As we can conclude, classical mechanics was made on intuitive assumption that mass and matter are one and the same, and that the amount of mass is determined by the amount of matter in a certain volume. This intuitive assumption was also that mass moves in an empty space of the Universe. This could apparently argue by the fact that body will continue to move straightforward at even speed until it is stopped and distracted by some other body, or until it finds itself in a field upon different forces act.

However, by that time already we could ask ourselves a justified and concrete question: how it can be possible to explain the movement of electromagnetic waves through an empty space, if we base our reflection upon empirical and theoretically accepted fact that waves are basically an oscillatory movement of precisely the medium which transfers it, and which nature determines all fundamental characteristics of the waves. Most importantly, it determines the speed of the waves. Kinetic theory established a long time ago and then experimentally confirmed the existence of a functional relationship between the speed of chaotic thermal movement of gas particles and the speed of waves in that gas:

\[ \frac {\delta P}{\delta \rho} = c^2 = \gamma \frac P \rho = \frac \gamma 3 {v^2}\]

In this equation, as Kinetic theory predicts, \(c\) marks the speed of wave propagation, and \(v\) mean speed of chaotic movement of gas particles. What we can say on coefficient for thermal capacity of gas \(\gamma\) when ether is in question? The only presumption which won't lead as to methaphisics in which conterporary theories dwell, is that ether is the simplest gas fluid which particles are withouth any inner structure, that they have exclusevly kinetic energy of progressive movement and that there are no forces which act between them except the force of elactical mechanical chrashes. If we would assume any inner structure of individual particles and any forces which act between these seperated particles, we would find ourselves to explain the unexplaineable, which is mutual problem of all known theories.

If we accept the assumption that ether is described gas fluid, than by Kinetic theory it stands that

\[ \gamma = \frac 5 3\]

It can be directly seen from the equations (1) and (2) this relation:

\[ c^2 = \frac 5 9 {v^2}\]

If we follow the suggested logic in which there isn't anything peculiar or inexplicable, it can be noticed that the speed of chaotic movement of ether's particle is distinctively bigger than the speed of the light. What is more, the speed of the light loses in this way all the mystery which Theory of relativity attributes it. Consequence of cutting the ether out of the theory was that today no one can know nor explain what electromagnetic waves are, because by definition of nature of waves they cannot exist in an empty space.

Constructed stories on how these are some special waves for which stand some special rules (on which we won't elaborate) don't explain anything but make the problem even more vague which open the opportunity for everyone to fantasize according to his/her imagination. As it is known, that is main characteristic of all kinds of metaphysical, esoteric, occult and religious systems, and this is also their biggest advantage, because it is the hardest thing to undermine the claims which aren't clear to no one. However, in science which must be clear and exact, this vagueness isn't advantage but proof that the problem in question is not understood.

We will now present our determination of the nature of the mass, rather unusual although quite simple, if the assumption of ether, which fills all the space of the Universe, is accepted. What helped us the most was experimental fact that during crashes of natural particles at speeds close to speed of the light, a great number of artificial particles is created. Even more important was the fact that these particles, with a certain and sometimes measured masses, are being formed in pairs of 'particles – antiparticles' which exist in a very short period of time – to be more specific, they disappear in a process called 'annihilation', while releasing the energy invested in their construction.

That was probably the first proof that mass and matter weren't the same thing, although the problem wasn't solved by that. The problem was only distinguished and was apparently solved by Theory of relativity. However, this explanation have started to raise doubt and official science still invest great intellectual capacities and material means to find a valid explanation for the subject of this paper – determination of the mass.

