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Time Travel: Paradox, Parallel or Repetitive?

  1. Jun 28, 2004 #1
    Time Travel has been a common staple in the science fiction genre and a topic that I always found interesting. In movies and books I learned that there are three types of time travel: paradoxical, parallel and repetitive. The first type of time travel is known as being paradoxical, where the time traveler goes back into the past to prevent his or her parents from meeting. If the time traveler succeeds, he or she will disappear and never have existed. But if the time traveler never existed, then how could he or she have been able to go back in time in the first place? Clearly, a paradox has taken place.

    The second type of time travel is known as the many-worlds or many-universes interpretation. If a time traveler goes back into the past to prevent their own existence from occuring, time will automatically fork into another timeline or form a parallel universe where in the second timeline, the time traveler would never have been born because it hasn't happen yet. Therefore, the time traveler's life is in no danger of erasing his or her existence, afterall, he or she had to come from somewhere!

    Finally, the last type of time travel is known as repetitive. That is, if a time traveler goes into the past, he or she can never change it because the laws of time will prevent them from doing so, therefore, they can only FULLFILL the past.

    Personally, I don't think time travel into the past will ever be possible because quite simply, there is no frame of reference to begin with. The past is forever gone, there is no going back. The future has not happened yet, therefore, our cherished concept of free-will is secured. The past and future cannot exist simultaneously with the present. Hence, the only thing that remains constant is the present.

    On the other hand, if our descendants discover time travel to be possible with the aid of some extremely advance technology, the one type of time travel that will never be possible is the paradoxical one. Why? Well, Einstein stated that all living things have what is called a worldline. Think of a worldline something akin to a film negative. One end represents your birth, the other end, your death. If a time traveler were to travel back into the past to prevent you from being born, your worldline will disappear and you would cease to exist like in the movie, "Back To The Future".

    However, according to Einstein, wordlines can never be cut or altered. Paradoxes by definition CANNOT HAPPEN. Any time travel paradigms that result in paradoxes are inherently flawed. It should be the responsibility of any theory worth two cents to provide a paradigm that does NOT result in paradoxes.

    Another sign of a lousy theory is any that requires something as implausable and unproveable as the creation of an entire universe every time someone makes a left turn as opposed to a right, just to avoid situations that are impossible in the first place! (Parallel Universes). Which leaves Repetative, or Self Consistancy. This is of course the only theory that makes sense.

    Thoughts anyone?

  2. jcsd
  3. Jun 29, 2004 #2


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    I totally agree. If time travel into the past is possible, and someone has traveled into the past (or will travel) then the past unfolded in the way it did as a result of that person's presence. The past happened the way it happened, whatever the cause.
  4. Jun 30, 2004 #3
    Like I have said before

    I believe that time travel is possible

    1. Moving faster than the speed of light. If you somehow do so, then you will go back in time.

    2. Entering a Wormhole, since wormholes traverse space and time. I think I heard somewhere that wormholes have actually been observed on the microscopic level, but I don't remember where.

    3. Sending your mind across time while your body sits in a nice air conditioned room. If you did this, then you would avoid all of the ugly paradoxes that arise by going back in time.
  5. Jul 16, 2004 #4
    Parallel Universes

    Some theories state that parallel universes are not created when you make that turn. They were already there. See Parallel Universes by Max Tegmark. The theory goes hand in hand with eternalism in which the past, present and future are all actual. So, in one you would take the left turn and in the other you don't. Although Tegmark didn't write about time travel, the theory would explain the balance of matter. If you travel to another time then you leave one parallel universe and enter another, so in the Multiverse no matter is lost or created.
  6. Jul 16, 2004 #5


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    You can side step the issue using parallel universe or multiverse concepts, but, in leaving this time you effectively destroy energy in the here and now, which violates the law of energy-mass conservancy. Furthermore, upon arriving in the past, the atoms you are composed of would be physically located in two different places at the same time.

    Therefore, the law of energy-mass conservancy must be ignored to allow time travel. This creates even more headaches. The mass density of the universe is so finely tuned that sending any amount of mass back to the early universe could cause it to collapse. And, conversely, 'stealing' any amount of mass from the early universe could cause it to expand so rapidly that galaxies, stars, etc would never form. And to think, people worry about what would happen if you murdered your ancestors.
  7. Jul 16, 2004 #6

    In the quantum world when an observer tries to measuer a very small amount of time it becomes no longer possible to tell the difference between past pressent and future. Therefor, they all CAN happen at the same time. In the quantum world everything that happens is a game of chance where-as everything that can happen, has a chance of happening.


    In the Relativity world it is proved that time is bound to our three dimensional space. Also in the relativity world it is proven that our three dimensional space is able to be manipulated Thererfor if our three dimensional space is able to be manipulated then time is also.

    Watch this online if you are still having trouble
    Last edited: Jul 16, 2004
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