The Law of Universal Gravity is an invention of parasites. The history of the discovery of the law of universal gravitation - description, features and interesting facts
When he came to a great result: the same cause causes phenomena of an amazingly wide range - from the fall of a thrown stone to the Earth to the movement of huge cosmic bodies. Newton found this reason and was able to accurately express it in the form of one formula - the law of universal gravitation.
Since the force of universal gravitation imparts the same acceleration to all bodies regardless of their mass, it must be proportional to the mass of the body on which it acts:
But since, for example, the Earth acts on the Moon with a force proportional to the mass of the Moon, then the Moon, according to Newton’s third law, must act on the Earth with the same force. Moreover, this force must be proportional to the mass of the Earth. If the force of gravity is truly universal, then from the side of a given body a force must act on any other body proportional to the mass of this other body. Consequently, the force of universal gravity must be proportional to the product of the masses of interacting bodies. This leads to the formulation law of universal gravitation.
Definition of the law of universal gravitation
The force of mutual attraction between two bodies is directly proportional to the product of the masses of these bodies and inversely proportional to the square of the distance between them:
Proportionality factor G called gravitational constant.
The gravitational constant is numerically equal to the force of attraction between two material points weighing 1 kg each, if the distance between them is 1 m. After all, when m 1 = m 2=1 kg and R=1 m we get G=F(numerically).
It must be borne in mind that the law of universal gravitation (4.5) as a universal law is valid for material points. In this case, the forces of gravitational interaction are directed along the line connecting these points ( Fig.4.2). This kind of force is called central.
It can be shown that homogeneous bodies shaped like a ball (even if they cannot be considered material points) also interact with the force determined by formula (4.5). In this case R- the distance between the centers of the balls. The forces of mutual attraction lie on a straight line passing through the centers of the balls. (Such forces are called central.) The bodies that we usually consider falling on the Earth have dimensions much smaller than the Earth’s radius ( R≈6400 km). Such bodies can, regardless of their shape, be considered as material points and determine the force of their attraction to the Earth using the law (4.5), keeping in mind that R is the distance from a given body to the center of the Earth.
Determination of the gravitational constant
Now let's find out how to find the gravitational constant. First of all, we note that G has a specific name. This is due to the fact that the units (and, accordingly, the names) of all quantities included in the law of universal gravitation have already been established earlier. The law of gravitation provides a new connection between known quantities with certain names of units. That is why the coefficient turns out to be a named quantity. Using the formula of the law of universal gravitation, it is easy to find the name of the SI unit of gravitational constant:
N m 2 / kg 2 = m 3 / (kg s 2).
For quantification G it is necessary to independently determine all the quantities included in the law of universal gravitation: both masses, force and distance between bodies. It is impossible to use astronomical observations for this, since the masses of the planets, the Sun, and the Earth can only be determined on the basis of the law of universal gravitation itself, if the value of the gravitational constant is known. The experiment must be carried out on Earth with bodies whose masses can be measured on a scale.
The difficulty is that the gravitational forces between bodies of small masses are extremely small. It is for this reason that we do not notice the attraction of our body to surrounding objects and the mutual attraction of objects to each other, although gravitational forces are the most universal of all forces in nature. Two people with masses of 60 kg at a distance of 1 m from each other are attracted with a force of only about 10 -9 N. Therefore, to measure the gravitational constant, fairly subtle experiments are needed.
The gravitational constant was first measured by the English physicist G. Cavendish in 1798 using an instrument called a torsion balance. The diagram of the torsion balance is shown in Figure 4.3. A light rocker with two identical weights at the ends is suspended from a thin elastic thread. Two heavy balls are fixed motionless nearby. Gravitational forces act between the weights and the stationary balls. Under the influence of these forces, the rocker turns and twists the thread. By the angle of twist you can determine the force of attraction. To do this, you only need to know the elastic properties of the thread. The masses of the bodies are known, and the distance between the centers of interacting bodies can be directly measured.
From these experiments it was obtained next value for the gravitational constant:
Only in the case when bodies of enormous mass interact (or at least the mass of one of the bodies is very large) does the gravitational force reach a large value. For example, the Earth and the Moon are attracted to each other with a force F≈2 10 20 H.
Dependence of the acceleration of free falling bodies on geographic latitude
One of the reasons for the increase in the acceleration of gravity when the point where the body is located moves from the equator to the poles is that the globe is somewhat flattened at the poles and the distance from the center of the Earth to its surface at the poles is less than at the equator. Another, more significant reason is the rotation of the Earth.
Equality of inertial and gravitational masses
The most striking property of gravitational forces is that they impart the same acceleration to all bodies, regardless of their masses. What would you say about a football player whose kick would be equally accelerated by an ordinary leather ball and a two-pound weight? Everyone will say that this is impossible. But the Earth is just such an “extraordinary football player” with the only difference that its effect on bodies is not of the nature of a short-term blow, but continues continuously for billions of years.
The extraordinary property of gravitational forces, as we have already said, is explained by the fact that these forces are proportional to the masses of both interacting bodies. This fact cannot but cause surprise if you think about it carefully. After all, the mass of a body, which is included in Newton’s second law, determines the inertial properties of the body, that is, its ability to acquire a certain acceleration under the influence of a given force. It is natural to call this mass inert mass and denote by m and.
It would seem, what relation can it have to the ability of bodies to attract each other? The mass that determines the ability of bodies to attract each other should be called gravitational mass m g.
It does not at all follow from Newtonian mechanics that the inertial and gravitational masses are the same, i.e. that
Equality (4.6) is a direct consequence of experiment. It means that we can simply talk about the mass of a body as a quantitative measure of both its inertial and gravitational properties.
The law of universal gravitation is one of the most universal laws of nature. It is valid for any bodies with mass.
The meaning of the law of universal gravitation
But if we approach this topic more radically, it turns out that the law of universal gravitation does not have the possibility of its application everywhere. This law has found its application for bodies that have the shape of a ball, it can be used for material points, and it is also acceptable for a ball having a large radius, where this ball can interact with bodies much smaller than its size.
