We live in a galaxy populated by hundreds of billions of suns. There are billions of terrestrial planets… So why in this vast space have we not (yet) had contact with extraterrestrial civilizations? Here are 11 possibilities to try to explain it.
Is there life elsewhere than on Earth, or are we absolutely alone in the universe? This question worries humanity. Rather, one would tend to think that there are other inhabited worlds, especially considering that there are hundreds of billions of stars in our galaxy – and hundreds of billions of galaxies in it. Universe – and that most of them are surrounded by planets …
In addition, 13 billion years have passed since the formation of the Milky Way, which, one may think, leaves quite a long time for life to emerge on a multitude of planets. So, as the famous Fermi paradox states, if there is life elsewhere and extraterrestrial civilizations (Carl Sagan predicted more than 10,000), why haven’t these beings come to find us yet? “But where are they? Cried Enrico Fermi. Here are 11 possibilities that could explain this silence.
1. There are no aliens
One possibility would be that we are absolutely (and desperately) alone throughout the universe. There would be no life other than on Earth. All other worlds would be sterile, in short. Or life could have begun and then been annihilated by a cosmic event. It is possible, but it is still hard to believe when we know, according to the statistics, that there are at least 40 billion habitable exoterres in our galaxy alone.
2. There is no intelligent extraterrestrial life
First, how do you define intelligent extraterrestrial life? Are we one of them? After all, there may well be life elsewhere but of a primitive nature … microbial, for example, like the one that developed on Earth for several billion years. Or even plants and animals that would not (yet) have the faculties to communicate beyond their planet (for Earth, this was the case until very recently … at the geological scale).
3. Aliens don’t use technology
Extraterrestrial civilizations may well not have technology to communicate with other worlds. Their development may have been very different from ours, so they might not be interested in them. Or, don’t want to use it…
4. Aliens have much more advanced technology than ours.
Another scenario: their technology could be much more advanced than ours. It is possible that they use modes of communication that we do not (yet) know and that are impossible to decipher.
5. Alien civilizations self-destruct
When we see the challenges facing humanity, especially since the mid-twentieth century, it is permissible to think that elsewhere, on other planets, so-called “intelligent” civilizations may have caused their own disappearance. As far as we are concerned, the threats of collapse and/or extinction are multiple: nuclear fire at the end of a global conflict, severe global warming (famines, droughts, diseases, wars, collapse of Democracies, etc.) combined with the sixth mass extinction, epidemics, etc. Nevertheless, we can hope that Man will be able to avoid such issues …
6. The universe is a very dangerous environment
As we saw above, a sixth mass extinction has begun on Earth. While the latter is caused by our species, the previous ones all had a natural origin: natural climate change and also… asteroids, as was the case for the previous biological crisis, 65 million years ago. Today, Homo sapiens knows that asteroids may one day endanger life on Earth and he also knows that there are still other cosmic events that could annihilate it, such as surpernovae, quasars and also, near us, violent solar flares. It is therefore possible that elsewhere, and frequently, life did not have time to develop. Consider, for example, that the red dwarfs around which rocky planets are often discovered (see Trappist-1 and its 7 planets) are clearly stars with a devastating mood. Their repetitive angers greatly reduce the chances that these planets are truly habitable…
7. The Milky Way Is Very Large
To explain that contact with an advanced alien civilization has not yet occurred, another possibility is that our galaxy — and even more so, the universe — is so large that it could not yet happen. With a diameter of 100,000 light-years, we can imagine that signals emitted at the other end of the Milky Way take several millennia to arrive. It all depends on the distance and also when it was done. And then, let’s not forget that there are hundreds of billions of stars … we just might not have been spotted (yet). For example, if they sent a signal 100 years ago and are 10,000 light-years away, then we will still have to wait 9,900 years. Same problem for us, who are (also) looking for interlocutors.
8. We have been searching for aliens for too short a time
Humanity has not been able to pick up signals from an extraterrestrial civilization via radio telescopes for a century yet. It’s been 80 years, and the active search for signals really began barely 60 years ago. It is therefore an extremely short period of time compared to the age of the Milky Way.
Also, there are so many possible directions that we don’t necessarily listen to the right place. As Andrew Fain illustrates in a Universe. Today article, it’s a bit like we’re looking for a friend’s frequency on a CB that has some 250 billion channels …
9. Aliens emit little or no signals
It is still possible that extraterrestrial civilizations listen without sending out strong signals, like what we do. On our side, we send some in the direction of a few stars. In reality, we have not yet made ourselves known.
10. Aliens avoid us
We do not know their ways of thinking, of course. But we can imagine that in fact we do not interest them at all, nor indeed our planet. The conditions there may be too hostile for them. Unless, too, we seem too dangerous and unfeasible to them. Who knows? Maybe we scare them!
It is also possible that they apply a galactic-scale policy of non-interference with regard to worlds like ours, populated by primitive beings… (as in Star Trek). Perhaps they then feel that contact would be too premature and have deliberately chosen, at least for now, to leave us alone, in our affairs, refraining from interfering.
11. The aliens are already here
Last but not least, maybe the Visitors are already there and we haven’t even noticed them. So maybe they are watching us discreetly. On the other hand, from there to convince oneself that extraterrestrials have made agreements with the governments of several countries, as the conspirators carry out all the time and at the top of their lungs, that sounds more laughable than likely.
So, are we alone in the universe or not? In any case, according to several astronomers and exobiologists, we should soon know if there is life elsewhere. Researchers are confident of making such discoveries in the coming years. On the one hand, within our Solar System, via probes and landers on Mars, Europe and/or Enceladus. And, on the other hand, beyond that, by studying the atmosphere of the rocky exoplanets that we are always more acutely uncovering…
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