Greg Egan - The Arrows of Time

‘What happened?’ he asked her.

‘Nothing,’ she said. ‘Nothing’s wrong.’

‘No.’ He had no children to lose. How many times had he told his idiot body the same beautiful lie? How stupid could it be, that it hadn’t seen through him yet?

He looked past Tarquinia, to the pale grey wall of his cabin. He knew exactly where he was now. The Surveyor was his second prison, and outside it was the third. ‘How will anyone live here?’ he wondered.

‘There’ll be a better place than this for a city,’ Tarquinia promised. ‘No dust storms – just gentle winds to sweep the footprints away.’

‘That’s not enough.’

‘Then you’ll build machines to plant the wheat and harvest it. No one will ever have to touch the soil.’

Ramiro turned to her. ‘Who’ll build these machines?’

‘You will. You and the other settlers.’

‘And where will you be?’

Tarquinia said, ‘I thought you didn’t want to know the future.’

Agata pressed the broom down firmly against the floor of her cabin and tried again. ‘How hard can it be?’ she muttered. Dust starts off in a large area. Pressure is applied inwards along successive portions of the border. Dust ends up in a smaller area, ready to be collected and removed. On the face of it, this didn’t even pose a conflict with the local arrow: Esilian dust should have been happy to have its entropy decreased as her own time advanced.

But as she moved the broom across the floor, duly concentrating the dust ahead of it, other dust began to appear behind it – some of it falling from the air, some sliding over the stone to pile up against the bristles. Its entropy was decreasing too, as it accumulated from whatever scattered reaches of the Surveyor in which it had been lurking. The net result was that the stretch of floor she’d swept remained as dusty as ever.

Azelio knocked on her open door. ‘I know you’re busy, but Ramiro’s sleeping and Tarquinia’s on watch—’

‘I’m not busy,’ Agata assured him. ‘Do you want a hand with the measurements?’

‘If you don’t mind.’ Azelio nodded at the broom. ‘Have you found the trick to it?’

‘Not really,’ she admitted. ‘Maybe what we need is some kind of covered system of barriers. If we can place it on the floor and then reconfigure it without opening the cover, we ought to able to manipulate the dust inside without any more arriving.’

‘That sounds… elaborate.’

Agata put on her corset and tool belt and followed Azelio to the airlock, then waited for him to cycle through. The view through the window showed that the weather was calm, but the Surveyor had become so filthy that Tarquinia now insisted on the protocol, regardless. Agata was beginning to suspect that the only remedy for the dust invasion would be to ascend into the void and flush every room out with clean air – and even that depended on their arrow prevailing and the void not being ready with a conspiracy of pollutants poised to rush in the moment they opened the airlock, in a perfect reversal of the intended purge.

Outside, she caught up with Azelio at the start of the trail. It was Ramiro who’d noticed the regularly spaced indentations in the ground after the last high winds, and decided to fill them with rocks marking the way to each of the four test plots. Agata hadn’t questioned him too closely on the matter, but she suspected that he’d already been contemplating doing something similar. The idea hadn’t come from nowhere, inspired by nothing but the evidence of its own implementation.

‘How are the calculations going?’ Azelio asked her, as they started along the trail.

‘Slowly.’

‘Just as well. If you finish them, what will you do on the journey back?’

‘There’s no risk of that.’ Agata had set aside her efforts to understand the curved vacuum and instead had spent the last two stints attempting to analyse their current situation, using a crude model of a field in which two opposing thermodynamic arrows met. But in the versions that were simple enough to handle, both arrows rapidly decayed away, leading almost immediately to a time-blind equilibrium state. The reality, in which countless slender fingers of opposing time interpenetrated, seemed to depend on details too subtle for her to approximate in any meaningful way.

‘It’s Luisa’s fifth birthday today,’ Azelio announced cheerfully. ‘I’ll show you her drawing for it when we get back.’

‘Happy birthday, Luisa!’ Agata played her coherer’s beam over the grey stones to her left. ‘You never peek, do you? You never riffle through the pile to see what’s coming up?’

Azelio buzzed. ‘Of course not! That would defeat the whole point.’

‘I know. But that wouldn’t be enough to stop me.’

When they reached the first plot the plants were all dormant, their flowers closed. Agata glanced up at the sky; she knew from the positions of the stars that the sun was well above the horizon, but she would have had to forego artificial light for a few lapses to have any chance of picking out the faint disc. ‘I was hoping the petals might synchronise to the Esilian day,’ she said. ‘They give out photons, the sun accepts them: what could be more sensible than that?’

‘Except that eons of evolution has left them with no skill but waiting for an ordinary night, not a time-reversed day.’

‘Maybe the settlers could breed it into them,’ Agata suggested. If detecting the dawn for themselves was too hard, the plants could still be prodded with more conventional signals into following the new cycle. For now, the Esilian sun would be getting its due regardless – from the plants, the ground, and her own skin – but not in any useful way.

‘Can you do the heights and the stalk circumferences?’ Azelio asked her.

‘Sure.’ Agata knelt by the first plant and reached into her tool belt. In a perfect world some clever instrument builder would have added a data recorder directly to the tape measure, but instead she had to aim her coherer so that she could read the tape by eye, raise the figure on her skin, and have her corset record it. ‘Is one soil type racing ahead yet?’ she asked Azelio. He’d started from the other end of the row, making his own inspection to record the number and condition of the flowers.

‘No.’

‘So there’s not much difference? The settlers could farm anywhere?’

Azelio was silent. Agata regretted distracting him; she’d probably made him lose count.

As he stood to move on to the next plant, he said, ‘Actually, they’ve all stopped growing.’

Agata was startled; nothing in Azelio’s demeanour had prepared her for this news. ‘All of them? Every single one?’

‘Yes.’ Azelio spoke calmly. ‘At first it was only a few cases, and I put it down to transplantation shock. But the numbers just kept getting worse, and three days ago the last exceptions succumbed.’

Agata struggled to find the least dismaying interpretation of these facts. ‘Do you think it’s the wind?’ They could always improve the windbreaks, or even relocate the whole experiment.

‘No. They haven’t lost that many petals, or had roots dislodged.’

‘So it’s the soil,’ she concluded. ‘All four kinds are inhospitable.’

‘It’s looking that way.’

‘Have you told Ramiro?’

‘The trial isn’t finished yet,’ Azelio stressed. ‘There’s still a chance that this could be a temporary hiatus.’

‘Right.’ Agata understood now why he’d called on her to help him with the measurements: he was trying to keep the results from Ramiro for as long as possible, in the hope that something would change.

Azelio knelt down and continued his inspection; Agata did the same. As she turned the revelation over in her mind, she was surprised at her own equanimity. After six years away from the mountain the conflict that they’d come here to remedy seemed remote and petty. If they really could rid the Peerless of Medoro’s killers by showing that a settlement was viable, she’d certainly relish that victory – but between the light-deflection measurements and her work on the vacuum, she already found it impossible to think of her time here as wasted.