Purgatory Mount

by Adam Roberts

Genres: Science Fiction; Space Exploration; Space Opera

Synopsis

An interstellar craft is decelerating after its century-long voyage. Its destination is V538 Aurigae ?, a now-empty planet dominated by one gigantic megastructure, a conical mountain of such height that its summit is high above the atmosphere. The ship's crew of five hope to discover how the long-departed builders made such a colossal thing, and why: a space elevator? a temple? a work of art? Its resemblance to the mountain of purgatory lead the crew to call this world Dante.

In our near future, the United States is falling apart. A neurotoxin has interfered with the memory function of many of the population, leaving them reliant on their phones as makeshift memory prostheses. But life goes on. For Ottoline Barragão, a regular kid juggling school and her friends and her beehives in the back garden, things are about to get very dangerous, chased across the north-east by competing groups, each willing to do whatever it takes to get inside Ottoline's private network and recover the secret inside.

Purgatory Mount, Adam Roberts's first SF novel for three years, combines wry space opera and a fast-paced thriller in equal measure. It is a novel about memory and atonement, about exploration and passion, and like all of Roberts's novels it's not quite like anything else.

Shortlisted for the 2021 BSFA award for Best Novel!

Release date: February 4, 2021

Publisher: Orion Publishing Group

Print pages: 336

Sample

:1:

The Forward, interstellar exploration craft. Here, present, correct: its crew of five. To assist these brave explorers, the ship has been equipped with a great quantity of advanced technology and an even larger quantity of supplies, dry store as well as livestock – animals from pygs and sheep all the way down to chickens, mice and microbes. The ship was shaped like a kilometre-long church spire, a comparison that dates from the period when churches were architecture with common cultural currency. But only pygs go to church these days. So say, rather: the ship was shaped like a gigantic bullet, crafted of ice many hundreds of metres thick – shield, fuel and a reservoir all at once. Inside this titanic sheath was a structure made of metallic plastic, eighty major compartments and many smaller spaces and corridors, ship’s supplies and life-support. The drive shaft extended fourteen hundred metres to the rear.

Now the Forward was entering the system of V538 Aurigae. The eagles are coming! The eagles are here!

The ship was shaped like a bullet to streamline it, because interstellar space is not a vacuum. It is, rather, an extremely attenuated gas: ions, atoms and molecules spread so thinly that one might encounter only a single atom in each cubic kilometre (or, of course, one might encounter areas considerably more dense with particles). At the speeds needful for interstellar travel, even flying into the path of one molecule releases significant energy, and flying for centuries at very high speeds is, in effect, to fly through an atmosphere. Moreover, at such speeds, evasive action is sluggish and limited, and however good one’s forward sensors, there is always the chance that your craft will encounter a damaging, perhaps even a catastrophic collision event on your travels. It all adds to the spice of the journey. But the Forward made it to V538 Aurigae without such disaster. Indeed, if one believed in Providence, one might find fortuity in the fact that our natal star, the Sun, happens to exist in what is called ‘the Local Bubble’, a relative cavity in the interstellar medium some 300 light-years in breadth and height, in which the density of space is markedly lower than the surroundings. The unusually sparse gaseous and molecular matter in this cavity is the result of a supernova explosion fifteen million years ago, the force of which cleared much of this space. This works to facilitate travel between stars in our local group. And so human beings pour into this space, flying in all directions, because, like Mallory with Everest, space in every direction is there. Dark, dark, dark – oh, we all go into the dark. It’s almost as if Providence wants humanity to spread out from its natal star! Eagles leaving the nest.

Of course, you don’t believe in Providence. No matter!

