"Daddy?"

"Yes, Brigid," I reply in a distracted voice. I am driving home from Louisville, Kentucky, with my daughter. It is late, maybe eight o'clock, and the sun has been down for over an hour. Headlights flash past on the interstate. The radio plays. Brigid has been sitting silently in the darkness beside me. We have an hour of driving ahead of us. Tomorrow I have a lot to do.

"Can you tell me about the Big Bang?"

I nearly laugh, but the sincerity of the question breaks me out of my driving fog. I glance at her. Light stretches across her cheeks, and her eyes glitter with headlight reflection. She is eight years old, and already she knows how to ask questions that will get my attention. How do you describe the Big Bang to an eight-year-old?

I need, I realize, a baseline.

"Why don't you tell me what you know, first. Then I'll fill in the rest."

A smile. She proceeds to describe a ball of "stuff" that was all together, then exploded. Then she explains that all the material in the ball became stars and planets. She uses more detail than that. I wish I could remember everything she said. But she pulls together information from our trip to Washington, D.C., this year and patches together this story of the origins of the universe as we know it.

Inside, my heart pounds. Brigid knew. How could she know so much? How could she soak up so much in such a short period? How could she make the leaps she had made and be so correct? For a moment I don't say anything.

"What else can you tell me?" she asks.

"Well," I say, trying to find a way to say she knows it all. After all, I'm certainly not going to try to explain quantum physics to an eight-year-old. No matter how damned smart she might be. "You've pretty much got it right."

Silence.

I drive, figuring that one is over.

"You don't know anything else about the Big Bang?"

I sigh. The miles roll past. What the heck, I think. I'll give it a go.

I start slow.

I explain that even scientists don't know for certain what it was like in the beginning. I talk about theories, reminding her of our science experiments of last school year. I tell her she was right, though, that the theory is that our world started as a ball of mass.

She latches onto that word. Mass. It is the right word, the scientific word. It immediately replaces "stuff" in her vocabulary. "How big of a ball was the mass?" she asks.

I have to tell her I don't know.

I hate that. Fathers are supposed to know everything when you're eight. And now I'm describing quantum physics. Sure.

I describe it as hot. We talk about hot.

"Hot enough to boil?" she asks.

I nod. "Even hotter," I reply. "So hot a person would be immediately burned up and vaporized."

She doesn't totally understand "vaporized," but realizing that it's not good, she lets it go past to focus on this topic. Pressing on, she asks more questions.

Outside, the miles slip by.

Inside, we talk about energy. We talk about time. We talk about particles, leptons and muons and quarks. She understands what I tell her. I know this because she mulls each part of our discussion over and restates things in her own terms. She pulls out pieces of stuff she learned in the Simthsonians to corroborate my story. We talk about the universe cooling, particles forming bigger particles, electrons, protons. Atoms. Molecules.

"Those make things we can actually see," I say.

"Like CHON," she replies.

I am stymied. "I don't understand CHON."

"Carbon, hydrogen, oxygen, and whatever the N stands for," Brigid replies.

I flash back to a movie we saw, again in the Smithsonian. It was in the Natural Sciences area, describing the beginning of life on earth. CHON.

"The N stands for nitrogen," I reply. I suddenly realize I have separated into two people. One of me is talking to my eight-year-old daughter, teaching. The other is marveling at the world. Unable to speak. At moments this individual takes control of me, and I almost well up with tears. This moment is powerful in ways impossible to describe.

"Do astronomers learn about all these things?" she asks.

"Yes."

"I want to be an astronomer when I grow up."

I grin. I am a mechanical engineer. My father is one also. I recently learned he actually applied to the space program when it first geared up. I love the stars.

Brigid and I continue our conversation. We talk about how people came to these conclusions. History of science. We talk about open and closed universes. We talk about black holes. Finally, as all conversations about science and the origin of the universe must, we get down to talking about God. It begins when she asks the logical question "What happened before the Big Bang?"

"No one really knows, Brigid," I reply. "Some people believe that scientists will be able to prove the existence of God, and that he started it all."

"And others don't?"

Her question makes me suddenly uncomfortable.

One of her friends does not believe in God.

Lisa, my wife, was raised in the Catholic faith. I was not. For a year or two, I went to church with her. But I do not go anymore. My lack of attendance, I realize now, confuses Brigid. I hesitate, uncertain of how much reality to let into this discussion. Uncertain of how I feel about exposing as much of myself as I might have to if I go down this path.

"You're right," I finally say. "There are people who think there is no God."

"What do you think?"

I suddenly want to hug her tight. I want to grab her and pull her into me, feeling her warmth against my chest and smelling the childhood smells that used to cling to her. But I know that even if I could hug her now, those smells would be gone. She is growing. She is no longer a baby, and will be a child for only a few more short, precious years.

"I choose to believe in God, Brigid."

"Me, too," she says. I hear the smile in her voice.

I am surprised that we have made it to Columbus already. The streetlamps shine on the highway, leading us down the exit. I look at Brigid. She is beautiful.

And I am suddenly larger inside than I can ever remember.