Ellie and Myra moved uncomfortably around the Pit. They were like two huge green pupae, Myra thought, bounding around these roughly melted chambers under the harsh light of the floods.

Ellie von Devender tolerated her presence, but barely. Busy, driven, full of a sense of herself and the importance of her work, Ellie wasnt the type to make space for nursemaiding. She was prepared to talk about her work, however, if Myra was able to ask intelligent questions.

Ellie had set up a kind of suite of sensors around the Eye, some in the Eye chamber itself and others in bays she had had melted into the Martian ice. High-energy particle detectors. Radiation sensors. A neutrino detection tank. This was a chamber blown into the ice, full of liquid carbon dioxide.

Ellie had active ways to probe the Eye too. She had set up an array of lasers and small particle guns, trained on the Eye like the rifles of a firing squad. These could mimic the Eyes own leakage of radiation and particlesand it was through manipulating this input to the Eye that Ellie had, remarkably, been able to send signals to Bisesas mobile phone, abandoned in another world.

The neutrino work was a little coarse however, the particle-detection array standard off-the-shelf gear. Ellie was most animated by her gravity wave detector.

She had devised this herself for the peculiar conditions of the Martian cap. Shed borrowed Hanses moles, smart little hot-nosed burrowers intended to explore the interior of the ice. She had had them create a network of long straight-line tunnels through which high-frequency laser light was passed back and forth. The theory was that any change in the peculiar gravity field of the Eye itself, or of the Martian containment cage, would cause the emission of gravity waves. The waves would make the polar ice shudder, and those minute disturbances would be detected as subtle shifts in the laser light.

Its a tricky setup, Ellie said with some pride. Gravity waves are notoriously weak. Mars is geologically quiet, but you do get the odd tremor. And the polar ice itself flows, minutely. But you can factor all that out. I have secondary arrays on the surface and in orbit. The most impressive is based on a couple of stations on the moons, Phobos and Deimos; when they are in line of sight of each other you get a good long baseline...

And with all this stuff youre studying the Eye. Not just the Eye. The Martian cage as well. Ellie said the Eye and the cage of folded spacetime that contained it were like two components of a mutually interlocked system, yin and yang. And it was a dynamic system; the components continually tested each other. This silent, eons-long battle spilled particles and radiation and gravity waves that Ellie was able to detect and analyze.

In a sense the Martian technology is more interesting to me, she told Myra. Because I have a feeling its closer to our own in development level, and therefore weve got a better chance of understanding it.

Right. And if you can figure it out? What then?

She shrugged, her motion magnified clumsily by the servos in her suit. If we could manipulate spacetime theres no limit to what we might achieve. Architecture beyond the constraints of gravity. Artificial gravity fields. Antigravity fields. Reactionless space drives. Tractor beams. Why, we might even make our own toy universes, like the Mir universe.

Myra grunted. You ought to patent this stuff.

Ellie looked at her through her visor, coolly. I think ensuring a technology like that gets into the right hands is more important than making money. Dont you?

Ellie had a self-righteous streak that Myra didnt particularly take to. Sure. Joke. She was reminded that she was basically unwelcome here. She prepared to leave.

But Ellie called her back.

There is something else, she said, more hesitantly. Tell me.

Im not sure... Ellie paused. Put it this way. I dont think every element of the gravity-field structure Im detecting has to do with engineering. Theres a level of detail in there thats so intricateI think of it as baroqueit has to have a meaning beyond the functional.

Myra had lived with Eugene Mangles long enough to be able to detect academic caution, and she decoded that negative statement with ease. If its not functional, then what? Symbolic?

Yes. Possibly.

Myras imagination raced. You think there are symbols in there? In the gravity field? What kind of symbolswriting, images? Recorded in a lattice of spacetime? Thats incredible.

Ellie ignored that last remark. Myra realized she wouldnt be saying anything about this unless it were, in fact, credible, and demonstrable. Writing is a closer analogy, I think. Im finding symbols of certain kinds, repeated across the field. Glyphs. And they come in clusters. Again, some of those clusters are repeated.

