The most common myths about gravity. Which of this is true

There are many myths in the world. I'm not talking about those who were born in ancient Greece, but about those that people still come up with just out of ignorance. Often, some information is either distorted or simply misunderstood by one person and disseminated among others. So it turns out that we know about objects and phenomena that in fact does not exist. To dispel such myths, we periodically publish "exposing" articles in which we tell the true nature of things and how they work. To do this, we collect the opinions of scientists, researchers and just common sense. All together this allows you to understand the nature of things and, as they say, become smarter. This time we'll talk about gravity, which causes a lot of controversy. And also Hollywood films spoil our understanding of what it really is.

What's with gravity in space?

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Which is stronger – electromagnetic or gravitational force

Many people think that electromagnetism is stronger than gravity. In general, if you do not find fault with some subtleties, this is true, but, as always, there are some “but”.

Electromagnetism is a force that arises at the most microscopic level and in some way is the basis of all mechanics, creating the main forces. For example, an atom of something ( let's say hydrogen ) has protons that fly around electrons. As a result, we have electric charge and mass. The first determines the strength of the electromagnetic interaction, and the second already refers to gravity.

`Ученые обнаружили неизвестный источник гравитационных волн`

These forces are considered separately due to the fact that they have their influence at different levels. It's no secret that electromagnetic particles of one charge are repelled, while those of the opposite charge are attracted. If we are dealing with a system in which there are particles with positive and negative charges, then we can assume that it is neutral. An example is an atom that is, as it were, in equilibrium .

If we take a huge number of atoms and begin to consider, for example, a planet, then the alignment of forces will change. In this case, the whole body as a whole will have a plus or minus neutral charge, and it is the force of gravity that will come to the fore. That is, electromagnetism is really strong, but only when it comes to the connection of elementary particles. At this level, it is really stronger than gravity. When it comes to large objects, gravity is more important .

At the micro level, everything is balanced by our own forces.

Can a parade of planets reduce gravity?

There is an opinion that the parade of planets is able to reduce gravity on our planet, but this is pure fiction. Well, or just a delusion.

A parade of planets is such a phenomenon when the planets line up relative to the Sun in one line. True, they still will not end up on one straight line and there will be small deviations along the axis. But this is enough to slightly change the gravitational interaction of the planets.

`Скоро на орбите появится космический отель с искусственной гравитацией`

If you do not go into physical formulas, then we can say that the force of gravity is the greater, the closer objects are to each other or the larger their size. For example, Venus has a great influence on the Earth due to the fact that it is close. However, it is not very large. Saturn is far away, but it is huge, and therefore it can also influence the Earth.

Being on the surface of our planet, by gravity, we usually mean not the force of gravity, but our weight. Relative to other planets, we constantly fall with the Earth , but our weight does not change.

The planets don't line up that way. There are still deviations.

However, there is still some effect from the parade of planets. But we still say that it does not exist. This is due to the fact that the deviation is very small. If we talk about a person, he will “feel” it as a change in weight by about one millionth of a gram. It is easier to say that there is no change than to calculate this value.

It is a completely different matter if we talk about the influence on our planet of a giant in comparison with it, the Sun or the Moon very close to us. Both of these celestial bodies can affect the Earth, up to the appearance of the ebb and flow. But in the case of planets, there is no need to talk about such an impact.

`Искусственная гравитация перестаёт быть фантастикой.`

What will happen to a body near a black hole

Some misconceptions suggest that a body that happens to be near a black hole must be torn apart. Don't worry, it won't happen.

When a body approaches a black hole, the force of gravity and tidal forces begin to grow very strongly, but it is not at all necessary that the tidal forces become very large when approaching the event horizon.

A black hole doesn't have to tear a body apart.