The five human beings crewing the Forward had travelled to V538 Aurigae to see for themselves. To check it out. They were coming to observe at first-hand a strange feature spotted on the third planet of this system, V538 Aurigae γ. This feature had been noted by a passing probe – an unmanned device which had been moving at a significant fraction of light speed and had come no closer to the Aurigaean system than half a light-year. At such distances and velocities no very detailed or precise data could be collected, although enough information returned (eventually) to Earth to suggest some unusual terrain on Aurigae γ. It was probably nothing. Certainly, nobody suspected that it might be an alien megastructure, or anything of that sort. No intelligent alien life had yet been encountered, and neither had any human being yet visited any archaeological remnant of vanished intelligent alien civilisations. Still, it gave the owners, which is to say the crew, of the Forward somewhere to go, something to look into.

They did not realise as they set off from Earth that they would strike gold.

As the Forward approached closer and closer to the Aurigaean system and was able to analyse better data from γ, the lineaments of the artefact became clearer. A pillar on a conical base, or perhaps it would be better described as a continuous hyperbolic tower. It stretched 142 kilometres above the surface of the planet, far above the atmosphere and into space. Presumably, therefore, the artefact represented an alien space elevator, or at least the remnants of one. As the Forward approached closer still, the data became more accurate and informative. The structure stood on a roughly circular island, two hundred kilometres across, and grew, as a mountain might, smoothly from the bedrock. It manifestly was not a naturally occurring element in the landscape: therefore, it had been constructed. But it had been constructed so as to resemble a massively elongated mountain, with its peak outside the air. There were many terraces running around the circumference, but twelve main ones. In all this it resembled the mountain of Purgatory, as described in Dante’s medieval Italian epic, and so the crew began referring to it with that name. To be precise: Dante’s fictional mount had possessed nine terraces, with one extra, a magic garden, at the very top; but this alien structure was close enough in broader resemblance for the name to stick.

There were no signs of contemporary industry, technology or life anywhere on γ.

The Captain (we can call them that, although it’s not how they or their fellow crew members thought of them) walked the Forward’s corridors. The ship’s infrastructure was a smart-shell which could reconfigure itself in various ways. When the mission settled into orbit around γ it would heat its skin to free itself from its giant ice-sheath, shake itself out slowly into a new config and start spinning to simulate gravity. As it was, still being inside its ice-hide, it was configged to be a varied and meaningful arrangement of different-sized chambers and linking corridors that, on the flight to γ, utilised the slow .2g acceleration to give the crew somewhere to walk on. And now that it was approaching its destination, the structure had reconfigged to turn former ceilings into new floors.

The deceleration pulled a rather more testing fraction of g than had the acceleration. But the Captain’s body was quite strong enough to cope with that.

The Captain walked the corridors as they had done throughout the voyage. Each light-year of the forty traversed lasted them a week – which meant that this passage had entailed almost a whole year on duty, sleeping little, checking and monitoring much, personally patrolling their ship. The Captain could easily have watched their ship eat up the light-years more rapidly – that was, after all, what the other four crew members had done (one had watched the entire voyage pass in a month) – but the Captain did not judge such rapid passage compatible with their manifold shipboard duties. As it was, at a week per light-year, many circumstances and problems hurtled around them: the pygs and other animals on board raced hither and thither so rapidly they were blurred lines, more contrail than living creature. The ship’s hal was able to sync its input-output to the Captain’s, or at least it was able to do so most of the time. In the event of a sudden and unexpected emergency, it naturally took the Cap time to gearshift up to the one-to-one of clock-time on board. Indeed, in many cases, the Captain preferred to overshoot, to in effect slow down clock-time relative to themself, one-to-one-point-five or even a higher ratio, to give them more time to consider and react – and that, of course, took them even longer to orchestrate. But emergencies were rare, and for most of the voyage the Captain was content to wander their ship, light-year markers passing weekly. They got a sense of how things were going that way: they could feel, intuit how the ship was operating, the temporal disparity notwithstanding.

As targeted deceleration ate into the Forward’s speed, the other four crew members slowly phased down their perceptual time-consciousnesses to something closer in ratio to shipboard clock-time. No reason to be abrupt about this. Don’t bolt down your changes in temporal perception, or you’ll get temporal indigestion, figuratively speaking. A complex of psychological impairments was associated with the ‘bends’ of enforced suddenness of perceptual temporal reorientation.

