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The Dark Forest Rule: One Solution to the Fermi Paradox

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Abstract

The "dark forest rule" proposed by Cixin Liu, a Chinese science fiction writer, offers a new explanation for the Fermi paradox and is proximate to the "state of nature" detailed by Hobbes. In this paper, the "dark forest rule" is introduced based on the "state of nature". Furthermore, the significance of scientific and technological levels in interstellar communication is discussed. Finally, a revised dark forest rule is put forward: the use of concealment to avoid unknown risks.
1
e Dark Forest Rule: One Solution to the Fermi Paradox
JBIS, Vol. 67, pp.??-??, 2014
THE DARK FOREST RULE: ONE SOLUTION TO THE FERMI PARADOX
1. INTRODUCTION
In 1950, the physicist Enrico Fermi asked “where are they?”.
This question, uttered in conversation, developed into the
Fermi paradox that has sparked massive debate. The paradox
posits that, following mathematical probability, technologically
advanced civilizations should exist somewhere in the universe.
If these civilizations are hundreds of millions of years more
advanced than that on Earth, then signs of these civilizations
should be apparent. Thus the famous words, “where are they?”
David Brin, a scientist famous for his science ction stories and
his opposition to Messaging to Extra-Terrestrial Intelligence
(METI), proposed in 1983 [1] the possibility of an unknown
risk faced by other civilizations in the universe, forcing them
to maintain silence. This results in human beings failing to
discover any foreign civilization, which he termed “the Great
Silence”. Brin posits that METI projects are futile calls in the
forest of the universe.
The Three Body trilogy by Cixin Liu [2], a Chinese science
ction writer, also offers a detailed interpretation of the
Fermi paradox: the dark forest rule. Representing an effective
reiteration and expansion of Brin’s position, the dark forest rule
is based on two hypotheses and two concepts.
The two basic hypotheses are as follows: 1) survival is
the primary requirement of civilization; 2) civilization grows
and expands continuously, whereas the total cosmic materials
remain constant. The two basic concepts are “suspicion chain”
and “technology explosion”. The “suspicion chain” is caused
by poor communication between different civilizations in the
universe, resulting in civilizations distrusting each other. The
concept of “technology explosion” indicates that technologies
in civilizations may achieve explosive breakthroughs and
development at any time, which are beyond the accurate
estimation of any distant civilization with its own technological
level. Based on these two hypotheses, civilizations in the
universe are competing for resources. Furthermore, and any
civilization can neither trust others nor be condent about the
advancement of its technology due to the “suspicion chain”
and “technology explosion”. Therefore, the universe is akin to
a dark forest where the law of the jungle applies.
At the end of Dark Forest, part of the Three Body trilogy,
CHAO YU
School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China.
Email: 653001002@qq.com
The “dark forest rule” proposed by Cixin Liu, a Chinese science ction writer, offers a new explanation for the Fermi paradox
and is proximate to the “state of nature” detailed by Hobbes. In this paper, the “dark forest rule” is introduced based on the
“state of nature”. Furthermore, the signicance of scientic and technological levels in interstellar communication is discussed.
Finally, a revised dark forest rule is put forward: the use of concealment to avoid unknown risks.
Keywords: Dark forest rule, state of nature, science and technological level, Fermi paradox
Cixin Liu explained the Fermi paradox clearly by the leading
character Luoji: “Universe is a dark forest. Every civilization is
a hunter with gun in hand and he sneaks in the forest. He must
be careful enough as there are other hunters in the forest. If he
discovered other lives, he can only do one thing: shoot it. In this
forest, other lives are hell and constant threats. Any life that
will expose his existence will be killed soon. This is the picture
of universe civilizations” [2]. These words recall the state of
nature, as proposed by Thomas Hobbes [3].
2. DARK FOREST AND HOBBES FOREST
Owing to their similarities, the “dark forest rule” of Cixin Liu
may be inspired from the “state of nature” of Hobbes. To gain
an improved understanding of the development of the “dark
forest rule”, we reviewed the description of state of nature in
the Leviathan [3]:
(1) “But the most frequent reason why men desire to hurt
each other, ariseth hence, that many men at the same
time have an Appetite to the same thing; which yet very
often they can neither enjoy in common, nor yet divide
it; whence it follows that the strongest must have it, and
who is strongest must be decided by the Sword” (ch. 6
[3]).
Therefore the rst foundation of naturall Right is this,
That every man as much as in him lies endeavor to
protect his life and members” (ch. 7 [3]).
Several religions (e.g., Buddhism and Christianity) advocate
the eternity of the soul. They believe that after physical death,
the destination of the soul depends on the acts of the person
during their lifetime. This results in the teaching that hell
after death is the most terrible consequence for humans, as
opposed to suffering during physical life. Hobbes advocates
the opposite. He declares that death is the most terrible thing
and when facing death, survival is paramount, as opposed to
reincarnation and retribution.
