MEMORY FILES SHOULD CONTAIN SUFFICIENT DATA TO ENABLE YOU TO.

FIND THE EXPLANATION OF THIS TWO-POSITION PARADOX. FIND THAT.

EXPLANATION.

SUBMIT METHOD OF PROCEDURE, it answered.

I DO NOT KNOW HOW. YOU WILL HAVE TO ARRIVE AT THE EXPLANATION UNAIDED.

THIS CANNOT BE DONE, it replied.

He wrote, with morbid curiosity: IF YOU DO NOT FIND THE ANSWER UNAIDED YOU WILL BE DESTROYED.

ALONG WITH ME AT 13:53. DON'T YOU GIVE A d.a.m.n?.

It answered: GIVE A d.a.m.n IS A SEMANTIC EXPRESSION I DO NOT UNDERSTAND. CLARIFY QUESTION.

He got out of the computer seat and walked about the room restlessly. He pa.s.sed by the transdimensional viewscreen and communicator and pressed the communicator's signal b.u.t.ton. A dial flickered in return, showing his signal was going out, but there was no sound in response. If only he could make contact with the brains in Observation- He was umpty billion miles east of the sun and umpty billion miles west of the sun.

He was racing faster than light in two different directions at once and he was sitting motionless under the blasters of two Slug cruisers.

Another thought came to him: even if he could move the ship while in the warp, where could he go?

He would have to go far beyond the outer limits of the solar system to escape detection by the Slug cruisers. And at that distance the sun would be only a yellow star, incapable of energizing the little solar power units. He would not live long after the last of the power was drained from the batteries and the air regeneration equipment ceased functioning. He would not even dare sleep, toward the last. There were no convection currents in the air of a ship without gravity, and it was imperative that the air be circulated constantly. The air circulation blowers would cease functioning while the ship still contained pure air but he would have to move about continually to breathe that air.

Should he lie down to sleep he would smother to death in a carbon dioxide bubble of his own making.

If he managed to emerge into normal s.p.a.ce at some point just outside Earth's atmosphere, beyond range of the cruisers, his driveless ship would descend as a blazing meteor. If, by some miracle, he could emerge into normal s.p.a.ce just a few inches above the s.p.a.ce-field it would be to materialize into s.p.a.ce already occupied by air. Such a materialization would be simultaneously fatal to him and to the electronic components of the shuttle and computer.

And if he did not move the ship, the Slug cruisers would disintegrate him. He had four hypothetical choices of his way to die, all equally unpleasant.

He smiled wanly at his reflection in the bright metal bordering the viewscreen and said, "Brother-you've had it!"

He went to the control room, there to brush his fingers across the useless control b.u.t.tons and look into the viewscreen that revealed only black and limitless Nothing.

What was the warp? Surely it must have definite physical laws of some kind. It was difficult to imagine any kind of existence-even the black nothing of the warp-as being utterly without rule or reason. If he knew the laws of the warp he might find some means of survival hitherto hidden from him. There was only one way he could learn about the warp. He would have to question the computer and continue questioning it until he learned or until his time was up.

He returned to the computer and considered his next question. The computer had calculated their positions from observations of the sun and other stars in front of the ship-what would similar calculations based on observations of the stars behind the ship reveal? He typed: USE FIRST THE TRIANGULATION METHOD AND THEN THE SPECTRUM-.

SHIFT METHOD TO DETERMINE OUR POSITION FROM OBSERVATIONS.

MADE OF THE STARS OF OPHIUCHUS.

The answers appeared. They showed the ship to be simultaneously speeding away from Ophiuchus and toward it.

He asked: DO THESE TWO POSITIONS COINCIDE WITH THOSE RESULTING FROM THE OBSERVATIONS OF ORION?.

YES, it answered.

Was the paradox limited to the line of flight?

He asked the computer: WHAT IS OUR POSITION, COURSE AND SPEED AS INDICATED BY THE STARS AT RIGHT-ANGLES TO OUR FORWARD-.

