For life on earth, water, oxygen and sufficient sunlight are three essential requirements. Without any of them, life cannot survive and continue. The life of the earth mainly lives on the surface of the earth, which has 71% of the ocean surface and sufficient oxygen. The earth itself occupies two of the three essential elements needed for life, and the other abundant sunlight is not available on the earth itself. We need other sources, and this source is the star sun in the center of the solar system.
The sun played an important role in the birth of life on the earth. Without it, there would be no liquid water, no thick atmosphere, no warm climate, and no life would be born without it. There is the birth of mankind. It can be said that the sun can also be regarded as the mother of life on earth. Perhaps for people in ancient times, they never thought about what would happen if the sun no longer shines and heats up?
Because in the eyes of the ancients, the sun is an eternal fireball, it will not go out, it will always shine on the earth. However, when mankind entered the age of technology, with the help of technology, we learned more about the sun, and then we realized that the sun is just a star, and its life span varies greatly depending on its mass.
The life span of a massive star may be only tens of millions of years, while a yellow dwarf star like the sun has a relatively longer life span, reaching about 10 billion years. Today’s sun has been burning for 5 billion years, half of its life has been completed, and in another 5 billion years, the sun will be completely extinguished, and the earth will no longer be shining at that time.
So someone once brought up an interesting topic: How long does it take for humans to know after the sun goes out? Someone might say, isn’t this a very simple math problem? The earth is about 149.6 million kilometers away from the sun, and the speed of light is 300,000 kilometers per second, and the final calculated time is about 8 minutes and 18 seconds. In other words, after the sun goes out, no more photons will reach the earth after 8 minutes and 18 seconds, and the earth will fall into permanent darkness.
So is this time accurate? After the sun goes out, we will really know after 8 minutes, will we be able to see the coming of eternal darkness? If you think so, you are very wrong. After the sun goes out, the time left for the earth to arrive for eternal darkness is much longer than we thought, and it may take tens of thousands of years. What is going on?
It is actually not difficult to unravel this mystery. First of all, we must understand that the burning of the sun is completely different from ordinary burning. It is a burning mode of nuclear fusion. We can regard the sun as a huge nuclear fusion reaction. The furnace, which is filled with hydrogen and helium, is undergoing nuclear fusion at all times in the center. This is also the source of solar energy.
In the process of generating nuclear fusion, the energy released by the sun every second is equivalent to the sum of 1.8 billion nuclear weapons exploded at the same time. The surface of the sun is in a burning state. In fact, the photons constantly running out of the sun are acting. So how long does it take for the light emitted from the center of the sun to reach the surface of the sun?
Some people may think that the speed of light is so fast that it takes a very short time even from the center of the sun to come to the surface of the sun. Is this really the case? The true answer may make many people feel unbelievable. It is not easy for the photon at the center of the sun to reach the surface of the sun. It takes many obstacles to be able to do it. This is a relatively long process.
The internal structure of the sun is much more complicated than the nuclear fusion reactor we imagined. Because the sun is a huge and very dense plasma ball, the photons produced by deep nuclear fusion reflection often cannot reach the sun’s surface directly. Since the interior is filled with countless electrons, ions, and atoms, photons must compete with these “obstacles” if they want to reach the surface.
When a photon is produced by nuclear fusion, it needs to interact with various substances in the process of continuously moving outwards, and the energy of the photon will continue to be consumed in this process. The photons generated in the center of the sun are powerful gamma rays at the beginning. After reaching the surface, their energy is constantly weakened and finally turned into X-rays.
The process of photons traveling from the inside to the surface is not a straight line. The reason is that it may collide with protons and other particles in the process of walking, thereby changing the direction of travel, so this process is a curved and tortuous process. To complete this series of tortuous processes, it will take at least ten thousand years. If you are unlucky, it may take tens of thousands of years.
Only after the photon reaches the surface from the inside, can it become a wild horse that runs freely in space, and it can take 8 minutes to reach the earth. Therefore, when the nuclear fusion inside the sun ceases to react, that is, the sun’s interior is extinguished and no more photon energy is produced.
Although the sun’s interior is extinguished and no more photons are produced, there will still be a steady stream of photons coming from the sun’s surface, which will last for tens of thousands of years. And we who live on the earth naturally don’t know that the sun has gone out. What we can see is that the sun is still burning and the earth is still shining through the sun.
Until tens of thousands of years later, no more photons inside the sun reach the surface, and after the last photons reach the earth, we can truly usher in eternal darkness. Of course, this is a very ideal state for us. In fact, the earth cannot resist the moment when the surface of the sun really goes out.
With the end of the hydrogen fuel inside the sun, the entire sun will continue to expand, forming a red giant star. The expanding sun will slowly approach the earth, causing the earth’s temperature to continue to rise, the atmosphere is constantly being stripped, liquid water evaporates, and life cannot survive. The whole earth becomes a desolate planet of inferno, and then the expanding sun will completely swallow the whole earth. If you are lucky, maybe there will be a dense metal core left on the earth.
This time may happen in 3 billion years. When the sun’s surface is extinguished, the outer layer of the sun will continue to peel off, the inner core will collapse, and finally it will evolve into a white dwarf. Therefore, the earth cannot wait until 5 billion years later, and humans need to withdraw from the earth during the process of the sun turning into a red giant star.
If at that time, humans still existed and have become a powerful interstellar civilization, then we can leave the solar system and go to other galaxies to survive. If you miss the earth, perhaps you can also transform the earth into a wandering planet and leave the solar system with the earth. Going to a new galaxy to start a new time, it can be seen that the destiny of mankind in the future wants to change, and only science and technology can do it.