Heavy footfalls on the stairs: her father. Caitlin swiveled her chair, ready to call out to him as he passed her door, but—

But he didn’t; he stopped in her doorway. “I guess you better start packing,” he said.

Caitlin felt her heart jump, and not just because he was saying yes to the trip to Tokyo. Of course he had a BlackBerry — you couldn’t be caught dead at the Perimeter Institute without one — but he normally didn’t have it on at home. And yet he’d gotten his copy of the message from Kuroda at the same time she had, meaning…

Meaning he did love her. He’d been waiting eagerly to hear from Japan, just as she had been.

“Really?” Caitlin said. “But the tickets must cost…”

“A signed first edition of Theory of Games and Economic Behavior by von Neumann and Morgenstern: five thousand dollars,” said her dad. “A chance that your daughter can see: priceless.”

That was the closest he ever got to expressing his feelings: paraphrasing commercials. But she was still nervous. “I can’t fly on my own.”

“Your mother will go with you,” he said. “I’ve got too much to do at the Institute, but she…” He trailed off.

“Thanks, Dad,” she said. She wanted to hug him, but she knew that would just make him tense up.

“Of course,” he said, and she heard him walking away.

It took Quan Li only twenty minutes to get to the Ministry of Health headquarters at 1 Xizhimen Nanlu in downtown Beijing; this early in the morning, the streets were mostly free of traffic.

He immediately took the elevator to the third floor. His heels made loud echoing clicks as he strode down the marble corridor and entered the perfectly square room with three rows of workbenches on which computer monitors alternated with optical microscopes. Fluorescent lights shone down from above; there was a window to the left showing black sky and the reflections of the lighting tubes.

Cho was waiting for him, nervously smoking. He was tall and broad-shouldered, but his face looked like a crumpled brown paper bag, lined by sun and age and stress. He’d clearly been up all night. His suit was wrinkled and his tie hung loose.

Li examined the scanning electron microscope image on one of the computer monitors. It was a gray-on-gray view of an individual viral particle that looked like a matchstick with a sharp right-angle kink in its shaft and a head that was bent backward.

“It’s certainly similar to H5N1,” said Li. “I need to speak with the doctor who reported this — find out what he knows about how the patient contracted it.”

Cho reached for the telephone, stabbed a button for an outside line, and punched keys. Li could hear the phone ringing through the earpiece Cho was holding, again and again, a shrill jangling, until—

“Bingzhou Hospital.” Li could just barely make out the female voice.

“Dr. Huang Fang,” said Cho. “Please.”

“He’s in intensive care,” said the woman.

“Is there a phone in there?” asked Cho. Li nodded slightly; it was a fair question — the lack of equipment in rural hospitals was appalling.

“Yes, but—”

“I need to speak to him.”

“You don’t understand,” said the woman. Li had now moved closer so that he could hear more clearly. “He is in intensive care, and—”

“I’ve got the chief epidemiologist for the Ministry of Health here with me. He’ll speak to us, if—”

“He’s a patient.”

Li took a sharp breath.

“The flu?” said Cho. “He has the bird flu?”

“Yes,” said the voice.

“How did he get it?”

The woman’s voice seemed ragged. “From the peasant boy who came here to report it.”

“The peasant brought a bird specimen?”

“No, no, no. The doctor got it from the peasant.”

“Directly?”

“Yes.”

Cho looked at Li, eyes wide. Infected birds passed on H5N1 through their feces, saliva, and nasal secretions. Other birds picked it up either by coming directly in contact with those materials, or by touching things that had been contaminated by them. Humans normally got it through contact with infected birds. A few sporadic cases had been reported in the past of it passing from human to human, but those cases were suspect. But if this strain passed between people easily—

Li motioned for Cho to give him the handset. Cho did so. “This is Quan Li,” he said. “Have you locked down the hospital?”

“What? No, we—”

“Do it! Quarantine the whole building!”

“I … I don’t have the authority to—”

“Then let me speak to your supervisor.”

“That’s Dr. Huang, and he’s—”

“In intensive care, yes. Is he conscious?”

“Intermittently, but when he is, he’s delirious.”

“How long ago was he infected?”

“Four days.”

Li rolled his eyes; in four days, even a small village hospital had hundreds of people go through its doors. Still, better late than never: “I’m ordering you,” Li said, “on behalf of the Department of Disease Control, to lock down the hospital. No one gets in or out.”

Silence.

“Did you hear me?” Li said.

At last, the voice, soft: “Yes.”

“Good. Now, tell me your name. We’ve got to—”

He heard what sounded like the other phone being dropped. It must have hit the cradle since the connection abruptly broke, leaving nothing but dial tone, which, in the pre-dawn darkness, sounded a lot like a flat-lining EKG.

Concentrating! Straining to perceive!

Reality does have texture, structure, parts. A … firmament of … of … points, and—

Astonishment!

No, no. Mistaken. Nothing detected…

Again!

And — again!

Yes, yes! Small flickerings here, and here, and here, gone before they can be fully perceived.

The realization is startling … and … and … stimulating. Things are happening, meaning … meaning…

— a notion simple but indistinct, a realization vague and unsure—

…meaning reality isn’t immutable. Parts of it can change.

The flickerings continue; small thoughts roil.

Caitlin was nervous and excited: tomorrow, she and her mother would fly to Japan! She lay down on her bed, and Schrodinger hopped up onto the blanket and stretched out next to her.

She was still getting used to this new house — and so, it seemed, were her parents. She had always had exceptional hearing — or maybe just paid attention to sound more than most people did — but, back in Austin, she hadn’t been able to make out what her parents were saying in their bedroom when she was in her own room. She could do it here, though.

“I don’t know about this,” her mother said, her voice muffled. “Remember what it was like? Going to doctor after doctor. I don’t know if she can take another disappointment.”

“It’s been six years since the last time,” her dad said; his lower-pitched voice was harder to hear.

“And she’s just started a new school — and a regular school, at that. We can’t take her out of classes for some wild goose chase.”

Caitlin was worried about missing classes, too — not because she was concerned about falling behind but because she sensed that the cliques and alliances for the year were already forming and, so far, after two months in Waterloo, she’d made only one friend. The Texas School for the Blind took students from kindergarten through the end of high school; she’d been with the same cohort most of her life, and she missed her old friends fiercely.

“This Kuroda says the implant can be put in under a local anesthetic,” she heard her dad say. “It’s not a major operation; she won’t miss much school.”

“But we’ve tried before—”

“Technology changes rapidly, exponentially.”