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Time machine possible or impossilble

  1. Mar 10, 2005 #1
    Hi everyone,
    Does any one of you believe that time machines or timetravel is possible because if it were possible we would already be familiar to one. Because someone would have travelled back in our time whom we could have seen. This has only one explanation that the man who would made the timemachine did not travel back in our time.
     
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  3. Mar 10, 2005 #2

    HallsofIvy

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    IF the person were to announce to the world that he had come from the future, yes.

    But he might have very good reasons for not doing that! How do you know that people have NOT come back from the future?
     
  4. Mar 10, 2005 #3
    Ya maybe the Ufo which r sighted sometimes are timemachines of somesort.
     
  5. Mar 10, 2005 #4

    SpaceTiger

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    A professor here claims that, according to current theory, you would need something like a galaxy's worth of energy to go back a second...but it is possible.

    As for the guy you're referring to, he's a nut.
     
  6. Mar 10, 2005 #5
    John Titor has traveled to our time. Look him up, must be possible hehe.
     
  7. Mar 10, 2005 #6
    interesting thing, what about the pattent of a time mechine? lol somebody could go back in time and steal the pattent lol, just a monyy-pythonish style thing that happened to play out in me head.

    Adam
     
  8. Mar 10, 2005 #7
    i think it was steven hawkings who said that if that was possible then people from the future would be likely to be all around us, which might actually be.

    accoding to einstein, it'd be impossible as time has only one dimensuion and one direction.

    however i beleive, and i THINK that quantum theories say that chance can mean that this never happens in our timeline, while in others it does...
     
  9. Mar 10, 2005 #8
    Not only is it possible to build one, one has been built, used, but now it is retired. They called it the mir space station. Some russian spent a month I think it was on the station and went back in time a 50th of a second.
     
  10. Mar 11, 2005 #9
    are you sure you don't mean that time was slower in his frame of reference by 1/50th of a second due to relativity? i highly doubt that he went back in time....
     
  11. Mar 11, 2005 #10
    He didn't go back in time, his time was slowed due to relativity.

    And the question of whether 'time-travelers' are all around us is effectively the same question as:

    "Have things happened that we don't know about, and have no way of finding out about?" ...and that question pretty much is unanswerable
     
  12. Mar 11, 2005 #11
    I see it in this way:

    When you travel in time, you get at such a speed that you can't be seen by anybody. You can see everything, but you can't affect the world in any way. You can't touch things or talk to people. Even if you stop the machine (for me a time travelling machine could only be done if it can achieve faster speed than light) you will come back to your time. So your like watching tv, but travelling in time and backwards.
     
  13. Mar 11, 2005 #12
    exactly what i was gonna say, wasnt to sure though, also, as time is sperate from space, i doubt that speed could make you travel in time, ultimatly, from what i know, time travel is a long way ahead
     
  14. Mar 11, 2005 #13

    JesseM

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    Actually, Einstein's theory of general relativity (which explains gravity in terms of matter/energy causing spacetime to curve) does allow backwards time travel in certain unusual spacetimes, like a rotating universe or a universe containing a "wormhole". For example, see this article by physicist Paul Davies:

    http://www.sciam.com/article.cfm?articleID=0004226A-F77D-1D4A-90FB809EC5880000

    However, most physicists would probably guess that when general relativity is combined with quantum physics to produce a theory of quantum gravity, the possibility of backwards time travel will be eliminated. Here's an article on how string theory (a candidate for a theory of quantum gravity) might eliminate the possibility of time travel:

    http://groups-beta.google.com/group..._frm/thread/770fe3895b4bc0cc/fc5fefa6578822ee (for some background on the 'holographic principle' discussed in this article, see here)
     
  15. Mar 11, 2005 #14

    Pengwuino

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    I remember seeing something about it being only possible to travel back in time as long as the time machien exists in the time frame you travel back into. Like... if you live in 2005 and a time machine is built, you cant go back to 2004 but if you wait till 2025, you will be able to go back in time but only until 2005. Dont remember the explanation though...
     
  16. Mar 11, 2005 #15
    Actually, the only thing you would see is the very thing you LAST saw. The abilty or answer to travel backwards currently eludes me. However, for forward travel to feasible the vehicle and everything in it would have to effectively stop moving. All matter, electrons, atoms and photon emmisions must suspend in order to induce a sort of temporal stasis that will "pause" the vehicle (un-noticeable to occupant) in the normal sense of "time" and cause it to shift in and out of the fourth dimension (which is NOT time) as the particles must remain in motion by any means necessary as they do along the XYZ axes in the 1,2, and 3rd dimensions. I'm currently studying the dynamics of reverse travel although I highly doubt it's feasible. I need to further study blackholes, theorised wormholes, and string theory to draw any conclusion. If a wormhole is actually a gateway to the past it would have to take you (presuming the trip to be survivable) to the presice point in the 4 dimensions that it was created. That could be billions of years earlier and trillions of AU away from your current position. Still wanna make that trip? If you did you would most likely be scattered across the universe as you exited the wormhole as it was created; surely not surviving. Sorry for any spelling or grammar mistakes. I rushed this but it should be accurate.
     
  17. Mar 11, 2005 #16

    JesseM

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    That would be true if it were possible to travel through time using a wormhole. According to special relativity, if you one of two twins makes a journey at near light speed away from earth and then returns, the twin who made this journey will be younger than his twin brother when he returns. But if each twin is carrying one mouth of a wormhole, when they look through it they will see the other twin aging at the same rate as themselves. So if both twins were 20 years old when the travelling twin departs, and when the travelling twin returns he is 25 while the earth-twin is 70, then if the travelling twin looks through his end of the wormhole he will see the earth-twin as he was at age 25, 45 years in the past...so by hopping back throught this mouth he can actually journey 45 years in the past. But this method won't allow him to go back to a time before the two twins travelled apart and a time difference was introduced between their wormhole mouths. This is discussed a bit more in the article by Paul Davies I posted above.
     
  18. Mar 12, 2005 #17
    time is just something exist in our head. It doesn't really exist so you can't really manipulate it.
     
  19. Mar 12, 2005 #18
    i believe that everything in nature is determined
    and we live according to natural laws of our complex Universe.
    travelling forward and backwards in time needs few equations to be set up
    by then, we will surely be able to do such a thing which now it's hard to imagine!
     
  20. Mar 12, 2005 #19
    It is highly impossible that time machine would be ever created that is because :

    1) Time itself may not exist.

    2) There is no natural occurance of time travell phenomenon of an object or atleast information.
     
  21. Mar 12, 2005 #20
    Really,

    ??Then how come I havent yet seen a picture of this cosmonaut with a handshake with his own self from past ?

    That was not time travel, it was slowing down of all the atoms of an object called MIR.

    The real measure of time travel will be when we get a copy of an object from another time simultaneously. I hope U dont ever forget that before making such a statement again, unless U r from a previous time I guess.
     
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