Scientists reckon they know how many alien civilisations exist in our galaxy

The Milky Way rising behind Radio Telescope Observatory (Ferran Traite/Getty Images)

Astrophysicists have come up with the number of intelligent alien civilisations that could exist in our galaxy.

It’s not some incomprehensible number or complicated equation – it’s 36. The answer is 36.

Apparently, we should be looking to make contact with 36 other intelligent species out there in the Milky Way.

The number comes from a study by the University of Nottingham that assumes intelligent life would evolve on other planets the same way it did here. That means, it has to be on a planet that’s within the habitable zone of its star and the age of said planet needs to be between 4.5 and 5.5 billion years old.

It’s worth pointing out the team define intelligent life as being able to broadcast radio signals into space, like us. There’s even an acronym for it: CETI or Communicating Extra-Terrestrial Intelligent civilisations.

Professor Christopher Conselice, an astrophysicist at Nottingham and the lead researcher on the study, explained: ‘There should be at least a few dozen active civilisations in our galaxy under the assumption that it takes five 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,’ he said.

Alien civilisations would likely evolve similarly to life on Earth (Photo by European Southern Observatory via Getty Images)

While 36 is a pretty slim number, given the size of the Milky Way, it’s actually more complicated than that. If you think about it, the human race has only been able to understand and broadcast radio signals for the last hundred years or so – even though humans have been on Earth for 200,000 years.

So if we were to make contact with another race, they would have to be at roughly the same technological level as us.

What’s more, if you spread those 36 civilisations out across the galaxy the nearest one to us would be 17,000 light years away. A light year is the distance a beam of light can travel in a year – roughly six million million miles.

So even if intelligent life is out there and it is capable of tuning a radio station to pick up our transmissions, it’s extremely unlikely we’ll ever actually get to meet them.

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