Artifacts

by Greg Egan

  Rykov says, without much conviction, “I think there’s some kind of liquid crystal in one of the detectors. A highly directional polymer.”

  Zoe says, “Corrosive?”

  “I wouldn’t think so.”

  “Well, this is something else, then.” She shines a beam into a clear patch of “liquid” where it meets the tunnel wall. The wall comes to an end precisely at the surface; the “liquid” continues off to the side, with no sign of even the slightest vestige of what should have been there.

  Rykov says dully, “If they were caught in this, they’re dead.”

  Zoe says, “Maybe. But what the fuck is it?” She reaches into a suit flap and takes out a black marker pen. I say, “Are you sure you—”

  She touches the tip of the pen to the surface. There’s a whipcrack of static on the radio, and a brilliant flash of green light—a line of green light, instantly stretching from the point of contact, far into the depths.

  She jerks the pen back, and the light vanishes.

  I blink at the afterimage, dazed. Rykov swears. Zoe says softly, “No give at all. It felt solid.”

  This is no “chemical,” spilt from one of the detectors; the idea is preposterous. What, then? I hear my own words tumbling out, as if listening from a distance, eavesdropping on myself in a dream.

  “Something must have happened here, last collision. They created an exotic vacuum state in the accelerator … but it didn’t just vanish in a matter of femtoseconds. And it didn’t stay confined to the collision point. Maybe they reached the totally symmetric four-space, and it decayed—but not back into normal space-time.”

  And why should it have? In the particle physicist’s multidimensional landscape of vacuum states, where altitude equals energy, and the map coordinates are all the various properties of the vacuum, the topological and physical “constants” we’re used to are represented by one point in a valley in a far corner of the map—the valley into which the observable universe happened to fall as it cooled, a fraction of a second after the Big Bang. Push a boulder from this valley all the way up to the ultimate peak of the central energy mountain, and then let it go; Why should it fall back to the very same point again?

  Rykov says, “Two spatial and two time-like dimensions? One of the times is aligned with our own; the other, we’re seeing as depth?”

  I make a choking sound that’s almost a laugh. “Maybe. Maybe the matter in there has cooled down enough to condense into ‘atoms,’ and what we’re looking at is some kind of chemical reaction in a two-dimensional gas. And if there’s no apparent change with depth—with the second time-like dimension—that might just be a question of scale. If lightspeed comes into it, a microsecond could stretch for hundreds of metres.”

  I stare at the prismatic swirls, and suddenly recall why we’re here. The matter in there might include the distant remnants of three people.

  Zoe says, “If this was formed straight after the collision, how could the crew end up trapped in there?”

  Rykov says, “Maybe it wasn’t. Maybe it formed after they arrived. Or started off in a smaller region, and suddenly expanded.”

  “Then it might expand again, mightn’t it?” She hesitates, then says, “We’re evacuating, immediately. There’s nobody alive here.”

  Zoe and Rykov turn, but I can’t take my eyes off this awful miracle. Two-dimensional chemistry. Two orthogonal times. I sweep my hand beam across the boiling surface one last time, amazed that our kind of light can cross the boundary and return with information; perhaps at the surface it excites emission of the local form, and vice versa—

  “Wait!”

  “Martin—”

  “Look. At the edge.” Where, just minutes ago, the tunnel wall touched the boundary of the two-space, a gap has opened up. I play the beam around the edge; the width of the gap varies smoothly, from a millimetre or less on one side, to several centimetres at the point diametrically opposite.

  I say, “It must be shrinking.”

  Rykov says, “Or we’re rotating away from it.”

  “What?”

  “OMAF has a slight spin. A three-hour period. If the region didn’t form symmetrically around the collision point, or if it’s drifted off-centre since it formed …”

  “You mean, we’re turning away from the place where it’s furthest from the centre?”

  “I think so. Like … the tide going out, when the Earth’s rotation carries you away from the tidal bulge. Although whether this thing has a bulge, or whether it’s a sphere that’s drifted off-centre …” She gestures helplessly. “Who knows what shape it is?”

  “Three hours. So when the repair crew were here, this might have been on the other side? They might have seen nothing but empty space?”

  Zoe says, “And then what? They found a fucking great hole in the middle of OMAF, and they just wandered in to take a look? Without telling anyone?”

  “Sakharov might have been over the horizon.”

  “You ever heard of relay satellites? And even if they couldn’t get a channel, there are plenty of other people they could have informed.”

  “Yeah—and in a perfect world, no doubt they would have. But maybe they thought they’d leave it until their regular call-in … after they’d found out a few more details. You haven’t reported anything back to Abbas yet, have you?”

  She glares at me, then proceeds to do so.

  I turn to Rykov. “I still don’t understand. There are access tunnels leading in from all directions. If they went in with a decent amount of propellant, they should have been able to make it out … even if the two-space blocked the way, so they couldn’t return by the same route.”

  “Unless there’s something else in there. Another phase besides the two-space.”

  I stare at the widening gap. “Something else? You think so?”

