Researchers at the University of Nottingham came to this conclusion using a method called the Astrobiological Copernican limits.
Are there other civilizations like ours in the Universe? This is one of the most intriguing questions since humanity first looked at the night sky. And a new study led by researchers at the University of Nottingham, UK, promises to be another step towards the answer.
The research, published on Monday (15) in the Astrophysical Journal, suggests that more than 30 civilizations with intelligent life may exist in the Milky Way. According to the researchers, this is a huge improvement over other estimates that establish numbers from zero to billions.
To estimate this number, scientists assumed that intelligent life forms on other planets are similar to those on Earth. “There should be at least a few dozen active civilizations in our Galaxy under the assumption that it takes 5 billion years for intelligent life to form on other planets, as on Earth,” said Christopher Conselice, who led the study, in a statement.
As the researchers explain, the method they used considers the theory of natural selection, but on a cosmic scale, and is called the Astrobiological Copernican limits. They also took into account other astronomical aspects, such as the existence of stars close to where these societies would be.
“The classic method for estimating the number of intelligent civilizations relies on making guesses of values relating to life, whereby opinions about such matters vary quite substantially,” said Tom Westby, one of the study’s authors. “Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our Galaxy.”
According to the research, the number of civilizations depends on how long they have been actively sending signals of their existence to space, such as radio broadcasts from satellites and television. According to the scientists, if other technological societies have existed as long as ours, about 36 intelligent civilizations must exist in the Milky Way.
However, the distance between Earth and these worlds would be, on average, 17,000 light-years, which would make detection and communication with our current technology difficult. Furthermore, it is possible that we are the only civilization within the Milky Way that is not yet extinct, for example.
“Our new research suggests that searches for extraterrestrial intelligent civilizations not only reveals the existence of how life forms, but also gives us clues for how long our own civilization will last,” said Conselice. “If we find that intelligent life is common then this would reveal that our civilization could exist for much longer than a few hundred years, alternatively if we find that there are no active civilizations in our Galaxy it is a bad sign for our own long-term existence.”