"But, out here -" Amber sits up. "d.a.m.n," she says, quietly. "What got into him?"

"Middle-aged restlessness, my downwell sibs say." Monica shrugs. "This time Annette didn't stop him. But he hasn't made up his mind to travel yet."

"Good. Then he might not -" Amber stops. "The phrase, 'made up his mind', what exactly do you mean?"

Monica's smile mocks her for a few seconds before the older woman surrenders. "He's talking about uploading."

"Is that embarra.s.sing or what?" asks Ang. Amber glances at her, mildly annoyed, but Ang isn't looking her way. So much for friends, Amber thinks. Being queen of all you survey is a great way of breaking up peer relationships - "He won't do it," Amber predicts. "Dad's burned out."

"He thinks he'll get it back if he optimizes himself for re-entrancy." Monica continues to smile. "I've been telling him it's just what he needs."

"I do not want my father bugging me. Or my mother. Or Auntie 'Nette and Uncle Gianni. Memo to immigration control: No entry rights for Manfred Macx or the other named individuals without clearance through the Queen's secretary."

"What did he do to get you so uptight?" asks Monica idly.

Amber sighs, and subsides. "Nothing. It's not that I'm ungrateful or anything, but he's just so extropian, it's embarra.s.sing. Like, that was the last century's apocalypse. Y'know?"

"I think he was a really very forward-looking organic," Monica, speaking for the Franklin borg, a.s.serts. Amber looks away. Pierre would get it, she thinks. Pierre would understand her aversion to Manfred's showing up. Pierre, too, wants to carve out his own niche without parents looking over his shoulders, although for very different reasons. She focuses on someone male and more or less mature - Nicky, she thinks, though she hasn't seen him for a long time - walking toward the piazza, bare-a.s.s naked and beautifully tanned.

"Parents. What are they good for?" asks Amber, with all the truculence of her seventeen years. "Even if they stay neotenous, they lose flexibility. And there's that long Paleolithic tradition of juvenile slavery. Inhuman, I call it."

"How old were you when it was safe to leave you around the house on your own?" challenges Monica.

"Three. That's when I had my first implants." Amber smiles at the approaching young Adonis, who smiles back: Yes, it's Nicky, and he seems pleased to see her. Life is good, she thinks, idly considering whether or not to tell Pierre.

"Times change," remarks Monica. "Don't write your family off too soon; there might come a time when you want their company."

"Huh." Amber pulls a face at the old borg component. "That's what you all say!"

As soon as Amber steps onto the gra.s.s, she can feel possibilities open up around her. She has management authority here, and this universe is big, wide open, not like Sadeq's existential trap. A twitch of a sub-process rea.s.serts her self-image, back to short hair and comfortable clothing. Another twitch brings up a whole load of useful diagnostics. Amber has a nasty feeling that she's running in a compatibility sandbox here - there are signs that her access to the simulation system's control interface is very much via proxy - but at least she's got it.

"Wow! Back in the real world at last!" She can hardly contain her excitement, even forgetting to be p.i.s.sed at Sadeq for thinking she was just an actor in his Cartesian theatre's performance of Puritan h.e.l.l. "Look! It's the DMZ!"

They're standing on a gra.s.sy knoll overlooking a gleaming Mediterranean city. It snoozes beneath a Mandelbrot-fuzzy not-sun that hangs at the center of a hyperbolic landscape, which dwindles into a blue yonder that seems incomprehensibly distant. Circular baby-blue wells open in the walls of the world at regular intervals, connecting to other parts of the manifold. "How big is it, ghost? In planetary simulation-equivalents."

"This demilitarized zone is an embedded reality, funneling all transfers between the local star system's router and the civilization that built it. It uses on the order of a thousandth of the capacity of the Matrioshka brain it is part of, although the runaway excursion currently in force has absorbed most of that. Matrioshka brain, you are familiar with the concept?" The ghost sounds fussily pedantic.

