The Clockwork Rocket

by Greg Egan

  Ten more nights of this unprecedented madness remain. If the customers were paying then this cheerless and unscrupulous diversion would quickly close for want of funds, but Talk urges the next best outcome: an empty hall, to shame these charlatans into silence.

  When Yalda reached the apartment Daria was awake, so she showed her the piece.

  “I wouldn’t pay too much attention to Talk,” Daria said loftily. “Their idea of pushing the intellectual boundaries of journalism is to cover a literary salon.”

  “What’s a literary salon?”

  “An event where people who can’t read or reason gather to reassure each other of their own importance.”

  Yalda said, “But anyone who reads this will think the whole thing’s some kind of… investment scam!”

  Daria was amused. “Anyone who’d take this uncomprehending babble seriously was already a lost cause: they were never going to help you improve the Peerless, let alone volunteer for the ride.”

  “Maybe not,” Yalda conceded. “But—”

  “But you want everyone in Zeugma to understand what’s at stake?” Daria suggested.

  “Of course. Don’t you think they’re owed that?”

  Daria said, “I’ve been in the business for ten years, and I’ve had notices far worse than this. Believe me, the people who are truly curious will still come.” She rolled the sheet deftly into a cylinder and launched it across the room. “Just forget about it.”

  Lidia had worked a late shift and was still asleep; Daria agreed to take the children to school. Yalda did her best to follow Daria’s advice, but when she reached the university Giorgio had more bad news for her: the senior members of the department had voted to refuse Eusebio’s offer to fund a new observatory. What’s more, they were taking their title over the land to Zeugma’s Council, seeking an order forbidding Eusebio from interfering with their present use.

  Giorgio said, “If the telescope is raised entirely above the atmosphere it would actually improve the quality of observations. So if you can get the right wording on the order…”

  Yalda was in no mood for jokes. “I thought you were going to persuade your friends to vote for this! Whatever they think of Eusebio’s rocket, a bigger telescope would be a worthwhile trade-off, surely.”

  “I’m sorry,” he said. “Ludovico had more favors to call in than I did.”

  Yalda didn’t doubt that Giorgio had kept his word. But he was still trapped in the kind of anesthetized state from which she’d taken so long to emerge herself. When he argued the physics with her, he accepted that the orthogonal cluster theory of the Hurtlers was as plausible as any alternative—but he still couldn’t bring himself to take the threat seriously, to look at his children and imagine their extinction.

  Yalda had a lecture to deliver for the introductory optics course. As her students dutifully recorded her diagrams and equations for the laws of thin lenses, she felt like someone handing out useless trinkets at the edge of a raging wildfire. But she was forbidden from discussing Eusebio’s project during her lessons, or holding recruitment meetings on the campus. If any of these bright young men and women wanted to know the truth about the matter, they’d have to make the effort to turn up for the night’s unscrupulous diversion.

  At lunchtime, as Yalda entered the food hall she saw Ludovico coming out of the pantry, his arms laden with loaves for a group of fellow diners. She hung back to avoid crossing his path, but he saw her and approached, calling out to her in a booming voice pitched to attract as much attention as possible.

  “Professor Yalda! I’m surprised to see you here! I thought you’d left us for the entertainment business.”

  Yalda humored him with a desultory buzz, but couldn’t help adding, “It seems everyone has two jobs these days; I see you’ve gone into journalism, yourself.”

  “I was consulted by journalists,” Ludovico replied stiffly. “As a noted authority on the Hurtlers, not a paid employee.”

  Yalda said, “Forgive me, but I must have missed all your learned publications on ‘Spontaneous Excitations in the Solar Miasma’. Perhaps you can rectify my ignorance on the topic by explaining precisely what that phrase means?” Everyone in the hall was watching them now, through rear eyes or front.

  Ludovico said, “Gladly. One particle of the solar wind expels a fast luxite, which strikes another, prompting it to do the same. And so on. Other, slower light is emitted as well. That is what the Hurtlers are: long chains of activity arising within the gas itself, mediated by fast-moving particles of light.”

  Yalda bowed her head in a gesture of gratitude, then feigned deep contemplation for several pauses—contemplation that failed to dispel her puzzlement. “But why are these ‘chains of activity’ parallel to each other? Why are these ‘spontaneous excitations’, these random events, all lined up in exactly the same direction?”

  Ludovico replied without hesitation, “A distant source of rapid luxites—not quite at the resonant energy that would trigger an excitation itself—illuminates the solar wind and nudges the particles into alignment. The gas spontaneously emits its own light, but it is not randomly oriented when it does so.”

  Yalda was speechless for a moment, marveling at the utter shamelessness of this absurd contrivance. “That’s nonsense,” she said cheerfully. “And you know it’s nonsense.”

  Ludovico replied with calm hauteur, “Refute it, then. Show me your meticulous observations establishing my theory’s falsehood.” He began to walk away, but then he paused and turned back to face her. “Oh, I’m sorry, that was thoughtless of me! To make an observation, you might need an observatory… a facility that you’d prefer to see shattered into dust by your demented co-stead. Enjoy your meal, Professor Yalda.”

