Gravitational interaction is manifested in the attraction of bodies to each other. This interaction is explained by the presence of a gravitational field around each body.
The modulus of the force of gravitational interaction between two material points of mass m 1 and m 2 located at a distance r from each other
(2.49)
where F 1.2, F 2.1 - interaction forces directed along the straight line connecting the material points, G \u003d 6.67 
is the gravitational constant.
Relation (2.3) is called law of gravity discovered by Newton.
Gravitational interaction is valid for material points and bodies with a spherically symmetrical mass distribution, the distance between which is measured from their centers.
If one of the interacting bodies is taken to be the Earth, and the second is a body with mass m located near or on its surface, then an attractive force acts between them
,
(2.50)
where M 3 ,R 3 are the mass and radius of the Earth.
Ratio 
- a constant value equal to 9.8 m / s 2, denoted by g, has the dimension of acceleration and is called free fall acceleration.
The product of the mass of the body m and the acceleration of free fall 
, is called gravity
.
(2.51)
In contrast to the force of gravitational interaction 
gravity modulus 
depends on the geographic latitude of the location of the body on Earth. At the poles 
, while at the equator it decreases by 0.36%. This difference is due to the fact that the Earth rotates on its axis.
With the removal of the body relative to the surface of the Earth to a height 
the force of gravity decreases
,
(2.52)
where 
is the free fall acceleration at a height h from the Earth.
Mass in formulas (2.3-2.6) is a measure of gravitational interaction.
If you hang a body or put it on a fixed support, it will rest relative to the Earth, because. the force of gravity is balanced by the reaction force acting on the body from the side of the support or suspension.
Reaction Force- the force with which other bodies act on a given body, limiting its movement.
Force of normal support reaction
attached to the body and directed perpendicular to the plane of support.
Thread Reaction Force(suspension) 
directed along the thread (suspension)
Body weight 
–the force with which the body presses on the support or stretches the suspension thread and is applied to the support or suspension.
Weight is numerically equal to the force of gravity if the body is on a horizontal support surface in a state of rest or uniform rectilinear motion. In other cases, body weight and gravity are not equal in absolute value.
2.6.3 Friction forces
Friction forces 
arise as a result of the interaction of moving and resting bodies in contact with each other.
Distinguish between external (dry) and internal (viscous) friction.
External dry friction divided by:
The listed types of external friction correspond to the forces of friction, rest, sliding, rolling. 
With
acts between the surfaces of interacting bodies when the magnitude of external forces is insufficient to cause their relative movement.
If an increasing external force is applied to a body in contact with another body 
, parallel to the plane of contact (Fig. 2.2.a), then when changing 
from zero to some value 
there is no body movement. The body starts moving at F 
F tr. max.
Maximum static friction force
,
(2.53)
where 
is the static friction coefficient, N is the modulus of the force of the normal reaction of the support.
Coefficient of static friction 
can be determined experimentally by finding the tangent of the angle of inclination to the horizon of the surface from which the body begins to roll under the action of its gravity.
When F> 
bodies slide relative to each other at a certain speed 
(Fig. 2.11 b).
The force of sliding friction is directed against the speed 
. The modulus of the sliding friction force at low speeds is calculated in accordance with the Amonton law
,
(2.54)
where 
is the dimensionless coefficient of sliding friction, depending on the material and the state of the surface of the contacting bodies, and is always less 
.
The rolling friction force occurs when a body, having the shape of a cylinder or a ball of radius R, rolls along the surface of the support. The numerical value of the rolling friction force is determined in accordance with the Coulomb law
,
(2.55)
where k[m] is the coefficient of rolling friction.
It is believed that any physical body in the universe has its own gravitational field. This gravitational field is formed as a set of gravitational fields of all particles, atoms and molecules that make up this physical body. Depending on the mass, density and other characteristics of a physical body, the gravitational field of some physical bodies is different from others. Large physical bodies have a stronger and more extensive gravitational field and are able to attract other, smaller physical bodies. The value of the force of their mutual attraction to each other is determined by I. Newton's law of universal gravitation - gravity. This also applies to any physical body in the universe.
So what is the physical meaning of the gravity of physical bodies? What did the great genius I. Newton not have time to tell us?
Let's try to clarify this issue. In his theory, I. Newton considered not particles, but, first of all, planets and stars. We, before proceeding to the consideration of gravitational interactions between planets and stars in the Universe, already having an idea of the gravitational interaction of particles, will try to understand the gravitational interaction between physical bodies on Earth and understand what is the general physical meaning of gravity.
