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  • Dichronauts

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Dichronauts

by Greg Egan (Author) Format: Kindle Edition
3.9 out of 5 stars (278)
Seth is a surveyor, along with his friend Theo, a leech-like creature running through his skull who tells Seth what lies to his left and right. Theo, in turn, relies on Seth for mobility, and for ordinary vision looking forwards and backwards. Like everyone else in their world, they are symbionts, depending on each other to survive. In the universe containing Seth’s world, light cannot travel in all directions: there is a “dark cone” to the north and south. Seth can only face to the east (or the west, if he tips his head backwards). If he starts to turn to the north or south, his body stretches out across the landscape, and to rotate to face north-east is every bit as impossible as accelerating to the speed of light. Every living thing in Seth’s world is in a state of perpetual migration as they follow the sun’s shifting orbit and the narrow habitable zone it creates. Cities are being constantly disassembled at one edge and rebuilt at the other, with surveyors mapping safe routes ahead. But when Seth and Theo join an expedition to the edge of the habitable zone, they discover a terrifying threat: a fissure in the surface of the world, so deep and wide that no one can perceive its limits. As the habitable zone continues to move, the migration will soon be blocked by this unbridgeable void, and the expedition has only one option to save its city from annihilation: descend into the unknown.
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  1. Print length
    314 pages
  2. Language
    English
  3. Accessibility
    Learn more
  4. Publication date
    31 March 2017
  5. File size
    3.4 MB
  6. Page Flip
    Enabled
  7. Word Wise
    Enabled
  8. Enhanced typesetting
    Enabled
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Product description

Review

"Impressively bizarre . . . Egan may have out-Eganed himself with this one."--Publishers Weekly

"Egan (The Arrows of Time, 2014, etc.) specializes in inventing seriously strange worlds; this one might well be his weirdest yet."--Kirkus Reviews

"Hard science fiction in its purest form . . . Egan has always done the science half of science fiction as well as anyone can."--The 1000 Year Plan

"Per usual for Egan, conceptualizing the math and physics that form the foundation of this bizarre sci-fi tale takes some doing, but the results are well worth the effort."--B&N Sci-Fi and Fantasy Blog

"I always enjoy Greg Egan's writing. Coupled with his scientific background and fertile imagination, he manages to come up with places and aliens unlike any others . . . not only does Egan offer a unique world and alien race - he also provides a cracking adventure story full of tension and excitement right from the start through to the climactic ending. . . . I love this one. Brilliant and inventive, this book reminds me all over again just why I love science fiction so much."--Brainfluff, 10/10. Reviewed by Sarah J. Higbee

"I haven't been this surprised and entertained by world building for a long time . . . the most brutal and poignant depiction of oppression I have ever seen in fiction. This is why I love Egan's work - he is absolutely unflinching. . . . Like all of Egan's work, Dichronauts is brilliant and sweet, heartbreaking and obscure."--The Kingdoms of Evil

"I enjoyed this one very much--in large part because the characters and problems become very engaging as the story progresses, but also because I just liked messing around with the maths."--The Oikofuge

About the Author

Paul Boehmer is a seasoned actor who has appeared on Broadway, film, and television, including The Thomas Crown Affair and All My Children. Coinciding with another of his passions, sci-fi, Paul has been cast in various roles in many episodes of Star Trek.

Greg Egan is a computer programmer and the author of the acclaimed science fiction novels Permutation City, Diaspora, Teranesia, Quarantine, and the Orthogonal trilogy. Greg has won the Hugo Award as well as the John W. Campbell Memorial Award. He lives in Australia.

Product details

  • ASIN ‏ : ‎ B01MV3SUNB
  • Publisher ‏ : ‎ Greg Egan
  • Accessibility ‏ : ‎ Learn more
  • Publication date ‏ : ‎ 31 March 2017
  • Language ‏ : ‎ English
  • File size ‏ : ‎ 3.4 MB
  • Screen Reader ‏ : ‎ Supported
  • Enhanced typesetting ‏ : ‎ Enabled
  • X-Ray ‏ : ‎ Not Enabled
  • Word Wise ‏ : ‎ Enabled
  • Print length ‏ : ‎ 314 pages
  • ISBN-13 ‏ : ‎ 978-1922240200
  • Page Flip ‏ : ‎ Enabled
  • Best Sellers Rank: 699,267 in Kindle Store (See Top 100 in Kindle Store)
  • Customer Reviews:
    3.9 out of 5 stars (278)

About the author

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Greg Egan

Greg Egan

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Greg Egan lives in Perth, Western Australia. He has won the Hugo Award, the John W. Campbell Memorial Award, and the Japanese Seiun Award for best translated fiction.

