by Timothy Zahn
I nodded carefully and looked around the room. Pascal had already gotten it, from the expression on his face; Wilkinson and Tobbar were starting to. "Could an extra piece of Ming metal, placed several meters off the ship's center line, cause such a divergence?" I asked Chileogu.
"Possibly." He frowned. "Very possibly."
I shifted my gaze to Lanton. His face had gone white. "I think," I said, "I've located the problem."
—
Seated at the main terminal in Pascal's cramped computer room, Chileogu turned the Ming-metal coil over in his hands and shook his head. "I'm sorry, Captain, but it simply can't be done. A dual crossover winding is one of the most complex shapes in existence, and there's no way I can calculate its effect with a computer this small."
I glanced over his head at Pascal and Lanton, the latter having tagged along after I cut short the meeting and hustled the mathematician down here. "Can't you even get us an estimate?" I asked.
"Certainly. But the estimate could be anywhere up to a factor of three off, which would be worse than useless to you."
I nodded, pursing my lips tightly. "Well, then, how about going on from here? With that coil back in the shield, the real and physical rotations coincide again. Is there some way we can get back to our universe; say, by taking a long step out from Taimyr and two short ones back?"
Chileogu pondered that one for a long minute. "I would say that it depends on how many universes we're actually dealing with," he said at last. "If there are just two—ours and this one—then rotating past any one discontinuity should do it. But if there are more than two, you'd wind up just going one deeper into the stack if you crossed the wrong line."
"Ouch," Pascal murmured. "And if there are an infinite number, I presume, we'd never get back out?"
The mathematician shrugged uncomfortably. "Very likely."
"But don't the mathematics show how many universes there are?" Lanton spoke up.
"They show how many Riemann surfaces there are," Chileogu corrected. "But physical reality is never obliged to correspond with our theories and constructs. Experimental checks are always required, and to the best of my knowledge no one has ever tried this one."
I thought of all the ships that had simply disappeared, and shivered slightly. "In other words, trying to find the Taimyr colony is out. All right, then. What about the principle of reversibility? Will that let us go back the way we came?" "Back to Earth?" Chileogu hesitated. "Ye-e-s, I think that would apply here. But to go back don't you need to know...?"
"The real rotations we used to get here," I nodded heavily. "Yeah." We looked at each other, and I saw that he, too, recognized the implications of that requirement.
Lanton, though, was still light-years behind us. "You act like there's still a problem," he said, looking back and forth between us. "Don't you have records of the rotations we made at each point?"
I was suddenly tired of the psychiatrist. "Pascal, would you explain things to Dr. Lanton—on your way back to the passenger area?"
"Sure." Pascal stepped to Lanton's side and took his arm. "This way, Doctor."
"But—" Lanton's protests were cut off by the closing door.
I sat down carefully on a corner of the console, staring back at the Korusyn 630 that took up most of the room's space. "I take it," Chileogu said quietly, "that you can't get the return-trip parameters?"
"We can get all but the last two points we'd need," I told him. "The ship's basic configuration was normal for all of those, and the Korusyn there can handle them." I shook my head. "But even for those the parameters will be totally different—a two-degree rotation one way might become a one or three on the return trip. It depends on our relation to the galactic magnetic field and angular momentum vectors, closest-approach distance to large masses, and a half-dozen other parameters. Even if we had a mathematical expression for the influence Lanton's damn coil had on our first two points, I wouldn't know how to reprogram the machine to take that into account."
Chileogu was silent for a moment. Then, straightening up in his seat, he flexed his fingers. "Well, I suppose we have to start somewhere. Can you clear me a section of memory?"
"Easily. What are you going to do?"
He picked up the coil again. "I can't do a complete calculation, but there are several approximation methods that occasionally work pretty well; they're scattered throughout my technical tapes if your library doesn't have a list. If they give widely varying results—as they probably will, I'm afraid—then we're back where we started. But if they happen to show a close agreement, we can probably use the result with reasonable confidence." He smiled slightly. "Then we get to worry about programming it in."