As you may have guessed from the information provided in this lesson, the law of universal gravitation is the basis in the study of celestial mechanics. And as you know, celestial mechanics studies the movement of planets.
Thanks to this law of universal gravitation, it became possible to more accurately determine the location of celestial bodies and the ability to calculate their trajectory.
But for a body and an infinite plane, as well as for the interaction of an infinite rod and a ball, this formula cannot be applied.
With the help of this law, Newton was able to explain not only how the planets move, but also why sea tides arise. Over time, thanks to the work of Newton, astronomers managed to discover such planets of the solar system as Neptune and Pluto.
The importance of the discovery of the law of universal gravitation lies in the fact that with its help it became possible to make forecasts of solar and lunar eclipses and accurately calculate the movements of spacecraft.
The forces of universal gravity are the most universal of all the forces of nature. After all, their action extends to the interaction between any bodies that have mass. And as you know, any body has mass. The forces of gravity act through any body, since there are no barriers to the forces of gravity.
Task
And now, in order to consolidate knowledge about the law of universal gravitation, let's try to consider and solve an interesting problem. The rocket rose to a height h equal to 990 km. Determine how much the force of gravity acting on the rocket at a height h has decreased compared to the force of gravity mg acting on it at the surface of the Earth? Radius of the Earth R = 6400 km. Let us denote by m the mass of the rocket, and by M the mass of the Earth.
At height h the force of gravity is:
From here we calculate:
Substituting the value will give the result:
The legend about how Newton discovered the law of universal gravitation after hitting the top of his head with an apple was invented by Voltaire. Moreover, Voltaire himself assured that this true story was told to him by Newton’s beloved niece Katherine Barton. It’s just strange that neither the niece herself nor her very close friend Jonathan Swift ever mentioned the fateful apple in their memoirs about Newton. By the way, Isaac Newton himself, writing in detail in his notebooks the results of experiments on the behavior of different bodies, noted only vessels filled with gold, silver, lead, sand, glass, water or wheat, not to mention an apple. However, this did not stop Newton’s descendants from taking tourists around the garden on the Woolstock estate and showing them that same apple tree before the storm destroyed it.
Yes, there was an apple tree, and apples probably fell from it, but how great was the merit of the apple in the discovery of the law of universal gravitation?
The debate about the apple has not subsided for 300 years, just like the debate about the law of universal gravitation itself or about who has the priority of discovery.uk
G.Ya.Myakishev, B.B.Bukhovtsev, N.N.Sotsky, Physics 10th grade
The structure of the gravity field does not in any way come from the size of the planet’s mass. On the contrary, it is the intensity of this gravitational field (as one of the types of gravity), expressed by the magnitude of the field charge (gravitational acceleration), that forms the mass of the planet.
And this once again emphasizes the absurdity of expressing the force of gravity by a formula, called in traditional physical theory the formula of universal gravity, through the equality: Ft. = m*g= G*(m*Mз)/R 2, where “R” is the radius of the Earth plus the height of the body above the Earth’s surface, and Mz is the mass of the Earth, but actually denotes its weight (which is again absurd).
Please note that in addition to determining the “mass” of the Earth from the above equality, the charge of the gravity field (gravitational acceleration) is also expressed from it in the form “g = G*Mз/Rз. 2,” calling such a formula a kind of independent expression for the acceleration of free fall. At the same time, it is forgotten that the acceleration of free fall is expressed, naturally, without any consideration of masses, based on the formula for the path of fall of a body “ GT²/2" (And gOt²/4 in the physics of discrimination) and - from the formula of a reversible pendulum ( go=4piR/T 2).
Based on the absurd formula g=G*Mз/Rз. 2, accordingly, the absurd Schwarzschild formula was also derived, which states that stars tend to compress and, subsequently, to some kind of gravitational collapse. Such an absurd statement led to the absurd theory of certain “black holes”. And all these absurdities are expressed against the background of the facts of a decrease in the weight of bodies as they approach the center of the Earth and the independence of the nature of the fall of bodies from their mass.
Despite the fact that Newton, due to his time, was not familiar with the fact of physical fields, he actually designated the universal gravitational structure as a force or external manifestation of the entire space-time cosmic structure. After all, he revealed the dependence of the values of spatial charges of rotation (called centripetal rotational acceleration for the Moon and gravitational acceleration for the Earth) on the square of the radius between them without any consideration of masses.
This structural spatial dependence expressing the mutually centric outward force interaction of fields and is the law of universal gravity. But, considering the interactions of bodies, and not fields denoting bodies and individual charges, I. Newton expressed the law of universal gravity not rotationally and structurally, but linearly and mathematically: by the product of the gravitational charges of bodies (then replaced by masses).
These charges in Coulomb's law are already electric charges, and in Cavendish's experiment they are external molecular charges of bodies. And so the further replacement of I. Newton’s gravitational charges, denoting the external field or spatial characteristic (including that of a specific body) with masses, characterizing the internal field characteristic of bodies exclusively, led to the absurdity of the equality “Ft. = m*g= G*(m*Mз)/R 2 ".
After all, mass (not actually distinguished in traditional physics from the force of gravity) is a derivative of the internal molecular charge of the substance of the body. Thus, on the initial distortion of the law of universal gravitation, expressed in a linear rather than a rotational structural consideration of force, a distortion was superimposed in the form of replacing the external concept of gravitational charge with the internal physical concept of mass.
This resulted in a double distortion of the law of universal gravity. In this regard, it has nothing to do with the formation of gravity, since, firstly, universal gravity or gravitation means a rotationally structural, rather than linear, consideration of force. And, secondly, the linear consideration of force does not express internal characteristics bodies and internal field interaction, and - external spatial-field interaction of gravitational charges (by considering their rotational field characteristic, in the dimension of rotational acceleration).
And, indeed, the force of gravity, acting only on large cosmic bodies, and not in space, has nothing to do with the universal or universal gravity. The formation of gravity, naturally, relates to gravity, but indirectly through mass.
At the same time, the formation of gravity, as well as any strength, based on the comparison of rotational field charges by Newton himself, it is necessary to consider not linear or linear vectors, but rotationally structural or spiral vectors. Newton’s third law also speaks about the field or spherical origin of force, as spiral vectors of action and reaction.
