Name: Diaspora
ISBN: 9783453161818

Greg Egan

Roman

Diaspora

里森

Gavin

Does three things unusually well: hardness, alterity, and scale. Maybe uniquely well. Unfortunately these are not enough for a great book. 

Hard. For years I’ve wanted to write actually hard science fiction. Stuff like computing a full dynamical model of each plotline and space trajectory. Hard budget for delta-v. Deriving counterfactual physics from strange axioms. Showing the crucial moments in the plot, and quantifying their crucialness. 

Egan has done basically this in Diaspora, but he goofed by including much of his model in the prose (where I was going to hide it away on github). Probably about a quarter of this book is physics and physicslike exposition. 


  The classical properties of a fermion were having a spin of half a unit, obeying the Pauli exclusion principle (which kept all the electrons in an atom, and neutrons and protons in a nucleus, from falling together into the same, lowest-energy state), and responding to a 360-degree rotation by slipping 180 degrees out of phase with its unrotated version. A fermion needed two full rotations, 720 degrees, to come back into phase. Bosons needed only one rotation to end up exactly as they began.

Any long particle made up of an odd number of individual fermions would retain the first two fermionic properties, but if it also included any bosons, their presence would show up in the pattern of phase changes when the particle was rotated. A long particle with a wormhole sequence of "fermion-boson-fermion-fermion" would go out of phase and back like a simple fermion after one and two rotations, but a third rotation would bring it back into phase again immediately. Successive rotations could probe the wormhole's structure at ever greater depths: for each individual fermion in the chain it would take two rotations to restore the particle's phase, while for each boson it would take just one.


(view spoiler)[the characters leave spacetime to transit in higher dimensional realms, then leave that higher realm, then leave that one. They make this ascent trillions of times. (hide spoiler)]


  “It was meaningless to ask how many universes each handful of vacuum here contained. The Handler's revelations meant that even in the home universe, there were an infinite number of levels below them.”


  “They [fast-forwarded time] for a millennium”


  “They granted themselves eight-dimensional senses, and sat on the girders of an 8-scaped Satellite Pinatubo, watching perpendicular pairs of slender three- and five- dimensional artifacts rotate in and out of view. It was like whirling around a spiral staircase running from macrosphere to macrosphere, dimension to dimension”


(view spoiler)[
  

  
    “Taken together, the artifacts comprised a giant sculpture, spanning more than a quadrillion dimensions. The Transmuters had built a structure that dwarfed universes, but touched each one only lightly”
  
  

 (hide spoiler)]

Alterity. It's one of the few depictions of posthumans that makes you want to be there. The hints of their art we see are way beyond ours. It's a libertarian paradise, where rights are enforced at the OS level. There's no antagonist as a result. Physics, mathematics, and the relation of computation to meaning are the great challenges. 

I liked the political struggle between escapists and starfarers, metaphysicians and positivists. (view spoiler)[ in the end even the positivists sort of become escapists, by finding the natural em carpets and by ascending away from the original reality. (hide spoiler)]


  "we choose to value the physical world. That's what defines us, but it's as arbitrary as any other choice of values. Why can't you accept that? It's not the One True Path which the infidels have to be bludgeoned into following.”



  “Everything goes on in a multidimensional frequency space. I've Fourier-transformed the edge into over a thousand components, and there's independent information in all of them. We're only in a narrow cross section here, a sixteen-dimensional slice—but it's oriented to show the principal components, the maximum detail."
Paolo spun in a blur of meaningless color, utterly lost, his surroundings beyond comprehension. "You're a gleisner robot, Karpal! Only sixteen dimensions! How can you have done this?"
Karpal sounded hurt, wherever he was. "Why do you think I came to C-Z? I thought you people were flexible!"
"What you're doing is…" What? Heresy? There was no such thing. Officially. "Have you shown this to anyone else?"
"Of course not. Who did you have in mind? Liesl? Hermann?"
"Good. I know how to keep my mouth shut." Paolo jumped back to the dodecahedron; Karpal followed. "How can I put this? The physical universe has three spatial dimensions, plus time. Citizens of Carter-Zimmerman inhabit the physical universe. The false promises of Kozuch Theory kept us from the stars for a thousand years. Higher-dimensional mind games are strictly for the solipsists...

