Greg Egan - The Eternal Flame

The tube stayed in place, curled five times around the slowly turning shaft. Carla pulled apart the join between her cooling bag and its supply tank, and interposed the crude timer.

She opened the valve on the air tank slowly, afraid that too much pressure would tear the tube free. She stopped at the point she remembered by touch—well short of fully open, but where she’d last felt enough air flowing across her skin to make some difference. Nothing was coming through the pinch, and there’d been no tell-tale bounce of the tube unraveling.

She was dizzy now, too disoriented to trust herself to check anything she’d done, let alone try to change it. The lights behind her eyelids swarmed and chittered. She tried to picture Carlo, his body pressed against her, but then part of her refused to be fooled or comforted and the image of him spun away into the whiteness.

25

Carla shuddered and vomited a thin sludge into her helmet. She felt as if every scant of her flesh had been pounded with a mallet. She opened her rear eyes and looked down to see blue flames flickering over the gray rocks beneath her. Again? She was about to start buzzing hysterically, before her mind cleared enough for her to realize that the fire didn’t have to be a bad sign at all.

She reached for the clock, afraid that the tube might have become caught in the mechanism and jammed it, but far from being stuck the dials showed a later time than she’d dared to hope for. The Mite had passed its lowest point. She was alive, and she was moving away from danger.

She quickly turned Ivo’s air back on. The flames rose up in response, but she persisted until the heat became threatening, then she cut the flow back a fraction.

Ivo didn’t move. He’d shut off his air long before she had. Carla shivered but refused to start mourning him. A few lapses later the flames went out completely, so she set his cooling bag to full strength. The tube that had saved her life had broken away from the clock shaft and was floating around in front of her in an irritating loop, so she reconnected her tank directly to her bag and stowed the tube inside one of the Mite ’s small storage compartments.

Ivo stirred and began rolling his head, as if trying to unkink his neck muscles. Carla let him be until he opened his eyes and appraised the situation for himself.

He reached for her hand. We’re ascending?

Yes.

He didn’t ask her to explain what had happened. After a while, he took his hand away and began loosening his harness.

Carla’s first instinct was not to intervene; if he’d been injured by the ordeal he might need to move to make himself more comfortable. It was only when he was entirely free of the harness and on the verge of pushing away from the Mite that she understood and grabbed hold of his arm. She was not at her strongest, but he was in no condition to resist her.

She took his hand again.

Better that I die, he wrote.

Carla didn’t know what to say to that, but she resisted the urge to slap him across the head. He’d made an honest mistake that had put them in danger, but they’d both survived. He’d undermined the Gnat ’s chances of capturing the Object, but a future mission could always try again, better prepared. And though his reputation would be marred by this débâcle, he’d still been instrumental in the fact that the Gnat had flown at all.

The contamination was an uncharacteristic lapse. Carla had seen Ivo inspecting the air filters with a microscope, to ensure that there were no tears in them. But if the problem hadn’t arisen through carelessness, what had been its root? A misunderstanding of some kind. Which process was better understood, though: the filtering of dust from air… or the behavior of air in the presence of orthogonal matter?

What if the air is pure?she wrote.

Ivo didn’t dignify that with a reply. There was no better established fact in all of chemistry than the inertness of air. Nobody had a perfect explanation for this, but it had long been conjectured that each particle of the gas was a spherical cluster of luxagens, arranged in such a way that Nereo’s force canceled almost perfectly outside the cluster.

Still, when air bounced against rock it was Nereo’s force that made it bounce. Once an air particle actually made contact with something, the luxagens within couldn’t hide themselves completely. So it wasn’t inconceivable that orthogonal rock could react differently to air built from positive luxagens than it would to its own, presumably innocuous, swapped version. Let everyone on the Gnat and the Peerless share the blame, then, for failing to imagine that possibility.

Carla hadn’t thought to try to get a spectrum of the flames their spilt air had summoned, but she’d have bet anything that the same dominant spectral line as they’d seen before would have been present. Every mineral’s structure was complicated in a different way, and even a particle of air had its own elaborate geometry, but that one line screamed simplicity.

What was the UV frequency?she wrote.

Ivo gave her the wavelength.

No, the frequency.

I have no idea, he replied. His spectrograph was calibrated for wavelengths; it was the convention among chemists to express all their results in those terms.

You can’t work it out?Carla wasn’t so rattled that she couldn’t do it herself, but she wanted to keep Ivo engaged.

He humored her, carrying out the calculations on the patch of skin they shared. The spectral line’s wavelength wasn’t much greater than the minimum wavelength of light. Yalda’s formula put the frequency at near enough to three tenths the maximum; Ivo dutifully multiplied this out to get roughly a dozen and three generoso-cycles per pause.

Carla didn’t care about the final number; it must have been nice for the ancestors that a “pause” was a convenient fraction of the rotational period of the home world, but it had no bearing on anything else in the cosmos. All the real physics was in the pure ratios of numbers, untouched by the whims of history and convention.

The UV line they’d seen in every fire on the Object was three tenths the maximum frequency of light. Every photon of that frequency was traveling at a speed that tilted its energy-momentum vector steeply enough to make it lie at three tenths its original height.

But three to ten was the ratio Patrizia had found, when she’d fitted her curves for colliding particles to the data for light scattering off luxagens. A luxagen’s mass was three tenths the mass of a photon. So every photon in this ultraviolet line possessed the same energy as a stationary luxagen.

What if a luxagen became a photon?Carla wrote.

She could feel Ivo’s body shaking as he buzzed with mirth. Source strength?he replied.

He was right to object; a luxagen carried one unit of source strength, a photon had none. And from Nereo’s equation you could prove with mathematical certainty that source strength could never simply vanish.

Mathematically, though… it could cancel.

One positive luxagen, one negative, Carla suggested. Strictly speaking, the only quantity that had to remain unchanged was the total source strength: the count of positive particles minus the count of negative ones. The individual numbers didn’t need to stay fixed.

Ivo didn’t respond. Carla looked to his face; he appeared to be mulling it over.

She tried to imagine the process. Two luxagens came together, one of each sign… but instead of them simply bouncing off each other, the original particles were destroyed and two photons emerged.