And the very path of the fall of the body, which turns into the gravity vector, is the length of the unfolded circle with a radius equal to the arc of the semicircle described by the average radius of the Earth. Thus, in considering the law of universal gravity, relating to the circular mutually centric field space and to the rotational-structural expression of force, it was allowed to be combined with a linear expression of force (for example, in Coulomb’s law and in a similar expression of the force of external molecular interaction lead balls by G. Cavendish).
And this expression of force already applies to the pre-mass transition space (occupying about 20% of the total observable cosmic volume) and therefore applies to manifestation of the universal gravitational or external force structure, but not to the law of universal gravity. And then this linear designation of force was combined with the expression of gravity (and not in the form of “F=m*g0”, but in the form of “F=m*g” without distinguishing the meaning of the acceleration of gravity and the meaning of the concept of mass). The force of gravity, all the more, does not relate to the law of universal gravity, denoting only the direct mass space or the space of masses that occupies only around 5% of the entire observable cosmic volume.
And only in mass space do universal spherical lines receive a circumferential and then a rectilinear curvature. Therefore, a straight line, oddly enough, means the greatest, but precisely spatial curvature.
Also, I. Newton, due to his era, saw a universal category or universality, based only on the earthly environment, as from the indicated five percent. At the present time of space research, such a perception of gravity and world law gravity is no longer acceptable.
So, the movement of planets, for example the Moon around the Earth or the Earth around the Sun, is the same fall, but only a fall that lasts indefinitely (in any case, if we ignore the transition of energy into “non-mechanical” forms).
The conjecture about the unity of causes governing the movement of planets and the fall of earthly bodies was expressed by scientists long before Newton. Apparently, the first to clearly express this idea was the Greek philosopher Anaxagoras, a native of Asia Minor, who lived in Athens almost two thousand years ago. He said that the Moon, if it did not move, would fall to the Earth.
However, Anaxagoras’ brilliant guess, apparently, did not have any practical impact on the development of science. She was destined to be misunderstood by her contemporaries and forgotten by her descendants. Ancient and medieval thinkers, whose attention was attracted by the movement of the planets, were very far from the correct (and more often than not any) interpretation of the causes of this movement. After all, even the great Kepler, who, at the cost of enormous labor, was able to formulate the exact mathematical laws of planetary motion, believed that the cause of this motion was the rotation of the Sun.
According to Kepler's ideas, the Sun, rotating, constantly pushes the planets into rotation. True, it remained unclear why the time of revolution of the planets around the Sun differs from the period of revolution of the Sun around its own axis. Kepler wrote about this: “if the planets did not have natural resistance, then it would be impossible to give reasons why they should not follow exactly the rotation of the Sun. But although in reality all the planets move in the same direction in which the rotation of the Sun occurs, the speed of their movement is not the same. The fact is that they mix, in certain proportions, the inertia of their own mass with the speed of their movement.”
Kepler failed to understand that the coincidence of the directions of motion of the planets around the Sun with the direction of rotation of the Sun around its axis is not associated with the laws of planetary motion, but with the origin of our solar system. An artificial planet can be launched both in the direction of rotation of the Sun and against this rotation.
Robert Hooke came much closer than Kepler to the discovery of the law of attraction of bodies. Here are his actual words from a work entitled An Attempt to Study the Motion of the Earth, published in 1674: “I will develop a theory which is in every respect consistent with the generally accepted rules of mechanics. This theory is based on three assumptions: firstly, that all celestial bodies, without exception, have a gravity directed towards their center, due to which they attract not only their own parts, but also all celestial bodies within their sphere of action. According to the second assumption, all bodies moving in a rectilinear and uniform manner will move in a straight line until they are deflected by some force and begin to describe trajectories in a circle, an ellipse, or some other less simple curve. According to the third assumption, the forces of attraction act the more strongly, the closer to them the bodies on which they act are located. I have not yet been able to establish by experience what the different degrees of attraction are. But if we develop this idea further, astronomers will be able to determine the law according to which all celestial bodies move.”
Truly, one can only be amazed that Hooke himself did not want to engage in the development of these ideas, citing being busy with other work. But a scientist appeared who made a breakthrough in this area
The history of Newton's discovery of the law of universal gravitation is quite well known. For the first time, the idea that the nature of the forces that make a stone fall and determine the movement of celestial bodies is one and the same arose with Newton the student, that the first calculations did not give the correct results, since the data available at that time on the distance from the Earth to the Moon were inaccurate, that 16 years later new, corrected information about this distance appeared. To explain the laws of planetary motion, Newton applied the laws of dynamics he created and the law of universal gravitation that he himself established.
He named the Galilean principle of inertia as the first law of dynamics, including it in the system of basic laws-postulates of his theory.
At the same time, Newton had to eliminate the mistake of Galileo, who believed that uniform motion in a circle was motion by inertia. Newton pointed out (and this is the second law of dynamics) that the only way to change the motion of a body - the value or direction of the velocity - is to act on it with some force. In this case, the acceleration with which a body moves under the influence of a force is inversely proportional to the mass of the body.
According to Newton's third law of dynamics, “to every action there is always an equal and opposite reaction.”
Consistently applying the principles - the laws of dynamics, he first calculated the centripetal acceleration of the Moon as it moves in orbit around the Earth, and then was able to show that the ratio of this acceleration to the acceleration of free fall of bodies at the Earth's surface is equal to the ratio of the squares of the radii of the Earth and the lunar orbit. From this Newton concluded that the nature of gravity and the force that holds the Moon in orbit are the same. In other words, according to his conclusions, the Earth and the Moon are attracted to each other with a force inversely proportional to the square of the distance between their centers Fg ≈ 1∕r2.
Newton was able to show that the only explanation for the independence of the acceleration of free fall of bodies from their mass is the proportionality of the force of gravity to the mass.