BACKWARD COURSE; BY THE STARS OF URSA MINOR AND CRUX?.

The answer appeared on the panel: the ship was racing sideward through the warp in two diametrically opposed directions, but at only one-third the speed with which it was racing forward and backward.

So now the ship had four impossible positions and two different speeds.

He frowned at the computer, trying to find some clue in the new data. He noticed, absently, that the hand of one of the dials was near zero in the red section of the dial. He had not noticed any of the dials registering in the danger zone before . . .

He jerked out of his preoccupation with apprehension and typed: TELL ME IN NON- TECHNICAL LANGUAGE THE MEANING OF THE HAND NEAR ZERO ON THE.

DIAL LABELED MAX. ET. REF.

It answered: ONE OF MY CIRCUITS WAS DAMAGED BY THE SUDDEN RELEASE OF AIR PRESSURE. I WILL CEASE FUNCTIONING AT THE END OF.

FOUR MORE MINUTES OF OPERATION.

He slammed the master switch to OFF. The lights on the board went out, the various needles swung to zero, leaving the computer a mindless structure more than ever resembling an overgrown refrigerator.

Four minutes more of operation . . . and he had so many questions to ask before he could hope to learn enough about the warp to know what he should do. He had wasted almost an hour of the computer's limited life, leaving it turned on when he was not using it. If only it had told him . . . but it was not the nature of a machine to voluntarily give information. Besides, the receding hand of the dial was there for him to see. The computer neither knew nor cared that no one had thought it worthwhile to teach him the rudiments of its operation and maintenance.

It was 12:52. One hour and one minute left.

He put the thought aside and concentrated on the problem of finding the key to the paradox.

What conceivable set of circ.u.mstances would cause receding stars to have a spectrum shift that showed them to be approaching the ship? Or, to rephrase the question, what conceivable set of circ.u.mstances would cause approaching stars to appear to dwindle in size?

The answer came with startling suddenness and clarity: There was no paradox-the ship was expanding.

He considered the solution, examining it for flaws of logic, and found none. If he and the ship were expanding the wave length of light would diminish in proportion to the increasing size of the retinas of his eyes and the scanner plates of the transdimensional viewscreens: would become shorter and go into the ultraviolet. At the same time, the increasing size of himself and the ship would make the Earth and sun relatively smaller and therefore apparently receding.

The same theory explained the two different speeds of the ship: its length was three times its diameter so its longitudinal expansion would proceed at three times the speed of its cross-sectional expansion.

Everything checked.

How large was the ship now?

He made a rough calculation and stared almost unbelievingly at the results. He was a giant, more than a third of a light-year tall, in a ship that was six light-years long and two light-years in diameter. Far Centauri, which had required thirty years to reach in the fastest interplanetary ship, floated seventy-one feet away in the blackness outside the hull.

And the sun and Earth were in the room with him, going into the shuttle's silvery focal ball.

He would have to ask the computer to make certain his theory was valid. His time was too critically short for him to waste any of it with speculation based on an erroneous theory.

He switched on the computer and it lighted up again. He typed rapidly: a.s.sUME THIS SHIP TO BE MOTIONLESS AND EXPANDING WOULD THAT.

THEORY SATISFACTORILY EXPLAIN ALL THE HITHERTO CONTRADICTORY.

PHENOMENA?.

There was a brief pause as the computer evaluated its data, then it answered with one word: YES.

He switched it off again, to squander none of its short period of usefulness until he had decided upon what his further questions should be. At last, he had some grounds for conjecture; had learned something about the warp the designers of the shuttle had not suspected. Their calculations had been correct when they showed a ship would travel in the warp at many times the normal s.p.a.ce speed of light. But somewhere some little factor had been overlooked-or never found-and their precise mathematics had not indicated that the travel would be produced by expansion.

