The Great Filter

In 1990 Robin Hanson proposed a hypothesis in his attempt to resolve the Fermi paradox – “If there are billions of earth-like planets, where are all the aliens?” Since the time we started looking up, we watched, listened and waited for someone out there to say Hi, but space seems empty and dead. Is life so rare after all? Or maybe life is abundant but has a hard time reaching to our stage as humans, able to produce space crafts and radio waves? Is it at all possible that life can be so technologically advanced that we can’t detect it because we don’t know what to look for?

The Great filter describes certain stages in the evolution of a species that allow it to go from basic chemistry to space faring civilizations.

  1. The life must be able to self-replicate

  2. Simple cells evolve into complex ones

  3. Multicellular organisms develop

  4. Lifeforms become more complex and are able to use tools

  5. These lifeforms create advanced technology for space colonization

  6. These lifeforms colonize their star system, neighbouring systems and possibly their whole galaxy


Humans are currently almost at stage 5, able to produce technology that can take us around our own solar system, albeit very slowly. The Great filter lies in one of these stages. It is an obstacle so difficult for life to overcome that it stops lifeforms from evolving to the next stage. We can’t know which one it is, but one thing is for sure; it is either behind us or ahead of us. Both scenarios are equally scary depending on your point of view.

The Filter is behind us

If the filter is somewhere between 1 and 4 it means we are extremely special. We made it past the filter and we are one of the few species if not the only one that has evolved to this stage.

Maybe the filter is the first stage and life has a really hard time developing in the first place. If we find Mars, the oceans of Europa or the clouds of Venus completely lifeless then that might be the case. There is nothing elsewhere apart from Earth.

Maybe the filter hides between stages 4 and 5. Maybe there are a lot of intelligent species out there able to use tools and form early civilizations, but never make it to space. Maybe the discovery and advancement of technology is their undoing. Imagine other Earths that never make it through the World Wars or the cold war. Imagine planets where Roman empires rule over with cities, war tactics and poetry but are unable send out any form of signal of their presence to us. Maybe space is filled with these civilizations, but we have no way of knowing unless we visited every single planet in the goldilock zone.

The Filter is ahead of us

The baseline of this blog rests on the premise that we are behind the filter. Humanity has yet to face the biggest challenge of them all, one that can bring total extinction to our species. It will not be an event that can possibly cause death and chaos to the majority of the population like asteroids or super volcanoes. No, our species can survive even that; we will find a way through technology and innovation. The filter implies an obstacle so hard that it is simply impossible for life to get past it; an obstacle that hides and lingers within us, feasting on our civilization’s greatest flaws and growing until it’s too late to stop it. It might sound corny, but the biggest challenge humanity has yet to face is humans themselves. Either by nuclear or economic war, climate change, advanced doomsday technology, malevolent AI or something else entirely that we can’t even imagine right now, our species is on a course of extinction.

Is it a depressing thought? Maybe, but it is not that far fetched to consider that any species that claims domination over their planet will need more and more resources to sustain itself. It is a fair assumption that a species at the same stage as humans will want to completely take over their world and use its resources before starting colonizing elsewhere. It is a universal principle for any civilized species to want to expand.

This would be the most probable place for the filter. The point where a civilization is already powerful enough to change their environment but doesn't have the know-how to face the consequences. Therefore, it wouldn't be surprising to see galactic species fighting among themselves and ultimately wiping themselves out. One could argue that alien intelligent life doesn't necessarily have to be violent. Evolution however and nature in general makes it essential for any dominant species to thrive on competition and destruction. This is the only way we know nature works.


In order to progress to the next stage, we need to change mentality as a collective. Our narrow mindedness will be our undoing, unless we take action. We have already changed, littered and used our planet for our own gains. We are still plagued by poverty and exploitation around the globe. We still fight over imaginary borders and the concentration of melanin in our skin. These issues and many others will catch up with us at some point and we cannot escape it in our current situation of society. Life is not just about working 9 to 5, having kids and at some point dying. Let's ask more from ourselves. The worst thing we can do is remain idle and indifferent to the problems that affect us as humans. Don't ask "Why should I care?" but "When should I start worrying about all that", which is now!

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