From a hundred-kilometer distance, Rover sent her robot prospector around the thing she had tracked down. The little machine circled close, taking readings, storing data. When behind the sphere, it steered itself, with sufficient judgment to stay well clear of the radiation streaming forth from one site there. Otherwise Saxtorph kept in radio rapport, his computer helping him devise the orders he issued. From time to time the prospector transmitted, downloading what it had gathered. At length Saxtorph had it land on the surface. Capable of hundred-gravity acceleration, the robot could also make feather-soft contact. Presently he ventured to have it apply its dynamic analyzer, attempting sonic, electronic, and radiation soundings plus measurements of several different moduli.
Mostly it drew blank. This material was nothing like the asteroids and moons that it was meant to study. A few experiments yielded values, but with ridiculously large probable errors. Nor was the robot well suited for a tour of inspection. Saxtorph recalled it to his ship.
“At any rate, the side away from the firebeam should be safe for people,” he said. “Okay, I’m on my way.”
‘’ ‘Should be’ isn’t quite the same as ‘is,’ “ Ryan objected.
The captain ignored him. “I could use a partner.” He glanced at Carita. She nodded avidly.
After some unavoidable argument and essential preparations, they left. Saxtorph deemed that taking the boat, a comparatively large and ungainly object, was hazardous. They flitted in spacesuits.
The nearer they drew to the objective, the more the mystery deepened for them. Its horizon arcing across nearly half their sky, the starlit surface became a pitted bare plain on which crouched outlandish bulks, soared skeletal spires, sprawled shadowy labyrinths. Soon Rover seemed as remote as Earth. Breath sounded harsh in helmets, pulsebeats loud in motors, pumps, and bloodstreams.
The man pressed the control for a radar reading. Numbers appeared. He made his command carefully prosaic: “Brake, hold position, and wait for further instructions. I’m going down.”
“I still say I should,” Carita answered. “We can’t spare you.”
“Sure you can, while you’ve got Dorcas.” That was why his wife stayed behind, though he’d had to pull rank to make her do it.
“Your vectors are correct for landing,” she informed him from her post aboard. The ship tracked the flyers with a precision they themselves could not match. Probably he alone heard the tremor in her voice.
It filled Tyra’s: “Be careful, Robert, oh, be careful!”
“Quiet,” Dorcas snapped. She hadn’t wanted the Wunderlander in the circuit. Ryan wasn’t; he kept lookout at the main observation panel. But Tyra had appealed to Saxtorph. Not sniveling or anything; a simple request. When she wanted to, though, she could charm the stripes off a skunk.
“I’m sorry,” she said.
The captain set his thrusters and boosted. Acceleration tugged briefly. As he turned and slowed, giddiness whirled through him. He was used to it, his reflexes compensated, it passed. His bootsoles touched solidity and he stood on the thing.
Rather, he floated. A few tens of millions of tons, concentrated some eight kilometers below him, exerted no gravity worth mentioning. He directed thruster force upward and increased it until he was pressed down hard enough that he could stand or walk low-gee fashion. This adjustment he made most slowly and cautiously, a fraction at a time. Untold ages had eroded the hollow shell, wearing away its strength until a rock traveling at mere KPS could drive a hole through. Of course, that might mean resistance equal to ordinary armor plate, but it might be considerably less, if not everywhere then at certain points; and he could have happened to land at one of those points.
Otherwise the stuff kept unbelievable properties. Measurements taken on the escaping radiation showed what an inferno raged inside. Yet on this opposite hemisphere, a glance at instruments on his vambrace confirmed the findings made by the robot. Nothing was coming off but infrared at a temperature hardly above ambient.
Saxtorph realized he had been holding his breath. He let it out in a gust. His ribs ached, his sweat stank. Why had he undertaken the flit, anyway?
Well, it was irresistible. Nobody felt able to leave without exploring just a little bit more. And after all, you never knew; a search could turn up a clue to Peter Nordbo’s fate.
Saxtorph made for a surrealistic jumble of pipes, reticulations, and clustered globules. Dust, millimeters thick, scuffed up in ghost-wisps wherever his boots struck. After several leaps, he halted. “Okay, Carita, come join the fun. Don’t land, remember. Stay a few meters above and behind me, on the alert.”
“You’re afraid maybe I’ll take a nap?” the crewman gibed. Edged with their luminance, her spacesuit arrowed across the stars.
I suppose we shouldn’t crack jokes in the presence of something ancient and inscrutable, Saxtorph thought. We should be duly awed, reverent, and exalted. To hell with that. We’ve got a job to do. I hope Tyra will understand, when she writes this up.
Of course she will. She’s our own sort. If her whole life didn’t prove it already, the past couple of weeks sure did.
Saxtorph neared the complex. At hover, Carita directed a search beam as he desired, supplementing his flash. Undiffused, the brightness flowed like water over a substance that was not rock nor metal nor anything the humans knew. They both operated cameras as well as instruments, while their suits transmitted to the ship. Saxtorph’s eyes strained.