`Приливными силами называют те силы, которые возникают в телах, свободно движущихся в неоднородном силовом поле. Может показаться, что действие таких сил может влиять на приливы и отливы на Земле, и это действительно так. Собственно, название этих сил от этого и произошло.`

Tidal forces depend on the distance to the body and its size. It is important that the distance is calculated from the center, not from the edge . The size of a black hole is directly proportional to its mass. From this we can conclude that if one and the same object falls into black holes of different sizes, then the tidal forces will depend only on the mass of the black hole. And based on what has been said about mass and size, we can conclude that the larger the hole, the less tidal forces will be on the horizon.

That is, if the black hole is relatively small, it can really affect the bodies flying up to it. But if the size of the black hole is huge, then it will simply swallow the body and that's it. Some science fiction films are based on this, where the heroes fall into a black hole and nothing happens to them.

In the movie Interstellar, the characters were able to walk through the black hole due to its size.

Is there gravity in space

When we watch a movie about space or watch a broadcast from the ISS in which astronauts soar in zero gravity, many of us think that there is no gravity. This is mistake.

In fact, gravity in orbit is not what it is, it is almost no different from what we feel on Earth. If we take the distance from the center of the Earth to the ISS, then it will be about 10 percent greater than the distance from the center of the Earth to its surface. If we remember that gravity depends on the size of bodies and on their distance from each other, then it becomes clear that gravity in orbit is much less than Earth's.

`Впервые зафиксированы гравитационные волны от слияния черной дыры и нейтронной звезды`

Astronauts can feel weightlessness not because there is no gravity in orbit, but because they are constantly in a state of free fall with their ship or space station. Nevertheless, if we put a huge stepladder and climb to the upper step, which will be at the altitude of the ISS orbit, we will not take off, but will stand on it. Our gravity will change slightly, but not enough to take off.

This is not due to the absence of gravity, but, on the contrary, due to the fact that it is.

Quite simply, a space station in orbit moves at a tremendous speed and constantly strives to fly past the Earth, as it were. Its gravity, in turn, keeps the station from "flying away". As a result, the cosmonauts with their spacecraft revolve around the Earth and, due to the centrifugal force, are in a balanced state of weightlessness. It turns out that there is gravity in orbit, and moreover, it is it that allows the astronauts to experience weightlessness, no matter how paradoxical it may sound.

`Ученые возобновили поиск гравитационных волн при помощи улучшенных детекторов`

How long can satellites fly around the Earth

It is believed that artificial satellites of the Earth or other celestial bodies can revolve around our planet forever. This is not entirely true, although there is some truth in this reasoning.

It all depends on what orbit the satellite is in. If it is in low orbit, then there is at least small, but atmospheric resistance. As a result, the speed gained by him, which compensates for the force of gravity due to centrifugal force, will gradually decrease. As the speed decreases, the satellite's orbit will gradually decrease, and the speed will drop even more. As a result, sooner or later, he will fall. Of course, if you do not constantly set it in motion with the engine. But we are considering an example in which it flies by itself. For example, if the end of the world has occurred and there is no one to control it.

There are a lot of things in orbit, but over time it will clear itself of debris and other objects.

If you raise a satellite to an orbit where there is no influence of the atmosphere, then other factors begin there, and the moon , the sun and other planets will exert a gravitational effect on the satellite. Each such impact will be small, but if we are talking about time on the scale of the universe, then such forces will lead to a chaotic change in the satellite's orbit . As a result, the speed of the satellite will change, whether its distance from the Earth. All this will lead to an imbalance of forces that kept him in orbit and he will either fly into open space, or go to a lower orbit, and there is atmosphere, resistance and goodbye.

`В далеком космосе обнаружены круглые, таинственные объекты`

As a result, the satellite can fly around the Earth for a long time, but not indefinitely. What can we say, even if the Moon is gradually “running away” from us into open space and sooner or later will completely leave the Earth's gravitational field?

As you can see, there are many myths about gravity, like about any other phenomenon. For example, our Ramis Ganiev just recently prepared an article about myths related to the Sun , and some time ago I wrote about myths related to radiation . By examining our revelations, you can understand our world a little better. We will continue to publish articles about such myths, and you write in the comments or in our Telegram chat , what you would like to know better from what is often accompanied by a large number of misconceptions. We will disassemble and show everything, tell you.