The Arrows of Time

by Greg Egan

  Ramiro said, ‘All right.’

  He adjusted his grip on the rope, taking the opportunity to rest one arm for a lapse. He didn’t think it would be wise to try to mess with the cooling bag to let him extrude a fresh pair of limbs, but if fatigue really did start to threaten his hold he could try tying his corset’s photonic cable in a loop around the rope.

  As the gnats drew closer together, the centre of the rope dropped lower, nearer to the engines. Ramiro began climbing towards Tarquinia’s side, alarmed at how much harder it was to make progress with the rope at a steeper angle. Tarquinia poked her head out through the hatch, then reached down and began winding the rope in; Ramiro could see her straining to shift his weight, but she was doing much more than sparing him the effort of the climb. With the rope shortened the angle improved, and Tarquinia kept winding until it was nearly horizontal again.

  Then she disappeared back into the cabin, and the gnats moved closer still.

  Ramiro clung on, trying to ignore the revived throbbing of his foot. Everyone had imagined the rogue defending itself with antimatter, or elaborate software to deal with would-be intruders. But the measure that had actually defeated him might not even have been a deliberate strategy: in those last days at the Station, whoever had reprogrammed the navigation system might simply never have had an opportunity to restock the decommissioned gnat with cooling air. At this very moment, they might be fretting over the possibility that their weapon had overheated to the point where every photonic lattice had cracked and the rebounders’ mirrors had split into shards.

  Tarquinia turned the gnat so that its flat belly faced the rogue’s. Ramiro scrambled to keep himself away from both the engines below and the approaching slab of hot rock. As Tarquinia eased the gnats’ bases together he found himself suspended half a dozen strides below the hatch through which he’d left the cabin. With the side of his body resting against the polished grey stone of the hull, he could feel the surface growing warmer as heat spread into it from the rogue. But before he could panic, he registered a quickening flow of air from the cooling channels. Tarquinia’s gnat was built to run at three times its current power; the extra burden would not overwhelm it.

  ‘How long to the impact?’ Ramiro asked.

  ‘A chime and a half,’ Tarquinia replied evenly. ‘I’m going to start applying force now; this might get rough, but don’t let it shake you.’

  ‘I’ll do my best.’

  Ramiro hugged the rope. The immediate effect of Tarquinia’s shoving was imperceptible, but it wouldn’t take long before the rogue sensed itself drifting off course – and no tampering by the saboteurs was needed to ensure a response. The navigation system would adjust the power in the individual rebounders, skewing the direction of the main engines’ thrust to try to compensate for the deviation.

  Above, still, there was nothing but stars. How hard could it be to miss a target too small to discern? Ramiro flinched suddenly, his teeth aching with a hideous vibration. It was over in an instant, but his skull kept ringing. One gnat must have suffered a brief drop in thrust, scraping hull against hull.

  He steadied himself and tightened his grip. He still had no real sense of motion; if he closed his eyes, he might have been clinging to the side of a wall back in the Peerless, somewhere out near the rim. But now that Tarquinia had gone beyond simply matching the rogue’s trajectory, there could be no more placid mimicry: the instruments that were detecting her provocations were not so perfect and standardised that their response could be predicted and allowed for in advance. The rogue wasn’t even trying to shake them off – with the proximity sensors dead, it thought it was moving untrammelled through the void, in battle with nothing but its own errors.

  Ramiro cried out in shock before he knew why: the hulls were moving apart. Tarquinia said, ‘I’ve got it, I’ve got it!’ The gap began to shrink, then the surfaces made contact again with an ugly grinding sound.

  Ramiro was shivering. If the gnats separated and the rope snapped on the wrong side, he needed to be ready to release his hold to stop his body being slammed against the overheated hull. Better to end up dashed against the walls of the Station than be flayed by heat from head to toe.

  He looked down at his ruined foot. It had grown numb again, but the luminous discharge was unabated. In all the years since the launch, only three people had gone to light in the Peerless; Ramiro had never paid much attention to the accounts he’d read of the phenomenon, other than fixing in his mind the importance of fleeing if he ever saw a glowing liquid seeping from someone else’s wound. All he could do was wait for the manoeuvre to be finished so Tarquinia could bring him a knife. He looked to the zenith and finally spotted a tiny pale oval against the star trails.