“I think the microcraters everywhere were formed in the last hundred million years, plus or minus x,” he said. “Otherwise we’d see much more overlap.”
“You’re supposing the construction is older than that, then,” Carita deduced.
“It certainly is,” Dorcas told them from the ship. “The computer just finished evaluating our data on the dust. Isotope ratios prove it’s been collecting for a minimum of two billion years, likely more.” After a moment: “Incidentally, that suggests cosmic radiation isn’t what weakened the shell to the point where impacts started leaving pockmarks and at last a big one broke through. The radiation inside must be mainly responsible. But if it hasn’t done more damage, well, the thing was built to last.”
“Besides,” Saxtorph said, “if I’ve got any feeling for machinery, this bears every earmark of tnuctipun work.”
“How can you tell?” Carita asked. Her words sounded thin. Ordinarily she would have kept silence, except for business and an occasional wisecrack, but the weirdness had shaken her a bit, roused a need to talk. Saxtorph sympathized. “What do we know about the Slaver era? What little the bandersnatchi remember, or believe they do, and what got learned from the thrint that came out of stasis for a short while, before they got it bottled again.”
“That includes a smidgin of technical information, and a lot of thinking has been done about it ever since,” he reminded her. “I’ve studied the subject some. It interests me. Come on.”
He bounded ahead to the next aggregation and examined it as best he cursorily could.
And the next and the next and the next. Time ceased to exist. He drank from his water tube, stuffed rations through his chowlock, excreted into his disposer, without noticing. He had become pure search. Sturdily, Carita followed. She made no attempt to call halt, nor did anyone aboard ship. The quest had seized them all.
Monkey curiosity, Saxtorph thought once, fleetingly. The kzinti would sneer. But they’d examine this too, in detail, till they used up every possibility of discovery that was in their equipment and their brains. Because to them it’d spell power.
The knowledge was chill: It is a terrible weapon.
“I suspect it’s one of a kind,” he said. “Humans and their acquaintances haven’t found any mini-black holes yet, and that hasn’t been for lack of looking. They’re bound to be uncommon.”
“Yes,” Dorcas agreed. “The tnuctipun doubtless came on this one by chance. I’d guess that was after they’d rebelled. They saw how to use it against the Slavers. Otherwise, if they’d built the machine around it earlier, the Slavers would have been in possession, and might have quelled the uprising early on. They might be alive today.”
Carita shuddered audibly. “A black hole ”
It could only be that. Mass, dimensions, radiation spectrum, everything fitted astrophysical theory. Peter Nordbo had recorded the idea in his notes, but he couldn’t reconcile it with the sudden apparition in the heavens. The tumbling shell and the meteoroid gap accounted for that. Perhaps while they were here the kzinti, under his guidance, had found indirect ways to study the interior, the eerie effects of so mighty a gravitation on space-time. But Rovers crew already had ample data to be confident of what it was they confronted.
Burnt out, a giant star collapses into a form so dense, infinitely dense at the core singularity, that light itself can no longer escape its grip. The minimum mass required is about three Sols. Today. In the first furious instants of creation, immediately after the Big Bang, immeasurably great forces were at play. Where they chanced to concentrate, they had the power to compress any amount of mass, however small, into the black hole state. It must have happened, over and over. Countless billions must have formed, a few large, most diminutive.
In the universe of later epochs, they are not stable. Quantum tunneling causes them to give off particles, matter and antimatter, which mutually annihilate. For a body of stellar size, the rate of evaporation is negligible. But it increases as the body shrinks. Ever faster and more fiercely does the radiation go, until in a final supernal eruption the remnant vanishes altogether. Nearly every black hole made in the beginning has thus, long since, departed.
This one had been just big enough to survive to the present day. Applying what theory the ship’s database contained, Dorcas had made some estimates. Three or four billion years ago it was radiating with about half its current intensity. Its mass, equal to a minor asteroid’s, was now packed inside an event horizon with a diameter less than that of an atomic nucleus. Another 50,000 years or so remained until the end.
Carita rallied. “A weapon?” she asked. “How could that be?”
“Your mind isn’t as nasty as mine,” Saxtorph replied absently. His attention was on high lattices, surrounding a paraboloid (?), which grew out of the shell where he stood. Their half-familiarity chewed at him. Almost, almost, he knew them.
“What else could it be?” Dorcas said. “A power source for peaceful use? Awkward and unnecessary when you have fusion, let alone total conversion. As a weapon, though, the thing is hideous. Invulnerable. Open a port, and a beam shoots out that no screen can protect against. At a minimum, electronics are scrambled and personnel get a lethal dose. No missile can penetrate that defense; if it manages to approach, it will be vaporized before it strikes. Sail through an enemy fleet, with death in your wake. Pass near any fort and leave corpses manning armament in ruins. Cruise low around a planet and sterilize it at your leisure.”
“Then why didn’t the tnuctipun win?”
