The sun consumes 4.2 million tons of matter every second and burns for 4.6 billion years. Why hasn’t the sun finished burning?

Photosynthesis provides the basis for the growth of plants on the earth, and plants provide sufficient food for the earth’s animals and humans. The remains of ancient animals and plants have evolved over a long period of time to form the coal and oil necessary for human civilization. These are The benefits of the sun to the earth. The sun is selfless, it burns itself, but illuminates the whole earth. The sun continuously delivers a lot of energy to the earth. According to the statistics of scientists, the energy radiated by the sun per second is 3.9×10∧26 joules, of which 7.3×10∧17 joules of energy is received by the earth, and the earth receives it every second. The energy is only one-twentieth billionth of the total solar radiation.

In the solar energy received by the earth, human beings can use only one ten thousandth of the energy. It can be seen that the energy generated by the sun is huge. Einstein is a very great scientist. He created the mass-energy equation E=MC^2, which lets us know that the mass of matter consumed by the sun per second is as high as 4.2 million tons. The problem is that the sun consumes 4.2 million tons per second. Thousands of tons of material, and this time has lasted for a full 4.6 billion years, why hasn’t the sun been burned out?

To know the answer, first we have to figure out how the sun burns. Many people think that the burning of the sun and the burning of the earth are the same. In fact, this idea is wrong. The burning of the earth and the burning of the sun are two completely different burnings. The burning of the earth is a chemical reaction, while the burning of the sun It is a physical reaction. The combustion of the sun is essentially a nuclear fusion reaction. Due to pressure and high temperature, intense nuclear fusion reactions are going on inside the sun all the time. The reaction of energy, so the sun can emit light and heat.

The sun is a star, its mass accounts for 99.8% of the total mass of the solar system, about 2.0×10^27 tons, while the mass of the earth is only 60 trillion tons, and the mass of the sun is 330,000 times that of the earth. The strong gravitational force generated by the mass of the sun and the strong gravitational force generate huge pressure and temperature inside the earth. According to observations, the temperature inside the sun is as high as 1500 degrees Celsius. It is precisely because of this that continuous nuclear fusion reactions can occur inside the sun, because The prerequisite for nuclear fusion reaction is high temperature and high pressure. For the nuclear fusion reaction to occur, another raw material is needed, that is, hydrogen, and the sun has an extremely rich hydrogen raw material.

According to scientists’ analysis, the sun is mainly composed of two elements, hydrogen and helium. Among them, the hydrogen required for nuclear fusion reaction accounts for 75% of the total mass of the sun, while helium only accounts for 23%, and the remaining 2% is other trace elements. Scientists said that the life of the sun is 10 billion years, and now the sun has continued to burn for 4.6 billion years. It stands to reason that the sun still has half of the hydrogen element, but the research results are unexpected, because after 4.6 billion years In the combustion of the sun, the hydrogen consumed by the nuclear fusion reaction of the sun only accounts for 0.03% of the total mass of the sun, which is equivalent to the mass of 100 Earths. It can be seen that the sun still has a lot of hydrogen, which is almost inexhaustible.

Since the sun is still very rich in hydrogen, why do scientists predict that the sun has only 5 billion years of life left? This is because the sun is a star, and a star has its life cycle. A star will go through the stages of nebula, star, red giant, white dwarf, black dwarf, and black hole in its lifetime. This process lasts for about 10 billion years, that is, stars The longest lifespan is 10 billion years. After 10 billion years, the excess hydrogen element becomes useless matter, because the star itself has perished. Therefore, although the sun consumes 4.2 million tons of material per second and burns for 4.6 billion years, the material consumed in these dozens of years accounts for a very small proportion of the sun’s mass and has almost no effect on the sun, so the huge mass is that the sun can last for a long time. The main condition for burning, in addition to mass, the sun can burn for 4.6 billion years, is that its burning is very stable, why can the sun burn so stable?

I believe everyone has heard of hydrogen bombs. Like the sun, hydrogen bombs release huge amounts of energy through nuclear fusion reactions. However, the difference between hydrogen bombs and the sun is that the energy released by hydrogen bombs is very short, usually only a few seconds. The generated energy is released, but the sun releases energy for 4.6 billion years. Why doesn’t the sun explode in an instant like a hydrogen bomb? That is because the gravitational force generated inside the sun and the radiation pressure generated by the nuclear fusion reaction form a dynamic balance. Although nuclear fusion reactions occur both inside the sun and inside the hydrogen bomb, there are still some differences between the two nuclear fusion reactions. The hydrogen bomb is an artificial nuclear Fusion reaction, this kind of reaction requires a temperature of more than 100 million degrees Celsius to occur, but the temperature inside the sun is only 1500 degrees Celsius, which is obviously not enough, so why can nuclear fusion reactions occur inside the sun?

That’s because the sun uses the quantum tunneling effect to achieve a nuclear fusion reaction inside. What is the quantum tunneling effect? The so-called quantum tunneling effect is that when energy or temperature is insufficient, matter can also undergo nuclear fusion reaction, but the probability of nuclear fusion reaction is very low, which is difficult to use quantum tunneling effect to generate nuclear fusion reaction on earth. Otherwise, humans have already created a controllable nuclear fusion reaction. The sun is just the opposite. The mass of the sun is 330,000 times that of the earth. Its huge mass allows a large number of particles to participate in nuclear fusion reactions, so even if the probability of quantum tunneling is low, relying on the huge volume of the sun makes the probability extremely high. Low quantum tunneling effect becomes a reality. The main feature of the nuclear fusion reaction produced by quantum tunneling is that it is slow and stable, not as fast and unstable as a hydrogen bomb, which is another reason why the sun can burn stably for a long time.

However, the internal dynamic balance of the sun will be broken after 5 billion years. According to the observations and research of scientists, the brightness of the sun is now one-third higher than that of 4 billion years ago. It is estimated that after 5 billion years, the sun will continue to change. Once the internal dynamic balance is broken, the conditions for the nuclear fusion reaction to take place in the sun will be lost, and the nuclear fusion reaction will stop happening inside the sun. At this time, the sun will expand rapidly and become a red giant star. , then becomes a white dwarf, and finally becomes a black hole, and perishes.