The law of gravitation was discovered by Newton in 1687 when studying the motion of the moon's satellite around the Earth. The English physicist has clearly formulated the postulate that characterizes the forces of gravity. In addition, analyzing Kepler's laws, Newton calculated that the forces of gravity must exist not only on our planet, but also in space.

History of the issue

The law of universal gravitation was not born spontaneously. Since ancient times, people have studied the sky, mainly for compiling agricultural calendars, calculating important dates, religious holidays. Observations indicated that in the center of the "world" there is a Luminary (the Sun), around which celestial bodies revolve in orbits. Subsequently, the dogmas of the church did not allow to think so, and people lost the knowledge accumulated over thousands of years.

In the 16th century, before the invention of telescopes, a galaxy of astronomers appeared who looked at the sky in a scientific way, discarding the prohibitions of the church. T. Brahe, observing space for many years, systematized the movements of the planets with particular care. These high-precision data helped I. Kepler subsequently to discover his three laws.

By the time of the discovery (1667) by Isaac Newton of the law of gravitation in astronomy, the heliocentric system of the world of N. Copernicus was finally established. According to her, each of the planets of the system revolves around the Luminary in orbits, which, with an approximation sufficient for many calculations, can be considered circular. At the beginning of the 17th century. I. Kepler, analyzing the work of T. Brahe, established the kinematic laws that characterize the motion of the planets. The discovery became the foundation for elucidating the dynamics of planetary motion, that is, the forces that determine precisely this type of their motion.

Description of interaction

Unlike short-period weak and strong interactions, gravity and electromagnetic fields have long-range properties: their influence manifests itself at giant distances. Mechanical phenomena in the macrocosm are influenced by 2 forces: electromagnetic and gravitational. The impact of planets on satellites, the flight of a thrown or launched object, the floating of a body in a liquid - gravitational forces act in each of these phenomena. These objects are attracted by the planet, gravitate towards it, hence the name "law of universal gravitation".

It is proven that between physical bodies the force of mutual attraction certainly acts. Such phenomena as the fall of objects on the Earth, the rotation of the Moon, planets around the Sun, occurring under the influence of the forces of universal attraction, are called gravitational.

The law of universal gravitation: formula

Universal gravitation is formulated as follows: any two material objects are attracted to each other from a certain strength... The magnitude of this force is directly proportional to the product of the masses of these objects and inversely proportional to the square of the distance between them:

In the formula, m1 and m2 are the masses of the studied material objects; r is the distance determined between the centers of mass of the calculated objects; G is a constant gravitational quantity expressing the force with which the mutual attraction of two objects weighing 1 kg each, located at a distance of 1 m, is carried out.

What determines the force of attraction

The law of gravitation works differently, depending on the region. Since the force of gravity depends on the latitude values ​​at a certain location, similarly the acceleration of gravity has different meanings v different places... The force of gravity and, accordingly, the acceleration of free fall have the maximum value at the poles of the Earth - the force of gravity at these points is equal to the force of gravity. The minimum values ​​will be at the equator.

The globe is slightly flattened, its polar radius is less than the equatorial one by about 21.5 km. However, this dependence is less significant in comparison with the daily rotation of the Earth. Calculations show that due to the flattening of the Earth at the equator, the acceleration due to gravity is slightly less than its value at the pole by 0.18%, and through the daily rotation - by 0.34%.

However, in the same place on the Earth, the angle between the direction vectors is small, so the discrepancy between the force of gravity and the force of gravity is insignificant, and it can be neglected in the calculations. That is, we can assume that the moduli of these forces are the same - the acceleration of gravity near the Earth's surface is the same everywhere and is equal to approximately 9.8 m / s².

Conclusion

Isaac Newton was a scientist who made a scientific revolution, completely rebuilt the principles of dynamics and, on their basis, created a scientific picture of the world. His discovery influenced the development of science, the creation of material and spiritual culture. The fate of Newton fell to the task of revising the results of the concept of the world. In the XVII century. Scientists have completed the grandiose work of building the foundation of a new science - physics.

DEFINITION

The law of universal gravitation was discovered by I. Newton:

Two bodies are attracted to each other with, directly proportional to their product and inversely proportional to the square of the distance between them:

Description of the law of universal gravitation

The coefficient is the gravitational constant. In the SI system, the gravitational constant matters:

This constant, as can be seen, is very small, therefore the forces of gravity between bodies with small masses are also small and practically not felt. However, the motion of cosmic bodies is completely determined by gravity. The presence of universal gravitation or, in other words, gravitational interaction explains what the Earth and the planets are "held on", and why they move around the Sun along certain trajectories, and do not fly away from it. The law of gravitation makes it possible to determine many characteristics of celestial bodies - the masses of planets, stars, galaxies and even black holes. This law makes it possible to calculate the orbits of the planets with great accuracy and create a mathematical model of the Universe.

Using the law of universal gravitation, it is also possible to calculate cosmic velocities. For example, the minimum speed at which a body moving horizontally above the surface of the Earth will not fall on it, but will move in a circular orbit - 7.9 km / s (the first cosmic speed). In order to leave the Earth, i.e. overcome its gravitational attraction, the body must have a speed of 11.2 km / s, (the second cosmic speed).

Gravity is one of the most amazing natural phenomena. In the absence of gravitational forces, the existence of the Universe would be impossible, the Universe could not even arise. Gravity is responsible for many processes in the Universe - its birth, the existence of order instead of chaos. The nature of gravity is still completely unsolved. Until now, no one has been able to develop a decent mechanism and model of gravitational interaction.

Gravity

A special case of the manifestation of gravitational forces is the force of gravity.

Gravity is always directed vertically downward (toward the center of the earth).

If gravity acts on the body, then the body commits. The type of movement depends on the direction and module of the initial speed.

We are faced with the action of gravity every day. , after a while appears on the ground. The book, released from the hands, falls down. Having jumped, a person does not fly away into open space, but sinks down to the ground.

