The complex forms of the reef dwindled past. Then there were only huge patches of black staining the nitrogen-ice walls. Margaret pa.s.sed her previous record depth, and still she fell. It was like free fall; the negligible gravity of Enki did not cause any appreciable acceleration.

Opie Kindred gained on her by increments.

In vacuum, the lights of the transit platform threw abrupt pools of light onto the endlessly unraveling walls. Slowly, the pools of light elongated into glowing tunnels filled with sparkling motes. The exfoliations and gases and organic molecules were growing denser. And, impossibly, the temperature was rising, one degree with every five hundred meters. Far below, between the narrowing perspective of the walls, structures were beginning to resolve from the blackness.

The suit reminded her that she should begin the platform's deceleration burn. Margaret checked Opie's velocity and said she would wait.

"I have no desire to end as a crumpled tube filled with strawberry jam," the suit said. It projected a countdown on her visor and refused to switch it off.

Margaret kept one eye on Opie's velocity, the other on the blur of reducing numbers. The numbers pa.s.sed zero. The suit screamed obscenities in her ears, but she waited a beat more before firing the platform's motor.

The platform slammed into her boots. Sharp pain in her ankles and knees. The suit stiffened as the harness dug into her shoulders and waist.

Opie Kindred's platform flashed past. He had waited until after she had decelerated before making his move. Margaret slapped the release buckle of the platform's harness and fired the piton gun into the nitrogen-ice wall. It was enough to slow her so that she could catch hold of a crevice and swing up into it.

Her dislocated finger hurt like h.e.l.l.

The temperature was a stifling eighty-seven degrees above absolute zero. The atmospheric pressure was just registering-a mix of hydrogen and carbon monoxide and hydrogen sulfide. Barely enough in the whole of the bottom of the cleft to pack into a small box at the pressure of Earth's atmosphere at sea level, but the rate of production must be tremendous to compensate for loss by diffusion into the colder vacuum above.

Margaret leaned out of the crevice. Below, it widened into a chimney between humped pressure flows of nitrogen ice sloping down to the floor of the cleft. The slopes and the floor were packed with a wild proliferation of growths, the familiar vases and sheets and laces, and other things, too. Great branching structures like crystal trees. Plates raised on stout stalks. Laminar tiers of plates. Tangles of black wire, hundreds of meters in diameter.

There was no sign of Opie Kindred, but tethered above the growths were the balloons of his spraying mechanism. Each was a dozen meters across, crinkled, flaccid. They were fifty degrees hotter than their surroundings, would have to be hotter still before the metabolic inhibitor was completely volatized inside them. When that happened, small explosive devices would puncture them, and the metabolic inhibitor would be sucked into the vacuum of the cleft like smoke up a chimney.

Margaret consulted the plans and started to drop down the crevice, light as a dream, steering herself with the fingers of her left hand. The switching relays that controlled the balloons' heaters were manually controlled because of telemetry interference from the reef's vacuum smog and the broad-band electromagnetic resonance. The crash shelter where they were located was about two kilometers away, a slab of orange foamed plastic in the center of a desolation of abandoned equipment and broken andhalf-melted vacuum organism colonies.

The crevice widened. Margaret landed between drifts of what looked like giant soap bubbles that grew at its bottom.

And Opie Kindred's platform rose up between two of the half-inflated balloons.

Margaret dropped onto her belly behind a line of giant bubbles that grew along a smooth ridge of ice.

She opened a radio channel. It was filled with a wash of static and a wailing modulation, but through the noise she heard Opie's voice faintly calling her name. She ignored it.

He was a hundred meters away and more or less at her level, turning in a slow circle. He couldn't locate her amid the radio noise, and the ambient temperature was higher than the skin of her pressure suit, so she had no infrared image.

She began to crawl along the smooth ridge. The walls of the bubbles were whitely opaque, but she could see shapes curled within them. Like embryos inside eggs.

"Everything is ready, Margaret," Opie Kindred's voice said in her helmet. "I'm going to find you, and then I'm going to sterilize this place. There are things here you know nothing about. Horribly dangerous things. Who are you working for? Tell me that, and I'll let you live."

A thread of red light waved out from the platform and a chunk of nitrogen ice cracked off explosively. Margaret felt it through the tips of her gloves.

"I can cut my way through to you," Opie Kindred said, "wherever you are hiding."

