The Aurora Experiment
The Aurora experiment shows the anisotropy of light (electromagnetic radiation or waves) propagation in the medium. It does not determine the speed of light in different directions; it shows only the phenomenon itself.
Suppose now that the observer likes to conduct an Aurora Experiment. He takes two identical modern atomic clocks with cesium oscillators (or better clocks with optical oscillators, ref. #1). He sets them up at a given distance from each other at points M and N. That distance is supposed to be five kilometers. The following picture shows that case.
Aurora Effect
The observer turns both clocks on. Both clocks start operation. That means this. Their oscillating devices (oscillators) starts to make oscillations. Those oscillations come to internal counting devices of both clocks. Those counting devices counts incoming oscillations. That is enough to conduct the Aurora Experiment.
The observer pushes the button that starts the emission of the signal (electromagnetic disturbance of the medium, electromagnetic radiation, light, etc.). The signal, in the form of waves, starts propagating in every direction, as explained above. At the same time, the atomic clock determines its indication and keeps it inside the clock as value M1.
The disturbance (in the form of a signal) propagates through the medium for some duration. It reaches the clock N when the clock has indication N1. The experiment ends. Both clocks exchange their indications. The observer compares those indications and comprehends this.
The signal left the clock M when it had an indication M1. The signal comes to the clock N when it has indication N1.
The observer calculates the Basic Difference of Clock Indications or BDCI value as N1-M1.
The observer sends another signal. In that case, the signal leaves the first clock when it has indication M2 and reaches the clock N as soon as it shows indication N2. The observer calculates BDCI again as N2-M2 and sees the same value of BDCI in the next experiment.
It looks obvious to the observer because he uses two identical clocks. The distance between the clocks also remains constant during the experiment. Hence, the duration of signal propagation remains constant in both experiments.
As a result, the number of oscillations of clock M counted between events M1 and M2 becomes equal to the number of oscillations counted by the clock N between two consequent events of signal emission (M2-M1) and detection (N2-N1). Moreover, the BDCI value remains constant in both cases.
Everything looked fine for a while. The observer decided to conduct measurements every quarter of an hour. After 15 minutes, he conducted one more measurement and possessed values M3 and N4. To his surprise, the value of N4 became greater than the expected value of N3.
The observer comprehends this. The Earth, with all elements involved in the experiment, moves in the medium and rotates regarding that medium. The duration of signal propagation shows some deviation as soon as the angle of rotation becomes enough to detect it. Strictly speaking, a difference in 1 oscillation is enough to detect that phenomenon.
The observer continues his experiments. Each time, he has a different value of NX that does not match the first experiment. In other words, the difference in clock indications becomes unequal to BDCI and changes slowly and continuously. After some time of observation, it reaches its maximal value of N6 and starts slowly to come back again. The observer notices this. The full period of changes is equal to the Sidereal rotation of the Earth (23 h 56 min 4.0905 s). He also notices points when it reaches mean values.
The observer calculates another BDCI when the first reaches its mean value and then draws a plot of deviation.
The plot shows this. The new BDCI becomes equal to the difference of clock indications N5-M3 as soon as the Earth takes orientation P0. After that, the difference of clock indications rises until it reaches the minimal value of X1. Clocks show that value as soon as the Earth takes orientation P1.
After that, the deviation slowly increases until it reaches the maximal value of X3 (the experiment's maximal difference of clock indications). Point X3 coincides with point P3 in the figure. At that time, the Earth takes orientation P3.
After that, the deviation slowly decreases until it reaches its mean value of X4 when the Earth takes orientation P4. The circle of deviation starts all over again after that point. The observer understands this.
The signal keeps the same duration of propagation between two clocks set at a given distance from each other in case of their static location in the medium.
The signal shows a different duration when such clocks move through the medium or change their orientation regarding the direction of their motion.
- Allan Zade
That slow wave-like deviation in a plot looks like a rare event of the Aurora Effect, which is observable in the sky of polar areas of the Earth. It is a tremendous and awe-inspiring phenomenon. The following figure shows an example of it.
Aurora in the sky
The explained phenomenon is named after that because of a similar slow nature of changes looking like waves.