It is impossible to say in which exact moment we felt the 'eureka' moment. We basically remembered this phenomenon: if areas of increased and decreased density were to be generated in any kind of gas fluid in which a certain pressure exist as a consequence of kinetic energy of its particles – what can logically be expected? First of all, that is possible only in a pair of 'area of increased – area of decreased' density. It simply stems from the Conservation of matter law. Secondly, if these areas were to be left to themselves they would quickly annihilate one another and, what is important, the quicker as the basic pressure in fluid is bigger. If we assume this process in ether takes place at breakneck speed it means the basic pressure in ether is gigantic. This means in order of sizes \(\rho {c^2}\), where size \(c\) we already know and that is the speed of the light. For determination of density we will have to make some further efforts. Unbelievable as it may sound, physics already has experimental data which provide the calculus for ether's density and we used it. However, this will be presented in separate paper.

This was the first step to determine the concept of mass. Is it possible, if ether exists with its enormous basic pressure, to define a mass as an area of increased and decreased density of ether? How it is possible that both areas, meaning area of increased and area of decreased density, represent masses, and what is more - the masses which are mutually equal? The answer on that question was found shortly after and thanks to simple math.

If the field of ether's changed density would appear in some spherical area, and in a way that the change of density is even in all parts of the sphere, we get this formula:

\[ M = \frac {(\Delta \rho)^2} \rho \frac {4 \pi R^3} 3\]

One condition is for sure fulfilled – regardless on the fact is density increased or decreased, in the area of changed ether's density mass is always a positive value. If we use standard terminology, we can state that the mass of field of increased ether's density correspond with the 'particle' and a mass of field of decreased ether's density correspond to 'anti-particle'.

The next question that imposes is: would movement of this mass trough ether's medium which stands still as a whole, correspond to established law of mechanics which we mentioned in introduction:

\[ F = M a = M \frac {\delta v} {\delta t}\]

It seems to us that analysis will be more comprehensible if we tie coordinate system to a 'mass' and assume that mass stands still and that ether's medium moves in relation to it. Let's assume also that there is no diverting of the flow line; the movement is linear. In this case, for the law of conservation of matter to be met, the same amount of ether in unit of time flows through the field of mass and also trough even section outside of mass. In this case this equation must apply:

\[ \rho v = (\rho + \Delta \rho) v_1\]

From that equation we see that this one stands too:

\[ \Delta \rho v = (\rho + \Delta \rho) \Delta v = - \rho_1 \Delta v\]

Negative sign on the right side of equation is a consequence of the fact that the speed of ether's flow is decreased in the field of increased ether's density. Now when we established this we can move to coordinate system of ether's medium which now stands still as a whole and field of mass moves in relation to it, in, off course, an opposite direction. According to Galilee's relativity law, the same as the mass brake the flow of ether's medium through the area of its field, in this other case when field is what it moves and medium stands still; the field pulls/entails the medium with it.

Formally, if ether's medium move in positive direction of the X-axis, in equation (7) in the field of mass the speed will decrease if density is increased, and grow if ether's density is decreased. In other case, the mass moves at the same speed in relation to ether's medium but now in negative direction of X-axis. Mass entails ether's medium at the speed of \(\Delta v\) in the same direction in which mass moves. By that, the relative speed of the mass and ether's medium decreases for \(\Delta v\), and if negative speed decreases, this change of speed is formally positive.

In the case where mass, in which field ether's density is decreased, is moving, everything is reverse: when ether's medium moves in positive direction of X-axis, the speed of the flow inside of the field of mass is increased.

When the field of mass is moving in a negative direction of X-axis, than the field of diluted ether pushes the ether's matter in the opposite direction of its movement. If we now sum up all this we can state that the mass of the 'particle' pulls the matter of ether's medium in the same direction in which mass itself moves. The mass of 'anti-particle' pushes the ether's matter backward in relation to its direction of movement. If the changes of ether's density are equal by number, than the changes of speed of ether's matter caused by moving of this kind of masses are also equal by number.