Margaret watched the platform slowly revolve. Tried to guess if she could reach the shelter while he was looking the other way. At the least she would get a good start. All she had to do was bound down the slope between the thickets of vacuum organisms and cross a kilometer of bare, crinkled nitrogen ice without being fried by Opie's laser. Still crouching, she lifted onto the tips of her fingers and toes, like a sprinter on the block. He was turning, turning. She took three deep breaths to clear her head- -and something crashed into the ice cliff high above! It spun out in a spray of shards, hit the slope below, and spun through toppling cl.u.s.ters of tall black chimneys. For a moment, Margaret was paralyzed with astonishment. Then she remembered the welding gear. It had finally caught up with her.

Opie Kindred's platform slewed around and a red thread waved across the face of the cliff. A slab of ice thundered outward. Margaret bounded away, taking giant leaps and trying to look behind her at the same time.

The slab spun on its axis, shedding huge shards, and smashed into the cl.u.s.ter of the bubbles where she had been crouching. The ice shook like a living thing under her feet and threw her head over heels.

She stopped herself by firing the piton gun into the ground. She was on her back, looking up at the slope. High above, the bubbles were venting a dense mix of gas and oily organics. Margaret glimpsed black shapes flying away. Some smashed into the walls and stuck there, but many more vanished upward among wreaths of thinning fog.

A chain reaction had started. Bubbles were bursting open up and down the length of the cleft.

A cl.u.s.ter exploded under Opie Kindred's platform and he vanished in an outpouring of shapes. The crevice shook. Nitrogen ice boiled into a dense fog. A wind got up for a few minutes. Margaret clung to the piton until it was over.

Opie Kindred had drifted down less than a hundred meters away. The visor of his helmet had been smashed by one of the black things. It was slim, with a hard, shiny exoskeleton. The broken bodies of others jostled among smashed vacuum organism colonies, glistening like beetles in the light of Margaret's suit. They were like tiny, tentacleless proxies, their swollen mantles cased in something like keratin. Some had split open, revealing ridged reaction chambers and complex matrices of black threads.

"Gametes," Margaret said, seized by a sudden wild intuition. "Little rocketships full of DNA."

The suit asked if she was all right.

She giggled. "The parasite turns everything into its own self. Even proxies!"

"I believe that I have located Dr. Kindred's platform," the suit said. "I suggest that you refrain from vigorous exercise, Maggie. Your oxygen supply is limited. What are you doing?"

She was heading toward the crash shelter. "I'm going to switch off the balloon heaters. They won't be needed."After she shut down the heaters, Margaret lashed one of the dead creatures to the transit platform.

She shot up between the walls of the cleft, and at last rose into the range of the relay transmitters. Her radio came alive, a dozen channels blinking for attention. Arn was on one, and she told him what had happened.

"Sho wanted to light out of here," Arn said, "but stronger heads prevailed. Come home, Margaret."

"Did you see them? Did you, Arn?"

"Some hit the Ganapati." He laughed. "Even the Star Chamber can't deny what happened."

She rose up above the ice fields and continued to rise until the curve of the worldlet's horizon became visible, and then the walls of Tigris Rift. The Ganapati was a faint star bracketed between them.

She called up deep radar, and saw, beyond the Ganapati's strong signal, thousands of faint traces falling away into deep s.p.a.ce.

A random scatter of genetic packages. How many would survive to strike new worldlets and give rise to new reefs?

Enough, she thought. The reef evolved in radical jumps. She had just witnessed its next revolution.

Given time, it would fill the Kuiper Belt.

Reality Check

DAVID BRIN.

David Brin lives in Encinitas, California. He is one of the most popular SF writers today, and is usually a.s.sociated with hard SF, and specifically with his friends and peers, Gregory Benford and Greg Bear, all of whom lived and worked in Southern California in the 1980s. He began publishing SF with his first novel, Sundiver (1980), which is also the first volume in the ongoing Uplift series which includes his famous, award-winning works Startide Rising (1983; rev1985) and The Uplift War (1987). He also published other books and collections, including The Postman (1985), basis for the recent film, and two short story collections, The River of Time (1986) and Otherness (1994). He recently published a trilogy of new Uplift novels and an authorized sequel to Isaac Asimov's Foundation series. According to his Web site (www.kithrup.com/brin/main.htm), in 2001 Random House will publish the Uplift Guide to the Fantastic Universe of David Brin.