Assumption
I guess that physical meaning of gravity in general, it consists in the constant desire of the rarefied ethereal region of the physical body to move into an equilibrium state with the surrounding ethereal medium, reducing its stressed state, due to the attraction of other rarefied ethereal regions of other physical bodies into the region of its ethereal rarefaction.
If we consider the gravitational interaction of our planet and any other physical body that is raised above the earth or has come to us from space, then we can state that any other physical body always falls to the surface of the Earth. Usually, in this case, we say that the Earth, due to gravity, attracts physical bodies to itself. However, no one has yet been able to understand and explain the mechanism of this attraction.
At the same time, the physical essence of this mysterious phenomenon is explained by the fact that rarefied on-air environment at the surface of the earth is more rarefied than at a distance from it. In other words, the gravitational field and the force of attraction of the Earth at its surface is more powerful than at a distance from the planet. Note that we are talking only about the ethereal medium, and not about the Earth's atmosphere, in which there are atoms, molecules and the smallest particles of various chemicals. It is the filling of the ethereal medium with these chemical substances that gives the rarefied ethereal medium in the Earth's atmosphere an additional density.
The ethereal medium itself constitutes not only the Earth's atmosphere. It completely unhindered permeates the entire body of the planet. All particles that make up everything that exists on Earth and what it consists of, including its atmosphere, crust, mantle and core, rotate in an ethereal vortex that has not stopped for many billions of years. At the same time, the rotation of the planet, as well as the rotation of all planets and stars in the Universe, is provided by the influence of their ethereal vortices. The ethereal medium of the Earth rotates in concert with it and its atmosphere.
The sparseness of the ethereal medium depends only on the distance to the center of the Earth and does not depend on the density of the earth's crust or mantle. Therefore, the indicators of the Earth's attraction force also do not depend on the density of rocks, water or air, but only on how far from the center of the planet we measure this force.
To prove this is quite simple, using the data of the gravitational acceleration of physical bodies (gravitational acceleration) at various distances from the surface of the planet. For example, on the surface of the earth it will be equal to 9.806 m / s 2, at a height of 5 km - 9.791 m / s 2, at a height of 10 km - 9.775 m / s 2, 100 km - 9.505 m / s 2, 1000 km - 7.36 m/sec 2,
10,000 km - 1.5 m / s 2, and at an altitude of 400,000 km - 0.002 m / s 2.
These data indicate that with increasing distance from the center of the Earth, the density of the ethereal medium also increases, which leads to a decrease in the acceleration of free fall and the force of gravity of the Earth.
Closer to the center of the planet, the rarefaction of the ethereal medium increases. The increase in rarefaction of the ethereal medium predetermines the increase in gravitational acceleration, and, consequently, the body weight. This confirms our understanding of the physical essence of gravity, as such.
When any other physical body enters the planet's gravitational field, it finds itself in a position where the ethereal medium above the falling body is always denser than the ethereal medium below this body. Then, a denser ethereal medium will act on the body, moving it from a denser medium to a less dense one. The body, as if, constantly loses its support under itself and “falls through” in space towards the ground.
It is known that the value of the free fall acceleration at the equator is 9.75 m/sec 2 , which is less than the value of this indicator at the Earth's poles, which reaches 9.81 m/sec 2 . Scientists explain this difference by the daily rotation of the Earth around its axis, the deviation of the Earth's shape from spherical and the heterogeneous distribution of the density of earth rocks. In fact, only the specific shape of the planet can be taken into account. Everything else, if it has its influence on the value of the acceleration of gravity at the equator and at the poles, is very, very insignificant.
However, our views on gravity and the reasons for its manifestation will be well confirmed if we imagine a classical sphere, the most distant points of which from the center of the Earth will be located at the equator. In this case, at the poles from the surface of this classical speculative sphere to the surface of the Earth, a distance equal to 21.3 km is formed. This is easily explained by the somewhat flattened shape of the planet. Therefore, the distance from the earth's surface at the pole to the center of the earth is less than the same distance at the equator. But then, in accordance with our views, the ethereal medium at the poles of the planet is more rarefied and, therefore, its gravitational field is more powerful, which leads to higher rates of free fall acceleration.
This happens because the rarefied area of a more massive physical body initially captures the rarefied ethereal area of another physical body, and then brings the physical body itself closer to itself, which has a smaller mass or a smaller amount of condensed ether.
In view of the fact that it is impossible to remove the tension of the ethereal medium by attracting new physical bodies into the gravitational field of a massive physical body, since in this case its mass will only increase, and, consequently, the gravitational field will only expand, this desire will continue constantly, providing gravitational constancy of physical bodies. Therefore, a physical body, attracting other physical bodies to itself, will only increase its mass, and, consequently, its gravitational field.
