Undertow

by Elizabeth Bear

  Even when emitted as a single particle, in other words, light also behaves as a wave. The cat is both dead and alive.

  But if a detector is placed at each of the two slits, so that the experimenter is aware through which slit it has passed, then no interference pattern emerges. The bars of light and dark vanish.

  Until the particle is detected, it isn’t perhaps everywhere—it is everywhere. When it may pass through either slit, it passes through both. The wave propagates both ways.

  But if a method exists, the wave—collapses. The universe is forced to choose.

  Unlike the infamous cat in the box, this is not a thought-problem.

  This is experimental fact.

  The speculation arises when we consider why. According to Bohr and Heisenberg’s Copenhagen interpretation of quantum theory, the individual photon passes through both slits simultaneously and produces the striped pattern by interfering with itself. In other words, it simultaneously follows both possible paths. The “many worlds” formulation additionally suggests that the particle not only travels through both slits, but that it takes every possible path to get there, and that it is detected at every possible destination—in mutually unobservable worlds. But as long as no one notices where it’s going, and how it gets there—the fork heals itself again.

  Until the box is opened, the cat is both dead and alive.

  And no matter how the photon gets where it gets, in each particular instance, we see all the outcomes at once.

  A bullet splashed Jean Kroc’s skull open on the deck. A Rim security officer fell like a toppled tree as Jean twisted impossibly and shattered his right knee. The bullet missed; the bullet severed Jean’s spine. Jean went quietly, head lowered. Jean went for the rail. Jean took a rifle-butt in the ribs. Jean ripped a weapon from the hands of the guard who stooped to handcuff him. There was no shot.

  There were three.

  Lightning struck the superstructure of Nouel’s barge. There was no spark. Cricket lunged from a runner’s crouch between the riflemen. She went down on her face and awaited the twist of the cuffs. She jumped backward and out, over the rail with a kick-slither, plunged along the side of the boat feetfirst, headfirst, executing a gainer. She tangled on the rail and dashed her brains on the lip of the deck as she fell. She slid on wet wood and hit the bay flat, broke her spine, and drowned. The water closed over her.

  They cuffed her and pushed her to her feet.

  The forward edge of the rain—thin still, barely misting—washed Jean’s and Nouel’s blood down the deck, minicurrents rippling around and over chips of bone. Ogod, ogod, ogod.

  Jean, shoulders drawn back by the cuffs, had half a second to turn and catch her eye, lift his chin in disdain of their captors before they herded him away. Cricket, neck snapped in the fall, was drowning, her flaccid body swung against the side of the boat by the lapping waves.

  Nouel ran for it. Nouel ran below. Nouel got shot trying. Nouel, wincing, on his stomach, wiped his data and prayed.

  André—got lucky.

  Freakishly, unnaturally lucky. There were no more Rimmers. There were two. There were four. He walked between bullets like a wire-dancer; he shot one opponent and disarmed the other with a swing of his heavy cane; he danced across the deck and lifted himself over the rail.

  He slid in blood and landed hard on his casted leg.

  Even luck has its limits.

  And anything that can go wrong—

  —already has.

  He screamed; they were far enough from the disintegrating remains of Novo Haven that the storm claxon was not loud enough to cover the sound. He gritted his teeth and made no sound at all. The cane had gone flying, and so he crawled. The cane lay by his hand, and he levered himself to his feet, his knee grinding sweet agony when he tried it with his weight.

  As he was dragging himself to the rail, as he was lifting himself to his feet, as he was bleeding from a wound to the chest, the thigh, the throat—

  —all the ranids in the world came frothing over the rail.

  Jean smacked hard and sharp into the water between barges, headfirst, dove deep. Was cut by a propeller, was broken by the fall. Knifed to the surface and kicked. Snorted water that tasted of oil, that he imagined tasted of Cricket’s blood. Of course, it did not—she was not bleeding, she bled on the deck he had left, she surfaced ten feet off, she surfaced beside him and a sniper blew her white face red.

  Then he tasted blood for real.

