Silencethe Fermi paradox and the Great Silence
No alien signal has ever been confirmed. The Fermi paradox, the Great Silence and the research behind the Cosmos Era ending “Silence”, from SETI to Dyson.
No signal from an extraterrestrial civilization has ever been confirmed. That is the Fermi paradox, and David Brin's 1983 "Great Silence" systematically discussed the possible reasons for the quiet. The game's ending “Silence” picks the coldest explanation: in a dark forest, the safest sound is no sound. But the "dark forest" is a literary explanation proposed by Liu Cixin, not a scientific conclusion.
This page first explains how to unlock the ending, then covers what the “Permanent silence” node really means, then several studies on searching for alien signals, and finally a related novel.
How to unlock it
- Hint: In a dark forest, the safest sound is no sound.
- Condition: Unlock “Permanent silence”, then witness the end of the universe.
- Reward: This run appears in the album as a blank card.
The ending belongs to the Information category, and the reward fits the theme: this run is a blank card in the album, with nothing left on it, a picture of "silence".
The “Permanent silence” node asks you to do three things:
- Turn off all radio stations: Keep radio signals from leaking out so no one can listen in.
- Bring waste heat down to the ambient temperature: An advanced civilization doing work gives off heat, and infrared radiation is the easiest trace to give away. Freeman Dyson's paper used exactly this to look for civilizations.
- Make your star look like any other star: Do not enclose the star, and leave no trace that infrared radiation could identify.
Why silence may be the safest
The reasoning behind "Permanent silence" is blunt: in a universe with relativistic kinetic weapons, "not being found" is the most reliable survival strategy. A 1-tonne object hitting at 0.1 times the speed of light releases energy equal to about 100 million tonnes of TNT.
Real research on searching for alien signals
- Searching for interstellar signals: Two physicists suggested listening for alien signals with radio telescopes near the 21-centimeter frequency of hydrogen, which launched SETI (Cocconi and Morrison, Nature, 1959).
- Dyson spheres: A sufficiently advanced civilization might enclose its star, and we could find such civilizations by their anomalous infrared radiation (Dyson, Science, 1960).
- Scale of civilizations: Civilizations are sorted into three types, planetary, stellar and galactic, by the energy they can use (Kardashev, Soviet Astronomy, 1964).
- Where are they?: If alien civilizations were common, they should long ago have spread across the Milky Way. Michael Hart concluded that we may be the first (Hart, Quarterly Journal of the Royal Astronomical Society, 1975).
- Light sails to the stars: Pushing an extremely light sail with a ground-based laser array could accelerate a probe to one fifth of the speed of light (Lubin, Journal of the British Interplanetary Society, 2016).
- The first exoplanet: A giant planet was found around 51 Pegasi, circling its star in just 4 days. The Solar System was no longer the only one (Mayor and Queloz, Nature, 1995).
- The last chapter of the universe: The fate of the universe trillions of years from now and beyond: stars burn out, protons may decay, and black holes eventually evaporate (Adams and Laughlin, Reviews of Modern Physics, 1997). Unlocking requires witnessing the end of the universe, which is why it relates to this ending.
These studies tell us how humans look for alien civilizations. They cannot answer why none has been found. They are placed under "Silence" because they are the background to the Fermi paradox, not evidence for the dark forest.
Game lore, not real
The "dark forest" is a literary explanation proposed by Liu Cixin, not a scientific conclusion. The Three-Body Problem II: The Dark Forest (2008) is about humanity facing an enemy that is sure to arrive, and placing its hope in four "Wallfacers". One of them works out a cold cosmic sociology: every civilization is an armed hunter. Its scientific background is this: the Fermi paradox is a real scientific question, and the "dark forest" is one literary explanation that can be neither confirmed nor refuted.
Want to read the originals? Search these titles
- Cocconi and Morrison (1959): "Searching for interstellar communications"
- Dyson (1960): "Search for artificial stellar sources of infrared radiation"
- Kardashev (1964): "Transmission of information by extraterrestrial civilizations"
- Hart (1975): "An explanation for the absence of extraterrestrials on Earth"
- Mayor and Queloz (1995): "A Jupiter-mass companion to a solar-type star"
- Adams and Laughlin (1997): "A dying universe: the long-term fate and evolution of astrophysical objects"
- Lubin (2016): "A roadmap to interstellar flight"
Real basis
No signal from an extraterrestrial civilization has ever been confirmed; this is the Fermi paradox. Brin's 1983 “Great Silence” discussed the various reasons for silence systematically.
Permanent silence: Turn off all radio stations, bring your waste heat down to ambient temperature, and make your star look like any other. In a universe with relativistic kinetic weapons, “not being found” is the most reliable survival strategy: a 1-tonne object hitting at 0.1 c carries energy equal to about 100 million tonnes of TNT.
The Dark Forest (Liu Cixin, 2008), the science: the Fermi paradox is a real scientific question; the “dark forest” is one literary explanation, and can be neither confirmed nor refuted.
Related research
These studies relate to this topic but are not direct proof of this page.
The first exoplanet: A giant planet was found around 51 Pegasi, circling its star in 4 days. The solar system was no longer unique. Nobel Prize 2019.
Source: Mayor & Queloz, Nature 1995, "A Jupiter-mass companion to a solar-type star"
Searching for interstellar signals: Two physicists suggested listening for alien signals with radio telescopes near hydrogen's 21 cm frequency, launching SETI.
Source: Cocconi & Morrison, Nature 1959, "Searching for interstellar communications"
Dyson sphere: A sufficiently advanced civilization might wrap its star, and we could find it through anomalous infrared radiation.
Source: Dyson, Science 1960, "Search for artificial stellar sources of infrared radiation"
Scale of civilizations: Sorts civilizations into three types by the energy they can use: planetary, stellar and galactic.
Source: Kardashev, Soviet Astronomy 1964, "Transmission of information by extraterrestrial civilizations"
Light sails to the stars: Pushing ultralight light sails with a ground-based laser array could accelerate probes to one fifth the speed of light.
Source: Lubin, Journal of the British Interplanetary Society 2016, "A roadmap to interstellar flight"
Where are they?: If alien civilizations were common, they should already fill the galaxy. From this Hart argued that we may be the first.
Source: Hart, Quarterly Journal of the Royal Astronomical Society 1975, "An explanation for the absence of extraterrestrials on Earth"
The last chapter of the universe: Worked out the fate of the universe over trillions of years and beyond: stars go out, protons perhaps decay, and black holes finally evaporate.
Source: Adams & Laughlin, Reviews of Modern Physics 1997, "A dying universe: the long-term fate and evolution of astrophysical objects"
Game lore (fictional)
- The “dark forest” is a literary explanation proposed by Liu Cixin, not a scientific conclusion.
- Summary of the novel The Dark Forest: Facing an enemy that is bound to arrive, humanity stakes its hopes on four “Wallfacers”. One of them derives a cold cosmic sociology: every civilization is an armed hunter.
Related open-source projects
BOINC volunteer computing
2.49K stars
BOINC/boinc
Lets your home computer help scientists crunch numbers while idle. SETI@home used it to analyze radio telescope data in the search for alien signals, and stopped sending new tasks in 2020.