Why can't humans find alien life?
Does aliens exist? Do they have the same material composition as humans? Where do they live now? The question about alien life is the biggest and most tempting mystery in the process of human exploration of the universe.
At the same time, this puzzle has always plagued humans. What makes us unable to figure out is why we have not found aliens, or why have they not visited the earth?
This is the main idea of the famous Fermi Paradox. So what is a paradox? A paradox refers to a situation where the result of a correct theory is contrary to the facts.
According to all the scientific theories currently mastered by mankind, we can draw such a reasoning conclusion:
Alien life, even intelligent alien life, they are everywhere in the universe, even in the Milky Way, and their technology is much more advanced than human beings, they are already capable of interstellar travel and have colonized the entire galaxy;
So we should be full of aliens around us. But what about the fact? Not only have we never seen aliens, we have not even found a little evidence of their existence.
Why does our theory tell us that the galaxy is full of aliens? And they are more advanced than us?
First of all, we have to admit that the scientific theories currently mastered by human beings are applicable to all parts of the universe, then it is not difficult for us to see that our sun is just an ordinary G-class star in the Milky Way;
Among the 400 billion stars in the Milky Way, the number of stars like the sun accounts for about 8%, which is tens of billions.
According to our research and discovery of exoplanets in recent years, NASA issued a statement that among sun-like stars, at least 7% of stars have a habitable planet, just like the Earth.;
A more optimistic estimate, this ratio can reach 75%, which means that there are 2.2 billion to 24 billion habitable planets in the Milky Way alone, and its parent star is still a sun-like star.
In addition to the habitable environment, we have not only discovered all the elements necessary for life in the universe, but also in the interstellar medium of the universe, the gas cloud that forms stars, and the gas debris that erupts after the death of stars.In addition to chemical molecules, even complex organic chemical molecules.
The above findings make it hard for us to believe that human beings are lonely in the universe. In addition to sun-like stars, there are also planets around other types of stars, and there are also habitable terrestrial planets.
So, the theory tells us that aliens are everywhere.
The next question is, why must aliens be more advanced than us?
The reason is very simple. Humans appeared too late. It takes only 4 to 5 million years for humans to appear today. This is like a blink of an eye to the universe.
Not only human beings, the earth and even the solar system appeared relatively late. The age of the earth is only 4.5 billion years old, accounting for 1/3 of the age of the universe.
The reason for the late appearance of the solar system is that it is outside the third ring of the Milky Way, that is, the suburbs, about 25,000 light-years from the center of the Milky Way, where the material density and gravitational activity are relatively weak, so the star formation speed is slow, andThe formed stars are relatively small in mass and have a long lifespan, so the speed of the heavy element-rich interstellar medium is also slow, so the solar system appeared relatively late.
But the closer it is to the center of the Milky Way galaxy, the difference is different. The original matter here is denser and gravitational fluctuations are stronger, so the formation of stars is fast, massive, and short-lived. They can die quickly and give birth to the next generation of stars;
So in the central area of the Milky Way, the speed and number of second-generation or third-generation stars similar to the sun are also much higher. Of course, rocky planets like the Earth also appeared very early and in numbermany.
If life appeared on them, their evolution would be hundreds of millions, billions of years earlier than the earth. Therefore, we believe that aliens are more advanced than us, and they have the ability to colonize the entire galaxy.
Then the question is coming? If our theory is correct, why did we not find aliens?
The explanation of this question is actually the explanation of Fermi's paradox, including some theories:
Life is rare:
Maybe we have always overestimated the birth of life, and the probability of the emergence of life is very, very low, to a heinously low level;
Even if there are many building blocks for the birth of life in the universe, there are habitable planets with the birth of life, but because the emergence of life is a very accidental and ultra-low probability event, there is still very little life in the galaxy.
Even if there is life, it is even more impossible for them to evolve intelligent life like human beings. That is to say: we humans are completely miracles among miracles. We cannot expect such miracles to happen in other places in the universe.
Dark Forest Theory
Everyone has heard about this, saying that there are indeed intelligent life in the universe, and there are many more, but they all hide themselves from other civilizations.
Like lone hunters wandering in the dark forest, if they expose their existence and location, they will be wiped out by other civilizations.
This statement is a bit sci-fi.
Limits of the laws of the universe
Intelligent life is indeed widespread, but the vastness of the universe makes the gap between intelligent life insurmountable, and all life is always restricted in its own star system and cannot escape.
No one has the ability to discover who, just like human beings are trapped in the solar system now, an event of at least 30,000 years to fly out, an event of at least 70,000 years to the nearest neighboring star, this is for humansIt is simply an invisible cage.
The development of smart life to a certain extent will be due to the exhaustion of resources, the deterioration of the living environment, and the technology reaching a certain bottleneck. It will eventually lead to extinction, or the technological civilization itself is destructive, and the future will be in itself due to energyThe war broke out and caused the extinction of civilization.
This is indeed very possible. Looking at the development of mankind, it is not difficult to see the dilemma we are facing now. The development of human science and technology is only a short period of hundreds of years, but the earth’s environment has begun to worsen and we are nowProtecting the environment can only delay this process;
In addition to environmental issues, there are also resource issues. The earth's resources will definitely be exhausted, so anyway, we humans need to find a second home, but where is this home? I don’t know yet.
Civilization development will always face various problems. If certain problems cannot be solved and no breakthroughs are made in technology, civilization will definitely be extinct.
Then which one do you believe is the reason why we did not find alien life?
Recently, scientists published a paper in "arxiv", and their view supports the last big filter.
Researchers pointed out that low-level single-celled life appeared only 1 billion years after the birth of the earth, and it took more than 3 billion years of evolution for humans to appear. If the process of intelligent life appears similar to humans;
Then intelligent life in the Milky Way first appeared in the 8 billion years after the birth of the Milky Way, which is about 8.5 billion years after the birth of the universe. Most of them are concentrated in the area near the center of the Milky Way, which is within the range of 13,000 light years.
It can be seen that the earliest extraterrestrial intelligent life appeared nearly 5 billion years earlier than human beings, or when the solar system was still a dust cloud, advanced intelligent life has evolved in the galaxy.
And during these 5 billion years, intelligent life in the galaxy blossomed everywhere, but in the end they all became extinct due to various reasons. These reasons include: resource depletion, war, technological bottleneck, parent star death and other possible factors.
So when humans appeared, the galaxy had become very quiet, and there were extinct aliens everywhere, so we have not found higher intelligent life, nor have they visited us.
And the intelligent life that may exist in the galaxy now has gone through the extinction one after another. They may still be in the development stage, and are comparable to human technology, so they can't communicate with each other..
If the above guess is correct, then humans may not be able to escape the sanctions of the "big filter" and eventually become extinct after the development of science and technology to a certain extent.
And intelligent life will continue to evolve in the galaxy, they also trouble why no higher life visits them?
In the end, they will also discover that the original higher life will eventually be extinct, and their ending will be the same. Life is so repeated, in short, no one can find anyone, no one can achieve interstellar travel, or even colonize the entire galaxy.
This is why we did not find aliens, and why aliens did not visit us, because they were all extinct before they could visit us.
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