If there are at least 100 billion galaxies in the universe, each containing 1000 billion stars, where are they all? This is the Fermi Paradox.
The universe is a vast and mysterious place, full of galaxies, stars and planets. One of the questions people have asked since the beginning of time is: “Are we alone in the universe?“. And in this context, Fermi’s paradox poses a challenging question: “If the universe is so vast and potentially hospitable, why have we not yet found any obvious signs of extraterrestrial intelligence?“.
Let us look together at possible explanations and implications for the search for extraterrestrial life.
The Fermi Paradox
The Fermi Paradox is named after the famous Italian physicist Enrico Fermi, winner of the 1938 Nobel Prize in Physics.
According to the story of how the paradox was formulated, in 1950, during an informal discussion with colleagues at the Los Alamos laboratory in New Mexico about a UFO sighting, Fermi asked a question that remains unanswered to this day: “Where is everybody?” (Dove sono tutti?).
The contradiction, the main feature of paradoxes, is the fact that despite the high theoretical possibility of life in the universe – it is plausible that there are other forms of life on other planets, as there are hundreds of billions of galaxies – there is no conclusive evidence on the basis of available scientific data for the existence of extraterrestrial civilisations.
Why has no one contacted us yet?
Possible solutions
Over the years, various approaches and theories have been developed to explain Fermi’s paradox, all based on logical reasoning. Let us analyse the most relevant ones, bearing in mind that none of them is based on scientific evidence:
Aliens exist but are hiding
This explanation suggests that there are advanced extraterrestrial civilisations, but that they prefer not to come into contact with other life forms. This may be because they lack the technological development that would allow them to communicate or, on the contrary, because they have reached a level of technological development that would protect their existence from possible ‘encounters’ with other civilisations.
In these cases, the lack of evidence could be the result of deliberate action on the part of these extraterrestrial civilisations.
Aliens exist, but are too far away
Another plausible answer to Fermi’s question is that other intelligent life forms exist, but are too far away in space and time to contact us. A possible alternative to this hypothesis is that other populations are not so far away from our galaxy, but are not yet able to travel in space.
Aliens exist, but we cannot receive their signals
Even this hypothesis accepts the existence of extraterrestrial civilisations so intelligent that they may have developed communication techniques that are still completely unknown to us, or only hypothesised by us, so that we are unable to pick up their attempts to communicate.
Aliens are extinct
This option, also known as the ‘Great Filter Theory‘, predicts that there is an insurmountable obstacle preventing the spread of intelligent civilisations into space. This could be a catastrophic event that destroys civilisations before they can colonise other regions of the Universe, or a series of evolutionary challenges that only a few species can overcome.
The hypothesis would seem to be supported by Drake’s Equation, which suggests that the average lifespan of an intelligent civilisation is very short, around 10,000 years, after which it would tend to self-destruct with total annihilation or regression to a primitive state.
So while there have been intelligent alien civilisations capable of communication, they may have destroyed themselves before they could send us signals.
Aliens do not exist
The simplest solution is that the probability of life spontaneously evolving in the universe to produce an intelligent civilisation is very small. If the conditions necessary for life to emerge are extremely specific, it could be a coincidence that life evolved on our planet, and this would explain the lack of contact with other civilisations.
A fascinating puzzle
The Fermi paradox is a fascinating puzzle that fuels our curiosity about extraterrestrial life. Despite scientists’ best efforts to search for signs of extraterrestrial intelligence, no conclusive results have yet been found.
Nevertheless, the search for extraterrestrial life continues to fascinate and stimulate the human imagination. Recent developments in the discovery of habitable exoplanets and advances in the technology of astrophysical observations offer new opportunities to search the universe for signs of life.
