Silver motioned him forward. As they walked, Lash looked curiously at the rooms to the left and right. He noticed a large personal gym, complete with exercise flume, weight machines, and treadmill; a spartan dining room. The hallway ended in a black door, a scanner set beside it. Silver put his wrist beneath the scanner, and for the first time Lash noticed that he, too, wore a security bracelet. The door sprang open.

The room beyond was almost as dimly lit as the corridor. Except here, the light came solely from tiny winking lights and dozens of vacuum-fluorescent displays. From all sides came a constant low rush of air: the sound of innumerable fans, breathing in unison. Rack-mounted equipment of all kinds — routers, RAID hard disc arrays, video renderers, countless other exotica unknown to Lash — covered the nearest walls. Opposite them, half a dozen terminals and their keyboards were lined up on a long wooden desk, crowded together. A lone chair sat before them. The only other piece of furniture was in a far corner: a narrow and very curious-looking couch, contoured almost in the fashion of a dentist’s chair, sat behind a screen of Plexiglas. Several leads snaked away from the chair to a nearby rack of diagnostic equipment. A lavalier-style microphone was pinned to the chair by a plastic clip.

“Please excuse the lack of seats,” Silver said. “Nobody but me ever comes here.”

“What is all this?” Lash said, looking around.

“Liza.”

Lash looked at Silver quickly. “But I saw Liza the other day. The small terminal you showed me.”

“That’s Liza, too. Liza’s everywhere in this penthouse. For some things I use that terminal you saw. This is for more complicated matters. When I need to access her directly.”

Lash remembered what Tara Stapleton had said over lunch in the cafeteria: We never get near the core routines or intelligence. Only Silver has access. Everybody else uses the corporate computer grid. He looked around at the electronics surrounding them on all sides. “Why don’t you tell me a little more about Liza?”

“What would you like to know?”

“You could start with the name.”

“Of course.” Silver paused. “By the way, speaking of names, I finally remembered where I saw yours.”

Lash raised his eyebrows.

“It was in the Times a couple years back. Weren’t you an intended victim in that string of—”

“That’s right.” Lash realized immediately he’d interrupted too quickly. “Remarkable memory.”

There was a brief silence.

“Anyway, about Liza’s name. It’s a nod to ‘Eliza,’ a famous piece of software from the early sixties. Eliza simulated a dialogue between a person and the computer, in which the program seized on words typed in by the person running it. ‘How are you feeling?’ the program would start out asking. ‘I feel lousy,’ you might type in. ‘Why do you think you feel lousy?’ the program would respond. ‘Because my father is ill,’ you’d type. ‘Why do you say that about your father?’ comes the reply. It was very primitive, and it often gave ludicrous responses, but it showed me what I needed to do.”

“And what was that?”

“To accomplish what Eliza only pretended to do. To create a program—‘program’ isn’t really the right word — a data construct that could interact flawlessly with a human being. That could, at some level, think.”

“That’s all?” Lash said.

It was meant as a joke, but Silver’s response was serious. “It’s still a work in progress. I’ll probably devote the rest of my life to perfecting it. But once the intelligence models were fully functional within a computational hyperspace—”

“A what?”

Silver smiled shyly. “Sorry. In the early days of AI, everybody thought it was just a matter of time until the machines would be able to think for themselves. But it turned out the littlest things were the hardest to implement. How can you program a computer to understand how somebody is feeling? So in graduate school I proposed a two-fold solution. Give a computer access to a huge amount of information — a knowledge base — along with the tools to search that knowledge base intelligently. Second, model as real a personality as possible within silicon and binary code, because human curiosity would be necessary to make use of all that information. I felt if I could synthesize these two elements, I’d create a computer that could teach itself to learn. And if it could learn, it could learn to respond like a human. Not to feel, of course. But it would understand what feeling was.”

Silver spoke quietly, but his voice carried the conviction of a preacher at a camp meeting.

“I guess, since we’re standing here atop your private skyscraper, you succeeded,” Lash replied.

Silver smiled again. “For years I was stymied. It seemed I could take machine learning only so far and no farther. It turned out I was just too impatient. The program was learning, only very slowly in the beginning. And I needed more horsepower than the old mainframes I could afford in those days. Suddenly, computers got cheaper. And then came the ARPAnet. That’s when her learning really accelerated.” He shook his head. “I’ll never forget watching as she made her first forays over the ’Net, searching — without any help from me — for answers to a problem set. I think she was as proud as I was.”

“Proud,” Lash repeated. “Do you mean to say that it’s conscious? Self-aware?”

“She’s definitely self-aware. Whether she’s conscious or not gets into a philosophical area I’m not prepared to address.”

“But she is self-aware. So what, exactly, is she aware of? She knows she’s a computer, that she’s different. Right?”

Silver shook his head. “I never added any module of code to that effect.”

“What?” Lash said in surprise.

“Why should she think she’s any different than us?”

“I just assumed—”

“Does a child, no matter how precocious, ever doubt the reality of its existence? Do you?”

Lash shook his head. “But we’re talking about software and hardware here. That sounds like a false syllogism to me.”

“There’s no such thing in AI. Who’s to say when programming stops and consciousness begins? A famous scientist once referred to humans as ‘meat machines.’ Are we the better for it? Besides, there’s no test you can take to prove you’re not a program, wandering around in cyberspace. What’s your proof?”

Silver had been speaking with a passion Lash hadn’t seen before. Suddenly he stopped. “Sorry,” he said, laughing shyly. “I guess I think about these things a lot more than I talk about them. Anyway, back to Liza’s architecture. She employs a very advanced form of a neural network — a computer architecture based on how the human brain works. Regular computers are constrained to two dimensions. But a neural net is arranged in three: rings inside rings inside rings. So you can move data in an almost infinite number of directions, not just along a single circuit.” Silver paused. “It’s a lot more complicated than that, of course. To ramp up her problem-solving capability, I employed swarm intelligence. Large functions are broken up into tiny, discrete data agents. That’s what allows her to solve such profound challenges, so quickly.”

“Does she know we’re here?”

Silver nodded toward a video monitor set high in one wall. “Yes. But her processing isn’t currently focused on us.”

“Earlier, you said you needed to access Liza directly for complicated work. Such as?”

“A variety of things. She runs scenarios, for example, that I monitor.”

“What kinds of scenarios?”

“All kinds. Problem-solving. Role-playing. Survival games. Things that stimulate creative thinking.” Silver hesitated. “I also use direct access for more difficult, personal tasks like software updates. But it would probably be easier just to show you.”

He walked across the room, slid open the Plexiglas panel, and took a seat in the sculpted chair. Lash watched as he fixed electrodes to his temples. A small keypad and stylus were set into one arm of the chair; a hat switch was mounted on the other. Reaching overhead, Silver pulled down a flat panel monitor, fixed to a telescoping arm. His left hand began moving over the keypad.