The Arrows of Time

by Greg Egan

  He took the link from its hiding place under the desk and plugged it into the console.

  The occulters were approaching the bottom of the mountain. Having them crawl over the sharp edge that divided the slopes from the base would have been insanely ambitious, so the machines had been instructed to fly from one surface to the other, keeping as low as possible but sparing themselves the most difficult terrain.

  Centrifugal gravity turned the base of the mountain into a sheer vertical wall. The cargo hooked to the occulters’ arms would hang down over them, applying a torque that would try to peel them off the rock, and increasing the risk of the connecting strings becoming tangled in the clockwork. Ramiro had programmed adjustments to the depth and angle of the drills that he hoped would minimise the problems, but it was all untested; there’d been no reason back on the Surveyor to rehearse for this strange asymmetric loading. He found it hard not to resent Giacomo’s group for failing to devise a better solution when they’d had three years’ warning, but then the innovation block wasn’t an imaginary disease that people invoked just to excuse their laziness. Agata’s long silence since she’d set out to overcome it proved just how pernicious it must be.

  A short burst of data appeared on the console. Tarquinia chirped. ‘Number one’s made the jump!’

  Ramiro waited for the next report, then scrutinised the figures. ‘It’s clinging on, and it hasn’t jammed.’ He wasn’t satisfied yet; it was still possible that the strings would become progressively twisted. The occulter rotated its body in opposite directions with each step, so all things being equal it ought to unwind as much it entwined, but he could imagine some configurations of the strings interfering with the process and favouring one direction.

  But in the third report the torques were unchanged, and the fourth confirmed that nothing was escalating. The occulter was cycling its way up the rock face towards its target, tenaciously regaining the same equilibrium with every step.

  Ramiro sagged across the desk. ‘I think I just aged another six years.’

  Tarquinia said, ‘Better here than back on the Surveyor.’

  ‘That’s true.’ Ramiro had never thanked her for the lengths to which she’d gone to spare him that fate. He sat and watched her for a moment, wondering what she’d say if he raised it after all this time. But he suspected that it would only annoy and embarrass her if he told her that he knew what she’d done for him.

  The second occulter flew over the edge, and recovered as well as the first. Ramiro was wary of becoming complacent — but it made no sense to reason about the machines’ fate without taking account of everything he knew of both the past and the future. The disruption would happen, that was close to a certainty, and the occulters’ behaviour had to be consistent with that. The cosmos was indifferent as to whether the solution of its governing equations described the Peerless obliterated by a meteor, or just a few conspirators managing to shatter a few mirrors. But even the most dispassionate mathematician who’d been told that twelve clockwork insects carrying explosives were crawling across the mountain towards the light collectors would have to accept that the second solution now appeared at least as viable as the first.

  The third occulter reported success. The fourth, the fifth. Ramiro said, ‘When this stage is over, we should go and tell Agata and Azelio. They deserve to have their minds put at ease.’

  Tarquinia was sympathetic, but not so sure that it would help. ‘Do you think Azelio would get any comfort from this?’

  ‘Once he’s confronted with the sheer improbability of a meteor arriving at exactly the same time as the occulters, it might change his perspective.’

  The sixth occulter landed safely and commenced its upwards crawl. Tarquinia said, ‘After Agata and Azelio, we should break the news to the Councillors.’

  ‘Really?’

  ‘Just to taunt them,’ she stressed. ‘No details.’

  Ramiro said, ‘Where’s the fun in that? They’ve known for three years that they were going to be defeated.’

  ‘I’m not sure that’s true,’ Tarquinia replied. ‘I think they convinced themselves that it would be a meteor. No defeat, no surrender, just an act of nature.’

  The seventh occulter sent its report. Ramiro squinted at the numbers, confused. ‘What . . . ?’

  Tarquinia leant closer to the screen. ‘It’s gone into the void. It fired the air jets to leave the slope, but then something jammed and it couldn’t get back.’