Nature abhors a vacuum. And the black, empty warp was a vacuum more perfect than any that existed in normal s.p.a.ce. In the normal s.p.a.ce universe there were millions of stars in the galaxy and millions of galaxies. In the warp there was utter Nothing. Did the physical laws of the warp demand that matter be scattered throughout it, in emulation of its rich neighbor in the adjoining dimension? Was the warp hungry for matter?

He rejected the thought as fantasy. There was some explanation that the physicists would eventually find. Perhaps there was a vast size-ratio difference between the two dimensions; perhaps the warp was far larger than the normal s.p.a.ce universe and some co- universal law demanded that objects entering it become proportionally larger.

None of that aspect of his circ.u.mstances, however, was of importance. There was only one prime problem facing him: how to move the ship within less than an hour to some point in the warp where his emergence into normal s.p.a.ce would result in neither instant nor days-away death and where he would have the time to try to carry out the responsibility, so suddenly placed in his hands, of delivering the s.p.a.ce warp shuttle to the Thunderbolt.

The long-range task depended upon his immediate survival. He had to move the ship, and how did a man move a driveless ship? It might not require a very large propulsive force-perhaps even an oxygen tank would serve as a jet. Except that he had none.

He could use part of the air in the ship. Its sudden release should move the ship.

There was a sun very near: Alpha Centauri. If he had the proper tools, and the time, he could cut a hole in the hull opposite Centauri . . . but he had neither the tools nor the time.

And what good would it do him if he could emerge into normal s.p.a.ce at the desired distance from Centauri? He would be provided with power for the air regenerators by the solar power units but not power sufficient to operate the shuttle. He would breathe, and eat, for a week. Then the small amount of food on the ship would be gone and he would breathe for another four or five weeks. And then he would die of starvation and his driveless ship would continue its slow drift into the sun, taking his bones and the shuttle with it.

He would have to go to Sirius and he would have to reach it the first try or never. If he could emerge into normal s.p.a.ce at the proper distance from Sirius he would have power from it to operate the communicator. The Thunderbolt would come at once when it received his message and swallow the little Argosy in its enormous hold. The return to Earth would be the swift one through the warp and the Slug cruisers, so bold in pursuit of unarmed interplanetary ships, would quickly cease to exist.

At 13:53 Sirius would be somewhere in or near the bow of the ship. The ship would not have to be moved more than two thirds of its length-twenty meters. He could do that by releasing part of the air in the shuttle room through the sternward airlock.

How much air?

He tried to remember long-forgotten formulas. So many cubic feet of air at such and such a pressure when released through an opening of such and such a diameter would exert a propulsive force of . . . h.e.l.l, he didn't know. And not even the computer would be able to tell him because there were so many unknown factors, such as the proportion of the ship's ma.s.s lost to the Slug blasters, the irregular shape of the airlock opening, the degree of smoothness of its metal . . .

He made calculations with pencil and paper. He would have to move the ship with extreme precision. A light-hour short of the proper distance put him too far from the sun for it to power the communicator, a light-hour beyond put him in the sun's flaming white heart. One light-hour out of eight point six light-years was approximately one part out of seventy-five thousand. He would have to move the ship with an accuracy of point aught three centimeters-one hundredth of an inch.

One hundredth of an inch!

He laid the pencil back down, almost numbly. He could never open and close an airlock and move a ma.s.s of thousand of tons with an accuracy of a hundredth of an inch.

The very thought was wildly fantastic.

He was already far closer to Sirius than he would be if he tried to get any closer. And that was over eight light-years from it.

He looked at the chronometer and saw the hands had already reached 13:20. Thirty- three minutes left to him. Sirius was near-soon it would be in the bow of the ship-and Sirius was eight point six light-years away.

How could he move the ship a certain distance accurate to one hundredth of an inch?

He couldn't. The answer was blunt and ugly: he couldn't.

