Based on the assumption that intelligent life develops on other planets in the same way as on Earth, a study estimates that there could be dozens of intelligent civilizations in our galaxy.
Are we alone in the universe? Many doubt it. It seems indeed very unlikely, given the vastness of the cosmos, that our planet is the only one to carry life. Especially since it seems to have appeared on Earth as soon as it had the opportunity. Based on this observation, we could, therefore, imagine that, if conditions allow, life could also develop elsewhere in the Universe.
The idea that microbial life could exist on another planet, or even on a moon, is almost acquired. Indeed, it is only a matter of time, a priori, before one of our instruments detects the presence on Mars, Europe, or even Enceladus, which are in our system the main candidates for the support.
Estimating the possible number of intelligent extraterrestrial civilizations is, however, much more difficult. A team from the University of Nottingham (UK) still tried it.
More than 30 civilizations in the Milky Way
In an article published in The Astrophysical Journal, the researchers explain having based their calculations on a so-called “strong” Copernican astrobiological limit, which suggests that intelligent life is formed in 4.5 to 5 billion years on a planet, as was the case for Earth, around 4.5 billion years old. By “intelligent life” means “advanced civilization”.
Note that, conversely, a so-called “weak” Copernican astrobiological limit suggests that intelligent life can develop before this threshold. This being the case, this new research was therefore based on the first hypothesis, finally taking example from our planet.
In addition, the researchers also assumed that these advanced civilizations should develop in environments rich in metals. Again, as was the case for Earth, thanks to the Sun which has a high rate of metallicity. Previous research conducted in 2012 had also assessed the appropriate “minimum stellar metallicity” required for the formation of Earth-like planets.
The researchers then sought to find out how many planets in the Milky Way would be able to meet these conditions. They estimate that there could be more than 30 intelligent civilizations currently able in the galaxy to emit radio signals into space, as we have been doing for decades.
“There should be at least a few dozen active civilizations in our Galaxy assuming that it takes 5 billion years for intelligent life to form on other planets similar to Earth,” said Christopher Conselice of the ‘University of Nottingham in a statement.
Furthermore, still according to their approach, the average distance separating us from all these possible civilizations would be about 17,000 light-years. This unfortunately makes the possibility of communicating with our potential “neighbors” a priori very complicated.