1

Recently Harry Whitebook had found a method for increasing animal tolerance to CO2, by introducing into mammals a gene which coded for certain characteristics of crocodile hemoglobin. Crocodiles could hold their breath for a very long time underwater, and the CO2 that should have built up in their blood actually dissolved there into bicarbonate ions, bound to amino acids in the hemoglobin, in a complex that caused the hemoglobin to release oxygen molecules. High CO2 tolerance was thus combined with increased oxygenation efficiency, a very elegant adaptation, and as it turned out fairly easy (once Whitebook showed the way) to introduce into mammals by utilizing the latest trait transcription technology: designed strands of the DNA repair enzyme photolyase were assembled, and these would patch the descriptions for the trait into the genome during the gerontological treatments, changing slightly the hemoglobin properties of the subject.

Sax was one of the first people to have this trait administered to him. He liked the idea because it would obviate the need for a face mask in the outdoors, and he was spending a lot of his time outdoors. Carbon-dioxide levels in the atmosphere were still at about 40 millibars of the 500 total at sea level, the rest consisting of 260 millibars nitrogen, 170 millibars oxygen, and 30 of miscellaneous noble gases. So there was still too much CO2 for humans to tolerate without filter masks. But after trait transcription he could walk free in the air, observing the wide array of animals with similar trait transcriptions already out there. All of them monsters together, settling into their ecological niches, in a very confusing flux of surges, die-offs, invasions and retreats— everything vainly seeking a balance that could not, given the changing climate, exist. No different than life on Earth had ever been, in other words; but here all happening at a much faster rate, pushed by the human-driven changes, modifications, introductions, transcriptions, translations— the interventions that worked, the interventions that backfired— the effects unintended, unforeseen, unnoticed— to the point where many thoughtful scientists were giving up any pretense of control. “Let happen what may,” as Spencer would say when he was in his cups. This offended Michel’s sense of meaning, but there was nothing to be done about that, except to alter Michel’s sense of what was meaningful. Contingency, the flux of life: in a word, evolution. From the Latin, meaning the unrolling of a book. And not directed evolution either, not by a long shot. Influenced evolution perhaps, accelerated evolution certainly (in some aspects, anyway). But not managed, nor directed. They didn’t know what they were doing. It took some getting used to.

CHRYSE GULF

• • •

So Sax wandered around on Da Vinci Peninsula, a rectangular chunk of land surrounding the round rim hill of Da Vinci Crater, and bounded by the Simud, Shalbatana, and Ravi fjords, all of which debouched onto the southern end of Chryse Gulf. Two islands, Copernicus and Galileo, lay to the west, in the mouths of the Ares and Tiu fjords. A very rich braiding of sea and land, perfect for the burgeoning of life— the Da Vinci lab techs could not have chosen a better site, although Sax was quite sure they had had no sense at all of their surroundings when they chose the crater for the underground’s hidden aerospace labs. The crater had had a thick rim and was located a good distance from Burroughs and Sabishii, and that had been that. Stumbled into paradise. More than a lifetime’s observations to be made, without ever leaving home.

Hydrology, invasion biology, areology, ecology, materials science, particle physics, cosmology: all these fields interested Sax extremely, but most of his daily work in these years concerned the weather. Da Vinci Peninsula got a lot of dramatic weather; wet storms swept south down the gulf, dry katabatic winds dropped off the southern highland and out the fjord canyons, initiating big northward waves at sea. Because they were so close to the equator, the perihelion-aphelion cycle affected them much more than the ordinary inclination seasons. Aphelion brought cold weather twenty degrees north of the equator at least, while perihelion cooked the equator as much as the south. In the Januaries and Februaries, sun-warmed southern air lofted into the stratosphere, turned east at the tropopause and joined the jet streams in their circumnavigations. The jet streams were difluent around the Tharsis Bulge; the southern stream carried moisture from Amazonis Bay, and dumped it on Daedalia and Icaria, sometimes even on the western wall of the Argyre Basin mountains, where glaciers were forming. The northern jet stream ran over the Tempe-Mareotis highlands, then blew over the North Sea, picking up the moisture for storm after storm. North of that, over the polar cap, air cooled and fell on the rotating planet, causing surface winds from the northeast. These cold dry winds sometimes shot underneath the warmer wetter air of the temperate westerlies, causing fronts of huge thunderheads to rise over the North Sea, thunderheads twenty kilometers high.