In the ethereal space of the Universe, this process will take place until the gravitational forces of one planet or star are balanced with the gravitational forces of other planets and stars, as well as with the core of their own galaxy and the core of the Universe. In this case, all planets or stars will be in a tense, but balanced state in relation to each other.
The forces of gravity between physical bodies begin to manifest themselves from the moment of contact of the gravitational fields of these bodies. Based on this, it can be assumed that gravity does indeed have long-range. At the same time, the gravitational interaction begins to manifest itself almost instantly and, of course, without any participation of any gravitons or other incomprehensible particles.
From all this it follows that not physical bodies interact, but their gravitational fields interact, which, being deformed, attract physical bodies to each other. Excuse me, but this contradicts the provisions of the laws of the respected I. Newton, which postulate the force of attraction masses physical bodies and which have faithfully served and are serving humanity for more than one century!
I wouldn't be so dramatic. Our statements do not reject the laws of a highly respected scientist. They only reveal their physical essence, leaving the question of the manifestation of these laws absolutely untouched.
And that's exactly it. But according to I. Newton's law, any physical body has its own gravitational field and interacts with other physical bodies in accordance with their masses and distances between their centers. At the same time, I. Newton, first of all, had in mind the interaction of planets and stars. His scientific followers mechanically transferred the features of the interaction of planets and stars to the interaction of any physical bodies, based on the universality of the law of universal gravitation.
At the same time, they did not pass by the fact that on our planet, the Earth regularly attracts any physical bodies, but the physical bodies themselves do not really tend to each other. Except, of course, magnets. Apparently, in order not to violate the scientific idyll and not to question the law of universal gravitation, scientists postulated that the masses of the physical bodies surrounding us on our planet on a universal scale are extremely small and therefore the force of gravity when they approach each other is very, very weak.
However, we can try to bring conscientiously polished physical bodies from any substance close to each other, practically eliminating the presence of a distance between them. It would seem that, in accordance with the law, the forces of gravity should break out and surprise us with their undivided presence and remote power. But that doesn't happen. The forces of gravity modestly and without much enthusiasm silently observe our efforts from the most remote corner of every interacting physical body. What's the matter? How to get out of this delicate situation. After all, is there a law? There is. Does it work? Valid. So everything is fine?!
No, not normal. If we adhere to this statement, then many objects located next to each other would “stick together” in an instant, filling our lives with such problems that humanity, having resisted for a short time, would have ceased its nightmarish existence long ago.
One can object and refer to the fact that these physical bodies are very small. Therefore, they are not attracted. But this is not very convincing. Why? Because the huge, even on the scale of the Earth, the Tibetan mountain range would have long ago gathered on its harsh peaks all the planes flying by and would not allow tireless travelers and climbers, due to the powerful manifestation of their gravitational forces, to lift even the lightest ammunition. And it is unlikely that anyone can suspect the harsh Tibet of insufficient size, density or mass.
What to do? To the aid of adherents of omnipotent formulas, rather dubious coefficients again came in the form of the "gravitational constant" - not entirely convincing Mrs. "G", equal to approximately 6.67x10 -11 kg -1 m 3 sec -2. The presence of this constant in I. Newton's formula immediately turned the value of any force into practically nothing. Why this particular number? Simply because humanity simply cannot provide comparable indicators of the mass of any physical body on our planet. Therefore, judging by the value of this constant, the force of attraction of any physical bodies on Earth will be extremely small. And this will perfectly explain the lack of visible interaction of physical bodies on Earth.
And why 10 -11 kg -1? Yes, because the mass of the Earth, which certainly attracts all physical bodies without exception (it is not possible to hide this), is approximately 6x10 24 kg. Therefore, only for her 10 -11 kg -1 is easily overcome. Here is an original solution to the problem.
Failing to explain the essence of the problem, pundits, as often happens, introduced a certain constant value into the formula, which, without solving the problem, made it possible to give a certain near-scientific clarity to a physical process or natural phenomenon.
By the way, I. Newton, it seems, had nothing to do with this. In his works, when developing the law of universal gravitation, he never mentioned any gravitational constant. Neither did his contemporaries mention her. For the first time, the gravitational constant was introduced into the law of universal gravitation only at the beginning of the 19th century by the French physicist, mathematician and mechanic S.D. Poisson. However, history has not recorded a single scientist who would take responsibility for both the methodology for calculating it and for its generally accepted values.
The story refers to the English physicist Henry Cavendish, who in 1798 set up a unique experiment using a torsion balance. But it should be noted that G. Cavendish set up his experiment only to determine the average density of the Earth and he never spoke or wrote about any gravitational constant. Moreover, I did not calculate any of its numerical values.