Do you do ‘time’? Is that something in which you believe?

Well, all right then!

Let’s talk names. The five crew members each had many different names, depending on which in-group, relation or specifics were concerned. For the purposes of the voyage, and within the interactions of their time together, they had adopted on-ship monikers, and although it is a little tricky to translate these, we can start with the crew member who was responsible for the animal life on board. They took their responsibilities seriously, and many times during the voyage this individual dialled down to actual clock-time in order to check on the biomes, to ponder the data assembled by the agribots, to run specific tests on livestock health and so on. They did this regardless of whether the ship’s hal notified them of a specific issue – as for example when, around the twenty-light-year mark, a glitch in agribot code meant that too many chickens and sheep were culled and butchered at once, such that these two animal populations almost died out, and new storage units had to be excavated from the ice in which to store the meat (it took six months for the stable populations of these animals to be re-established). When that happened, hal called on this person’s expertise, you can be sure! But the longer the voyage continued, and even when there was no specific reason to dial down, this individual did so. It seemed they actually liked getting their hands in the soil, examining the animals and all suchlike labour.

For this reason, their fellow crew members called them Pan. To be clear (and at the risk of mere pedantry), the name ‘Pan’ was not the one they actually used. The name they actually used referenced a figure from a different culture-text altogether, one whose mere composition is hundreds of years in the future as I write this. Pan is an approximation, although a reasonable one. They were a figure gifted with magic (in the Clarkean sense of the word) and given responsibility over beasts, birds and plants, but who pursued that responsibility with a zeal that tipped them over into, as the others saw it, eccentricity.

If this crew member was Pan, then let’s call the Captain Zeus. The analogy is weaker here but will serve. With the other three individuals – Apollo, Dionysus and Hades – the cultural translation is less and less helpful, more and more imprecise. But let’s go with it. Why not?

Zeus, Apollo and Hades had worked together previously, many decades before – on a voyage to 61 Cygni and back again to Earth. All three liked the challenge, liked satisfying their outward urge and their curiosity. And the mission had been profitable! All three were meat-eaters, and Dionysus had a particular taste for pyg-meat, although, since they’d dialled themselves into a very steep perceptual–temporal gradient, they didn’t eat very often. Their bodies subsisted on infed nutrients and hydration, and their consciousnesses, habituated to a accelerated perceptual rhythm, were rarely moved to enjoy food as a somatic delicacy. This meant that the pyg population increased significantly over the course of the voyage. But that was all right.

And now, all five of the crew adjusted themselves incrementally towards a closer perceptual approximation of clock-time. There was no hurry. Deceleration took a while, and the closer they got the more data they received. Of course, they wouldn’t start getting really tasty info on the artefact – this strange pillar, this alien Purgatory Mount – until they were actually in orbit, and exploring it in person.

Captain Zeus stalked the corridors and chambers of their ship. The pygs and chickens and deer streaking past them moved, day by day, slower and slower. From their point of view, of course, the Captain, having marched with almost imperceptible slowness for decades – for their whole lives, and the lives of their parents and parents’ parents – having, indeed, been worshipped as an actual god in pyg societies – was now, for reasons that went beyond what they could ever understand, speeding up. It was no wonder that the pygs grew too terrified to approach the Captain as they made their way about the craft.

Daft little critters.

‘If,’ says Apollo, using their actual voice now that they and Zeus were within easy perceiving distance of one another, ‘it’s a space elevator, or the remains of one, then we would surely expect to see other artefacts – space stations, perhaps abandoned; structures on other planets, perhaps abandoned.’

Apollo sounded like Apollo to Apollo, but to Captain Zeus their voice sounded low and rumbling and rather splendidly menacing.

‘Agreed,’ Zeus said. ‘And yet nothing is showing up on any scan or scope.’