Considering the free fall of a body near the Earth's surface as a result of the gravitational interaction of this body with the Earth, we can write:

where is the acceleration of gravity:

Free fall acceleration does not depend on body weight, but depends on the body's height above the Earth. The globe will flatten slightly at the poles, so the bodies near the poles are located a little closer to the center of the Earth. In this regard, the acceleration of gravity depends on the latitude of the terrain: at the pole it is slightly higher than at the equator and other latitudes (at the equator m / s, at the North Pole equator m / s.

The same formula allows you to find the acceleration of gravity on the surface of any planet by mass and radius.

Examples of problem solving

EXAMPLE 1 (the problem of "weighing" the Earth)

Exercise	The radius of the Earth is km, the acceleration of gravity on the surface of the planet is m / s. Using this data, estimate the approximate mass of the Earth.
Solution	Free fall acceleration near the Earth's surface: where is the mass of the earth: In the C system, the radius of the Earth is m. Substituting numerical values ​​into the formula physical quantities, let us estimate the mass of the Earth:
Answer	Earth mass kg.

EXAMPLE 2

Exercise

The Earth's satellite moves in a circular orbit at an altitude of 1000 km from the Earth's surface. How fast is the satellite moving? How long does it take for the satellite to complete one complete revolution around the Earth?

Solution

Po, the force acting on the satellite from the Earth is equal to the product of the satellite's mass by the acceleration with which it moves: From the side of the earth, a force of gravitational attraction acts on the satellite, which, according to the law of universal gravitation, is equal to: where are the masses of the satellite and the Earth, respectively. Since the satellite is at a certain height above the surface of the Earth, the distance from it to the center of the Earth is: where is the radius of the Earth.

In this paragraph, we will remind you about the force of gravity, centripetal acceleration and body weight.

Every body on the planet is affected by the gravity of the Earth. The force with which the Earth attracts each body is determined by the formula

The point of application is at the center of gravity of the body. Gravity always points straight down.

The force with which a body is attracted to the Earth under the action of the Earth's gravitational field is called by gravity. According to the law of universal gravitation on the surface of the Earth (or near this surface), a body of mass m acts on the force of gravity

F t = GMm / R 2

where M is the mass of the Earth; R is the radius of the Earth.
If only gravity acts on the body, and all other forces are mutually balanced, the body makes a free fall. According to Newton's second law and the formula F t = GMm / R 2 the free fall acceleration modulus g is found by the formula

g = F t / m = GM / R 2.

From formula (2.29) it follows that the acceleration of gravity does not depend on the mass m of the falling body, i.e. for all bodies in a given place on the Earth, it is the same. From formula (2.29) it follows that Ft = mg. In vector form

F t = mg

In § 5 it was noted that since the Earth is not a sphere, but an ellipsoid of revolution, its polar radius is less than the equatorial one. From the formula F t = GMm / R 2 it can be seen that for this reason the force of gravity and the acceleration of gravity caused by it at the pole is greater than at the equator.

The force of gravity acts on all bodies in the gravitational field of the Earth, but not all bodies fall to the Earth. This is due to the fact that the movement of many bodies is impeded by other bodies, for example, supports, suspension threads, etc. Bodies that restrict the movement of other bodies are called connections. Under the action of gravity, the bonds are deformed and the reaction force of the deformed bond according to Newton's third law balances the force of gravity.

The acceleration of gravity is influenced by the rotation of the Earth. This influence is explained as follows. Reference systems associated with the Earth's surface (except for two related to the poles of the Earth) are not, strictly speaking, inertial reference systems - the Earth rotates around its axis, and with it moves in circles with centripetal acceleration and such reference systems. This non-inertia of reference systems is manifested, in particular, in the fact that the value of the acceleration due to gravity is different in different places on the Earth and depends on the latitude of the place where the reference system connected with the Earth is located, relative to which the acceleration of gravity is determined.

Measurements carried out at different latitudes showed that numerical values the accelerations of gravity differ little from each other. Therefore, with not very accurate calculations, one can neglect the non-inertia of the reference frames associated with the Earth's surface, as well as the difference in the shape of the Earth from the spherical one, and assume that the acceleration of gravity anywhere on the Earth is the same and equal to 9.8 m / s 2.

From the law of universal gravitation it follows that the force of gravity and the acceleration of gravity caused by it decrease with increasing distance from the Earth. At a height h from the Earth's surface, the free fall acceleration modulus is determined by the formula

g = GM / (R + h) 2.

It was found that at an altitude of 300 km above the Earth's surface, the acceleration of gravity is less than at the Earth's surface by 1 m / s2.
Consequently, near the Earth (up to heights of several kilometers), the force of gravity practically does not change, and therefore the free fall of bodies near the Earth is uniformly accelerated motion.

Body weight. Weightlessness and overload

The force in which, due to attraction to the Earth, the body acts on its support or suspension is called body weight. Unlike gravity, which is the gravitational force applied to a body, weight is an elastic force applied to a support or suspension (i.e., a bond).

Observations show that the weight of the body P, determined on a spring balance, is equal to the force of gravity F t acting on the body only if the balance with the body relative to the Earth is at rest or moves uniformly and rectilinearly; In this case

P = F t = mg.

If the body is moving with acceleration, then its weight depends on the value of this acceleration and on its direction relative to the direction of the acceleration of gravity.

When the body is suspended on a spring balance, two forces act on it: the force of gravity F t = mg and the elastic force F yp of the spring. If, in this case, the body moves vertically up or down relative to the direction of the free fall acceleration, then the vector sum of the forces F t and F yn gives the resultant, causing the body to accelerate, i.e.

F t + F pack = ma.

According to the above definition of the concept of "weight", you can write that P = -F yп. From the formula: F t + F pack = ma. taking into account that F T = mg, it follows that mg-ma = -F yп ... Therefore, P = m (g-a).

