Arthur Clarke - Imperial Earth

“It’s the only logical time to shut down the Drive,” he had explained. “Between zero zero and zero four, all the passengers will be in their cabins, er, sleeping. So there will be a minimum of disturbance. We couldn’t close down during the day—remember, the kitchens and the toilets will be out of action while we’re weightless. Don’t forget that! We’ll remind everyone in the late evening, but some idiot always gets overconfident, or drinks too much, and doesn’t have enough sense to read the instructions on those little plastic bags you’ll find in your cabins—no thanks, Steward, I don’t feel like soup.”

Duncan had been tempted; Marissa was beginning to fade, and there was no lack of opportunity. He had received unmistakable signals from several directions, and for groups with all values of n from one to five. It would not have been easy to make a choice, but Fate had saved him the trouble.

It was a full week, and Turnaround was only three days ahead, before he had felt confident enough of his increasing intimacy with Chief Engineer Mackenzie to drop some gentle hints. They had not been rejected out of hand, but Warren obviously wanted time to weigh the possibilities. He gave Duncan his decision only twelve hours in advance.

“I won’t pretend this might cost me my job,” he said, “but it could be embarrassing, to say the least, if it got around. But you are a Makenzie, and a Special Assistant to the Administrator, and all that. If the worst comes to the worst, which I hope it won’t, we can say your request’s official.”

“Of course. I understand completely, and I really appreciate what you’re doing. I won’t let you down.”

“Now there’s the question of timing. If everything checks out smoothly—and I’ve no reason to expect otherwise—I’ll be through in two hours and can dismiss my assistants. They’ll leave like meteors—they’ll all have something lined up, you can be sure of that —so we’ll have the place to ourselves. I’ll give you a call at zero two, or as soon after as possible.”

“I hope I’m not interrupting any—ah—personal plans you’ve made.”

“As it happens, no. The novelty’s worn off. What are you smiling at?”

“It’s just occurred to me,” Duncan answered, “that if anyone does meet the pair of us at two o’clock on the morning of Turnaround, we’ll have a perfect alibi...”

Nevertheless, he felt a mild sense of guilt as he drifted along the corridors behind Warren Mackenzie. The weightless—but far from sleeping—ship might have been deserted, for there was no occasion now for anyone to descend below the freight deck on Level Three. It was not even necessary to pretend that they were heading for an innocent assignation.

Yet the guilt was there, and he knew why. He was taking advantage of a friendship for secret purposes of his own, by suggesting that his interest in the Asymptotic Drive was no more than would be expected from anyone with a scientific or engineering background. But perhaps Warren was not as naïve as he seemed; he could hardly be unaware that the Drive posed a threat to the entire economy of Duncan’s society. He might even be trying to help, in a tactful way.

“You may be disappointed,” said Warren as they passed through the bulkhead floor separating Levels Three and Two. “There’s not much to see. But what there is is enough to give some people nightmares—which is why we discourage visitors.”

Not the most important reason, thought Duncan. The Drive was not exactly a secret; there was an immense literature on the subject, from the most esoteric mathematical papers down to popularizations so elementary that they amounted to little more than: “You pull on your bootstraps, and away you go.” But it would be fair to say that Earth’s Space Transportation Authority was curiously evasive when it came down to the practical details, and only its own personnel were allowed on the minor planet where the Drive was assembled. The few photos of Asteroid 4587 were blurred telescopic shots showing two cylindrical structures, more than a thousand kilometers long, stretching out into space on either side of the tiny world, which was an almost invisible speck between them. It was known that these were the accelerators that smashed matter together at such velocities that it fused to form the node or singularity at the heart of the Drive; and this was all that anyone did know, outside the STA.

Duncan was now floating, a few meters behind his guide, along a corridor lined with pipes and cable ducts—all the anonymous plumbing of any vehicle of sea, air, or space for the last three hundred years. Only the remarkable number of handholds, and the profusion of thick padding, revealed that this was the interior of a ship designed to be independent of gravity.

“D’you see that pipe?” said the engineer. “The little red one?”

“Yes—what about it?”

Duncan would certainly never have given it a second glance; it was only about as thick as a lead pencil.

“ That’s the main hydrogen feed, believe it or not. All of a hundred grams a second. Say eight tons a day, under full thrust.”

Duncan wondered what the old-time rocket engineers would have thought of this tiny fuel line. He tried to visualize the monstrous pipes and pumps of the Saturns that had first taken men to the Moon; what was their rate of fuel consumption? He was certain that they burned more in every second than Sirius consumed in a day. That was a good measure of how far technology had progressed, in three centuries. And in another three...?

“Mind your head—those are the deflection coils. We don’t trust room-temperature superconductors. These are still good old cryogenics.”

“Deflection coils? What for?”

“Ever stopped to think what would happen if that jet accidentally touched part of the ship? These coils keep it centered, and also give it all the vector control we need.”

They were now hovering beside a massive—yet still surprisingly small—cylinder that might have been the barrel of a twentieth-century naval gun. So this was the reaction chamber of the Drive.

It was hard not to feel a sense of almost superstitious awe at the knowledge of what lay within a few centimeters of him. Duncan could easily have encircled the metal tube with his arms; how strange to think of putting your arms around a singularity, and thus, if some of the theories were correct, embracing an entire universe...

Near the middle of the five-meter-long tube a small section of the casing had been removed, like the door of some miniature bank vault, and replaced by a crystal window. Through this obviously temporary opening a microscope, mounted on a swinging arm so that it could be moved away after use, was aimed into the interior of the drive unit.

The engineer clipped himself into position by the buckles conveniently fixed to the casing, stared through the eyepiece, and made some delicate micrometer adjustments.

“Take a look,” he said, when he was finally satisfied.

Duncan floated to the eyepiece and fastened himself rather clumsily in place. He did not know what he had expected to see, and he remembered that the eye had to be educated before it could pass intelligible impressions to the brain. Anything utterly unfamiliar could be, quite literally, invisible, so he was not too disappointed at his first view.

What he saw was, indeed, perfectly ordinary—merely a grid of fine hairlines, crossing at right angles to from a reticule of the kind commonly used for optical measurements. Though he searched the brightly lit field of view, he could find nothing else; he might have been exploring a piece of blank graph paper.

“Look at the crossover at the exact center,” said his guide, “and turn the knob to the left— very slowly. Half a rev will do—either direction.”