In ancient times, human beings were full of all kinds of fantasies about the starry sky, but due to the lack of scientific knowledge of ancient humans, in addition to curiosity about the starry sky, it was more awe and fear.
It is not until mankind embarked on the road of science and technology hundreds of years ago, with the guidance of science and technology, we have a new understanding of the starry sky, and the awe and fear in our hearts are also fading a little.
After hundreds of years of scientific and technological development, today's human beings have stepped out of the earth and seen a relatively real vast universe, and with the assistance of astronomical telescopes, we can also roughly observe some mysteries of the universe.
With the continuous unveiling of the mystery of the universe, human beings have a further understanding of the universe, and a topic that cannot be bypassed is constantly being valued, that is, the doubt about the existence of alien civilizations.
Do alien civilizations exist? It is estimated that no one can give an answer to this question, but when we understand the vastness of the universe, few people will doubt it. How big is the universe? The current observable universe for humans is about 93 billion light-years, and there are at least trillions of galaxies like the Milky Way in this range.
There are at least hundreds of billions of stars in every galaxy, and basically every star is surrounded by several planets orbiting it. Excluding planets that are not suitable for human habitation, the number of planets suitable for human habitation in the entire observable universe is at least one trillion, which means that life may not be rare in the universe.
If there is a lot of life in the universe, why hasn't mankind discovered anything until now? Scientists believe that the search for extraterrestrial intelligent life is far more difficult than we thought, especially a situation we have to guard against.
As early as more than half a century ago, scientists formulated an extraterrestrial life search plan, scientists search for Earth-like planets similar to Earth through astronomical telescopes, and search for possible extraterrestrial civilization signals in the universe through radio telescopes.
In addition to searching for traces of alien civilizations, humans also actively send their own radio signals to the depths of the universe, hoping to be received by alien civilizations. After much effort, until now, we have not received any rewards, traces of alien civilizations have not been found, and the signals sent by humans have not been responded to.
But even so, scientists have not given up hope and have been working the road of searching for extraterrestrial civilizations. In the eyes of scientists, the existence of extraterrestrial civilizations is not doubtful, and the main reason why humans cannot be discovered is that human science and technology are still very backward, and the scope of effective search is very small.
Although our observable universe ranges to 93 billion light-years, the range that can actually be searched further is very narrow, and scientists have calculated that the 30,000 light-years range centered on Earth is a relatively dense region of stars in the Milky Way, and in this region, the possibility of alien civilizations is very high, and humans have only searched for areas equivalent to dust in this range.
If the range of 30,000 light-years is reduced to the size of Earth, the area currently searched by humans is only equivalent to an area of about 5 centimeters. And we want to search for a larger range, only by constantly striving to develop science and technology and create more advanced observation tools, so that both the search range and accuracy can be greatly improved.
Human beings are currently actively searching for traces of alien civilizations, which is tantamount to finding a needle in a haystack, the difficulty can be imagined, and if you want to find an alien civilization, perhaps more or more of a luck component is needed.
Some scientists have abandoned this path of finding a vain "needle" in the sea, and instead turned to research and explore why alien civilizations do not actively contact human beings. Some scientists believe that we only need to be sure that there is a needle in the sea, and more importantly, we still have to think about the attitude of alien civilizations to humans.
Human technology has only developed for less than 300 years so far, and the universe has been born for 13.8 billion years. According to the research of scientists, 800 million years after the Big Bang, the universe stabilized and had the conditions for the birth and evolution of life.
Therefore, in theory, it is not unusual for civilizations in the universe to exist hundreds of millions of years more advanced than humans. If there is a wise civilization, the strength of science and technology is tens of thousands of years more advanced than that of human beings, their strength is beyond our imagination, and it is difficult for us to understand what kind of means they have.
For a powerful cosmic civilization, it does not seem too difficult to find that the Earth came to the solar system to contact humans. But the strange thing is that human civilization has been formed for about 5,000 years, and there is no conclusive evidence to prove that there are alien civilizations that have come into contact with humans.
Especially in the hundreds of years since the era of technology, although there are many UFOs, it is still unknown whether they are related to extraterrestrial civilizations. The advanced civilizations have the ability to contact and communicate with humans, but why didn't they do this? At this time, some people thought of a very frightening possibility, that is, a hypothesis used to explain the Fermi paradox, the laboratory hypothesis.
The laboratory hypothesis holds that the Earth, and indeed the entire solar system, may be a laboratory of an advanced civilization, and humans are the guinea pigs in this laboratory.
In some remote areas of the earth, there are some human beings who still maintain the primitive civilization of the Stone Age, and scientists have discovered this civilization and have not bothered them, but have observed and studied the environment in which they live and the behavior of primitive people through satellites and various observation devices.
The primitive humans living on the island have not found anything, and the area where they live has become a laboratory for humans, which is the huge gap brought about by technology. If the alien civilization is much more advanced than humans, then it has the full strength to designate an area in the universe as a laboratory to observe the development of a certain intelligent civilization in this laboratory.
Humans are in this laboratory, and due to the huge gap in technology, it is also difficult for us to find observation devices set up by extraterrestrial civilizations in the solar system or outside the solar system. And this situation is the last thing humans want to see at present, after all, no one wants to be a guinea pig in the laboratory.
Of course, these are still only hypotheses, human beings can not search for alien civilizations, the most important thing is that the scientific and technological strength is not strong enough, if humans have the ability to go out of the solar system for interstellar navigation, then the probability of finding alien civilizations will be much higher, of course, provided that there is an alien civilization in the Milky Way.