The laws of gravity do not work. Force of gravity. The gravitational field of the Earth. What modern scientists think about gravity

Gravity is the most mysterious force in the universe. Scientists do not fully know its nature. It is she who keeps the planets of the solar system in orbits. It is a force that occurs between two objects and depends on mass and distance.

Gravity is called the force of attraction or gravity. With the help of it, a planet or other body pulls objects to its center. Gravity keeps the planets in orbit around the sun.

What else does gravity do?

Why do you land on earth when you jump up and not float away into space? Why do items fall when you drop them? The answer is the invisible force of gravity that pulls objects towards each other. Earth's gravity is what keeps you on the ground and makes things fall.

Anything that has mass has gravity. The power of gravity depends on two factors: the mass of objects and the distance between them. If you take a stone and a feather in your hands, release them from the same height, both objects will fall to the ground. A heavy stone will fall faster than a feather. The feather will still hang in the air because it is lighter. Objects with a higher mass have a greater force of attraction, which becomes weaker with distance: the closer objects are to each other, the stronger their gravitational pull.

Gravity on Earth and in the Universe

During the flight of the aircraft, people in it remain in place and can move as on the ground. This is due to the flight path. There are specially designed airplanes, in which there is no gravity at a certain height, weightlessness is formed. The plane performs a special maneuver, the mass of objects changes, they briefly rise into the air. After a few seconds, the gravitational field is restored.

Considering the force of gravity in Space, the earth's force is greater than most of the planets. It is enough to look at the movement of astronauts when landing on planets. If we walk on the ground calmly, then there the astronauts seem to soar in the air, but do not fly into space. This means that this planet also has a gravitational force, just slightly different than that of the planet Earth.

The sun's gravity is so great that it holds nine planets, numerous satellites, asteroids, and planets.

Gravity plays a critical role in the development of the universe. In the absence of gravity, there would be no stars, planets, asteroids, black holes, galaxies. Interestingly, black holes are not actually visible. Scientists determine the signs of a black hole by the strength of the gravitational field in a particular area. If it is very strong with strong vibration, this suggests the existence of a black hole.

Myth 1. There is no gravity in space

Watching documentaries about astronauts, it seems that they are hovering above the surface of the planets. This is due to the fact that on other planets gravity is lower than on Earth, so the astronauts go as if floating in the air.

Myth 2. All bodies approaching a black hole are torn apart

Black holes are powerful and generate powerful gravitational fields. The closer the object is to the black hole, the stronger the tidal forces and the power of attraction become. The further development of events depends on the mass of the object, the size of the black hole and the distance between them. A black hole has the opposite mass of its size. Interestingly, the larger the hole, the weaker the tidal forces and vice versa. Thus, not all objects are torn apart when hitting the field of a black hole.

Myth 3. Artificial satellites can orbit the Earth forever

Theoretically, you can say so, if not for the influence of secondary factors. Much depends on the orbit. In a low orbit, the satellite will not be able to fly forever due to atmospheric deceleration, in high orbits it can remain in an unchanged state for quite a long time, but here the gravitational forces of other objects come into play.

If of all the planets only the Earth existed, the satellite would be attracted to it and practically did not change its trajectory. But in high orbits, the object is surrounded by many planets, large and small, each with its own gravitational force.

In this case, the satellite would gradually move away from its orbit and move chaotically. And, it is likely that after some time, it would have crashed to the nearest surface or moved to another orbit.

Some facts

1. In some parts of the Earth, the force of gravity is weaker than on the entire planet. For example, in Canada, in the Hudson Bay area, the force of gravity is lower.
2. When astronauts return from space to our planet, at the very beginning it is difficult for them to adapt to the gravitational force of the globe. Sometimes it takes several months.
3. The most powerful force of gravity among space objects is possessed by black holes. One black hole the size of a ball is more powerful than any planet.

Despite the ongoing study of the force of gravity, gravity remains undisclosed. This means that scientific knowledge remains limited and humanity has to learn a lot of new things.

The science

Here on Earth, we take gravity for granted. However, the force of gravity by which objects pull towards each other in proportion to their mass is much more than a falling apple on Newton's head. Below are the strangest facts about this universal power.

It's all in our head

The force of attraction is a constant and consistent phenomenon, but our perception of this force is not. According to a study published in April 2011 in the journal PLoS ONE, humans are able to make more accurate judgments about falling objects when they are seated.

The researchers concluded that our perception of gravity is less based on the actual visual direction of force and more on the "orientation" of the body.

