The Voice of Allan Zade
It is time to revisit well-known physical experiments. All explanations that you can see above in this article are given regardless of any particular disturbance-to-medium combination. Therefore, all of them are correct for any disturbance-to-medium combination.
In the acoustic case, Figure 1 describes any acoustic experiment in any acoustic environment. For example, you are a passenger on a moving train. You hear a pitch from the locomotive of that train. You notice the same tone of that pitch that coincides with the tone at the station that you heard in case of a stopped train. That happens because you have zero relative speed in the acoustic medium (air, in both cases) with respect to the sound source.
Another example comes from cars. Suppose now this. You are a car driver. You drive the vehicle at a certain speed on the street. Suddenly, another driver, who is driving his car at the same speed as you, not far from your car, uses the horn on his car. You hear a familiar sound because both vehicles have zero relative motion regarding each other. Figure 1 shows that case as a possible direction O-C2.
Despite sound wave distortion by the car-to-air relative motion of another car, you do not notice any deviation of sound frequency (tone). That happens because your motion relative to the same medium (air) restores the wavelength of the sound. In other words,
There are two elements of the Doppler Effect in the case of zero relative speed of the observers to each other.
Both elements taken together make an illusion of the same length of a wave that it has in the case of a static location for both observers in a given medium.
- Allan Zade
In other words, the Doppler Effect exists for moving observers. However, in the case of their motion in the same direction with the same speed regarding the medium, DE does not reveal itself to any observer.
In other cases, when observers have different velocities regarding the medium (in magnitude and/or direction), they detect DE. In the “classical” explanation, DE appears as a result of the relative motion of the observers regarding each other. That explanation is not entirely correct, as explained above. The distortion of a wave appears at both sides of observation. Moreover, the active observer (who makes a wave) also makes a physical distortion of a wave in a given continuum. Another observer (a passive one) only interacts with the distorted wave through his observer-to-medium relative motion. As a result, he “restores” the wavelength (and its frequency) by physical observation of its frequency, as explained above.
It is worth noting one more aspect of wave propagation.
Waves are not inertial entities. Therefore, any motion of a wave source regarding any given medium does not change the speed of wave-to-medium relative motion
- Allan Zade
Figure 1 shows it as the radius of sphere S.
In the case of optical experiments, all aspects remain correct for the same reason that initial explanations do not depend on any particular disturbance-to-medium combination. Therefore, two (or more) observers who keep identical velocities regarding the z-continuum do not detect any Doppler Effect. Is it possible to keep such identical velocities in the z-continuum where no external reference exists?
Yes, it is quite possible. In that case, the observers have to be bound to "a rigid reference frame" that keeps a constant speed of the frame to the z-continuum relative motion. As a result, all observers maintain the same velocity with respect to the z-continuum. A straightforward example of such a condition is observers on the Earth's surface. All of them have the same velocity of observer to z-continuum relative motion because of Earth (or the reference frame) to z-continuum relative motion.
That aspect created a significant illusion from the beginning of research on EM-radiation propagation and light waves. For example, you have a radio receiver. You listen to a radio transmission coming from a local broadcast station. You often hear something like this. “Listen to us on frequency of (a given number) Kilohertz (or Megahertz).”
You believe that the frequency of an EM wave emitted by a broadcast station is the same as mentioned on the display of your receiver. That is correct until you measure only the frequency of the EM-signal.
As explained above, in this case, the physical wavelength in the z-continuum does not match its wavelength in the z-continuum when the Earth is at a static location in the z-continuum (which is physically impossible).
Moreover, you believe that physical EM-wave keeps the same length according to their frequency in all directions. That is one of the most extraordinary delusions of humankind.