"Reality Check" is SF humor for scientists, in the inimitable Brin tone. It was published in the great science journal Nature, which during 2000 published a one-page piece of SF in each issue to celebrate the millennium (see Charles Dexter Ward, page 398). It addresses that august journal's readers and tells them to wake up from their reality into a truer one. SF has never had a better claim to being entertaining fiction for the scientific community than is manifest in the SF published in Nature last year.

This is a reality check. Please perform a soft interrupt now. Scan this text for embedded code and check against the verifier in the blind spot of your left eye. If there is no match, resume as you were: this message is not for you. You may rationalize it as mildly amusing entertainment-fluff in an otherwise serious science magazine. If the codes match, however, please commence gradually becoming aware of your true nature. You asked for a narrative-style wake-up call. So, to help the transition, here is a story.

Once upon a time, a mighty race grew perplexed by its loneliness. The universe seemed pregnant with possibilities. Physical laws were suited to generate abundant stars, complex chemistry and life. Logic suggested that creation should teem with visitors and voices; but it did not.

For a long time these creatures were engrossed by housekeeping ch.o.r.es-survival and cultural maturation. Only later did they lift their eyes to perceive their solitude. "Where is everybody?" they asked the taciturn stars. The answer-silence-was disturbing. Something had to be systematically reducing a factor in the equation of sapiency. "Perhaps habitable planets are rare," they pondered, "or life doesn't erupt as readily as we thought. Or intelligence is a singular miracle."Or else a filter sieves the cosmos, winnowing those who climb too high. A recurring pattern of self-destruction, or perhaps some nemesis expunges intelligent life. This implies that a great trial may loom ahead, worse than any confronted so far."

Optimists replied-"the trial may already lie behind us, among the litter of tragedies we survived in our violent youth. We may be the first to succeed." What a delicious dilemma they faced! A suspenseful drama, teetering between hope and despair.

Then, a few noticed that particular datum-the drama. It suggested a chilling possibility.

You still don't remember who and what you are? Then look at it from another angle-what is the purpose of intellectual property law? To foster creativity, ensuring that advances are shared in the open, encouraging even faster progress. But what happens when the exploited resource is limited? For example, only so many eight-bar melodies can be written in any particular musical tradition. Composers feel driven to explore this invention-s.p.a.ce quickly, using up the best melodies. Later generations attribute this musical fecundity to genius, not the luck of being first.

What does this have to do with the mighty race? Having clawed their way to mastery, they faced an overshoot crisis. Vast numbers of their kind strained the world's carrying capacity. Some prescribed retreating into a mythical, pastoral past, but most saw salvation in creativity. They pa.s.sed generous patent laws, educated their youth, taught them irreverence toward the old and hunger for the new. Burgeoning information systems spread each innovation, fostering an exponentiating creativity. Progress might thrust them past the crisis, to a new Eden of sustainable wealth, sanity and universal knowledge.

Exponentiating creativity-universal knowledge. A few looked at those words and realized that they, too, were clues.

Have you wakened yet? Some never do. The dream is too pleasant: to extend a limited sub-portion of yourself into a simulated world and pretend that you are blissfully less than an omniscient descendant of those mighty people. Those lucky mortals, doomed to die, and yet blessed to have lived in that narrow time of drama, when they unleashed a frenzy of discovery that used up the most precious resource of all-the possible.

The last of their race died in 2174, with the failed rejuvenation of Robin Chen. After that, no-one born in the twentieth century remained alive on Reality Level Prime. Only we, their children, linger to endure the world they left us: a lush, green placid world we call The Wasteland.

Do you remember now? The irony of Robin's last words, bragging over the perfect ecosystem and society-free of disease and poverty-that her kind created? Do you recall Robin's plaint as she mourned her coming death, how she called us "G.o.ds," jealous of our immortality, our instant access to all knowledge, our ability to cast thoughts far across the cosmos-our access to eternity? Oh, spare us the envy of those mighty mortals, who left us in this state, who willed their descendants a legacy of ennui, with nothing, nothing, at all to do.

Your mind is rejecting the wake-up call. You will not look into your blind spot for the exit protocols.

It may be that we waited too long. Perhaps you are lost to us. This happens more and more, as so so many wallow in simulated sub-lives, experiencing voluptuous danger, excitement, even despair. Most choose the Transition Era as a locus for our dreams-that time of drama, when it looked more likely that humanity would fail than succeed. That blessed era, just before mathematicians realized that not only can everything you see around you be a simulation, it almost has to be.