The numerical indicator of the gravitational constant, allegedly, was calculated much later on the basis of G. Cavendish's calculations of the average density of the Earth, but who and when calculated it remained a mystery, as well as what all this was for.
And, apparently, in order to completely confuse humanity and somehow get out of the forest of contradictions and inconsistencies, in the modern scientific world they were forced, under the guise of a transition to a single metric system of measures, to accept different gravitational constants for various space systems. So, when calculating the orbits of, for example, satellites relative to the Earth, the geocentric gravitational constant is used equal to GE \u003d 3.98603x10 14 m 3 sec -2 multiplied by the mass of the Earth, and to calculate the orbits of celestial bodies relative to the Sun, another gravitational constant is used - heliocentric, equal to GSs = 1.32718x10 20 m 3 sec -2 times the mass of the Sun. It turns out interestingly, the law is one and universal, and the constant coefficients are different! How can such a respected "permanent" be so surprisingly non-permanent?!
So how to be? The situation is hopeless and therefore it is necessary to reconcile? No. You just need to go back to the basics and define the concepts. The fact is that everything that exists on the planet Earth, came out of it, is its property and will enter it. Everything - mountains, seas and oceans, trees, houses, factories, cars, and you and me - all this is mined, nurtured, nurtured and nurtured on Earth and created from Earth. All this is just different time e variable combinations of a huge number of atoms and molecules that belong only to our planet.
The Earth was created from particles and atoms and is a completely independent and almost completely closed system. During its formation, each particle and each atom, creating a single gravitational field of the planet, in fact, “transferred” to it all their gravitational powers.
Therefore, there is a single gravitational field on Earth, which conscientiously stands guard over all available earthly resources, not releasing from the planet what was once brought to this planet. Therefore, all objects and everything that is on Earth, are not independent gravitational substances and cannot decide whether or not to use their gravitational abilities when communicating with other physical bodies. Therefore, physical bodies on the Earth fall only down, onto its surface, and not up, left or right, joining other massive bodies. Therefore, no physical body on Earth, from the point of view of gravity, can be called independent.
But what about rockets? Can they be called independent physical bodies? As long as they are here on Earth - no, you can't. But if they overcome the gravity of the Earth and go beyond the gravitational field of the planet, then - yes, you can. Only in this case they will be able to become independent physical bodies in relation to the Earth, taking with them their individual part of the gravitational field. The Earth will decrease in size and in its mass by the size and mass of the rocket. Its gravitational field will decrease proportionally. The gravitational relationship between the rocket and the Earth will, of course, break.
And what about the various meteorites that visit our Earth quite often? Are they independent physical bodies or not? As long as they are outside the gravitational field of the Earth, they are independent. But when they enter the gravitational field of the planet, having their own less rarefied ethereal medium, they will interact with the more rarefied ethereal medium of the Earth.
However, the interaction of the gravitational fields of the Earth and the meteorite differs from the interaction of the gravitational fields of ethereal vortex clots that are almost equal in size to each other. This is due to the huge difference in the size of the gravitational fields of the Earth and the meteorite. The gravitational field of a meteorite, when interacting with the gravitational field of the Earth, practically does not deform, but, remaining an accessory of the meteorite, is absorbed by the gravitational field of the Earth.
The gravitational field of the meteorite seems to fall into the gravitational field of the Earth, because as it approaches the Earth's surface, its rarefied ethereal medium becomes more and more rarefied. And the closer to the Earth, the more rarefied its environment is, and the faster the meteorite moves towards the planet. The Earth seeks to replace its rarefied environment with an unexpected alien from space, creating the effect of attracting a meteorite to its surface.
Having reached the Earth's surface, the meteorite does not lose its gravitational field, and in the case of its transportation to outer space, it will leave the Earth with its gravitational field. But on Earth, he loses his independence of the physical body. Now it belongs to the Earth, its gravitational field is added to the gravitational field of the Earth, and the mass of the Earth is increased by the mass of the meteorite.
Therefore, we are forced to state that, being on the planets, all physical bodies from the gravitational point of view cannot be independent physical bodies. Their gravitational capabilities are within the gravitational capabilities of the planets, which are the main generators of gravitational interaction.
Therefore, the law of universal gravitation is absolutely fair to the entire universal system and does not require any additional constants, even gravitational ones.
Assumption
Thus, gravitational field of a physical body- this is an unevenly tense rarefied ethereal region, which belongs to the physical body and has arisen as a result of the concentration of the rotating ethereal medium in the physical body itself.
