If 7 billion people take off at the same time, will the earth be destroyed? Expert: Maybe it's the destruction of all mankind

Now the total global population has increased to 7.83 billion. I wonder if you have ever thought about it. If you gather so many people in one place and let them jump at the same time, what impact will it have on the earth? Will it directly destroy the earth? ?

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Impact on the Earth as a whole

To understand this problem, we first need to know a well-known physics theory: the law of conservation of momentum. The expression for momentum is velocity times mass. The law of conservation of momentum is universal, and together with the law of conservation of energy and the law of conservation of angular momentum are considered to be the three basic conservation laws in modern physics.

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If a part of a system changes its momentum in one direction under the action of an internal force, the remaining part will have the same amount of momentum change in the opposite direction. Taking a rocket as an example, a rocket contains the mass of the rocket and the mass of the fuel. At first, since the velocity is 0, the total momentum is also 0. When the rocket is started, the fuel will be ignited and released to the ground, that is to say, the gas will flow toward the ground. The ground has a momentum. Due to the conservation of momentum, the rocket will have the same momentum change in the opposite direction of the ground (the sky), which shows that the rocket takes off.

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The people on the earth and the earth itself are a system. When all the human beings take off, if all the human beings in the world gather in one place to take off, then there will be a place perpendicular to the earth, and there will be a momentum in the direction of the sky, so the earth All but the human race must have a momentum in the opposite direction. What will be the result?

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We all know that the mass of the earth is 5.965×10^24 kilograms, and the average mass of all human beings, we calculate according to 60 kilograms (120 kilograms), the total mass of 7.83 billion people is 4.698*10^11 kilograms, people take off The speed that can be achieved in an instant is about 3~4 meters per second. Let’s exaggerate a little. Calculated according to 5 meters per second, the momentum generated by 7.83 billion people taking off at the same time is 2.349*10^12kg·m/s. This means that the remaining part of the earth excluding humans needs to produce the same amount in the opposite direction, and it can be calculated that the remaining part of the earth excluding humans will have a 3.93*10^(-13) m/s The speed is extremely small, so small that the impact on the earth is negligible, and the earth will not be destroyed by it.

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Therefore, human beings are too small relative to the earth. Even if all human beings are put together, they will not have much impact on the earth. Although the earth as a whole will not have much impact, it will still have some impact on the local earth of the earth and humans themselves. What are the specific impacts?

Will humans go extinct?

First of all, after all human beings take off at the same time, and then fall back to the ground, the noise caused by this process is extremely huge, not to mention the sound of human speech, even if it is just the impact of shoes and the ground, the cumulative noise of 7.83 billion pairs of shoes is also extremely high. scary. The limit of noise that an average person can tolerate is around 160 decibels. When it reaches 165 decibels, many animals will die because they cannot bear it. If the noise exceeds 175 decibels, humans will also die because they cannot bear it.

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And 7.83 billion people take off at the same time. It is necessary to gather all these together and make a unified order. The time to take off and return to the ground is almost the same, and the noise generated can reach more than 200 decibels, which means that most people on the scene will The noise is too loud to cause death, even if it is barely able to survive, it will cause great harm to the body, and the rest of life can basically only be spent in pain. Therefore, if there is such an event, the basic result will be the extinction event of all human beings, and the starting point will be the graveyard of all human beings.

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other effects

In addition to the possible extinction of humans, it will also have an impact on local geological activity, triggering small-scale earthquakes. Previously, the BBC had planned to explore whether the earth would move after all humans took off at the same time, or whether the time of the earth would be shortened. At that time, the program team organized 50,000 people to take off at the same time, resulting in an earthquake with a magnitude of 0.6 on the Richter scale.

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If 7.83 billion people take off at the same time, it is bound to cause an earthquake, and the series is not small. It was also calculated at the time that if you want the earth to shorten the time by 2 milliseconds in one day, that is, to reach the magnitude of 8.6 of the previous earthquake in Japan, then 7.83 billion people are not enough, at least 5*10^16 people are needed, that is 500 million people. That's 7 million times the population of our entire planet. Therefore, although it will cause an earthquake of a certain size, it will not be a very strong earthquake.