Summarizing the findings, Newton wrote: “there can be no doubt that the nature of gravity on other planets is the same as on Earth. In fact, let us imagine that the earth's bodies are raised to the orbit of the Moon and sent together with the Moon, also devoid of any movement, to fall to the Earth. Based on what has already been proven (meaning the experiments of Galileo), there is no doubt that at the same times they will pass through the same spaces as the Moon, for their masses are related to the mass of the Moon in the same way as their weights are to its weight.” So Newton discovered and then formulated the law of universal gravitation, which is rightfully the property of science.
2. Properties of gravitational forces.
One of the most remarkable properties of the forces of universal gravitation, or, as they are often called, gravitational forces, is reflected in the very name given by Newton: universal. These forces, so to speak, are “the most universal” among all the forces of nature. Everything that has mass - and mass is inherent in any form, any kind of matter - must experience gravitational influences. Even light is no exception. If we visualize gravitational forces with the help of strings that stretch from one body to another, then an innumerable number of such strings would have to permeate space anywhere. At the same time, it is worth noting that it is impossible to break such a thread and protect yourself from gravitational forces. There are no barriers to universal gravity; their radius of action is unlimited (r = ∞). Gravitational forces are long-range forces. This is the “official name” of these forces in physics. Due to long-range action, gravity connects all bodies of the Universe.
The relative slowness of the decrease of forces with distance at each step is manifested in our earthly conditions: after all, all bodies do not change their weight when transferred from one height to another (or, to be more precise, they change, but extremely insignificantly), precisely because with a relatively small change in distance - in this case from the center of the Earth - gravitational forces practically do not change.
By the way, it is for this reason that the law of measuring gravitational forces with distance was discovered “in the sky.” All the necessary data was drawn from astronomy. One should not, however, think that a decrease in gravity with height cannot be detected under terrestrial conditions. So, for example, a pendulum clock with an oscillation period of one second will fall behind a day by almost three seconds if it is raised from the basement to the top floor of Moscow University (200 meters) - and this is only due to a decrease in gravity.
The altitudes at which artificial satellites move are already comparable to the radius of the Earth, so to calculate their trajectory, taking into account the change in the force of gravity with distance is absolutely necessary.
Gravitational forces have another very interesting and unusual property, which will be discussed now.
For many centuries, medieval science accepted as an unshakable dogma Aristotle's statement that a body falls the faster the greater its weight. Even everyday experience confirms this: it is known that a piece of fluff falls slower than a stone. However, as Galileo was able to show for the first time, the whole point here is that air resistance, coming into play, radically distorts the picture that would be if only earthly gravity acted on all bodies. There is a remarkable experiment with the so-called Newton tube, which makes it possible to very easily evaluate the role of air resistance. Here short description this experience. Imagine an ordinary glass tube (so that you can see what is happening inside) in which various objects are placed: pellets, pieces of cork, feathers or fluffs, etc. If you turn the tube over so that all this can fall, then the pellet will flash faster , followed by pieces of cork and, finally, the fluff will gradually fall. But let’s try to monitor the fall of the same objects when the air is pumped out of the tube. The fluff, having lost its former slowness, rushes along, keeping pace with the pellet and the cork. This means that its movement was delayed by air resistance, which had a lesser effect on the movement of the plug and even less on the movement of the pellet. Consequently, if it were not for air resistance, if only the forces of universal gravity acted on bodies - in a particular case, gravity - then all bodies would fall exactly the same, accelerating at the same pace.
But “there is nothing new under the sun.” Two thousand years ago, Lucretius Carus wrote in his famous poem “On the Nature of Things”:
everything that falls in rare air,
Should fall faster according to its own weight
Only because water or air is a subtle essence
I am not able to put obstacles in the way of things that are the same,
But it is more likely to yield to those with greater severity.
On the contrary, I am never capable of anything anywhere
The thing holds the emptiness and appears as some kind of support,
By nature, constantly giving in to everything.
Therefore, everything, rushing through the void without obstacles,
Have the same speed despite the difference in weight.
Of course, these wonderful words were a great guess. To turn this guess into a reliably established law, it took many experiments, starting with the famous experiments of Galileo, who studied falling from a known inclined Leaning Tower of Pisa balls of the same size, but made of various materials(marble, wood, lead, etc.), and ending with the most complex modern measurements of the influence of gravity on light. And all this variety of experimental data persistently strengthens us in the belief that gravitational forces impart equal acceleration to all bodies; in particular, the acceleration of free fall caused by gravity is the same for all bodies and does not depend on the composition, structure, or mass of the bodies themselves.
This seemingly simple law expresses perhaps the most remarkable feature of gravitational forces. There are literally no other forces that accelerate all bodies equally, regardless of their mass.
So, this property of the forces of universal gravity can be compressed into one short statement: the gravitational force is proportional to the mass of bodies. Let us emphasize that here we're talking about about the very mass that acts as a measure of inertia in Newton’s laws. It is even called inert mass.
The four words “gravitational force is proportional to mass” contain a surprisingly deep meaning. Large and small bodies, hot and cold, of all kinds chemical composition, any structure - they all experience the same gravitational interaction if their masses are equal.
Or maybe this law is really simple? After all, Galileo, for example, considered it almost self-evident. Here is his reasoning. Let two bodies of different weights fall. According to Aristotle, a heavy body should fall faster even in vacuum. Now let's connect the bodies. Then, on the one hand, the bodies should fall faster, since total weight increased. But, on the other hand, adding a part to a heavy body that falls more slowly should slow down this body. There is a contradiction that can be eliminated only if we assume that all bodies under the influence of gravity alone fall with the same acceleration. It's like everything is consistent! However, let us think again about the above reasoning. It is based on the common method of proof by contradiction: assuming that the heavier body falls faster than light, we have arrived at a contradiction. And from the very beginning there was an assumption that the acceleration of free fall is determined by weight and only weight. (Strictly speaking, not by weight, but by mass.)
