Still, that Conurbation was our target for the evacuation. Amid the domes I could see the squat cone shape of a heavy-lift shuttle, dropped here on the Spline’s last pass through the atmosphere, ready to lift the population.
But I had a problem, I saw now. My marines were heading straight for the nominal target, the Conurbation, just as they should. But there was another cluster of buildings and lights, much smaller, stranded halfway up the flank of the mountain. There was no sign of domed Conurbation architecture, but there seemed no doubt this was human. Another village? And then I saw a pale pink light blinking at me from the middle of that cluster of shacks.
I’m not sentimental, and I don’t go for heroic gestures. In a given situation, with given resources, you do what you can, what’s possible. Given a free hand I’d have concentrated my energies on evacuating the Conurbation which undoubtedly held the bulk of the population. I wouldn’t have gone after that isolated handful of people, wouldn’t have approached that village at all - if not for that pink light. It was Tilo’s beacon. Kard had made it clear enough that unless I came home with the Academician, or at least with his data, next time I made a drop it would be without a Yukawa suit.
I slowed my fall and barked out orders. I knew my people would be able to supervise the evacuation of the main township without me; it was a simple mission. Then I redirected my own descent, down towards the smaller community. I’d go get Tilo out of there myself.
It was only after I had committed myself that I saw one of my troop had followed me: the kid, Lian.
No time to think about that now. A Yukawa suit is good for one drop, one way. You can’t go back and change your mind. Anyhow I was already close. I glimpsed a few ramshackle buildings, upturned faces shining like coins.
Then the ground raced up to meet me. Feet together, knees bent, back straight, roll when you hit - and then a lung-emptying impact on hard rock.
I allowed myself three full breaths, lying there on the cold ground, as I checked I was still in one piece.
Then I stood and pulled off my visor. The air was breathable, but thick with the smell of burning, and of sulphur. But the ground quivered under my feet, over and over. I wasn’t too troubled by that - until I reminded myself that I wasn’t on a ship any more, that planets were supposed to be stable.
Lian was standing there, her suit glowing softly. ‘Good landing, sir,’ she said.
I nodded, glad she was safe, but irritated; if she’d followed orders she wouldn’t have been here at all. I turned away from her, a deliberate snub that was enough admonishment for now.
I tried to get my bearings. The sky was deep. Beyond clouds of ash, sunsats swam. And past them I glimpsed the red pinprick of the true sun, and the wraith-like Galaxy disc.
I was just outside that mountainside village. Below me the valley skirted the base of Mount Perfect, neatly separating it from more broken ground beyond. The landscape was dark green, its contours coated by forest, and clear streams bubbled into a river that ran down the valley’s centre. A single, elegant bridge spanned the valley, reaching towards the old Conurbation on the far side. Further upstream I saw what looked like a logging plant, giant pieces of yellow-coloured equipment standing idle amid huge piles of sawn trees. Idyllic, if you liked that kind of thing, which I didn’t.
On this side of the valley, the village was just a huddle of huts - some of them made from wood - clustered on the lower slopes of the mountain. Bigger buildings might have been a school, a medical centre maybe, and there were a couple of battered ground transports. Beyond, I glimpsed the rectangular shapes of fields - apparently ploughed, not a glimmer of replicator technology in sight. It was like a living-history exhibit. But today it was all covered in ash.
People were standing, watching me, grey as the ground under their feet. Men, women, children, infants in arms, old folk, people in little clusters. There were maybe thirty of them.
Lian stood close to me. ‘Sir, I don’t understand. The way they are standing together—’
‘These are families,’ I murmured. ‘You’ll pick it up.’
‘Dark matter.’ The new voice was harsh, damaged by smoke.
A man was limping towards me. About my height and age but a lot leaner, he wore a tattered Navy coverall, and was he using an improvised crutch to hobble over the rocky ground, favouring what looked like a broken leg. His face and hair were grey with the ash.
I said, ‘You’re the Academician.’
‘Yes, I’m Tilo.’
‘We’re here to get you out.’
