by Greg Egan
You could always keep asking why. The succession of explanations and rules had to be either infinite, or circular—and yet somehow matter, logic, and however many levels of metalogic there were, still managed to get things done.
Watching the surveyor probing the ground, I was sure that I didn’t want Elena to become wealthy, to stop trading, to anchor us to a single world. I didn’t want our lives to change at all.
But I couldn’t help half wishing for a chance to touch the solid reason why the universe made sense.
By the fifth site, Elena was so defiantly cheerful that I couldn’t bear to look her in the eye. By the sixth, I was desperately trying to think of something I could say to cushion the blow—although I knew that anything I said would sound insincere.
When the surveyor announced its final negative verdict, Elena ordered it into its bay, and marched into the ship without a word to me. I followed at a prudent distance—but not so prudent as to risk being left behind.
In the control room, I found her sitting at the main console—but she was looking at a gravimetric map of the Rock, not plotting our next jump.
She mused, “If it’s buried deep enough—deeper than Chalmer’s version—it could be hard to detect from the surface.”
I said, “Buried how? It would have blown the whole asteroid apart before it dug a hole that deep.”
“It might have started off close to the surface of a smaller body. One of the bodies which eventually aggregated into this.”
I put a hand on her shoulder. “No, Elena. Think about it. In Chalmer’s version, the deposit was near the surface of a body the size and shape of this one. If you’re going to say that the impact might have occurred on a completely different asteroid, that’s true … and that asteroid might have ended up part of a larger one. But why should the final resting place of the deposit end up looking the same, with two such different scenarios?”
She stared at the map in silence. I wanted to tell her that it just didn’t matter, that our lives were fine as they were, that the best thing by far would be to forget that we’d ever heard of Chalmer’s Rock. Write it off.
She said, “There’s some kind of cave system here.”
“Asteroids don’t have caves.”
“Call it what you like.” She pointed to a pale blue zone on a hypothetical section through the Rock, close to one of its rotational poles. “The lower limit on the density is zero. There’s an extensive hollow region here, however it formed.”
Gravimetric maps are full of ambiguities; the external field of a body isn’t enough to reveal the precise mass distribution. Still, according to the mapping software, constrained by some plausible assumptions, Elena was probably right.
She traced the extent of the blue zone with her finger, following it to greater depths, and greater uncertainties. “It could go for tens of kilometres. If we collected data from in there, we’d have a far better picture of the whole Rock.” She turned to face me squarely. “Isn’t that right?”
I sighed. Obtaining more data was pointless. The Rock had no secrets to yield; I was sure of that.
But I’d never gone spelunking on an asteroid before. We were here for one and only one visit; it seemed a waste not to make the most of it.
And if this was what it took to make Elena understand that her search was in vain, then it would be time well spent.
The entrance was a hole about ten metres across, but the cavern beneath spread out rapidly to five or six times that width, before narrowing again: a near-spherical bubble, sliced open at the top. We descended, harnessed to a polymer cable unwinding from a winch I’d anchored to the rock with nanoware glue. Elena, a few metres below me, carried a portable surveying unit, constantly logging gravimetric data; I had a backpack full of pulleys for the cable, with my hands free to work the remote control of the winch. We could have gone in untethered, using helium jets alone—the gravity was so low that we needed occasional bursts from the jets pushing us down to make reasonable headway—but going ballistic in the bowels of an asteroid might have been a little rash, and I liked the security of a tangible connection to the surface.
The walls of the cavern were the same greyish-red as the rocks around the entrance. I’d hooked a light bulb to the cable just above me, the underside shielded so as not to dazzle us, and there was a second one below Elena, shielded on top. Everything around us was illuminated starkly; no shadows, no surprises.
Long before we reached the floor of the cavern, it was clear that there was an opening in it, about half the size of the top entrance, and some distance off-centre. When we touched down, I anchored two pulleys in the rock—one directly below the entrance hole, the other cantilevered over the centre of this second opening—and guided the cable onto them.
We descended into another spherical cavern, larger than the first. Below us was yet another opening. What was this? The fossil of a chain of intersecting bubbles, formed by gas coming out of solution in molten rock a billion years ago? My lithochemistry was hazy; I didn’t really know if that was plausible or not.
I said, “This is something, Elena. This just about makes it worth being here.”
She said, “We need to go much deeper than this, before we’ll get any useful data.” She stared at the screen on the surveying unit, which displayed an updated gravimetric map. “We’ll have to go down three or four kilometres, at least.”
Three or four kilometres sounded optimistic; we weren’t carrying the means to blast our way through if we met with any obstructions. I kept waiting for us to hit a dead end, to reach the last cavern, but it seemed there was always one more, scarcely different from the ones before it—although the walls grew smoother, less rocky, more metallic-looking. By the seventh cavern, the cable told us we were five hundred metres deep, and the surveyor still read hollow space beneath us. I pictured a chain of bubbles stretching on down to the centre of the Rock, eighty kilometres below.
The eighth cavern was different, though.
The hole in the floor of the eighth cavern was dead centre, perfectly circular—and it didn’t lead into a ninth. It was the top of a vertical shaft, a smooth cylindrical tunnel, which plunged straight down as far as we could see.
