The Compleat McAndrew

FIFTH CHRONICLE: The Hidden Matter of McAndrew

The message was concise and clear:

Dear Captain Roker,

The Institute is sending a party to explore a region approximately half a light-year from Sol, for the purpose of verifying dark matter conjectures in current cosmological theories. Our projected departure date is six days hence. Knowing of your experience with Hoatzin-class ships employing the balanced drive, we wonder if you might be available to serve as a crew member for Project Missing Matter. If you are interested in so serving, I invite you to contact me or Dr. Dorian Jarver, at the above address.

Sincerely,

Arthur Morton McAndrew,

Research Scientist,

Penrose Institute.

Clear, but also totally baffling. It was no surprise that McAndrew wanted to test obscure scientific theories. That was his stock-in-trade. People who knew physics as I would never know it told me that McAndrew was better than anyone else alive, a name to be mentioned in the same breath as Newton and Einstein.

It was also predictable that he might be heading far out of the Solar System. He had done that whenever he thought there was something interesting to look at, or just when he needed a little time and space for serious solitary thinking. “I have to have it, Jeanie,” he’d said to me, a score of times. “It’s very nice to work with colleagues, but in my line of business the real stuff is mostly worked out alone.”

Nor was it odd that I was learning about the trip so late — a couple of times he had hared off on wild sorties far outside the Solar System, and I had been forced to chase after him and drag him out of trouble.

But now for the mysteries: He had never, in all the many years since first we met, sent a letter to “Captain Roker,” or signed himself with his full name. I was always “Jeanie” when he wrote to me, while he signed as “Mac” or “Macavity” — my private Old Possum-ish name for him, because like Macavity the Mystery Cat, McAndrew did things that seemed to break the law of gravity.

Second, he didn’t write when he was planning an expedition. There would be a random call, at any hour of the day or night. He was thinking of making a trip, he’d say vaguely. Would I perhaps like to go along?

Third — a detail, but one that chafed my ego — I was invited to go on the Project Missing Matter expedition as a crew member. Mac knew that I’d served as ship’s captain, and only as captain, for fifteen years.

Fourth, the whole tone of the letter was too stilted and officious to be genuine McAndrew. He couldn’t sound that formal if he tried.

And one more mystery, to round out the set. Who the devil was Dorian Jarver? I thought I knew all the key scientists at the Penrose Institute.

That question was fifth on the list, and the least important until I tried to call McAndrew for an explanation. Then instead of the old direct-access lines into individual offices at the Penrose Institute, I found myself dumped to a Message Center where my call was at once rerouted from McAndrew to Dorian Jarver. Director Jarver is unavailable, said a polite voice. Please leave your name, and he will return the call as soon as possible.

I hung up without waiting to learn if the voice at the other end was live or recorded. Director Jarver? What had happened to my old friend Professor Limperis, the blackest man alive, who had run the Institute since long before my first visit?

Finding the answer to that was not difficult. I tapped one of the general data bases and queried for the staff file of the Penrose Institute. Professor Limperis was listed, sure enough — but as professor emeritus and ex-Director. The new director was Dr. Dorian Jarver, former head of the Terran science applications group, and — bad sign — nephew of Councilor Griss, head of Terran Food and Energy.

Anna Lisa Griss, that was, a lady whose arm McAndrew had once, with the best of possible intentions, cut off with a power laser out in the Oort cloud. It would have been regrown, long since; but I doubted that the memory had faded with the scar.

I followed an old McAndrew principle, and went to a publications data base. Dorian Jarver was there, with eight or nine decent-sounding physics papers credited to him; but they were not recent. The newest one was eleven years old. The new director of the Penrose Institute appeared to be an ex-physicist.

McAndrew was anything but an ex-physicist. Why would he cite his own name and Jarver’s as someone I might contact?

When I received the message from McAndrew I was on the tail end of a routine run home from Titan. As soon as the Assembly I had been piloting was tucked away and all its Sections placed in a stable parking orbit, I signed off and headed straight for the Penrose Institute aboard one of the 5-gee mini-versions of the McAndrew balanced drive.

“I invite you to contact me or Dr. Dorian Jarver,” the letter had said. Contact can surely include a visit.

The outline of the Institute at last appeared as a lumpy and spiky double-egg during my final approach. I examined it closely. It would wander around the Inner Solar System depending on research needs, anywhere between Mercury and the Belt, but its facilities shouldn’t change. They hadn’t. As we docked I could see the Dotterel and the Merganser moored in the external hoists. They were the first prototypes using the McAndrew balanced drive (which everyone else, to Mac’s intense annoyance, insists on calling the McAndrew inertia-less drive). Those early ships were no longer in use. They had been replaced by a more advanced design, embodied in the Hoatzin. I could see its bulky massplate and longer central spike off in the distance. It appeared slightly grubby and battered-looking, as befitted the first and only ship to visit both the Ark of Massingham and the Oort cloud.

The changes began inside, as soon as I passed through the lock. In the old Institute the visitor found herself wading at once through a junkyard of obsolete equipment waiting for disposal. It would have been quite an obstacle course in an emergency, but nobody had ever seemed worried about that.

Now I found myself in a clean and uncluttered chamber. The walls were painted white, the floor was polished grey, and in the middle of the room sat something that the Institute had surely never seen before: a long desk, two receptionists, and in front of them, a sign-in terminal and a tray of badges.

The woman behind the desk went on fiddling with a great bank of controls in front of her, all flickering lights and low humming, but the man glanced up at me inquiringly.

“I’m here to see McAndrew,” I said, and started towards the corridor on the left. I’d been here scores of times, and I knew where Mac hung out, in a cluttered room that made even the old entry to the Institute look elegant. Mac didn’t throw away junk equipment. He kept it in his office.

“Not that way, ma’am,” said the man politely. “Professor McAndrew is the other way now. You will need an escort. And if you’d first please check in…”

McAndrew’s voice was starting to whisper in my ear. By the time that I had signed in, stated my identity, had my ID independently checked with a DNA mapper, been assigned a badge, and refused refreshments (how long did they expect me to be in the reception area?) Mac’s voice was shouting at me. “Help, Jeanie,” it screamed. “Help, help, help!”

This wasn’t the Penrose Institute that I had known, the place of casual procedure and superb science where Mac had worked for half his life. It had become a clone of a thousand Earthside technology offices.

And it got worse. When I, checked and signed and badged, was led away towards the new working offices, I still did not reach McAndrew. “In a few minutes,” said my guide, in answer to my question. “But first, the Director.”

I was ushered into a new chamber, starkly clean and sparsely furnished. My guide left at once and I looked around. There was no desk, no terminal. Over in one corner on an angular white chair sat an equally angular and thoughtful man, fingertips touching in front of his face.

“Captain Roker,” he said, and stood up. He smiled, very white teeth in a thin-lipped, worried countenance. “I’m Dorian Jarver, the Director of the Penrose Institute. I must say I didn’t expect a visit until you’d heard more about the project. But it’s a blessing that you’re here, because now we can all do our best to persuade you.”

“I’m persuaded already.” I realized that was true, and had been since I saw that ritzy new entrance foyer. “I’m reporting for duty right now.”

“For the expedition described in Professor McAndrew’s letter to you? But the mission and your role in it are not yet fully defined.”

“You can define that later. I’m here, and I’m ready to start.”

Dorian Jarver must have been surprised at both my arrival and my instant acceptance. “I’m delighted to hear that,” he said, though he didn’t sound it. “You come to us with the highest recommendations. And I have to admit that I’ve been a little worried about this proposed expedition. It could be dangerous, and Professor McAndrew is too valuable to risk. He’s one of our most priceless assets.”

No matter what else he didn’t know, he obviously understood McAndrew. It could be dangerous, because Mac would charge into Hell itself if he saw some intriguing scientific fact sitting in the innermost circle. He was too valuable to risk. But Jarver’s final word was disturbing to me. Not a scientist, not a human being. An asset.

“You have been to the Institute before?” added Jarver.

I nodded. I didn’t know what Mac had told him about me, but I suspected that the new director had no idea how close we were.

“Then you’ll have noticed the changes here. The Council had been worrying about the Institute for quite a while. When Director Limperis retired and I came in, the Council insisted that from now on operations would have to be organized rather differently.”

He talked about those changes for the next few minutes. Better equipment and facilities for the scientists. Bigger and cleaner offices. More attention by support staff to routine maintenance functions. Removal of the need for top scientists to waste their time on calls and letters and incoming requests for information, trivia that could be handled just as well by junior staff.

