More accurate calculations of the possible number of extraterrestrial civilizations in the Milky Way have shown that in total up to 36 extraterrestrial civilizations can exist in the Galaxy.
Scientists’ calculations took into account the nature of the chemical evolution of the Universe and the typical rate of development of increasingly complex life forms. The results were published by the Astrophysical Journal.
“Our idea was to use the principles of the theory of evolution on a cosmic scale. We called the results of our calculations the“ astrobiological limit of Copernicus. ”According to them, at least several dozen civilizations should exist in our Galaxy, if each of them takes about five billion years, “said one of the authors of the work, Professor Christopher Conselis, University of Nottingham, UK.
Half a century ago, the American astronomer Frank Drake came up with an equation with which you can calculate the number of extraterrestrial civilizations in our galaxy, as well as estimate the chances of contact with them.
Drake’s calculations showed that there should be a lot of them and that humanity will certainly meet with them. However, the fact that such contacts never happened made many scientists of that time, including the famous physicist Enrico Fermi, doubt the truth of Drake’s assumptions. As a result, the so-called “Fermi paradox” appeared: if there are aliens, then why hasn’t humanity discovered until now any traces of their existence?
Now there is no single answer to this question. In the past, scientists have suggested that the absence of extraterrestrial civilizations can be explained by the unique conditions for the formation of intelligent life that have developed on Earth.
This hypothesis now seems unlikely to scientists after the discovery of many earth-like planets near the stars closest to us. Concelis and his colleagues attempted to resolve the Fermi paradox by approaching it in terms of chemical and biological evolution.
The apparent absence of extraterrestrial civilizations, scientists suggested, can be explained by the fact that the main limiter of their formation may not be specific conditions on individual planets, but the general level of the chemical evolution of the Universe and the rate of development of life.
The fact is that initially the Universe consisted of only three elements – hydrogen, helium and a small amount of lithium. Oxygen, carbon, nitrogen, and other elements that make up proteins and other “life bricks” began to accumulate in it after the first stars were lit and burnt out. In other words, in the Galaxy at the first stages of its development there simply weren’t enough “building materials” that are needed to form planets and “building blocks of life”.
Guided by such an idea, scientists calculated various scenarios of the birth of extraterrestrial civilizations within the Milky Way, based on the knowledge about the evolution of life on Earth that was obtained in recent years.
As a result, Conselis and his colleagues calculated how many civilizations could be in the Galaxy in principle for the entire time of its existence, and also estimated the number of possible “contemporaries” of mankind.
It turned out that from 475 to 928 civilizations could exist in the Milky Way, however, now, as astronomers suggest, their number does not exceed three dozen. The closest of them, according to Conselis and his team, will be at a distance of several thousand light-years from Earth.
If this is true, then this well explains why humanity has not yet been associated with them. On the one hand, our observational instruments cannot pick up radio signals or flashes of light from such a distance. Moreover, the aliens themselves, even if their civilization exists much longer than human, will not suspect our existence, since our radio signals will go to them for several millennia.
If humanity manages to discover such signals in the future, then this will mean, as Conselis concludes, that highly developed technological civilizations, in principle, can exist for a very long time. Many theoretical astrobiologists today doubt this, who explain in this way the absence of visible “extraterrestrial beings.”