This paper takes part in the series essay competition of “great science” of Recordunkown.
The earth is a beautiful planet of life. Before human beings go out of the earth, we don’t know the vastness of the universe, and we don’t know what position the earth is in the universe.
With the continuous progress of human science and technology, we went out of the earth and finally saw the vast universe. At this time, we understand how small the earth is. From the perspective of the universe, it seems that the earth is very ordinary and nothing special. However, with the continuous improvement of observation technology, we have found many planets. Through comparison, we can clearly see that the earth is unique and a very beautiful planet. Maybe this is the characteristic of life planet.
When human beings see the vastness of the universe, nature has a strong interest in the existence of extraterrestrial life. Whether from the perspective of the vastness of the universe or the age of 13.8 billion years of the universe, there is no doubt about the existence of extraterrestrial life. However, scientists have made efforts for more than half a century and still find any trace of extraterrestrial life.
Despite this, scientists still firmly believe that alien life exists, but the solar system has only earth, a beautiful ecological planet, and possibly only earth, a living planet. If we want to find extraterrestrial life, we still need to focus on the sea of stars outside the solar system.
Through the characteristics of the earth as a living planet, we can also find a certain direction for extraterrestrial life. Since the earth became a living planet 3.8 billion years ago, it shows that the earth’s ecological conditions meet the various factors needed for the birth of life. Therefore, it is a very good direction to rely on the earth’s ecological conditions to find extraterrestrial life.
So why is life born on earth? Mainly due to its suitable temperature, suitable atmosphere, air composition and liquid water and so on. The combination of these conditions finally led to the birth of life on earth, and after a long period of evolution, there was the birth of human beings.
There is no second planet in the solar system that is very similar to the earth’s ecology, so we can only look outside the solar system. In order to find earth like planets very similar to the earth, in the 1990s, scientists launched an optical telescope into the earth orbit. I believe many friends know who it is, that is, the famous Hubble telescope.
The launch of the Hubble telescope has extended human vision to the depths of the universe. Recently, it can see 13 billion light-years deep. Through it, we have a deeper understanding of the universe, and let us see what the universe looked like 13 billion years ago. Through it, we have a profound understanding of the evolution of celestial bodies and galaxies in the universe, and the Hubble telescope also takes a huge contribution to the big bang theory.
In the eyes of many people, the universe is dark and empty, but in 2012, NASA released a very deep field image of Hubble. This image is a long time exposure of a very small space (only 1 / 10 of the area of the full moon) by the Hubble telescope.
In our eyes, a small dark and empty starry sky is another scene in the field of vision of Hubble telescope. From the picture, we can see that the whole picture is full of bright stars, which are galaxies like the Milky way. This shows how large the number of celestial bodies and galaxies in the universe is.
There are about 10000 galaxies in this small photo, and the oldest galaxy is 13.2 billion years old. In so many galaxies, there is no lack of earth like planets very similar to earth. However, human observation technology is still not advanced enough. Although the observation is very far away, we can only observe galaxies closer to the earth if we want to get more information about a galaxy.
So far, scientists have discovered more than 4500 exoplanets by using transit method, apparent velocity method, microlens method and other scientific methods. In these planets, scientists focus on those that are very similar to the earth. Only earth like planets that are very similar to the earth are more likely to have life.
Some time ago, in the journal astrobiology, scientists published a paper. The paper shows that scientists have re listed some criteria that a super livable planet should meet, and according to these criteria, they have re screened more than 4500 exoplanets, and found the best 24 candidate planets.
These 24 planets are very similar to the earth in appearance, and they also have a beautiful color. We can judge the ecology of a planet, and we can get a general data by comparing some characteristics of its appearance with that of the earth. The main star of the galaxy where these planets are located is a k-class star, while our sun is a G-class star.
The life span of a class g star is only about 10 billion years. It takes a long time for life to evolve from the primitive stage to the intelligent stage. It takes 3.8 billion years for life on earth to evolve to the birth of human beings, which is actually a relatively short time. If the time is longer, the earth may not be able to wait for the birth of human beings.
Therefore, G-class stars such as the sun are not ideal host stars for the birth and evolution of life. On the contrary, the k-class star is more superior. Its mass is smaller than that of the sun, and its life span can reach 20 billion to 30 billion years, which can support the evolution of life for a longer time. It is more hopeful that intelligent life will be born and developed step by step to become an interstellar civilization.
One of the 24 planets is about 5 to 8 billion years old, much older than the earth. In addition, it has a beautiful ecosystem. Scientists speculate that life may have been born on this planet, and even intelligent civilization may have evolved.
According to the observation and analysis, the surface temperature of this planet is about 3 ℃ higher than that of the earth, which is equivalent to the tropical rain forest area of the earth, and is a very suitable temperature for the survival and evolution of life. From this, we can also think that there is probably liquid water on this planet, and there is also a very thick inner layer and magnetic field.
The atmosphere of this planet has 25% – 30% oxygen level, most of the rest are inert gases, which is very similar to the atmospheric environment of the earth. It is a planet more suitable for human survival than the earth. In addition to this planet which is more suitable for human survival, the other 23 planets are also not bad, probably with life, which may also be more suitable for human survival.
Although these planets let us look forward and hope to migrate one day, we also have to consider two problems. One is that the 24 planets are almost thousands of light-years away from the earth. Although this distance is nothing in the universe, it is an insurmountable gap for human beings.
If human beings want to reach such a distant galaxy, our spaceship needs to fly faster than light. There are only two ways to achieve faster than light. One is wormhole, and the other is curvature engine that scientists have been studying. In the future, the most promising is the curvature engine, which can let the spacecraft break through the space and realize the superluminal shuttle.
Another problem to consider is that these 24 planets may already have intelligent civilization. If so, it is basically impossible for human beings to immigrate, unless they are forcibly occupied by star wars, but the price for human beings will be very high. Moreover, the age of these planets is much older than that of the earth. If life was born much earlier than that of the earth, the strength of civilization may be much stronger than that of human beings.
It can be seen that the discovery of earth like planets similar to the earth is one thing, but the realization of migration may be much more difficult. There are a large number of livable planets in the universe, but such a beautiful ecological environment may also give birth to life and even civilization.
Therefore, even if human beings become interstellar civilization in the future, it is not easy to find a planet that is Ownerless and suitable for human survival.