I have a question about time travel, and I'm going to use a South Park episode as an example. In the trapper keeper episode, someone comes back from the future to destroy Cartman's trapper keeper because it eventually becomes the ruler of the world. What I don't understand is if he destroyed it, the trapper keeper would have never taken over the world, so he would have never existed, which means he would have never come back to destroy it, so then it would take over the earth. It's just a big cycle.. Am I looking at it wrong or what? I don't think time travel really is possible or anything, its just confusing.
2007-11-19 06:04:40 · 11 answers · asked by Stacy L 1 in Science & Mathematics ➔ Astronomy & Space
This is a paradox known as the "Grandfather paradox"
If you go back in time and kill your grandfather before he met your grandmother, you would never exist and therefore COULD NOT have gone back in time and killed your grandfather which means that you would exist and that you would have gone back in time etc...
One explanation is that when you travel back in time, you travel to an alternate universe where you existed at that time, therefore your universe where you live and exist will not be affected by your action in the past.
Another explanation is that you cannot prevent something from happening, because it has already happened. An example is you travel back in time, kill your grandfather, and then somehow without realizing it you actually cause your grandmother to conceive your parents, as in you cause your birth.
2007-11-19 06:17:19 · answer #1 · answered by Trekky0623 5 · 0⤊ 2⤋
aviophage got it right. But she is very polite. I won't be:
Time travel is not even a logical paradox but (as of today) simple nonsense.
Russel's paradox
http://plato.stanford.edu/entries/russell-paradox/
about
"The barber in the village who only shaves the beards of men who do not shave their own beards."
(that is not really Russel's paradox but it is easier to see the problem unless one is a mathematician)
is not a paradox, at all. It simply indicates that the naive assumption that all mathematical questions (that can be asked in group theory) make sense, is wrong. In mathematics something great came of it, namely the insight of Goedel that one can pose questions in mathematics which can not be answered with the same language used in the question (and ultimately some, actually most, questions can not be answered at all).
In physics, however, we do not have such a luxury. The only things that truly count are experimental results. And in experiments nobody has turned back time, yet. Until that happens, time travel is assumed impossible. And once somebody manages to turn time back, we will simply rewrite most, if not all of physics to accomodate the new fact. And if that happens we will simply learn that our naive illusions of time were all wrong. Time travel as found in cheap SciFi will still stay impossible but some other, much more fantastic and interesting form of time travel might be possible. And even that won't be as big a deal as most people think. Physicists revise their own naive illusions of nature all the time. THAT IS THE JOB of a physicist.
:-)
2007-11-19 16:48:01 · answer #2 · answered by Anonymous · 0⤊ 0⤋
By going back in time...you would be inserting yourself into a time in the past where before you did not exist. If you were to do something in the past to change the course of events going forward..you would not be able to go back to the 'future' you came from because it no longer would exists. If you were to travel forward from the past you would enter a new present time in which you may or may not exist...but if you do exist there will now be two of you...You the time traveler...and you the result of changes in the past. Traveling outside of "your time" is a one way ticket
2007-11-19 17:45:14 · answer #3 · answered by J. A 2 · 0⤊ 0⤋
It is relatively easy to come up with 'time-travel' paradoxes. This has led many to believe that their existence (and non-solvability) demonstrates that time travel cannot exist, otherwise, our "time-line" would (already?) be in shambles.
One way out is for every inventor of time machines to be killed (by someone from the future, of course) before they invent their machine.
However, there is always the possibility that somebody else will get a visit from himself-in-the-future, with the plans of the time-machine he will soon invent. So, he builds a new time machine based on plans that came from the future, thereby 'inventing' it (this is an example of an ontological paradox: information coming from the future).
---
Now, if you really want to fry your mind with this stuff (it is fun, but you'll be mentally lost forever), read "All you Zombies" by Robert Heinlein.
Fantasy and Science Fiction Magazine, 1959.
2007-11-19 14:21:42 · answer #4 · answered by Raymond 7 · 0⤊ 2⤋
The paradoxes are fun to think about.
Time travel is not logically possible, and cannot ever be.
The past and the future are not destinations like Paris and Philadelphia. They are not "places" to which it is possible to "travel."
It is not possible to go to the past, because the past no longer exists.
It is not possible to go to the future, because the future does not yet exist.
No science required--just basic logic.
On the other hand, you can put your ear to your girlfriend's bellybutton and see if you can hear the ocean. That's a real trip!
Good luck!
2007-11-19 16:17:47 · answer #5 · answered by aviophage 7 · 1⤊ 1⤋
what your talking about is a variation of the grandfather paradox, which says the same thing u did but with killing your grandfather.
the 2 main theories are that either
1. time travel is not possible.
2. when you travel back in time it starts a new "branch" of time that doesnt effect the original one.
2007-11-19 16:14:19 · answer #6 · answered by Anonymous · 0⤊ 2⤋
even if you go back in time to change an event that changes the event in the current time you went to.
you can not change the future. now say i went back to stop the assissantion of JFK. there time line he would still be alive. when i go back to my future JFK would still have been assissnated.
2007-11-19 14:13:55 · answer #7 · answered by Anonymous · 0⤊ 1⤋
come on~
its just a tv programme! it doesnt have to make sense! especially south park! i see were ur coming from, but still, get over it dude!
xx
2007-11-19 14:19:28 · answer #8 · answered by *Facepalm* 5 · 1⤊ 0⤋
it makes sence if its a time parodox. Like its suposed to happen and by going back in time you can change it. It makes sence if you can have a wider view of time and space.
2007-11-19 14:11:53 · answer #9 · answered by bryang702 2 · 0⤊ 1⤋
We are all time traveling right now. If you don't believe me, ask a physicist.
2007-11-19 18:46:10 · answer #10 · answered by Eratosthenes 3 · 1⤊ 0⤋