I am – let’s be honest, was – a human being, a woman named Nysa. I was born on Pellucid, a world of the Commonwealth. After a happy childhood I had dreams of being a dancer or choreographer. In my teens, however, I showed a striking aptitude for physics. Not many people have the right mental architecture to fully understand momentum trading, but I grasped the slippery fundamentals with a quick, intuitive ease. Rapidly it was made clear to me that I had a duty, an obligation, to the Commonwealth. The encouragement to study propulsion physics was fierce, and I duly submitted.
In truth, it wasn’t a hard decision. I would have been one dancer among thousands, struggling for recognition. But as a physicist I was already a singular, bright-burning talent.
It was at the academy that I fell into Vashka’s orbit, and eventually in love. Like me, she’d been plucked from obscurity on the basis of a talent. Vashka’s brilliance lay in nothing so mundane as the mechanics of space travel, though. She was drawn to the grandest and oldest of the physical disciplines: the study of the origin, structure and destiny of our universe. This project, this entire mission – sponsored by the economies of hundreds of planets, across dozens of solar systems – was her brainchild.
I think of Vashka now, when her hate for me had reached its bitter zenith. We were in Sculptor’s conference room, all twelve of the vivified crew, debating the impact of the latest uplink. Through the upsweeping radiation-proof glass of the windows, the pulsar’s optical pulses strobe-lit the glittering face of Pebble five times a second. Each pulse sapped angular momentum from the pulsar’s rotation. In ten billion years, that little city-sized nugget of degenerate matter would have exhausted its capacity to pulse at all. But it would still be out here, a softly radiating neutron star. In a hundred billion years, much the same would still be true.
“It’s not a question of whether we do this,” Vashka said, looking at each of us in turn with that peculiar steely gaze of hers. “We have no choice in the matter. It’s what we were sent out here to accomplish; what the entire Commonwealth is depending on us to get done. If we turn back now, we may as well not have bothered.”
“Even allowing for this latest uplink,” Captain Reusel said carefully, “the majority of the symbol chains won’t need significant modification. There’ll be a few mistakes, a few incorrect assertions. But the overall picture won’t be drastically different.” Reusel spoke with judicial equanimity, committing herself to neither side until she’d heard all the arguments and had time to weigh them.
“If we knowingly leave errors in the Pebble engravings,” Vashka replied, “we’ll be doing more harm than if we’d never started.”
I coughed by way of interjection. “That’s an exaggeration. Our cosmological descendants – the downstream aliens, whoever they are – will be at least as smart as us, if not more so. They’ll be aware that we weren’t infallible, and they’ll be alert to mistakes. We don’t have to get this absolutely, one-hundred per cent correct. We just have to give them a shove in the right direction.”
Vashka couldn’t mask her disgust. “Or they may be so inflexible in their thinking that they tie themselves in knots trying to reconcile our errors, or decide to throw Pebble away as a lost cause. The point is we don’t have to take a chance either way. All we have to do is get this right, before we leave. Then we can go home with a clear conscience.”
In the run-up to the decision about the latest draft the tension had opened a cleft neither of us was willing to bridge. Vashka, rightly, saw me as the one thing standing between her and the satisfactory completion of the project. In my instinct to caution, my willingness to accept compromise over perfection, I’d shifted from ally to adversary.
We’d stopped sleeping together, restricting our interactions to acrimonious exchanges in the conference room. Beyond that, we had nothing worth saying.
“You won’t have a conscience to keep clear, if the cores go critical,” I said.
Vashka shot back a look of unbridled spite. “Now who’s exaggerating, Nysa?”
Reusel sighed. She hated bickering among her crew, and I knew ours caused her particular hurt. “Estimated time to engrave the new modifications, Loimaa?” The question was directed at the willowy senior technician in matters of planetary sculpture.
“Based on the last round of modifications,” Loimaa said, glancing down at hidden numbers, “with both grasers at maximum output… thirty thousand orbits, give or take. Around a thousand days.”
