A. Einstein devoted his report on May 5, 1920 at the University of Leiden to ether (see Einstein: "Ether and Relativity"). In his report, striving for the unity of understanding of Nature, he, nevertheless, affirms dualism, that is, the existence of two substances: matter and ether. He calls the elementary particles of matter and the electromagnetic field two realities, completely separated from each other. He calls them Space and Matter. Einstein admits the existence of the ether, but says that the idea of motion is not applicable to the ether. At the same time, he talks about his dream - understanding the gravitational field and the electromagnetic field as one single structure (see above Report). This representation of A. Einstein is still preserved in modern physics.
Further it will be shown that such unity is possible on the basis of the disclosure of the deep essence of the ether. However, it turns out that the unification of these fields will require a significant adjustment of the very concepts of the electromagnetic and gravitational fields (Gravity - not an attraction, New concept of electromagnetic waves see below).
Part of the deep essence of the ether is disclosed above (see Essence of space vacuum). This is done on the basis of the concepts of Material Space established here (see Correction of Concepts). As a result, it is proved that the ether and the material Space have no differences. They have a deep unity. The most appropriate name for this single space substance is taken "Maternal ether". Let's try to penetrate deeper into the essence of the Space Ether and reveal its properties.

                                            J.Maxwell and A.Einstein trusted in an space ether

The space ether microvibration. From In Space all moves and Space oscilation follows that space ether possesses a motion, and this motion should be oscillating. From 3-regularity of Universe (Space and Time see) streams the oscillation of it can be only the unique: the density magnification – the density reduction. It within any viewed volume of  space ether is the squeezing – expansion, but for the microvolumes concerning of boundless  ether means:  space ether possesses the microvibration (2nd fundamental property of space ether - maternal ether, 1st property see in What is space vacuum). The erected undular magnification of density of  ether in microvolumes (the thickening) means also the transient formation of the conditional (The maternal ether see) microparticles at the expense of reduction of density of  space ether about these temporarily shaping conditional particles (of quasi-particles). That is  space ether has no the continuity disruptures – of vacuum, but there are the small auto-oscillations of density of  the ether, whence follows: the ether (maternal ether) – is not  gas and not  fluid.

It also follows from the above that when considering the motions of the ether in volumes larger than the indicated extremely small microvolumes, the density of the ether is the number of the smallest particles of the maternal ether (quasi-particles) together with the neighboring interparticle maternal ether. Obviously, this density cannot be measured. It is possible to determine only the comparative density of the ether - by the number of quasiparticles without the neighboring ether. In this case, the comparative density is calculated by the pressure of the ether exerted by these vibrating particles and by the viscosity of the ether (see below) at different speeds of its movement.

The space ether fluxion. From indicated 2nd fundamental property of  space ether – the microvibration and 2nd fundamental property of Material Space (World is not identical see) – it’s the unequality streams 1st consequence: the unequality of density ρ of  ether in the next volumes of Space leads to occurrence of the motion of space ether – of the fluxion  (3rd property of  ether), levelling its densities. Among themselvesthe exchange of the microvolumes by motion – the expansion on squeezing and on the contrary – is the microoverflow (i.e. by the fluxion also).

The property of  space ether – the fluxion streams from following microprocesses. The exchange of microvolumes of  the ether by motion – the expansion and the squeezing  more often occurs there where these vibrating microvolumes are disposed in Space  more close to each other, i.e. there where  ether is more dense. This more dense field on the boundary with the less dense will be dilated because the return of micromotion of the microvolumes of the expansion – squeezing  of  ether from the side of the less dense field occurs more slowly, than from the side of the more dense one, i.e. retards. As result the front of the more dense zone consistently behind everyone microoscillations moves in the less dense zone, and the subsequent to front the more dense zone moves in one – the preferred direction – it  flows.

The featured equalization of density of space ether in the greater volume of Space (the macrofluxion) obviously occurs with the simultaneous (the cophased) local fluxions – equalizations of the local unequalities  the ether densities.

From the given follows the indicated fluxions are the bottom of existence of motion itself ("In Space all moves") in any places of Universe (of any objects of Universe, systems and their parts). It is obvious also that fluxion of space ether is the bottom of the property of all objects of Universe – self-equalization and, hence, by the cause of the known aspiration of all objects to an energy minimum. Real presence in Nature of three indicated properties (the fluxion, the self-equalization, the aspiration to an energy minimum) reliably confirms their physical origin – the  space ether vibration.

The space ether viscosity. From 2nd property of  space ether – vibration and 3rd properties – fluxion the 2 consequence streams:  the ether will be at the motion – fluxion to display the viscosity. It is 4th rather important property of space ether. The viscosity of the ether on the essence differs from the thermodynamic concept of viscosity of gases and fluids since the ether "particles" it is the quasi-particles (see above 1st paragraph). From  space ether to a body (Тhe chemical bond is not the fundamental see) is transmitted not the push from the forward or/and rotary movement of a particle as it occurs in the thermodynamic systems, but the motion – the expansionof a microvolume of  space ether. And the ether macrofluxion is more prompt or more its density, the most part of the micromotion – the expansion is transmitted to the object "surface" about which the  ether flows, for example, to one of microvortexes (see further) from which the body consists. The possession of space ether by the property of viscosity is confirmed by the presence of Gravity in bodies ("Gravity - not an attraction" see above).

The space ether elasticity. Themselves microoscillations of density of each of  the ether microvolumes generate (more precisely, mean) its elasticity. That is the space ether is elastic. It is the 5th property of space ether, which is the bottom of the oscilation of  World ("Space ascilation" see). Elasticity of  space ether is confirmed by presence of Inertia at bodies (The essence of Inertia see), and also by the ability of ether to transmit the elastic waves (known, as the electromagnetic waves. see above) at is the property of the elastic mediums.

Consequence 1. It follows from the established properties of the ether that the ether is neither a gas nor a liquid.

Consequence 2. From space ether continuity (1st property) and its elasticity (5th property) streams the elastic squeezed zone (a wave) of  space ether  is spread on the ether rectilinearly.

Thus, the dualism in the understanding of Nature is eliminated. The properties of the space ether, including the property of motion, have been established.