Chapter Seventeen

Hans Rebka had spent a lot of time studying Paradox. He knew the history of the artifact’s discovery, and all about the effects of its interior on incident radiation (little) and intruding sapient species (disastrous). So far as the spiral arm was concerned, Rebka qualified as a Paradox expert.

Whereas…

He hung in space staring back toward the inaccessible outside, then ahead to the ominous-looking central region, and was filled with a sobering thought: he really knew next to nothing about the structure, nature, or origin of Paradox.

There had certainly been changes — nothing in Paradox’s history spoke of irreversible movement within it, or of an isolated torus at the center. But changes how, when, and why?

Another couple of attempts showed that any attempt to move toward the outer surface was a waste of fuel and energy. He turned off his suit’s thrust. That was when he realized that the situation was worse than he had thought. In principle he should be hovering at a fixed location within Paradox. In practice he was drifting, slowly but steadily, toward the center. He could move tangentially without any problem, but always there was a small radial component carrying him farther inward.

His next action was instinctive, the result of twenty years of hard experience. He did not think about it or try to explain it, although E.C. Tally, had he been present, could have done so in his own terms. When a computing problem of exceptional size and urgency was encountered, all subsidiary computation should be halted. Peripheral activities must go into complete stand-by mode, in favor of work on the single central problem.

Of course, Tally regarded humans as very handicapped by virtue of inefficient design. A major part of human central nervous activity went into simple maintenance work, so that total power-down of peripherals or unwanted memory banks was not feasible.

But given those built-in limitations, Hans Rebka came pretty close to E.C. Tally’s ideal. Rebka did not give a thought to Tally, or his own situation, or to anything that might be happening outside Paradox. He did not waste time with more experiments in tangential movement, or futile back-up attempts, or even in speculation as to the reason for his forward motion. Every scrap of his attention focused on the fat donut-disk twenty kilometers ahead of him. Unless something changed, he would be arriving there in an hour or so. Better be ready.

The outside of the donut was studded with dark markings, possible openings. They indicated that the disk was slowly rotating. At first they seemed no more than tiny pock marks, but as Hans came closer he could see a shape to each of them. They were like scores of little black diamonds, irregularly spaced around the disk, the long diagonal of each parallel to the disk’s main axis. What had appeared from a distance to be a central hole right through the disk, making it into a plump torus, now was of more ambiguous nature. There was certainly a darkness at the center, but the black was touched with cloudiness and a hint of structure that did not match Rebka’s concept of empty space.

He stared until his vision blurred. What could give that impression, of simultaneous presence and absence? Nothing in his experience.

No matter. Unless something changed, he would soon be able to find out by direct experience. His inward progress had not slowed. If anything, he was moving faster. Maybe ten more minutes to the center.

Now his ability to move tangentially was important — because he suddenly had a choice. Not much of one, in normal terms, but he could aim for one of the diamond-shaped openings on the side of the disk, or else head for the black swirl at the center.

Which?

Assume that his inability to move farther from the center continued. Then he could enter one of the diamonds, and if that proved useless he might still be able to go on and see what lay in the darkness at the disk’s center. Explore the black region first, and there would be no later chance to visit the diamonds. Maximize your number of options. Decision made.

The disk was rotating, but very slowly. Rendezvous should present no problem. He could count half a dozen different diamonds along the edge, each looking as good as any other. Rebka picked one at random and used his suit thrustor to match angular velocity with it. Then it was only a matter of watching and waiting, making sure that no anomalous increase in his own radial speed threw him off target.

The opening was bigger than it had seemed from a distance, maybe twenty meters on the diamond’s long axis and fifteen on the short. Rebka aimed right for the middle, wondering in the final seconds if he was about to be dissociated to individual atoms, squeezed to a pinpoint of nuclear density matter, or spun a hundred thousand light-years out of the spiral arm to intergalactic space.

He felt a slight resistance as he entered the opening, as though he was passing through a thin film of sticky material. Then he was inside, tensed and quiveringly ready for whatever life-preserving action might be necessary. A sharp note within his helmet told him to glance at the monitors. He observed that the temperature outside his suit had gone instantly from the bleak frigidity of interstellar space to that of a pleasant spring morning on Sentinel Gate.

What else had changed?

Speculation ahead of time would have been a waste of effort, so before entering the diamond he had not allowed himself the indulgence of wondering what he might find inside. In spite of that, he must have carried somewhere in the back of his head a list of things he definitely did not expect to encounter when he went through the opening. Otherwise, there would have been no reason for his astonishment at what he saw when he emerged into the interior.

He was in a room like a misshapen cube. One dimension was the full width of the disk, with curved ceiling and floor that followed the shape of the torus. On either side the plane walls stretched away, to make a chamber at least forty meters across. Every square inch of those walls was occupied by cabinets, nozzles, troughs, gas supply lines, faucets, and hoses. Thousand after thousand of them, in all shapes and sizes.

Rebka moved to the far wall of the chamber, closest to the center of Paradox. It was rock-solid, seamless, and resonated a deep boom under a blow from his fist. No way out through that.

He went to inspect the wall on his right. The first units he came to were apparently a line of gas dispensers. There were no dials, indicators or instructions, but it was hard to mistake the turncocks for anything else. Rebka cautiously cracked one open. He waited for his suit’s sensors to sample what came out, then turned the gas stream off at once. Fluorine! Poisonous, highly reactive, and no knowing how much of it the unit would supply. Maybe enough to fill the whole chamber, assuming the membrane at the entrance was able to hold an atmosphere.

Hans moved along the line, trying each dispenser. Chlorine, helium, nitrogen, neon, hydrogen, methane, carbon dioxide, ammonia. Oxygen. He might starve here or die of thirst, but he was not going to asphyxiate. He could recharge the air supply of his suit, matching it to any preferred proportion of gases. In fact — he eyed the line of units, stretching away in both directions — it would not be surprising if some dispensers offered mixtures of gases. Certainly he saw far more dispensers than were needed to offer the gaseous elements and their simplest compounds.

It was tempting to test that idea. Instead, he turned his attention to smaller units farther along the wall. These provided liquids instead of gases. His suit was able to identify only the simplest as he permitted small samples of each to touch the sensors. Methyl alcohol, acetone, ethyl alcohol, benzene, ether, toluene, carbon tetrachloride.