Since the beginning of civilization, humanity has wondered whether we are alone in the universe. Obtaining good estimates of the number of conceivable extraterrestrial civilizations has always been challenging.
A new study has taken a new approach to this problem. By assuming that intelligent life forms on other planets as it does on Earth, scientists have obtained an estimate for the number of intelligent communicating civilizations within our galaxy -the Milky Way.
They were able to enumerate that there must be almost 30 active communicating intelligent civilizations in our home Galaxy.
The classic technique for assessing the number of intelligent civilizations depends on making guesses of values relating to life, whereby suppositions about such matters change significantly. This new study streamlines these presumptions utilizing further information, giving a solid estimate of the number of civilizations in our Galaxy.
Professor of Astrophysics at the University of Nottingham, Christopher Conselice, who led the research, explains: “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. The idea is looking at evolution but on a cosmic scale. We call this calculation the Astrobiological Copernican Limit.”
First author Tom Westby explains, “The two Astrobiological Copernican limits are that intelligent life forms in less than 5 billion years, or after about 5 billion years – similar to on Earth where a communicating civilization formed after 4.5 billion years. In the strong criteria, whereby a metal content equal to that of the Sun is needed (the Sun is relatively speaking quite metal-rich), we calculate that there should be around 36 active civilizations in our Galaxy.”
Scientists found that the number of civilizations relies firmly upon to what extent they are effectively conveying signals of their existence into space, for example, radio transmissions from satellites, TV, and so forth. If other technological civilizations last as long as our own, which is currently 100 years old, then there will be around 36 ongoing intelligent technical civilizations throughout our Galaxy.
However, the research shows that the average distance to these civilizations would be 17,000 light-years away. This might be the reason that it is quite challenging to detect them and communicate with them. It is also possible that we are the only civilization within our Galaxy unless the survival times of civilizations like our own are long.
Professor Conselice continues: “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 civilization will last. 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 long-term existence. By searching for extraterrestrial intelligent life — even if we find nothing — we are discovering our future and fate.”
The study is published today in The Astrophysical Journal.