On a heap of shattered stones a small child was sitting on the lap of an older girl, playing with a bit of melted glass. The girl was the infant’s cadre sister, Luru supposed. They both had hair, thick dark thatches of it. The little one looked up, coughing, as they passed.

‘This isn’t a healthy place,’ Luru observed.

‘What did you expect? But I keep forgetting. You expect nothing; you know nothing. Luru, people die young in places like this. How else do you think I became so senior here so quickly? And yet they still come. I came.’

‘Perhaps you were seduced by the closeness of the cadres here.’ A healthy dissolution might restore the social balance here, she thought.

He stared at her. ‘There are no cadres here. The cadres, dissolved every couple of years, are another Qax social invention, imposed on humans after the Rebellion for the purposes of control. Didn’t you even know that? Luru, these are families.’

He had to explain what that meant. And that the girl who nursed the child was not the little one’s cadre sibling, but her mother.

They reached a door that had been crudely cut in the wall of the Qax facility. They passed through into an immense curving chamber where vast engines crouched. Hovering light globes cast long, complex shadows, and human technicians talked softly, dwarfed to insignificance. There was a smell of burned lubricant, of ozone.

Luru was overwhelmed.

Symat said, ‘This place was thrown up by the Qax after the Rebellion. It was one of hundreds around the planet. We think it was a factory for making exotic matter - that is, matter with a negative energy density. They abandoned the place; we don’t know why. Since it was built with human wealth and labour I suppose it means nothing to them. We refurbished the machinery, rebuilt much of it. Now we use it to make our own superheavy nuclei, by bombarding lumps of plutonium with high-energy calcium ions.’

That puzzled her. He’d said his goal was the detection of superheavy elements in Earth’s crust. So why was he manufacturing them?

‘Why were the Qax making exotic matter?’

‘None of us knows for sure,’ he said. ‘There is a rumour that the Qax were trying to build a tunnel to the future. It’s even said that the Qax Governor itself is an immigrant from the future, where humanity is triumphant. And that is why the Qax work so hard to control us. Because they are frightened of us.’

‘That’s just a legend.’

‘Is it? Perhaps with time all history becomes legend.’

‘This is nonsense, Symat!’

‘How do you know, Luru?’

‘There are witnesses to the past. The pharaohs.’