The idea of getting in touch with extraterrestrial life goes through a series of uncertainties. First of all, there should be some form of life elsewhere than on Earth. Then that life is advanced enough to master an advanced form of technology. Finally, that this way of life is not too far away in the Universe and that it lives at the same time as our humanity.
Let us assume that all these assumptions are true. It would still be necessary for the extraterrestrial signal to reach us and for us to understand that it is a form of communication! Lots of doubt. And still. Some scientists are convinced that it is impossible for us to be the only form of life in the universe.
The famous exobiologist Michel Visonous trusted last autumn: “In all studies conducted by large scientific communities, it is believed that in order for a way of life to develop, it needs liquid water and a compatible temperature: between -5 degrees and + 100 degrees around the rain.However, many exoplanets in the Milky Way meet these criteria.Does the absence of evidence of life mean the absence of life at all?
36 extraterrestrial civilizations capable of contacting us
Many scientists have tried to solve this puzzle. The Fermi paradox, named after the Italian physicist, says that if an intelligent extraterrestrial civilization existed, we would already know about it.
Astronomer Frank Drake took the problem head on to come up with a complex equation in 1961, the famous Drake equation. Its purpose is to estimate (with a large amount of uncertainty) the number of advanced civilizations capable of communicating with Earth. It takes into account several factors, such as the number of habitable exoplanets in our galaxy, the possibility that a life form may be intelligent, or even the duration during which a civilization could exist. Depending on these variables, the result of this equation varies from 0 to … 1,000,000!
Based on the Drake equation and using our current knowledge of habitable planets, a group of scientists recently estimated the number of extraterrestrial civilizations capable of contacting us at 36.
400,000 years before communication with an extraterrestrial civilization
If these advanced civilizations exist, then when will we communicate with them? Not until 400,000 years ago does a new study … apparently based on assumptions. Its authors admit: “Knowing what proportion of the planets can give rise to life, the evolutionary process of this life towards an intelligent civilization and its ability to send traceable signals into space is very unpredictable”.
However, it is not impossible to produce valid models based on logical assumptions, leading to plausible estimates of the existence of intelligent civilizations, the authors specify.
That is why they looked at two specific parameters: on the one hand, the number of habitable planets and the frequency with which life on these planets evolves into an intelligent form. On the other hand, the stage of development of the host star when the intelligent civilization is born (since the death of the star also means the death of civilization).
Thus, the first parameter is denoted fc and the second F. By performing several series of simulations, the researchers succeeded in drawing the most optimistic and the most pessimistic scenario.
First contact with aliens in 2,000 years, at best
The most optimistic scenario believes that the star could only have reached 25% of its total lifetime when an advanced civilization appears (F = 25%), and for every habitable planet, the scenario estimates that there is a 0.1% chance of a advanced civilization emerges.
With these two variables, there could be 42,000 intelligent civilizations scattered across the galaxy, having lived in different eras. According to the authors of the study, we can at best engage in communication with one of them over the next 2,000 years. Remote control and available at the same time …
But in the worst case, the star is 75% of its lifetime when a civilization occurs (F = 75%), and the chance of life on a habitable planet would be 0.001%. In this case, there would be only 111 extraterrestrial civilizations left in our galaxy. But above all, we had to wait another 400,000 years to get in touch with one of them …!
It should also be noted that other civilizations, if they exist, are subject to external parameters just as much as we are: sudden climate change, killer comets, the death of the host star, the explosion of a supernova … Their lifespan is self-sustaining, reducing the chances of coming in contact with them.
Meanwhile, there is nothing to stop us from imagining what it is. Perhaps extraterrestrial civilizations are already communicating with each other. Maybe they have already discovered us in the past without us knowing it. Perhaps the day we contact them, our humanity will be so advanced that it will be unrecognizable to present human beings. Or maybe even that we never come into communication with any kind of life … In the domain of hypothesis, anything is possible.