She yawned again.

"I'm going to make some coffee," she said. "If I don't, I'll fall asleep. You'll have some too?"

She filled an electric kettle, and while she spooned instant coffee into two mugs Lyra stared at the Chinese pattern on the back of the door.

"What's that?" she said.

"It's Chinese. The symbols of the I Ching. D'you know what that is? Do they have that in your world?"

Lyra looked at her narrow-eyed, in case she was being sarcastic. She said: "There are some things the same and some that are different, that's all. I don't know everything about my world. Maybe they got this Ching thing there too."

"I'm sorry," said Dr. Malone. "Yes, maybe they have."

"What's dark matter?" said Lyra. "That's what it says on the sign, isn't it?"

Dr. Malone sat down again, and hooked another chair out with her ankle for Lyra.

She said, "Dark matter is what my research team is looking for. No one knows what it is. There's more stuff out there in the universe than we can see, that's the point. We can see the stars and the galaxies and the things that shine, but for it all to hang together and not fly apart, there needs to be a lot more of it—to make gravity work, you see. But no one can detect it. So there are lots of different research projects trying to find out what it is, and this is one of them."

Lyra was all focused attention. At last the woman was talking seriously.

"And what do you think it is?" she asked.

"Well, what we think it is—" As she began, the kettle boiled, so she got up and made the coffee as she continued. "We think it's some kind of elementary particle. Something quite different from anything discovered so far. But the particles are very hard to detect… Where do you go to school? Do you study physics?"

Lyra felt Pantalaimon nip her hand, warning her not to get cross. It was all very well, the alethiometer telling her to be truthful, but she knew what would happen if she told the whole truth. She had to tread carefully and just avoid direct lies.

"Yes," she said, "I know a little bit. But not about dark matter."

"Well, we're trying to detect this almost-undetectable thing among the noise of all the other particles crashing about. Normally they put detectors very deep underground, but what we've done instead is to set up an electromagnetic field around the detector that shuts out the things we don't want and lets through the ones we do. Then we amplify the signal and put it through a computer."

She handed across a mug of coffee. There was no milk and no sugar, but she did find a couple of ginger biscuits in a drawer, and Lyra took one hungrily.

"And we found a particle that fits," Dr. Malone went on. "We think it fits. But it's so strange… Why am I telling you this? I shouldn't. It's not published, it's not refereed, it's not even written down. I'm a little crazy this afternoon."

"Well…" she went on, and she yawned for so long that Lyra thought she'd never stop, "our particles are strange little devils, make no mistake. We call them shadow particles, Shadows. You know what nearly knocked me off my chair just now? When you mentioned the skulls in the museum. Because one of our team, you see, is a bit of an amateur archaeologist. And he discovered something one day that we couldn't believe. But we couldn't ignore it, because it fitted in with the craziest thing of all about these Shadows. You know what? They're conscious. That's right. Shadows are particles of consciousness. You ever heard anything so stupid? No wonder we can't get our grant renewed."

She sipped her coffee. Lyra was drinking in every word like a thirsty flower.

"Yes," Dr. Malone went on, "they know we're here. They answer back. And here goes the crazy part: you can't see them unless you expect to. Unless you put your mind in a certain state. You have to be confident and relaxed at the same time. You have to be capable– Where's that quotation…"

She reached into the muddle of papers on her desk and found a scrap on which someone had written with a green pen. She read: "'…Capable of being in uncertainties, mysteries, doubts, without any irritable reaching after fact and reason.' You have to get into that state of mind. That's from the poet Keats, by the way. I found it the other day. So you get yourself in the right state of mind, and then you look at the Cave—"

"The cave?" said Lyra.

"Oh, sorry. The computer. We call it the Cave. Shadows on the walls of the Cave, you see, from Plato. That's our archaeologist again. He's an all-around intellectual. But he's gone off to Geneva for a job interview, and I don't suppose for a moment he'll be back… Where was I? Oh, the Cave, that's right. Once you're linked up to it, if you think, the Shadows respond. There's no doubt about it. The Shadows flock to your thinking like birds…"

"What about the skulls?"

"I was coming to that. Oliver Payne—him, my colleague—was fooling about one day testing things with the Cave. And it was so odd. It didn't make any sense in the way a physicist would expect. He got a piece of ivory, just a lump, and there were no Shadows with that. It didn't react. But a carved ivory chess piece did. A big splinter of wood off a plank didn't, but a wooden ruler did. And a carved wooden statuette had more… I'm talking about elementary panicles here, for goodness' sake. Little minute lumps of scarcely anything. They knew what these objects were. Anything that was associated with human workmanship and human thought was surrounded by Shadows…"

"And then Oliver—Dr. Payne—got some fossil skulls from a friend at the museum and tested them to see how far back in time the effect went. There was a cutoff point about thirty, forty thousand years ago. Before that, no Shadows. After that, plenty. And that's about the time, apparently, that modern human beings first appeared. I mean, you know, our remote ancestors, but people no different from us, really…"

"It's Dust," said Lyra authoritatively. "That's what it is."

"But, you see, you can't say this sort of thing in a funding application if you want to be taken seriously. It does not make sense. It cannot exist. It's impossible, and if it isn't impossible, it's irrelevant, and if it isn't either of those things, it's embarrassing."

"I want to see the Cave," said Lyra.

She stood up.

Dr. Malone was running her hands through her hair and blinking hard to keep her tired eyes clear.

"Well, I can't see why not," she said. "We might not have a Cave tomorrow. Come along through."

She led Lyra into the other room. It was larger, and crowded with anbaric equipment.

"This is it. Over there," she said, pointing to a screen that was glowing an empty gray. "That's where the detector is, behind all that wiring. To see the Shadows, you have to be linked up to some electrodes. Like for measuring brain waves."

"I want to try it," said Lyra.

"You won't see anything. Anyway, I'm tired. It's too complicated."

"Please! I know what I'm doing!"

"Do you, now? I wish I did. No, for heaven's sake. This is an expensive, difficult scientific experiment. You can't come charging in here and expect to have a go as if it were a pinball machine… Where do you come from, anyway? Shouldn't you be at school? How did you find your way in here?"

And she rubbed her eyes again, as if she was only just waking up.

Lyra was trembling. Tell the truth, she thought. "I found my way in with this," she said, and took out the alethiometer.

"What in the world is that? A compass?"

Lyra let her take it. Dr. Malone's eyes widened as she felt the weight.

"Dear Lord, it's made of gold. Where on earth—"

"I think it does what your Cave does. That's what I want to find out. If I can answer a question truly," said Lyra desperately, "something you know the answer to and I don't, can I try your Cave then?"