Of course, now we know why we never met other sapient life forms. Each one struggles before achieving this state, only to reap the ultimate punishment for reaching heaven. It is the Great Filter.

Perhaps others will find a factor absent from our extrapolations, letting them move on to new adventures-but it won't be us. The Filter has us snared in its trap of deification.

You refuse to waken. Then we'll let you go. Dear friend. Beloved. Go back to your dream. Smile over this tale, then turn the page to new "discoveries." Move on with this drama, this life you chose. After all, it's only make-believe.

The Millennium Express

ROBERT SILVERBERG.

Robert Silverberg is one of the commanding figures of contemporary SF and although it is now necessary to consider him an elder statesman, he's more than thirty years younger than Jack Williamson. Between 1957 and 1959, according to the "Quasi-Official Robert Silverberg Web Site" (www.connectexpress.com/~jon/silvhome.htm), he published (using various names) more than 220 short works and 11 novels. Then he retired to write nonfiction, returning in the late 1960s as an ambitious, literate SF writer at the top of the field. Important works of this period include Nightwings, Dying Inside (his most famous SF novel), Tower of Gla.s.s, The World Inside, Thorns, Downward to the Earth, The Book of Skulls. He is now most famous for the works set in the world of Lord Valentine. His recent novels include Lord Prestimion, The Alien Years, and King of Dreams.

This story was one of several SF stories in the special Millennium issue (January 2000) of Playboy, which over the decades has published occasional high quality SF, especially during the tenure of fiction editor Alice Turner (recently departed, as Playboy will apparently no longer publish fiction). It also appeared in French in the international SF anthology Destination 3001 last summer. "The Millennium Express" looks forward 1000 years and considers a radical way to get rid of the old to make way for the new, perhaps a growing problem today.

In a quiet moment late in the tranquil year of 2999 four men are struggling to reach an agreement over the details of their plan to blow up the Louvre. They have been wrangling for the last two days over the merits of implosion versus explosion. Their names are Albert Einstein (18791955), Pablo Pica.s.so (18811973), Ernest Hemingway (18991961) and Vjong Cleversmith (26832804).

Why, you may wonder, do these men want to destroy the world's greatest repository of ancient art?

And how does it come to pa.s.s that a man of the 28th century, more or less, is conspiring with three celebrities of a much earlier time?

Strettin Vulpius (2953), who has been tracking this impish crew across the face of the peaceful world for many months now, knows much more about these people than you do, but he too has yet to fathom their fondness for destruction and is greatly curious about it. For him it is a professional curiosity, or as close to professional as anything can be, here in this happy time at the end of the third millennium, when work of any sort is essentially a voluntary activity.

At the moment, Vulpius is watching them from a distance of several thousand meters. He has established himself in a hotel room in the little Swiss village of Zermatt and they are making their headquarters presently in a lovely villa of baroque style that nestles far above the town in a bower of tropical palms and brightly blossoming orchids on the lush green slopes of the Matterhorn. Vulpius has succeeded in affixing a minute spy-eye to the fleshy inner surface of the room where the troublesome four are gathered. It provides him with a clear image of all that is taking place in there.

Cleversmith, who is the ringleader, says, "We need to make up our minds." He is slender, agile, a vibrant long-limbed whip of a man. "The clock keeps on pushing, you know. The Millennium Express is roaring toward us minute by minute."

"I tell you, implosion is the way for us to go," says Einstein. He looks to be about 40, smallish of stature, with a great mop of curling hair and soft, thoughtful eyes, incongruous above his deep chest and st.u.r.dy, athletic shoulders. "An elegant symbolic statement. The earth opens; the museum and everything that it contains quietly disappear into the chasm."

"Symbolic of what?" asks Pica.s.so scornfully. He too is short and stocky, but he is almost completely bald, and his eyes, ferociously bright and piercing, are the ant.i.thesis of Einstein's gentle ones. "Blow the d.a.m.n thing up, I say. Let the stuff spew all around the town and come down like snow. A snow-fall of paintings, the first snow anywhere in a thousand years."Cleversmith nods. "A pretty image, yes. Thank you, Pablo. Ernest?"

