Hundreds of years ago, with the help of science and technology, human beings finally realized their dream of flying to the sky, walked out of the earth and saw the vast universe. When we walk out of the earth, we really understand the vastness and smallness. In the eyes of human beings, the universe is vast and the earth is small. With the continuous progress of human science and technology, we are more aware of how vast the universe is, and the earth is not even dust in front of the universe. At most, it can only be regarded as a cell in the organism, so we can see how small the earth is.
When we see the vast universe, a question that many people want to know appears: is there any alien civilization in the universe? In the eyes of most people, alien civilization probably exists. If alien civilization exists in the universe, then why does human beings not encounter alien civilization? Scientists have come up with five possible answers.
1、 Alien civilizations have long discovered human beings and observed them in the dark. We all know that the universe was born 13.8 billion years ago. In such a long time, countless planets were born in different periods of time. If some planets are older than the ancient earth, then the development time of the intelligent civilization born on them is far longer than that of human beings, and it may have become a powerful interstellar civilization that can cross the interstellar navigation.
For the interstellar civilization, the distance between the universe is no longer an insurmountable gap, they can quickly reach the distant interstellar space. It is possible that alien civilizations have inadvertently observed the existence of the earth, and have come to the earth through wormholes or other superluminal ways to discover the existence of human beings.
Alien intelligence civilization is very rare for human beings, but it must not be rare for interstellar civilization. In their long exploration, they found a large number of all kinds of intelligent civilization, so human beings are nothing in the eyes of alien civilization. In addition, human science and technology are so backward that they can’t attract the interest of alien civilization at all, so they don’t want to contact with human beings, they just observe in the dark. Perhaps in the eyes of powerful alien civilizations, life on earth and human beings are just their objects of observation and research, while the earth is just a biological laboratory in their eyes.
2、 We all know that the universe is so vast that we can’t imagine it. The distance in the universe is based on light years, the distance between stars is more than several light years, and the distance between large galaxies can reach more than millions of light years.
Therefore, in order to realize the exploration between galaxies in the universe, the speed of the spaceship must exceed the speed of light. Some people may say that the speed of light can also go out of the parent galaxy and explore nearby galaxies. This is true. But in fact, even if humans achieve the speed of light, the scope of our exploration is very limited, and within the limited scope, the possibility of discovering alien civilization is very small.
Only by flying faster than the speed of light can we cross the galaxy and explore the possible alien civilization in the galaxy. However, it’s not easy to achieve superluminal flight. In the current scientific system of human beings, the speed of light is the limit of the speed of an object. Even photons can only reach the speed of light, but cannot break through the speed of light.
In the future, it will take many years for human beings to realize the sub light speed flight which is infinitely close to the speed of light. Let alone the more distant science fiction super speed of light flight, we can find many earth like planets very similar to the earth through astronomical telescope observation, and suspect that there may be life on these planets, or even intelligent civilization.
However, due to the speed limit, there is no interstellar navigation ability and can not reach. This is true for humans, and it may also be true for alien civilizations. For example, in the nearest neighboring galaxy to the earth, if there is intelligent civilization in this galaxy, they may be able to observe the existence of the earth and guess that there may be civilization on the earth. But without the ability of interstellar navigation, we can only look at the ball and sigh.
Therefore, there may be many living planets in the universe, but we can’t be too far away from our parent star. We can only move in the parent galaxy and can’t go out. Naturally, we can’t meet in interstellar space.
3、 Human beings are the most developed civilization in the universe. Some people may think that the universe is so big that it is 13.8 billion years old, while the earth is only 4.6 billion years old, and the birth of human beings is only millions of years old. How can human beings be the most developed civilization in the universe?
But if we think about it carefully, this possibility is not entirely absent. Although the age of the universe is 13.8 billion years old, it is not long for the universe to become a stable space and satisfy the birth of life. According to the research guess of scientists, after the big bang, it is a very long process from the initial basic elements to the formation of matter, matter to nebula, and then nebula to form stars and planets.
This long process may last for billions of years. After the formation of these celestial bodies, the universe may not be really stable. It will take billions of years for the universe to be truly stable. Then the universe will have the conditions for the birth of life. And this time is likely to last as long as 8 billion years. That is to say, the universe may also have the conditions for the birth of life 5.8 billion years ago, when the solar system may still be in its formative stage.
Therefore, the birth time of the life planet in the universe may not be earlier than that of the earth, and we have experienced all kinds of hardships from the birth of life on the earth to the later evolution, and then to the birth of human beings. I don’t know how many times we have experienced large and small mass extinctions. Life on earth was finally born 4 billion years ago.
It can be seen that the emergence of any intelligent civilization is not an easy thing, and it needs all kinds of efforts and luck to be able to do so. The earth is like this, and so will other living planets. Nature will not simply let a civilization come into being, but will have to go through all kinds of hardships. In all kinds of tribulations, carelessness will make life fall down and start again.
Therefore, although the birth time of other living planets in the universe may be much earlier than that of the earth, they may not be as lucky as the life on the earth. They can continue to evolve through five mass extinctions and complete the pace towards intelligent life. It is possible that other living planets experienced several times of life overthrow and comeback before finally giving birth to intelligent life. At this time, human beings may have formed civilization. Therefore, it is not impossible for human beings to be the most powerful civilization in the universe.
4、 The earth is the only civilized planet. As we said above, the life planet needs to go through all kinds of tests of nature to complete a series of evolution. It is very difficult to survive. Luck accounts for a large part of the life on earth. It is precisely because the lucky index of life on earth is high enough that after the mass extinction, a little life can survive and continue to evolve.
Life on earth can have such a high lucky index, but other living planets in the universe may not be so lucky. They may not survive the test of nature and eventually become desolate planets like Mars. Lost the right to continue to evolve. Even if some living planets are not completely desolate and life continues to evolve, it may take a long time to become a civilized planet like the earth.
Therefore, it is possible to analyze the difficulty of upgrading from a living planet to a civilized planet, that is, the earth is the only civilized planet in the universe. Of course, these are just our conjectures. In order to understand whether there are other intelligent civilizations in the universe, apart from the alien civilizations coming to the earth to contact with human beings, we can only rely on science and technology. Only when we become a powerful interstellar civilization and have the ability of interstellar travel can we travel to the stars and explore the vast universe.
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