Clusters of glyphs. Words?

Or maybe sentences. I mean, if each glyph represents a concept in itselfif a glyph is an ideogram rather than a letter. Ellie seemed to lose a little confidence; she clearly had a scientists deep desire not to make a fool of herself. When she spoke again her voice was a bray, her volume control poor, her social skills evaporating with her tension. You realize how unlikely all this is. We have plenty of models of alien intelligences with no symbolic modes of communication at all. If you and I were telepathic, you see, we wouldnt need letters and spoken words to talk to each other. So theres no a priori reason to have expected the Martian builders of this cage to have left any kind of message.

And yet, if youre right, they did. Myra glared up at the trapped Eye. Maybe we should have expected this. After all, they made a strong statement just by leaving this Eye here, trapped. Look what we did. We fought back. We cut off the arm of the monster... I dont suppose No, I havent decoded any of it. Whatever is in there is complex; not a linear array of symbols, like letters in a row, but a matrix in three-space, and maybe even higher dimensions. If the glyphs are real, they are surely given meaning positionally as well as from their form.

There has to be a starting point, Myra said. A primer.

Ellie nodded inside her suit. Im trying to extract some of the most common symbol strings.

Myra studied her. Ellies eyes were masked, even behind her faceplate, by her spectacles; her expression was cold. Myra realized she knew almost nothing about this woman, who might be in the middle of making the discovery of the age; they had barely spoken in the long months Myra had been here.

Myra fetched them both coffees. These came in pouches you had to dock to a port on the side of your helmet. She asked, Where are you from, Ellie? The Low Countries?

Holland, actually. Delft. I am a Eurasian citizen. As you are, yes?

Forgive me but Im not sure how old you are.

I was two years old when the sunstorm hit, Ellie snapped. So she was twenty-nine now. I do not remember the storm. I do remember the refugee camps where my parents and I spent the next three years. My parents discouraged me from following my vocation, which was an academic career. After the storm there was much reconstruction to be done, they said. I should work on that, be an architect or an engineer, not a physicist. They said it was my duty.

I guess you won the argument.

But I lost my parents. I think they wished me to suffer as they had suffered, for the sunstorm had destroyed their home, all they had built, their plans. Sometimes I think they wished they had failed, that the storm had smashed everything up, for then they would not have raised ungrateful children who did not understand.

This torrent of words took Myra aback. When you open up, you open up all the way, dont you, Ellie? And is that why youre here, working on this Eye? Because of what the sunstorm did to your family?

No. I am here because the physics is fascinating.

Sure you are. Ellieyou havent told anybody else about the cage symbology, have you? None of your crewmates here. Then why me?

Unexpectedly Ellie grinned. I needed to tell somebody. Just to see if I sounded completely crazy. Even though you arent qualified to judge the quality of the work, or the results.

Of course not, Myra said dryly. Im glad you told me, Ellie. An alarm chimed softly in her helmet, and her suit told her she was due to meet Hanse for her ride back to the surface. Let me know when you find out something more.

I will. And Ellie turned back to her work, her cage of instruments, and the invisible gravitational battle of alien artifacts.

35: POSEIDONS BARB.

Bisesa, Emeline White, and the young Abdikadir Omar were to cross the Atlantic Ocean aboard a vessel called Poseidons Barb. She was, to Bisesas eyes, an extraordinary mixture of Alexandrian trireme and nineteenth-century schooner: the Cutty Sark with oars. She was under the command of an English-speaking Greek who treated his passengers with the utmost respect, once Abdikadir had handed over a letter of safe conduct from Eumenes.

They had to spend weeks at the rudimentary port at Gibraltar, waiting for a ship. Transatlantic travel wasnt exactly common yet in this world. It was a relief when they got underway at last.

The Barb cut briskly through the gray waters of an Atlantic summer. The crew worked with a will, their argot a collision of nineteenth-century American English with archaic Greek.