“Forget it,” I said. “That’ll take us much too far into the red. I’m already uncomfortable with the existing over-stay.”
“Home wouldn’t have uplinked the modifications if they didn’t mean us to implement them,” Vashka said.
“Home don’t have realtime data on our engine stability,” I countered. “If they did, they’d know that we can’t delay our return much longer.”
“Things are that critical?” Reusel asked, skepticism and suspicion mingling in her narrowed eyes. “If they were, I trust you’d have let me know by now…”
“Of course,” I said. “And for the moment things are nominal. We’re probably good for another hundred days. But a thousand… that’s completely out of the question.”
By accident or design, Sculptor’s starboard engine pod was visible through the conference room windows. I didn’t have to ask any of the others to glance at it – their attention was drawn anyway. I imagined what they were thinking. The light spilling from the radiator grids – was it hotter, whiter, than it had been a week ago, a month?
Of course. It couldn’t be otherwise, with the momentum debt we’d incurred reaching Pebble. A debt that the universe sought to claw back like a grubby-fingered pawnbroker.
It would, too: one way or the other.
“We could begin the resculpting,” Loimaa proposed, looking hesitantly at Vashka for affirmation. “Stop it the moment Nysa gave the word. It wouldn’t take more than a few days to clear up shop and begin our return home.”
“A few days might still be too much, if the instabilities begin to mount,” I said.
“Abandoning the work half-unfinished isn’t an option either,” Vashka declared. “The corrections are too complex and inter-dependent. We either implement them fully, or not at all.”
“I see your point,” Reusel said. “At the moment, the Pebble engravings embody errors, incorrect premises and false deductions. But at least there’s a degree of internal consistency, however flawed it might be. The sense of an argument, with a beginning, middle and end.”
Vashka’s nod was cautious. “That’s correct. It offends me that we might leave these errors in place, but it’s still better than tearing up half the logic chains and leaving before we’ve restored a coherent narrative.”
“Then it’s simple,” I said, trying hard not to let my satisfaction break through. “The lesser of two evils. Better to leave now, knowing we’ve left something self-consistent in place, than be forced to bail out halfway through the next draft.”
The captain was thoughtful. Her heavy-lidded eyes suggested a fight against profound weariness. “But it would be unfortunate,” she said, “to let our sponsors down, if there was a fighting chance of completing this work. Never mind the downstreamers.” Alertness snapped into her again. Her attention was on me. “Nysa: I can’t take this decision without a comprehensive overview of our engine status. I want to know how the real odds lie.” She paused. “We all accepted risks when we volunteered for this mission. Sculptor has brought us thousands of light years from home, thousands of years of travel from the friends and loved ones we left behind on our homeworlds.”
We nodded. We’d all heard this speech before – it was nothing we didn’t know for ourselves – but sometimes the captain felt the need to drill it into us again. As if reminding herself of what we’d already sacrificed.
“Even if we were to commence our return mission now,” she went on, “at this moment, it would be to homes, worlds, most of us won’t recognise. Yes, they’ll reward our retur
n. Yes, they’ll do all that they can to make us feel welcome and appreciated. But it will still be a kind of death, for most of us. And we knew that before we stepped aboard.” She knitted her fingers together on the table’s mirror-black surface. “What I mean to say is, we have already taken the hardest decision, and here we are, still alive, chasing a neutron star out of the galaxy, falling further from the Commonwealth with every passing second. Any decisions we make now must be seen in that light. And I think we must be ready to shoulder further risks.”
“Then you’ve already made up your mind?” I asked, dismayed.
“No, I still want that report. But if the odds are no worse than ninety percent in our favour, we will stay. We will stay and finish Vashka’s work. And then we will go home with heads high, knowing we did not shirk this burden.”
I nodded. She would have her report. And I hoped very much that the numbers would persuade her against staying.