"Yeah. Well, first things first. Alana, have you been listening in?"
"Yes," her voice came promptly through the intercom. "I'm clearing the computer now."
Chileogu left a moment later to fetch his tapes. Pascal returned while he was gone, and I filled him in on what we were going to try. Together, he and Alana had the computer ready by the time Chileogu returned. I considered staying to watch, but common sense told me I would just be in the way, so instead I went up to the bridge and relieved Alana. It wasn't really my shift, but I didn't feel like mixing with the passengers, and I could think and brood as well on the bridge as I could in my cabin. Besides, I had a feeling Alana would like to check up on Bradley.
I'd been sitting there staring at Taimyr for about an hour when the intercom bleeped. "Captain," Alana's voice said, "can you come down to the dining room right away? Dr. Lanton's come up with an idea I think you'll want to hear."
I resisted my reflexive urge to tell her what Lanton could do with his ideas; her use of my title meant she wasn't alone. "All right," I sighed. "I'll get Sarojis to take over here and be down in a few minutes."
"I think Dr. Chileogu and Pascal should be here, too."
Something frosty went skittering down my back. Alana knew the importance of what those two were doing. Whatever Lanton's brainstorm was, she must genuinely think it worth listening to. "All right. We'll be there shortly."
They were all waiting quietly around one of the tables when I arrived. Bradley, not surprisingly, was there too, seated next to Alana and across from Lanton. Only the six of us were present; the other passengers, I guessed, were keeping the autobar in the lounge busy. "Okay, let's have it," I said without preamble as I sat down.
"Yes, sir," Lanton said, throwing a quick glance in Pascal's direction. "If I understood Mr. Pascal's earlier explanation correctly, we're basically stuck because there's no way to calibrate the Aura Dancer's instruments to take the, uh, extra Ming metal into account."
"Close enough," I grunted. "So?"
"So, it occurred to me that this 'real' rotation you were talking about ought to have some external manifestations, the same way a gyro needle shows the ship's physical rotation."
"You mean like something outside the viewports?" I frowned.
"No; something inside. I'm referring to the cascade images."
I opened my mouth, closed it again. My first thought was that it was the world's dumbest idea, but my second was why not? "You're saying, what, that the image-shuffling that occurs while we rotate is tied to the real rotation, each shift being a hundredth of a radian or something?" "Right"—he nodded—"although I don't know whether that kind of calibration would be possible."
I looked at Chileogu. "Doctor?"
The mathematician brought his gaze back from infinity. "I'm not sure what to say. The basic idea is actually not new—Colloton himself showed such a manifestation ought to be present, and several others have suggested the cascade images were it. But I've never heard of any actual test being made of the hypothesis; and from what I've heard of the images, I suspect there are grave practical problems besides. The pattern doesn't change in any mathematically predictable way, so I don't know how you would keep track of the shifts."
"I wouldn't have to," Lanton said. "I've been observing Rik's cascade images throughout
the trip. I remember what the pattern looked like at both the beginning and ending of each rotation."
I looked at Bradley, suddenly understanding. His eyes met mine and he nodded fractionally.
"The only problem," Lanton continued, "is that I'm not sure we could set up at either end to do the reverse rotation."
"Chances are good we can," I said absently, my eyes still on Bradley. His expression was strangely hard for someone who was supposedly seeing the way out of permanent exile. Alana, if possible, looked even less happy. "All rotations are supposed to begin at zero, and since we always go 'forward' we always rotate the same direction."
I glanced back at Lanton to see his eyes go flat, as if he were watching a private movie. "You're right; it is the same starting pattern each time. I hadn't really noticed that before, with the changes and all."
"It should be easy enough to check, Captain," Pascal spoke up. "We can compute the physical rotations for the first six points we'll be going through. The real rotations should be the same as on the outbound leg, though, so if Dr. Lanton's right the images will wind up in the same pattern they did before."