Customer reviews

3.9 out of 5 stars
278 global ratings

Customers say

Customers find the book's scientific concepts interesting and appreciate its excellent math-heavy SF approach. The story receives positive feedback, with one customer describing it as an "absolutely marvelous alternate universe story." The world-building and content receive mixed reactions, with some finding it stunning while others find it nearly incomprehensible. The book's readability is also mixed, with some finding it very interesting while others describe it as boring.
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12 customers mention interesting concepts, 11 positive, 1 negative
Customers find the book's concepts engaging, particularly its math-heavy science fiction elements, with one customer appreciating the development of physics throughout the narrative.
Genius, as always. Don't hesitate to read​ some introductory material before reading the novel, it will help a lot and save a lot of frustration.Read more
Excellent math-heavy SF. Make sure to read up on hyperbolic geometry first; the Dichronauts page on Egan's site is a good start.Read more
There are some interesting ideas, but they are presented in such a dull and indirect way that it's a slog.Read more
An interesting idea involving a universe with different physical rules....Read more
7 customers mention story, 5 positive, 2 negative
Customers enjoy the story of the book, with one describing it as an absolutely marvelous alternate universe narrative that drives the plot in interesting ways.
Great storytelling but unless you’re a Riemann geometry gerk, you’re gonna have a hell of a time following the where from/where to.Read more
...the physics starting from the basic assumptions, and it drove the plot in interesting ways....Read more
...interesting parts of the world he built, the story just stops without resolving the main conflict....Read more
...complete with alternate physics that the reader can enjoy puzzling out along with the plot....Read more
15 customers mention engaging, 9 positive, 6 negative
Customers have mixed reactions to the book, with some finding it very interesting while others describe it as boring.
Very interesting, especially the unorthodox geometry- would like to see more of this...Read more
...They're too much like hard work and are, frankly boring....Read more
My son read this in one night.Read more
...scientific concepts in this book are interesting but it is a very slow boring book. Gave up 15% of the way through.Read more
11 customers mention content, 7 positive, 4 negative
Customers have mixed reactions to the book's content, with some appreciating its depth while others note that more diagrams would help with understanding the world. One customer describes it as a stunningly in-depth documentary, while another compares it to a 300-page math problem with social commentary.
...of Egan's work, Dichronauts is brilliant and sweet, heartbreaking and obscure....Read more
...In Dichronauts, the explanation of the physics is missing (apart from a very brief afterword, most of which I'd figured out anyway), and I still do...Read more
...from our own is a long and respected tradition but the care and depth of analysis you'll find here is not as common....Read more
...is possibly a spoiler, but suffice to say that the afterword explains things extremely clearly... if you can grasp the mathematics....Read more
9 customers mention world building, 6 positive, 3 negative
Customers have mixed opinions about the world-building in the book, with one customer describing it as stunning and another noting it's extremely detailed, while others find it confusing, with one mentioning they don't have a clear idea of the world's shape.
Greg Egan is one of the few people who still writes hard sci fi....Read more
...and I still don't have a clear idea of what shape the world is (which is important in the story), why water flow...Read more
Excellente with an extremely detailed world and thoroughly outlandish symbiotic aliens. I’m not dumb but this was tough to really grasp....Read more
...His world building is the strongest and most inventive I have ever seen, taking place in alternate universes with fully worked out laws of physics....Read more
5 customers mention readability, 2 positive, 3 negative
Customers have mixed opinions about the book's readability, with some finding it nearly incomprehensible.
...This was not an easy read, in fact it was quite exhausting and, I imagine, would not attract non-sf readers much....Read more
...the style is pretty much what readers of Egan are used to - clear, succinct prose with very few unneeded sentences - so I would say that...Read more
...of physics, visual-spacial skills, and a gift for math, much of the book is incomprehensible....Read more
...describes it with such patience and clarity that it is also impossible to misunderstand....Read more

