The dark forest hypothesis is the conjecture that many alien civilizations exist throughout the universe, but they are both silent and hostile, maintaining their undetectability for fear of being destroyed by another hostile and undetected civilization.[1] In this framing, it is presumed that any space-faring civilization would view any other intelligent life as an inevitable threat,[2] and thus destroy any nascent life that makes itself known. As a result, the electromagnetic spectrum would be relatively quiet, without evidence of any intelligent alien life, as in a "dark forest" filled with "armed hunter(s) stalking through the trees like ghosts".[3][4]

Background

Main article: Fermi paradox

There is no reliable or reproducible evidence that aliens have visited or attempted to contact Earth.[5][6] No transmissions and little evidence of intelligent extraterrestrial life have been detected or observed. This runs counter to the knowledge that the universe is filled with a very large number of planets, some of which likely hold conditions hospitable for life. Life typically expands until it fills all available niches.[7] These contradictory facts form the basis for the Fermi paradox, of which the dark forest hypothesis is one proposed solution.

Relationship to other proposed Fermi paradox solutions

The dark forest hypothesis is distinct from the berserker hypothesis in that many alien civilizations would still exist if they kept silent. It can be viewed as a special example of the Berserker hypothesis, if the 'deadly berserker probes' are (due to resource scarcity) only sent to star systems that show signs of intelligent life.[8]

Game theory

The dark forest hypothesis is a special case of the "sequential and incomplete information game" in game theory.[9][10][11]

In game theory, a "sequential and incomplete information game" is one in which all players act in sequence, one after the other, and none are aware of all available information.[12] In the case of this particular game, the only win condition is continued survival.[8] An additional constraint in the special case of the "dark forest" is the scarcity of vital resources.[10] The "dark forest" can be considered an extensive-form game with each "player" possessing the following possible actions: destroy another civilization known to the player; broadcast and alert other civilizations of one's existence; or do nothing.[9]

Science fiction versions

The hypothesis was described by astronomer and author David Brin in his 1983 summary of the arguments for and against the Fermi paradox,[13] for which this hypothesis is one potential solution.[8][10] In 1987, science fiction author Greg Bear explored the concept in his novel The Forge of God.[14] The term "dark forest" was coined for the idea in 2008 by science fiction author Liu Cixin in his novel The Dark Forest.[15][16]

In The Forge of God, humanity is likened to a baby crying in a hostile forest: "There once was an infant lost in the woods, crying its heart out, wondering why no one answered, drawing down the wolves."[17] One of the characters explains, "We've been sitting in our tree chirping like foolish birds for over a century now, wondering why no other birds answered. The galactic skies are full of hawks, that's why. Planetisms that don't know enough to keep quiet, get eaten."[18]

In Liu Cixin's novel, the dark forest hypothesis is introduced by the character Ye Wenjie, while visiting her daughter's grave. She introduces three key axioms to a new field she describes as "cosmic sociology":[19][8]

  1. "Suppose a vast number of civilizations distributed throughout the universe, on the order of the number of observable stars. Lots and lots of them. Those civilizations make up the body of a cosmic society. Cosmic sociology is the study of the nature of this super-society."[19] (based on the Drake equation)[16]
  2. Suppose that survival is the primary need of a civilization.
  3. Suppose that civilizations continuously expand over time, but the total matter in the universe remains constant.

The only logical conclusion from the acceptance of these axioms, Ye says, is that any intelligent life in the universe will be pitted against all other life in the struggle for survival.[19][8]

References

  1. ^ Paradis, Justine (18 February 2022). "Outside/In[box]: What is the Dark Forest Theory?". New Hampshire Public Radio. Retrieved 18 October 2022.
  2. ^ Vakoch, Douglas A. (3 April 2017). "Hawking's fear of an alien invasion may explain the Fermi Paradox". Theology and Science. 15 (2): 134–138. doi:10.1080/14746700.2017.1299380. S2CID 219627161. Retrieved 18 October 2022.
  3. ^ Liu, Cixin (2015). The dark forest (First ed.). New York. p. 484. ISBN 9780765377081.((cite book)): CS1 maint: location missing publisher (link)
  4. ^ Hsu, Jeremy (October 31, 2015). "China's 'Dark Forest' Answer to 'Star Wars' Optimism". Discover. Archived from the original on October 17, 2022.
  5. ^ Tingay, Steven (May 19, 2022). "Is there evidence aliens have visited Earth? Here's what's come out of US congress hearings on 'unidentified aerial phenomena'". The Conversation. Retrieved 27 October 2022.
  6. ^ Kolbert, Elizabeth (14 January 2021). "Have We Already Been Visited by Aliens?". The New Yorker. Retrieved 27 October 2022.
  7. ^ Papagiannis, Michael D. (1978). ""Are We All Alone, or could They be in the Asteroid Belt" by Michael D. Papagiannis, Quarterly Journal of the Royal Astronomical Society, Vol. 19, p.277". Quarterly Journal of the Royal Astronomical Society. 19: 277. Bibcode:1978QJRAS..19..277P. Archived from the original on 2019-01-07. Retrieved 2022-10-27.
  8. ^ a b c d e Williams, Matt (7 January 2021). "Beyond "Fermi's Paradox" XVI: What is the "Dark Forest" Hypothesis?". Universe Today. Retrieved 18 October 2022.
  9. ^ a b Yasser, Shehab (12 October 2020). "Aliens, The Fermi Paradox, And The Dark Forest Theory". Project Nash. Retrieved 18 October 2022.
  10. ^ a b c Konior, Bogna (6 July 2020). "The Dark Forest: Theory of the Internet". BLOK Magazine. ISSN 2719-4973. Retrieved 18 October 2022.
  11. ^ Fudenberg, Drew; Tirole, Jean (April 1983). "Sequential Bargaining with Incomplete Information". The Review of Economic Studies. 50 (2): 221. doi:10.2307/2297414. JSTOR 2297414. Retrieved 18 October 2022.
  12. ^ Ausubel, Lawrence M.; Cramton, Peter; Deneckere, Raymond J. (2002). "Bargaining with incomplete information". In Aumann, Robert; Hart, Sergiu (eds.). Handbook of Game Theory with Economic Applications. Vol. 3. pp. 1897–1945. doi:10.1016/S1574-0005(02)03013-8. ISBN 978-0-444-89428-1.
  13. ^ Brin, G. D. (1 September 1983). "The Great Silence - the Controversy Concerning Extraterrestrial Intelligent Life". Quarterly Journal of the Royal Astronomical Society. 24: 283–309. Bibcode:1983QJRAS..24..283B. ISSN 0035-8738. Retrieved 18 October 2022.
  14. ^ Cramer, John (1987). "Self-Reproducing Machines From Another Planet : THE FORGE OF GOD by Greg Bear". Los Angeles Times.
  15. ^ Kevra, Derek (11 October 2022). "Dark Forest theory: should we try to contact aliens?". FOX 2 Detroit. Retrieved 18 October 2022.
  16. ^ a b Yu, C. (1 January 2015). "The Dark Forest Rule: One Solution to the Fermi Paradox". Journal of the British Interplanetary Society. 68: 142–144. Bibcode:2015JBIS...68..142Y. ISSN 0007-084X. Retrieved 18 October 2022.
  17. ^ "The forge of God quotes". Goodreads.
  18. ^ Cramer, John (1987). "Self-Reproducing Machines From Another Planet : THE FORGE OF GOD by Greg Bear". Los Angeles Times.
  19. ^ a b c Liu, Cixin (2015). "Chapter 1". The dark forest (First ed.). New York: Tor. ISBN 9780765386694.
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