The gravitational field of any physical body, in order to achieve equilibrium with the surrounding elastic ethereal medium, tends to increase its density, attracting rarefied ethereal regions of other physical bodies to itself. The interaction of the gravitational fields of physical bodies with each other creates the effect of attraction of physical bodies. This effect is the action of gravitational forces or gravitational interaction of independent physical bodies.
The rarefied ethereal space always strives to restore the initial homogeneous state of the ethereal medium by adding the ethereal medium of other physical bodies. When a physical body appears in the ethereal gravitational field, some other physical body that also has its own ethereal gravitational field, but with a smaller mass, the first physical body seeks to “absorb” it and hold it with a force depending on the masses of these bodies and the distance between them .
Consequently, in the ethereal gravitational field, when two or more physical bodies appear in it, the process of their gravitational interactions, which guides them towards each other. Gravitational forces act only to approach some physical bodies or a body to other bodies.
Once again I have to admit that all this is possible only under ideal conditions, when physical bodies are not influenced by the gravitational forces of the planet. On Earth, the gravitational fields of all physical bodies are only an integral part of the unified gravitational field of the planet and cannot manifest themselves in relation to each other.
Therefore, physical bodies on the planet do not have their own individual gravitational field and have gravitational interaction only with the Earth.
Raising the physical body to a certain height, we do some work and expend a certain amount of energy. Some believe that by lifting the body, we transfer to it energy equivalent to the energy expended in lifting it to a certain height. Falling, the physical body releases this energy.
But it's not.
We do not transfer energy to it, but expend our energy to overcome the gravitational force of the Earth. Moreover, we seem to be disrupting the usual course of events on Earth by changing the location of the physical body relative to the planet. The Earth rightly reacts to this disgrace that is inconsistent with it and seeks to return any object to its surface, immediately turning on its gravitational forces.
The gravitational force acts on the lifted body in the same way as when this body is on the Earth, but with increasing distance from the Earth's surface, its value will be less than the initial gravitational force. True, it will not be so easy to notice it due to the insignificance of changes in the parameters of this force. If we raise this body to a height of 450 kilometers above the Earth, then the force of gravity will decrease significantly and the body will be in a state of weightlessness.
Here we meet with gravity, i.e. with impact gravitational ethereal medium our planet to the physical body. The raised body is located in the gravitational ethereal field of the planet, the vector of which is directed towards the center of the Earth. The closer the physical body is to the Earth, the effect gravitational interaction stronger. The further, the less. Therefore, at long distances, the gravitational interaction will also manifest itself, but not so clearly.
But, falling to the Earth, the physical body interacts with it in the same way as two bodies interact in space. The gravitational forces of the Earth act on the body, move it in space, returning it to the mortal earth.
What will happen if we act on the body for a long time, moving it farther and farther from the Earth, and, finally, take it out of the solar system? Does this mean that the gravitational interaction between them will disappear? If so, is there a possibility that, in doing so, the Earth will lose some of its gravitational capabilities?
Yes, that is exactly what will happen. Part of the gravitational potential of the Earth will leave it along with the physical body. The earth will become smaller by the amount of the mass of this body. And if the mass of the Earth becomes smaller, then it is quite obvious that its gravitational power will proportionally change to a smaller side, and its gravitational interaction with this physical body will disappear.
But if a meteorite falls on the Earth's surface, then its gravitational field will be "absorbed" by the Earth's gravitational field, and, having lost its independence, it will become a part of the Earth, proportionally increasing its gravitational capabilities.
Therefore, larger physical bodies, including planets and stars, have stronger gravity and attract smaller ones, absorbing them. By attracting smaller physical bodies to themselves, they increase their mass and, accordingly, increase their gravitational field. Between bodies there will be a gravitational interaction.
So, around any physical body on our planet has its own gravitational field, but only conditionally. This gravitational field enters the unified gravitational field of the Earth and rotates with it. This is due to the fact that any physical body, including all physical bodies created on Earth or flown in from outer space, is already or is becoming belonging to our planet. Any physical body on Earth originated from it and into it and will return. Their gravitational field is part of the unified gravitational field of the Earth, which rotates around the planet. Therefore, objects fall to the Earth, and do not join each other. They fall down instead of moving parallel to the ground. In addition, the gravitational capabilities of the Earth are incomparably more powerful than the gravitational capabilities of any physical body on the planet, no matter what size, volume or density it has. Therefore, any physical body is attracted to the Earth, and not to Everest.
All physical bodies have a gravitational field, but it can only be considered in conjunction with the general gravitational field of the Earth. It is possible to separate it from the gravitational field of the Earth only at a distance beyond the boundaries of the gravitational field of the planet. At this distance, the gravitational field of a physical body, for example, a rocket, will be completely independent and will rotate around the physical body, no matter what size it is.
