Stephen Baxter: Xeelee: Endurance

‘Why?’

‘It seems to be studying Effigies. It thinks that the Construction Material of which Buildings are made excludes Effigies. Some of us are born inside Buildings, so no Effigy can enter us then. Others die within a Building, a special one we call the Morgue, in an attempt to trap the Effigies when they are driven out of their bodies. My own great-aunt died recently, and had to be taken inside the Morgue, but no Effigy was released.’

‘It seems very strange to us,’ Mina said cautiously. ‘To Shelf folk, I mean. That here you are living out your lives on a machine, made by another machine.’

‘It’s not as if we have a choice,’ Telni said, feeling defensive. ‘We aren’t allowed to leave.’

She looked down at her feet, which were clad in sensible leather shoes – not spindling hide like Telni’s. ‘I could tell that a machine built this place. It lacks a certain humanity.’ She glanced at him uncertainly. ‘Look, I’m speaking as a Philosopher. I myself am studying geology. The way time stratification affects erosion, with higher levels wearing away faster than the low, and the sluggish way rivers flow as they head down into the red . . . All this is a manifestation of depth, you see, depth that pivots into time. On the Shelf we all grew up on a cliff-top, over all that depth. But here we are suspended in the air on a paper-thin sheet! Whatever the intentions of the Weapon that governs you, it doesn’t feel safe. A human designer would never have done it like this.’

‘We live as best we can.’

‘I’m sure.’

‘I’ll show you,’ he said with a dash of defiance.

He took her to the very centre of the Platform, and the wheel that turned as always, drawn by teams of patient spindlings as they laboured to draw up supplies from the plain below.

MinaAndry patted the necks of the plodding beasts. The cargo jockeys, unloading buckets and pallets of supplies drawn up from the Lowland, stared at her curiously.

She said, ‘How charming these beasts are! You know that on the Shelf they were driven to extinction during the Creationist-Mechanist Wars. We are slowly restocking with animals drawn up from the Lowland herds, but it’s ferociously expensive . . .’

Something about the way she patted and stroked the tall, elegant creatures moved Telni deep inside. But he had to pull her aside when he saw a spindling was ready to cough up its faeces. Mina was astonished at the sight.

He took Mina’s hand and led her to the centre of the Hub, close to the great hatch in the floor of the Platform, which revealed the goods-laden cables that dangled down to the Lowland far below.

Mina squealed and drew back. ‘Oh! I’m sorry. Vertigo – what a foolish reaction that is! Although it proves my point about the uncomfortable design.’

He pointed down through the hole. ‘I brought you here to see my own work. I earn my living through my studies with an apothecary. But this is my passion . . .’

Holding tight to the rail, pushing a stray strand of hair back from her face, she peered down through the floor. From here, Telni’s cradles of pendulums, of bobs and weights and simple control mechanisms, were clearly visible, attached in a train along one of the guide ropes that tethered the Platform to the Lowland plain.

‘Pendulums?’

‘Pendulums. I time their swing. From here I can vary the length and amplitude . . .’ He showed her a rigging-up of levers he had fixed above the tether’s anchor. ‘Sometimes there’s a snag, and I go down in a harness, or send one of the cargo jockeys.’

‘How do you time them?’

‘I have a clock the Weapon gave me. I don’t understand how it works,’ he said, and that admission embarrassed him. ‘But it’s clearly more accurate than any clock we can make. I have the pendulums spread out over more than a quarter of a kilometre. There’s no record of anybody attempting to make such measurements over such a height difference. And by seeing how the period of the pendulums vary with height, what I’m trying to measure is—’

‘The stratification of time. The higher up you raise your pendulums, the faster they will swing.’ She smiled. ‘Even a geologist understands that much. Isn’t it about five per cent per metre?’

‘Yes. But that’s only a linear approximation. With more accurate measurements I’ve detected an underlying curved function . . .’ The rate at which time flowed faster, Telni believed, was actually inversely proportional to the distance from the centre of Old Earth. ‘It only looks linear, simply proportional to height, if you pick points close enough together that you can’t detect the curve. And an inverse relationship makes sense, because that’s the same mathematical form as the planet’s gravitational potential, and time stratification is surely some kind of gravitational effect . . .’ He hoped this didn’t sound naive. His physics, based on philosophies imported from Foro centuries ago with the Platform’s first inhabitants, was no doubt primitive compared to the teachings Mina had been exposed to.

Mina peered up at a sky where a flock of stars, brightly blueshifted, wheeled continually around an empty pole. ‘I think I understand,’ she said. ‘My mathematics is rustier than it should be. That means that the time distortion doesn’t keep rising on and on. It comes to some limit.’

‘Yes! And that asymptotic limit is a distortion factor of around three hundred and twenty thousand – compared to the Shelf level, which we’ve always taken as our benchmark. So one year here corresponds to nearly a third of a million years, up there in the sky.’

She looked up in wonder. ‘It is said that nearly ten thousand years have elapsed since the last Formidable Caress. An interval that spans all the history we know. But ten thousand years here —’

‘Corresponds to about three billion years there. In the sky. We are falling into the future, Mina! And if you study the sky, as some do, you can see the working-out of time on a huge scale. A year up there passes in a mere hundred seconds down here, and we see the starscape march to that pace. And even as the sky turns, the stars in their flight spark and die, they swim towards and away from each other . . . We live in a great system of stars, which we see as a band across the sky. Some say there are other such systems, and that they too evolve and change.

‘And some believe that once Old Earth was a world without this layering of time, a world like many others, perhaps, hanging among the stars. Its people were more or less like us. But Old Earth came under some kind of threat. And so the elders pulled a blanket of time over their world and packed it off to the future: “Old Earth is a jar of time, stopped up to preserve its children” – that’s how it has been written.’

‘That’s all speculation.’

‘Yes. But it would explain such a high differential of perceived time. I’m always trying to improve my accuracy. The pendulums need to be long enough to give a decent period, but not too long or else the time stratification becomes significant even over the length of the pendulum itself , and the physics gets very complicated—’

She slipped her hand into his. ‘It’s a wonderful discovery. Nobody before, maybe not since the last Caress, has worked this out before.’

He flushed, pleased. But something made him confess, ‘I did need the Weapon’s clock to measure the effects sufficiently accurately. And the Weapon set me asking questions about time in the first place.’

‘It doesn’t matter what the Weapon did. This is your work. You should be happy.’

‘I don’t feel happy,’ he blurted.

She frowned. ‘Why do you say that?’