The Clockwork Rocket

“Of course.” Tullia shook herself out of her stupor. “That was, what, three and a half pauses from violet to red?”

“Sounds right.”

“Which puts it far above the atmosphere, but still close; a fraction of the distance to the sun.”

“A gross and a half severances or so,” Yalda confirmed.

The people around them were still buzzing with excitement, but Yalda detected no real sense of how extraordinary the sight had been; it was as if they’d just witnessed an elegant fireworks display to cap off the magic show.

“What if it had been closer?” Tullia asked. “What if it had hit the ground?”

Yalda had never seriously considered the possibility of a collision; with barely more than half a dozen sightings in a generation, it struck her as a remote prospect. “I wouldn’t like to be standing at the point of impact,” she conceded.

Tullia said, “I wouldn’t like to be on the same planet.”

The current thinking about the Hurtlers was that something was colliding with the tenuous gas that wafted out from the sun to occupy the surrounding region. Just as an ordinary shooting star could burn up brightly in the atmosphere, even the sun’s thin exhaust might be enough to ignite a sufficiently rapid interloper.

How rapid were the Hurtlers? If an object was moving so speedily that you might as well imagine its entire trajectory erupting with light all at once, then the closest part of that long straight line would appear to a watcher first in violet, the fastest color, with the other hues following. Each color would appear to fly out along two opposing, symmetrical trails, as the light arrived from pairs of equidistant locations ever farther from the watcher. Any measurable asymmetry in the color trails would imply a lower speed for the object itself—with light from earlier parts of the trajectory gaining a head start—but as yet nobody had observed such subtle effects with enough confidence even to be sure which way the Hurtlers were traveling.

“If you can salvage my geometrical theory of time,” Yalda bargained, “the pay-off is that something so fast won’t be carrying as much kinetic energy.”

“If I salvage your theory,” Tullia retorted, “nothing will even need kinetic energy to tear itself apart. Everything in the cosmos will be itching to turn into light and hot gas.”

“Don’t blame me if there are no happy endings; I didn’t invent entropy. Darkness and cold dust… bright light and hot gas. Does it really matter which one we end up as?”

They began making their way toward Tullia’s apartment, to put their observations onto paper.

Tullia said, “You do realize that according to your theory, someone traveling along with the Hurtler would think that half the light we just saw was coming in toward them, not going out?”

Yalda made a quick sketch on her chest.

“You’re right,” she said. “That’s eerie.” The arrow of time shared by the world and the solar atmosphere was so different from the Hurtler’s arrow of time that Tullia’s hypothetical traveler would have seen a part of the light- burst converging on them—violating the law of increasing entropy as surely as if a roomful of smoke had shrunk in on itself and turned back into fuel. Obviously entropy couldn’t increase along every direction in four-space at once, but it was unsettling to have an example of the bizarre disparity play out right in front of their eyes.

Yalda brushed the complication aside; she was having enough trouble trying to make the exponential blow-up in the light equation go away. She was scheduled to deliver a summary of her theory to the school of natural sciences in less than two stints, but if she couldn’t offer Giorgio a plausible solution to the flaw he’d uncovered, he’d cancel the talk.

When they entered the apartment, Antonia was seated on the floor with dye and paper beside her. A firestone lamp was sputtering on the shelf above, casting a forlorn shadow. She’d probably been composing another letter to Antonio, but when Yalda and Tullia approached to greet her, her skin was blank. Yalda wished she could have offered her advice or comfort, but what did a solo have to say about the choices she faced?

“How was the magic show?” Antonia asked, forcedly cheerful.

“Upstaged,” Tullia replied. She described the celestial mirror trick that had followed.

“I heard some commotion from the street,” Antonia said. “I looked out the window, but it must have been over by then.”

“Do you mind if we use the dye?” Yalda asked. She wanted to have the report on the Hurtler completed as soon as possible, ready for the couriers who’d be leaving at dawn.

“Of course not.” Antonia put the lid back on the pot and slid it toward her. “I was still gathering my thoughts; it can wait until morning.”

Yalda saw the curtain part at the entrance to the apartment. As she spun around to face the intruders one of them screamed, “Lie on the floor! All of you!” By now, four men had filed into the room, and there were more behind them. They wore police belts, and they’d unsheathed their knives.

Antonia began wailing. “I’m sorry! Tullia, I’m sorry! Someone must have—”

Tullia said, “Be quiet, you don’t know—” One of the officers stepped up to her, knife outstretched.

“Lie down, or I’ll split you open!”

Tullia knelt then lay on her chest. Yalda met her rear gaze, hoping for advice, but if there was a message she couldn’t read it.

Yalda said, “Antonia, get behind me.” She moved toward the officer who’d threatened Tullia. He was tiny; if not for the knife she could have done what she liked with him. “You want to go out the window?” she taunted him. “You’ve got no business here. Go harass someone else.”

The man raised the knife confidently, no doubt accustomed to its power to induce obedience. Yalda advanced on him, undeterred. She wouldn’t even need to extrude extra limbs for the encounter; if she seized him with both hands it wouldn’t matter if she lost an arm in the process, she could still fling him down to the street with the remaining one.

“Please, Yalda, don’t!” Antonia implored her, distraught. “I’ll go back! Don’t make trouble for yourself!”

Yalda was unmoved; what gave these buffoons the right to interfere in anyone’s life? If one of them spilled his brains on the cobblestones, the others might rethink their priorities.

Tullia addressed her calmly. “Yalda, if you resist, we’ll all get a beating. If you harm even one of them, we’ll all be killed.”

Yalda stared at the man in front of her, then forced herself to look past his triumphant sneer to the long line of colleagues waiting behind him, knives at the ready. She might be able to deal with three or four of them before she was overpowered—but if Tullia was right, it would not be worth the price.

She knelt down, then lay on the floor, subduing her rage. Her physical strength meant nothing. The rightness of her cause meant nothing. The Council had given these men the authority to capture and return runaways; Antonia’s plans for her life were irrelevant.

The officer she’d confronted put a foot on her back and held her arms behind her while someone passed him a length of hardstone chain. He slipped the loop at the end of the chain around one of her arms, then took a vial from his belt and shook a few beads of bright red resin onto her palm. It stung fiercely, but Yalda forced herself not to lash out. Then he pressed both of her palms together. Skin stuck tightly to skin, in itself no great hardship, but the resin made her body act as if these ordinary surfaces comprised a kind of internal partition, a pathological mistake that needed to be broken down.

Yalda closed her eyes for a moment, fighting not to lose consciousness. She had no right to be surprised by any of this; how many prisoners had she seen shuffling through Zeugma with their arms melded? She’d looked away, like everyone else. Murderers and thieves got what they deserved.

The officer ran the tip of his knife over her skin methodically, until he found the telltale crease of a pocket.

“Do you want me to cut it open?” he asked.

Yalda opened the pocket. He reached in and took out a handful of coins and her vial of holin.

In the corner of the room, Antonia was pleading with her own captor. Her hands had been bound with rope,