The southern hemisphere, being more uniform than the north, had winds that followed even more clearly the physics of air over a rotating sphere: southeast trades from the equator to latitude thirty; prevailing westerlies from latitude thirty down to latitude sixty; polar easterlies from there to the pole. There were vast deserts in the south, especially between latitude fifteen and thirty, where the air that rose at the equator sank again, causing high air pressure and hot air that held a lot of water vapor without condensing; it hardly ever rained in this band, which included the hyperarid provinces of Solis, Noachis, and Hesperia. In these regions the winds picked up dust off the dry land, and the dust storms, while more localized than before, were also thicker, as Sax had witnessed himself, unfortunately, while up on Tyrrhena with Nirgal.

Those were the major patterns in Martian weather: violent around aphelion, gentle during the helionequinoxes; the south the hemisphere of extremes, the north of moderation. Or so some models suggested. Sax liked generating the simulations that created such models, but he was aware that their match with reality was approximate at best; every year on record was an exception of some kind, with conditions changing at each stage of the terraforming. And the future of their climate was impossible to predict, even if one froze the variables and pretended terraformation had stabilized, which it certainly had not. Over and over Sax watched a thousand years of weather, altering variables in the models, and every time a completely different millennium flitted past. Fascinating. The light gravity and the resulting scale height of the atmosphere, the vast vertical relief of the surface, the presence of the North Sea that might or might not ice over, the thickening air, the perihelion-aphelion cycle, which was an eccentricity that was slowly precessing through the inclination seasons; these had predictable effects, perhaps, but in combination they made Martian weather a very hard thing to understand, and the more he watched, the less Sax felt they knew. But it was fascinating, and he could watch the iterations play out all day long.

• • •

Or else just sit out on Simshal Point, watching clouds flow across hyacinth skies. Kasei Fjord, off to the northwest, was a wind tunnel for the strongest katabatic blows on the planet, winds pouring out of it onto Chryse Gulf at speeds that occasionally reached five hundred kilometers an hour. When these howlers struck Sax could see the cinnamon clouds marking them, over the horizon to the north. Ten or twelve hours later big swells would roll in from the north, and rise up and hammer the sea cliffs, fifty-meter-high wedges of water blasting to spray against the rock, until the air all over the peninsula was a thick white mist. It was dangerous to be at sea during a howler, as he had found out once while sailing the coastal waters of the southern gulf, in a little catamaran he had learned to operate.

Nicer by far to observe storms from the sea cliffs. No howler today; just a steady stiff wind, and the distant black broom of a squall on the water north of Copernicus, and the heat of sun on skin. Global average temperature changed every year, up and down, mostly up. With time as the horizontal axis, a rising mountain range. The Year Without Summer, now an old chasm; actually it had lasted three years, but people would not disturb such a name for a mere fact. Three Unusually Cold Years— no. It didn’t have what people wanted, some kind of compression of the truth, to create a strong trace in the memory, perhaps. Symbolic thinking; people needed things thrown together. Sax knew this because he spent a lot of time in Sabishii visiting Michel and Maya. People loved drama. Maya more than most, perhaps, but it served to show. Limit-case demonstration of the norm. He worried about her effect on Michel. Michel seemed not to be enjoying life. Nostalgia, from the Greek nostos, “a return home,” and algos, “pain.” Pain of the return home. A very accurate description; despite their blurs, words could sometimes be so exact. It was a paradox until you looked into how the brain worked, then it became less surprising. A model of the mind’s interaction with physical reality, blurred at the edges. Even science had to admit it. Not that this meant giving up trying to explain things!

“Come out and do some field studies with me,” he would urge Michel.

“Soon.”

“Concentrate on the moment,” Sax suggested. “Each moment is its own reality. It has its particular thisness. You can’t predict, but you can explain. Or try. If you are observant, and lucky, you can say, this is why this is happening! It’s very interesting!”

“Sax. When did you become such a poet?”

Sax did not know how to answer that. Michel was still stuffed with his immense nostalgia. Finally Sax said, “Make time to come out into the field.”

• • •

In the mild winters when the winds were gentle, Sax took sailing trips around the south end of Chryse Gulf. The golden gulf. The rest of the year he stayed on the peninsula, and went out from Da Vinci Crater on foot, or in a little car for overnighters. Mostly he did meteorology, though of course he looked at everything. On the water he would sit and feel the wind in the sail as he wandered into one little convolution of the coast after another. On the land he would drive in the mornings, looking at the view until he saw a good spot. Then he would stop the car and go outside.

Pants, shirt, windbreaker, hiking boots, his old hat; all he needed on this day of m-year 65. A fact that never ceased to amaze him. Usually it was in the 280s— bracing, but he liked it. Global averages were bouncing around the mid-270s. A good average, he felt— above freezing— sending a thermal pulse down into the permafrost. On its own this pulse would melt the permafrost in about ten thousand years. But of course it was not on its own.