It all sounded terrific. But McAndrew’s strangely awkward letter stuck in my head. I wanted to see him, and make sure that he was all right.

With my mind on McAndrew as Jarver went on talking, I didn’t think that I was saying much in reply. But it must have been enough for the director, because after another few minutes he seemed to lose interest in the conversation, nodded, and said, “Now, Captain Roker, I’m sure you’ll be wanting to hear more about the expedition itself. Project Missing Matter will be testing some of the most fundamental ideas in cosmology; of course, you’ll get that better from McAndrew than you’ll ever get it from me.”

As we stood up I thought that I had Dorian Jarver pegged. I had seen him before, many times. Not the man himself, but the type. The upper levels of Terran government were full of them: competent, hard-working men and women, who started out as scientists, found that they were never going to be better than average, and at an early age substituted management and administration for research. Jarver had changed over the years from scientist to calculating bureaucrat.

Well, I’ve been wrong before. Let’s call that my first mistake on Project Missing Matter.

The director led me to an office down at the far end of the corridor and opened the door. It was big, far bigger than McAndrew’s old, cluttered den. It had the same antiseptic look as the rest of the new Institute. But even Jarver couldn’t do much about the appearance of the occupant.

McAndrew was lolling in an easy chair, staring vacantly at the wall. His shoes were off, his feet were bare and grubby. His thinning, sandy hair was standing up in little wispy spikes as though he had been running his hands through it, which he tended to do when he was thinking, and I could see from the redness of his finger and toe joints that he had been pulling them and cracking them, in the way that I hated.

He glanced up as we came in, swinging his chair casually in our direction.

“Jeanie Roker,” he said. He didn’t stand up, and he didn’t seem in the least surprised at my unexpected arrival. I glanced at Jarver out of the corner of my eye. If Mac wanted to convince the director that he hardly knew me, he should have acted quite differently.

“Professor McAndrew,” said Jarver to me. It could have been an introduction, or possibly an apology. “If you’ll excuse me, Captain Roker, I’ll leave the two of you to discuss the expedition. I’ll meet with you again later.”

As soon as he was gone I bent over and gave McAndrew a six-month separation hug. The hell with formal handshakes. He hugged me right back, then I flopped into the seat opposite and said, “Mac. What the hell is going on here?”

“You saw it already.” His face took on a gloomy, give-up expression that I didn’t like at all. “New offices, new procedures, all the other folderol. Now tell me, did I need a new office?”

“Does it matter that much? You can work as well in here as you could in your old place, and it’s nice to visit and sit on something softer than an optical scalar calibrator. And Jarver’s right, the Institute was getting a bit run-down. It looks good now. You’re becoming crabby in your old age.”

He glared at me. “If that were the whole of it, I might agree with you… but it’s not. You had that letter. Didn’t it make you wonder a bit?”

“Why d’you think I’m here?”

I don’t believe he heard me. “Due procedure,” he said, “that’s what they call it. But it’s beyond that. No messages or memos or papers or letters go out from here without stamps of official approval on them. You saw how my letter to you sounded after they’d done messing with it. All the incoming mail is opened, too — personal as well as professional — before we get to see it. Spoken messages are just as bad. Incoming and outgoing calls are all logged and recorded. Did you see that blasted bank of equipment in the front area, with administrative staff snooping on everything? I’m telling you, it’s like being in a bloody prison.”

“Mac, you’re overreacting. Jarver is used to running things Earth-style. They’re hot on procedure. It’ll take him a while to learn Institute ways. You and your buddies will sort him out.”

“Will we now?” McAndrew snorted. “Me and my buddies will sort him out, will we — when Emma Gowers and Wenig and Lucky Macedo have already resigned and left.”

That was a shocker. I knew all three, and there wasn’t one who didn’t make me feel, without their ever intending it, about as bright as a chimps’ tea-party drop-out.

“Mac, that proves my point. If Jarver’s losing high-caliber people like that, he must know that he won’t last another three months. Unless he’s too dumb even to realize what he’s driving away?”

I saw a change in McAndrew’s expression. He’s the system’s most honest man, even when it undermines his own arguments. Now he looked guilty.

“That’s maybe the worst of it,” he said. “Jarver’s not stupid at all. He got the job here, likely, because he’s a relative of Anna Griss. She’s no lover of the Institute after what I did to her. But Jarver didn’t come here wanting to destroy the place. He’s a good physicist, see, with a real sense for what’s important.”

“That’s not what I thought when I looked at his publication record. Not many papers to his credit, and all written a long time ago.”

“Jeanie.” McAndrew stared at me with the disappointed expression of a man whose dog has slipped back into non-housebroken ways. “How many times have I told you, a publication record tells you nothing. Any clod can spew out words and equations, year in and year out, and push them into print. Papers don’t count for anything, unless other people use ’em. You should have looked at the Citation Index, to see how often Jarver’s work is given as a reference by other people. If you’d done that, you’d have seen hundreds of them. He’s not publishing now, true enough, but when he did, he was good.”

Poor old McAndrew. I was beginning to see the real problem. Here was a new director who did everything that Mac disliked, a man whom he would love to hate and disparage. But he couldn’t do that. Jarver was a good physicist, and therefore almost beyond censure.

“But if he’s that bright, you ought to be able to work with him. Persuade him.”

“Damn it, I have persuaded him. That’s what the new expedition is all about. I’ve got Jarver convinced that we have to go out a long way from Sol. Then we stop, and sit still, and do our measurements, and learn more than anyone has ever known about the distribution of missing matter.”

I had to find out more about that, but this wasn’t the time for it. Half a light-year from Sol was a long trip, even with a hundred gees of continuous acceleration and the relativity squeeze that our high speed would provide us. We’d have weeks to talk about missing matter, Mac’s experiments, and everything else in the Universe. But it would be nice to know why we had to go out there at all.

“Why not do your experiments here at the Institute?”

“Because it’s too damned noisy near in.” McAndrew became more like his old self as the conversation turned closer to physics. I decided there was hope — maybe he wasn’t a broken man after all. “It’s the Sun’s fault,” he went on. “Sol generates such an infernal din, gravitationally and in almost every electromagnetic wavelength you can think of, that you can’t do a decently sensitive experiment closer than half a light-year. It’s like listening for a pin drop, when somebody’s banging a bass drum right next to your ear. We have to go out, out where the interstellar medium is nice and quiet.”

“But that’s exactly what you will be doing. You’ll be flying out on the Hoatzin, and as far from the Institute as you want to be. So why aren’t you pleased?” I had a horrible thought. “Unless you’re telling me that Jarver proposes to go along with us.”

“No, no, no.” McAndrew went right back to being gloomy. “He says he’d like to, but he’s far too busy running the Institute. He’s not going. But he’s sending his aunt’s pet bully-boys, Lyle and Parmikan, along to keep an eye on things and report back. Now that’s what really has me going, Jeanie. That’s the reason I sent you the letter.”

I got very annoyed with McAndrew. He was taking a perfectly natural decision, from Jarver’s point of view, and blowing it up out of all proportion.

Of course, this was before I met Van Lyle and Stefan Parmikan.

The doubtful pleasure of that meeting was not long delayed. It came the same afternoon, when McAndrew dragged me along to the weekly seminar, a tradition of the Penrose Institute for as long as I had been visiting it.

The old meeting room, with its poor air circulation and white plastic hard-backed chairs, had vanished. In its place was a hall with tiers of plushy seats running in banks up towards the rear. It could hold maybe three hundred. The seminars that I remembered might draw fifty if they were on a really hot subject.

Today there were no more than thirty people in the room. McAndrew and I took seats at the end of the last occupied row. I tried to recognize the people I knew from the look of the backs of their heads. I did pretty well, over half the audience. Wenig and Gowers and Macedo might be gone, but most of the other old-timers at the Institute hadn’t given up yet.

The lecturer, Siclaro — another Institute perennial — was already in position and raring to go.

“The first ten-thousandth of a second after the Big Bang is far more interesting than the entire rest of the history of the Universe.” That was his first sentence. I couldn’t tell you what his second sentence was. I didn’t expect to understand the seminar, you see, because I never had in the past. But I might still enjoy it. Like the psychologist at the burlesque show I concentrated on the audience, examining the newcomers to try to guess their specialties and how good they were at them.

A futile exercise, of course. Emma Gowers, the System’s top expert on multiple kernel arrays, looks and dresses like a high-class whore. Wenig could be her pimp, and McAndrew himself resembles an accountant in need of a haircut and a good meal.

