This document contains comments about the document "Lorentz ether theory" in Wikipedia
• The text in italics is copied from that url
• Immediate followed by some comments
In the last paragraph I explain my own opinion.

### Introduction

The article starts with the following sentence.

### 1.1 Basic concept

Contrary to Clausius, who accepted that the electrons operate by actions at a distance, the electromagnetic field of the aether appears as a mediator between the electrons, and changes in this field can propagate not faster than the speed of light.
In a sense there is nothing wrong to link all electromagnetic phenomena to the speed of light or better to the speed of radiation. However that does not mean that this speed is constant.
A fundamental concept of Lorentz's theory in 1895 was the "theorem of corresponding states" for terms of order v/c. This theorem states that a moving observer with respect to the aether can use the same electrodynamic equations as an observer in the stationary aether system, thus they are making the same observations.

### 1.3 Local time

An important part of the theorem of corresponding states in 1892 and 1895 was the local time t'=t-vx/c^2, where t is the time coordinate for an observer resting in the ether, and t' is the time coordinate for an observer moving in the ether.
To apply the formula t'=t-vx/c^2 is relatif easy.
The problem with this formula is how do you measure v and how do you measure c. In fact in order to measure these quantities you need at least one clock and the behaviour of such a clock is the subject of the formula.
When v = 0 the formula is simple, but how do you know that v = 0?
While for Lorentz length contraction was a real physical effect, he considered the time transformation only as a heuristic working hypothesis and a mathematical stipulation to simplify the calculation from the resting to a "fictitious" moving system.
For Lorentz length contraction was a real physical effect. The question is if that is currently also the accepted opinion.

### 2.1 Constancy of light

Already in his philosophical writing on time measurements, Poincaré wrote that astronomers like Ole Rřmer, in determining the speed of light, simply assume that light has a constant speed, and that this speed is the same in all directions.
From a practical point of view, and for most day by day applications, this seems logical. However it may not be true, specific when large distances are involved. The problem is to demonstrate this.
Without this postulate it would not be possible to infer the speed of light from astronomical observations, as Rřmer did based on observations of the moons of Jupiter.
This immediate demonstrates how difficult it is to calculate the speed of light.
Poincaré went on to note that Rřmer also had to assume that Jupiter's moons obey Newton's laws, including the law of gravitation, whereas it would be possible to reconcile a different speed of light with the same observations if we assumed some different (probably more complicated) laws of motion.
This immediate demonstrates how clever Poincaré was.
Poincaré also noted that the propagation speed of light can be used to define simultaneity between spatially separate events. However, in that paper he did not go on to discuss the consequences of applying these "conventions" to multiple relatively moving systems of reference.
The problem is in the first sentence namely that it is very difficult to define "universal" simultaneity using light signals. The problems are that not all observers have the same speed relative to the same light signal.

### 2.3 Aether

Also Lorentz argued during his lifetime that in all frames of reference this one has to be preferred, in which the ether is at rest. Clocks in this frame are showing the "real“ time and simultaneity is not relative. However, if the correctness of the relativity principle is accepted, it is impossible to find this system by experiment.
What Lorentz should have argued that the Universe at large constitutes a frame at rest. It is in this frame that events can be simultaneous. Ofcourse it is very difficult locally to find this frame globally.

### 3.1 Special Relativity

Einstein identified two fundamental principles, each founded on experience, from which all of Lorentz's electrodynamics follows:
The question is what means: "founded on experience"?
"based on experience" sounds better. Does this mean "common sense"? But it does not mean based on experiment.
1. The laws by which physical processes occur are the same with respect to any system of inertial coordinates (the principle of relativity)
The problem which such a law is that it depends on the definition of "inertial coordinates". This indirect implies that the law is not always applicable. So what is than the practical purpose?
2. In empty space light propagates at an absolute speed c in any system of inertial coordinates (the principle of the constancy of light)
The same problem as above. What is the definition of "inertial coordinates"?
This defintion raises serious doubts if the speed is always c. For example in a gravitational filed.

### 3.4 Priority

Some claim that Poincaré and Lorentz are the true founders of special relativity, not Einstein.
The issue is exactly: what is Special Relativity physical?
When SR is about the behaviour of moving clocks, which predicts that the ticking rate of a clock is not constant as established by experiment, than I expect that even Isaac Newton would not have any problem to accept that.
When SR is about length contraction and assuming that this is a physical effect, than I expect that Isaac Newton would raise some doubt.

### 4. Later activities

Comments on the article Quantum_and_classical_clocks.htm "Einstein’s quantum clocks and Poincaré’s classical clocks in SR" by Yves Pierseaux

### Reflection

There are two major problems regarding the speed of light.
The first problem is how do you calculate the speed of light.
The second problem is how do you establish IF the speed of light is constant.
• Regarding the calculation you should follow the following rules:
You should calculate the speed independent of the speed of the observer over a fixed distance.
The only way to do that is sending a signal from A to B and back to A with a clock at A. The distance A to B should be fixed, that means they should be physical connected.
• A whole different problem is if the speed of light is constant.
In order to decide that instead of light we use a ball (in reality 2 balls) which we drop from a tower and which bounces back.
When you drop a ball from a tower we know from experience that the speed is not constant. The cause is gravity.
Figure 1 below shows the path of two balls "1" and "2". In Figure 2 this is the same.
The horizontal line with the dots identifies half the height of the tower. Here the two paths split.
 ``` t0 t1 t2 -x 2 1 2 . x 2 x 2 . - x 2 1 2 2 . . -...x.1...2.... . . - . . -----1-------- Figure 1 ``` Both balls are dropped at the same moment, but the height that each ball falls is different. Ball "1" falls the full height and than bounces back. Ball "2" drops half the height of the tower, bounces back. This process is repeated once. Ball "1" is dropped at t0. First the ball identified with the number x, because the path of both is identical. The point 1 at the bottom is the moment when ball "1" bounces back. There after the path is identified with the letter 1. Ball "1" is back at the top of the tower at t1. Ball "2" is also dropped at t0. First the ball identified with the number x, because the path of both is identical. Ball "2" bounces back and is identified with the letter 2. There after the whole process repeats itself Ball "2" is back at the top of the tower at t2. ``` t0 t12 -x 2 x . x 2 2 x . x 2 2 x - x 2 2 x . x 2 2 x . x 2 2 x -......x...........x........ . 1 1 . 1 1 - 1 1 . 1 1 . 1 1 -------------1-------------- Figure 2 ```
What Figure 1 clearly shows that the arrival time of the two balls (indicated as t1 and t2) is different.
Figure 2 shows the same experiment but now that the arrival time (indicated as t12) is the same
The result of an actual experiment is that the arrival time is different. Implying that the speed of the ball "1" in the first leg is slower than in the second leg. That means there is acceleration involved and the cause is the force of gravitation or gravity.

The point is what happens when instead of a ball a lightsignal is used (or photons). This light signal is reflected for signal 1 at the bottom (with a mirror) and for signal 2 with a mirror at half distance. For signal 2 the process is repeated.
The problem is that it is impossible to perform such an experiment in reality. The question is what do you, the reader, expect as the outcome.

IMO the most probably outcome is that the arrival time is different. This leads to the conclusion that the speed of photons is influenced by gravity. This is in line with the observation that the path of the photons is not straight but bended close to mass.

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