He barked a laugh. ‘Sure you are. Listen to me. Dark matter. That’s why the Xeelee are here, meddling in this system. It may have nothing to do with us at all. Things are going to happen fast. If I don’t get out of here … whatever happens, just remember that one thing - dark matter.’
A woman hurried towards me. One of the locals, she was wearing a simple shift of woven cloth, and leather sandals on her feet; she looked maybe forty, strong, tired. An antique translator box hovered at her shoulder. ‘My name is Doel,’ she said. ‘We saw you fall.’
‘Are you in charge here?’
‘I—’ She smiled wearily. ‘Yes, if you like. Will you help us get out of here?’
She didn’t look, or talk, or act, like any Expansion citizen I had ever met. Things truly had drifted here. ‘You are in the wrong place.’ I was annoyed how prissy I sounded. I pointed to the Conurbation, on the other side of the valley. ‘That’s where you’re supposed to be. The evacuation point.’
‘I’m sorry,’ she said, bemused. ‘We’ve lived here in the village since my grandfather’s time. We didn’t like it, over in Blessed. We came here to live a different way. No replicators. Crops we grow ourselves. Clothes we make—’
‘Mothers and fathers and grandfathers,’ Tilo cackled. ‘What do you think of that, Lieutenant?’
‘Academician, why are you here, in this village?’
He shrugged. ‘I came to study the mountain, as an exemplar of the planet’s geology. I accepted the hospitality of these people. That’s all. I got to like them, despite their - alien culture.’
‘But you left your equipment behind,’ I snapped. ‘You don’t have comms implants. You didn’t even take your mnemonic fluid, did you?’
‘I brought my pickup beacon,’ he said smugly.
‘Lethe, I don’t have time for this.’ I turned to Doel. ‘Look, if you can get your people across the valley, to where that transport is, you’ll be taken out with the rest.’
‘But I don’t think there will be time—’
I ignored her. ‘Academician, can you walk?’
Tilo laughed. ‘No. And you can’t hear the mountain, can you?’
That was when Mount Perfect exploded.
Tilo told me later that, if I’d known where and how to look, I could have seen the north side of the mountain bulging out. The immense chthonic defect had been growing visibly, at a metre a day. Well, I didn’t notice that. Thanks to some trick of acoustics I didn’t even hear the eruption - though it was heard by other Navy teams working hundreds of kilometres away.
But the aftermath was clear enough. With Lian and Doel, and with Academician Tilo limping after us, I ran to the crest of a ridge to see down the length of the valley.
As we watched, a billion tonnes of rock slid into the valley in a monstrous landslide. Already a huge grey thunderhead of smoke and ash was rearing up to the murky sky. A sharp earthquake had caused the mountain’s swollen flank to shear and fall away.
But that was only the start of the sequence of geological events, for the removal of all that weight was like opening a pressurised can. The mountain erupted - not upwards, but sideways, like the blast of an immense weapon, a volley of superheated gas and pulverised rock. The eruption quickly overtook the landslide, and I saw it demolish trees, imports from distant Earth, sentinels centuries old flattened like straws. I was stupefied by the scale of it all.
And there was more to come. From out of the ripped-open side of the mountain, a chthonic blood oozed, yellow-grey, viscous, steaming hot. It began to flow down the mountainside, spilling into rain-cut valleys.
‘That’s a lahar,’ Tilo murmured. ‘Mud. The heat is melting the permafrost - the mountain was snow-covered two weeks ago; did you know that? - making up a thick mixture of volcanic debris and meltwater. I’ve learned a lot of esoteric geology here, Lieutenant.’
‘So it’s just mud,’ said Lian uncertainly.
‘Just mud. You aren’t an earthworm, are you, marine?’
‘Look at the logging camp,’ Doel said.
Already the mud had overwhelmed the heavy equipment, big yellow tractors and huge cables and chains used for hauling logs, crumpling it all like paper. Piles of sawn logs were spilled, immense wooden beams shoved downstream effortlessly. The mud, grey and yellow, was steaming, oddly like curdled milk.
Just mud. For the first time I began to consider the contingency that we might not get out of here.