  Down, down, only a few feet of water would shred a hypersonic bullet like soft cheese. Down, kick, down, die, down, live, down, swim, swim.

  André could have shot at the frogs, but in no set of choices did he do so.

  He never raised the pistol; he lowered it again; he tasted violet ranid blood thick in his mouth and gagged, his steady gun-hand shivering. He could have shot.

  He could have.

  He remembered Gourami and Tetra sinking their dead, remembered them searching the fallen for Caetei.

  He lowered the gun, he turned it and surrendered it to the nearest ranid, he slipped it into his holster. And sometimes they killed him—what was one more strange human in the dark?—and sometimes they didn’t. But he never pulled the trigger.

  He walked in among them; he limped; he stumped; he helped them drag him. There followed silence; there followed screaming.

  The ranids made no sound.

  There was a craft—a scoot, a dinghy, a flashboat. Sometimes, corporations being what they were, its codes were still set to one of the factory standards. There was a froggie, a pair of frogs. He knew this frog, one of the frogs, knew its worried eyes and its long vague mouth, though it seemed teardrop-shaped and fat under the bandoleers. “Ziyi Zhou,” he said to Gourami, over and over again, a thousand voices, one choice. “I have to get to Zhou.”

  For Timothy Closs, it was a long and shattered night. The barge drifted broadside into shipping and met an outbound ferry full of evacuees amidships; the engineers restarted the engines in time; an electrical fire started in the machine room and she burned to the waterline while the fleeing city parted around her in two floodlit streams.

  The saboteurs—including Deschênes, including Maurice, fuck, fuck—were captured. They escaped. They were killed, singly or in combination. They waves broke in interference patterns, the probabilities greater or lesser, bright bars and dark, fuzzing at the edges. Some futures grew almost inescapable, some diverged on random looping paths from a single freakish chance. A barge exploded, Jefferson Greene’s chopper crashed in the storm, one of the lighters overshot the landing zone in the storm and crashed through two dozen still-moored barges.

  The ranid army arrived, and arrived, and arrived. All Rim’s defenders fell. They drove back the boarders with few casualties. Rim held the center of the ship by force of arms; staff escaped in helicopters; staff went to ground to wait out the battle.

  Sometimes, Closs was one of the ones that made it out.

  There were times for subtlety and concealment. For the Jean Krocs who escaped the raid on Nouel’s boat, this was not the time for either. A transfinite number tried sneaking; an insignificantly smaller transfinite number failed. The few who succeeded were too late.

  But some of the Jeans chose to run, to steal fast boats moored alongside fleeing barges or knock a pilot from an idling flashboat. They put their heads down and the throttle on full; they cut the night with roaring engines and wakes that rose like shimmering curtains on either side and fell behind. They died on the bay and they died in the bayou—in collisions, in malfunctions, when their roaring boats hit snags, when they missed a turn of the narrow channel and were crushed under a somersaulting craft.

  But some of them won through. And of those, some did not break a leg or an arm or their neck clambering through trees with no moonlight to aid them, as the storm sealed up the brilliant night.

  Every single one that made it into the humming embrace of the hollow tree remembered to lock the door.

  And then there was
no choice. Because half a glance at his instruments told him that his intent—to shut the system down and hunker until nature took its course—might be a worse disaster than anything else. Here in the calm, shut away from the storm and the cascading effects of other’s choices, he could think. Could even experiment, one of him risking, the others observing.

  There wasn’t time, he all thought, for much of that.

  The world was trapped midchoice. Stuck.

  Middecision. Midfork. He would have to push it through. Have to fix it, observe it, make it real. Lock down the path that the world would follow.

  There was a problem with that. He was probably safe. He was the observer now. But he wasn’t the only one who had died that night.

  Or who hadn’t.

  He sat down in his chair. He pulled the virtual-reality helmet over his head, positioned the keyboards, worked his hands into the gloves by feel. He flexed his fingers and the interface lit up, sharp relief.

