How much time is needed for the time travel?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Eagle9, Oct 16, 2014.

  1. Eagle9 Registered Senior Member

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    To whom exactly?

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    And what about the length of this moment? Is it equal to 1 second or less or more?


    Why it is difficult or impossible? If I depart from 2014 to 1914 I will take time machine with me (imagine that the compact one exist) and return to 2014 again. So there will be two separate voyages.
     
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  3. Motor Daddy Valued Senior Member

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    Time elapses continuously, cumulatively, infinitely! Elapsed time always increases, never decreases. It is impossible for elapsed time to decrease. If a stop watch reads 10 seconds and counting, it is not possible for time to elapse and decrease from 10 seconds of elapsed time to 9 seconds of elapsed time a duration of time later. It is retarded to think that if you travel fast enough you can go back to 1914. It is 2014 now, and there is nothing you can do to make it go from 2014 to 2013, instead of 2014-2015...
     
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  5. wellwisher Banned Banned

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    Say you make a small 1 minute movie with your video camera. We can play the movie backwards and return to the original time the movie began; rewind. This is sort of like moving back in time. But if you look at the clock in the room, while your rewind, the clock in the room continues to move to the future. The net effect is going backwards in time means going forward in time.

    Time is not like energy conservation, where energy lost one places is gained in another place. Rewinding the movie for one second, does not make the clock in the room jump ahead one-second. Time is not being conserved like energy in this scenario.

    If there was conservation of time (hypothetical) like energy conservation, going back in time would require any return to the future, mean a jump forward, further into the future so time is conserved; normalized to the present. The work around would require the time difference go into entropy; come back older to the present.
     
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  7. RajeshTrivedi Valued Senior Member

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    In fact its quite simple to find out the time from EH to singularity due to its free fall nature..actual solution which would involve travel from r = infinity, to r = 0 via EH will also lead to the same solution..

    since its a free fall, so no gravity dilation and hence second equation of motion is enough to find out the time...

    R = (1/2) gt^2 where g can be taken as = GM/R^2 (assumption that all the mass of M is confined to a sphere of R, but otherwise its a point singularity..!)

    this will lead t = 2R/c where R is the schwarzchild radius = 2GM/c^2...
     
  8. Motor Daddy Valued Senior Member

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    At t=0 (12 O'Clock) I start recording a movie. At t=60 seconds I stop recording. At t=72 seconds I rewind the tape, and it takes 3 seconds for the tape to rewind, hence when it's done rewinding it is t=75 seconds. At t=86 seconds I press play, and watch the movie for 60 seconds, and when the movie finishes it is t=146 seconds. I go to the store at t=13,786 seconds. It takes me 128 seconds to get to the store. I start my journey in the store at t=14,000 seconds. I shop for 11,000 seconds and return to my car at t=25,500 seconds. I return home at t=27,000 seconds due to traffic. At t=29,896 seconds I go to sleep. At t=39,567 seconds I wake up. At t=46,298 seconds I press rewind on the movie. It takes 3 seconds to rewind the tape, hence it's t=46,301 seconds when it's done rewinding. I press play at t=46,308 seconds, and it plays for 60 seconds, and finishes at t=46,368 seconds.

    At no time did time go in reverse, slow down, speed up, change rate, or do something crazy, illusionistic, or any other bizarre thing you can think of. Time elapsed continuously and cumulatively, just like it will infinitely!!
     
  9. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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  10. paddoboy Valued Senior Member

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    Correct! But if you were to stand at a safe distance from a BH, and watch me approach it, you will see my time as going slow.
    In effect, if I had the rocket power to return, You will have aged significantly more then me.
    An illustration of time passing at different rates.
     
  11. Landau Roof Registered Senior Member

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    Too many 'Ifs'. First of all, - no 'if' - I am standing, sitting and (sometimes) walking near or lying down a safe distance from a black hole right now, but all right, you must mean even closer. Next how are you going to approach closer than I am? If you had a rocket ship, you could. How am I going to see you? If I had a giant telescope, I could. If I cared enough to watch you slowly approach the black hole; I don't. I would have aged significantly more than you (if I had not forgotten all about your slowpoke ass; I have). If you had the rocket power to return - you're running up quite a rocket fuel bill there, aren't you, fellah?
    [heavy sigh] I know the OP realizes time travel is merely hypothetical, but I agree with Motor Daddy, if I understood him correctly. Time travel will only ever be possible in a forward direction, and we and all else proceed at it at a rate of sixty seconds per minute, sixty minutes per hour. Enough said.
     
