"What machine?" Kate said.
"Sue's machine."
"But she hasn't left yet."
"I know," he said. "It doesn't seem to make sense. Quantum events are all counterintuitive."
"You're saying you get an indicator that she is returning before she has left?"
"Yes."
"Why?" Kate said.
Gordon sighed. "It's complicated. Actually, what we are seeing in the field is a probability function - the likelihood that a machine is going to return. We don't usually think about it that way. We just say it's coming back. But to be accurate, a field buck is really telling us that it is highly probable a machine is coming back."
Kate was shaking her head. "I don't get it."
Gordon said, "Let's just say that in the ordinary world, we have beliefs about cause and effect. Causes occur first, effects second. But that order of events does not always occur in the quantum world. Effects can be simultaneous with causes, and effects can precede causes. This is one minor example of that."
The woman, Gomez, stepped into one of the machines. She pushed the white wafer into a slot in the base in front of her. "She's just installed her nav marker, which guides the machine out and back."
"And how do you know you'll get back?" Stern said.
"A multiverse transfer," Gordon said, "creates a sort of potential energy, like a stretched spring that wants to snap back. So the machines can come home relatively easily. Outbound is the tricky part. That's what's encoded in the ceramic."
He leaned forward to press an intercom button. "Sue? How long are you gone?"
"I'll be a minute, maybe two."
"Okay. Synch elapsed."
Now the technicians began to talk, flipping switches at a console, looking at video readouts in front of them.
"Helium check."
"Read as full," a technician said, looking at her console.
"EMR check."
"Check."
"Stand by for laser alignment."
One of the technicians flipped a switch, and from the metal strips, a dense array of green lasers fired into the center of the machine, putting dozens of green spots on Gomez's face and body as she stood still, her eyes closed.
The bars began to revolve slowly. The woman in the center remained still. The lasers made green horizontal streaks over her body. Then the bars stopped.
"Lasers aligned."
Gordon said, "See you in a minute, Sue." He turned to the others. "Okay. Here we go."
The curved water shields around the cage began to glow a faint blue. Once again the machine began to rotate slowly. The woman in the center stood motionless; the machine moved around her.
The humming grew louder. The rotation increased in speed. The woman stood, calm and relaxed.
"For this trip," Gordon said, "she'll use up only a minute or two. But she actually has thirty-seven hours in her battery cells. That's the limit these machines can remain in a location without returning."
The bars were spinning swiftly. They now heard a rapid chattering sound, like a machine gun.
"That's the clearance check: infrared sensors verify the space around the machine. They won't proceed without two meters on all sides. They check both ways. It's a safety measure. We wouldn't want the machine emerging in the middle of a stone wall. All right. They're releasing xenon. Here she goes."
The humming was now very loud. The enclosure spun so rapidly, the metal strips were blurred. They could see the woman inside quite clearly.
They heard a recorded voice say, "Stand still - eyes open - deep breath - hold it. . . . Now!"
From the top of the machine, a single ring descended, scanning quickly to her feet.
"Now watch closely. It's fast," Gordon said.
Kate saw deep violet lasers fire inward from all the bars toward the center. The woman inside seemed to glow white-hot for an instant, and then a burst of blinding white light flashed inside the machine. Kate closed her eyes, turned away. When she looked back again, there were spots in front of her eyes, and for a moment she couldn't see what had happened. Then she realized that the machine was smaller. It had pulled away from the cables at the top, which now dangled free.
Another laser flash.
The machine was smaller. The woman inside was smaller. She was now only about three feet high, and shrinking before their eyes in a series of bright laser flashes.
"Jesus," Stern said, watching. "What does that feel like?"
"Nothing," Gordon said. "You don't feel a thing. Nerve conduction time from skin to brain is on the order of a hundred milliseconds. Laser vaporization is five nanoseconds. You're long gone."
"But she's still there."
"No, she's not. She was gone in the first laser burst. The computer's just processing the data now. What you see is an artifact of compression stepping. The compression's about three to the minus two. . . ."
There was another bright flash. The cage now shrank rapidly. It was three feet high, then two. Now it was close to the floor - less than a foot tall. The woman inside looked like a little doll in khakis.
"Minus four," Gordon said. There was another bright burst, near the floor. Now Kate couldn't see the cage at all.
"What happened to it?"
"It's there. Barely."
Another burst, this time just a pinpoint flash on the floor.
"Minus five."
The flashes came more quickly now, winking like a firefly, diminishing in strength. Gordon counted them out.
"And minus fourteen. . . . Gone."