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Help explain twins paradox.?

Assume ships A and B synchronize clocks first and then they take off in opposite directions with a high relative speed. It is my understanding the observer on ship A says the clock on ship B is running slowly and the observer on ship B says the clock on ship A is running slowly. If the two ships manage to dock together the next day, would the clocks on both ships be the same or would they be different? Is it possible for one ship to age more or less than the other?

I am trying to better understand the twins paradox. If a twin takes off in a ship, wouldn't that twin observe the clocks on earth ticking more slowly while (during the same trip) the twin on earth observes the twin's clock aboard the ship moving more slowly?

Hopefully someone can help clarify what I am missing. Thanks in advance.

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  • 9 years ago
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    Your conclusion about each observer seeing the time running more slowly for the other traveler is based on inertial reference frames, i.e. each one is moving at a constant speed relative to the other - no acceleration allowed. If they each travel at that constant speed, then it is true that each will see time running more slowly for the other guy, and they will both be right. They cannot dock the next day to compare clocks, since that would would require an acceleration on the part of one or the other or both. In this case, neither one can tell which one is "moving" and which one is "standing still." Each reference frame is equally valid, and the observations for each are therefore equally valid.

    The classic Twin Paradox involves one twin that does not accelerate and another who does. One stays at home, the other leaves, accelerates, travels at high speed, and then returns. This establishes one as the inertial reference frame and the other as the one who moves relative to that frame. In this case, the integration of speed changes over the entire journey of the "moving traveler" will result in his clock having run more slowly upon their comparison at the end of the trip. In other words, the "moving traveler" will be younger upon their reunion.

    The case that you described is different. If each traveler accelerates identically in opposite directions, and then returns to meet the other in an identical fashion, then neither frame is inertial, but each will encounter identical relativistic effects as compared to the other. So when they meet again, their clocks will be identical.

  • 9 years ago

    In twins paradox only one ship would take off but since both observe the other traveling away (Since the ship appears relatively stationary to the person on it and they are observing it as though everything else was moving away) the other twin would have appeared to age more rapidly (or themselves age more slowly, either way) based on the assumption that spacial relativity has an affect on that.

    That assumption is based off an experiment done with clocks and airplanes across the world with variation due to earth's rotation accounted for. What they didn't account for however is unknown rotation. It is theoretically likely that entire galaxies have rotations around each other that weren't accounted for though, which could explain the difference making this entire thought experiment pointless.

    Anyway, assuming the spacial relativity age difference thing isn't complete BS it could be explained by the fact that one is physically moving and under additional physical forces of movement, acceleration, deceleration, etc that the other isn't thus not making it a true paradox and only one observing other as having aged more rapidly.

    Given equal movement in opposite directions completely defeats the purpose of the thought experiment.

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