Bisesa spent as much time as she could on deck. She had once flown choppers, and wasnt troubled by the sea. Nor was Emeline, but poor landlubber Abdikadir spent a lot of time nursing a heaving gut.

Emeline became more confident in herself once they had cast off from Gibraltar. The ship was owned by a consortium of Babylonians, but its technology was at least half American, and Emeline seemed glad to shake off the dirt of the strange Old World. We found each other by boat, she told Bisesa. We Chicagoans came down to the sea by the rivers, all the way to the Mississippi delta, while the Greeks came across the ocean in their big rowboats, scouting down the east coast and the Gulf. We showed the Alexandrians how to build masts that wouldnt snap in an ocean squall and better ways to run their rigging, and in turn we have their big rowboats traveling up and down the Mississippi and the Illinois. It was a pooling of cultures, Josh liked to say.

No steamships, Bisesa said.

Not yet. We have a few steamboats on Lake Michigan, that came with us through the Freeze. But we arent geared up for the ocean. We may need steam if the ice continues to push south. And she pointed to the north.

According to the phone s star sightingsit grumpily complained about the lack of GPS satellitesthey were somewhere south of Bermuda, perhaps south of the thirtieth parallel. But even so far south, Emelines pointing finger picked out an unmistakable gleam of white.

During the voyage, on the neutral territory of the sea, Bisesa tried to get to know her companions better.

Abdi was bright, young, unformed, refreshingly curious. He was a unique product, a boy who had been taught to think both by his modern-British father, and by Greeks who had learned at the feet of Aristotle. But there was enough of his father about him to make Bisesa feel safe, in a way she had always felt with the first Abdi.

Emeline was a more complex case. The ghost of Josh always hovered between them, a presence of which they rarely spoke. And, though Emeline had felt impelled to cross the ocean to investigate the phone calls in Babylon, just as her husband would surely have done, she confided to Bisesa that she was uncomfortable with the whole business.

I was only nine when the world froze around Chicago. Most of my life has been occupied with the great project of survivalthats how Mayor Rice puts it. Were always busy. So its possible to put aside the great mystery of why were all here in the first placedo you see? Rather as one prefers not to contemplate ones own inevitable death. But now here you are Im an angel of death, Bisesa said grimly.

Youre hardly that, though you havent brought us good news, have you? But I can tell you Ill be glad when we reach Chicago, and I can get back to normal life!

During the nights, the phone asked Bisesa to take it up on deck to see the sky. She set up a little wooden stand for it, strapping it down so it wouldnt tumble as the ship rolled.

Mir was a turbulent world, its climate as cobbled together as its geology, and not yet healed. For astronomers, the seeing was generally poor. But in mid-Atlantic the skies were as clear of cloud and volcanic ash as Bisesa had seen anywhere. She patiently allowed the phone to peer at the stars, reinforcing the observations it had made itself when Mir had first formed, and the sightings of the Babylonian astronomers since. It sent images back to the Little Birds old radio receivers in Babylon, and from there, it was hoped, through the Eye to the true universe.

And, prompted by the phone, she looked for the cool misty band of the Milky Way, wondering if it was more pale, more scattered than she remembered.

By assembling the observations made by Abdi and by the phone itself, the phone and the brain trust back on Mars had been able to determine that the universe in which Mir was embedded was expanding, dramatically. For example the Andromeda Galaxy, the nearest large galaxy to the Milky Way, was receding fast. The cosmologists had likened this to the expansion of Earths own universe, fueled by a kind of dark energy, an antigravity field called quintessence. This quintessence was pulling Bisesas universe apart too. It was just that it was happening a lot earlier, here.

It was on this basis that the prediction of a universal ending relatively soon had been made, though the numbers were still imprecise. The phone believed that the recession might already be reaching into the structure of the Galaxy itself, with distant stars showing red shifts. The end of the world might already be visible in the sky, if you knew how to look.