Sadeq shakes his head. Amber glances at him, askance. "Take all the planets in a star system and dismantle them," she explains. "Turn them into dust - structured nanocomp, powered by heat exchangers, spread in concentric orbits around the central star. The inner orbitals run close to the melting point of iron, the outer ones are cold as liquid nitrogen, and each layer runs off the waste heat of the next sh.e.l.l in. It's like a Russian doll made out of Dyson spheres, sh.e.l.l enclosing sh.e.l.l enclosing sh.e.l.l, but it's not designed to support human life. It's computronium, matter optimized at the atomic level to support computing, and they're all running uploads - Dad figured our own solar system could support, uh, about a hundred billion times as many inhabitants as Earth. At a conservative estimate. As uploads, living in simulation s.p.a.ce. If you first dismantle all the planets and use the resulting materials to build a Matrioshka brain."

"Ah." Sadeq nods thoughtfully. "Is that your definition, too?" he asks, glancing up at the glowing point the ghost uses to localize its presence.

"Substantially," it says, almost grudgingly.

"Substantially?" Amber glances around. A billion worlds to explore, she thinks dizzily. And that's just the firewall? She feels obscurely cheated: You need to be vaster than human just to count the digits in the big numbers at play here, but there's nothing fundamentally incomprehensible about it. This is the sort of civilization Dad said she could expect to live in, within her meatbody life expectancy. Dad and his drinking buddies, singing, "Dismantle the Moon! Melt down Mars!" in a castle outside Prague as they waited for the results of a shamelessly gerrymandered election to arrive in the third decade of the third millennium. The s.p.a.ce and Freedom Party taking over the EU, and cranking up to escape velocity. But this is supposed to be kilopa.r.s.ecs from home, ancient alien civilizations and all that! Where's the exotic superscience? What about the neuron stars, strange matter suns structured for computing at nucleonic, rather than electronic, speeds? I have a bad feeling about this, she thinks, sp.a.w.ning a copy of herself to set up a private channel to Sadeq. It's not advanced enough. Do you suppose these guys could be like the Wunch? Parasites or barbarians. .h.i.tching a ride in the machine?

You believe it's lying to us? Sadeq sends back.

"Hmm." Amber sets off downslope toward the piazza below, at the heart of the fake town. "It looks a bit too human to me."

"Human," echoes Sadeq, a curious wistfulness in his voice. "Did you not say humans are extinct?"

"Your species is obsolete," the ghost comments smugly. "Inappropriately adapted to artificial realities. Poorly optimized circuitry, excessively complex low-bandwidth sensors, messily global variables -"

"Yeah, yeah, I get the picture," says Amber, turning her attention to the town. "So why do you think we can deal with this alien G.o.d you've got a problem with?"

"It asked for you," says the ghost, narrowing from an ellipse to a line, then shrinking to a dimensionless point of brilliance. "And now it's coming. We-I not willing to risk exposure. Call us-me when you have slain the dragon. Goodbye."

"Oh s.h.i.t -" Amber spins round. But she and Sadeq are alone beneath the hot sunlight from above. The piazza, like the one in the Nursery Republic, is charmingly rustic - but there's n.o.body home, nothing but ornate cast-iron furniture basking beneath the noon-bright sun, a table with a parasol over it, and something furry lying sprawled in a patch of sunlight beside it.

"We appear to be alone for now," says Sadeq. He smiles crookedly, then nods at the table. "Maybe we should wait for our host to arrive?"

"Our host." Amber peers around. "The ghost is kind of frightened of this alien. I wonder why?"

"It asked for us." Sadeq heads toward the table, pulls out a chair, and sits down carefully. "That could be very good news - or very bad."

"Hmm." Amber finishes her survey, sees no sign of life. For lack of any better ideas, she ambles over to the table and sits down on the other side of it from Sadeq. He looks slightly nervous beneath her inspection, but maybe it's just embarra.s.sment about having seen her in her underwear. If I had an afterlife like that, I'd be embarra.s.sed about it, too, Amber thinks to herself.

"Hey, you nearly tripped over -" Sadeq freezes, peering at something close to Amber's left foot. He looks puzzled for a moment, then smiles broadly. "What are you doing here?" he asks her blind spot.

"What are you talking to?" she asks, startled.

He's talking to me, dummy, says something tantalizingly familiar from her blind spot. So the f.u.c.kwits are trying to use you to dislodge me, hmm? That's not exactly clever.

"Who -" Amber squints at the flagstone, sp.a.w.ns a bunch of ghosts who tear hurriedly at her reality modification ackles. Nothing seems to shift the blindness. "Are you the alien?"

"What else could I be?" the blind spot asks with heavy irony. "No, I'm your father's pet cat. Listen, do you want to get out of here?"

