Remembrance of Earth's Past

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Remembrance of Earth's Past
United States edition book covers by Tor Books. United Kingdom book covers have slightly different designs.

AuthorLiu Cixin[a]
Original title
地球往事; Dìqiú Wǎngshì
TranslatorKen Liu (books 1 and 3)
Joel Martinsen (book 2)
LanguageMandarin Chinese
GenreHard science fiction and Alien invasion
PublisherChongqing Publishing Group (Chinese edition)
PublishedMay 2008 – November 2010 (original trilogy)
2011 (fanfiction spin-off)
Published in EnglishNovember 11, 2014 – September 19, 2016 (original trilogy)
July 16, 2019 (spin-off)
Media type
No. of books3
Remembrance of Earth's Past
Simplified Chinese地球往事
Traditional Chinese地球往事
Literal meaningEarth's Past
Alternative Chinese name
Simplified Chinese三体
Traditional Chinese三體
Literal meaningThree-Bodies

Remembrance of Earth's Past (Chinese: 地球往事; pinyin: Dìqiú Wǎngshì; lit. 'Earth's Past') is a science fiction 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 (Chinese: 三体; pinyin: Sān Tǐ; lit. 'Three-Body').[2] The series details humanity's discovery of and preparation for an alien invasion force from the planet Trisolaris.


Original trilogy[edit]

The books in the Remembrance of Earth's Past trilogy are:[3]

  • The Three-Body Problem (三体), 2006; English translation by Ken Liu published by Tor Books on November 11, 2014.[4] Also known in Chinese as "三体I"
  • The Dark Forest (黑暗森林), 2008; English translation by Joel Martinsen published by Tor Books on August 11, 2015.[4] Also known in Chinese as "三体II"
  • Death's End (死神永生), November 2010; English translation by Ken Liu published by Tor Books on September 20, 2016[4] (September 19 in digital stores).[5] Also known in Chinese as "三体III"

Extended series[edit]

  • The Redemption of Time (观想之宙), originally posted to an internet forum as fan fiction in 2010 by Li Jun writing as Baoshu, that was later published by Chongqing Press, the original trilogy publisher, with the permission of Liu Cixin in 2011, as Three-Body X: Aeon of Contemplation (Chinese: 三体X·观想之宙; pinyin: Sān Tǐ X · Guān Xiǎng Zhī Zhòu). It was translated by Ken Liu into English for Tor Books and published on July 16, 2019, as The Redemption of Time.[6]

Science fiction concepts[edit]


Sophons are created from eleven-dimensional protons dimensionally unfolded down to two-dimensional protons with Trisolaran particle accelerators. While in the two-dimensional form, they are embedded with circuitry to create a supercomputer. Once online, the embedded supercomputer could control the proton's dimensional level and could fold itself back into an eleven-dimensional proton. To be seen with the naked eye, the protons could unfold themselves down to a fourth-, fifth-, or sixth-dimensional form, becoming larger with each subsequent lower dimension without changing mass. They can visually record anything and thus their secondary purpose is to act as surveillance devices, beaming the information they gather back to another sophon instantaneously via quantum entanglement. Their primary purpose for their Trisolaran manufacturers is to disrupt Earth's particle accelerators, capable of straying into the paths of fired particles and scrambling the results of experiments before re-assembling, effectively blocking advancement of the science. Since they can move through three-dimensional space at the speed of light, a single sophon is capable of disrupting all of Earth's particle accelerators.


Trisolaran space probes are covered in a strong interaction force material. Due to this material, they are stronger than any material in the solar system and thus are impervious to any physical attack. Their propulsion system is capable of moving in any direction in 3D space. Seemingly unaffected by inertia, they can make sudden impossible turns, and their primary method of attack is to simply smash through objects.

Curvature propulsion[edit]

Simplified in a demonstration as a piece of soap attached to a paper boat on water, with the soap reducing the water tension at its end, and the water tension disparity propelling the boat. Traveling through previous paths slows the boat down due to decreased surface tension. Curvature Propulsion is a method of acceleration to lightspeed that utilizes the same concept, via reducing the speed of light it is possible to drag a ship through space at light speed, while its wake is a reduced light-speed region of space.


Humanity by the time of Dark Forest has developed cryogenic technology, capable of preserving a human life, unaging, for hundreds of years barring certain genetic disorders. Initially, it is viewed as a sign of inequality before it is fully developed, viewed as a way for the rich to simply skip through the centuries to eras of more advanced technology, peace, and human development. With the advent of the Trisolaran invasion, however, it becomes a near-worthless technology in terms of demand, as people prefer to die naturally in a world still free from Trisolaris rather than skip ahead to doomsday. Because of this, only researchers and certain high-value staff make use of cryogenics to skip through time.