Top reviews from Australia

There are 0 reviews from Australia

Top reviews from other countries

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  • knolle
    5 out of 5 stars
    Absolutely marvelous alternate universe story.
    Reviewed in Germany on 4 March 2021
    Format: Kindle
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    Dichronauts is fantastic. Until about 2/3 into the book I thought it was the greatest adventure story I ever read. Only in the end it suffers a bit form Egans usual weakness: it just stops.

    The story happens in another alternate universe, which clearly is Egans forte. After his orthogonal trilogy, which featured a world with four spacelike coordinates, dichronauts is the logical next step: a world with two timelike coordinates. Its fundamentals are worked out in far less detail than in the orthogonal series - probably because it is a far stranger setting. Even so (or because of this) the story bristles with surprise turns and is strange beyond measure. I don't want to give anything away, so I'll just say that it is mindboggling how otherworldly it feels. And yet, he managed to transfer so much of human thought and emotion - wonderfully twisted and adapted - to really make you think.

    I loved this book and regret very much that it is not a few hundred pages longer.

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  • Chris
    5 out of 5 stars
    A truly Mind Stretching alien world
    Reviewed in the United Kingdom on 19 August 2021
    Format: Kindle
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    Excellente with an extremely detailed world and thoroughly outlandish symbiotic aliens. I’m not dumb but this was tough to really grasp. That’s what I loved about it. The characters were fairly interesting but the nearest I got to seeing the world as GE imagined it is when I went to his accompanying website and used his program to try to move simple objects in his strange world. Minutes of fun trying to move and balance things and watching them destroy themselves with weird physics. I’ve read nothing really like it in my 64 years.

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  • Nadia&Casey
    4 out of 5 stars
    Amazing world and decent story
    Reviewed in the United States on 1 August 2017
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    I am a lover of hard science fiction and Greg Egan is the epitome of that genre. His world building is the strongest and most inventive I have ever seen, taking place in alternate universes with fully worked out laws of physics. The physics are typically one of the main focuses of his books with story and characters not quite as developed. He is no Mark Twain but rich prose and character development is not the main reason to read his books, I read his books to see the incredible ideas that no other author has yet explored.

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  • FeydRautha
    2 out of 5 stars
    Un Greg Egan raté
    Reviewed in France on 21 September 2017
    Format: Kindle
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    Je n'avais pas imaginé écrire un jour une critique négative sur un livre de Greg Egan, mais il y a un début à tout.

    Greg Egan, c'est le pape incontesté de la Hard SF, version très Hard. J'avais jusqu'alors toujours été passionné par l'incroyable ambition de ses écrits, sa vision éclairée d'un futur parfois proche, parfois plus lointain, sa maîtrise des concepts scientifiques et mathématiques les plus avancés, même si l'aridité de son style pouvait parfois rendre la lecture de ses romans et de ses nouvelles quelque peu singulière. Greg Egan écrit parce qu'il a des idées, scientifiques mais aussi parfois politiques, à partager de façon pressente, et pas pour proposer un moment de détente à son lecteur. Ses écrits réclament un engagement de la part du lecteur, une attention et une réflexion. Ainsi que bien souvent des connaissances en sciences et en mathématiques assez solides.

    Mais voilà, j'ai eu beaucoup de mal à finir Dichronauts, par manque d'intérêt pour le monde décrit et l'histoire contée. Dans ce nouveau roman, Greg Egan reprend l'idée explorée dans la série Orthogonal d'un monde régit par des dimensions de l'espace temps différentes de l'univers que nous connaissons, où il imaginait un monde répondant à la métrique de Riemann, dans laquelle les trois dimensions de l'espace et celle du temps sont strictement équivalentes, pour faire court. Le propos des trois romans de cette série était alors d'explorer les conséquences de cette métrique. Cela fonctionnait car au niveau le pus bas, il avait finalement peu de différences entre cet univers et le nôtre, et il était facile pour le lecteur d'évoluer dans ce monde sans trop perdre ses repères.