Zeus sounded like Zeus to Zeus, but their voice was high and piping and pleasantly comical to Apollo.

Apollo basso-profundo’d: ‘Unless we’re looking for the wrong sort of thing.’

‘Or,’ squeaked Zeus, ‘unless it was never a space elevator in the first place. Unless it served some other purpose.’

‘Political dominance,’ low-groaned Apollo, Paul Robeson style. ‘Religious observation – perhaps it’s a gigantic cathedral. For all we know, it is hollow. It could be positively riddled with chambers. And who knows what might be inside such interior spaces?’

‘For all we know,’ squealed Zeus, ‘it contains alien technological wonders. Faster than light drives. Time machines. We can’t be sure until we actually go there – step out upon that alien world, walk through those alien chambers!’

‘A structure of such dimensions, such sheer height,’ boomed Apollo, ‘were it made of mere rock, would long since have collapsed back into an entropic heap of rubble. Therefore it must be, either, constructed wholly of some super-strong material, or else reinforced within with ribs and spars of such a kind of stuff. And that in itself would be a discovery of history-altering dimensions. We could return to Earth with the wherewithal, finally, to build a Dyson sphere!’

In this fashion they dreamed, wide awake, of what the consequences of their voyage of discovery might be. And as they chatted, their voices slowly converging, from below and above, on a common timbre, Pan was silently going about their work, testing the soil in the various ship’s biomes, collating data on the various animals, wandering the faux-forests and communing with the beasts. An artificial balance was maintained in the ship’s artificial environment. Most of the animals were herbivores and insectivores, to keep the vegetation and insects in check, and the lack of carnivores – apart, of course, from the pygs, and a few flying raptors – meant that these creatures were prone to unexpected population booms that had to be controlled by the ship’s systems directly. When the chickens, the goats or the sheep began to overbreed, agribots would cull the populations, and the meat would be stored for the crew to consume later. Pan did not like this. That is to say, they didn’t like the final destination of the meat (being vegetarian themselves, they barely tolerated their crew mates eating flesh) but, worse, they disliked the inelegance of it. In their mind, the perfect ship’s mission would be built around a self-sustaining string of biomes. Pan yearned for natural harmony, and in their downtime they studied how large a craft would have to be to manage such a thing. Very large, it seemed. Very much larger than the Forward.

And so these five decelerated towards γ, and towards Purgatory Mount.

:2:

The mysteries associated with this mountain were not dispelled by closer inspection. The Forward settled into a comfortable orbit around γ – unofficially named Dante by Zeus, and subversively referred to variously as Dantette and Aligbarely and Planet Comedy by Hades – and sent down a glitter cloud of drones and probes. The orbit rolled the ship leisurely around the dayside and nightside in forty minutes, which meant crew members could sit at the observation blister and stare at the landscape-seascape below. It was hypnotic. Hades extrapolated from the first deep-dive data that the planet had once enjoyed a hundred thousand pascals of pressure at sea level. This had dropped, now, to a quarter of its former level, and the sea levels were in retreat, with associated dieback of even the hardy, rudimentary vegetation that characterised this world’s only life form.

‘We’ve arrived, by remarkable good luck, while this process is ongoing,’ Hades told the others, over supper (chicken casserole and fresh vegetables for all, save only Pan, who watched the others with a pained expression on their face and picked at a salad). ‘In another, let’s say, fifty thousand years the atmosphere will have leaked almost entirely away – the surface sea will finally evaporate and the surface atmosphere will reduce to a number of hundreds of pascals. Like Mars, before we started reforming it. It will become a desert and dead world.’

‘It’s already dead,’ grumbled Apollo.

Pan, uncharacteristically, was moved to conversational interaction.

‘It has vegetation,’ they pointed out.

‘I’m talking about the sort of life I can hunt and eat,’ said Apollo, with a menacing smile.

‘You can eat vegetables,’ Pan observed mildly.

‘I can,’ said Apollo, spearing a gobbet of spice-fried chicken on one chopstick and holding it up, ‘but I prefer meat.’

