# Introduction

##### 5 minutes • 1036 words

## Table of contents

The aberration of light and the related optical and electrical phenomena seems to provide us a means of determining the absolute motion of the Earth, or rather its motion, not in relation to the other stars, but in relation to the ether.

Fresnel had already tried it. But he recognized that the Earht’s motion does not alter the laws of refraction and reflection.

Similar experiments were done:

- a telescope filled with water. This considered only terms of first order in respect to aberration
- Michelson considered the square of the aberration becoming sensitive

These all failed and gave a negative result.

It seems that this impossibility of demonstrating an experimental evidence for absolute motion of the Earth is a general law of nature.

This leads us to admit this law – the Postulate of [Poincare] Relativity – without restriction.

This postulate, is up to now in accord with experiments. These may be either confirmed or disproved later by more precise experiments.

What are its consequences?

Lorentz and FitzGerald introduced the hypothesis of a contraction undergone by all bodies into the direction of the motion of earth and proportional to the square of aberration.

This Lorentz contraction would account for the the experiment of Michelson and others.

The hypothesis would become insufficient, however, if one were to assume the postulate of relativity in all its generality.

Lorentz modified it in order to put it in perfect agreement with this postulate. He succeeded in doing so in his article entitled Electromagnetic phenomena in a system moving with any velocity smaller than that of light (Proceedings de l’Académie d’Amsterdam, May 27, 1904).

My results are in agreement with those of Lorentz on all important points.

## Lorentz’ Idea

If we can bring the whole system to a common translation, without modification of any of the apparent phenomena, it is because the equations of the electromagnetic medium are not altered by Lorentz transformations.

Two systems, one motionless, the other in translation, thus become exact images of one another.

Langevin[1] modified this idea of Lorentz. The moving electron takes the shape of a flattened ellipsoid.

- For Lorentz, 2 of the axes of the ellipsoid remain constant
- For Langevin, the volume of the ellipsoid remains constant

These 2 hypothesis are in agreement with the experiments of Kaufmann, as well as the original hypothesis of Abraham (undeformable spherical electron).

The advantage of Langevin’s theory is that it uses only electromagnetic forces and binding forces.

Lorentz showed that it is incompatible with [my] postulate of relativity.

We need to suppose a special force which explains at the same time the contraction and the constancy of 2 of the axes.

I found that this force can be compared to a constant external pressure, acting on the deformable and compressible electron, and whose work is proportional to the variations of the volume of the electron.

Since the experiment of Kaufmann, the inertia of matter is thought exclusively of electromagnetic origin. Therefore, all forces, except that of that constant external pressure, are of electromagnetic origin.

This establishes the postulate of relativity.

I show this by a very simple calculation founded on the principle of least action.

Lorentz considered it to be necessary to supplement his hypothesis so that the postulate remains when there are other forces as the electromagnetic forces.

According to him, all the forces are affected by the Lorentz transformation (and consequently by a translation) in the same way as the electromagnetic forces.

This forces us to suppose that the propagation of gravitation is not instantaneous. Instead, it happens at the speed of light.

One could believe that this is a sufficient reason to reject the hypothesis, as Laplace has shown that this cannot be so.

But actually, this propagation effect is mainly compensated by a different cause, so that there is no more contradiction between the proposed law and the astronomical observations.

Is there a law which satisfies the condition imposed by Lorentz, and which at the same time is reduced to Newton’s law when the speeds of the stars are slow?

In this way, one can neglect their squares (as well as the product of acceleration and distance) in respect to the square speed of light?

I answer yes.

Is the law thus amended compatible with the astronomical observations?

If the propagation of gravity happens at the speed of light, then it must be due to a function of the ether.

We would then need to penetrate the nature of this function, and to relate it to the other functions of the ether fluid.

Let us suppose an astronomer before Copernicus who uses the system of Ptolemy.

- He will notice that for all planets, one of the two circles, epicycle or deferent, is traversed in the same time.
- This cannot be by chance.
- There is a mysterious binding between all planets.

But Copernicus simply changed the axes of coordinates regarded as fixed, and destroyed this appearance.

Each planet has only 1 circle. The durations of the revolutions become independent (until Kepler restores between them the binding which was believed to be destroyed).

Here it is possible that there is something analogue. If we admit [my] postulate of relativity, we would find in the law of gravitation and the electromagnetic laws a common number – the speed of light.

This speed of light is found in all the other forces of any origin. This is explained in 2 ways:

- The speed of light means that everything is of electromagnetic origin
- The speed of light is common to all the physical phenomena. But only is caused by our methods of measurement

How do we perform our measurements?

By transportation, one on the other, of objects regarded as invariable solids, one will answer immediately;

But this is not true any more in the current theory, if the Lorentz contraction is admitted.

In this theory, two equal lengths are, by definition, two lengths for which light takes the same time to traverse.

Abandoning this definition completely rejects the theory of Lorentz just as Copernicus rejects the system of Ptolemy.

It does not mean that Lorentz’ effort was useless. Simliarly, Ptolemy’s work was not useless for Copernicus.

My whole theory seems to be endangered by the discovery of magnetocathodic rays.