The Arrows of Time: Orthogonal Book Three (2 page)

‘We know we can make the turn,’ Lila said. ‘All the way around that semicircle, the acceleration we need can be produced with the engines sending photons into
the future of
either
the home cluster or the orthogonal cluster. Only the last stage of the journey presents a problem: it’s not clear how we can begin to decelerate in the approach
to the home world. But we’ll have six more generations to address that, and I can’t believe it will prove insurmountable.’

Lila glanced at the timer. ‘To describe this plan as “dangerous” is absurd. Dangerous compared to trying to give birth to
children made of negative luxagens?
I
don’t think so!’

The timer rang. Most of the crowd cheered; Agata ignored her mother’s look of lofty amusement and joined in. Lila deserved the encouragement. Pio’s ideas weren’t likely to get
much traction, but with the vote less than a stint away they needed to be refuted decisively for the sake of everyone’s morale.

Pio dragged himself forward again. ‘What dangers would the return pose?’ he asked. ‘Let’s start with a wildly optimistic view, and suppose that the entire journey could
be completed safely. Once we reach the home world and deal with the Hurtlers, the barbarians are sure to be grateful – for a while. But could we really live among them, after so much time
apart? I can’t see them approving of our ideas about governance, let alone our reproductive methods, and my guess is that they’d hold Starvers in almost as much contempt as Shedders.
Then again . . . since we’ve made such a habit of bequeathing tasks to our descendants, maybe the last one could be to devise the kind of weapons they’d need to defend their way of life
against the planetary status quo.’

Agata shifted uncomfortably on her rope. She knew he was being sarcastic, but any talk of weapons put her on edge.

Pio said, ‘That’s the optimistic view, but the real problems will arise much sooner. As we decelerate for the turn, we’ll be moving at ever greater speeds with respect to the
Hurtlers. For a long time our spin has been enough to fling these specks of dust away, and now we have a fancy system of sensors and coherers guarding the slopes so we can spin-down the mountain
with impunity – but even the coherers won’t be able to protect us once the Hurtlers are moving faster than the fastest radiation we can actually detect.’

The audience fidgeted, underwhelmed. Everyone knew that the
Peerless
was a small target, and though it was true that the mountain’s defences would be useless once the Hurtlers
crossed a certain threshold velocity, the period of vulnerability would be brief.

Pio inclined his head slightly, acknowledging the weakness of the point and moving on. ‘Lila assures us that the engines won’t need to violate any thermodynamic laws as we turn the
Peerless
around. But how certain can we be that they really will keep functioning? And even if the turnaround itself proves uneventful, keep in mind that
the entire return journey
entails our own arrow of time pointing against the arrow of the orthogonal cluster – a configuration we’ve never experienced before.’

Agata couldn’t contain an exasperated hum. The most dramatic effect she expected from the reversal was for the orthogonal stars to vanish from the sky.

‘Beyond those disturbing uncertainties, no one has the slightest idea how we could commence the final deceleration. Lila herself admits as much!’ Pio paused to let the audience dwell
on this – despite his own cheerful confession that he had no idea how a viable migration scheme would work. ‘Imagine what it would mean to be trapped in this mountain, heading back into
a region full of ordinary matter but unable to slow down and match speeds with it. Every grain of interstellar dust we encountered would strike us with infinite velocity – rendering it as
lethal to us as a Hurtler would be to the ancestors. Astronomers in Yalda’s day searched the sky for years to find the safe corridor we’re moving through now. We should take their gift
and make the most of it: we should remain on this trajectory for as long as it’s clear, and use the time to prepare ourselves to step away from all of these colliding worlds and find a home
that will be safe for eons to come.’

As Pio reached down to reset the timer there were a few scattered cheers.

Lila took his place. ‘If migrating to the orthogonal worlds would be so much easier than slowing the
Peerless
for the final approach,’ she said, ‘then let people
ponder both questions while we’re travelling back towards the home world. When one problem or the other is actually solved, we’ll be in a position to make an informed choice.
What’s more, sticking to the plan and reversing the
Peerless
would actually make migration easier: all those negative luxagens in the orthogonal worlds will become positive to us!
The thermodynamic arrow of the orthogonal stars will be pointing against us, but between coping with
that
and trying to walk on antimatter, I know which challenge I’d
prefer.’