He wandered over tundra moss and samphire, kedge and grass. Life on Mars. An odd business. Life anywhere, really. Not at all obvious why it should appear. This was something Sax had been thinking about recently. Why was there increasing order in any part of the cosmos, when one might expect nothing but entropy everywhere? This puzzled him greatly. He had been intrigued when Spencer had offered an offhand explanation, over beer one night on the Odessa corniche— in an expanding universe, Spencer had said, order was not really order, but merely the difference between the actual entropy exhibited and the maximum entropy possible. This difference was what humans perceived as order. Sax had been surprised to hear such an interesting cosmological notion from Spencer, but Spencer was a surprising man. Although he drank too much alcohol.

Lying on the grass looking at tundra flowers, one couldn’t help thinking about life. In the sunlight the little flowers stood on their stems glowing with their anthracyins, dense with color. Ideograms of order. They did not look like a mere difference in entropic levels. Such a fine texture to a flower petal; drenched in light, it was almost as if it were visible molecule by molecule: there a white molecule, there lavender, there clematis blue. These pointillist dots were not molecules, of course, which were well below visible resolution. And even if molecules had been visible, the ultimate building blocks of the petal were so much smaller than that that they were hard to imagine— finer than one’s conceptual resolution, one might say. Although recently the theory group at Da Vinci had begun buzzing about developments in superstring theory and quantum gravity they were making; it had even gotten to the point of testable predictions, which historically had been string theory’s great weakness. Intrigued by this reconnection with experiment, Sax had recently started trying to understand what they were doing. It meant foregoing sea cliffs for seminar rooms, but in the rainy seasons he had done it, sitting in on the group’s afternoon meetings, listening to the presentations and the discussions afterward, studying the scrawled math on the screens and spending his mornings working on Riemann surfaces, Lie algebras, Euler numbers, the topologies of compact six-dimensional spaces, differential geometries, Grassmannian variables, Vlad’s emergence operators, and all the rest of the mathematics necessary to follow what the current generation was talking about.

Some of this math concerning superstrings he had looked into before. The theory had existed for almost two centuries now, but it had been proposed speculatively long before there was either the math or the experimental ability to properly investigate it. The theory described the smallest particles of spacetime not as geometrical points but as ultramicroscopic loops, vibrating in ten dimensions, six of which were compactified around the loops, making them somewhat exotic mathematical objects. The space they vibrated in had been quantized by twenty-first-century theorists, into loop patterns called spin networks, in which lines of force in the finest grain of the gravitational field acted somewhat like the lines of magnetic force around a magnet, allowing the strings to vibrate only in certain harmonics. These supersymmetrical strings, vibrating harmonically in ten-dimensional spin networks, accounted very elegantly and plausibly for the various forces and particles as perceived at the subatomic level, all the bosons and fermions, and their gravitational effects as well. The fully elaborated theory therefore claimed to mesh successfully quantum mechanics with gravity, which had been the problem in physical theory for over two centuries.

All very well; indeed, exciting. But the problem, for Sax and many other skeptics, came with the difficulty of confirming any of this beautiful math by experiment, a difficulty caused by the very, very, very small sizes of the loops and spaces being theorized. These were all in the 10-33 centimeter range, the so-called Planck length, and this length was so much smaller than subatomic particles that it was hard to imagine. A typical atomic nucleus was about 10-13 centimeter in diameter, or one millionth of a billionth of a centimeter. First Sax had tried very hard to contemplate that distance for a while; hopeless, but one had to try, one had to hold that hopelessly inconceivable smallness in the mind for a moment. And then remember that in string theory they were talking about a distance twenty magnitudes smaller still— about objects one thousandth of one billionth of one billionth the size of an atomic nucleus! Sax struggled for ratio; a string, then, was to the size of an atom, as an atom was to the size of . . . the solar system. A ratio which rationality itself could scarcely comprehend.

Worse yet, it was too small to detect experimentally. This to Sax was the crux of the problem. Physicists had been managing experiments in accelerators at energy levels on the order of one hundred GeV, or one hundred times the mass energy of a proton. From these experiments they had worked up, with great effort, over many years, the so-called revised standard model of particle physics. The revised standard model explained a lot, it was really an amazing achievement, and it made predictions that could be proved or disproved by lab experiment or cosmological observations, predictions that were so varied and had been so well fulfilled that physicists could speak with confidence about much of what had gone on in the history of the universe since the Big Bang, going as far back as the first millionth of a second of time.