‘At any rate, I challenge your prognosis,’ said Zeus, haughtily. ‘Dante is much closer to its star than Mars is to the sun, which means considerably more energy is being pumped into its global system. I suggest the atmosphere will entirely boil away in much fewer than fifty thousand years.’

‘If it had the mass of Mars,’ said Hades, looking contemptuous in the face of this challenge to their authority (it being not offensive enough to merit calling the Captain out in a duel, but enough to incommode Hades in the enjoyment of their meal), ‘then you would be correct. But the earth-like mass of this planet –’ not giving Zeus the satisfaction of using their naming for it – ‘means that it will be millions, not mere thousands, of years before atmospheric gases finally absent themselves altogether.’

They shunted a rack of calculations and equations into the crew’s shared Social and watched as Zeus pointedly ignored the data.

‘I’m more interested,’ the Captain said, ‘in the past than the future. Once upon a time, as the Brothers Grimm might have said, intelligent beings lived here. They assembled, or sculpted, or somehow created this structure. Why? More to the point – how? Our job, comrades mine, is to master the technologies involved. We’re forty light-years from Earth – once the images from our data arrive home it will poke a stick deep in the beehive. It will excite a lot of interest. I’d say we have a century or so before the next wave of excited tourists and speculators and maniacs come buzzing round our discovery. Will a century be long enough?’

‘To unlock all these mysteries?’ Dionysus said. ‘I say – yes.’

‘I, on the other hand,’ said the more cautious Apollo, ‘believe we must triage the specific questions we wish to address.’ When a person lives tens of thousands of years, a mere century comes, of course, to seem a blip. ‘I propose – the structural ones are the most lucrative. If we can replicate whatever it was that enabled our long-gone builders to combine this kind of scale with this kind of rigidity and durability, then we will have the most valuable intellectual property in the history of humanity. It will unlock the ability to build any and every megastructure humanity could conceive!’

‘Agreed,’ said Zeus.

‘One might wonder,’ Pan said quietly, ‘why the original builders didn’t go on to do precisely that?’

The others ignored this intervention.

‘If nobody else is going to say it,’ put in Hades, ‘then I will. We could dial down. We could, if we choose, turn this brief century of research into a thousand years.’

The other four only looked at them.

‘I think I’ll maintain my sanity, if you don’t mind,’ said Dionysus. They added: ‘This chicken lacks flavour. Chicken always does. I suggest we have some roast pyg tomorrow. At least wrap this chicken in a bit of bacon, why not?’

‘All right,’ agreed Hades, speaking to the proposal to dial down, not to the question of bacon. ‘A thousand years might be overambitious. But we can surely dial down a little, and so give ourselves more time?’

‘Let’s see how the first few clock-time years go,’ suggested Zeus, in a conciliatory voice. ‘And then we’ll make a judgment, shall we?’

The problem, in a word, was friction. Not material friction, such as is experienced by these conker-sized probes raining down on Planet Dante, the air heating them cherry-red. Not that. Rather perceptual, cognitive and memorial friction. The mind rubs against the medium of life. That’s the definition of living. Which is to say – ablation is the idiom of existence, and what is ablated over time eventually rubs away entirely. Take these five human beings. It is not physical or bodily decay that limits their lifespan to a few tens of thousands of years. Their bodies are capable of, more or less, unlimited self-repair and restoration. Short of a complete firestorm atomisation of their corporeal selves, these are bodies that will last and last. But the consciousnesses housed in those bodies, their carbon strands of mental tissue, howsoever augmented by silicon data processing capacity – well, that’s a different matter. Mind grates against the medium in which it moves, or else it isn’t thinking at all. Such friction eventually wears mind down. Memory goes first, overloaded by the sheer accumulation of lived experience and information. But memory is also the easiest to prop up with artificial prostheses. Humankind’s first forays into technological enhancement was, after all, precisely the restoration and propping up of functioning memory. The earliest computers were talented at remembering things, storing immense quantities of data and retrieving it briskly and accurately; and it soon followed that the first somatic adaptions to incorporate this tech plugged and resolved memory issues. But memory is only one element of consciousness, and even with unlimited artificial memory and flawless recall, the will to recall eventually fails. Cognitive capacity can, likewise, be bolstered, but it too eventually wears down to a mere stub. The last two things to go are mere perception – but who would want to live, if living meant merely sitting in a chair thoughtlessly aware of one’s surroundings? – and the most stubbornly persistent of all the components of human consciousness, will itself. Some people do subsist on mere will, it is true, all other strands of their minds evacuated and empty and yet still, stubbornly, living on. It is a remarkable thing to see. One might even call it heroic, after the Pyrrhic mode of heroism. But it is not eternal. Even will, sooner or later, wears down. And then the individual dies.

