New Research on Intelligent Life Within Our Own Galaxy – 30 Active Communicating Civilizations in Milky Way?

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One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.

A new study led by the University of Nottingham and published today (June 15, 2020) in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy — the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home 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.” Conselice also explains that “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 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.

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.”

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