On the Electrodynamics of Moving Bodies By A. Einstein
The following introduction appears in Albert Einstein's flagship paper, "On the Electrodynamics of Moving Bodies," as the foundation for his Special Relativity theory.
It is known that Maxwell’s electrodynamics—as usually understood at the present time—when applied to moving bodies, leads to asymmetries which do not appear to be inherent in the phenomena. Take, for example, the reciprocal electrodynamic action of a magnet and a conductor. The observable phenomenon here depends only on the relative motion of the conductor and the magnet, whereas the customary view draws a sharp distinction between the two cases in which either the one or the other of these bodies is in motion. For if the magnet is in motion and the conductor at rest, there arises in the neighbourhood of the magnet an electric field with a certain definite energy, producing a current at the places where parts of the conductor are situated. But if the magnet is stationary and the conductor in motion, no electric field arises in the neighbourhood of the magnet. In the conductor, however, we find an electromotive force, to which in itself there is no corresponding energy, but which gives rise—assuming equality of relative motion in the two cases discussed—to electric currents of the same path and intensity as those produced by the electric forces in the former case.
Examples of this sort, together with the unsuccessful attempts to discover any motion of the earth relatively to the “light medium,” suggest that the phenomena of electrodynamics as well as of mechanics possess no properties corresponding to the idea of absolute rest. They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good. We will raise this conjecture (the purport of which will hereafter be called the “Principle of Relativity”) to the status of a postulate, and also introduce another postulate, which is only apparently irreconcilable with the former, namely, that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body. These two postulates suffice for the attainment of a simple and consistent theory of the electrodynamics of moving bodies based on Maxwell’s theory for stationary bodies. The introduction of a “luminiferous ether” will prove to be superfluous inasmuch as the view here to be developed will not require an “absolutely stationary space” provided with special properties, nor assign a velocity-vector to a point of the empty space in which electromagnetic processes take place.
The theory to be developed is based—like all electrodynamics—on the kinematics of the rigid body, since the assertions of any such theory have to do with the relationships between rigid bodies (systems of co-ordinates), clocks, and electromagnetic processes. Insufficient consideration of this circumstance lies at the root of the difficulties which the electrodynamics of moving bodies at present encounters.
The introduction to On the Electrodynamics of Moving Bodies is rewritten here for clarity:
The current understanding of Maxwell's electrodynamics, when applied to moving bodies, shows asymmetries that don't seem to be inherent in the observed phenomena. For instance, the reciprocal electrodynamic interaction of a magnet and a conductor only depends on the relative motion of the two bodies. Still, the customary view distinguishes the two cases where either the magnet or the conductor is in motion. If the magnet moves while the conductor is at rest, an electric field arises near the magnet, producing a current in the conductor. However, if the magnet is stationary and the conductor moves, no electric field arises near the magnet. Still, an electromotive force appears in the conductor, which produces currents of the same path and intensity as the former case.
These examples, along with the failed attempts to detect any motion of the earth relative to the "light medium," suggest that electrodynamics and mechanics have no properties that correspond to absolute rest. Instead, they imply that the same laws of electrodynamics and optics apply to all frames of reference where the mechanical equations hold true. This idea, referred to as the "Principle of Relativity," is raised as a conjecture and postulate, along with another postulate that light propagates in empty space with a constant velocity c, independent of the motion of the emitting body. These two postulates lead to a simple and consistent theory of the electrodynamics of moving bodies based on Maxwell's theory for stationary bodies, without requiring the concept of a "luminiferous ether" or a stationary space.
This theory is founded on the kinematics of rigid bodies, which relate to the connections between systems of coordinates, clocks, and electromagnetic processes. Neglecting this aspect has been the cause of the difficulties that the electrodynamics of moving bodies currently face.
Albert Einstein argued that "if the magnet is in motion and the conductor at rest, there arises in the neighbourhood of the magnet an electric field with a certain definite energy, producing a current at the places where parts of the conductor are situated. But if the magnet is stationary and the conductor in motion, no electric field arises in the neighbourhood of the magnet." Of course, there is no electric field in the magnetic field or the magnet! According to Maxwell's equations, the magnetic field is orthogonal to the electric field. If the magnetic field is present, then the electric field is not. Neither will a moving conductor produce an electric field in a stationary second conductor. However, a conductor with a current moving through it will produce a magnetic field that can interact with both a magnet and a second conductor. This argument by Einstein is a red herring and has nothing to do with physical mechanics.
Einstein continues by misstating the Michelson-Morley experiment. The original intent of the Michelson-Morley experiment was to identify a fixed Aether through which the Earth moved. The data showed a much smaller than expected Aether drift, which Poincare and Lorentz hypothesized meant the Aether was fluid in nature, as opposed to rigid. The Poincare-Lorentz transformations arose as this smaller-than-expected Aether drift was quantified due to a fluid Aether.
The fluid Aether concept of Poincare and Lorentz was a continuation of the fluid Aether concept of Rene Descartes. The fluid Aether works exactly the way a submarine operates in fluid water. The submarine displaces water in front of it, whirling around to fill the cavity behind the moving submarine. Physical matter displaces space in front of it, and that space whirls around to behind the object, and this fact is observed as "frame dragging" in physics. Still, Einstein chooses to incorrectly describe the Aether in the context of Michelson's failed rigid Aether hypothesis instead of the successfully quantified fluid Aether hypothesis of Poincare and Lorentz.
Einstein's first postulate from his own explanation in On the Electrodynamics of Moving Bodies essentially says, "There is no rigid Aether," which is true. But this does not address the fluid Aether the Lorentz transformations base upon. The second postulate states that photons (light) propagate in empty space at constant velocity c, which is fully compatible with a fluid Aether hypothesis. The fact that photons always move at speed c in the local space independent of moving observers implies that space (Aether) has a quantum structure, similar to how the ocean has the quantum structure of water molecules. Just as the speed of sound is constant in the water it travels through, the speed of photons is constant in the Aether it travels through, regardless of the observer's motion relative to the medium.
No submarine marks its course through the water by identifying water molecules. The submarines use gyroscopes and communications with fixed locations at the bottom of the ocean, the shorelines, and satellites in space. The idea that Einstein could eliminate the Aether from physics is as absurd as eliminating the ocean from the mechanics of submarines. Like water, space has physical properties that interact with physical matter. For example, the speed of photons is always the same in space (Aether). Space has constants of conductance, permeability, and permittivity. The circular deflection angle around massive objects in space (Aether) can never exceed one radian. These are very real, measurable properties of the Aether.
As presented in On the Electrodynamics of Moving Bodies, Einstein's Special Relativity was based only on physical matter and intentionally attempted to dismiss the existence of the Aether. While it is true that mathematics can be made that removes the word "Aether" from human physics, it is not possible to eliminate the Aether from the physical Universe.
The Circular Deflection Angle Equation
The Aether's essential existence in physics is easily made by expressing Albert Einstein's circular deflection angle equation in terms of a gravitational-magnetic tensor, which is a tensor between physical matter and space: