A few were in the Quicksilver Group. Others were among the colony worlds, especially on Jinx, trying to get the Institute of Knowledge to finance various projects, such as more expeditions to the collapsar in Cygnus.

“Are you still with the Institute, Doctor?”

Forward shook his head. “They stopped backing me. Not enough results. But I can continue to use this station, which is Institute property. One day they’ll sell it, and we’ll have to move.”

“I was wondering why they sent you here in the first place,” said Carlos. “Sirius has an adequate cometary belt.”

“But Sol is the only system with any kind of civilization this far from its sun. And I can count on better men to work with. Sol system has always had its fair share of cosmologists.”

“I thought you might have come to solve an old mystery. The Tunguska meteorite. You’ve heard of it, of course.”

Forward laughed. “Of course. Who hasn’t? I don’t think we’ll ever know just what it was that hit Siberia that night. It may have been a chunk of antimatter. I’m told that there is antimatter in known space.”

“If it was, we’ll never prove it,” Carlos admitted.

“Shall we discuss your problem?” Forward seemed to remember my existence. “Shaeffer, what does a professional pilot think when his hyperdrive motor disappears?”

“He gets very upset.”

“Any theories?”

I decided not to mention pirates. I wanted to see if Forward would mention them first. “Nobody seems to like my theory,” I said, and I sketched out the argument for monsters in hyperspace.

Forward heard me out politely. Then, “I’ll give you this; it’d be hard to disprove. Do you buy it?”

“I’m afraid to. I almost got myself killed once, looking for space monsters when I should have been looking for natural causes.”

“Why would the hyperspace monsters eat only your motor?”

“Um…futz. I pass.”

“What do you think, Carlos? Natural phenomena or space monsters?”

“Pirates,” said Carlos.

“How are they going about it?”

“Well, this business of a hyperdrive motor disappearing and leaving the ship behind—that’s brand new. I’d think it would take a sharp gravity gradient with a tidal effect as strong as that of a neutron star or a black hole.”

“You won’t find anything like that anywhere in human space.”

“I know.” Carlos looked frustrated. That had to be faked. Earlier he’d behaved as if he already had an answer.

Forward said, “I don’t think a black hole would have that anyway. If it did, you’d never know it, because the ship would disappear down the black hole.”

“What about a powerful gravity generator?”