“We’ll never know. But they can only have had this one. That was scarcely decisive. And… the war exterminated both races. Perhaps the crew here heard they were last of their kind, and went elsewhere to die.”
Saxtorph caught Tyra’s whisper: “While the black hole, the machine, drifted through space for billions of years ” The Wunderlander raised her voice: “I am sorry. I should not interrupt. But do you not overlook something?”
“What?” Dorcas sounded edgy. As well she might be after these many hours, Saxtorph told himself.
“How could the tnuctipun bring the weapon to bear?” Tyra asked. “The black hole was orbiting free in interstellar space, surely, light-years from anywhere. The mass is huge to accelerate.”
“They could have harnessed its own energy output to a polarizer system.”
“Really? Is that enough, to get it to a destination fast enough to be useful?”
Smart girl, Saxtorph thought. She hasn’t got the figures at her fingertips, but those fingers have a good, firm, sensitive hold on reality.
“Through hyperspace,” Dorcas clipped.
“Forgive me,” Tyra said. “I do not mean to be a nuisance. You must know more about tnuctipun technology than I do. But I studied what I was able. Is it not true that their hyperdrive was crude? It would not work before the vessel was moving close to light speed. This genstand has ordinary velocity, in the middle of empty space.”
“That is a shrewd question,” Dorcas admitted.
“A real fox question,” Saxtorph said. He was coming out of his preoccupation, aware how tired he was but also exuberant, full of love for everybody. Well, for most beings. Especially his comrades. “It could stonker our whole notion. Except I believe I’ve found the answer. There is in fact a hyperdrive engine. It’s not like anything we know or much like any of the hypothetical reconstructions I’ve seen of tnuctipun artifacts. But I believe I can identify it for what it is, or anyhow what it does. My guess is that, yes, they could take this black hole through hyperspace, emerging with a reasonable intrinsic velocity that a gravity drive could then change to whatever they needed for combat purposes.”
“How, when every ship must first move so fast?” Tyra wondered.
“I am only guessing, mind you. But think.” Despite physical exhaustion, Saxtorph’s brain had seldom run like this. Talking to her was a burst of added stimulation. “Speed means kinetic energy, right? That’s what the Slaver hyperdrive depended on, kinetic energy, not speed in itself. Well, here you’ve got a terrific energy concentration, so-and-so fantastically many joules per mean cubic centimeter. If the tnuctipun invented a way to feed it to their quantum jumper, they’d be in business.”
“I see. Yes. Robert, you are brilliant.”
“Naw. I may be dead wrong. The tech boys and girls will need months to warm over this gizmo before they can figure it out for sure. They better be careful. Considering how well preserved the apparatus is, in spite of everything that the black hole inside and the universe outside could do, I wouldn’t be surprised but what that hyperdrive is still in working order.”
“More powerful than ever,” Dorcas breathed. “The black hole has been evolving.”
“Brrr!” Carita exclaimed. “Knock it off, will you? If the ratcats got hold of it ” She yelped. “But they were here! Weren’t they? How much did they learn? How come they didn’t whoop home to Alpha Centauri with this thing and scrub our fleet out of space?”
“Even taking its time, what a single expedition could find out would be limited, I should think,” Dorcas said. Her tone went metallic. “We, though, the human species, we’d better make certain.”
“Yah,” Saxtorph concurred. He shook himself in his armor. “Listen, I decree we’re past the point of diminishing returns today. Let’s head back, Carita, have a hot meal and a stiff drink, and sleep for ten or twelve hours. Then I have some ideas about our next move.”
“Wow-hoo!” his companion caroled, uneasiness shoved aside. “I thought you’d decided to homestead. Say, ever consider how lucky the tnuctip race was, not speaking English? Spell the name backwards ”
“Never mind,” Saxtorph sighed. “Compute your vectors and boost.”
Bound for Rover, he felt as if he were awakening from a dream. In the time lately past, he had experienced in full something that had rarely and barely touched him before, the excitement of the scientist. It had been a transcendence. How did that line or two of poetry go? “Some watcher of the skies, when a new planet swims into his ken.” Or a new star, small and strange, foredoomed, yet waxingly radiant; and the archeology of a civilization vast and vanished. Now he returned to his ordinary self.
He ached, his tongue was a block of wood, his eyelids were sandpaper, but he rejoiced. By God, he had seen Truth naked, and She took him by the hand and led him beyond himself, into Her own country! It wouldn’t happen again, he supposed; and that was as well. He wasn’t built for it. But this once it did happen.
When he and Carita completed airlock cycle, their shipmates were waiting for them. Dorcas embraced him. “Welcome, welcome,” she said tenderly.
“Thanks.” He looked past her shoulder. How bright was Tyra’s hair against the bulkhead. His brain hadn’t yet stopped leapfrogging. “We’ve got facts to go on,” he blurted. “Knowing what the kzinti found, we can make a pretty good guess at what they did. And where they are. With your dad.”
“O-o-oh ” the Wunderlander gasped.
He disengaged. She sprang forward, seized and kissed him.