Diaspora
Author — Greg EganFinished — 2025-12-10
Started — 2025-09-20
Don’t miss Egan’s dedicated website of scientific explanations and errata for this book!
Now that ve’d experienced Truth Mining for verself, Yatima could only agree. There was nothing in any scape or library file, any satellite feed or drone image, more beautiful than mathematics. Ve sent the scape a query tag, and it lit the way to the Gauss-Bonnet Theorem with an azure glow for vis viewpoint only. Ve floated off slowly down one of the tunnels, reading all the tags from the jewelled path.
ok truth mining is cool
Understanding an idea meant entangling it so thoroughly with all the other symbols in your mind that it changed the way you thought about everything.
Any citizen with a mind broadly modelled on a flesher’s was vulnerable to drift: the decay over time of even the most cherished goals and values. Flexibility was an essential part of the flesher legacy, but after a dozen computational equivalents of the pre-Introdus lifespan, even the most robust personality was liable to unwind into an entropic mess. None of the polises’ founders had chosen to build predetermined stabilising mechanisms into their basic designs, though, lest the entire species ossify into tribes of self-perpetuating monomaniacs, parasitised by a handful of memes. It was judged far safer for each citizen to be free to choose from a wide variety of outlooks: software that could run inside your exoself and reinforce the qualities you valued most, if and when you felt the need for such an anchor. The possibilities for short-term cross-cultural experimentation were almost incidental.
Yatima was glad to be witnessing it, taking some part of it inside verself before every image dissolved into nothing but a flicker of entropy in Ashton-Laval’s coolant flow.
At one point Yatima had envisioned a vast trail of similar mementos stretching across the savannah, a map ve could fly over whenever ve wanted to review the turning points in vis life . . . but then the whole idea had begun to seem childish. If the things ve’d seen had changed ver, they’d changed ver; there was no need to re-create them as monuments.
Art had its place, tweaking the remnants of all the instincts and drives that the fleshers, in their innocence, had once mistaken for embodiments of immutable truth – but only in the Mines could ve hope to discover the real invariants of identity and consciousness. Only in the Mines could ve begin to understand exactly who ve was.
No wonder most fleshers had stampeded into the polises, once they had the chance: if disease and ageing weren’t reason enough, there was gravity, friction, and inertia. The physical world was one vast, tangled obstacle course of pointless, arbitrary restrictions.
Liana said, ‘Better gleisners out there than fleshers. Can you imagine statics in space? They’d probably have terraformed Mars by now. The gleisners have barely touched the planet; mostly they’ve just surveyed it from orbit. They’re not vandals. They’re not colonists.’
:O is it easier to upload than terraform?
In Konishi, the whole idea of solidity, of atavistic delusions of corporeality, was generally equated with obstruction and coercion. Once your icon could so much as block another’s path in a public scape, autonomy was violated. Reconnecting the pleasures of love to concepts like force and friction was simply barbaric.
Without the unrepeatable allure which had brought them here, would this place, and these friends, ever again be worth eight hundred times more than all the rest?
Quantifiability of value of experience
This tranquillity wouldn’t last forever. G-1a and G-1b were separated by just half a million kilometres, and over the next seven million years gravitational waves would carry away all the angular momentum that kept them apart.
Wow
The biosphere was a disordered world, full of potential toxins and pathogens, ruled by nothing but the chance collisions of molecules. A ruptured skin would be like a wildly malfunctioning exoself that let data flood across its borders at random, overwriting and corrupting the citizen within.
When Atlanta came into view ahead, surrounded by its vast green and golden fields, it was as if the scale of the problems the bridgers would soon be facing had been laid out for inspection in hectares of soil, megalitres of water, tonnes of grain. In principle, there was absolutely no reason why suitably adapted organic life couldn’t flourish in the new environment Lacerta would create. Crops could employ robust pigments that made use of UV photons, their roots secreting glycols to melt the hardest tundra, their biochemistry adapted to the acidic, nitrogenous water and soil. Other species essential to the medium-term chemical stability of the biosphere could be given protective modifications, and the fleshers themselves could engineer a new integument to shield them from cell death and genetic damage even in direct sunlight. In practice, though, any such transition would be a race against time, constrained at every step by the realities of mass and distance, entropy and inertia. The physical world couldn’t simply be commanded to change; it could only be manipulated, painstakingly, step by step – more like a mathematical proof than a scape.
