“The visible and invisible worlds. The visible world is the one we know, different though it may be. People like us, even if most of them are no longer primarily formed of organic material.”

“There’s no one to be seen on the plain, just like last time,” the ambassador said, straining to look.

“People haven’t needed to walk on the ground for several hundred years. See—” The captain pointed at a place in the air, where, through the dust and clouds, the ambassador saw indistinct flying objects, little more than a cluster of black dots at this distance. “—those could be planes or people. Any machine might be someone’s body. A ship in the ocean, for instance, could be a body, and the computer memory directing it might be a copy of a human brain. People generally have several bodies, one of which is like ours. And that one, although it’s the most fragile, is the most important, perhaps due to a sort of nostalgia.”

“Are we dreaming?” the ambassador murmured.

“Compared to this visible world, the invisible world is the real dream.”

“I’ve got an idea of what that might be. People don’t even use machines for bodies.”

“Right. The invisible world is stored in a supercomputer, and each individual is a program.”

The captain pointed ahead to a peak, glittering metallic blue in the sunlight, that stood alone on the horizon. “That’s a continent in the invisible world. Do you remember those little quantum memory chips from last time? It’s an entire mountain of them. You can imagine, or maybe you can’t, the capacity of that computer.”

“What sort of life is it on the inside, when people are nothing more than a collection of quantum impulses?”