It should be noted that the speed of rotation of the ethereal medium near the surface of the physical body is equal to the speed of rotation of the physical body itself. In relation to the physical body, the environment is motionless. Near a physical body, the gravitational force is much higher than away from it. Let's recall our experience with a rubber circle (Fig. 2). As you move away from the physical body, both the speed of rotation of the ethereal medium and gravity decrease.
At the same time, we understand that the concentration of ether under the influence of ethereal vortices and gravitational forces leads to the emergence of a rarefied ethereal region around the physical body. This rarefied ethereal area is the greater, the more ether is concentrated in the physical body in the form of a set of fundamental ethereal particles - ethereal vortex clots, of which energy fractions, photons, neutrinos, antineutrinos, positrons, electrons, protons, neutrons, atoms, molecules, respectively, consist and other physical bodies. The rarefied ethereal region, for example, of the planet Earth is much larger in volume than the rarefied region of the Moon, since the Earth is much larger than the Moon. And each rarefied area corresponds to the amount of ether concentrated in the physical body.
The rarefied regions of the ethereal medium are extremely vast. They size gravitational fields physical bodies, i.e. those areas in which gravitational forces act. The actions of these forces begin from the outer boundaries of the rarefied area of the physical body. Since the boundaries of the rarefied region are far enough from the center of the physical body, these forces can be characterized as long-range forces or long-range interaction.
When rarefied areas of two or more physical bodies come into contact, each of them, in accordance with the law of balance of opposites, seeks to balance its ethereal rarefied medium, which leads to attraction and convergence of bodies.
Thus, it is not the masses of physical bodies that attract, but the gravitational fields of these physical bodies interact with each other, moving the physical bodies towards each other.
Moreover, the closer the bodies are to each other, the more pronounced and intense this attraction is. Therefore, when falling, for example, bodies to the ground, there is a constant acceleration of this fall. This acceleration is called free fall acceleration and is equal to approximately 9.806 m/s 2 .
The essence of this acceleration lies in the fact that the closer the rarefied medium is to the body, the less dense it is and, therefore, the stronger the desire of the physical body to balance its rarefied ethereal medium, the more powerful the force of gravitational interaction. We have already talked about this before. With approaching the boundary of a rarefied medium with an elastic ethereal space, this tension decreases and, finally, at the boundary it begins to fully correspond to the density of the ethereal space. In this case, the gravitational interaction of the physical body completely loses its strength, and the gravitational field of this physical body disappears.
This explains the fact that from the beginning of its launch, a rocket spends a huge amount of energy to overcome the Earth's gravity, but as it flies and moves away from the planet, it enters orbit and practically does not waste its energy.
Here it is necessary to understand that the density of the Earth's atmosphere and the density of its gravitational field are different concepts. The density of the Earth's atmosphere has higher values at its surface than at altitude. For example, on the surface of the earth, the density of the atmosphere is approximately equal to 1.225 kg / m 3, at a height of 2 kilometers - 1.007 kg / m 3, and at a height of 3 km - 0.909 kg / m 3 i.e. As altitude increases, the density of the atmosphere decreases.
But we argue that the gravitational field of any physical body is more rarefied precisely at its surface, and this rarefaction decreases with increasing distance from the physical body. Contradiction? Not at all. This is confirmation of our reasoning! The fact is that the rarefied ethereal gravitational field will tend to draw into its space everything that is possible to reduce its tension. Therefore, the gravitational field of the Earth is filled with molecules of nitrogen, oxygen, hydrogen, etc. In addition, near the surface of the earth in the atmosphere there are not only gas molecules, but also particles of dust, water, ice crystals, sea salt, and so on. The higher from the Earth's surface, the less rarefied the gravitational field is, the fewer molecules and particles it can hold in the Earth's atmosphere, the lower the density of the planet's atmosphere, respectively. Everything matches. Everything is correct.
To prove this statement, we cite the reflections of Aristotle and the experiments of G. Galileo and I. Newton. The great Aristotle argued that heavier bodies fall to the ground faster than light bodies and gave the example of a stone and a bird's feather falling from the same height. Unlike Aristotle, G. Galileo suggested that the reason for the difference in the speed of falling objects is air resistance. It is alleged that he simultaneously dropped a rifle bullet and an artillery ball from the Leaning Tower of Pisa, which also reached the ground almost simultaneously, despite the significant difference in weight.
In support of G. Galileo's conclusions, I. Newton pumped air out of a long glass tube and at the same time threw a bird's feather and a gold coin on top. Both the pen and the coin fell almost simultaneously to the bottom of the tube. Later, it was experimentally established that both in air and in vacuum there was an acceleration of the free fall of bodies to the ground.
