The Fermi Paradox

Last month, the US government released a report on UFO (unidentified flying objects) sightings. This report neither confirmed nor denied whether these sightings were of extra-terrestrial nature. The fact that there is no outright denial is quite significant, as theories of extra-terrestrials have beamed out of the realm of purely science fiction pop culture, and into the world of US national security.

However, is it still speculation? I mean, even the Avengers have met aliens, albeit ones that wanted to destroy half of all creatures in the universe. So where are the aliens in our universe? Why is it in this expanding universe it feels as if we are still alone? There is no clear answer to this question, but theories and possibilities have developed over the years.

This brings us on to the Fermi Paradox; its name coming from a question posed by Enrico Fermi, an Italian-American physicist. One day, Fermi asked his colleagues, "where are all the aliens?" The Fermi paradox explores the contradiction between the high estimations for the existence of extra-terrestrial life and yet no evidence of their existence.

Above is a diagram to put into perspective the possible estimations for the number of intelligent civilisations there could exist in the universe.

One method to predict the existence of extra-terrestrial life is the Drake equation, which considers many factors to determine the number of technologically advanced civilisations in the Milky Way galaxy.

Above is a picture which details the Drake equation. When considering all the factors and estimating appropriate values for each, the equation suggests that there are between 1000 to 100,000,000 civilisations in the Milky Way galaxy that are technologically advanced.

Yet we still ask the question Fermi and so many others before and after have asked, which is where is everybody?

To find any valuable form of answer to the paradox, many have suggested certain hypotheses and possibilities, below I have listed a few that I personally find fascinating:

1) Rare Earth Hypothesis

The book 'Rare Earth: Why Complex Life is Uncommon in the Universe' by Peter Ward (geologist and palaeontologist) and Donald Brownlee (astronomer and astrobiologist), explores the rare earth hypothesis. It states that for intelligent life to develop, an improbable combination of astrophysical and geological events and circumstances are needed.

Ward and Brownlee argue that complex life is very rare among the cosmos, and a multitude of factors need to be just right at a certain time and place. For example, the planet needs to be located in the galactic habitable zone; a region in a galaxy where there is the highest chance for life to develop, and there needs to be a certain arrangements of planets surrounding the main star within the planet's solar system. At the foundation of the hypothesis the belief that the solar system must be similar to that of our own for life to develop. Factors such as a stable orbit, plate tectonics and a strong magnetic field to ensure the carbon cycle is maintained and global temperatures are regulated are essential for the develop of intelligent life, at least, when basing it of the Earth.

Thus, this hypothesis argues that the solution to the Fermi Paradox is that intelligent life is extremely rare is very unlikely. Every factor needed for complex life forms to develop can occur many times in many different places throughout the universe. This theory assumes that humans are a rarity and Earth is a rare occurrence, which is unlikely.

2) First Born Hypothesis

This hypothesis considers the fact that humans may be the first intelligent species to exist in the universe. This goes hand in hand with the Rare Earth Hypothesis in which the development of intellectual life is incredibly rare, meaning that Earth may be the first of its kind in existence.

Thy hypothesis states that we may be living in a cosmological window where the emergence of life is possible, and in previous epochs, conditions were too harsh for life to exist. Humans were the first to emerge in this 'cosmological window', and will be followed by other intellectual life forms.

Similar to me, you may consider this hypothesis to sound ignorant and quite far fetched, seeing as it states that throughout the entire universe, humans are the first intellectual species. However, there is no real way to prove or disprove this hypothesis.

3) Extinction Event

This theory considers the fact that periodic extinction events may occur on every planet, and so civilisations may never develop to an intellectual level where they are advanced enough to engage in space travel or explore the universe.

The theory takes support from the multiple extinction events that have occurred on Earth so far, most notably the extinction of dinosaurs. However, this does mean that humans may one day die out due to a natural disaster, so is a bit more of an unpleasant theory.