The findings could lead to a new strategy to help astronauts cope with microgravity in space.

Hard descent to the ground

The experience of astronauts has shown that the transition from a state of weightlessness and back can be very difficult for the human body. In the absence of gravity, muscles begin to atrophy, and bones also begin to lose bone mass. According to NASA, astronauts can lose up to 1 percent of their bone mass per month.

Upon returning to earth, the organisms and minds of astronauts need a period of time to recover. The blood pressure, which becomes the same throughout the body in space, should return to normal functioning, in which the heart works well and the brain receives a sufficient amount of food.

Sometimes the restructuring of the body affects astronauts extremely hard, both physically (repeated fainting, etc.) and emotionally. For example, one astronaut told how, upon returning from space, he broke a bottle of aftershave at home, because he forgot that when he released it into the air, it would fall and break, rather than float in it.

To Lose Weight Try Pluto

In this dwarf planet, a person weighing 68 kilograms will weigh no more than 4.5 kg.

That being said, on the other hand, on the planet with the highest level of gravity, Jupiter, the same person would weigh about 160.5 kg.

A person will probably also feel like a feather on Mars, since the force of gravity on this planet is only 38 percent of that on earth, that is, a 68-kilogram person will feel how light his gait is, since he will weigh only 26 kg.

Different gravity

Even on earth, gravity is not the same everywhere. Due to the fact that the shape of the globe is not an ideal sphere, its mass is distributed unevenly. Therefore, uneven mass means uneven gravity.

One mysterious gravity anomaly is observed in Hudson Bay in Canada. In this region, the force of gravity is lower than in others, and a 2007 study revealed the cause is melting glaciers.

The ice that once covered this area during the last ice age has melted long ago, but the Earth has not completely rid itself of this burden. Since the gravity of the region is proportional to the mass of this region, and the "ice trail" has pushed some of the earth's mass aside, gravity has become weaker here. Minor crustal deformation explains 25-45 percent of the unusually low gravitational force, among other things, it is also "blamed" for the movement of magma in the Earth's mantle.

Without gravity, some viruses would be stronger

Bad news for space cadets: some bacteria are becoming intolerable in space.

In the absence of gravity, bacteria change at least the activity of 167 genes and 73 proteins.

Mice that ate food with these salmonella sickened much faster.

In other words, the danger of contamination does not necessarily come from space; it is more likely that our own bacteria are gathering strength to attack.

Black holes in the center of the galaxy

Named this way because nothing, not even light, can escape their attraction, black holes are some of the most destructive objects in the universe. At the center of our galaxy lies a massive black hole weighing 3 million suns. Sounds intimidating, right? However, according to experts from Kyoto University, this black hole is currently "just resting."

In fact, the black hole is not dangerous for us, earthlings, because it is very far away and behaves extremely calmly. However, in 2008 it was reported that about 300 years ago, this hole was sending out bursts of energy. Another study published in 2007 found that a few thousand years ago, "galactic hiccups" sent a small amount of matter, the size of Mercury, into this very hole, causing a powerful explosion.

This black hole, called Sagittarius A *, has a relatively blurry shape compared to other black holes. "This weakness means that stars and gas rarely approach the black hole at an unsafe distance," says Frederick Baganoff, a research associate at MIT. "Great appetite is present, but not satisfied."

Every person in his life has come across this concept more than once, because gravity is the basis not only of modern physics, but also of a number of other related sciences.

Many scientists have been studying the attraction of bodies since ancient times, but the main discovery is attributed to Newton and is described as the well-known story with a fruit falling on its head.

What is gravity in simple words

Gravity is the attraction between several things in the entire universe. The nature of the phenomenon is different, since it is determined by the mass of each of them and the length between, that is, the distance.

Newton's theory was based on the fact that the same force acts on the falling fruit and on the satellite of our planet - attraction to the Earth. And the satellite did not fall on the earth's space precisely because of its mass and remoteness.

Gravitational field

The gravitational field is a space within which the interaction of bodies occurs according to the laws of attraction.

Einstein's theory of relativity describes the field as a certain property of time and space, which characteristically manifests itself when physical objects appear.

Gravity wave

This is a certain kind of changes in the fields that are formed as a result of radiation from moving objects. They detach from the subject and spread in a ripple effect.

Theories of gravity

The classical theory is Newtonian. However, it was imperfect and later there were alternative options.

These include:

• metric theories;
• non-metric;
• vector;
• Le Sage, who first described the phases;
• quantum gravity.

