Wil McCarthy - The Collapsium

The staircase widened at the last, doubling and tripling its breadth before opening, finally, to a flattened, roughly circular depression at Skadi’s summit, some thirty meters across. The rock into which it was sunk formed a waist-high wall all around, broken by sheets into rough-smooth pastry layers. To the southwest, the twilight was brighter; Bruno hurried in that direction, crowding up against the wall, looking out toward the sun, hidden by miles of cloud and miles more of rock.

And there, standing nearly vertical in the sunset glow, was the Ring Collapsiter, barely visible as a filament of blue-green Cerenkov light, not quite a line but the peak of an arch; two very fine lines rising together to join at the top. Like the stars themselves, too small and distant to see as objects; this was a sort of stretched pinpoint, a brightness without dimension, but not without structure. Marlon’s promised crenellations were quite apparent, though subtle: little scallopy waves in the smoothness of the ring, and smaller waves scalloping those, placing each of the structure’s millions of collapsons into one of gravity’s infinitely many vibrational nodes, making it a stable, eternal structure. In theory.

Again, he was struck by the beauty of the thing, by the sheer elegance of function cast into form. Would future generations perceive its marvel, its grace? Would it slide into mundanity, one more work of engineering fading into civilization’s background, like cabling and sewer pipes? The very thought made him angry.

And then it struck him: he was doing it too, presuming a future for this thing, for the people whose lives it threatened. He, too, presumed unconsciously that this problem would be solved. And that was interesting, because he’d never presumed, for example, that the Earth could be towed to a warmer orbit to thaw its frozen regions, or that wellstone iron could magically change to atomic iron, or that one fine day, people would all cease being rotten to each other. Bruno prided himself on a good sense of which problems were and weren’t tractable, and this one—the fall of the Ring Collapsiter—apparently passed the test.

So what did his subconscious know that he himself did not? What had it been doing, while he was off barfing into cups and whatnot?

“There it is,” Marlon Sykes said, pointing vaguely. “In all its glory. You can even see Her Majesty’s superreflectors, little white dots all around.”

Bruno peered, squinted, and decided Marlon was right. The pinpoints were faint, much fainter than the collapsium itself. They were yellow-white, like sunlight, and they hovered outside the ring at various distances, sunlight pushing them away as fast as they could be lowered into place. In fact, a few of the more distant dots were moving with just-barely-perceptible speed.

“Hmm,” Bruno agreed. “Yes. Interesting. How big are the sheets?”

“Not large. A hundred meters.”

“Hmm,” Bruno said again, nodding slowly and pinching his chin. “Enough to wrap around the torus, like tape around the rim of a steering wheel. Goodness, if the ring were solid, we’d have no problem, would we?”

And then the world stopped. He drew a slow, reeking breath, filling his lungs, and then released it slowly, loudly, in an extended sigh. Because that was it. Because by God, that was bloody well it .

“They’re wellstone sheets?” he asked excitedly. “Thin and flexible, but able to be rigidized quickly?”

“Uh, affirmative,” Marlon said, noting Bruno’s change of mood with less-than-complete certainty. The resentment, Bruno saw, hadn’t really vanished. It was just better hidden.

“So we wrap them around!” he said, excited anyway, anxious to share the insight. “Send it home in a cast , letting sunlight and solar wind do the lifting for us! If the inertia is still too great, which I’m sure it is, we erect solar sails, hundreds of kilometers wide, to collect the necessary force. With perfect reflection, momentum should build fairly rapidly, at least as compared to the alternative. It should provide enough time for your additional grapples to be built and placed, to stabilize the structure. It should; I believe it will!”

“Uh, Declarant,” Sykes said, hesitantly and with visible reluctance, “the collapsiter is made of black holes. Universal superabsorbers. They’ll devour the wellstone sheets; we have no way to prevent this.”

“Indeed!” Bruno agreed, doffing his cap. “Indeed. But devour them how quickly? The holes are far narrower than a silicon nucleus. Semisafe, yes? Statistically, some erosion is bound to occur— bound to—but any resulting damage could be repaired locally, without interrupting the overall process.”

He thrust his fist against the top of his hat, thinking to burst it out, to create a model with which to demonstrate. The hat proved tougher than it looked, though. He punched it harder, with no better result.

Sykes glanced down at the hat and back up again, as if doubting Bruno’s sobriety. “Sir,” he said tightly, “the space between the silicon atoms is enormous compared to the size of a neuble-mass black hole. At best, the collapsium will pass right through.”

Bruno punched his hat again, aware that a crowd was building steadily all around, conscious of the weight of their collective gaze. “Will it, Declarant? After sucking electrons off the wellstone’s surface? The nuclei, being positively charged, will be attracted directly to the collapson nodes, blocking them partially, all but plugging them.” He looked at the hat, still good as new in his hands. “Blast. Look, you: I’m trying to remove your top.”

At that, to his astonishment, the hat’s crown separated all around, and fluttered end over end to the ground, leaving a flat ring of leather in his hands, a broad disc with a head-sized hole through its center.

Blinking, he said to it, “Er, assume a toroidal cross-section, please.”

Obligingly, the hat shrank one way and fattened the other, inflating to a kind of oversized, black leather donut in his hands. Still a bit surprised, he held this up for Marlon’s inspection.

“Imagine this as your Ring Collapsiter.” He held up a hand beside it, palm flat, fingers together. “This is your sheet of superreflector. When you wrap the one around the other—” He demonstrated by slowly grabbing the donut.“—and then rigidize it—” He tensed his fist.“—what you’re doing, effectively, is balancing a sheet of joined marbles on a bed of… I don’t know… small drains with tremendous suction behind them. Yes, each of your big marbles is really fourteen drain-sized marbles, and yes, the substance of the drains is somewhat pliable. Wait long enough, and despite the energy barriers their mouths will pull protons right off the nuclei, widen, pull some more, widen some more… But they won’t get big enough to suck whole marbles down, not in the time frame that concerns us. So the erosion will be slow, and the collapsium’s mass gain negligible. If there’s damage, we’ll just snip those collapsons out and replace them. It ought to work.”

Did Marlon’s face grow pale? In the twilight it was difficult to be sure.

“Good Lord, Bruno. I believe you’re right.”

“I haven’t tried the math, of course. I’m guessing.”

“As you guessed before? Phooey. I’ll begin the computations in the morning, and then we’ll know for certain. But at this point, I’d say you’re well within the bounds of decorum to leap and prance and shout ‘Eureka!’ You’ve banished my doubts, and that’s no mean accomplishment.”

Eureka. Hmm, well. With his Greek-philosopher haircut fluttering in the breeze, Bruno had no doubts how ridiculous that would look. Should he run naked down the stairs as well, carrying the Archimedes impersonation to its logical conclusion? Conscious of the news cameras at his back, framing his silhouette against the changeless sunset, he instead cocked his hand back and snapped it forward, sailing the leather donut of his hat out into the empty air, in the general direction of the Ring Collapsiter.