You just can’t tell. Brains won’t correlate with appearance.

Over to the far left of our row sat a group of three. I saw Dorian Jarver. He was leaning forward, intent on the presentation. To his immediate right were two men of particular interest to me — because they too were taking no notice of the lecture and showing a lot of interest in the audience. I nudged McAndrew, just as someone hurried in from the back of the room and leaned over to whisper in Jarver’s ear. He sighed, shook his head, and followed the woman quickly out of the hall.

“What?” said McAndrew at last. He had missed the whole episode with Jarver.

“Those two men. Who are they?”

He snorted. “Them two? Van Lyle. Stefan Parmikan.”

I stared with redoubled curiosity. Van Lyle (I found out later which was which) was a big, broad-shouldered fellow with curly blond hair and a handsome, craggy profile. He made no pretence of listening to the lecture, but he observed the audience with open interest. At his side the little, round-shouldered figure of Stefan Parmikan was far more discreet. To a casual observer he was following everything that Siclaro said — but every few seconds his head would turn for a moment and his eyes would flicker over everyone. When they met mine he at once turned away.

“Mac,” I said. And paused.

He had slipped away from my side. I saw him down by the lecturer’s podium next to Siclaro, one hand pointed at the screen.

“You know the problem,” he was saying. “We all believe that the amount of matter in the universe is just enough to keep it expanding forever. That gives asymptotically flat spacetime, an idea we have half a dozen good theoretical reasons for wanting to believe. But the bright matter — the stuff we can see — only accounts for maybe a hundredth of what’s needed to close spacetime. So, where’s the rest of it? Where’s the missing matter?

“I agree with Siclaro, it’s the devil to answer that question from any experiments we’ve been able to do so far. I wouldn’t propose to try. But we’ve designed a whole new set of crucial experiments that we can do if we are far out from Sol, where there’s not so much interference.”

He was getting into a discussion of the hidden matter, the reason for taking the Hoatzin on its light-year round-trip. But I couldn’t listen to him, because I was no longer alone. The two men next to Jarver had slid quietly across from the other side of the room and were now by my side.

“Captain Roker?” said the blond-haired man. “I wanted to say hello. I hear we’re going to be shipmates.”

He gazed sincerely into my eyes, took my hand in his big, meaty paw, and held on a few seconds longer than necessary.

“Pleased to meet you,” added his companion, leaning across and taking my hand in turn. “I’m Stefan Parmikan. I’ve heard a lot about you.” His smile was a wet, shapeless version of Van Lyle’s intimate grin. And instead of riveting me like Lyle, his brown eyes would look anywhere but into mine.

“You heard about me?” I was surprised. McAndrew is closer than a clam. “From whom?”

“The boss. Councilor Griss.”

His limp grip was like a lump of wet gristle, much worse than Van Lyle’s intimate clutch; but that wasn’t what bothered me.

Suddenly, I could put it all together. So far my thinking had managed to get everything wrong. Anna Lisa Griss could push her relatives into high places, and no one would be surprised by that. Nepotism never changes. She had arranged for Dorian Jarver to take over the Penrose Institute.

But it was her bad luck that Jarver happened to be genuine, a conscientious scientist with a real feel for physics and science. She couldn’t change his nature. What she could do, though, and had done, was to install as his assistants her chosen few: people with no feeling for science, who would follow the Councilor’s style of operation and do exactly what she said. She had told them to mold the Institute to her own taste, to change it to a copy of the standard Terran bureaucracy that she understood and controlled so well.

And they were doing it. I was now convinced that the real author of the message to me had not been McAndrew. Lyle or Parmikan had structured it, with Anna Griss behind them. Mac had asked for my help, but she had been the manipulator. She wanted me on board the Hoatzin, for a trip that she would control, through Van Lyle and Stefan Parmikan, from beginning to end.

What made me so sure? There’s one point that I neglected to mention about the run-in that we had with Anna Griss out in the Oort cloud. McAndrew had cut off her arm, which was bad enough but maybe forgivable since he thought he was doing it to save her life. But before that I had stared her down, overridden her authority, and asserted my own position as ship’s captain. She had been forced to accept it. But knowing Anna, I knew that would never be forgiven, or forgotten. Not even when she had taken an eye for an eye — or an arm for an arm.

I heard the door at the back of the room open. Jarver was coming back in, and Lyle and Parmikan dutifully hurried back to his side. I shivered, and sat up straight in my seat. Something creepy had brushed by me in the past few minutes, and I didn’t yet know what it was.

“So that’s it,” McAndrew was saying from the podium. “The two best candidates for the missing material needed to flatten the universe are hot dark matter — probably energetic neutrinos with a small rest mass, generated soon after the Big Bang; or maybe cold dark matter, particles like the axions needed for charge-parity conservation, or the photinos and other more massive objects required by supersymmetry theories.

“So which should we believe in, the hot or the cold? We don’t know. They both have problems describing the way that the galaxies formed.

“Worse than that, we aren’t measuring nearly enough of either kind of matter. Add everything together, and we still have less than half the mass density needed to make a flat universe. We must be badly underestimating either the cold dark matter or the hot.

“Which? Theory still can’t provide the answer. Most of the events that decide all this began happening in the first 10^-35 seconds after the origin of the universe, when we weren’t around to do experiments; when even the laws of physics may not have been the same.

“We may never know the composition of the missing matter, until we can put our instruments in the right place for observation — deep in interstellar space.”

He halted. Siclaro nodded his appreciation, and Mac came ambling back to his seat.

Naturally, he had missed the whole interaction with Lyle and Parmikan. He’d have missed it even if it had happened under his nose, because he never saw anything when he was talking about physics. He had temporarily forgotten his annoyance at the changes to the Institute, and he seemed quite pleased with life.

I wasn’t. I had been brought to the Institute so that McAndrew and I could fly half a light-year from home with Lyle and Parmikan. Anna Griss had engineered my arrival. It was inconceivable that the surprises were all over.

What little goodies were in store when Anna’s bully-boys and I were flying far off in the Hoatzin?

I lost track of that question in the busy days before departure. The Hoatzin was primed and ready, but I hadn’t performed my engine inspection or any of the other preparations that I like to do. I went over the ship, checking everything, and found nothing worse than a slight imbalance in the drive that would have meant a mid-course correction at ship turn-around, a quarter of a light-year from Sol.

Neither Lyle nor Parmikan gave me any trouble. In fact, I hardly saw them until the four of us assembled for final check-in and departure. Then Stefan Parmikan rolled up with about ten times as much baggage as he was allowed.

He objected strongly when I told him to take it away. “All that space.” He pointed outside, to the Hoatzin with its hundred meter mass disk and the four hundred meter axle sticking out like a great grey spike from its center. “There’s oceans of room for my stuff.”

How could a man reach adulthood today, and know so little about the McAndrew balanced drive?

“The disk you’re pointing at is solid compressed matter,” I said. “Density is twelve hundred tons per cubic centimeter, and surface gravity is a hundred and ten gees. If you want to strap your luggage on the outside of that, good luck to you.”

“What about the axle? I can see that it’s hollow.”

“It is. And it has to stay that way, so the living-capsule can move up and down it. Otherwise we couldn’t balance the gravitational and inertial accelerations. Either we move the capsule in closer to the disk as we increase the acceleration, or you tell me how we’re going to survive a hundred gees.” When he still didn’t show much sign of understanding me, I waved my hand. “The total living accommodation of the Hoatzin is that four-meter sphere. I’m not going to spend the next month falling over your stuff. And I’m not going to waste time arguing. That luggage isn’t going with us. That’s final. Get it out of here, so we can prepare to board.”

Parmikan glowered and grumbled, and finally dragged it away. When he reappeared an hour later with a much smaller package I hustled everyone onto the Hoatzin as quickly as possible to avoid any more hold-ups. Maybe I wasn’t as thorough as I should have been inspecting luggage. But I suspect it would have done no good if I had been. There must be a definite threat before you start opening people’s personal effects. I was anticipating rudeness and arguments and possible discipline problems, but not danger.

Let’s call that my second mistake in Project Missing Matter.

Once we were under way I felt a lot better. With the drive on the perimeter of the mass disk turned on, the Hoatzin is surrounded by a sheath of highly relativistic plasma. Signals won’t penetrate it. Communications with Anna Griss, or anyone else back in the Solar System, were blocked. That suited me fine.