String theorists, however, wanted to make a fantastic leap beyond the revised standard model, to the Planck distance which was the smallest realm possible, the minimum quantum movement, which could not be decreased without contradicting the Pauli exclusion principle. It made sense, in a way, to think about that minimum size of things; but actually seeing events at this scale would take experimental energy levels of at least 1019 GeV, and they could not create those. No accelerator would ever come close. The heart of a supernova would be more like it. No. A great divide, like a vast chasm or desert, separated them from the Planck realm. It was a level of reality fated to remain unknown to them in any physical sense.

Or so skeptics maintained. But those interested in the theory had never been dissuaded from studying it. They searched for indirect confirmation of the theory at the subatomic level, which from this perspective now seemed gigantic, and from cosmology. Anomalies in phenomena that the revised standard could not explain, might be explained by predictions made by string theory about the Planck realm. These predictions had been few, however, and the predicted phenomena very difficult to see. No real clinchers had been found. But as the decades passed, a few string enthusiasts had always continued to explore new mathematical structures, which might reveal more ramifications of the theory, might predict more detectable indirect results. This was all they could do; and it was a very chancy road for physics to take, Sax felt. He believed in the experimental testing of theories with all his heart. If it couldn’t be tested, it remained math only, and its beauty was irrelevant; there were lots of bizarrely beautiful exotic fields of mathematics, but if they weren’t modeling the phenomenal world, Sax wasn’t interested.

Now, however, after all the decades of work, they were beginning to make progress in ways that Sax found interesting. At the new supercollider in Rutherford Crater’s rim, they had found the second Z particle that string theory had long predicted would be there. And a magnetic monopole detector, orbiting the sun out of the plane of the ecliptic, had captured a trace of what looked to be a fractionally charged unconfined particle with a mass as big as a bacterium— a very rare glimpse of a “weakly interacting massive particle,” or WIMP. String theory had predicted WIMPs would be out there, while the revised standard did not call for them. That was thought provoking, because the shapes of galaxies showed that they had gravitational masses ten times as large as their visible light revealed; if the dark matter could be explained satisfactorily as weakly interacting massive particles, Sax thought, then the theory responsible would have to be called very interesting indeed.

Interesting in a different way was the fact that one of the leading theorists in this new stage of development was working right there in Da Vinci, part of the impressive group Sax was sitting in on. Her name was Bao Shuyo. She had been born and raised in Dorsa Brevia, her ancestry Japanese and Polynesian. She was small for one of the young natives, though still half a meter taller than Sax. Black hair, dark skin, Pacific features, very regular and somewhat plain. She was shy with Sax, shy with everyone; she even sometimes stuttered, which Sax found extremely endearing. But when she stood up in the seminar room to give a presentation, she became quite firm in hand if not in voice, writing her equations and notes on the screen very quickly, as if doing speed calligraphy. Everyone in these moments attended to her very closely, in effect mesmerized; she had been working at Da Vinci for a year now, and everyone there smart enough to recognize such a thing knew that they were watching one of the pantheon at work, discovering reality right there before their eyes.

The other young turks would interrupt her to ask questions, of course— there were many good minds in that group— and if they were lucky, off they would all go together, mathematically modeling gravitons and gravitinos, dark matter and shadow matter— all personality and indeed all persons forgotten. Very productive exciting sessions; and clearly Bao was the driving force in them, the one they relied on, the one they had to reckon with.

It was disconcerting, a bit. Sax had met women in math and physics departments before, but this was the only female mathematical genius he had ever even heard of, in all the long history of mathematical advancement, which, now that he thought of it, had been a weirdly male affair. Was there anything in life as male as mathematics had been? And why was that?

Disconcerting in a different way was the fact that areas of Bao’s work were based on the unpublished papers of a Thai mathematician of the previous century, an unstable young man named Samui, who had lived in Bangkok brothels and committed suicide at the age of twenty-three, leaving behind several “last problems” in the manner of Fermat, and insisting to the end that all of his math had been dictated to him by telepathic aliens. Bao had ignored all that and explained some of Samui’s more obscure innovations, and then used them to develop a group of expressions called advanced Rovelli-Smolin operators, which allowed her to establish a system of spin networks that meshed with superstrings very beautifully. In effect this was the complete uniting of quantum mechanics and gravity at last, the great problem solved— if it were true. And true or not, it had been powerful enough to allow Bao to make several specific predictions in the larger realms of the atom and the cosmos; and some of these had since been confirmed.

