# Difficult gravity

(ORDO NEWS) — It would seem that absolutely every person has heard about gravity since school and, perhaps, everyone remembers the beautiful legend, how an apple fell on Newton’s head, and after that he discovered the law of universal gravitation.

Yet this is extremely superficial knowledge and we decided to try in simple language to explain as comprehensively as possible what gravity is.

## The basics

In extremely simple words, then gravity is the attraction between objects in the Universe. The index of gravity between two bodies can be determined by having the mass of these bodies and knowing the distance between them.

It follows from this that the stronger the gravitational field, the greater the mass of the body and the higher its acceleration. The strength of the gravitational field directly depends on the size of the object.

Since the lunar gravity is 6 times lower than that of the earth, then the weight of an object on the surface of the moon will be 6 times less than on Earth . This was first substantiated and proved with the help of mathematical calculations by the English scientist Isaac Newton in the distant 17th century.

## Was there an apple?

Newton became the founder of a new era in the natural sciences and this was facilitated by his work “Mathematical Principles of Natural Philosophy”, where he describes the law of gravitation and other important laws of mechanics, discovered by him. It took the scientist more than 20 years to create this work.

It is likely that the legend of the fallen fruit has some basis under it, but the apple definitely did not fall on the scientist’s head and did not become the reason for many years of work.

Before Newton, scientists from different countries of the world studied and described the laws of attraction, but only Isaac Newton was able to formulate the mathematical relationship between gravity and the motion of celestial bodies.

Simply put, between the fall of an apple from a tree branch and the rotation of the Moon around the Earth lies the same force – gravity, which applies to all objects in the world.

What today seems to be a generally known fact, at one time laid the foundation for celestial mechanics and gave rise to the development of dynamics. Newton’s model of the world was considered perfect for more than two centuries, until General Relativity and Quantum Mechanics appeared.

## Modern science

Of the four fundamental interactions known to date, gravity is the weakest. All particles and bodies composed of them are subject not only to gravitational interaction, but strong (the bond of nucleons in the nucleus and nuclear forces), electromagnetic and weak (responsible for some types of nuclear processes).

Sometimes, considering some special cases of interaction with small gravity, scientists still apply Newton’s theory, but when it comes to strong gravity and large scales, then it cannot do without Einstein’s General Theory of Relativity.

Scientists say that in order to understand gravity at the quantum level, the description of interactions will occur by means of quantum theory (which does not yet exist).

## Myths and misconceptions

How can we do without myths in science? They touched gravity too.

### Artificial satellites will be in Earth’s orbit forever

It’s a lie. In addition to gravity, satellites are affected by other factors that directly affect their position: the atmosphere in low orbit, the gravity of the moon and planets.

If you do not control the satellite and release it into free “swimming”, then it will most likely fly into open space or collapse to Earth.

### There is no gravity in space

Lie. Gravity is everywhere, and even astronauts floating aboard the ISS experience strong Earth’s gravity (slightly less than on the surface).

### An object near a black hole will be torn apart

The gravitational pull of a black hole will increase as you get closer to it, but this does not mean that tidal forces can be that catastrophically strong for an object.

All the power of a black hole is concentrated in its center, so in most cases, in order to be torn apart by a black hole, the object will have to pass the event horizon.

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