Where is everybody? (The Great Filter)

Source: pixabay

Our universe is 13.8 billion years old. In that time, the formation of over 10 trillion galaxies has occurred. In each of these galaxies exist over 100 billion stars. To put this in perspective; it is estimated that there are at least 10,000 stars in our universe for every grain of sand on Earth. Therefore, it is also highly likely that there are up to 1 billion habitable planets just within our own galaxy. If each of these habitable planets are capable of supporting life, then that leaves us with one major question: Where is everybody? This was the question remarked by Enrico Fermi, a physicist and one of the founding fathers of the nuclear age, during an ordinary lunchtime break with his colleagues which led to the eventual birth of the quite extraordinary: “Fermi paradox”.

The “Fermi paradox” asks; that given the age of the Universe and the potential for life outside of Earth, then why has there not been any apparent colonization attempted, or communication made by such extraterrestrial life? Several hypotheses have been created to account for this paradox and these form the basis for a theory referred to as the “Great Filter”. The “Great Filter” theory suggests that during the advancement of an intelligent civilization, life from that civilization will encounter an inevitable barrier that is almost impossible to surpass. A barrier such as this would therefore account for the apparent rarity of alien life. That barrier is called the “Great filter”.

The earlier the better

One hypothesis for the Fermi paradox is the idea that the Great Filter is the creation of the very first cell. Perhaps the conditions for the creation of life is considerably more complex than what is presently assumed, and requires not only time but also incredible luck. Indeed it is worth noting that we are still very far from unlocking the mysteries of how the first cell on Earth came to be.

Another hypothesis that partially parallels the last is the idea that the Great filter may be the transformation of the simple prokaryote cell to the more sophisticated: eukaryotic cell. If either of those were the case, this would mean that we, as humans, have already have surpassed the Great Filter. However, if this is not the case, theorists suggest that the Great filter will inevitably occur later. This is not good.


The prospect that our civilisation is still awaiting the Great filter is a frightening thought. If this is indeed true, then we are due for a certain extinction level event. Some have hypothesised that – for humans – this will occur in the form of a devastating nuclear war. Others have suggested that global warming may spell the end for us.

However, the most amusing yet equally terrifying theory is the idea that some highly advanced alien race may be operating on a “search and destroy” mandate through observing the technological progress of other civilizations. As the scientific knowledge of a particular civilisation begins to advance to a level that can potentially be traced and detected by the alien warlords, that race is then promptly wiped off the galactic map.

Source: pixabay

If you’re now feeling a little worried about the possibility of an impending alien invasion in the near future, you may rest assured knowing that it is highly unlikely that we will reach a level of technology that could ping our location to these alien bullies within our lifetimes. This is assuming that such a race even exists.

Ultimately however, it is still entirely likely that we are alone in this universe. It is possible that we are the only source of life in a universe that is 96 billion light years of sheer emptiness, and for some reason, I find this prospect infinitely more terrifying than being subject to an alien invasion.

 If you’d like to find out more about this, I’d highly recommend that you refer to the “The Fermi Paradox — Where Are All The Aliens?” 2 part series, published by the “Kurzgesagt – In a Nutshell” Youtube channel, which was also a major source of information for this blog post.

2 Responses to “Where is everybody? (The Great Filter)”

  1. lohj3 says:

    Really interesting article. =-)

  2. Nadun Udawela says:

    On a side note: The SETI (Search for extraterrestrial intelligence) institute has bet everyone a cup of coffee that an extraterrestrial intelligent lifeform will be found within the next 20 years.