Cosmic Sociology
Andrija Curganov | Vladyslav Tomashpolskyi


We are going to model an epistemic approach to a solution to Fermi's paradox as it was proposed by Liu Cixin in his second book of the Remembrance of Earth's Past-trilogy. Before going into the details of how we modeled it, we will give you, the reader, a short summary of the background information which underlies the project.

Where is everybody?

This is the question Enrico Fermi, mainly famous for creating the world's first nuclear reactor, asked some colleagues during a lunchtime conversation, referring to the apparent contradiction between the high probability of existence of extraterrestrial life, and the lack of evidence that other civilizations actually exist. Over the years, many different explanations have been offered as an answer to this question, which is now commonly referred to as the Fermi paradox.

Chain of suspicion

The chain of suspicion is a concept introduced by Liu Cixin in The Dark Forest, his second book in the Remembrance of Earth's Past-trilogy. It consists of a few axioms and presumptions about civilizations throughout the universe. Based on these axioms and presumptions, the civilizations behave and act in certain ways, when evolving and encountering other civilizations.


  1. Survival is the primary need.
  2. Civilization grow and expand continuously, but the total amount of matter within the universe is constant.


  • Communication barriers. Due to biological differences between civilizations and the delay in communication across interstellar distances, it is very difficult for civilizations to communicate and understand each other.
  • Detection reversibility. If a civilization can detect another civilization, sooner or later, the other civilization can also detect the one that detected it.
  • Tech explosion. When looking at the history of humans, we can see that certain advancement in technology can quickly lead to an acceleration in this advance of technology.

Deducing a possible shape of the universe, using these axioms and presumptions, one can see that only one kind of relationships is possible between worlds: upon discovery of another world, a civilization must, in order to survive, do everything within its power to destroy it.

This is also a possible theoretical explanation for the Fermi paradox. If any civilization exposed itself in the universe, it would soon be destroyed. This is why the universe is so silent.