  On stage in the Variety Hall, Yalda tried to push the day’s setbacks out of her mind and focus on the presentation. Even her bountifully bulky body was too small for people to read from the back row, so she’d worked with the Hall’s set designers to create a contraption with a sunstone lamp and lenses that projected a series of printed images onto a large white screen behind her.

  As she gazed out into the darkness that concealed the audience, she honed her message, stressing its simplicity. Time was just another direction in space: nothing else could make sense of light’s behavior, or the ferocity of burning fuel. And to keep light tame, time needed to be finite—which meant that history would wrap around and meet itself, as surely as the system of roads and railway lines that wrapped itself around the planet. But while neighboring cities worked together to plan the railway lines between them, any intersections in the histories of worlds would be haphazard and ungoverned. Spectacular as they were, the Hurtlers were mere pedestrian tracks on this map; ahead, there would be busy freight lines.

  Eusebio joined her, and the screen reprised the simple sketch he’d shown her: the detour, the long slow zigzag into the future that could buy them time, and with it fresh ideas and discoveries. It would be a risky journey, daunting for anyone to contemplate, but the Peerless needed whatever Zeugma’s people could bring to it. Navigating the void was just the start; to keep the community of travelers alive and thriving would take a whole city’s worth of inspiration and expertise.

  Daria had advised them not to take questions from the floor; that only invited attention-seeking hecklers. Instead, they set up two desks in a corner of the foyer and invited people to come and speak with them after the performance, quietly, face-to-face.

  Yalda had braced herself for a frenzy of disparagement spurred on by the negative coverage in Talk, but the audience as a whole had been no rowdier than the night before, and the individual interlocutors who approached them after the show were, if anything, more polite and encouraging. “I don’t believe a word of your scaremongering,” one young man told Yalda amiably, “but I do wish you luck.”

  “Why do you think it’s scaremongering?”

  “The world has survived for eons,” he replied. “History might not mention shooting stars like th
ese, but the world is far older than we are. Geologists say the planet has been bombarded many times before; a few more stones from the sky will hardly be a calamity. But if you can send a rocket through the void and bring it back safely, that will be something to admire.”

  “I can’t interest you in being a passenger yourself?” Yalda wasn’t taunting him; it might be worth having a thoughtful, good-natured skeptic among the travelers.

  He said, “I think my children will stand a better chance of surviving with solid ground beneath their feet.”

  Eusebio had to leave for an appointment with a legal adviser about the observatory dispute. Yalda decided to stay on a little longer; the foyer wasn’t empty yet, even if most of the dawdlers seemed to be talking among themselves rather than waiting for the right time to approach her.

  When the clock struck two chimes before midnight, she started packing away her information pamphlets. She’d gathered five more names on top of the seven from the night before, and even if these volunteers were willing to do no more than plant crops in an artificial cave inside the mountain, that would be something.

  As she stepped away from the desk, a young woman hurried across the foyer toward her.

  “I’m sorry,” the woman said. “I wasn’t sure if I should speak to you, but…”

  Yalda put down her box of pamphlets. “What did you want to say?”

  “I was thinking about your rocket. One thing worries me—” She stopped and lowered her gaze, suddenly shy, as if her words might already have been too presumptuous.

  “Go on,” Yalda encouraged her. “If there’s only one thing that worries you, you’re a dozen times more confident than I am.”

  The woman said, “When the rocket turns around and comes back toward us… from the point of view of the travelers on the first half of the journey, isn’t it now moving backward in time?”

  “Yes it is,” Yalda agreed. “That’s exactly right.”

  “And from the point of view of the Hurtlers, and the worlds you think might collide with us… the same thing is true? In the second half of the journey, the rocket will be traveling into their past as well?”

  “Yes.” Yalda was impressed; though it was a simple enough observation, only Eusebio and Giorgio had raised it with her before.

  The woman looked up, fidgeted anxiously. “Is that… safe?”

  “We don’t know,” Yalda admitted. “To what degree the rocket will carry its own arrow of time, embodied in its passengers and cargo, and to what degree its surroundings will influence the arrow… we don’t know.”

  “So you’re hoping the travelers will learn enough on the outward voyage to protect themselves on the inward leg?” the woman suggested.

  “I suppose it does come down to that.” Yalda had berated Eusebio for relying on uninvented methods of propulsion, but the truth was they had no hope of preparing the travelers in advance for every hazard the journey would entail.

  Gaining courage, the woman said, “I’d be satisfied if you could at least be sure that the rocket was heading into the Hurtlers’ future at the start of the trip. If it takes half an age to prepare for the clash, so be it—but having to face that problem from the very beginning would be too much.”

  “Satisfied enough… to approve of the venture?”

  “Satisfied enough to be a passenger myself.”

  Yalda said, “Can I ask your name?”

  “Benedetta.”

  Yalda took her over to the desk and recorded her details, trying not to let slip that no one else had come close to making such a commitment—not even the recruiter herself.

  “Have you studied somewhere?” Yalda asked her. The first passenger of the Peerless had described her profession as “factory worker”.