Today there are several dozen different theories, all of them either complement each other, or consider the phenomena from the other side.

Its useful to note: There is no perfect answer yet, but constant development is opening up more options for the attraction of bodies.

Gravitational pull

The basic calculation is as follows - the force of gravity is proportional to the multiplication of body mass by another, between which it is determined. This formula is also expressed like this: the force is inversely proportional to the distance between the objects squared.

The gravitational field is potential, which means that kinetic energy is conserved. This fact simplifies the solution of problems in which the force of attraction is measured.

Gravity in space

Despite the misconception of many, there is gravity in space. It is lower than on Earth, but still present.

As for the astronauts, who at first glance fly, they are in reality in a state of slow decline. Visually, they don't seem to be attracted to anything, but in practice they experience gravity.

The force of attraction depends on the distance, but no matter how large the distance between objects, they will continue to reach for each other. Mutual attraction will never be equal to zero.

Gravity in the solar system

In the solar system, not only the Earth has gravity. The planets, as well as the Sun, attract objects to themselves.

Since the force is determined by the mass of the object, the Sun has the greatest indicator. For example, if our planet has an indicator of one, then the figure of a luminary will be almost equal to twenty-eight.

The next, after the Sun, in gravity is Jupiter, so its gravity is three times higher than that of the Earth. Pluto has the smallest parameter.

For clarity, let's designate it as follows: in theory, on the Sun, an average person would weigh about two tons, but on the smallest planet of our system - only four kilograms.

What determines the gravity of the planet

Gravitational thrust, as mentioned above, is the power with which the planet pulls objects located on its surface to itself.

The force of attraction depends on the gravity of the object, the planet itself and the distance between them. If there are many kilometers, gravity is low, but it still keeps objects in touch.

Several important and fascinating aspects of gravity and its properties that are worth explaining to your child:

1. The phenomenon attracts everything, but never repels - this distinguishes it from other physical phenomena.
2. There is no zero indicator. It is impossible to simulate a situation in which pressure does not act, that is, gravity does not work.
3. The earth falls from average speed 11.2 kilometers per second, reaching this speed, you can leave the planet's attraction well.
4. The fact of existence gravitational waves has not been scientifically proven, it is just a guess. If ever they become visible, then humanity will discover many of the mysteries of space associated with the interaction of bodies.

According to the theory of basic relativity of a scientist like Einstein, gravity is a curvature of the basic parameters of the existence of the material world, which is the basis of the universe.

Gravity is the mutual attraction of two objects. The force of interaction depends on the gravity of the bodies and the distance between them. So far, not all the secrets of the phenomenon have been revealed, but today there are several dozen theories describing the concept and its properties.

The complexity of the objects being studied affects the research time. In most cases, the dependence of mass and distance is simply taken.

Gravity is the most powerful force in the Universe, one of the four fundamental foundations of the universe, which determines its structure. Once, thanks to her, planets, stars and whole galaxies arose. Today it keeps the Earth in orbit on its endless journey around the Sun.

Attraction is also of great importance for a person's daily life. Thanks to this invisible force, the oceans of our world pulsate, rivers flow, raindrops fall to the ground. Since childhood, we feel the weight of our body and surrounding objects. The influence of gravity on our economic activities is also enormous.

The first theory of gravity was created by Isaac Newton at the end of the 17th century. His Law of Universal Gravitation describes this interaction within the framework of classical mechanics. This phenomenon was expounded more broadly by Einstein in his general theory relativity, which saw the light at the beginning of the last century. The processes occurring with the force of gravity at the level of elementary particles should be explained by the quantum theory of gravity, but it has yet to be created.

We know much more about the nature of gravity today than we did in Newton's day, but despite centuries of study, it still remains a real stumbling block in modern physics. There are many blank spots in the existing theory of gravity, and we still do not understand exactly what gives rise to it, and how the transfer of this interaction occurs. And, of course, we are very far from being able to control the force of gravity, so that antigravity or levitation will exist for a long time only on the pages of science fiction novels.

What fell on Newton's head?

At all times, people have thought about the nature of the force that attracts objects to the earth, but it was only in the 17th century that Isaac Newton managed to open the veil of secrecy. The basis for its breakthrough was laid by the works of Kepler and Galileo, brilliant scientists who studied the movements of celestial bodies.

