I told Snowbird about it. “I met Dr. Oswald,” she said. “I breathed for him.” Oz had spent some time in the Martian city, measuring the metabolism of the various families.

“I miss him,” I said. “He was one of my closest friends.” He and Josie might have been on this expedition if the Corporation hadn’t been pressured into taking three military people.

“It is difficult for us to gauge human personality. But I can understand why you would like Dr. Oz. He is interested in everything. Or should I say ‘was,’ as you did? He will not live long enough to see us again.”

“I should have said ‘is.’ As long as the person is alive.”

“He told me about Norway,” she said, “where he studied art. I’d like to go there someday. It sounds a little like Mars.”

“Maybe they’ll do something about the gravity by then.”

“I hope so. This is nice.” She pushed up gently, rose to the ceiling, and floated back down. “But you are joking.”

“Yes. Gravity’s like death and taxes. Always with us.”

“Not always. There’s no gravity here, nor death, nor taxes. Not for some time. And when we take off for Wolf 25, it will be the ship’s acceleration that presses us to the floor.”

“Homemade gravity. You can’t tell it from the real thing.”

“Ha-ha. Dr. Einstein’s Principle of Equivalence. A good joke.”

Was it I who had made the joke, or Einstein? I decided not to pursue it.

Dustin came into the lounge, sideways and a little fast. He crashed into a wall with a modicum of grace.

“Good aim,” I said. “You want to work on the speed.”

He brushed himself off, rotating toward the center of the room. “Good aim if I’d been aiming for this door,” he said. “Good afternoon, Snowbird. What’s up?”

“Carmen helped us with a tree. Now we are discussing general relativity.”

That raised his eyebrows a few millimeters. “A little beyond me. The math, anyhow. Tensor calculus?”

I had to come clean. “Don’t ask me. I’m just sitting around being impressed. What is tensor calculus?”

“To me, it was a big ‘stop’ sign. I withdrew from the course and changed my major to philosophy. From physics.”

“Pretty drastic.”

“I try to be philosophical about it. Snowbird, your family is both, right? Science and philosophy?”

“Not in the sense of being scientists and philosophers, no. We don’t experiment, traditionally. Not on things and not on ideas. I am in a small group that wants to change that. Which I think is why the others were glad to see me go.

“Traditionally, you know, we learn by rote. It’s not like human physics and chemistry and biology. Things and processes are described in great detail, but those descriptions aren’t tested, and the underlying relationships aren’t studied.”

“We’d call that Aristotelianism, in a way. If you had an Aristotle.”

“I know. It was studying the ways you classify different methods of thinking that made some of us want to change the ways we think.”