PROBABILITY MOON

by Nancy Kress

  She taught a class at the Academy.

  She took more futile rehab.

  She tried to get interested in gardening.

  She was aware, every endless limping day, that half her life span remained.

  When the call came about the Zeus mission to World, she had realized at once that high command wanted her not only for her knowledge of space tunnels but also for her retired status. The Fallers, it was rumored, might have human informants, drawn from those countries on and off Earth that were displeased with the Solar Alliance and its leader, Mars. Colonel Syree Johnson, retired, would arouse no interest if she took a berth on a minor scientific expedition. And she knew as much as anyone still living about how Space Tunnel #1 had been first approached, decoded, used. She was prepared to do the same for Orbital Object #7.

  It grew larger on the shuttle display as Austen maneuvered his craft. Silent, cold, enticing.

  “Match orbit as close as possible,” she said.

  “Matching orbit.”

  While Austen fine-tuned his position fifty meters behind the artifact, Syree put on her helmet, ran a last check on her suit and tether rings, picked up her bag of instruments.

  “Leaving ship, Captain.”

  “Good luck, Colonel.” He gave her his fine irreverent grin and tossed off a flamboyant salute.

  Outside, Syree’s jets carried her to Orbital Object #7. Then she floated next to it, touching it. At its equator, the surface was deeply indented in regular flowing patterns that made convenient handholds. She hitched herself to a groove and orbited with the artificial moon.

  “Contact.”

  “Acknowledged.”

  Slowly Syree ran the fingers of her right glove over the metallic surface. Yes, it resembled the feel of the sparse markings on space tunnels. Computer analysis would confirm that the language was the same, and the Solar Alliance had a Rosetta stone for that.

  She opened her instrument bag. A sudden absurd image came to her: an old-time country doctor, making a house call. This was no time for absurdities; perhaps she would increase her dosage of Contex, which increased mental concentration. For now, she banished the silly image by sheer will.

  “Beginning detailed data scan. Testing reception.”

  “Receiving data,” Austen said. “Colonel, the first-contact ceremony on World is beginning. You asked to be informed.”

  “Thank you. Record the ceremony, as per orders.”

  “Acknowledged.”

  She would watch the recording cube later. She would have to: Officially, contact with the natives was the only reason the Zeus was here. All ship personnel were required to remain current on World data, in case rescue intervention became necessary.

  Which it wouldn’t. Syree had read the recon reports. The natives had barely reached preindustrial; they even made bicycles manually, one by one. And they were unusually peaceful, with no known history of war. Otherwise the “social scientists”—there was an oxymoron—wouldn’t bring human kids down there. The contact ceremony would consist of bowing and passing around flowers, and the xeno-team’s eventual results would consist of one more report stuck in some academic library somewhere. None of it mattered, next to what orbited under Syree Johnson’s fingers. She didn’t yet know what it was, but she knew it could change radically the human/ Faller balance of power.

  As she worked her way completely around the sphere, twelve and a half clicks, a stream of data flowed silently through her instruments to the shuttle and from there to the computers on board the Zeus. It would take days to analyze all of it, but not the flowing script. The Zeus would have that in a few minutes.

  She had barely completed circumnavigation when Austen said, “Incoming data.”

  “Relay.”

  Her first assistant, Major John Ombatu. “Markings on Orbital Object #7 decoded, Colonel. Ready to receive?”

  “Ready to receive.”

  “translation, using the Webbel-Grey translation model: ‘unknown-word unknown-word small holding-together disruption device unknown-word stop strengths one, two, three, five, seven, eleven, thirteen, seventeen, nineteen.’ End.”

  Syree said, “That’s it, John? Three unknown words out of seven, plus a strength-calibration listing by primes?”

  “Those old aliens were fond of primes, especially eleven. As you know.”

  Of course she knew. Space tunnels were all labeled in primes—to the extent anything was labeled at all. Without extensive markings on the floating panels, Webbel and Grey had actually had very little to go on in constructing their translation model. Syree guessed that “holding-together” came from one of the few repeated markings they did have, a warning that any mass above a certain limit would not go through a tunnel.

  This had turned out to be true. The Anaconda, A Thor-class cruiser, had been lost, along with nine hundred lives. The cruiser had fit, tightly, inside Space Tunnel #1, but not inside the unknown field that the tunnel was presumed to enclose. The Anaconda had disappeared in a massive implosion, without debris or residual radiation. Intense experimentation determined that the same thing would happen to any object which massed more than roughly one hundred thousand tons. The Anaconda, Martian physicists decided, had had a Schwarzschild radius—defined as the radius below which, if you squeezed the mass, it would become a black hole—larger than the tunnel’s capacity to handle. From the disaster, xen-olinguists had learned the meaning of the alien marking for “disruption.”

  Now Syree pushed away her disappointment. She’d hoped the translation would confirm that Orbital Object #7 was a weapon. That possibility had not been ruled out. But it would take a lot more data analysis before she could form a hypothesis to test.

  Three ship-days later, she was no closer to understanding the object.

  Her team had performed every noninvasive test Syree could think of, from the obvious spectral, sonic, and magnetic analyses to less reliable statistical simulations. The facts were clear; there just weren’t enough of them.