Another century and a half before Newton's Law of Universal Gravity, the Polish astronomer Copernicus believed that attraction is "... nothing more than a natural tendency, which the father of the Universe bestowed on all particles, namely, to combine into one common whole, forming spherical bodies." Descartes, on the other hand, considered attraction to be a consequence of disturbances in the world ether. The Greek philosopher and scientist Aristotle was convinced that mass affects the speed of falling bodies. And only Galileo Galilei at the end of the 16th century proved that this is not true: if there is no air resistance, all objects are accelerated in the same way.

Contrary to popular legend about the head and the apple, Newton has been on the path to understanding the nature of gravity for over twenty years. His law of gravity is one of the most significant scientific discoveries of all times and peoples. It is universal and allows you to calculate the trajectories of celestial bodies and accurately describes the behavior of objects around us. The classical theory of gravitation laid the foundations for celestial mechanics. Newton's three laws gave scientists the opportunity to discover new planets literally "at the tip of a pen", in the end, thanks to them, a person was able to overcome Earth's gravity and fly into space. They provided a strict scientific basis for the philosophical concept of the material unity of the universe, in which all natural phenomena are interconnected and governed by general physical rules.

Newton not only published a formula that allows you to calculate the force that attracts bodies to each other, he created a holistic model, which also included mathematical analysis. These theoretical conclusions have been repeatedly confirmed in practice, including using the most modern methods.

In Newtonian theory, any material object generates an attraction field, which is called gravitational. Moreover, the force is proportional to the mass of both bodies and is inversely proportional to the distance between them:

F = (G m1 m2) / r2

G is the gravitational constant, which equals 6.67 × 10−11 m³ / (kg · s²). Henry Cavendish was the first to calculate it in 1798.

In everyday life and in applied disciplines, the force with which the earth attracts a body is referred to as its weight. The attraction between any two material objects in the Universe is what gravity is. in simple words.

The force of gravity is the weakest of the four fundamental interactions of physics, but due to its peculiarities, it is able to regulate the movement of stellar systems and galaxies:

• Attraction works at any distance, this is the main difference between gravity and strong and weak nuclear interactions. With increasing distance, its effect decreases, but it never becomes equal to zero, so we can say that even two atoms located at different ends of the galaxy exert mutual influence. It's just very small;
• Gravity is universal. The field of attraction is inherent in any material body. Scientists have not yet discovered an object on our planet or in space that would not participate in this type of interaction, so the role of gravity in the life of the Universe is enormous. In this, gravitation differs from electromagnetic interaction, the influence of which on cosmic processes is minimal, since in nature most bodies are electrically neutral. Gravitational forces cannot be limited or shielded;
• Gravity acts not only on matter, but also on energy. For him, the chemical composition of objects does not matter, only their mass plays a role.

Using Newton's formula, the force of gravity can be easily calculated. For example, the gravity on the Moon is several times less than that of the Earth, because our satellite has a relatively small mass. But it is enough for the formation of regular ebbs and flows in the oceans. On Earth, the acceleration due to gravity is approximately 9.81 m / s2. Moreover, at the poles it is somewhat larger than at the equator.

Despite the enormous importance for the further development of science, Newtonian laws had a number of weak points that haunted researchers. It was not clear how gravity acts through absolutely empty space over huge distances, and with an incomprehensible speed. In addition, data gradually began to accumulate that contradicted Newton's laws: for example, the gravitational paradox or the displacement of the perihelion of Mercury. It became obvious that the theory of universal gravitation needs to be improved. This honor fell to the genius German physicist Albert Einstein.

Attraction and the theory of relativity

Newton's refusal to discuss the nature of gravity ("I am not inventing hypotheses") was an obvious weakness of his concept. Unsurprisingly, in the years that followed, many theories of gravity emerged.

Most of them belonged to the so-called hydrodynamic models, which tried to substantiate the occurrence of gravitation by the mechanical interaction of material objects with some intermediate substance that has certain properties. Researchers called it differently: "vacuum", "ether", "flow of gravitons", etc. In this case, the force of attraction between bodies arose as a result of changes in this substance, when it was absorbed by objects or screened flows. In reality, all such theories had one serious drawback: while predicting quite accurately the dependence of the gravitational force on the distance, they should have led to the deceleration of bodies that were moving relative to the "ether" or "flow of gravitons".

Einstein approached this issue from a different angle. In his general theory of relativity (GR), gravity is considered not as the interaction of forces, but as a property of space-time itself. Any object with mass leads to its curvature, which causes attraction. In this case, gravity is a geometric effect that is considered within the framework of non-Euclidean geometry.

Simply put, the space-time continuum acts on matter, conditioning its movement. And that, in turn, affects the space, "showing" him how to bend.