Yatima tried to imagine an alien species with the retarded morality required for warfare and the technological prowess to manipulate neutron stars. It was a deeply unpleasant notion, but about as likely as the influenza virus inventing the H-bomb.
Everything about the nanoware in the hand is great Egan plotting
half the speech seemed to consist of references to a virulent family of Palestinian theistic replicators.
I think I agree this is dumb
This seemed to split the audience; some responded with jeers of derision, some with renewed calm and even enthusiasm. Yatima felt like ve was playing a game ve barely understood, for stakes ve hardly dared contemplate. They had never been fit for this task, either of them. In Konishi, the grossest acts of foolishness could barely wound a fellow citizen’s pride; here and now, a few poorly judged words could cost thousands of lives.
This whole culture clash is good sf
Yatima felt an overpowering sense of hope. It was as if the Konishi mind seed still encoded the instinctive knowledge that, in time, the darkest stormclouds would always clear, the longest night would always yield to dawn, the harshest winter would always be tempered by spring. Every hardship the Earth forced upon its inhabitants was bounded, cyclic, survivable. Every creature born in the flesh carried the genes of an ancestor who had lived through the most savage punishment this world could inflict. No longer. Sunlight breaking through the clouds was a lie now. Every instinct that proclaimed that the future could be no worse than the worst of the past was obsolete.
Lac G-1’s great age meant that the two supernovae which had left the neutron stars behind pre-dated the solar system. Supernovae sent shockwaves rippling through surrounding clouds of gas and dust, triggering star formation. So it was not inconceivable that G-1a or G-1b had created the sun, and the Earth, and the planets. Yatima wished ve’d thought of this when Inoshiro was talking to the statics; renaming the neutron stars ‘Brahma’ and ‘Shiva’ might have carried the right kind of mythic resonance to penetrate their mythic stupor.
The conceptory wasn’t interested in scattering Konishi shapers far and wide, like replicating genes; its goal was the efficient use of polis resources for the enrichment of the polis itself.
Is this a real theory!?
At the other extreme, ninety-two citizens had chosen to experience every one of the thousand journeys, and though some were rushing fast enough to shrink each trip to a few megatau, the rest subscribed to the curious belief that flesher-equivalent subjective time was the only ‘honest’ rate at which to engage with the physical world. They were the ones who required the most heavy-handed outlooks to keep them from going insane.
Suspected “Liu but better” status coming true
Paolo was relieved to be back to normal. Ceremonial regression to the ancestral form every now and then kept his father happy – and being a flesher was largely self-affirming, while it lasted – but every time he emerged from the experience he felt like he’d broken free of billion-year-old shackles. There were polises where the citizens would have found his present structure almost as archaic, but the balance seemed right to Paolo; he enjoyed the sense of embodiment that came from a tactile surface and proprioceptive feedback, but only a fanatic could persist in simulating kilograms of pointless viscera, perceiving every scape through crippled sense organs, and subjugating vis mind to all the unpleasant quirks of flesher neurobiology.
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.
There was no crime of heresy in C-Z; the polis charter was just a statement of the founders’ values, not some doctrine to be accepted under threat of exile. At times it still felt like a tightrope walk, though, trying to classify every act of simulation into those which contributed to an understanding of the physical universe (good), those which were merely convenient, recreational, aesthetic (acceptable) . . . and those which constituted a denial of the primacy of real phenomena (time to think about emigration).
With the right set of tiles, to force the right pattern, the next row of the tiling will look like the data tape after the Turing Machine has performed one step of its computation. And the row after that will be the data tape after two steps, and so on. For any given Turing Machine there’s a set of Wang tiles that can imitate it.’
‘The carpets must be carrying out billions of acts of computation every second . . . but then, so are the water molecules around them. There are no physical processes that don’t perform arithmetic of some kind.’
if nature had evolved ‘organisms’ as divorced from reality as the inhabitants of the most inward-looking polis, where was the privileged status of the physical universe, the clear distinction between reality and illusion?
