Ether and Special Relativity

My Special Relativity and space-time theory were modelled on the Maxwell-Lorentz theory of the electromagnetic field.

If K is a system of co-ordinates relatively to which the Lorentzian ether is at rest, the Maxwell-Lorentz equations are valid primarily with reference to K.

But by Special Relativity, the same equations also hold in relation to any new system of co-ordinates K' which is moving relatively to K.

But why must I distinguish the non-moving K system above all moving K' systems, which are physically equivalent to it in all respects, by assuming that the ether is at rest relatively to the non-moving K system?

*Superphysics Note: We answer that the duality is essential in because the non-moving K has properrties that affect and explain the motions and dynamics within the moving K'

I think that such an asymmetry in the theoretical structure, with no corresponding asymmetry in the system of experience, is intolerable*.

*Superphysics Note: To Einstein, it is intolerable to have a dimension which is unknown

If the ether were at rest relatively to non-moving K, but in motion relatively to moving K', the physical equivalence of non-moving K and moving K' is unacceptable.

Initially, the solution is that the ether does not exist at all.

The electromagnetic fields:

• are not states of a medium
• are not bound down to any bearer
• are independent realities which are not reducible to anything else, exactly like the atoms of ponderable matter.
• are electromagnetic radiation, according to Lorentz’s theory. This is like ponderable matter bringing impulse and energy with it

According to Special Relativity, both matter and radiation are but special forms of distributed energy, ponderable mass losing its isolation and appearing as a special form of energy.

But afterwards, Special Relativity however does not compel us to deny ether.

We may assume the existence of an ether. But it does not have a definite state of motion to it, i.e. we must remove its immobility.

Think of waves on the surface of water. Here we can describe two entirely different things. Either we may observe how

The undulatory surface between water in a pond and the air above it changes in time. Through buoys as markers, we can see how the water changes in time. If such buoys were impossible, then we cannot say that water was made up of moving particles. But it would still be a medium.

The electromagnetic field is like water, consisting of lines of force*. Each separate line of force is tracked through time. But this way of regarding the electromagnetic field leads to contradictions.

There might be extended physical objects to which the idea of motion cannot be applied. They might not be made up of trackable particles.

Minkowski expresses this as= Not every extended conformation in the four-dimensional world are composed of world-threads. Special Relativity forbids us to assume the ether to consist of particles observable through time. But the hypothesis of ether in itself is not in conflict with Special Relativity.

We merely must not ascribe a state of motion to the ether. To Special Relativity, the ether hypothesis initially is an empty hypothesis.

The equations of the electromagnetic field only have:

• the densities of the electric charge
• the intensities of the field.

Electromagnetic processes in vacua are completely determined by these equations, uninfluenced by other physical quantities.

The electromagnetic fields appear as ultimate, irreducible realities. At first, it seems superfluous to:

• postulate a homogeneous, isotropic ether-medium
• envisage electromagnetic fields as states of this medium.

But on the other hand, the ether hypothesis is useful in harmonizing the fundamental facts of mechanics.

The mechanical behaviour of body hovering freely in empty space depends on:

• relative positions (distances)
• relative velocities
• its state of rotation
  • This might not appertaining to the body in itself.

In order to look at the rotation of the body as something real, Newton objectivises space. He classes his absolute space together with real things. For him, rotation relative to an absolute space is also something real.

Newton could have called his absolute space as “Ether”. Besides observable objects, another thing, which is not perceptible, must be looked upon as real in order to enable acceleration or rotation to be looked upon as something real.

Mach

Mach tried to avoid assigning reality to a something not observable. Instead of an acceleration with reference to absolute space, he used all of the masses in the universe as reference.

But inertial resistance opposed to relative acceleration of distant masses presupposes action at a distance. Anyone who follows Mach will still end up with the ether as medium for the effects of inertia. But Mach’s ether is different from the ether of Newton, Fresnel, and Lorentz.

Mach’s ether not only conditions the behaviour of inert masses, but is also conditioned in its state by them.

Mach’s idea finds its full development in the ether of General Relativity which says that the metrical qualities of space-time:

• differ in the different points of space-time
• are partly conditioned by the matter existing outside of the territory

Space is not physically empty. This is because:

• Space and time have reciprocal relations
• “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν),

This makes the ether useful. But this ether is very different from that of the ether of the mechanical undulatory theory of light.

The ether of General Relativity is a medium which is itself devoid of all mechanical and kinematical qualities. But it helps to determine mechanical (and electromagnetic) events.

Difference Between GR Ether and Lorentz Ether

The state of General Relativity (GR) Ether is at every place determined by connections with the matter and the state of the ether in neighbouring places. These are amenable to law in the form of differential equations.

The Lorentzian ether in the absence of electromagnetic fields is:

• conditioned by nothing outside itself
• everywhere the same

The GR ether is transmuted conceptually into the ether of Lorentz if we substitute constants for the functions of space which describe the former, disregarding the causes which condition its state.

Thus, the GR ether is the outcome of the Lorentzian ether, through relativation.

As to the part which the new ether is to play in the physics of the future we are not yet clear.

The new ether determines the metrical relations in the space-time continuum, e.g. the configurative possibilities of solid bodies as well as the gravitational fields.

But we do not know whether:

• it has an essential share in the structure of the electrical elementary particles constituting matter.
• it is only in the proximity of ponderable masses that its structure differs essentially from that of the Lorentzian ether
• the geometry of spaces of cosmic extent is approximately Euclidean.

But we can assert by reason of the relativistic equations of gravitation that there must be a departure from Euclidean relations, with spaces of cosmic order of magnitude, if there exists a positive mean density, no matter how small, of the matter in the universe.

In this case, the universe must of necessity be spatially unbounded and of finite magnitude. Its magnitude is determined by the value of that mean density.

If we consider the gravitational field and the electromagnetic field from the standpoint of the ether hypothesis, we find a remarkable difference between the two.

There can be no space nor any part of space without gravitational potentials; for these confer upon space its metrical qualities, without which it cannot be imagined at all.

The existence of the gravitational field is inseparably bound up with the existence of space. On the other hand a part of space may very well be imagined without an electromagnetic field. Thus in contrast with the gravitational field, the electromagnetic field seems to be only secondarily linked to the ether, the formal nature of the electromagnetic field being as yet in no way determined by that of gravitational ether.

From the present state of theory it looks as if the electromagnetic field, as opposed to the gravitational field, rests upon an entirely new formal motif, as though nature might just as well have endowed the gravitational ether with fields of quite another type, for example, with fields of a scalar potential, instead of fields of the electromagnetic type.

The elementary particles of matter are merely condensations of the electromagnetic field. This leads to two views of the universe:

• gravitational ether (space)
• electromagnetic field (matter)

These two realities are completely separated from each other conceptually, although connected causally.

It would be a great advance if we could comprehend the gravitational field and the electromagnetic field together as one unified conformation. This would conclude the the epoch of theoretical physics founded by Faraday and Maxwell. It would remove the contrast between ether and matter.

Through General Relativity*, the whole of physics would become a complete system of thought, like geometry, kinematics, and the theory of gravitation.

*Superphysics Note: Such a unification is actually being prevented by General Relativity

The mathematician H. Weyl is trying to do this. But I do not think that his theory will hold in reality.

We should not unconditionally reject the possibility that the facts comprised in the quantum theory may set bounds to the field theory beyond which it cannot pass.

According to GR, space has physical qualities represented by the ether.

But this ether is not a ponderable media which has parts which may be tracked through time. The idea of motion may not be applied to it.