So now she was the queen of physics— the first queen of physics— and experimentalists in labs all over were on-line to Da Vinci, anxious to have more suggestions from her. The afternoon sessions in the seminar room were invested with a palpable sense of tension and excitement; Max Schnell would start the meeting, and at some point call on Bao; and she would stand and go to the screen at the front of the room, plain, graceful, demure, firm, pen flying over the screen as she gave them a way to calculate precisely the neutrino mass, or described very specifically the ways strings vibrated to form the different quarks, or quantized space so that gravitinos were divided into three families, and so on; and her colleagues and friends, perhaps twenty men and one other woman, would interrupt to ask questions, or add equations that explained side issues, or tell the rest of them about the latest results from Geneva or Palo Alto or Rutherford; and during that hour, they all knew they were at the center of the world.

And in labs on Earth and Mars and in the asteroid belt, following her work, unusual gravity waves were noted; in very difficult delicate experiments; particular geometric patterns were revealed in the fine fluctuations in the cosmic background radiation; dark-matter WIMPs and shadow-matter WISPs were being sought out; the various families of leptons and fermions and leptoquarks were explained; galactic clumping in the first inflation was provisionally solved; and so on. It seemed as if physics might be on the brink of the Final Theory at last. Or at least in the midst of the Next Big Step.

• • •

Given the significance of what Bao was doing, Sax felt shy about speaking to her. He did not want to waste her time on trivial things. But one afternoon at a kava party, out on one of the arc balconies overlooking Da Vinci’s crater lake, she approached him— even more shy and stumbling than he was— so much so that he was forced into the very unusual position of trying to put someone else at ease, finishing sentences for her and the like. He did that as best he could, and they stumbled along, talking about his old Russell diagrams for gravitinos, useless now he would have thought, though she said they still helped her to see gravitational action. And then when he asked a question about that day’s seminar, she was much more relaxed. Yes, clearly that was the way to put her at ease; he should have thought of it immediately. It was what he liked himself.

After that, they got in the habit of talking from time to time. He always had to work to draw her out, but it was interesting work. And when the dry season came, in the fall helionequinox, and he started going out sailing again from the little harbor Alpha, he asked her haltingly if she would like to join him, and they stuttered their way through a deeply awkward interaction, which resulted in her going out with him the next nice day, sailing in one of the lab’s many little catamarans.

When day sailing, Sax stayed in the little bay called the Florentine, southeast of the peninsula, where Ravi Fjord widened but before it became Hydroates Bay. This was where Sax had learned to sail, and where he still felt best acquainted with the winds and currents. On longer trips he had explored the delta of fjords and bays at the bottom end of the Marineris system, and three or four times he had sailed up the eastern side of the Chryse Gulf, all the way to Mawrth Fjord and along the Sinai Peninsula.

On this special day, however, he confined himself to the Florentine. The wind was from the south, and Sax tacked down into it, enlisting Bao’s help at every change of tack. Neither of them said much. Finally, to get things started, Sax was forced to ask about physics. They talked about the ways in which strings constituted the very fabric of space-time itself, rather than being replacements for points in some absolute abstract grid.

Thinking it over, Sax said, “Do you ever worry that work on a realm so far beyond the reach of experiment will turn out to be a kind of house of cards— knocked over by some simple discrepancy in the math, or some later different theory that does the job better, or is more confirmable?”

“No,” Bao said. “Something so beautiful as this has to be true.”

“Hmm,” Sax said, glancing at her. “I must admit I’d rather have something solid crop up. Something like Einstein’s Mercury— a known discrepancy in the previous theory, which the new theory resolves.”

“Some people would say that the missing shadow matter fills that bill.”

“Possibly.”

She laughed. “You need more, I can see. Perhaps some kind of thing we can do.”

“Not necessarily,” Sax said. “Although it would be nice, of course. Convincing, I mean. If something were better understood, so that we could manipulate it better. Like the plasmas in fusion reactors.” This was an ongoing problem in another lab at Da Vinci.

“Plasmas might very well be better understood if you modeled them as having patterns imposed by spin networks.”

“Really?”

“I think so.”

She closed her eyes— as if she could see it all written down, on the inside of her eyelids. Everything in the world. Sax felt a piercing stab of envy, of— loss. He had always wanted that kind of insight; and there it was, right in the boat beside him. Genius was a strange thing to witness.

“Do you think this theory will mean the end of physics?” he asked.

“Oh no. Although we might work out the fundamentals. You know, the basic laws. That might be possible, sure. But then every level of emergence above that creates its own problems. Taneev’s work only scratches the surface there. It’s like chess— we might learn all the rules, but still not be able to play very well because of emergent properties. Like, you know, pieces are stronger if they’re out in the center of the board. That’s not in the rules, it’s a result of all the rules put together.”

“Like weather.”

“Yes. We already understand atoms better than weather. The interactions of the elements are too complex to follow.”

“There’s holonomy. Study of whole systems.”

