American astronomers have calculated different scenarios for the emergence of alien civilizations and came to the conclusion that they must be extremely rare, but at the same time capable of establishing contact with a person from anywhere in the Galaxy, says an article published in the arXiv.org electronic library.
“In May 1961, President Kennedy announced that the United States would send people to the moon and bring them back in the next 10 years. This dream came true in July 1969, filling one of the most important pages in the history of space exploration. In this regard, it is very difficult to believe that nothing like this has happened in other parts of the universe. And that's why we think for a very long time about how Enrico Fermi said - where did all these aliens go? - written by Jorge Soriano and his colleagues at the City University of New York (USA).
More than half a century ago, American astronomer Frank Drake developed a formula to calculate the number of civilizations in the galaxy with which contact is possible, trying to estimate the chances of discovering extraterrestrial intelligence and life.
Physicist Enrico Fermi, in response to a rather high assessment of the chances of interplanetary contact using Drake's formula, formulated the thesis, which is now known as the Fermi paradox: if there are so many alien civilizations, then why does humanity not observe any traces of them? Scientists have tried to solve this paradox in many ways, the most popular of which is the "unique Earth" hypothesis.
She says that for the emergence of intelligent beings, unique conditions are necessary, in fact, a complete copy of our planet. Other astronomers believe that we cannot contact aliens because galactic civilizations are either disappearing too quickly for us to notice them, or because they are actively hiding their existence from humanity.
Soriano and his colleagues decided to find out why we have not yet encountered brothers in mind, and calculated various options for their evolution and time of existence.
In these calculations, the scientists relied on two simple things. Firstly, not all inhabited planets can become a haven for intelligent life, and secondly, their average lifetime can vary greatly depending on the frequency of gamma-ray bursts, supernova explosions and other galactic cataclysms that can destroy life on a single planet. …
Guided by these ideas, scientists tried to reconcile the Fermi paradox and Drake's formula by calculating scenarios for the existence of aliens that would correspond to both ideas. To do this, the researchers added two new parameters to Drake's formula - the proportion of "intelligent" civilizations that have means of interstellar communication, and the time of their existence.
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Calculations show that intelligent, but invisible to us, alien civilizations really could or can exist in our Galaxy, but their share among the total number of intelligent aliens will be extremely small - about 0.5%. This makes it much more difficult to find them and explains why we do not see them today.
At the same time, the lifetime of civilizations can be quite long - about 300 thousand years. Therefore, in principle, they could establish contact with humanity from anywhere in the galaxy, if they knew about its existence. The search for their traces, according to Soriano and his colleagues, will be possible only in the future, when the heirs of modern NASA space telescopes will discover a greater number of Earth "twins" and full-fledged analogues of our planet.