"But how—?" Chileogu broke off suddenly. "Ah. You've had a mnemonic treatment?"
Lanton nodded and then looked at me. "I think Mr. Pascal's idea is a good one, Captain, and I don't see any purpose in hanging around here any longer than necessary. Whenever you want to start back—"
"I have a few questions to ask first," I interrupted mildly. I glanced at Bradley, decided to tackle the easier ones first. "Dr. Chileogu, what's the status of your project?"
"The approximations? We've just finished programming the first one; it'll take another hour or so to collect enough data for a plot. I agree with Dr. Lanton, though—we can do the calculations between cascade points as easily as we can do them in orbit here."
"Thank you. Dr. Lanton, you mentioned something about changes a minute ago. What exactly did you mean?"
Lanton's eyes flicked to Bradley for an instant. "Well... as I told you several weeks ago, a person's mind has a certain effect on the cascade image pattern. Some of the medicines Rik's been taking have slightly altered the—oh, I guess you could call it the texture of the pattern."
"Altered it how much?"
"In some cases, fairly extensively." He hesitated, just a bit too long. "But nothing I've done is absolutely irreversible. I should be able to re-create the original conditions before each cascade point."
Deliberately, I leaned back in my chair. "All right. Now let's hear what the problem is."
"I beg your pardon?"
"You heard me." I waved at Bradley and Alana. "Your patient and my first officer look like they're about to leave for a funeral. I want to know why."
Lanton's cheek twitched. "I don't think this is the time Or the place to discuss—"
"The problem, Captain," Bradley interrupted quietly, "is that the reversing of the treatments may turn out to be permanent."
It took a moment for that to sink in. When it did I turned my eyes back on Lanton. "Explain."
The psychiatrist took a deep breath. "The day after the second point I used ultrasound to perform a type of minor neurosurgery called synapse fixing. It applies heat to selected regions of the brain to correct a tendency of the nerves to misfire. The effects can be reversed... but the procedures been done only rarely, and usually involves unavoidable peripheral damage."
I felt my gaze hardening into an icy stare. "In other words," I bit out, "not only will the progress he's made lately be reversed, but he'll likely wind up worse off than he started. Is that it?"
Lanton squirmed uncomfortably, avoiding my eyes. "I don't know that he will. Now that I've found a treatment—"
"You're about to give him a brand-new disorder," I snapped. "Damn it all, Lanton, you are the most coldblooded—" "Captain."
Bradley's single word cut off my flow of invective faster than anything but hard vacuum could have. "What?" I said.
"Captain, I understand how you feel." His voice was quiet but firm; and though the tightness remained in his expression, it had been joined by an odd sort of determination. "But Dr. Lanton wasn't really trying to maneuver you into supporting something unethical. For the record, I've already agreed to work with him on this; I'll put that on tape if you'd like." He smiled slightly. "And before you bring it up, I am recognized as legally responsible for my actions, so as long as Dr. Lanton and I agree on a course of treatment your agreement is not required."
"That's not entirely true," I ground out. "As a ship's captain in deep space, I have full legal power here. If I say he can't do something to you, he can't. Period."
Bradley's face never changed. "Perhaps. But unless you can find another way to get us back to Earth, I don't see that you have any other choice."
I stared into those eyes for a couple of heartbeats. Then, slowly, my gaze swept the table, touching in turn all the others as they sat watching me, awaiting my decision. The thought of deliberately sending Bradley back to his permanent disorientation—really permanent, this time—left a taste in my mouth that was practically gagging in its intensity. But Bradley was right... and at the moment I didn't have any better ideas.
"Pascal," I said, "you and Dr. Chileogu will first of all get some output on that program of yours. Alana, as soon as they're finished you'll take the computer back and calculate the parameters for our first point. You two"—I glared in turn at Bradley and Lanton—"will be ready to test this image theory of yours. You'll do the observations in your cabin as usual, and tell me afterwards whether we duplicated the rotation exactly or came out short or long. Questions? All right; dismissed."