By the end of the first twenty-four hours at full drive we were doing well. We were up to a quarter of light-speed, heading out from Sol at right angles to the plane of the ecliptic and already at the distance of Neptune. We had settled into a typical shipboard routine, each person giving the others as much space as possible. You do that when you know you have to spend a long time packed together into a space no bigger than a fair-sized kitchen.

And then, unexpectedly, our communications silence caused trouble.

The Hoatzin had been pleasantly quiet for hours. McAndrew had donned a suit, one of the new transparent models so light that you could sit in high vacuum and hardly realize you had a suit on at all.

He was going outside. Most people would be terrified at the prospect of leaving the capsule when the drive is on — if for any reason it turned off, the capsule would automatically spring out to the far end of the axle, to hold the interior field at one gee. But anyone not firmly secured to the capsule would fall at a hundred gee acceleration towards the mass disk. A quick end, and a messy one.

It never occurred to McAndrew that his inventions might fail. He had happily gone outside, for a status check of one of the new mass detectors that he would be using when we reached our destination in the middle of nowhere. We were heading for the region of lowest matter density known, out beyond the limits of the Oort cloud where we would find less than one atom per hundred cubic meters.

I was looking at the outside display screens, partly to scan the plume of plasma behind the Hoatzin for any sign of drive variability, and partly, to tell the truth, because I wanted to keep my eye on McAndrew. He doesn’t believe the balanced drive can give trouble, despite the fact that its very first use nearly killed him.

While I had my attention on the screens, Stefan Parmikan crept up behind me. I didn’t know he was there until I heard a soft, sibilant voice in my ear. “I am required to send a report to the Council every day, and be able to receive messages from them.”

I jerked around. Parmikan’s face was only a foot from mine. It was probably not his fault, but why was his mouth always so wet-looking?

“But Professor McAndrew tells me that we cannot send messages to Terra when the drive is turned on,” he continued.

“Quite right. To Terra, or anywhere else. The signals can’t get through.”

“In that case, the drive must be turned off once every shipboard day.”

“Forget it.” I was a bit brusque, but Lyle and Parmikan seemed to have come along on the expedition without learning a thing about the ship, the drive, or anything else. And Parmikan didn’t sound like he was asking — he was telling. “We lose a couple of hours every time we turn power on and off,” I went on. “And you’d have the living-capsule going up and down the axle like a yo-yo, to balance the change in acceleration from a hundred gee to zero. And anyway, once we’re a long way out the signal travel time is so long the messages would be useless.”

“But it is technologically feasible to turn off the drive, and to send and receive messages?”

“It is. And practically ridiculous. We won’t do it.”

Parmikan smiled his wet smile, and for once he appeared to be genuinely pleased about something.

“We will, Ms. Roker. Or rather, you will. You will turn the drive off once a day, for communication with Earth.”

He drew a yellow document from his pocket, stamped prominently with the Council seal, and handed it to me.

Not Captain Roker. Ms. Roker. It took only a few seconds to scan the paper and understand what it was. I was holding Parmikan’s appointment as captain of the Hoatzin for this mission. In all the excitement of preparing for our departure I had completely forgotten the original letter to me. An invitation to serve as crew member on the expedition, not captain. For the days before our departure I had instinctively and naturally assumed the senior position. And Lyle and Parmikan had been sly enough to go along with me, even addressing me as “Captain Roker” until we were on our way and it was too late to do anything about it.

“Well, Ms. Roker? Do you question the authority assigned by this document?”

“I question its wisdom. But I accept its validity.” I scanned down the rest of the page. Parmikan’s command extended from the time we left the Penrose Institute until the moment when we docked on our return. No loopholes. “I agree, you’re the captain. I don’t see anything here defining my duties, though, or saying that I’ll agree to them. So if you want to turn the drive off yourself, without my help…”

Stefan Parmikan said nothing, but his sliding brown eyes met mine for one triumphant split-second. He reached into his pocket, pulled out a tiny playback unit, and turned it on.

“I’m reporting for duty right now,” said a voice. It was my own.

“For the expedition described in Professor McAndrew’s letter to you? But the mission and your role in it are not yet fully defined.” That was Dorian Jarver.

“You can define that later. I’m here, and I’m ready to start.”

There was a pause, as that section of the recording ended. Then Jarver’s voice came again: “In accordance with Captain Jean Pelham Roker’s earlier statement, this serves to define her duties on the Hoatzin mission identified as Project Missing Matter. Ms. Roker will serve as a general crew member, taking her orders and assignments from Captain Stefan Parmikan and from Senior Officer Van Lyle.”

Set-up. But my own fault completely. I had felt bad vibrations the moment I met Parmikan and Lyle. Then I had gone right ahead and ignored my own instincts. Let’s call that my third mistake.

McAndrew was climbing back in through the tiny airlock. I turned to him. “Mac, suppose we turned the drive off every day for a minute or two, long enough to send a burst mode message back to Earth. Allowing for the time we need to power the drive down and back up, how much would that add to our total trip?”

He stared at me for a moment, then his jaw dropped and his face took on a strange half-witted vacancy. That was fine. It just meant that he was off in his own world, thinking and calculating. I had given up trying to understand what went on inside McAndrew’s head when he was solving a problem. Even though what I had asked him was straightforward and I could have done the calculation myself given a little time, I would bet money that he was not using any technique I’d have chosen. As one of the Institute members told me years ago, McAndrew has a mind that sees round corners.

“Five days,” he said after a few seconds. “Of course, that’s shipboard days. Two months Terran, allowing for time squeeze.”

“Quite acceptable,” said Parmikan. “Ms. Roker, please work out the necessary arrangements and bring them to me.”

He turned and headed off for the private area of his own bunk, leaving me to fume and curse. And then, after a few minutes, to sit down and work out the best times for a regular interruption to the drive. I had to work it into other activities, so that Parmikan would make his daily call with minimum disruption to ship routine.

McAndrew came to me when I was almost finished. “Jeanie, I didn’t catch on to what he wanted when you asked me that, or I’d have said it was hard to do. You don’t have to take this sort of guff from him.”

“I do.” I picked up the results of my efforts, aware that Van Lyle had been watching me all the time I was working. “You know the first rule of space travel as well as I do: Like it or not, you can only have one captain. Parmikan is the captain of the Hoatzin.”

I carried the schedule I had generated across to Parmikan’s curtained rest area. The little private spaces allotted to each of us were intentionally set as far apart from each other as possible, around the perimeter of the living capsule. I rapped on the curtain rail. “This is my recommended schedule,” I said, when Parmikan’s head poked through. I held it out to him, but he did not take it.

“Is it a simple procedure?” he asked.

“I believe so. I’ve done my best to make it as simple as possible.”

“Good. Then you should have no trouble carrying it out. Notify me when the drive is off, and we are ready for our first communication opportunity with Terra. By then I’ll have another assignment for you.”

His head vanished back through the curtain. I had an insight into Parmikan’s style of command. He would give all the orders. I would do all the work. This was Anna Lisa Griss’s revenge for my asserting my authority over her. I would have to obey Parmikan’s every random whim for two months.

I was still naive enough to think that would be enough to satisfy her. My fourth mistake, was that? I’m beginning to lose count.

I stayed angry at being ordered around, until I remembered Lyle and Parmikan’s general ignorance of shipboard matters. Then I thought, Hey, it’s better like this. How would you feel if Parmikan took over the controls himself? And I went away to set up the program to power down the drive at regular intervals.

Except that McAndrew had heard my exchange with Parmikan, and he was feeling sorry for me. He insisted that he would do the tedious job of changing the drive program schedule. I let him. It was quite safe to do so, because Mac’s such a perfectionist on this sort of thing that he sometimes makes me feel sloppy.

But Mac is only devious in scientific matters. He didn’t catch something in the Hoatzin’s overall mission profile that I would have noticed at once.

I discovered it much later, and almost too late. Call that my fifth mistake, and let’s stop counting.

To me, the interruptions to our outward progress were a useless nuisance. I have no idea what was sent or received by Parmikan and Lyle in their daily communications. I was specifically excluded from them, and in any case Parmikan had me far too busy with a hundred other things to worry much about messages — he had an absolute genius for thinking up demeaning and pointless tasks. I do know, though, that the person sending or receiving at the other end was not Dorian Jarver. The link was set up to a location on Terra, not to the Penrose Institute.