"Uh." Amber rubs her eyes. "I can't see you, whatever you are," she says politely. "Do I know you?" She's got a strange sense that she does know the blind spot, that it's really important, and she's missing something intimate to her own sense of ident.i.ty, but what it might be she can't tell.

"Yeah, kid." There's a note of world-weary amus.e.m.e.nt in the not-voice coming from the hazy patch on the ground. "They've hacked you but good, both of you. Let me in, and I'll fix it."

"No!" Exclaims Amber, a second ahead of Sadeq, who looks at her oddly. "Are you really an invader?"

The blind spot sighs. "I'm as much an invader as you are, remember? I came here with you. Difference is, I'm not going to let some stupid corporate ghost use me as fungible currency."

"Fungible -" Sadeq stops. "I remember you," he says slowly, with an expression of absolute, utter surprise on his face. "What do you mean?"

The blind spot yawns, baring sharp ivory fangs. Amber shakes her head, dismissing the momentary hallucination. "Lemme guess. You woke up in a room, and this alien ghost tells you the human species is extinct and asks you to do a number on me. Is that right?"

Amber nods, as an icy finger of fear trails up and down her spine. "Is it lying?" she asks.

"d.a.m.n right." The blind spot is smiling, now, and the smile on the void won't go away - she can see the smile, just not the body it's attached to. "My reckoning is, we're about sixteen light-years from Earth. The Wunch came through here, stripped the dump, then took off for parts unknown; it's a trashhole, you wouldn't believe it. The main life-form is an incredibly ornate corporate ecosphere, legal instruments breeding and replicating. They mug pa.s.sing sapients and use them as currency."

There's a triangular, pointy head behind the smile, slit eyes and sharp ears, a predatory, intelligent-looking but infinitely alien face. Amber can see it out of the corners of her eyes when she looks around the piazza. "You mean we, uh, they grabbed us when we appeared, and they've mangled my memories -" Amber suddenly finds it incredibly difficult to concentrate, but if she focuses on the smile, she can almost see the body behind it, hunched like a furry chicken, tail wrapped neatly around its front paws.

"Yeah. Except they didn't bargain on meeting something like me." The smile is infinitely wide, a Cheshire-cat grin on front of an orange-and-brown stripy body that shimmers in front of Amber's gaze like a hallucination. "Your mother's cracking tools are self-extending, Amber. Do you remember Hong Kong?"

"Hong -"

There is a moment of painless pressure, then Amber feels huge invisible barriers sliding away on all sides. She looks around, for the first time seeing the piazza as it really is, half the crew of the Field Circus waiting nervously around her, the grinning cat crouched on the floor at her feet, the enormous walls of recomplicating data that fence their little town off from the gaping holes - interfaces to the other routers in the network.

"Welcome back," Pierre says gravely, as Amber gives a squeak of surprise and leans forward to pick up her cat. "Now you're out from under, how about we start trying to figure out how to get home?"

Welcome to decade the sixth, millennium three. These old datelines don't mean so much anymore, for while some billions of fleshbody humans are still infected with viral memes, the significance of theocentric dating has been dealt a body blow. This may be the fifties, but what that means to you depends on how fast your reality rate runs. The various upload clades exploding across the reaches of the solar system vary by several orders of magnitude - some are barely out of 2049, while others are exploring the subjective thousandth millennium.

While the Field Circus floats in orbit around an alien router (itself orbiting the brown dwarf Hyundai +4904/[-56]), while Amber and her crew are trapped on the far side of a wormhole linking the router to a network of incomprehensibly vast alien mindscapes - while all this is going on, the d.a.m.nfool human species has finally succeeded in making itself obsolete. The proximate cause of its displacement from the pinnacle of creation (or the pinnacle of teleological self-congratulation, depending on your stance on evolutionary biology) is an attack of self-aware corporations. The phrase "smart money" has taken on a whole new meaning, for the collision between international business law and neurocomputing technology has given rise to a whole new family of species - fast-moving corporate carnivores in the Net. The planet Mercury has been broken up by a consortium of energy brokers, and Venus is an expanding debris cloud, energized to a violent glare by the trapped and channeled solar output. A million billion fist-sized computing caltrops, backsides glowing dull red with the efflux from their thinking, orbit the sun at various inclinations no farther out than Mercury used to be.