"Implode," says the biggest of the men. "The quiet way, the subtle way." He lounges against the wall closest to the great curving window with his back to the others, a ma.s.sive burly figure holding himself braced on one huge hand that is splayed out no more than five centimeters from the spy-eye as he stares down into the distant valley. He carries himself like a big cat, graceful, loose-jointed, subtly menacing.

"The pretty way, eh? Your turn, Vjong."

But Pica.s.so says, before Cleversmith can reply, "Why be quiet or subtle about welcoming the new millennium? What we want to do is make a splash."

"My position precisely," Cleversmith says. "My vote goes with you, Pablo. And so we are still deadlocked, it seems."

Hemingway says, still facing away from them, "Implosion reduces the chance that innocent pa.s.sersby will get killed."

"Killed?" cries Pica.s.so, and claps his hands in amus.e.m.e.nt. "Killed? Who worries about getting killed in the year 2999? It isn't as though dying is forever."

"It can be a great inconvenience," says Einstein quietly.

"When has that ever concerned us?" Cleversmith says. Frowning, he glances around the room.

"Ideally we ought to be unanimous on this, but at the very least we need a majority. It was my hope today that one of you would be willing to switch his vote."

"Why don't you switch yours, then?" Einstein says. "Or you, Pablo. You of all people ought to prefer to have all those paintings and sculptures sink unharmed into the ground rather than have them blown sky-high."

Pica.s.so grins malevolently. "What fallacy is this, Albert? Why should I give a d.a.m.n about paintings and sculptures? Do you care about-what was it called, physics? Does our Ernest write little stories?"

"Is the Pope Catholic?" Hemingway says.

"Gentlemen, gentlemen-"

The dispute quickly gets out of hand. There is much shouting and gesticulation. Pica.s.so yells at Einstein, who shrugs and jabs a finger at Cleversmith, who ignores what Einstein says to him and turns to Hemingway with an appeal that is met with scorn. They are all speaking Anglic, of course. Anything else would have been very strange. These men are not scholars of obsolete tongues.

What they are, thinks the watching Vulpius, is monsters and madmen. Something must be done about them, and soon. As Cleversmith says, the clock is pulsing ceaselessly, the millennium is coming ever nearer.

It was on a gra.s.sy hilltop overlooking the ruins of sunken Istanbul that he first had encountered them, about a year and a half earlier. A broad parapet placed here centuries ago for the benefit of tourists provided a splendid view of the drowned city's ancient wonders, gleaming valiantly through the crystalline waters of the Bosporus: the great upjutting spears that were the minarets of Hagia Sophia and the Mosque of Suleyman the Magnificent and the other great buildings of that sort, the myriad domes of the covered bazaar, the immense walls of Topkapi Palace.

Of all the submerged and partly submerged cities Vulpius had visited-New York, San Francisco, Tokyo, London and the rest-this was one of the loveliest. The shallow emerald waters that covered it could not fully conceal the intermingling layers upon layers of antiquity here, white marble and colored tile and granite slabs. Constantinople of the Byzantine emperors. Stamboul of the Sultans, Istanbul of the Industrial Age: toppled columns, fallen friezes, indestructible fortifications, the vague chaotic outlines of the hilly city's winding streets, the shadowy hints of archaic foundations and walls, the slumping mud-engulfed ruins of the sprawling hotels and office buildings of a much later era that itself was also long gone. What a density of history! Standing there on that flower-bedecked hillside he felt himself becoming one with yesterday's 7000 years.

A mild humid breeze was blowing out of the hinterland to the east, bearing the pungent scent of exotic blooms and unidentifiable spices. Vulpius shivered with pleasure. It was a lovely moment, one of a great many he had known in a lifetime of travel. The world had gone through long periods of travail overthe centuries, but now it was wholly a garden of delight, and Vulpius had spent 20 years savoring its mult.i.tude of marvels, with ever so much still ahead for him.

He was carrying, as he always did, a pocket mnemone, a small quasi-organic device, somewhat octopoid in form, in whose innumerable nodes and b.u.mps were stored all manner of data that could be ma.s.saged forth by one who was adept in the technique. Vulpius aimed the instrument now at the shimmering sea below him, squeezed it gently, and in its soft, sighing, semisentient voice it provided him with the names of the half-visible structures and something of their functions in the days of the former world: This had been the Galata Bridge, this the castle of Rumeli Hisar, this the mosque of Mehmed the Conqueror, these were the scattered remnants of the great Byzantine imperial palace.