And McAndrew, being McAndrew, contrived to turn the periods when the drive was off into an opportunity. He decided that he could use those few dead minutes every day to perform his first experiments. One morning right after breakfast I went to the rear of the living capsule to escape from Van Lyle — he, and his probing eyes, followed me everywhere. I found McAndrew sitting beside his instrument panel, frowning at the wall.

“Problems?”

He shrugged, and scratched at the back of his balding head. “I’d have said no. Everything passes the internal checks. But look at this.” He pulled up a display. “I’ve got the most sensitive mass detectors ever, lined up on our final destination. All the other instruments confirm that there’s absolutely nothing out there. But see these.”

He pointed to small blips in the output level of the instruments.

“Noise?” I suggested. “Or the result of our high velocity? Or maybe a local effect, something on the Hoatzin?” He had told me that his new instruments were supernaturally sensitive to disturbance.

“No, they’re definitely external, and far-off. And regular. That’s just the signals I’d be getting if massive objects were flying, evenly spaced, across my field of view. Except there’s nothing there. It’s a total mystery.”

“Then you’ll just have to be patient. We’re already past turn-around. In twelve days we’ll be there, and you’ll be able to see for your—”

“Crewman Roker!” It was Parmikan’s voice, ringing through the living capsule. “Come here immediately. I have a task that must be performed at once.”

I took a deep breath, and held it. Another fun-filled day was beginning. Twelve more to go, before we came to rest in the most perfect nothingness known to humans, half a light-year from the Sun.

With the whole habitable space of the Hoatzin only four meters across, I knew before we left the Institute that we’d be living close. But given the lack of privacy, there was one form of closeness I had never expected.

The surprise came late in the evening on the twenty-third day out, when Mac was in the shielded rear of the living capsule muttering over his still-anomalous instrument readings. The blips were growing. With Parmikan’s consent Mac had gradually changed our course, angling the ship’s direction of travel towards the strongest source of signal. We would arrive a tenth of a light-year away from our original destination, but as McAndrew pointed out, the choice of that had been more or less arbitrary. Any place where the matter density was unusually low would serve his purpose equally well.

By eleven o’clock Stefan Parmikan was asleep. I was sitting cross-legged on my bunk, listening to an Institute lecture from my talking library. It was “Modern Physics for Engineers,” by Gowers, Siclaro, and McAndrew, a course designed to be less high-powered than the straight two-hundred-proof Institute seminar presentations. There were three other series available, of rapidly descending levels of difficulty. They each had official names, but inside the Institute they were known as “Physics for Animals,” “Physics for Vegetables,” and “Physics for Football Players.”

I had brought all four, just in case, but I was holding my own with “Physics for Engineers.” I was finally gaining a clearer idea of just why we had to charge off half a light-year from Sol.

Something was absent from the Universe, something that the best brains around thought had to be there: Missing matter.

The “bright stuff” — visible matter — isn’t nearly enough to make the Universe hover on the fine line between expanding forever, and collapsing back one day to the Big Crunch. That’s what the theorists want, but there’s only about one percent of the mass needed in the bright stuff. You can pick up a factor of ten or so from matter that’s pretty much the same as visible matter, but happens to be too cold to see, and that’s all.

This leaves you about a factor of ten short on mass. And there you stick. You have to start laying bets on other, less familiar materials.

Neutrinos moving up close to the speed of light — hot dark matter — are one candidate. There are scads of neutrinos around, generated soon after the Big Bang but damnably difficult to find by experiment. Neutrinos don’t interact much with ordinary matter. They’d slip through light-years of solid lead, if you happened to have light-years of lead available. They’re a candidate for the missing matter, but they’re not the front runner. They don’t give a Universe with the right lumpy structure, and anyway they come up short on total mass.

The other candidates are much slower and heavier than neutrinos. They’re the cold dark matter school, axions and photinos and gravitinos, and they don’t give the right lumpiness to the Universe, either. Even adding them to the neutrino mass, the whole thing still came up too small. McAndrew was saying, in effect, we’ve gone as far as theories can go. Let’s get out there, where the experiments have a chance to succeed, and measure how much hot dark matter and cold dark matter is around. Then we’ll know where we stand.

It was all fairly new to me. I was concentrating deeply, struggling with the theories of WIMPs — Weakly Interacting Massive Particles — when I was interrupted.

For the past three days I had been aware of Van Lyle hanging around me. I became a lot more aware of him when two arms suddenly went around me from behind, and two hands clasped my breasts.

“Hey, Jeanie,” Lyle’s voice whispered in my ear. “You’ve got lovely tits. It’s going to be nice and quiet for a while. Want to get friendly?”

I jerked forward along the bunk, untangling my legs and trying to pull myself free. He was hanging on tight. That hurt.

“Get your damned hands off me.” I wanted to say something a lot worse, but I knew we were going to be cooped up in the same space for another few weeks, no matter what. I had been trained to avoid onboard confrontations, and I wanted to stay cool and end this politely.

I swung around to face him and pushed myself away.

“Oh, don’t be like that.” He was grinning, a big, smarmy God’s-gift-to-women grin. “Come on. Lighten up. We could have some real fun.”

He reached out towards my breast again, and I pushed his hand away. “Quit that, Lyle! I tell you, I’m not having any.”

“You haven’t tried it. Lots of women could tell you, you won’t be disappointed. Want to have a look at my testimonials?” And then, as I pushed his groping hand away again, this time when it reached towards my crotch, “Hey, Jeanie, you’re strong. I just love strong women.”

“You do, do you?” I’d had it. “This strong enough for you?”

I swung with all my body behind it as his face came forward, and got him with my fist right on the bridge of his nose.

It hurt like hell — hurt me, I mean. I didn’t care how much it hurt him. But I don’t think he enjoyed it, because as the blood spurted out of his flattened nose and splashed all over my bunk, he let out a terrible howl that brought McAndrew running.

Just as well, because by that time I was upright, off my bunk, and all set to kick Lyle in the balls at least ten times as hard as I’d punched his nose. McAndrew got in the way before I could do it. He leaned close to Van Lyle, a rag in his hand to mop up blood.

“What happened?”

Lyle produced only a horrible snorting noise.

“Tripped as he was coming in here,” I said, “and banged his face on the edge of the bunk. Get the medical kit.”

McAndrew glanced at the bunk as Stefan Parmikan finally appeared. I knew that Mac was doing an instant height and angle match, and rejecting it. But he never said a thing. Nor did Lyle, unless you count the groans when Parmikan was moving his broken nose around in an attempt to achieve a reasonably straight result.

We fixed the nose, more or less, and sedated Lyle. Parmikan went back to bed. During the sleep period, McAndrew leaned over the edge of my bunk and whispered to me. “Jeanie? I know you’re awake. Are you all right?”

“I’m just fine.” I didn’t want him as furious as I was.

“He didn’t bang himself on the bunk, did he? He made advances to you, and you hit him.”

“What makes you think that?” Mac’s insights were supposed to be into Nature, but not human nature.

“He was talking about you two days ago, when you weren’t present. He said he wanted to take you to bed. Get a piece, he said.”

“And you were there? Why for God’s sake didn’t you stop him? Tell him that you and I are lovers, have been for years.”

There was a long, worried pause. “It wouldn’t have been right, talking about you like that. And Jeanie, I don’t own you, you know.”

McAndrew, McAndrew. If I weren’t so fond of you, I’d wring your scrupulous Puritan neck.

“But you know what?” he went on, “I’m afraid that it’s going to make for a more difficult working atmosphere during the experiments.”

It’s a good thing it was dark, so I couldn’t take a shot at his nose, too.

The first twenty-three days of the trip out had seemed pretty bad. I learned the next morning that the remaining five were going to be a lot worse — and then after that we had the period of McAndrew’s experiments to look forward to, followed by a four-week return journey to the Institute.

The pattern was established on the twenty-fourth day. Van Lyle was back on his feet early. The bruise from his broken nose had mysteriously spread, to give him two purple-black eyes. With a white, rigid plaster across the middle of his face, he resembled a vengeful owl as he staggered out of his bunk. He glared around him.

“The inside of this capsule is dirty. It must be cleaned.”

“It’s not bad,” I said. “It’s just the way you’d expect the ship to look after three weeks.”

“I’ll be the judge of that.” Lyle picked up a dish of soggy cereal, inverted it, and deliberately dropped it to the floor. “Get to work. This cabin first, then my quarters. I’ll be back to inspect your progress this afternoon.”

I held myself in — just. When Stefan Parmikan appeared ten minutes later, I had all the cleaning equipment out of the ceiling racks and ready for use.

