gravity

Despite the fact that gravity is the weakest interaction between objects in the universe, its importance in physics and astronomy is enormous, since it is able to influence physical objects at any distance in space.

If you are fond of astronomy, you probably thought about the question of what is such a thing as gravity or the law of universal gravitation. Gravity is a universal fundamental interaction between all objects in the Universe.

The discovery of the law of gravity is attributed to the famous English physicist Isaac Newton. Probably, many of you know the story of an apple that fell on the head of a famous scientist. Nevertheless, if you look deep into history, you can see that the presence of gravity was thought about long before his era by philosophers and scientists of antiquity, for example, Epicurus. Nevertheless, it was Newton who first described the gravitational interaction between physical bodies within the framework of classical mechanics. His theory was developed by another famous scientist - Albert Einstein, who in his general theory of relativity more accurately described the influence of gravity in space, as well as its role in the space-time continuum.

Newton's law of universal gravitation says that the force of gravitational attraction between two points of mass separated by a distance is inversely proportional to the square of the distance and directly proportional to both masses. The force of gravity is long-range. That is, regardless of how a body with mass moves, in classical mechanics its gravitational potential will depend purely on the position of this object at a given moment in time. The greater the mass of an object, the greater its gravitational field - the more powerful the gravitational force it has. Such cosmic objects as galaxies, stars and planets have the greatest force of attraction and, accordingly, rather strong gravitational fields.

Gravity fields

Earth's gravitational field

The gravitational field is the distance within which the gravitational interaction between objects in the Universe takes place. The greater the mass of an object, the stronger its gravitational field - the more noticeable its impact on other physical bodies within a certain space. The gravitational field of an object is potentially. The essence of the previous statement is that if we introduce the potential energy of attraction between two bodies, then it will not change after the latter move along a closed contour. From here emerges another famous law of conservation of the sum of potential and kinetic energy in a closed circuit.

In the material world, the gravitational field is of great importance. It is possessed by all material objects in the Universe that have mass. The gravitational field can influence not only matter, but also energy. It is due to the influence of the gravitational fields of such large space objects as black holes, quasars and supermassive stars that solar systems, galaxies and other astronomical clusters are formed, which are characterized by a logical structure.

The latest scientific data show that the famous effect of the expansion of the Universe is also based on the laws of gravitational interaction. In particular, the expansion of the Universe is facilitated by powerful gravitational fields, both small and its largest objects.

Gravitational radiation in a binary system

Gravitational radiation or gravitational wave is a term first introduced into physics and cosmology by the famous scientist Albert Einstein. Gravitational radiation in the theory of gravity is generated by the movement of material objects with variable acceleration. During the acceleration of the object, the gravitational wave, as it were, “breaks away” from it, which leads to fluctuations in the gravitational field in the surrounding space. This is called the gravitational wave effect.

Although gravitational waves are predicted by Einstein's general theory of relativity, as well as other theories of gravity, they have never been directly detected. This is primarily due to their extreme smallness. However, there is circumstantial evidence in astronomy that can confirm this effect. Thus, the effect of a gravitational wave can be observed on the example of the approach of binary stars. Observations confirm that the rate of approach of binary stars to some extent depends on the loss of energy of these space objects, which is presumably spent on gravitational radiation. Scientists will be able to reliably confirm this hypothesis in the near future with the help of a new generation of Advanced LIGO and VIRGO telescopes.

In modern physics, there are two concepts of mechanics: classical and quantum. Quantum mechanics was derived relatively recently and is fundamentally different from classical mechanics. In quantum mechanics, objects (quanta) have no definite positions and velocities, everything here is based on probability. That is, an object can occupy a certain place in space at a certain point in time. It is impossible to reliably determine where he will move next, but only with a high degree of probability.

An interesting effect of gravity is that it can bend the space-time continuum. Einstein's theory says that in the space around a bunch of energy or any material substance, space-time is curved. Accordingly, the trajectory of particles that fall under the influence of the gravitational field of this substance changes, which makes it possible to predict the trajectory of their movement with a high degree of probability.

Theories of gravity

Today, scientists know over a dozen different theories of gravity. They are divided into classical and alternative theories. The most famous representative of the former is the classical theory of gravity by Isaac Newton, which was invented by the famous British physicist back in 1666. Its essence lies in the fact that a massive body in mechanics generates a gravitational field around itself, which attracts smaller objects to itself. In turn, the latter also have a gravitational field, like any other material objects in the Universe.

The next popular theory of gravity was invented by the world famous German scientist Albert Einstein at the beginning of the 20th century. Einstein managed to more accurately describe gravity as a phenomenon, and also to explain its action not only in classical mechanics, but also in the quantum world. His general theory of relativity describes the ability of such a force as gravity to influence the space-time continuum, as well as the trajectory of elementary particles in space.

Among the alternative theories of gravity, perhaps the most attention deserves the relativistic theory, which was invented by our compatriot, the famous physicist A.A. Logunov. Unlike Einstein, Logunov argued that gravity is not a geometric, but a real, fairly strong physical force field. Among the alternative theories of gravity, scalar, bimetric, quasi-linear and others are also known.

1. For people who have been in space and returned to Earth, it is quite difficult at first to get used to the force of the gravitational influence of our planet. Sometimes it takes several weeks.
2. It has been proven that the human body in a state of weightlessness can lose up to 1% of bone marrow mass per month.
3. Among the planets, Mars has the least force of attraction in the solar system, and Jupiter has the greatest.
4. The well-known salmonella bacteria, which are the cause of intestinal diseases, behave more actively in a state of weightlessness and can cause much more harm to the human body.
5. Among all known astronomical objects in the universe, black holes have the greatest gravitational force. A black hole the size of a golf ball could have the same gravitational force as our entire planet.
6. The force of gravity on Earth is not the same in all corners of our planet. For example, in the Hudson Bay region of Canada, it is lower than in other regions of the globe.