  The timestreams normally ran through his interface in a smooth braided strand, like weavable water. Loops might curve off, but they arched back, and the whole had a kind of flowing inevitability.

  What he saw now was a cataract. Loops and coils and rivulets bounced wildly, intersecting, splashing. Some were fatter—more probable timestreams—and some were bare hair-threads, finely shining wires.

  Jean just paused for a moment and blinked, boggled. And then he took a deep breath—the VR mask pushed against his nose—and assumed his avatar.

  He wore a ten-legged spider for this work. Not a biological spider, but a delicate creature of silver and cobalt glass, its legs adorned with pinchers and combs and feather-fine barbs. He scampered across the surface of the virtual timestreams, testing them with palps and toetips, the movements of the spider controlled by the fine twitches of his gloved hands.

  Normally, he was meticulous and hesitant over this work. He’d dip a limb in the timestream, let it flow over the sensing hair, sample and test and inspect weave after weave for the intersection of most advantage.

  Now, he plunged and grabbed and shoved. He moved through a storm of time like a dancer dodging whirling blades, captured renegade threads that slithered, slick and willful, through his grasp. The thicker streams were muscular as snakes, the thinner sharp as wire. And they could dissolve into water, or fork into a fistful of writhing medusa strands, at a touch.

  He chose the thickest one, the hardest to bend, and bestrode it. His legs darted about him, three or four shaping and sustaining that base timeline, the rest snagging any stream that wandered close and edging it back into the channel. He tried to pick—to snip the threads that ended in disaster and reinforce the ones that led to tolerable futures. But he didn’t know, half the time, what he was grabbing, and there was so much—

  He juggled cold silver fire. It tasted of death and diesel and explosions, of spilled blood and the salt of storm. It sang to him like flicked crystal.

  He bound and wound and twisted tight, sharp, and sweet.

  Winning.

  And tried not to wince each time he grabbed one thread and integrated it, and watched another one snuff out, vanished to a fading afterimage of silver, and the one he’d chosen smelled of char.

  André dragged himself from the cockpit of the flashboat, or he walked, or the froggies helped him up the ladder. Ziyi Zhou sometimes came out to meet him, and sometimes helped him up the ladder. André’s cast was soaked and dripping, inflated plastic squishing water out the top of the boot with each pained step. Sometimes, Zhou even turned him away.

  “I can’t reach him,” she said, or “Not in this storm,” as he commended the data Maurice and Lucienne had died for into her hands. Or she raised a disapproving eyebrow at him as he retained it, unwilling to let the chit out of his hands. Or she said, “Come with me,” and took his elbow, and supported him inside.

  There were locks and codes and pass-pads, and a concealed space in the bow of her barge. And a small soothingly lit compartment with a plain virtual interface, just a helmet and a touchpad. Very stark, calm light on brushed steel, a screen on the wall above the panel that showed a soothing abstract seascape, moving gently.

  André felt a faint misgiving as she seated herself and smoothed her hair back, or he felt nothing but the euphoria of adrenaline, or nothing but drained and tired. “Someone brought down the transfer station,” some of her said. “I heard it’s an alien invasion.”

  “Aliens.” or “That can’t be true.” or just numb silence.

  And whatever he said, some of her answered, “We have to do it on the ham radio.”

  And some of the Andrés that heard her answered, “Brought down the station? Destroyed it?”

  “I don’t know.” Her hands moved over the touchpad; the pattern varied. “You want a concrete answer in this?”

  Outside, worlds away, another André Deschênes died in agony when a ranid insurgent put the bolt of a spear-gun through his abdomen. Other Andrés felt it, and winced. “Probability storm?”

  Some of her laughed, some of her called him ignorant, some explained what that meant. And that those who worked with wave states called it a correction.

  And that she’d never even heard of one like this.

  The barge pitched and yawed as the wind picked up; André felt its conflicting shivers through his many feet. All the Ziyis at their consoles downloaded the chit, burned a copy of the data, and handed the original back to André. Then the current one pulled the helm on over her head and composed herself. “Calling Bryson now,” she said. “We’ll see if I get through.”

