The Eternal Flame

by Greg Egan

  He carried the bodies into the airlock with him, slid the door closed and started laboriously pumping down the pressure. A loose edge of the shroud flapped in the surge of air across the confined space as he delivered each stroke. He unreeled a suitable length of the safety rope, engaged the brake on the reel and hooked the rope into his harness. Then he crouched down, braced himself against the outrush of residual air and pulled open the hatch in the floor.

  A short stone ladder rising up beside the hatch made the descent onto the external rope ladder easier. Carlo used four hands on the rungs and held the children in the other two. As his head passed below the hatch the trails of the old stars were suddenly right in front of him—long, garish streaks of color gouged out of the sky—while behind him the orthogonal stars were almost point-like. He glanced down and saw the fire-watch platform silhouetted against the transition circle, where the old stars blazed brightest before their light cut out.

  Carlo descended until he felt the safety rope grow taut. He clung to the children, unsure what he should say before releasing them. This boy should have lived for three dozen years, and died with children of his own to mourn him. This girl should have survived in those children, her flesh outliving every man’s. What was life, if that pattern was broken? What was life, when a father had to plead for an assassin to murder half his family, just to save the rest from starvation?

  So who had failed them? Not their mother, that was sure. The idiot ancestors who squatted on the home world, waiting to be rescued from their own problems? The three generations of agronomists who had barely increased the yield from the crops? But then, what good would it do if the fourth generation triumphed? If he and his colleagues found a way to raise the yield, that would bring a brief respite. But it would also bring more four-child families, and in time the population would rise again until all the same problems returned.

  What miracle could put an end to hunger and infanticide? However many solos and widows chose to go the way of men, most women would rather starve themselves in the hope of having only one daughter than contemplate a regime where for every two sisters, one would be compelled to die childless.

  And if he was honest, it was not just down to the women. Even if Carla, given her say, had proved willing, he would not have been prepared to throw away his chance of fatherhood to raise these children as his own.

  “Forgive us,” Carlo pleaded. He stared down at the lifeless bundle. “Forgive us all. We’ve lost our way.”

  He let the children slip from his arms, and watched the shroud descend into the void.

  2

  Straining against the harness that held her to the observation bench, Tamara cranked the azimuth wheel of the telescope mount. Each laborious turn of the handle beside her nudged the huge contraption by just one arc-chime, and though she still had strength to spare there was nothing to be gained from it: a governor limited the speed of rotation to prevent excessive torques that might damage the gears. The soft, steady clicking of the wheel, usually a reassuring, meditative sound, drove home the machine’s serene indifference to her impatience.

  When the telescope was finally pointed in the direction of her last sighting of the Object, she lay flat on the bench and wriggled into place beneath the eyepiece. As she brought the image into focus she was granted as glorious a vision as she could have hoped for: there was nothing to be seen here but the usual mundane star trails.

  The trails were exactly as Tamara remembered them, so she knew that she hadn’t mis-set the coordinates. Twice now, the Object had escaped the field of view that had framed it just one day earlier. Such elusiveness proved that it was crossing the sky faster than anything she’d seen before.

  Tamara turned the secondary azimuth wheel until she was rewarded with a small gray smudge of light at the top of the field, then she adjusted the altitude to center it. To the limits of the telescope’s resolving power, the Object was simply a point. Nothing in the cosmos was close enough to the Peerless to reveal its width, but even those orthogonal stars that had remained fixed in the sky for three generations showed color trails at this magnification. To possess a point-like image the Object had to be moving slowly—but the only way a slow-moving body could cross the sky as rapidly as this was by virtue of its proximity.

  She ran her fingertips over the embossed coordinate wheels, recorded the numbers on her chest, then computed the angle between the Object’s last two bearings. Symbols blossomed on her forearm as she worked through the calculation. In both of the intervals between sightings the gray smudge had moved about two arc-pauses—but the second shift was slightly greater than the first. The true speed of the Object was unlikely to have changed, so its quickening progress against the background of stars could only mean that it had already moved measurably closer.

  The change was far too small to yield accurate predictions, but Tamara couldn’t resist working through some crude estimates. Within a period perhaps as short as four stints—or perhaps as long as five dozen—the Object would make its closest approach to the Peerless. Just how close that would be was impossible to say, without knowing how fast the thing was moving through the void, but the lack of a discernible color trail put a ceiling on its speed. The upshot was, the Object would pass by at a distance of, at most, nine gross severances. In astronomical terms that was positively propinquitous: about a twelfth the distance of the home world from its star. No living traveler among them had ever been so close to another solid body.

  Tamara resisted the urge to bolt from the observatory and start spreading the news; the protocols dictated that she should complete her shift in the face of anything less than an imminent collision. But it would not be wasted time; the Object could easily be accompanied by fellow travelers, fragments from the same parent body with similar trajectories. So she duly worked her way across her allotted segment of the sky, hunting for another speck of light or a dark silhouette against a star’s band of colors. Field after field was unblemished, as usual, but whenever the tedium of the search reached the point where her thoughts began to stray to the emptiness in her gut, she turned her mind back to the Object itself and savored again the thrill of discovery.