In which case my primary mission was to preserve Tilo’s data. I quickly used my suit to establish an uplink. We were able to access Tilo’s records, stored in cranial implants, and fire them up to the Spline. But in case it didn’t work—
‘Tell me about dark matter,’ I said. ‘Quickly.’
Tilo pointed up at the sky. ‘That star - the natural sun, the dwarf - shouldn’t exist.’
‘What?’
‘It’s too small. It has only around a twentieth of Earth’s sun’s mass. It should be a planet: a brown dwarf, like a big, fat Jovian. It shouldn’t burn - not yet. You understand that stars form from the interstellar medium - gas and dust. Originally the medium was just Big-Bang hydrogen and helium. But stars bake heavy elements, like metals, in their interiors, and eject them back into the medium when the stars die. So as time goes on, the medium is increasingly polluted.’
Impatiently I snapped, ‘And the point?’
‘The point is that an increase in impurities in the interstellar medium lowers the critical mass needed for a star to be big enough to burn hydrogen. So as time goes by and the medium gets murkier, smaller stars start lighting up. Lieutenant, that star shouldn’t be shining. Not in this era, not for trillions of years yet; the interstellar medium is too clean … You know, it’s so small that its surface temperature isn’t thousands of degrees, like Earth’s sun, but the freezing point of water. It is a star with ice clouds in its atmosphere. There may even be liquid water on its surface.’
I looked up, wishing I could see the frozen star better. Despite the urgency of the moment I shivered, confronted by strangeness, a vision from trillions of years downstream.
Tilo said bookishly, ‘What does all this mean? It means that out here in the halo, something, some agent, is making the interstellar medium dirtier than it ought to be. The only way to do that is by making the stars grow old.’ He waved a hand at the cluttered sky. ‘And if you look, you can see it all over this part of the halo; the stellar evolution diagrams are impossibly skewed.’
I shook my head; I was far out of my depth. What could make a star grow old too fast? … Oh. ‘Dark matter?’
‘The matter we’re made of - baryonic matter, protons and neutrons and the rest - is only about a tenth of the universe’s total. The rest is dark matter: subject only to gravity and the weak nuclear force, impervious to electromagnetism. Dark matter came out of the Big Bang, just like the baryonic stuff. As our Galaxy coalesced the dark matter was squeezed out of the main disc … But it lingered here. This is the domain of dark matter, Lieutenant. Out here in the halo.’
‘And this stuff can affect the ageing of stars.’
‘Yes. A dark matter concentration in the core of a star can change temperatures, and so affect fusion rates.
‘You said an “agent” was ageing the stars. You make it sound intentional.’
He was cautious now, an Academician who didn’t want to commit himself. ‘The stellar disruption appears non-random.’
Through the jargon, I tried to figure out what this meant. ‘Something is using the dark matter? … Or are there life forms in the dark matter? And what does that have to do with the Xeelee, and the problems here on Shade?’
His face twisted. ‘I haven’t figured out the links yet. There’s a lot of history. I need my data desk,’ he said plaintively.
I pulled my chin, thinking of the bigger picture. ‘Academician, you’re on an assignment for the Admiral. Do you think you’re finding what he wants to hear?’
He eyed me carefully. ‘The Admiral is part of a faction within the Navy that is keen to go to war with the Xeelee - if necessary, even to provoke conflict. Some call them extremists. Kard’s actions have to be seen in this light.’
Actually I’d heard such rumours, but I stiffened. ‘He’s my commanding officer. That’s all that matters.’
Tilo sighed. ‘I understand. But—’
‘Lethe,’ Lian said suddenly. ‘Sorry, sir. But that mud is moving fast.’
So it was, I saw.
The mud was filling up the valley, rising rapidly, even as it flowed towards us. It was piling up behind a front that was held back by its own viscosity. As it surged forward the mud ripped away the land’s green coat to reveal bare rock, and was visibly eating away at the walls of the valley itself. Overlaying the crack of tree trunks and the clatter of rock there was a noise like the feet of a vast running crowd, and a sour, sulphurous smell hit me.