  ‘How’s our course?’ he asked. They’d pushed gently against the rogue – not gently enough to remain unopposed, but there had to be some small chance that the net result had ended up in their favour.

  ‘Not good,’ Tarquinia admitted. ‘We’re still aimed at the Station.’

  Ramiro tried to accept the news calmly. ‘What more can you do? Give me a couple of lapses with a knife, then we can fly away.’ He could still survive this: he just had to cut through the rope on the rogue’s side before starting work on his leg.

  Tarquinia said, ‘I’m going to unbalance the main engines.’

  Ramiro’s shivering grew worse. ‘Manually?’

  ‘Yes,’ she confirmed.

  The manoeuvring engines delivered a modest push that any trained pilot could use manually, for docking. Severing the main engines from the feedback loop of accelerometers and gyroscopes that aimed to keep their thrust perfectly symmetrical, and then imposing a deliberate asymmetry to try to push their neighbour off course, would escalate the speed and violence of the interaction between the gnats by an order of magnitude. Tarquinia had the stronger engines – but the gnats could easily smash each other into rubble without anyone winning.

  Ramiro said, ‘Automate it.’

  ‘We have eight lapses to impact, Ramiro. We don’t have time to rewrite the navigation system.’

  ‘What I’m thinking of would take a very small change.’

  ‘We don’t have time!’ Tarquinia repeated.

  Ramiro struggled to find the words to sway her. ‘Do you trust what I did for the Peerless? Most of the tricks I used there were things I learnt from the woman who programmed the gnats. I know their navigation software backwards – and I’ve been revisiting it in my head from the moment Greta sent me out here.’

  ‘You don’t think I can do this myself?’

  ‘I’d trust my life to you as a pilot,’ Ramiro promised her, ‘but no one has the reaction time they’d need to make this work. All we have to do is poke a skewed target value into one register, and instead of disabling all the guidance sensors we’ll have enlisted them: we’ll force them to deliver a measured push, whatever the rogue does, no more and no less. Everything you usually rely on to keep you flying straight will be working towards this new goal. Can you really do better than that by gut alone?’

  In the silence, Ramiro glanced up at the Object. It still looked absurdly small, but in another few lapses he’d see how big a target it made. Tarquinia seemed paralysed with indecision; if he let himself drop now he could take his chances with his air tank, while hoping that she came to her senses and simply flew away from the rogue in time.

  Tarquinia said, ‘How do we do this?’

  Ramiro was confused. ‘Do what?’ Settle the argument before they were dead?

  ‘How do we automate the push?’ she asked impatiently. She’d accepted his plan.

  Ramiro described the commands for the navigation system, raising the glyphs on his own skin as he spoke, picturing them repeated on Tarquinia’s body under her own corset’s empowering gaze.

  As Tarquinia echoed the last command back to him, the opposing hulls began to screech and shudder. The shaking cost Ramiro’s good foot its grip on the rope; the other one fell back against the hull. He barely
felt the knock, but when he looked down there was a swarm of brilliant yellow specks dropping away into the void, endlessly replenished from his disintegrating flesh. The balance of energies that tamed his body’s chemistry was coming to an end; the damaged tissue was making ever more light, wrecking all the finely honed systems that had held the process in check. His only chance to survive would be to part from it, but in this juddering chaos he doubted he could take a knife from Tarquinia’s hand, let alone use it.

  The rogue shifted suddenly, its hull scraping backwards like a boulder sliding down an incline. Ramiro watched the slack part of the rope stretching out below him and readied himself for the void – but then the motion stopped abruptly.

  He understood what was happening: as the rogue fought to stay true – with no extra power to spend on the task – it could only shift its balance by throttling some of its rebounders, decreasing its forward thrust. Tarquinia was doing her best to fall back alongside their neighbour – and at least his clumsy fix had spared her from having to micromanage the sideways shove at the same time – but the whole encounter was too complicated to be rendered truly stable, and their luck couldn’t last much longer.