But this is not at all obvious in advance (i.e., before the experiment). What if this acceleration was determined by the volume of the bodies? Or temperature? Let's imagine that there is a gravitational charge, similar to an electric charge and, like the latter, completely unrelated directly to mass. Comparison with electric charge very helpful. Here are two specks of dust between the charged plates of a capacitor. Let these dust grains have equal charges, and the masses are in the ratio 1 to 2. Then the accelerations should differ by a factor of two: the forces determined by the charges are equal, and with equal forces, a body with twice the mass accelerates half as much. If you connect dust particles, then, obviously, the acceleration will have a new, intermediate value. No speculative approach without an experimental study of electrical forces can give anything here. The picture would be exactly the same if the gravitational charge were not associated with mass. But only experience can answer the question of whether such a connection exists. And we now understand that it was the experiments that proved the identical acceleration due to gravity for all bodies that essentially showed that the gravitational charge (gravitational or heavy mass) is equal to the inertial mass.
Experience and only experience can serve both as a basis for physical laws and as a criterion for their validity. Let us at least recall the record-breaking precision experiments conducted under the leadership of V.B. Braginsky at Moscow State University. These experiments, in which an accuracy of about 10-12 was obtained, once again confirmed the equality of heavy and inert mass.
It is on experience, on the wide testing of nature - from the modest scale of a small laboratory of a scientist to the grandiose cosmic scale - that the law of universal gravitation is based, which (to summarize everything said above) says:
The force of mutual attraction of any two bodies whose dimensions are much smaller than the distance between them is proportional to the product of the masses of these bodies and inversely proportional to the square of the distance between these bodies.
The proportionality coefficient is called the gravitational constant. If we measure length in meters, time in seconds, and mass in kilograms, the gravitational force will always be equal to 6.673*10-11, and its dimension will be m3/kg*s2 or N*m2/kg2, respectively.
G=6.673*10-11 N*m2/kg2
3. Gravitational waves.
Newton's law of universal gravitation does not say anything about the time of transmission of gravitational interaction. It is implicitly assumed that it occurs instantly, no matter how large the distances between the interacting bodies are. This view is generally typical of supporters of action at a distance. But from Einstein’s “special theory of relativity” it follows that gravity is transmitted from one body to another at the same speed as the light signal. If some body moves from its place, then the curvature of space and time caused by it does not change instantly. First, this will affect the immediate vicinity of the body, then the change will affect more and more distant areas, and, finally, a new distribution of curvature will be established throughout space, corresponding to the changed position of the body.
And here we come to the problem that has caused and continues to cause the greatest number of disputes and disagreements - the problem of gravitational radiation.
Can gravity exist if there is no mass creating it? According to Newton's law, definitely not. It makes no sense to even raise such a question there. However, as soon as we agreed that gravitational signals are transmitted, although at a very high, but still not infinite speed, everything changes radically. Indeed, imagine that at first the mass causing gravity, for example a ball, was at rest. All bodies around the ball will be affected by ordinary Newtonian forces. Now let’s remove the ball from its original place with great speed. At first, the surrounding bodies will not feel this. After all, gravitational forces do not change instantly. It takes time for changes in the curvature of space to spread in all directions. This means that the surrounding bodies will experience the same influence of the ball for some time, when the ball itself is no longer there (at least, in the same place).
It turns out that the curvatures of space acquire a certain independence, that it is possible to tear a body out of the area of space where it caused the curvatures, and in such a way that these curvatures themselves, at least over large distances, will remain and develop according to their internal laws. Here is gravity without gravitating mass! We can go further. If you make the ball oscillate, then, as it turns out from Einstein’s theory, a kind of ripple is superimposed on the Newtonian picture of gravity - gravitational waves. To better imagine these waves, you need to use a model - a rubber film. If you not only press your finger on this film, but simultaneously make oscillatory movements with it, then these vibrations will begin to be transmitted along the stretched film in all directions. This is an analogue of gravitational waves. The further away from the source, the weaker such waves are.
And now at some point we will stop putting pressure on the film. The waves won't go away. They will exist independently, scattering further and further across the film, causing geometry to bend along the way.
In exactly the same way, waves of space curvature - gravitational waves - can exist independently. Many researchers draw this conclusion from Einstein’s theory.
Of course, all these effects are very weak. For example, the energy released when one match burns is many times greater than the energy of gravitational waves emitted by our entire solar system during the same time. But what is important here is not the quantitative, but the principled side of the matter.
Proponents of gravitational waves - and they seem to be in the majority now - predict another amazing phenomenon; the transformation of gravity into particles such as electrons and positrons (they must be born in pairs), protons, antitrons, etc. (Ivanenko, Wheeler, etc.).
It should look something like this. A wave of gravity reached a certain area of space. At a certain moment, this gravity sharply, abruptly, decreases and at the same time, say, an electron-positron pair appears there. The same can be described as an abrupt decrease in the curvature of space with the simultaneous birth of a pair.
There are many attempts to translate this into quantum mechanical language. Particles are introduced into consideration - gravitons, which are compared to the non-quantum image of a gravitational wave. In the physical literature, the term “transmutation of gravitons into other particles” is in circulation, and these transmutations - mutual transformations - are possible between gravitons and, in principle, any other particles. After all, there are no particles that are insensitive to gravity.
Even though such transformations are unlikely, that is, they happen extremely rarely, on a cosmic scale they can turn out to be fundamental.
4. Curvature of space-time by gravity,
"Eddington's Parable"
A parable by the English physicist Eddington from the book “Space, Time and Gravity” (retelling):
“In an ocean that has only two dimensions, there once lived a breed of flat fish. It was observed that the fish generally swam in straight lines as long as they did not encounter obvious obstacles in their path. This behavior seemed quite natural. But there was a mysterious area in the ocean; when the fish fell into it, they seemed enchanted; some sailed through this area but changed the direction of their movement, others endlessly circled around this area. One fish (almost Descartes) proposed a theory of vortices; she said that in this area there are whirlpools that make everything that gets into them spin. Over time, a much more advanced theory was proposed (Newton's theory); they said that all fish are attracted to a very large fish - the sun fish, dormant in the middle of the region - and this explained the deviation of their paths. At first this theory seemed perhaps a little strange; but it was confirmed with amazing accuracy by a wide variety of observations. All fish have been found to have this attractive property, proportionate to their size; the law of attraction (analogous to the law of universal gravitation) was extremely simple, but despite this, it explained all movements with such precision that precision had never reached before scientific research. True, some fish, grumbling, declared that they did not understand how such an action at a distance was possible; but everyone agreed that this action was carried out by the ocean, and that it would be easier to understand when the nature of water was better studied. Therefore, almost every fish that wanted to explain gravity began by suggesting some mechanism by which it spread through water.