Forces F t and F yn are directed along one vertical straight line. Therefore, if the acceleration of the body a is directed downward (i.e. coincides in the direction with the acceleration of gravity g), then the modulus

P = m (g-a)

If the acceleration of the body is directed upward (i.e., opposite to the direction of the acceleration of gravity), then

P = m = m (g + a).

Consequently, the weight of a body, the acceleration of which coincides in the direction with the acceleration of gravity, is less than the weight of the body at rest, and the weight of the body, the acceleration of which is opposite to the direction of the acceleration of gravity, more weight resting body. The increase in body weight caused by its accelerated movement is called overload.

In free fall, a = g. From the formula: P = m (g-a)

it follows that in this case P = 0, that is, there is no weight. Consequently, if bodies move only under the action of gravity (i.e., fall freely), they are in the state weightlessness. A characteristic feature This state is the absence of deformations and internal stresses in freely falling bodies, which are caused by gravity in bodies at rest. The reason for the weightlessness of bodies is that the force of gravity imparts equal accelerations to a freely falling body and its support (or suspension).

The force of gravity

Newton discovered the laws of motion of bodies. According to these laws, movement with acceleration is possible only under the action of force. Since the falling bodies are moving with acceleration, then a force directed downward toward the Earth must act on them. Is it only the Earth that has the ability to attract bodies located near its surface? In 1667 Newton suggested that in general, forces of mutual attraction act between all bodies. He called these forces the forces of gravity.

Why do we not notice the mutual attraction between the bodies around us? Perhaps this is due to the fact that the forces of attraction between them are too small?

Newton was able to show that the force of attraction between bodies depends on the masses of both bodies and, as it turned out, reaches a noticeable value only when the interacting bodies (or at least one of them) have a sufficiently large mass.

"HOLES" IN SPACE AND TIME

Black holes are the product of gigantic gravitational forces. They arise when, in the course of a strong compression of a larger mass of matter, its increasing gravitational field becomes so strong that it does not even release light, nothing can come out of a black hole at all. One can only fall into it under the influence of enormous gravitational forces, but there is no way out of there. Modern science revealed the connection of time with physical processes, called to "probe" the first links of the time chain in the past and trace its properties in the distant future.

The role of the masses of attracting bodies

Free fall acceleration is distinguished by the curious feature that it is the same in a given place for all bodies, for bodies of any mass. How can this strange property be explained?

The only explanation that can be found for the fact that acceleration does not depend on body mass is that the force F with which the Earth attracts a body is proportional to its mass m.

Indeed, in this case, an increase in the mass m, for example, twice will lead to an increase in the modulus of the force F also twice, and the acceleration, which is equal to the ratio F / m, will remain unchanged. Newton made this only correct conclusion: the force of universal gravity is proportional to the mass of the body on which it acts.

But after all, bodies are attracted mutually, and the forces of interaction are always of the same nature. Consequently, the force with which the body attracts the Earth is proportional to the mass of the Earth. According to Newton's third law, these forces are equal in magnitude. This means that if one of them is proportional to the mass of the Earth, then the other force equal to it is also proportional to the mass of the Earth. From this it follows that the force of mutual attraction is proportional to the masses of both interacting bodies. This means that it is proportional to the product of the masses of both bodies.

WHY IS GRAVITY IN SPACE NOT THE SAME AS ON EARTH?

Every object in the Universe affects another object, they attract each other. The force of attraction, or gravity, depends on two factors.

First, it depends on how much substance the object, body, object contains. The greater the mass of a body's substance, the stronger the gravity. If the body has a very small mass, its gravity is small. For example, the mass of the Earth is many times the mass of the Moon, so the Earth has a greater gravity than the Moon.

Secondly, the force of gravity depends on the distances between the bodies. The closer the bodies are to each other, the greater the force of attraction. The farther they are from each other, the less gravity.

Not only the most mysterious of forces of nature but also the most powerful.

Man on the path of progress

Historically, it turned out that Human as it moves forward along paths of progress seized more and more powerful forces of nature. He started when he had nothing but a stick in his fist and his own physical strength.

But he was wise, and he attracted the physical strength of animals to his service, making them domestic. The horse accelerated his run, the camel made passable the desert, the elephant made the swampy jungle. But the physical strength of even the most powerful animals is immeasurably small in front of the forces of nature.

The first man subdued the element of fire, but only in its most weakened versions. At first - for many centuries - he used only wood as a fuel - a very low-energy-consuming type of fuel. A little later this source of energy he learned to use the energy of the wind, a man raised the white wing of a sail into the air - and a light ship flew like a bird over the waves.

Sailboat on the waves

He exposed the blades to the gusts of wind windmill- and the heavy stones of the millstones were turning, the pestles of the grinders clattered. But it is clear to everyone that the energy of air jets is far from being concentrated. In addition, both the sail and the windmill were afraid of the blows of the wind: the storm tore the sails and sank ships, the storm broke its wings and overturned the mills.

Later still, man began to conquer the flowing water. The wheel is not only the most primitive of the devices capable of converting the energy of water into a rotary motion, but also the least powerful in comparison with various ones.

Man walked all the way forward on the ladder of progress and needed everything in large quantities energy.
He began to use new types of fuel - already switching to combustion coal raised the energy consumption of a kilogram of fuel from 2500 kcal to 7000 kcal - almost three times. Then came the time for oil and gas. The energy content of each kilogram of fossil fuels has again increased by one and a half to two times.

Steam engines were replaced by steam turbines; the mill wheels were replaced by hydraulic turbines. Then the man stretched out his hand to the fissioning uranium atom. However, the first use of a new type of energy had tragic consequences - the nuclear flame of Hiroshima in 1945 incinerated 70 thousand human hearts in a matter of minutes.

In 1954, the world's first Soviet nuclear power plant went into operation, transforming the power of uranium into a radiant power of electric current. And it should be noted that a kilogram of uranium contains two million times more energy than a kilogram of the best oil.

