In the summer of 1950 at the Los Alamos National Laboratory, Italian-American physicist Enrico Fermi was conversing with his co-workers Edward Teller, and Herbert York on their way to get lunch.
The group was discussing the topic of flying saucers and the lack of evidence supporting its existence. This is when another co-worker, Emil Konopinski, joined the conversation and brought up a cartoon he had recently seen in the New Yorker.
At the time, there were reports of public trash cans disappearing from the streets of New York City, which the newspapers of New York covered in great detail. The cartoon provided a humorous explanation by claiming that 'little green men' with 'flying saucers' were taking away the public trash cans.
Fermi commented that the cartoon provided a reasonable theory as it covered two separate phenomena; the reports of flying saucers and the disappearances of public trash cans within New York. This led the group to begin discussing whether saucers could somehow exceed the speed of light.
Fermi then asked Teller how likely it was that they would find evidence of "a material object that moves faster than light" within ten years. Teller responded with "10-6", to which Fermi disagreed and believed that the probability was around ten percent.
The two went back and forth debating each other, rapidly changing numerical values as quick as they could think of. The conversation about extraterrestrial life finally simmered down, and the group went on to discuss unrelated things before they finally sat down at a luncheon table. After they sat down, Fermi suddenly asked a question that would surprise his co-workers and puzzle scientists for decades to come; "Where is everybody?"
This question would lay the foundation for what is known as the 'Fermi Paradox'. The Fermi Paradox is defined as the contradiction between the many pieces of evidence that support the possibility of life existing beyond our own planet, and the complete lack of any empirical evidence that indicates that extraterrestrial life exists.
Fermi rationalised that any civilization that possessed a moderate amount of rocket technology could have colonised an entire galaxy within 10 million years, which is a miniscule amount of time within the cosmological time scale.
Yet, there was no such evidence of a galactic empire to be found. Many decades have passed, and we still have no concrete proof of extraterrestrial life even though logically there should be an extremely high chance of it to appear.
Within just our Milky Way, there are around between 100 billion to 400 billion stars. Out of all of these stars, there is no complete consensus on how many are 'sun-like', but even within the most conservative guesses (around 5%), there would be around 20 billion sun-like stars.
A study from November 2013, using data gathered from the Kepler Space Telescope, suggested that a fifth of these sun-like stars have an earth-sized planet orbiting within its habitable zone.
If only 0.1% of those planets hosted life, there would be at least around a million planets teeming with extraterrestrial life. Yet we have never encountered a single shred of empirical evidence that undoubtedly proves the existence of life. Why is this the case?
Throughout the years, there have been a variety of people proposing their own ideas for why this is the case, be it technological, astrographical, and more. One such example of a hypothesis revolves around a concept known as the 'Great Filter'. It is defined as the variable that prevents non-living matter from fully completing the process between abiogenesis, or 'becoming alive', to becoming an intelligent civilization that can be measured on the Kardashev scale.
It is hypothesised that this hypothetical 'Great Filter' is the reason why we have not found any extraterrestrial life, as they were wiped off by it. We do not know what the 'Great Filter' exactly is, nor do we know whether or not it is behind us or something that humanity will face in the near or far future.
Another hypothesis to explain the Fermi Paradox is the 'Rare Earth hypothesis' which posits that our 'pale blue dot' is truly unique and the conditions for life to appear are far more complicated than we think. After all, we have found multiple heavenly bodies that could house life, but we have not found proof of any life living in them so far. This stands in contrast to the Copernican principle that most scientists abide by, which in simple terms states that if a theory needs a special origin or concept, it is not plausible.
A third example is the 'Zoo hypothesis', which proposes that extraterrestrials exist but are intentionally avoiding interacting with us in order to observe us, like how we view animals at a zoo.
There are multiple reasons for why extraterrestrials would want to observe us from a distance, with an example being wanting an example of how civilizations function and progress. Alternatively, they are not interacting with us in order to protect some sort of nebulous threat that could transfer to us, should they meet us.
The last and the most obvious hypothesis is to take all the info we have at face value, and conclude that we truly are the only ones living within the Local Group, if not the whole Universe.
In conclusion, we have so far been unable to find life beyond our own plant. While there have been many proposals for why that is the case, I believe that we are lacking huge pieces of the puzzle and should refrain from choosing a conclusion. For most of human history, people have been only hunting and gathering food to survive. It is only recently that we can actually broadcast and send rockets to space.
We have only discovered a microscopic portion of the incomprehensibly vast universe, leaving behind billions and billions of uncharted worlds that could hypothetically host life. If there truly is no life outside of Earth, that just leaves the mesmerizing beauty of the stars for us to exclusively explore someday.