Paolo felt himself being tempted. Inhabit a sixteen dimensional slice of a thousand-dimensional frequency space? But it was in the service of understanding a real physical system—not a novel experience for its own sake.
And nobody had to find out.
He ran a quick self-predictive model. There was a ninety-three percent chance that he'd give in, after a kilotau spent agonizing over the decision.



Scale. The second half of the book just doesn't stop escalating. Some of the ems live for millions of years subjective, billions objective. (view spoiler)[Each neutron is used to store vast amounts of data, more than we store on our planet of hard drives. They visit dozens of worlds and then trillions of dimensions. Until they are perfectly alone, until the milky way is dead. (hide spoiler)]

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* It has a very strong philosophy of science, underdetermination:


  Blanca accepted that it was possible that all of Kozuch Theory's successful predictions were due to nothing but the "mirroring" of the logical structure of wormhole topology in another system altogether. The motion under gravity of an object dropped down a borehole passing through the center of an asteroid obeyed essentially the same mathematics as the motion of an object tied to the free end of an idealized anchored spring—but pushing either model too far as a metaphor for the other generated nonsense. The success of Kozuch's model could be due to the fact that it was just an extremely good metaphor, most of the time, for some deeper physical process which was actually as different from extra-dimensional wormholes as a spring was different from an asteroid.



* Egan is modish, anti-growth:


  Fleshers used to spin fantasies about aliens arriving to 'conquer' Earth, to steal their 'precious' physical resources, to wipe them out for fear of 'competition'… as if a species capable of making the journey wouldn't have had the power, or the wit, or the imagination, to rid itself of obsolete biological imperatives. Conquering the galaxy is what bacteria with spaceships would do—knowing no better, having no choice.

Our condition is the opposite of that: we have no end of choices. That's why we need to find another spacefaring civilization. Understanding Lacerta is important, the astrophysics of survival is important, but we also need to speak to others who've faced the same decisions, and discovered how to live, what to become. We need to understand what it means to inhabit the universe.



* (view spoiler)[In passing he solves Fermi: they’ve all gone to the second macrosphere for some reason, two dimensions rotated away from us. (hide spoiler)]

* Paolo is a moody bastard who never grows. Many such cases. Also he’s one of the only sims to have gender; even his dad, who was born biological, ends up using the neuter “ve”. 


  Ve stared down into the expanding well. "I'm doing this because of some badly-chosen fields in my mind seed. What's your excuse?"
Paolo didn't reply.
Yatima looked up. "Well, you should be good company”

But this stubborn stasis is exactly what he needs for his plotline, (view spoiler)[what it takes to be one of the few appreciators of the greatest artwork possible, to remain himself over 90 billion years (hide spoiler)].

* I love "bridging", his depiction of how to do first contact: you produce a clone of yourself who is less like you, more like the alien. You repeat this process n times until the nth clone can communicate with the alien and their n-1, who explains it to n-2…


  There was a world where that being had lived… but ve could neither name it nor clearly imagine it. With the symbols gone for most of the original's episodic memories, the clone's strongest inheritance was a sense of urgency, yet the edges of the lost memories still ached, like the vestiges of some plotless, senseless, unrecoverable dream of love and belonging.


* The emotional heft of having a clone, and reintegrating them:


  “I'll merge with you. If you really are willing."
Orlando examined his strange twin's face, wondering if he was being mocked, or tested. "I'm willing. Are you sure it's what you want, though? When I merge with the other thousand, what will a few megatau of your experience in 5-scapes amount to?"
"Not much," the clone conceded. "A tiny wound. A subtle ache. A reminder that you once embraced something larger than you thought you could."
"You want me to find sanctuary, and still be dissatisfied?"
"Just a bit."
"You want me to dream in five dimensions?"
"Now and then.”