  When she’d done her duty—with no further revelations—Tamara slipped out of the harness and pushed herself through the hatch at the base of the observatory. She drifted across the gap that separated the telescope’s stabilized mount from the imperceptibly spinning rock below, and her momentum carried her into the entrance tunnel, returning her to the Peerless proper. She grabbed a guide rope and dragged herself along to the office. Roberto was there, ready to start his own shift, while Ada was studying for an assessment, poring over a tattered set of notes on the art of navigational astrometry.

  “I do believe we should expect company!” Tamara announced. She gave her fellow observers the three data points and waited while they made their own calculations.

  “It does look close,” Roberto confirmed.

  “How bright is it?” Ada asked.

  “Five,” Tamara said.

  “And you’ve only just seen it?”

  “You know what it’s like, trying to spot things close to the horizon.”

  To Tamara, they both sounded a shade resentful. She knew there’d been no special skill in what she’d done, and her luck would attract no great esteem. But what lay ahead now was open to everyone: the chance to observe a body of orthogonal matter in unprecedented detail.

  “I wish we had some way to pin down the distance,” Roberto lamented.

  “Do I detect a hint of parallax envy?” Tamara joked. On the home world, astronomers had had it easy: wait half a day and your viewpoint moved by the planet’s width; wait half a year and that became the width of the orbit. Once those baselines had been measured, the shifting angles they created had been revelatory. But whether you imagined it was the Peerless itself that was moving day by day, or the Object, without knowing the relative velocity to fix the baseline between successive views the most you could glean from the a
ngles alone was the timing of the encounter, not the distance.

  Roberto hummed with frustration. “This thing might come close enough for us to resolve its shape—and maybe even structural features, impact craters… who knows? Think how much more valuable all that would be if we knew their scale!”

  Ada said, “It sounds like the perfect job for an infrared color trail.”

  “What kind of gratitude is this?” Tamara demanded. “I bring my two friends the find of a lifetime, and all I get are fantasies about how things could be better!”

  Ada was indignant. “What fantasy? I’m serious! The chemists have never made infrared a priority before, because they’ve never had a good enough reason.”

  Chemicals sensitive to ultraviolet light had been known since before the launch, but no one had managed to achieve the same feat at the infrared end of the spectrum. Imaging a slow-moving object’s color trail in ultraviolet wasn’t all that helpful; even infinitely fast UV would lie closer to violet in the trail than violet was to red. But an infrared trail could stretch out to many times the length of the visible portion.

  “And this will count as a good reason?” Roberto was amused. “The last time I asked for a favor from the chemists, I was told to wait until they’d solved the fuel problem.”

  Ada said, “Maybe we can find a chemist who’s itching for a break. If you’ve spent half your life bashing your head against the same old problem, why not try something easier?”

  “No, they all want the glory too badly for that,” Roberto declared. “Who’s going to waste their time inventing infrared-sensitive paper when they might be on the verge of inventing a way home?”

  Tamara tried to put herself inside a chemist’s skin. The Peerless’s reserves of sunstone, burned in the usual manner, would barely be enough to bring the mountain to a halt, let alone carry their descendants back to the home world. She’d understood that unsettling fact since childhood, but to someone who’d made the fuel problem their vocation what interest could there be in the astronomers’ petty concerns? The orthogonal cluster and the debris that surrounded it were just obstacles to be avoided, and while gathering statistics on the distribution of this hazard was a worthwhile activity, it wouldn’t take an infrared color trail to recognize a head-on collision.

  Then again, surely every chemist was at least a little curious as to how the sprinkling of orthogonal dust that had adhered to the surface of the Peerless had threatened to set the rock on fire, in the days before spin. Tamara wondered if she could sell them on the notion that establishing the size of any craters on the Object might shed light on that mysterious reaction. The trouble was, any ordinary rock that had struck the Object would have done so at such a great speed that the most likely result would have been, not a crater, but an all-obliterating fireball. The Peerless itself was almost certainly the only ordinary object in the region that had ended up more or less matching velocities with the orthogonal material—and if a leisurely encounter between the two kinds of matter was ever to be repeated, the Peerless would have to be involved again.

  Tamara looked up at her friends and realized just how blind she’d been. Roberto had been right to refuse to accept the same old regime of half-useless observations; Ada had been right to insist that there could easily be better methods within their reach. But all three of them had been too timid by far.

  Tamara said, “Why don’t we go there?”

  Roberto blinked. “What?”

  Ada emitted an excited chirp. “You mean start the engines and…?”

  “No, no!” Tamara cut her off. “The Peerless is too big and unwieldy, and it would be insane to waste that much fuel. We should build a smaller rocket, just for this journey—something we can take as close to the Object as we dare. Then we can measure what we like, observe what we like… carry out experiments, maybe even bring back samples.”

