NOTTINGHAM, United Kingdom – Are we alone in the universe or are there other intelligent civilizations out there? If so, how many of these alien civilizations might exist?
A new study published in The Astrophysical Journal sheds new light on these age-old questions. In the study, University of Nottingham astrophysicists estimate that there could be 36 intelligent civilizations capable of communication within our galaxy, the Milky Way.
Earth as the model for alien civilizations
The scientists say they reached this conclusion by assuming that intelligent life forms on other planets similar to how it formed on Earth. Here, intelligent life formed after 4.5 billion years. Based on this, the researchers assume that intelligent life also forms on other planets after about 5 billion years. Similarly, they believe that intelligent life on other planets requires a metal-rich environment. On Earth, we have the sun, which is quite metal-rich compared to other stars.
“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.” Lead researcher Christopher Conselice explains in a release. “The idea is looking at evolution, but on a cosmic scale. We call this calculation the Astrobiological Copernican Limit.”
However, the researchers also suggest that these alien civilizations are spread uniformly throughout the galaxy. If this is the case, the nearest civilization would be 17,000 light-years away, making interstellar communication extremely difficult, if not impossible. Further, they write that the conditions that give rise to these civilizations are not likely very stable, making it unlikely that these civilizations would survive for very long.
“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,” says Dr. 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. By searching for extraterrestrial intelligent life — even if we find nothing — we are discovering our own future and fate.”
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