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Time travel / Already lived

  1. Jun 26, 2012 #1
    I have had this question and nobody can answer it, so I decided to REGISTER here.

    If time travel was possible, would a person living in the year 3000, time traveled back to year 1000 AD. Does that mean that life has already been played out?

    Meaning people living in the year 1000, feel as if their time is right now (now happening). So if someone time traveled from 3000, they would think that they have already lived their life, how else could someone come from the future unless their life has already been played out?

    So technically everyone alive right now, are not living in current time. We have really already lived our life, correct?
  2. jcsd
  3. Jun 26, 2012 #2
    What a mind boggling question!
    I'm by no means a professional in this field but I think this falls more into the category of philosophy than physics.

    Another approach would be that you won't actually be traveling back in our current timeline. Whenever you choose to travel back in time you do so into another timeline, so in essence you would not return to our universe. Mathematics suggest that there are an infinite amount of universes.

    I'm plowing through "A Brief History of Time" right now but haven't gotten far enough to touch this subject yet.
  4. Jun 26, 2012 #3
    what about the reverse? someone time travelling to the future, their life wouldn't have played out yet. sooo... they would feel like they shouldn't exist, because they skipped the whole part where they came into existence and stuff.

    So to your theory everyone alive right now, don't exist?

    I think you can't conclude that we have already lived our life, because none of us have traveled between past and present
  5. Jun 27, 2012 #4
    If one is traveling to the future, their life has played out. They are living in the (machine) or said object that is bringing them to the future. That is their life being played out, (the time traveling).

    We know time is steadily moving forwards, not backwards. I feel like, my (theory) cannot be flipped to the reverse.
  6. Jun 27, 2012 #5
    That would, again, bring in the problem of infinity. If time travel was possible that would mean that time is a constant in a sense. Meaning that every moment in time is in a system that we can revisit.
    Playing with the idea that we could choose which time line to visit, we could return to any moment in time. This would mean that everything that ever happened and will happen is actually a constant.

    All in all we have to assume that the question is invalid. For the time being, time travel is impossible. Speculating about it is interesting but you might as well speculate about what mathematics might look like if a=b. Everything we know of physics is based on the fact that time can only be stopped, not turned backwards.
  7. Jun 27, 2012 #6
    Here might lay the answer to your question. Time does not exist, it does not travel, move, or do anything; it is purely a mathematical idea that we [humans] use to describe change.
  8. Jun 27, 2012 #7


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    Staff: Mentor

    No we are now living our life.
  9. Jun 27, 2012 #8


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    Science Advisor

    The time - like basis vector ∂t is future - directed.
  10. Jun 27, 2012 #9
    Time does exist, 14 billions years this universe has been around.
    And if time does not exist, explain how come we cannot visit other periods of life?

    It would seem like that, but if a time traveler from the future popped into our lives, I believe that would make the premise false. He cannot time travel from the future UNLESS we have already lived.

    I believe every moment seems like (right now) but for all we know, somewhere else EGYPTIANS could be building their pyramids, and they go through this everyday.
  11. Jun 27, 2012 #10
    This thread is overspeculative and does not meet the guidelines of this forum.
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