    Greg Egan complique les choses dans Dichronauts en imaginant un univers où il n'y a non plus 3 dimensions de l'espace et 1 du temps, mais 2 dimensions spatiales et 2 temporelles. Cela donne un univers à la géométrie hyperbolique. Et le soucis d'une hyperbole, si vous vous souvenez de vos cours de math, c'est qu'elle diverge aux extrêmes. Il ne s'agit pas d'un roman de science fiction, mais d'une fiction mathématique. Les habitants de ce monde sont des symbiotes, constitués d'une paire d'individus, soit un "walker", dont on ne sait trop quelle forme il a si ce n'est qu'il marche sur deux jambes et qu'il possède deux bras et une tête, et un "sider", sorte de sangsue logée dans le crâne du walker. En raison de la géométrie hyperbolique de ce monde, la lumière ne se propage pas de la même manière dans toutes les directions. Un walker ne peut ainsi percevoir le monde que dans une direction. En utilisant l'écholocation, le sider lui fournit une vision dans l'autre direction. Mais ce n'est pas tout, le walker ne peut tourner sur lui-même, car sa forme géométrique divergerait rapidement, jusqu'à le briser. Il est ainsi condamné à la naissance à faire face à l'ouest ou à l'est. Pour se déplacer vers le nord ou vers le sud, il doit faire un pas de côté. une chute dans la mauvaise direction, et c'est le drame. La simple manipulation des objet est aussi compliquée voire rendue impossible par cette géométrie. Greg Egan va prendre le prétexte d'une exploration du monde par quelques individus pour s'amuser avec cette géométrie particulière et en tester les conséquences. C'est sans doute amusant pour l'auteur mais nettement moins pour le lecteur.

    Le problème principal qui se pose au lecteur est l'impossibilité de se représenter ce monde, les mouvements, les déplacements, la physique de base de cet univers. Le mal de crâne est rapide, et le désintérêt prompt. Greg Egan n'a jamais brillé par le développement de ses personnages, mais dans ce cas, ils sont totalement inintéressants. L'histoire elle même n'est pas plus enthousiasmante. Au final, ce que me gène le plus, c'est qu'il y a de trop nombreuses impossibilités conceptuelles dans un tel monde pour rendre sa description un tant soit peu crédible voire même simplement amusante. Je n'ai eu de cesse durant ma lecture de me dire que l'évolution sous de telles contraintes, n'aurait pas abouti aux créatures ni au monde décrits par Egan dans ce roman. Elle n'aurait d'ailleurs abouti à rien. Greg Egan fait le choix de ne pas envisager les conséquences de la géométrie hyperbolique au niveau microscopique. Mais les conséquences sont les mêmes qu'au niveau macroscopique : une simple molécule ne pourrait exister dans ces conditions.

    Au final, si j'ai trouvé ce roman très ambitieux, je l'ai aussi trouvé raté car ennuyeux, et pénible à lire de part la difficulté, voire l'impossibilité, à se représenter mentalement ce monde. Le plus mauvais Egan que j'ai lu.

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  • Daniel M. Bensen
    5 out of 5 stars
    A Beautiful Book
    Reviewed in the United States on 3 August 2017
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    I haven't been this surprised and entertained by world building for a long time, and I was beginning to think I had outgrown science fiction. I hadn't. I just didn't know how far it could go.

    The geometry of the world of Dichronauts is impossible to intuit, but Egan describes it with such patience and clarity that it is also impossible to misunderstand. Flatland lies somewhere at the base of this book, but Egan far surpasses anything Abbott managed, both in playing with dimensions and the most brutal and poignant depiction of oppression I have ever seen in fiction.

    This is why I love Egan's work – he is absolutely unflinching. He never cuts corners with his world, his characters' motivations, or the agonizing dilemmas in which they find themselves. They are people trying to do right in circumstances in which doing right is physically impossible. They get no magic wands to wave, no convenient shortcut to everyone's best interests..

    Like all of Egan's work, Dichronauts is brilliant and sweet, heartbreaking and obscure. Having read it, I feel like I have some tools to tackle the real world as well.

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