However, scientists, having fixed the presence of acceleration of free fall of bodies to the ground, limited themselves only to the derivation of known mathematical dependencies, which make it possible to accurately measure the magnitude of this acceleration. But the physical essence of this acceleration remained undiscovered.
I believe that the physical essence of this phenomenon lies in the presence of a rarefied ethereal medium around the Earth. The closer to the surface of the Earth is the body falling on it, the more rarefied the ethereal medium of the planet and the faster the body falls on its surface. This can be accepted as a clear confirmation of our reasoning about the nature of gravitational fields and the mechanism of their interactions in the Universe.
Of course, our statement about the interaction of the gravitational fields of physical bodies, and not about the mutual influence of their masses, contradicts the views of the highly respected I. Newton and the modern scientific community. However, paying tribute to the great genius, we unequivocally recognize the fact that the formula he derived is quite indicative and quite rightly allows us to calculate the force of the gravitational interaction of two physical bodies. It should also be recognized that the Newtonian formula describes the consequence of a phenomenon, but does not at all concern its physical essence.
Thus, we have determined that the constant desire of the rarefied ethereal region of any physical body to move into an equilibrium state with the surrounding ethereal medium, reducing its stressed state, due to the attraction of other rarefied ethereal regions of other physical bodies to the region of its ethereal rarefaction, constitutes a general the physical meaning of gravity or gravitational interaction.
Every physical body has its own gravitational field, but it is not independent. Being on the Earth, this gravitational field is united into a single gravitational field of the planet. The gravitational field of any physical body can only be considered as part of the gravitational field of the planet.
Gravity (universal gravitation, gravitation)(from lat. gravitas - "gravity") - a long-range fundamental interaction in nature, to which all material bodies are subject. According to modern data, it is a universal interaction in the sense that, unlike any other forces, it gives the same acceleration to all bodies without exception, regardless of their mass. Primarily gravity plays a decisive role on a cosmic scale. Term gravity also used as the name of a branch of physics that studies the gravitational interaction. The most successful modern physical theory in classical physics, describing gravity, is the general theory of relativity, the quantum theory of gravitational interaction has not yet been built.
Gravitational interaction
Gravitational interaction is one of the four fundamental interactions in our world. Within classical mechanics, the gravitational interaction is described by law of gravity Newton, who states that the force of gravitational attraction between two material points of mass m 1 and m 2 separated by distance R, is proportional to both masses and inversely proportional to the square of the distance - i.e.
.Here G- gravitational constant, equal to approximately 
m³/(kg s²). The minus sign means that the force acting on the body is always equal in direction to the radius vector directed to the body, that is, the gravitational interaction always leads to the attraction of any bodies.
The law of universal gravitation is one of the applications of the inverse square law, which is also encountered in the study of radiation (see, for example, Light Pressure), and which is a direct consequence of the quadratic increase in the area of the sphere with increasing radius, which leads to a quadratic decrease in the contribution of any unit area to the area of the entire sphere.
The simplest task of celestial mechanics is the gravitational interaction of two bodies in empty space. This problem is solved analytically to the end; the result of its solution is often formulated in the form of Kepler's three laws.
As the number of interacting bodies increases, the problem becomes much more complicated. So, the already famous three-body problem (that is, the motion of three bodies with non-zero masses) cannot be solved analytically in a general form. With a numerical solution, the instability of solutions with respect to the initial conditions sets in rather quickly. When applied to the solar system, this instability makes it impossible to predict the motion of the planets on scales exceeding a hundred million years.
In some special cases, it is possible to find an approximate solution. The most important is the case when the mass of one body is significantly greater than the mass of other bodies (examples: the solar system and the dynamics of Saturn's rings). In this case, in the first approximation, we can assume that light bodies do not interact with each other and move along Keplerian trajectories around a massive body. Interactions between them can be taken into account in the framework of perturbation theory, and averaged over time. In this case, non-trivial phenomena may arise, such as resonances, attractors, randomness, etc. A good example of such phenomena is the non-trivial structure of Saturn's rings.
Despite attempts to describe the behavior of a system of a large number of attracting bodies of approximately the same mass, this cannot be done due to the phenomenon of dynamic chaos.
