The law of universal gravitation

On the slope of his days, Newton confessed how everything really happened. He strolled through the apple orchard of his parents and saw the moon in the daytime sky. And then, before his eyes, the apple comes off the branch and falls to the ground. At this time, Newton worked on the law of motion, he already knew that the fall of the apple is closely related to the action of gravity. He also knew that the Moon rotates in orbit, and does not hang in the air, that it is influenced by a certain force that keeps it in this orbit, not letting it fall from its trajectory and go into open space. It was at the time of the fall of the apple before Isaac came: to fall the apple, and to stay in orbit, the moon is forced by one force. The law of universal gravitation of Newton was close to the discovery.

Let's take a look at the background. Galileo and other Newton's predecessors study the motion of bodies (uniformly accelerated) that fall on the ground. It has been suggested that the phenomenon is purely natural and exists only at the surface of the globe. Kepler with his associates argues that in the spheres of heaven the laws are different, not at all those that govern the movement on Earth. All arguments boil down to the fact that the bodies of heaven , by virtue of their perfection, are moving in orbits again, in virtue of their perfection. In other words, gravity was divided into two types: terrestrial (imperfect) and heavenly (perfect).

And Newton's insight combined both types of gravity in his mind. We can say that this moment has become historical, combining the division of the false (Earth) and the artificial (the universe).

The result of Newton's calculations now sounds like this: the law of universal gravitation. The definition of it says: between the pair of bodies in the entire universe there is a force of mutual attraction. The law is in the form of the equation:

F = GMm / D2,

M and m - mean the masses of one and the second body, D - the distance between these bodies, F - the force of gravitational attraction. G here is a constant, is determined experimentally and, if expressed in SI units, is 6.67 × 10-11.

But the law of universal gravitation requires several observations. First, its action extends to all material physical bodies in the universe. For example, the book you read, like yourself, is also subject to the force of mutual gravitational attraction, equal in magnitude but opposite in direction. The power is too small even for sensitive instruments, but it does exist and it can even be calculated. Another example is the mutual attraction between you and the infinitely distant quasar, which is removed by billions of light years. These forces of attraction are smaller than in the previous example, but they exist.

Secondly, the earth's gravitational force at the surface affects all bodies in the wound measure and at any point. At this moment, this same force acts on you, which you can calculate by the formula indicated above, physically you feel it as your own weight. Drop something. And this object will rush to the earth at the same time. Galileo was the first to measure the experimentally estimated value of the acceleration of incidence near the earth's surface. Remember the letter g from the equation? But for Galileo this was an experimentally measured constant, and according to Newton this value (acceleration at free fall) can be determined by substituting the mass of the Earth (M) and its radius (D) into the formula. The subject of measurement of Galileo becomes mathematical calculations and forecasts of Newton.

Thirdly, the law of universal gravitation shows and explains the structure of our system (Solar), Kepler's laws, revealing the trajectory of the motion of the planet, can be deduced from it. For Kepler himself, these laws were only descriptive - scientists simply generalized observations in mathematical forms. In the great system of the world order, according to Newton, the deduced Kepler's laws are a direct consequence of the laws of mechanics and the law of universal gravitation. Again, we see the transformation of empirical conclusions obtained at the level of one, into clear logical substantiated conclusions and the transition to the level of the other.

Was she really told by Newton on the slope of her years? Was he telling the truth about his discovery? No documents testifying or refuting the fact that the problem of gravity Newton was engaged at that time and really himself, no. As you know, documents are inherent and lost. And it is also well known that Newton was an unpleasant person and terribly meticulous in that, at least somehow concerned the consolidation of priorities in science behind him. Therefore, to obscure the truth, feeling the slightest threat, was precisely in his character.
So it remains a question: why, having published his law of universal gravitation in 1687, he opened it in 1666th year? What divided these 20 years?