Where are everybody? This question asked by the physicist Enrico Fermi in 1950 about the possible existence of other intelligent civilizations in the Universe is still haunting the minds of scientists, that shuffle the idea that they have already located us and do not want to establish contact.
"Perhaps they are watching us as we look at zebras in a zoo," said US astronomer Douglas Vakoch, president of METI, an educational and research organization that transmits signals to nearby stars in search of a hypothetical exchange.
His body has assembled biophysicists, astronomers, sociologists and palaeontologists at the planetarium in Paris to reflect on the paradox raised by Fermi: why if there are billions of possibilities for intelligent civilizations on other planets, none has contacted us.
"For about 50 years astronomers are listening for possible signals, but what if all civilizations do the same? It would be a very silent universe, "adds Vakoch, 57 years old.
The radiofrequency or laser signals sent so far seek to take that first step that makes see those hypothetical intelligent life forms that human beings are open to dialogue.
One of those messages was sent in 2018 to mark the 25th anniversary of the Sónar electronic music festival in Barcelona. It was directed to the Star of Luyten, about 12.4 light years from Earth, with basic information about humanity, various musical pieces and instructions to decode them.
"The aliens are not going to speak English or Spanish. What language do we have in common? If they can detect our signal they need to have been able to build a receiver, so they should know some math, "adds Vakoch.
This biennial meeting also contemplated the idea that these extraterrestrial assumptions with technologies superior to ours, aware that encounters between civilizations can be harmful for both, want to stay on the sidelines.
"You do not have to be paranoid or afraid, but you must be prudent," adds the astrophysicist of the Paris-Meudon Observatory Danielle Briot.
The possibility that the signals that are sent from Earth are captured or that theirs reach us is negligible, admits. "But even if it's small, we have no right not to try."
The forum of the METI also took hold of the hypothesis of the American astrophysicist Michael Hart, according to which the absence of extraterrestrial visits could be due to the fact that these have already begun interstellar travel but have not arrived, or that they did it in the past and we did not perceive it. or we still did not exist.
That lack of temporal coincidence or the possibility that human intelligence is not sufficiently developed to capture that type of signals are factors that add to another: that there really is no extraterrestrial life.
"It would be a miracle to me that there was no other life out there, and I do not believe in miracles. Finding her is tremendously difficult, and above all, engaging in conversation. (…) We want to believe, but we need proof. That's why these interdisciplinary meetings are so important, "adds Vakoch.
The discovery in 1995 of the first exoplanet and the discovery since then of more than 3,700, according to the Paris forum, encourage the hope of the scientific community focused on this work.
The scientists emphasize that the vision that has been had until now of the hypothetical extraterrestrial is very anthropocentric: they are attributed arms, legs, head and eyes, as if they were a more evolved version of the human race.
To imagine the aspect of that intelligent life is a mere speculation, but what would happen if it were to be contacted?
«It would be extraordinary. I would change everything: biology, politics, philosophy … All the way to consider the world and our way of reasoning, "concludes Briot, for whom, at that point, new questions would arise, such as what to do or how communicate. EFE