So as these five humans stared down the lengthy boulevard of – a conservative estimate – another twenty thousand years of existence, it was mental existence they were contemplating. And mental existence, defined by friction, is the same whether you are dialled up to one perceptual minute to one clock-time day, or, on the contrary, are experiencing a whole day while the clock ticks through sixty seconds. Indeed, human beings had come to learn that the latter, the artificial intensification of perception (measured with respect to the vibration of caesium atoms in the outer universe) tended to increase perceptual friction to the point where sanity, and life itself, became perilously eroded. Sometimes people indulged, of course, for any number of reasons. But it was smoother to ski fluidly downslope, to watch the universe as a whole flow by in fast-forward – to abbreviate what would otherwise be tediously drawn-out voyages from star to star, for example – than to do the other thing.

But humans are humans, and ever keen to compete with one another. The structural secrets of Purgatory Mount, if these five could uncover them, would make the team vastly wealthy – in terms of status and power (they were already vastly wealthy in terms of material goods and possibilities, of course) – and accordingly they wanted it. If the price of obtaining that knowledge was dialling down to extend the time available to them to unlock the mystery – before the hordes of other humans arrived, having been alerted to this tempting destination, shooting across the long, vacant light-years all the way to V538 Aurigae γ – then that is what they would do.

But maybe the mystery would be more tractable, and such desperate measures would not prove necessary.

‘I suggest,’ said Apollo, ‘establishing a base at the foot of the mountain and spending a little while actually there.’

‘What,’ agreed Zeus, ‘an excellent notion.’

Dessert was a St-Emilion au chocolat torte, followed by cognac laced with psychedelics, and a long and deliciously complicated series of nested trips for all the crew. Then: a refreshing sleep.

:3:

For the first twenty years of B’s life the gods embodied the mystery of timelessness. You could sit in front of one for as long as you liked, fidgeting and restless as you inevitably were, and never see them move. Then you would run off, and spend a couple of weeks in some other part of the ship, and when you returned to the god you would discover that he was a yard further down the corridor. They never moved when you looked at them, but still they moved. It was one of the core and holy mysteries of religious faith, and B found in it an endless source of wonder and fascination.

He was not the most religious person in his family, or in-group, but then again neither was he the least religious. He went to church on Saturday, like his friends and family. He believed some of what was preached, and with respect to other parts he had doubts. But it was part of his life, and he tried to get on with living as best he could.

There were plenty of folk who regarded the gods as false idols. Some of these people worshipped a god ‘outside the ship’, a vague and abstract quantity so far as B could understand it, like admiring strands of dissipating steam instead of drinking the actual coffee. This ‘outsider’ god had many names – The Us, A-Lá, Old Jar of Hova among others – most of which had been winkled out of the shipboard data systems. Hal was supposed to keep a tight rein on what people could access, since its job was maintaining the smooth functioning of the ship, and if people and animals obtained too detailed a sense of how the ship worked, they might (original sin, original sin in every breast) try to break it. But it was possible to sneak past hal’s blocks and guidewires, and people on board generally knew more than hal realised they d. . .