They continued down the road for several more miles. They came to a prominent green-and-white highway sign that read ITC BLACK ROCK LABORATORY. The Land Cruiser turned right, heading up a twisting road into the forested hills.

From the back seat, Stern said, "You told us before that you can connect to other universes."

"Yes."

"Through quantum foam."

"That's right."

"But that doesn't make any sense," Stern said.

"Why? What is quantum foam?" Kate said, stifling a yawn.

"It's a remnant of the birth of the universe," Stern said. He explained that the universe had begun as a single, very dense pinpoint of matter. Then, eighteen billion years ago, it exploded outward from that pinpoint - in what was known as the big bang.

"After the explosion, the universe expanded as a sphere. Except it wasn't an absolutely perfect sphere. Inside the sphere, the universe wasn't absolutely homogeneous homogeneous - which is why we now have galaxies clumped and clustered irregularly in the universe, instead of being uniformly distributed. Anyway, the point is, the expanding sphere had tiny, tiny imperfections in it. And the imperfections never got ironed out. They're still a part of the universe."

"They are? Where?"

"At subatomic dimensions. Quantum foam is just a way of saying that at very small dimensions, space-time has ripples and bubbles. But the foam is smaller than an individual atomic particle. There may or may not be wormholes in that foam."

"There are," Gordon said.

"But how could you use them for travel? You can't put a person through a hole that small. You can't put anything through it."

"Correct," Gordon said. "You also can't put a piece of paper through a telephone line. But you can send a fax."

Stern frowned. "That's entirely different."

"Why?" Gordon said. "You can transmit anything, as long as you have a way to compress and encode it. Isn't that so?"

"In theory, yes," Stern said. "But you're talking about compressing and encoding the information for an entire human being."

"That's right."

"That can't be done."

Gordon was smiling, amused now. "Why not?"

"Because the complete description of a human being - all the billions of cells, how they are interconnected, all the chemicals and molecules they contain, their biochemical state - consists of far too much information for any computer to handle."

"It's just information," Gordon said, shrugging.

"Yes. Too much information."

"We compress it by using a lossless fractal algorithm."

"Even so, it's still an enormous-"

"Excuse me," Chris said. "Are you saying you compress a person?"

"No. We compress the information equivalent of a person."

"And how is that done?" Chris said.

"With compression algorithms - methods to pack data on a computer, so they take up less space. Like JPEG and MPEG for visual material. Are you familiar with those?"

"I've got software that uses it, but that's it."

"Okay," Gordon said. "All compression programs work the same way. They look for similarities in data. Suppose you have a picture of a rose, made up of a million pixels. Each pixel has a location and a color. That's three million pieces of information - a lot of data. But most of those pixels are going to be red, surrounded by other red pixels. So the program scans the picture line by line, and sees whether adjacent pixels are the same color. If they are, it writes an instruction to the computer that says make this pixel red, and also the next fifty pixels in the line. Then switch to gray, and make the next ten pixels gray. And so on. It doesn't store information for each individual point. It stores instructions for how to re-create the picture. And the data is cut to a tenth of what it was."

"Even so," Stern said, "you're not talking about a two-dimensional picture, you're talking about a three-dimensional living object, and its description requires so much data-"

"That you'd need massive parallel processing," Gordon said, nodding. "That's true."

Chris frowned. "Parallel processing is what?"

"You hook several computers together and divide the job up among them, so it gets done faster. A big parallel-processing computer would have sixteen thousand processors hooked together. For a really big one, thirty-two thousand processors. We have thirty-two billion processors hooked together."

"Billion?" Chris said.

Stern leaned forward. "That's impossible. Even if you tried to make one…" He stared at the roof of the car, calculating. "Say, allow one inch between motherboards… that makes a stack… uh… two thousand six hundred. .. that makes a stack half a mile high. Even reconfigured into a cube, it'd be a huge building. You'd never build it. You'd never cool it. And it'd never work anyway, because the processors would end up too far apart."

Gordon sat and smiled. He was looking at Stern, waiting.

"The only possible way to do that much processing," Stern said, "would be to use the quantum characteristics of individual electrons. But then you'd be talking about a quantum computer. And no one's ever made one."

Gordon just smiled.

"Have they?" Stern said.

"Let me explain what David is talking about," Gordon said to the others. "Ordinary computers make calculations using two electron states, which are designated one and zero. That's how all computers work, by pushing around ones and zeros. But twenty years ago, Richard Feynman suggested it might be possible to make an extremely powerful computer using all thirty-two quantum states of an electron. Many laboratories are now trying to build these quantum computers. Their advantage is unimaginably great power - so great that you can indeed describe and compress a three-dimensional living object into an electron stream. Exactly like a fax. You can then transmit the electron stream through a quantum foam wormhole and reconstruct it in another universe. And that's what we do. It's not quantum teleportation. It's not particle entanglement. It's direct transmission to another universe."

The group was silent, staring at him. The Land Cruiser came into a clearing. They saw a number of two-story buildings, brick and glass. They looked surprisingly ordinary. This could be any one of those small industrial parks found on the outskirts of many American cities. Marek said, "This is ITC?"

"We like to keep a low profile," Gordon said. "Actually, we chose this spot because there is an old mine here. Good mines are getting hard to find now. So many physics projects require them."

Off to one side, working in the glare of floodlights, several men were getting ready to launch a weather balloon. The balloon was six feet in diameter, pale white. As they watched, it moved swiftly up into the sky, a small instrument bundle hanging beneath. Marek said, "What's that about?"

"We monitor the cloud cover every hour, especially when it's stormy. It's an ongoing research project, to see if the weather is the cause of any interference."

"Interference with what?" Marek asked.

The car pulled up in front of the largest building. A security guard opened the door. "Welcome to ITC," he said with a big smile. "Mr. Doniger is waiting for you."

Doniger walked quickly down the hallway with Gordon. Kramer followed behind. As he walked, Doniger scanned a sheet of paper that listed everybody's names and backgrounds. "How do they look, John?"

"Better than I expected. They're in good physical shape. They know the area. They know the time period."

"And how much persuading will they need?"

"I think they're ready. You just have to be careful talking about the risks."

"Are you suggesting I should be less than entirely honest?" Doniger said.

"Just be careful how you put it," Gordon said. "They're very bright."

"Are they? Well, let's have a look."