The forces of attraction act in the microcosm as well, but at the level of elementary particles, their influence, in comparison with electrostatic interaction, is negligible. Physicists believe that the gravitational interaction was not inferior to the rest in the first moments (10 -43 seconds) after the Big Bang.

Currently, the concept of gravity, proposed in the general theory of relativity, is the main working hypothesis, accepted by the majority of the scientific community and confirmed by the results of numerous experiments.

Einstein foresaw amazing effects of gravitational forces in his work, most of which have already been confirmed. For example, the ability of massive bodies to bend light rays and even slow down the passage of time. The latter phenomenon must be taken into account in the operation of global satellite navigation systems, such as GLONASS and GPS, otherwise, in a few days, their error would be tens of kilometers.

In addition, the consequence of Einstein's theory are the so-called subtle effects of gravity, such as the gravimagnetic field and the dragging of inertial reference frames (aka the Lense-Thirring effect). These manifestations of the force of gravity are so weak that they could not be detected for a long time. Only in 2005, thanks to the unique NASA Gravity Probe B mission, the Lense-Thirring effect was confirmed.

Gravitational radiation or the most fundamental discovery of recent years

Gravitational waves are vibrations of a geometric space-time structure that propagate at the speed of light. The existence of this phenomenon was also predicted by Einstein in general relativity, but due to the weakness of the gravitational force, its magnitude is very small, therefore, it could not be detected for a long time. Only indirect evidence spoke in favor of the existence of radiation.

Such waves generate any material objects moving with asymmetric acceleration. Scientists describe them as "ripples of space-time." The most powerful sources of such radiation are colliding galaxies and collapsing systems consisting of two objects. A typical example of the latter is the merging of black holes or neutron stars. In such processes, gravitational radiation can transfer more than 50% of the total mass of the system.

Gravitational waves were first detected in 2015 by two LIGO observatories. Almost immediately, this event received the status of the largest discovery in physics in recent decades. In 2017, he was awarded Nobel Prize... After that, scientists managed to record gravitational radiation several times.

Back in the 70s of the last century - long before experimental confirmation- Scientists suggested using gravitational radiation for long-distance communication. Its undoubted advantage is its high ability to pass through any substance without being absorbed. But at present this is hardly possible, because there are enormous difficulties in generating and receiving these waves. And we don't have enough real knowledge about the nature of gravity.

Today, in different countries of the world, several installations similar to LIGO are operating and new ones are being built. It is likely that we will learn more about gravitational radiation in the near future.

Alternative theories of universal gravitation and the reasons for their creation

At the moment, the dominant concept of gravity is general relativity. The entire existing array of experimental data and observations is consistent with it. At the same time, it has a large number of openly weak points and controversial points, so attempts to create new models that explain the nature of gravity do not stop.

All the theories of universal gravitation developed to date can be divided into several main groups:

• standard;
• alternative;
• quantum;
• unified field theory.

Attempts to create a new concept of universal gravitation were made back in the 19th century. Various authors included ether or corpuscular theory of light in it. But the appearance of general relativity put an end to these studies. After its publication, the goal of scientists changed - now their efforts were aimed at improving Einstein's model, including new natural phenomena in it: the spin of particles, the expansion of the Universe, etc.

By the early 80s, physicists experimentally rejected all concepts, with the exception of those that included general relativity as an integral part. At this time, "string theories" came into vogue, which looked very promising. But these hypotheses have not been found experimentally. Over the past decades, science has reached significant heights and has accumulated a huge array of empirical data. Today, attempts to create alternative theories of gravity are inspired mainly by cosmological research related to concepts such as “ dark matter"," Inflation "," dark energy ".

One of the main tasks of modern physics is to combine two fundamental directions: quantum theory and general relativity. Scientists seek to link attraction with other types of interactions, thus creating a "theory of everything." This is exactly what quantum gravity does - a branch of physics that tries to give a quantum description of gravitational interaction. An offshoot of this direction is the theory of loop gravity.

Despite active and long-term efforts, this goal has not yet been achieved. And it’s not even a matter of the complexity of this problem: it’s just that the quantum theory and general relativity are based on completely different paradigms. Quantum mechanics works with physical systems operating against the background of ordinary space-time. And in the theory of relativity, space-time itself is a dynamic component that depends on the parameters of the classical systems in it.

