Han Erim
February 18, 2019

Measurement of a speed of a signal going towards a moving target means testing the validity of Galilean Relativity Principle (and, at the same time, Special Relativity Theory). In this essay, this relationship between the two has been covered.

I will make use of a simple mechanism to cover the topic. We place a Signal Source that can move forward and backward on a ruler. We mount the target, which the signal will arrive at, on the edge of the ruler.

Figure 1

The figure below is the flowchart of the event taking place while the mechanism is working. The Signal Source, while moving to the right at v speed, emits a light signal; and in the final state, the signal reaches the Target.

Figure 2

Based on the information that Figure 2 provides, lets write down the speed of the signal for the Signal Source and the Target:
Relative to the frame of the motionless Target, the speed of the signal which is coming towards itself is c. 
Relative to the frame of the Signal Source that is in motion, the speed of the signal which is going towards the Target becomes c+v.

Figure 3

Lets link this topic to Galilean Relativity Principle. Lets assume that the event occurs within a Top Frame that moves at any speed and in any direction (Top Frame can be a ship, a plane, a train, etc.) According to Galilean Relativity Principle, the mechanism will not be affected by the movement of the Top Frame and will work in the same way.

Figure 4

We use a vehicle as Top Frame and we place the mechanism on the vehicle. Lets plan the movement of the vehicle this way: While the Signal Source moves to the right on the ruler at v speed, the vehicle moves to the left at the same v speed. In this case, relative to the observer that is outside the vehicle and on the ground, the Signal Source will remain motionless. On the other hand, the target will move to the left at v speed. Relative to the Signal Source, as the speed of the signal is c+v, the observer will measure the speed of the signal as c+v.

Figure 5

In this way, I have shown you that the speed of a signal going towards a moving target is different than c based on Galilean Relativity Principle.  

Figure 6 Conservation of Galilean Relativity Principle 


In this writing, based on Galilean Relativity Principle, I have shown what kind of result would be obtained in case we measure the speed of a signal that is moving towards a target that is in motion.

In Special Relativity Theory, the thesis Light speed is constant relative to all reference systems and it equals c. is used as base. This logic assumes that the speed of the signal is c, even relative to the frame of the source that is sending the signal. However, considering this speed as c is an obvious violation of mathematics (Figure 3). On the other hand, the speed of a signal that is going towards a target that is in motion has never been measured and has been neglected. Therefore, the measurement to be done will expose this mistake in the theory with all its clarity. The critical point is that, this mistake in the Special Relativity Theory has caused undesired results. I referred to this topic in my paper named "Invitation to the Light", which is attached. Please read it.

As can be seen here, once the Galilean Relativity Principle is logically acknowledged to be correct, there is no need even to perform the measurement. The mathematics of Electromagnetic Theory becomes (c+v) (c-v) mathematics. But the speed of a signal that is going towards a moving target must definitely be measured. The primary role of this measurement would not be testing Special Relativity Theory but would be putting the validity of Galilean Relativity Principle into test.

Can Galilean Relativity Principle be wrong? This is extremely unlikely. If Galilean Relativity Principle were wrong, it would eliminate the situation where the Top Frame is included in the discussion of the topic (Figure 4) and, in this case, all Physics Theories would fall down. Nothing would be left in our hands other than some mathematical equations whose correctness would not be certain for us any more. I do not regard as possible such a great annihilation.

Measure the speed of a signal that is going towards a moving target. Please perform this measurement meticulously under best conditions. You are measuring the oldest and the most established principle, Galilean Relativity Principle.

Thank you for reading. 
Han Erim

Galilean Relativity Principle: The fundamental laws of physics are the same in all frames of reference moving with constant speed with respect to one another.

Galileo Galilei (1565-1642)

This article named Measurement of the Speed of a Signal Going Towards a Moving Target and Galilean Relativity Principle" is registered at Istanbul, Beyoglu 37th Notary of Republic of Turkey with No: 03483 and Date: 18/February/2019.