  “I don’t know what the energy density of the two-space is, but it’s hard to believe that it’s precisely the same as our space-time. So creating it must have either used up, or liberated, a great deal of energy—much more than that of the original monopole collision. If it used up energy, what supplied it? If it liberated energy, Where did it go? A different phase, with the opposite energy relationship.”

  I shake my head to clear it. “So the collision just seeded the process, and these two phases grew together out of our vacuum … one with higher energy, one with lower energy … like a see-saw tipping. But then, why’d they stop at this size? Why not keep on growing?”

  She shrugs. “Or—equally—why not cancel each other out, and vanish? I don’t know. There could be surface effects from the interactions at the boundaries, complicating the energy function, favouring a certain size.”

  “So what is the other phase?” The gap is a metre wide now, at its largest. Wide enough to slip through. For the first time in days, my weightlessness is beginning to feel like falling again.

  Rykov says, “If it has a different metric, there’s only one remaining possibility.”

  “You mean an extra spatial dimension—to balance the two-space, with one less? A large, stable region of totally symmetric four-space?”

  Zoe says, “Shit. I’ve lost Franz.”

  Rykov says, “Let me try. Channel one.” I watch her lips move; she repeats his name with increasing frustration.

  Zoe signals to her to stop. “It doesn’t matter. We’re heading straight back. If Martin can drag himself away.”

  It’s clear, now, that the two-space is a sphere, much smaller than the cavity that it’s gauged from the centre of OMAF: I can see it curving away from us, across the width of the tunnel. I shine my hand beam into the void, as if half expecting to see the glint of a suited figure in the distance, but there’s nothing visible at all.

  I say, “Gladly. ”

  As we launch ourselves along the tunnel, Rykov says, “I don’t understand why we’ve lost contact with Franz.”

  Zoe says, impatiently, “It doesn’t matter.”

  I say, “I take back wha
t I said before. I don’t think they would have gone in there. Not all three of them, without a word.”

  Nobody replies. We travel in a white halo, back towards the safety of the bus. Well, no Mercy Dash trash for SciNet’s viewers, after all; just the first glimpse of a different kind of universe. I can almost feel the stored vision inside me, heavy in my gut like an undigested meal.

  Rykov mutters, “Unless there’s something in the way. Blocking the signal.”

  Zoe says, “What are you on about?”

  My blood freezes—but I can’t believe what Rykov’s suggesting. There was no sign of damage between the airlock and the two-space; if the hypothetical bubble of four-space had drifted further from OMAF’s centre, surely it would have carved out its own void?

  What happened to the repair crew, though, if they didn’t go into the central cavity? Did it start with the loss of radio contact with the retransmitters in their bus?

  Rykov starts to fill Zoe in on the argument for a second phase. As we drift up to the tunnel wall, the two of them grab hand holds and bring themselves to a halt. I hit the wall ahead of them with outstretched hands, and bounce awkwardly; the wall is designed to gently absorb the energy of the impact, but my instincts go awry and I end up pushing myself away.

  In an instant, everything vanishes. Darkness, silence, numbness swallow me. I try to cry out, to wave my arms—but I hear and feel nothing, and have no way of judging if I’ve succeeded in moving a limb or making a sound.

  My panic is so ineffectual that it’s difficult to sustain. After a second or two, I find myself observing, almost calmly: I’ve blundered straight into Rykov’s other phase, whatever it is—and one part of the mystery has just been clarified; it gouged no cavity along its path, because ordinary matter can, evidently, drift right through the boundary. Like me. Like the repair crew.

  Well, the walls of the access tunnels seemed to have survived the experience, intact. A good sign. And the repair crew? Not so good. I wait for something to happen—some further dysfunction—and then wonder if I’d actually notice if I was lapsing into imbecility, en route to brain death.

  If this is symmetric four-space, why am I still alive—let alone perceiving the passage of time? In a universe without cause and effect, why haven’t I simply disintegrated into a gas of randomly scattered particles? This part of OMAF clearly didn’t, either—but why not? Have I dragged some trace of the physics of space-time with me? Are the atoms of my body running on sheer “memory,” maintaining a kind of causal momentum? I can’t believe that.

  Unless … I haven’t passed through the boundary, but merely deformed it. Maybe it’s as flexible as the two-space border was rigid. Maybe there’s a bubble of ordinary space-time clinging to me, surrounding me; I’m not in the four-space—I’m merely surrounded by it, like a scuba diver in water.

  In which case, when will I surface? It could be an hour or more before OMAF’s rotation reunites me with my native universe. Can I last that long? I don’t even know if I’m breathing or not.

  And … an hour or more of whose time? Adrift, disconnected, am I still in synch with the outside world? Is my time running at the same rate? Or even in the same direction?

  Fear returns—and then, in glorious symmetry, an explosion of sensation. I sob, gasping for air, flailing for a handhold—but I’m still in the middle of the tunnel.

  I close my eyes and say, “Suit: take me to the wall behind me.”

  It replies enthusiastically, “Yes!” The trimming jets start up—inaudibly, but I swear I can feel the milligees of thrust. I don’t open my eyes until I hear Zoe’s voice.

  “Martin? Are you okay?”

  “I think so.” I’m shaking badly, but I don’t seem to be injured. I look around; I’m almost touching the tunnel wall.