Now let us look to equation (7):

\[ \Delta \rho v = - \rho_1 \Delta v\]

To make the writing more easy we will mark the difference in speeds on the right side with \(V\) keeping in mind that this is the speed at which moves total ether's matter, either in direction in which moves the mass or in direction which is opposite of moving of the mass, depending on the fact is 'particle' or 'anti-particle' moving:

\[ \Delta \rho v = - \rho_1 V\]

It needs to be noticed what this equation means: if the left side of equation represents field of the mass in movement at the speed which is visible by naked eye, we can notice that the real movement of material ether’s medium is always smaller in number. How much smaller we will see when the time come, and this, as it can be seen, depends on the relationship \(\Delta \rho / \rho\).

The question that rises is: is there any point in analyzing the phenomena which appear when fields of increased or decreased ether's density move evenly through motionless ether's medium, if we stated that these fields disintegrate at breakneck speed the same moment when they appear. However, we are convinced that masses of natural particles, which continually exists and build atoms, molecules and all macroscopic bodies – protons, neutrons and electrons – have the same physical basics. Anyway, official contemporary theories accept this also, regardless of the fact they do not understand fundamental essence any of it.

We cannot avoid this question also: if the masses of natural particles are represented by described fields in ether, which are basically the same as the fields of artificially created masses, how these fields can exist unlimitedly long in time? For a theory to make sense, this must be explained. However, one paper isn't enough to present a complete theory on nature of the Universe. We are forced to limit the number of problems for one paper only and leave other to deal in separate ones. Due to that circumstance let us continue to analyze the movement of the field of changed ether's density in relation to motionless ether's medium and look the equation (6):

\[ \rho v = \rho_1 v_1\]

This equation shows, as it has been said, that the speed of ether's flow decreased in the field where density is increased, and where density is decreased the speed is increased. The question of utmost importance is: is it possible in this case to be established an even stationary flow of the ether, unlimited in time?

Let's think what is happening if ether's density is increased in the field which is placed in a line of flow. Entering that field ether thickens and its particles lose part of kinetic energy which is spent on compression of ether to reach this increased density. The consequence of this should be that the field of increased density, in time of its formation, heats. When the final state has already established, the particles which enter in the field lose certain amount of kinetic energy, and particles that exit the field get certain amount of kinetic energy. In which case is possible to maintain continuity of this process in time? As it is obvious, if the whole process is adiabatic which means without the energy loss in surrounding space, than the process is unlimited in time. Is this possible in reality?

Let us now investigate this same phenomenon from the other angle which Galilee's law of relativity permits: is it possible for this field of thickened or diluted ether which has been once set in motion, to continue its linear movement at even speed for unlimited period of time? If there is no energy loss from the field to the surroundings, than it is possible. If the loss is very small the movement will continue for a long time but not for unlimited period of time, depending on the amount of energy that has been lost. Does Nature give us an answer? Let's recall the sound waves in air, which aren't nothing else than the fields of changed basic density which moves in relation to surrounding air at the speed of the sound.

As it is known, movement of sound wave is carried out approximately adiabatic, which means that the loss of thermal energy from the wave in surroundings is very small. This fact has a consequence that sound wave cannot move unlimitedly far, sooner or later it must disappear. However, in everyday experience is impossible to notice that directly – our experience tells us that the sound spreads uninterrupted through air medium if there are no obstacles which interfere with it.

And how electromagnetic wave acts? As in many other cases, contemporary theories speak one thing, and Nature goes its own way, regardless of theories. So, official theory claims that 'electromagnetic quants' move through space without energy loss unlimitedly far in space and unlimitedly long in time. However, this theory imposes the implications of this claim: if this would be so, the whole sky above us would be the source of energy of even intensity. It wouldn't be possible to see nor register the Sun, the Moon, stars, nor any individual source of energy. How to solve this paradox?