Along with scientific hypotheses of universal gravitation, there are also theories that are very far from modern physics. Unfortunately in last years such "opuses" simply flooded the Internet and the shelves of bookstores. Some authors of such works generally inform the reader that gravity does not exist, and the laws of Newton and Einstein are inventions and hoaxes.

An example is the works of the "scientist" Nikolai Levashov, who assert that Newton did not discover the law of universal gravitation, but gravitational force only planets and our satellite Moon have in the solar system. This "Russian scientist" gives rather strange proofs. One of them is the flight of the American probe NEAR Shoemaker to the asteroid Eros, which took place in 2000. The lack of attraction between the probe and the celestial body Levashov considers proof of the falsity of Newton's works and the conspiracy of physicists who hide from people the truth about gravity.

Actually spacecraft successfully completed its mission: first it entered the orbit of the asteroid, and then made a soft landing on its surface.

Artificial gravity and what it is for

There are two concepts associated with gravity that, despite their current theoretical status, are well known to the general public. This is anti-gravity and artificial gravity.

Antigravity is the process of counteracting the force of gravity, which can significantly reduce it or even replace it with repulsion. Mastering such technology would lead to a real revolution in transport, aviation, space exploration and radically change our whole life. But at present, the possibility of antigravity does not even have a theoretical confirmation. Moreover, based on general relativity, such a phenomenon is not at all realizable, since there can be no negative mass in our Universe. It is possible that in the future we will learn more about attraction and learn how to build aircraft based on this principle.

Artificial gravity is a man-made modification of the existing gravity. Today we do not need such technology too much, but the situation will definitely change after the start of long-term space travel. And it's about our physiology. The human body, "accustomed" by millions of years of evolution to the constant gravity of the Earth, extremely negatively perceives the effect of reduced gravity. Long stay even in conditions of lunar gravity (six times weaker than Earth's) can lead to sad consequences. The illusion of attraction can be created using other physical forces, such as inertia. However, these options are complex and expensive. At the moment, artificial gravity does not even have a theoretical basis, it is obvious that its possible practical implementation is a matter of a very distant future.

Gravity is a concept that everyone has known since school. It would seem that scientists should have thoroughly investigated this phenomenon! But gravity remains the deepest secret for modern science... And this can be called an excellent example of how limited a person's knowledge about our huge and wonderful world is.

If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.

Since ancient times, mankind has thought about how the world... Why the grass grows, why the sun is shining, why we cannot fly ... The latter, by the way, has always been of particular interest to people. We now know that gravity is the cause of everything. What it is, and why this phenomenon is so important on the scale of the Universe, we will consider today.

Introductory part

Scientists have found that all massive bodies experience mutual attraction to each other. Subsequently, it turned out that this mysterious force determines the movement of celestial bodies along their constant orbits. The very same theory of gravity was formulated by a genius whose hypotheses predetermined the development of physics for many centuries to come. This teaching was developed and continued (albeit in a completely different direction) by Albert Einstein - one of the greatest minds of the past century.

For centuries, scientists have observed gravity, tried to understand and measure it. Finally, in the past few decades, even such a phenomenon as gravity has been put at the service of humanity (in a sense, of course). What is it, what is the definition of the term in question in modern science?

Scientific definition

If you study the works of ancient thinkers, you can find out that the Latin word "gravitas" means "heaviness", "attraction". Today, scientists call this the universal and constant interaction between material bodies. If this force is relatively weak and acts only on objects that move much slower, then Newton's theory is applicable to them. If the opposite is the case, one should use Einstein's conclusions.

Let's make a reservation right away: at present, the very nature of gravity has not been fully studied in principle. What it is, we still do not fully understand.

Theories of Newton and Einstein

According to the classical teachings of Isaac Newton, all bodies are attracted to each other with a force directly proportional to their mass, inversely proportional to the square of the distance that lies between them. Einstein, on the other hand, argued that gravitation between objects manifests itself in the case of curvature of space and time (and the curvature of space is possible only if there is matter in it).

This idea was very deep, but modern research proves its some inaccuracy. Today it is believed that gravity in space bends only space: time can be slowed down and even stopped, but the reality of the change in the form of temporary matter has not been theoretically confirmed. Therefore, the classical equation of Einstein does not even provide for a chance that space will continue to influence matter and the resulting magnetic field.

To a greater extent, the law of gravity (universal gravitation) is known, the mathematical expression of which belongs to Newton:

\ [F = γ \ frac [-1.2] (m_1 m_2) (r ^ 2) \]

Γ is understood as the gravitational constant (sometimes the symbol G is used), the value of which is 6.67545 × 10−11 m³ / (kg · s²).