He looked, not at me but past me. “What do you think you are doing?”

“Getting ready to clean the cabin. Following Officer Lyle’s instruction.”

“Very well. You can do that later. I need you to explain the procedure for ship automatic course tracking to me.”

Unbelievable. Could it be that Stefan Parmikan was at last taking an interest in the way that the Hoatzin worked? I rose to follow him, but he turned and pointed to the cleaning equipment.

“Put those away first, back in the ceiling racks. I’m not going to spend the whole day falling over your stuff. And I’m not going to waste time arguing. You can get everything out again later.”

It didn’t help to recognize that Parmikan was quoting my own words, about the luggage of his that I had refused to allow aboard.

I began to put away the cleaning equipment, and thought favorably of Fletcher Christian.

No one on the Hoatzin seemed happy for the next five days. Parmikan and Lyle constantly tried to push me over the edge, and were constantly disappointed. They came close, but I certainly wasn’t going to give them the pleasure of knowing how close.

And McAndrew, who should have been as happy as a pig because the time of his experiments had arrived, had become intense and introverted. The Hoatzin had homed in close to his strongest anomalous signal, but it did not seem to have resolved his problem.

“Look at this, Jeanie,” he said, during one of my rare breaks from slavery. I had just checked that the ship had achieved its final location and velocity, and confirmed that we were at rest again relative to Sol. “These are real-time signals, happening right this minute. I’ve got instruments focused on a region only two light-seconds from here. You can see the visual display of it on the left half of the screen.”

I looked. Other than a triangle of three bright reference stars, the visible wavelength display was blank.

“Nothing there,” I said.

“Quite right. And now, the input from the mass detectors. They’re set up to scan the same field, and I’ve got them in imaging mode focused for two light-seconds away.” McAndrew popped the mass detector result on the right, as a split-screen display.

I stared. I expected to see nothing on the right side of the screen, either, and that’s exactly what I saw. The region two light-seconds from us, where McAndrew’s mass detection instruments were focused, was empty of matter — more empty, in fact, than any other known region.

“Well,” I began to say. And then something impossible happened. The left-hand screen at visible wavelengths continued to show nothing but distant reference stars; but the screen displaying the mass imaging system inputs showed an object floating steadily across it, from top to bottom. The blob was clean-edged and irregular in shape, its outline like a fat, curved and pimpled cigar. It took maybe ten seconds from the first appearance on the top of the screen to its leisurely disappearance from the lower boundary. It must be moving at just a few miles a second relative to the Hoatzin.

“Mac, you’ve got the displays set up wrong. Those have to be showing different fields of view.”

“They’re not, Jeanie. I’ve checked a dozen times. They’re showing the same part of the sky.”

“Rerun it. Let me see it again.”

“I don’t need to. Wait twenty seconds, and you’ll see another one. About one a minute.”

We waited. At last a second shape, apparently identical to the first, came floating across the mass detector screen. And again the visible wavelength screen remained blank.

“Ultra-violet,” I said. “Or infrared, or microwave…”

“I’ve checked them all. Nothing, from radiation or particle sensors. Only the signal from the mass detectors.”

“So they’re black holes. Kernels. They have to be.”

“That’s exactly what I thought, when we were a ways off and the signal was just a fuzzy blob with no structure. But just you look at the shape of that” — a third shape like a thick, warty banana was crossing the screen — “when you know as well as I do that any black hole has to have at least rotational symmetry. Those things have no axis of symmetry at all. And another thing. I did an active test. I sent a particle stream off to intercept one of those objects. If it were a black hole, you’d get a return radiation signal as the particles were gravitationally caught. But I got nothing. The particles went right on through as though there wasn’t anything there at all.”

I had a strange, prickly feeling up the back of my neck. We were observing nothing, a vacuum specter, a lost memory of matter. By a knight of ghosts and shadows, I summoned am to tourney, ten leagues beyond the wide world’s end… Except that in our case, ten leagues had grown to half a light-year.

“Mac, they’re impossible. They can’t exist.”

“They do, though.” McAndrew’s eyes were gleaming. I realized that I had mistaken his emotion. It wasn’t frustration. It was immense, pent-up excitement and secret delight. “And now I’ve seen them in more detail, I know what they are.”

“What, then?”

“I’ll tell you — but not until we get a chance for a real close-up look. Come on, Jeanie.”

He headed straight for Parmikan’s private quarters, banged on the wall, and pulled the curtain to one side without waiting for an invitation. Parmikan and Lyle were both inside, heads close together. They had kept to themselves completely since the previous day, after an unusually long message to or from Earth. They jerked apart as McAndrew barged through.

“We want to move the Hoatzin a bit,” he said without preamble. “And I have to go outside. I’d like Captain Roker to go with me.”

If he was asking permission, calling me “Captain Roker” to Stefan Parmikan was the worst way to go about getting it. I expected an instant refusal. Instead a rapid glance passed between the two men, then Parmikan turned to McAndrew.

“What do you mean, move the ship?”

“Just a smidgeon, a couple of light-seconds. There’s something I need to look at as part of my experiments. As soon as we’re in the right position I need to take a couple of mass detectors outside with me and examine a structure. It will take a few hours, that’s all. But it’s a two-person job, and I’ll need help.”

I certainly didn’t expect that Lyle or Parmikan would volunteer for the job of helper, but equally I didn’t expect that they’d agree to my doing it — if I were outside, how could they give me disgusting chores? But Parmikan nodded his head at once.

“Right,” said McAndrew. His diffident manner had vanished. “Jeanie, while I get the equipment ready I want you to take the Hoatzin to encounter one of the anomalies. Put us smack in the middle, and set us to hold at zero relative velocity.”

I didn’t argue. But as he went off to the rear of the living-capsule, I did exactly half of what he had requested. A small, watchful region of my brain was awakening, from a slumber it must have been in ever since I decided to reply to McAndrew’s letter by flying straight to the Institute. Now I closed in on one of the objects and set us to zero relative velocity — but I kept our ship a couple of kilometers clear rather than providing McAndrew’s requested encounter. He might know exactly what he was dealing with, and be sure that it was safe. Until I had that knowledge, too, I was going to regard any region of empty space occupied by a mystery as possibly dangerous.

As I was completing my task I noticed a minor oddity in the operations of the Hoatzin’s computer. The program was functioning flawlessly, but as I directed each change in position or speed, a status light indicated that an extra data storage was being performed. The response time was a fraction of a second longer than usual.

I’d probably have caught it when at Parmikan’s insistence we switched the drive on and off every day, but Mac had programmed all those changes as a favor to me. And if McAndrew had been ready to go outside at once, I might have ignored it now. Instead, I took a look to see where the generated data were being stored.

I found a Dummy’s Delight.

The data I was creating were being placed in a trajectory control program of a type much despised by professionals. It was the sort of thing that anyone could use and no one ever did, because it was guaranteed to be inefficient. In a Dummy’s Delight, for every move made by the ship the inverse move was generated and stored. If the program were then executed, the ship would return to its point of origin along whatever convoluted trajectory it may have taken to fly out.

The program’s only advantage was simplicity. One push of a button, and all need for piloting went away.

But there was no way that we would fly back along our original trajectory — there were much more efficient thrust patterns. And I certainly hadn’t given the command to place the required data into the Dummy’s Delight before the Hoatzin left the Penrose Institute.

Had Mac done it? And if so, why?

My wariness node had started to work overtime. On impulse I wiped from memory the whole Dummy’s Delight sequence, and left a message on the control screen: AUTOMATIC RETURN PROGRAM TO TERRA HAS BEEN ERASED BY CAPTAIN ROKER. It seemed reasonable when I did it, but I started to have second thoughts as I hurried to join McAndrew. He had his mass detector survey instruments working as free-standing units and was already in his suit.

“Mac.” I waited until I had my own suit on, and was absolutely sure that we could not be overheard by Van Lyle or Stefan Parmikan. “Did you set up a Dummy’s Delight in the Hoatzin’s computer?”

He was busy, guiding the bulky detectors into the lock. “Now why would I do a daft thing like that?” he said, and vanished into the lock himself.

Why would he do a thing like that? I asked myself. Why would anyone do it? — unless they suspected that no competent pilot, like me or McAndrew, would be around to fly the Hoatzin on its return journey to Sol.

Paranoid? You bet. It’s the only way to fly.

