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Time travel

  1. May 15, 2003 #1
    I'm new to the topic of theoretical physics so can someone fill me in is it possible to go back in time and go to the future?

    because say Joe is from the future, and he goes to the pass and kill's his younger version. will he instantly disappear?

    oh yeah btw, it struck me, parallel universes, how do they exist?
     
  2. jcsd
  3. May 15, 2003 #2
    the Einstein's theory of relativity show me the time can't move back
    so i think go back is impossible
    but go to future is possible
    because when you moving with light speed
    your time will stop, and you will be live 1000...year
    this is future
     
  4. May 15, 2003 #3
    1. No, it is not possible to travel through time. It is completely and totally impossible, it's just a sci-fi idea that will NEVER happen. That's that.

    2. If you want to see proof of paralell universes I URGE YOU to go to the store and get the newest copy of SCIENTIFIC AMERICAN which says in big letters PARALELL UNIVERSES on the cover. It's about 6 bucks and WELL WORTH IT. It's amazing how easily it is to prove they exist.
     
  5. May 15, 2003 #4
    Time travel is only based on reletivity. That may be useful in normal situations, but is this a normal situation? We are talking about reversing all of the reletivistic veiws to point in the opposite direction of what they were before. This is what I call 'total time dialation.'
    Another way to change time is to slow your 'time experience' to make the reletivistic veiw of everybody around you move faster and, basicallly speed up their time reletivistically to your time feild.
    this is what I call reletivistic time dialation.
     
  6. May 15, 2003 #5
    No, it's not possible. See the first post in: Why We Can't Go Back
     
  7. May 15, 2003 #6
    Heh, yes mentat says it all! I like mentat, good discussion 1 on 1 and he points it out so simply! yay!
     
  8. May 15, 2003 #7
    I use logic et al to explain my theories and facts. But I'm gonna make a special exception and make a point, I will also post the common rebutal. NOTE, the rebutal is fine, but no need as I am just pointing this out.

    Let's make the non-controversial (unless your a religious idiot) that the universe is oh let's say 50 billion years old.

    Let's make another assumption, since people here like to pull stuff outta their butt, that there's only THIS universe, ok?

    Ok. Now, practically speaking, if we have gone 50 bill years here, and we have oh let's say an infinite amount of time left. Then, even if time travel was discovered in 100 billion years, you telling me we wouldnt have future organisms popping the hell up all over the place?

    They would have billions of years to choose all sorts of time periods and places to go.

    It's just a practical idea.

    The usual rebutal is, how would we notice something from the future. Well, would you notice if an 8th century warrior was walking around the freakin mall, going crazy over what he's seeing? I thought so.

    Just a point. time travel possibilities have slready been disproven beyond rationality, thus and only thus i point this out for entertainment.

    time travel is pseudo science.
     
  9. May 16, 2003 #8


    In a quantum parallel universe, his younger version is alive and not alive. This is called super-positioning. When he kills his younger version, the older Joe creates a new history.



    Which parallel universe?
    :wink:

    Level 1: I'll get back to you on this one...
    Level 2: When the universe inflates, some parts of space stop stretching. The symmetry on that region would break, therefore creating a new bubble like universe with a Hubble volume that is identical to the original universe. But the events aren't the same.
    Level 3:The quantum universe. In this universe, everything is random. Events branch out according to each event. For example, if you choose a salad out of 6 choices, you are only experiencing the 1/6 of the whole reality. There is one wave function per reality. In another quantum history, you didn't have a salad and so on. So, you did have salad and you didn't have salad. This is called supperpositioning.
    Level 4: In this universe, all physical laws are not consistent with ours. In such a universe, what we think of gravity is exactly the opposite in the Level 4 universe. Time could be a physical aspect of our universe that we can control easily and naturally.

    Scientific American has an article on this, if you want to read it.
     
  10. May 16, 2003 #9
    Majin - Yeah this article was recommended by me and others, it's good. I wanna learn more about it I'm gonna get the elgant universe..
     
  11. May 16, 2003 #10

    Ivan Seeking

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    In the collection of essays, "The Future of Spacetime" by Hawking and others, Igor Novikov presents a rather interesting proof. I have not seen the formal derivation of this but I understand that one does exist. The setup is to consider a billiards table with a time machine located in the corner pocket. If we shoot a ball into the corner pocket, the ball falls into the time machine, goes back in time, and is then released from the side pocket just in time to hit itself; thus deflecting it's original trajectory and preventing the ball from ever falling in the corner pocket - a billiards version of the grandfather paradox. It can be shown that it is possible to cause the ball to deflect itself, but not so much as to miss the pocket.

    Edit: Hawking [I think] then comments that one might go back in time to kill their grandfather, but the laws of physics would conspire to deflect the bullet or the thrusting knife.

    For you multiple universe fans out there, could this still be consistent with the many worlds theory in that all possible paths exist, but only those allowed by this solution?
     
    Last edited: May 16, 2003
  12. May 16, 2003 #11
    Ivan - that idea can quickly be debunked. It's just one science fiction idea of how time travel would work.

    Nevertheless, time travel still remains completely and totally impossible.
     
  13. May 16, 2003 #12
    If there is sarcasm implied in this, I've missed it, and I thank you for the apparent compliment.
     
  14. May 16, 2003 #13
    This illustration (of the billiard ball) is interesting enough to discuss, but it is not even an hypothesis. An hypothesis must be testable (at some future point). This is not only untestable, but utter (obviously fictitious) nonsense.
     
  15. May 16, 2003 #14

    Ivan Seeking

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    Please do so. [?]
     
  16. May 16, 2003 #15
    Mentat - it's a compliment, I'm never sarcastic, I'll just say it if I mean it.
     
  17. May 16, 2003 #16

    Ivan Seeking

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    Why do make faith arguments in a scientific discussion?
     
  18. May 16, 2003 #17
    You mean, debunk the idea? Did you happen to read the first post of the link I provided?
     
  19. May 16, 2003 #18
    I'm not making a faith argument. I made a simple, scientific, argument against the idea of backward time travel in the link that I provided (above). I call the illustration nonsense because it relies on something that cannot (unless my reasoning in "Why We Can't Go Back" fails) happen.
     
  20. May 16, 2003 #19
    Good point, I've noticed that about you.
     
  21. May 16, 2003 #20
    Ahh, now I know where all our conspiracy theories originate from. Its those bastards from the future...
     
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