After all, I thought amid the general scraping of chairs, for the first six points all Bradley will need to do is cut back on medicines. That means twenty-eight days or so before any irreversible surgery is done.
I had just that long to come up with another answer.
—
We left orbit three hours later, pushing outward on low drive to conserve fuel. That plus the course I'd chosen meant another ten hours until we were in position for the first point, but none of that time was wasted. Pascal and Chileogu were able to program and run two more approximation schemes; the results, unfortunately, were not encouraging. Any two of the three plots had a fair chance of agreeing over ranges of half a degree or so, but there was no consistency at all over the larger angles we would need to use. Chileogu refused to throw in the towel, pointing out that he had another six methods to try and making vague noises about statistical curve-fitting schemes. I promised him all the computer time he needed between point maneuvers, but privately I conceded defeat. Lanton's method now seemed our only chance... if it worked.
I handled the first point myself, double-checking all parameters beforehand and taking special pains to run the gyro needle as close to the proper angle as I could. As with any such hand operation, of course, perfection was not quite possible, and I ran the Dancer something under a hundredth of a degree long. I'm not sure what I was expecting from this first test, but I was more than a little surprised when Lanton accurately reported that we'd slightly overshot the mark.
"It looks like it'll work," Alana commented from her cabin when I relayed the news. She didn't sound too enthusiastic.
"Maybe," I said, feeling somehow the need to be as skeptical as possible. "We'll see what happens when he starts taking Bradley off the drugs. I find it hard to believe that the man's mental state can be played like a yo-yo, and if it can't be we'll have to go with whatever statistical magic Chileogu can put together."
Alana gave a little snort that she'd probably meant to be a laugh. "Hard to know which way to hope, isn't it?"
"Yeah." I hesitated for a second, running the duty arrangements over in my mind. "Look, why don't you take the next few days off, at least until the next point. Sarojis can take your shift up here."
"That's all right," she sighed. "I—if it's all the same with you, I'd rather save any offtime until later. Rik will... nee
d my help more then."
"Okay," I told her. "Just let me know when you want it and the time's yours."
We continued on our slow way, and with each cascade point I became more and more convinced that Lanton really would be able to guide us through those last two critical points. His accuracy for the first four maneuvers was a solid hundred percent, and on the fifth maneuver we got to within point zero two percent of the computer's previous reading by deliberately jockeying the Dancer back and forth until Bradley's image pattern was exactly as Lanton remembered it. After that even Matope was willing to be cautiously optimistic; and if it hadn't been for one small cloud hanging over my head I probably would have been as happy as the rest of the passengers had become.
The cloud, of course, being Bradley.
I'd been wrong about how much his improvement had been due to the drugs Lanton had been giving him, and every time I saw him that ill-considered line about playing his mind like a yo-yo came back to haunt me. Slowly, but very steadily, Bradley was regressing toward his original mental state. His face went first, his expressions beginning to crowd each other again as if he were unable to decide which of several moods should be expressed at any given moment. His eyes took on that shining, nervous look I hated so much: just occasionally at first, but gradually becoming more and more frequent, until it seemed to be almost his norm. And yet, even though he certainly saw what was happening to him, not once did I hear him say anything that could be taken as resentment or complaint. It was as if the chance to save twenty other lives was so important to him that it was worth any sacrifice. I thought occasionally about Alana's comment that he'd never before had a sense of dignity, and wondered if he would lose it again to his illness. But I didn't wonder about it all that much; I was too busy worrying about Alana.
I hadn't expected her to take Bradley's regression well, of course—to someone with Alana's wing-mending instincts a backsliding patient would be both insult and injury. What I wasn't prepared for was her abrupt withdrawal into a shell of silence on the issue which no amount of gentle probing could crack open. I tried to be patient with her, figuring that eventually the need to talk would overcome her reticence; but as the day for what Lanton described as "minor surgery" approached, I finally decided I couldn't wait any longer. On the day after our sixth cascade point, I quit being subtle and forced the issue.