“But it’s just a bunch of speculation at this point. The start of a science, if it turns out to work.”

“And so plasmas, though?”

“Those are very homogeneous. There’s only a very few factors involved, so it might be amenable to spin-network analysis.”

“You should talk to the fusion group about that.”

“Yes?” She looked surprised.

“Yes.”

Then a hard gust hit, and they spent a few minutes watching the boat respond, the mast sucking in sails with a bit of humming until they were reset, and running across the strengthening breeze, into the sun. Light flaked off the fine black hair gathered at the back of Bao’s neck; beyond that, the sea cliffs of Da Vinci. Networks, trembling at the touch of the sun— no. He could not see it, with eyes open or closed.

Cautiously he said, “Do you ever wonder about being, you know. Being one of the first great women mathematicians?”

She looked startled, then turned her head away. She had thought about it, he saw. “The atoms in a plasma move in patterns that are big fractals of the spin-network patterns,” she said.

Sax nodded, asked more questions about that. It seemed possible to him that she would be able to help Da Vinci’s fusion group with the problems they were having engineering a lightweight fusion apparatus. “Have you ever done any engineering? Or physics?”

Affronted: “I am a physicist.”

“Well, a mathematical physicist. I was thinking of the engineering side.”

“Physics is physics.”

“True.”

Only once more did he push, and this time indirectly. “When did you first learn math?”

“My mom gave me quadratic equations at four, and all kinds of math games. She was a statistician, very keen about it all.”

“And the Dorsa Brevia schools. . . .”

She shrugged. “They were fair. Math was mostly something I did by reading, and correspondence with the department in Sabishii.”

“I see.”

And they went back to talking about the new results from CERN; about weather; about the sailboat’s ability to point to within a few degrees of the wind. And then the following week she went out with him again, on one of his walks on the peninsula’s sea cliffs. It was a great pleasure to show her a bit of the tundra. And over time, taking him through it step-by-step, she managed to convince him that they were perhaps coming close to understanding what was happening at the Planck level. A truly amazing thing, he thought, to intuit this level, and then make the speculations and deductions necessary to flesh it out and understand it, creating a very complex powerful physics, for a realm that was so very small, so very far beyond the senses. Awe-inspiring, really. The fabric of reality. Although both of them agreed that just as with all earlier theories, many fundamental questions were left unanswered. It was inevitable. So that they could lie side by side in the grass in the sun, staring as deeply into the petals of a tundra flower as ever one could, and no matter what was happening at the Planck level, in the here and now the petals glowed blue in the light with a quite mysterious power to catch the eye.

• • •

Actually, lying on the grass made it clear how much the permafrost was melting. And the melt lay on a hardpan of still-frozen ground, so that the surface became saturated and boggy. When Sax stood up, his ventral side chilled instantly in the breeze. He spread his arms to the sunlight. Photon rain, vibrating across the spin networks. In many regions heat exhaust from nuclear power plants was being directed down into capillary galleries in the permafrost, he told Bao as they walked back to the rover. This was causing trouble in some wet areas, which were tending to saturate at the surface. The land melting, so to speak. Instant wetlands. A very active biome, in fact. Though the Reds objected. But most of the land that would have been affected by permafrost melt was now under the North Sea anyway. What little remained above the sea was to be treasured as swamps and marshes.

The rest of the hydrosphere was almost equally transformative of the surface. It couldn’t be helped; water was a very effective carver of rock, hard though it was to believe when watching a gossamer waterfall drift down a sea cliff, turning to white mist long before it hit the ocean. Then again there was the sight of the massive giant howler waves, battering the cliffs so hard that the ground shook underfoot. A few million years of that and those cliffs would be significantly eroded.

“Have you seen the riverine canyons?” she asked.

“Yes, I saw Nirgal Vallis. Remarkable how satisfying it was to see water down at its bottom. So apt.”

“I didn’t know there was so much tundra out here.”

Tundra was the dominant ecology for much of the southern highlands, he told her. Tundra and desert. In the tundra, fines were fixed very effectively to the ground; no wind could lift mud, or quicksand, of which there was a good quantity, making it dangerous to travel in certain regions. But in the deserts the powerful winds ripped great quantities of dust into the sky, cooling temperatures while they darkened the day, and causing problems where they landed, as they had for Nirgal. Suddenly curious, he said, “Have you ever met Nirgal?”

“No.”

The sandstorms these days were nothing like the long-forgotten Great Storm of course, but still a factor that had to be considered. Desert pavement formed by microbacteria was one very promising solution, though it tended to fix only the top centimeter of deposits, and if the wind tore the edge of the pavement, what was underneath was then free to be borne away. Not an easy problem. Dust storms would be with them for centuries.