Agata turned to her mother and whispered, ‘The woman just won. It’s over!’ Diehard migrationists might have their reasons to remain committed to the more difficult route, but
whatever allure the idea held for wavering voters, Lila had just offered them a vastly less terrifying way to go on thinking about deserting the ancestors, without burning any bridges until their
own safety was guaranteed.

Cira made a non-committal noise.

‘It’s a dangerous cosmos,’ Lila declared. ‘For us, for the ancestors – and for our descendants, whatever choices we make. But thanks to the efforts of the people
who launched the
Peerless
, we’ve had six generations of thought and experiment to ameliorate that danger, and the prospect of six more to come. Pio calls those people barbarians, but
what would be barbaric would be turning our backs on them for no other reason than a lack of certainty. If we’re ever confronted with proof that trying to return to the home world would be
suicidal, then of course we should change our plans. Until then, why would we not do our best to save the lives of the people to whom we owe our existence? And why would we not all wish our own
descendants to be present at that glorious reunion, when the generation who flung a mountain into the sky learn of the extraordinary things we’ve done with the time that they stole for
us?’

Agata clung to a rope outside the voting hall, watching the bars of the histogram slowly rising on the news screen beside the entrance.

‘Agata!’ Her friend Medoro approached, the amiable look of recognition on his face giving way to one of amusement. ‘How long have you been here?’

‘A while,’ she admitted. ‘I voted early, and then I thought I’d stay and watch the turnout.’

‘So you’ve been here since the first bell?’

‘I’ve got nothing else to do,’ she said defensively.

‘If I’d known you were holding a vigil, I would have brought you supplies.’

‘Go and vote,’ she suggested, shooing him towards the entrance.

Medoro leant towards her in a conspiratorial pose. ‘How much are you paying?’ he whispered. ‘I took a dozen pieces from your brother’s side, but you still have a chance
to buy me back.’

‘That’s not funny.’

He swayed back on the rope. ‘Seriously, what’s wrong with you? When I come out we should get something to eat.’ Agata saw him lift his rear gaze towards the screen. ‘I
can barely even see that sliver for the no vote.’

‘I’m not afraid that we might lose,’ she said. ‘What worries me is that we had to ask the question at all.’

‘So we should just be happy cogs in Eusebio’s machine?’ Medoro goaded her. ‘Born into the mountain with no say in anything?’

‘You make it sound as if
Eusebio
had a choice,’ Agata retorted. ‘If there’d been no launch, you wouldn’t have been born anywhere.’

‘Of course,’ Medoro agreed. ‘The builders did the right thing, and I’m grateful. But that doesn’t mean we should be enslaved to them. What we owe the ancestors
isn’t blind allegiance, it’s constant scrutiny of the actual possibilities. Your brother’s wrong because his arguments are wrong – not because the mere idea of deviating
from the plan should be unthinkable.’

Agata was unimpressed by his euphemism: ‘deviating from the plan’ was a phrase befitting a bold rebellion against pernickety bureaucracy, not a calculated act that amounted to mass
murder. But she wasn’t in the mood to pick a fight. ‘Pio’s had his chance to be heard, so maybe that will get it out of his system.’

Medoro said, ‘Sure – but it’s not just Pio and the people who’ll vote with him who needed this. Every one of us knows that the outcome was always a foregone conclusion .
. . but it still matters that it’s only a foregone conclusion because we’ll judge it to be the best choice on offer.’

‘Hmm.’

Medoro headed into the hall. Agata watched as the tally on the screen reached one third of the enrolled population. The ‘yes’ count now outnumbered the ‘no’ by more than
a dozen to one. In principle the result remained undecided, but the truth was that her side was heading for an overwhelming victory.

Medoro emerged, and approached her with a guilty demeanour. ‘Don’t be angry with me,’ he pleaded. ‘But I thought it would only be fair to even things out a
little—’

Agata took a swipe at him; he twisted away. She was almost certain that he was joking, but if he wasn’t she didn’t want to know.

