Introduction
A hundred years ago, almost everything in physics could be understood by high-school seniors and by everybody with a similar education. Anything which was not understood was outspokenly presented as such and was strongly believed to become apprehendable in the progress of science. Making facts of physics understandable to those prepared for such understanding was considered as one of the most important duties of science, if not the most important. The uncompromised quest for understanding made physics differ from engineering, the main task of which was to make facts manageable, to operate or just to engineer them.
This is also why most prominent physicists would give pay-lectures, unsolicited and unsponsored by any organization, and why people would buy tickets and fill lecture and theater-halls as they did for concerts and plays. Mind you, those lectures were not superficial smatters of knowledge but in-depth analyses and explanations of scientific achievements on the then-highest level. The only thing which made them differ from professional lectures given to colleagues or students was the absence of mathematical complications. People paid with the best of their after-tax money just for the fun of understanding physics. The desire to understand also made people go and study physics.
The attitude started changing after 1887, when Michelson-Morley's experiment proved that light is propagating with the same velocity in the direction of Earth's motion as in the opposite direction. This fact could not and still cannot be understood on the basis of accepted scientific theories. It became the basis of Einstein's second postulate of relativity. However, raising the fact to the rank of a postulate did not explain it, nor could it make relativity apprehendable, though Einstein himself used to present his ideas to the general public by lectures and popularizing articles.
Thereafter came the successful mathematical formulations of Schroedinger, Heisenberg and Pauli in quantum mechanics, which could not and cannot be understood on the basis of accepted theories. These scientists never tried to make their findings apprehendable. On the contrary, they presented the inability to understand their findings as an important scientific principle, stating that there is not and cannot be any understanding, and that all there is in physics are the mathematical formulations. Hence, R. Feynman, one of the great theorists of our times, could proudly state, in 1967, that: "I think I can safely say that nobody understands quantum mechanics." P.A.M. Dirac expressed the worshipping relations toward mathematical formulations by saying that: "It is more important to have beauty in one's equations than to have them fit experiment."
The XX century physics is unable to explain the discovered oddities in the positions and motions of atoms and subatomic particles and the peculiarities of their interactions, especially with light; nor is it able to disclose the nature of light itself. These phenomena are dealt by quantum physics and relativity in such a way that for every observed oddity, a postulate or principle is formulated, followed by a correspondingly adjusted mathematical treatment. The systems of ad hoc fitted verbal postulated principles and mathematical treatments enable us to adjust to the unexplained facts of modern physics, to work with them and to use them successfully in the development of science and technology.
With the discovery of each new oddity, adjustment is reached by developing new postulates and formulas. Elseways, new quasi-particles are invented, which are made responsible for the missing or superfluous mass, or for any other property which could not otherwise be accounted for. There are tens of such exotic quasi-particles flourishing in the literature, some bearing the names of their creators, others bearing the names of their functions (like gluons, gluinos, etc.). One more way is to add dimensions to our troubled world. The superstring theory, which specializes in it, counts 10 or 11 dimensions, instead of the three space-dimensions and time, for which we have a feeling. Other workers in this field propose 15, 20, 25 dimensions, promising to solve with them all existing problems. The largest number of worlds dimensions we know of is 506, proposed by M.J. Duff in 1985.
It is obvious that quantum physics and relativity lack a physical model of the electromagnetic field, as carrier of both the electromagnetic and the gravitational interaction. The carrier would not only carry electromagnetic and gravitational waves but also interact with atomic bodies, atoms and subatomic particles; thus, it would be responsible for the oddities in their positions and motions. Such a physical model would therefore serve as a basis for the "grand unification" of quantum physics and relativity. The unification was and is promised by many theories to be achieved by adding dimensions, particles, or by other approaches, but was never reached. Without a physical model for the electromagnetic field, both quantum physics and relativity remain two separate systems of unexplained, loosely-connected postulates and prescriptions for calculations.
The empty space was proclaimed as the carrier of light in 1905. With the introduction of photons as particles of light, there was no immediate need to ascribe mass and and elasticity to the empty space. By proclaiming time as just the fourth coordinate, it seemed that physical problems can be reduced to geometry in the four-dimensional space. Hence, the empty space seemed not to need any physical properties in order to carry electromagnetic radiation and gravitation. However, in 1934, Einstein had to agree that: "space is endowed with physical qualities". It turned out that space must have not only geometry but also topology and geodesy; that it can wrap and be wrapped, with all features of a disturbable and deformable physical object.
