scientists have been wondering for a long time about the difficulty of the quest for an extraterrestrial life, which astronomers announced Thursday that they have found possible clues on an exoplanet.
An American-British team has detected in the atmosphere of a distant planet, K2-18B, the chemical traces “the most promising to date” of a possible presence of life, in a study whose results are still to be confirmed.
Our galaxy, the Milky Way, has existed for about 10 billion years and has more than 100 billion stars. It therefore probably shelters a vertiginous number of potentially habitable planets alone.
In this case “where is everyone?” Asked the enrico physicist in 1950 during a lunch with colleagues who remained famous.
According to this “Fermi paradox”, with enough time, “each extraterrestrial species should end up having its own Elon Musk who would colonize the following star”, explains to AFP Jason Wright, director of the Research Center on Extraterrestrial Intelligence at Pennsylvania State University.
At least 75 hypothetical solutions to this paradox have been proposed, according to a book published 2015.
Humanity may not have yet detected extraterrestrial life because there is simply not.
Many scientists judge this unlikely. Approximately 87 % of those questioned in a recent survey of Nature Astronomy think that there is at least a basic extraterrestrial life form. And more than 67 % that intelligent civilizations also exist.
It is also possible that the extraterrestrials are already there without us having noticed them – or that this has been hidden.
The interstellar space may be too difficult to cross, the distances that are too large, the necessary resources too large.
Another theory is that of a “large filter” which would prevent life from emerging or overcoming a certain stage of development. Once a civilization has controlled space travel technology, it could tend to self -destruct or exhaust the natural resources of its planet.
Theories are even more speculative.
According to the hypothesis of the “zoo”, technologically advanced extraterrestrials would choose to leave us alone, observing us from afar. That of the “planetarium” suggests that the extraterrestrials create an illusion which makes the space empty in our eyes.
Another imagines the universe as a “dark forest” where everyone hides so as not to be destroyed.
But there is a major problem with many of these “so-called solutions,” said Wright. They start from the principle that all hypothetical extraterrestrial civilizations would behave in the same way and forever.