It was a fundamentally new fire that could be called physical, for it was physicists who studied the processes leading to the birth of such fabulous amounts of energy.
Uranium is not the only nuclear fuel. A more powerful type of fuel is already being used - isotopes of hydrogen.

Unfortunately, man has not yet been able to subdue the hydrogen-helium nuclear flame. He knows how to light his all-burning fire for a moment, igniting the reaction in the hydrogen bomb with the flash of a uranium explosion. But closer and closer, scientists see the hydrogen reactor, which will give birth electricity as a result of the fusion of nuclei of hydrogen isotopes into helium nuclei.

Again, the amount of energy that a person can take from each kilogram of fuel will increase almost tenfold. But will this step be the last in the coming history of the power of mankind over the forces of nature?

Not! Ahead is the mastery of the gravitational form of energy. It is even more calculatedly packed by nature than even the energy of hydrogen-helium fusion. Today it is the most concentrated form of energy that a person can even guess about.

Nothing further can be seen there, beyond the cutting edge of science. And although we can confidently say that power plants will work for humans, converting gravitational energy into electric current (or maybe into a stream of gas escaping from a jet engine nozzle, or into the planned transformation of the ubiquitous silicon and oxygen atoms into atoms of super rare metals), we cannot yet say anything about the details of such a power plant ( rocket engine, physical reactor).

The force of gravity at the origins of the birth of galaxies

The force of universal gravitation is at the origin of the birth of galaxies from prestellar matter, as Academician V.A.Ambartsumyan is convinced of. It also extinguishes the stars that have burnt out their time and have spent the stellar fuel released by them at birth.

Yes, look around: and here on Earth everything is largely controlled by this force.

It is it that determines the layered structure of our planet - the alternation of the lithosphere, hydrosphere and atmosphere. It is she who keeps a thick layer of air gases, at the bottom of which and thanks to which we all exist.

If it were not for gravity, the Earth would immediately fall from its orbit around the Sun, and the Earth's globe itself would fall apart, torn centrifugal forces... It is difficult to find anything that would not be more or less dependent on the force of gravity.

Of course, the ancient philosophers, very observant people, could not help but notice that a stone thrown upwards always comes back. Plato in the 4th century BC explained this by the fact that all the substances of the Universe tend to where most of similar substances are concentrated: a thrown stone falls to the ground or goes to the bottom, spilled water seeps into the nearest pond or into a river making its way to the sea , the smoke of the fire rushes to its kindred clouds.

A student of Plato, Aristotle, clarified that all bodies have special properties of heaviness and lightness. Heavy bodies - stones, metals - rush to the center of the Universe, light bodies - fire, smoke, vapors - to the periphery. This hypothesis, which explains some of the phenomena associated with the force of gravity, existed for more than 2 thousand years.

Scientists on the force of gravity

Probably the first to raise the question of the force of gravity really scientific, was the genius of the Renaissance - Leonardo da Vinci. Leonardo proclaimed that gravitation is inherent not only to the Earth, that there are many centers of gravity. And he also expressed the idea that the force of gravity depends on the distance to the center of gravity.

The works of Copernicus, Galileo, Kepler, Robert Hooke brought closer and closer to the idea of ​​the law of universal gravitation, but in its final formulation this law is forever associated with the name of Isaac Newton.

Isaac Newton on the force of gravity

Born on January 4, 1643. Graduated from the University of Cambridge, became a bachelor, then a master of science.

Isaac Newton

All further - an endless wealth of scientific works. But his main work is "Mathematical Principles natural philosophy", Published in 1687 and usually referred to simply as" Beginnings ". It is in them that the great is formulated. Probably everyone remembers him from high school.

All bodies are attracted to each other with a force directly proportional to the product of the masses of these bodies and inversely proportional to the square of the distance between them ...

Some of the provisions of this formulation could be anticipated by Newton's predecessors, but no one has yet fully learned it. It took the genius of Newton to collect these fragments into a single whole, in order to spread the gravity of the Earth to the Moon, and the Sun to the entire planetary system.

From the law of universal gravitation, Newton deduced all the laws of motion of the Planets, previously discovered by Kepler. They turned out to be just its consequences. Moreover, Newton showed that not only Kepler's laws, but also deviations from these laws (in the world of three or more bodies) are a consequence of universal gravitation ... This was a great triumph of science.

It seemed that the main force of nature, which drives the worlds, the force that is subject to air molecules, apples, and the Sun, was finally discovered and mathematically described. Gigantic, immeasurably huge was the step taken by Newton.

The first popularizer of the works of the brilliant scientist, French writer François Marie Arouet, world famous under the pseudonym Voltaire, said that Newton suddenly guessed the existence of the law named after him when he looked at a falling apple.

Newton himself never mentioned this apple. And it is hardly worth losing time today to refute this beautiful legend. And, apparently, Newton came to comprehend the great power of nature by means of logical reasoning. Probably, it was precisely this that entered the corresponding chapter of the Beginnings.

The force of gravity affects the flight of the nucleus

Suppose that for a very high mountain so high that its summit is already out of the atmosphere, we set up a gigantic artillery piece. Its barrel was placed strictly parallel to the surface of the globe and fired. Having described the arc, the core falls to earth.

We increase the charge, improve the quality of the powder, in one way or another we force the core to move at a higher speed after the next shot. The arc described by the nucleus becomes flatter. The core falls much further from the foot of our mountain.

We also increase the charge and shoot. The core flies along such a gentle trajectory that it descends parallel to the surface of the globe. The core can no longer fall to the Earth: with the same speed with which it descends, the Earth escapes from under it. And, having described the ring around our planet, the core returns to the point of departure.

The weapon can be removed in the meantime. After all, the flight of the nucleus around the globe will take over an hour. And then the core will swiftly sweep over the top of the mountain and set off on a new circumnavigation of the Earth. Fall, if, as we agreed, the core does not experience any air resistance, it will never be able to.