Wow
Simple linear cascades were rapidly tried out, then inhibited as stale – or vis mind would have been paralysed by positive feedback loops of hot/cold, wet/dry banality – but novel combinations of symbols were firing all the time, and if they resonated strongly enough with the current activity, their alliance could be reinforced, and even rise to consciousness. Thought was a lot like biochemistry; there were millions of random collisions going on all the time, but it was the need to form a product with the right shape to adhere firmly to an existing template that advanced the process in a coherent way.
The only way to get anything done
Using the loosely bound neutrons of halo nuclei in a manner analogous to the electron clouds of a normal atom, he’d managed to build ‘molecules’ five orders of magnitude smaller than those with electron bonds,
Wow
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.
The most plausible scheme Yatima had heard so far involved encoding every polis’s data as a pattern of deep trenches on a planetary surface, and then building a vast army of non-sentient robots on a variety of scales, from nanoware up, so numerous that there was a chance that the relatively few survivors would be capable of reconstructing the polis.
Dude
The macrosphere’s four-dimensional standard fibre yielded a much smaller set of fundamental particles than the ordinary universe’s six-dimensional one. In place of six flavours of quarks and six flavours of leptons there was just one of each, plus their antiparticles. There were gluons, gravitons and photons, but no W or Z bosons, since they mediated the process of quarks changing flavour. Three quarks or three antiquarks together formed a charged ‘nucleon’ or ‘anti-nucleon’, similar to an ordinary proton or antiproton, and the sole lepton and its antiparticle were much like an electron and positron, but there was no combination of quarks analogous to a neutron.
Wow!
He addressed the scape. ‘Sweep the sky.’ At any one moment, the ordinary view from the Island – a mere two-dimensional dome – could only encompass a narrow portion of the macrosphere’s four-dimensional sky. But the hemisphere could be swept across the sky, scanning it like a Flatlander scanning ordinary space by rotating the plane of vis slit-like view. Orlando watched the sparse stars come and go, far fewer than he’d have seen from Atlanta beneath a full moon. Still, it was remarkable that he could make out so many, when they were scattered so widely and their light was spread so thin.
Wow
Comparisons of scale with the home universe were slippery, but if the 5-bodies they’d chosen were used as measuring rods, Poincaré’s hypersurface could hold ten billion times as many denizens as the Earth – or conceal a few thousand industrial civilisations in the cracks between its putative forests and vast deserts. Mapping the entire star at a resolution guaranteed to reveal or rule out even a Shanghai-sized pre-Introdus city was a task akin to mapping every terrestrial planet in the Milky Way. The circular band of images collected by one probe as it completed one orbit of the hypersphere amounted to less than a pinprick, and even when the orbit was swept 360 degrees around the star, the sphere it traced out was about as significant, proportionately, as one shot of one location on an ordinary globe.
Gahhh
The long nucleons in the rock carried the same map of the Milky Way as Swift’s neutrons, followed by a catalytic sequence designed to interact with the vacuum of the second macrosphere. Bombarding the nucleons with antileptons energetic enough to overcome electrostatic repulsion would cause the singularity in ‘U-double-star’ to emit particles of ordinary matter; conversely, any particles fired back at the singularity would modify the same nucleon-antilepton interaction.
What
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.
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. They hadn’t turned whole worlds to rubble, they hadn’t reshaped galaxies in their image. Having evolved on some distant, finite world, they’d inherited the most valuable survival trait of all. Restraint.
fibre bundle: a fibre bundle is a manifold (the ‘total space’) plus some scheme for projecting it on to a second manifold of lower dimension (the ‘base space’). For example, the surface of a torus is a two-dimensional manifold, but if every longitudinal circle is reduced to a point, that projects the torus on to a single, equatorial circle, a one-dimensional manifold. The set of points in the total space that is projected on to any given point of the base space is called the ‘fibre’ of that point (e.g. one of the longitudinal circles of the torus). The fibres need not be identical from point to point, but if they are, their general form is called the standard fibre of the bundle. So, a torus is a fibre bundle with a circle as its base space, and another circle as its standard fibre. In classical Kozuch Theory, the universe is a fibre bundle with four-dimensional space-time as its base space, and a six-dimensional sphere as its standard fibre.
Wow
The broad principles of the Konish citizens’ mental architecture were inspired by the human cognitive models of Daniel C. Dennett and Marvin Minsky.