But there was a fish who looked at things differently. She drew attention to the fact that big fish and the small ones always moved along the same paths, although it might seem that great force would be required to deflect the large fish from its path. (The sunfish imparted equal accelerations to all bodies.) Therefore, instead of trying, she began to study in detail the paths of movement of fish and thus came to an astonishing solution to the problem. There was a high place in the world where the sunfish lay. The fish could not directly notice this because they were two-dimensional; but when the fish in its movement fell on the slope of this elevation, then although it tried to swim in a straight line, it involuntarily turned a little to the side. This was the secret of the mysterious attraction or curvature of paths that occurred in the mysterious area. »
This parable shows how the curvature of the world in which we live can give the illusion of gravity, and we see that an effect like gravity is the only way such curvature can manifest itself.
Briefly this can be formulated in the following way. Since gravity bends the paths of all bodies in the same way, we can think of gravity as the curvature of space-time.
5. Gravity on Earth.
If you think about the role that gravitational forces play in the life of our planet, entire oceans open up. And not only oceans of phenomena, but also oceans in the literal sense of the word. Oceans of water. Air ocean. Without gravity they would not exist.
A wave in the sea, the movement of every drop of water in the rivers that feed this sea, all currents, all winds, clouds, the entire climate of the planet are determined by the play of two main factors: solar activity and gravity.
Gravity not only holds people, animals, water and air on Earth, but also compresses them. This compression at the Earth's surface is not so great, but its role is important.
The ship is sailing on the sea. Everyone knows what prevents him from drowning. This is the famous buoyant force of Archimedes. But it appears only because the water is compressed by gravity with a force that increases with increasing depth. Inside spaceship in flight there is no buoyancy force, just as there is no weight. The globe itself is compressed by gravitational forces to colossal pressures. At the center of the Earth, the pressure appears to exceed 3 million atmospheres.
Under the influence for a long time active forces pressure under these conditions, all substances that we are accustomed to consider solid behave like pitch or resin. Heavy materials sink to the bottom (if you can call the center of the Earth that way), and light materials float to the surface. This process has been going on for billions of years. It has not ended, as follows from Schmidt’s theory, even now. Concentration heavy elements in the region of the center of the Earth slowly increases.
Well, how does the attraction of the Sun and the closest celestial body of the Moon manifest itself on Earth? Only residents of the ocean coasts can observe this attraction without special instruments.
The sun acts in almost the same way on everything on and inside the Earth. The force with which the Sun attracts a person at noon, when he is closest to the Sun, is almost the same as the force acting on him at midnight. After all, the distance from the Earth to the Sun is ten thousand times greater than the Earth’s diameter, and an increase in the distance by one ten-thousandth when the Earth rotates half a turn around its axis practically does not change the force of gravity. Therefore, the Sun imparts almost identical accelerations to all parts globe and all bodies on its surface. Almost, but still not quite the same. Because of this difference, the ebb and flow of the ocean occurs.
On the section of the earth's surface facing the Sun, the force of gravity is somewhat greater than that necessary for the movement of this section along an elliptical orbit, and on the opposite side of the Earth it is somewhat less. As a result, according to Newton's laws of mechanics, the water in the ocean bulges slightly in the direction facing the Sun, and on the opposite side it recedes from the Earth's surface. Tidal forces, as they say, arise, stretching the globe and giving, roughly speaking, the surface of the oceans the shape of an ellipsoid.
The smaller the distances between interacting bodies, the greater the tidal forces. This is why the Moon has a greater influence on the shape of the world's oceans than the Sun. More precisely, tidal influence is determined by the ratio of the mass of a body to the cube of its distance from the Earth; this ratio for the Moon is approximately twice that for the Sun.
If there were no cohesion between the parts of the globe, then tidal forces would tear it apart.
Perhaps this happened to one of Saturn's satellites when it came close to this large planet. That fragmented ring that makes Saturn such a remarkable planet may be debris from the satellite.
So, the surface of the world's oceans is similar to an ellipsoid, the major axis of which faces the Moon. The earth rotates around its axis. Therefore, a tidal wave moves along the surface of the ocean towards the direction of rotation of the Earth. When it approaches the shore, the tide begins. In some places the water level rises to 18 meters. Then the tidal wave goes away and the tide begins to ebb. The water level in the ocean fluctuates, on average, with a period of 12 hours. 25min. (half a lunar day).
This simple picture is greatly distorted by the simultaneous tidal action of the Sun, water friction, continental resistance, the complexity of the configuration of ocean shores and bottom in coastal zones, and some other particular effects.
It is important that the tidal wave slows down the Earth's rotation.
True, the effect is very small. Over 100 years, the day increases by a thousandth of a second. But, acting for billions of years, the braking forces will lead to the fact that the Earth will be turned to the Moon all the time with one side, and the Earth’s days will become equal lunar month. This has already happened to Luna. The Moon is slowed down so much that it always faces the Earth with one side. To "look" at reverse side Moon, we had to send a spaceship around it.
Despite the fact that gravity is the weakest interaction between objects in the Universe, its significance in physics and astronomy is enormous, since it can influence physical objects at any distance in space.
If you are interested in astronomy, you have probably wondered what such a concept as gravity or the law of universal gravitation is. Gravity is the universal fundamental interaction between all objects in the Universe.
The discovery of the law of gravity is attributed to the famous English physicist Isaac Newton. Probably many of you know the story of the apple that fell on the head of the famous scientist. However, if you look deeper into history, you can see that the presence of gravity was thought about long before his era by philosophers and scientists of antiquity, for example, Epicurus. However, it was Newton who first described the gravitational interaction between physical bodies within the framework of classical mechanics. His theory was developed by another famous scientist, Albert Einstein, who in his general theory of relativity more accurately described the influence of gravity in space, as well as its role in the space-time continuum.