For this, the core speed should be close to 8 km / s. And if you increase the speed of the core flight? It will first fly in an arc flatter than the curvature of the earth's surface and begin to move away from the earth. At the same time, its speed will decrease under the influence of the Earth's gravity.

And, finally, having turned, it will begin, as it were, to fall back to the Earth, but it will fly past it and close not a circle, but an ellipse. The core will move around the Earth in exactly the same way as the Earth moves around the Sun, namely along an ellipse, in one of the focuses of which will be the center of our planet.

If you increase the initial velocity of the core even more, the ellipse will be more elongated. You can stretch this ellipse so that the core will fly to the lunar orbit or even much farther. But as long as the initial velocity of this core does not exceed 11.2 km / sec, it will remain a satellite of the Earth.

The nucleus, which received a speed of more than 11.2 km / s when fired, will forever fly off the Earth along a parabolic trajectory. If an ellipse is a closed curve, then a parabola is a curve that has two branches going to infinity. Moving along the ellipse, no matter how elongated it may be, we will inevitably return systematically to the starting point. Moving along a parabola, we will never return to the starting point.

But, having left the Earth at this speed, the core will not yet be able to fly away to infinity. The powerful gravity of the Sun will bend the trajectory of its flight, close around itself like the trajectory of a planet. The nucleus will become the sister of the Earth, an independent tiny planet in our family of planets.

In order to direct the core outside the planetary system, to overcome the solar attraction, it is necessary to inform it of a speed of over 16.7 km / s, and direct it so that the speed is applied to this speed own movement Earth.

A speed of about 8 km / s (this speed depends on the height of the mountain from which our cannon shoots) is called circular speed, speeds from 8 to 11.2 km / s - elliptical, from 11.2 to 16.7 km / s - parabolic , and above this number - by liberating speeds.

It should be added here that the given values ​​of these velocities are valid only for the Earth. If we lived on Mars, the circular speed would be much more easily achievable for us - it there is only about 3.6 km / s, and the parabolic speed is only slightly higher than 5 km / s.

But sending a nucleus on a space flight from Jupiter would be much more difficult than from Earth: the circular speed on this planet is 42.2 km / s, and the parabolic speed is even 61.8 km / s!

It would be most difficult for the inhabitants of the Sun to leave their world (if, of course, such could exist). The circular speed of this giant should be 437.6, and the breakaway speed - 618.8 km / s!

So Newton at the end of the 17th century, a hundred years before the first flight filled with warm air hot air balloon Brothers Montgolfier, two hundred years before the first flights of the Wright brothers' airplane and almost a quarter of a millennium before the first liquid-propellant rockets took off, showed the way to the sky for satellites and spacecraft.

The force of gravity is inherent in every sphere

Via the law of gravitation unknown planets were discovered, cosmogonic hypotheses of origin were created Solar system... Opened and mathematically described that main force of nature, which is subject to the stars, and planets, and apples in the garden, and the molecules of gases in the atmosphere.

But we do not know the mechanism of universal gravitation. Newtonian gravitation does not explain, but clearly presents state of the art the movement of the planets.

We do not know what, what causes the interaction of all the bodies of the Universe. And it cannot be said that Newton was not interested in this reason. Over the years, he pondered over its possible mechanism.

Incidentally, this is indeed an extremely mysterious force. A force that manifests itself through hundreds of millions of kilometers of space, devoid, at first glance, of any material formations with which one could explain the transfer of interaction.

Newton's hypotheses

AND Newton resorted to hypothesis about the existence of a certain ether that supposedly fills the entire Universe. In 1675, he explained the attraction to the Earth by the fact that the ether filling the entire Universe rushes to the center of the Earth in continuous streams, capturing all objects in this movement and creating the force of gravity. The same stream of ether rushes to the Sun and, dragging planets and comets along with it, provides their elliptical trajectories ...

This was not a very convincing, although absolutely mathematically logical hypothesis. But now, in 1679, Newton created a new hypothesis to explain the mechanism of gravitation. This time he endows the ether with the property of having a different concentration near the planets and far from them. The farther from the center of the planet, the supposedly denser the ether. And he has the ability to squeeze out all material bodies from their denser layers into less dense ones. And all bodies are squeezed out to the surface of the Earth.

In 1706, Newton sharply denies the very existence of the ether. In 1717 he again returned to the squeezing ether hypothesis.

Newton's genius brain struggled to solve great mystery and did not find her. This explains such a sharp throwing from side to side. Newton liked to say:

I do not build hypotheses.

And although, as we could only be convinced, this is not entirely true, we can definitely state something else: Newton was able to clearly distinguish between indisputable things from shaky and controversial hypotheses. And in the "Elements" there is a formula of the great law, but there are no attempts to explain its mechanism.
The great physicist bequeathed this riddle to the man of the future. He died in 1727.
It has not been solved even today.

The discussion about the physical essence of Newton's law took two centuries. And maybe this discussion would not touch on the very essence of the law if he answered exactly all the questions asked to him.

But the fact of the matter is that over time it turned out that this law is not universal. That there are cases when he cannot explain this or that phenomenon. Here are some examples.

The force of gravity in the calculations of Seeeliger

The first is the Seeeliger paradox. Considering the Universe to be infinite and uniformly filled with matter, Seeeliger tried to calculate, according to Newton's law, the force of universal gravitation created by the entire infinitely large mass of the infinite Universe at some point.

It was not an easy task from the point of view of pure mathematics. Having overcome all the difficulties of the most complex transformations, Seeeliger found that the sought-for force of universal gravitation is proportional to the radius of the Universe. And since this radius is equal to infinity, then the gravitational force must be infinitely large. However, in practice we do not observe this. This means that the law of universal gravitation is not applicable to the entire Universe.