This paradox is solved in a way we find hardly scientific and serious, by proposing an idea of 'big bang', from which the Universe emerged and because of which the Universe expands and all space bodies are diverging from each other in a way that the bodies which have started to move first diverge fastest, and then all other bodies follows. The consequence of that is so called Doppler Effect, that wavelengths of 'electromagnetic quants' are the bigger as the sources from which they generate are more distant from us. There is also a 'proof' for this: experimental fact indeed is that wavelengths of analogue spectral lines divert more in 'red side' if the stars from which they emit are more distant. Taking this fact as a 'proof' of 'big bang' seems imaginative but not scientific.

There is lots of imagination of this kind in many today's theories and all of it is a consequence of the same perpetuate mistake – that ether doesn't exist and that interstellar space is empty void without energy. But if we accept the fact that electromagnetic waves are in reality a mechanical waves of ether, than for them stands everything that stands for sound waves in air. They also move through ether's medium approximately adiabatic, which means they lose a bit of its energy on its way on heating the medium through which they move. That is a simple explanation of prolonging of wavelengths on its way through the space and eventually their complete disappearing.

This assumption of waves as fields of changed density which move in relation to surroundings without directly visible energy loss gives us a valid standpoint to claim that described fields of mass can also, once being set in motion, move linear and without visible energy loss for a period of time that is long enough to experience this movement as inertial, meaning without any energy and speed loss. Here is important to notice that movement which we visually see is only apparent movement in a certain sense, because it is not actual movement of matter which transfers wave. This we will understand easily if we examine the water wave. The wave transfers in the space at one speed but the speed of oscillation of water molecules is different speed and we don't see it. Let us write again equation (8):

\[ \Delta \rho v = \rho V\]

In this equation the left side describes the speed at which the field transfers in space and the right side the actual speed at which ether's matter moves in the field. With the help of this equation we can easily calculate kinetic energy of unit volume of ether's matter inside the field:

\[ \frac {(\Delta \rho v)^2} {2 \rho} = \frac {\rho V^2} 2\]

If we assume that the space of the field has the shape of a sphere and that the field is homogenous in whole volume of the sphere, total energy of the whole volume equals:

\[ W_{kin} = \frac {4 \pi R^3} 3 \frac {(\Delta \rho v)^2} {2 \rho} = \frac {4 \pi R^3} 3 \frac {\rho V^2} 2\]

Now we will mathematically describe how the energy changes in case when this is happening in a way that the speed changes on the way through space:

\[ \frac {\delta W_{kin}} {\delta S} = \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho \frac {v \delta v} {\delta S} = \frac {4 \pi R^3} 3 \frac {V \delta V} {\delta S}\]

It is obvious that this relation stands:

\[ \frac {v \delta v} {\delta S} = \frac {\delta v} {\delta t} = a\]

So, when we set it in equation (11), we get:

\[ \frac {\delta W_{kin}} {\delta S} = \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho a\]

The fundament law of mechanic which we mentioned in introduction is this:

\[ \frac {\delta W_{kin}} {\delta S} = M a\]

From equations (12) and (13) we see their right sides are equal:

\[ \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho a = M a\]

If we take into account elementary mathematics, we can observe that mass equals:

\[ M = \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho\]

In this way, by elementary logic and elementary mathematics, we determined the physical essence of the mass. How to grasp all the consequences of equation (15)? We proved it is in accordance with the law (15). We are of the opinion it is also in accordance with the law of inertia. Besides, if we set in (14) that the change of speed equals zero, we directly prove by that the fact that the mass continues to move linear at even speed until this is changed by acting of some force.

It appears that a human throughout the whole history cannot see the reality which stand literally in front of his/her nose. Where is that ether, if we cannot see it? However, everything that we see is ether. Our own body, that is ether also. And why it doesn't give any resistance in movement of the body? Well of course it gives resistance, that is what we call the inertia of the mass. The blindness of the human mind reminds us on the story of E. A. Poe where the police of the whole Paris is in search of the letter which lies on the table for everyone to see it.

