Consider a light source emitting a series of pulses equally distanced from one another. A stationary observer (receiver) measures the frequency of the pulses:
http://www.einstein-online.info/imag...ler_static.gif
The observer starts moving with constant speed towards the light source - the measured frequency increases:
http://www.einstein-online.info/imag...ector_blue.gif
The following quotation is relevant:
http://www.einstein-online.info/spotlights/doppler
Albert Einstein Institute: "By observing the two indicator lights, you can see for yourself that, once more, there is a blue-shift - the pulse frequency measured at the receiver is somewhat higher than the frequency with which the pulses are sent out. This time, the distances between subsequent pulses are not affected, but still there is a frequency shift: As the receiver moves towards each pulse, the time until pulse and receiver meet up is shortened. In this particular animation, which has the receiver moving towards the source at one third the speed of the pulses themselves, four pulses are received in the time it takes the source to emit three pulses."
That is, the speed of the pulses as measured by the moving observer (receiver) is (4/3)c. Einsteinians clearly see this but, if asked, would say that the speed of the pulses relative to the moving observer is c, not (4/3)c.
Similarly, Fermilab physicist Dr. Ricardo Eusebi demonstrates how both the speed of light (relative to the observer) and the frequency vary with the speed of the observer but then explains that only the frequency varies (the speed of the light doesn't):
http://www.youtube.com/watch?feature...&v=EVzUyE2oD1w
"Light frequency is relative to the observer. The velocity is not though. The velocity is the same in all the reference frames."
Ignatius of Loyola: "That we may be altogether of the same mind and in conformity with the Church herself, if she shall have defined anything to be black which appears to our eyes to be white, we ought in like manner to pronounce it to be black." x
Pentcho Valev