But this was no longer a world of antiquity and stillness. The shudders were coming every few minutes now. In places the ice crust was collapsing, ancient features subsiding, here and there sending up sprays of dust and ice splinters that sparkled briefly before falling back, all in utter silence.

Hama thought back to a time before this assignment, to the convocations he had joined, the earnest talk of political futures and ethical settlements. He had been a foolish boy, he thought, his ideas half-formed. Now, when he looked into his heart, he saw crystal-hard determination. In an implacably hostile universe humanity must survive, whatever the cost.

‘No more pharaohs,’ Hama murmured. ‘No more immortality. That way lies selfishness and arrogance and compromise and introversion and surrender. A brief life burns brightly - that is the way.’

Nomi growled, ‘Even now you’re theorising, Hama? Let’s count the ways we might die, standing right here. The Xeelee starbreaker might cream us. One of these miniature quakes might erupt right under us. Or maybe we’ll last long enough to suffocate in our own farts, stuck inside these damn suits. What do you think? I don’t know why you let that arrogant pharaoh kill himself.’

Hama murmured, ‘You see death as an escape?’

‘If it’s easy, if it’s under your control - yes.’

‘Reth did escape,’ Hama said. ‘But I don’t think it was into death.’

‘You believed all that stuff about theoretical worlds?’

‘Yes,’ Hama said. ‘Yes, in the end I think I did believe it.’

‘Why?’

‘Because of them.’ He gestured at the sky. ‘The Xeelee. If our second-hand wisdom has any validity at all, we know that the Xeelee react to what they fear. And almost as soon as Reth constructed his interface to his world of logic and data, as soon as the pharaohs began to pass into it, they came here.’

‘You think the Xeelee fear us?’

‘Not us. The bugs in the ice: Reth’s cryptoendoliths, dreaming their billion-year dreams . . . The Xeelee seem intent on keeping those dreams from escaping. And that’s why I think Reth hit on a truth, you see. Because the Xeelee see it too.’

Now, over one horizon, there was a glowing crimson cloud, like dawn approaching - but there could be no dawn on this all-but-airless world.

‘Starbreaker light,’ murmured Nomi. ‘The glow must be vapour, ice splinters, dust, thrown up from the trench they are digging.’