“Hello, mate. How did you get yourself in there?”

“Let’s just say it wasn’t easy,” he said gnomically.

“What are you doing?”

“Saving the future.”

“We can’t get him out,” Rosa said to me. “The cleft is too narrow. We haven’t been able to find the way he got in — presumably from above. We might get one or two people in from the front, but they could never get behind him to bring him out. And besides, we’re afraid he might harm them.”

I frowned. “Harm them? Harm them how? You think he’s sitting in there with a revolver?”

Rosa said heavily, “Remember San Jose.”

“Look, Rosa, I don’t know why he’s got himself stuck in a hole in the rock. But I can’t see what harm he can do you in there. I mean, all you have to do is wait a few hours, or days even, and you’ll starve him out. In fact you might have to if you want him to get through that gap.”

“This isn’t funny, George.”

“Isn’t it?” I felt a little light-headed.

“Talk to him. You say he’s your friend. Fine. Find out what he’s doing here, what he wants, what he intends. And then find a way to resolve this situation. Because if you don’t, I will.”

I tried to read her. “Will you call the police? … You won’t, will you? Or the FBI, or Interpol. You don’t want to bring them here into the Crypt, despite the danger you perceive. What are you planning, Rosa?”

She said evenly, “I’m responsible for the safety of the Crypt. As is every member of the Order. I will do whatever it takes, at whatever cost, to ensure that safety. I suggest you make sure it doesn’t come to that.” In the gloom her face was hard, set — almost fanatical — I thought she had never looked less like me, or my parents.

I nodded, chilled. “I believe you.”

I approached Peter’s wall again.

“Don’t listen to her,” he said. “Don’t let her whisper in your ear.”

“Or overwhelm me with chimp pant-hoots or pheromones? …”

“George, just get out of here.”

“Why?”

“It doesn’t concern you. Just get away—”

“Of course it concerns me. That’s my sister, standing over there. But that’s not why I’m staying, Peter.”

“Then why?”

“For you, you arsehole.”

He laughed, sardonic. “I didn’t see you once in twenty years.”

“But you were a good friend to my dad. Even if I didn’t know about it until too late.”

Silence for a while. When he spoke again, his tone was softer. “Okay, then. Do what you like. Arsehole yourself.”

“Yes … Peter, we need to talk.”

“About—”

“About San Jose.”

He hesitated. “So you know about that.”

“Interpol send their best. Peter, what happened over there?”

He sighed noisily. “You really want to know?”

“Tell me.”

“I warn you now we will have to discuss black holes. Because that’s what they were trying to build in that lab.”

Even now, more spooky stuff. “Oh, for God’s sake …”

The drones, unaware of the odd grammar of our relationship, stirred, baffled, nervous.

Peter began to describe “geometric optics.” “A black hole is a space-time flaw, a hole out of which nothing can escape, not even light. Black holes suck in light through having ultrapowerful gravity fields …”

Black holes in nature are formed by massive collapsed stars, or by aggregates of matter at the centers of galaxies like ours — or they may have been formed in the extreme pressures of the Big Bang, the most tremendous crucible of all. It used to be thought that black holes, even microscopic ones, would be so massive and would require such immense densities that to make or manipulate them was forever beyond human reach.

But that wisdom, said George, had turned out to be false. “Light is the fastest thing in the universe — as far as we know — which is why it takes the massive gravity of a black hole to capture it. But if light were to move more slowly, then a more feeble trap might do the job.”

Tense, with the gazes of the drones boring into me, I took the bait. “Fine. How can you slow down light?”

“Anytime light passes through a medium it is slowed from its vacuum speed. Even in water it is slowed by about a quarter — still bloody fast, but that’s enough to give you refraction effects.”

Memories of O-level physics swam into my mind. “Like the way a stick in a stream will seem bent—”

“Yes. But in the lab you can do a lot better. Pass light through a vapor of certain types of atom and you’re down to a few feet per second. And if you use a Bose-Einstein condensate—”

“A what?”

He hesitated. “Supercold matter. All the atoms line up, quantum-mechanically … It doesn’t matter. The point is, light can be slowed to below walking pace. I saw the trials in that lab in San Jose. It’s really quite remarkable.”

“And then you can make your black hole.”

“You can blow your slow-moving light around — even make it move backward. Photons, thrown around like paper planes in a Texas twister. To make a black hole you set up a vortex in your medium — a whirlpool. You just pull out the plug. And if the vortex walls are moving faster than your light stream, the light gets sucked into the center and can’t escape, and you have your black hole.”

“That’s what these Californians were doing?”

“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 …”