The neighbourhood of a pulsar, a whirling magnetic neutron star, is no place for anything as fragile as a human being. We should have sent robots, I thought, as I went out for a visual inspection in one of our ridiculously armoured suits. Robots could have completed this work and then self-destructed, instead of worrying about getting back home again. But once Vashka had implanted the idea in their minds, the collective leaders of the Commonwealth had demanded that this grand gesture, this preposterous stab at posterity, be shaped under the guidance of human minds, in close proximity. Ultimately, the Pebble structures might be the last imprint that the human species left on the cosmos. The last forensic trace that we ever existed.
But even this wouldn’t last forever.
Why had we come?
It was simple, really. We knew something, a single cosmic truth, one that we had discovered through patient scientific observation. It was one of the oldest pieces of information known to the species, something so elementary, so easily grasped, so familiar to any child, that it seemed self-evidential.
Before the Commonwealth, before our emergence into space, our ancestors had peered into the night sky. They mapped the starry whirlpools of other galaxies, at first mistaking them for nearby nebulae, formations of spiralling gas. Later, their instruments had shown them that galaxies were in fact very distant assemblages of stars, countless billions of them. And these galaxies were located far beyond our own Milky Way, out to the horizon of observations, out to the very edge of the visible universe. They were also receding. Their light was shifted into red, evidence of a universal cosmic expansion.
Backtracking this expansion, our ancestors deduced that the universe must have emerged from a single dimensionless point of spacetime, less than fourteen billion years ago. With a singular absence of poetry they labelled this birth event the Big Bang.
Quite a lot has happened since that discovery. We have settled interstellar space and spread our influence through a wide swathe of the galaxy. Our science is vastly more sophisticated. We don’t think of the birth event as a ‘bang’ at all, or even an ‘event’ in the accepted sense. But we continue to preserve the notion that our universe was once infinitely small, infinitely dense, infinitely hot, and that there is no sense in which anything can be said to have happened ‘before’ this eyeblink epoch.
Our Earthbound ancestors made this discovery using telescopes of glass and metal, recording spectral light onto silvery plates activated by crude photochemistry. That they were able to do it at all is a kind of miracle. Of course, it’s much, much simpler now. A child, with the right demands, could reveal this truth of cosmic expansion in a single lazy afternoon. The night sky is still aspray with galaxies, and each and every one of them still feels that tug of cosmic expansion.
There’s a catch, though. The galaxies aren’t just rushing away from each other, like the blasted fragments of a bomb. If they were, then their mutual self-gravity would eventually retard the expansion, perhaps even bring the galaxies crashing in on each other again.
Instead, they’re speeding up. Eight billion years into the universe’s life, something began to accelerate its expansion. Our ancestors called this influence ‘dark energy’. They measured it long before they had even the sketchiest understanding of what might be motivating it. Our understanding of the underlying physics would be unrecognisable to them, but we still honour their name. And dark energy changes everything. It’s the reason we came to this miserable and desolate point in space, around a dense dead star that will soon leave the galaxy altogether.
It’s the reason we came to leave Vashka’s message, engraved into the crust of a world made of star-fired diamonds.
I circled Sculptor, taking care to keep away from the banks of gamma-ray lasers that were even now etching Vashka’s patterns. The ship’s orange peel orbit brought it over every part of Pebble eventually, the lasers sweeping like spotlights, and when we were done there would be no part of the planet’s surface that hadn’t been touched. The lasers took the raw diamond of her crust, melting and incinerating it to leave elegant chains of symbolic reasoning, scribed from the sky in canyon-wide lines. The chains of argument formed a winding spiral, quite distinct from the surface track of our orbit. That spiral converged on a single spot on the planetary surface, the entry point to a cavern where the entire statement had been duplicated for safekeeping.
In truth we were finished; had been so for many orbital cycles. What Sculptor was doing now was completing the tidying-up exercise after another uplink from home. We were finishing off the ninth draft, and now home wanted us to begin again on the tenth.