Photons as particles of the empty space became able to knock out electrons not only from solids, as in the photo-electric effect, but also from the outer and inner orbits of atoms, and even out of the vacuum itself, as in the "creation" of electron-positron paris. Thus, the particles of the emptiness turned out to have mass and momentum, which would suggest that the empty space must also have these qualities. The newest addition to the swollen list og physical properties of the empty space is that it is also quantized. The discreteness of the empty space is dealt by various gauge and lattice theories, carrying even the calculations of such an exclusive property of a lattice, as is the existence of a highest-possible vibrational frequency, or the 'cutoff' frequency.
All experimental facts of quantum physics and relativity, as well as theoretical developments forced on physics by these facts, lead to the electron-positron lattice, or epola, for short, model of space. This model is mainly based on three experiments or groups of experiments. First is the Michelson-Morley experiment. Then comes Rutherford's experiment on scattering of alpha-particles, proving that only a part of the volume of atomic bodies, including the Earth and ourselves(!) is occupied by 'dense' particles: electrons and atomic nuclei. The rest, i.e., practically all the volume, is as empty as the vacuum of space and penetrable to dense particles. Hence, our natural perception of atomic bodies as bodies of continuous dense matter is false. Unfortunately for the epola model, this knowledge did not become part of our picture of the world and is hard to accept; maybe, even hard than to accept a four-dimensional space, the existence of which was never proven by direct experiment.
The third basic experiment is Anderson's 1932 discovery of the "creation" and "annihilation" of electron-positron paris. It proves that electrons and positrons are released from any point in space by submitting to it 1.02 MeV of gamma-ray energy. More recent high-energy acceleration and collision experiments prove that electrons and positrons remain stable and intact under gains and losses, greatly exceeding this energy. An electron or a positron cannot be created or annihilated even by GeV energies. Hence, electrons and positrons must exist in space in a bound, therefore indetectible form, and 1.02 MeV is just the binding energy of an electron and positron to their counterparts in space. Finally, quantum effects prove that the system which these bound particles create in space must be a lattice.
The only physical explanation for the possibility of the electron-positron pair 'creation' and 'annihilation' is that the empty space is densely populated by these particles. Unfortunately for the epola model, this contradicts our natural perception of space as an emptiness, in which the allegedly dense and continuous bodies of atomic matter can move without facing any resistance. However, experimental facts draw an opposite picture of almost empty atomic bodies, completely penetrable to the bound electrons and positrons of the epola space. Motion of atomic bodies in the epola is the motion of their atomic nuclei, their orbital and 'free' electrons, in channels between epola particles. The particle-density in the epola is billions of times larger than in atomic bodies. Hence, the motion of atomic bodies in the epola does not face any resistance, up to certain limiting velocities. Similarly, a net, mad of widely spaced thin threads can slowly move in air or water without resistance, and without causing winds or currents in these ambients.
The billions of times higher particle density in the epola also explains why the motion of the almost-empty atomic bodies cannot cause 'winds' in the epola carrier of light, or push or pull the epola. Hence, the results of Michelson-Morley's experiment are in full agreement with the epola model of space; one may say that they follow naturally from this model. Therefore, there is no need to force upon us a belief in a four-dimensional space, which contradicts our natural perception and our life and laboratory experience. There is also no need in tyrranic requests that the velocity of light and all physical laws established in our backyard must be the same in the whole universe. The epola model also dismisses some paradoxes of relativity, as time dilation, length contraction, clock or twin effects, or the Big Bang-created exploding universe. The epola model allows us to derive and explain the experimentally-proven postulates, principles and laws of quantum physics and relativity. With few physical assumptions and the aid of basic calculus it unifies these two branches oh physics and enables a unified treatment of all out-of-nuclei physical phenomena.
All this for the price of accepting the experimentally-proven 'emptiness' of atomic bodies and the so-much-higher density of bound particles in space. This seemingly-paradoxical 'etherized' atomic matter and 'solidified' space are still less paradoxical than the alternatives, which stay in physics now.