  Ramiro placed his injured leg against the rope and managed to work a full turn around it. But the loop was too low, barely above his ankle. He brought his hands down a span to lower his body while kicking out with his leg, until the rope rode up to encircle his knee. He made a second loop, then a third.

  He looked up to see the Object looming ahead, its red and grey rock mottled with craters and crevices limned with shadows in the starlight. Then in the foreground, far smaller for an instant but growing in no time to obscure the whole asteroid, he saw the Station: a cluster of stone boxes, rooms and workshops pieced together in weightless anarchy, rushing forward greedily towards the duelling gnats.

  Instinctively, Ramiro released his hold on the rope, convinced for a moment that this would save him. He fell upside down, hanging by his knee, his face to the sky as a featureless shadow flickered across the stars and was gone.

  He braced himself for the second, greater threat: a cratered landscape of antimatter rushing past near enough to touch – or rising up to meet him in extinction. The vision of it hung in his mind’s eye, stark and terrible. But the thing itself failed to appear.

  Ramiro lacked the strength to right his body but he raised his head sufficiently to stare up at the zenith. There was nothing ahead of the gnats now but the long, gaudy star trails of the home cluster. The shadow he’d mistaken for the Station passing by had been the Object; the first missed target had come and gone too rapidly to be perceived at all.

  He was still chirping with elation at the near miss when he noticed the yellow sparks falling around him. His whole lower leg was radiant now, filled to bursting with light.

  ‘Pull away!’ he begged Tarquinia.

  He saw her helmet poke out of the hatch.

  ‘Wait,’ she said. She was gone for a moment but then she reappeared with the safety harness.

  ‘There isn’t time!’ Ramiro protested. But he understood why she was taking the risk: if he ended up falling alongside his amputated leg, it could still kill him.

  Tarquinia dropped the harness. Ramiro reached out to accept it, but the rope wasn’t long enough; the harness hung suspended beside his bad knee. He tried to raise his torso, but the effort merely set him swaying.

  ‘Grab it with your other foot,’ Tarquinia urged him.

  Ramiro tried, but some earlier knock against the hardstone must have damaged his foot, robbing it of its power to grip. He poked it between two of the harness’s straps, pushed his leg through and bent his knee.

  ‘Now!’ he pleaded redundantly: the gnats were already separating. He could see starlight between the hulls.

  As Tarquinia retreated into the cabin, Ramiro felt the rope tightening, until he lost all sensation in the constricted flesh. Viscid yellow fire sprayed from the stump of his foot. The glow became too painful to watch; he threw his arms up in front of his helmet.

  Suddenly all his weight shifted to his good knee, almost pulling him free from the harness. The light from above was gone; Ramiro lowered his rear gaze and saw his severed leg tumbling through the void, part of the snapped boarding rope beside it. As he watched, the flesh liquefied completely then swelled into a ball of flame, lifting the rogue’s form out of the darkness. A moment later he felt a faint gust of warmth penetrate his cooling bag, then a single sharp sting to his shoulder. He groped at the wound with a gloved hand; it was painful to touch, but any break in the skin was too small to discern. Maybe he’d been hit by a fragment of bone.

  When the fireball had faded, Tarquinia shut off her engines. The rogue shot forward, passing the gnat, making no attempt to recover from its failure. But even if this was a ruse – and even if the rogue didn’t overheat and shatter from a lack of cooling air – it would need eleven bells just to slow and come back, and twice that to make a fresh stab at the original plan. That left time for half a dozen more gnats to come from the Peerless and start towing the Station away.

  Weightless, Ramiro reached up and took the safety harness in his hands. He clung to it for a while, too weak to go any further, then Tarquinia began drawing the rope back into the cabin.

  4

  ‘Happy Ancestors’ Day!’ Agata greeted her mother. ‘Are you coming to the celebration?’

  Cira regarded her with undisguised pity. ‘I came here to ask if you’d visit your brother with me.’

