It all depended on the Guardians, and their Snowflake cosmic-linkage technology. Luru said, ‘With such a technology you can do almost anything you can conceive of. Why, you can bend spacetime itself . . .’

And that was what Luru intended to do.

If you descended into a gravity well, you found your clocks turning more slowly than those of your colleagues on an orbiting ship, far above. All this was commonplace. Even in a gravity well as shallow as Earth’s, time passed more slowly for Symat than for an observer up there in free space. In a black hole, the deepest gravity well possible, the time-stretching effect ultimately became dominant, until at the event horizon itself time would cease to flow for you altogether.

The Curator shook his head. ‘Ascendent, I’m no physicist. Are you planning to turn the Earth into a black hole?’

‘No. But I want to reshape its spacetime.’

Luru planned to make the Earth a pit of slow time. Just as if looking into a black hole, from the outside time on its surface would seem stretched out. Conversely if you stood on its surface, you would see blueshifted stars wheel across the sky, flaring and dying. It was possible to do all this, she claimed, by manipulating spacetime subtly; you didn’t need the immense and concentrated mass of a black hole to do it.

Mela was looking oddly absent; Symat imagined massed intelligences looking through her eyes and listening through her ears, and crowding her mind with their speculations. She said, ’It would have to be quite a gradient. There would be a perceptible difference in the passage of time over the height of a human - a difference between your head and your toes!’

Symat scratched his head. ‘That would be a strange place to live.’

‘People adapt. And with their lives stretched out to megayears, ’ Luru said, ‘the inhabitants of Earth would be safe from the depredations of the Xeelee, or anybody else. They wouldn’t even need energy from outside, for Earth’s inner heat, reduced to a trickle, would fuel their slow-moving biosphere. Of course there are a few details to work out. This must be a long-term solution. The saved Earth - or “Old Earth” as I think of it - will need a stocked ecology, a self-renewing biosphere, some equivalent of tectonic processing. It will need a day and a night. I haven’t worked out how yet.’

The Curator laughed. ‘A typical Ascendent solution - to save the world with a gift of time!’

‘But,’ Symat asked anxiously, ‘will it work?’

‘Oh, yes,’ Luru said calmly. ‘The Guardians can do this. I’ve been able to consult them about it. They can turn their weapons on the Earth itself, and use the resources of a universe to reshape it as they please.’