  A second report arrived; the accelerometer showed the occulter in free fall.

  Ramiro was numb. ‘That’s impossible. How can we lose one when we have no spares?’

  Tarquinia said, ‘What if we change some of the targeting? Maybe we can take out two light collectors with one bomb – or three with two.’

  Ramiro brought the target coordinates onto the screen. ‘How do we model this? Do we add the pressures from each shock wave?’

  ‘That will do, for an estimate.’

  The estimate told them that the strategy wouldn’t work. The light collectors were spread too far apart, and the blast radius of each bomb was too small.

  Ramiro was lost. ‘What is it that we don’t understand? Could one channel survive?’

  Tarquinia considered this. ‘So one Councillor already knows what comes after the disruption? It’s hard to believe that they could keep that a secret from the others, and I don’t see how the politics would work: in the aftermath they’d just be despised by everyone for withholding the information.’

  ‘It’s not impossible, though.’

  ‘It’s not impossible, but I’m not going to rely on it.’

  ‘So what do we do?’

  Tarquinia hesitated, then came to a decision. ‘I’ll go out and repair the occulter – clean the jets, change the air tank. It’s in free fall and we know the trajectory; it shouldn’t be too difficult to intercept.’

  Ramiro fought down an impulse to volunteer himself; she’d have a far better chance of success than he would, if she could get out into the void at all. ‘Won’t the airlocks be guarded?’

  ‘I know a way out through the observatory,’ she said.

  ‘A way out that isn’t an airlock?’

  ‘It’s a chamber with two airtight doors,’ Tarquinia conceded, ‘but no one ever uses it to come and go. There are some small instruments that we operate in the void, and we slide them in and out on tracks to avoid all the rigmarole of going outside to tend to them.’

  ‘But a person can squeeze through?’

  ‘Yes. Just barely.’

  Ramiro said, ‘We don’t know that it won’t be guarded, or monitored somehow.’

  ‘No. But we can be sure that every other airlock will be.’

  ‘How will you get access?’

  ‘I think I can talk my way into an observing session – and there are tools, cooling bags and air tanks there already, I won’t need to drag a lot of suspicious paraphernalia with me. All I need is a bell or two alone in the main dome, exploring some hunch about the disruption.’

  ‘A hunch that your colleagues will know must come to nothing, or the Council would have sent the results back three years.’

  Tarquinia scowled. ‘No, it must come to nothing that’s recognised as vital in the next three days – but that doesn’t prove that the observations won’t be valuable later. I can invent some wild theory on my way to the summit. Believe me, I’ve seen the observing program – no one has any idea where to point the telescopes right now. The chief astronomer will be grateful for anything that looks even half plausible.’

  ‘So the instrument will be doing some automated sweep . . . while you’re out in the void fixing the occulter?’ Every part of this sounded desperate, but Ramiro had no better ideas. ‘Won’t you be tracked?’

  ‘If I go straight up from the summit and then arc around towards the plane of the base I can stay out of range of the systems tuned for accidental egress – and I certainly won’t have the signature to be mistaken for an incoming Hurtler.
’ Tarquinia reached across the desk and took the link. ‘I’m going to need this to reprogram the occulter. We should have made it possible to talk to the things with a corset alone, but it’s no use complaining about a lack of foresight.’ She formed a pocket for the link then started dragging herself towards the door, then she saw the expression on Ramiro’s face.

  ‘We’ve both survived tougher jobs than this,’ she said. ‘I’m not going to die out there.’

  ‘I know, but—’

  ‘If I get arrested, just pretend to be shocked. Maybe there’ll still be something you can do – don’t assume that the whole plan’s dead just because they’ve grabbed me.’

  ‘All right.’

  Tarquinia drew herself towards Ramiro and embraced him. ‘This is just a glitch,’ she said. ‘In a few bells I’ll be back here and we’ll be joking about it.’

  ‘Yeah.’