We have already tackled the question of the ways how the field of changed ether's density maintains. In every case we must presume the nature has the mechanism by which it accomplishes it. For the time being we will put aside this question and move our attention to question of how big work needs to be invested to build this field. According to mechanical law which we have already used in this paper, the change of energy is equal to acting of force on the way on which force acts:

\[ \frac {\delta W} {\delta S} = F\]

The force which is produced by acting of the gas is equal to product between the surface and pressure which acts on this surface. Now let's imagine how the spherical volume forms inside of ether's medium in which ether's density is increased. This happens when the surface of some sphere moves toward inside in a way that all ether, which was in the start inside of the sphere, compresses in a smaller volume. In the beginning of the compression the pressure outside and inside of the sphere is equal. The difference in the pressure establishes only when the surface of the sphere moves toward inside. During the reducing the sphere the difference in pressure inside and outside the sphere gradually grows so that in the end of compression has maximal value. Mean difference in difference between the pressure outside and inside of the sphere is equal to half of the maximal:

\[ \delta W = 4 \pi R^2 \Delta P \delta S\]

The conservation of matter law demands this equation to be right:

\[ 4 \pi R^2 \rho \delta S = \frac {4 \pi R^3} 3 \delta \rho\]

\[ \delta S = \frac {\delta \rho R} {3 \rho}\]

Now we set this section of way from the equation (18) in equation (17):

\[ \delta W = \frac {4 \pi R^3} 3 \frac {\Delta P \delta \rho} \rho\]

For our conclusions to be further mathematically correct we must assume that the ratio \(\Delta \rho / \rho\) is small. We have this ratio theoretically calculated this ratio for the nuclear field also and it is in order of size \(10^{-10}\). According to this ratio, as Kinetic theory has calculated for gas when it is compressed adiabatically in a sound wave, stands this equation \(\Delta P = \Delta \rho c^2\). For ether, of course, the speed of the light is in question. In this specific case we need to understand that this equation was calculated for sound wave which moves freely through the space, meaning that ether's particles in electromagnetic wave, responsible for increasing the pressure and density in gas, also move freely through the space.

However, in situation which we described ether's particles remain closed in spherical volume, so we can assume they bounce from the spherical surface by exerting pressure on it. In this case the impulse which is being transferred to the surface of bouncing is two times bigger, which means that the pressure on surface is also two times bigger. This gives us the right to write this equations stands: \(\Delta P = 2 \Delta \rho c^2\). When we set this in equation (19) we get:

\[ \delta W = \frac {4 \pi R^3} 3 \frac {2 \Delta \rho \delta \rho} \rho c^2\]

Integral of this equation is:

\[ W = \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho c^2\]

When we compare this equation with equation (15) we notice we got by the use of classical mechanics the relation which made Einstein famous:

\[ W = M c^2\]

We will get the same result if we assume that the force which acts on ether acts on the surface of sphere from the inside, by increasing its volume. The only difference now is that work is being carried out on ether outside the sphere, but the work needed to establish this kind of field, the field of diluted ether, stays the same. The work stays the same also in the case if the field would form in a volume in a shape of a cube. This is important to underline because it is hard to assume that artificially created particles have volume in a shape of a sphere or in a shape of any geometrically simple volume.

However, every volume, regardless on its total shape, can be understood as the sum of little volumes in a shape of a cube in which every cube has homogenous field. Total mass and total energy we can get by summing of masses and energies in all these boxes, and result will be again the same as in relation (22). We assume that masses of artificially created particles cannot measure directly – we assume energy can, and that mass calculates by equation (22). That would mean we believed in accuracy of masses of artificially created subatomic particles on Einstein's "word", because he didn't give any credible proof for accuracy of equation (22). The fact that energy released in atomic explosion equals to \(\Delta W = \Delta M c^2\) cannot stand as a proof of accuracy of equation (22).