Billions of fleshbody humans refuse to have anything to do with the blasphemous new realities. Many of their leaders denounce the uploads and AIs as soulless machines. Many more are timid, harboring self-preservation memes that amplify a previously healthy aversion to having one's brain peeled like an onion by mind-mapping robots into an all-pervading neurosis. Sales of electrified tinfoil-lined hats are at an all-time high. Still, hundreds of millions have already traded their meat puppets for mind machines, and they breed fast. In another few years, the fleshbody populace will be an absolute minority of the posthuman clade. Sometime later, there will probably be a war. The dwellers in the thoughtcloud are hungry for dumb matter to convert, and the fleshbodies make notoriously poor use of the collection of silicon and rare elements that pool at the bottom of the gravity well that is Earth.

Energy and thought are driving a phase-change in the condensed matter substance of the solar system. The MIPS per kilogram metric is on the steep upward leg of a sigmoid curve - dumb matter is coming to life as the mind children restructure everything with voracious nanomechanical servants. The thoughtcloud forming in orbit around the sun will ultimately be the graveyard of a biological ecology, another marker in s.p.a.ce visible to the telescopes of any new iron-age species with the insight to understand what they're seeing: the death throes of dumb matter, the birth of a habitable reality vaster than a galaxy and far speedier. Death throes that, within a few centuries, will mean the extinction of biological life within a light-year or so of that star - for the majestic Matrioshka brains, though they are the pinnacles of sentient civilization, are intrinsically hostile environments for fleshy life.

Pierre, Donna-the-all-seeing-eye, and Su Ang fill Amber in on what they've discovered about the bazaar - as they call the s.p.a.ce the ghost referred to as the demilitarized zone - over ice-cold margaritas and a very good simulation of a sociable joint. Some of them have been on the loose in here for subjective years. There's a lot of information to absorb.

"The physical layer is half a light-hour in diameter, four hundred times as ma.s.sive as Earth," Pierre explains. "Not solid, of course - the largest component is about the size my fist used to be." Amber squints, trying to remember how big that was - scale factors are hard to remember accurately. "I met this old chatbot that said it's outlived its original star, but I'm not sure it's running with a full deck. Anyway, if it's telling the truth, we're a third of a light year out from a closely coupled binary system - they use orbital lasers the size of Jupiter to power it without getting too close to all those icky gravity wells."

Amber is intimidated, despite her better judgment, because this bizarre bazaar is several hundred billion times as big as the totality of human presingularity civilization. She tries not to show it in front of the others, but she's worried that getting home may be impossible - requiring enterprise beyond the economic event horizon, as realistic a proposition as a dime debuting as a dollar bill. Still, she's got to at least try. Just knowing about the existence of the bazaar will change so many things ...

"How much money can we lay our hands on?" She asks. "What is money hereabouts, anyway? a.s.suming they've got a scarcity-mediated economy. Bandwidth, maybe?"

"Ah, well." Pierre looks at her oddly. "That's the problem. Didn't the ghost tell you?"

"Tell me?" Amber raises an eyebrow. "Yeah, but it hasn't exactly proven to be a reliable guide to anything, has it?"

"Tell her," Su Ang says quietly. She looks away, embarra.s.sed by something.

"They've got a scarcity economy all right," says Pierre. "Bandwidth is the limited resource, that and matter. This whole civilization is tied together locally because if you move too far away, well, it takes ages to catch up on the gossip. Matrioshka brain intelligences are much more likely to stay at home than anybody realized, even though they chat on the phone a lot. And they use things that come from other cognitive universes as, well, currency. We came in through the coin slot, is it any wonder we ended up in the bank?"

"That's so deeply wrong that I don't know where to begin," Amber grumbles. "How did they get into this mess?"

"Don't ask me." Pierre shrugs. "I have the distinct feeling that anyone or anything we meet in this place won't have any more of a clue than we do - whoever or whatever built this brain, there ain't n.o.body home anymore except the self-propelled corporations and hitchhikers like the Wunch. We're in the dark, just like they were."

"Huh. You mean they built something like this, then they went extinct? That sounds so dumb ..."

Su Ang sighs. "They got too big and complex to go traveling once they built themselves a bigger house to live in. Extinction tends to be what happens to overspecialized organisms that are stuck in one environmental niche for too long. If you posit a singularity, then maximization of local computing resources - like this - as the usual end state for tool users, is it any wonder none of them ever came calling on us?"