  The artifact emitted no radiation of any kind, had no magnetic field, and no thermal gradations. The hull, 0.9765 centimeters thick, was made mostly of an allotropic form of carbon that resembled a known class of fullerenes but was subtly different. The artifact contained no heavy metals, nothing with an atomic number above seventy-five. It massed slightly less than a million tons. Inside was mostly hollow, although unidentifiable structures were suspended inside (how?) in an extremely complex but partial manner, without direct connection to each other. These unknown but stable structures appeared to be without any mass—an impossibility. When the computer ran mathematical analyses, the suspensions suggested a complicated web wherein each curve folded back on itself many times, a sort of multidimensional fractal. Computer breakdown further suggested a strange attractor, a region in which all sufficiently close trajectories were attracted in the limit, but in which arbitrarily close points over time became exponentially separated. Syree figured the Hausdorff dimension of the suggested fractal. It was 1.2, the same dimension as the galactic filling of the universe.

  None of it added up to anything. None of it indicated what Orbital Object #7 might be for.

  The only way to determine that was to activate it.

  “What if it blows up the entire star system?” John Ombatu asked.

  “It wouldn’t have different strength settings if it was designed for a one-time, scorched-earth solution.”

  “Okay, what if it just blows up World?”

  “Still a lot of different settings for that extreme a measure to happen at the lowest one.”

  Commander Peres said skeptically, “Are you sure you even know how to activate it?”

  “Of course I’m not sure,” Syree said. “But it seems to have double-button pressure points. A user must activate both buttons simultaneously, so they can’t be set off accidentally by, say, a meteor hit.”

  The team fell silent. Syree could feel her own breath, loud in her chest. She waited.

  “I think it’s too
great a risk,” Ombatu said finally, and she knew something about him she had not known before.

  “Do it,” said Lieutenant Lucy Wu, the junior officer. “The Fallers took out that colony on New Rome just last week, remember. Six thousand dead. We haven’t got that many off-system colonies left. If we don’t risk anything here, where we don’t even have a colony, we risk everything everywhere else.”

  Syree’s thinking exactly. But she waited to hear from Daniel Austen and Canton Lee. She needed to know what her team was made of. Although the final decision rested with Peres. Syree was project head, but he commanded the Zeus; any decision potentially endangering the ship was his.

  “Yes,” Lee said.

  “Yes,” Austen said. “We’re at war.”

  “All right,” Peres said. “At the artifact’s lowest setting.”

  Syree said, “I’ll go out at oh-seven-hundred. Commander Peres, the Zeus should move to the other side of the planet, as shielded as she can be. Austen, you pilot the shuttle.”

  Her tone allowed for no further discussion. She didn’t look at John Ombatu.

  The most disciplined—or Disciplined—mind may wander under stress. Syree, experienced in combat, already knew this. So she was not surprised when she left the shuttle airlock and found herself thinking again of Grandmother Emily.

  Emily James Johnson had seen action in Africa, in South America, and, shamefully, in the Resistance Rebellion when the United States joined the United Atlantic Federation. She married late and when Syree remembered her grandmother, she remembered her old. Frail, stooped, liver-spotted—she had stopped the cosmetic genemod treatments at eighty-five. But still stern. When Syree, about four, had a temper tantrum, Grandmother Emily had swatted her across the shoulders with her oak cane. “A Johnson masters herself! Remember that, Syree!”

  Syree’s mother had cried over the welts and given Syree a cookie. Syree looked at her mother with contempt. Even at four, she had known that Grandmother Johnson had been right to hit her, and that her mother was a soft weakling.

  Floating toward Orbital Object #7, Syree regretted that contemptuous look of forty-odd years ago. Her mother had not deserved it. She was not a soldier, and Syree’s father had married her for her soft sweetness. Syree could still see her, holding out the rejected cookie in one slim white-fingered hand, her first intolerance from a daughter to whom tolerance would be the hardest discipline, always.

  Syree put her family out of her mind.

  Orbital Object #7 was once again under her hand. She fastened the remote pressure device on the raised circle under the flowing script for “one.” Quickly she swung along the handholds (tentacle holds? machine grips?). The flowing script on the opposite side of the artifact included identical raised circles. Over two thousand clicks below her, World turned under equatorial clouds. How did that sky look to the natives, who saw farther into the infrared than Syree but less far into the short-scattered blues?

  However they see, let them go on doing it after I’m done. She fastened down the second pressure device.

  “Remotes set,” she said.

  “Remotes set,” Austen repeated in the shuttle. “Coming to pick you up.”

  “Don’t,” Syree said. “I’m staying out.”

  There was a long pause. “Colonel, that’s not per plan.”

  “I’m staying out,” she repeated. She didn’t offer her explanation: that if the entire planet of civilians was at risk from whatever Orbital Object #7 delivered at force one, then so should she be. Either Austen understood or no amount of explanation would make him understand.

  “Permission to remain,” Austen said.

  “Permission granted.” Now she knew something else about Daniel Austen. Something worth knowing. “Back up a few hundred meters, Captain. Let’s get two more perspectives.”