If we would, for example, write \(\delta W = \delta M c^2\), in this case is \(W = M c^2 + Const\). And this constant can be zero as well as arbitrary large. As for artificially created particles, we have shown by our analyses that relation (22) marks the work invested in forming of the mass, but only of the artificially created subatomic particles. It certainly cannot be taken as a proof that equation stand for natural particles also because no one has ever created them, nor see nor measure the energy of their breakdown. On the contrary, it needs to invest the enormous work, in a size of \(1000 MeV\) to break one proton. We do not know how contemporary theory solves this paradox. Our logic goes like this: if the energy in order of sizes of \(1000 MeV\) needs to be communicated to volume in which mass of the proton is for this mass to disappear, it means that in this volume energy is decreased for this amount in comparison to the space outside of that volume. The second question is why this lack of energy is maintained by the natural way and we will speak on this subject also in one of our papers.

Equation (21) is enough to explain almost everything what theoretical physics needs to explain:

\[ W = \frac {4 \pi R^3} 3 \frac {(\Delta \rho)^2} \rho c^2\]

What will happen, for instance, if we try to push two protons in the same volume? From equation (21) we can see that enormous work is needed, because the sum of two proton's fields would increase the energy of this new particle two times in relation to total energy which two protons had before the merging. This specifically means the invested work would equal to \(2 \times 938.28 MeV\). Because of that the mass is "hard", although this is, *de facto*, in a gas state, and why protons elastically bounce until the energy reaches the size when both crash in an impact.

Among other interesting results to which our theory of ether came is the fact that the essential nature of nuclear and electrical field is the same. They differ only by strength and topography. We will show this on the example of mass of the electron. Based on conclusions which we have established following the experimentally proven facts, the mass of electron appears like this: inside the sphere with radius of \(1.408964 \times 10^{-13} cm\) the field of electron has constant size, and beginning with the surface of the sphere and to the infinity the strength of the field decreases with the distance square from the sphere. Expressed by mathematics, the field inside the sphere equals \(\Delta \rho_0\), the field outside the sphere equals \(\Delta \rho_0 \frac {R_e^2} {R^2}\) when \(R \gt R_e\).

On the basis of these assumptions we can calculate the total mass of electron. Inside the sphere with radius \(R_e\) is a part of mass which we get by multiplying the volume of the sphere with square of the field inside of the sphere. The amount of the mass which is distributed throughout the space of the Universe we get as integral of the expression:

\[ \delta M = 4 \pi R^2 \delta R \frac {(\Delta \rho_0)^2} \rho \frac {R_0^4} {R^4}\]

The calculus is simple and it gives this size for the total mass of the electron:

\[ m_e = \frac {16 \pi R_e^3} 3 \frac {(\Delta \rho_0)^2} \rho\]

We marked the mass with the small letter \(m\) because we did so in our previous papers. The field of electron is negative, meaning; ether in its field is diluted. One quarter of the mass of electron is inside the sphere with radius \(R_e\) and three quarters are distributed throughout the whole space of the Universe. Total energy that is needed to build the mass of electron we simply get by multiplying the mass with squared speed of the light:

\[ W_e = \frac {16 \pi R_e^3} 3 \frac {(\Delta \rho_0)^2} \rho c^2\]

If we write this energy in function of electron's charge and its radius we get:

\[ \frac {e^2} {2 R_e} = \frac {16 \pi R_e^3} 3 \frac {(\Delta \rho_0)^2} \rho c^2 = m_e c^2 = 0.511 MeV\]

Now we can realize that every body which is in electrostatic field of an electron is practically inside of the electron's body. And two charged bodies, regardless of the distance between them, mutually permeate with their fields, or in another words, with their bodies. Taken into account that energy depends on square of the field, it is immediately understood that convergence of the same fields increases energy and convergence of different ones decreases energy. By that it can simply be explained the phenomenon of "potential holes" in which particles in space situate. The fields of different signs are being pushed one into another, and the fields of the same signs are being pushed one outside of another. That is at the same time an explanation of the force which acts "on distance" between charged bodies. The force that acts on distance does not exist and cannot exist in material world.