However, other explanations of the paradox are also possible. For example, we can assume that matter does not uniformly fill the entire Universe, but its density gradually decreases and, finally, somewhere very far away there is no matter at all. But to present such a picture means to admit the possibility of the existence of space without matter, which is generally absurd.

We can assume that the force of universal gravitation is weakening faster than the square of the distance grows. But this casts doubt on the amazing harmony of Newton's law. No, and this explanation did not satisfy the scientists. The paradox remained a paradox.

Observing the movement of Mercury

Another fact, the actions of the force of universal gravitation, which cannot be explained by Newton's law, brought observing the movement of Mercury- closest to the planet. Accurate calculations according to Newton's law showed that perehelium - the point of the ellipse closest to the Sun, along which Mercury moves - should shift by 531 arc seconds in 100 years.

And astronomers have established that this displacement is equal to 573 arc seconds. This excess - 42 arc seconds - could not be explained by scientists either, using only formulas arising from Newton's law.

Explained both the Seeeliger paradox, the displacement of the superhelium of Mercury, and many other paradoxical phenomena and unexplained facts Albert Einstein, one of the greatest, if not the greatest physicist of all times and peoples. Among the annoying little things was the question of etheric wind.

The experiments of Albert Michelson

It seemed that this question did not directly concern the problem of gravitation. He related to optics, to light. More precisely, to determine its speed.

For the first time the speed of light was determined by a Danish astronomer Olaf Roemer observing the eclipse of Jupiter's moons. This happened back in 1675.

American physicist Albert Michelson at the end of the 18th century, he carried out a series of measurements of the speed of light in terrestrial conditions, using the devices he designed.

In 1927, he gave the value of 299796 + 4 km / s for the speed of light - this was an excellent accuracy for those times. But the crux of the matter is different. In 1880, he decided to investigate the etheric wind. He wanted to finally establish the existence of that very ether, by the presence of which they tried to explain both the transmission of gravitational interaction and the transmission of light waves.

Michelson was probably the most remarkable experimenter of his time. He had excellent equipment. And he was almost sure of success.

The essence of experience

Experience was conceived like this. The earth moves in its orbit at a speed of about 30 km / s... Moves through the ether. This means that the speed of light from a source in front of the receiver relative to the motion of the Earth must be greater than from a source on the other side. In the first case, the speed of the ether wind should be added to the speed of light; in the second case, the speed of light should decrease by this value.

Of course, the speed of the Earth's orbit around the Sun is only one ten-thousandth the speed of light. It is very difficult to find such a small term, but it is not in vain that Michelson was called the king of accuracy. He used a clever method to capture the "subtle" difference in the speed of light beams.

He split the beam into two equal streams and directed them in mutually perpendicular directions: along the meridian and along the parallel. Reflected from the mirrors, the rays returned. If the parallel beam was influenced by the ethereal wind, when it was added to the meridional beam, interference fringes should have appeared, the waves of the two beams would be out of phase.

However, it was difficult for Michelson to measure the paths of both rays with such great accuracy that they would be exactly the same. So he built the apparatus so that there were no fringes, and then turned it 90 degrees.

The meridional ray became latitudinal and vice versa. If there is ethereal wind, black and light stripes should appear under the eyepiece! But they weren't. Perhaps, when turning the apparatus, the scientist moved it.

He set it up at noon and secured it. After all, besides that, it still rotates around the axis. And so in different time day, the latitudinal ray occupies a different position relative to the oncoming etheric wind. Now, when the device is strictly motionless, one can be convinced of the accuracy of the experiment.

There were no interference fringes again. The experiment was carried out many times, and Michelson, and with him all the physicists of that time, were amazed. The ethereal wind was not found! The light moved in all directions at the same speed!

Nobody was able to explain this. Michelson repeated the experiment again and again, improved the equipment and, finally, achieved an almost incredible measurement accuracy, an order of magnitude greater than was necessary for the success of the experiment. Again, nothing!

The experiments of Albert Einstein

The next big step in knowledge of the force of gravity did Albert Einstein.
Albert Einstein was once asked:

How did you arrive at your special theory of relativity? Under what circumstances did this ingenious guess dawned on you? The scientist replied: - It always seemed to me that this is the case.

Maybe he didn't want to be frank, maybe he wanted to get rid of the annoying interlocutor. But it is difficult to imagine that the idea of ​​the connections between time, space and speed, discovered by Einstein, was innate.

No, of course, at first a guess flashed, bright as lightning. Then her development began. No, there are no contradictions with known phenomena. And then those five pages, saturated with formulas, which were published in a physics journal, appeared. Pages that ushered in a new era in physics.

Imagine a starship flying through space. We warn you right away: the starship is very peculiar, the same as you are in fantasy stories have not read it. Its length is 300 thousand kilometers, and its speed is, say, 240 thousand km / sec. And this spaceship flies past one of the intermediate platforms in space, without stopping at it. Full speed.

One of its passengers is standing on the deck of the starship with a clock. And you and I, the reader, are standing on a platform - its length must correspond to the size of the starship, that is, 300 thousand kilometers, because otherwise it will not be able to stick to it. And we also have a watch in our hands.

We notice that the moment the starship's nose came up to the rear edge of our platform, a lantern flashed on it, illuminating the space around it. A second later, the beam of light reached the front edge of our platform. We do not doubt this, for we know the speed of light, and we managed to accurately detect the corresponding moment by the clock. And on a starship ...

But the starship was flying towards the beam of light. And we definitely saw that the light illuminated its stern at the moment when it was somewhere near the middle of the platform. We definitely saw that the beam of light did not cover 300 thousand kilometers from bow to stern of the ship.

But passengers on the deck of a starship are sure of something else. They are confident that their beam covered the entire distance from bow to stern of 300 thousand kilometers. After all, he spent a whole second on it. They, too, spotted it absolutely accurately on their watch. And how could it be otherwise: after all, the speed of light does not depend on the speed of movement of the source ...