He got up and walked across the room, feeling like a man who had in quick succession been condemned, reprieved, recondemned. He had been projected into a situation for which he had had no preliminary training whatever; had been made sole custodian and operator of a computer and a s.p.a.ce warp shuttle that he had never before been permitted to touch. He had used the sound but not at all brilliant mind nature had given him to solve the riddle of the paradoxes and learn where he was and where he wanted to go. He had done quite well-he had solved every problem of his survival and the shuttle's delivery except the last one!

He pa.s.sed by the shuttle and stopped to rest his hand on the bright, silvery focal ball.

The solar system would be deep inside the ball; the atoms of the ball larger than Earth, perhaps, and far more impalpable than the thinnest air. The Slug cruisers would be in there, infinitesimally tiny, waiting for him to return . . .

No-faulty reasoning. The solar system was as it had always been, not diminished in size and not really in the ball. It was only that two different points in two different dimensions coincided in the ball . . .

He saw the answer.

He did not have to move the ship to Sirius-he had only to move the ball!

There would be little time, very little time. First, to see if the warp shuttle was portable- It was. When he unfastened the clamp that held it to the stand it lifted up freely, trailing a heavy cable behind it. He saw it was only a power supply cable, with a plug that would fit one of the sockets in the bow of the ship. He left the shuttle floating in the air, leashed by the cable, and went to the computer. Next, he would have to know if Sirius would be fully in the ship- He switched the computer on and typed: DETERMINE THE DISTANCE FROM THE CENTER OF THE WARP SHUTTLE'S FOCAL BALL TO THE s.p.a.cE WARP POSITION OF SIRIUS AT 13:53,.

BASING YOUR COMPUTATIONS ON THE EXPANDING-SHIP THEORY.

It gave him the answer a moment later: 18.3496 METERS.

He visualized the distance, from his knowledge of the ship's interior, and saw the position would be within the forward spare-parts room.

Next, to learn exactly where in that room he should place the shuttle. He could not do so by measuring from the present position of the shuttle. The most precise steel tape would have to be at exactly the right temperature for such a measurement to be neither too short nor too long. He had no such tape, and the distance from the focal ball was only part of the necessary measuring: he would have to measure off a certain distance and a precisely certain angle from the purely imaginary central line of the ship's axis to intersect the original line. Such a measurement would be impossible in the time he had.

He considered what would be his last question to the computer. The hand was touching the zero and his question would have to be worded very clearly and subject to no misinterpretations. There would be no follow-up questions permitted.

He began typing: IT IS DESIRED THAT THIS SHIP EMERGE INTO NORMAL s.p.a.cE ONE.

LIGHT-HOUR THIS SIDE OF SIRIUS AT 13:53. THIS WILL BE ACCOMPLISHED.

BY MOVING THE WARP SHUTTLE TO SUCH A POSITION THAT ITS FOCAL.

CENTER WILL BE IN A s.p.a.cE WARP POSITION COINCIDING WITH A.

NORMAL s.p.a.cE POSITION ONE LIGHT-HOUR THIS SIDE OF SIRIUS AT 13:53.

CONSIDER ALL FACTORS THAT MIGHT HAVE AFFECTED THE DIMENSIONS.

OF THIS SHIP, SUCH AS TEMPERATURE CHANGES PRODUCED BY OUR.

NORMAL s.p.a.cE ACCELERATION AND DECELERATION, WHEN COMPUTING.

THE POSITION OF SIRIUS. THEN DEFINE THAT LOCATION IN RELATION TO.

THE STRUCTURAL FEATURES OF THE ROOM'S INTERIOR. DO THIS IN SUCH.

A MANNER THAT PLACING THE SHUTTLE IN THE PROPER POSITION WILL.

REQUIRE THE LEAST POSSIBLE AMOUNT OF MEASURING DISTANCES AND.

ANGLES.

It seemed to take it an unduly long time to answer the question and he waited restlessly, unpleasantly aware of the hand touching zero and wondering if the computer's mind was baffled by the question; the mind that thought best in terms of orderly mathematics and could not know or care that measurement by protractor and tape would result in a position fatally far from that described by the neat, rigid figures.