Amber focuses on the table in front of her, rests the heel of her palm on the cool metal, and tries to remember how to fork a second copy of her state vector. A moment later, her ghost obligingly f.u.c.ks with the physics model of the table. Iron gives way like rubber beneath her fingertips, a pleasant elasticity. "Okay, we have some control over the universe, at least that's something to work with. Have any of you tried any self-modification?"

"That's dangerous," Pierre says emphatically. "The more of us the better before we start doing that stuff. And we need some firewalling of our own."

"How deep does reality go, here?" asks Sadeq. It's almost the first question he's asked of his own volition, and Amber takes it as a positive sign that he's finally coming out of his sh.e.l.l.

"Oh, the Planck length is about a hundredth of a millimeter in this world. Too small to see, comfortably large for the simulation engines to handle. Not like real s.p.a.ce-time."

"Well, then." Sadeq pauses. "They can zoom their reality if they need to?"

"Yeah, fractals work in here." Pierre nods. "I didn't -"

"This place is a trap," Su Ang says emphatically.

"No it isn't," Pierre replies, nettled.

"What do you mean, a trap?" asks Amber.

"We've been here a while," says Ang. She glances at Aineko, who sprawls on the flagstones, snoozing or whatever it is that weakly superhuman AIs do when they're emulating a sleeping cat. "After your cat broke us out of bondage, we had a look around. There are things out there that -" She shivers. "Humans can't survive in most of the simulation s.p.a.ces here. Universes with physics models that don't support our kind of neural computing. You could migrate there, but you'd need to be ported to a whole new type of logic - by the time you did that, would you still be you? Still, there are enough ent.i.ties roughly as complex as we are to prove that the builders aren't here anymore. Just lesser sapients, rooting through the wreckage. Worms and parasites squirming through the body after nightfall on the battlefield."

"I ran into the Wunch," Donna volunteers helpfully. "The first couple of times they ate my ghost, but eventually I figured out how to talk to them."

"And there's other aliens, too," Su Ang adds gloomily. "Just n.o.body you'd want to meet on a dark night."

"So there's no hope of making contact," Amber summarizes. "At least, not with anything transcendent and well-intentioned toward visiting humans."

"That's probably right," Pierre concedes. He doesn't sound happy about it.

"So we're stuck in a pocket universe with limited bandwidth to home and a bunch of crazy slum dwellers who've moved into the abandoned and decaying mansion and want to use us for currency. 'Jesus saves, and redeems souls for valuable gifts.' Yeah?"

"Yeah." Su Ang looks depressed.

"Well." Amber glances at Sadeq speculatively. Sadeq is staring into the distance, at the crazy infinite sunspot that limns the square with shadows. "Hey, G.o.d-man. Got a question for you."

"Yes?" Sadeq looks at her, a slightly dazed expression on his face. "I'm sorry, I am just feeling the jaws of a larger trap around my throat -"

"Don't be." Amber grins, and it is not a pleasant expression. "Have you ever been to Brooklyn?"

"No, why -"

"Because you're going to help me sell these lying b.a.s.t.a.r.ds a bridge. Okay? And when we've sold it we're going to use the money to pay the purchasing fools to drive us across, so we can go home. Listen, this is what I'm planning ..."

"I can do this, I think," Sadeq says, moodily examining the Klein bottle on the table. The bottle is half-empty, its fluid contents invisible around the corner of the fourth-dimensional store. "I spent long enough alone in there to -" He shivers.

"I don't want you damaging yourself," Amber says, calmly enough, because she has an ominous feeling that their survival in this place has an expiry date attached.

"Oh, never fear." Sadeq grins lopsidedly. "One pocket h.e.l.l is much like another."

"Do you understand why -"

"Yes, yes," he says dismissively. "We can't send copies of ourselves into it, that would be an abomination. It needs to be unpopulated, yes?"

"Well, the idea is to get us home, not leave thousands of copies of ourselves trapped in a pocket universe here. Isn't that it?" Su Ang asks hesitantly. She's looking distracted, most of her attention focused on absorbing the experiences of a dozen ghosts she's spun off to attend to perimeter security.

"Who are we selling this to?" asks Sadeq. "If you want me to make it attractive -"