How so? We see one thing from a stationary platform, and another on the deck of a starship? What's the matter?

Einstein's theory of relativity

It should be noted right away: Einstein's theory of relativity at first glance, it absolutely contradicts our established concept of the structure of the world. We can say that it also contradicts common sense, as we are used to presenting it. This has happened more than once in the history of science.

But the discovery of the sphericity of the Earth was contrary to common sense. How can people live on the opposite side and not fall into the abyss?

For us, the sphericity of the Earth is an undeniable fact, and from the point of view of common sense, any other assumption is meaningless and wild. But look away from your time, imagine the first appearance of this idea, and it becomes clear how difficult it would be to accept it.

Well, was it easier to admit that the Earth is not stationary, but flies along its trajectory tens of times faster than a cannonball?

These were all crashes of common sense. Therefore, modern physicists never refer to it.

Now let's get back to the special theory of relativity. The world recognized her for the first time in 1905 from an article signed by few people famous name- Albert Einstein. And he was at that time only 26 years old.

Einstein made a very simple and logical assumption out of this paradox: from the point of view of an observer on the platform, less time has passed in a moving car than your Wrist Watch... In the car, the passage of time has slowed down in comparison with the time on a stationary platform.

Quite surprising things logically flowed from this assumption. It turned out that a person traveling to work in a tram, compared to a pedestrian walking the same path, not only saves time at the expense of speed, but it also goes slower for him.

However, do not try to save this way. eternal youth: Even if you become a tram driver and spend a third of your life in a tram, in 30 years you will earn hardly more than a millionth of a second. For the gain in time to become noticeable, it is necessary to move at a speed close to the speed of light.

It turns out that an increase in the speed of bodies is reflected in their mass. The closer the speed of a body is to the speed of light, the greater its mass. At the speed of a body equal to the speed of light, its mass is equal to infinity, that is, it is greater than the mass of the Earth, the Sun, the Galaxy, our entire Universe ... This is what mass can be concentrated in a simple cobblestone, accelerating it to speed
Sveta!

This also imposes a limitation that does not allow any material body to develop a speed equal to the speed of light. Indeed, as the mass grows, it becomes more and more difficult to disperse it. And an infinite mass cannot be moved by any force.

However, nature has made a very important exception to this law for a whole class of particles. For example, for photons. They can move at the speed of light. More precisely, they cannot move at any other speed. It is unthinkable to imagine a stationary photon.

When stationary, it has no mass. Neutrinos also do not have rest mass, and they are also condemned to eternal unrestrained flight through space with the maximum possible speed in our Universe, not overtaking light and not lagging behind it.

Isn't it true that each of the consequences of the special theory of relativity that we have listed is surprising, paradoxical! And each, of course, contradicts "common sense"!

But here's what is interesting: not in its concrete form, but as a broad philosophical position, all these amazing consequences were predicted by the founders of dialectical materialism. What do these consequences say? About the connections that interconnect energy and mass, mass and speed, speed and time, speed and length of a moving object ...

Einstein's discovery of interdependence, like cement (in more detail:), connecting together reinforcement, or foundation stones, brought together things and phenomena that seemed independent from each other and created the basis on which, for the first time in the history of science, it was possible to build a slender building. This building is a representation of how our universe works.

But first, at least a few words about the general theory of relativity, also created by Albert Einstein.

Albert Einstein

This name - the general theory of relativity - does not fully correspond to the content of the theory, which will be discussed. It establishes the interdependence between space and matter. Apparently, it would be more correct to call her space-time theory, or theory of gravity.

But this name has so grown together with Einstein's theory that it seems indecent for many scientists to even raise the question of replacing it now.

General relativity established the interdependence between matter and time, and the space that contains it. It turned out that space and time are not only impossible to imagine existing separately from matter, but their properties also depend on the matter filling them.

Starting point of reasoning

Therefore, one can only indicate starting point of reasoning and provide some important conclusions.

At the beginning of space travel, an unexpected catastrophe destroyed the library, film fund and other repositories of the mind, memory of people flying through space. And the nature of the native planet is forgotten in the turn of the century. Even the law of universal gravitation has been forgotten, for the rocket flies in intergalactic space, where it is almost not felt.

However, the ship's engines work great, the energy supply in the batteries is practically unlimited. Most of the time, the ship moves by inertia, and its inhabitants are accustomed to weightlessness. But sometimes they turn on the engines and slow down or speed up the movement of the ship. When the jet nozzles blaze into the void with a colorless flame and the ship moves at an accelerated rate, the inhabitants feel that their bodies are becoming heavy, they are forced to walk around the ship, and not fly along the corridors.

And now the flight is close to completion. The ship flies up to one of the stars and lays down in the orbits of the most suitable planet. The starships go outside, walking on the ground covered with fresh greenery, constantly experiencing the same sensation of heaviness, familiar from the time when the ship was moving at an accelerated pace.

But the planet moves evenly. It cannot fly towards them with a constant acceleration of 9.8 m / sec2! And they have the first assumption that the gravitational field (the force of attraction) and acceleration give the same effect, and perhaps have a common nature.

None of our contemporaries, earthlings, was on such a long flight, but many felt the phenomenon of "weight" and "relief" of their bodies. Already an ordinary elevator, when it moves at an accelerated rate, creates this feeling. On the descent, you feel a sudden loss of weight; on the ascent, on the contrary, the floor presses on your legs with more force than usual.

But one feeling doesn't prove anything. After all, sensations try to convince us that the Sun moves in the sky around the motionless Earth, that all stars and planets are at the same distance from us, on the firmament, etc.

Scientists have tested sensations. Even Newton pondered over the strange identity of the two phenomena. He tried to give them numerical characteristics. Having measured the gravitational and, he made sure that their values ​​are always strictly equal to each other.

From whatever materials he made the pendulums of the experimental installation: from silver, lead, glass, salt, wood, water, gold, sand, wheat. The result was the same.