* Egan is genuinely successful at making em relationships romantic:


  Paolo took the responsibilities of intimacy seriously; his lover before Elena had asked him to erase all his knowledge of her, and he'd more or less complied the only thing he still knew about her was the fact that she'd made the request.

Paolo brushed the dew from his skin. "Can I hold you in my mind? Just below sentience? Just to keep me sane?"
Elena sighed with mock wistfulness. "Of course, my love! Take a lock of my mind on your journey, and I'll carry a lock of yours on mine."


* "Slow-notion replay" (since thought is the medium for ems, not embodied movement)

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Egan is smarter than me, and it is good to spend time with such people, even if you don’t get everything, and even if you don’t have that much fun. You should read this on that basis.

A quantum Brave New World from the boldest and most wildly speculative writer of his generation. Since the Introdus in the twenty-first century, humanity has reconfigured itself drastically. Most chose immortality, joining the polises to become conscious software. Others opted for gleisners: disposable, renewable robotic bodies that remain in contact with the physical world of force and friction. Many of these have left the solar system forever in fusion-drive starships. And there are the holdouts: the fleshers left behind in the muck and jungle of Earth—some devolved into dream apes, others cavorting in the seas or the air—while the statics and bridgers try to shape out a roughly human destiny. But the complacency of the citizens is shattered when an unforeseen disaster ravages the fleshers and reveals the possibility that the polises themselves might be at risk from bizarre astrophysical processes that seem to violate fundamental laws of nature. The orphan Yatima, a digital being grown from a mind seed, joins a group of citizens and flesher refugees in a search for the knowledge that will guarantee their safety—a search that puts them on the trail of the ancient and elusive Transmuters, who have the power to reshape subatomic particles, and to cross into the macrocosmos, where the universe we know is nothing but a speck in the higher-dimensional vacuum. Skyhorse Publishing, under our Night Shade and Talos imprints, is proud to publish a broad range of titles for readers interested in science fiction (space opera, time travel, hard SF, alien invasion, near-future dystopia), fantasy (grimdark, sword and sorcery, contemporary urban fantasy, steampunk, alternative history), and horror (zombies, vampires, and the occult and supernatural), and much more. While not every title we publish becomes a New York Times bestseller, a national bestseller, or a Hugo or Nebula award-winner, we are committed to publishing quality books from a diverse group of authors.

A Novel

I love how BRUTALLY nerdy this book is. It’s unapologetic in how deep it goes on math/physics. Not sure I got even 25% of the math/tech. Might not be a fun read for anyone with no technical background. Goes hard on consciousness, apocalypse, space travel, alternate universes, VR spaces, existence of life, time and other philosophical concepts.

Aske Dørge

Joseph Aleo

Nothing ages more quickly than scifi but Egan's Diaspora, already 11 years old, is so far ahead of the curve that it still blows my mind every time I read it (this is my sixth read)!

Most scifi writers like Vernor Vinge sidestep the technological singularity but Egan uses the singularity to launch Diaspora. The year is 2996 and the Earth is divided into fleshers (humans), gleisners (robots) and AI citizens who live in polises. Two neutron stars have collided into each other bathing Earth in deadly gamma radiation sending the remaining fleshers into the polises to survive. Both citizens and gleisners decide to explore the galaxy to find lifeforms in the hopes of learning what made the neutron stars collide and how to live as a star-faring race. Along the way they find clues and alien races in their quest to find their answers.

The characters that inhabit Diaspora are removed enough from humanity that although the stakes are enormous the drama. Despite this Egan still delivers an entertaining and engaging tale is breath taking in scope.

Diaspora Roman