It was, almost certainly, an artefact. I was astonished—and delighted—but Elena looked crushed. Finally, she said, “Miners. Someone’s been here before us. Someone’s beat us to it.”
“You think so?”
She laughed miserably. “Of course!” She crouched down and ran a finger along the tunnel wall, pressing hard to feel the surface texture through the nerveless layers of her exoskin. “You think some natural process made this?”
I said, “If it’s a mine shaft, where are all the tailings?”
“I don’t know. Maybe they pumped them up to the surface, took them away to be refined somewhere. To extract every last fragment.”
We stood at the edge in silence. I thought: Now that she knows that someone else besides Chalmer struck logic, she’s never going to stop searching, she’s never going to stop coming back.
She said, “We might as well go down a bit and check it out. There could be some clues as to who it was, how they worked. What they found.”
I hesitated, then nodded. I set up two more pulleys, to keep the cable running smoothly, and then we began our final descent.
No two civilizations perform the same task in quite the same way. If we’d found anything of value, we would have seeded the Rock with nanoware replicators, and then stood back and let them digest and separate the entire asteroid … but some cultures consider replicators too dangerous to use, even in the middle of nowhere in a universe you’re certain never to visit again. Mining by boring through the rock with macroscopic machinery seemed quaint, but it wasn’t unthinkable.
Of course, the tunnel might have been purely exploratory, rather than extractive—dug for the sake of data collection … which revealed that the Rock had nothing worth taking. There was no evidence that any mining had gone on here; no cross
-shafts full of discarded machinery, no evacuation instructions in incomprehensible languages. Just the one, unmarked vertical shaft, looking as if it went down forever.
A kilometre below the surface, I said, “Elena, this is crazy. We’re not going to find anything. And even if we did, it would be no more use to you than Chalmer’s log.”
She said, “Do you see that?”
I hit the STOP button on the controller, and the brakes brought us smoothly to a halt. “Do I see what?”
“On the wall.”
At first, it looked the same as ever to me; a dull metallic red-grey. Then I raised my hand to block the harsh light, and in the penumbra of its shadow, I made out a glistening, transparent patina, like a thin coating of ice.
I didn’t dare touch it. “Is that it? Logic?”
Elena said, “I don’t know. Logic crystals are blue, in bulk—but a thin layer might not show the colour.”
I absorbed that, then said, as gently as I could, “Then how do we know it’s not just frozen volatiles?”
She took an infrared spectroscopy probe from her backpack, and aimed it at the wall.
“What does it say?”
“Unidentified. It’s not any kind of ice.”
“Unidentified? But the logic spectrum is—?”
She looked up at me. “Known? On file? Of course. If it’s unidentified, it isn’t logic.”
“So … we’ve found a completely novel molecule?”
That seemed unlikely—although perhaps the would-be miners had left a trace of some organic substance peculiar to their own adapted metabolism. “What now?”
“Let’s go down a bit further. Slowly. See how far it extends. Whatever it is.”
I started the cable unwinding again. I thought: The probe is broken—or confused by the thinness of the layer, or conflicting spectra from the rock beneath. The wall is coated with methane, carbon dioxide, water—nothing more exotic than that.
I was wrong. As we descended, the substance took on colour; it started as a faint, uncertain tinge, then suddenly deepened into a vivid emerald green, strong enough to mask the colour of the rock. We stopped, so Elena could use the probe again—but the reading was unchanged.
I stared down the tunnel; still no end in sight. The green colour seemed to fade out just beneath us, though, giving way to the usual red-grey.
We continued—and the wall around us remained emerald green. A few metres below us, the tunnel appeared to be uncoated—but if I fixed my gaze on a point on the wall, its colour seemed to change as we approached it, and by the time it was level with my eyes it had taken on the same hue as we’d seen for the last twenty metres.
I pointed this out to Elena.
“Yes, I noticed. It must be some optical effect in the crystal—the colour depends on the angle of view.”
“But … look above us! At the same angle to the surface, in the other direction, it still looks green!”
Elena looked up, then shrugged. “I don’t know, Khali. I expect it’s some trick of the light.” She sounded tired and dispirited. None of this had anything to do with the reason she was here; it was all just an annoying, confusing distraction.
I was baffled, but I couldn’t think of a serious explanation. I laughed. “Maybe we’re exuding the stuff. Maybe our exoskins are leaking—and this is nothing but frozen perspiration.” Elena ignored the joke; nothing I could say would cheer her up.
Soon after that, the emerald green gave way to a stretch of bright cherry red—not remotely like the rusty ferrous colours of the surface rock—and then, in rapid succession, bands of indigo, yellow, a darker green, a startling azure. Each time we stopped to investigate, the probe declared the substance unknown. The tunnel below still looked like bare rock—until we reached it—but above us was a strange mineralized rainbow, vanishing into the darkness.
When the coating changed to a glistening silver, it hardly seemed worth pausing, yet again; I was ready to sail right through, eager to reach the end of the tunnel, still hopeful that the miners, or whoever, might have left some interesting machinery behind.
Then Elena said, “Khali, do you see—?”
