I went back into the bedroom, and watched the game for about ten minutes before I fell asleep.

When I awoke in the morning, I saw that Julia's side of the bed was still made up, her pillow uncreased. She hadn't come home last night at all. I checked the telephone messages; there were none. Eric wandered in, and saw the bed. "Where's Mom?"

"I don't know, son."

"Did she leave already?"

"I guess so…"

He stared at me, and then at the unmade bed. And he walked out of the room. He wasn't going to deal with it.

But I was beginning to think I had to. Maybe I should even talk to a lawyer. Except in my mind, there was something irrevocable about talking to a lawyer. If the trouble was that serious, it was probably fatal. I didn't want to believe my marriage was over, so I wanted to postpone seeing a lawyer.

That was when I decided to call my sister in San Diego. Ellen is a clinical psychologist, she has a practice in La Jolla. It was early enough that I figured she hadn't gone to the office yet; she answered the phone at home. She sounded surprised I had called. I love my sister but we are very different. Anyway, I told her briefly about the things I'd been suspecting about Julia, and why.

"You're saying Julia didn't come home and she didn't call?"

"Right."

"Did you call her?"

"Not yet."

"How come?"

"I don't know."

"Maybe she was in an accident, maybe she's hurt…"

"I don't think so."

"Why not?"

"You always hear if there's an accident. There's no accident."

"You sound upset, Jack."

"I don't know. Maybe."

My sister was silent for a moment. Then she said, "Jack, you've got a problem. Why aren't you doing something?"

"Like what?"

"Like see a marriage counselor. Or a lawyer."

"Oh, jeez."

"Don't you think you should?" she asked.

"I don't know. No. Not yet."

"Jack. She didn't come home last night and she didn't bother to call. When this woman drops a hint, she uses a bombsight. How much clearer do you need it to be?"

"I don't know."

"You're saying 'I don't know' a lot. Are you aware of that?"

"I guess so."

A pause. "Jack, are you all right?"

"I don't know."

"Do you want me to come up for a couple of days? Because I can, no problem. I was supposed to go out of town with my boyfriend, but his company just got bought. So I'm available, if you want me to come up."

"No. It's okay."

"You sure? I'm worried about you."

"No, no," I said. "You don't have to worry."

"Are you depressed?"

"No. Why?"

"Sleeping okay? Exercising?"

"Fair. Not really exercising that much."

"Uh-huh. Do you have a job yet?"

"No."

"Prospects?"

"Not really. No."

"Jack," she said. "You have to see a lawyer."

"Maybe in a while."

"Jack. What's the matter with you? This is what you've told me. Your wife is acting cold and angry toward you. She's lying to you. She's acting strange with the kids. She doesn't seem to care about her family. She's angry and absent a lot. It's getting worse. You think she's involved with someone else. Last night, she doesn't even show up or call. And you're just going to let this go without doing anything?"

"I don't know what to do."

"I told you. See a lawyer."

"You think so?"

"You're damn right I think so."

"I don't know…"

She sighed, a long exasperated hiss. "Jack. Look. I know you're a little passive at times, but-"

"I'm not passive," I said. And I added, "I hate it when you shrink me."

"Your wife is screwing around on you, you think she's building a case to take the kids away from you, and you're just letting it happen. I'd say that's passive."

"What am I supposed to do?"

"I told you." Another exasperated sigh. "Okay. I'm taking a couple of days and coming up to see you."

"Ellen-"

"Don't argue. I'm coming. You can tell Julia I'm going to help out with the kids. I'll be up there this afternoon."

"But-"

"Don't argue."

And she got off the phone. …

I'm not passive. I'm thoughtful. Ellen's very energetic, her personality's perfect for a psychologist, because she loves to tell people what to do. Frankly, I think she's pushy. And she thinks I'm passive.

This is Ellen's idea about me. That I went to Stanford in the late seventies, and studied population biology-a purely academic field, with no practical application, no jobs except in universities. In those days population biology was being revolutionized by field studies of animals, and by advances in genetic screening. Both required computer analysis, using advanced mathematical algorithms. I couldn't find the kind of programs I needed for my research, so I began to write them myself. And I slid sideways into computer science-another geeky, purely academic field.

But my graduation just happened to coincide with the rise of Silicon Valley and the personal-computer explosion. Low-number employees at startup companies were making a fortune in the eighties, and I did pretty well at the first one I worked for. I met Julia, and we got married, had kids. Everything was smooth. We were both doing great, just by showing up for work. I got hired away by another company; more perks, bigger options. I just rode the advancing wave into the nineties. By then I wasn't programming anymore, I was supervising software development. And things just fell into place for me, without any real effort on my part. I just fell into my life. I never had to prove myself.

That's Ellen's idea of me. My idea is different. The companies of Silicon Valley are the most intensely competitive in the history of the planet. Everybody works a hundred hours a week. Everybody is racing against milestones. Everybody is cutting development cycles. The cycles were originally three years to a new product, a new version. Then it was two years. Then eighteen months. Now it was twelve months-a new version every year. If you figure beta debugging to golden master takes four months, then you have only eight months to do the actual work. Eight months to revise ten million lines of code, and make sure it all works right. In short, Silicon Valley is no place for a passive person, and I'm not one. I hustled my ass off every minute of every day. I had to prove myself every day-or I'd be gone. That was my idea about myself. I was sure I was right.

Ellen was right about one part, though. A strong streak of luck ran through my career. Because my original field of study had been biology, I had an advantage when computer programs began to explicitly mimic biological systems. In fact, there were programmers who shuttled back and forth between computer simulation and studies of animal groups in the wild, applying the lessons of one to the other.

But further, I had worked in population biology-the study of groups of living organisms. And computer science had evolved in the direction of massively parallel networked structures-the programming of populations of intelligent agents. A special kind of thinking was required to handle populations of agents, and I had been trained in that thinking for years. So I was admirably suited to the trends of my field, and I made excellent progress as the fields emerged. I had been in the right place at the right time.

That much was true.

Agent-based programs that modeled biological populations were increasingly important in the real world. Like my own programs that mimicked ant foraging to control big communications networks. Or programs that mimicked division of labor among termite colonies to control thermostats in a skyscraper. And closely related were the programs that mimicked genetic selection, used for a wide range of applications. In one program, witnesses to a crime were shown nine faces and asked to choose which was most like the criminal, even if none really were; the program then showed them nine more faces, and asked them to choose again; and from many repeated generations the program slowly evolved a highly accurate composite picture of the face, far more accurate than any police artist could make. Witnesses never had to say what exactly they were responding to in each face; they just chose, and the program evolved.