When a teacher mentions a pre-existing concept of planet Earth as a plane resting on whales, elephants or turtles during physics classes in primary school, smiles appear on the faces of students and even laughter is heard in the classroom. It is now that many already in kindergarten know that the Earth is a ball, and the force of gravity affects all material objects. However, let’s imagine for a moment that we don’t know anything about gravity. How then to explain that people are kept on the surface, and the water of the oceans does not pour out into the void of outer space, if you do not use the concept of a flat planet? If gravity is a mystery to us, then perhaps nothing. That is why it is so important to treat the past with understanding, because each time has its own discoveries.
The force of gravitational attraction was discovered by I. Newton in 1666. Before him, gravitation was tried to explain by such outstanding scientists of his time as Huygens, known for his works on centrifugal force, Descartes, as well as Kepler, who formulated the fundamental three laws that govern the movement of celestial objects. However, these were only assumptions based more on conjecture rather than fact. None of them gave a holistic understanding of the world order. Newton, on the other hand, intended to create a complete theory, within the framework of which the force of attraction and the phenomena connected with it could be explained. And he succeeded. Not only theoretical premises with formulas were formulated, but a full-fledged model was created. It turned out to be so successful that even now, centuries later, the general theory of relativity, being a development of Newton's ideas, is used in the calculations of celestial mechanics.
Its formulation is extremely simple and memorable: the force with which objects are attracted depends on their mass and distance. This definition is expressed as follows:
F = (M1 * M2) / (R * R),
where M1 and M2 are the masses of objects; R is the distance.
Usually, acquaintance with classical theory begins precisely with this formula. For a more accurate representation, the entire right-hand side should be multiplied by the gravitational constant.
The conclusion is the following: the more massive the object, the more attractive it attracts the environment. Moreover, it does not matter at all whether it will be a sphere weighing 1 kg, or a point with the same weight. At the same time, when calculating a system of two bodies, for example, the Sun and the Earth, the latter attracts the star to itself in the same way. The force of gravity of the earth, interacting with the field of the Sun, forms a common center of mass around which mutual circulation takes place. It just seems that the Sun is the center of our system. True, although it is in the star, it does not coincide with the physical midpoint.
The force of gravity can be determined in the framework of the classical law of gravity, subject to two conditions:
- the speed of the objects of the system in question is much less than the speed of the light ray;
- the potential of the gravitational field is relatively small.
Soon after Newton completed the work of attraction, the need for its substantial improvement became apparent. The fact is that although the motion of the bodies of the celestial sphere could be calculated using the proposed formulas, sometimes there were situations when Newton's theory turned out to be inapplicable, since it yielded completely unpredictable results.
The flaws were eliminated by Einstein, who proposed a seriously modified model that takes into account both the speed of light and too strong gravitational fields. However, now even such a general theory of relativity has ceased to be a universal answer to all questions: in the microworld its postulates are incorrect.