I hit the brakes.
The thin silver layer on the tunnel wall was growing before our eyes. Feathery needles appeared on the surface, branching out, thickening and overlapping until they formed a solid substrate, upon which the whole process began again. It was like a crystalline mass coming out of solution—but out of solution from what? I racked my brain for some half-sensible explanation. A transparent organometallic gas filling the tunnel, breaking down and depositing solid magnesium or aluminium? Gas coming from where? Some machine at the bottom of the tunnel, which had just happened to spring a leak as we arrived?
Even as I rotated my harness and reached out to touch the growing encrustation, my next guess was: replicators, after all? The thought came too late for me to pull back, though; before I could think seriously about the perils of coming into contact with an unknown culture’s nanoware, I’d grabbed a handful of the fine silver needles, and—
A wave of bittersweet hope flooded through me. Elena’s insane pursuit of Chalmer’s lode across the multiverse, her need to have this unreachable goal hovering forever on the horizon, suddenly made the most compelling sense.
I understood—
I let the crystals drop from my hand.
And the electrifying clarity of sharing Elena’s private logic fell away with them.
I cried out in surprise, but I couldn’t speak. My heart raced. I stared at the glittering mass condensing out of the vacuum onto the wall, precisely where we hung, and nowhere else; thickest and fastest around Elena—What had happened here? Something had struck this version of the Rock. Something much stranger than Chalmer’s find. Something more primordial. It had ricocheted eight times within the rock, blasting out the caverns above us, before forming this.
A place where hope could solidify like logic.
And what else? What else within us had been reified? What coated the walls above us? I looked up at the crystalline rainbow we’d left in our wake, chromatograph of our souls.
Elena said, “Khali, we have to move. Quick, take us up!”
I heard her, but I was still in a daze. Our souls? Our brains were matter, nothing more; hope was a property of a system of neural pathways, ultimately explicable in terms of the simplest laws. But … if matter could form such elaborate structures, perhaps logic could too. Levels of explanation corresponding to the emergence of “higher” laws.
I turned and gazed into the depths of the tunnel. Down there, what would be reified? Consciousness? Simpler animal drives? Organic growth? Finally, pure inanimate logic itself?
It was a horrifying prospect—but a strangely seductive one, too. Everything was a thing, after all; everything that made a difference. I said, “Take us up? No, take us down! We don’t have to look for the mother lode any more. We can become the mother lode!”
Elena, thankfully, didn’t understand what I meant. If she had, she might have found the suggestion tempting.
Instead, she hoisted herself up the cable, hand over hand, grabbed the control from me, and hit the button to winch us up.
I was hysterical and incoherent most of the way back to the surface. As we passed by the other layers, I tried to reach out and touch them—to discover what they were—but Elena pinned my arms to my side, and talked about abandoned mining replicators; mutated, unpredictable. I tried to tell her what I believed had happened, but I doubt that anything I said made the slightest sense. She hurried me across the floor of each cavern, deftly tugging the cable free and leaving the pulleys behind.
And outside the ship, it finally hit me: we’d left part of ourselves behind, too. Reasons, motives, emotions; whatever the arrangement of neurons inside our skulls, the mental phenomena they gave rise to had taken another—equally tangible—form in the tunnel. If manipulating primitive, solid logic could break the laws of physics, what would happen if we were separated from
the reified abstractions of our own minds?
I said, “We have to go back. Scrape it all off. Take it with us.”
Elena said, “You’re delirious. You’re infected.” She held me by the wrists, glancing with horror at my right hand.
I laughed. “You think I’m swarming with nanomachines? Then don’t take any risks. Leave me here.”
“Don’t be stupid, Khali. Come into the ship and get treated—”
“It’s not worth the risk, is it? I might contaminate everything. Leave me. Go make a jump. Leave me behind. I’ll live. Go find Chalmer’s lode. If you still want to.”
If you still want to.
I was a child. I was thirteen years old. I was in shock, I was hysterical. I didn’t know what I was doing—or at least, I could hardly be sure.
I pulled free. “I’m not getting into the ship. I’m staying.” I backed away, but not far. And I didn’t turn and run.
Elena said quietly, “Do what I say.”
I took a step backwards, not quite out of her reach, then said, “Do you really think you can make me?”
Elena gave no warning—or if she did, I managed to blind myself to it, because I know I didn’t flinch. She moved in a blur; punching me in the face, knocking me to the ground. The exoskin over one cheekbone ruptured, spraying red mist in front of my eyes. It must have resealed in less than a second, but by then I’d lost consciousness—and given up any chance of explaining what she’d be leaving behind.
WANG’S CARPETS
Waiting to be cloned one thousand times and scattered across ten million cubic light-years, Paolo Venetti relaxed in his favorite ceremonial bathtub: a tiered hexagonal pool set in a courtyard of black marble flecked with gold. Paolo wore full traditional anatomy, uncomfortable garb at first, but the warm currents flowing across his back and shoulders slowly eased him into a pleasant torpor. He could have reached the same state in an instant, by decree—but the occasion seemed to demand the complete ritual of verisimilitude, the ornate curlicued longhand of imitation physical cause and effect.