  Agata dropped clear of the doorway to allow Cira to clamber down the entrance ladder. ‘Mind the bookcase.’ A year and a half into the deceleration, Agata had kept the changes to her apartment messy and proudly provisional. ‘Why would I want to see Pio?’

  ‘Common decency.’

  Agata felt a twinge of guilt, but she remained unpersuaded. ‘All we ever did when he was free was argue, so I doubt he spends his time now yearning for my company.’

  ‘You need to mend things with your brother,’ Cira insisted. ‘If you think Medoro’s going to do Pio’s job for you, his sister might have another opinion.’

  Agata grimaced. ‘Medoro’s a friend! Is there anything going on in your head that isn’t about reproductive strategies?’

  ‘Someone has to think about these things.’ Cira peered suspiciously at Agata’s console, as if the images of phase-space flows on display might reveal the true source of her daughter’s intransigence. ‘If you value your work, you should value your brother.’

  ‘Really?’

  ‘Why do you think I had a son at all? It was for your benefit, not mine.’

  Agata was chilled. ‘Whatever my differences with Pio, at least I don’t think of him as some kind of useful machine.’

  ‘You can take all the holin you like, and it will never give you certainty,’ Cira said bluntly. ‘But no woman who’s shed a child has ever divided afterwards. If you try to raise a child on your own, it will cost you years away from your research. This is what men are for. Argue politics with Pio as much as you like, but to alienate him completely would be self-defeating.’

  Agata said, ‘He tried to stop the turnaround. It’s gone beyond arguing politics.’

  Cira spread her hands in a gesture of agnosticism. ‘There was no evidence connecting him to that. And I would have thought you’d be troubled by this whole notion of “preventative detention”.’

  In truth, Agata was divided. That the Council had empowered itself to imprison people without trial disturbed her, but she’d almost convinced herself that the Peerless’s vulnerable transition state justified the move. Pio and the other migrationist leaders were being treated well enough; three years in comfortable accommodation, free to read and study, wasn’t exactly torture.

  ‘If you won’t visit him, you can still do right by him,’ Cira suggested.

  ‘What do you mean?’

  ‘If you had a child, I don’t believe they’d keep her from her uncle.’

  Agata was appalled. ‘
Now you want my daughter to be raised in prison?’

  ‘Only for a couple of stints,’ Cira assured her. ‘After that, we’d have grounds to ask for his early release. If he’s looking after a child, what harm can he do? They can still monitor him, but it would be absurd to keep him locked up.’

  Agata’s head was throbbing. ‘You’re unbelievable!’

  ‘Do this for him now,’ Cira replied, ‘and he’s sure to be so grateful that he’ll happily raise a son as well. Then the next generation will be complete. You owe that to your daughter: to give her the opportunities I gave you.’

  Agata said, ‘I’m going to the party. You’re welcome to join me—’

  ‘To commune with the ancestors?’ Cira hummed contemptuously.

  ‘To remember what we’re here for,’ Agata countered.

  Cira said, ‘We’re here to survive, and to strengthen our position.’

  ‘You mean manipulate each other, and preserve the status quo?’

  ‘Your grandmother lived under the old rules,’ Cira reminded her. ‘Starving wasn’t an eccentric choice then; it was forced on every woman in the mountain. If you’d listened to her more, you might not be so complacent.’

  Agata said, ‘If you’re so terrified of the old ways returning, why did you have a son at all? You got by without a brother. Why not wipe out your enemy completely and be done with it?’

  ‘Far better to keep them alive and weak,’ Cira replied, ‘than to turn against ourselves and reduce some women to playing the role of men.’

  Agata arrived at the celebration later than she’d intended. It was easy enough to make allowances for the time it took to climb the rope ladders between the levels she frequented day to day, but when a journey took her up or down the old helical staircases she found it impossible not to dawdle. For six generations these elaborately carved grooves had been nothing more than peculiar decorations wrapping the walls of horizontal tunnels, but to traverse them now meant treading on stone that had last been used this way when Yalda was alive. If Agata spotted a blemish in the rock she had to stop and inspect it in the moss-light, hoping that someone who had walked on the home world – famous or obscure, she didn’t care – might have carved their name into these steps.