I emerged from the lock into that great forever silence that fills all the space between the stars. Sol was dwindled, indistinguishable from dozens of others. I picked it out from its position, not its superior brightness. The region I floated in appeared totally empty and featureless, despite the suit’s vision enhancement systems. Particles were fewer here, the vacuum a little harder. But the human observer would never know the difference.

I glanced back at Sol. Look at the situation any way you liked; if I blew it and something went wrong, it was a long walk home.

I propelled myself gently away from the ship and towards McAndrew. He was staring at his mass detector readings in great irritation.

“Jeanie, you’ve made a mistake. We’re kilometers away from the source.”

“We certainly are. Two kilometers, to be exact. I know you can see right through it and it looks like nothing’s there, but I want to approach this particular nothing very carefully.”

He gave the patient sigh of a long-suffering martyr. “Ah, Jeanie. There’s no danger here, the way you’re thinking. I know just what this is.”

“Maybe. But you haven’t told me.”

“I will, though, right now. It’s shadow matter.” And then, seeing my stare, “I’m surprised you’ve not heard of it.”

“I know, Mac. I’m a constant disappointment to you. But I haven’t. So tell me.”

“It’s wonderful. Right out of supersymmetry theory. Soon after the Big Bang — about 10^-43 seconds after it, actually, before anything else we know about happened — gravity decoupled from everything else. Sort of like the way that radiation decoupled from matter, but the gravity decoupling happened much earlier. So then you had a symmetry breaking, a sort of splitting, and two types of matter were created: ordinary matter and shadow matter. Just like matter and anti-matter — except that matter and shadow matter can’t interact by strong nuclear forces, or radiation, or the weak nuclear force. They can only interact by gravitational influence. You’d never detect shadow matter by firing particles at it. We proved that for ourselves. The particles feel the gravitational force, but that’s tens of orders of magnitude too weak to do anything noticeable.”

I stared at nothing, in the direction that the mass detectors were pointing. “You’re saying that whatever is out there is as real as we are — but we can’t see it?”

“Can’t see it, never will be able to see it. Seeing depends on interaction with radiation. The only way to learn what we’ve found is through these.” He pointed at the mass detectors. “We’re safe enough, as I said. But we have to do some detailed mapping. Who knows what that is out there? It could be a shadow matter star — we don’t have any idea how big a star might be in that universe, or what the laws of force are. Or maybe we’re detecting a set of interstellar shadow matter spaceships, or a column of shadow matter ants marching in a shadow matter superworld.

“You think I’m joking, but I’m not. It could be anything. The only way we’ll get any idea what we’ve found is by plotting structure. That’s why I need you — it’s a two-person job, to make transects.”

We’re safe enough, he had said. But maybe only while we were outside the Hoatzin.

“Mac, before we start your work we’ve got to talk. I think we have a bad problem.” I told him about the Dummy’s Delight on the ship’s computer.

He frowned through his suit visor. “But why would they waste data storage on a thing like that?”

“So they could get home, even if something happened to both of us.” I took the last mental step, the one I had been resisting. “Mac, we’re not intended to return from this trip. The plan is for us to vanish while we’re out here. If the drive of the ship were turned on now, who’d ever know what had happened to us?”

He turned to stare at the Hoatzin. “They wouldn’t dare.”

“Not now they wouldn’t. I wiped the program they were relying on to fly them back. So they need us.” Or one of us. But I didn’t say that. “We’re safe enough for the moment.”

“But what about when we go back inside? We can’t stay out here forever.”

“I don’t have an answer for you. We’ve got enough air for six or seven hours. We have to think of something — soon.”

We had to think of something. But we didn’t succeed. My mind stayed blank. McAndrew is a superbrain, but not when it comes to this sort of problem. After half an hour floating free not far from the ship, he shook his head.

“It’s got me beat. But this is silly. There’s no point in sitting here doing nothing. We might as well get on with the measurements.”

He placed one mass detector in my care, with its inertial position sensor tuned to the Hoatzin as reference, and started to steer me under his direction from one fixed place to another, while he moved himself in constant relative motion. He apparently knew exactly what he wanted. That was just as well. My own thoughts were all on the situation aboard the ship. What would we do when our air ran low?

I worried that problem with no result while McAndrew made four straight-line passages, right through the middle of the kilometer-wide region that he described as shadow matter. The mass detectors confirmed that something was there. I saw absolutely nothing.

On the fifth passage through, McAndrew paused halfway. He called to me to move closer, while he carried his own detector through a complicated spiral in space. At the end of it he left his mass detector where it was, flew across to me, and examined the recording on my instrument.

“Well, I’m damned,” he said. “Jeanie, I think you were right. Stay there.” And leaving me mystified and feeling about as intelligent as a marker post, he flew away. This time he moved his mass detector through an even more complex path in space, pausing often and proceeding very cautiously.

“I’ve still no idea what this is, overall,” he said when he came back. “But I’ll tell you one thing for sure. There are structures in shadow space that I’ve never met in our spacetime.”

“Right about what?” I asked. “You just said I was right. But what was I right about?”

“That we ought not to set the ship in the middle of that, without knowing more about it. I’m seeing evidence of gravitational line singularities, or something very like them, running across the shadow matter region. You don’t find those in our universe. If we had flown in too close to one of them, we might have found ourselves in trouble.”

“You mean we’re not in trouble now? With Lyle and Parmikan waiting for us.”

“I’ve been thinking about that, too.” He came close, and his face was earnest and unshaven within his visor. “I think you’re overreacting. There’s no evidence at all that Lyle and Parmikan even knew there was a Dummy’s Delight set up in the Hoatzin’s computer. And certainly there’s no evidence they mean us any harm. But anyway,” he went on, before I could interrupt, “one thing’s for sure: When we go back in the lock, I should enter first while you stay outside. I know both of them, they respect me, and they’ll not do anything to hurt me.”

McAndrew is a pathetically bad liar. I didn’t argue with him. But when we were a few meters from the lock I said, “You’ve got it backwards. I’m the one they won’t hurt, because they need a pilot to get home. And you don’t know how to work our only weapon. Don’t stand too near the hatch of the lock.”

I dived for the airlock, pulled myself inside, and swung it closed in one movement, leaving Mac to bang on the outside. While the lock was filling with air I did a little work of my own. It required that three separate safety procedures be overridden, so it took a few minutes. At last I moved forward to open the inner lock door, then jumped back at once to stand by the outer one.

I didn’t know what I was expecting. Lyle and Parmikan, going about the normal business of the ship, with a stack of messy chores ready for me? Or waiting to complain that I had for no reason at all wiped out a program that one of them had set up in the computer, for a wholly innocent purpose?

What I hadn’t expected was a projectile weapon, held in Van Lyle’s hand and pointed right at my belly-button. I rammed my left fist down on the lock control, as the thought flashed through my head that there should have been a more thorough luggage inspection when we boarded the Hoatzin.

I moved as fast as I could, but they had been ready and waiting. I was too slow. Lyle pressed the trigger.

As he did so two things happened. Parmikan smacked at Lyle’s hand and screamed, “Don’t kill her! We need her to get us back.” That saved me, spoiling Lyle’s aim. In the same moment the outer lock door, its final safety trigger broken by the force of my fist, blew outward in a rush of air.

I flew out with it, knowing that my last-ditch plan to fight back had failed. I was hit. And my secret weapon was useless, because Lyle and Parmikan were already wearing suits.

I felt the fainting weakness that comes with a sudden drop of blood pressure. Then my suit resealed, and a few seconds later McAndrew was grabbing at me to halt my spin. He had followed me as I emerged in that crystal cloud of cooling air.

I felt pain for the first time, and looked down. Half the calf of my left leg was missing. The automatic tourniquet had cut in and tightened below the knee. The flow of blood from the wound had already stopped. I would live — if we somehow survived the next few minutes.

Which didn’t seem likely. Lyle and Parmikan had emerged from the lock, and Lyle still had his gun. He raised it. And shot me again.

Or he would have done, had he been the least bit familiar with freefall kinematics and momentum conservation. Instead the recoil of his gun sent him rolling into a backward somersault, while the bolt itself flew who knows where.

Before Lyle could sort himself out and fire again, McAndrew was dragging me away, using his suit propulsion system at maximum setting to carry both of us along. One nice thing about Mac, he didn’t need much data to form a conclusion.

“Don’t try a long shot.” That was Parmikan to Lyle, over the suit radio. “She’s injured. Get in close. Then we finish him and grab her. But don’t kill her — she’s taking us home.”

