Talk:A-level Physics (Advancing Physics)/Doppler Effect

Doppler Effect vs Time Dilatation ?

Is there any conceptual difference between the Doppler experiment and the experimental pattern described under “Time Dilatation” in the Special Relativity theory? In both cases a frequency generator is in inertial motion in respect to an observer. In both cases one computes the perception of the frequency by the distant observer… But contrary to the Doppler Effect where a red-shift or a blue-shift in frequency may be observed, Special Relativity only concludes to time dilatation in all cases. This does not look very consistent.

This immediately triggers a second question: is it legitimate for Special Relativity to invoke the Lorentz Transform in this particular context? If I understand correctly this transformation applies to the gaps in position and time between two events in a given inertial frame, and it delivers the corresponding gaps between the same events in another inertial frame. However, Special Relativity uses the Lorentz Transform to compute gaps between two events related to the observer’s life on the basis of gaps between two events relevant to the clock’s history. Moreover both pairs of events belong to the same "frame"; here I mean the same "convention" for representing the relative motion of the clock and the observer.Sugdub (talk) 21:56, 14 December 2009 (UTC)