Greg Egan - The Arrows of Time

‘They’re not going to give up, any more than we are,’ Agata replied. ‘Do you see any sign in what we’ve heard from the mountain that the Council have resigned themselves to a state of fatalistic powerlessness?’

‘No,’ Azelio conceded.

‘Think of it as a kind of equilibrium,’ Tarquinia suggested. ‘I’m sure there are limits to how far the Council would go to try to stop the inevitable, but there must be limits, too, on how supine they’ll become: they’re not going to shut down the system themselves, or release all the anti-messagers and let them go on a rampage with mallets. They’ve taken a stance and they’re going to pursue it as far as they can. When this is over they’ll be looking for a political advantage in the details of the fight, as much as in the outcome.’

Azelio was looking disoriented. ‘I want this to work,’ he said haltingly. ‘But every time I stop and think about it, it feels as if all we’re doing is playing some kind of game. Shouldn’t we be trying to build better meteor detectors? If we really are the only people left with any hope of innovating, why not design a device that could actually save the mountain – instead of one for faking its death?’

Agata said, ‘If we saved the mountain from a meteor, don’t you think we’d know about it?’

‘I have no idea.’ Azelio rose from his seat. ‘But what we’re doing now is pointless.’ He walked out of the cabin.

In the silence, Ramiro felt his own confidence faltering. ‘I don’t know how to reason about this any more,’ he said. ‘If it’s a meteor that could actually kill us, isn’t that where our efforts should go? Forget what the messages say or don’t say about it: if we do our best to build something useful, how can that fail to make a difference?’

Agata inclined her head, expressing some sympathy with the impulse. But she wasn’t swayed. ‘I was the one who tried to argue that there’s no such thing as an undetectable meteor – but what do we have on board for tackling that problem? A single time-reversed camera, and no facilities for building new photonic chips or any kind of high-precision optics. Even if we came up with a glorious new design, how are we supposed to manufacture a whole network of surveillance cameras and get them deployed? They can’t just be drifting around the mountain detecting hazards for their own amusement – if they find something, they have to be able to trigger either a coherer powerful enough to deflect the thing, or start up the engines and make the whole mountain swerve. Do you really think we’d be able to do that in secret?’

‘Maybe the Council will finally exercise enough discipline to keep it all quiet,’ Ramiro replied.

‘If they’re capable of that,’ Agata countered, ‘then they’re capable of doing a vastly better job than we are with the entire project.’

Ramiro gave up. He desperately wanted everything to work in the old way, when he could wrap his mind around a self-contained problem and take it apart without having to think about the entire history and politics of the mountain. But wishing for those days wasn’t going to bring them back. ‘Then we should go ahead with the star-occulters for our hypothetical saboteurs,’ he said. ‘Find a way to build them, and a way to keep them secret, and then hope that the cosmos takes us up on the offer to explain away the disruption with one simple, harmless conspiracy.’

Agata took hold of one end of the slab of calmstone, Ramiro the other, then they lifted it onto their shoulders and stood facing each other, some four strides apart.

‘Are you ready?’ Tarquinia asked.

‘I’m not sure how steady this will be,’ Agata replied.

‘That doesn’t matter. I just want you to be able to keep your grip when there’s a force applied from below.’

Agata put a second hand on the slab. ‘All right. Go ahead.’ The improvised test rig looked alarmingly amateurish, but the ceiling of the cabin was made of the wrong material, and in any case they didn’t want to leave it covered with incriminating marks. They’d hunted through the storeroom for something to serve as a trestle, but there’d been nothing ready-made, so in the end their bodies had seemed like the most expeditious substitute.

Tarquinia pushed a button on the remote control and the occulter rose from the floor. The core of the tiny craft was a dodecahedron about a span wide, with air nozzles fixed in the centres of eleven of its pentagonal faces. Attached to the top, twelfth face was a linear assembly, a pair of arms three or four spans long, as densely packed with gears and linkages as anything from the age of clockwork.

Staying low, the occulter steered its way across the cabin until it was hovering in front of Agata’s feet; she could feel the spill of air against her skin. Then it ascended smoothly until it made contact with the calmstone slab – surrogate for the slopes of the Peerless itself. She gripped the slab tightly as four burred tips drilled obliquely into the stone. As Tarquinia had promised, the net force was purely vertical, so the weight of the slab bore most of it, and with the drills counter-rotating in matched pairs Agata felt no torque trying to twist the slab sideways.

After a few lapses the drills fell silent and the air jets cut off, leaving the device hanging.

‘Try to shake it loose,’ Tarquinia suggested. Ramiro ignored the invitation, but Agata slid her end gently from side to side, and when this had no effect she grew bolder and began rocking the slab back and forth. The linkage rattled alarmingly, but the four splayed drill bits remained lodged in place.

‘That’s reassuring, isn’t it?’ she said. ‘The mountain is hardly going to sway like that.’

Ramiro wasn’t so impressed. ‘It doesn’t tell us much about the real hazards. If there’s a hole under the surface, or a powderstone inclusion—’

‘If it comes loose that’s not the end of the world,’ Tarquinia stressed. ‘It can always fly back and reattach itself.’

Agata said, ‘Try the walking mode.’

Tarquinia tapped the remote. The four bits remained fixed in the stone, but the plate on which the drills were mounted began rotating on the end of its arm – or rather, the arm began rotating around the plate, swinging the entire occulter forward, carrying it from Agata’s end of the slab towards Ramiro’s.

When this repositioning was complete, the four drills at the end of the second arm pushed up against the stone and began biting into it. The new quartet managed to gain purchase with only the first set bracing them; there was no need to start up the air jets again. Then the first four went into reverse and disengaged from the stone, and the whole process began to repeat itself.

Agata watched anxiously as the machine whirred and clanked its way down the slope from her shoulder to Ramiro’s. If the slab was unrealistically smooth, at least they’d made sure that it wasn’t gravitationally level.

When the occulter had come within a span of Ramiro’s body, Tarquinia used the remote again. The craft freed itself from the slab and flew away to alight on the cabin floor. Ramiro looked to Agata, and they carefully put the slab down together.

‘Not bad,’ Tarquinia declared.

Ramiro said, ‘No. But we still need to decide what happens when the surface is uneven.’

Tarquinia had already reached her position on that. ‘It should detour around the problem if it can, or drop away and fly past it if it can’t. That makes it purely a question of navigation.’

‘And a question of air,’ Ramiro corrected her.

‘Whatever we do,’ Tarquinia replied, ‘there’ll always be a chance of the air running out. Letting the arms tilt so they can conform to the surface won’t guarantee anything – and it’s one more joint that can jam, two more actuators that can leak, plus six more sensors to make the idea work at all.’