And the phone pointed out the planets to Bisesa: Mars in the evenings, Venus a bright morning star. We never saw them, last time, the phone whispered. When I studied the sky, trying to date Mir. I remember.

The seeing was too poor, always. I never noticed how they were different... Both Mars and Venus, siblings of Earth, were chips of sky blue.

36: HUBBLE.

January 2070 Drifting above the Earth, the telescope was a fat double cylinder, thirteen meters long, its two big flat solar-cell panels angled toward the sun.

The slimmer forward cylinder, properly known as the forward shell, was open at the far end, with a hinged cover. At the base of the forward shellinside the short, squat cylinder known as the aft shroudwas a mirror, a disk over two meters across. The mirror was precision-ground, shaped from low-expansion titanium silicate glass, with a covering of aluminium-magnesium fluoride. Light collected by this primary mirror was focused onto a smaller secondary, and then reflected back through a gap in the primary to a cluster of scientific instruments. The instruments included cameras, spectral analyzers, and light intensity and polarization calibrators.

There were handrails fixed to the exterior of the hull. The telescope had been designed to fit into the payload bay of a space shuttle orbiter, and, with its modularity and ease of access, to be capable of regular maintenance by astronaut engineers.

As a space project the telescope had been fraught by expense, delays, and overruns, caught up in the politics of NASAs long-drawn-out decline. Its launch had been delayed for years by the Challenger disaster. When it was finally deployed, the first images it returned were flawed by a spherical aberration, a mirror defect a fraction the width of a human hair that had eluded detection during testing. It took more years before another shuttle flight brought up a corrective lens system to compensate for the aberration.

But it was the culmination of an old dream of the first space visionaries to place a telescope above the murk of Earths atmosphere. The telescope was able to view features two hundred kilometers across on the cloud tops of Jupiter.

The telescope was said to be NASAs most popular mission with the public since the Moon landings. Decades after its launch the telescopes images still adorned softwalls and image-tattoos.

But the shuttle maintenance missions were always hugely expensive, and after the Columbia catastrophe became even more infeasible. And the telescope itself aged. Astronauts replaced worn-out gyroscopes, degraded solar panels, and torn insulation, but the optical surfaces were subject to wear from sunlight, micrometeorite and spacecraft debris impacts, and corrosion from the thin, highly reactive gases of Earths upper atmosphere.

At last the telescope was made redundant by a younger, cheaper, more effective rival. It was ordered to position itself to reduce atmospheric drag to a minimum: mothballed in orbit, until a more favorable funding environment might prevail in the future. Its systems were made quiescent. The aperture door over the forward shell closed: the telescope shut its single eye. Decades passed.

The telescope was fortunate to survive the sunstorm.

And after the storm came a new era, a new urgency, when eyes in the sky were at a premium.

Five years after the sunstorm, a spacecraft at last came climbing up from Earth to visit the telescope once more, not a shuttle but a technological descendant. The spaceplane carried a manipulator arm and kits of antiquated replacement parts. Astronauts replaced the damaged components, revived the telescopes systems, and returned to Earth.

The telescope opened its eye once more.

More years passed. And then the telescope saw something.

It seemed to many appropriate that the oldest of Earths space telescopes should be the first of any system based on or close to the home planet to pick out the approaching Q-bomb.

In her Mount Weather office, Bella Fingal peered at the Hubble images, of a teardrop distortion sliding across the stars. There was less than a year left until the bomb was due to reach Earth. Horror knotted her stomach.

She called Paxton. Get in here, Bob. We cant just sit and wait for this damn thing. I want some fresh options.

37: NEW NEW ORLEANS.

On the last day of the voyage, the Barb nosed through a complex delta system. Even Abdikadir came on deck to see. This was the outflow of the Mississippi, but sea levels were so much lower in this world of an incipient ice age that the delta pushed far out into the Gulf. There was certainly no New Orleans in this version of the world. And amid dense reed banks, watched by nervous crew, alligators the size of small trucks nosed into the water.