‘Come and eat,’ Medoro said. ‘Assuming you’re not turning into a Starver.’

‘Hardly.’ Agata followed him down the corridor towards the food hall. ‘I’m not turning into a Shedder, either.’ The idea of giving birth terrified her –
whether or not she had to live through the process – but beyond her own fears the last thing she’d wish on any child was to be raised by her idiot brother.

Greta turned to Ramiro. ‘Start the spin-down,’ she said.

Unaccountably, Ramiro hesitated. He’d been anxious for days that, at this very moment, some obscure detail that he’d failed to allow for would make itself known by undermining
everything – but an unplanned hiatus wouldn’t so much forestall the risk of humiliation as turn his fears into a self-fulfilling prophecy.

Just as Greta’s expression of controlled anticipation was on the verge of faltering – and revealing to every onlooker that the delay was not just unexpected but incomprehensible
– his paralysis ended and he threw the switch. A single tiny coherer in the panel in front of him sent its light into the maze of photonics below, and the system that Ramiro had spent the
last six years building, testing and refining began, very slowly, to move the mountain.

The entire Council had crowded into the control room, and now they turned to watch the main navigation screen mounted high on the wall. At Greta’s insistence, Ramiro had programmed an
elaborate animation that made it look as if the sensor readings confirming the successful firing of the counter-rotation engines were only arriving gradually, piece by piece. ‘Not so slowly
that they start to get worried,’ she’d suggested, ‘but not so fast that it’s an anticlimax.’

‘And if something fails?’ he’d asked. ‘How do you want that paced?’

Greta had given this careful thought. ‘Delay it long enough that it looks as if things were going perfectly, up to a point. But not so long that anyone could say that we were hiding
it.’

Ramiro’s own unobtrusive display was feeding him news in real time; so far it was all encouraging. Not only were the engines reporting a flawless performance, the accelerometers and the
star trackers showed that the
Peerless
really had begun shedding its spin. If all went well, in less than three days the mountain would be perfectly still.

For the first time in six generations, chambers at the rim of the
Peerless
would be as weightless as those on the axis, and for a stint, the farmers and an army of helpers would work to
reconfigure the fields, shifting soil from the useless centrifugal floors to surfaces once seen as walls. When they were done, the mountain would be slowly flipped, base over apex, ready for the
main event.

The catalogue of triumphs unfurling on the navigation screen finally reached the same conclusion as the real-time reports. ‘Congratulations!’ Councillor Marina offered effusively.
‘We couldn’t have hoped for a smoother start.’ Ramiro glanced towards her with his rear gaze, but she was addressing herself solely to Greta.

Greta inclined her head graciously.

‘This is promising,’ Councillor Prisca conceded, ‘but the real test is yet to come.’

‘Of course,’ Greta concurred, though Ramiro could see her struggling not to add a few words in favour of the present achievement. The mountain had gained its spin from giant slabs of
sunstone spewing flame into the void, controlled by compressed air and clockwork. Now it was losing it through nothing but light – light flowing through the switches and sensors as much as
the engines themselves. If that didn’t count as a
real test
, they should all just stay silent and humble until the home world itself had been shifted from its course.

An inset opened in the navigation screen and Tarquinia spoke from the observatory on the peak. ‘I’ve made sightings of six beacons and estimated the rate of change of the
Peerless
’s spin. Everything’s within the expected range.’

Ramiro thanked her and she closed the link. For all the built-in redundancy in his own system, an independent manual check was a welcome proof that the software was faithfully reporting
reality.

The Councillors filed out, with Greta following. Ramiro leant back in his harness and stretched his shoulders, chirping softly with relief. In principle, the program controlling the photonics
could do everything now without further intervention: kill the spin, turn the mountain so the giant engines at the base were aimed in the right direction, then start those engines and keep them
glowing with exactly the right power and frequency, until they’d fully reversed the travellers’ original velocity with respect to the home world. Ramiro could see himself sitting at his
console watching the script playing out day by day. But if it was too much to hope that the
Peerless
really would drive itself for the next three years, he’d be satisfied if the
program managed to detect and describe any problems it was unable to circumvent.