I have a unclear problem about time travel:(adsbygoogle = window.adsbygoogle || []).push({});

As you all know,when a spaceship move pass earth with the speed nearly c, the observer will regconise that the watch on the spaceship is moving slower than his own clock.

However, to the astronaunt who is on the spaceship, what he saw is the Earth is moving away from the Spaceship,therefore he has to experinence that the clock on the Earth has to be slower than his own.However, that's not correct according to the twin paradox because it'll be impossible to say which one is older.

I have an explanation that using the Doppler effect, you will have different time for the astronaunt and the obsever.Suggest that at time t the spaceship sends a light signal to the earth and it bounces back to the space ship after it travelled a distance x.To the obsever,he has travelled a distance y.Because c is a constant,therefore,x/t1(t1 is the time for the spaceship to cover that distance) has to be the same as y/t2(t2 is the time for the Earth to cover that distance).Assume that x>>y because the speed of the space ship is closer to C, i will have t1>>t2.That is wrong but i can't correct it myself.

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# Time problem

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