Newton's law of universal gravitation states that the force of gravitational attraction between two points of mass separated by a distance is inversely proportional to the square of the distance and directly proportional to both masses. The force of gravity is long-range. That is, regardless of how a body with mass moves, in classical mechanics its gravitational potential will depend purely on the position of this object at a given moment in time. The greater the mass of an object, the greater its gravitational field - the more powerful the gravitational force it has. Space objects such as galaxies, stars and planets have the greatest gravitational force and, accordingly, quite strong gravitational fields.
Gravitational fields
Earth's gravitational field
The gravitational field is the distance within which gravitational interaction occurs between objects in the Universe. The greater the mass of an object, the stronger its gravitational field - the more noticeable its impact on other physical bodies within a certain space. The gravitational field of an object is potential. The essence of the previous statement is that if you introduce the potential energy of attraction between two bodies, then it will not change after moving the latter along a closed loop. This brings up another famous law of conservation of the sum of potential and kinetic energy in a closed loop.
In the material world, the gravitational field has great importance. It is possessed by all material objects in the Universe that have mass. The gravitational field can influence not only matter, but also energy. It is due to the influence of the gravitational fields of such large cosmic objects as black holes, quasars and supermassive stars that solar systems, galaxies and other astronomical clusters are formed, which are characterized by a logical structure.
Recent scientific data show that the famous effect of the expansion of the Universe is also based on the laws of gravitational interaction. In particular, the expansion of the Universe is facilitated by powerful gravitational fields, both of its small and largest objects.
Gravitational radiation in a binary system
Gravitational radiation or gravitational wave is a term first introduced into physics and cosmology by the famous scientist Albert Einstein. Gravitational radiation in the theory of gravitation is generated by the movement of material objects with variable acceleration. During the acceleration of an object, a gravitational wave seems to “break away” from it, which leads to oscillations of the gravitational field in the surrounding space. This is called the gravitational wave effect.
Although gravitational waves are predicted by Einstein's general theory of relativity as well as other theories of gravity, they have never been directly detected. This is due primarily to their extreme smallness. However, in astronomy there is indirect evidence that can confirm this effect. Thus, the effect of a gravitational wave can be observed in the example of the convergence of double stars. Observations confirm that the rate of convergence of double stars depends to some extent on the loss of energy from these cosmic objects, which is presumably spent on gravitational radiation. Scientists will be able to reliably confirm this hypothesis in the near future using the new generation of Advanced LIGO and VIRGO telescopes.
In modern physics, there are two concepts of mechanics: classical and quantum. Quantum mechanics was developed relatively recently and is fundamentally different from classical mechanics. In quantum mechanics, objects (quanta) do not have definite positions and velocities; everything here is based on probability. That is, an object can occupy a certain place in space at a certain point in time. Where he will move next cannot be reliably determined, but only with a high degree of probability.
An interesting effect of gravity is that it can bend the space-time continuum. Einstein's theory states that in the space around a bunch of energy or any material substance, space-time is curved. Accordingly, the trajectory of particles that fall under the influence of the gravitational field of this substance changes, which makes it possible to predict the trajectory of their movement with a high degree of probability.
Theories of gravity
Today scientists know over a dozen various theories gravity. They are divided into classical and alternative theories. Most well-known representatives The first is the classical theory of gravity by Isaac Newton, which was invented by the famous British physicist back in 1666. Its essence lies in the fact that a massive body in mechanics generates a gravitational field around itself, which attracts smaller objects. In turn, the latter also have a gravitational field, like any other material objects in the Universe.
The next popular theory of gravity was invented by the world famous German scientist Albert Einstein at the beginning of the 20th century. Einstein was able to more accurately describe gravity as a phenomenon, and also explain its action not only in classical mechanics, but also in the quantum world. His general theory of relativity describes the ability of a force such as gravity to influence the space-time continuum, as well as the trajectory of movement elementary particles in space.
Among the alternative theories of gravity, the relativistic theory, which was invented by our compatriot, the famous physicist A.A., perhaps deserves the greatest attention. Logunov. Unlike Einstein, Logunov argued that gravity is not a geometric, but a real, fairly strong physical force field. Among the alternative theories of gravity, scalar, bimetric, quasilinear and others are also known.
- For people who have been in space and returned to Earth, it is quite difficult at first to get used to the strength of the gravitational influence of our planet. Sometimes this takes several weeks.
- It has been proven that the human body in a state of weightlessness can lose up to 1% of bone marrow mass per month.
- The least attractive force in solar system Among the planets, Mars has the largest, and Jupiter has the largest.
- The known salmonella bacteria, which cause intestinal diseases, behave more actively in a state of weightlessness and are capable of causing much more harm to the human body.
- Among all known astronomical objects in the Universe, black holes have the greatest gravitational force. A black hole the size of a golf ball could have the same gravitational force as our entire planet.
- The force of gravity on Earth is not the same in all corners of our planet. For example, in the Hudson Bay region of Canada it is lower than in other regions of the globe.
As a character from Soviet film classics said, “Isn’t it time, my friends, for us to take a swing at William Isaac, you know, um, our Shakespeare and Newton?”
I think it's time.
Newton is considered one of the greatest scientific minds in all of human history. It was the “Mathematical Principles of Natural Philosophy” that laid the foundation for the “scientific worldview”, which smoothly developed into militant materialism, which became the basis of the scientific paradigm for centuries.
The right to the uniqueness of truth was argued by “exact knowledge” of the phenomena of the surrounding world. The foundation of this very “indestructible, exact knowledge” was the Law of Universal Gravitation named after Isaac Newton. That’s exactly where we’ll hit the foundation! - We will show that no law of gravity actually exists in nature, and the entire edifice of modern physics is built not even on sand, but on swamp abyss.
In order to demonstrate the inconsistency of Newton's hypothesis about the mutual attraction of matter, a single exception is sufficient. We will give a few, and start with the most obvious and easily verifiable - with the movement of the Moon in its orbit. Formulas known to everyone from a high school course, and calculations available to a fifth grader. The data for the calculation can be taken even from Wikipedia, and then checked in scientific reference books.
According to the Law, the movement of celestial bodies in orbits is determined by the force of attraction between the masses of bodies and the speed of bodies relative to each other. So, let's see where the resultant forces of attraction from the Earth and the Sun are directed, acting on the Moon at the moment when the Moon flies between the Earth and the Sun (at least at the moment of a solar eclipse).
