How long can humans "live" unless there is an accident? Academician of Chinese Academy of Sciences: Life is still about 4.5 billion years.

"The earth is the cradle of mankind", but now, this cradle will become temporary. Because many people think that human beings will leave the cradle sooner or later, just like babies have to learn to grow up. But the question is, when can we leave?

This question depends on two points, the time of the destruction of the earth and the time of the destruction of mankind. No matter which one comes, only leaving is the best ending.

So, how long can humans live on the earth? How long can the earth exist? Where can we go after leaving the earth? Can the interstellar migration plan really succeed? Academician of Chinese Academy of Sciences said that the life span of the earth is still 4.5 billion years. If there are no accidents, how long can we humans "live"?

I'm afraid it's difficult for human beings to answer this question accurately, because it's all in the future anyway, and no one has the ability to predict the future. So scientists can only speculate from two aspects.

The first is energy. As we all know, human beings can't move without coal, oil and natural gas. According to their reserves, we can speculate how long humans can live.

At present, the proven oil reserves can be used by human beings for another 50 years, and it is conservatively estimated that the use limit of oil is between 100-200 years. The natural gas on the earth can be used for about 250 years, but according to the annual increase in natural gas consumption, this use time will be shortened to be similar to that of oil.

Compared with oil and natural gas, coal has a long history of exploitation and utilization by human beings, and the world's coal reserves are only enough to maintain human use for 200 years. In this case, coal, oil and natural gas will basically be used up in 200 years. As a resource for human survival, its exhaustion also indicates that the time for human survival on the earth will be fixed at 200 years. However, who says that human beings can only use these three kinds of energy?

Another criterion for guessing is the level of civilization. The energy of the earth is beyond human imagination. We always feel that there is not enough energy because we can use very little earth energy. How to make good use of one's own planet is an important standard of the first-class civilization in the universe. We humans have not reached it yet, so we are not enough to become a famous civilization in the universe. Kakumichio, a theoretical physicist, once said that human beings will reach the first-class civilization in the universe in 100 years at the latest, and we can make full use of the earth's resources at this time.

In this way, the survival time of human beings on the earth will be closely related to the life of the earth. As long as the earth doesn't explode, we don't have to have a holiday. What is the life geometry of the earth?

Wang Jizhuo, an academician of China Academy of Sciences, once said that the life span of the earth is about 4.5 billion years. Academician Wang didn't just say that. He inferred from the life of the sun.

Although the earth is called the "cradle of life", more than half of the credit comes from the sun. Without the energy of the sun, the earth would not be what it is today. The sun has a history of about 4.6 billion years since its birth. However, at this time, the sun is still a young and middle-aged person, and it is in a burning age. It still has about 4.5 billion years to continue to glow.

At this time, the sun is in its own main sequence star period, and the external hydrogen atoms are undergoing nuclear fusion reaction, producing light and heat, which makes the energy received by the earth continue to be stable. However, all celestial bodies in the universe have a lifetime, and the sun, a star that consumes its own material, can't escape the cycle of fate.

About 4.5 billion years later, the hydrogen atom on the sun ended its own fusion reaction, and then the helium atom participated in the fusion reaction. Their reactions are not as continuous and stable as hydrogen atoms, and the atoms generated will be heavier. The reaction mainly occurs inside the sun, when the inner core will start to shrink and the outer shell will start to expand to balance itself. At this time, the sun has become a red giant and its volume has increased rapidly. Several planets close to it, such as Mercury, Venus and Earth, will be swallowed up by it.

After the earth is swallowed by the sun in the form of a red giant, it will no longer exist in the universe, and it will become a part of the core. Finally, the balance between internal contraction and external expansion of the red giant was broken, and the sun ended its fiery life in a collapse, wandering in the universe in the form of a white dwarf.

Theoretically, during the main sequence of the sun, not only the earth can exist safely, but also the life on it will not be cut off. Throughout history, there have been several mass extinctions on the earth. The most serious one was at the end of Permian 250 million years ago, when 95% of species disappeared, but this still did not cut off the continuation of the tree of life.

Therefore, scientists have come to the theory that the life of the earth is 4.5 billion years. After reaching the first level of civilization in the universe, mankind will move towards a more advanced civilization. Theoretically, it takes about 1000 to 2000 for human beings to move from the first civilization to the second civilization. It takes about 654.38 million+years for civilization to go from the second level to the third level, all within the scope of life on earth.

Leaving the earth seems to have become a certain thing. The question is, where will humans go when they leave the earth?

In 1980s, a super building was built in the desert of Arizona, USA. It simulates the ecological environment of the earth and hopes to replicate another ecological circle, so it was named "Biosphere 2". As a result, the experiment originally planned for two years was forced to end ahead of schedule, and eight scientists who participated in the experiment were finally tortured. The experiment ended in failure.

The failure of "Biosphere II" tells us that the earth's biosphere is unique and we can't leave easily. Even if we go to the universe, our final destination must be a planet similar to the earth. According to the observations and calculations of astronomers, there are about 6 billion Earth-like planets in our galaxy alone. Their structures are similar to those of the earth, and they are all rocky planets. There are four rocky planets in the solar system, namely Mercury, Venus, Earth and Mars, among which the Earth is suitable for survival. According to this probability, the ideal situation is that about a quarter of the 6 billion terrestrial planets are suitable for life, so it is about 65.438+05 billion.

Unfortunately, among the 6 billion Earth-like planets, only about 4,000 have been confirmed by scientists, and the rest are still in a state of missing tails. However, as human beings reach the third level of cosmic civilization, the scope of their homes will expand from the solar system to the Milky Way. At this time, distance is no longer a constraint for human beings to go further. At this time, those super earths in our galaxy are likely to become our new homes.

These are scientists' assumptions and guesses. In fact, human footprints have only reached the moon, and the next step is to go to Mars.

The gap between ideal and reality is sometimes even farther than the distance between celestial bodies. Many people are pessimistic about the interstellar migration plan and think that we can't reach it.

However, many scientists have great enthusiasm. On his deathbed, Hawking predicted that mankind would eventually leave the earth to realize immigration, and the first step to realize this plan is to turn Mars into a place suitable for human habitation. Academician Ouyang Ziyuan, the "father of Chang 'e" and chief engineer of Chinese lunar exploration, said in 2020 that human beings have the ability to transform Mars into a livable planet in the future.

Scientists believe that at the current rate of human development, it will take 200 to 300 years to transform Mars. By then, humans can live on Mars just like they live on the earth without wearing spacesuits. If humans successfully transform Mars, it means that our interstellar migration plan is feasible. We don't have to stick to looking for planets similar to the earth, but we can also look for planets similar to Mars, so the number of available planets has tripled directly.

Take the first step well, and the next road will be overcome one by one.