Why do we have no artificial gravity in space?

Put a person in space, away from the gravity of the earth’s surface, and he will feel weightlessness. Although all the masses of the universe will still affect it gravitationally, they will also attract any spacecraft in which the person is located, so he will float. And yet, on TV, we were shown that the crew of a certain space ship was quite successfully walking with the feet on the floor under any conditions. For this, artificial gravity is used, created by installations on board a fantastic ship. How close is it to real science?

Captain Gabriel Lorca on the Discovery Bridge during the imitation of the battle with the Klingons. The entire crew is attracted by an artificial gravity force, and it is as if already a canon

Concerning gravity, Einstein’s great discovery was the principle of equivalence: with uniform acceleration, the reference frame is indistinguishable from the gravitational field. If you were on a rocket and could not see the Universe through the porthole, you would have no idea what is happening: are you being pulled down by the force of gravity or by the acceleration of a rocket in a certain direction? Such was the idea that led to the general theory of relativity. After 100 years, this is the most correct description of gravity and acceleration, which we know.

The identical behavior of the ball, falling on the floor in the flying rocket (on the left) and on the Earth (on the right), demonstrates the Einstein equivalence principle

There is another trick, as Ethan Siegel writes, which we can use if we want: we can make the spacecraft spin. Instead of linear acceleration (like the thrust of a rocket), it is possible to make centripetal acceleration work, so that a person on board feels the outer shell of the spacecraft that pushes him toward the center. This technique was used in the 2001 Space Odyssey, and if your spaceship were large enough, the artificial gravity would be indistinguishable from the real one.

Only one thing but. Three of these types of acceleration – gravitational, linear and rotational – are the only ones that we can use to simulate the effects of gravity. And this is a huge problem for the spacecraft.

The concept of the station in 1969, which was supposed to be assembled in orbit from the worked-out stages of the Apollo program. The station had to rotate on its central axis to create artificial gravity

Why? Because if you want to go to another star system, you will need to speed up your ship to get there, and then slow it down upon arrival. If you can not protect yourself from these accelerations, you are in for a disaster. For example, to accelerate to a full pulse in the “Star Trek”, up to several percent of the light speed, we will have to experience an acceleration of 4000 g. It is 100 times faster than acceleration, which starts to interfere with the blood flow in the body.

The launch of the space shuttle Columbia in 1992 showed that acceleration takes place over a long period. Acceleration of the spacecraft will be many times higher, and the human body can not cope with it

If you do not want to be weightless during a long journey – so as not to expose yourself to terrible biological wear such as loss of muscle and bone mass – the body must constantly act force. For any other force, this is quite easy to do. In electromagnetism, for example, it would be possible to place a crew in a conducting cabin, and many external electric fields would simply disappear. It would be possible to arrange two parallel plates inside and get a constant electric field, pushing charges in a certain direction.

If gravity worked the same way.

Such a concept as a gravitational conductor simply does not exist, as is the ability to shield oneself from gravitational force. It is impossible to create a uniform gravitational field in the region of space, for example, between two plates. Why? Because unlike the electric force generated by positive and negative charges, there is only one type of gravitational charge, and this is mass-energy. Gravitational force always attracts, and from it you can not hide anywhere. You can only use three types of acceleration – gravitational, linear and rotational.

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