Written by on June 15, 2020

A major study conducted by the University of Nottingham suggests there could be dozens of ‘active’ alien civilisations in the Milky Way. 

The study used a calculation known as the Astrobiological Copernican Limit to determine how many planets in our galaxy could be home to intelligent alien life, and it turns out we might have more than 30 lots of extra-terrestrial neighbours.

For the purposes of the study, researchers assumed life develops on other planets in a similar way to how it develops on Earth, and that the new species would need to develop in metal-rich environments in the same way humans have done, due to the metal present in the Sun.

Christopher Conselice of the University of Nottingham explained in a press release that it took five billion years for intelligent life to form on Earth.

Therefore, ‘under the assumption that it takes five billion years for intelligent life to form on other planets’, Conselice and the team estimated ‘there should be at least a few dozen active civilizations in our Galaxy’.

Conselice, who led the research, said:

The idea is looking at evolution, but on a cosmic scale. We call this calculation the Astrobiological Copernican Limit.

Tom Westby, first author on the study, which has been published in The Astrophysical Journal, explained:

The two Astrobiological Copernican limits are that intelligent life forms in less than five billion years, or after about five billion years – similar to on Earth where a communicating civilisation 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 civilisations in our Galaxy.

Westby said that while the ‘classic’ method for estimating the number of civilisations relies on making guesses of values relating to life, the new study ‘simplifies these assumptions using new data, giving us a solid estimate of the number of civilisations in our Galaxy’.

The ability to detect other civilisations is strongly dependent on how well we can pick up signals, such as radio transmissions from satellites and television, that are being sent into space.

If these technological civilisations last as long as ours, it is estimated there could be 36 ongoing intelligent civilisations. On the other hand, it’s possible other civilisations do develop, but die out before we can detect them.

Conselice discussed the findings and what they may mean for our own future, saying:

Our new research suggests that searches for extraterrestrial intelligent civilisations not only reveals the existence of how life forms, but also gives us clues for how long our own civilisation will last.

If we find that intelligent life is common then this would reveal that our civilisation could exist for much longer than a few hundred years, alternatively if we find that there are no active civilisations 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.

Though we might be sharing our Galaxy with up to 30 different civilisations, it’s unlikely we’ll be inviting them over for a brew any time soon. The average distance to any possible civilisation is be 17,000 light years, meaning it would be very difficult for us to communicate.


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