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] It is one of many possible explanations of the Fermi paradox, which contrasts the lack of contact with alien life with the potential for such contact. The hypothesis derives its name from Liu Cixin's 2008 novel The Dark Forest , [2] although the concept predates the novel. [3] [4]
There is no known reliable or reproducible evidence that aliens have visited or attempted to contact Earth. No transmissions and no firm evidence of intelligent extraterrestrial life have been detected or observed. [5] [6] [3] : 2 This runs counter to the general observations, that:
These contradictory facts form the basis for the Fermi paradox. [3]
The "dark forest" hypothesis presumes that any space-faring civilization would view any other intelligent life as an inevitable threat 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. [8] [9]
A similar hypothesis, under the name "deadly probes", was described by astronomer and author David Brin in his 1983 summary of the arguments for and against the Fermi paradox. [10]
The name of the hypothesis derives from Liu Cixin’s 2008 novel The Dark Forest, [11] as in a "dark forest" filled with "armed hunter(s) stalking through the trees like ghosts". [12] [13] According to the dark forest hypothesis, since the intentions of any newly contacted civilisation can never be known with certainty, then if one is encountered, it is best to shoot first and ask questions later, in order to avoid the potential extinction of one’s own species. The novel provides a detailed investigation of Liu's concerns about alien contact. [2]
The Berserker hypothesis, also known as the deadly probes scenario, proposes self-reproducing machines that would seek to destroy organic life. [3] : 112 The name derives from short stories by Fred Saberhagen written in the 1960s. The dark forest hypothesis is distinct from the Berserker hypothesis in that under the former, many alien civilizations could still exist provided they keep silent. The former can be viewed as a special case of the latter, if the deadly probes are (e.g. due to resource scarcity) only sent to star systems that show signs of intelligent life. [8]
The dark forest hypothesis is a special case of the "sequential and incomplete information game" in game theory. [14] [9] [15]
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. [16] 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. [9] 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. [14]
In addition to Fred Saberhagen's Berserker novels, [3] : 112 variations of these ideas have been used in other science fiction stories. In 1987, science fiction author Greg Bear explored this concept that he called a "vicious jungle" in his novel The Forge of God . [17] 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." 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." [4]
The term "dark forest" was coined for the idea in 2008 by science fiction author Liu Cixin in his novel The Dark Forest . [18] [2] 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]
The only logical conclusion from the acceptance of these axioms as well as two other considerations, "chain of suspicion" and "technological explosion", according to the character Ye was talking to, is that any civilization that revealed itself will be considered as an imminent existential threat by at least some of the other civilizations, among which some will then proceed to destroy the civilization that makes itself known. [19] [8]
In the third book of the trilogy, the perspective of the hunters in The Dark Forest is further illustrated through an alien character called Singer, who thinks that intelligent life that does not fear the dark forest would "expand and attack without fear". [20] In other words, dark-forest-fearing civilizations are benign, civilizations that would reveal themselves are evil, and hunters are enforcers and protectors.
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. Those affirming the paradox generally conclude that if the conditions required for life to arise from non-living matter are as permissive as the available evidence on Earth indicates, then extraterrestrial life would be sufficiently common such that it would be implausible for it not to have been detected yet.
The Berserker series is a series of space opera science fiction short stories and novels by Fred Saberhagen, in which robotic self-replicating machines strive to destroy all life.
Extraterrestrial intelligence (ETI) refers to hypothetical intelligent extraterrestrial life. No such life has ever been verifiably observed to exist. The question of whether other inhabited worlds might exist has been debated since ancient times. The modern form of the concept emerged when the Copernican Revolution demonstrated that the Earth was a planet revolving around the Sun, and other planets were, conversely, other worlds. The question of whether other inhabited planets or moons exist was a natural consequence of this new understanding. It has become one of the most speculative questions in science and is a central theme of science fiction and popular culture.
The concept of self-replicating spacecraft, as envisioned by mathematician John von Neumann, has been described by futurists and has been discussed across a wide breadth of hard science fiction novels and stories. Self-replicating probes are sometimes referred to as von Neumann probes. Self-replicating spacecraft would in some ways either mimic or echo the features of living organisms or viruses.