Still, an active hydrosphere. Meaning life everywhere.

• • •

Bao’s mother died in a small plane crash, and Bao as the youngest daughter had to go home and take care of things, including possession of the family home. Ultimogeniture in action, modeled on the Hopi matriarchy, he was told. Bao wasn’t sure when she would be back; there was even a chance she wouldn’t be. She was matter-of-fact about it, it was just something that had to be done. Withdrawn already into an internal world. Sax could only wave good-bye to her and walk back to his room, shaking his head. They would understand the fundamental laws of the universe before they had even the slightest handle on society. A particularly obdurate subject of study. He called Michel on screen and expressed something like this, and Michel said, “It’s because culture keeps progressing.”

Sax thought he could see what Michel meant— there were rapid changes in attitudes to many things. Werteswandel, as Bela called it, mutation of values. But they still lived in a society struggling with archaisms of all sorts. Primates banding into tribes, guarding a territory, praying to a god like a cartoon parent. . . . “Sometimes I don’t think there’s been any progress at all,” he said, feeling strangely disconsolate.

“But Sax,” Michel protested, “right here on Mars we have seen both patriarchy and property brought to an end. It’s one of the greatest achievements in human history.”

“If true.”

“Don’t you think women have as much power as men now?”

“As far as I can tell.”

“Perhaps even more, when it comes to reproduction.”

“That would make sense.”

“And the land is in the shared stewardship of everyone. We still own personal items as property, but land as property has never happened here. That’s a new social reality, we struggle with it every day.”

So they did. And Sax remembered how bitter the conflicts had been in the old days, when property and capital had been the order of the day. Yes, perhaps it was true: patriarchy and property were in the process of being dismantled. At least on Mars, at least for now. As with string theory, it might take a long time to work it into any proper state. After all Sax himself, who had no prejudices whatsoever, had been amazed to see a woman mathematician at work. Or, to be more precise, a woman genius. By whom he had been promptly hypnotized, so to speak, along with every other man in the theory group— to the point of being rendered quite distraught by her departure. Uneasily he said, “On Earth people seem to be fighting just as much as before.”

Even Michel had to admit it. “Population pressures,” he said, trying to wave them away. “There are too many people down there, and more all the time. You saw what it was like during our visit. As long as Earth is in that situation, Mars is under threat. And so we fight up here too.”

Sax took the point. In a way it was comforting; human behavior not as irreducibly evil or stupid, but as responding, semirationally, to a given historical situation, a danger. Seizing what one could, with the notion that there might not be enough for all; doing everything possible to protect one’s offspring; which of course endangered all offspring, by the aggregate of individual selfish actions. But at least it could be called an attempt at reason, a first approximation.

“It’s not as bad as it was, anyway,” Michel was saying. “Even on Earth people are having far fewer children. And they’re reorganizing into collectives pretty well, considering the flood and all the trouble that preceded it. A lot of new social movements down there, a lot of them inspired by what we’re doing here. And by what Nirgal does. They’re still watching him and listening to him, even when he doesn’t speak. What he said during our visit there is still having a big effect.”

“I believe it.”

“Well, there you are! It’s getting better, you have to admit it. And when the longevity treatments stop working, there will come a balance of births and deaths.”

“We’ll hit that time soon,” Sax predicted glumly.

“Why do you say so?”

“Signs of it cropping up. People dying from one thing or other. Senescence is not a simple matter. Staying alive when senescence should have kicked in— it’s a wonder we’ve done as much as we have. There’s probably a purpose in senescence. Avoiding overpopulation, perhaps. Making room for new genetic material.”

“That bodes poorly for us.”

“We’re already over two hundred percent the old average lifetime.”

“Granted, but even so. One doesn’t want it to end just because of that.”

“No. But we have to focus on the moment. Speaking of which, why don’t you come out into the field with me? I’ll be as upbeat as you want out there. It’s very interesting.”

“I’ll try to free up some time. I’ve got a lot of clients.”

“You’ve got a lot of free time. You’ll see.”

