The formula

(frequency) = (speed of light)/(wavelength)

says that a frequency shift entails either a wavelength shift or a speed-of-light shift.

If the speed of light is invariable, as Einstein postulated in 1905, the implication is

"Any frequency shift entails a wavelength shift".

This implication is almost obviously false. Here is a counterexample - the wavelength (distance between the light pulses in this scenario) is independent of the speed of the receiver:

Albert Einstein Institute: "Here is an animation of the receiver moving towards the source:

http://www.einstein-online.info/imag...ector_blue.gif

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." Website: http://www.einstein-online.info/spotlights/doppler.html

Since the implication is false, the underlying axiom "The speed of light is invariable" is false as well.

If the wavelength of light is invariable, as future physics will have to postulate, the implication is

"Any frequency shift entails (is caused by) a speed-of-light shift".

It can be shown that the axiom

"The wavelength of light is invariable"

is correct when the speed of the light source changes, and also when light falls in a gravitational field.

Pentcho Valev