Our galaxy may have 36 active communicating intelligent civilizations, according to research by a team from the University of Nottingham, UK. As per the study, the average distance to the nearest of these civilizations would be 17,000 light-years which makes the detection and communication very difficult with the current technology, according to Advanced Science News.
The research team's approach uses simple assumptions for how life developed, assuming that intelligent life formed in a similar way like that 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,” Advanced Science News quoted team lead Christopher Conselice as saying.
“It is clear that the lifetime of a communicating civilization is the key aspect within this problem, and very long lifetimes are needed for those within the Galaxy to contain even a few possible active contemporary civilizations,” Advanced Science News quoted the study.
The study is based on the Drake equation that predicts the number of communicating civilizations in a given volume of the universe. However, the team makes simple assumptions for how life is formed.
“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. Our new study simplifies these assumptions using new data, giving us a solid estimate of the number of civilizations in our Galaxy,” Advanced Science News quoted Tom Westby, the study’s first author.
The team developed the Astrobiological Copernican Principle to establish weak and strong limits on life in the galaxy. The calculations take into account star formation, their metal content, and the likelihood of stars hosting Earth-like planets in their habitable zones, under specific assumptions, which are based on the one situation in which intelligent, communicative life is known to exist, as per Advanced Science News.
According to the team, this makes it possible to answer important questions, such as what fraction of planets in our galaxy will host life and by what definition. An assumption is that these extraterrestrial civilizations are making their presence known by actively sending out signals but detecting them is a challenge because of the distance.