Therefore, despite the assumption that numerous exploratory
civilizations, moral-advocating civilizations, or even seless
civilizations exist in the universe, these will be inferior to
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Chao Yu
survivalist civilizations. For example, the Roman civilization
was defeated by the Goths and the Song Dynasty was defeated
by Mongolian cavalry.
These examples are in line with the “survival is the primary
requirement of civilization” tenet of the “dark forest rule”.
(2) But because it is in vaine for a man to have a Right to
the end, if the Right to the necessary means be denied
him; it follows, that since every man hath a Right to
preserve himself, he must also be allowed a Right to use
all the means, and do all the actions, without which He
cannot Preserve himself” (ch. 8 [3]).
Now whether the means which he is about to use, and the
action he is performing, be necessary to the preservation
of his Life, and Members, or not, he Himself, by the right
of nature, must be judge; for say another man, judge
that it is contrary to right reason that I should judge
of mine own peril: why now, because he judge of what
concerns me, by the same reason, because we are equal
by nature, will I judge also of things which doe belong
to him; therefore it agrees with the right reason (that is)
it is the right of nature that I judge of his opinion, (i.e.)
whether it conduce to my preservation, or not” (ch. 9
[3]).
In this sense, based on (1), resources in the world are limited,
because people who care little about life will be uninterested in
conquest.
Limited resources means that innite wealth expansion does
not necessarily correspond to willingness of people to engage
in conict with others. On the contrary, this stems from the
uncertainty of the necessities required for survival, a universal
possibility. Thus, Hobbes argues that for survival, in the state
of nature, each individual has universal access, inevitably
resulting in a state of war.
The dark forest rule also includes a concept of limited
resources: “civilizations are expanding, while total universal
materials remain same”. However, a signicant difference can
be found between these two concepts. Cixin Liu stated that
civilizations are expanding continuously, whereas Hobbes
persuaded human beings not to expand their needs because
any private need may conict with those of others. From
this perspective, the Cixin Liu concept can be viewed as an
updated Malthus Theory rather than one inspired by Hobbes.
If we investigate these two concepts of limited resources by
using the second law of thermodynamics, both civilizations and
human being are open systems that require energy continuously
for survival. Activities of civilization will accelerate the rate of
entropy increase. If the universe is viewed as a closed system,
entropy increase is irreversible. Thus, other civilizations must
be eliminated to slow down the heat death of the universe.
(3) “And from this difdence of one another, there is no
way for any man to secure himself so reasonable as
anticipation; that is, by force, or wiles, to master the
persons of all men he can so long till he see no other
power great enough to endanger him: and this is no
more than his own conservation requireth, and is
generally allowed” (ch. 13 [3]).
So that in the nature of man, we nd three principal
causes of quarrel. First, competition; secondly,
difdence; thirdly, glory. The rst maketh men invade
for gain; the second, for safety; and the third, for
reputation. The rst use violence, to make themselves
masters of other men’s persons, wives, children, and
cattle; the second, to defend them; the third, for tries,
as a word, a smile, a different opinion, and any other
sign of undervalue, either direct in their persons or by
reection in their kindred, their friends, their nation,
their profession, or their name.”(ch.13 [3])
In the dark forest rule, the “suspicion chain” setting is similar
to the prisoner’s dilemma. In the universe, civilizations are too
distant from each other to facilitate real-time communication,
due to the light barrier. In addition, the potential technology
explosion results in considerable dangers in positive
communication, thus compelling civilization that discover
others (referred henceforth as “discoverer”) to be aggressive
and eliminate it immediately. In the state of nature of Hobbes,
human beings will be suspicious for survival and compete for
interests. When this practice becomes the basis of all behaviors
of every human being, they will deduce the behaviors of others
with maximum malevolence to protect from threats. Therefore,
both the dark forest rule and the state of nature of Hobbes
indicate that weakening others and conducting self-protection
is the safest strategy.
3. DISCUSSION
Hobbes advocates the physical and psychological equality
of human beings. “NATURE hath made men so equal in the
faculties of body and mind as that, though there be found one
man sometimes manifestly stronger in body or of quicker mind
than another, yet when all is reckoned together the difference
between man and man is not so considerable as that one man
can thereupon claim to himself any benet to which another
may not pretend as well as he. For as to the strength of body,
the weakest has strength enough to kill the strongest, either by
secret machination or by confederacy with others that are in
the same danger with himself...From this equality of ability
ariseth equality of hope in the attaining of our ends” (ch.13
[3]). Therefore, in the state of nature, Hobbes proposed that
protection can be achieved by social contracts.
