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Mar9-12, 08:22 PM
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Quote Quote by Nugatory View Post
The mechanism that moves the needle is the same in all frames of reference - what's different is the speed at which all mechanisms, including that one, appear to operate when viewed from different frames of reference. Use a mechanical clock operated by a pendulum, and the moving observer will measure a different speed for the pendulum, and hence a different slower tick rate for the clock, than will the observer at rest relative to the pendulum.
Einstein said a balance clock is preferred. A pendulum clock is dependent on gravity and not good.