The Barb was rowed cautiously into a small harbor. Bisesa glimpsed wharves and warehouses; one jetty had a kind of wooden crane. Behind the port buildings was a tiny township of huddled wooden shacks.

Welcome to New New Orleans, Emeline said dryly. There really isnt much of it. But we do what we can.

Abdikadir murmured what sounded like a prayer in guttural Greek. Bisesa. I had been wondering what machines these Americans have used to dredge out their harbors. Look over there.

Through the mist rising off the open water, Bisesa glimpsed what looked like elephants, treading slowly. Harnessed with thick ropes in a team of four, they were dragging some immense engine. But the beasts had odd profiles, with small domed skulls and humps on their backs. The men who drove them with goads and whips were dwarfed by their beasts, which looked tremendously tall, surely taller than the African elephants of Bisesas day. Then one of them lifted its head and trumpeted, a thin, stately sound, and Bisesa saw extraordinarily long tusks curved in loose spirals.

Those arent elephants, are they?

Welcome to America, Emeline said dryly. We call these Jeffersons mammoths. Some say imperial and some Columbian, but in Chicago were patriots, and Jefferson it is.

Abdikadir was intrigued. Are they easy to tame?

Not according to the stories in the newspapers, Emeline said. We imported some elephant trainers from India; our men were just carnie folk who had been making it up as they went along. The Indians grumbled that the thousands of years they had put into breeding their own strain of elephant into docility had all been rubbed out here. Now come. We have a train to catch...

The passengers disembarked, with their few items of luggage. The dockworkers didnt show much interest in the new arrivals, despite their Macedonian garb.

It was summer, and they were somewhere south of the latitude of old New Orleans. But the wind from the north was chill.

There was no train station here, just a place where a crudely-laid line came to an end amid a heap of sleepers and rusty, reused rails. But a row of carriages sat behind a hissing, old-fashioned-looking loco that hauled a fuel cart full of logs.

Emeline negotiated directly with the engine driver; she used dollar notes to pay for their passage. And she was able to buy a loaf, some beef jerky, and a pot of coffee in the towns small bar. Her money was crisp and new; evidently Chicago had a mint.

Back in her own environment, Emeline was bright and purposeful. Bisesa had to admit there was a sense of modernity here, even in this scrubby outpost, that had been missing in an Alexandrian Europe that seemed to be sinking back into the past.

On the train they had a carriage to themselves; the other carriages were mostly full of goods, lumber, fleeces, a catch of salted fish. The windows werent glazed, but there were blinds of some kind of hide that would block out the drafts, and heaps of blankets of some thick, smelly orange-brown wool. Emeline assured them that this would be enough to keep them warm until they reached New Chicago. After that youll need cold-weather gear for the ice, she said. Well pick up something in town.

A couple of hours after they had arrivedit was around noonthe locomotive belched white smoke, and the train lumbered into motion. There was a clucking as chickens scattered off the tracks. A few skinny-looking children came running from the rude houses to wave, and Abdi and Bisesa waved back. The wind turned, and smoke from the stack blew into the cabin: wood smoke, a familiar, comforting scent.

Emeline said they were going to follow the valley of the Mississippi, all the way to the settlement of New Chicago, which was near the site of Memphis in the old world. It was a journey of a few hundred miles that would likely take twenty-four hours to make; they would sleep on the train.

Bisesa peered curiously from her window. She saw traffic on the river, a real mix, an Alexandrian trireme, what looked like a paddle steamer stranded by the shoreand a couple of canoes that might have been native American, but no native Americans had been brought to Mir.

Emeline said, They dug a couple of war canoes out of the city museum and the worlds fair exhibits. Took them apart to see how they were made. They raided William Codys Wild West Show too, for bows and arrows and teepees and whatnot. The canoes are pretty, arent they? I tried one once, with Josh, for a lark. But the water is dashed cold, even so far south as this. Runoff from the ice. You dont want to fall in!