Cosmic sociology[edit]

The study of theoretical interactions between cosmic civilizations. This area of study is first proposed by the character Ye Wenjie in conversation with future Wallfacer Luo Ji. Ye Wenjie proposes two axioms of cosmic sociology: "First: Survival is the primary need of civilization. Second: Civilization continuously grows and expands, but the total matter in the universe remains constant."[7] After becoming a Wallfacer, Luo Ji uses the axioms provided by Ye Wenjie to invent the dark-forest theory of the universe and the idea of dark-forest deterrence to stop the Trisolaran invasion.[8]


The Three-Body Problem (Chinese: 三体) is an indefinitely postponed Chinese science fiction 3D film,[9] adapted from The Three-Body Problem, directed by Fanfan Zhang, and starring Feng Shaofeng and Zhang Jingchu.[10][11][12]

A Chinese Minecraft machinima animated series based on the series began releasing on February 27, 2014.[13]

A Chinese animated series based on The Dark Forest aired from December 10, 2022, to March 25, 2023.[14]

A Chinese live-action series based on The Three-Body Problem aired from January 15 to February 3, 2023.[15]

A series based on The Three-Body Problem has been ordered by Netflix, with David Benioff, D. B. Weiss, and Alexander Woo set to write and executive produce.[16]

A 3-part documentary series entitled Rendezvous with the Future which explores the science behind Liu Cixin's science fiction was produced by BBC Studios and released by Bilibili in China in November 2022.[17] The series includes an extensive interview with Liu Cixin and covers many ideas featured in the Remembrance of Earth's Past such as: messaging extraterrestrial civilisations; gravitational wave transmitter; dark forest hypothesis; space elevator; artificial hibernation; fusion drive; and circumsolar particle accelerator.

See also[edit]


  1. ^ Credited as Cixin Liu in the English editions
  1. ^ The Three-Body Problem (Remembrance of Earth's Past Book 1. Tor Books. 11 November 2014. Retrieved September 5, 2019.
  2. ^ Liu, Cixin (7 May 2014). "The Worst of All Possible Universes and the Best of All Possible Earths: Three Body and Chinese Science Fiction". Retrieved 8 May 2014.
  3. ^ "Three-Body Introduction". Archived from the original on 2015-03-03.
  4. ^ a b c Liu, Ken. "Three Body". Retrieved September 5, 2019.
  5. ^ Liu, Cixin (20 September 2016). Death's End. ISBN 9781466853454. Retrieved September 5, 2019. {{cite book}}: |website= ignored (help)
  6. ^ Andrew Liptak (19 October 2018). "How a fan fiction for Cixin Liu's Three-Body Problem became an official novel". The Verge.
  7. ^ Liu, Cixin (2019). The Dark Forest. Translated by Martinsen, Joel. New York: Tor Books. p. 13. ISBN 978-0-7653-8669-4.
  8. ^ Liu, Cixin (2019). The Dark Forest. Translated by Martinsen, Joel. New York: Tor Books. pp. 479–512. ISBN 978-0-7653-8669-4.
  9. ^ "三体 的海报". (in Chinese). Retrieved June 10, 2015.
  10. ^ "三体 (2017)". (in Chinese). Retrieved June 24, 2016.
  11. ^ "三体 (2017)". (in Chinese). Inc. Archived from the original on February 7, 2019. Retrieved June 24, 2016.
  12. ^ CaixinOnline (June 23, 2016). "Premiere of Film based on Acclaimed Sci-fi Novel 'The Three-Body Problem' Pushed Back until 2017". Retrieved June 24, 2015.
  13. ^ "科幻巨著《三体》被动画化,前几集令人绝望,后面堪称神作!". (in Chinese). 7 February 2018. Retrieved 23 January 2021.
  14. ^ Yuanyuan, Zhao (December 13, 2022). "Mixed reaction for animated adaptation of science-fiction hit 'The Three-Body Problem'". Retrieved January 19, 2023.
  15. ^ "Chinese TV Series Based on "The Three Body Problem" to Premiere Sunday". Retrieved 2022-01-15.
  16. ^ Otterson, Joe (September 1, 2020). "'Three-Body Problem' Series From David Benioff, D.B. Weiss, Alexander Woo Set at Netflix". Variety.
  17. ^ "Rendezvous with the Future". Bilibili. 2022.