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Thread: how come ????

  1. #1 how come ???? 
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    a simple question that was running through my head lately: if according to Einstein s general relativity one traveling faster than the speed of light would be able to travel back in time how is it that when u travel near the speed of light u would be traveling forward in time so in the first case u travel to the past while in the second case u will travel back in time


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  3. #2  
    Quagma SpeedFreek's Avatar
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    Because, (and this is highly simplified) IF you could travel AT the speed of light, time would come to a stop for you.


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    Forum Ph.D.
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    that confused me. if you travel at c, you would be in a constant now meaning you eliminated the past and the future. but, you would go forward compared to someone at a lower c and so can be backtracked; but you can't go backwards.
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    Forum Freshman WaterWalker's Avatar
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    Quote Originally Posted by curious mind View Post
    that confused me. if you travel at c, you would be in a constant now meaning you eliminated the past and the future. but, you would go forward compared to someone at a lower c and so can be backtracked; but you can't go backwards.
    Curious mind, I believe you are forgetting to balance the equation. This is not so much time travel, as it is time viewing. As you are moving away from the Earth, and it being at the speed of light, that "light-moment" (don't know how else to say it) will be traveling the same speed as you. Thus giving the impression of time travel. However, the object that is in front of you (say a planet around a star 50 lightyears away), it's light will be moving "faster" than the speed of light as you move through it's light. So, as a result, the time on that planet seems to speed up. Once at the planet, turn around, and the same thing happens. This is how I understand it. (I never did get the Twins Thought Experiment. Can someone maybe help me understand it. Thanks.)
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    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by WaterWalker View Post
    However, the object that is in front of you (say a planet around a star 50 lightyears away), it's light will be moving "faster" than the speed of light as you move through it's light.
    No its light will be moving at c. The speed of light is a constant for all observers.
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    Forum Freshman WaterWalker's Avatar
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by WaterWalker View Post
    However, the object that is in front of you (say a planet around a star 50 lightyears away), it's light will be moving "faster" than the speed of light as you move through it's light.
    No its light will be moving at c. The speed of light is a constant for all observers.
    I do agree with you. The light coming from the object (planet, in this case) will be a constant. But, you are moving at about 300 000km/s towards the object. The light from that object is moving at 300 000km/s towards you(opposite direction). Won't that equal 600 000km/s percieved speed? To try and make it easier (or more difficult, ), in this analogy, you are moving away from planet Earth at c, and toward planet x at c. Lets call that a northerly course for simplicity. The light from planet x is moving towards you in a southerly direction at c. Because it's opposite directions, won't it add the speeds? Theoretically speaking. Or am I being a dumbass again? (My brain isn't working to well right now. Graveyard shift. )
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    Genius Duck Moderator Dywyddyr's Avatar
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    Because of time dilation and length contraction any measurements made on the ship will be "different" (i.e. not according to a "stationary" frame) - that's why, at relativistic speeds, you can't just add the two speeds.
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    Forum Freshman WaterWalker's Avatar
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    Quote Originally Posted by Dywyddyr View Post
    Because of time dilation and length contraction any measurements made on the ship will be "different" (i.e. not according to a "stationary" frame) - that's why, at relativistic speeds, you can't just add the two speeds.
    Ah, yes. True. Now I'm the one forgetting the variables. . Forgot about the effects of that speed. My bad.
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