  12. paddoboy Valued Senior Member

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    Time travel is not against the laws of physics and GR, and to any sufficiently advanced civilisation, it is possible...certainly very difficult [probably new physics] but possible.
    And yes forward time travel as understood, is more intuitive then past time travel.
     
  13. Landau Roof Registered Senior Member

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    Again too much fancy flying here - by which I mean flights of fancy. I know from reading your posts that you believe there is alien life elsewhere and that it may very well include advanced civilizations, and that you are hopeful that we ourselves may someday qualify as an advanced civilization (IMHO: if it weren't for those pesky stumbling blocks of being civilized, and then advancing!) Even still, 'not against the laws of physics and GR."; a whole "new physics" is a bit of a stretch. I agree with you on every point, but can we please slow down a little!

    In a couple of other threads we are all discussing the feasibility of colonizing, terraforming or just getting to Mars for 68 days. In another LM has announced that just maybe on Christmas ten years from now if they're super-good and do all their homework, for Xmas, Santa will bring them a portable fusion engine (which would help us with our Mars colonization), but come on! we should be working on biodegradable shopping bags and fuel- efficient hybrid cars. let's set our noodles to the sensible and doable before we head back to the future.
     
  14. Motor Daddy Valued Senior Member

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    I think I've explained to you before why traveling back in time is not possible, but you persist!

    Again, I am in NY and you are in Florida. We have a conversation on the phone and agree to each start traveling towards the other at exactly 12 O'Clock. Since we are in the same timezone our clocks are synched to the SAME time, Eastern Time!! I hop into a 70 GTO and you hop into your AMC Pacer! At exactly 12:00 we each start traveling.

    Now, according to you, it is possible for one of us to be at the others' position at or before 12:00. I repeat, that is impossible! For ANYTHING in the universe to move a muscle, even one tiny little centimeter, regardless of its initial velocity, time MUST ELAPSE past 12 O'Clock. Time can NOT go back to 11:59. Can NOT!
     
    Last edited: Oct 27, 2014
  15. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    (shakes head)
     
  16. Landau Roof Registered Senior Member

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    What does that mean? Like this?

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  17. krash661 [MK6] transitioning scifi to reality Valued Senior Member

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    Last edited: Oct 27, 2014
  18. paddoboy Valued Senior Member

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    Not really. All you have done is rattle off some pathetic irrelevant scenario....
    The number of "shakes heads"following your comment attests to that.
    Again, the laws of physics and GR, do not forbid time travel, either forward or backwards.
    And we do have a number of theoretical scenarios where both can be undertaken, by any sufficiently advanced civilisation.
     
  19. Motor Daddy Valued Senior Member

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    I just gave you a scenario. How do you propose you can get to my location at or before 12 O'Clock? You're the one saying it's possible, or that it's not impossible, remember? I'm the one saying it's impossible. Show me! Tell me how you beat the clock?
     
  20. paddoboy Valued Senior Member

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    Read my post....CAREFULLY:
    Again, the laws of physics and GR, do not forbid time travel, either forward or backwards.
    And we do have a number of theoretical scenarios where both can be undertaken, by any sufficiently advanced civilisation.

    Theoretically speaking, time travel either foward or backward could be possible via wormholes [another aspect of spacetime topology not disallowed by the laws of physics] and GR] Kerr type BH's and their ring Singularities.
    Of course backward time travel does have inherent problems re cause and effect.
    But perhaps by going back, and doing something to recreate the future, we would actually be recreating another time line.
    Perhaps Feynmans "Sum over Histories" concept has some application.
    Finally as originally stated....
    The laws of physics and GR, do not forbid time travel, either forward or backwards.
    And we do have a number of theoretical scenarios where both can be undertaken, by any sufficiently advanced civilisation.
     
  21. Motor Daddy Valued Senior Member

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    Again, you're full of it! A clock can never reduce time, ever! No matter how much you want it to! Just like if you are at a point in space, you can never travel to negative space. You are at a point in space! The only thing you can do is move a distance away from that point, which is a positive distance, not negative. if you move 5 feet away, then move back to it, you moved a total of 10 feet, not 0 feet. Duh? You are trying to claim it's possible to move negative feet!!! Same difference when you claim it's possible to go back to 1902.
     
  22. Enmos Valued Senior Member

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    Relative to your original spot you moved 0 feet. Duh?
     
  23. paddoboy Valued Senior Member

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