4) Intellectual life destroys itself

This theory is one that I find quite interesting. It argues that it is the nature of all intelligent life to eventually end up driving themselves to extinction before they are able to engage in space flight and/or develop the technology needed for space flight.

Sebastian Von Hoerner stated that the progress of science and technology on Earth was driven by two factors—the struggle for domination and the desire for an easy life. The former potentially leads to complete destruction, while the latter may lead to biological or mental degeneration. This is very interesting to consider, since if we look at Earth, it isn't hard to see the damage we have done to the planet. So we can see how this theory may be accurate - especially for the case of Earth, and possibly for all other intellectual civilisations.

5) They are too alien

If the smartest slug was to try communicate with the least intellectual human being, they would get nowhere because they level of comprehension are far too different. What if that is the level of difference between aliens and humans, and the primary reason we have not been able to communicate with them. Maybe aliens are too alien, making their intellectual level may be far beyond us. They may be trying to communicate with us, but their methods are much too complex for us to even realise they are trying to communicate.

6) Our technology is too underdeveloped

This theory is much like the previous one, since it considers the fact that we are simply not as intelligent as we assume we are. Something I once heard at a physics lecture (this was years ago - so I can't remember to credit the lecturer), that has stuck with me all these years was a parallelism to describe our lack of intelligence. The lecturer explained if we were to imagine the universe as a chessboard, and us as the chess pieces, then imagine that each year the chess pieces get together to discuss the rules of chess. Eventually, the players find out that it is not a chess board they are on, but in fact, a checkers board. What if humanity is in the same predicament? We are writing down the rules and laws of the universe only for it to actually be a checkers game, instead of our original assumption of chess. Therefore, we have it so wrong that we are unable to communicate with aliens because they are on a checkers board and we are on a chess board.

7) Zoo Hypothesis

This hypothesis is quite fascinating, since it supports the idea that intelligent life has purposely avoided Earth so as not to interfere with our development as a civilisation. They have essentially left us for our own evolutionary development. As interesting as this sounds, for it to be true, this must mean humans are incredibly (almost too) important. Life on Earth must be so important that galactic species actively keep away from us. The idea that all extra-terrestrials are keen to keep the evolution of our planet free and natural sounds odd, self-centred and a bit too altruistic.

An interesting branch of this hypothesis, that might be more convincing is the Laboratory Hypothesis. This hypothesis suggests that since Earth may be an experiment, we are untouched by aliens as they are experimenting with us. Perhaps to study evolution by monitoring our development through centuries. Our solar system or even our galaxy may be their lab!

8) Planetarium Hypothesis

This hypothesis may be one of interest to those of you who may like the matrix and virtual reality. The idea explores the fact that we are in a simulation and the observable universe is not real, but virtual. Therefore, we have not and will not encounter any alien life because what we see is not real. The whole thought of this is quite mind boggling.

However, this theory does have strong criticism, but then of course, there is the argument that one cannot disapprove the simulation theory based on physical arguments when the very physics we are referencing could be nothing more than the result of the simulation - so it cannot be proven or disproven!

9) Alien life is already here

This one aligns with all the conspiracy theories - what if alien life is already here? What if they have blended in, what if your local bakery is run by aliens? As odd as it sounds, it might be true, so next time you order a croissant, be wary it may be an alien serving you.

10) Communication is dangerous

This possibility comes right out of an action movie, since it considers the fact that communicating and forming relations with other civilisations is dangerous, hence other intellectual species do not try to contact us and ignore our efforts to contact them. From past experiences all around the world, we can see that contact between different cultures has most often lead to violence. Thus, fear from other species of this impending violence may prevent them from reaching out to us


I guess for now, we will have to continue to wonder the endless possibilities for where everyone is!


I hope you've enjoyed this article and found it as fascinating as I have whilst researching!


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Mechanical Engineering student. Future space engineer. Writer. Runner. Passionate about getting more women into STEM.

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