The question of whether we are alone in the Universe has been haunted by the representatives of the human race for decades. Each time, peering into the night sky, we hope that someone will notice us and our deafening loneliness will finally come to an end. But what if we are the last? What if all the civilizations that theoretically inhabit the Milky Way died long ago? No matter how sad this scenario may seem to us, we cannot completely exclude it. So, according to the results of a study conducted by employees of the California Institute of Technology, our Galaxy may be full of dead civilizations. The authors of the scientific work used the extended Frank Drake equation, which determines the chances of the existence of extraterrestrial intelligence in the Milky Way. In general, researchers have come to the conclusion that intelligent life forms in the vastness of the Universe are prone to self-destruction. But why?
Who lives in the Milky Way?
The very idea that there is no one else in the observable universe except us is frightening. The billions of galaxies, stars and planets that astronomers observe with increasingly powerful telescopes appear uninhabited from Earth. Meanwhile, quite recently, a team of astronomers from the University of Nottingham in England calculated that our galaxy must have at least 36 intelligent civilizations capable of communicating with us.
English astronomers proceeded from the assumption that intelligent life appears on other inhabited terrestrial planets approximately 4, 5-5, 5 billion years after their formation. You can read more about this work here.
The eminent astronomer and popularizer of science Carl Sagan believed that the emergence of life on planets should be a cosmic inevitability, and the number of alien civilizations in the Universe could range from “a miserable few to millions”. Using the famous Drake equation, designed to determine the possible number of intelligent civilizations in the vastness of the Milky Way, Sagan came to the conclusion that a very small number of civilizations are able to avoid self-destruction.
Another difficulty in the search for aliens is that all our assumptions about the development of life are based on a single example - life on Earth.
According to Livescience, a team of researchers from the California Institute of Technology, NASA's Jet Propulsion Laboratory and Santiago High School seem to agree with Sagan's conclusions about the propensity of intelligent civilizations to self-destruct.
In the course of work, which has not yet been peer reviewed and published on the AirXiv preprint server, the scientists used an extended version of the Drake equation, written by the prominent astronomer back in 1961. The study took into account factors such as the rate at which stars appear, the number of planets, and the proportion of planets on which life develops. Note that the Drake equation was originally designed not to calculate an exact number, but rather to stimulate a debate about how many extraterrestrial civilizations might exist nearby.
According to the mathematical model used by scientists in their work, alien civilizations could appear in the Milky Way about 8 billion years after the formation of the galaxy. Models also predict that some of these civilizations may have been 13,000 light-years from the center of the Galaxy, which is about 12,000 light-years closer than the Earth, where you and I are believed to have appeared 13.5 billion years later. after the formation of the Milky Way.
There is a high probability that intelligent civilizations are destroying themselves before they devise a way to travel across the universe.
Interestingly, astronomers came to their conclusions after considering a number of factors that are often overlooked - for example, abiogenesis - a process that is the creation of organic molecules by forces other than living organisms, as well as different evolutionary time frames and the likelihood of potential self-destruction. The authors also considered a number of factors presumably influencing the development of intelligent life - the predominance of sun-like stars around which Earth-like planets revolve; the frequency of supernova explosions; the probability and time required for the development of intelligent life.
However, the new study differs in that the researchers focused mainly on the factors that can lead a civilization to inevitable death. These include exposure to radiation, a sudden pause in evolution, and a tendency to self-destruct through climate change, technological progress, or war. It also follows that any existing alien civilizations are most likely very young, since self-destruction usually occurs after a long period of the existence and development of a civilization.
Even if the galaxy reached its civilization peak more than 5 billion years ago, most of the civilizations that existed then, most likely, self-destructed, researchers discovered.
Perhaps we are still alone, because alien civilizations in the Milky Way died long ago.
All in all, a team of researchers from California Institute of Technology, NASA's Jet Propulsion Laboratory, and Santiago High School gives a grim answer to the question posed by the Italian physicist and one of the founding fathers of the nuclear bomb, Enrico Fermi, "where is everyone?" The authors of the scientific work believe that all intelligent civilizations that exist in the Milky Way may have already destroyed themselves. The results obtained, I must say, look convincing - after all, the Universe is inconceivably huge, and we still have not found any signs that intelligent living beings exist anywhere else besides the Earth.