Twin Paradox: Earth-Twin vs Space-Twin Aging

bino
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The Twin Paradox: If a twin on a rocket travels at high speed for a while, and then returns to the Earth, the Earth-twin would have aged much more than the space-twin. But isn't it just as valid to say that the Earth is moving away from the rocket? Then the situation would be switched. Why would the astronaut return to find the Earth-twin aged far more, and not the Earth-twin find the astronaut aged much more?
 
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The simple answer is that dynamic frames are in general not equivalent - the stay at home twin remains in one inertial frame (no accelerations are involved). The traveler experiences acceleration when he starts, and depending upon the version of the problem, he will experience either acceleration or a change of frames upon turning around.
 

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