The Dark Forest Theory: A frightening answer to the Fermi Paradox
- Jonathan Ong
- Jan 3
- 4 min read
In 1928 Edwin Hubble made observations of the rate of expansion of galaxies, estimating that the universe is around 2 billion years old. In the present, better observation tools allowed us to figure out that the universe was expanding at an ever increasing rate, changing that 2 billion estimate to around 14 billion years (Hubblesite, 2002).
Later on In 1961, Frank Drake created his Drake Equation which aims to predict the number of intelligent civilizations in the cosmos and determined that there should be at least 10 such civilizations in the milky way alone (Lohnes, 2024).
This leads to the question, if intelligent life is so likely to appear out there in the cosmos, then why haven’t we met any? The contradiction between the idea that intelligent life should be common and our lack of evidence for intelligent life that makes up the Fermi Paradox.
To this end there are several theories which hope to provide an answer. This article aims to discuss one such possible answer, posed by the science fiction author Liu Cixin in his book “The Dark Forest”.
The Dark Forest theory suggests that the reason why we haven’t met any aliens yet is because they’re all hiding. To be more clear, they are hiding from hunter civilizations. To understand this idea there are a few points needed to be made clear first.
Point number 1: Every civilization wants to stay alive
This one is pretty self explanatory.
Point number 2: Interstellar communication is difficult, and it is impossible for civilizations to determine if another civilization is hostile or not
It is in the best interest of civilizations to determine if neighbouring civilizations are friendly or hostile. However, in terms of communication across space, this would prove difficult
Different cultures, forms of communication and species all make communication between civilizations a herculean task as the same message can be interpreted differently based on who is reading the message. In addition to this, civilizations may also communicate in ways others can’t process. As an example of this, think of how ants communicate with each other using pheromones whereas humans communicate through speech and text. If this article was conveyed to you using pheromones would you have understood its contents?
This doesn’t even include how difficult it is to communicate across interstellar distances. If we on Earth attempted to communicate with a civilization on Alpha Centauri, the closest star system to Earth, it would take 4 years for a message travelling at the speed of light to reach them, and another 4 years for a message to reach back to us. Now imagine communication in distances of hundreds, thousands, hundreds of thousands of light years. By the time a message has been received, the sender could have advanced beyond recognition, undergone a societal shift, or even gone extinct. Even if a civilization were able to somehow break through previously mentioned barriers to communication and determine that another civilization was friendly, that information may be outdated by decades, centuries or even millenia.
Because of these difficulties in communication between civilizations, it is near impossible to determine if an alien civilization is hostile or friendly.
Point number 3: The safest option for civilizations is to destroy other civilizations before they may do the same to yours
It's been established that communication between civilizations is near impossible. That being the case, the safest option for your civilization is to assume other civilizations are hostile and prepare for the worst, rather than being caught off guard expecting them to be friendly. Even in scenarios where a civilization encounters other friendly civilizations, due to the vast distances in space, that friendliness might be outdated and they have now turned hostile.
Differences in technological level also play a part in this as if your civilization is significantly advanced enough, you would not need to worry about weaker hostile civilizations. However, due to the explosive nature of scientific advancement, a hostile civilization that's weak one day may become strong enough to destroy yours the next.
Due to this, the safest bet for civilizations would be to simply eliminate other species before they have a chance to pose a threat.
If that’s the case, and you know there are hunters lurking in the dark, then it would be in your civilizations best interest to keep quiet and avoid the gaze of those hunters.
The Dark Forest State
Since these 3 points are now understood, we can explain how this serves as an answer to the Fermi Paradox. If it is in the best interest of civilizations to hunt down and destroy other civilizations, then it is also in the best interest for them to hide from other hunters. The reason why space seems so empty, in the Dark Forest Theory’s suggestion of the universe, is because everyone is hiding so as to not get destroyed.
Liu Cixin explains this in his book “The Dark Forest” as hunters roaming a dark forest uncertain of what they will meet, and shooting at noises which may or may not be other hunters.
If this truly is the case, then decades of human efforts to contact alien life would have been not only a mistake, but a fatal one.
Luckily there are arguments against such a Dark Forest State for the universe. Vast interstellar distances also mean that civilizations are unlikely to feel a need to hunt others. Why should they when the resources in space are so abundant? Arguments also include, if we are truly in a Dark Forest State, shouldn’t someone have destroyed Earth already?
Regardless, since we haven’t met any alien species, there is no way to determine if the Dark Forest Theory is true or false. Hopefully, it ends up being the latter.
References:
Hubble uncovers oldest “Clocks” in space to read Age of Universe. (2002). HubbleSite.
Lohnes, K. (2024). The Fermi paradox: Where are all the aliens? Encyclopedia Britannica.
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