The force of attraction, as is known, is determined by the formula:
G - gravitational constant
m, M - body masses
R - distance between bodies
Let's take it from the reference books:
gravitational constant equal to approximately 6.6725 × 10 −11 m³/(kg s²).
Moon mass - 7.3477×10 22 kg
mass of the Sun - 1.9891×10 30 kg
Earth mass - 5.9737×10 24 kg
distance between Earth and Moon = 380,000,000 m
distance between the Moon and the Sun = 149,000,000,000 m
Substituting this data into the formula we get:
The force of attraction between the Earth and the Moon = 6.6725×10 - 11 x 7.3477×10 22 x 5.9737×10 24 / 380000000 2 = 2.028×10 20 H
The force of attraction between the Moon and the Sun =6.6725×10 - 11 x 7.3477 10 22 x 1.9891 10 30 / 149000000000 2 = 4.39 × 10 20 H
Thus, according to strict scientific data and calculations, the force of attraction between the Sun and the Moon, at the moment the Moon passes between the Earth and the Sun, is more than twice as strong as between the Earth and the Moon. And then the Moon should continue its path in orbit around the Sun, if the same law of universal gravitation were true. That is, the law written by Newton for the Moon is not a decree.
We also note that the Moon does not show its attractive properties in relation to the Earth: even in the time of Laplace, scientists were baffled by the behavior of sea tides, which in no way depend on the Moon.
One more fact. The Moon, moving around the Earth, would have to influence the trajectory of the latter - dragging the Earth from side to side with its gravity, as a result, the trajectory of the Earth should be zigzag, the center of mass of the Moon-Earth system should move strictly along an ellipse:
But, alas, nothing of the kind was found, although modern methods allow this displacement towards the Sun and back, at a speed of about 12 meters per second, to be reliably established. If only it really existed.
There was no decrease in the weight of bodies when immersed in ultra-deep mines.
The first attempt to test the theory of mass gravity was made on the shore Indian Ocean, where on one side there is the world’s highest rock ridge of the Himalayas, and on the other, a bowl of ocean filled with much less massive water. But, alas. the plumb line towards the Himalayas does not deviate!
Moreover, ultra-sensitive instruments - gravimeters - do not detect a difference in the gravity of a test body at the same height above mountains or seas - even if the depth is several kilometers. And then scientific world, in order to save the established theory, he came up with a support for it - they say the reason for this is “isostasy” - they say, denser rocks are located under the seas, and loose ones under the mountains, and their density is exactly such as to fit everything to the answer scientists need. It's just a song!
But if only this were the only example in the scientific world of adjusting the surrounding reality to the ideas of highbrow men about it. One can also give a blatant example of an invented “elemental particle” - the neutrino, which was invented to explain the “mass defect” in nuclear physics. Even earlier, the “latent heat of crystallization” was invented in thermal engineering.
But we digress from “universal gravity”. Another example of where the predictions of this theory cannot be detected is the lack of reliably established satellites for asteroids. There are clouds of asteroids flying across the sky, but none of them have satellites! Attempts to place artificial satellites into asteroid orbit ended in failure. The first attempt - the NEAR probe was driven to the Eros asteroid by the Americans. Wasted. The second attempt was the HAYABUSA (“Falcon”) probe, the Japanese sent it to the Itokawa asteroid, and nothing came of it either.
There are many more similar examples that can be given, but we will not overload the text with them. Let us turn to another problem of scientific knowledge: is it always possible to establish the truth in principle - at least ever.
No not always. Let us give an example based on the same “universal gravity”. As you know, the speed of light is finite, as a result we see distant objects not where they are located at the moment, but we see them at the point from which the ray of light we saw started. Many stars, perhaps not at all, only their light comes through - a hackneyed topic. But gravity - at what speed does it spread? Laplace also managed to establish that gravity from the Sun does not come from where we see it, but from another point. Having analyzed the data accumulated by that time, Laplace established that “gravity” propagates faster than light by at least seven orders of magnitude! Modern measurements have pushed the speed of gravity even further - at least 11 orders of magnitude faster than the speed of light.
There are strong suspicions that “gravity” generally spreads instantly. But if this actually takes place, then how can this be established - after all, any measurements are theoretically impossible without some kind of error. So we will never know whether this speed is finite or infinite. And the world in which it has a limit and the world in which it is unlimited are “two big differences,” and we will never know what kind of world we live in! This is the limit that is set for scientific knowledge. Accepting one point of view or another is a matter of faith, completely irrational and not amenable to any logic. How the belief in the “scientific picture of the world”, which is based on the “law of universal gravitation”, which exists only in zombie heads, and which does not appear in the world around us, defies any logic...
For now, let's leave Newton's law, and in conclusion we give the clearest example the fact that the laws discovered on Earth are not at all universal for the rest of the Universe.
Let's look at the same Moon. Preferably during the full moon. Why does the Moon look like a disk - more like a pancake than a bun, the shape of which it has.
After all, she is a ball, and a ball, if illuminated from the photographer’s side, looks something like this: in the center there is a glare, then the illumination will decrease, and the image is darker towards the edges of the disk.
The moon in the sky has uniform illumination - both in the center and at the edges, just look at the sky. You can use good binoculars or a camera with a strong optical “zoom”; an example of such a photograph is given at the beginning of the article. It was filmed at 16x zoom. This image can be processed in any graphics editor, increasing the contrast, to make sure that everything is so. Moreover, the brightness at the edges of the disk at the top and bottom is even slightly higher than in the center, where, according to theory, it should be maximum.
Here we have an example of the fact that the laws of optics on the Moon and on Earth are completely different! For some reason, the moon reflects all the falling light towards the Earth. We have no reason to extend the patterns identified in the conditions of the Earth to the entire Universe. It is not a fact that physical “constants” are actually constants and do not change over time.
All of the above shows that the “theories” of “black holes”, “Higgs bosons” and much more are not even science fiction, but simply nonsense, more than the theory that the earth rests on turtles, elephants and whales...