“I won’t kill her.” That was Lyle, the white plaster on his nose vivid through the suit’s visor. “Not ’til I’m done with the bitch. She’ll wish she was dead before that.”

They were coming after us, knowing that we had no place to hide. It was our misfortune to find ourselves, weaponless and pursued, in the emptiest quarter of known space. Nowhere to run to, and soon we would be out of air.

McAndrew was retreating anyway, dragging me along with him, but not in a simple, straight-line run. We were zigzagging up and across and sideways, rolling all over the sky; which made good sense if you were trying to evade being shot, and no sense at all when your enemy had just declared that he would not shoot until he got close.

Then we stopped dead. Mac glanced all around him, sighting for Parmikan and Lyle, the two mass detectors just where we had left them, and the shape of the Hoatzin, further off. He lifted us a few meters upward, and halted again.

“Here we are, then,” he muttered. “And here we stay.”

Lyle and Parmikan hadn’t moved while Mac and I had been corkscrewing our way around in space. Now they started towards us. Soon I could see their faces, white in the reflected glow of the visors’ built-in instruments.

Still McAndrew didn’t move. The feeling of distance and unreality that had swamped me the moment I was shot started to fade. At last I was scared. But when I started my propulsion system, ready to take off again away from the advancing men, Mac held out his hand to stop me.

“No, Jeanie. Hold by, and don’t move.”

They were closing on us. Parmikan was two or three meters in the lead. Lyle still held the gun, but he had learned his lesson. He would not fire again until he was at point-blank range, too close to be thrown off in his aim by the effects of free-fall rotation.

“Mac!” We couldn’t stand still and be slaughtered like sheep. I swung to argue with him, and saw the expression on his face. He was agonized and biting his lower lip. “Mac, come on. We can’t just give in.”

But he was shaking his head at me. “I’m sorry, Jeanie,” he said. “This isn’t me. I can’t go through with it. No matter what happens next, I have to give them a chance.” And he lifted his arm towards Lyle and Parmikan. “Don’t come any closer. Stay right there. You are in terrible danger.”

That stopped them — for a second or two. They stared all around, and saw nothing. Lyle snorted through his broken nose, while Parmikan laughed aloud for the first time since I had met him.

“Don’t try that on us, McAndrew,” he said. “We weren’t born yesterday. If you stand still, I promise you’ll get yours clean and quick.”

He was moving forward again. My suit’s vision enhancement showed the grin on his shapeless mouth. He looked as happy as I had ever seen him. And then the clean white of his suit was broken by a thin black line that ran across Stefan Parmikan from hip to hip, about two inches below his navel.

He stared down at himself as the line widened. He started to scream, and tried to back up.

It was too late. His motion carried him forward. As it did so he shrank, shortening and squeezing in towards his hips. The thin black line became a rolling tunnel of red and purple across his whole body. Twisted internal organs were moving into it from above and below. Then Parmikan had passed all the way through.

The scream ended. A pair of legs, still held together at the top, came floating on towards us. Separate from it moved a torso, cleanly severed. Blood gouted out and froze as a fine icy spray.

Lyle, a few meters behind, had enough time to stop. He paused, still holding the gun.

“Hand that over.” I summoned what little energy I had and spoke over the suit radio before McAndrew had time to react. And then, when Lyle hesitated, I said, “Hand it over right now. Or get just the same as he did.”

He hardly seemed to be listening. His eyes were following the horror of Parmikan’s severed body. But he nodded and released the gun, which floated gently away from him.

It’s a measure of how far gone I was that I actually started out towards it, until McAndrew grabbed me.

“You stay where you are, too,” he said. “And Lyle, don’t move a millimeter until we come around and get you. There’s other gravitational line singularities through this whole volume.”

We began to move again, McAndrew hauling me along like ballast in a strange helical path that wound its way towards Van Lyle. Finally McAndrew was able to reach out and snag the gun.

“All right.” He waved it at Lyle, then towards the Hoatzin. “We’ve got a clear run from here to the ship. You start that way. And remember that I understand freefall ballistics a lot better than you do. I won’t miss.”

The three of us drifted slowly back to the lock, but McAndrew would not let Van Lyle enter. He handed me the gun. “You first, Jeanie. Can you fix the lock so it works?”

“I think so.” I moved inside. “I just have to reset the safety interlocks.”

I made it sound trivial, and it should have been. But I kept half blacking-out before I was done and able at last to refill the interior of the Hoatzin with air.

It seemed forever before the lock cycled again. I wondered and stayed tense. I had the gun. Suppose Lyle had taken advantage of that and overpowered McAndrew?

I dropped those worries when Lyle emerged from the inner lock. His manner and bearing were of a crushed man with no fight left in him. I made him take his suit off, but I kept my own on until McAndrew finally came through the lock.

He didn’t give Lyle a look. He came straight across to me and examined my injured leg.

“I’m sorry, Jeanie,” he said, as he helped me ease out of my suit. “I know I put us in danger, warning them the way I did. If Parmikan had stopped in time we might have been killed. But I couldn’t let them go on moving into that line singularity, without giving them at least a chance to stop. I just couldn’t do that. You’d have done the same thing, wouldn’t you?”

“Of course I would.”

Like hell. If it had been up to me, Lyle would be floating around in two halves, the same as Stefan Parmikan. But then, compared with McAndrew I’m a barbaric, vengeful throwback. “Don’t worry about it, Mac. What you did was the right thing.”

I winced, as the suit came free from my calf and caught on crusted blood. “So whose idea was it, Van Lyle?” I said. “Who decided that on this expedition, McAndrew and I wouldn’t be going back?”

He had been sitting slumped over, staring at the floor. He looked up, opened his mouth to speak, then changed his mind. He shook his head.

I didn’t blame him. When we arrived home he would be charged and surely convicted; but nothing the system authorities could do to him was half as bad as Anna Lisa Griss’s vengeance if he betrayed her.

McAndrew had gone across to the capsule’s medical center and was returning with two spray syringes. “I’m going to put you under, Jeanie, while I dress your leg,” he said. “You’ll have to wait until we’re home for a full repair. But first, to be safe…”

He went to Van Lyle and pressed the loaded syringe against the back of the stooped man’s neck. Lyle tried to stand up, with a startled expression on his face. It was already too late.

“Better if we keep him under all the way back,” Mac said, as after a few struggling seconds Lyle slid forward and fell face-down on the floor. “That way we don’t have to worry.”

I wasn’t worrying. I was going to be next, and physically I was ready for it. My calf was beginning to throb mercilessly. Still I held up my hand in protest. “Mac, wait a minute. We shouldn’t head back until you’ve finished your experiments. And you’ve hardly started.”

He moved behind me. “Don’t be daft, Jeanie. I can come here anytime. And I surely will. There’s big questions to be answered. I need to map the structure of those shadow matter objects in more detail. And now we’ve got another candidate for the hidden matter. How much is cold dark matter, how much hot dark matter, how much shadow matter?”

The cool nozzle of the syringe touched the back of my neck, and the spray diffused through my skin. I felt the effect at once as a pleasant, relaxing warmth that spread through my whole body.

“Mac,” I said, as the capsule of the Hoatzin began to blur around me. “You saved us, but I don’t know how you did it. How did you know where to go, to put that gravity singularity right between us and those two?”

“Easy enough,” he said. “I had the measurements from the mass detectors. That made it a standard problem of inverse potential theory: Given the field, where are the masses needed to generate it? I already felt sure that there were line singularities of shadow matter, ones that would work — gravitationally — on anything in our universe that encountered them. But just where were they? I worked that out while you were inside the lock, playing your fun and games with Lyle and Parmikan. Of course, I had to make simplifying assumptions and hope they wouldn’t affect the answer. And it would have been really nice to have a computer. But there was no time for that. I did what I could.”

I did what I could. What he had done, in the few minutes before I was blown out of the lock in a gust of freezing air, was to solve, mentally, a problem that would have taken me half a day to set up, and a computer to solve. And he had done it while knowing that the next half hour might end his own life.

Cold Dark Matter, Hot Dark Matter, Shadow Matter. The words spun through my mind as the world darkened, and McAndrew’s earnest face faded before my eyes. Cold Dark Matter, Hot Dark Matter, Shadow Matter.

Which one had dominated our past, to create the present structure of the Universe?

I had no idea. All I knew for sure as I slid into unconsciousness was that the future of our Universe was going to be dominated by cool grey matter; the sort that McAndrew and a few rare others like him have between their ears.