Half a century ago, American astronomer Frank Drake came up with the equation, which you can use to calculate the number of extraterrestrial civilizations in our Galaxy, as well as to assess the chances of contact with them. Drake’s calculations showed that there should be very many and that humanity will certainly meet with them.

However, the fact that such contact was not made many scientists, including famous physicist Enrico Fermi, to doubt the truth of the assumptions of the Drake. The result is a so-called “Fermi paradox”: if there are aliens, then why is humanity still did not reveal any traces of their existence?

Now this question has no definite answer. In the past, scientists assumed that the absence of extraterrestrial civilizations can be explained by the unique conditions for the formation of intelligent life that has evolved on Earth. This hypothesis now seems unlikely scientists after the discovery of many earth-like planets closest to us stars.

Evolution of extraterrestrial life

Consoles and his colleagues tried to resolve the “Fermi paradox” came to him from the point of view of chemical and biological evolution. The apparent absence of extraterrestrial civilizations, scientists have assumed, can be explained by the fact that the main limiting factor of their formation there may be no specific conditions on the individual planets, and the overall chemical evolution of the Universe and the speed of development of life.

The fact that initially the universe consisted only of three elements – hydrogen, helium and a small amount of lithium. Oxygen, carbon, nitrogen and other elements from which proteins and other “building blocks of life”, began to accumulate in it after ignited and burned first. In other words, in the Galaxy in the first stages of its development just didn’t have enough “building materials”, which are necessary for the formation of planets and the “bricks of life”.

Guided by this idea, scientists have calculated various scenarios of birth of extraterrestrial civilizations within the milky Way, based on knowledge about the evolution of life on Earth, which were obtained in recent years. As a result of Consoles and his colleagues have calculated how many civilizations could be in the Galaxy, in principle, for all time of its existence, and also estimated the number of possible “contemporaries” of humanity.

It turned out that only in the milky Way could be from 475 to 928 civilizations, but now, as suggested by the astronomers, their number does not exceed three dozen. The nearest of them, according to Conselice and his team, will be at a distance of several thousand light-years from Earth.

If this is true, it well explains why humanity has still not contacted them. On the one hand, our observation devices can not catch the radio signals or flashes of light from this distance. While the aliens themselves, even if their civilization has existed for much longer a human will not suspect about our existence, as our radio signals will go to them for a few millennia.

If humanity will be able to access such signals in the future, it will mean, as it concludes Consoles that advanced technological civilization can exist for a very long time. Today I doubt many astrobiologists-researchers who explain in a similar way, the absence of visible “brothers on reason” in the nearby space and predicted a similar fate of earth civilization.