However, interstellar communication is characteristic of
technological inequality between civilizations. Social contracts
are inapplicable owing to discrepancies in technological levels
and the perceptions of such. Further discussions on the dark
forest rule are also necessary:
1. Suspicion chain: Two ends of the suspicion chain are
equal. In other words, a suspicion chain is generally
formed between two civilizations with similar
technological level, but cannot be formed between those
with a qualitative technological gap. The evolution
span of civilizations runs through the whole space-
time axis. A considerable technological gap is universal
between different civilizations; civilizations with
similar technological levels meeting each other is less
likely because they may have been discovered by more
advanced civilizations.
2. Technological explosion: Although low-level
civilizations may achieve technological explosion, the
safest strategy for discoverers is to reduce contact with
the outside instead of observing or eliminating them.
Discoverers cannot ensure that their attacks will not
be discovered by more advanced civilizations in the
universe because all behaviours may be captured by
them.
3
e Dark Forest Rule: One Solution to the Fermi Paradox
3. Resources: In terms of entropy increase, not all
civilizations will accelerate entropy increase.
Exceptions include civilizations that could not coexist
with their environment for an extended period. If a
civilization could develop a permanent cycle with
external resources, limited entropy increase will occur.
The extant civilization on Earth is characterized as an
abundant resource-consuming low-level civilization.
The ideal high-level civilization can maintain the
slowest entropy increase based on appropriate resources
recycling rather than maximum energy consumption.
The most reasonable high-level civilization can form
a cycle independently and use tremendous energies to
slow down the entropy increase by reform, assimilation
and integration.
4. Aggressive attack: Although discoverers may incur
reduced costs for aggressive attack compared with
detection and communication, they will suffer
signicantly more risks. For example, in a dark forest,
a child sits at a campre and sings, leading to many
hunters aiming at the child. Despite the possibility
that the child is a potential risk, a hunter shooting the
child may involve a more dangerous risk; other high-
level hunters may search for the shooter. From the
perspective of higher-level hunters, the shooter is on the
same level as the child even though the former used the
most advanced technologies and concealment. In the
dark forest rule, a low-level civilization is akin to the
child, discoverers are akin to the shooter and higher-
level civilizations are akin to the higher-level hunters.
We can also assume that several violent civilizations exist
in the universe. If these civilizations are discovered by others,
they may be: 1) just discovered (original probability); or 2)
discovered when attacking other civilizations. For the second
situation, discoverers believe that they are more likely to be
attacked if discovered by these violent civilizations in the future.
Then, discoverers with far more advanced technology will
either eliminate these violent civilizations or remain inactive,
considering threats from unknown higher-level civilizations.
Furthermore, these violent civilizations may attack each
other. In summary, violent civilizations are more likely to be
eliminated compared to concealed civilizations, thus resulting
in the lower survival probability of violent genes and higher
survival probability of concealing genes. This is the state of the
present universe.
Therefore, in the survival-oriented dark forest rule,
concealment is paramount. As a result, technological inequality
is the top priority of universe sociology, because technological
level determines the status of civilizations in the universe.
The author proposed a new survive-oriented dark forest rule:
concealment rather than active communication with foreign
civilizations.
4. CONCLUSIONS
The dark forest rule, one solution to the Fermi paradox, is rooted
in the state of nature of Hobbes. Therefore, the original rough
law of universe sociology is not a general inexorable law of the
universe, but only valid under unique conditions. However, this
does not imply that our universe is a kind universe.
In the revised dark forest rule, each civilization spares no
effort to conceal themselves in the universe to avoid unknown
risks, thus forming the present great silence. To be more
imaginative, certain supernova explosions we have observed
may be attacks or warnings of top civilizations to exposed
civilizations. These questions can only be answered when
we reach a higher technological level; the order of universe
civilizations can only be determined by top civilizations rather
than low-level civilizations such as ours. When we achieve such
a technological breakthrough, our civilization will conduct a
qualitative change, changing our views as well. The author
believes that a harmonious sense of beauty occurs between the
basic rule and basic form in the universe.
1. D. Brin, “The Great Silence - the Controversy Concerning Extraterrestrial
Intelligent Life”, Quarterly Journal of the Royal Astronomical Society,
24, pp.283-309, 1983.
REFERENCES
(Received 10 April 2014; Accepted 20 April 2015)
* * *
2. Liu Cixin, “Three-body”, Chongqing Publishing Group, Chongqing,
2008.
3. T. Hobbes, “Leviathan”, Dutton, New York, 1950.
... There have been proposed a series of possible solutions to the FP. In particular, Yu [3] suggests a solution based on an assumption that civilizations by exocomets [12], the discovery of the Tabby's star has stimulated a further study in this eld and in a certain sense, it has revived the Dysonian SETI. Recently, by taking into account the observational data of the Gaia mission, Zackrisson, et al. [13] emphasised peculiarity of the object TYC 6111-1162-1, which, according to the authors, deserves further investigation. ...
... Consequently, likewise the previous case, the variability timescale is expressed as follows, 3 ...
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