Doppler effect triggered by the motion of the observer:

https://youtube.com/watch?v=bg7O4rtlwEE

The speed of the light pulses as measured by the stationary observer is

c = df

where d is the distance between the pulses and f is the frequency measured by the stationary observer. The speed of the pulses as measured by the moving observer is

c'= df' c

where f' f is the frequency measured by the moving observer.

Einsteinians clearly see that the frequency and the speed of the light pulses vary proportionally for the moving observer, but believe that only the frequency varies - the speed of the pulses gloriously remains constant. Such a behaviour was explained long time ago:

Ignatius of Loyola: "We should always be prepared so as never to err to believe that what I see as white is black, if the hierarchical Church defines it thus."

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Pentcho Valev