Interaction between elementary particles

The incredible complexity of the space around us is largely due to the infinite number of elementary particles. There are also various interactions between them at levels that we can only speculate about. However, all types of interaction of elementary particles with each other differ significantly in their strength.

The most powerful forces known to us bind together the components of the atomic nucleus. To separate them, you need to spend a truly colossal amount of energy. As for the electrons, they are "attached" to the nucleus only by ordinary ones. To stop it, sometimes the energy that appears as a result of the most ordinary chemical reaction is enough. Gravity (what it is, you already know) in the variant of atoms and subatomic particles is the easiest type of interaction.

The gravitational field in this case is so weak that it is difficult to imagine it. Strange as it may seem, but it is they who “follow” the movement of celestial bodies, whose mass is sometimes impossible to imagine. All this is possible due to two features of gravitation, which are especially pronounced in the case of large physical bodies:

• Unlike atomic, it is more noticeable at a distance from the object. So, the gravity of the Earth keeps even the Moon in its field, and the similar force of Jupiter easily supports the orbits of several satellites at once, the mass of each of which is quite comparable to that of the Earth!
• In addition, it always provides attraction between objects, and with distance this force weakens at a low speed.

The formation of a more or less harmonious theory of gravity happened relatively recently, and precisely according to the results of centuries of observations of the motion of planets and other celestial bodies. The task was greatly facilitated by the fact that they all move in a vacuum, where there are simply no other possible interactions. Galileo and Kepler, two outstanding astronomers of that time, helped prepare the ground for new discoveries with their most valuable observations.

But only the great Isaac Newton was able to create the first theory of gravity and express it in mathematical representation. This was the first law of gravity, the mathematical representation of which is presented above.

Conclusions of Newton and some of his predecessors

Unlike other physical phenomena that exist in the world around us, gravity manifests itself always and everywhere. You need to understand that the term "zero gravity", which is often found in pseudo-scientific circles, is extremely incorrect: even weightlessness in space does not mean that a person or spaceship the attraction of some massive object does not work.

In addition, all material bodies have a certain mass, which is expressed in the form of the force that was applied to them, and the acceleration obtained due to this impact.

Thus, the forces of gravity are proportional to the mass of objects. In numerical terms, they can be expressed by obtaining the product of the masses of both bodies under consideration. This force strictly obeys the inverse relationship with the square of the distance between objects. All other interactions are completely differently dependent on the distances between the two bodies.

Mass as a cornerstone of theory

The mass of objects has become a special controversial point around which Einstein's entire modern theory of gravity and relativity is built. If you remember the Second, then you probably know that mass is a mandatory characteristic of any physical material body. It shows how an object will behave if force is applied to it, regardless of its origin.

Since all bodies (according to Newton) are accelerated when an external force is applied to them, it is the mass that determines how large this acceleration will be. Let's look at a clearer example. Imagine a scooter and a bus: if you apply exactly the same force to them, they will reach different speeds in different times. All this is explained precisely by the theory of gravity.

What is the relationship between mass and attraction?

If we talk about gravitation, then the mass in this phenomenon plays a completely opposite role to that which it plays in relation to the force and acceleration of the object. It is she who is the primary source of attraction itself. If you take two bodies and see with what force they attract the third object, which is located at equal distances from the first two, then the ratio of all forces will be equal to the ratio of the masses of the first two objects. Thus, the force of gravity is directly proportional to the mass of the body.

If we consider Newton's Third Law, then we can be sure that he says exactly the same thing. The force of gravity, which acts on two bodies located at an equal distance from the source of attraction, directly depends on the mass of these objects. In everyday life, we talk about the force with which a body is attracted to the surface of the planet as its weight.

Let's summarize some of the results. So, mass is closely related to acceleration. At the same time, it is she who determines the force with which the attraction will act on the body.

Features of the acceleration of bodies in a gravitational field

This amazing duality is the reason that in the same gravitational field, the acceleration of completely different objects will be equal. Suppose we have two bodies. Let's assign mass z to one of them, and Z to the other. Both objects are thrown to the ground, where they fall freely.

How is the ratio of the forces of attraction determined? It is shown by the simplest mathematical formula - z / Z. But the acceleration they receive as a result of the action of the force of gravity will be exactly the same. Simply put, the acceleration that a body has in a gravitational field does not in any way depend on its properties.

What does the acceleration depend on in the described case?

