Imperial Earth

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 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 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 i!nfamiliar 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 form 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 on the left-very slowly. Half a rev will do-either direction.”

Duncan obeyed, yet for a few seconds he could still see nothing. Then be realized that a tiny bulge was creeping along the hairline as he tracked the microscope. It was as if he was looking at the reticule through a sheet of glass with one minute bubble or imperfection in it.

“Do you see it?”

“Yes-just. Like a pin head-sized lens. Without the grid, you’d never notice it.”

“Pinbead-sized! That’s an exaggeration, if ever I heard one. The node’s smaller than an atomic nucleus. You’re not actually seeing it, of course-only the distortion it produces.”

“And yet there are thousands of tons of matter in there.”

“Well, one or two thousand,” answered the engivneer, rather evasively.