  Ramiro watched her leave, then he sat by the console. Without the link he couldn’t even check what was happening with the other occulters. He didn’t doubt Tarquinia’s skill or resolve, but if they lost one more machine she could hardly repeat the same ruse. The whole plan was on the verge of collapsing, and he had no idea how to salvage it.

  Ramiro pounded on Agata’s door until his hand ached, but there was no response. So much for her sitting in her room and thinking. Who would she visit? Lila? Azelio?

  He looked up Lila’s address on a public console, but he hadn’t gone far when he ran into Agata coming the other way, carrying a box full of books.

  Ramiro greeted her casually and restrained himself from blurting out anything compromising. ‘That’s a lot of reading,’ he said.

  ‘They’re Medoro’s books,’ Agata explained. ‘His family had no use for them, so I thought I’d take them.’

  Ramiro gave a quiet chirp of approval, as if he were acknowledging a respectful gesture of remembrance. ‘It’d be good to catch up with you,’ he said. ‘If you’re not too busy.’

  ‘I’d like that,’ Agata replied. ‘My apartment’s a mess, though – it’s not fit for company.’ They’d never checked it for listening devices.

  ‘You could drop off the books and come to my place, if you like.’

  ‘All right. I’ll see you in a chime.’

  They parted at the next intersection.

  When Agata arrived, Ramiro invited her in and closed the door. ‘If you have another plan,’ he said, ‘now’s the time to tell us.’

  Agata’s composure shattered as if he’d struck her. ‘I couldn’t do it,’ she confessed. She started humming and shivering. ‘I wasn’t strong enough.’

  Ramiro was horrified. ‘It’s all right, calm down! I was just asking.’ In all their time together he’d never seen her so wretched. ‘No one else could break the innovation block – and so far you’ve had about three bells without it.’

  ‘You don’t understand,’ she said. ‘I already had a plan three stints ago – no innovations, it was all gleaned from textbooks. But I couldn’t go through with it.’

  Ramiro led her over to the couch and sat beside her. ‘What happened?’ he asked gently.

  Agata explained between bouts of shivering. ‘I had everything worked out so that Celia would think I’d done a final shift and then quit. No one would have been searching the tunnels for my body. I’d even found a way to repair the grilles behind me so that the other workers wouldn’t notice the damage. I was going to schedule a message to you and Tarquinia, telling you the threshold that the refractive index of the air near the axis would need to cross for you to know that you could cancel the bombs. But after I sent a message to myself to hold fast against Giacomo, I lost all my courage.’

  Ramiro squeezed her shoulder. ‘I’m glad you didn’t do it.’

  ‘Why?’ she asked miserably. ‘If your own plan’s gone bad, all that’s left to explain the disruption is a meteor—’

  ‘We’re not there yet,’ he protested. He described what had happened to the occulter, and Tarquinia’s scheme to get out and fix it. ‘But if you have any non-suicidal alternatives, don’t keep them to yourself.’ Ramiro suspected that the three of them working together might have found a way to get Agata’s chemical into the cooling chamber, but it was too late for that now.

  ‘I have no more ideas,’ Agata said forlornly. ‘That’s why I asked Serena and Gineto for the books. The Council has all of Medoro’s notes on the time-reversed camera, but his design didn’t come out of nowhere. If I can retrace the steps of his education myself, there’s a chance I might see something that I missed.’

  Ramiro pictured the bulging container she’d been lugging down the corridor; he couldn’t read that much in a year. But if Tarquinia couldn’t repair the occulter, they’d have three days to mine Medoro’s textbooks and come up with a new way to shut down the system.

  ‘I shouldn’t keep you from your study, then,’ he said. ‘Just promise me you won’t try anything like the last plan.’

  ‘Why couldn’t they have spoken more clearly?’ Agata asked, bewildered. ‘I thought they were giving me the courage I needed to go down that shaft . . .’ She began shivering again. ‘How can I fail them, when they know my whole future? How is that possible?’

