“They were getting there,” Peter said. “They hit practical problems. The condensate is a quantum structure, and it doesn’t respond well to being spun around . . . But all this was fixable, in principle.”

“Why would anybody want to do this?”

“That’s obvious. Quantum gravity,” he said.

“Of course,” I said. I actually had to keep from laughing. I was talking to a crack in the wall, watched by ten differently evolved hive-mind drones and my own long-lost sister. “You know, on any other day this conversation would seem bizarre.”

“Pay attention, double-oh seven,” he said wearily.

Quantum gravity, it seems, is the Next Big Thing in physics. The two great theories of twentieth-century physics were quantum mechanics, which describes the very small, like atomic structures, and general relativity, which describes the very large, like the universe itself. They are both successful, but they don’t fit together.

“The universe today is kind of separated out,” said Peter. “Large and small don’t interact too much—which is why quantum mechanics and relativity work so well. You don’t find many places in nature where they overlap, where you can study quantum gravity effects, the predictions of a unified theory. But the Black Hole Kit would be a tabletop gravity field. The San Jose people hoped, for instance, to explore whether space-time itself is quantized, broken into little packets, as light is, as matter is.”

I said heavily, “What I don’t understand is why all this should cost anybody her life. How do you justify it, Peter? Omelettes and eggs?”

“You know I don’t think like that, George.”

“Then tell me why that lab was destroyed.”

“You already know.”

“Tell me anyhow.”

“Because of the future. Humankind’s future. And because of the war in Heaven.”

All this was so like our bullshit sessions in the park by the Forum. I could imagine his earnest face as he spoke, that big jaw, the small mouth, the beads of sweat on his brow, the half-closed eyes. But Rosa was watching me, skeptical, drawing her own conclusions, no doubt, about Peter’s sanity. She twirled her finger. Hurry it up.

He reminded me of what he had told me, of SETI, the search for extraterrestrial life, and attempts to signal to it.

“Most of it was absurd,” he whispered. “Quixotic. Like the plaques stuck on the side of Pioneer space probes. They will fail through sheer statistics, because the chance of any sentient being picking up such objects is minuscule. We are surrounded by that tremendous unintentional ripple of radio noise, spreading out everywhere at lightspeed—nothing we can do about that now . . . But then, most perniciously, some signaling has been intentional, and designed to succeed. Such as using the big antenna at Arecibo to throw digital signals at the nearest stars . . .”

“Pernicious?”