# Why can the earth rotate 4.6 billion years without stopping? Where does its energy come from?

This paper takes part in the series essay competition of “great science” of Recordunkown.

As we all know, there are countless stars, planets and other celestial bodies in the vast universe. One of the common characteristics of these celestial bodies is that they are all in motion. In addition to orbiting around things of greater mass, they are also constantly rotating.

The earth is a planet. When it revolves around the sun, it is also rotating. The linear speed of rotation on the equator has reached 465 meters per second, which seems to many people to have exceeded the speed of sound. However, when we live on the earth, we do not feel that the earth is rotating because of gravity.

The earth has been rotating since the day it was born. Up to now, it has been rotating for 4.6 billion years, so many people will have such a question: why can the earth rotate for 4.6 billion years without stopping? Where does its energy come from? I believe many people want to know the answer to this question. From the point of view of physics, there is no perpetual motion machine in the world. There was a time when the research and exploration of perpetual motion machine was a very hot topic, and many people tried to develop it and became famous in the world.

However, after repeated failures, many people realize that the perpetual motion machine is impossible to exist. Up to now, few people have studied the perpetual motion machine, because now a junior high school student knows that the perpetual motion machine violates the law of conservation of energy, and it is impossible to exist.

In our real world, the law of conservation of energy is one of the basic laws of nature. It tells us that energy will neither be produced nor disappear out of thin air. It will only be transformed from one form to another, or transferred from one object to another, while the total amount of energy remains unchanged. If an object wants to rotate forever, it needs to achieve a perfect balance between kinetic energy and other energy, that is, the energy will not be consumed in other directions. But in fact, such a thing can not happen in reality, so the real perpetual motion machine can not exist.

But when we look at the universe, it seems that the situation has changed a little, because we see all kinds of celestial bodies that never stop rotating. For example, the earth has been rotating for 4.6 billion years since its birth. Is this the perpetual motion machine we have been looking for? If the constant rotation of the earth is similar to the principle of perpetual motion machine, does it violate the law of conservation of energy?

To understand this problem, we still need to find out the energy source of the earth’s rotation. The earth is the planetary body of the universe, and all the planets in the universe have rotation motion, so this rotation motion stands in the macro cosmic angle, we can trace back to the moment of the big bang. The universe started from the big bang. At the moment of the explosion, infinite energy pushed the expansion of space-time, and matter expanded from nothing in the violent tumbling.

The huge energy generated by the big bang makes the whole universe matter in motion. In the big system of the universe, energy is conserved, and other different types of energy can be converted into kinetic energy, so matter can keep moving, and the nebula formed by them is also in motion. Stars, planets and other celestial bodies are born in nebulae, so their formation process is a process of motion.

From the macro world of the universe, we go into the micro world. In the micro world, we will find that particles are in motion. Even if we see objects that are still in our eyes, the particles in their micro world are in motion. Therefore, in our eyes, seemingly motionless objects are always moving. Only when they stand in a relative position can they present a relative static state.

In addition, all things in the world have gravitation, and the role of gravitation in the universe is more obvious. The motion relationship between celestial bodies is determined by gravitation. The reason why the earth revolves around the sun is that the mass of the sun is much greater than that of the earth, and the mass of the galactic center is much greater than that of the stars, so the stars can only move around it. So part of the earth’s rotation energy comes from gravity. This gravity has the gravity from the sun and the tidal force from the moon.

Of course, the above is only our preliminary analysis of the energy sources of the earth and other celestial bodies that can keep rotating. In fact, they may be far from the final truth. After all, we have very little knowledge of the universe, which may not even be skin. And we still don’t know why the universe has gravity.

Some scientists believe that the gravitational force of the universe may be related to dark matter and dark energy. Dark matter forms the membrane framework of the universe, and dark energy fills it, making the universe expand continuously. If we think of the universe as a sphere with infinite elasticity, then stars, planets and other celestial bodies are equivalent to adhering to the sphere membrane.

The weight of Tianxiu’s self weight will produce a downward concave force on the elastic sphere of the universe. In this way, there will be a pulling force around the celestial body, and this pulling force is gravity. It will pull the objects in the surrounding space, and there will be gravity. This is also the space distortion theory proposed by Einstein’s general theory of relativity. Our universe is a distorted space structure.

After seeing that the celestial bodies in the universe can rotate continuously for a long time, we think of the perpetual motion machine. If the model of the celestial body’s continuous rotation is equivalent to a perpetual motion machine, it means that the perpetual motion machine does not seem to exist. Although the current physics believes that the perpetual motion machine is against the law of eternal energy, it is impossible to be born, but with the rapid development of human science and technology, there may be new theories to support the emergence of perpetual motion machine in the future.

Standing in the vast universe, anything that is impossible can become possible. Perpetual motion machine just can’t exist under the existing physical system, and it doesn’t mean that it can’t be born in the future science and technology. It is possible that one day, a great physicist of genius will appear again, who has solved the mystery of perpetual motion machine and developed a perpetual motion machine similar to the celestial body that can rotate continuously, which will have unimaginable significance to human beings.

Of course, it is not so easy to really develop perpetual motion machine, and it is not possible to achieve it in a short time. Perhaps only when we truly understand the mystery of the rotation of celestial bodies in the universe can it be realized. We are looking forward to that day.