  She placed her hand on the smooth dome of the touchpad, and exploded into flames.

  From the inside, head and chest and the white-hot fire eating her as if her bones themselves were phosphorus, the flames tunneling through, burning to the extremities. André reached for her, somehow thinking he could yank the headset off, pull her clear. But the heat licked his fingers, and a thick column of oily grease rolled from her chair.

  And André felt himself collapsing. Narrowing, narrowing, crashing in, clenching down.

  The man who grabbed Ziyi Zhou’s shoulder would likely die. Unless, on some other timeline, he was already dead. Unless he were about to vanish from possibility, like a photon detected passing through the other slit.

  Knees like gelatin, eyes watering from the smoke, André backed out of the hold, the data chit folded in his left hand.

  Cricket—this Cricket, of all the Crickets that could have been—was still alive when she finally met Timothy Closs, in an improvised meeting room aboard an evacuation ship, running before the storm. They’d brought her in by chopper, a ride harrowing enough that she planned never to leave the surface again. She didn’t know if Closs had come in the same way, or if he’d been here all along.

  Judging by the state of his hair and a tear in the sleeve of his jacket that was still repairing itself, he’d probably been in the fighting, which she knew about because she’d been eavesdropping in the helicopter.

  Despite it all, though, it was morning, and the world was unsplintered, though the storm defeated any glimpse of rallying dawn. Cricket was wet to the skin. Her blouse—saturated with salt spray—had given up the ghost and hung against her body in sodden, lifeless folds. She shivered, and with her hands fixed behind her, couldn’t even hug herself for warmth.

  She drew her shoulders back, though, and set herself on her heels, refusing to tilt her head and stare up at him. He wasn’t tall, but it didn’t take much to be taller than she.

  He studied her for a moment, though, and didn’t step too close. He was a fit, compact, older man. He frowned, his hands clasped behind his back as if in unconscious mimicry of her own less-voluntary pose. Any minute, she thought, he’d cock his head and say something like You’ve been a great deal of trouble.

  But what do you say in a situation like that, if you don’t have the scripts to fall back on?

  He surprised her. A thoughtful regard, straight-on, and then he turned away.
“Major?” she asked his back, her teeth rattling.

  “Get this woman a blanket,” he said. “And something hot to drink. With sugar and caffeine in it.”

  They did, and eased her restraints, resealing the plastic cuffs in front of her instead of behind so she could sit and manage the cup. When she was halfway comfortable, her hair and clothes soaking the dry blanket—garish Charter Trade green—they wrapped around her shoulders, he leaned back against the edge of a table, folded his arms across his chest, and gave her another considering look.

  The silence in the room let the sound of the storm seep through. Beyond the shutters, wind wailed and hail and rain slashed the sides of the vessel. She hoped they didn’t run into a waterspout. On the other hand, that wouldn’t matter much to her if they were planning an execution.

  “I hope you’re proud of yourself,” he said.

  The gesture of her chin included the storm, his torn sleeve, the restraints on her wrists. She cupped both hands around the mug of cocoa that warmed her palms. “I hope you don’t think I had anything to do with this.”

  “Enough to go forward on,” he said. “Unless you want to tell me a little about what your plans are.”

  Oh, what the hell. Either André had gotten away or he hadn’t; if he had, Ziyi had the information already. If he hadn’t, maybe she could scare Closs into doing something stupid. “We know,” she said. “We know that the omelite is the by-product of a Slide explosion; we know about the exploitation of the ranid workers; we know that Greene’s World is undergoing a major ecological catastrophe due to unregulated tanglestone mining; and we know that the ranids had a technological society and willingly relinquished it. And we’re telling the Core, Major.”

  “You’re bluffing.” Calm, but that crease between his brows was deepening. “You can’t prove any of that.”

  She sipped the cocoa. It was she who cocked her head. “Lucienne Spivak was a Unified Earth security agent, Closs. You killed a uniform. And André Deschênes will testify to it.” Please, André. Please have gotten away.