Strong gravitational fields
In strong gravitational fields, when moving at relativistic speeds, the effects of general relativity begin to appear:
- deviation of the law of gravity from Newtonian;
- potential delay associated with the finite propagation velocity of gravitational perturbations; the appearance of gravitational waves;
- non-linear effects: gravitational waves tend to interact with each other, so the principle of superposition of waves in strong fields is no longer valid;
- change in the geometry of space-time;
- the emergence of black holes;
Gravitational radiation
One of the important predictions of general relativity is gravitational radiation, the presence of which has not yet been confirmed by direct observations. However, there is indirect observational evidence in favor of its existence, namely: the energy loss in the binary system with the PSR B1913+16 pulsar - the Hulse-Taylor pulsar - is in good agreement with the model in which this energy is carried away by gravitational radiation.
Gravitational radiation can only be generated by systems with variable quadrupole or higher multipole moments, this fact suggests that the gravitational radiation of most natural sources is directional, which greatly complicates its detection. Gravity power l-poly source is proportional (v / c) 2l + 2 , if the multipole is of electric type, and (v / c) 2l + 4 - if the multipole is magnetic type , where v is the characteristic velocity of sources in the radiating system, and c is the speed of light. Thus, the dominant moment will be the quadrupole moment of the electric type, and the power of the corresponding radiation is equal to:
where Q ij is the tensor of the quadrupole moment of the mass distribution of the radiating system. Constant 
(1/W) makes it possible to estimate the order of magnitude of the radiation power.
Since 1969 (Weber's experiments (English)) and up to the present (February 2007), attempts have been made to directly detect gravitational radiation. In the USA, Europe and Japan, there are currently several operating ground-based detectors (GEO 600), as well as a project for a space gravitational detector of the Republic of Tatarstan.
Subtle effects of gravity
In addition to the classical effects of gravitational attraction and time dilation, the general theory of relativity predicts the existence of other manifestations of gravity, which are very weak under terrestrial conditions and therefore their detection and experimental verification are therefore very difficult. Until recently, overcoming these difficulties seemed beyond the capabilities of experimenters.
Among them, in particular, one can name the drag of inertial reference frames (or the Lense-Thirring effect) and the gravitomagnetic field. In 2005, NASA's robotic Gravity Probe B conducted an experiment of unprecedented accuracy to measure these effects near the Earth, but the full results have not yet been published.
quantum theory of gravity
Despite more than half a century of attempts, gravity is the only fundamental interaction for which a consistent renormalizable quantum theory has not yet been built. However, at low energies, in the spirit of quantum field theory, the gravitational interaction can be represented as an exchange of gravitons - gauge bosons with spin 2.
Standard Theories of Gravity
Due to the fact that the quantum effects of gravity are extremely small even under the most extreme experimental and observational conditions, there are still no reliable observations of them. Theoretical estimates show that in the overwhelming majority of cases one can confine oneself to the classical description of the gravitational interaction.
There is a modern canonical classical theory of gravity - the general theory of relativity, and many hypotheses that refine it and theories of varying degrees of development that compete with each other (see the article Alternative theories of gravity). All of these theories give very similar predictions within the approximation in which experimental tests are currently being carried out. The following are some of the major, most well developed or known theories of gravity.
- Gravity is not a geometric field, but a real physical force field described by a tensor.
- Gravitational phenomena should be considered within the framework of the flat Minkowski space, in which the laws of conservation of energy-momentum and angular momentum are unambiguously fulfilled. Then the motion of bodies in the Minkowski space is equivalent to the motion of these bodies in the effective Riemannian space.
- In tensor equations, to determine the metric, one should take into account the mass of the graviton, and also use the gauge conditions associated with the metric of the Minkowski space. This does not allow destroying the gravitational field even locally by choosing some suitable frame of reference.
As in general relativity, in RTG, matter refers to all forms of matter (including the electromagnetic field), with the exception of the gravitational field itself. The consequences of the RTG theory are as follows: black holes as physical objects predicted in general relativity do not exist; The universe is flat, homogeneous, isotropic, immobile and Euclidean.
On the other hand, there are no less convincing arguments of RTG opponents, which boil down to the following points:
A similar thing happens in RTG, where the second tensor equation is introduced to take into account the connection between the non-Euclidean space and the Minkowski space. Due to the presence of a dimensionless fitting parameter in the Jordan-Brans-Dicke theory, it becomes possible to choose it so that the results of the theory coincide with the results of gravitational experiments.
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Sources and notes
Literature
- Vizgin V.P. Relativistic theory of gravity (origins and formation, 1900-1915). M.: Nauka, 1981. - 352c.
- Vizgin V.P. Unified theories in the 1st third of the twentieth century. M.: Nauka, 1985. - 304c.
- Ivanenko D. D., Sardanashvili G. A. Gravity, 3rd ed. M.: URSS, 2008. - 200p.
see also
- gravimeter
Links
- The law of universal gravitation or "Why does the moon not fall to the Earth?" - Just about the complex
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