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What if light clock experiment was done on top of train?

  1. Jul 25, 2009 #1
    If the light clock was on top of the train, it wouldnt be in a inertial system. If a table tennis game was played inside the train, the ball would move as if played on the platform. But it wouldn't be possible ontop of the train.
    Does the light react the similarly to a table-tennis ball or is a photon too small to be affected? So would the observer on the platform see the light trail behind the train?

    If the light clock theory doesn't work or is effected in some way (i'm not a brilliant scientist so i have no clue what would happen), what would happen if the train, after some time of travelling, was suddenly upgraded into a open-patio-class seating carriage i.e. the roof and walls of the train was suddenly ripped off? Will the time difference just suddenly dissappear?
  2. jcsd
  3. Jul 25, 2009 #2

    Doc Al

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    Staff: Mentor

    Why not?
    Only because there would be air rushing by. Put the same conditions on the platform (have air rushing by at the same rate) and the game would look the same.

    No. As long as the speed of the train remained the same, time measurements between train and platform would have the same relationship.
  4. Jul 25, 2009 #3


    Staff: Mentor

    Hi wdai03, welcome to PF,

    I am afraid that your premise is mistaken. The top of the train is also a inertial coordinate system in every way that the interior of the train is.

    I think you are confusing a frame being inertial with the air being at rest in that frame.
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