Lead
"Where are we?" was suddenly asked by the American scientist Fermi during a chat with a colleague, but this simple question was almost unanswered.
In fact, the American astronomer Carl Sagan and his colleagues also thought about this question, but came to a very incredible conclusion, that is, "we are probably the only intelligent beings".
Since ancient times, human beings have been full of curiosity about the exploration of space and extraterrestrial life, and with the advancement of science and technology, human exploration of extraterrestrial life has become deeper and more probable.
But Fermi's question is always there, so are humans really lonely intelligent beings?
If not, then why haven't humans discovered other intelligent life?
Robin, an American astronomer, put forward the theory of the Great Filter, believing that intelligent life must go through an obstacle, and this obstacle is the filter, which is why human beings have not discovered other intelligent life.
So what exactly is a filter?
Humans have been trying to break through the filter, so does this filter really exist?
Some people think that the filter is an unknown obstacle, and some people think that the filter is human beings themselves.
So how do humans break through the filter?
1. The Fermi paradox.
The Fermi paradox is a paradox about the existence of extraterrestrial life first proposed by the American scientist Fermi in 1950, which refers to the fact that the existence of extraterrestrial civilizations is very reasonable from the perspective of our current technology and life evolution, but from another point of view, it is difficult to prove the existence of extraterrestrial civilizations.
To put it more bluntly, it is very likely that extraterrestrial civilizations exist, but there is no evidence that extraterrestrial civilizations do exist.
This situation is like someone telling you tomorrow's lottery numbers in advance, but you have no way to verify this thing, then you can't judge the authenticity of this thing.
Fermi believes that in our galaxy, there are billions of sun-like stars, and these stars were born earlier than the sun, so there are many planets among them, and these planets may also give birth to life.
On these planets, there may not be life like Earth's organisms, but some intelligent life similar to ours can be born.
In this way, there will be many extraterrestrial civilizations, but why haven't we found any extraterrestrial civilizations yet?
Fermi gave two explanations, one is that the alien civilization never appeared, and the other is that the alien civilization is extinct.
It has been suggested that, judging from the evolution of the earth's civilization, intelligent life will not exist for a long time, so this explanation is somewhat possible.
However, the evolution of life on Earth has also taken hundreds of millions of years, so on a longer time scale, it is still possible that there is still intelligent life.
In Fermi's second explanation, it is believed that extraterrestrial civilizations may have self-exterminated without coming into contact with other interstellar civilizations.
This situation is more likely, because no one knows what an alien civilization is like, so it can only be guessed about the existence of an alien civilization.
In addition, there are some people who believe that this is because the alien civilization is too far away from us in space coordinates, so we have not discovered the existence of extraterrestrial civilization.
But this explanation is also not valid, because some simple data analysis can be used to prove that extraterrestrial civilizations will definitely reach the earth, but from the perspective of no human history, there has never been an invasion of extraterrestrial civilizations on earth.
Fermi also pointed out that the development of extraterrestrial civilizations may be faster than our evolution, so at this time, extraterrestrial civilizations established colonies on Earth, but there is no evidence that there are colonies of extraterrestrial civilizations on Earth.
2. The Great Filter Theory.
In the Fermi paradox, there is a situation in which humans have never discovered extraterrestrial civilizations, and this situation is the basic content of the Great Filter Theory.
The American astronomer Robin first proposed the Great Filter Theory in 1996, arguing that intelligent life must go through obstacles, which he also called filters.
This filter may be a natural law that we don't know yet, which makes it very mysterious, like life on our planet, which has experienced many rounds of mass extinctions.
One of these was the Ker-Pi III mass extinction event, which wiped out about 75 per cent of terrestrial species and 96 per cent of marine life.
It was this mass extinction event that brought about a dramatic change in life on Earth, which is why Robin called the Great Filter to exist in the laws of nature.
In addition, there is also a possibility that the form of filter exists in the process of planet birth, because in the process of planet birth, countless meteorites will hit the surface of the planet, which will make the environment on the planet's surface very harsh, which will greatly limit the birth of life.
There is also a possibility that the filter exists in the evolution of intelligent life, because in the process of evolution, intelligent life will develop some technology, which may cause catastrophe to intelligent life.
This technology is like a nuclear weapon, and if some countries accidentally press the start button of a nuclear weapon, it could trigger a very tragic world war, which could lead to the extinction of intelligent life.
There is also a possibility that the filter may exist in the process of our observation of extraterrestrial civilizations, that is, the big filter is in the process of our exploration of extraterrestrial life, so it makes sense that we have not yet discovered extraterrestrial civilizations.
If this is the case, then humanity must find a way to break through this filter, and only then can the existence of extraterrestrial civilizations be found.
3. Explore the existence of extraterrestrial civilizations.
In the past 100 years, human exploration of extraterrestrial life has never stopped, and many scientists have made great efforts to explore extraterrestrial life.
In 1960, American astronomer Drake proposed the Drake equation, which is mainly used to determine how many beings in the universe have the ability to transmit radio.
This equation is based on the "law of large numbers", and after calculating from this equation, it can be found that there are millions of planets in the universe with radio transmission capabilities.
There is a planet with radio transmission capabilities, which generally only emits for about 100 years, which greatly reduces the number of interstellar civilizations that humans will discover.
However, the transmission channels of these extraterrestrial civilizations may not only be radio, but also some other interstellar signals, such as twinkling starlight, etc., which will continue to be emitted until the interstellar civilization disappears.
Human beings have also formulated the "Search for Intelligent Life Plan", mainly to find the existence of intelligent life in the universe, but so far, this plan has not yielded anything.
Human beings have also searched for extraterrestrial civilizations through the Bell experiment, but there has been no gain, and human exploration of extraterrestrial life has always been carried out in their own planetary systems, and they are all through some simple detection methods to find traces of extraterrestrial life.
These methods have the potential to cover up the trail of extraterrestrial life, so humanity has not been able to find extraterrestrial life.
Therefore, human beings still have a long way to go on the road of exploring extraterrestrial life, and only by continuously deepening their understanding of extraterrestrial life can we find the existence of extraterrestrial life.
epilogue
In the exploration of the universe, human beings may be lonely existences, or they may coexist with other lifeforms, and either outcome is a challenge to human beings.
Therefore, on the road of exploring extraterrestrial life, human beings should also consider how to protect their home and not cause any harm to the earth.