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Time travel to future

  1. Apr 13, 2016 #1
    Theoretically you can travel back in time by moving faster than the speed of light, or the universal speed limit. Is there a minimum speed? 0. But with gravity you would be moving, so if you move against gravity relative to yourself you are moving. So if there was a place in the universe free of a gravitational pull or the gravitational pull was the same from all sides you would be moving at a true 0. So my question is; can you stop moving and if so is that the minimum speed, and if it is what would time do? would it take you to the future?
  2. jcsd
  3. Apr 13, 2016 #2


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    Gold Member

    You seem to believe that there is such a thing as absolute motion. There is absolute acceleration, but other than that, all motion is relative so "moving at 0" is not a meaningful concept except in relation to some other object.
  4. Apr 13, 2016 #3


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    Staff: Mentor

    Kinda sorta.... Google for "tachyonic antitelephone" to see how faster-than-light travel can be described as going backwards in time. (If you find the description of the anti-telephone complicated or confusing, or if any of the math is even slightly unclear.... That will be a hint that you should spend some time with a good basic textbook - I recommend Taylor and Wheeler's "Spacetime Physics").

    The quick answer is that of course you travel into the future, whether in a gravitational field or not - I'm doing it right now, travelling into the future at a rate of one second every second.

    However, you have a more serious misunderstanding here. All speeds are relative; it never makes sense to say that something is moving without saying what it is moving relative to. Thus, there cannot be anything special about speed zero - it just means that whatever we're talking about is not moving relative to its immediate surroundings. I'm sitting in a comfortable chair right now. Am I moving? Not according to someone in the same room watching me... But I'm moving at several kilometers a second relative to a Martian astronomer resting comfortably in his chair on Mars and watching me through a telescope. You have to really seriously wrap your mind around this notion that all motion is relative, that there is no moving and not moving, before you will be able to understand relativity.

    As this thread is based on a number of misunderstandings, it is closed and will remain closed.
    Last edited: Apr 13, 2016
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