• • •

In this particular moment, the sun was high. Rounded white clouds were piling up in the air overhead, forming great masses that would never come again, though at the moment they were as solid as marble, and darkening at their bottoms. Cumulonimbus. He was standing on Da Vinci Peninsula’s western cliff again, looking across Shalbatana Fjord to the cliff edging the east side of Lunae Planum. Behind him rose the flat-topped hill that was the rim of Da Vinci Crater. Home base. He had lived there a long time now. These days their co-op was making many of the satellites being put up into orbit, and the boosters as well, in collaboration with Spencer’s lab in Odessa, and a great number of other places. A Mondragon-style cooperative, operating the ring of labs and homes in the rim, and the fields and lake filling the crater floor. Some of them chafed at restrictions imposed by the courts on projects they had in mind, involving new power plants that would put out too much heat. In the last few years the GEC had been issuing K rations, as they were called, giving communities the right to add some fraction of a degree Kelvin to the global warming. Some Red communities were doing their best to get assigned K rations and then not use them. This action, along with ongoing incidences of ecotage, kept the global temperature from rising very fast no matter what other communities did. Or so the other communities argued. But the ecocourts were still parsimonious with the K rations. Cases were judged by a provincial ecocourt, then the judgment was approved by the GEC, and that was it: no appeals, unless you could get a petition signed by fifty other communities, and even then the appeal was only dropped into the morass of the global legislature, where its fate was up to the undisciplined crowd in the duma.

Slow progress. Just as well. With the global average temperatures above freezing, Sax was content. Without the constraint of the GEC, things could easily get too warm. No, he was in no further hurry. He had become an advocate of stabilization.

Now, out in the sun of a perihelion day, it was an invigorating 281 K, and he was walking along the sea-cliff edge of Da Vinci, looking at alpine flowers in the cracks of the rubble, then past them to the distant quantum sheen of the fjord’s sunny surface, when down the cliff edge walking his way came a tall woman, wearing a face mask and jumper, and big hiking boots: Ann. He recognized her instantly— that stride, no doubt about it— Ann Clayborne, in the flesh.

• • •

This surprise brought a double jolt to his memory— of Hiroko, emerging out of the snow to lead him to his rover— then of Ann, in Antarctica, striding over rock to meet him— but for what?

Confused, he tried to track the thought. Double image— a fleet single image—

Then Ann was before him and the memories were gone, forgotten like a dream.

• • •

He had not seen her since forcing the gerontological treatment on her in Tempe, and he was acutely uncomfortable; possibly this was a fright reaction. Of course it was unlikely she would physically assault him. Though she had before. But that was never the kind of assault that worried him. That time in Antarctica— he grasped for the elusive memory, lost it again. Memories on the edge of consciousness were certain to be lost if one made any deliberate effort to retrieve them. Why that should be was a mystery. He didn’t know what to say.

“Are you immune to carbon dioxide now?” she asked through her face mask.

He explained about the new hemoglobin treatment, struggling for each word, in the way he had after his stroke. Halfway through his explanation, she laughed out loud. “Crocodile blood now, eh?”

“Yes,” he said, guessing her thought. “Crocodile blood, rat mind.”

“A hundred rats.”

“Yes. Special rats,” he said, striving for accuracy. Myths after all had their own rigorous logic, as Lévi-Strauss had shown. They had been genius rats, he wanted to say, a hundred of them and geniuses every one. Even his miserable graduate students had had to admit that.

“Minds altered,” she said, following his drift.

“Yes.”

“So, after your brain damage, altered twice,” she noted.

“That’s right.” Depressing when you thought of it that way. Those rats were far from home. “Plasticity enhancement. Did you . . . ?”

“No. I did not.”

So it was still the same old Ann. He had been hoping she would try the drugs on her own recognizance. See the light. But no. Although in fact the woman before him did not look like the same Ann, not exactly. The look in her eye; he had gotten used to a look from her that seemed a certain signal of hatred. Ever since their arguments on the Ares, and perhaps before. He had had time to get used to it. Or at least to learn it.

Now, with a face mask on, and a different expression around her eyes, it was almost like a different face. She was watching him closely, but the skin around the eyes was no longer so knotted. Wrinkled, she and he were both maximally wrinkled, but the pattern of wrinkles was that of a relaxed musculature. It seemed possible the mask even hid a small smile. He didn’t know what to make of it.

“You gave me the gerontological treatment,” she said.

“Yes.”

Should he say he was sorry if he wasn’t? Tongue-tied, lockjawed, he stared at her like a bird transfixed by a snake, hoping for some sign that it was all right, that he had done the right thing.

She gestured suddenly at their surroundings. “What are you trying to do now?”

He struggled to understand her meaning, which seemed to him as gnomic as a koan. “I’m out looking,” he said. He couldn’t think what to say. Language, all those beautiful precious words, had suddenly scattered away, like a flock of startled birds. All out of reach. That kind of meaning gone. Just two animals, standing there in the sun. Look, look, look!

She was no longer smiling, if she had been. Neither was she looking daggers at him. A more evaluative look, as if he were a rock. A rock; with Ann that surely indicated progress.

But then she turned and walked away, down the sea cliff toward the little seaport at Zed.