Greg Egan - The Arrows of Time

‘A dozen and a half,’ Giacomo corrected him. ‘Including spares. In the end it was just a matter of stealth and patience. Everything was based on pre-existing designs; it’s only the delivery mechanism that would have been beyond us.’

Ramiro said, ‘Tell me about the bombs.’

‘They’ll do the job,’ Giacomo promised him.

‘I don’t doubt that. But what’s the size of each charge? The blast radius?’

‘In vacuum, they’ll fracture clearstone within six strides of the detonation point.’

‘That’s all?’

‘That’s enough,’ Giacomo insisted. ‘Once the light collector’s damaged, the channel will be dead.’

‘And do you know how well protected the internal light path is?’

Giacomo said, ‘There are three clearstone seals below the collector: at four strides deep, eight strides, and one stretch. Once you go past those three seals, the main tube itself is continuous – they don’t put anything between the mirrors, because that would cut into the light with every bounce. But there’s no chance of us breaching the tubes: the first seal alone will take most of the energy out of the blast.’

‘You’re certain of that?’ Ramiro wished Agata hadn’t given up on the plan before she’d heard these details.

‘That’s what the explosives experts tell me,’ Giacomo replied carefully. ‘Running a test on a mock-up would have been the best way to answer that, but there’s a limit to what we can slip past surveillance.’

Three seals, with the last at double the blast radius . The saboteurs had no need to damage anything so deep. And even if something went awry in the delivery, that would lead to less harm to these structures, not more.

‘What about the defences?’ Ramiro asked. ‘They won’t have left the collectors sitting there unguarded.’

‘All the original defences at the base were designed to protect the engines from micrometeors – arriving from out of the void at high speed without changing course.’ Giacomo spread his arms. ‘We believe they’ve tried to improve the system since they learnt about the disruption, but anything coming in low above the rocks and moving unpredictably will be a completely different kind of target.’

‘So we have a chance.’ Ramiro was beginning to feel optimistic.

‘I believe so.’ Giacomo had had three years to mull over the same facts; if there was no thrill of delight in his verdict, at least he’d earned the right to issue it.

‘This next request is a little delicate,’ Ramiro admitted. ‘Though I don’t suppose it will shock you.’

‘Go ahead.’

‘I’ll need to talk everything over with Tarquinia,’ he said, ‘but even if she agrees, we’ll have one more proviso: we’ll want to hold onto the codes for the occulters ourselves. You provide the coordinates, we operate the devices.’

‘I understand.’ Giacomo was completely unperturbed.

Ramiro understood that his collaborator could hardly need more time to weigh up the proposal, but he was still taken aback by this placid response. ‘Agata is hoping to find a safer way to cause the disruption,’ he said. It felt incumbent on him to provide a full justification for Giacomo’s ease; he couldn’t drop the discussion just because they’d agreed. ‘I don’t know what her chances are, but this way it will be clear that we can still change the plan at the last moment if she comes up with something better.’

Giacomo said, ‘We’ve always known that that was part of the deal, and we have no problem with it at all.’ He reached across from his rope and clasped Ramiro’s shoulder. ‘To the end of the system, brother.’

‘To the end of the system,’ Ramiro echoed. This strangely dispassionate rebel could not have achieved much without his own knowledge of the future. But then nothing could have been more apt than their enemies’ machine enabling its own destruction.

‘Why do I feel that I have no choice in this?’ Tarquinia complained.

‘Because everything feels that way,’ Ramiro replied. ‘Just ignore it and do what you want.’

She slid away from him beneath the tarpaulin of his sand bed, a silhouette against the red moss-light coming through the fabric from the wall behind her. ‘The codes remain in our hands to the end,’ she said. ‘What is there I could possibly object to?’ She made this sound like a bad thing.

‘It’s strange being trusted by strangers,’ Ramiro conceded. ‘But they know we won’t betray them for at least the next four stints, and we know we won’t have any reason to regret the deal ourselves or we would have sent back a warning. This is what life is like without surprises. I wouldn’t want it to last for ever, but at a time like this I can’t honestly claim a need for even more uncertainty.’

Tarquinia said, ‘What I’m afraid of is being certain, without being right.’

‘About what, exactly?’ he pressed her.

‘If I knew that there wouldn’t be a problem.’

Ramiro drew the tarpaulin away from his face and looked out across the room. ‘What’s the worst that can happen – short of a meteor strike? Vincenzo’s right and it’s all a set-up. Giacomo is secretly working for the Council. We’ll end up in prison, but with a clear conscience: nothing we were planning would have harmed anyone, while the Councillors lied to the whole mountain for years. Come the next election we’ll probably be pardoned, and the system will never be turned on again. Does any of that sound so bad to you?’

‘No.’ Tarquinia shifted uneasily.

‘So… ?’

‘We’ll go ahead,’ she said. ‘Nothing else makes sense. Maybe I’m just not accustomed to things slotting into place so perfectly. It used to be that anyone who knew from the start what to say to win you over was setting an ambush. These days, maybe all it proves is that they bother to read their messages.’

Giacomo handed over the data link, a shiny black slab of photonics about five scants across.

Ramiro inspected it. ‘That’s perfect,’ he said. He’d had no hope of getting hold of anything like this himself. ‘How do you get past the inventory checks?’

‘You can swap an inert mock-up for the real thing,’ Giacomo explained. ‘If you do it the right way no one will notice for years.’

Ramiro formed a pocket and hid the link. ‘Do you have the coordinates for me?’

‘Yes, but we should get the other business out of the way first.’ Giacomo paused expectantly.

‘Of course.’ Ramiro had sat down with Tarquinia for a bell the night before, refining the sketches from memory. They’d kept no records of the occulters’ design on paper or in photonics, and not merely to avoid discovery; they hadn’t actually anticipated any need for it.

He summoned the final drawing onto the skin of his chest, with all the details and dimensions that Giacomo had requested. The explosives caches would need to have been carefully designed if they were to grab the occulters and ride them – without jamming the mechanism or fatally unbalancing their hosts. Still, Ramiro’s first impulse when asked for the plans had been to challenge his accomplice, jokingly, to display them first. But the information would still need to pass between them in the conventional direction at some point, and Ramiro hadn’t really wished to be confronted with an unarguable proof that he would agree to the transaction eventually.

Giacomo dragged himself closer along the guide rope. ‘Do you mind if we do this by touch? My visual memory isn’t so strong, and cameras are a security risk.’

‘All right.’ Ramiro hadn’t been expecting this, but he had no reason to object. He moved forward and let Giacomo embrace him, and as their skin made contact the gentle pressure rendered the ridges of the drawing palpable to both of them.