  Ada held up her navigator’s manual, regarding it with an almost fearful new respect. When Tamara had studied the same notes, she’d assumed that the only use she’d ever make of them would be to teach the theory to the next generation, keeping the knowledge from withering away while they waited for the infinitely remote prospect of commencing the journey home.

  Roberto’s stunned expression gave way to one of pure delight. “If the tiniest speck of orthogonal rock is a liberator for calmstone,” he said, “who knows what the same material in bulk could do to our fuel?”

  Tamara said, “I think we might be able to interest the chemists in helping us find the answer to that.”

  3

  Carla opened the valve at the top of the lamp, allowing a trickle of liberator to fall onto the sunstone. She started at the sudden hissing sound and the dazzling eruption of radiance, and her hand moved quickly to the dousing lever that would bury the flame in sand. But after a moment the noise settled to a steady splutter, and though the beam escaping through the aperture in the lamp’s cover retained its formidable intensity, it appeared to be stable.

  Carla had prepared the liberator herself, extracting the active ingredient from sawflower roots, then diluting it with crushed powderstone, checking the proportions three times and running the mixture through an agitator to be sure there were no clumps. But even these precautions couldn’t assuage her fears entirely. Fire of every kind crossed the Cornelio line into positive temperatures, but the act of igniting sunstone felt like summoning a malevolent creature out of the sagas. It might sit on the bench and amuse you with its tricks, but you knew that what it really wanted was to bring its whole world of bright chaos through the crack you’d opened up between the realms.

  A lens over the lamp’s aperture partly countered the natural spreading of the light. Carla placed a small mirror in its path; mounted diagonally on a pegged holder, it sent the beam straight down through a hole in the bench-top. She knelt and fitted a triangular prism into place to intercept the vertical beam, then she ran an upturned hand through the space below it, to watch the brilliant spectrum glide over her skin. Sunstone disquieted her, but no other source produced such pure, intense colors.

  A robust clearstone container sat on the floor beneath the bench. Apart from the corners, rounded for strength, it was almost box-like in shape, and the gravity here was strong enough to hold it in place by friction alone. At the bottom of the container was a flat rectangular mirror, freshly polished. The spectrum from the prism fell along the length of the mirror, with a thin strip of colors spilling off one edge onto a sheet of gridded paper, making it easy to see the position of every hue. Carla noted the locations of the red and violet ends; some space remained beyond them where the mirrorstone would be exposed to invisible wavelengths. Half of the spectrum reflecting off the mirror showed up on the underside of the bench-top, with the rest reaching an adjacent wall, but Carla felt no urge to contain the spilt light. It was no longer part of the experiment, and the streak on the wall made a cheerful decoration.

  The prism she was using had been calibrated against a light comb by an earlier custodian of the workshop—the neatly written table was dated just a dozen and four years after the launch—allowing her to assign a precise wavelength to each line on the grid. She verified the overall calibration with half a dozen spot checks, then glanced at the clock. Going on what Marzio had told her, and accounting for the strength of the beam, she had planned for an initial exposure of one day.

  Marzio was one of the most respected instrument builders on the Peerless. Four years ago, he’d been asked by the astronomers to construct a wide-field camera that could function in the void, in the hope of capturing sharper images than those taken behind the clearstone panels of the observatory domes. Like most such cameras his design had included a mirror to divert the light path, making it easier to keep the gas that activated the sensitized paper from leaving a residue on the lens. The device he’d built had been successful enough, but when Carla had run into him recently he’d told her something curious: the mirror had grown tarnished more rapidly than the corresponding part in any camer
a he’d built before. This was not what anyone would have expected; the gradual loss of reflectivity in polished mirrorstone had always been attributed to some kind of slow chemical reaction with the air.

  Marzio had speculated that perhaps the activating gas, which seemed to cause no problems with the mirrors in air-filled cameras, was behaving differently in the vacuum—although it still did its job perfectly well. And the tarnish on the mirror, he admitted, bore no signs of being an entirely new phenomenon: it was indistinguishable from the patina that appeared under ordinary conditions. It merely arrived sooner in the absence of air.

  Carla had had no good theories about any of this, but Marzio’s observation had nagged at her. If it wasn’t air that tarnished mirrors, what was it? Exposure to light, or simply the passage of time? It would have been absurd to ask Marzio to build a whole new camera for her to play with, so she’d set up this simple test. To measure the effect of time alone, a second mirror in its own evacuated container had been shut away in a light-proof box.

  Carla stood by the bench, eyeing the lamp warily. She’d had to beg Assunto to approve the use of sunstone, though this handful was nothing to the quantity the Peerless’s cooling system burned up every day. “What’s the purpose of this experiment?” he’d asked irritably. He’d have to justify his decision to the Council in person at the next meeting, so he needed as pithy a summary as possible.

  “Understanding the stability of matter.”

  “And how exactly will a tarnished mirror help with that?”

  “If the surface of a mirror can change in a vacuum,” Carla had argued, “that’s not a chemical reaction, it’s something simpler. If the luxagens in the mirrorstone are rearranging themselves in response to light, that could provide us with a mildly unstable system that we’d have a chance to manipulate and study—”