“Which I can’t believe was a coincidence,” she told Dan Ys-tebo as they walked into the center’s physics lab, now crowded with researchers.

He laughed uncomfortably, his big belly wobbling. “I don’t know why you brought me here. This isn’t exactly my field. And you have no jurisdiction here.”

“But you spent long enough in the asylum with Reid Malen-fant. This is more spooky stuff, Dan. Somebody has to figure out what all this really means. If not us, who?”

“Umm,” he said doubtfully.

In the lab, they confronted the anomaly that had killed Wayne Dupree.

Tinkerbell in a cage, Bill Tybee called it, and that was exactly what it looked like. Just a point of light that glowed brightly, like a captive star, bobbing around in a languid, unpredictable loop inside its ramshackle trap of wire. The anomaly was so bright it actually cast shadows of its wire mesh cage: long shadows that fell on the white-coated scientist types who crawled around the floor, and on their white boxes and probes and softscreens and cameras and tangles of cabling, and even on the primary-color plastic walls of the schoolroom, which were still coated with kids’ stuff, blotchy watercolor paintings and big alphabet letters and posters of the last rhinos in their dome in Zambia.

It was this contradiction, the surreally exotic with the mundane, that made Maura’s every contact with these children so eerie.

Dan Ystebo was beside her. “It looks as if someone found a way to split the atom in the middle of a McDonald’s, doesn’t it?”

“Tell me what’s going on here, Dan.”

He guided her forward through the nest of cabling toward the glowing thing in the cage. There was a protective barrier of white metal thrown up a yard from the cage itself. “Hold your hand out,” he said.

She held her palm up to the glow, as if warming it by a fire. “By golly, I can feel the heat. What makes it glow?”

“The destruction of neutrons from the atmosphere. Step a little closer.”

She stepped right up to the protective barrier, nervous. This time she felt a ripple in the flesh of her hand, a gentle tugging. When she moved her hand from side to side she felt the wash of some invisible force.

“What’s that?”

“Gravity,” Dan said.

“Gravity? From the anomaly?”

“At its surface the gravity pulls about thirty thousand G. But it drops off quickly, down to less than one percent of G a yard away. The anomaly masses about a million tons. Which, if it were water, would be enough to fill a fair-sized swimming pool.”

“All crammed into that little thing?”

“Yup. It’s around a sixteenth of an inch across. Right now these guys, the physicists here, don’t have a good handle on its shape. It’s presumably spherical, but it may be oscillating.”

“So it’s pretty dense.”

“A little denser than an atomic nucleus, in fact. So dense it shouldn’t even notice normal matter. An anomaly like that should pass right through the Earth like a bullet through a cloud.”

“Then how come it doesn’t fall through the floor right now?”

Dan looked uncertain. “Because of the cage.”

“This contraption the children built?”

“Maura, it seems to generate a very powerful, localized magnetic field. It’s a magnetic bottle that holds up the nugget.”

“How?”

“Hell, we don’t know. We can do this — we have to build magnetic bottles for fusion experiments — but only with such things as superconducting loops, and at vast expense. How the kids do it with a handful of copper wire and an old car battery…”

She nodded. “But this is where the potential is. The technological potential.”

“Yeah. Partly, anyhow. If we could manipulate magnetic fields of that strength, on that scale, so easily, we could build an operational fusion reactor for the first tune. Clean energy, Maura. But that’s not all.”

“So what is Tinkerbell? Some kind of miniature black hole?”

“Not quite as exotic as that.”

“Not quite?’“

“It seems to be a nugget of quark matter. The essential difference from ordinary matter is that the individual quark wave functions are delocalized, spread through a macroscopic volume…”

It took some time for Maura, cross-examining him, to interpret all this.

In ordinary matter, it seemed, atomic nuclei were made of protons and neutrons, which in turn were made of more fundamental particles called quarks. But the size of a nucleus was limited because protons’ positive charges tended to blow overlarge nuclei to bits.

But quarks came in a number of varieties.

The ones inside protons and neutrons were called, obscurely, “up” and “down” quarks. If you added another type of quark to the mix, called “strange” quarks — a geeky term that didn’t surprise Maura in the least — then you could keep growing your positive-charge “nuclei” without limit, because the strange quarks would hold them together, And that was a quark nugget: nothing more than a giant atomic nucleus.

“We’ve actually had evidence of quark nuggets before — probably much smaller, fast-moving ones — that strike the top of the atmosphere and cause exotic cosmic-ray events called Cen-tauro events.”

“So where do the nuggets come from?”

Dan rubbed his nose. “To make a nugget you need regions of very high density and pressure, because you have to break down the stable configuration of matter. You need a soup of quarks, out of which the nuggets can crystallize. We only know of two places, in nature, where this happens. One place is — was — the Big Bang. And the nuggets baked back there have wandered the universe ever since. The theory predicts we should find Bang nuggets from maybe a thousand tons to a billion. So our nugget

is right at the middle of the range.”

“Where else?”

“In the interior of a neutron star. A collapsed supernova remnant: very small, very hot, very dense, the mass of the sun crammed into the volume of a city block. And when the pressure gets high enough quark matter can form. All you need is a tiny part of the core of the star to flip over, and you get a quark matter runaway. The whole star is eaten up. It’s spectacular. The star might lose twenty percent of its radius in a few seconds. Maybe half the star’s mass — and we’re talking about masses comparable to the sun, remember — half of it is turned to energy, and blown out in a gale of neutrinos and gamma rays.”

Quark matter runaway. She didn’t like the sound of that. “Which origin are we favoring here?”

“I’d back the Big Bang. I told you our nugget is right in the middle of the mass range the cosmogenic-origin theory predicts. On the other hand we don’t have a real good mass spectrum for neutron-star nuggets, so that isn’t ruled out either. But then there’s the slow velocity of our nugget. The nuggets should squirt out of neutron stars at relativistic velocities. That is, a good fraction of light speed. But the Big Bang nuggets have been slowed by the expansion of the universe…”

Slowed by the expansion of the universe. Good God, she thought. What a phrase. This nugget is a cosmological relic, and it’s right here in this plastic schoolroom. And brought here, perhaps, by children.

He spread his hands. “Anyhow that’s our best guess. Unless somebody somewhere is manufacturing nuggets. Ha ha.”

“Funny, Dan.” She bent to see closer. “Tell me again why Tinkerbell shines. Neutrons?”

“It will repel ordinary nuclei, because of the positive charges. But it can drag in free neutrons, which have no charge. A neutron is just a bag of quarks. The nugget pulls them in from the air, releasing energy in the process, and the quarks are converted to the mix it needs.”

Converted. Runaway. “Dan, you said something about a drop of this stuff consuming an entire star. Is there any possibility that this little thing—”

“Could eat the Earth?”