
The "future" David-less family would still have grieved for him for 8 years, even if you did say that timeline was 'erased'.
The fact that David saw them, means they do exist somewhere. I don't really think you can erase that suffering by changing time. It still happened.
Think of the Mutiverse theory.
sharecorrection, he was still abducted and taken to where he was taken , at the same time the david from the future was returned not long after the original was abducted, then 8 years later the original david comes back, so there are 2 david's existing at the same time, so how exactly does david being returned AFTER he was abducted change the fact that he WAS abducted?
"sir, sir, i gotta check and see if you've soiled yourself, I'll get to you in a moment, sir!"
Where does he change the timeline that he gets kidnapped, he gets taken to a point in time about 5 minutes AFTER he was kidnapped, he only changed the future, not the past. A David will appear in 8 years time and the events of the film will be different, creating multiple timelines which will unravel the fabric of reality itself and possible blow up the galaxy, hopefully it will only be this one, which would be some relief. Great Scott.
"sir, sir, i gotta check and see if you've soiled yourself, I'll get to you in a moment, sir!"
The other David never appears, because if it did, we would see it happen in the movie. I mean, we've seen the future, and there's only one David there.
But in the end, the whole thing is a paradox that nullifies itself, so either way, it can't happen. Here's my old explanation of it (I am quoting myself):
"BEGINNING OF THE LOOP:
No "missing David" = "No police station" = "No trip to NASA" = "No navigator for Max" = "No time travel back to 1978" ...
... which would then mean ..
"No time travel back to 1978" = "Missing David" = "Police station" = "Trip to NASA" = "Navigator for Max" = "Time travel back to 1978" ..
... which would then mean ..
GO TO THE BEGINNING OF THE LOOP"
Technically you are right. This is a paradox. David is returned to his original time at the end of the movie. Therefore he would never have been reported as missing in the first place. There should have been an older David in the future as he was returned.
On a side note. He didn't time travel 8 years into the future. It took 8 years on earth for him to go to Alpha Centauri and be experimented on and then brought back. He hasn't aged because of the theory that when you travel faster then the speed of light time slows down for the traveler.
He hasn't aged because of the theory that when you travel faster then the speed of light time slows down for the traveler.
Actually, it is a theory in the strict sense of the term. Time dilation has been observed on trans-Atlantic flights.
One interesting thought that I've had about this is what stops different parts of one's body from existing in different times? While it might not be perceptible, there would still be some. If you move your arm back and forth, it is traveling at a different speed.
[deleted]
might not be a "paradox" but a really severe and possibly head-exploding headache trying to figure it out altogether! LOL.
But yes, I believe one of the other posters explained it best (forget which one). David was abducted & placed on a separate timeline than his own. He was "missing" for 8 years, and since he would most likely be labelled "David-Prime" (meaning original or #1), David-Prime was simply returned to his own time a slightly later than falling into the trench.
Max the ship/computer simply just placed him in the same area as the trench, just was off by a few years.
You are correct. However, just to clarify, traveling forward in time is entirely possible. As you accelerate toward the speed of light, time slows down. This effect is observed everyday on a small scale, on satellites in orbit, particle accelerators (like the large haldron collider), etc.
Going back in time, at the end of the movie... that's the paradox.
How about going with the Parallel Universe idea, and Max and David landed in a parallel universe.
Anything that can happen, will happen, so what are the chances of jumping into a parallel universe, a place where an alternate david was missing for 8 years and simply goes nack to hia reality where he was missing for 2 hours
In stories where paradox is not directly addressed, I take it like this: David left 1978 and came back in 1986. He was in 1986 for a few days. Then he went back in time to 1978. For the few days, that timeline existed only for David (and Max). No one else would ever experience that timeline.
All glory to the Hypnotoad
I agree with this interpretation. Even though David travels back to 1978, he does not do this until the end of the movie, so technically, those few days in 1986 took place "before" David is returned to his family on July 4, 1978. Therefore, there is no 20 year old David in the 1986 that is shown in the movie.
shareThe answer lies in what those in the movie "Deja Vu" call the "branching universe theory"... Or the Many-worlds Interpretation.
http://en.wikipedia.org/wiki/Many-worlds_interpretation
------------
Right now, we are alive... And in this moment, I swear... We are infinite.
I don't know if any of this makes a difference in the "paradox" so if it does someone please explain it for me. A couple things have changed even if the alternate timeline in the movie is erased: 1)Max and the aliens who built it still have the knowledge gathered by Max's expedition (even if the alternate timeline doesn't exist) and 2) Max still has memory of the alternate timeline so I'm guessing this makes both David and Max certified inter-dimensional travelers.
Also something to consider, the little alien creature David keeps from Max at the end of the movie is proof that that alternate timeline took place somewhere/sometime.
Lastly, whoever said David didn't travel into the future is correct, it's only stated at the end by Max that they will travel through time to return David to where he was supposed to have been returned to in the first place. Apparently time travel was the only real dangerous thing they did in the movie.
Peace is not the absence of affliction, but the presence of God. ~Author Unknown
There's two basic kinds of time travel in movies - a single timeline that's always changing (i.e. Back To The Future), or as a single fixed timeline (i.e. Bill & Ted) where changes have always happened.
We can rule out the fixed timeline in this movie, considering that 12 year old 1978 David obviously shows up in 1986, and because he still has the creature with him at the end, along with his memories of Max and his adventure. It's just like Back to the Future's single changeable timeline, so my theory is that, once David is back in 1978 (more or less "in his own time", albeit a few days older), the 1986 version of his parents and his brother Jeff we saw in the movie, ceases to exist.
Put it this way, if a time traveler were in '86 at the very end of the movie, the timeline probably would've immediately changed around them to a universe where 20-year-old David had always existed (just with his memories of the trip years before).
It's like how Marty all throughout Back to the Future would remember his nerdy dad and alcoholic mom from the beginning of Part 1, and all his adventures throughout Part 2 and 3, despite those timelines no longer existing.