“Exactly. But I had to give up that approach,” said Forward. “I was using a new method when the Institute, ah, severed our relationship.”

They must both be mad, I thought. Carlos was tied to a pillar and Forward was about to kill him, yet they were both behaving like members of a very exclusive club…to which I did not belong.

Carlos was interested. “How’d you work it?”

“You know that it is possible for an asteroid to capture a quantum black hole? In its interior? For instance, at a mass of ten to the twelfth kilograms—a billion metric tons,” he added for my benefit, “a black hole would be only one point five times ten to the minus fifth angstroms across. Smaller than an atom. In a slow pass through an asteroid it might absorb a few billions of atoms, enough to slow it into an orbit. Thereafter it might orbit within the asteroid for eons, absorbing very little mass on each pass.”

“So?”

“If I chance on an asteroid more massive than it ought to be, and if I contrive to move it, and some of the mass stays behind…”

“You’d have to search a lot of asteroids. Why do it out here? Why not the asteroid belt? Oh, of course. You can use hyperdrive out here.”

“Exactly. We could search a score of masses in a day, using very little fuel.”

“Hey. If it was big enough to eat a spacecraft, why didn’t it eat the asteroid you found it in?”

“It wasn’t that big,” said Forward. “The black hole I found was exactly as I have described it. I enlarged it. I towed it home and ran it into my neutronium sphere. Then it was large enough to absorb an asteroid. Now it is quite a massive object. Ten to the twentieth power kilograms, the mass of one of the larger asteroids, and a radius of just under ten to the minus fifth centimeters.”

There was satisfaction in Forward’s voice. In Carlos’s there was suddenly nothing but contempt. “You accomplished all that, and then you used it to rob ships and bury the evidence. Is that what’s going to happen to us? Down the rabbit hole?”

“To another universe, perhaps. Where does a black hole lead?”

I wondered about that myself.

Angel had taken Forward’s place at the control console. He had fastened the seat belt, something I had not seen Forward do, and was dividing his attention between the instruments and the conversation.

“I’m still wondering how you move it,” said Carlos. Then, “Uh! The tugs!”

Forward stared, then guffawed. “You didn’t guess that? But of course the black hole can hold a charge. I played the exhaust from an old ion drive reaction motor into it for nearly a month. Now it holds an enormous charge. The tugs can pull it well enough. I wish I had more of them. Soon I will.”