We’d left the Commonwealth with what appeared to be a complete, self-consistent statement of physics and cosmology, encoded in terms that ought to be decipherable by any starfaring intelligence. But by the time Sculptor arrived, the eager minds back home had had second thoughts. A tweak here, an edit there. The first and second drafts had been simple enough, and there’d been no cause for concern. But by the time we were on the fifth and sixth edits, some of us were having qualms. The changes were progressively more sweeping. We’d had to begin almost completely from scratch – lasering the planet back to a blank canvas before starting over, changing our story. As fluent with physics as I was, the level of encoding had long ago slipped beyond my ready comprehension. I had to take Vashka’s word that this was all worthwhile. She seemed to think it was.
But then she would, wouldn’t she? This entire project was Vashka’s idea. Always a perfectionist, she wasn’t going to settle for second best.
The problem was that we couldn’t stay here forever. Which was where my own narrow expertise came in.
For thousands of years we’ve been crossing interstellar space using momentum-exchange drives – long enough that it’s easy to think that the technology is routine and safe. For the most part, that’s exactly what it is. Give or take a few tens of kilometres per second, the stars and planets of the Commonwealth are all co-moving in the same spiral arm, travelling at the same speed with respect to the galactic core. Interstellar transits proceed without incident. We steal momentum from the universe, but we give it back before the universe gets irritated. The net momentum deficit between a ship starting its journey around one star, and the same ship ending its journey around another, is close enough to zero to make no difference. Momentum – and by extension kinetic energy – has neither been created nor destroyed.
But that’s not true here. Because the Pebble and its pulsar are hurtling away from the galaxy at twelve thousand kilometres per second, we haven’t actually stopped. We started off at zero relative to the Commonwealth, and we’re still travelling at a good clip away from it.
Which means that a momentum debt is still waiting to be repaid.
The engines were a dull red when we arrived, but with each day that we delay paying that debt, they glow a little more intensely. That’s the universe reminding us, in an accumulation of microscopic thermal fluctuations, that we owe it something.
Leave it long enough, and the antimomentum cores will undergo catastrophic
implosion.
But that wasn’t going to happen today, or tomorrow, or for months in the future. As much as I’d hoped to find some problem or trend that could be used to justify our early departure, nothing was amiss. The cores were progressing according to expectations. Loimaa’s thousand days might be a stretch too far, but I had to admit that we were good for at least the next two or three hundred. And if and when the cores started deviating, I’d be able to give Captain Reusel plenty of warning.
That didn’t mean I felt easy about it.
Yet I’d turned things over in my head long enough, and knew that twisting the facts, over-stressing the hazards, wasn’t an option. Reusel would see through that in a flash.
As would Vashka.
My suit picked up a proximity signal. I used the thrusters to spin around, in time to see another suit looping out from behind Sculptor. Like mine, it was an upright armoured bottle with manipulators and steering gear. The ident tag told me exactly who it was.
“Come to talk me into lying?” I asked.
“Not at all. I know you better than that, Nysa. You’d never lie, or read anything into the data that wasn’t really there. That would take…” Vashka seemed to trail off, as if her thoughts had carried her in a direction she now regretted.
“Imagination?”
“I was going to say, a streak of unprofessionalism that you don’t have.”
“Yes. I always was the diligent plodder, while you made the wild, intuitive leaps.”
“I didn’t mean it that way.”
“But it’s not too far off the mark. Oh, don’t worry. I’m not offended. It’s basically the truth, after all. I’m very good with fixing engines and making them work a bit better. That’s a rare skill, one worth cherishing. But it can’t be compared with what you’ve done, what you’ve brought into being. No one had ever thought of anything like this before you did, Vashka. It’s all yours.”
“It was a shared enterprise, Nysa.”
Solaris Rising: The New Solaris Book of Science Fiction Page 34