  Ramiro said, ‘There was no message from the ancestors.’ The stupid hoax had gone on far too long, and it had almost killed her. ‘Tarquinia carved those words into the rock, before we left Esilio. You and Azelio were sick, bedridden in your cabins, so it was easy for her to slip away to the blast site while she was packing up the tents.’

  Agata was stunned. ‘Why would she do that?’

  ‘To make the messaging system look redundant, so no one would have to scratch out a living on Esilio.’

  Agata drew away from him. ‘So the two of you lied to me for six years?’ She thought for a moment. ‘Because you wanted me to sell it on the mountain? You thought people might believe my testimony, so long as I didn’t know the truth.’

  ‘That was the plan,’ Ramiro admitted. There was no point going into the whole convoluted history of the thing, explaining his failed attempt to make the inscription his own.

  ‘We don’t know anything now.’ Agata seemed more wounded by this revelation than by the personal betrayal. ‘If the mountain’s wiped out, the Councillors might not make it to Esilio. We don’t even have that comfort any more – we don’t know that there’ll be any survivors at all, that the home world won’t burn.’

  Ramiro said, ‘I’m sorry.’ He’d only meant to spare her the burden of imagining herself chosen by history, pinned to this impossible task by the ancestors’ gaze. But there was no way to do that without stripping away the whole lie.

  Agata rose from the couch and dragged herself towards the door. She said, ‘When Tarquinia gets back, tell her I’m dead to both of you. I don’t care any more. Let the cosmos work it out.’

  Six bells after she’d left for the observatory, Tarquinia had still not returned.

  Ramiro knew that if she’d been arrested she wouldn’t tell her captors anything – but the mere fact of her transgression would mean that the two of them would have been under observation from the moment they’d left the Surveyor. If the authorities had found the link on her, they would have been searching for its signal all along, so they could have picked up the transmissions to the occulters. Even without decoding any of the content, they would have been able to deduce the machines’ locations from the direction of the beam.

  But he didn’t know any of that with certainty. All he could do now was gamble on the chance that the plan could still be salvaged. If he could get outside and fix the occulter himself, everything might yet come together.

  Ramiro checked the records on the console and committed the occulter’s trajectory to memory. Heading straight for the nearest airlock would be futile; he might as well turn himself in. But anyone who could get more than a dozen caches of explosives onto the slopes would have to know a safe way out. His allies had been wise to limit their contact with him, and they’d manage
d to convince themselves that having set the plan in motion there’d be nothing more they’d need to do. But if they hadn’t yet realised how wrong they’d been, it would be up to him to disillusion them.

  ‘I don’t know anyone called Giacomo,’ the man protested irritably.

  ‘I met him here a few stints ago,’ Ramiro explained. ‘I think he borrowed your apartment, because it wasn’t convenient to use his own.’

  ‘You must be confused about the address.’ The man closed the door.

  Ramiro supposed it was possible that the apartment’s tenant had had no knowledge of the meeting, but he couldn’t think of any other way to attract the group’s attention. Perhaps they’d been monitoring the whole project independently and already knew what had happened to the occulter, but he couldn’t take that for granted and rely on them to intervene.

  Back in his apartment, he sat and waited for contact. Greta’s people might be watching him, but that had always been true; either Giacomo’s group had ways around that, or everything they’d done would have been spotted long ago.

  After six bells, Ramiro lost patience. He knew he’d have no hope of sleeping, so he went out hoping to be found.

  By most people’s schedules it was night-time, and the corridors were lit with nothing but red moss-light, but the precinct was as busy as he’d seen it. Ramiro passed dozens of restless neighbours, crowding the guide ropes, moving as briskly and aimlessly as he was. When he met their eyes they turned away, confused. In two days the mountain might be gone, and any sane person would want to play a part in protecting it. But after three years of complying with the flawless predictions of their own private messages – or their friends’ messages, or whatever impinged on their lives in the public news – what could they do when they’d been told that they’d do nothing?