  “Affirmative.”

  There were, of course, instrument satellites covering the artifact activation from several different positions. The more, the better. Syree watched the shuttle maneuver into position. Austen said cheerfully, “Recording equipment activated. Ready when you are, Colonel.”

  “Stand by.”

  “Let the games begin!” Austen said, and she heard the jaunty laughter in his voice.

  Syree jetted back from Orbital Object #7. At twenty meters, she activated both remote pressure devices.

  For a long moment, nothing happened. The artifact didn’t change at all. Then the shuttle began to glow. An eerie, deadly glow that brightened as she watched.

  “Austen. What do the displays show?”

  Silence.

  “Austen. Come in, Captain Austen.”

  Silence.

  “Daniel! Come in!”

  Silence. The shuttle still glowed. Syree jetted toward it. After a hundred meters, her suit spoke urgently in prerecorded warning: “Radiation ahead. Do not advance. Three thousand rads. Twenty-eight hundred rads. Twenty-six hundred rads …”

  Three thousand rads? And decreasing? That made no sense.

  The only part that made sense was that Daniel Austen was now dying. And so was she.

  Only she wasn’t.

  Aboard the Zeus the medtechs laved her thoroughly inside and out, frowning as they did it because no counters anywhere aboard ship showed that she’d taken any radiation. Austen had, and so had the shuttle. Robots went aboard and retrieved Austen, along with samples of everything aboard ship. By that time, the shuttle had stopped glowing.

  The medtechs did what they could for him, knowing it was probably futile. They pumped the contents of his stomach and sent robotic scouring tubes down his esophagus, into his bronchial tree, up his rectum, into nose and ears and eyelids and urinary tract. They scrubbed his skin with chemicals, shaved off all hair, inserted an endotracheal tube because in a few hours he would need help breathing. They gave him a drug to make him sweat, attached an IV, hooked him to both invasive and skin monitors. Throughout, Austen said little except to make his official report. He knew.

  By the next day, Austen was vomiting. The ulceration of his digestive tract had begun. Nothing had happened to Syree.

  The team, plus Rafael Peres, met in her quarters to go over the data. Lieutenant Wu, Major Ombatu, Engineer Lee. Graphs and tables littered the table. Syree said, “Major, summarize what we have so far about the effect.” That’s what they were calling it: “the effect.” Austen, she thought irrelevantly, would have come up with something better. Let the games begin. And his voice full of that jaunty laughter.

  “The effect is a wave,” Ombatu said, frowning, “emitted uniformly from Orbital Object #7 and traveling at the speed of light. It’s subject to the inverse square law. We know that from the rads taken by each of the outlying instrument satellites. The wave seems to have caused primary radioactivity, with a rise time of several minutes. After it passes, secondary radiation remains, but—and this is the key—not uniformly. Some objects retrieved from the shuttle turned radioactive, and some did not.”

  “Why?” Peres said, frowning.

  Syree said, “I have a hypothesis.”

  They all looked at her. She knew how momentous it was, what she was going to say. She picked up the lab report on the shuttle samples. “Look at the elements that went radioactive, and the ones that didn’t. The titanium hull: no. The platinum in the life-support catalyst vials: yes. The iridium alloy in the pressure vessels for gas samples: yes. The lead in Captain Austen’s pewter belt buckle: no. Mercury: yes. Gold: yes. Aluminum: no. Antimony: no. Iodine: no.

  “Nothing below atomic weight seventy-five destabilized when the wave went through. And everything above did.”

  Lucy Wu said instantly, “Lead is above seventy-five.”

  “But with an extremely stable nucleus. That argues that the effect caused nuclear destabilization by weakening the binding energy of the nucleon.”

  Canton Lee blurted, “The effect fucks with the strong force?”

  “I think so,” Syree said.

  Ombatu looked thoughtful. “Yes. T
hat would explain why Syree wasn’t affected. Her suit is made of a carbon composite, and the lighter molecules wouldn’t be affected because the electromagnetic repulsion between protons isn’t enough to overcome the reduced binding energy …” He went to the computer and started to key in equations.

  Peres said, “So Captain Austen took the radiation not from the wave itself, but from the radioactivity of the shuttle parts that the wave affects.”

  Lucy Wu said excitedly, “And when the wave passes, the nucleus restabilizes. But there’s a rise time; the effect doesn’t happen instantaneously, or vanish instantaneously. It takes several minutes.”

  “The strong force,” Lee repeated. He seemed mesmerized. “What a weapon!”

  Syree said, “And we only experienced it at force one. It goes up by primes to nineteen.”

  Peres said suddenly, “We have to secure it before the Fallers ever learn it exists.”

  “Agreed,” Syree said. “But unfortunately the mass exceeds space tunnel capacity.”

  She watched them digest that. Any object that failed to pass through a space tunnel became a black hole. That was the theory, even though the initial mass wasn’t large enough to form a black hole under normal circumstances, and even though no one had actually observed a black hole formed in this way. What had been observed and verified was the cutoff mass: one hundred thousand tons. Orbital Object #7 massed nine times that.