The Arrows of Time

By touch, Agata confirmed what she’d guessed by sight when the grille had been illuminated: the bars really were embedded in the wall, continuing right into the surrounding stone. The masons must have drilled one hole straight, but created a whole triangular cavity at the opposite point, allowing a rod that was too long to fit directly across the tunnel to be inserted at an angle and then made true. They would have packed the cavity with sand and adhesive, and over time it would have set into something almost as strong as the surrounding calmstone. But though the bars themselves were close to unbreakable, calmstone was just calmstone. Agata put the point of her hand drill against the wall beside the longest of the bars and set to work enlarging the hole that contained it.

By the end of her shift she’d made slots that allowed her to remove and replace three of the bars at will. Two more, and she’d be able to squeeze through.

Agata packed up her tools and forced herself to swallow them again. Beyond the half-disassembled grille and the last segment of the tunnel, there’d be another grille just like it guarding the outlet from the chamber itself. She’d need more time to transit that segment, but the task no longer seemed impossible.

Agata ground the roots with the mortar and pestle she normally used for spices, feeling like some kind of demented kitchen alchemist. The flowers she’d cut up were all decorative species that had been planted around the beds of travellers for generations, in a relic of the old folk belief that their petals’ light had health-giving properties. She had never gone in for the custom herself, but at the garden no one had questioned her. The assistant had invited her to pick whatever she liked.

Every plant root contained substances that bound to a range of minerals. Over the generations, chemists had painstakingly tabulated their properties, species by species, and the appendices to Agata’s school chemistry textbooks were full of such quaint pre-photonic compendia.

The effect she was hoping for was not dramatic; she didn’t need a liberator to set the sunstone in the cooling chamber on fire. All she had to do was ‘poison’ a large enough portion of the surface of the rock. The size of the air particles that the sunstone produced was sensitive to the amount of time the decomposing agent spent in contact with it; if she could weaken the agent’s binding, some lighter air than normal would be produced. The total volume didn’t have to be enormous; the giant centrifuge of the Peerless itself would separate out the less massive component, concentrating it preferentially around the axis.

If she could get enough disruptor into the cooling chamber, the next step would be verification. She would need to be able to quantify the effect of her intervention on the refractive index of the air near the axis, not least to be able to convince Ramiro and Tarquinia to abandon their own efforts. The shift ought to be measurable in principle, but it would require specialised, high-precision instruments. Agata had no idea how she could get her hands on equipment like that without attracting attention – but she was sure that, like every other aspect of the plan, if she remained resolute it would fall into place.

‘You get keener every day,’ Celia observed. ‘I can move you to an earlier shift if you like.’

‘No, this is perfect.’ Agata wasn’t sure how much explanation her early starts required. ‘I just have trouble planning the journey sometimes; if I’m not as energetic it can take me a few more lapses to get here, but if there’s any doubt I’d rather make sure I won’t be late.’

‘Hmm.’ Celia didn’t care. ‘Any new thoughts about the disruption?’

‘I’m still optimistic,’ Agata replied cautiously.

‘You’ve seen the ancestors’ writing,’ Celia acknowledged. ‘Of course that makes you hopeful. But they didn’t tell you how many of us survive.’

‘But nor did they mention a great tragedy,’ Agata replied. ‘They just offered their thanks. If the mountain had been shattered, you’d think they would have aimed for a higher level of solemnity.’

Celia was amused. ‘Six generations on? It will all be ancient history by then. They’ll carve their memorial on Esilio and some politician will make an empty speech.’ She handed Agata her tool belt and access key. ‘No one will know what our lives were really like, and no one will care.’

Agata said, ‘Perhaps.’

Agata forced herself to complete a full sweep of the tunnel, burning off every visible speck of moss. But as she raced back towards the site of her real work, when she noticed one faint red smudge that she’d missed she did not stop to pull her coherer from her belt.