Michael H. Hart is an American astrophysicist, author and white nationalist. Since 1978, he has published five books, most notably of the best-selling work, The 100: A Ranking of the Most Influential Persons in History.
The zoo hypothesis speculates on the assumed behavior and existence of technologically advanced extraterrestrial life and the reasons they refrain from contacting Earth. It is one of many theoretical explanations for the Fermi paradox. The hypothesis states that extraterrestrial life intentionally avoids communication with Earth to allow for natural evolution and sociocultural development, and avoiding interplanetary contamination, similar to people observing animals at a zoo. The hypothesis seeks to explain the apparent absence of extraterrestrial life despite its generally accepted plausibility and hence the reasonable expectation of its existence.
The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.
Dark Forest may refer to:
Active SETI is the attempt to send messages to intelligent extraterrestrial life. Active SETI messages are predominantly sent in the form of radio signals. Physical messages like that of the Pioneer plaque may also be considered an active SETI message. Active SETI is also known as METI.
The planetarium hypothesis, conceived in 2001 by Stephen Baxter, attempts to provide a solution to the Fermi paradox by holding that our astronomical observations represent an illusion, created by a Type III civilization capable of manipulating matter and energy on galactic scales. He postulates that we do not see evidence of extraterrestrial life because the universe has been engineered so that it appears empty of other life.
Remembrance of Earth's Past is a science fiction novel series by Chinese writer Liu Cixin. The series is also popularly referred to as Three-Body from part of the title of its first novel, The Three-Body Problem. The series details humanity's discovery of and preparation for an alien invasion force from the planet Trisolaris.
The Dark Forest is a 2008 science fiction novel by the Chinese writer Liu Cixin. It is the sequel to the Hugo Award-winning novel The Three-Body Problem in the trilogy titled Remembrance of Earth's Past, but Chinese readers generally refer to the series by the title of the first novel. The English version, translated by Joel Martinsen, was published in 2015. The novel is about the dark forest hypothesis, a possible solution to the Fermi paradox, though similar theories have been described as early as 1983.
The aestivation hypothesis is a hypothesized solution to the Fermi paradox conceived in 2017 by Anders Sandberg, Stuart Armstrong and Milan M. Ćirković. The hypothesis, published on 27 April 2017, suggests advanced alien civilizations may be storing energy and aestivating, until the universe cools to better make use of the stored energy to perform tasks.
METI International, known simply as METI, is a non-profit research organization founded in July 2015 by Douglas Vakoch that creates and transmits interstellar messages to attempt to communicate with extraterrestrial civilizations. It is based in San Francisco, California.
The following outline is provided as an overview of and topical guide to extraterrestrial life:
The Berserker hypothesis, also known as the deadly probes scenario, is the idea that humans have not yet detected intelligent alien life in the universe because it has been systematically destroyed by a series of lethal Von Neumann probes. The hypothesis is named after the Berserker series of novels (1963–2005) written by Fred Saberhagen.
The Hart–Tipler conjecture is the idea that an absence of detectable Von Neumann probes is contrapositive evidence that no intelligent life exists outside of the Solar System. This idea was first proposed in opposition to the Drake equation in a 1975 paper by Michael H. Hart titled "Explanation for the Absence of Extraterrestrials on Earth". Assuming that the probes traveled at 1/10 the speed of light and that no time was lost in building new ships upon arriving at the destination, Hart surmised that a wave of Von Neumann probes could cross the galaxy in approximately 650,000 years, a comparatively minimal span of time relative to the estimated age of the universe at 13.7 billion years. Hart’s argument was extended by cosmologist Frank Tipler in his 1981 paper entitled "Extraterrestrial intelligent beings do not exist".
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Stephen Webb is a physicist and author of numerous popular science and math books, as well as academic publications. Webb was educated at Bristol University and, as a graduate student, attended Manchester University. Webb is currently on the academic staff at the University of Portsmouth, and is a presenter of numerous science-related non-academic talks and academic lectures. In 2018, Webb was a featured science speaker at the annual TED conference.