  “Listen to me: keep moving. Don’t try to come back this way. It must be protruding into the tunnel—you seem to have grazed the edge of the bulge. We’re going to back off and wait for it to move out of the way—but you have to go on to the bus.”

  I’m about to reply, but then I look back down the tunnel.

  Just past the point where I left the far wall, there’s a long, glistening object, stretched out towards me. The sides are a silvery white, exactly like the surface of my suit. The object is ten or twelve metres long, but in cross-section, it’s precisely the size and shape of a human body. The end that faces me drives this home, unambiguously: from the walls of the skull, to the two rows of white spots that must be the ribs, to the startling pink fibres of muscle, to the transected coils of the intestines, nestled around an obliquely cut cubic package: an array of high density memory chips …

  I look away. I say, “I’m okay. I’m fine. I understand. I’ll meet you back at the bus.”

  Zoe says, “We’ll—”

  The radio cuts out.

  I glance back one more time. The cross-section is growing smaller—moving closer to the surface of the body. I keep half expecting blood to spurt from the open arteries, but it doesn’t, of course, It didn’t. Nothing has been cut open; this is just an unusual point of view.

  Part of me badly wants to see the end of this—to stay until the slice shrinks to a point and vanishes—but the four-space must be encroaching further into the tunnel, and I doubt that I’m clear of its path.

  I move on.

  When Zoe calls in on the radio, I almost cry out with relief. Abbas grins unsteadily; I’m not sure if he can yet quite bring himself to believe a word of what we’ve told him. Minutes later, they’re in the airlock; seconds later, safe on board.

  Rykov says, frowning, “Visible light and matter could get through—but not radio. I wonder if it’s a question of energy density, or length scale.”

  I shake my head dumbly. “I wouldn’t know.”

  On the trip back, an awkward silence descends. No one wants to speak of the fate of the repair crew—but I think I know what must have happened.

  Like me, they must have stumbled into the four-space. The space-time they dragged with them would have kept them alive, for a while—but where I did little more than graze the surface, they must have plunged right into the depths.

  They might even have survived—if all they’d had to do was stay alive as they drifted down the tunnel, waiting for their forward motion to carry them out of danger. But they lost … direction. Cut off from the rest of the universe, immersed in a space where all dimensions were the same, their local time coordinates swung out of alignment with the outside world. Like divers whose buoyancy carried them, not up, but sideways. In ordinary space-time, a straight line is the longest path between two points; travel to a distant star and back, and you age less than if you’d “travelled” the straight world-line of staying at home. In four-space, though, as in three-space, any detour can only add to the “distance.” Wandering back and forth at random, on their way between entering and emerging from the region—two events, externally; maybe thirty or forty seconds apart—their path might have added up to anything.

  Minutes. Hours. Days.

  I catch Zoe watching me, uneasily; she manages a thin smile, then looks away.

  I close my eyes—and see again my own bundle of “world-lines,” the trail of my brief ordeal stretched out behind me. And I wonder …

  Where was I, at that moment? Outside the four-space, looking back—or in there, still blind, still disoriented, still waiting to surface?

  How can anything really be over—when “the past” is, visibly, nothing more than another place? Was that nothing but an illusion, a confusing aberration … or was it a glimpse of the deeper truth?

  I open my eyes, and tap Rykov on the shoulder. She turns.

  “This may sound like a stupid question—but I’d really like to know which way is down.”

  DUST

  I open my eyes, blinking at the room’s unexpected brightness, then lazily reach out to place one hand in a patch of sunlight spilling onto the bed from a gap between the curtains. Dust motes drift across the shaft of l
ight, appearing for all the world to be conjured into, and out of, existence—evoking a childhood memory of the last time I found this illusion so compelling, so hypnotic. I feel utterly refreshed—and utterly disinclined to give up my present state of comfort. I don’t know why I’ve slept so late, and I don’t care. I spread my fingers on the sun-warmed sheet, and think about drifting back to sleep.

  Something’s troubling me, though. A dream? I pause and try to dredge up some trace of it, without much hope; unless I’m catapulted awake by a nightmare, my dreams tend to be evanescent. And yet—

  I leap out of bed, crouch down on the carpet, fists to my eyes, face against my knees, lips moving soundlessly. The shock of realization is a palpable thing: a red lesion behind my eyes, pulsing with blood. Like … the aftermath of a hammer blow to the thumb—and tinged with the very same mixture of surprise, anger, humiliation, and idiot bewilderment. Another childhood memory: I held a nail to the wood, yes—but only to camouflage my true intention. I was curious about everything, including pain. I’d seen my father injure himself this way—but I knew that I needed firsthand experience to understand what he’d been through. And I was sure that it would be worth it, right up to the very last moment—

  I rock back and forth, on the verge of laughter, trying to keep my mind blank, waiting for the panic to subside. And eventually, it does—laced by one simple, perfectly coherent thought: I don’t want to be here.

  For a moment, this conclusion seems unassailable, but then a countervailing voice rises up in me: I’m not going to quit. Not again. I swore to myself that I wouldn’t … and there are a hundred good reasons not to—