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.

SIXTH CHRONICLE: The Invariants of Nature

“I must say it was a surprise to me that you came here at all,” Van Lyle said pleasantly. “You really have to hand it to the Director. Anna Griss predicted all of this, you know — the effect of the announcement, McAndrew’s arrival, and then yours. Very perceptive of her. But, then, isn’t that exactly why she has the job of Administrator, and we do not?”

He was standing in front of a huge pair of metal doors, checking a set of dials built into the frame. On the other side of them lay the processing vats, where all organic tissues — muscles, bones, nails, skin and hair — were dissolved to basic biotic molecules. Warning signals were splashed all over the chamber, and on both the doors: CONTROLLED ACCESS — DANGER, CORROSIVE GASES AND LIQUIDS — DO NOT PROCEED WITHOUT PROTECTIVE SUITS — OFFICIAL DEPARTMENT REPRESENTATIVES ONLY PERMITTED BEYOND THIS POINT.

Van Lyle turned to me questioningly. “Impressive, wouldn’t you say? Don’t be coy, Captain. I’d really like to hear your opinions on all this.”

I rolled my eyes at him. I was sitting upright in a metal wheelchair. My wrists and elbows were bound to the chair arms with broad fiber tape, the sort that is hard to unstick and just about impossible to break. My lower legs were lashed to the chair’s metal struts with the same material. A broad sticky strip of it covered my face, from just below my nose to the point of my chin.

“Ah, I see the problem,” Lyle went on. “But are you ready to talk nicely now, and not make a fuss?”

I nodded — one of the few degrees of freedom available to me.

Van Lyle nodded back. “Very good! And just in case you feel tempted to change your mind, let me point out that it would be quite pointless. This part of the installation is all automated. No one is here but the two of us.”

He came across to me and touched one end of the tape that covered my mouth. But instead of pulling it loose, he paused to run his fingers along one side of my nose, and back down the other.

“What a nice, shapely adornment,” he said. “Not at all like mine, eh? Before we finish, we’ll have to do something about that.”

I hadn’t realized until that moment just how much he hated me. His nose was bent and slightly flattened, detracting from his rugged blond good looks. The mouth beneath the crooked nose twisted with anger as he ripped the tape away from my mouth.

I worked my lips against each other, wincing. A layer of skin had been torn away by the super-adhesive tape, along with every fine hair on my face. I felt a trickle of blood down my chin.

The less discussion of noses, though, the better. I had broken Van Lyle’s, half a light-year away from Sol, when he wouldn’t take his lecherous hands off me. That had been long ago, but unfortunately he didn’t seem willing to forget it.

“You know McAndrew,” I said. “All it took was the right word, and he was ready to head for Earth. Nothing that I said could stop him from coming.”

“So I understand.” Lyle nodded. “But you, Jeanie — surely you’re much more sophisticated than that? I would have bet money against you following him down here.”

Van Lyle’s calling me Jeanie made my flesh crawl, but he was right. I didn’t have the excuse that Mac had, the siren song, the magic words that had left him helpless: a new invariant of nature.

“You don’t understand,” I said. “I’ve spent half my life chasing after Mac when he got into trouble. By now it’s second nature. But usually it’s to some place halfway to the stars — not a trip down to Earth.”

I had no real interest in telling any of this to Van Lyle, true as it might be. I was merely stalling, postponing the moment when he would tape my mouth again and carry out the next stage of the proceedings. I had little doubt what that was going to be. Lyle hadn’t hauled me down to this processing plant, far offshore and a hundred meters beneath the surface of the sea, just to show off the advanced technology of Earth’s Food Department.

It was also a very bad sign that he had mentioned the name of Anna Griss. In the past he had always refused to admit that he worked for her.

I wondered what he was waiting for now. It shows how desperate I was feeling, but I actually hoped he might be planning another shot at raping me. Let him do anything — anything that might provide enough time for help to arrive, or give me a thin chance of resistance. That was better than being strapped in the wheelchair, able only to move my head and trunk from side to side.

I didn’t have much hope. This wasn’t my environment, it was theirs. I might have an edge in deep space, but down on Earth, Van Lyle and Anna Griss held home field advantage.

And suddenly I had no hope at all. Because I heard the steel doors at the back of the chamber open, the ones through which I had been wheeled in. There was the squeak of unoiled bearings, and a few seconds later another wheelchair was rolled alongside mine.

McAndrew sat in it, his legs and arms tied to the chair’s metal struts, not by sticky tape but by thick, knotted cords. His mouth was not covered.

He stared across at me miserably. “I’m sorry, Jeanie,” he said. “I really am. This is all my fault, every bit of it.”

I tried to smile at him, and winced at raw, stripped skin. My lips began to bleed again. “Don’t feel bad, Mac,” I mumbled. “If it’s your fault, it’s my responsibility.”

It had started at the Penrose Institute, over a month ago. I had been on the way home after a routine Europan delivery run. Orbital geometries happened to be favorable, so it was the most natural thing in the world for me to drop in on McAndrew. The Institute, after a disastrous couple of years of bureaucratic rule, was once more under the steady but informal guiding hand of old Dr. Limperis, dragged out of retirement to put things right. I wanted to see how everything was going, and renew old acquaintances.

I headed straight for Mac’s working quarters. He was not there. Instead, Emma Gowers was loafing in his favorite chair and staring at a display.

“Off in the communications center,” she said. “He’ll be back in a few minutes. You might as well wait here.” She was as blond, beautiful and blowzy as ever. And presumably as brilliant. She was the Institute’s resident expert on multiple kernel arrays.

“Is he all right?” I asked. Mac usually had to be dragged out of his own office, unless he was off somewhere running an experiment.

“Oh, he’s fine.” Emma pushed her mass of blond hair higher on her head. “But you know McAndrew. He’s got another pet project going. You can hardly talk to him any more.”

I nodded. It was the most natural thing in the world to find McAndrew in the grip of a new scientific obsession. He would be delighted to see me, I knew that. But he might also be only vaguely aware of my presence.

I sat down next to Emma. “What is it this time?”

“There’s talk of a new fundamental invariant. I’m skeptical, frankly, but he’s a believer — at least enough to want to check it out for himself.”

“Educate me, Emma. What do you mean, a fundamental invariant?”