  “In Jade City,” Benedetta admitted reluctantly, as if this were somehow shameful. “I studied engineering, but only for a year.”

  “It’s not important, I was just curious.” Yalda heard the forced joviality in her own voice, and struggled to bring the tone back to normal. Asking Benedetta if she were a runaway might frighten her off completely; it was an issue they’d need to deal with at some point—in order to protect both her and the project—but for now all that mattered was that she was keen, and a quick enough thinker to have spotted a genuine problem.

  They were alone in the foyer now. Yalda said, “I’m supposed to be out of here before the cleaners come in at midnight, but we can talk for a bit outside if you’re not busy.”

  “There’s nowhere I need to be,” Benedetta replied.

  Outside, the city was quiet. A dozen slow Hurtlers were spreading their colors across the sky. As the two of them walked away from the hall across the cobblestones, Benedetta said, “Do you really believe that time loops around on itself?”

  “I can’t be certain,” Yalda replied. “But I think the evidence is strong.”

  “So the future is no different from the past?”

  “The real difference is a matter of what we know,” Yalda said. “What information is easily accessible to us. We can know much more about the past than the future, at least if we don’t try to look back too far. But that’s a product of the vagaries of history; there’s no absolute distinction.”

  “But then… everything that’s yet to happen is fixed, just as much as everything in the past?”

  “Yes.”

  “So why are you striving so hard to change the future?”

  Yalda buzzed with delight; she should have seen that coming. “‘Change’ isn’t quite the right word,” she suggested. “You can strive to change a bad law—because the law can be different at different times. But either we survive this encounter or we don’t. Whatever the outcome is, no one will change it.”

  Benedetta accepted this, but persisted. “What word should I use then? ‘Influence’?”

  “I can live with that,” Yalda said. “I’ll own up to striving to influence the future.”

  “But how can you influence the future if it’s as fixed as the past? Do you try to influence what happened yesterday?”

  “Not anymore,” Yalda said, “but I certainly did the day before.”

  “Why, though? If you believe that what happened yesterday has always been fixed, wouldn’t it have turned out the same, regardless?” Benedetta wasn’t teasing her, or playing rhetorical games; she genuinely needed an answer.

  “Ah.” Yalda hadn’t had a conversation like this since the long nights she’d spent talking with Tullia—and back then, the roles would have been reversed. “I don’t believe in the kind of predestination that says our actions are irrelevant. So I don’t accept that yesterday would have turned out the same, regardless of what I did.”

  “But if your actions aren’t irrelevant, then you can’t be choosing them freely, can you?” Benedetta argued. “If the future is fixed, and your actions affect the future… then your actions themselves must be fixed, otherwise they could lead to the wrong outcome. That means you have no real choice in what you do; you’re just a puppet, steered by forces beyond your control.”

  Yalda thought for a while. “Raise your right hand.”

  “Why?”

  “Go on, humor me.”

  Benedetta complied.

  “Were you free to raise it or not, as you wished?” Yalda asked her.

  “I believe so.”

  Yalda said, “Tell me why you should feel any differently about that, depending on whether or not time is a loop and the future is really the distant past.”

  Benedetta puzzled over the question. “If it was always going to happen—if in a sense it had already happened—then when I thought I was making the decision, that was just an illusion.”

  “An illusion compared to what?” Yalda pressed her. “Tell me how the world could work—how physics could function, how history could be arranged—in a way that would somehow make you ‘more free’?”

  “If the future is open,” Benedetta replied. “If our actions are undetermined until we decide what to do.”
<
br />   “Suppose that really is the case,” Yalda said. “Then what is it that finally determined whether you raised your arm or not?”

  “I did. It was my choice.”

  “But why did you make that particular choice, and not refuse me?”

  Benedetta didn’t reply immediately. “The way you asked, I suppose,” she said finally.

  “So I determined your action?”

  “No, not completely. My mood, my state of mind played their part as well.”

  Yalda said, “None of the things you’ve just referred to disappear from the world if the future is fixed rather than open. Both of us are still here. Our actions are still related in exactly the same way to our wishes, our wishes to our personal moods and histories, and so on.”

  Benedetta was not convinced. “If the future is fixed, how can this conversation even mean anything? If it’s an unchangeable fact that I will say whatever I end up saying to you—as if we were just actors following a script—then how can we really be changing each other’s minds? How can we be communicating anything?”

  “Do I sound as if I’m making random noises for no particular reason?” Yalda joked.

  “No.”

  “If there’s a script,” Yalda said, “then we’re the playwrights as well as the actors; there’s no one else who could write our lines. There’s no puppet-master rushing around coordinating everything, forcing us to act against our will—or to make choices that go against our nature—just so history will reach its pre-ordained conclusion.”

  “Then how does it work?” Benedetta demanded. “How do things turn out the way they have to?”

  Yalda said, “The trick is to stop thinking that it works like fate in the sagas: some tedious monarch overcomes the odds and wins a great battle, because all the bit-players are nothing but cogs whose every action is subservient to his destiny. The reality is the opposite of that: ‘the way things have to be’ is completely unspectacular, and it’s fulfilled at the lowest possible level.