Red shift and the train thought experiment

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It seems there is usually no mention of "redshift" when train thought experiment is used to teach relativity. Is there a reason for not bringing redshift (blueshift) into the experiment?
 
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It isn't brought in because it isn't needed. Why do you think it is?
 
russ_watters said:
It isn't brought in because it isn't needed. Why do you think it is?

Because (I thought?), there's mentioned made in this experiment on how the measurement of light from a train is different than that of the sound from a train. But, it seems (?) they both have the doppler effect.

Is then the important difference that the person on the train has to add the speed of the train when measuring the speed of sound but not when measuring the speed of light?
 
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