Equivalence principle, which we are talking about, lies at the basis of the general theory of relativity, although the modern interpretation of the theory does not need this principle already. Omitting the mathematical conclusions following from this principle, let us go straight to some of the consequences of the general theory of relativity.

The presence of large masses of matter strongly affects the surrounding space. It leads to such changes in it, which can be defined as the inhomogeneity of space. These inhomogeneities direct the movement of any masses that are near the attracting body.

This analogy is usually used. Imagine a canvas stretched taut on a frame parallel to the ground. Place a heavy weight on it. This will be our great attractive mass. She, of course, will bend the canvas and find herself in a certain depression. Now roll the ball on this canvas so that part of its path lies next to the attracting mass. There are three options depending on how the ball will be launched.

1. The ball will fly far enough from the depression created by the deflection of the canvas and will not change its movement.
2. The ball will touch the depression, and the lines of its movement will bend towards the attracting mass.
3. The ball will fall into this hole, will not be able to get out of it and will make one or two revolutions around the gravitating mass.

Isn't it true that the third option very nicely simulates the capture by a star or planet of a foreign body inadvertently flying into their field of attraction?

And the second case is the bending of the trajectory of a body flying at a speed greater than the possible capture speed! The first case is analogous to flying out of the practical reach of the gravitational field. Yes, it is practical, because theoretically the gravitational field is unlimited.

Of course, this is a very distant analogy, primarily because no one can really imagine the deflection of our three-dimensional space... What is the physical meaning of this deflection, or curvature, as they often say, no one knows.

From the general theory of relativity it follows that any material body can move in a gravitational field only along curved lines. Only in particular, special cases, the curve turns into a straight line.

The ray of light also obeys this rule. After all, it consists of photons that have a certain mass in flight. And the gravitational field acts on it, as well as on a molecule, asteroid or planet.

Another important conclusion is that the gravitational field also changes the course of time. Near a large attracting mass, in a strong gravitational field created by it, the course of time should be slower than far from it.

You see, and the general theory of relativity is fraught with paradoxical conclusions that can turn our ideas of "common sense" over and over again!

Gravitational collapse

Let's talk about an amazing cosmic phenomenon - about gravitational collapse (catastrophic compression). This phenomenon occurs in gigantic accumulations of matter, where the forces of gravity reach such enormous magnitudes that no other forces existing in nature can resist them.

Remember Newton's famous formula: the gravitational forces are the greater, the less square distance between gravitating bodies. Thus, the denser the material formation becomes, the smaller its size, the more rapidly the forces of gravity increase, the more inevitable is their destructive embrace.

There is a clever trick with the help of which nature fights against the seemingly limitless contraction of matter. To do this, it stops the very course of time in the sphere of action of supergiant gravitational forces, and the chained masses of matter seem to be turned off from our Universe, freeze in a strange lethargic dream.

The first of these "black holes" in space has probably already been discovered. According to the assumption of Soviet scientists O. Kh. Guseinov and A. Sh. Novruzova, it is the Gemini delta - a double star with one invisible component.

The visible component has a mass of 1.8 solar, and its invisible "partner" should be, according to calculations, four times more massive than the visible one. But there is no trace of it: to see amazing creation nature, "black hole" is impossible.

The Soviet scientist Professor KP Stanyukovich, as they say, "at the tip of the pen", through purely theoretical constructions, showed that the particles of "frozen matter" can be very diverse in size.

• Its gigantic formations are possible, similar to quasars, continuously emitting the same amount of energy as all 100 billion stars of our Galaxy emit.
• Much more modest clumps are possible, equal to only a few solar masses. Both those and other objects can arise themselves from ordinary, not "sleeping" matter.
• And formations of a completely different class are possible, commensurate in mass with elementary particles.

For them to arise, it is necessary to first subject the constituent matter to gigantic pressure and drive it into the Schwarzschild sphere - a sphere where time for an external observer stops completely. And if after that the pressure is even removed, the particles for which time has stopped will remain to exist independently of our Universe.

Plankeons

Plankeons are a very special class of particles. They have, according to K.P. Stanyukovich, an extremely interesting property: they carry matter in themselves unchanged, such as it was millions and billions of years ago. Looking inside the plankeon, we could see matter as it was at the time of the birth of our universe. According to theoretical calculations, there are about 10 80 plankeons in the universe, approximately one plankeon in a cube of space with a side of 10 centimeters. By the way, simultaneously with Stanyukovich and (independently of him, the hypothesis of the plankeons was put forward by academician M. A. Markov. Only Markov gave them a different name - maximons.

One can try to explain the sometimes paradoxical transformations of elementary particles by the special properties of the plankeons. It is known that when two particles collide, fragments are never formed, but other elementary particles appear. This is truly amazing: in the ordinary world, breaking a vase, we never get whole cups or even rosettes. But suppose that in the depths of each elementary particle a plankeon is hidden, one or several, and sometimes many plankeons.

At the moment of collision of particles, the tightly tied "bag" of the Plankeon opens slightly, some particles will "fall" into it, and instead those that we consider to have arisen during the collision "pop out". At the same time, the Plankeon, as a prudent accountant, will provide all the "conservation laws" adopted in the world of elementary particles.
Well, what does the mechanism of universal gravitation have to do with it?

"Responsible" for gravitation, according to the hypothesis of KP Stanyukovich, are tiny particles, the so-called gravitons, continuously emitted by elementary particles. Gravitons are as much smaller than the latter, as much as a speck of dust dancing in sunbeam, smaller than the globe.

The emission of gravitons obeys a number of laws. In particular, they are easier to fly into that area of ​​space. Which contains fewer gravitons. This means that if there are two celestial bodies in space, both will radiate gravitons mainly "outward", in directions opposite to each other. Thus, an impulse is created that makes the bodies come closer, to be attracted to each other.