At last, Raoul saw, their steady rise was slowing, the tangle of silver cables thinning out, as if they were reaching the top of a vast metallic tree. But there was still no sign of black, star-studded sky above; rather he made out swathes of light, glowing brightly, bright as the sun. Maybe the ship was actually sailing through the outer layers of a sun; it wouldn’t be the first time the Ghosts had pulled such a stunt.

But the light, so his smart eyes quickly told him, was too complex for that. It was as if the sky was crowded with stars, every place he looked.

And suddenly he understood. Olbers’ paradox . . .

‘Sink Ambassador. This teleportation technique of yours. It can carry you from one side of the universe to the other. Yes?’

‘Further than that.’

‘And the light that bathes us—’

‘It is starlight, Jack Raoul. Nothing but starlight.’

Again he had the sense that someone called him. He ascended into the light, seeking the voice.

‘After several seconds the eyelids closed again, slowly and evenly, and the eyes took on the same appearance as before.

‘I called out again.

‘Once more, without any spasm, the lids lifted. Undeniably living eyes fixed themselves on mine with perhaps even more penetration than the first time. Then there was a further closing of the eyelids, but now less complete.’

He looked down at the Ghost ship, a mass of entwined silvery cables with knots of life embedded everywhere, all of it glowing in the endless starlight. He could still make out the Sink Ambassador, a mercury droplet clinging to the tangle.

But the structure was shrinking, closing on itself. The sky was a sphere of light, glowing white, and he felt he was being drawn away from the tangle, up into the light.

‘Olbers’ paradox,’ he whispered.

‘Yes,’ said the Ghost. ‘A key moment in the evolution of human thought, a philosophical fossil preserved by exiles through the Qax Extirpation . . . If the universe were infinite and static, every line of sight would meet the surface of a star, and the whole sky would be as bright as the surface of a sun. Even occluding dust clouds would soon become as hot as the stars themselves. That was evidently not so, observed those thinkers of old Earth. Therefore their universe could not be infinite or static.’

‘But here—’

‘But here, things are different. This appears to be a pocket universe, Jack Raoul. We believe it is a bubble of spacetime pinched off by a singularity. The heart of a black hole, perhaps.’

‘Infinite and static.’

‘Yes.’

‘It doesn’t make sense,’ Raoul said. ‘If the whole sky is as hot as the surface of the sun - Ambassador, how do you keep cool?’

The Ghost rolled, shimmering. ‘There is another pocket universe at the centre of the colony. Our heat is dumped there.’