It depends only (!) On the mass of objects that create this field, as well as on their spatial position. The dual role of mass and equal acceleration of various bodies in a gravitational field have been discovered for a relatively long time. These phenomena have received the following name: "The principle of equivalence". This term once again emphasizes that acceleration and inertia are often equivalent (to a certain extent, of course).

The importance of the value G

From the school physics course, we remember that the acceleration of gravity on the surface of our planet (Earth's gravity) is 10 m / sec. ² (9.8, of course, but this value is used for simplicity of calculations). Thus, if we do not take into account the air resistance (at a significant height with a small fall distance), then the effect will be obtained when the body acquires an acceleration increment of 10 m / s. every second. Thus, a book that fell from the second floor of a house will move at a speed of 30-40 m / s by the end of its flight. Simply put, 10 m / s is the "speed" of gravity within the Earth.

Acceleration of gravity in the physical literature is denoted by the letter "g". Since the shape of the Earth is to a certain extent more reminiscent of a mandarin than a ball, the value of this value is far from being the same in all of its areas. So, at the poles the acceleration is higher, and at the tops high mountains it gets smaller.

Even in the mining industry, gravity plays an important role. Physics of this phenomenon can sometimes save a lot of time. For example, geologists are especially interested in perfectly accurate determination of g, since this allows exploration and finding of mineral deposits with exceptional accuracy. By the way, what does the gravitation formula look like, in which the value we have considered plays an important role? There she is:

Note! In this case, the gravitation formula means by G the "gravitational constant", the value of which we have already given above.

At one time, Newton formulated the above principles. He perfectly understood both unity and universality, but he could not describe all aspects of this phenomenon. This honor fell to the lot of Albert Einstein, who was also able to explain the principle of equivalence. It is to him that humanity owes a modern understanding of the very nature of the space-time continuum.

The theory of relativity, the work of Albert Einstein

At the time of Isaac Newton, it was believed that the reference points can be represented in the form of some kind of rigid "rods", with the help of which the position of the body in the spatial coordinate system is established. At the same time, it was assumed that all observers who mark these coordinates will be in a single time space. In those years, this provision was considered so obvious that no attempt was made to challenge or supplement it. And this is understandable, because within the limits of our planet there are no deviations in this rule.

Einstein proved that the accuracy of the measurement will be really significant if the hypothetical clock moves much slower than the speed of light. Simply put, if one observer, moving slower than the speed of light, will follow two events, then they will happen for him at the same time. Accordingly, for the second observer? the speed of which is the same or more, events can occur at different times.

But how is the force of gravity related to the theory of relativity? We will reveal this issue in detail.

The relationship between the theory of relativity and gravitational forces

In recent years, a huge number of discoveries have been made in the field of subatomic particles. The conviction is growing that we are about to find the final particle, beyond which our world cannot be fragmented. The more insistent is the need to find out exactly how those fundamental forces that were discovered in the last century, or even earlier, affect the smallest "bricks" of our universe. It is especially offensive that the very nature of gravity has not yet been explained.

That is why, after Einstein, who established the "incapacity" of classical Newtonian mechanics in this area, the researchers focused on a complete rethinking of the previously obtained data. In many ways, gravity itself has undergone a revision. What is it at the level of subatomic particles? Does it have any meaning in this amazing multidimensional world?

A simple solution?

At first, many assumed that the discrepancy between Newton's gravity and the theory of relativity could be explained quite simply by drawing analogies from the field of electrodynamics. One could assume that the gravitational field propagates like a magnetic field, after which it can be declared a "mediator" in the interactions of celestial bodies, explaining many inconsistencies between the old and new theory... The fact is that then the relative velocities of propagation of the forces under consideration would be significantly lower than the light one. So how are gravity and time related?

In principle, Einstein himself almost succeeded in constructing a relativistic theory based on precisely such views, but only one circumstance interfered with his intention. None of the scientists of that time had any information at all that could help determine the "speed" of gravity. But there was a lot of information related to the movement of large masses. As you know, they were just the generally recognized source of the emergence of powerful gravitational fields.

High speeds strongly affect the masses of bodies, and this is in no way like the interaction of speed and charge. The higher the speed, the greater the body weight. The problem is that the latter value would automatically become infinite if traveling at the speed of light or faster. Therefore, Einstein concluded that there is not a gravitational field, but a tensor field, for the description of which many more variables should be used.

His followers concluded that gravity and time are practically unrelated. The fact is that this tensor field itself can act on space, but cannot influence time. However, the genius physicist of our time Stephen Hawking has a different point of view. But that's a completely different story ...